Adding upstream version 3.0.5.upstream/3.0.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

113 files changed, 36767 insertions, 0 deletions

diff --git a/src/contrib/Makefile.inc b/src/contrib/Makefile.inc
new file mode 100644
index 0000000..7addce2
--- /dev/null
+++ b/src/contrib/Makefile.inc
@@ -0,0 +1,157 @@
+noinst_LTLIBRARIES += libcontrib.la
+
+libcontrib_la_CPPFLAGS = $(AM_CPPFLAGS) $(CFLAG_VISIBILITY)
+libcontrib_la_LDFLAGS  = $(AM_LDFLAGS) $(LDFLAG_EXCLUDE_LIBS)
+libcontrib_la_LIBADD   = $(pthread_LIBS)
+if USE_GNUTLS_MEMSET
+libcontrib_la_CPPFLAGS += $(gnutls_CFLAGS)
+libcontrib_la_LIBADD   += $(gnutls_LIBS)
+endif USE_GNUTLS_MEMSET
+if EMBEDDED_LIBBPF
+libcontrib_la_CPPFLAGS += $(embedded_libbpf_CFLAGS)
+libcontrib_la_LIBADD   += $(embedded_libbpf_LIBS)
+endif EMBEDDED_LIBBPF
+
+EXTRA_DIST += \
+	contrib/licenses/0BSD			\
+	contrib/licenses/BSD-3-Clause		\
+	contrib/licenses/LGPL-2.0		\
+	contrib/licenses/LGPL-2.1		\
+	contrib/libbpf/LICENSE			\
+	contrib/openbsd/LICENSE			\
+	contrib/ucw/LICENSE			\
+	contrib/url-parser/LICENSE		\
+	contrib/url-parser/README.md		\
+	contrib/dnstap/dnstap.proto
+
+libcontrib_la_SOURCES = \
+	contrib/asan.h				\
+	contrib/base32hex.c			\
+	contrib/base32hex.h			\
+	contrib/base64.c			\
+	contrib/base64.h			\
+	contrib/base64url.c			\
+	contrib/base64url.h			\
+	contrib/ctype.h				\
+	contrib/dynarray.h			\
+	contrib/files.c				\
+	contrib/files.h				\
+	contrib/getline.c			\
+	contrib/getline.h			\
+	contrib/macros.h			\
+	contrib/mempattern.c			\
+	contrib/mempattern.h			\
+	contrib/net.c				\
+	contrib/net.h				\
+	contrib/qp-trie/trie.c			\
+	contrib/qp-trie/trie.h			\
+	contrib/semaphore.c			\
+	contrib/semaphore.h			\
+	contrib/sockaddr.c			\
+	contrib/sockaddr.h			\
+	contrib/spinlock.h			\
+	contrib/string.c			\
+	contrib/string.h			\
+	contrib/strtonum.h			\
+	contrib/time.c				\
+	contrib/time.h				\
+	contrib/tolower.h			\
+	contrib/trim.h				\
+	contrib/wire_ctx.h			\
+	contrib/openbsd/siphash.c		\
+	contrib/openbsd/siphash.h		\
+	contrib/openbsd/strlcat.c		\
+	contrib/openbsd/strlcat.h		\
+	contrib/openbsd/strlcpy.c		\
+	contrib/openbsd/strlcpy.h		\
+	contrib/ucw/array-sort.h		\
+	contrib/ucw/binsearch.h			\
+	contrib/ucw/heap.c			\
+	contrib/ucw/heap.h			\
+	contrib/ucw/lists.c			\
+	contrib/ucw/lists.h			\
+	contrib/ucw/mempool.c			\
+	contrib/ucw/mempool.h			\
+	contrib/url-parser/url_parser.c		\
+	contrib/url-parser/url_parser.h		\
+	contrib/vpool/vpool.c			\
+	contrib/vpool/vpool.h
+
+if EMBEDDED_LIBBPF
+libcontrib_la_SOURCES += \
+	contrib/libbpf/include/asm/barrier.h		\
+	contrib/libbpf/include/linux/compiler.h		\
+	contrib/libbpf/include/linux/err.h		\
+	contrib/libbpf/include/linux/filter.h		\
+	contrib/libbpf/include/linux/kernel.h		\
+	contrib/libbpf/include/linux/list.h		\
+	contrib/libbpf/include/linux/overflow.h		\
+	contrib/libbpf/include/linux/ring_buffer.h	\
+	contrib/libbpf/include/linux/types.h		\
+	contrib/libbpf/include/uapi/linux/bpf_common.h	\
+	contrib/libbpf/include/uapi/linux/bpf.h		\
+	contrib/libbpf/include/uapi/linux/btf.h		\
+	contrib/libbpf/include/uapi/linux/if_link.h	\
+	contrib/libbpf/include/uapi/linux/if_xdp.h	\
+	contrib/libbpf/include/uapi/linux/netlink.h	\
+	contrib/libbpf/bpf/bpf.c			\
+	contrib/libbpf/bpf/bpf.h			\
+	contrib/libbpf/bpf/bpf_core_read.h		\
+	contrib/libbpf/bpf/bpf_endian.h			\
+	contrib/libbpf/bpf/bpf_helper_defs.h		\
+	contrib/libbpf/bpf/bpf_helpers.h		\
+	contrib/libbpf/bpf/bpf_prog_linfo.c		\
+	contrib/libbpf/bpf/bpf_tracing.h		\
+	contrib/libbpf/bpf/btf.c			\
+	contrib/libbpf/bpf/btf.h			\
+	contrib/libbpf/bpf/btf_dump.c			\
+	contrib/libbpf/bpf/hashmap.c			\
+	contrib/libbpf/bpf/hashmap.h			\
+	contrib/libbpf/bpf/libbpf.c			\
+	contrib/libbpf/bpf/libbpf.h			\
+	contrib/libbpf/bpf/libbpf_errno.c		\
+	contrib/libbpf/bpf/libbpf_internal.h		\
+	contrib/libbpf/bpf/libbpf_probes.c		\
+	contrib/libbpf/bpf/libbpf_util.h		\
+	contrib/libbpf/bpf/netlink.c			\
+	contrib/libbpf/bpf/nlattr.c			\
+	contrib/libbpf/bpf/nlattr.h			\
+	contrib/libbpf/bpf/str_error.c			\
+	contrib/libbpf/bpf/str_error.h			\
+	contrib/libbpf/bpf/xsk.c			\
+	contrib/libbpf/bpf/xsk.h
+endif EMBEDDED_LIBBPF
+
+if HAVE_LIBDNSTAP
+noinst_LTLIBRARIES += libdnstap.la
+
+libdnstap_la_CPPFLAGS = $(AM_CPPFLAGS) $(DNSTAP_CFLAGS)
+libdnstap_la_LIBADD   = $(DNSTAP_LIBS)
+
+SUFFIXES = .proto .pb-c.c .pb-c.h
+
+.proto.pb-c.c:
+	$(AM_V_GEN)@PROTOC_C@ --c_out=. -I$(srcdir) $<
+
+.proto.pb-c.h:
+	$(AM_V_GEN)@PROTOC_C@ --c_out=. -I$(srcdir) $<
+
+libdnstap_la_SOURCES = \
+	contrib/dnstap/convert.c	\
+	contrib/dnstap/convert.h	\
+	contrib/dnstap/dnstap.c		\
+	contrib/dnstap/dnstap.h		\
+	contrib/dnstap/message.c	\
+	contrib/dnstap/message.h	\
+	contrib/dnstap/reader.c		\
+	contrib/dnstap/reader.h		\
+	contrib/dnstap/writer.c		\
+	contrib/dnstap/writer.h
+
+nodist_libdnstap_la_SOURCES = \
+	contrib/dnstap/dnstap.pb-c.c	\
+	contrib/dnstap/dnstap.pb-c.h
+
+BUILT_SOURCES += $(nodist_libdnstap_la_SOURCES)
+CLEANFILES    += $(nodist_libdnstap_la_SOURCES)
+endif HAVE_LIBDNSTAP
diff --git a/src/contrib/asan.h b/src/contrib/asan.h
new file mode 100644
index 0000000..5feb2c1
--- /dev/null
+++ b/src/contrib/asan.h
@@ -0,0 +1,37 @@
+/*  Copyright (C) 2015 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/*
+ * see sanitizer/asan_interface.h in compiler-rt (LLVM)
+ */
+#ifndef __has_feature
+  #define __has_feature(feature) 0
+#endif
+#if __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
+  void __asan_poison_memory_region(void const volatile *addr, size_t size);
+  void __asan_unpoison_memory_region(void const volatile *addr, size_t size);
+  #define ASAN_POISON_MEMORY_REGION(addr, size) \
+    __asan_poison_memory_region((addr), (size))
+  #define ASAN_UNPOISON_MEMORY_REGION(addr, size) \
+    __asan_unpoison_memory_region((addr), (size))
+#else
+  #define ASAN_POISON_MEMORY_REGION(addr, size) \
+    ((void)(addr), (void)(size))
+  #define ASAN_UNPOISON_MEMORY_REGION(addr, size) \
+    ((void)(addr), (void)(size))
+#endif
diff --git a/src/contrib/base32hex.c b/src/contrib/base32hex.c
new file mode 100644
index 0000000..ad216d2
--- /dev/null
+++ b/src/contrib/base32hex.c
@@ -0,0 +1,353 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "contrib/base32hex.h"
+#include "libknot/errcode.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+
+/*! \brief Maximal length of binary input to Base32hex encoding. */
+#define MAX_BIN_DATA_LEN	((INT32_MAX / 8) * 5)
+
+/*! \brief Base32hex padding character. */
+static const uint8_t base32hex_pad = '=';
+/*! \brief Base32hex alphabet. */
+static const uint8_t base32hex_enc[] = "0123456789abcdefghijklmnopqrstuv";
+
+/*! \brief Indicates bad Base32hex character. */
+#define KO	255
+/*! \brief Indicates Base32hex padding character. */
+#define PD	 32
+
+/*! \brief Transformation and validation table for decoding Base32hex. */
+static const uint8_t base32hex_dec[256] = {
+	[  0] = KO, [ 43] = KO, ['V'] = 31, [129] = KO, [172] = KO, [215] = KO,
+	[  1] = KO, [ 44] = KO, ['W'] = KO, [130] = KO, [173] = KO, [216] = KO,
+	[  2] = KO, [ 45] = KO, ['X'] = KO, [131] = KO, [174] = KO, [217] = KO,
+	[  3] = KO, [ 46] = KO, ['Y'] = KO, [132] = KO, [175] = KO, [218] = KO,
+	[  4] = KO, [ 47] = KO, ['Z'] = KO, [133] = KO, [176] = KO, [219] = KO,
+	[  5] = KO, ['0'] =  0, [ 91] = KO, [134] = KO, [177] = KO, [220] = KO,
+	[  6] = KO, ['1'] =  1, [ 92] = KO, [135] = KO, [178] = KO, [221] = KO,
+	[  7] = KO, ['2'] =  2, [ 93] = KO, [136] = KO, [179] = KO, [222] = KO,
+	[  8] = KO, ['3'] =  3, [ 94] = KO, [137] = KO, [180] = KO, [223] = KO,
+	[  9] = KO, ['4'] =  4, [ 95] = KO, [138] = KO, [181] = KO, [224] = KO,
+	[ 10] = KO, ['5'] =  5, [ 96] = KO, [139] = KO, [182] = KO, [225] = KO,
+	[ 11] = KO, ['6'] =  6, ['a'] = 10, [140] = KO, [183] = KO, [226] = KO,
+	[ 12] = KO, ['7'] =  7, ['b'] = 11, [141] = KO, [184] = KO, [227] = KO,
+	[ 13] = KO, ['8'] =  8, ['c'] = 12, [142] = KO, [185] = KO, [228] = KO,
+	[ 14] = KO, ['9'] =  9, ['d'] = 13, [143] = KO, [186] = KO, [229] = KO,
+	[ 15] = KO, [ 58] = KO, ['e'] = 14, [144] = KO, [187] = KO, [230] = KO,
+	[ 16] = KO, [ 59] = KO, ['f'] = 15, [145] = KO, [188] = KO, [231] = KO,
+	[ 17] = KO, [ 60] = KO, ['g'] = 16, [146] = KO, [189] = KO, [232] = KO,
+	[ 18] = KO, ['='] = PD, ['h'] = 17, [147] = KO, [190] = KO, [233] = KO,
+	[ 19] = KO, [ 62] = KO, ['i'] = 18, [148] = KO, [191] = KO, [234] = KO,
+	[ 20] = KO, [ 63] = KO, ['j'] = 19, [149] = KO, [192] = KO, [235] = KO,
+	[ 21] = KO, [ 64] = KO, ['k'] = 20, [150] = KO, [193] = KO, [236] = KO,
+	[ 22] = KO, ['A'] = 10, ['l'] = 21, [151] = KO, [194] = KO, [237] = KO,
+	[ 23] = KO, ['B'] = 11, ['m'] = 22, [152] = KO, [195] = KO, [238] = KO,
+	[ 24] = KO, ['C'] = 12, ['n'] = 23, [153] = KO, [196] = KO, [239] = KO,
+	[ 25] = KO, ['D'] = 13, ['o'] = 24, [154] = KO, [197] = KO, [240] = KO,
+	[ 26] = KO, ['E'] = 14, ['p'] = 25, [155] = KO, [198] = KO, [241] = KO,
+	[ 27] = KO, ['F'] = 15, ['q'] = 26, [156] = KO, [199] = KO, [242] = KO,
+	[ 28] = KO, ['G'] = 16, ['r'] = 27, [157] = KO, [200] = KO, [243] = KO,
+	[ 29] = KO, ['H'] = 17, ['s'] = 28, [158] = KO, [201] = KO, [244] = KO,
+	[ 30] = KO, ['I'] = 18, ['t'] = 29, [159] = KO, [202] = KO, [245] = KO,
+	[ 31] = KO, ['J'] = 19, ['u'] = 30, [160] = KO, [203] = KO, [246] = KO,
+	[ 32] = KO, ['K'] = 20, ['v'] = 31, [161] = KO, [204] = KO, [247] = KO,
+	[ 33] = KO, ['L'] = 21, ['w'] = KO, [162] = KO, [205] = KO, [248] = KO,
+	[ 34] = KO, ['M'] = 22, ['x'] = KO, [163] = KO, [206] = KO, [249] = KO,
+	[ 35] = KO, ['N'] = 23, ['y'] = KO, [164] = KO, [207] = KO, [250] = KO,
+	[ 36] = KO, ['O'] = 24, ['z'] = KO, [165] = KO, [208] = KO, [251] = KO,
+	[ 37] = KO, ['P'] = 25, [123] = KO, [166] = KO, [209] = KO, [252] = KO,
+	[ 38] = KO, ['Q'] = 26, [124] = KO, [167] = KO, [210] = KO, [253] = KO,
+	[ 39] = KO, ['R'] = 27, [125] = KO, [168] = KO, [211] = KO, [254] = KO,
+	[ 40] = KO, ['S'] = 28, [126] = KO, [169] = KO, [212] = KO, [255] = KO,
+	[ 41] = KO, ['T'] = 29, [127] = KO, [170] = KO, [213] = KO,
+	[ 42] = KO, ['U'] = 30, [128] = KO, [171] = KO, [214] = KO,
+};
+
+int32_t knot_base32hex_encode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN || out_len < ((in_len + 4) / 5) * 8) {
+		return KNOT_ERANGE;
+	}
+
+	uint8_t		rest_len = in_len % 5;
+	const uint8_t	*stop = in + in_len - rest_len;
+	uint8_t		*text = out;
+
+	// Encoding loop takes 5 bytes and creates 8 characters.
+	while (in < stop) {
+		text[0] = base32hex_enc[in[0] >> 3];
+		text[1] = base32hex_enc[(in[0] & 0x07) << 2 | in[1] >> 6];
+		text[2] = base32hex_enc[(in[1] & 0x3E) >> 1];
+		text[3] = base32hex_enc[(in[1] & 0x01) << 4 | in[2] >> 4];
+		text[4] = base32hex_enc[(in[2] & 0x0F) << 1 | in[3] >> 7];
+		text[5] = base32hex_enc[(in[3] & 0x7C) >> 2];
+		text[6] = base32hex_enc[(in[3] & 0x03) << 3 | in[4] >> 5];
+		text[7] = base32hex_enc[in[4] & 0x1F];
+		text += 8;
+		in += 5;
+	}
+
+	// Processing of padding, if any.
+	switch (rest_len) {
+	case 4:
+		text[0] = base32hex_enc[in[0] >> 3];
+		text[1] = base32hex_enc[(in[0] & 0x07) << 2 | in[1] >> 6];
+		text[2] = base32hex_enc[(in[1] & 0x3E) >> 1];
+		text[3] = base32hex_enc[(in[1] & 0x01) << 4 | in[2] >> 4];
+		text[4] = base32hex_enc[(in[2] & 0x0F) << 1 | in[3] >> 7];
+		text[5] = base32hex_enc[(in[3] & 0x7C) >> 2];
+		text[6] = base32hex_enc[(in[3] & 0x03) << 3];
+		text[7] = base32hex_pad;
+		text += 8;
+		break;
+	case 3:
+		text[0] = base32hex_enc[in[0] >> 3];
+		text[1] = base32hex_enc[(in[0] & 0x07) << 2 | in[1] >> 6];
+		text[2] = base32hex_enc[(in[1] & 0x3E) >> 1];
+		text[3] = base32hex_enc[(in[1] & 0x01) << 4 | in[2] >> 4];
+		text[4] = base32hex_enc[(in[2] & 0x0F) << 1];
+		text[5] = base32hex_pad;
+		text[6] = base32hex_pad;
+		text[7] = base32hex_pad;
+		text += 8;
+		break;
+	case 2:
+		text[0] = base32hex_enc[in[0] >> 3];
+		text[1] = base32hex_enc[(in[0] & 0x07) << 2 | in[1] >> 6];
+		text[2] = base32hex_enc[(in[1] & 0x3E) >> 1];
+		text[3] = base32hex_enc[(in[1] & 0x01) << 4];
+		text[4] = base32hex_pad;
+		text[5] = base32hex_pad;
+		text[6] = base32hex_pad;
+		text[7] = base32hex_pad;
+		text += 8;
+		break;
+	case 1:
+		text[0] = base32hex_enc[in[0] >> 3];
+		text[1] = base32hex_enc[(in[0] & 0x07) << 2];
+		text[2] = base32hex_pad;
+		text[3] = base32hex_pad;
+		text[4] = base32hex_pad;
+		text[5] = base32hex_pad;
+		text[6] = base32hex_pad;
+		text[7] = base32hex_pad;
+		text += 8;
+		break;
+	}
+
+	return (text - out);
+}
+
+int32_t knot_base32hex_encode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN) {
+		return KNOT_ERANGE;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 4) / 5) * 8;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Encode data.
+	int32_t ret = knot_base32hex_encode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
+
+int32_t knot_base32hex_decode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > INT32_MAX || out_len < ((in_len + 7) / 8) * 5) {
+		return KNOT_ERANGE;
+	}
+	if ((in_len % 8) != 0) {
+		return KNOT_BASE32HEX_ESIZE;
+	}
+
+	const uint8_t	*stop = in + in_len;
+	uint8_t		*bin = out;
+	uint8_t		pad_len = 0;
+	uint8_t		c1, c2, c3, c4, c5, c6, c7, c8;
+
+	// Decoding loop takes 8 characters and creates 5 bytes.
+	while (in < stop) {
+		// Filling and transforming 8 Base32hex chars.
+		c1 = base32hex_dec[in[0]];
+		c2 = base32hex_dec[in[1]];
+		c3 = base32hex_dec[in[2]];
+		c4 = base32hex_dec[in[3]];
+		c5 = base32hex_dec[in[4]];
+		c6 = base32hex_dec[in[5]];
+		c7 = base32hex_dec[in[6]];
+		c8 = base32hex_dec[in[7]];
+
+		// Check 8. char if is bad or padding.
+		if (c8 >= PD) {
+			if (c8 == PD && pad_len == 0) {
+				pad_len = 1;
+			} else {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// Check 7. char if is bad or padding (if so, 6. must be too).
+		if (c7 >= PD) {
+			if (c7 == PD && c6 == PD && pad_len == 1) {
+				pad_len = 3;
+			} else {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// Check 6. char if is bad or padding.
+		if (c6 >= PD) {
+			if (!(c6 == PD && pad_len == 3)) {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// Check 5. char if is bad or padding.
+		if (c5 >= PD) {
+			if (c5 == PD && pad_len == 3) {
+				pad_len = 4;
+			} else {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// Check 4. char if is bad or padding (if so, 3. must be too).
+		if (c4 >= PD) {
+			if (c4 == PD && c3 == PD && pad_len == 4) {
+				pad_len = 6;
+			} else {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// Check 3. char if is bad or padding.
+		if (c3 >= PD) {
+			if (!(c3 == PD && pad_len == 6)) {
+				return KNOT_BASE32HEX_ECHAR;
+			}
+		}
+
+		// 1. and 2. chars must not be padding.
+		if (c2 >= PD || c1 >= PD) {
+			return KNOT_BASE32HEX_ECHAR;
+		}
+
+		// Computing of output data based on padding length.
+		switch (pad_len) {
+		case 0:
+			bin[4] = (c7 << 5) + c8;
+			// FALLTHROUGH
+		case 1:
+			bin[3] = (c5 << 7) + (c6 << 2) + (c7 >> 3);
+			// FALLTHROUGH
+		case 3:
+			bin[2] = (c4 << 4) + (c5 >> 1);
+			// FALLTHROUGH
+		case 4:
+			bin[1] = (c2 << 6) + (c3 << 1) + (c4 >> 4);
+			// FALLTHROUGH
+		case 6:
+			bin[0] = (c1 << 3) + (c2 >> 2);
+		}
+
+		// Update output end.
+		switch (pad_len) {
+		case 0:
+			bin += 5;
+			break;
+		case 1:
+			bin += 4;
+			break;
+		case 3:
+			bin += 3;
+			break;
+		case 4:
+			bin += 2;
+			break;
+		case 6:
+			bin += 1;
+			break;
+		}
+
+		in += 8;
+	}
+
+	return (bin - out);
+}
+
+int32_t knot_base32hex_decode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 7) / 8) * 5;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Decode data.
+	int32_t ret = knot_base32hex_decode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
diff --git a/src/contrib/base32hex.h b/src/contrib/base32hex.h
new file mode 100644
index 0000000..4a6fd8f
--- /dev/null
+++ b/src/contrib/base32hex.h
@@ -0,0 +1,104 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Base32hex implementation (RFC 4648).
+ *
+ * \note Input Base32hex string can contain a-v characters. These characters
+ *       are considered as A-V equivalent. Lower-case variant is used for encoding!
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*!
+ * \brief Encodes binary data using Base32hex.
+ *
+ * \note Output data buffer contains Base32hex text string which isn't
+ *       terminated with '\0'!
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base32hex_encode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len);
+
+/*!
+ * \brief Encodes binary data using Base32hex and output stores to own buffer.
+ *
+ * \note Output data buffer contains Base32hex text string which isn't
+ *       terminated with '\0'!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base32hex_encode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out);
+
+/*!
+ * \brief Decodes text data using Base32hex.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base32hex string!
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base32hex_decode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len);
+
+/*!
+ * \brief Decodes text data using Base32hex and output stores to own buffer.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base32hex string!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base32hex_decode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out);
diff --git a/src/contrib/base64.c b/src/contrib/base64.c
new file mode 100644
index 0000000..ab4a560
--- /dev/null
+++ b/src/contrib/base64.c
@@ -0,0 +1,272 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "contrib/base64.h"
+#include "libknot/errcode.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+
+/*! \brief Maximal length of binary input to Base64 encoding. */
+#define MAX_BIN_DATA_LEN	((INT32_MAX / 4) * 3)
+
+/*! \brief Base64 padding character. */
+static const uint8_t base64_pad = '=';
+/*! \brief Base64 alphabet. */
+static const uint8_t base64_enc[] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+/*! \brief Indicates bad Base64 character. */
+#define KO	255
+/*! \brief Indicates Base64 padding character. */
+#define PD	 64
+
+/*! \brief Transformation and validation table for decoding Base64. */
+static const uint8_t base64_dec[256] = {
+	[  0] = KO, ['+'] = 62, ['V'] = 21, [129] = KO, [172] = KO, [215] = KO,
+	[  1] = KO, [ 44] = KO, ['W'] = 22, [130] = KO, [173] = KO, [216] = KO,
+	[  2] = KO, [ 45] = KO, ['X'] = 23, [131] = KO, [174] = KO, [217] = KO,
+	[  3] = KO, [ 46] = KO, ['Y'] = 24, [132] = KO, [175] = KO, [218] = KO,
+	[  4] = KO, ['/'] = 63, ['Z'] = 25, [133] = KO, [176] = KO, [219] = KO,
+	[  5] = KO, ['0'] = 52, [ 91] = KO, [134] = KO, [177] = KO, [220] = KO,
+	[  6] = KO, ['1'] = 53, [ 92] = KO, [135] = KO, [178] = KO, [221] = KO,
+	[  7] = KO, ['2'] = 54, [ 93] = KO, [136] = KO, [179] = KO, [222] = KO,
+	[  8] = KO, ['3'] = 55, [ 94] = KO, [137] = KO, [180] = KO, [223] = KO,
+	[  9] = KO, ['4'] = 56, [ 95] = KO, [138] = KO, [181] = KO, [224] = KO,
+	[ 10] = KO, ['5'] = 57, [ 96] = KO, [139] = KO, [182] = KO, [225] = KO,
+	[ 11] = KO, ['6'] = 58, ['a'] = 26, [140] = KO, [183] = KO, [226] = KO,
+	[ 12] = KO, ['7'] = 59, ['b'] = 27, [141] = KO, [184] = KO, [227] = KO,
+	[ 13] = KO, ['8'] = 60, ['c'] = 28, [142] = KO, [185] = KO, [228] = KO,
+	[ 14] = KO, ['9'] = 61, ['d'] = 29, [143] = KO, [186] = KO, [229] = KO,
+	[ 15] = KO, [ 58] = KO, ['e'] = 30, [144] = KO, [187] = KO, [230] = KO,
+	[ 16] = KO, [ 59] = KO, ['f'] = 31, [145] = KO, [188] = KO, [231] = KO,
+	[ 17] = KO, [ 60] = KO, ['g'] = 32, [146] = KO, [189] = KO, [232] = KO,
+	[ 18] = KO, ['='] = PD, ['h'] = 33, [147] = KO, [190] = KO, [233] = KO,
+	[ 19] = KO, [ 62] = KO, ['i'] = 34, [148] = KO, [191] = KO, [234] = KO,
+	[ 20] = KO, [ 63] = KO, ['j'] = 35, [149] = KO, [192] = KO, [235] = KO,
+	[ 21] = KO, [ 64] = KO, ['k'] = 36, [150] = KO, [193] = KO, [236] = KO,
+	[ 22] = KO, ['A'] =  0, ['l'] = 37, [151] = KO, [194] = KO, [237] = KO,
+	[ 23] = KO, ['B'] =  1, ['m'] = 38, [152] = KO, [195] = KO, [238] = KO,
+	[ 24] = KO, ['C'] =  2, ['n'] = 39, [153] = KO, [196] = KO, [239] = KO,
+	[ 25] = KO, ['D'] =  3, ['o'] = 40, [154] = KO, [197] = KO, [240] = KO,
+	[ 26] = KO, ['E'] =  4, ['p'] = 41, [155] = KO, [198] = KO, [241] = KO,
+	[ 27] = KO, ['F'] =  5, ['q'] = 42, [156] = KO, [199] = KO, [242] = KO,
+	[ 28] = KO, ['G'] =  6, ['r'] = 43, [157] = KO, [200] = KO, [243] = KO,
+	[ 29] = KO, ['H'] =  7, ['s'] = 44, [158] = KO, [201] = KO, [244] = KO,
+	[ 30] = KO, ['I'] =  8, ['t'] = 45, [159] = KO, [202] = KO, [245] = KO,
+	[ 31] = KO, ['J'] =  9, ['u'] = 46, [160] = KO, [203] = KO, [246] = KO,
+	[ 32] = KO, ['K'] = 10, ['v'] = 47, [161] = KO, [204] = KO, [247] = KO,
+	[ 33] = KO, ['L'] = 11, ['w'] = 48, [162] = KO, [205] = KO, [248] = KO,
+	[ 34] = KO, ['M'] = 12, ['x'] = 49, [163] = KO, [206] = KO, [249] = KO,
+	[ 35] = KO, ['N'] = 13, ['y'] = 50, [164] = KO, [207] = KO, [250] = KO,
+	[ 36] = KO, ['O'] = 14, ['z'] = 51, [165] = KO, [208] = KO, [251] = KO,
+	[ 37] = KO, ['P'] = 15, [123] = KO, [166] = KO, [209] = KO, [252] = KO,
+	[ 38] = KO, ['Q'] = 16, [124] = KO, [167] = KO, [210] = KO, [253] = KO,
+	[ 39] = KO, ['R'] = 17, [125] = KO, [168] = KO, [211] = KO, [254] = KO,
+	[ 40] = KO, ['S'] = 18, [126] = KO, [169] = KO, [212] = KO, [255] = KO,
+	[ 41] = KO, ['T'] = 19, [127] = KO, [170] = KO, [213] = KO,
+	[ 42] = KO, ['U'] = 20, [128] = KO, [171] = KO, [214] = KO,
+};
+
+int32_t knot_base64_encode(const uint8_t  *in,
+                           const uint32_t in_len,
+                           uint8_t        *out,
+                           const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN || out_len < ((in_len + 2) / 3) * 4) {
+		return KNOT_ERANGE;
+	}
+
+	uint8_t		rest_len = in_len % 3;
+	const uint8_t	*stop = in + in_len - rest_len;
+	uint8_t		*text = out;
+
+	// Encoding loop takes 3 bytes and creates 4 characters.
+	while (in < stop) {
+		text[0] = base64_enc[in[0] >> 2];
+		text[1] = base64_enc[(in[0] & 0x03) << 4 | in[1] >> 4];
+		text[2] = base64_enc[(in[1] & 0x0F) << 2 | in[2] >> 6];
+		text[3] = base64_enc[in[2] & 0x3F];
+		text += 4;
+		in += 3;
+	}
+
+	// Processing of padding, if any.
+	switch (rest_len) {
+	case 2:
+		text[0] = base64_enc[in[0] >> 2];
+		text[1] = base64_enc[(in[0] & 0x03) << 4 | in[1] >> 4];
+		text[2] = base64_enc[(in[1] & 0x0F) << 2];
+		text[3] = base64_pad;
+		text += 4;
+		break;
+	case 1:
+		text[0] = base64_enc[in[0] >> 2];
+		text[1] = base64_enc[(in[0] & 0x03) << 4];
+		text[2] = base64_pad;
+		text[3] = base64_pad;
+		text += 4;
+		break;
+	}
+
+	return (text - out);
+}
+
+int32_t knot_base64_encode_alloc(const uint8_t  *in,
+                                 const uint32_t in_len,
+                                 uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN) {
+		return KNOT_ERANGE;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 2) / 3) * 4;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Encode data.
+	int32_t ret = knot_base64_encode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
+
+int32_t knot_base64_decode(const uint8_t  *in,
+                           const uint32_t in_len,
+                           uint8_t        *out,
+                           const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > INT32_MAX || out_len < ((in_len + 3) / 4) * 3) {
+		return KNOT_ERANGE;
+	}
+	if ((in_len % 4) != 0) {
+		return KNOT_BASE64_ESIZE;
+	}
+
+	const uint8_t	*stop = in + in_len;
+	uint8_t		*bin = out;
+	uint8_t		pad_len = 0;
+	uint8_t		c1, c2, c3, c4;
+
+	// Decoding loop takes 4 characters and creates 3 bytes.
+	while (in < stop) {
+		// Filling and transforming 4 Base64 chars.
+		c1 = base64_dec[in[0]];
+		c2 = base64_dec[in[1]];
+		c3 = base64_dec[in[2]];
+		c4 = base64_dec[in[3]];
+
+		// Check 4. char if is bad or padding.
+		if (c4 >= PD) {
+			if (c4 == PD && pad_len == 0) {
+				pad_len = 1;
+			} else {
+				return KNOT_BASE64_ECHAR;
+			}
+		}
+
+		// Check 3. char if is bad or padding.
+		if (c3 >= PD) {
+			if (c3 == PD && pad_len == 1) {
+				pad_len = 2;
+			} else {
+				return KNOT_BASE64_ECHAR;
+			}
+		}
+
+		// Check 1. and 2. chars if are not padding.
+		if (c2 >= PD || c1 >= PD) {
+			return KNOT_BASE64_ECHAR;
+		}
+
+		// Computing of output data based on padding length.
+		switch (pad_len) {
+		case 0:
+			bin[2] = (c3 << 6) + c4;
+			// FALLTHROUGH
+		case 1:
+			bin[1] = (c2 << 4) + (c3 >> 2);
+			// FALLTHROUGH
+		case 2:
+			bin[0] = (c1 << 2) + (c2 >> 4);
+		}
+
+		// Update output end.
+		switch (pad_len) {
+		case 0:
+			bin += 3;
+			break;
+		case 1:
+			bin += 2;
+			break;
+		case 2:
+			bin += 1;
+			break;
+		}
+
+		in += 4;
+	}
+
+	return (bin - out);
+}
+
+int32_t knot_base64_decode_alloc(const uint8_t  *in,
+                                 const uint32_t in_len,
+                                 uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 3) / 4) * 3;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Decode data.
+	int32_t ret = knot_base64_decode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
diff --git a/src/contrib/base64.h b/src/contrib/base64.h
new file mode 100644
index 0000000..0a98733
--- /dev/null
+++ b/src/contrib/base64.h
@@ -0,0 +1,103 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Base64 implementation (RFC 4648).
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*!
+ * \brief Encodes binary data using Base64.
+ *
+ * \note Output data buffer contains Base64 text string which isn't
+ *       terminated with '\0'!
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64_encode(const uint8_t  *in,
+                           const uint32_t in_len,
+                           uint8_t        *out,
+                           const uint32_t out_len);
+
+/*!
+ * \brief Encodes binary data using Base64 and output stores to own buffer.
+ *
+ * \note Output data buffer contains Base64 text string which isn't
+ *       terminated with '\0'!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64_encode_alloc(const uint8_t  *in,
+                                 const uint32_t in_len,
+                                 uint8_t        **out);
+
+/*!
+ * \brief Decodes text data using Base64.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base64 string!
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64_decode(const uint8_t  *in,
+                           const uint32_t in_len,
+                           uint8_t        *out,
+                           const uint32_t out_len);
+
+/*!
+ * \brief Decodes text data using Base64 and output stores to own buffer.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base64 string!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64_decode_alloc(const uint8_t  *in,
+                                 const uint32_t in_len,
+                                 uint8_t        **out);
+
+/*! @} */
diff --git a/src/contrib/base64url.c b/src/contrib/base64url.c
new file mode 100644
index 0000000..34e2bbe
--- /dev/null
+++ b/src/contrib/base64url.c
@@ -0,0 +1,287 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "contrib/base64url.h"
+#include "libknot/errcode.h"
+
+#include <stdlib.h>
+#include <stdint.h>
+#include <ctype.h>
+
+/*! \brief Maximal length of binary input to Base64url encoding. */
+#define MAX_BIN_DATA_LEN	((INT32_MAX / 4) * 3)
+
+/*! \brief Base64url padding character. */
+static const uint8_t base64url_pad = '\0';
+/*! \brief Base64 alphabet. */
+static const uint8_t base64url_enc[] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
+
+/*! \brief Indicates bad Base64 character. */
+#define KO	255
+/*! \brief Indicates Base64 padding character. */
+#define PD	 64
+
+/*! \brief Transformation and validation table for decoding Base64. */
+static const uint8_t base64url_dec[256] = {
+	[  0] = PD, [ 43] = KO, ['V'] = 21, [129] = KO, [172] = KO, [215] = KO,
+	[  1] = KO, [ 44] = KO, ['W'] = 22, [130] = KO, [173] = KO, [216] = KO,
+	[  2] = KO, ['-'] = 62, ['X'] = 23, [131] = KO, [174] = KO, [217] = KO,
+	[  3] = KO, [ 46] = KO, ['Y'] = 24, [132] = KO, [175] = KO, [218] = KO,
+	[  4] = KO, [ 47] = KO, ['Z'] = 25, [133] = KO, [176] = KO, [219] = KO,
+	[  5] = KO, ['0'] = 52, [ 91] = KO, [134] = KO, [177] = KO, [220] = KO,
+	[  6] = KO, ['1'] = 53, [ 92] = KO, [135] = KO, [178] = KO, [221] = KO,
+	[  7] = KO, ['2'] = 54, [ 93] = KO, [136] = KO, [179] = KO, [222] = KO,
+	[  8] = KO, ['3'] = 55, [ 94] = KO, [137] = KO, [180] = KO, [223] = KO,
+	[  9] = KO, ['4'] = 56, ['_'] = 63, [138] = KO, [181] = KO, [224] = KO,
+	[ 10] = KO, ['5'] = 57, [ 96] = KO, [139] = KO, [182] = KO, [225] = KO,
+	[ 11] = KO, ['6'] = 58, ['a'] = 26, [140] = KO, [183] = KO, [226] = KO,
+	[ 12] = KO, ['7'] = 59, ['b'] = 27, [141] = KO, [184] = KO, [227] = KO,
+	[ 13] = KO, ['8'] = 60, ['c'] = 28, [142] = KO, [185] = KO, [228] = KO,
+	[ 14] = KO, ['9'] = 61, ['d'] = 29, [143] = KO, [186] = KO, [229] = KO,
+	[ 15] = KO, [ 58] = KO, ['e'] = 30, [144] = KO, [187] = KO, [230] = KO,
+	[ 16] = KO, [ 59] = KO, ['f'] = 31, [145] = KO, [188] = KO, [231] = KO,
+	[ 17] = KO, [ 60] = KO, ['g'] = 32, [146] = KO, [189] = KO, [232] = KO,
+	[ 18] = KO, [ 61] = KO, ['h'] = 33, [147] = KO, [190] = KO, [233] = KO,
+	[ 19] = KO, [ 62] = KO, ['i'] = 34, [148] = KO, [191] = KO, [234] = KO,
+	[ 20] = KO, [ 63] = KO, ['j'] = 35, [149] = KO, [192] = KO, [235] = KO,
+	[ 21] = KO, [ 64] = KO, ['k'] = 36, [150] = KO, [193] = KO, [236] = KO,
+	[ 22] = KO, ['A'] =  0, ['l'] = 37, [151] = KO, [194] = KO, [237] = KO,
+	[ 23] = KO, ['B'] =  1, ['m'] = 38, [152] = KO, [195] = KO, [238] = KO,
+	[ 24] = KO, ['C'] =  2, ['n'] = 39, [153] = KO, [196] = KO, [239] = KO,
+	[ 25] = KO, ['D'] =  3, ['o'] = 40, [154] = KO, [197] = KO, [240] = KO,
+	[ 26] = KO, ['E'] =  4, ['p'] = 41, [155] = KO, [198] = KO, [241] = KO,
+	[ 27] = KO, ['F'] =  5, ['q'] = 42, [156] = KO, [199] = KO, [242] = KO,
+	[ 28] = KO, ['G'] =  6, ['r'] = 43, [157] = KO, [200] = KO, [243] = KO,
+	[ 29] = KO, ['H'] =  7, ['s'] = 44, [158] = KO, [201] = KO, [244] = KO,
+	[ 30] = KO, ['I'] =  8, ['t'] = 45, [159] = KO, [202] = KO, [245] = KO,
+	[ 31] = KO, ['J'] =  9, ['u'] = 46, [160] = KO, [203] = KO, [246] = KO,
+	[ 32] = KO, ['K'] = 10, ['v'] = 47, [161] = KO, [204] = KO, [247] = KO,
+	[ 33] = KO, ['L'] = 11, ['w'] = 48, [162] = KO, [205] = KO, [248] = KO,
+	[ 34] = KO, ['M'] = 12, ['x'] = 49, [163] = KO, [206] = KO, [249] = KO,
+	[ 35] = KO, ['N'] = 13, ['y'] = 50, [164] = KO, [207] = KO, [250] = KO,
+	[ 36] = KO, ['O'] = 14, ['z'] = 51, [165] = KO, [208] = KO, [251] = KO,
+	['%'] = KO, ['P'] = 15, [123] = KO, [166] = KO, [209] = KO, [252] = KO,
+	[ 38] = KO, ['Q'] = 16, [124] = KO, [167] = KO, [210] = KO, [253] = KO,
+	[ 39] = KO, ['R'] = 17, [125] = KO, [168] = KO, [211] = KO, [254] = KO,
+	[ 40] = KO, ['S'] = 18, [126] = KO, [169] = KO, [212] = KO, [255] = KO,
+	[ 41] = KO, ['T'] = 19, [127] = KO, [170] = KO, [213] = KO,
+	[ 42] = KO, ['U'] = 20, [128] = KO, [171] = KO, [214] = KO,
+};
+
+int32_t knot_base64url_encode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN || out_len < ((in_len + 2) / 3) * 4) {
+		return KNOT_ERANGE;
+	}
+
+	uint8_t		rest_len = in_len % 3;
+	const uint8_t	*stop = in + in_len - rest_len;
+	uint8_t		*text = out;
+
+	// Encoding loop takes 3 bytes and creates 4 characters.
+	while (in < stop) {
+		text[0] = base64url_enc[in[0] >> 2];
+		text[1] = base64url_enc[(in[0] & 0x03) << 4 | in[1] >> 4];
+		text[2] = base64url_enc[(in[1] & 0x0F) << 2 | in[2] >> 6];
+		text[3] = base64url_enc[in[2] & 0x3F];
+		text += 4;
+		in += 3;
+	}
+
+	// Processing of padding, if any.
+	switch (rest_len) {
+	case 2:
+		text[0] = base64url_enc[in[0] >> 2];
+		text[1] = base64url_enc[(in[0] & 0x03) << 4 | in[1] >> 4];
+		text[2] = base64url_enc[(in[1] & 0x0F) << 2];
+		text[3] = base64url_pad;
+		text += 3;
+		break;
+	case 1:
+		text[0] = base64url_enc[in[0] >> 2];
+		text[1] = base64url_enc[(in[0] & 0x03) << 4];
+		text[2] = base64url_pad;
+		text[3] = base64url_pad;
+		text += 2;
+		break;
+	}
+	return (text - out);
+}
+
+int32_t knot_base64url_encode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (in_len > MAX_BIN_DATA_LEN) {
+		return KNOT_ERANGE;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 2) / 3) * 4;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Encode data.
+	int32_t ret = knot_base64url_encode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
+
+int32_t knot_base64url_decode(const uint8_t  *in,
+                              uint32_t       in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len)
+{
+	// Checking inputs.
+	if (in == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// cut up to two "%3d" from the end of input
+	int pad3d = 0;
+	const uint8_t *end = in + in_len;
+	char *perc3d = "d3%d3%", *stop3d = perc3d + 6;
+	while (end != in && perc3d != stop3d && tolower(*--end) == *perc3d) {
+		if (*perc3d++ == '%') {
+			in_len -= 3;
+			pad3d++;
+		}
+	}
+
+	if (in_len > INT32_MAX || out_len < ((in_len + 3) / 4) * 3) {
+		return KNOT_ERANGE;
+	}
+
+	const uint8_t	*stop = in + in_len;
+	uint8_t		*bin = out;
+	uint8_t		pad_len = 0;
+	uint8_t		c1, c2, c3, c4;
+
+	// Decoding loop takes 4 characters and creates 3 bytes.
+	while (in < stop) {
+		// Filling and transforming 4 Base64 chars.
+		c1 =                   base64url_dec[in[0]]     ;
+		c2 =                   base64url_dec[in[1]]     ;
+		c3 = (in + 2 < stop) ? base64url_dec[in[2]] : PD;
+		c4 = (in + 3 < stop) ? base64url_dec[in[3]] : PD;
+
+		// Check 1. and 2. chars if are not padding
+		if (c1 >= PD || c2 >= PD) {
+			return KNOT_BASE64_ECHAR;
+		}
+		// Check 3. char if is bad or padding.
+		else if (c3 >= PD) {
+			if (c3 == PD) {
+				pad_len = 2;
+			} else {
+				return KNOT_BASE64_ECHAR;
+			}
+		}
+		// Check 3. char if is bad or padding.
+		else if (c4 >= PD) {
+			if (c4 == PD) {
+				pad_len = 1;
+			} else {
+				return KNOT_BASE64_ECHAR;
+			}
+		}
+
+		if (pad_len > 0 && in <= stop - 4) {
+			return KNOT_BASE64_ECHAR;
+		}
+
+		// Computing of output data based on padding length.
+		switch (pad_len) {
+		case 0:
+			bin[2] = (c3 << 6) + c4;
+			// FALLTHROUGH
+		case 1:
+			bin[1] = (c2 << 4) + (c3 >> 2);
+			// FALLTHROUGH
+		case 2:
+			bin[0] = (c1 << 2) + (c2 >> 4);
+		}
+
+		// Update output end.
+		switch (pad_len) {
+		case 0:
+			bin += 3;
+			break;
+		case 1:
+			bin += 2;
+			goto end;
+		case 2:
+			bin += 1;
+			goto end;
+		}
+
+		in += 4;
+	}
+
+end:
+	if (pad3d > pad_len) {
+		return KNOT_BASE64_ECHAR;
+	}
+	return (bin - out);
+}
+
+int32_t knot_base64url_decode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out)
+{
+	// Checking inputs.
+	if (out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Compute output buffer length.
+	uint32_t out_len = ((in_len + 3) / 4) * 3;
+
+	// Allocate output buffer.
+	*out = malloc(out_len);
+	if (*out == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	// Decode data.
+	int32_t ret = knot_base64url_decode(in, in_len, *out, out_len);
+	if (ret < 0) {
+		free(*out);
+		*out = NULL;
+	}
+
+	return ret;
+}
diff --git a/src/contrib/base64url.h b/src/contrib/base64url.h
new file mode 100644
index 0000000..ba4bb43
--- /dev/null
+++ b/src/contrib/base64url.h
@@ -0,0 +1,103 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Base64url implementation (RFC 4648).
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*!
+ * \brief Encodes binary data using Base64.
+ *
+ * \note Output data buffer contains Base64 text string which isn't
+ *       terminated with '\0'!
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64url_encode(const uint8_t  *in,
+                              const uint32_t in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len);
+
+/*!
+ * \brief Encodes binary data using Base64 and output stores to own buffer.
+ *
+ * \note Output data buffer contains Base64 text string which isn't
+ *       terminated with '\0'!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input binary data.
+ * \param in_len	Length of input data.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output string.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64url_encode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out);
+
+/*!
+ * \brief Decodes text data using Base64.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base64 string!
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ * \param out_len	Size of output buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64url_decode(const uint8_t  *in,
+                              uint32_t       in_len,
+                              uint8_t        *out,
+                              const uint32_t out_len);
+
+/*!
+ * \brief Decodes text data using Base64 and output stores to own buffer.
+ *
+ * \note Input data needn't be terminated with '\0'.
+ *
+ * \note Input data must be continuous Base64 string!
+ *
+ * \note Output buffer should be deallocated after use.
+ *
+ * \param in		Input text data.
+ * \param in_len	Length of input string.
+ * \param out		Output data buffer.
+ *
+ * \retval >=0		length of output data.
+ * \retval KNOT_E*	if error.
+ */
+int32_t knot_base64url_decode_alloc(const uint8_t  *in,
+                                    const uint32_t in_len,
+                                    uint8_t        **out);
+
+/*! @} */
diff --git a/src/contrib/ctype.h b/src/contrib/ctype.h
new file mode 100644
index 0000000..d1e9d27
--- /dev/null
+++ b/src/contrib/ctype.h
@@ -0,0 +1,193 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Locale-independent ctype functions.
+ */
+
+#pragma once
+
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+enum {
+	CT_DIGIT = 1 << 0,
+	CT_UPPER = 1 << 1,
+	CT_LOWER = 1 << 2,
+	CT_XDIGT = 1 << 3,
+	CT_PUNCT = 1 << 4,
+	CT_PRINT = 1 << 5,
+	CT_SPACE = 1 << 6,
+};
+
+static const uint8_t char_mask[256] = {
+	// 0 - 8
+	['\t'] = CT_SPACE,
+	['\n'] = CT_SPACE,
+	['\v'] = CT_SPACE,
+	['\f'] = CT_SPACE,
+	['\r'] = CT_SPACE,
+	// 14 - 31
+	[' ']  = CT_PRINT | CT_SPACE,
+
+	['!']  = CT_PRINT | CT_PUNCT,
+	['"']  = CT_PRINT | CT_PUNCT,
+	['#']  = CT_PRINT | CT_PUNCT,
+	['$']  = CT_PRINT | CT_PUNCT,
+	['%']  = CT_PRINT | CT_PUNCT,
+	['&']  = CT_PRINT | CT_PUNCT,
+	['\''] = CT_PRINT | CT_PUNCT,
+	['(']  = CT_PRINT | CT_PUNCT,
+	[')']  = CT_PRINT | CT_PUNCT,
+	['*']  = CT_PRINT | CT_PUNCT,
+	['+']  = CT_PRINT | CT_PUNCT,
+	[',']  = CT_PRINT | CT_PUNCT,
+	['-']  = CT_PRINT | CT_PUNCT,
+	['.']  = CT_PRINT | CT_PUNCT,
+	['/']  = CT_PRINT | CT_PUNCT,
+
+	['0']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['1']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['2']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['3']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['4']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['5']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['6']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['7']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['8']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+	['9']  = CT_PRINT | CT_DIGIT | CT_XDIGT,
+
+	[':']  = CT_PRINT | CT_PUNCT,
+	[';']  = CT_PRINT | CT_PUNCT,
+	['<']  = CT_PRINT | CT_PUNCT,
+	['=']  = CT_PRINT | CT_PUNCT,
+	['>']  = CT_PRINT | CT_PUNCT,
+	['?']  = CT_PRINT | CT_PUNCT,
+	['@']  = CT_PRINT | CT_PUNCT,
+
+	['A']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['B']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['C']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['D']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['E']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['F']  = CT_PRINT | CT_UPPER | CT_XDIGT,
+	['G']  = CT_PRINT | CT_UPPER,
+	['H']  = CT_PRINT | CT_UPPER,
+	['I']  = CT_PRINT | CT_UPPER,
+	['J']  = CT_PRINT | CT_UPPER,
+	['K']  = CT_PRINT | CT_UPPER,
+	['L']  = CT_PRINT | CT_UPPER,
+	['M']  = CT_PRINT | CT_UPPER,
+	['N']  = CT_PRINT | CT_UPPER,
+	['O']  = CT_PRINT | CT_UPPER,
+	['P']  = CT_PRINT | CT_UPPER,
+	['Q']  = CT_PRINT | CT_UPPER,
+	['R']  = CT_PRINT | CT_UPPER,
+	['S']  = CT_PRINT | CT_UPPER,
+	['T']  = CT_PRINT | CT_UPPER,
+	['U']  = CT_PRINT | CT_UPPER,
+	['V']  = CT_PRINT | CT_UPPER,
+	['W']  = CT_PRINT | CT_UPPER,
+	['X']  = CT_PRINT | CT_UPPER,
+	['Y']  = CT_PRINT | CT_UPPER,
+	['Z']  = CT_PRINT | CT_UPPER,
+
+	['[']  = CT_PRINT | CT_PUNCT,
+	['\\'] = CT_PRINT | CT_PUNCT,
+	[']']  = CT_PRINT | CT_PUNCT,
+	['^']  = CT_PRINT | CT_PUNCT,
+	['_']  = CT_PRINT | CT_PUNCT,
+	['`']  = CT_PRINT | CT_PUNCT,
+
+	['a']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['b']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['c']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['d']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['e']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['f']  = CT_PRINT | CT_LOWER | CT_XDIGT,
+	['g']  = CT_PRINT | CT_LOWER,
+	['h']  = CT_PRINT | CT_LOWER,
+	['i']  = CT_PRINT | CT_LOWER,
+	['j']  = CT_PRINT | CT_LOWER,
+	['k']  = CT_PRINT | CT_LOWER,
+	['l']  = CT_PRINT | CT_LOWER,
+	['m']  = CT_PRINT | CT_LOWER,
+	['n']  = CT_PRINT | CT_LOWER,
+	['o']  = CT_PRINT | CT_LOWER,
+	['p']  = CT_PRINT | CT_LOWER,
+	['q']  = CT_PRINT | CT_LOWER,
+	['r']  = CT_PRINT | CT_LOWER,
+	['s']  = CT_PRINT | CT_LOWER,
+	['t']  = CT_PRINT | CT_LOWER,
+	['u']  = CT_PRINT | CT_LOWER,
+	['v']  = CT_PRINT | CT_LOWER,
+	['w']  = CT_PRINT | CT_LOWER,
+	['x']  = CT_PRINT | CT_LOWER,
+	['y']  = CT_PRINT | CT_LOWER,
+	['z']  = CT_PRINT | CT_LOWER,
+
+	['{']  = CT_PRINT | CT_PUNCT,
+	['|']  = CT_PRINT | CT_PUNCT,
+	['}']  = CT_PRINT | CT_PUNCT,
+	['~']  = CT_PRINT | CT_PUNCT,
+	// 127 - 255
+};
+
+static inline bool is_alnum(uint8_t c)
+{
+	return char_mask[c] & (CT_DIGIT | CT_UPPER | CT_LOWER);
+}
+
+static inline bool is_alpha(uint8_t c)
+{
+	return char_mask[c] & (CT_UPPER | CT_LOWER);
+}
+
+static inline bool is_digit(uint8_t c)
+{
+	return char_mask[c] & CT_DIGIT;
+}
+
+static inline bool is_xdigit(uint8_t c)
+{
+	return char_mask[c] & CT_XDIGT;
+}
+
+static inline bool is_lower(uint8_t c)
+{
+	return char_mask[c] & CT_LOWER;
+}
+
+static inline bool is_upper(uint8_t c)
+{
+	return char_mask[c] & CT_UPPER;
+}
+
+static inline bool is_print(uint8_t c)
+{
+	return char_mask[c] & CT_PRINT;
+}
+
+static inline bool is_punct(uint8_t c)
+{
+	return char_mask[c] & CT_PUNCT;
+}
+
+static inline bool is_space(uint8_t c)
+{
+	return char_mask[c] & CT_SPACE;
+}
diff --git a/src/contrib/dnstap/convert.c b/src/contrib/dnstap/convert.c
new file mode 100644
index 0000000..93ee8e9
--- /dev/null
+++ b/src/contrib/dnstap/convert.c
@@ -0,0 +1,142 @@
+/*  Copyright (C) 2016 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+
+#include "contrib/dnstap/convert.h"
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+/*!
+ * \brief Translation between real and Dnstap value.
+ */
+typedef struct mapping {
+	int real;
+	int dnstap;
+} mapping_t;
+
+/*!
+ * \brief Mapping for network family.
+ */
+static const mapping_t SOCKET_FAMILY_MAPPING[] = {
+	{ AF_INET,  DNSTAP__SOCKET_FAMILY__INET },
+	{ AF_INET6, DNSTAP__SOCKET_FAMILY__INET6 },
+	{ 0 }
+};
+
+/*!
+ * \brief Mapping from network protocol.
+ */
+static const mapping_t SOCKET_PROTOCOL_MAPPING[] = {
+	{ IPPROTO_UDP, DNSTAP__SOCKET_PROTOCOL__UDP },
+	{ IPPROTO_TCP, DNSTAP__SOCKET_PROTOCOL__TCP },
+	{ 0 }
+};
+
+/*!
+ * \brief Get Dnstap value for a given real value.
+ */
+static int encode(const mapping_t *mapping, int real)
+{
+	for (const mapping_t *m = mapping; m->real != 0; m += 1) {
+		if (m->real == real) {
+			return m->dnstap;
+		}
+	}
+
+	return 0;
+}
+
+/*!
+ * \brief Get real value for a given Dnstap value.
+ */
+static int decode(const mapping_t *mapping, int dnstap)
+{
+	for (const mapping_t *m = mapping; m->real != 0; m += 1) {
+		if (m->dnstap == dnstap) {
+			return m->real;
+		}
+	}
+
+	return 0;
+}
+
+/* -- public API ----------------------------------------------------------- */
+
+Dnstap__SocketFamily dt_family_encode(int family)
+{
+	return encode(SOCKET_FAMILY_MAPPING, family);
+}
+
+int dt_family_decode(Dnstap__SocketFamily dnstap_family)
+{
+	return decode(SOCKET_FAMILY_MAPPING, dnstap_family);
+}
+
+Dnstap__SocketProtocol dt_protocol_encode(int protocol)
+{
+	return encode(SOCKET_PROTOCOL_MAPPING, protocol);
+}
+
+int dt_protocol_decode(Dnstap__SocketProtocol dnstap_protocol)
+{
+	return decode(SOCKET_PROTOCOL_MAPPING, dnstap_protocol);
+}
+
+bool dt_message_type_is_query(Dnstap__Message__Type type)
+{
+	switch (type) {
+	case DNSTAP__MESSAGE__TYPE__AUTH_QUERY:
+	case DNSTAP__MESSAGE__TYPE__CLIENT_QUERY:
+	case DNSTAP__MESSAGE__TYPE__FORWARDER_QUERY:
+	case DNSTAP__MESSAGE__TYPE__RESOLVER_QUERY:
+	case DNSTAP__MESSAGE__TYPE__STUB_QUERY:
+	case DNSTAP__MESSAGE__TYPE__TOOL_QUERY:
+		return true;
+	default:
+		return false;
+	}
+}
+
+bool dt_message_type_is_response(Dnstap__Message__Type type)
+{
+	switch (type) {
+	case DNSTAP__MESSAGE__TYPE__AUTH_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__CLIENT_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__FORWARDER_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__RESOLVER_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__STUB_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__TOOL_RESPONSE:
+		return true;
+	default:
+		return false;
+	}
+}
+
+bool dt_message_role_is_initiator(Dnstap__Message__Type type)
+{
+	switch (type) {
+	case DNSTAP__MESSAGE__TYPE__AUTH_QUERY:
+	case DNSTAP__MESSAGE__TYPE__AUTH_RESPONSE:
+	case DNSTAP__MESSAGE__TYPE__CLIENT_QUERY:
+	case DNSTAP__MESSAGE__TYPE__CLIENT_RESPONSE:
+		return false;
+	default:
+		return true;
+	}
+}
diff --git a/src/contrib/dnstap/convert.h b/src/contrib/dnstap/convert.h
new file mode 100644
index 0000000..0e2a86a
--- /dev/null
+++ b/src/contrib/dnstap/convert.h
@@ -0,0 +1,60 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Dnstap identifiers conversions.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+/*!
+ * \brief Get Dnstap socket family from the real one.
+ */
+Dnstap__SocketFamily dt_family_encode(int family);
+
+/*!
+ * \brief Get real socket family from the Dnstap one.
+ */
+int dt_family_decode(Dnstap__SocketFamily dnstap_family);
+
+/*!
+ * \brief Get Dnstap protocol from a real one.
+ */
+Dnstap__SocketProtocol dt_protocol_encode(int protocol);
+
+/*!
+ * \brief Get real protocol from the Dnstap one.
+ */
+int dt_protocol_decode(Dnstap__SocketProtocol dnstap_protocol);
+
+/*!
+ * Check if a message type is any type of a query.
+ */
+bool dt_message_type_is_query(Dnstap__Message__Type type);
+
+/*!
+ * Check if a message type is any type of a response.
+ */
+bool dt_message_type_is_response(Dnstap__Message__Type type);
+
+/*!
+ * Check if a message role is any type of an initiator.
+ */
+bool dt_message_role_is_initiator(Dnstap__Message__Type type);
diff --git a/src/contrib/dnstap/dnstap.c b/src/contrib/dnstap/dnstap.c
new file mode 100644
index 0000000..1f39a48
--- /dev/null
+++ b/src/contrib/dnstap/dnstap.c
@@ -0,0 +1,40 @@
+/*  Copyright (C) 2014 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+#define DNSTAP_INITIAL_BUF_SIZE         256
+
+uint8_t* dt_pack(const Dnstap__Dnstap *d, uint8_t **buf, size_t *sz)
+{
+	ProtobufCBufferSimple sbuf = { { NULL } };
+
+	sbuf.base.append = protobuf_c_buffer_simple_append;
+	sbuf.len = 0;
+	sbuf.alloced = DNSTAP_INITIAL_BUF_SIZE;
+	sbuf.data = malloc(sbuf.alloced);
+	if (sbuf.data == NULL) {
+		return NULL;
+	}
+	sbuf.must_free_data = 1;
+
+	*sz = dnstap__dnstap__pack_to_buffer(d, (ProtobufCBuffer *) &sbuf);
+	*buf = sbuf.data;
+	return *buf;
+}
diff --git a/src/contrib/dnstap/dnstap.h b/src/contrib/dnstap/dnstap.h
new file mode 100644
index 0000000..f7aecbc
--- /dev/null
+++ b/src/contrib/dnstap/dnstap.h
@@ -0,0 +1,47 @@
+/*  Copyright (C) 2014 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \author Robert Edmonds <edmonds@fsi.io>
+ *
+ * \brief Public interface for dnstap.
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+/*! \brief Frame Streams "Content Type" value for dnstap. */
+#define DNSTAP_CONTENT_TYPE     "protobuf:dnstap.Dnstap"
+
+/*!
+ * \brief Serializes a filled out dnstap protobuf struct. Dynamically allocates
+ * storage for the serialized frame.
+ *
+ * \note This function returns a copy of its parameter return value 'buf' to
+ * make error checking slightly easier.
+ *
+ * \param d             dnstap protobuf struct.
+ * \param[out] buf      Serialized frame.
+ * \param[out] sz       Size in bytes of the serialized frame.
+ *
+ * \return              Serialized frame.
+ * \retval NULL         if error.
+ */
+uint8_t* dt_pack(const Dnstap__Dnstap *d, uint8_t **buf, size_t *sz);
diff --git a/src/contrib/dnstap/dnstap.proto b/src/contrib/dnstap/dnstap.proto
new file mode 100644
index 0000000..ea5c77a
--- /dev/null
+++ b/src/contrib/dnstap/dnstap.proto
@@ -0,0 +1,270 @@
+// dnstap: flexible, structured event replication format for DNS software
+//
+// This file contains the protobuf schemas for the "dnstap" structured event
+// replication format for DNS software.
+
+// Written in 2013-2014 by Farsight Security, Inc.
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this file to the public
+// domain worldwide. This file is distributed without any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication along
+// with this file. If not, see:
+//
+// <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+syntax = "proto2";
+
+package dnstap;
+
+// "Dnstap": this is the top-level dnstap type, which is a "union" type that
+// contains other kinds of dnstap payloads, although currently only one type
+// of dnstap payload is defined.
+// See: https://developers.google.com/protocol-buffers/docs/techniques#union
+message Dnstap {
+    // DNS server identity.
+    // If enabled, this is the identity string of the DNS server which generated
+    // this message. Typically this would be the same string as returned by an
+    // "NSID" (RFC 5001) query.
+    optional bytes      identity = 1;
+
+    // DNS server version.
+    // If enabled, this is the version string of the DNS server which generated
+    // this message. Typically this would be the same string as returned by a
+    // "version.bind" query.
+    optional bytes      version = 2;
+
+    // Extra data for this payload.
+    // This field can be used for adding an arbitrary byte-string annotation to
+    // the payload. No encoding or interpretation is applied or enforced.
+    optional bytes      extra = 3;
+
+    // Identifies which field below is filled in.
+    enum Type {
+        MESSAGE = 1;
+    }
+    required Type       type = 15;
+
+    // One of the following will be filled in.
+    optional Message    message = 14;
+}
+
+// SocketFamily: the network protocol family of a socket. This specifies how
+// to interpret "network address" fields.
+enum SocketFamily {
+    INET = 1;   // IPv4 (RFC 791)
+    INET6 = 2;  // IPv6 (RFC 2460)
+}
+
+// SocketProtocol: the transport protocol of a socket. This specifies how to
+// interpret "transport port" fields.
+enum SocketProtocol {
+    UDP = 1;    // User Datagram Protocol (RFC 768)
+    TCP = 2;    // Transmission Control Protocol (RFC 793)
+}
+
+// Message: a wire-format (RFC 1035 section 4) DNS message and associated
+// metadata. Applications generating "Message" payloads should follow
+// certain requirements based on the MessageType, see below.
+message Message {
+
+    // There are eight types of "Message" defined that correspond to the
+    // four arrows in the following diagram, slightly modified from RFC 1035
+    // section 2:
+
+    //    +---------+               +----------+           +--------+
+    //    |         |     query     |          |   query   |        |
+    //    | Stub    |-SQ--------CQ->| Recursive|-RQ----AQ->| Auth.  |
+    //    | Resolver|               | Server   |           | Name   |
+    //    |         |<-SR--------CR-|          |<-RR----AR-| Server |
+    //    +---------+    response   |          |  response |        |
+    //                              +----------+           +--------+
+
+    // Each arrow has two Type values each, one for each "end" of each arrow,
+    // because these are considered to be distinct events. Each end of each
+    // arrow on the diagram above has been marked with a two-letter Type
+    // mnemonic. Clockwise from upper left, these mnemonic values are:
+    //
+    //   SQ:        STUB_QUERY
+    //   CQ:      CLIENT_QUERY
+    //   RQ:    RESOLVER_QUERY
+    //   AQ:        AUTH_QUERY
+    //   AR:        AUTH_RESPONSE
+    //   RR:    RESOLVER_RESPONSE
+    //   CR:      CLIENT_RESPONSE
+    //   SR:        STUB_RESPONSE
+
+    // Two additional types of "Message" have been defined for the
+    // "forwarding" case where an upstream DNS server is responsible for
+    // further recursion. These are not shown on the diagram above, but have
+    // the following mnemonic values:
+
+    //   FQ:   FORWARDER_QUERY
+    //   FR:   FORWARDER_RESPONSE
+
+    // The "Message" Type values are defined below.
+
+    enum Type {
+        // AUTH_QUERY is a DNS query message received from a resolver by an
+        // authoritative name server, from the perspective of the authoritative
+        // name server.
+        AUTH_QUERY = 1;
+
+        // AUTH_RESPONSE is a DNS response message sent from an authoritative
+        // name server to a resolver, from the perspective of the authoritative
+        // name server.
+        AUTH_RESPONSE = 2;
+
+        // RESOLVER_QUERY is a DNS query message sent from a resolver to an
+        // authoritative name server, from the perspective of the resolver.
+        // Resolvers typically clear the RD (recursion desired) bit when
+        // sending queries.
+        RESOLVER_QUERY = 3;
+
+        // RESOLVER_RESPONSE is a DNS response message received from an
+        // authoritative name server by a resolver, from the perspective of
+        // the resolver.
+        RESOLVER_RESPONSE = 4;
+
+        // CLIENT_QUERY is a DNS query message sent from a client to a DNS
+        // server which is expected to perform further recursion, from the
+        // perspective of the DNS server. The client may be a stub resolver or
+        // forwarder or some other type of software which typically sets the RD
+        // (recursion desired) bit when querying the DNS server. The DNS server
+        // may be a simple forwarding proxy or it may be a full recursive
+        // resolver.
+        CLIENT_QUERY = 5;
+
+        // CLIENT_RESPONSE is a DNS response message sent from a DNS server to
+        // a client, from the perspective of the DNS server. The DNS server
+        // typically sets the RA (recursion available) bit when responding.
+        CLIENT_RESPONSE = 6;
+
+        // FORWARDER_QUERY is a DNS query message sent from a downstream DNS
+        // server to an upstream DNS server which is expected to perform
+        // further recursion, from the perspective of the downstream DNS
+        // server.
+        FORWARDER_QUERY = 7;
+
+        // FORWARDER_RESPONSE is a DNS response message sent from an upstream
+        // DNS server performing recursion to a downstream DNS server, from the
+        // perspective of the downstream DNS server.
+        FORWARDER_RESPONSE = 8;
+
+        // STUB_QUERY is a DNS query message sent from a stub resolver to a DNS
+        // server, from the perspective of the stub resolver.
+        STUB_QUERY = 9;
+
+        // STUB_RESPONSE is a DNS response message sent from a DNS server to a
+        // stub resolver, from the perspective of the stub resolver.
+        STUB_RESPONSE = 10;
+
+        // TOOL_QUERY is a DNS query message sent from a DNS software tool to a
+        // DNS server, from the perspective of the tool.
+        TOOL_QUERY = 11;
+
+        // TOOL_RESPONSE is a DNS response message received by a DNS software
+        // tool from a DNS server, from the perspective of the tool.
+        TOOL_RESPONSE = 12;
+    }
+
+    // One of the Type values described above.
+    required Type               type = 1;
+
+    // One of the SocketFamily values described above.
+    optional SocketFamily       socket_family = 2;
+
+    // One of the SocketProtocol values described above.
+    optional SocketProtocol     socket_protocol = 3;
+
+    // The network address of the message initiator.
+    // For SocketFamily INET, this field is 4 octets (IPv4 address).
+    // For SocketFamily INET6, this field is 16 octets (IPv6 address).
+    optional bytes              query_address = 4;
+
+    // The network address of the message responder.
+    // For SocketFamily INET, this field is 4 octets (IPv4 address).
+    // For SocketFamily INET6, this field is 16 octets (IPv6 address).
+    optional bytes              response_address = 5;
+
+    // The transport port of the message initiator.
+    // This is a 16-bit UDP or TCP port number, depending on SocketProtocol.
+    optional uint32             query_port = 6;
+
+    // The transport port of the message responder.
+    // This is a 16-bit UDP or TCP port number, depending on SocketProtocol.
+    optional uint32             response_port = 7;
+
+    // The time at which the DNS query message was sent or received, depending
+    // on whether this is an AUTH_QUERY, RESOLVER_QUERY, or CLIENT_QUERY.
+    // This is the number of seconds since the UNIX epoch.
+    optional uint64             query_time_sec = 8;
+
+    // The time at which the DNS query message was sent or received.
+    // This is the seconds fraction, expressed as a count of nanoseconds.
+    optional fixed32            query_time_nsec = 9;
+
+    // The initiator's original wire-format DNS query message, verbatim.
+    optional bytes              query_message = 10;
+
+    // The "zone" or "bailiwick" pertaining to the DNS query message.
+    // This is a wire-format DNS domain name.
+    optional bytes              query_zone = 11;
+
+    // The time at which the DNS response message was sent or received,
+    // depending on whether this is an AUTH_RESPONSE, RESOLVER_RESPONSE, or
+    // CLIENT_RESPONSE.
+    // This is the number of seconds since the UNIX epoch.
+    optional uint64             response_time_sec = 12;
+
+    // The time at which the DNS response message was sent or received.
+    // This is the seconds fraction, expressed as a count of nanoseconds.
+    optional fixed32            response_time_nsec = 13;
+
+    // The responder's original wire-format DNS response message, verbatim.
+    optional bytes              response_message = 14;
+}
+
+// All fields except for 'type' in the Message schema are optional.
+// It is recommended that at least the following fields be filled in for
+// particular types of Messages.
+
+// AUTH_QUERY:
+//      socket_family, socket_protocol
+//      query_address, query_port
+//      query_message
+//      query_time_sec, query_time_nsec
+
+// AUTH_RESPONSE:
+//      socket_family, socket_protocol
+//      query_address, query_port
+//      query_time_sec, query_time_nsec
+//      response_message
+//      response_time_sec, response_time_nsec
+
+// RESOLVER_QUERY:
+//      socket_family, socket_protocol
+//      query_message
+//      query_time_sec, query_time_nsec
+//      query_zone
+//      response_address, response_port
+
+// RESOLVER_RESPONSE:
+//      socket_family, socket_protocol
+//      query_time_sec, query_time_nsec
+//      query_zone
+//      response_address, response_port
+//      response_message
+//      response_time_sec, response_time_nsec
+
+// CLIENT_QUERY:
+//      socket_family, socket_protocol
+//      query_message
+//      query_time_sec, query_time_nsec
+
+// CLIENT_RESPONSE:
+//      socket_family, socket_protocol
+//      query_time_sec, query_time_nsec
+//      response_message
+//      response_time_sec, response_time_nsec
diff --git a/src/contrib/dnstap/message.c b/src/contrib/dnstap/message.c
new file mode 100644
index 0000000..a5f798e
--- /dev/null
+++ b/src/contrib/dnstap/message.c
@@ -0,0 +1,130 @@
+/*  Copyright (C) 2017 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libknot/errcode.h"
+
+#include "contrib/dnstap/convert.h"
+#include "contrib/dnstap/message.h"
+
+static void set_address(const struct sockaddr *sockaddr,
+                        ProtobufCBinaryData   *addr,
+                        protobuf_c_boolean    *has_addr,
+                        uint32_t              *port,
+                        protobuf_c_boolean    *has_port)
+{
+	if (sockaddr == NULL) {
+		*has_addr = 0;
+		*has_port = 0;
+		return;
+	}
+
+	*has_addr = 1;
+	*has_port = 1;
+
+	if (sockaddr->sa_family == AF_INET) {
+		const struct sockaddr_in *sai;
+		sai = (const struct sockaddr_in *)sockaddr;
+		addr->len = sizeof(sai->sin_addr);
+		addr->data = (uint8_t *)&sai->sin_addr.s_addr;
+		*port = ntohs(sai->sin_port);
+	} else if (sockaddr->sa_family == AF_INET6) {
+		const struct sockaddr_in6 *sai6;
+		sai6 = (const struct sockaddr_in6 *)sockaddr;
+		addr->len = sizeof(sai6->sin6_addr);
+		addr->data = (uint8_t *)&sai6->sin6_addr.s6_addr;
+		*port = ntohs(sai6->sin6_port);
+	}
+}
+
+static int get_family(const struct sockaddr *query_sa,
+	              const struct sockaddr *response_sa)
+{
+	const struct sockaddr *source = query_sa ? query_sa : response_sa;
+	if (source == NULL) {
+		return 0;
+	}
+
+	return dt_family_encode(source->sa_family);
+}
+
+int dt_message_fill(Dnstap__Message             *m,
+                    const Dnstap__Message__Type type,
+                    const struct sockaddr       *query_sa,
+                    const struct sockaddr       *response_sa,
+                    const int                   protocol,
+                    const void                  *wire,
+                    const size_t                len_wire,
+                    const struct timespec       *mtime)
+{
+	if (m == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	memset(m, 0, sizeof(*m));
+
+	m->base.descriptor = &dnstap__message__descriptor;
+
+	// Message.type
+	m->type = type;
+
+	// Message.socket_family
+	m->socket_family = get_family(query_sa, response_sa);
+	m->has_socket_family = m->socket_family != 0;
+
+	// Message.socket_protocol
+	m->socket_protocol = dt_protocol_encode(protocol);
+	m->has_socket_protocol = m->socket_protocol != 0;
+
+	// Message addresses
+	set_address(query_sa, &m->query_address, &m->has_query_address,
+	            &m->query_port, &m->has_query_port);
+	set_address(response_sa, &m->response_address, &m->has_response_address,
+	            &m->response_port, &m->has_response_port);
+
+	if (dt_message_type_is_query(type)) {
+		// Message.query_message
+		m->query_message.len = len_wire;
+		m->query_message.data = (uint8_t *)wire;
+		m->has_query_message = 1;
+		// Message.query_time_sec, Message.query_time_nsec
+		if (mtime != NULL) {
+			m->query_time_sec = mtime->tv_sec;
+			m->query_time_nsec = mtime->tv_nsec;
+			m->has_query_time_sec = 1;
+			m->has_query_time_nsec = 1;
+		}
+	} else if (dt_message_type_is_response(type)) {
+		// Message.response_message
+		m->response_message.len = len_wire;
+		m->response_message.data = (uint8_t *)wire;
+		m->has_response_message = 1;
+		// Message.response_time_sec, Message.response_time_nsec
+		if (mtime != NULL) {
+			m->response_time_sec = mtime->tv_sec;
+			m->response_time_nsec = mtime->tv_nsec;
+			m->has_response_time_sec = 1;
+			m->has_response_time_nsec = 1;
+		}
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/contrib/dnstap/message.h b/src/contrib/dnstap/message.h
new file mode 100644
index 0000000..b9e3aff
--- /dev/null
+++ b/src/contrib/dnstap/message.h
@@ -0,0 +1,63 @@
+/*  Copyright (C) 2017 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \author Robert Edmonds <edmonds@fsi.io>
+ *
+ * \brief Dnstap message interface.
+ */
+
+#pragma once
+
+#include <sys/socket.h>
+#include <sys/time.h>
+#include <stddef.h>
+
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+/*!
+ * \brief Fill a Dnstap__Message structure with the given parameters.
+ *
+ * \param[out] m
+ *      Dnstap__Message structure to fill. Will be zeroed first.
+ * \param type
+ *      One of the DNSTAP__MESSAGE__TYPE__* values.
+ * \param query_sa
+ *      sockaddr_in or sockaddr_in6 to use when filling the 'socket_family',
+ *      'query_address', 'query_port' fields.
+ * \param response_sa
+ *      sockaddr_in or sockaddr_in6 to use when filling the 'socket_family',
+ *      'response_address', 'response_port' fields.
+ * \param protocol
+ *      \c IPPROTO_UDP or \c IPPROTO_TCP.
+ * \param wire
+ *	Wire-format query message or response message (depending on 'type').
+ * \param len_wire
+ *	Length in bytes of 'wire'.
+ * \param mtime
+ *	Message time. May be NULL.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ */
+int dt_message_fill(Dnstap__Message             *m,
+                    const Dnstap__Message__Type type,
+                    const struct sockaddr       *query_sa,
+                    const struct sockaddr       *response_sa,
+                    const int                   protocol,
+                    const void                  *wire,
+                    const size_t                len_wire,
+                    const struct timespec       *mtime);
diff --git a/src/contrib/dnstap/reader.c b/src/contrib/dnstap/reader.c
new file mode 100644
index 0000000..7b98c1b
--- /dev/null
+++ b/src/contrib/dnstap/reader.c
@@ -0,0 +1,105 @@
+/*  Copyright (C) 2014 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libknot/errcode.h"
+
+#include "contrib/macros.h"
+#include "contrib/dnstap/dnstap.h"
+#include "contrib/dnstap/reader.h"
+
+dt_reader_t* dt_reader_create(const char *file_path)
+{
+	struct fstrm_file_options *fopt = NULL;
+	struct fstrm_reader_options *ropt = NULL;
+	dt_reader_t *reader = NULL;
+	fstrm_res res;
+
+	reader = calloc(1, sizeof(dt_reader_t));
+	if (reader == NULL) {
+		goto fail;
+	}
+
+	// Open reader.
+	fopt = fstrm_file_options_init();
+	fstrm_file_options_set_file_path(fopt, file_path);
+	ropt = fstrm_reader_options_init();
+	fstrm_reader_options_add_content_type(ropt,
+		(const uint8_t *) DNSTAP_CONTENT_TYPE,
+		strlen(DNSTAP_CONTENT_TYPE));
+	reader->fr = fstrm_file_reader_init(fopt, ropt);
+	fstrm_file_options_destroy(&fopt);
+	fstrm_reader_options_destroy(&ropt);
+	if (reader->fr == NULL) {
+		goto fail;
+	}
+	res = fstrm_reader_open(reader->fr);
+	if (res != fstrm_res_success) {
+		goto fail;
+	}
+
+	return reader;
+fail:
+	dt_reader_free(reader);
+	return NULL;
+}
+
+void dt_reader_free(dt_reader_t *reader)
+{
+	if (reader == NULL) {
+		return;
+	}
+
+	fstrm_reader_destroy(&reader->fr);
+	free(reader);
+}
+
+int dt_reader_read(dt_reader_t *reader, Dnstap__Dnstap **d)
+{
+	fstrm_res res;
+	const uint8_t *data = NULL;
+	size_t len = 0;
+
+	res = fstrm_reader_read(reader->fr, &data, &len);
+	if (res == fstrm_res_success) {
+		*d = dnstap__dnstap__unpack(NULL, len, data);
+		if (*d == NULL) {
+			return KNOT_ENOMEM;
+		}
+	} else if (res == fstrm_res_failure) {
+		return KNOT_ERROR;
+	} else if (res == fstrm_res_stop) {
+		return KNOT_EOF;
+	}
+
+	return KNOT_EOK;
+}
+
+void dt_reader_free_frame(dt_reader_t *reader, Dnstap__Dnstap **frame_ptr)
+{
+	if (!*frame_ptr) {
+		return;
+	}
+
+	UNUSED(reader);
+
+	dnstap__dnstap__free_unpacked(*frame_ptr, NULL);
+	*frame_ptr = NULL;
+}
diff --git a/src/contrib/dnstap/reader.h b/src/contrib/dnstap/reader.h
new file mode 100644
index 0000000..cc6385f
--- /dev/null
+++ b/src/contrib/dnstap/reader.h
@@ -0,0 +1,73 @@
+/*  Copyright (C) 2017 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Dnstap file reader.
+ */
+
+#pragma once
+
+#include <fstrm.h>
+#include <protobuf-c/protobuf-c.h>
+
+#include "contrib/dnstap/dnstap.pb-c.h"
+
+/*! \brief Structure for dnstap file reader. */
+typedef struct {
+	/*!< Input reader. */
+	struct fstrm_reader	*fr;
+} dt_reader_t;
+
+/*!
+ * \brief Creates dnstap file reader structure.
+ *
+ * \param file_path		Name of file to read input from.
+ *
+ * \retval reader		if success.
+ * \retval NULL			if error.
+ */
+dt_reader_t* dt_reader_create(const char *file_path);
+
+/*!
+ * \brief Close dnstap file reader.
+ *
+ * \param reader		dnstap file reader structure.
+ */
+void dt_reader_free(dt_reader_t *reader);
+
+/*!
+ * \brief Read a dnstap protobuf from a dnstap file reader.
+ *
+ * Caller must deallocate the returned protobuf with the
+ * dnstap__dnstap__free_unpacked() function.
+ *
+ * \param[in]  reader		dnstap file reader structure.
+ * \param[out] d     		Unpacked dnstap protobuf.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_ERROR
+ * \retval KNOT_EOF
+ * \retval KNOT_ENOMEM
+ */
+int dt_reader_read(dt_reader_t *reader, Dnstap__Dnstap **d);
+
+/*!
+ * \brief free the frame allocated by dt_read_data.
+ *
+ * \param reader                Dnstap reader context.
+ * \param d                     The frame to be freed.
+ */
+void dt_reader_free_frame(dt_reader_t *reader, Dnstap__Dnstap **d);
diff --git a/src/contrib/dnstap/writer.c b/src/contrib/dnstap/writer.c
new file mode 100644
index 0000000..03961c1
--- /dev/null
+++ b/src/contrib/dnstap/writer.c
@@ -0,0 +1,120 @@
+/*  Copyright (C) 2014 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libknot/errcode.h"
+
+#include "contrib/dnstap/dnstap.h"
+#include "contrib/dnstap/writer.h"
+
+dt_writer_t* dt_writer_create(const char *file_path, const char *version)
+{
+	struct fstrm_file_options *fopt = NULL;
+	struct fstrm_writer_options *wopt = NULL;
+	dt_writer_t *writer = NULL;
+	fstrm_res res;
+
+	writer = calloc(1, sizeof(dt_writer_t));
+	if (writer == NULL) {
+		goto fail;
+	}
+
+	// Set "version".
+	if (version != NULL) {
+		writer->len_version = strlen(version);
+		writer->version = strdup(version);
+		if (!writer->version) {
+			goto fail;
+		}
+	}
+
+	// Open writer.
+	fopt = fstrm_file_options_init();
+	fstrm_file_options_set_file_path(fopt, file_path);
+	wopt = fstrm_writer_options_init();
+	fstrm_writer_options_add_content_type(wopt,
+		(const uint8_t *) DNSTAP_CONTENT_TYPE,
+		strlen(DNSTAP_CONTENT_TYPE));
+	writer->fw = fstrm_file_writer_init(fopt, wopt);
+	fstrm_file_options_destroy(&fopt);
+	fstrm_writer_options_destroy(&wopt);
+	if (writer->fw == NULL) {
+		goto fail;
+	}
+
+	res = fstrm_writer_open(writer->fw);
+	if (res != fstrm_res_success) {
+		goto fail;
+	}
+
+	return writer;
+fail:
+	dt_writer_free(writer);
+	return NULL;
+}
+
+void dt_writer_free(dt_writer_t *writer)
+{
+	if (writer == NULL) {
+		return;
+	}
+
+	fstrm_writer_destroy(&writer->fw);
+	free(writer->version);
+	free(writer);
+}
+
+int dt_writer_write(dt_writer_t *writer, const ProtobufCMessage *msg)
+{
+	Dnstap__Dnstap dnstap = DNSTAP__DNSTAP__INIT;
+	size_t len;
+	uint8_t *data;
+
+	if (writer->fw == NULL) {
+		return KNOT_EOK;
+	}
+
+	// Only handle dnstap/Message.
+	assert(msg->descriptor == &dnstap__message__descriptor);
+
+	// Fill out 'dnstap'.
+	if (writer->version) {
+		dnstap.version.data = writer->version;
+		dnstap.version.len = writer->len_version;
+		dnstap.has_version = 1;
+	}
+	dnstap.type = DNSTAP__DNSTAP__TYPE__MESSAGE;
+	dnstap.message = (Dnstap__Message *)msg;
+
+	// Serialize the dnstap frame.
+	if (!dt_pack(&dnstap, &data, &len)) {
+		return KNOT_ENOMEM;
+	}
+
+	// Write the dnstap frame to the output stream.
+	if (fstrm_writer_write(writer->fw, data, len) != fstrm_res_success) {
+		return KNOT_ERROR;
+	}
+
+	// Cleanup.
+	free(data);
+
+	return KNOT_EOK;
+}
diff --git a/src/contrib/dnstap/writer.h b/src/contrib/dnstap/writer.h
new file mode 100644
index 0000000..e6928c5
--- /dev/null
+++ b/src/contrib/dnstap/writer.h
@@ -0,0 +1,71 @@
+/*  Copyright (C) 2014 Farsight Security, Inc. <software@farsightsecurity.com>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \author Robert Edmonds <edmonds@fsi.io>
+ *
+ * \brief Dnstap file writer.
+ */
+
+#pragma once
+
+#include <fstrm.h>
+#include <protobuf-c/protobuf-c.h>
+
+/*! \brief Structure for dnstap file writer. */
+typedef struct {
+	/*!< Output writer. */
+	struct fstrm_writer	*fw;
+
+	/*!< dnstap "version" field. */
+	void			*version;
+
+	/*!< length of dnstap "version" field. */
+	size_t			len_version;
+} dt_writer_t;
+
+/*!
+ * \brief Creates dnstap file writer structure.
+ *
+ * \param file_path		Name of file to write output to.
+ * \param version		Version string of software. May be NULL.
+ *
+ * \retval writer		if success.
+ * \retval NULL			if error.
+ */
+dt_writer_t* dt_writer_create(const char *file_path, const char *version);
+
+/*!
+ * \brief Finish writing dnstap file writer and free resources.
+ *
+ * \param writer		dnstap file writer structure.
+ */
+void dt_writer_free(dt_writer_t *writer);
+
+/*!
+ * \brief Write a protobuf to the dnstap file writer.
+ *
+ * Supported protobuf types for the 'msg' parameter:
+ *	\c Dnstap__Message
+ *
+ * \param writer		dnstap file writer structure.
+ * \param msg			dnstap protobuf. Must be a supported type.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ * \retval KNOT_ENOMEM
+ */
+int dt_writer_write(dt_writer_t *writer, const ProtobufCMessage *msg);
diff --git a/src/contrib/dynarray.h b/src/contrib/dynarray.h
new file mode 100644
index 0000000..06a6165
--- /dev/null
+++ b/src/contrib/dynarray.h
@@ -0,0 +1,171 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Simple write-once allocation-optimal dynamic array.
+ *
+ * Include it into your .c file
+ *
+ * prefix - identifier prefix, e.g. ptr -> struct ptr_dynarray, ptr_dynarray_add(), ...
+ * ntype - data type to be stored. Let it be a number, pointer or small struct
+ * initial_capacity - how many data items will be allocated on stac and copied with assignment
+ *
+ * prefix_dynarray_add() - add a data item
+ * prefix_dynarray_fix() - call EVERYTIME the array is copied from some already invalid stack
+ * prefix_dynarray_free() - call EVERYTIME you dismiss all copies of the array
+ *
+ */
+
+#include <stdlib.h>
+#include <assert.h>
+
+#pragma once
+
+#define DYNARRAY_VISIBILITY_STATIC static
+#define DYNARRAY_VISIBILITY_PUBLIC
+#define DYNARRAY_VISIBILITY_LIBRARY __public__
+
+#define dynarray_declare(prefix, ntype, visibility, initial_capacity) \
+	typedef struct prefix ## _dynarray { \
+		ssize_t capacity; \
+		ssize_t size; \
+		ntype *(*arr)(struct prefix ## _dynarray *dynarray); \
+		ntype init[initial_capacity]; \
+		ntype *_arr; \
+	} prefix ## _dynarray_t; \
+	\
+	visibility ntype *prefix ## _dynarray_arr(prefix ## _dynarray_t *dynarray); \
+	visibility void prefix ## _dynarray_add(prefix ## _dynarray_t *dynarray, \
+	                                        ntype const *to_add); \
+	visibility void prefix ## _dynarray_free(prefix ## _dynarray_t *dynarray);
+
+#define dynarray_foreach(prefix, ntype, ptr, array) \
+	for (ntype *ptr = prefix ## _dynarray_arr(&(array)); \
+	     ptr < prefix ## _dynarray_arr(&(array)) + (array).size; ptr++)
+
+#define dynarray_define(prefix, ntype, visibility) \
+	\
+	static void prefix ## _dynarray_free__(struct prefix ## _dynarray *dynarray) \
+	{ \
+		if (dynarray->capacity > sizeof(dynarray->init) / sizeof(*dynarray->init)) { \
+			free(dynarray->_arr); \
+		} \
+	} \
+	\
+	__attribute__((unused)) \
+	visibility ntype *prefix ## _dynarray_arr(struct prefix ## _dynarray *dynarray) \
+	{ \
+		assert(dynarray->size <= dynarray->capacity); \
+		return (dynarray->capacity <= sizeof(dynarray->init) / sizeof(*dynarray->init) ? \
+			dynarray->init : dynarray->_arr); \
+	} \
+	\
+	static ntype *prefix ## _dynarray_arr_init__(struct prefix ## _dynarray *dynarray) \
+	{ \
+		assert(dynarray->capacity == sizeof(dynarray->init) / sizeof(*dynarray->init)); \
+		return dynarray->init; \
+	} \
+	\
+	static ntype *prefix ## _dynarray_arr_arr__(struct prefix ## _dynarray *dynarray) \
+	{ \
+		assert(dynarray->capacity > sizeof(dynarray->init) / sizeof(*dynarray->init)); \
+		return dynarray->_arr; \
+	} \
+	\
+	__attribute__((unused)) \
+	visibility void prefix ## _dynarray_add(struct prefix ## _dynarray *dynarray, \
+	                                        ntype const *to_add) \
+	{ \
+		if (dynarray->capacity < 0) { \
+			return; \
+		} \
+		if (dynarray->capacity == 0) { \
+			dynarray->capacity = sizeof(dynarray->init) / sizeof(*dynarray->init); \
+			dynarray->arr = prefix ## _dynarray_arr_init__; \
+		} \
+		if (dynarray->size >= dynarray->capacity) { \
+			ssize_t new_capacity = dynarray->capacity * 2 + 1; \
+			ntype *new_arr = calloc(new_capacity, sizeof(ntype)); \
+			if (new_arr == NULL) { \
+				prefix ## _dynarray_free__(dynarray); \
+				dynarray->capacity = dynarray->size = -1; \
+				return; \
+			} \
+			if (dynarray->capacity > 0) { \
+				memcpy(new_arr, prefix ## _dynarray_arr(dynarray), \
+				       dynarray->capacity * sizeof(ntype)); \
+			} \
+			prefix ## _dynarray_free__(dynarray); \
+			dynarray->_arr = new_arr; \
+			dynarray->capacity = new_capacity; \
+			dynarray->arr = prefix ## _dynarray_arr_arr__; \
+		} \
+		prefix ## _dynarray_arr(dynarray)[dynarray->size++] = *to_add; \
+	} \
+	\
+	__attribute__((unused)) \
+	visibility void prefix ## _dynarray_remove(struct prefix ## _dynarray *dynarray, \
+	                                           ntype const *to_remove) \
+	{ \
+		ntype *orig_arr = prefix ## _dynarray_arr(dynarray); \
+		dynarray_foreach(prefix, ntype, removable, *dynarray) { \
+			if (memcmp(removable, to_remove, sizeof(*to_remove)) == 0) { \
+				if (removable != orig_arr + --dynarray->size) { \
+					*removable = orig_arr[dynarray->size]; \
+				} \
+			} \
+		} /* TODO enable lowering capacity, take care of capacity going back to initial! */ \
+	} \
+	\
+	__attribute__((unused)) \
+	static int prefix ## _dynarray_memb_cmp(const void *a, const void *b) { \
+		return memcmp(a, b, sizeof(ntype)); \
+	} \
+	\
+	__attribute__((unused)) \
+	visibility void prefix ## _dynarray_sort(struct prefix ## _dynarray *dynarray) \
+	{ \
+		ntype *arr = prefix ## _dynarray_arr(dynarray); \
+		qsort(arr, dynarray->size, sizeof(*arr), prefix ## _dynarray_memb_cmp); \
+	} \
+	\
+	__attribute__((unused)) \
+	visibility void prefix ## _dynarray_sort_dedup(struct prefix ## _dynarray *dynarray) \
+	{ \
+		if (dynarray->size > 1) { \
+			prefix ## _dynarray_sort(dynarray); \
+			ntype *arr = prefix ## _dynarray_arr(dynarray); \
+			ntype *rd = arr + 1; \
+			ntype *wr = arr + 1; \
+			ntype *end = arr + dynarray->size; \
+			while (rd != end) { \
+				if (memcmp(rd - 1, rd, sizeof(*rd)) != 0) { \
+					if (wr != rd) { \
+						*wr = *rd; \
+					} \
+					wr++; \
+				} \
+				rd++; \
+			} \
+			dynarray->size = wr - arr; \
+		} \
+	} \
+	__attribute__((unused)) \
+	visibility void prefix ## _dynarray_free(struct prefix ## _dynarray *dynarray) \
+	{ \
+		prefix ## _dynarray_free__(dynarray); \
+		memset(dynarray, 0, sizeof(*dynarray)); \
+	}
diff --git a/src/contrib/files.c b/src/contrib/files.c
new file mode 100644
index 0000000..7f24426
--- /dev/null
+++ b/src/contrib/files.c
@@ -0,0 +1,199 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <ftw.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "contrib/files.h"
+#include "contrib/string.h"
+#include "libknot/errcode.h"
+
+#if defined(MAXBSIZE)
+  #define BUFSIZE MAXBSIZE
+#else
+  #define BUFSIZE (64 * 1024)
+#endif
+
+static int remove_file(const char *path, const struct stat *stat, int type, struct FTW *ftw)
+{
+	(void)stat;
+	(void)ftw;
+	if (type == FTW_DP) {
+		return rmdir(path);
+	} else {
+		return unlink(path);
+	}
+}
+
+bool remove_path(const char *path)
+{
+	return (0 == nftw(path, remove_file, 1, FTW_DEPTH | FTW_PHYS));
+}
+
+int make_dir(const char *path, mode_t mode, bool ignore_existing)
+{
+	if (mkdir(path, mode) == 0) {
+		return KNOT_EOK;
+	}
+
+	if (!ignore_existing || errno != EEXIST) {
+		return knot_map_errno();
+	}
+
+	assert(errno == EEXIST);
+
+	struct stat st = { 0 };
+	if (stat(path, &st) != 0) {
+		return knot_map_errno();
+	}
+
+	if (!S_ISDIR(st.st_mode)) {
+		return knot_map_errno_code(ENOTDIR);
+	}
+
+	return KNOT_EOK;
+}
+
+int make_path(const char *path, mode_t mode)
+{
+	if (path == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	char *dir = strdup(path);
+	if (dir == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	for (char *p = strchr(dir + 1, '/'); p != NULL; p = strchr(p + 1, '/')) {
+		*p = '\0';
+		if (mkdir(dir, mode) == -1 && errno != EEXIST) {
+			free(dir);
+			return knot_map_errno();
+		}
+		*p = '/';
+	}
+
+	free(dir);
+
+	return KNOT_EOK;
+}
+
+int open_tmp_file(const char *path, char **tmp_name, FILE **file, mode_t mode)
+{
+	int ret;
+
+	*tmp_name = sprintf_alloc("%s.XXXXXX", path);
+	if (*tmp_name == NULL) {
+		ret = KNOT_ENOMEM;
+		goto open_tmp_failed;
+	}
+
+	int fd = mkstemp(*tmp_name);
+	if (fd < 0) {
+		ret = knot_map_errno();
+		goto open_tmp_failed;
+	}
+
+	if (fchmod(fd, mode) != 0) {
+		ret = knot_map_errno();
+		close(fd);
+		unlink(*tmp_name);
+		goto open_tmp_failed;
+	}
+
+	*file = fdopen(fd, "w");
+	if (*file == NULL) {
+		ret = knot_map_errno();
+		close(fd);
+		unlink(*tmp_name);
+		goto open_tmp_failed;
+	}
+
+	return KNOT_EOK;
+open_tmp_failed:
+	free(*tmp_name);
+	*tmp_name = NULL;
+	*file = NULL;
+
+	assert(ret != KNOT_EOK);
+	return ret;
+}
+
+int copy_file(const char *dest, const char *src)
+{
+	if (dest == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = 0;
+	char *buf = NULL, *tmp_name = NULL;
+	FILE *file = NULL;
+
+	FILE *from = fopen(src, "r");
+	if (from == NULL) {
+		ret = knot_map_errno();
+		goto done;
+	}
+
+	buf = malloc(sizeof(*buf) * BUFSIZE);
+	if (buf == NULL) {
+		ret = KNOT_ENOMEM;
+		goto done;
+	}
+
+	ret = open_tmp_file(dest, &tmp_name, &file, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
+	if (ret != KNOT_EOK) {
+		goto done;
+	}
+
+	ssize_t cnt;
+	while ((cnt = fread(buf, sizeof(*buf), BUFSIZE, from)) != 0 &&
+	       (ret = (fwrite(buf, sizeof(*buf), cnt, file) == cnt))) {
+	}
+
+	ret = !ret || ferror(from);
+	if (ret != 0) {
+		ret = knot_map_errno();
+		unlink(tmp_name);
+		goto done;
+	}
+
+	ret = rename(tmp_name, dest);
+	if (ret != 0) {
+		ret = knot_map_errno();
+		unlink(tmp_name);
+		goto done;
+	}
+	ret = KNOT_EOK;
+
+done:
+	free(tmp_name);
+	if (file != NULL) {
+		fclose(file);
+	}
+	free(buf);
+	if (from != NULL) {
+		fclose(from);
+	}
+	return ret;
+}
diff --git a/src/contrib/files.h b/src/contrib/files.h
new file mode 100644
index 0000000..c8e2457
--- /dev/null
+++ b/src/contrib/files.h
@@ -0,0 +1,48 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/types.h>
+
+/*!
+ * \brief Delete file or directory (recursive).
+ *
+ * \return true on success, false when one or more files failed to be removed.
+ */
+bool remove_path(const char *path);
+
+/*!
+ * Equivalent to mkdir(2), can succeed if the directory already exists.
+ */
+int make_dir(const char *path, mode_t mode, bool ignore_existing);
+
+/*!
+ * Makes a directory part of the path with all parent directories if not exist.
+ */
+int make_path(const char *path, mode_t mode);
+
+/*!
+ * Creates and opens for writing a temporary file based on given path.
+ */
+int open_tmp_file(const char *path, char **tmp_name, FILE **file, mode_t mode);
+
+/*!
+ * Copies a file, possibly overwriting existing one, as an atomic operation.
+ */
+int copy_file(const char *dest, const char *src);
diff --git a/src/contrib/getline.c b/src/contrib/getline.c
new file mode 100644
index 0000000..46cdff9
--- /dev/null
+++ b/src/contrib/getline.c
@@ -0,0 +1,60 @@
+/*  Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+// FreeBSD POSIX2008 getline
+#ifndef _WITH_GETLINE
+#define _WITH_GETLINE
+#endif
+
+#include "contrib/getline.h"
+
+#include <stdio.h>		// getline or fgetln
+#include <stdlib.h>		// free
+#include <string.h>		// memcpy
+
+ssize_t knot_getline(char **lineptr, size_t *n, FILE *stream)
+{
+#ifdef HAVE_GETLINE
+	return getline(lineptr, n, stream);
+#else
+#ifdef HAVE_FGETLN
+	size_t length = 0;
+	char *buffer = fgetln(stream, &length);
+	if (buffer == NULL) {
+		return -1;
+	}
+
+	/* NOTE: Function fgetln doesn't return terminated string!
+	 *       Output buffer from the fgetln can't be freed.
+	 */
+
+	// If the output buffer is not specified or is small, extend it.
+	if (*lineptr == NULL || *n <= length) {
+		char *tmp = realloc(*lineptr, length + 1);
+		if (tmp == NULL) {
+			return -1;
+		}
+		*lineptr = tmp;
+		*n = length + 1;
+	}
+
+	memcpy(*lineptr, buffer, length);
+	(*lineptr)[length] = '\0';
+
+	return length;
+#endif
+#endif
+}
diff --git a/src/contrib/getline.h b/src/contrib/getline.h
new file mode 100644
index 0000000..80f2db1
--- /dev/null
+++ b/src/contrib/getline.h
@@ -0,0 +1,39 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Multiplatform getline wrapper.
+ */
+
+#pragma once
+
+#include <stdio.h>
+#include <sys/types.h>
+
+/*!
+ * \brief Reads a line from a stream.
+ *
+ * This function has the same semantics as POSIX.1-2008 getline().
+ * If necessary, the output buffer will be allocated/reallocated.
+ *
+ * \param lineptr	Output buffer.
+ * \param n		Output buffer size.
+ * \param stream	Input stream.
+ *
+ * \retval Number of characters read, including new line delimiter,
+ *         not including terminating. -1 on error or EOF.
+ */
+ssize_t knot_getline(char **lineptr, size_t *n, FILE *stream);
diff --git a/src/contrib/libbpf/LICENSE b/src/contrib/libbpf/LICENSE
new file mode 100644
index 0000000..149c7b0
--- /dev/null
+++ b/src/contrib/libbpf/LICENSE
@@ -0,0 +1 @@
+../licenses/LGPL-2.1
\ No newline at end of file
diff --git a/src/contrib/libbpf/bpf/bpf.c b/src/contrib/libbpf/bpf/bpf.c
new file mode 100644
index 0000000..98596e1
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf.c
@@ -0,0 +1,710 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * common eBPF ELF operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <memory.h>
+#include <unistd.h>
+#include <asm/unistd.h>
+#include <errno.h>
+#include <linux/bpf.h>
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+/*
+ * When building perf, unistd.h is overridden. __NR_bpf is
+ * required to be defined explicitly.
+ */
+#ifndef __NR_bpf
+# if defined(__i386__)
+#  define __NR_bpf 357
+# elif defined(__x86_64__)
+#  define __NR_bpf 321
+# elif defined(__aarch64__)
+#  define __NR_bpf 280
+# elif defined(__sparc__)
+#  define __NR_bpf 349
+# elif defined(__s390__)
+#  define __NR_bpf 351
+# elif defined(__arc__)
+#  define __NR_bpf 280
+# else
+#  error __NR_bpf not defined. libbpf does not support your arch.
+# endif
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+static inline int sys_bpf(enum bpf_cmd cmd, union bpf_attr *attr,
+			  unsigned int size)
+{
+	return syscall(__NR_bpf, cmd, attr, size);
+}
+
+static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size)
+{
+	int fd;
+
+	do {
+		fd = sys_bpf(BPF_PROG_LOAD, attr, size);
+	} while (fd < 0 && errno == EAGAIN);
+
+	return fd;
+}
+
+int bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr)
+{
+	union bpf_attr attr;
+
+	memset(&attr, '\0', sizeof(attr));
+
+	attr.map_type = create_attr->map_type;
+	attr.key_size = create_attr->key_size;
+	attr.value_size = create_attr->value_size;
+	attr.max_entries = create_attr->max_entries;
+	attr.map_flags = create_attr->map_flags;
+	if (create_attr->name)
+		memcpy(attr.map_name, create_attr->name,
+		       min(strlen(create_attr->name), BPF_OBJ_NAME_LEN - 1));
+	attr.numa_node = create_attr->numa_node;
+	attr.btf_fd = create_attr->btf_fd;
+	attr.btf_key_type_id = create_attr->btf_key_type_id;
+	attr.btf_value_type_id = create_attr->btf_value_type_id;
+	attr.map_ifindex = create_attr->map_ifindex;
+	attr.inner_map_fd = create_attr->inner_map_fd;
+
+	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+}
+
+int bpf_create_map_node(enum bpf_map_type map_type, const char *name,
+			int key_size, int value_size, int max_entries,
+			__u32 map_flags, int node)
+{
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.name = name;
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
+	if (node >= 0) {
+		map_attr.numa_node = node;
+		map_attr.map_flags |= BPF_F_NUMA_NODE;
+	}
+
+	return bpf_create_map_xattr(&map_attr);
+}
+
+int bpf_create_map(enum bpf_map_type map_type, int key_size,
+		   int value_size, int max_entries, __u32 map_flags)
+{
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
+
+	return bpf_create_map_xattr(&map_attr);
+}
+
+int bpf_create_map_name(enum bpf_map_type map_type, const char *name,
+			int key_size, int value_size, int max_entries,
+			__u32 map_flags)
+{
+	struct bpf_create_map_attr map_attr = {};
+
+	map_attr.name = name;
+	map_attr.map_type = map_type;
+	map_attr.map_flags = map_flags;
+	map_attr.key_size = key_size;
+	map_attr.value_size = value_size;
+	map_attr.max_entries = max_entries;
+
+	return bpf_create_map_xattr(&map_attr);
+}
+
+int bpf_create_map_in_map_node(enum bpf_map_type map_type, const char *name,
+			       int key_size, int inner_map_fd, int max_entries,
+			       __u32 map_flags, int node)
+{
+	union bpf_attr attr;
+
+	memset(&attr, '\0', sizeof(attr));
+
+	attr.map_type = map_type;
+	attr.key_size = key_size;
+	attr.value_size = 4;
+	attr.inner_map_fd = inner_map_fd;
+	attr.max_entries = max_entries;
+	attr.map_flags = map_flags;
+	if (name)
+		memcpy(attr.map_name, name,
+		       min(strlen(name), BPF_OBJ_NAME_LEN - 1));
+
+	if (node >= 0) {
+		attr.map_flags |= BPF_F_NUMA_NODE;
+		attr.numa_node = node;
+	}
+
+	return sys_bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+}
+
+int bpf_create_map_in_map(enum bpf_map_type map_type, const char *name,
+			  int key_size, int inner_map_fd, int max_entries,
+			  __u32 map_flags)
+{
+	return bpf_create_map_in_map_node(map_type, name, key_size,
+					  inner_map_fd, max_entries, map_flags,
+					  -1);
+}
+
+static void *
+alloc_zero_tailing_info(const void *orecord, __u32 cnt,
+			__u32 actual_rec_size, __u32 expected_rec_size)
+{
+	__u64 info_len = (__u64)actual_rec_size * cnt;
+	void *info, *nrecord;
+	int i;
+
+	info = malloc(info_len);
+	if (!info)
+		return NULL;
+
+	/* zero out bytes kernel does not understand */
+	nrecord = info;
+	for (i = 0; i < cnt; i++) {
+		memcpy(nrecord, orecord, expected_rec_size);
+		memset(nrecord + expected_rec_size, 0,
+		       actual_rec_size - expected_rec_size);
+		orecord += actual_rec_size;
+		nrecord += actual_rec_size;
+	}
+
+	return info;
+}
+
+int bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
+			   char *log_buf, size_t log_buf_sz)
+{
+	void *finfo = NULL, *linfo = NULL;
+	union bpf_attr attr;
+	__u32 log_level;
+	int fd;
+
+	if (!load_attr || !log_buf != !log_buf_sz)
+		return -EINVAL;
+
+	log_level = load_attr->log_level;
+	if (log_level > (4 | 2 | 1) || (log_level && !log_buf))
+		return -EINVAL;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = load_attr->prog_type;
+	attr.expected_attach_type = load_attr->expected_attach_type;
+	if (attr.prog_type == BPF_PROG_TYPE_TRACING) {
+		attr.attach_btf_id = load_attr->attach_btf_id;
+		attr.attach_prog_fd = load_attr->attach_prog_fd;
+	} else {
+		attr.prog_ifindex = load_attr->prog_ifindex;
+		attr.kern_version = load_attr->kern_version;
+	}
+	attr.insn_cnt = (__u32)load_attr->insns_cnt;
+	attr.insns = ptr_to_u64(load_attr->insns);
+	attr.license = ptr_to_u64(load_attr->license);
+
+	attr.log_level = log_level;
+	if (log_level) {
+		attr.log_buf = ptr_to_u64(log_buf);
+		attr.log_size = log_buf_sz;
+	} else {
+		attr.log_buf = ptr_to_u64(NULL);
+		attr.log_size = 0;
+	}
+
+	attr.prog_btf_fd = load_attr->prog_btf_fd;
+	attr.func_info_rec_size = load_attr->func_info_rec_size;
+	attr.func_info_cnt = load_attr->func_info_cnt;
+	attr.func_info = ptr_to_u64(load_attr->func_info);
+	attr.line_info_rec_size = load_attr->line_info_rec_size;
+	attr.line_info_cnt = load_attr->line_info_cnt;
+	attr.line_info = ptr_to_u64(load_attr->line_info);
+	if (load_attr->name)
+		memcpy(attr.prog_name, load_attr->name,
+		       min(strlen(load_attr->name), BPF_OBJ_NAME_LEN - 1));
+	attr.prog_flags = load_attr->prog_flags;
+
+	fd = sys_bpf_prog_load(&attr, sizeof(attr));
+	if (fd >= 0)
+		return fd;
+
+	/* After bpf_prog_load, the kernel may modify certain attributes
+	 * to give user space a hint how to deal with loading failure.
+	 * Check to see whether we can make some changes and load again.
+	 */
+	while (errno == E2BIG && (!finfo || !linfo)) {
+		if (!finfo && attr.func_info_cnt &&
+		    attr.func_info_rec_size < load_attr->func_info_rec_size) {
+			/* try with corrected func info records */
+			finfo = alloc_zero_tailing_info(load_attr->func_info,
+							load_attr->func_info_cnt,
+							load_attr->func_info_rec_size,
+							attr.func_info_rec_size);
+			if (!finfo)
+				goto done;
+
+			attr.func_info = ptr_to_u64(finfo);
+			attr.func_info_rec_size = load_attr->func_info_rec_size;
+		} else if (!linfo && attr.line_info_cnt &&
+			   attr.line_info_rec_size <
+			   load_attr->line_info_rec_size) {
+			linfo = alloc_zero_tailing_info(load_attr->line_info,
+							load_attr->line_info_cnt,
+							load_attr->line_info_rec_size,
+							attr.line_info_rec_size);
+			if (!linfo)
+				goto done;
+
+			attr.line_info = ptr_to_u64(linfo);
+			attr.line_info_rec_size = load_attr->line_info_rec_size;
+		} else {
+			break;
+		}
+
+		fd = sys_bpf_prog_load(&attr, sizeof(attr));
+
+		if (fd >= 0)
+			goto done;
+	}
+
+	if (log_level || !log_buf)
+		goto done;
+
+	/* Try again with log */
+	attr.log_buf = ptr_to_u64(log_buf);
+	attr.log_size = log_buf_sz;
+	attr.log_level = 1;
+	log_buf[0] = 0;
+	fd = sys_bpf_prog_load(&attr, sizeof(attr));
+done:
+	free(finfo);
+	free(linfo);
+	return fd;
+}
+
+int bpf_load_program(enum bpf_prog_type type, const struct bpf_insn *insns,
+		     size_t insns_cnt, const char *license,
+		     __u32 kern_version, char *log_buf,
+		     size_t log_buf_sz)
+{
+	struct bpf_load_program_attr load_attr;
+
+	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+	load_attr.prog_type = type;
+	load_attr.expected_attach_type = 0;
+	load_attr.name = NULL;
+	load_attr.insns = insns;
+	load_attr.insns_cnt = insns_cnt;
+	load_attr.license = license;
+	load_attr.kern_version = kern_version;
+
+	return bpf_load_program_xattr(&load_attr, log_buf, log_buf_sz);
+}
+
+int bpf_verify_program(enum bpf_prog_type type, const struct bpf_insn *insns,
+		       size_t insns_cnt, __u32 prog_flags, const char *license,
+		       __u32 kern_version, char *log_buf, size_t log_buf_sz,
+		       int log_level)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = type;
+	attr.insn_cnt = (__u32)insns_cnt;
+	attr.insns = ptr_to_u64(insns);
+	attr.license = ptr_to_u64(license);
+	attr.log_buf = ptr_to_u64(log_buf);
+	attr.log_size = log_buf_sz;
+	attr.log_level = log_level;
+	log_buf[0] = 0;
+	attr.kern_version = kern_version;
+	attr.prog_flags = prog_flags;
+
+	return sys_bpf_prog_load(&attr, sizeof(attr));
+}
+
+int bpf_map_update_elem(int fd, const void *key, const void *value,
+			__u64 flags)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	return sys_bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_lookup_elem(int fd, const void *key, void *value)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+
+	return sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_lookup_elem_flags(int fd, const void *key, void *value, __u64 flags)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+	attr.flags = flags;
+
+	return sys_bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_lookup_and_delete_elem(int fd, const void *key, void *value)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.value = ptr_to_u64(value);
+
+	return sys_bpf(BPF_MAP_LOOKUP_AND_DELETE_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_delete_elem(int fd, const void *key)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+
+	return sys_bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+}
+
+int bpf_map_get_next_key(int fd, const void *key, void *next_key)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+	attr.key = ptr_to_u64(key);
+	attr.next_key = ptr_to_u64(next_key);
+
+	return sys_bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+}
+
+int bpf_map_freeze(int fd)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_fd = fd;
+
+	return sys_bpf(BPF_MAP_FREEZE, &attr, sizeof(attr));
+}
+
+int bpf_obj_pin(int fd, const char *pathname)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.pathname = ptr_to_u64((void *)pathname);
+	attr.bpf_fd = fd;
+
+	return sys_bpf(BPF_OBJ_PIN, &attr, sizeof(attr));
+}
+
+int bpf_obj_get(const char *pathname)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.pathname = ptr_to_u64((void *)pathname);
+
+	return sys_bpf(BPF_OBJ_GET, &attr, sizeof(attr));
+}
+
+int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type,
+		    unsigned int flags)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.target_fd	   = target_fd;
+	attr.attach_bpf_fd = prog_fd;
+	attr.attach_type   = type;
+	attr.attach_flags  = flags;
+
+	return sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr));
+}
+
+int bpf_prog_detach(int target_fd, enum bpf_attach_type type)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.target_fd	 = target_fd;
+	attr.attach_type = type;
+
+	return sys_bpf(BPF_PROG_DETACH, &attr, sizeof(attr));
+}
+
+int bpf_prog_detach2(int prog_fd, int target_fd, enum bpf_attach_type type)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.target_fd	 = target_fd;
+	attr.attach_bpf_fd = prog_fd;
+	attr.attach_type = type;
+
+	return sys_bpf(BPF_PROG_DETACH, &attr, sizeof(attr));
+}
+
+int bpf_prog_query(int target_fd, enum bpf_attach_type type, __u32 query_flags,
+		   __u32 *attach_flags, __u32 *prog_ids, __u32 *prog_cnt)
+{
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.query.target_fd	= target_fd;
+	attr.query.attach_type	= type;
+	attr.query.query_flags	= query_flags;
+	attr.query.prog_cnt	= *prog_cnt;
+	attr.query.prog_ids	= ptr_to_u64(prog_ids);
+
+	ret = sys_bpf(BPF_PROG_QUERY, &attr, sizeof(attr));
+	if (attach_flags)
+		*attach_flags = attr.query.attach_flags;
+	*prog_cnt = attr.query.prog_cnt;
+	return ret;
+}
+
+int bpf_prog_test_run(int prog_fd, int repeat, void *data, __u32 size,
+		      void *data_out, __u32 *size_out, __u32 *retval,
+		      __u32 *duration)
+{
+	union bpf_attr attr;
+	int ret;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.test.prog_fd = prog_fd;
+	attr.test.data_in = ptr_to_u64(data);
+	attr.test.data_out = ptr_to_u64(data_out);
+	attr.test.data_size_in = size;
+	attr.test.repeat = repeat;
+
+	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, sizeof(attr));
+	if (size_out)
+		*size_out = attr.test.data_size_out;
+	if (retval)
+		*retval = attr.test.retval;
+	if (duration)
+		*duration = attr.test.duration;
+	return ret;
+}
+
+int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr)
+{
+	union bpf_attr attr;
+	int ret;
+
+	if (!test_attr->data_out && test_attr->data_size_out > 0)
+		return -EINVAL;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.test.prog_fd = test_attr->prog_fd;
+	attr.test.data_in = ptr_to_u64(test_attr->data_in);
+	attr.test.data_out = ptr_to_u64(test_attr->data_out);
+	attr.test.data_size_in = test_attr->data_size_in;
+	attr.test.data_size_out = test_attr->data_size_out;
+	attr.test.ctx_in = ptr_to_u64(test_attr->ctx_in);
+	attr.test.ctx_out = ptr_to_u64(test_attr->ctx_out);
+	attr.test.ctx_size_in = test_attr->ctx_size_in;
+	attr.test.ctx_size_out = test_attr->ctx_size_out;
+	attr.test.repeat = test_attr->repeat;
+
+	ret = sys_bpf(BPF_PROG_TEST_RUN, &attr, sizeof(attr));
+	test_attr->data_size_out = attr.test.data_size_out;
+	test_attr->ctx_size_out = attr.test.ctx_size_out;
+	test_attr->retval = attr.test.retval;
+	test_attr->duration = attr.test.duration;
+	return ret;
+}
+
+static int bpf_obj_get_next_id(__u32 start_id, __u32 *next_id, int cmd)
+{
+	union bpf_attr attr;
+	int err;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.start_id = start_id;
+
+	err = sys_bpf(cmd, &attr, sizeof(attr));
+	if (!err)
+		*next_id = attr.next_id;
+
+	return err;
+}
+
+int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_PROG_GET_NEXT_ID);
+}
+
+int bpf_map_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_MAP_GET_NEXT_ID);
+}
+
+int bpf_btf_get_next_id(__u32 start_id, __u32 *next_id)
+{
+	return bpf_obj_get_next_id(start_id, next_id, BPF_BTF_GET_NEXT_ID);
+}
+
+int bpf_prog_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_id = id;
+
+	return sys_bpf(BPF_PROG_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int bpf_map_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.map_id = id;
+
+	return sys_bpf(BPF_MAP_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int bpf_btf_get_fd_by_id(__u32 id)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.btf_id = id;
+
+	return sys_bpf(BPF_BTF_GET_FD_BY_ID, &attr, sizeof(attr));
+}
+
+int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len)
+{
+	union bpf_attr attr;
+	int err;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.info.bpf_fd = prog_fd;
+	attr.info.info_len = *info_len;
+	attr.info.info = ptr_to_u64(info);
+
+	err = sys_bpf(BPF_OBJ_GET_INFO_BY_FD, &attr, sizeof(attr));
+	if (!err)
+		*info_len = attr.info.info_len;
+
+	return err;
+}
+
+int bpf_raw_tracepoint_open(const char *name, int prog_fd)
+{
+	union bpf_attr attr;
+
+	memset(&attr, 0, sizeof(attr));
+	attr.raw_tracepoint.name = ptr_to_u64(name);
+	attr.raw_tracepoint.prog_fd = prog_fd;
+
+	return sys_bpf(BPF_RAW_TRACEPOINT_OPEN, &attr, sizeof(attr));
+}
+
+int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf, __u32 log_buf_size,
+		 bool do_log)
+{
+	union bpf_attr attr = {};
+	int fd;
+
+	attr.btf = ptr_to_u64(btf);
+	attr.btf_size = btf_size;
+
+retry:
+	if (do_log && log_buf && log_buf_size) {
+		attr.btf_log_level = 1;
+		attr.btf_log_size = log_buf_size;
+		attr.btf_log_buf = ptr_to_u64(log_buf);
+	}
+
+	fd = sys_bpf(BPF_BTF_LOAD, &attr, sizeof(attr));
+	if (fd == -1 && !do_log && log_buf && log_buf_size) {
+		do_log = true;
+		goto retry;
+	}
+
+	return fd;
+}
+
+int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf, __u32 *buf_len,
+		      __u32 *prog_id, __u32 *fd_type, __u64 *probe_offset,
+		      __u64 *probe_addr)
+{
+	union bpf_attr attr = {};
+	int err;
+
+	attr.task_fd_query.pid = pid;
+	attr.task_fd_query.fd = fd;
+	attr.task_fd_query.flags = flags;
+	attr.task_fd_query.buf = ptr_to_u64(buf);
+	attr.task_fd_query.buf_len = *buf_len;
+
+	err = sys_bpf(BPF_TASK_FD_QUERY, &attr, sizeof(attr));
+	*buf_len = attr.task_fd_query.buf_len;
+	*prog_id = attr.task_fd_query.prog_id;
+	*fd_type = attr.task_fd_query.fd_type;
+	*probe_offset = attr.task_fd_query.probe_offset;
+	*probe_addr = attr.task_fd_query.probe_addr;
+
+	return err;
+}
diff --git a/src/contrib/libbpf/bpf/bpf.h b/src/contrib/libbpf/bpf/bpf.h
new file mode 100644
index 0000000..3c791fa
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf.h
@@ -0,0 +1,184 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * common eBPF ELF operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License (not later!)
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this program; if not,  see <http://www.gnu.org/licenses>
+ */
+#ifndef __LIBBPF_BPF_H
+#define __LIBBPF_BPF_H
+
+#include <linux/bpf.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef LIBBPF_API
+#define LIBBPF_API __attribute__((visibility("default")))
+#endif
+
+struct bpf_create_map_attr {
+	const char *name;
+	enum bpf_map_type map_type;
+	__u32 map_flags;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 numa_node;
+	__u32 btf_fd;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	__u32 map_ifindex;
+	__u32 inner_map_fd;
+};
+
+LIBBPF_API int
+bpf_create_map_xattr(const struct bpf_create_map_attr *create_attr);
+LIBBPF_API int bpf_create_map_node(enum bpf_map_type map_type, const char *name,
+				   int key_size, int value_size,
+				   int max_entries, __u32 map_flags, int node);
+LIBBPF_API int bpf_create_map_name(enum bpf_map_type map_type, const char *name,
+				   int key_size, int value_size,
+				   int max_entries, __u32 map_flags);
+LIBBPF_API int bpf_create_map(enum bpf_map_type map_type, int key_size,
+			      int value_size, int max_entries, __u32 map_flags);
+LIBBPF_API int bpf_create_map_in_map_node(enum bpf_map_type map_type,
+					  const char *name, int key_size,
+					  int inner_map_fd, int max_entries,
+					  __u32 map_flags, int node);
+LIBBPF_API int bpf_create_map_in_map(enum bpf_map_type map_type,
+				     const char *name, int key_size,
+				     int inner_map_fd, int max_entries,
+				     __u32 map_flags);
+
+struct bpf_load_program_attr {
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	const char *name;
+	const struct bpf_insn *insns;
+	size_t insns_cnt;
+	const char *license;
+	union {
+		__u32 kern_version;
+		__u32 attach_prog_fd;
+	};
+	union {
+		__u32 prog_ifindex;
+		__u32 attach_btf_id;
+	};
+	__u32 prog_btf_fd;
+	__u32 func_info_rec_size;
+	const void *func_info;
+	__u32 func_info_cnt;
+	__u32 line_info_rec_size;
+	const void *line_info;
+	__u32 line_info_cnt;
+	__u32 log_level;
+	__u32 prog_flags;
+};
+
+/* Flags to direct loading requirements */
+#define MAPS_RELAX_COMPAT	0x01
+
+/* Recommend log buffer size */
+#define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */
+LIBBPF_API int
+bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
+		       char *log_buf, size_t log_buf_sz);
+LIBBPF_API int bpf_load_program(enum bpf_prog_type type,
+				const struct bpf_insn *insns, size_t insns_cnt,
+				const char *license, __u32 kern_version,
+				char *log_buf, size_t log_buf_sz);
+LIBBPF_API int bpf_verify_program(enum bpf_prog_type type,
+				  const struct bpf_insn *insns,
+				  size_t insns_cnt, __u32 prog_flags,
+				  const char *license, __u32 kern_version,
+				  char *log_buf, size_t log_buf_sz,
+				  int log_level);
+
+LIBBPF_API int bpf_map_update_elem(int fd, const void *key, const void *value,
+				   __u64 flags);
+
+LIBBPF_API int bpf_map_lookup_elem(int fd, const void *key, void *value);
+LIBBPF_API int bpf_map_lookup_elem_flags(int fd, const void *key, void *value,
+					 __u64 flags);
+LIBBPF_API int bpf_map_lookup_and_delete_elem(int fd, const void *key,
+					      void *value);
+LIBBPF_API int bpf_map_delete_elem(int fd, const void *key);
+LIBBPF_API int bpf_map_get_next_key(int fd, const void *key, void *next_key);
+LIBBPF_API int bpf_map_freeze(int fd);
+LIBBPF_API int bpf_obj_pin(int fd, const char *pathname);
+LIBBPF_API int bpf_obj_get(const char *pathname);
+LIBBPF_API int bpf_prog_attach(int prog_fd, int attachable_fd,
+			       enum bpf_attach_type type, unsigned int flags);
+LIBBPF_API int bpf_prog_detach(int attachable_fd, enum bpf_attach_type type);
+LIBBPF_API int bpf_prog_detach2(int prog_fd, int attachable_fd,
+				enum bpf_attach_type type);
+
+struct bpf_prog_test_run_attr {
+	int prog_fd;
+	int repeat;
+	const void *data_in;
+	__u32 data_size_in;
+	void *data_out;      /* optional */
+	__u32 data_size_out; /* in: max length of data_out
+			      * out: length of data_out */
+	__u32 retval;        /* out: return code of the BPF program */
+	__u32 duration;      /* out: average per repetition in ns */
+	const void *ctx_in; /* optional */
+	__u32 ctx_size_in;
+	void *ctx_out;      /* optional */
+	__u32 ctx_size_out; /* in: max length of ctx_out
+			     * out: length of cxt_out */
+};
+
+LIBBPF_API int bpf_prog_test_run_xattr(struct bpf_prog_test_run_attr *test_attr);
+
+/*
+ * bpf_prog_test_run does not check that data_out is large enough. Consider
+ * using bpf_prog_test_run_xattr instead.
+ */
+LIBBPF_API int bpf_prog_test_run(int prog_fd, int repeat, void *data,
+				 __u32 size, void *data_out, __u32 *size_out,
+				 __u32 *retval, __u32 *duration);
+LIBBPF_API int bpf_prog_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_map_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_btf_get_next_id(__u32 start_id, __u32 *next_id);
+LIBBPF_API int bpf_prog_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_map_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_btf_get_fd_by_id(__u32 id);
+LIBBPF_API int bpf_obj_get_info_by_fd(int prog_fd, void *info, __u32 *info_len);
+LIBBPF_API int bpf_prog_query(int target_fd, enum bpf_attach_type type,
+			      __u32 query_flags, __u32 *attach_flags,
+			      __u32 *prog_ids, __u32 *prog_cnt);
+LIBBPF_API int bpf_raw_tracepoint_open(const char *name, int prog_fd);
+LIBBPF_API int bpf_load_btf(void *btf, __u32 btf_size, char *log_buf,
+			    __u32 log_buf_size, bool do_log);
+LIBBPF_API int bpf_task_fd_query(int pid, int fd, __u32 flags, char *buf,
+				 __u32 *buf_len, __u32 *prog_id, __u32 *fd_type,
+				 __u64 *probe_offset, __u64 *probe_addr);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_BPF_H */
diff --git a/src/contrib/libbpf/bpf/bpf_core_read.h b/src/contrib/libbpf/bpf/bpf_core_read.h
new file mode 100644
index 0000000..7009dc9
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_core_read.h
@@ -0,0 +1,263 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_CORE_READ_H__
+#define __BPF_CORE_READ_H__
+
+/*
+ * enum bpf_field_info_kind is passed as a second argument into
+ * __builtin_preserve_field_info() built-in to get a specific aspect of
+ * a field, captured as a first argument. __builtin_preserve_field_info(field,
+ * info_kind) returns __u32 integer and produces BTF field relocation, which
+ * is understood and processed by libbpf during BPF object loading. See
+ * selftests/bpf for examples.
+ */
+enum bpf_field_info_kind {
+	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
+	BPF_FIELD_BYTE_SIZE = 1,
+	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
+	BPF_FIELD_SIGNED = 3,
+	BPF_FIELD_LSHIFT_U64 = 4,
+	BPF_FIELD_RSHIFT_U64 = 5,
+};
+
+#define __CORE_RELO(src, field, info)					      \
+	__builtin_preserve_field_info((src)->field, BPF_FIELD_##info)
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+#define __CORE_BITFIELD_PROBE_READ(dst, src, fld)			      \
+	bpf_probe_read((void *)dst,					      \
+		       __CORE_RELO(src, fld, BYTE_SIZE),		      \
+		       (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+#else
+/* semantics of LSHIFT_64 assumes loading values into low-ordered bytes, so
+ * for big-endian we need to adjust destination pointer accordingly, based on
+ * field byte size
+ */
+#define __CORE_BITFIELD_PROBE_READ(dst, src, fld)			      \
+	bpf_probe_read((void *)dst + (8 - __CORE_RELO(src, fld, BYTE_SIZE)),  \
+		       __CORE_RELO(src, fld, BYTE_SIZE),		      \
+		       (const void *)src + __CORE_RELO(src, fld, BYTE_OFFSET))
+#endif
+
+/*
+ * Extract bitfield, identified by s->field, and return its value as u64.
+ * All this is done in relocatable manner, so bitfield changes such as
+ * signedness, bit size, offset changes, this will be handled automatically.
+ * This version of macro is using bpf_probe_read() to read underlying integer
+ * storage. Macro functions as an expression and its return type is
+ * bpf_probe_read()'s return value: 0, on success, <0 on error.
+ */
+#define BPF_CORE_READ_BITFIELD_PROBED(s, field) ({			      \
+	unsigned long long val = 0;					      \
+									      \
+	__CORE_BITFIELD_PROBE_READ(&val, s, field);			      \
+	val <<= __CORE_RELO(s, field, LSHIFT_U64);			      \
+	if (__CORE_RELO(s, field, SIGNED))				      \
+		val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64);  \
+	else								      \
+		val = val >> __CORE_RELO(s, field, RSHIFT_U64);		      \
+	val;								      \
+})
+
+/*
+ * Extract bitfield, identified by s->field, and return its value as u64.
+ * This version of macro is using direct memory reads and should be used from
+ * BPF program types that support such functionality (e.g., typed raw
+ * tracepoints).
+ */
+#define BPF_CORE_READ_BITFIELD(s, field) ({				      \
+	const void *p = (const void *)s + __CORE_RELO(s, field, BYTE_OFFSET); \
+	unsigned long long val;						      \
+									      \
+	switch (__CORE_RELO(s, field, BYTE_SIZE)) {			      \
+	case 1: val = *(const unsigned char *)p;			      \
+	case 2: val = *(const unsigned short *)p;			      \
+	case 4: val = *(const unsigned int *)p;				      \
+	case 8: val = *(const unsigned long long *)p;			      \
+	}								      \
+	val <<= __CORE_RELO(s, field, LSHIFT_U64);			      \
+	if (__CORE_RELO(s, field, SIGNED))				      \
+		val = ((long long)val) >> __CORE_RELO(s, field, RSHIFT_U64);  \
+	else								      \
+		val = val >> __CORE_RELO(s, field, RSHIFT_U64);		      \
+	val;								      \
+})
+
+/*
+ * Convenience macro to check that field actually exists in target kernel's.
+ * Returns:
+ *    1, if matching field is present in target kernel;
+ *    0, if no matching field found.
+ */
+#define bpf_core_field_exists(field)					    \
+	__builtin_preserve_field_info(field, BPF_FIELD_EXISTS)
+
+/*
+ * Convenience macro to get byte size of a field. Works for integers,
+ * struct/unions, pointers, arrays, and enums.
+ */
+#define bpf_core_field_size(field)					    \
+	__builtin_preserve_field_info(field, BPF_FIELD_BYTE_SIZE)
+
+/*
+ * bpf_core_read() abstracts away bpf_probe_read() call and captures offset
+ * relocation for source address using __builtin_preserve_access_index()
+ * built-in, provided by Clang.
+ *
+ * __builtin_preserve_access_index() takes as an argument an expression of
+ * taking an address of a field within struct/union. It makes compiler emit
+ * a relocation, which records BTF type ID describing root struct/union and an
+ * accessor string which describes exact embedded field that was used to take
+ * an address. See detailed description of this relocation format and
+ * semantics in comments to struct bpf_field_reloc in libbpf_internal.h.
+ *
+ * This relocation allows libbpf to adjust BPF instruction to use correct
+ * actual field offset, based on target kernel BTF type that matches original
+ * (local) BTF, used to record relocation.
+ */
+#define bpf_core_read(dst, sz, src)					    \
+	bpf_probe_read(dst, sz,						    \
+		       (const void *)__builtin_preserve_access_index(src))
+
+/*
+ * bpf_core_read_str() is a thin wrapper around bpf_probe_read_str()
+ * additionally emitting BPF CO-RE field relocation for specified source
+ * argument.
+ */
+#define bpf_core_read_str(dst, sz, src)					    \
+	bpf_probe_read_str(dst, sz,					    \
+			   (const void *)__builtin_preserve_access_index(src))
+
+#define ___concat(a, b) a ## b
+#define ___apply(fn, n) ___concat(fn, n)
+#define ___nth(_1, _2, _3, _4, _5, _6, _7, _8, _9, _10, __11, N, ...) N
+
+/*
+ * return number of provided arguments; used for switch-based variadic macro
+ * definitions (see ___last, ___arrow, etc below)
+ */
+#define ___narg(...) ___nth(_, ##__VA_ARGS__, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
+/*
+ * return 0 if no arguments are passed, N - otherwise; used for
+ * recursively-defined macros to specify termination (0) case, and generic
+ * (N) case (e.g., ___read_ptrs, ___core_read)
+ */
+#define ___empty(...) ___nth(_, ##__VA_ARGS__, N, N, N, N, N, N, N, N, N, N, 0)
+
+#define ___last1(x) x
+#define ___last2(a, x) x
+#define ___last3(a, b, x) x
+#define ___last4(a, b, c, x) x
+#define ___last5(a, b, c, d, x) x
+#define ___last6(a, b, c, d, e, x) x
+#define ___last7(a, b, c, d, e, f, x) x
+#define ___last8(a, b, c, d, e, f, g, x) x
+#define ___last9(a, b, c, d, e, f, g, h, x) x
+#define ___last10(a, b, c, d, e, f, g, h, i, x) x
+#define ___last(...) ___apply(___last, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___nolast2(a, _) a
+#define ___nolast3(a, b, _) a, b
+#define ___nolast4(a, b, c, _) a, b, c
+#define ___nolast5(a, b, c, d, _) a, b, c, d
+#define ___nolast6(a, b, c, d, e, _) a, b, c, d, e
+#define ___nolast7(a, b, c, d, e, f, _) a, b, c, d, e, f
+#define ___nolast8(a, b, c, d, e, f, g, _) a, b, c, d, e, f, g
+#define ___nolast9(a, b, c, d, e, f, g, h, _) a, b, c, d, e, f, g, h
+#define ___nolast10(a, b, c, d, e, f, g, h, i, _) a, b, c, d, e, f, g, h, i
+#define ___nolast(...) ___apply(___nolast, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___arrow1(a) a
+#define ___arrow2(a, b) a->b
+#define ___arrow3(a, b, c) a->b->c
+#define ___arrow4(a, b, c, d) a->b->c->d
+#define ___arrow5(a, b, c, d, e) a->b->c->d->e
+#define ___arrow6(a, b, c, d, e, f) a->b->c->d->e->f
+#define ___arrow7(a, b, c, d, e, f, g) a->b->c->d->e->f->g
+#define ___arrow8(a, b, c, d, e, f, g, h) a->b->c->d->e->f->g->h
+#define ___arrow9(a, b, c, d, e, f, g, h, i) a->b->c->d->e->f->g->h->i
+#define ___arrow10(a, b, c, d, e, f, g, h, i, j) a->b->c->d->e->f->g->h->i->j
+#define ___arrow(...) ___apply(___arrow, ___narg(__VA_ARGS__))(__VA_ARGS__)
+
+#define ___type(...) typeof(___arrow(__VA_ARGS__))
+
+#define ___read(read_fn, dst, src_type, src, accessor)			    \
+	read_fn((void *)(dst), sizeof(*(dst)), &((src_type)(src))->accessor)
+
+/* "recursively" read a sequence of inner pointers using local __t var */
+#define ___rd_first(src, a) ___read(bpf_core_read, &__t, ___type(src), src, a);
+#define ___rd_last(...)							    \
+	___read(bpf_core_read, &__t,					    \
+		___type(___nolast(__VA_ARGS__)), __t, ___last(__VA_ARGS__));
+#define ___rd_p1(...) const void *__t; ___rd_first(__VA_ARGS__)
+#define ___rd_p2(...) ___rd_p1(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p3(...) ___rd_p2(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p4(...) ___rd_p3(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p5(...) ___rd_p4(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p6(...) ___rd_p5(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p7(...) ___rd_p6(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p8(...) ___rd_p7(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___rd_p9(...) ___rd_p8(___nolast(__VA_ARGS__)) ___rd_last(__VA_ARGS__)
+#define ___read_ptrs(src, ...)						    \
+	___apply(___rd_p, ___narg(__VA_ARGS__))(src, __VA_ARGS__)
+
+#define ___core_read0(fn, dst, src, a)					    \
+	___read(fn, dst, ___type(src), src, a);
+#define ___core_readN(fn, dst, src, ...)				    \
+	___read_ptrs(src, ___nolast(__VA_ARGS__))			    \
+	___read(fn, dst, ___type(src, ___nolast(__VA_ARGS__)), __t,	    \
+		___last(__VA_ARGS__));
+#define ___core_read(fn, dst, src, a, ...)				    \
+	___apply(___core_read, ___empty(__VA_ARGS__))(fn, dst,		    \
+						      src, a, ##__VA_ARGS__)
+
+/*
+ * BPF_CORE_READ_INTO() is a more performance-conscious variant of
+ * BPF_CORE_READ(), in which final field is read into user-provided storage.
+ * See BPF_CORE_READ() below for more details on general usage.
+ */
+#define BPF_CORE_READ_INTO(dst, src, a, ...)				    \
+	({								    \
+		___core_read(bpf_core_read, dst, src, a, ##__VA_ARGS__)	    \
+	})
+
+/*
+ * BPF_CORE_READ_STR_INTO() does same "pointer chasing" as
+ * BPF_CORE_READ() for intermediate pointers, but then executes (and returns
+ * corresponding error code) bpf_core_read_str() for final string read.
+ */
+#define BPF_CORE_READ_STR_INTO(dst, src, a, ...)			    \
+	({								    \
+		___core_read(bpf_core_read_str, dst, src, a, ##__VA_ARGS__) \
+	})
+
+/*
+ * BPF_CORE_READ() is used to simplify BPF CO-RE relocatable read, especially
+ * when there are few pointer chasing steps.
+ * E.g., what in non-BPF world (or in BPF w/ BCC) would be something like:
+ *	int x = s->a.b.c->d.e->f->g;
+ * can be succinctly achieved using BPF_CORE_READ as:
+ *	int x = BPF_CORE_READ(s, a.b.c, d.e, f, g);
+ *
+ * BPF_CORE_READ will decompose above statement into 4 bpf_core_read (BPF
+ * CO-RE relocatable bpf_probe_read() wrapper) calls, logically equivalent to:
+ * 1. const void *__t = s->a.b.c;
+ * 2. __t = __t->d.e;
+ * 3. __t = __t->f;
+ * 4. return __t->g;
+ *
+ * Equivalence is logical, because there is a heavy type casting/preservation
+ * involved, as well as all the reads are happening through bpf_probe_read()
+ * calls using __builtin_preserve_access_index() to emit CO-RE relocations.
+ *
+ * N.B. Only up to 9 "field accessors" are supported, which should be more
+ * than enough for any practical purpose.
+ */
+#define BPF_CORE_READ(src, a, ...)					    \
+	({								    \
+		___type(src, a, ##__VA_ARGS__) __r;			    \
+		BPF_CORE_READ_INTO(&__r, src, a, ##__VA_ARGS__);	    \
+		__r;							    \
+	})
+
+#endif
+
diff --git a/src/contrib/libbpf/bpf/bpf_endian.h b/src/contrib/libbpf/bpf/bpf_endian.h
new file mode 100644
index 0000000..fbe2800
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_endian.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_ENDIAN__
+#define __BPF_ENDIAN__
+
+#include <linux/stddef.h>
+#include <linux/swab.h>
+
+/* LLVM's BPF target selects the endianness of the CPU
+ * it compiles on, or the user specifies (bpfel/bpfeb),
+ * respectively. The used __BYTE_ORDER__ is defined by
+ * the compiler, we cannot rely on __BYTE_ORDER from
+ * libc headers, since it doesn't reflect the actual
+ * requested byte order.
+ *
+ * Note, LLVM's BPF target has different __builtin_bswapX()
+ * semantics. It does map to BPF_ALU | BPF_END | BPF_TO_BE
+ * in bpfel and bpfeb case, which means below, that we map
+ * to cpu_to_be16(). We could use it unconditionally in BPF
+ * case, but better not rely on it, so that this header here
+ * can be used from application and BPF program side, which
+ * use different targets.
+ */
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+# define __bpf_ntohs(x)			__builtin_bswap16(x)
+# define __bpf_htons(x)			__builtin_bswap16(x)
+# define __bpf_constant_ntohs(x)	___constant_swab16(x)
+# define __bpf_constant_htons(x)	___constant_swab16(x)
+# define __bpf_ntohl(x)			__builtin_bswap32(x)
+# define __bpf_htonl(x)			__builtin_bswap32(x)
+# define __bpf_constant_ntohl(x)	___constant_swab32(x)
+# define __bpf_constant_htonl(x)	___constant_swab32(x)
+# define __bpf_be64_to_cpu(x)		__builtin_bswap64(x)
+# define __bpf_cpu_to_be64(x)		__builtin_bswap64(x)
+# define __bpf_constant_be64_to_cpu(x)	___constant_swab64(x)
+# define __bpf_constant_cpu_to_be64(x)	___constant_swab64(x)
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
+# define __bpf_ntohs(x)			(x)
+# define __bpf_htons(x)			(x)
+# define __bpf_constant_ntohs(x)	(x)
+# define __bpf_constant_htons(x)	(x)
+# define __bpf_ntohl(x)			(x)
+# define __bpf_htonl(x)			(x)
+# define __bpf_constant_ntohl(x)	(x)
+# define __bpf_constant_htonl(x)	(x)
+# define __bpf_be64_to_cpu(x)		(x)
+# define __bpf_cpu_to_be64(x)		(x)
+# define __bpf_constant_be64_to_cpu(x)  (x)
+# define __bpf_constant_cpu_to_be64(x)  (x)
+#else
+# error "Fix your compiler's __BYTE_ORDER__?!"
+#endif
+
+#define bpf_htons(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_htons(x) : __bpf_htons(x))
+#define bpf_ntohs(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_ntohs(x) : __bpf_ntohs(x))
+#define bpf_htonl(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_htonl(x) : __bpf_htonl(x))
+#define bpf_ntohl(x)				\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_ntohl(x) : __bpf_ntohl(x))
+#define bpf_cpu_to_be64(x)			\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_cpu_to_be64(x) : __bpf_cpu_to_be64(x))
+#define bpf_be64_to_cpu(x)			\
+	(__builtin_constant_p(x) ?		\
+	 __bpf_constant_be64_to_cpu(x) : __bpf_be64_to_cpu(x))
+
+#endif /* __BPF_ENDIAN__ */
diff --git a/src/contrib/libbpf/bpf/bpf_helper_defs.h b/src/contrib/libbpf/bpf/bpf_helper_defs.h
new file mode 100644
index 0000000..1f357f6
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_helper_defs.h
@@ -0,0 +1,2759 @@
+/* This is auto-generated file. See bpf_helpers_doc.py for details. */
+
+/* Forward declarations of BPF structs */
+struct bpf_fib_lookup;
+struct bpf_perf_event_data;
+struct bpf_perf_event_value;
+struct bpf_sock;
+struct bpf_sock_addr;
+struct bpf_sock_ops;
+struct bpf_sock_tuple;
+struct bpf_spin_lock;
+struct bpf_sysctl;
+struct bpf_tcp_sock;
+struct bpf_tunnel_key;
+struct bpf_xfrm_state;
+struct pt_regs;
+struct sk_reuseport_md;
+struct sockaddr;
+struct tcphdr;
+struct __sk_buff;
+struct sk_msg_md;
+struct xdp_md;
+
+/*
+ * bpf_map_lookup_elem
+ *
+ * 	Perform a lookup in *map* for an entry associated to *key*.
+ *
+ * Returns
+ * 	Map value associated to *key*, or **NULL** if no entry was
+ * 	found.
+ */
+static void *(*bpf_map_lookup_elem)(void *map, const void *key) = (void *) 1;
+
+/*
+ * bpf_map_update_elem
+ *
+ * 	Add or update the value of the entry associated to *key* in
+ * 	*map* with *value*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	Flag value **BPF_NOEXIST** cannot be used for maps of types
+ * 	**BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
+ * 	elements always exist), the helper would return an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_map_update_elem)(void *map, const void *key, const void *value, __u64 flags) = (void *) 2;
+
+/*
+ * bpf_map_delete_elem
+ *
+ * 	Delete entry with *key* from *map*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_map_delete_elem)(void *map, const void *key) = (void *) 3;
+
+/*
+ * bpf_probe_read
+ *
+ * 	For tracing programs, safely attempt to read *size* bytes from
+ * 	kernel space address *unsafe_ptr* and store the data in *dst*.
+ *
+ * 	Generally, use bpf_probe_read_user() or bpf_probe_read_kernel()
+ * 	instead.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_probe_read)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 4;
+
+/*
+ * bpf_ktime_get_ns
+ *
+ * 	Return the time elapsed since system boot, in nanoseconds.
+ *
+ * Returns
+ * 	Current *ktime*.
+ */
+static __u64 (*bpf_ktime_get_ns)(void) = (void *) 5;
+
+/*
+ * bpf_trace_printk
+ *
+ * 	This helper is a "printk()-like" facility for debugging. It
+ * 	prints a message defined by format *fmt* (of size *fmt_size*)
+ * 	to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 	available. It can take up to three additional **u64**
+ * 	arguments (as an eBPF helpers, the total number of arguments is
+ * 	limited to five).
+ *
+ * 	Each time the helper is called, it appends a line to the trace.
+ * 	Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
+ * 	open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 	The format of the trace is customizable, and the exact output
+ * 	one will get depends on the options set in
+ * 	*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 	*README* file under the same directory). However, it usually
+ * 	defaults to something like:
+ *
+ * 	::
+ *
+ * 		telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
+ *
+ * 	In the above:
+ *
+ * 		* ``telnet`` is the name of the current task.
+ * 		* ``470`` is the PID of the current task.
+ * 		* ``001`` is the CPU number on which the task is
+ * 		  running.
+ * 		* In ``.N..``, each character refers to a set of
+ * 		  options (whether irqs are enabled, scheduling
+ * 		  options, whether hard/softirqs are running, level of
+ * 		  preempt_disabled respectively). **N** means that
+ * 		  **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
+ * 		  are set.
+ * 		* ``419421.045894`` is a timestamp.
+ * 		* ``0x00000001`` is a fake value used by BPF for the
+ * 		  instruction pointer register.
+ * 		* ``<formatted msg>`` is the message formatted with
+ * 		  *fmt*.
+ *
+ * 	The conversion specifiers supported by *fmt* are similar, but
+ * 	more limited than for printk(). They are **%d**, **%i**,
+ * 	**%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
+ * 	**%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
+ * 	of field, padding with zeroes, etc.) is available, and the
+ * 	helper will return **-EINVAL** (but print nothing) if it
+ * 	encounters an unknown specifier.
+ *
+ * 	Also, note that **bpf_trace_printk**\ () is slow, and should
+ * 	only be used for debugging purposes. For this reason, a notice
+ * 	bloc (spanning several lines) is printed to kernel logs and
+ * 	states that the helper should not be used "for production use"
+ * 	the first time this helper is used (or more precisely, when
+ * 	**trace_printk**\ () buffers are allocated). For passing values
+ * 	to user space, perf events should be preferred.
+ *
+ * Returns
+ * 	The number of bytes written to the buffer, or a negative error
+ * 	in case of failure.
+ */
+static int (*bpf_trace_printk)(const char *fmt, __u32 fmt_size, ...) = (void *) 6;
+
+/*
+ * bpf_get_prandom_u32
+ *
+ * 	Get a pseudo-random number.
+ *
+ * 	From a security point of view, this helper uses its own
+ * 	pseudo-random internal state, and cannot be used to infer the
+ * 	seed of other random functions in the kernel. However, it is
+ * 	essential to note that the generator used by the helper is not
+ * 	cryptographically secure.
+ *
+ * Returns
+ * 	A random 32-bit unsigned value.
+ */
+static __u32 (*bpf_get_prandom_u32)(void) = (void *) 7;
+
+/*
+ * bpf_get_smp_processor_id
+ *
+ * 	Get the SMP (symmetric multiprocessing) processor id. Note that
+ * 	all programs run with preemption disabled, which means that the
+ * 	SMP processor id is stable during all the execution of the
+ * 	program.
+ *
+ * Returns
+ * 	The SMP id of the processor running the program.
+ */
+static __u32 (*bpf_get_smp_processor_id)(void) = (void *) 8;
+
+/*
+ * bpf_skb_store_bytes
+ *
+ * 	Store *len* bytes from address *from* into the packet
+ * 	associated to *skb*, at *offset*. *flags* are a combination of
+ * 	**BPF_F_RECOMPUTE_CSUM** (automatically recompute the
+ * 	checksum for the packet after storing the bytes) and
+ * 	**BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
+ * 	**->swhash** and *skb*\ **->l4hash** to 0).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_store_bytes)(struct __sk_buff *skb, __u32 offset, const void *from, __u32 len, __u64 flags) = (void *) 9;
+
+/*
+ * bpf_l3_csum_replace
+ *
+ * 	Recompute the layer 3 (e.g. IP) checksum for the packet
+ * 	associated to *skb*. Computation is incremental, so the helper
+ * 	must know the former value of the header field that was
+ * 	modified (*from*), the new value of this field (*to*), and the
+ * 	number of bytes (2 or 4) for this field, stored in *size*.
+ * 	Alternatively, it is possible to store the difference between
+ * 	the previous and the new values of the header field in *to*, by
+ * 	setting *from* and *size* to 0. For both methods, *offset*
+ * 	indicates the location of the IP checksum within the packet.
+ *
+ * 	This helper works in combination with **bpf_csum_diff**\ (),
+ * 	which does not update the checksum in-place, but offers more
+ * 	flexibility and can handle sizes larger than 2 or 4 for the
+ * 	checksum to update.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_l3_csum_replace)(struct __sk_buff *skb, __u32 offset, __u64 from, __u64 to, __u64 size) = (void *) 10;
+
+/*
+ * bpf_l4_csum_replace
+ *
+ * 	Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
+ * 	packet associated to *skb*. Computation is incremental, so the
+ * 	helper must know the former value of the header field that was
+ * 	modified (*from*), the new value of this field (*to*), and the
+ * 	number of bytes (2 or 4) for this field, stored on the lowest
+ * 	four bits of *flags*. Alternatively, it is possible to store
+ * 	the difference between the previous and the new values of the
+ * 	header field in *to*, by setting *from* and the four lowest
+ * 	bits of *flags* to 0. For both methods, *offset* indicates the
+ * 	location of the IP checksum within the packet. In addition to
+ * 	the size of the field, *flags* can be added (bitwise OR) actual
+ * 	flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
+ * 	untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
+ * 	for updates resulting in a null checksum the value is set to
+ * 	**CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
+ * 	the checksum is to be computed against a pseudo-header.
+ *
+ * 	This helper works in combination with **bpf_csum_diff**\ (),
+ * 	which does not update the checksum in-place, but offers more
+ * 	flexibility and can handle sizes larger than 2 or 4 for the
+ * 	checksum to update.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_l4_csum_replace)(struct __sk_buff *skb, __u32 offset, __u64 from, __u64 to, __u64 flags) = (void *) 11;
+
+/*
+ * bpf_tail_call
+ *
+ * 	This special helper is used to trigger a "tail call", or in
+ * 	other words, to jump into another eBPF program. The same stack
+ * 	frame is used (but values on stack and in registers for the
+ * 	caller are not accessible to the callee). This mechanism allows
+ * 	for program chaining, either for raising the maximum number of
+ * 	available eBPF instructions, or to execute given programs in
+ * 	conditional blocks. For security reasons, there is an upper
+ * 	limit to the number of successive tail calls that can be
+ * 	performed.
+ *
+ * 	Upon call of this helper, the program attempts to jump into a
+ * 	program referenced at index *index* in *prog_array_map*, a
+ * 	special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
+ * 	*ctx*, a pointer to the context.
+ *
+ * 	If the call succeeds, the kernel immediately runs the first
+ * 	instruction of the new program. This is not a function call,
+ * 	and it never returns to the previous program. If the call
+ * 	fails, then the helper has no effect, and the caller continues
+ * 	to run its subsequent instructions. A call can fail if the
+ * 	destination program for the jump does not exist (i.e. *index*
+ * 	is superior to the number of entries in *prog_array_map*), or
+ * 	if the maximum number of tail calls has been reached for this
+ * 	chain of programs. This limit is defined in the kernel by the
+ * 	macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
+ * 	which is currently set to 32.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_tail_call)(void *ctx, void *prog_array_map, __u32 index) = (void *) 12;
+
+/*
+ * bpf_clone_redirect
+ *
+ * 	Clone and redirect the packet associated to *skb* to another
+ * 	net device of index *ifindex*. Both ingress and egress
+ * 	interfaces can be used for redirection. The **BPF_F_INGRESS**
+ * 	value in *flags* is used to make the distinction (ingress path
+ * 	is selected if the flag is present, egress path otherwise).
+ * 	This is the only flag supported for now.
+ *
+ * 	In comparison with **bpf_redirect**\ () helper,
+ * 	**bpf_clone_redirect**\ () has the associated cost of
+ * 	duplicating the packet buffer, but this can be executed out of
+ * 	the eBPF program. Conversely, **bpf_redirect**\ () is more
+ * 	efficient, but it is handled through an action code where the
+ * 	redirection happens only after the eBPF program has returned.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_clone_redirect)(struct __sk_buff *skb, __u32 ifindex, __u64 flags) = (void *) 13;
+
+/*
+ * bpf_get_current_pid_tgid
+ *
+ *
+ * Returns
+ * 	A 64-bit integer containing the current tgid and pid, and
+ * 	created as such:
+ * 	*current_task*\ **->tgid << 32 \|**
+ * 	*current_task*\ **->pid**.
+ */
+static __u64 (*bpf_get_current_pid_tgid)(void) = (void *) 14;
+
+/*
+ * bpf_get_current_uid_gid
+ *
+ *
+ * Returns
+ * 	A 64-bit integer containing the current GID and UID, and
+ * 	created as such: *current_gid* **<< 32 \|** *current_uid*.
+ */
+static __u64 (*bpf_get_current_uid_gid)(void) = (void *) 15;
+
+/*
+ * bpf_get_current_comm
+ *
+ * 	Copy the **comm** attribute of the current task into *buf* of
+ * 	*size_of_buf*. The **comm** attribute contains the name of
+ * 	the executable (excluding the path) for the current task. The
+ * 	*size_of_buf* must be strictly positive. On success, the
+ * 	helper makes sure that the *buf* is NUL-terminated. On failure,
+ * 	it is filled with zeroes.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_get_current_comm)(void *buf, __u32 size_of_buf) = (void *) 16;
+
+/*
+ * bpf_get_cgroup_classid
+ *
+ * 	Retrieve the classid for the current task, i.e. for the net_cls
+ * 	cgroup to which *skb* belongs.
+ *
+ * 	This helper can be used on TC egress path, but not on ingress.
+ *
+ * 	The net_cls cgroup provides an interface to tag network packets
+ * 	based on a user-provided identifier for all traffic coming from
+ * 	the tasks belonging to the related cgroup. See also the related
+ * 	kernel documentation, available from the Linux sources in file
+ * 	*Documentation/admin-guide/cgroup-v1/net_cls.rst*.
+ *
+ * 	The Linux kernel has two versions for cgroups: there are
+ * 	cgroups v1 and cgroups v2. Both are available to users, who can
+ * 	use a mixture of them, but note that the net_cls cgroup is for
+ * 	cgroup v1 only. This makes it incompatible with BPF programs
+ * 	run on cgroups, which is a cgroup-v2-only feature (a socket can
+ * 	only hold data for one version of cgroups at a time).
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
+ * 	"**y**" or to "**m**".
+ *
+ * Returns
+ * 	The classid, or 0 for the default unconfigured classid.
+ */
+static __u32 (*bpf_get_cgroup_classid)(struct __sk_buff *skb) = (void *) 17;
+
+/*
+ * bpf_skb_vlan_push
+ *
+ * 	Push a *vlan_tci* (VLAN tag control information) of protocol
+ * 	*vlan_proto* to the packet associated to *skb*, then update
+ * 	the checksum. Note that if *vlan_proto* is different from
+ * 	**ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
+ * 	be **ETH_P_8021Q**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_vlan_push)(struct __sk_buff *skb, __be16 vlan_proto, __u16 vlan_tci) = (void *) 18;
+
+/*
+ * bpf_skb_vlan_pop
+ *
+ * 	Pop a VLAN header from the packet associated to *skb*.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_vlan_pop)(struct __sk_buff *skb) = (void *) 19;
+
+/*
+ * bpf_skb_get_tunnel_key
+ *
+ * 	Get tunnel metadata. This helper takes a pointer *key* to an
+ * 	empty **struct bpf_tunnel_key** of **size**, that will be
+ * 	filled with tunnel metadata for the packet associated to *skb*.
+ * 	The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
+ * 	indicates that the tunnel is based on IPv6 protocol instead of
+ * 	IPv4.
+ *
+ * 	The **struct bpf_tunnel_key** is an object that generalizes the
+ * 	principal parameters used by various tunneling protocols into a
+ * 	single struct. This way, it can be used to easily make a
+ * 	decision based on the contents of the encapsulation header,
+ * 	"summarized" in this struct. In particular, it holds the IP
+ * 	address of the remote end (IPv4 or IPv6, depending on the case)
+ * 	in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
+ * 	this struct exposes the *key*\ **->tunnel_id**, which is
+ * 	generally mapped to a VNI (Virtual Network Identifier), making
+ * 	it programmable together with the **bpf_skb_set_tunnel_key**\
+ * 	() helper.
+ *
+ * 	Let's imagine that the following code is part of a program
+ * 	attached to the TC ingress interface, on one end of a GRE
+ * 	tunnel, and is supposed to filter out all messages coming from
+ * 	remote ends with IPv4 address other than 10.0.0.1:
+ *
+ * 	::
+ *
+ * 		int ret;
+ * 		struct bpf_tunnel_key key = {};
+ * 		
+ * 		ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
+ * 		if (ret < 0)
+ * 			return TC_ACT_SHOT;	// drop packet
+ * 		
+ * 		if (key.remote_ipv4 != 0x0a000001)
+ * 			return TC_ACT_SHOT;	// drop packet
+ * 		
+ * 		return TC_ACT_OK;		// accept packet
+ *
+ * 	This interface can also be used with all encapsulation devices
+ * 	that can operate in "collect metadata" mode: instead of having
+ * 	one network device per specific configuration, the "collect
+ * 	metadata" mode only requires a single device where the
+ * 	configuration can be extracted from this helper.
+ *
+ * 	This can be used together with various tunnels such as VXLan,
+ * 	Geneve, GRE or IP in IP (IPIP).
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_get_tunnel_key)(struct __sk_buff *skb, struct bpf_tunnel_key *key, __u32 size, __u64 flags) = (void *) 20;
+
+/*
+ * bpf_skb_set_tunnel_key
+ *
+ * 	Populate tunnel metadata for packet associated to *skb.* The
+ * 	tunnel metadata is set to the contents of *key*, of *size*. The
+ * 	*flags* can be set to a combination of the following values:
+ *
+ * 	**BPF_F_TUNINFO_IPV6**
+ * 		Indicate that the tunnel is based on IPv6 protocol
+ * 		instead of IPv4.
+ * 	**BPF_F_ZERO_CSUM_TX**
+ * 		For IPv4 packets, add a flag to tunnel metadata
+ * 		indicating that checksum computation should be skipped
+ * 		and checksum set to zeroes.
+ * 	**BPF_F_DONT_FRAGMENT**
+ * 		Add a flag to tunnel metadata indicating that the
+ * 		packet should not be fragmented.
+ * 	**BPF_F_SEQ_NUMBER**
+ * 		Add a flag to tunnel metadata indicating that a
+ * 		sequence number should be added to tunnel header before
+ * 		sending the packet. This flag was added for GRE
+ * 		encapsulation, but might be used with other protocols
+ * 		as well in the future.
+ *
+ * 	Here is a typical usage on the transmit path:
+ *
+ * 	::
+ *
+ * 		struct bpf_tunnel_key key;
+ * 		     populate key ...
+ * 		bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
+ * 		bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
+ *
+ * 	See also the description of the **bpf_skb_get_tunnel_key**\ ()
+ * 	helper for additional information.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_set_tunnel_key)(struct __sk_buff *skb, struct bpf_tunnel_key *key, __u32 size, __u64 flags) = (void *) 21;
+
+/*
+ * bpf_perf_event_read
+ *
+ * 	Read the value of a perf event counter. This helper relies on a
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
+ * 	the perf event counter is selected when *map* is updated with
+ * 	perf event file descriptors. The *map* is an array whose size
+ * 	is the number of available CPUs, and each cell contains a value
+ * 	relative to one CPU. The value to retrieve is indicated by
+ * 	*flags*, that contains the index of the CPU to look up, masked
+ * 	with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 	**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 	current CPU should be retrieved.
+ *
+ * 	Note that before Linux 4.13, only hardware perf event can be
+ * 	retrieved.
+ *
+ * 	Also, be aware that the newer helper
+ * 	**bpf_perf_event_read_value**\ () is recommended over
+ * 	**bpf_perf_event_read**\ () in general. The latter has some ABI
+ * 	quirks where error and counter value are used as a return code
+ * 	(which is wrong to do since ranges may overlap). This issue is
+ * 	fixed with **bpf_perf_event_read_value**\ (), which at the same
+ * 	time provides more features over the **bpf_perf_event_read**\
+ * 	() interface. Please refer to the description of
+ * 	**bpf_perf_event_read_value**\ () for details.
+ *
+ * Returns
+ * 	The value of the perf event counter read from the map, or a
+ * 	negative error code in case of failure.
+ */
+static __u64 (*bpf_perf_event_read)(void *map, __u64 flags) = (void *) 22;
+
+/*
+ * bpf_redirect
+ *
+ * 	Redirect the packet to another net device of index *ifindex*.
+ * 	This helper is somewhat similar to **bpf_clone_redirect**\
+ * 	(), except that the packet is not cloned, which provides
+ * 	increased performance.
+ *
+ * 	Except for XDP, both ingress and egress interfaces can be used
+ * 	for redirection. The **BPF_F_INGRESS** value in *flags* is used
+ * 	to make the distinction (ingress path is selected if the flag
+ * 	is present, egress path otherwise). Currently, XDP only
+ * 	supports redirection to the egress interface, and accepts no
+ * 	flag at all.
+ *
+ * 	The same effect can be attained with the more generic
+ * 	**bpf_redirect_map**\ (), which requires specific maps to be
+ * 	used but offers better performance.
+ *
+ * Returns
+ * 	For XDP, the helper returns **XDP_REDIRECT** on success or
+ * 	**XDP_ABORTED** on error. For other program types, the values
+ * 	are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
+ * 	error.
+ */
+static int (*bpf_redirect)(__u32 ifindex, __u64 flags) = (void *) 23;
+
+/*
+ * bpf_get_route_realm
+ *
+ * 	Retrieve the realm or the route, that is to say the
+ * 	**tclassid** field of the destination for the *skb*. The
+ * 	indentifier retrieved is a user-provided tag, similar to the
+ * 	one used with the net_cls cgroup (see description for
+ * 	**bpf_get_cgroup_classid**\ () helper), but here this tag is
+ * 	held by a route (a destination entry), not by a task.
+ *
+ * 	Retrieving this identifier works with the clsact TC egress hook
+ * 	(see also **tc-bpf(8)**), or alternatively on conventional
+ * 	classful egress qdiscs, but not on TC ingress path. In case of
+ * 	clsact TC egress hook, this has the advantage that, internally,
+ * 	the destination entry has not been dropped yet in the transmit
+ * 	path. Therefore, the destination entry does not need to be
+ * 	artificially held via **netif_keep_dst**\ () for a classful
+ * 	qdisc until the *skb* is freed.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_IP_ROUTE_CLASSID** configuration option.
+ *
+ * Returns
+ * 	The realm of the route for the packet associated to *skb*, or 0
+ * 	if none was found.
+ */
+static __u32 (*bpf_get_route_realm)(struct __sk_buff *skb) = (void *) 24;
+
+/*
+ * bpf_perf_event_output
+ *
+ * 	Write raw *data* blob into a special BPF perf event held by
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 	event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 	as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 	**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 	The *flags* are used to indicate the index in *map* for which
+ * 	the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 	Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 	to indicate that the index of the current CPU core should be
+ * 	used.
+ *
+ * 	The value to write, of *size*, is passed through eBPF stack and
+ * 	pointed by *data*.
+ *
+ * 	The context of the program *ctx* needs also be passed to the
+ * 	helper.
+ *
+ * 	On user space, a program willing to read the values needs to
+ * 	call **perf_event_open**\ () on the perf event (either for
+ * 	one or for all CPUs) and to store the file descriptor into the
+ * 	*map*. This must be done before the eBPF program can send data
+ * 	into it. An example is available in file
+ * 	*samples/bpf/trace_output_user.c* in the Linux kernel source
+ * 	tree (the eBPF program counterpart is in
+ * 	*samples/bpf/trace_output_kern.c*).
+ *
+ * 	**bpf_perf_event_output**\ () achieves better performance
+ * 	than **bpf_trace_printk**\ () for sharing data with user
+ * 	space, and is much better suitable for streaming data from eBPF
+ * 	programs.
+ *
+ * 	Note that this helper is not restricted to tracing use cases
+ * 	and can be used with programs attached to TC or XDP as well,
+ * 	where it allows for passing data to user space listeners. Data
+ * 	can be:
+ *
+ * 	* Only custom structs,
+ * 	* Only the packet payload, or
+ * 	* A combination of both.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_perf_event_output)(void *ctx, void *map, __u64 flags, void *data, __u64 size) = (void *) 25;
+
+/*
+ * bpf_skb_load_bytes
+ *
+ * 	This helper was provided as an easy way to load data from a
+ * 	packet. It can be used to load *len* bytes from *offset* from
+ * 	the packet associated to *skb*, into the buffer pointed by
+ * 	*to*.
+ *
+ * 	Since Linux 4.7, usage of this helper has mostly been replaced
+ * 	by "direct packet access", enabling packet data to be
+ * 	manipulated with *skb*\ **->data** and *skb*\ **->data_end**
+ * 	pointing respectively to the first byte of packet data and to
+ * 	the byte after the last byte of packet data. However, it
+ * 	remains useful if one wishes to read large quantities of data
+ * 	at once from a packet into the eBPF stack.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_load_bytes)(const void *skb, __u32 offset, void *to, __u32 len) = (void *) 26;
+
+/*
+ * bpf_get_stackid
+ *
+ * 	Walk a user or a kernel stack and return its id. To achieve
+ * 	this, the helper needs *ctx*, which is a pointer to the context
+ * 	on which the tracing program is executed, and a pointer to a
+ * 	*map* of type **BPF_MAP_TYPE_STACK_TRACE**.
+ *
+ * 	The last argument, *flags*, holds the number of stack frames to
+ * 	skip (from 0 to 255), masked with
+ * 	**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 	a combination of the following flags:
+ *
+ * 	**BPF_F_USER_STACK**
+ * 		Collect a user space stack instead of a kernel stack.
+ * 	**BPF_F_FAST_STACK_CMP**
+ * 		Compare stacks by hash only.
+ * 	**BPF_F_REUSE_STACKID**
+ * 		If two different stacks hash into the same *stackid*,
+ * 		discard the old one.
+ *
+ * 	The stack id retrieved is a 32 bit long integer handle which
+ * 	can be further combined with other data (including other stack
+ * 	ids) and used as a key into maps. This can be useful for
+ * 	generating a variety of graphs (such as flame graphs or off-cpu
+ * 	graphs).
+ *
+ * 	For walking a stack, this helper is an improvement over
+ * 	**bpf_probe_read**\ (), which can be used with unrolled loops
+ * 	but is not efficient and consumes a lot of eBPF instructions.
+ * 	Instead, **bpf_get_stackid**\ () can collect up to
+ * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
+ * 	this limit can be controlled with the **sysctl** program, and
+ * 	that it should be manually increased in order to profile long
+ * 	user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 	::
+ *
+ * 		# sysctl kernel.perf_event_max_stack=<new value>
+ *
+ * Returns
+ * 	The positive or null stack id on success, or a negative error
+ * 	in case of failure.
+ */
+static int (*bpf_get_stackid)(void *ctx, void *map, __u64 flags) = (void *) 27;
+
+/*
+ * bpf_csum_diff
+ *
+ * 	Compute a checksum difference, from the raw buffer pointed by
+ * 	*from*, of length *from_size* (that must be a multiple of 4),
+ * 	towards the raw buffer pointed by *to*, of size *to_size*
+ * 	(same remark). An optional *seed* can be added to the value
+ * 	(this can be cascaded, the seed may come from a previous call
+ * 	to the helper).
+ *
+ * 	This is flexible enough to be used in several ways:
+ *
+ * 	* With *from_size* == 0, *to_size* > 0 and *seed* set to
+ * 	  checksum, it can be used when pushing new data.
+ * 	* With *from_size* > 0, *to_size* == 0 and *seed* set to
+ * 	  checksum, it can be used when removing data from a packet.
+ * 	* With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
+ * 	  can be used to compute a diff. Note that *from_size* and
+ * 	  *to_size* do not need to be equal.
+ *
+ * 	This helper can be used in combination with
+ * 	**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
+ * 	which one can feed in the difference computed with
+ * 	**bpf_csum_diff**\ ().
+ *
+ * Returns
+ * 	The checksum result, or a negative error code in case of
+ * 	failure.
+ */
+static __s64 (*bpf_csum_diff)(__be32 *from, __u32 from_size, __be32 *to, __u32 to_size, __wsum seed) = (void *) 28;
+
+/*
+ * bpf_skb_get_tunnel_opt
+ *
+ * 	Retrieve tunnel options metadata for the packet associated to
+ * 	*skb*, and store the raw tunnel option data to the buffer *opt*
+ * 	of *size*.
+ *
+ * 	This helper can be used with encapsulation devices that can
+ * 	operate in "collect metadata" mode (please refer to the related
+ * 	note in the description of **bpf_skb_get_tunnel_key**\ () for
+ * 	more details). A particular example where this can be used is
+ * 	in combination with the Geneve encapsulation protocol, where it
+ * 	allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
+ * 	and retrieving arbitrary TLVs (Type-Length-Value headers) from
+ * 	the eBPF program. This allows for full customization of these
+ * 	headers.
+ *
+ * Returns
+ * 	The size of the option data retrieved.
+ */
+static int (*bpf_skb_get_tunnel_opt)(struct __sk_buff *skb, void *opt, __u32 size) = (void *) 29;
+
+/*
+ * bpf_skb_set_tunnel_opt
+ *
+ * 	Set tunnel options metadata for the packet associated to *skb*
+ * 	to the option data contained in the raw buffer *opt* of *size*.
+ *
+ * 	See also the description of the **bpf_skb_get_tunnel_opt**\ ()
+ * 	helper for additional information.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_set_tunnel_opt)(struct __sk_buff *skb, void *opt, __u32 size) = (void *) 30;
+
+/*
+ * bpf_skb_change_proto
+ *
+ * 	Change the protocol of the *skb* to *proto*. Currently
+ * 	supported are transition from IPv4 to IPv6, and from IPv6 to
+ * 	IPv4. The helper takes care of the groundwork for the
+ * 	transition, including resizing the socket buffer. The eBPF
+ * 	program is expected to fill the new headers, if any, via
+ * 	**skb_store_bytes**\ () and to recompute the checksums with
+ * 	**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
+ * 	(). The main case for this helper is to perform NAT64
+ * 	operations out of an eBPF program.
+ *
+ * 	Internally, the GSO type is marked as dodgy so that headers are
+ * 	checked and segments are recalculated by the GSO/GRO engine.
+ * 	The size for GSO target is adapted as well.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_change_proto)(struct __sk_buff *skb, __be16 proto, __u64 flags) = (void *) 31;
+
+/*
+ * bpf_skb_change_type
+ *
+ * 	Change the packet type for the packet associated to *skb*. This
+ * 	comes down to setting *skb*\ **->pkt_type** to *type*, except
+ * 	the eBPF program does not have a write access to *skb*\
+ * 	**->pkt_type** beside this helper. Using a helper here allows
+ * 	for graceful handling of errors.
+ *
+ * 	The major use case is to change incoming *skb*s to
+ * 	**PACKET_HOST** in a programmatic way instead of having to
+ * 	recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
+ * 	example.
+ *
+ * 	Note that *type* only allows certain values. At this time, they
+ * 	are:
+ *
+ * 	**PACKET_HOST**
+ * 		Packet is for us.
+ * 	**PACKET_BROADCAST**
+ * 		Send packet to all.
+ * 	**PACKET_MULTICAST**
+ * 		Send packet to group.
+ * 	**PACKET_OTHERHOST**
+ * 		Send packet to someone else.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_change_type)(struct __sk_buff *skb, __u32 type) = (void *) 32;
+
+/*
+ * bpf_skb_under_cgroup
+ *
+ * 	Check whether *skb* is a descendant of the cgroup2 held by
+ * 	*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ *
+ * Returns
+ * 	The return value depends on the result of the test, and can be:
+ *
+ * 	* 0, if the *skb* failed the cgroup2 descendant test.
+ * 	* 1, if the *skb* succeeded the cgroup2 descendant test.
+ * 	* A negative error code, if an error occurred.
+ */
+static int (*bpf_skb_under_cgroup)(struct __sk_buff *skb, void *map, __u32 index) = (void *) 33;
+
+/*
+ * bpf_get_hash_recalc
+ *
+ * 	Retrieve the hash of the packet, *skb*\ **->hash**. If it is
+ * 	not set, in particular if the hash was cleared due to mangling,
+ * 	recompute this hash. Later accesses to the hash can be done
+ * 	directly with *skb*\ **->hash**.
+ *
+ * 	Calling **bpf_set_hash_invalid**\ (), changing a packet
+ * 	prototype with **bpf_skb_change_proto**\ (), or calling
+ * 	**bpf_skb_store_bytes**\ () with the
+ * 	**BPF_F_INVALIDATE_HASH** are actions susceptible to clear
+ * 	the hash and to trigger a new computation for the next call to
+ * 	**bpf_get_hash_recalc**\ ().
+ *
+ * Returns
+ * 	The 32-bit hash.
+ */
+static __u32 (*bpf_get_hash_recalc)(struct __sk_buff *skb) = (void *) 34;
+
+/*
+ * bpf_get_current_task
+ *
+ *
+ * Returns
+ * 	A pointer to the current task struct.
+ */
+static __u64 (*bpf_get_current_task)(void) = (void *) 35;
+
+/*
+ * bpf_probe_write_user
+ *
+ * 	Attempt in a safe way to write *len* bytes from the buffer
+ * 	*src* to *dst* in memory. It only works for threads that are in
+ * 	user context, and *dst* must be a valid user space address.
+ *
+ * 	This helper should not be used to implement any kind of
+ * 	security mechanism because of TOC-TOU attacks, but rather to
+ * 	debug, divert, and manipulate execution of semi-cooperative
+ * 	processes.
+ *
+ * 	Keep in mind that this feature is meant for experiments, and it
+ * 	has a risk of crashing the system and running programs.
+ * 	Therefore, when an eBPF program using this helper is attached,
+ * 	a warning including PID and process name is printed to kernel
+ * 	logs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_probe_write_user)(void *dst, const void *src, __u32 len) = (void *) 36;
+
+/*
+ * bpf_current_task_under_cgroup
+ *
+ * 	Check whether the probe is being run is the context of a given
+ * 	subset of the cgroup2 hierarchy. The cgroup2 to test is held by
+ * 	*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ *
+ * Returns
+ * 	The return value depends on the result of the test, and can be:
+ *
+ * 	* 0, if the *skb* task belongs to the cgroup2.
+ * 	* 1, if the *skb* task does not belong to the cgroup2.
+ * 	* A negative error code, if an error occurred.
+ */
+static int (*bpf_current_task_under_cgroup)(void *map, __u32 index) = (void *) 37;
+
+/*
+ * bpf_skb_change_tail
+ *
+ * 	Resize (trim or grow) the packet associated to *skb* to the
+ * 	new *len*. The *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	The basic idea is that the helper performs the needed work to
+ * 	change the size of the packet, then the eBPF program rewrites
+ * 	the rest via helpers like **bpf_skb_store_bytes**\ (),
+ * 	**bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
+ * 	and others. This helper is a slow path utility intended for
+ * 	replies with control messages. And because it is targeted for
+ * 	slow path, the helper itself can afford to be slow: it
+ * 	implicitly linearizes, unclones and drops offloads from the
+ * 	*skb*.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_change_tail)(struct __sk_buff *skb, __u32 len, __u64 flags) = (void *) 38;
+
+/*
+ * bpf_skb_pull_data
+ *
+ * 	Pull in non-linear data in case the *skb* is non-linear and not
+ * 	all of *len* are part of the linear section. Make *len* bytes
+ * 	from *skb* readable and writable. If a zero value is passed for
+ * 	*len*, then the whole length of the *skb* is pulled.
+ *
+ * 	This helper is only needed for reading and writing with direct
+ * 	packet access.
+ *
+ * 	For direct packet access, testing that offsets to access
+ * 	are within packet boundaries (test on *skb*\ **->data_end**) is
+ * 	susceptible to fail if offsets are invalid, or if the requested
+ * 	data is in non-linear parts of the *skb*. On failure the
+ * 	program can just bail out, or in the case of a non-linear
+ * 	buffer, use a helper to make the data available. The
+ * 	**bpf_skb_load_bytes**\ () helper is a first solution to access
+ * 	the data. Another one consists in using **bpf_skb_pull_data**
+ * 	to pull in once the non-linear parts, then retesting and
+ * 	eventually access the data.
+ *
+ * 	At the same time, this also makes sure the *skb* is uncloned,
+ * 	which is a necessary condition for direct write. As this needs
+ * 	to be an invariant for the write part only, the verifier
+ * 	detects writes and adds a prologue that is calling
+ * 	**bpf_skb_pull_data()** to effectively unclone the *skb* from
+ * 	the very beginning in case it is indeed cloned.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_pull_data)(struct __sk_buff *skb, __u32 len) = (void *) 39;
+
+/*
+ * bpf_csum_update
+ *
+ * 	Add the checksum *csum* into *skb*\ **->csum** in case the
+ * 	driver has supplied a checksum for the entire packet into that
+ * 	field. Return an error otherwise. This helper is intended to be
+ * 	used in combination with **bpf_csum_diff**\ (), in particular
+ * 	when the checksum needs to be updated after data has been
+ * 	written into the packet through direct packet access.
+ *
+ * Returns
+ * 	The checksum on success, or a negative error code in case of
+ * 	failure.
+ */
+static __s64 (*bpf_csum_update)(struct __sk_buff *skb, __wsum csum) = (void *) 40;
+
+/*
+ * bpf_set_hash_invalid
+ *
+ * 	Invalidate the current *skb*\ **->hash**. It can be used after
+ * 	mangling on headers through direct packet access, in order to
+ * 	indicate that the hash is outdated and to trigger a
+ * 	recalculation the next time the kernel tries to access this
+ * 	hash or when the **bpf_get_hash_recalc**\ () helper is called.
+ *
+ */
+static void (*bpf_set_hash_invalid)(struct __sk_buff *skb) = (void *) 41;
+
+/*
+ * bpf_get_numa_node_id
+ *
+ * 	Return the id of the current NUMA node. The primary use case
+ * 	for this helper is the selection of sockets for the local NUMA
+ * 	node, when the program is attached to sockets using the
+ * 	**SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
+ * 	but the helper is also available to other eBPF program types,
+ * 	similarly to **bpf_get_smp_processor_id**\ ().
+ *
+ * Returns
+ * 	The id of current NUMA node.
+ */
+static int (*bpf_get_numa_node_id)(void) = (void *) 42;
+
+/*
+ * bpf_skb_change_head
+ *
+ * 	Grows headroom of packet associated to *skb* and adjusts the
+ * 	offset of the MAC header accordingly, adding *len* bytes of
+ * 	space. It automatically extends and reallocates memory as
+ * 	required.
+ *
+ * 	This helper can be used on a layer 3 *skb* to push a MAC header
+ * 	for redirection into a layer 2 device.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_change_head)(struct __sk_buff *skb, __u32 len, __u64 flags) = (void *) 43;
+
+/*
+ * bpf_xdp_adjust_head
+ *
+ * 	Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
+ * 	it is possible to use a negative value for *delta*. This helper
+ * 	can be used to prepare the packet for pushing or popping
+ * 	headers.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_xdp_adjust_head)(struct xdp_md *xdp_md, int delta) = (void *) 44;
+
+/*
+ * bpf_probe_read_str
+ *
+ * 	Copy a NUL terminated string from an unsafe kernel address
+ * 	*unsafe_ptr* to *dst*. See bpf_probe_read_kernel_str() for
+ * 	more details.
+ *
+ * 	Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str()
+ * 	instead.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string,
+ * 	including the trailing NUL character. On error, a negative
+ * 	value.
+ */
+static int (*bpf_probe_read_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 45;
+
+/*
+ * bpf_get_socket_cookie
+ *
+ * 	If the **struct sk_buff** pointed by *skb* has a known socket,
+ * 	retrieve the cookie (generated by the kernel) of this socket.
+ * 	If no cookie has been set yet, generate a new cookie. Once
+ * 	generated, the socket cookie remains stable for the life of the
+ * 	socket. This helper can be useful for monitoring per socket
+ * 	networking traffic statistics as it provides a global socket
+ * 	identifier that can be assumed unique.
+ *
+ * Returns
+ * 	A 8-byte long non-decreasing number on success, or 0 if the
+ * 	socket field is missing inside *skb*.
+ */
+static __u64 (*bpf_get_socket_cookie)(void *ctx) = (void *) 46;
+
+/*
+ * bpf_get_socket_uid
+ *
+ *
+ * Returns
+ * 	The owner UID of the socket associated to *skb*. If the socket
+ * 	is **NULL**, or if it is not a full socket (i.e. if it is a
+ * 	time-wait or a request socket instead), **overflowuid** value
+ * 	is returned (note that **overflowuid** might also be the actual
+ * 	UID value for the socket).
+ */
+static __u32 (*bpf_get_socket_uid)(struct __sk_buff *skb) = (void *) 47;
+
+/*
+ * bpf_set_hash
+ *
+ * 	Set the full hash for *skb* (set the field *skb*\ **->hash**)
+ * 	to value *hash*.
+ *
+ * Returns
+ * 	0
+ */
+static __u32 (*bpf_set_hash)(struct __sk_buff *skb, __u32 hash) = (void *) 48;
+
+/*
+ * bpf_setsockopt
+ *
+ * 	Emulate a call to **setsockopt()** on the socket associated to
+ * 	*bpf_socket*, which must be a full socket. The *level* at
+ * 	which the option resides and the name *optname* of the option
+ * 	must be specified, see **setsockopt(2)** for more information.
+ * 	The option value of length *optlen* is pointed by *optval*.
+ *
+ * 	This helper actually implements a subset of **setsockopt()**.
+ * 	It supports the following *level*\ s:
+ *
+ * 	* **SOL_SOCKET**, which supports the following *optname*\ s:
+ * 	  **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
+ * 	  **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**.
+ * 	* **IPPROTO_TCP**, which supports the following *optname*\ s:
+ * 	  **TCP_CONGESTION**, **TCP_BPF_IW**,
+ * 	  **TCP_BPF_SNDCWND_CLAMP**.
+ * 	* **IPPROTO_IP**, which supports *optname* **IP_TOS**.
+ * 	* **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_setsockopt)(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen) = (void *) 49;
+
+/*
+ * bpf_skb_adjust_room
+ *
+ * 	Grow or shrink the room for data in the packet associated to
+ * 	*skb* by *len_diff*, and according to the selected *mode*.
+ *
+ * 	There are two supported modes at this time:
+ *
+ * 	* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ * 	  (room space is added or removed below the layer 2 header).
+ *
+ * 	* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
+ * 	  (room space is added or removed below the layer 3 header).
+ *
+ * 	The following flags are supported at this time:
+ *
+ * 	* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
+ * 	  Adjusting mss in this way is not allowed for datagrams.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
+ * 	  **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
+ * 	  Any new space is reserved to hold a tunnel header.
+ * 	  Configure skb offsets and other fields accordingly.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
+ * 	  **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
+ * 	  Use with ENCAP_L3 flags to further specify the tunnel type.
+ *
+ * 	* **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
+ * 	  Use with ENCAP_L3/L4 flags to further specify the tunnel
+ * 	  type; *len* is the length of the inner MAC header.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_adjust_room)(struct __sk_buff *skb, __s32 len_diff, __u32 mode, __u64 flags) = (void *) 50;
+
+/*
+ * bpf_redirect_map
+ *
+ * 	Redirect the packet to the endpoint referenced by *map* at
+ * 	index *key*. Depending on its type, this *map* can contain
+ * 	references to net devices (for forwarding packets through other
+ * 	ports), or to CPUs (for redirecting XDP frames to another CPU;
+ * 	but this is only implemented for native XDP (with driver
+ * 	support) as of this writing).
+ *
+ * 	The lower two bits of *flags* are used as the return code if
+ * 	the map lookup fails. This is so that the return value can be
+ * 	one of the XDP program return codes up to XDP_TX, as chosen by
+ * 	the caller. Any higher bits in the *flags* argument must be
+ * 	unset.
+ *
+ * 	When used to redirect packets to net devices, this helper
+ * 	provides a high performance increase over **bpf_redirect**\ ().
+ * 	This is due to various implementation details of the underlying
+ * 	mechanisms, one of which is the fact that **bpf_redirect_map**\
+ * 	() tries to send packet as a "bulk" to the device.
+ *
+ * Returns
+ * 	**XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
+ */
+static int (*bpf_redirect_map)(void *map, __u32 key, __u64 flags) = (void *) 51;
+
+/*
+ * bpf_sk_redirect_map
+ *
+ * 	Redirect the packet to the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static int (*bpf_sk_redirect_map)(struct __sk_buff *skb, void *map, __u32 key, __u64 flags) = (void *) 52;
+
+/*
+ * bpf_sock_map_update
+ *
+ * 	Add an entry to, or update a *map* referencing sockets. The
+ * 	*skops* is used as a new value for the entry associated to
+ * 	*key*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	If the *map* has eBPF programs (parser and verdict), those will
+ * 	be inherited by the socket being added. If the socket is
+ * 	already attached to eBPF programs, this results in an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_sock_map_update)(struct bpf_sock_ops *skops, void *map, void *key, __u64 flags) = (void *) 53;
+
+/*
+ * bpf_xdp_adjust_meta
+ *
+ * 	Adjust the address pointed by *xdp_md*\ **->data_meta** by
+ * 	*delta* (which can be positive or negative). Note that this
+ * 	operation modifies the address stored in *xdp_md*\ **->data**,
+ * 	so the latter must be loaded only after the helper has been
+ * 	called.
+ *
+ * 	The use of *xdp_md*\ **->data_meta** is optional and programs
+ * 	are not required to use it. The rationale is that when the
+ * 	packet is processed with XDP (e.g. as DoS filter), it is
+ * 	possible to push further meta data along with it before passing
+ * 	to the stack, and to give the guarantee that an ingress eBPF
+ * 	program attached as a TC classifier on the same device can pick
+ * 	this up for further post-processing. Since TC works with socket
+ * 	buffers, it remains possible to set from XDP the **mark** or
+ * 	**priority** pointers, or other pointers for the socket buffer.
+ * 	Having this scratch space generic and programmable allows for
+ * 	more flexibility as the user is free to store whatever meta
+ * 	data they need.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_xdp_adjust_meta)(struct xdp_md *xdp_md, int delta) = (void *) 54;
+
+/*
+ * bpf_perf_event_read_value
+ *
+ * 	Read the value of a perf event counter, and store it into *buf*
+ * 	of size *buf_size*. This helper relies on a *map* of type
+ * 	**BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
+ * 	counter is selected when *map* is updated with perf event file
+ * 	descriptors. The *map* is an array whose size is the number of
+ * 	available CPUs, and each cell contains a value relative to one
+ * 	CPU. The value to retrieve is indicated by *flags*, that
+ * 	contains the index of the CPU to look up, masked with
+ * 	**BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 	**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 	current CPU should be retrieved.
+ *
+ * 	This helper behaves in a way close to
+ * 	**bpf_perf_event_read**\ () helper, save that instead of
+ * 	just returning the value observed, it fills the *buf*
+ * 	structure. This allows for additional data to be retrieved: in
+ * 	particular, the enabled and running times (in *buf*\
+ * 	**->enabled** and *buf*\ **->running**, respectively) are
+ * 	copied. In general, **bpf_perf_event_read_value**\ () is
+ * 	recommended over **bpf_perf_event_read**\ (), which has some
+ * 	ABI issues and provides fewer functionalities.
+ *
+ * 	These values are interesting, because hardware PMU (Performance
+ * 	Monitoring Unit) counters are limited resources. When there are
+ * 	more PMU based perf events opened than available counters,
+ * 	kernel will multiplex these events so each event gets certain
+ * 	percentage (but not all) of the PMU time. In case that
+ * 	multiplexing happens, the number of samples or counter value
+ * 	will not reflect the case compared to when no multiplexing
+ * 	occurs. This makes comparison between different runs difficult.
+ * 	Typically, the counter value should be normalized before
+ * 	comparing to other experiments. The usual normalization is done
+ * 	as follows.
+ *
+ * 	::
+ *
+ * 		normalized_counter = counter * t_enabled / t_running
+ *
+ * 	Where t_enabled is the time enabled for event and t_running is
+ * 	the time running for event since last normalization. The
+ * 	enabled and running times are accumulated since the perf event
+ * 	open. To achieve scaling factor between two invocations of an
+ * 	eBPF program, users can can use CPU id as the key (which is
+ * 	typical for perf array usage model) to remember the previous
+ * 	value and do the calculation inside the eBPF program.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_perf_event_read_value)(void *map, __u64 flags, struct bpf_perf_event_value *buf, __u32 buf_size) = (void *) 55;
+
+/*
+ * bpf_perf_prog_read_value
+ *
+ * 	For en eBPF program attached to a perf event, retrieve the
+ * 	value of the event counter associated to *ctx* and store it in
+ * 	the structure pointed by *buf* and of size *buf_size*. Enabled
+ * 	and running times are also stored in the structure (see
+ * 	description of helper **bpf_perf_event_read_value**\ () for
+ * 	more details).
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_perf_prog_read_value)(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, __u32 buf_size) = (void *) 56;
+
+/*
+ * bpf_getsockopt
+ *
+ * 	Emulate a call to **getsockopt()** on the socket associated to
+ * 	*bpf_socket*, which must be a full socket. The *level* at
+ * 	which the option resides and the name *optname* of the option
+ * 	must be specified, see **getsockopt(2)** for more information.
+ * 	The retrieved value is stored in the structure pointed by
+ * 	*opval* and of length *optlen*.
+ *
+ * 	This helper actually implements a subset of **getsockopt()**.
+ * 	It supports the following *level*\ s:
+ *
+ * 	* **IPPROTO_TCP**, which supports *optname*
+ * 	  **TCP_CONGESTION**.
+ * 	* **IPPROTO_IP**, which supports *optname* **IP_TOS**.
+ * 	* **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_getsockopt)(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen) = (void *) 57;
+
+/*
+ * bpf_override_return
+ *
+ * 	Used for error injection, this helper uses kprobes to override
+ * 	the return value of the probed function, and to set it to *rc*.
+ * 	The first argument is the context *regs* on which the kprobe
+ * 	works.
+ *
+ * 	This helper works by setting setting the PC (program counter)
+ * 	to an override function which is run in place of the original
+ * 	probed function. This means the probed function is not run at
+ * 	all. The replacement function just returns with the required
+ * 	value.
+ *
+ * 	This helper has security implications, and thus is subject to
+ * 	restrictions. It is only available if the kernel was compiled
+ * 	with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
+ * 	option, and in this case it only works on functions tagged with
+ * 	**ALLOW_ERROR_INJECTION** in the kernel code.
+ *
+ * 	Also, the helper is only available for the architectures having
+ * 	the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
+ * 	x86 architecture is the only one to support this feature.
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_override_return)(struct pt_regs *regs, __u64 rc) = (void *) 58;
+
+/*
+ * bpf_sock_ops_cb_flags_set
+ *
+ * 	Attempt to set the value of the **bpf_sock_ops_cb_flags** field
+ * 	for the full TCP socket associated to *bpf_sock_ops* to
+ * 	*argval*.
+ *
+ * 	The primary use of this field is to determine if there should
+ * 	be calls to eBPF programs of type
+ * 	**BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
+ * 	code. A program of the same type can change its value, per
+ * 	connection and as necessary, when the connection is
+ * 	established. This field is directly accessible for reading, but
+ * 	this helper must be used for updates in order to return an
+ * 	error if an eBPF program tries to set a callback that is not
+ * 	supported in the current kernel.
+ *
+ * 	*argval* is a flag array which can combine these flags:
+ *
+ * 	* **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
+ * 	* **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
+ * 	* **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
+ * 	* **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
+ *
+ * 	Therefore, this function can be used to clear a callback flag by
+ * 	setting the appropriate bit to zero. e.g. to disable the RTO
+ * 	callback:
+ *
+ * 	**bpf_sock_ops_cb_flags_set(bpf_sock,**
+ * 		**bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
+ *
+ * 	Here are some examples of where one could call such eBPF
+ * 	program:
+ *
+ * 	* When RTO fires.
+ * 	* When a packet is retransmitted.
+ * 	* When the connection terminates.
+ * 	* When a packet is sent.
+ * 	* When a packet is received.
+ *
+ * Returns
+ * 	Code **-EINVAL** if the socket is not a full TCP socket;
+ * 	otherwise, a positive number containing the bits that could not
+ * 	be set is returned (which comes down to 0 if all bits were set
+ * 	as required).
+ */
+static int (*bpf_sock_ops_cb_flags_set)(struct bpf_sock_ops *bpf_sock, int argval) = (void *) 59;
+
+/*
+ * bpf_msg_redirect_map
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	socket level. If the message *msg* is allowed to pass (i.e. if
+ * 	the verdict eBPF program returns **SK_PASS**), redirect it to
+ * 	the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static int (*bpf_msg_redirect_map)(struct sk_msg_md *msg, void *map, __u32 key, __u64 flags) = (void *) 60;
+
+/*
+ * bpf_msg_apply_bytes
+ *
+ * 	For socket policies, apply the verdict of the eBPF program to
+ * 	the next *bytes* (number of bytes) of message *msg*.
+ *
+ * 	For example, this helper can be used in the following cases:
+ *
+ * 	* A single **sendmsg**\ () or **sendfile**\ () system call
+ * 	  contains multiple logical messages that the eBPF program is
+ * 	  supposed to read and for which it should apply a verdict.
+ * 	* An eBPF program only cares to read the first *bytes* of a
+ * 	  *msg*. If the message has a large payload, then setting up
+ * 	  and calling the eBPF program repeatedly for all bytes, even
+ * 	  though the verdict is already known, would create unnecessary
+ * 	  overhead.
+ *
+ * 	When called from within an eBPF program, the helper sets a
+ * 	counter internal to the BPF infrastructure, that is used to
+ * 	apply the last verdict to the next *bytes*. If *bytes* is
+ * 	smaller than the current data being processed from a
+ * 	**sendmsg**\ () or **sendfile**\ () system call, the first
+ * 	*bytes* will be sent and the eBPF program will be re-run with
+ * 	the pointer for start of data pointing to byte number *bytes*
+ * 	**+ 1**. If *bytes* is larger than the current data being
+ * 	processed, then the eBPF verdict will be applied to multiple
+ * 	**sendmsg**\ () or **sendfile**\ () calls until *bytes* are
+ * 	consumed.
+ *
+ * 	Note that if a socket closes with the internal counter holding
+ * 	a non-zero value, this is not a problem because data is not
+ * 	being buffered for *bytes* and is sent as it is received.
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_msg_apply_bytes)(struct sk_msg_md *msg, __u32 bytes) = (void *) 61;
+
+/*
+ * bpf_msg_cork_bytes
+ *
+ * 	For socket policies, prevent the execution of the verdict eBPF
+ * 	program for message *msg* until *bytes* (byte number) have been
+ * 	accumulated.
+ *
+ * 	This can be used when one needs a specific number of bytes
+ * 	before a verdict can be assigned, even if the data spans
+ * 	multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
+ * 	case would be a user calling **sendmsg**\ () repeatedly with
+ * 	1-byte long message segments. Obviously, this is bad for
+ * 	performance, but it is still valid. If the eBPF program needs
+ * 	*bytes* bytes to validate a header, this helper can be used to
+ * 	prevent the eBPF program to be called again until *bytes* have
+ * 	been accumulated.
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_msg_cork_bytes)(struct sk_msg_md *msg, __u32 bytes) = (void *) 62;
+
+/*
+ * bpf_msg_pull_data
+ *
+ * 	For socket policies, pull in non-linear data from user space
+ * 	for *msg* and set pointers *msg*\ **->data** and *msg*\
+ * 	**->data_end** to *start* and *end* bytes offsets into *msg*,
+ * 	respectively.
+ *
+ * 	If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ * 	*msg* it can only parse data that the (**data**, **data_end**)
+ * 	pointers have already consumed. For **sendmsg**\ () hooks this
+ * 	is likely the first scatterlist element. But for calls relying
+ * 	on the **sendpage** handler (e.g. **sendfile**\ ()) this will
+ * 	be the range (**0**, **0**) because the data is shared with
+ * 	user space and by default the objective is to avoid allowing
+ * 	user space to modify data while (or after) eBPF verdict is
+ * 	being decided. This helper can be used to pull in data and to
+ * 	set the start and end pointer to given values. Data will be
+ * 	copied if necessary (i.e. if data was not linear and if start
+ * 	and end pointers do not point to the same chunk).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_msg_pull_data)(struct sk_msg_md *msg, __u32 start, __u32 end, __u64 flags) = (void *) 63;
+
+/*
+ * bpf_bind
+ *
+ * 	Bind the socket associated to *ctx* to the address pointed by
+ * 	*addr*, of length *addr_len*. This allows for making outgoing
+ * 	connection from the desired IP address, which can be useful for
+ * 	example when all processes inside a cgroup should use one
+ * 	single IP address on a host that has multiple IP configured.
+ *
+ * 	This helper works for IPv4 and IPv6, TCP and UDP sockets. The
+ * 	domain (*addr*\ **->sa_family**) must be **AF_INET** (or
+ * 	**AF_INET6**). Looking for a free port to bind to can be
+ * 	expensive, therefore binding to port is not permitted by the
+ * 	helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
+ * 	must be set to zero.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_bind)(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len) = (void *) 64;
+
+/*
+ * bpf_xdp_adjust_tail
+ *
+ * 	Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
+ * 	only possible to shrink the packet as of this writing,
+ * 	therefore *delta* must be a negative integer.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_xdp_adjust_tail)(struct xdp_md *xdp_md, int delta) = (void *) 65;
+
+/*
+ * bpf_skb_get_xfrm_state
+ *
+ * 	Retrieve the XFRM state (IP transform framework, see also
+ * 	**ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
+ *
+ * 	The retrieved value is stored in the **struct bpf_xfrm_state**
+ * 	pointed by *xfrm_state* and of length *size*.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_XFRM** configuration option.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_get_xfrm_state)(struct __sk_buff *skb, __u32 index, struct bpf_xfrm_state *xfrm_state, __u32 size, __u64 flags) = (void *) 66;
+
+/*
+ * bpf_get_stack
+ *
+ * 	Return a user or a kernel stack in bpf program provided buffer.
+ * 	To achieve this, the helper needs *ctx*, which is a pointer
+ * 	to the context on which the tracing program is executed.
+ * 	To store the stacktrace, the bpf program provides *buf* with
+ * 	a nonnegative *size*.
+ *
+ * 	The last argument, *flags*, holds the number of stack frames to
+ * 	skip (from 0 to 255), masked with
+ * 	**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 	the following flags:
+ *
+ * 	**BPF_F_USER_STACK**
+ * 		Collect a user space stack instead of a kernel stack.
+ * 	**BPF_F_USER_BUILD_ID**
+ * 		Collect buildid+offset instead of ips for user stack,
+ * 		only valid if **BPF_F_USER_STACK** is also specified.
+ *
+ * 	**bpf_get_stack**\ () can collect up to
+ * 	**PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
+ * 	to sufficient large buffer size. Note that
+ * 	this limit can be controlled with the **sysctl** program, and
+ * 	that it should be manually increased in order to profile long
+ * 	user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 	::
+ *
+ * 		# sysctl kernel.perf_event_max_stack=<new value>
+ *
+ * Returns
+ * 	A non-negative value equal to or less than *size* on success,
+ * 	or a negative error in case of failure.
+ */
+static int (*bpf_get_stack)(void *ctx, void *buf, __u32 size, __u64 flags) = (void *) 67;
+
+/*
+ * bpf_skb_load_bytes_relative
+ *
+ * 	This helper is similar to **bpf_skb_load_bytes**\ () in that
+ * 	it provides an easy way to load *len* bytes from *offset*
+ * 	from the packet associated to *skb*, into the buffer pointed
+ * 	by *to*. The difference to **bpf_skb_load_bytes**\ () is that
+ * 	a fifth argument *start_header* exists in order to select a
+ * 	base offset to start from. *start_header* can be one of:
+ *
+ * 	**BPF_HDR_START_MAC**
+ * 		Base offset to load data from is *skb*'s mac header.
+ * 	**BPF_HDR_START_NET**
+ * 		Base offset to load data from is *skb*'s network header.
+ *
+ * 	In general, "direct packet access" is the preferred method to
+ * 	access packet data, however, this helper is in particular useful
+ * 	in socket filters where *skb*\ **->data** does not always point
+ * 	to the start of the mac header and where "direct packet access"
+ * 	is not available.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_load_bytes_relative)(const void *skb, __u32 offset, void *to, __u32 len, __u32 start_header) = (void *) 68;
+
+/*
+ * bpf_fib_lookup
+ *
+ * 	Do FIB lookup in kernel tables using parameters in *params*.
+ * 	If lookup is successful and result shows packet is to be
+ * 	forwarded, the neighbor tables are searched for the nexthop.
+ * 	If successful (ie., FIB lookup shows forwarding and nexthop
+ * 	is resolved), the nexthop address is returned in ipv4_dst
+ * 	or ipv6_dst based on family, smac is set to mac address of
+ * 	egress device, dmac is set to nexthop mac address, rt_metric
+ * 	is set to metric from route (IPv4/IPv6 only), and ifindex
+ * 	is set to the device index of the nexthop from the FIB lookup.
+ *
+ * 	*plen* argument is the size of the passed in struct.
+ * 	*flags* argument can be a combination of one or more of the
+ * 	following values:
+ *
+ * 	**BPF_FIB_LOOKUP_DIRECT**
+ * 		Do a direct table lookup vs full lookup using FIB
+ * 		rules.
+ * 	**BPF_FIB_LOOKUP_OUTPUT**
+ * 		Perform lookup from an egress perspective (default is
+ * 		ingress).
+ *
+ * 	*ctx* is either **struct xdp_md** for XDP programs or
+ * 	**struct sk_buff** tc cls_act programs.
+ *
+ * Returns
+ * 	* < 0 if any input argument is invalid
+ * 	*   0 on success (packet is forwarded, nexthop neighbor exists)
+ * 	* > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
+ * 	  packet is not forwarded or needs assist from full stack
+ */
+static int (*bpf_fib_lookup)(void *ctx, struct bpf_fib_lookup *params, int plen, __u32 flags) = (void *) 69;
+
+/*
+ * bpf_sock_hash_update
+ *
+ * 	Add an entry to, or update a sockhash *map* referencing sockets.
+ * 	The *skops* is used as a new value for the entry associated to
+ * 	*key*. *flags* is one of:
+ *
+ * 	**BPF_NOEXIST**
+ * 		The entry for *key* must not exist in the map.
+ * 	**BPF_EXIST**
+ * 		The entry for *key* must already exist in the map.
+ * 	**BPF_ANY**
+ * 		No condition on the existence of the entry for *key*.
+ *
+ * 	If the *map* has eBPF programs (parser and verdict), those will
+ * 	be inherited by the socket being added. If the socket is
+ * 	already attached to eBPF programs, this results in an error.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_sock_hash_update)(struct bpf_sock_ops *skops, void *map, void *key, __u64 flags) = (void *) 70;
+
+/*
+ * bpf_msg_redirect_hash
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	socket level. If the message *msg* is allowed to pass (i.e. if
+ * 	the verdict eBPF program returns **SK_PASS**), redirect it to
+ * 	the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress path otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static int (*bpf_msg_redirect_hash)(struct sk_msg_md *msg, void *map, void *key, __u64 flags) = (void *) 71;
+
+/*
+ * bpf_sk_redirect_hash
+ *
+ * 	This helper is used in programs implementing policies at the
+ * 	skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
+ * 	if the verdeict eBPF program returns **SK_PASS**), redirect it
+ * 	to the socket referenced by *map* (of type
+ * 	**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ * 	egress interfaces can be used for redirection. The
+ * 	**BPF_F_INGRESS** value in *flags* is used to make the
+ * 	distinction (ingress path is selected if the flag is present,
+ * 	egress otherwise). This is the only flag supported for now.
+ *
+ * Returns
+ * 	**SK_PASS** on success, or **SK_DROP** on error.
+ */
+static int (*bpf_sk_redirect_hash)(struct __sk_buff *skb, void *map, void *key, __u64 flags) = (void *) 72;
+
+/*
+ * bpf_lwt_push_encap
+ *
+ * 	Encapsulate the packet associated to *skb* within a Layer 3
+ * 	protocol header. This header is provided in the buffer at
+ * 	address *hdr*, with *len* its size in bytes. *type* indicates
+ * 	the protocol of the header and can be one of:
+ *
+ * 	**BPF_LWT_ENCAP_SEG6**
+ * 		IPv6 encapsulation with Segment Routing Header
+ * 		(**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
+ * 		the IPv6 header is computed by the kernel.
+ * 	**BPF_LWT_ENCAP_SEG6_INLINE**
+ * 		Only works if *skb* contains an IPv6 packet. Insert a
+ * 		Segment Routing Header (**struct ipv6_sr_hdr**) inside
+ * 		the IPv6 header.
+ * 	**BPF_LWT_ENCAP_IP**
+ * 		IP encapsulation (GRE/GUE/IPIP/etc). The outer header
+ * 		must be IPv4 or IPv6, followed by zero or more
+ * 		additional headers, up to **LWT_BPF_MAX_HEADROOM**
+ * 		total bytes in all prepended headers. Please note that
+ * 		if **skb_is_gso**\ (*skb*) is true, no more than two
+ * 		headers can be prepended, and the inner header, if
+ * 		present, should be either GRE or UDP/GUE.
+ *
+ * 	**BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
+ * 	of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
+ * 	be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
+ * 	**BPF_PROG_TYPE_LWT_XMIT**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_lwt_push_encap)(struct __sk_buff *skb, __u32 type, void *hdr, __u32 len) = (void *) 73;
+
+/*
+ * bpf_lwt_seg6_store_bytes
+ *
+ * 	Store *len* bytes from address *from* into the packet
+ * 	associated to *skb*, at *offset*. Only the flags, tag and TLVs
+ * 	inside the outermost IPv6 Segment Routing Header can be
+ * 	modified through this helper.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_lwt_seg6_store_bytes)(struct __sk_buff *skb, __u32 offset, const void *from, __u32 len) = (void *) 74;
+
+/*
+ * bpf_lwt_seg6_adjust_srh
+ *
+ * 	Adjust the size allocated to TLVs in the outermost IPv6
+ * 	Segment Routing Header contained in the packet associated to
+ * 	*skb*, at position *offset* by *delta* bytes. Only offsets
+ * 	after the segments are accepted. *delta* can be as well
+ * 	positive (growing) as negative (shrinking).
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_lwt_seg6_adjust_srh)(struct __sk_buff *skb, __u32 offset, __s32 delta) = (void *) 75;
+
+/*
+ * bpf_lwt_seg6_action
+ *
+ * 	Apply an IPv6 Segment Routing action of type *action* to the
+ * 	packet associated to *skb*. Each action takes a parameter
+ * 	contained at address *param*, and of length *param_len* bytes.
+ * 	*action* can be one of:
+ *
+ * 	**SEG6_LOCAL_ACTION_END_X**
+ * 		End.X action: Endpoint with Layer-3 cross-connect.
+ * 		Type of *param*: **struct in6_addr**.
+ * 	**SEG6_LOCAL_ACTION_END_T**
+ * 		End.T action: Endpoint with specific IPv6 table lookup.
+ * 		Type of *param*: **int**.
+ * 	**SEG6_LOCAL_ACTION_END_B6**
+ * 		End.B6 action: Endpoint bound to an SRv6 policy.
+ * 		Type of *param*: **struct ipv6_sr_hdr**.
+ * 	**SEG6_LOCAL_ACTION_END_B6_ENCAP**
+ * 		End.B6.Encap action: Endpoint bound to an SRv6
+ * 		encapsulation policy.
+ * 		Type of *param*: **struct ipv6_sr_hdr**.
+ *
+ * 	A call to this helper is susceptible to change the underlying
+ * 	packet buffer. Therefore, at load time, all checks on pointers
+ * 	previously done by the verifier are invalidated and must be
+ * 	performed again, if the helper is used in combination with
+ * 	direct packet access.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_lwt_seg6_action)(struct __sk_buff *skb, __u32 action, void *param, __u32 param_len) = (void *) 76;
+
+/*
+ * bpf_rc_repeat
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded repeat key message. This delays
+ * 	the generation of a key up event for previously generated
+ * 	key down event.
+ *
+ * 	Some IR protocols like NEC have a special IR message for
+ * 	repeating last button, for when a button is held down.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_rc_repeat)(void *ctx) = (void *) 77;
+
+/*
+ * bpf_rc_keydown
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded key press with *scancode*,
+ * 	*toggle* value in the given *protocol*. The scancode will be
+ * 	translated to a keycode using the rc keymap, and reported as
+ * 	an input key down event. After a period a key up event is
+ * 	generated. This period can be extended by calling either
+ * 	**bpf_rc_keydown**\ () again with the same values, or calling
+ * 	**bpf_rc_repeat**\ ().
+ *
+ * 	Some protocols include a toggle bit, in case the button	was
+ * 	released and pressed again between consecutive scancodes.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	The *protocol* is the decoded protocol number (see
+ * 	**enum rc_proto** for some predefined values).
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_rc_keydown)(void *ctx, __u32 protocol, __u64 scancode, __u32 toggle) = (void *) 78;
+
+/*
+ * bpf_skb_cgroup_id
+ *
+ * 	Return the cgroup v2 id of the socket associated with the *skb*.
+ * 	This is roughly similar to the **bpf_get_cgroup_classid**\ ()
+ * 	helper for cgroup v1 by providing a tag resp. identifier that
+ * 	can be matched on or used for map lookups e.g. to implement
+ * 	policy. The cgroup v2 id of a given path in the hierarchy is
+ * 	exposed in user space through the f_handle API in order to get
+ * 	to the same 64-bit id.
+ *
+ * 	This helper can be used on TC egress path, but not on ingress,
+ * 	and is available only if the kernel was compiled with the
+ * 	**CONFIG_SOCK_CGROUP_DATA** configuration option.
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_skb_cgroup_id)(struct __sk_buff *skb) = (void *) 79;
+
+/*
+ * bpf_get_current_cgroup_id
+ *
+ *
+ * Returns
+ * 	A 64-bit integer containing the current cgroup id based
+ * 	on the cgroup within which the current task is running.
+ */
+static __u64 (*bpf_get_current_cgroup_id)(void) = (void *) 80;
+
+/*
+ * bpf_get_local_storage
+ *
+ * 	Get the pointer to the local storage area.
+ * 	The type and the size of the local storage is defined
+ * 	by the *map* argument.
+ * 	The *flags* meaning is specific for each map type,
+ * 	and has to be 0 for cgroup local storage.
+ *
+ * 	Depending on the BPF program type, a local storage area
+ * 	can be shared between multiple instances of the BPF program,
+ * 	running simultaneously.
+ *
+ * 	A user should care about the synchronization by himself.
+ * 	For example, by using the **BPF_STX_XADD** instruction to alter
+ * 	the shared data.
+ *
+ * Returns
+ * 	A pointer to the local storage area.
+ */
+static void *(*bpf_get_local_storage)(void *map, __u64 flags) = (void *) 81;
+
+/*
+ * bpf_sk_select_reuseport
+ *
+ * 	Select a **SO_REUSEPORT** socket from a
+ * 	**BPF_MAP_TYPE_REUSEPORT_ARRAY** *map*.
+ * 	It checks the selected socket is matching the incoming
+ * 	request in the socket buffer.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_sk_select_reuseport)(struct sk_reuseport_md *reuse, void *map, void *key, __u64 flags) = (void *) 82;
+
+/*
+ * bpf_skb_ancestor_cgroup_id
+ *
+ * 	Return id of cgroup v2 that is ancestor of cgroup associated
+ * 	with the *skb* at the *ancestor_level*.  The root cgroup is at
+ * 	*ancestor_level* zero and each step down the hierarchy
+ * 	increments the level. If *ancestor_level* == level of cgroup
+ * 	associated with *skb*, then return value will be same as that
+ * 	of **bpf_skb_cgroup_id**\ ().
+ *
+ * 	The helper is useful to implement policies based on cgroups
+ * 	that are upper in hierarchy than immediate cgroup associated
+ * 	with *skb*.
+ *
+ * 	The format of returned id and helper limitations are same as in
+ * 	**bpf_skb_cgroup_id**\ ().
+ *
+ * Returns
+ * 	The id is returned or 0 in case the id could not be retrieved.
+ */
+static __u64 (*bpf_skb_ancestor_cgroup_id)(struct __sk_buff *skb, int ancestor_level) = (void *) 83;
+
+/*
+ * bpf_sk_lookup_tcp
+ *
+ * 	Look for TCP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	The *ctx* should point to the context of the program, such as
+ * 	the skb or socket (depending on the hook in use). This is used
+ * 	to determine the base network namespace for the lookup.
+ *
+ * 	*tuple_size* must be one of:
+ *
+ * 	**sizeof**\ (*tuple*\ **->ipv4**)
+ * 		Look for an IPv4 socket.
+ * 	**sizeof**\ (*tuple*\ **->ipv6**)
+ * 		Look for an IPv6 socket.
+ *
+ * 	If the *netns* is a negative signed 32-bit integer, then the
+ * 	socket lookup table in the netns associated with the *ctx* will
+ * 	will be used. For the TC hooks, this is the netns of the device
+ * 	in the skb. For socket hooks, this is the netns of the socket.
+ * 	If *netns* is any other signed 32-bit value greater than or
+ * 	equal to zero then it specifies the ID of the netns relative to
+ * 	the netns associated with the *ctx*. *netns* values beyond the
+ * 	range of 32-bit integers are reserved for future use.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_sk_lookup_tcp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 84;
+
+/*
+ * bpf_sk_lookup_udp
+ *
+ * 	Look for UDP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	The *ctx* should point to the context of the program, such as
+ * 	the skb or socket (depending on the hook in use). This is used
+ * 	to determine the base network namespace for the lookup.
+ *
+ * 	*tuple_size* must be one of:
+ *
+ * 	**sizeof**\ (*tuple*\ **->ipv4**)
+ * 		Look for an IPv4 socket.
+ * 	**sizeof**\ (*tuple*\ **->ipv6**)
+ * 		Look for an IPv6 socket.
+ *
+ * 	If the *netns* is a negative signed 32-bit integer, then the
+ * 	socket lookup table in the netns associated with the *ctx* will
+ * 	will be used. For the TC hooks, this is the netns of the device
+ * 	in the skb. For socket hooks, this is the netns of the socket.
+ * 	If *netns* is any other signed 32-bit value greater than or
+ * 	equal to zero then it specifies the ID of the netns relative to
+ * 	the netns associated with the *ctx*. *netns* values beyond the
+ * 	range of 32-bit integers are reserved for future use.
+ *
+ * 	All values for *flags* are reserved for future usage, and must
+ * 	be left at zero.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_sk_lookup_udp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 85;
+
+/*
+ * bpf_sk_release
+ *
+ * 	Release the reference held by *sock*. *sock* must be a
+ * 	non-**NULL** pointer that was returned from
+ * 	**bpf_sk_lookup_xxx**\ ().
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_sk_release)(struct bpf_sock *sock) = (void *) 86;
+
+/*
+ * bpf_map_push_elem
+ *
+ * 	Push an element *value* in *map*. *flags* is one of:
+ *
+ * 	**BPF_EXIST**
+ * 		If the queue/stack is full, the oldest element is
+ * 		removed to make room for this.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_map_push_elem)(void *map, const void *value, __u64 flags) = (void *) 87;
+
+/*
+ * bpf_map_pop_elem
+ *
+ * 	Pop an element from *map*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_map_pop_elem)(void *map, void *value) = (void *) 88;
+
+/*
+ * bpf_map_peek_elem
+ *
+ * 	Get an element from *map* without removing it.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_map_peek_elem)(void *map, void *value) = (void *) 89;
+
+/*
+ * bpf_msg_push_data
+ *
+ * 	For socket policies, insert *len* bytes into *msg* at offset
+ * 	*start*.
+ *
+ * 	If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ * 	*msg* it may want to insert metadata or options into the *msg*.
+ * 	This can later be read and used by any of the lower layer BPF
+ * 	hooks.
+ *
+ * 	This helper may fail if under memory pressure (a malloc
+ * 	fails) in these cases BPF programs will get an appropriate
+ * 	error and BPF programs will need to handle them.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_msg_push_data)(struct sk_msg_md *msg, __u32 start, __u32 len, __u64 flags) = (void *) 90;
+
+/*
+ * bpf_msg_pop_data
+ *
+ * 	Will remove *len* bytes from a *msg* starting at byte *start*.
+ * 	This may result in **ENOMEM** errors under certain situations if
+ * 	an allocation and copy are required due to a full ring buffer.
+ * 	However, the helper will try to avoid doing the allocation
+ * 	if possible. Other errors can occur if input parameters are
+ * 	invalid either due to *start* byte not being valid part of *msg*
+ * 	payload and/or *pop* value being to large.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_msg_pop_data)(struct sk_msg_md *msg, __u32 start, __u32 len, __u64 flags) = (void *) 91;
+
+/*
+ * bpf_rc_pointer_rel
+ *
+ * 	This helper is used in programs implementing IR decoding, to
+ * 	report a successfully decoded pointer movement.
+ *
+ * 	The *ctx* should point to the lirc sample as passed into
+ * 	the program.
+ *
+ * 	This helper is only available is the kernel was compiled with
+ * 	the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ * 	"**y**".
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_rc_pointer_rel)(void *ctx, __s32 rel_x, __s32 rel_y) = (void *) 92;
+
+/*
+ * bpf_spin_lock
+ *
+ * 	Acquire a spinlock represented by the pointer *lock*, which is
+ * 	stored as part of a value of a map. Taking the lock allows to
+ * 	safely update the rest of the fields in that value. The
+ * 	spinlock can (and must) later be released with a call to
+ * 	**bpf_spin_unlock**\ (\ *lock*\ ).
+ *
+ * 	Spinlocks in BPF programs come with a number of restrictions
+ * 	and constraints:
+ *
+ * 	* **bpf_spin_lock** objects are only allowed inside maps of
+ * 	  types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
+ * 	  list could be extended in the future).
+ * 	* BTF description of the map is mandatory.
+ * 	* The BPF program can take ONE lock at a time, since taking two
+ * 	  or more could cause dead locks.
+ * 	* Only one **struct bpf_spin_lock** is allowed per map element.
+ * 	* When the lock is taken, calls (either BPF to BPF or helpers)
+ * 	  are not allowed.
+ * 	* The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
+ * 	  allowed inside a spinlock-ed region.
+ * 	* The BPF program MUST call **bpf_spin_unlock**\ () to release
+ * 	  the lock, on all execution paths, before it returns.
+ * 	* The BPF program can access **struct bpf_spin_lock** only via
+ * 	  the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
+ * 	  helpers. Loading or storing data into the **struct
+ * 	  bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
+ * 	* To use the **bpf_spin_lock**\ () helper, the BTF description
+ * 	  of the map value must be a struct and have **struct
+ * 	  bpf_spin_lock** *anyname*\ **;** field at the top level.
+ * 	  Nested lock inside another struct is not allowed.
+ * 	* The **struct bpf_spin_lock** *lock* field in a map value must
+ * 	  be aligned on a multiple of 4 bytes in that value.
+ * 	* Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
+ * 	  the **bpf_spin_lock** field to user space.
+ * 	* Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
+ * 	  a BPF program, do not update the **bpf_spin_lock** field.
+ * 	* **bpf_spin_lock** cannot be on the stack or inside a
+ * 	  networking packet (it can only be inside of a map values).
+ * 	* **bpf_spin_lock** is available to root only.
+ * 	* Tracing programs and socket filter programs cannot use
+ * 	  **bpf_spin_lock**\ () due to insufficient preemption checks
+ * 	  (but this may change in the future).
+ * 	* **bpf_spin_lock** is not allowed in inner maps of map-in-map.
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_spin_lock)(struct bpf_spin_lock *lock) = (void *) 93;
+
+/*
+ * bpf_spin_unlock
+ *
+ * 	Release the *lock* previously locked by a call to
+ * 	**bpf_spin_lock**\ (\ *lock*\ ).
+ *
+ * Returns
+ * 	0
+ */
+static int (*bpf_spin_unlock)(struct bpf_spin_lock *lock) = (void *) 94;
+
+/*
+ * bpf_sk_fullsock
+ *
+ * 	This helper gets a **struct bpf_sock** pointer such
+ * 	that all the fields in this **bpf_sock** can be accessed.
+ *
+ * Returns
+ * 	A **struct bpf_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_sock *(*bpf_sk_fullsock)(struct bpf_sock *sk) = (void *) 95;
+
+/*
+ * bpf_tcp_sock
+ *
+ * 	This helper gets a **struct bpf_tcp_sock** pointer from a
+ * 	**struct bpf_sock** pointer.
+ *
+ * Returns
+ * 	A **struct bpf_tcp_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_tcp_sock *(*bpf_tcp_sock)(struct bpf_sock *sk) = (void *) 96;
+
+/*
+ * bpf_skb_ecn_set_ce
+ *
+ * 	Set ECN (Explicit Congestion Notification) field of IP header
+ * 	to **CE** (Congestion Encountered) if current value is **ECT**
+ * 	(ECN Capable Transport). Otherwise, do nothing. Works with IPv6
+ * 	and IPv4.
+ *
+ * Returns
+ * 	1 if the **CE** flag is set (either by the current helper call
+ * 	or because it was already present), 0 if it is not set.
+ */
+static int (*bpf_skb_ecn_set_ce)(struct __sk_buff *skb) = (void *) 97;
+
+/*
+ * bpf_get_listener_sock
+ *
+ * 	Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
+ * 	**bpf_sk_release**\ () is unnecessary and not allowed.
+ *
+ * Returns
+ * 	A **struct bpf_sock** pointer on success, or **NULL** in
+ * 	case of failure.
+ */
+static struct bpf_sock *(*bpf_get_listener_sock)(struct bpf_sock *sk) = (void *) 98;
+
+/*
+ * bpf_skc_lookup_tcp
+ *
+ * 	Look for TCP socket matching *tuple*, optionally in a child
+ * 	network namespace *netns*. The return value must be checked,
+ * 	and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ * 	This function is identical to **bpf_sk_lookup_tcp**\ (), except
+ * 	that it also returns timewait or request sockets. Use
+ * 	**bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
+ * 	full structure.
+ *
+ * 	This helper is available only if the kernel was compiled with
+ * 	**CONFIG_NET** configuration option.
+ *
+ * Returns
+ * 	Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ * 	For sockets with reuseport option, the **struct bpf_sock**
+ * 	result is from *reuse*\ **->socks**\ [] using the hash of the
+ * 	tuple.
+ */
+static struct bpf_sock *(*bpf_skc_lookup_tcp)(void *ctx, struct bpf_sock_tuple *tuple, __u32 tuple_size, __u64 netns, __u64 flags) = (void *) 99;
+
+/*
+ * bpf_tcp_check_syncookie
+ *
+ * 	Check whether *iph* and *th* contain a valid SYN cookie ACK for
+ * 	the listening socket in *sk*.
+ *
+ * 	*iph* points to the start of the IPv4 or IPv6 header, while
+ * 	*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ * 	**sizeof**\ (**struct ip6hdr**).
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains **sizeof**\ (**struct tcphdr**).
+ *
+ *
+ * Returns
+ * 	0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
+ * 	error otherwise.
+ */
+static int (*bpf_tcp_check_syncookie)(struct bpf_sock *sk, void *iph, __u32 iph_len, struct tcphdr *th, __u32 th_len) = (void *) 100;
+
+/*
+ * bpf_sysctl_get_name
+ *
+ * 	Get name of sysctl in /proc/sys/ and copy it into provided by
+ * 	program buffer *buf* of size *buf_len*.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * 	If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
+ * 	copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
+ * 	only (e.g. "tcp_mem").
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ */
+static int (*bpf_sysctl_get_name)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len, __u64 flags) = (void *) 101;
+
+/*
+ * bpf_sysctl_get_current_value
+ *
+ * 	Get current value of sysctl as it is presented in /proc/sys
+ * 	(incl. newline, etc), and copy it as a string into provided
+ * 	by program buffer *buf* of size *buf_len*.
+ *
+ * 	The whole value is copied, no matter what file position user
+ * 	space issued e.g. sys_read at.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ *
+ * 	**-EINVAL** if current value was unavailable, e.g. because
+ * 	sysctl is uninitialized and read returns -EIO for it.
+ */
+static int (*bpf_sysctl_get_current_value)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len) = (void *) 102;
+
+/*
+ * bpf_sysctl_get_new_value
+ *
+ * 	Get new value being written by user space to sysctl (before
+ * 	the actual write happens) and copy it as a string into
+ * 	provided by program buffer *buf* of size *buf_len*.
+ *
+ * 	User space may write new value at file position > 0.
+ *
+ * 	The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ * Returns
+ * 	Number of character copied (not including the trailing NUL).
+ *
+ * 	**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ * 	truncated name in this case).
+ *
+ * 	**-EINVAL** if sysctl is being read.
+ */
+static int (*bpf_sysctl_get_new_value)(struct bpf_sysctl *ctx, char *buf, unsigned long buf_len) = (void *) 103;
+
+/*
+ * bpf_sysctl_set_new_value
+ *
+ * 	Override new value being written by user space to sysctl with
+ * 	value provided by program in buffer *buf* of size *buf_len*.
+ *
+ * 	*buf* should contain a string in same form as provided by user
+ * 	space on sysctl write.
+ *
+ * 	User space may write new value at file position > 0. To override
+ * 	the whole sysctl value file position should be set to zero.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-E2BIG** if the *buf_len* is too big.
+ *
+ * 	**-EINVAL** if sysctl is being read.
+ */
+static int (*bpf_sysctl_set_new_value)(struct bpf_sysctl *ctx, const char *buf, unsigned long buf_len) = (void *) 104;
+
+/*
+ * bpf_strtol
+ *
+ * 	Convert the initial part of the string from buffer *buf* of
+ * 	size *buf_len* to a long integer according to the given base
+ * 	and save the result in *res*.
+ *
+ * 	The string may begin with an arbitrary amount of white space
+ * 	(as determined by **isspace**\ (3)) followed by a single
+ * 	optional '**-**' sign.
+ *
+ * 	Five least significant bits of *flags* encode base, other bits
+ * 	are currently unused.
+ *
+ * 	Base must be either 8, 10, 16 or 0 to detect it automatically
+ * 	similar to user space **strtol**\ (3).
+ *
+ * Returns
+ * 	Number of characters consumed on success. Must be positive but
+ * 	no more than *buf_len*.
+ *
+ * 	**-EINVAL** if no valid digits were found or unsupported base
+ * 	was provided.
+ *
+ * 	**-ERANGE** if resulting value was out of range.
+ */
+static int (*bpf_strtol)(const char *buf, unsigned long buf_len, __u64 flags, long *res) = (void *) 105;
+
+/*
+ * bpf_strtoul
+ *
+ * 	Convert the initial part of the string from buffer *buf* of
+ * 	size *buf_len* to an unsigned long integer according to the
+ * 	given base and save the result in *res*.
+ *
+ * 	The string may begin with an arbitrary amount of white space
+ * 	(as determined by **isspace**\ (3)).
+ *
+ * 	Five least significant bits of *flags* encode base, other bits
+ * 	are currently unused.
+ *
+ * 	Base must be either 8, 10, 16 or 0 to detect it automatically
+ * 	similar to user space **strtoul**\ (3).
+ *
+ * Returns
+ * 	Number of characters consumed on success. Must be positive but
+ * 	no more than *buf_len*.
+ *
+ * 	**-EINVAL** if no valid digits were found or unsupported base
+ * 	was provided.
+ *
+ * 	**-ERANGE** if resulting value was out of range.
+ */
+static int (*bpf_strtoul)(const char *buf, unsigned long buf_len, __u64 flags, unsigned long *res) = (void *) 106;
+
+/*
+ * bpf_sk_storage_get
+ *
+ * 	Get a bpf-local-storage from a *sk*.
+ *
+ * 	Logically, it could be thought of getting the value from
+ * 	a *map* with *sk* as the **key**.  From this
+ * 	perspective,  the usage is not much different from
+ * 	**bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
+ * 	helper enforces the key must be a full socket and the map must
+ * 	be a **BPF_MAP_TYPE_SK_STORAGE** also.
+ *
+ * 	Underneath, the value is stored locally at *sk* instead of
+ * 	the *map*.  The *map* is used as the bpf-local-storage
+ * 	"type". The bpf-local-storage "type" (i.e. the *map*) is
+ * 	searched against all bpf-local-storages residing at *sk*.
+ *
+ * 	An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
+ * 	used such that a new bpf-local-storage will be
+ * 	created if one does not exist.  *value* can be used
+ * 	together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
+ * 	the initial value of a bpf-local-storage.  If *value* is
+ * 	**NULL**, the new bpf-local-storage will be zero initialized.
+ *
+ * Returns
+ * 	A bpf-local-storage pointer is returned on success.
+ *
+ * 	**NULL** if not found or there was an error in adding
+ * 	a new bpf-local-storage.
+ */
+static void *(*bpf_sk_storage_get)(void *map, struct bpf_sock *sk, void *value, __u64 flags) = (void *) 107;
+
+/*
+ * bpf_sk_storage_delete
+ *
+ * 	Delete a bpf-local-storage from a *sk*.
+ *
+ * Returns
+ * 	0 on success.
+ *
+ * 	**-ENOENT** if the bpf-local-storage cannot be found.
+ */
+static int (*bpf_sk_storage_delete)(void *map, struct bpf_sock *sk) = (void *) 108;
+
+/*
+ * bpf_send_signal
+ *
+ * 	Send signal *sig* to the current task.
+ *
+ * Returns
+ * 	0 on success or successfully queued.
+ *
+ * 	**-EBUSY** if work queue under nmi is full.
+ *
+ * 	**-EINVAL** if *sig* is invalid.
+ *
+ * 	**-EPERM** if no permission to send the *sig*.
+ *
+ * 	**-EAGAIN** if bpf program can try again.
+ */
+static int (*bpf_send_signal)(__u32 sig) = (void *) 109;
+
+/*
+ * bpf_tcp_gen_syncookie
+ *
+ * 	Try to issue a SYN cookie for the packet with corresponding
+ * 	IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
+ *
+ * 	*iph* points to the start of the IPv4 or IPv6 header, while
+ * 	*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ * 	**sizeof**\ (**struct ip6hdr**).
+ *
+ * 	*th* points to the start of the TCP header, while *th_len*
+ * 	contains the length of the TCP header.
+ *
+ *
+ * Returns
+ * 	On success, lower 32 bits hold the generated SYN cookie in
+ * 	followed by 16 bits which hold the MSS value for that cookie,
+ * 	and the top 16 bits are unused.
+ *
+ * 	On failure, the returned value is one of the following:
+ *
+ * 	**-EINVAL** SYN cookie cannot be issued due to error
+ *
+ * 	**-ENOENT** SYN cookie should not be issued (no SYN flood)
+ *
+ * 	**-EOPNOTSUPP** kernel configuration does not enable SYN cookies
+ *
+ * 	**-EPROTONOSUPPORT** IP packet version is not 4 or 6
+ */
+static __s64 (*bpf_tcp_gen_syncookie)(struct bpf_sock *sk, void *iph, __u32 iph_len, struct tcphdr *th, __u32 th_len) = (void *) 110;
+
+/*
+ * bpf_skb_output
+ *
+ * 	Write raw *data* blob into a special BPF perf event held by
+ * 	*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 	event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 	as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 	**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 	The *flags* are used to indicate the index in *map* for which
+ * 	the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 	Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 	to indicate that the index of the current CPU core should be
+ * 	used.
+ *
+ * 	The value to write, of *size*, is passed through eBPF stack and
+ * 	pointed by *data*.
+ *
+ * 	*ctx* is a pointer to in-kernel struct sk_buff.
+ *
+ * 	This helper is similar to **bpf_perf_event_output**\ () but
+ * 	restricted to raw_tracepoint bpf programs.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_skb_output)(void *ctx, void *map, __u64 flags, void *data, __u64 size) = (void *) 111;
+
+/*
+ * bpf_probe_read_user
+ *
+ * 	Safely attempt to read *size* bytes from user space address
+ * 	*unsafe_ptr* and store the data in *dst*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_probe_read_user)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 112;
+
+/*
+ * bpf_probe_read_kernel
+ *
+ * 	Safely attempt to read *size* bytes from kernel space address
+ * 	*unsafe_ptr* and store the data in *dst*.
+ *
+ * Returns
+ * 	0 on success, or a negative error in case of failure.
+ */
+static int (*bpf_probe_read_kernel)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 113;
+
+/*
+ * bpf_probe_read_user_str
+ *
+ * 	Copy a NUL terminated string from an unsafe user address
+ * 	*unsafe_ptr* to *dst*. The *size* should include the
+ * 	terminating NUL byte. In case the string length is smaller than
+ * 	*size*, the target is not padded with further NUL bytes. If the
+ * 	string length is larger than *size*, just *size*-1 bytes are
+ * 	copied and the last byte is set to NUL.
+ *
+ * 	On success, the length of the copied string is returned. This
+ * 	makes this helper useful in tracing programs for reading
+ * 	strings, and more importantly to get its length at runtime. See
+ * 	the following snippet:
+ *
+ * 	::
+ *
+ * 		SEC("kprobe/sys_open")
+ * 		void bpf_sys_open(struct pt_regs *ctx)
+ * 		{
+ * 		        char buf[PATHLEN]; // PATHLEN is defined to 256
+ * 		        int res = bpf_probe_read_user_str(buf, sizeof(buf),
+ * 			                                  ctx->di);
+ *
+ * 			// Consume buf, for example push it to
+ * 			// userspace via bpf_perf_event_output(); we
+ * 			// can use res (the string length) as event
+ * 			// size, after checking its boundaries.
+ * 		}
+ *
+ * 	In comparison, using **bpf_probe_read_user()** helper here
+ * 	instead to read the string would require to estimate the length
+ * 	at compile time, and would often result in copying more memory
+ * 	than necessary.
+ *
+ * 	Another useful use case is when parsing individual process
+ * 	arguments or individual environment variables navigating
+ * 	*current*\ **->mm->arg_start** and *current*\
+ * 	**->mm->env_start**: using this helper and the return value,
+ * 	one can quickly iterate at the right offset of the memory area.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string,
+ * 	including the trailing NUL character. On error, a negative
+ * 	value.
+ */
+static int (*bpf_probe_read_user_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 114;
+
+/*
+ * bpf_probe_read_kernel_str
+ *
+ * 	Copy a NUL terminated string from an unsafe kernel address *unsafe_ptr*
+ * 	to *dst*. Same semantics as with bpf_probe_read_user_str() apply.
+ *
+ * Returns
+ * 	On success, the strictly positive length of the string,	including
+ * 	the trailing NUL character. On error, a negative value.
+ */
+static int (*bpf_probe_read_kernel_str)(void *dst, __u32 size, const void *unsafe_ptr) = (void *) 115;
+
+
diff --git a/src/contrib/libbpf/bpf/bpf_helpers.h b/src/contrib/libbpf/bpf/bpf_helpers.h
new file mode 100644
index 0000000..0c7d282
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_helpers.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_HELPERS__
+#define __BPF_HELPERS__
+
+#include "bpf_helper_defs.h"
+
+#define __uint(name, val) int (*name)[val]
+#define __type(name, val) typeof(val) *name
+
+/* Helper macro to print out debug messages */
+#define bpf_printk(fmt, ...)				\
+({							\
+	char ____fmt[] = fmt;				\
+	bpf_trace_printk(____fmt, sizeof(____fmt),	\
+			 ##__VA_ARGS__);		\
+})
+
+/*
+ * Helper macro to place programs, maps, license in
+ * different sections in elf_bpf file. Section names
+ * are interpreted by elf_bpf loader
+ */
+#define SEC(NAME) __attribute__((section(NAME), used))
+
+#ifndef __always_inline
+#define __always_inline __attribute__((always_inline))
+#endif
+
+/*
+ * Helper structure used by eBPF C program
+ * to describe BPF map attributes to libbpf loader
+ */
+struct bpf_map_def {
+	unsigned int type;
+	unsigned int key_size;
+	unsigned int value_size;
+	unsigned int max_entries;
+	unsigned int map_flags;
+};
+
+enum libbpf_pin_type {
+	LIBBPF_PIN_NONE,
+	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
+	LIBBPF_PIN_BY_NAME,
+};
+
+#endif
diff --git a/src/contrib/libbpf/bpf/bpf_prog_linfo.c b/src/contrib/libbpf/bpf/bpf_prog_linfo.c
new file mode 100644
index 0000000..3ed1a27
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_prog_linfo.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <string.h>
+#include <stdlib.h>
+#include <linux/err.h>
+#include <linux/bpf.h>
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+struct bpf_prog_linfo {
+	void *raw_linfo;
+	void *raw_jited_linfo;
+	__u32 *nr_jited_linfo_per_func;
+	__u32 *jited_linfo_func_idx;
+	__u32 nr_linfo;
+	__u32 nr_jited_func;
+	__u32 rec_size;
+	__u32 jited_rec_size;
+};
+
+static int dissect_jited_func(struct bpf_prog_linfo *prog_linfo,
+			      const __u64 *ksym_func, const __u32 *ksym_len)
+{
+	__u32 nr_jited_func, nr_linfo;
+	const void *raw_jited_linfo;
+	const __u64 *jited_linfo;
+	__u64 last_jited_linfo;
+	/*
+	 * Index to raw_jited_linfo:
+	 *      i: Index for searching the next ksym_func
+	 * prev_i: Index to the last found ksym_func
+	 */
+	__u32 i, prev_i;
+	__u32 f; /* Index to ksym_func */
+
+	raw_jited_linfo = prog_linfo->raw_jited_linfo;
+	jited_linfo = raw_jited_linfo;
+	if (ksym_func[0] != *jited_linfo)
+		goto errout;
+
+	prog_linfo->jited_linfo_func_idx[0] = 0;
+	nr_jited_func = prog_linfo->nr_jited_func;
+	nr_linfo = prog_linfo->nr_linfo;
+
+	for (prev_i = 0, i = 1, f = 1;
+	     i < nr_linfo && f < nr_jited_func;
+	     i++) {
+		raw_jited_linfo += prog_linfo->jited_rec_size;
+		last_jited_linfo = *jited_linfo;
+		jited_linfo = raw_jited_linfo;
+
+		if (ksym_func[f] == *jited_linfo) {
+			prog_linfo->jited_linfo_func_idx[f] = i;
+
+			/* Sanity check */
+			if (last_jited_linfo - ksym_func[f - 1] + 1 >
+			    ksym_len[f - 1])
+				goto errout;
+
+			prog_linfo->nr_jited_linfo_per_func[f - 1] =
+				i - prev_i;
+			prev_i = i;
+
+			/*
+			 * The ksym_func[f] is found in jited_linfo.
+			 * Look for the next one.
+			 */
+			f++;
+		} else if (*jited_linfo <= last_jited_linfo) {
+			/* Ensure the addr is increasing _within_ a func */
+			goto errout;
+		}
+	}
+
+	if (f != nr_jited_func)
+		goto errout;
+
+	prog_linfo->nr_jited_linfo_per_func[nr_jited_func - 1] =
+		nr_linfo - prev_i;
+
+	return 0;
+
+errout:
+	return -EINVAL;
+}
+
+void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo)
+{
+	if (!prog_linfo)
+		return;
+
+	free(prog_linfo->raw_linfo);
+	free(prog_linfo->raw_jited_linfo);
+	free(prog_linfo->nr_jited_linfo_per_func);
+	free(prog_linfo->jited_linfo_func_idx);
+	free(prog_linfo);
+}
+
+struct bpf_prog_linfo *bpf_prog_linfo__new(const struct bpf_prog_info *info)
+{
+	struct bpf_prog_linfo *prog_linfo;
+	__u32 nr_linfo, nr_jited_func;
+	__u64 data_sz;
+
+	nr_linfo = info->nr_line_info;
+
+	if (!nr_linfo)
+		return NULL;
+
+	/*
+	 * The min size that bpf_prog_linfo has to access for
+	 * searching purpose.
+	 */
+	if (info->line_info_rec_size <
+	    offsetof(struct bpf_line_info, file_name_off))
+		return NULL;
+
+	prog_linfo = calloc(1, sizeof(*prog_linfo));
+	if (!prog_linfo)
+		return NULL;
+
+	/* Copy xlated line_info */
+	prog_linfo->nr_linfo = nr_linfo;
+	prog_linfo->rec_size = info->line_info_rec_size;
+	data_sz = (__u64)nr_linfo * prog_linfo->rec_size;
+	prog_linfo->raw_linfo = malloc(data_sz);
+	if (!prog_linfo->raw_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_linfo, (void *)(long)info->line_info, data_sz);
+
+	nr_jited_func = info->nr_jited_ksyms;
+	if (!nr_jited_func ||
+	    !info->jited_line_info ||
+	    info->nr_jited_line_info != nr_linfo ||
+	    info->jited_line_info_rec_size < sizeof(__u64) ||
+	    info->nr_jited_func_lens != nr_jited_func ||
+	    !info->jited_ksyms ||
+	    !info->jited_func_lens)
+		/* Not enough info to provide jited_line_info */
+		return prog_linfo;
+
+	/* Copy jited_line_info */
+	prog_linfo->nr_jited_func = nr_jited_func;
+	prog_linfo->jited_rec_size = info->jited_line_info_rec_size;
+	data_sz = (__u64)nr_linfo * prog_linfo->jited_rec_size;
+	prog_linfo->raw_jited_linfo = malloc(data_sz);
+	if (!prog_linfo->raw_jited_linfo)
+		goto err_free;
+	memcpy(prog_linfo->raw_jited_linfo,
+	       (void *)(long)info->jited_line_info, data_sz);
+
+	/* Number of jited_line_info per jited func */
+	prog_linfo->nr_jited_linfo_per_func = malloc(nr_jited_func *
+						     sizeof(__u32));
+	if (!prog_linfo->nr_jited_linfo_per_func)
+		goto err_free;
+
+	/*
+	 * For each jited func,
+	 * the start idx to the "linfo" and "jited_linfo" array,
+	 */
+	prog_linfo->jited_linfo_func_idx = malloc(nr_jited_func *
+						  sizeof(__u32));
+	if (!prog_linfo->jited_linfo_func_idx)
+		goto err_free;
+
+	if (dissect_jited_func(prog_linfo,
+			       (__u64 *)(long)info->jited_ksyms,
+			       (__u32 *)(long)info->jited_func_lens))
+		goto err_free;
+
+	return prog_linfo;
+
+err_free:
+	bpf_prog_linfo__free(prog_linfo);
+	return NULL;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip)
+{
+	__u32 jited_rec_size, rec_size, nr_linfo, start, i;
+	const void *raw_jited_linfo, *raw_linfo;
+	const __u64 *jited_linfo;
+
+	if (func_idx >= prog_linfo->nr_jited_func)
+		return NULL;
+
+	nr_linfo = prog_linfo->nr_jited_linfo_per_func[func_idx];
+	if (nr_skip >= nr_linfo)
+		return NULL;
+
+	start = prog_linfo->jited_linfo_func_idx[func_idx] + nr_skip;
+	jited_rec_size = prog_linfo->jited_rec_size;
+	raw_jited_linfo = prog_linfo->raw_jited_linfo +
+		(start * jited_rec_size);
+	jited_linfo = raw_jited_linfo;
+	if (addr < *jited_linfo)
+		return NULL;
+
+	nr_linfo -= nr_skip;
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (start * rec_size);
+	for (i = 0; i < nr_linfo; i++) {
+		if (addr < *jited_linfo)
+			break;
+
+		raw_linfo += rec_size;
+		raw_jited_linfo += jited_rec_size;
+		jited_linfo = raw_jited_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}
+
+const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip)
+{
+	const struct bpf_line_info *linfo;
+	__u32 rec_size, nr_linfo, i;
+	const void *raw_linfo;
+
+	nr_linfo = prog_linfo->nr_linfo;
+	if (nr_skip >= nr_linfo)
+		return NULL;
+
+	rec_size = prog_linfo->rec_size;
+	raw_linfo = prog_linfo->raw_linfo + (nr_skip * rec_size);
+	linfo = raw_linfo;
+	if (insn_off < linfo->insn_off)
+		return NULL;
+
+	nr_linfo -= nr_skip;
+	for (i = 0; i < nr_linfo; i++) {
+		if (insn_off < linfo->insn_off)
+			break;
+
+		raw_linfo += rec_size;
+		linfo = raw_linfo;
+	}
+
+	return raw_linfo - rec_size;
+}
diff --git a/src/contrib/libbpf/bpf/bpf_tracing.h b/src/contrib/libbpf/bpf/bpf_tracing.h
new file mode 100644
index 0000000..b0dafe8
--- /dev/null
+++ b/src/contrib/libbpf/bpf/bpf_tracing.h
@@ -0,0 +1,195 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __BPF_TRACING_H__
+#define __BPF_TRACING_H__
+
+/* Scan the ARCH passed in from ARCH env variable (see Makefile) */
+#if defined(__TARGET_ARCH_x86)
+	#define bpf_target_x86
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_s390)
+	#define bpf_target_s390
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arm)
+	#define bpf_target_arm
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_arm64)
+	#define bpf_target_arm64
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_mips)
+	#define bpf_target_mips
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_powerpc)
+	#define bpf_target_powerpc
+	#define bpf_target_defined
+#elif defined(__TARGET_ARCH_sparc)
+	#define bpf_target_sparc
+	#define bpf_target_defined
+#else
+	#undef bpf_target_defined
+#endif
+
+/* Fall back to what the compiler says */
+#ifndef bpf_target_defined
+#if defined(__x86_64__)
+	#define bpf_target_x86
+#elif defined(__s390__)
+	#define bpf_target_s390
+#elif defined(__arm__)
+	#define bpf_target_arm
+#elif defined(__aarch64__)
+	#define bpf_target_arm64
+#elif defined(__mips__)
+	#define bpf_target_mips
+#elif defined(__powerpc__)
+	#define bpf_target_powerpc
+#elif defined(__sparc__)
+	#define bpf_target_sparc
+#endif
+#endif
+
+#if defined(bpf_target_x86)
+
+#ifdef __KERNEL__
+#define PT_REGS_PARM1(x) ((x)->di)
+#define PT_REGS_PARM2(x) ((x)->si)
+#define PT_REGS_PARM3(x) ((x)->dx)
+#define PT_REGS_PARM4(x) ((x)->cx)
+#define PT_REGS_PARM5(x) ((x)->r8)
+#define PT_REGS_RET(x) ((x)->sp)
+#define PT_REGS_FP(x) ((x)->bp)
+#define PT_REGS_RC(x) ((x)->ax)
+#define PT_REGS_SP(x) ((x)->sp)
+#define PT_REGS_IP(x) ((x)->ip)
+#else
+#ifdef __i386__
+/* i386 kernel is built with -mregparm=3 */
+#define PT_REGS_PARM1(x) ((x)->eax)
+#define PT_REGS_PARM2(x) ((x)->edx)
+#define PT_REGS_PARM3(x) ((x)->ecx)
+#define PT_REGS_PARM4(x) 0
+#define PT_REGS_PARM5(x) 0
+#define PT_REGS_RET(x) ((x)->esp)
+#define PT_REGS_FP(x) ((x)->ebp)
+#define PT_REGS_RC(x) ((x)->eax)
+#define PT_REGS_SP(x) ((x)->esp)
+#define PT_REGS_IP(x) ((x)->eip)
+#else
+#define PT_REGS_PARM1(x) ((x)->rdi)
+#define PT_REGS_PARM2(x) ((x)->rsi)
+#define PT_REGS_PARM3(x) ((x)->rdx)
+#define PT_REGS_PARM4(x) ((x)->rcx)
+#define PT_REGS_PARM5(x) ((x)->r8)
+#define PT_REGS_RET(x) ((x)->rsp)
+#define PT_REGS_FP(x) ((x)->rbp)
+#define PT_REGS_RC(x) ((x)->rax)
+#define PT_REGS_SP(x) ((x)->rsp)
+#define PT_REGS_IP(x) ((x)->rip)
+#endif
+#endif
+
+#elif defined(bpf_target_s390)
+
+/* s390 provides user_pt_regs instead of struct pt_regs to userspace */
+struct pt_regs;
+#define PT_REGS_S390 const volatile user_pt_regs
+#define PT_REGS_PARM1(x) (((PT_REGS_S390 *)(x))->gprs[2])
+#define PT_REGS_PARM2(x) (((PT_REGS_S390 *)(x))->gprs[3])
+#define PT_REGS_PARM3(x) (((PT_REGS_S390 *)(x))->gprs[4])
+#define PT_REGS_PARM4(x) (((PT_REGS_S390 *)(x))->gprs[5])
+#define PT_REGS_PARM5(x) (((PT_REGS_S390 *)(x))->gprs[6])
+#define PT_REGS_RET(x) (((PT_REGS_S390 *)(x))->gprs[14])
+/* Works only with CONFIG_FRAME_POINTER */
+#define PT_REGS_FP(x) (((PT_REGS_S390 *)(x))->gprs[11])
+#define PT_REGS_RC(x) (((PT_REGS_S390 *)(x))->gprs[2])
+#define PT_REGS_SP(x) (((PT_REGS_S390 *)(x))->gprs[15])
+#define PT_REGS_IP(x) (((PT_REGS_S390 *)(x))->psw.addr)
+
+#elif defined(bpf_target_arm)
+
+#define PT_REGS_PARM1(x) ((x)->uregs[0])
+#define PT_REGS_PARM2(x) ((x)->uregs[1])
+#define PT_REGS_PARM3(x) ((x)->uregs[2])
+#define PT_REGS_PARM4(x) ((x)->uregs[3])
+#define PT_REGS_PARM5(x) ((x)->uregs[4])
+#define PT_REGS_RET(x) ((x)->uregs[14])
+#define PT_REGS_FP(x) ((x)->uregs[11]) /* Works only with CONFIG_FRAME_POINTER */
+#define PT_REGS_RC(x) ((x)->uregs[0])
+#define PT_REGS_SP(x) ((x)->uregs[13])
+#define PT_REGS_IP(x) ((x)->uregs[12])
+
+#elif defined(bpf_target_arm64)
+
+/* arm64 provides struct user_pt_regs instead of struct pt_regs to userspace */
+struct pt_regs;
+#define PT_REGS_ARM64 const volatile struct user_pt_regs
+#define PT_REGS_PARM1(x) (((PT_REGS_ARM64 *)(x))->regs[0])
+#define PT_REGS_PARM2(x) (((PT_REGS_ARM64 *)(x))->regs[1])
+#define PT_REGS_PARM3(x) (((PT_REGS_ARM64 *)(x))->regs[2])
+#define PT_REGS_PARM4(x) (((PT_REGS_ARM64 *)(x))->regs[3])
+#define PT_REGS_PARM5(x) (((PT_REGS_ARM64 *)(x))->regs[4])
+#define PT_REGS_RET(x) (((PT_REGS_ARM64 *)(x))->regs[30])
+/* Works only with CONFIG_FRAME_POINTER */
+#define PT_REGS_FP(x) (((PT_REGS_ARM64 *)(x))->regs[29])
+#define PT_REGS_RC(x) (((PT_REGS_ARM64 *)(x))->regs[0])
+#define PT_REGS_SP(x) (((PT_REGS_ARM64 *)(x))->sp)
+#define PT_REGS_IP(x) (((PT_REGS_ARM64 *)(x))->pc)
+
+#elif defined(bpf_target_mips)
+
+#define PT_REGS_PARM1(x) ((x)->regs[4])
+#define PT_REGS_PARM2(x) ((x)->regs[5])
+#define PT_REGS_PARM3(x) ((x)->regs[6])
+#define PT_REGS_PARM4(x) ((x)->regs[7])
+#define PT_REGS_PARM5(x) ((x)->regs[8])
+#define PT_REGS_RET(x) ((x)->regs[31])
+#define PT_REGS_FP(x) ((x)->regs[30]) /* Works only with CONFIG_FRAME_POINTER */
+#define PT_REGS_RC(x) ((x)->regs[1])
+#define PT_REGS_SP(x) ((x)->regs[29])
+#define PT_REGS_IP(x) ((x)->cp0_epc)
+
+#elif defined(bpf_target_powerpc)
+
+#define PT_REGS_PARM1(x) ((x)->gpr[3])
+#define PT_REGS_PARM2(x) ((x)->gpr[4])
+#define PT_REGS_PARM3(x) ((x)->gpr[5])
+#define PT_REGS_PARM4(x) ((x)->gpr[6])
+#define PT_REGS_PARM5(x) ((x)->gpr[7])
+#define PT_REGS_RC(x) ((x)->gpr[3])
+#define PT_REGS_SP(x) ((x)->sp)
+#define PT_REGS_IP(x) ((x)->nip)
+
+#elif defined(bpf_target_sparc)
+
+#define PT_REGS_PARM1(x) ((x)->u_regs[UREG_I0])
+#define PT_REGS_PARM2(x) ((x)->u_regs[UREG_I1])
+#define PT_REGS_PARM3(x) ((x)->u_regs[UREG_I2])
+#define PT_REGS_PARM4(x) ((x)->u_regs[UREG_I3])
+#define PT_REGS_PARM5(x) ((x)->u_regs[UREG_I4])
+#define PT_REGS_RET(x) ((x)->u_regs[UREG_I7])
+#define PT_REGS_RC(x) ((x)->u_regs[UREG_I0])
+#define PT_REGS_SP(x) ((x)->u_regs[UREG_FP])
+
+/* Should this also be a bpf_target check for the sparc case? */
+#if defined(__arch64__)
+#define PT_REGS_IP(x) ((x)->tpc)
+#else
+#define PT_REGS_IP(x) ((x)->pc)
+#endif
+
+#endif
+
+#if defined(bpf_target_powerpc)
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = (ctx)->link; })
+#define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
+#elif defined(bpf_target_sparc)
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)		({ (ip) = PT_REGS_RET(ctx); })
+#define BPF_KRETPROBE_READ_RET_IP		BPF_KPROBE_READ_RET_IP
+#else
+#define BPF_KPROBE_READ_RET_IP(ip, ctx)					    \
+	({ bpf_probe_read(&(ip), sizeof(ip), (void *)PT_REGS_RET(ctx)); })
+#define BPF_KRETPROBE_READ_RET_IP(ip, ctx)				    \
+	({ bpf_probe_read(&(ip), sizeof(ip),				    \
+			  (void *)(PT_REGS_FP(ctx) + sizeof(ip))); })
+#endif
+
+#endif
diff --git a/src/contrib/libbpf/bpf/btf.c b/src/contrib/libbpf/bpf/btf.c
new file mode 100644
index 0000000..88efa2b
--- /dev/null
+++ b/src/contrib/libbpf/bpf/btf.c
@@ -0,0 +1,2884 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <endian.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include <gelf.h>
+#include "btf.h"
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+
+#define BTF_MAX_NR_TYPES 0x7fffffff
+#define BTF_MAX_STR_OFFSET 0x7fffffff
+
+static struct btf_type btf_void;
+
+struct btf {
+	union {
+		struct btf_header *hdr;
+		void *data;
+	};
+	struct btf_type **types;
+	const char *strings;
+	void *nohdr_data;
+	__u32 nr_types;
+	__u32 types_size;
+	__u32 data_size;
+	int fd;
+};
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+static int btf_add_type(struct btf *btf, struct btf_type *t)
+{
+	if (btf->types_size - btf->nr_types < 2) {
+		struct btf_type **new_types;
+		__u32 expand_by, new_size;
+
+		if (btf->types_size == BTF_MAX_NR_TYPES)
+			return -E2BIG;
+
+		expand_by = max(btf->types_size >> 2, 16);
+		new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
+
+		new_types = realloc(btf->types, sizeof(*new_types) * new_size);
+		if (!new_types)
+			return -ENOMEM;
+
+		if (btf->nr_types == 0)
+			new_types[0] = &btf_void;
+
+		btf->types = new_types;
+		btf->types_size = new_size;
+	}
+
+	btf->types[++(btf->nr_types)] = t;
+
+	return 0;
+}
+
+static int btf_parse_hdr(struct btf *btf)
+{
+	const struct btf_header *hdr = btf->hdr;
+	__u32 meta_left;
+
+	if (btf->data_size < sizeof(struct btf_header)) {
+		pr_debug("BTF header not found\n");
+		return -EINVAL;
+	}
+
+	if (hdr->magic != BTF_MAGIC) {
+		pr_debug("Invalid BTF magic:%x\n", hdr->magic);
+		return -EINVAL;
+	}
+
+	if (hdr->version != BTF_VERSION) {
+		pr_debug("Unsupported BTF version:%u\n", hdr->version);
+		return -ENOTSUP;
+	}
+
+	if (hdr->flags) {
+		pr_debug("Unsupported BTF flags:%x\n", hdr->flags);
+		return -ENOTSUP;
+	}
+
+	meta_left = btf->data_size - sizeof(*hdr);
+	if (!meta_left) {
+		pr_debug("BTF has no data\n");
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->type_off) {
+		pr_debug("Invalid BTF type section offset:%u\n", hdr->type_off);
+		return -EINVAL;
+	}
+
+	if (meta_left < hdr->str_off) {
+		pr_debug("Invalid BTF string section offset:%u\n", hdr->str_off);
+		return -EINVAL;
+	}
+
+	if (hdr->type_off >= hdr->str_off) {
+		pr_debug("BTF type section offset >= string section offset. No type?\n");
+		return -EINVAL;
+	}
+
+	if (hdr->type_off & 0x02) {
+		pr_debug("BTF type section is not aligned to 4 bytes\n");
+		return -EINVAL;
+	}
+
+	btf->nohdr_data = btf->hdr + 1;
+
+	return 0;
+}
+
+static int btf_parse_str_sec(struct btf *btf)
+{
+	const struct btf_header *hdr = btf->hdr;
+	const char *start = btf->nohdr_data + hdr->str_off;
+	const char *end = start + btf->hdr->str_len;
+
+	if (!hdr->str_len || hdr->str_len - 1 > BTF_MAX_STR_OFFSET ||
+	    start[0] || end[-1]) {
+		pr_debug("Invalid BTF string section\n");
+		return -EINVAL;
+	}
+
+	btf->strings = start;
+
+	return 0;
+}
+
+static int btf_type_size(struct btf_type *t)
+{
+	int base_size = sizeof(struct btf_type);
+	__u16 vlen = btf_vlen(t);
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_FWD:
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+		return base_size;
+	case BTF_KIND_INT:
+		return base_size + sizeof(__u32);
+	case BTF_KIND_ENUM:
+		return base_size + vlen * sizeof(struct btf_enum);
+	case BTF_KIND_ARRAY:
+		return base_size + sizeof(struct btf_array);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		return base_size + vlen * sizeof(struct btf_member);
+	case BTF_KIND_FUNC_PROTO:
+		return base_size + vlen * sizeof(struct btf_param);
+	case BTF_KIND_VAR:
+		return base_size + sizeof(struct btf_var);
+	case BTF_KIND_DATASEC:
+		return base_size + vlen * sizeof(struct btf_var_secinfo);
+	default:
+		pr_debug("Unsupported BTF_KIND:%u\n", btf_kind(t));
+		return -EINVAL;
+	}
+}
+
+static int btf_parse_type_sec(struct btf *btf)
+{
+	struct btf_header *hdr = btf->hdr;
+	void *nohdr_data = btf->nohdr_data;
+	void *next_type = nohdr_data + hdr->type_off;
+	void *end_type = nohdr_data + hdr->str_off;
+
+	while (next_type < end_type) {
+		struct btf_type *t = next_type;
+		int type_size;
+		int err;
+
+		type_size = btf_type_size(t);
+		if (type_size < 0)
+			return type_size;
+		next_type += type_size;
+		err = btf_add_type(btf, t);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+__u32 btf__get_nr_types(const struct btf *btf)
+{
+	return btf->nr_types;
+}
+
+const struct btf_type *btf__type_by_id(const struct btf *btf, __u32 type_id)
+{
+	if (type_id > btf->nr_types)
+		return NULL;
+
+	return btf->types[type_id];
+}
+
+static bool btf_type_is_void(const struct btf_type *t)
+{
+	return t == &btf_void || btf_is_fwd(t);
+}
+
+static bool btf_type_is_void_or_null(const struct btf_type *t)
+{
+	return !t || btf_type_is_void(t);
+}
+
+#define MAX_RESOLVE_DEPTH 32
+
+__s64 btf__resolve_size(const struct btf *btf, __u32 type_id)
+{
+	const struct btf_array *array;
+	const struct btf_type *t;
+	__u32 nelems = 1;
+	__s64 size = -1;
+	int i;
+
+	t = btf__type_by_id(btf, type_id);
+	for (i = 0; i < MAX_RESOLVE_DEPTH && !btf_type_is_void_or_null(t);
+	     i++) {
+		switch (btf_kind(t)) {
+		case BTF_KIND_INT:
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_DATASEC:
+			size = t->size;
+			goto done;
+		case BTF_KIND_PTR:
+			size = sizeof(void *);
+			goto done;
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_VAR:
+			type_id = t->type;
+			break;
+		case BTF_KIND_ARRAY:
+			array = btf_array(t);
+			if (nelems && array->nelems > UINT32_MAX / nelems)
+				return -E2BIG;
+			nelems *= array->nelems;
+			type_id = array->type;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		t = btf__type_by_id(btf, type_id);
+	}
+
+done:
+	if (size < 0)
+		return -EINVAL;
+	if (nelems && size > UINT32_MAX / nelems)
+		return -E2BIG;
+
+	return nelems * size;
+}
+
+int btf__resolve_type(const struct btf *btf, __u32 type_id)
+{
+	const struct btf_type *t;
+	int depth = 0;
+
+	t = btf__type_by_id(btf, type_id);
+	while (depth < MAX_RESOLVE_DEPTH &&
+	       !btf_type_is_void_or_null(t) &&
+	       (btf_is_mod(t) || btf_is_typedef(t) || btf_is_var(t))) {
+		type_id = t->type;
+		t = btf__type_by_id(btf, type_id);
+		depth++;
+	}
+
+	if (depth == MAX_RESOLVE_DEPTH || btf_type_is_void_or_null(t))
+		return -EINVAL;
+
+	return type_id;
+}
+
+__s32 btf__find_by_name(const struct btf *btf, const char *type_name)
+{
+	__u32 i;
+
+	if (!strcmp(type_name, "void"))
+		return 0;
+
+	for (i = 1; i <= btf->nr_types; i++) {
+		const struct btf_type *t = btf->types[i];
+		const char *name = btf__name_by_offset(btf, t->name_off);
+
+		if (name && !strcmp(type_name, name))
+			return i;
+	}
+
+	return -ENOENT;
+}
+
+__s32 btf__find_by_name_kind(const struct btf *btf, const char *type_name,
+			     __u32 kind)
+{
+	__u32 i;
+
+	if (kind == BTF_KIND_UNKN || !strcmp(type_name, "void"))
+		return 0;
+
+	for (i = 1; i <= btf->nr_types; i++) {
+		const struct btf_type *t = btf->types[i];
+		const char *name;
+
+		if (btf_kind(t) != kind)
+			continue;
+		name = btf__name_by_offset(btf, t->name_off);
+		if (name && !strcmp(type_name, name))
+			return i;
+	}
+
+	return -ENOENT;
+}
+
+void btf__free(struct btf *btf)
+{
+	if (!btf)
+		return;
+
+	if (btf->fd != -1)
+		close(btf->fd);
+
+	free(btf->data);
+	free(btf->types);
+	free(btf);
+}
+
+struct btf *btf__new(__u8 *data, __u32 size)
+{
+	struct btf *btf;
+	int err;
+
+	btf = calloc(1, sizeof(struct btf));
+	if (!btf)
+		return ERR_PTR(-ENOMEM);
+
+	btf->fd = -1;
+
+	btf->data = malloc(size);
+	if (!btf->data) {
+		err = -ENOMEM;
+		goto done;
+	}
+
+	memcpy(btf->data, data, size);
+	btf->data_size = size;
+
+	err = btf_parse_hdr(btf);
+	if (err)
+		goto done;
+
+	err = btf_parse_str_sec(btf);
+	if (err)
+		goto done;
+
+	err = btf_parse_type_sec(btf);
+
+done:
+	if (err) {
+		btf__free(btf);
+		return ERR_PTR(err);
+	}
+
+	return btf;
+}
+
+static bool btf_check_endianness(const GElf_Ehdr *ehdr)
+{
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+	return ehdr->e_ident[EI_DATA] == ELFDATA2LSB;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+	return ehdr->e_ident[EI_DATA] == ELFDATA2MSB;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+}
+
+struct btf *btf__parse_elf(const char *path, struct btf_ext **btf_ext)
+{
+	Elf_Data *btf_data = NULL, *btf_ext_data = NULL;
+	int err = 0, fd = -1, idx = 0;
+	struct btf *btf = NULL;
+	Elf_Scn *scn = NULL;
+	Elf *elf = NULL;
+	GElf_Ehdr ehdr;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn("failed to init libelf for %s\n", path);
+		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+	}
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0) {
+		err = -errno;
+		pr_warn("failed to open %s: %s\n", path, strerror(errno));
+		return ERR_PTR(err);
+	}
+
+	err = -LIBBPF_ERRNO__FORMAT;
+
+	elf = elf_begin(fd, ELF_C_READ, NULL);
+	if (!elf) {
+		pr_warn("failed to open %s as ELF file\n", path);
+		goto done;
+	}
+	if (!gelf_getehdr(elf, &ehdr)) {
+		pr_warn("failed to get EHDR from %s\n", path);
+		goto done;
+	}
+	if (!btf_check_endianness(&ehdr)) {
+		pr_warn("non-native ELF endianness is not supported\n");
+		goto done;
+	}
+	if (!elf_rawdata(elf_getscn(elf, ehdr.e_shstrndx), NULL)) {
+		pr_warn("failed to get e_shstrndx from %s\n", path);
+		goto done;
+	}
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		GElf_Shdr sh;
+		char *name;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, path);
+			goto done;
+		}
+		name = elf_strptr(elf, ehdr.e_shstrndx, sh.sh_name);
+		if (!name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, path);
+			goto done;
+		}
+		if (strcmp(name, BTF_ELF_SEC) == 0) {
+			btf_data = elf_getdata(scn, 0);
+			if (!btf_data) {
+				pr_warn("failed to get section(%d, %s) data from %s\n",
+					idx, name, path);
+				goto done;
+			}
+			continue;
+		} else if (btf_ext && strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			btf_ext_data = elf_getdata(scn, 0);
+			if (!btf_ext_data) {
+				pr_warn("failed to get section(%d, %s) data from %s\n",
+					idx, name, path);
+				goto done;
+			}
+			continue;
+		}
+	}
+
+	err = 0;
+
+	if (!btf_data) {
+		err = -ENOENT;
+		goto done;
+	}
+	btf = btf__new(btf_data->d_buf, btf_data->d_size);
+	if (IS_ERR(btf))
+		goto done;
+
+	if (btf_ext && btf_ext_data) {
+		*btf_ext = btf_ext__new(btf_ext_data->d_buf,
+					btf_ext_data->d_size);
+		if (IS_ERR(*btf_ext))
+			goto done;
+	} else if (btf_ext) {
+		*btf_ext = NULL;
+	}
+done:
+	if (elf)
+		elf_end(elf);
+	close(fd);
+
+	if (err)
+		return ERR_PTR(err);
+	/*
+	 * btf is always parsed before btf_ext, so no need to clean up
+	 * btf_ext, if btf loading failed
+	 */
+	if (IS_ERR(btf))
+		return btf;
+	if (btf_ext && IS_ERR(*btf_ext)) {
+		btf__free(btf);
+		err = PTR_ERR(*btf_ext);
+		return ERR_PTR(err);
+	}
+	return btf;
+}
+
+static int compare_vsi_off(const void *_a, const void *_b)
+{
+	const struct btf_var_secinfo *a = _a;
+	const struct btf_var_secinfo *b = _b;
+
+	return a->offset - b->offset;
+}
+
+static int btf_fixup_datasec(struct bpf_object *obj, struct btf *btf,
+			     struct btf_type *t)
+{
+	__u32 size = 0, off = 0, i, vars = btf_vlen(t);
+	const char *name = btf__name_by_offset(btf, t->name_off);
+	const struct btf_type *t_var;
+	struct btf_var_secinfo *vsi;
+	const struct btf_var *var;
+	int ret;
+
+	if (!name) {
+		pr_debug("No name found in string section for DATASEC kind.\n");
+		return -ENOENT;
+	}
+
+	ret = bpf_object__section_size(obj, name, &size);
+	if (ret || !size || (t->size && t->size != size)) {
+		pr_debug("Invalid size for section %s: %u bytes\n", name, size);
+		return -ENOENT;
+	}
+
+	t->size = size;
+
+	for (i = 0, vsi = btf_var_secinfos(t); i < vars; i++, vsi++) {
+		t_var = btf__type_by_id(btf, vsi->type);
+		var = btf_var(t_var);
+
+		if (!btf_is_var(t_var)) {
+			pr_debug("Non-VAR type seen in section %s\n", name);
+			return -EINVAL;
+		}
+
+		if (var->linkage == BTF_VAR_STATIC)
+			continue;
+
+		name = btf__name_by_offset(btf, t_var->name_off);
+		if (!name) {
+			pr_debug("No name found in string section for VAR kind\n");
+			return -ENOENT;
+		}
+
+		ret = bpf_object__variable_offset(obj, name, &off);
+		if (ret) {
+			pr_debug("No offset found in symbol table for VAR %s\n",
+				 name);
+			return -ENOENT;
+		}
+
+		vsi->offset = off;
+	}
+
+	qsort(t + 1, vars, sizeof(*vsi), compare_vsi_off);
+	return 0;
+}
+
+int btf__finalize_data(struct bpf_object *obj, struct btf *btf)
+{
+	int err = 0;
+	__u32 i;
+
+	for (i = 1; i <= btf->nr_types; i++) {
+		struct btf_type *t = btf->types[i];
+
+		/* Loader needs to fix up some of the things compiler
+		 * couldn't get its hands on while emitting BTF. This
+		 * is section size and global variable offset. We use
+		 * the info from the ELF itself for this purpose.
+		 */
+		if (btf_is_datasec(t)) {
+			err = btf_fixup_datasec(obj, btf, t);
+			if (err)
+				break;
+		}
+	}
+
+	return err;
+}
+
+int btf__load(struct btf *btf)
+{
+	__u32 log_buf_size = BPF_LOG_BUF_SIZE;
+	char *log_buf = NULL;
+	int err = 0;
+
+	if (btf->fd >= 0)
+		return -EEXIST;
+
+	log_buf = malloc(log_buf_size);
+	if (!log_buf)
+		return -ENOMEM;
+
+	*log_buf = 0;
+
+	btf->fd = bpf_load_btf(btf->data, btf->data_size,
+			       log_buf, log_buf_size, false);
+	if (btf->fd < 0) {
+		err = -errno;
+		pr_warn("Error loading BTF: %s(%d)\n", strerror(errno), errno);
+		if (*log_buf)
+			pr_warn("%s\n", log_buf);
+		goto done;
+	}
+
+done:
+	free(log_buf);
+	return err;
+}
+
+int btf__fd(const struct btf *btf)
+{
+	return btf->fd;
+}
+
+const void *btf__get_raw_data(const struct btf *btf, __u32 *size)
+{
+	*size = btf->data_size;
+	return btf->data;
+}
+
+const char *btf__name_by_offset(const struct btf *btf, __u32 offset)
+{
+	if (offset < btf->hdr->str_len)
+		return &btf->strings[offset];
+	else
+		return NULL;
+}
+
+int btf__get_from_id(__u32 id, struct btf **btf)
+{
+	struct bpf_btf_info btf_info = { 0 };
+	__u32 len = sizeof(btf_info);
+	__u32 last_size;
+	int btf_fd;
+	void *ptr;
+	int err;
+
+	err = 0;
+	*btf = NULL;
+	btf_fd = bpf_btf_get_fd_by_id(id);
+	if (btf_fd < 0)
+		return 0;
+
+	/* we won't know btf_size until we call bpf_obj_get_info_by_fd(). so
+	 * let's start with a sane default - 4KiB here - and resize it only if
+	 * bpf_obj_get_info_by_fd() needs a bigger buffer.
+	 */
+	btf_info.btf_size = 4096;
+	last_size = btf_info.btf_size;
+	ptr = malloc(last_size);
+	if (!ptr) {
+		err = -ENOMEM;
+		goto exit_free;
+	}
+
+	memset(ptr, 0, last_size);
+	btf_info.btf = ptr_to_u64(ptr);
+	err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+
+	if (!err && btf_info.btf_size > last_size) {
+		void *temp_ptr;
+
+		last_size = btf_info.btf_size;
+		temp_ptr = realloc(ptr, last_size);
+		if (!temp_ptr) {
+			err = -ENOMEM;
+			goto exit_free;
+		}
+		ptr = temp_ptr;
+		memset(ptr, 0, last_size);
+		btf_info.btf = ptr_to_u64(ptr);
+		err = bpf_obj_get_info_by_fd(btf_fd, &btf_info, &len);
+	}
+
+	if (err || btf_info.btf_size > last_size) {
+		err = errno;
+		goto exit_free;
+	}
+
+	*btf = btf__new((__u8 *)(long)btf_info.btf, btf_info.btf_size);
+	if (IS_ERR(*btf)) {
+		err = PTR_ERR(*btf);
+		*btf = NULL;
+	}
+
+exit_free:
+	close(btf_fd);
+	free(ptr);
+
+	return err;
+}
+
+int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
+			 __u32 expected_key_size, __u32 expected_value_size,
+			 __u32 *key_type_id, __u32 *value_type_id)
+{
+	const struct btf_type *container_type;
+	const struct btf_member *key, *value;
+	const size_t max_name = 256;
+	char container_name[max_name];
+	__s64 key_size, value_size;
+	__s32 container_id;
+
+	if (snprintf(container_name, max_name, "____btf_map_%s", map_name) ==
+	    max_name) {
+		pr_warn("map:%s length of '____btf_map_%s' is too long\n",
+			map_name, map_name);
+		return -EINVAL;
+	}
+
+	container_id = btf__find_by_name(btf, container_name);
+	if (container_id < 0) {
+		pr_debug("map:%s container_name:%s cannot be found in BTF. Missing BPF_ANNOTATE_KV_PAIR?\n",
+			 map_name, container_name);
+		return container_id;
+	}
+
+	container_type = btf__type_by_id(btf, container_id);
+	if (!container_type) {
+		pr_warn("map:%s cannot find BTF type for container_id:%u\n",
+			map_name, container_id);
+		return -EINVAL;
+	}
+
+	if (!btf_is_struct(container_type) || btf_vlen(container_type) < 2) {
+		pr_warn("map:%s container_name:%s is an invalid container struct\n",
+			map_name, container_name);
+		return -EINVAL;
+	}
+
+	key = btf_members(container_type);
+	value = key + 1;
+
+	key_size = btf__resolve_size(btf, key->type);
+	if (key_size < 0) {
+		pr_warn("map:%s invalid BTF key_type_size\n", map_name);
+		return key_size;
+	}
+
+	if (expected_key_size != key_size) {
+		pr_warn("map:%s btf_key_type_size:%u != map_def_key_size:%u\n",
+			map_name, (__u32)key_size, expected_key_size);
+		return -EINVAL;
+	}
+
+	value_size = btf__resolve_size(btf, value->type);
+	if (value_size < 0) {
+		pr_warn("map:%s invalid BTF value_type_size\n", map_name);
+		return value_size;
+	}
+
+	if (expected_value_size != value_size) {
+		pr_warn("map:%s btf_value_type_size:%u != map_def_value_size:%u\n",
+			map_name, (__u32)value_size, expected_value_size);
+		return -EINVAL;
+	}
+
+	*key_type_id = key->type;
+	*value_type_id = value->type;
+
+	return 0;
+}
+
+struct btf_ext_sec_setup_param {
+	__u32 off;
+	__u32 len;
+	__u32 min_rec_size;
+	struct btf_ext_info *ext_info;
+	const char *desc;
+};
+
+static int btf_ext_setup_info(struct btf_ext *btf_ext,
+			      struct btf_ext_sec_setup_param *ext_sec)
+{
+	const struct btf_ext_info_sec *sinfo;
+	struct btf_ext_info *ext_info;
+	__u32 info_left, record_size;
+	/* The start of the info sec (including the __u32 record_size). */
+	void *info;
+
+	if (ext_sec->len == 0)
+		return 0;
+
+	if (ext_sec->off & 0x03) {
+		pr_debug(".BTF.ext %s section is not aligned to 4 bytes\n",
+		     ext_sec->desc);
+		return -EINVAL;
+	}
+
+	info = btf_ext->data + btf_ext->hdr->hdr_len + ext_sec->off;
+	info_left = ext_sec->len;
+
+	if (btf_ext->data + btf_ext->data_size < info + ext_sec->len) {
+		pr_debug("%s section (off:%u len:%u) is beyond the end of the ELF section .BTF.ext\n",
+			 ext_sec->desc, ext_sec->off, ext_sec->len);
+		return -EINVAL;
+	}
+
+	/* At least a record size */
+	if (info_left < sizeof(__u32)) {
+		pr_debug(".BTF.ext %s record size not found\n", ext_sec->desc);
+		return -EINVAL;
+	}
+
+	/* The record size needs to meet the minimum standard */
+	record_size = *(__u32 *)info;
+	if (record_size < ext_sec->min_rec_size ||
+	    record_size & 0x03) {
+		pr_debug("%s section in .BTF.ext has invalid record size %u\n",
+			 ext_sec->desc, record_size);
+		return -EINVAL;
+	}
+
+	sinfo = info + sizeof(__u32);
+	info_left -= sizeof(__u32);
+
+	/* If no records, return failure now so .BTF.ext won't be used. */
+	if (!info_left) {
+		pr_debug("%s section in .BTF.ext has no records", ext_sec->desc);
+		return -EINVAL;
+	}
+
+	while (info_left) {
+		unsigned int sec_hdrlen = sizeof(struct btf_ext_info_sec);
+		__u64 total_record_size;
+		__u32 num_records;
+
+		if (info_left < sec_hdrlen) {
+			pr_debug("%s section header is not found in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		num_records = sinfo->num_info;
+		if (num_records == 0) {
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		total_record_size = sec_hdrlen +
+				    (__u64)num_records * record_size;
+		if (info_left < total_record_size) {
+			pr_debug("%s section has incorrect num_records in .BTF.ext\n",
+			     ext_sec->desc);
+			return -EINVAL;
+		}
+
+		info_left -= total_record_size;
+		sinfo = (void *)sinfo + total_record_size;
+	}
+
+	ext_info = ext_sec->ext_info;
+	ext_info->len = ext_sec->len - sizeof(__u32);
+	ext_info->rec_size = record_size;
+	ext_info->info = info + sizeof(__u32);
+
+	return 0;
+}
+
+static int btf_ext_setup_func_info(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->func_info_off,
+		.len = btf_ext->hdr->func_info_len,
+		.min_rec_size = sizeof(struct bpf_func_info_min),
+		.ext_info = &btf_ext->func_info,
+		.desc = "func_info"
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_line_info(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->line_info_off,
+		.len = btf_ext->hdr->line_info_len,
+		.min_rec_size = sizeof(struct bpf_line_info_min),
+		.ext_info = &btf_ext->line_info,
+		.desc = "line_info",
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_setup_field_reloc(struct btf_ext *btf_ext)
+{
+	struct btf_ext_sec_setup_param param = {
+		.off = btf_ext->hdr->field_reloc_off,
+		.len = btf_ext->hdr->field_reloc_len,
+		.min_rec_size = sizeof(struct bpf_field_reloc),
+		.ext_info = &btf_ext->field_reloc_info,
+		.desc = "field_reloc",
+	};
+
+	return btf_ext_setup_info(btf_ext, &param);
+}
+
+static int btf_ext_parse_hdr(__u8 *data, __u32 data_size)
+{
+	const struct btf_ext_header *hdr = (struct btf_ext_header *)data;
+
+	if (data_size < offsetofend(struct btf_ext_header, hdr_len) ||
+	    data_size < hdr->hdr_len) {
+		pr_debug("BTF.ext header not found");
+		return -EINVAL;
+	}
+
+	if (hdr->magic != BTF_MAGIC) {
+		pr_debug("Invalid BTF.ext magic:%x\n", hdr->magic);
+		return -EINVAL;
+	}
+
+	if (hdr->version != BTF_VERSION) {
+		pr_debug("Unsupported BTF.ext version:%u\n", hdr->version);
+		return -ENOTSUP;
+	}
+
+	if (hdr->flags) {
+		pr_debug("Unsupported BTF.ext flags:%x\n", hdr->flags);
+		return -ENOTSUP;
+	}
+
+	if (data_size == hdr->hdr_len) {
+		pr_debug("BTF.ext has no data\n");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+void btf_ext__free(struct btf_ext *btf_ext)
+{
+	if (!btf_ext)
+		return;
+	free(btf_ext->data);
+	free(btf_ext);
+}
+
+struct btf_ext *btf_ext__new(__u8 *data, __u32 size)
+{
+	struct btf_ext *btf_ext;
+	int err;
+
+	err = btf_ext_parse_hdr(data, size);
+	if (err)
+		return ERR_PTR(err);
+
+	btf_ext = calloc(1, sizeof(struct btf_ext));
+	if (!btf_ext)
+		return ERR_PTR(-ENOMEM);
+
+	btf_ext->data_size = size;
+	btf_ext->data = malloc(size);
+	if (!btf_ext->data) {
+		err = -ENOMEM;
+		goto done;
+	}
+	memcpy(btf_ext->data, data, size);
+
+	if (btf_ext->hdr->hdr_len <
+	    offsetofend(struct btf_ext_header, line_info_len))
+		goto done;
+	err = btf_ext_setup_func_info(btf_ext);
+	if (err)
+		goto done;
+
+	err = btf_ext_setup_line_info(btf_ext);
+	if (err)
+		goto done;
+
+	if (btf_ext->hdr->hdr_len <
+	    offsetofend(struct btf_ext_header, field_reloc_len))
+		goto done;
+	err = btf_ext_setup_field_reloc(btf_ext);
+	if (err)
+		goto done;
+
+done:
+	if (err) {
+		btf_ext__free(btf_ext);
+		return ERR_PTR(err);
+	}
+
+	return btf_ext;
+}
+
+const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext, __u32 *size)
+{
+	*size = btf_ext->data_size;
+	return btf_ext->data;
+}
+
+static int btf_ext_reloc_info(const struct btf *btf,
+			      const struct btf_ext_info *ext_info,
+			      const char *sec_name, __u32 insns_cnt,
+			      void **info, __u32 *cnt)
+{
+	__u32 sec_hdrlen = sizeof(struct btf_ext_info_sec);
+	__u32 i, record_size, existing_len, records_len;
+	struct btf_ext_info_sec *sinfo;
+	const char *info_sec_name;
+	__u64 remain_len;
+	void *data;
+
+	record_size = ext_info->rec_size;
+	sinfo = ext_info->info;
+	remain_len = ext_info->len;
+	while (remain_len > 0) {
+		records_len = sinfo->num_info * record_size;
+		info_sec_name = btf__name_by_offset(btf, sinfo->sec_name_off);
+		if (strcmp(info_sec_name, sec_name)) {
+			remain_len -= sec_hdrlen + records_len;
+			sinfo = (void *)sinfo + sec_hdrlen + records_len;
+			continue;
+		}
+
+		existing_len = (*cnt) * record_size;
+		data = realloc(*info, existing_len + records_len);
+		if (!data)
+			return -ENOMEM;
+
+		memcpy(data + existing_len, sinfo->data, records_len);
+		/* adjust insn_off only, the rest data will be passed
+		 * to the kernel.
+		 */
+		for (i = 0; i < sinfo->num_info; i++) {
+			__u32 *insn_off;
+
+			insn_off = data + existing_len + (i * record_size);
+			*insn_off = *insn_off / sizeof(struct bpf_insn) +
+				insns_cnt;
+		}
+		*info = data;
+		*cnt += sinfo->num_info;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+int btf_ext__reloc_func_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **func_info, __u32 *cnt)
+{
+	return btf_ext_reloc_info(btf, &btf_ext->func_info, sec_name,
+				  insns_cnt, func_info, cnt);
+}
+
+int btf_ext__reloc_line_info(const struct btf *btf,
+			     const struct btf_ext *btf_ext,
+			     const char *sec_name, __u32 insns_cnt,
+			     void **line_info, __u32 *cnt)
+{
+	return btf_ext_reloc_info(btf, &btf_ext->line_info, sec_name,
+				  insns_cnt, line_info, cnt);
+}
+
+__u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext)
+{
+	return btf_ext->func_info.rec_size;
+}
+
+__u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext)
+{
+	return btf_ext->line_info.rec_size;
+}
+
+struct btf_dedup;
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
+				       const struct btf_dedup_opts *opts);
+static void btf_dedup_free(struct btf_dedup *d);
+static int btf_dedup_strings(struct btf_dedup *d);
+static int btf_dedup_prim_types(struct btf_dedup *d);
+static int btf_dedup_struct_types(struct btf_dedup *d);
+static int btf_dedup_ref_types(struct btf_dedup *d);
+static int btf_dedup_compact_types(struct btf_dedup *d);
+static int btf_dedup_remap_types(struct btf_dedup *d);
+
+/*
+ * Deduplicate BTF types and strings.
+ *
+ * BTF dedup algorithm takes as an input `struct btf` representing `.BTF` ELF
+ * section with all BTF type descriptors and string data. It overwrites that
+ * memory in-place with deduplicated types and strings without any loss of
+ * information. If optional `struct btf_ext` representing '.BTF.ext' ELF section
+ * is provided, all the strings referenced from .BTF.ext section are honored
+ * and updated to point to the right offsets after deduplication.
+ *
+ * If function returns with error, type/string data might be garbled and should
+ * be discarded.
+ *
+ * More verbose and detailed description of both problem btf_dedup is solving,
+ * as well as solution could be found at:
+ * https://facebookmicrosites.github.io/bpf/blog/2018/11/14/btf-enhancement.html
+ *
+ * Problem description and justification
+ * =====================================
+ *
+ * BTF type information is typically emitted either as a result of conversion
+ * from DWARF to BTF or directly by compiler. In both cases, each compilation
+ * unit contains information about a subset of all the types that are used
+ * in an application. These subsets are frequently overlapping and contain a lot
+ * of duplicated information when later concatenated together into a single
+ * binary. This algorithm ensures that each unique type is represented by single
+ * BTF type descriptor, greatly reducing resulting size of BTF data.
+ *
+ * Compilation unit isolation and subsequent duplication of data is not the only
+ * problem. The same type hierarchy (e.g., struct and all the type that struct
+ * references) in different compilation units can be represented in BTF to
+ * various degrees of completeness (or, rather, incompleteness) due to
+ * struct/union forward declarations.
+ *
+ * Let's take a look at an example, that we'll use to better understand the
+ * problem (and solution). Suppose we have two compilation units, each using
+ * same `struct S`, but each of them having incomplete type information about
+ * struct's fields:
+ *
+ * // CU #1:
+ * struct S;
+ * struct A {
+ *	int a;
+ *	struct A* self;
+ *	struct S* parent;
+ * };
+ * struct B;
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * // CU #2:
+ * struct S;
+ * struct A;
+ * struct B {
+ *	int b;
+ *	struct B* self;
+ *	struct S* parent;
+ * };
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * In case of CU #1, BTF data will know only that `struct B` exist (but no
+ * more), but will know the complete type information about `struct A`. While
+ * for CU #2, it will know full type information about `struct B`, but will
+ * only know about forward declaration of `struct A` (in BTF terms, it will
+ * have `BTF_KIND_FWD` type descriptor with name `B`).
+ *
+ * This compilation unit isolation means that it's possible that there is no
+ * single CU with complete type information describing structs `S`, `A`, and
+ * `B`. Also, we might get tons of duplicated and redundant type information.
+ *
+ * Additional complication we need to keep in mind comes from the fact that
+ * types, in general, can form graphs containing cycles, not just DAGs.
+ *
+ * While algorithm does deduplication, it also merges and resolves type
+ * information (unless disabled throught `struct btf_opts`), whenever possible.
+ * E.g., in the example above with two compilation units having partial type
+ * information for structs `A` and `B`, the output of algorithm will emit
+ * a single copy of each BTF type that describes structs `A`, `B`, and `S`
+ * (as well as type information for `int` and pointers), as if they were defined
+ * in a single compilation unit as:
+ *
+ * struct A {
+ *	int a;
+ *	struct A* self;
+ *	struct S* parent;
+ * };
+ * struct B {
+ *	int b;
+ *	struct B* self;
+ *	struct S* parent;
+ * };
+ * struct S {
+ *	struct A* a_ptr;
+ *	struct B* b_ptr;
+ * };
+ *
+ * Algorithm summary
+ * =================
+ *
+ * Algorithm completes its work in 6 separate passes:
+ *
+ * 1. Strings deduplication.
+ * 2. Primitive types deduplication (int, enum, fwd).
+ * 3. Struct/union types deduplication.
+ * 4. Reference types deduplication (pointers, typedefs, arrays, funcs, func
+ *    protos, and const/volatile/restrict modifiers).
+ * 5. Types compaction.
+ * 6. Types remapping.
+ *
+ * Algorithm determines canonical type descriptor, which is a single
+ * representative type for each truly unique type. This canonical type is the
+ * one that will go into final deduplicated BTF type information. For
+ * struct/unions, it is also the type that algorithm will merge additional type
+ * information into (while resolving FWDs), as it discovers it from data in
+ * other CUs. Each input BTF type eventually gets either mapped to itself, if
+ * that type is canonical, or to some other type, if that type is equivalent
+ * and was chosen as canonical representative. This mapping is stored in
+ * `btf_dedup->map` array. This map is also used to record STRUCT/UNION that
+ * FWD type got resolved to.
+ *
+ * To facilitate fast discovery of canonical types, we also maintain canonical
+ * index (`btf_dedup->dedup_table`), which maps type descriptor's signature hash
+ * (i.e., hashed kind, name, size, fields, etc) into a list of canonical types
+ * that match that signature. With sufficiently good choice of type signature
+ * hashing function, we can limit number of canonical types for each unique type
+ * signature to a very small number, allowing to find canonical type for any
+ * duplicated type very quickly.
+ *
+ * Struct/union deduplication is the most critical part and algorithm for
+ * deduplicating structs/unions is described in greater details in comments for
+ * `btf_dedup_is_equiv` function.
+ */
+int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
+	       const struct btf_dedup_opts *opts)
+{
+	struct btf_dedup *d = btf_dedup_new(btf, btf_ext, opts);
+	int err;
+
+	if (IS_ERR(d)) {
+		pr_debug("btf_dedup_new failed: %ld", PTR_ERR(d));
+		return -EINVAL;
+	}
+
+	err = btf_dedup_strings(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_strings failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_prim_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_prim_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_struct_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_struct_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_ref_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_ref_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_compact_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_compact_types failed:%d\n", err);
+		goto done;
+	}
+	err = btf_dedup_remap_types(d);
+	if (err < 0) {
+		pr_debug("btf_dedup_remap_types failed:%d\n", err);
+		goto done;
+	}
+
+done:
+	btf_dedup_free(d);
+	return err;
+}
+
+#define BTF_UNPROCESSED_ID ((__u32)-1)
+#define BTF_IN_PROGRESS_ID ((__u32)-2)
+
+struct btf_dedup {
+	/* .BTF section to be deduped in-place */
+	struct btf *btf;
+	/*
+	 * Optional .BTF.ext section. When provided, any strings referenced
+	 * from it will be taken into account when deduping strings
+	 */
+	struct btf_ext *btf_ext;
+	/*
+	 * This is a map from any type's signature hash to a list of possible
+	 * canonical representative type candidates. Hash collisions are
+	 * ignored, so even types of various kinds can share same list of
+	 * candidates, which is fine because we rely on subsequent
+	 * btf_xxx_equal() checks to authoritatively verify type equality.
+	 */
+	struct hashmap *dedup_table;
+	/* Canonical types map */
+	__u32 *map;
+	/* Hypothetical mapping, used during type graph equivalence checks */
+	__u32 *hypot_map;
+	__u32 *hypot_list;
+	size_t hypot_cnt;
+	size_t hypot_cap;
+	/* Various option modifying behavior of algorithm */
+	struct btf_dedup_opts opts;
+};
+
+struct btf_str_ptr {
+	const char *str;
+	__u32 new_off;
+	bool used;
+};
+
+struct btf_str_ptrs {
+	struct btf_str_ptr *ptrs;
+	const char *data;
+	__u32 cnt;
+	__u32 cap;
+};
+
+static long hash_combine(long h, long value)
+{
+	return h * 31 + value;
+}
+
+#define for_each_dedup_cand(d, node, hash) \
+	hashmap__for_each_key_entry(d->dedup_table, node, (void *)hash)
+
+static int btf_dedup_table_add(struct btf_dedup *d, long hash, __u32 type_id)
+{
+	return hashmap__append(d->dedup_table,
+			       (void *)hash, (void *)(long)type_id);
+}
+
+static int btf_dedup_hypot_map_add(struct btf_dedup *d,
+				   __u32 from_id, __u32 to_id)
+{
+	if (d->hypot_cnt == d->hypot_cap) {
+		__u32 *new_list;
+
+		d->hypot_cap += max(16, d->hypot_cap / 2);
+		new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
+		if (!new_list)
+			return -ENOMEM;
+		d->hypot_list = new_list;
+	}
+	d->hypot_list[d->hypot_cnt++] = from_id;
+	d->hypot_map[from_id] = to_id;
+	return 0;
+}
+
+static void btf_dedup_clear_hypot_map(struct btf_dedup *d)
+{
+	int i;
+
+	for (i = 0; i < d->hypot_cnt; i++)
+		d->hypot_map[d->hypot_list[i]] = BTF_UNPROCESSED_ID;
+	d->hypot_cnt = 0;
+}
+
+static void btf_dedup_free(struct btf_dedup *d)
+{
+	hashmap__free(d->dedup_table);
+	d->dedup_table = NULL;
+
+	free(d->map);
+	d->map = NULL;
+
+	free(d->hypot_map);
+	d->hypot_map = NULL;
+
+	free(d->hypot_list);
+	d->hypot_list = NULL;
+
+	free(d);
+}
+
+static size_t btf_dedup_identity_hash_fn(const void *key, void *ctx)
+{
+	return (size_t)key;
+}
+
+static size_t btf_dedup_collision_hash_fn(const void *key, void *ctx)
+{
+	return 0;
+}
+
+static bool btf_dedup_equal_fn(const void *k1, const void *k2, void *ctx)
+{
+	return k1 == k2;
+}
+
+static struct btf_dedup *btf_dedup_new(struct btf *btf, struct btf_ext *btf_ext,
+				       const struct btf_dedup_opts *opts)
+{
+	struct btf_dedup *d = calloc(1, sizeof(struct btf_dedup));
+	hashmap_hash_fn hash_fn = btf_dedup_identity_hash_fn;
+	int i, err = 0;
+
+	if (!d)
+		return ERR_PTR(-ENOMEM);
+
+	d->opts.dont_resolve_fwds = opts && opts->dont_resolve_fwds;
+	/* dedup_table_size is now used only to force collisions in tests */
+	if (opts && opts->dedup_table_size == 1)
+		hash_fn = btf_dedup_collision_hash_fn;
+
+	d->btf = btf;
+	d->btf_ext = btf_ext;
+
+	d->dedup_table = hashmap__new(hash_fn, btf_dedup_equal_fn, NULL);
+	if (IS_ERR(d->dedup_table)) {
+		err = PTR_ERR(d->dedup_table);
+		d->dedup_table = NULL;
+		goto done;
+	}
+
+	d->map = malloc(sizeof(__u32) * (1 + btf->nr_types));
+	if (!d->map) {
+		err = -ENOMEM;
+		goto done;
+	}
+	/* special BTF "void" type is made canonical immediately */
+	d->map[0] = 0;
+	for (i = 1; i <= btf->nr_types; i++) {
+		struct btf_type *t = d->btf->types[i];
+
+		/* VAR and DATASEC are never deduped and are self-canonical */
+		if (btf_is_var(t) || btf_is_datasec(t))
+			d->map[i] = i;
+		else
+			d->map[i] = BTF_UNPROCESSED_ID;
+	}
+
+	d->hypot_map = malloc(sizeof(__u32) * (1 + btf->nr_types));
+	if (!d->hypot_map) {
+		err = -ENOMEM;
+		goto done;
+	}
+	for (i = 0; i <= btf->nr_types; i++)
+		d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+done:
+	if (err) {
+		btf_dedup_free(d);
+		return ERR_PTR(err);
+	}
+
+	return d;
+}
+
+typedef int (*str_off_fn_t)(__u32 *str_off_ptr, void *ctx);
+
+/*
+ * Iterate over all possible places in .BTF and .BTF.ext that can reference
+ * string and pass pointer to it to a provided callback `fn`.
+ */
+static int btf_for_each_str_off(struct btf_dedup *d, str_off_fn_t fn, void *ctx)
+{
+	void *line_data_cur, *line_data_end;
+	int i, j, r, rec_size;
+	struct btf_type *t;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		t = d->btf->types[i];
+		r = fn(&t->name_off, ctx);
+		if (r)
+			return r;
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION: {
+			struct btf_member *m = btf_members(t);
+			__u16 vlen = btf_vlen(t);
+
+			for (j = 0; j < vlen; j++) {
+				r = fn(&m->name_off, ctx);
+				if (r)
+					return r;
+				m++;
+			}
+			break;
+		}
+		case BTF_KIND_ENUM: {
+			struct btf_enum *m = btf_enum(t);
+			__u16 vlen = btf_vlen(t);
+
+			for (j = 0; j < vlen; j++) {
+				r = fn(&m->name_off, ctx);
+				if (r)
+					return r;
+				m++;
+			}
+			break;
+		}
+		case BTF_KIND_FUNC_PROTO: {
+			struct btf_param *m = btf_params(t);
+			__u16 vlen = btf_vlen(t);
+
+			for (j = 0; j < vlen; j++) {
+				r = fn(&m->name_off, ctx);
+				if (r)
+					return r;
+				m++;
+			}
+			break;
+		}
+		default:
+			break;
+		}
+	}
+
+	if (!d->btf_ext)
+		return 0;
+
+	line_data_cur = d->btf_ext->line_info.info;
+	line_data_end = d->btf_ext->line_info.info + d->btf_ext->line_info.len;
+	rec_size = d->btf_ext->line_info.rec_size;
+
+	while (line_data_cur < line_data_end) {
+		struct btf_ext_info_sec *sec = line_data_cur;
+		struct bpf_line_info_min *line_info;
+		__u32 num_info = sec->num_info;
+
+		r = fn(&sec->sec_name_off, ctx);
+		if (r)
+			return r;
+
+		line_data_cur += sizeof(struct btf_ext_info_sec);
+		for (i = 0; i < num_info; i++) {
+			line_info = line_data_cur;
+			r = fn(&line_info->file_name_off, ctx);
+			if (r)
+				return r;
+			r = fn(&line_info->line_off, ctx);
+			if (r)
+				return r;
+			line_data_cur += rec_size;
+		}
+	}
+
+	return 0;
+}
+
+static int str_sort_by_content(const void *a1, const void *a2)
+{
+	const struct btf_str_ptr *p1 = a1;
+	const struct btf_str_ptr *p2 = a2;
+
+	return strcmp(p1->str, p2->str);
+}
+
+static int str_sort_by_offset(const void *a1, const void *a2)
+{
+	const struct btf_str_ptr *p1 = a1;
+	const struct btf_str_ptr *p2 = a2;
+
+	if (p1->str != p2->str)
+		return p1->str < p2->str ? -1 : 1;
+	return 0;
+}
+
+static int btf_dedup_str_ptr_cmp(const void *str_ptr, const void *pelem)
+{
+	const struct btf_str_ptr *p = pelem;
+
+	if (str_ptr != p->str)
+		return (const char *)str_ptr < p->str ? -1 : 1;
+	return 0;
+}
+
+static int btf_str_mark_as_used(__u32 *str_off_ptr, void *ctx)
+{
+	struct btf_str_ptrs *strs;
+	struct btf_str_ptr *s;
+
+	if (*str_off_ptr == 0)
+		return 0;
+
+	strs = ctx;
+	s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
+		    sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
+	if (!s)
+		return -EINVAL;
+	s->used = true;
+	return 0;
+}
+
+static int btf_str_remap_offset(__u32 *str_off_ptr, void *ctx)
+{
+	struct btf_str_ptrs *strs;
+	struct btf_str_ptr *s;
+
+	if (*str_off_ptr == 0)
+		return 0;
+
+	strs = ctx;
+	s = bsearch(strs->data + *str_off_ptr, strs->ptrs, strs->cnt,
+		    sizeof(struct btf_str_ptr), btf_dedup_str_ptr_cmp);
+	if (!s)
+		return -EINVAL;
+	*str_off_ptr = s->new_off;
+	return 0;
+}
+
+/*
+ * Dedup string and filter out those that are not referenced from either .BTF
+ * or .BTF.ext (if provided) sections.
+ *
+ * This is done by building index of all strings in BTF's string section,
+ * then iterating over all entities that can reference strings (e.g., type
+ * names, struct field names, .BTF.ext line info, etc) and marking corresponding
+ * strings as used. After that all used strings are deduped and compacted into
+ * sequential blob of memory and new offsets are calculated. Then all the string
+ * references are iterated again and rewritten using new offsets.
+ */
+static int btf_dedup_strings(struct btf_dedup *d)
+{
+	const struct btf_header *hdr = d->btf->hdr;
+	char *start = (char *)d->btf->nohdr_data + hdr->str_off;
+	char *end = start + d->btf->hdr->str_len;
+	char *p = start, *tmp_strs = NULL;
+	struct btf_str_ptrs strs = {
+		.cnt = 0,
+		.cap = 0,
+		.ptrs = NULL,
+		.data = start,
+	};
+	int i, j, err = 0, grp_idx;
+	bool grp_used;
+
+	/* build index of all strings */
+	while (p < end) {
+		if (strs.cnt + 1 > strs.cap) {
+			struct btf_str_ptr *new_ptrs;
+
+			strs.cap += max(strs.cnt / 2, 16);
+			new_ptrs = realloc(strs.ptrs,
+					   sizeof(strs.ptrs[0]) * strs.cap);
+			if (!new_ptrs) {
+				err = -ENOMEM;
+				goto done;
+			}
+			strs.ptrs = new_ptrs;
+		}
+
+		strs.ptrs[strs.cnt].str = p;
+		strs.ptrs[strs.cnt].used = false;
+
+		p += strlen(p) + 1;
+		strs.cnt++;
+	}
+
+	/* temporary storage for deduplicated strings */
+	tmp_strs = malloc(d->btf->hdr->str_len);
+	if (!tmp_strs) {
+		err = -ENOMEM;
+		goto done;
+	}
+
+	/* mark all used strings */
+	strs.ptrs[0].used = true;
+	err = btf_for_each_str_off(d, btf_str_mark_as_used, &strs);
+	if (err)
+		goto done;
+
+	/* sort strings by context, so that we can identify duplicates */
+	qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_content);
+
+	/*
+	 * iterate groups of equal strings and if any instance in a group was
+	 * referenced, emit single instance and remember new offset
+	 */
+	p = tmp_strs;
+	grp_idx = 0;
+	grp_used = strs.ptrs[0].used;
+	/* iterate past end to avoid code duplication after loop */
+	for (i = 1; i <= strs.cnt; i++) {
+		/*
+		 * when i == strs.cnt, we want to skip string comparison and go
+		 * straight to handling last group of strings (otherwise we'd
+		 * need to handle last group after the loop w/ duplicated code)
+		 */
+		if (i < strs.cnt &&
+		    !strcmp(strs.ptrs[i].str, strs.ptrs[grp_idx].str)) {
+			grp_used = grp_used || strs.ptrs[i].used;
+			continue;
+		}
+
+		/*
+		 * this check would have been required after the loop to handle
+		 * last group of strings, but due to <= condition in a loop
+		 * we avoid that duplication
+		 */
+		if (grp_used) {
+			int new_off = p - tmp_strs;
+			__u32 len = strlen(strs.ptrs[grp_idx].str);
+
+			memmove(p, strs.ptrs[grp_idx].str, len + 1);
+			for (j = grp_idx; j < i; j++)
+				strs.ptrs[j].new_off = new_off;
+			p += len + 1;
+		}
+
+		if (i < strs.cnt) {
+			grp_idx = i;
+			grp_used = strs.ptrs[i].used;
+		}
+	}
+
+	/* replace original strings with deduped ones */
+	d->btf->hdr->str_len = p - tmp_strs;
+	memmove(start, tmp_strs, d->btf->hdr->str_len);
+	end = start + d->btf->hdr->str_len;
+
+	/* restore original order for further binary search lookups */
+	qsort(strs.ptrs, strs.cnt, sizeof(strs.ptrs[0]), str_sort_by_offset);
+
+	/* remap string offsets */
+	err = btf_for_each_str_off(d, btf_str_remap_offset, &strs);
+	if (err)
+		goto done;
+
+	d->btf->hdr->str_len = end - start;
+
+done:
+	free(tmp_strs);
+	free(strs.ptrs);
+	return err;
+}
+
+static long btf_hash_common(struct btf_type *t)
+{
+	long h;
+
+	h = hash_combine(0, t->name_off);
+	h = hash_combine(h, t->info);
+	h = hash_combine(h, t->size);
+	return h;
+}
+
+static bool btf_equal_common(struct btf_type *t1, struct btf_type *t2)
+{
+	return t1->name_off == t2->name_off &&
+	       t1->info == t2->info &&
+	       t1->size == t2->size;
+}
+
+/* Calculate type signature hash of INT. */
+static long btf_hash_int(struct btf_type *t)
+{
+	__u32 info = *(__u32 *)(t + 1);
+	long h;
+
+	h = btf_hash_common(t);
+	h = hash_combine(h, info);
+	return h;
+}
+
+/* Check structural equality of two INTs. */
+static bool btf_equal_int(struct btf_type *t1, struct btf_type *t2)
+{
+	__u32 info1, info2;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+	info1 = *(__u32 *)(t1 + 1);
+	info2 = *(__u32 *)(t2 + 1);
+	return info1 == info2;
+}
+
+/* Calculate type signature hash of ENUM. */
+static long btf_hash_enum(struct btf_type *t)
+{
+	long h;
+
+	/* don't hash vlen and enum members to support enum fwd resolving */
+	h = hash_combine(0, t->name_off);
+	h = hash_combine(h, t->info & ~0xffff);
+	h = hash_combine(h, t->size);
+	return h;
+}
+
+/* Check structural equality of two ENUMs. */
+static bool btf_equal_enum(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_enum *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_enum(t1);
+	m2 = btf_enum(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->val != m2->val)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+static inline bool btf_is_enum_fwd(struct btf_type *t)
+{
+	return btf_is_enum(t) && btf_vlen(t) == 0;
+}
+
+static bool btf_compat_enum(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_is_enum_fwd(t1) && !btf_is_enum_fwd(t2))
+		return btf_equal_enum(t1, t2);
+	/* ignore vlen when comparing */
+	return t1->name_off == t2->name_off &&
+	       (t1->info & ~0xffff) == (t2->info & ~0xffff) &&
+	       t1->size == t2->size;
+}
+
+/*
+ * Calculate type signature hash of STRUCT/UNION, ignoring referenced type IDs,
+ * as referenced type IDs equivalence is established separately during type
+ * graph equivalence check algorithm.
+ */
+static long btf_hash_struct(struct btf_type *t)
+{
+	const struct btf_member *member = btf_members(t);
+	__u32 vlen = btf_vlen(t);
+	long h = btf_hash_common(t);
+	int i;
+
+	for (i = 0; i < vlen; i++) {
+		h = hash_combine(h, member->name_off);
+		h = hash_combine(h, member->offset);
+		/* no hashing of referenced type ID, it can be unresolved yet */
+		member++;
+	}
+	return h;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_shallow_equal_struct(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_member *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_members(t1);
+	m2 = btf_members(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->offset != m2->offset)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/*
+ * Calculate type signature hash of ARRAY, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_array(struct btf_type *t)
+{
+	const struct btf_array *info = btf_array(t);
+	long h = btf_hash_common(t);
+
+	h = hash_combine(h, info->type);
+	h = hash_combine(h, info->index_type);
+	h = hash_combine(h, info->nelems);
+	return h;
+}
+
+/*
+ * Check exact equality of two ARRAYs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * ARRAY to potential canonical representative.
+ */
+static bool btf_equal_array(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_array *info1, *info2;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	info1 = btf_array(t1);
+	info2 = btf_array(t2);
+	return info1->type == info2->type &&
+	       info1->index_type == info2->index_type &&
+	       info1->nelems == info2->nelems;
+}
+
+/*
+ * Check structural compatibility of two ARRAYs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_array(struct btf_type *t1, struct btf_type *t2)
+{
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	return btf_array(t1)->nelems == btf_array(t2)->nelems;
+}
+
+/*
+ * Calculate type signature hash of FUNC_PROTO, including referenced type IDs,
+ * under assumption that they were already resolved to canonical type IDs and
+ * are not going to change.
+ */
+static long btf_hash_fnproto(struct btf_type *t)
+{
+	const struct btf_param *member = btf_params(t);
+	__u16 vlen = btf_vlen(t);
+	long h = btf_hash_common(t);
+	int i;
+
+	for (i = 0; i < vlen; i++) {
+		h = hash_combine(h, member->name_off);
+		h = hash_combine(h, member->type);
+		member++;
+	}
+	return h;
+}
+
+/*
+ * Check exact equality of two FUNC_PROTOs, taking into account referenced
+ * type IDs, under assumption that they were already resolved to canonical
+ * type IDs and are not going to change.
+ * This function is called during reference types deduplication to compare
+ * FUNC_PROTO to potential canonical representative.
+ */
+static bool btf_equal_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_param *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	if (!btf_equal_common(t1, t2))
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_params(t1);
+	m2 = btf_params(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off || m1->type != m2->type)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/*
+ * Check structural compatibility of two FUNC_PROTOs, ignoring referenced type
+ * IDs. This check is performed during type graph equivalence check and
+ * referenced types equivalence is checked separately.
+ */
+static bool btf_compat_fnproto(struct btf_type *t1, struct btf_type *t2)
+{
+	const struct btf_param *m1, *m2;
+	__u16 vlen;
+	int i;
+
+	/* skip return type ID */
+	if (t1->name_off != t2->name_off || t1->info != t2->info)
+		return false;
+
+	vlen = btf_vlen(t1);
+	m1 = btf_params(t1);
+	m2 = btf_params(t2);
+	for (i = 0; i < vlen; i++) {
+		if (m1->name_off != m2->name_off)
+			return false;
+		m1++;
+		m2++;
+	}
+	return true;
+}
+
+/*
+ * Deduplicate primitive types, that can't reference other types, by calculating
+ * their type signature hash and comparing them with any possible canonical
+ * candidate. If no canonical candidate matches, type itself is marked as
+ * canonical and is added into `btf_dedup->dedup_table` as another candidate.
+ */
+static int btf_dedup_prim_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct btf_type *t = d->btf->types[type_id];
+	struct hashmap_entry *hash_entry;
+	struct btf_type *cand;
+	/* if we don't find equivalent type, then we are canonical */
+	__u32 new_id = type_id;
+	__u32 cand_id;
+	long h;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_ARRAY:
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_FUNC_PROTO:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DATASEC:
+		return 0;
+
+	case BTF_KIND_INT:
+		h = btf_hash_int(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_int(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	case BTF_KIND_ENUM:
+		h = btf_hash_enum(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_enum(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+			if (d->opts.dont_resolve_fwds)
+				continue;
+			if (btf_compat_enum(t, cand)) {
+				if (btf_is_enum_fwd(t)) {
+					/* resolve fwd to full enum */
+					new_id = cand_id;
+					break;
+				}
+				/* resolve canonical enum fwd to full enum */
+				d->map[cand_id] = type_id;
+			}
+		}
+		break;
+
+	case BTF_KIND_FWD:
+		h = btf_hash_common(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_common(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int btf_dedup_prim_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		err = btf_dedup_prim_type(d, i);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+/*
+ * Check whether type is already mapped into canonical one (could be to itself).
+ */
+static inline bool is_type_mapped(struct btf_dedup *d, uint32_t type_id)
+{
+	return d->map[type_id] <= BTF_MAX_NR_TYPES;
+}
+
+/*
+ * Resolve type ID into its canonical type ID, if any; otherwise return original
+ * type ID. If type is FWD and is resolved into STRUCT/UNION already, follow
+ * STRUCT/UNION link and resolve it into canonical type ID as well.
+ */
+static inline __u32 resolve_type_id(struct btf_dedup *d, __u32 type_id)
+{
+	while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+		type_id = d->map[type_id];
+	return type_id;
+}
+
+/*
+ * Resolve FWD to underlying STRUCT/UNION, if any; otherwise return original
+ * type ID.
+ */
+static uint32_t resolve_fwd_id(struct btf_dedup *d, uint32_t type_id)
+{
+	__u32 orig_type_id = type_id;
+
+	if (!btf_is_fwd(d->btf->types[type_id]))
+		return type_id;
+
+	while (is_type_mapped(d, type_id) && d->map[type_id] != type_id)
+		type_id = d->map[type_id];
+
+	if (!btf_is_fwd(d->btf->types[type_id]))
+		return type_id;
+
+	return orig_type_id;
+}
+
+
+static inline __u16 btf_fwd_kind(struct btf_type *t)
+{
+	return btf_kflag(t) ? BTF_KIND_UNION : BTF_KIND_STRUCT;
+}
+
+/*
+ * Check equivalence of BTF type graph formed by candidate struct/union (we'll
+ * call it "candidate graph" in this description for brevity) to a type graph
+ * formed by (potential) canonical struct/union ("canonical graph" for brevity
+ * here, though keep in mind that not all types in canonical graph are
+ * necessarily canonical representatives themselves, some of them might be
+ * duplicates or its uniqueness might not have been established yet).
+ * Returns:
+ *  - >0, if type graphs are equivalent;
+ *  -  0, if not equivalent;
+ *  - <0, on error.
+ *
+ * Algorithm performs side-by-side DFS traversal of both type graphs and checks
+ * equivalence of BTF types at each step. If at any point BTF types in candidate
+ * and canonical graphs are not compatible structurally, whole graphs are
+ * incompatible. If types are structurally equivalent (i.e., all information
+ * except referenced type IDs is exactly the same), a mapping from `canon_id` to
+ * a `cand_id` is recored in hypothetical mapping (`btf_dedup->hypot_map`).
+ * If a type references other types, then those referenced types are checked
+ * for equivalence recursively.
+ *
+ * During DFS traversal, if we find that for current `canon_id` type we
+ * already have some mapping in hypothetical map, we check for two possible
+ * situations:
+ *   - `canon_id` is mapped to exactly the same type as `cand_id`. This will
+ *     happen when type graphs have cycles. In this case we assume those two
+ *     types are equivalent.
+ *   - `canon_id` is mapped to different type. This is contradiction in our
+ *     hypothetical mapping, because same graph in canonical graph corresponds
+ *     to two different types in candidate graph, which for equivalent type
+ *     graphs shouldn't happen. This condition terminates equivalence check
+ *     with negative result.
+ *
+ * If type graphs traversal exhausts types to check and find no contradiction,
+ * then type graphs are equivalent.
+ *
+ * When checking types for equivalence, there is one special case: FWD types.
+ * If FWD type resolution is allowed and one of the types (either from canonical
+ * or candidate graph) is FWD and other is STRUCT/UNION (depending on FWD's kind
+ * flag) and their names match, hypothetical mapping is updated to point from
+ * FWD to STRUCT/UNION. If graphs will be determined as equivalent successfully,
+ * this mapping will be used to record FWD -> STRUCT/UNION mapping permanently.
+ *
+ * Technically, this could lead to incorrect FWD to STRUCT/UNION resolution,
+ * if there are two exactly named (or anonymous) structs/unions that are
+ * compatible structurally, one of which has FWD field, while other is concrete
+ * STRUCT/UNION, but according to C sources they are different structs/unions
+ * that are referencing different types with the same name. This is extremely
+ * unlikely to happen, but btf_dedup API allows to disable FWD resolution if
+ * this logic is causing problems.
+ *
+ * Doing FWD resolution means that both candidate and/or canonical graphs can
+ * consists of portions of the graph that come from multiple compilation units.
+ * This is due to the fact that types within single compilation unit are always
+ * deduplicated and FWDs are already resolved, if referenced struct/union
+ * definiton is available. So, if we had unresolved FWD and found corresponding
+ * STRUCT/UNION, they will be from different compilation units. This
+ * consequently means that when we "link" FWD to corresponding STRUCT/UNION,
+ * type graph will likely have at least two different BTF types that describe
+ * same type (e.g., most probably there will be two different BTF types for the
+ * same 'int' primitive type) and could even have "overlapping" parts of type
+ * graph that describe same subset of types.
+ *
+ * This in turn means that our assumption that each type in canonical graph
+ * must correspond to exactly one type in candidate graph might not hold
+ * anymore and will make it harder to detect contradictions using hypothetical
+ * map. To handle this problem, we allow to follow FWD -> STRUCT/UNION
+ * resolution only in canonical graph. FWDs in candidate graphs are never
+ * resolved. To see why it's OK, let's check all possible situations w.r.t. FWDs
+ * that can occur:
+ *   - Both types in canonical and candidate graphs are FWDs. If they are
+ *     structurally equivalent, then they can either be both resolved to the
+ *     same STRUCT/UNION or not resolved at all. In both cases they are
+ *     equivalent and there is no need to resolve FWD on candidate side.
+ *   - Both types in canonical and candidate graphs are concrete STRUCT/UNION,
+ *     so nothing to resolve as well, algorithm will check equivalence anyway.
+ *   - Type in canonical graph is FWD, while type in candidate is concrete
+ *     STRUCT/UNION. In this case candidate graph comes from single compilation
+ *     unit, so there is exactly one BTF type for each unique C type. After
+ *     resolving FWD into STRUCT/UNION, there might be more than one BTF type
+ *     in canonical graph mapping to single BTF type in candidate graph, but
+ *     because hypothetical mapping maps from canonical to candidate types, it's
+ *     alright, and we still maintain the property of having single `canon_id`
+ *     mapping to single `cand_id` (there could be two different `canon_id`
+ *     mapped to the same `cand_id`, but it's not contradictory).
+ *   - Type in canonical graph is concrete STRUCT/UNION, while type in candidate
+ *     graph is FWD. In this case we are just going to check compatibility of
+ *     STRUCT/UNION and corresponding FWD, and if they are compatible, we'll
+ *     assume that whatever STRUCT/UNION FWD resolves to must be equivalent to
+ *     a concrete STRUCT/UNION from canonical graph. If the rest of type graphs
+ *     turn out equivalent, we'll re-resolve FWD to concrete STRUCT/UNION from
+ *     canonical graph.
+ */
+static int btf_dedup_is_equiv(struct btf_dedup *d, __u32 cand_id,
+			      __u32 canon_id)
+{
+	struct btf_type *cand_type;
+	struct btf_type *canon_type;
+	__u32 hypot_type_id;
+	__u16 cand_kind;
+	__u16 canon_kind;
+	int i, eq;
+
+	/* if both resolve to the same canonical, they must be equivalent */
+	if (resolve_type_id(d, cand_id) == resolve_type_id(d, canon_id))
+		return 1;
+
+	canon_id = resolve_fwd_id(d, canon_id);
+
+	hypot_type_id = d->hypot_map[canon_id];
+	if (hypot_type_id <= BTF_MAX_NR_TYPES)
+		return hypot_type_id == cand_id;
+
+	if (btf_dedup_hypot_map_add(d, canon_id, cand_id))
+		return -ENOMEM;
+
+	cand_type = d->btf->types[cand_id];
+	canon_type = d->btf->types[canon_id];
+	cand_kind = btf_kind(cand_type);
+	canon_kind = btf_kind(canon_type);
+
+	if (cand_type->name_off != canon_type->name_off)
+		return 0;
+
+	/* FWD <--> STRUCT/UNION equivalence check, if enabled */
+	if (!d->opts.dont_resolve_fwds
+	    && (cand_kind == BTF_KIND_FWD || canon_kind == BTF_KIND_FWD)
+	    && cand_kind != canon_kind) {
+		__u16 real_kind;
+		__u16 fwd_kind;
+
+		if (cand_kind == BTF_KIND_FWD) {
+			real_kind = canon_kind;
+			fwd_kind = btf_fwd_kind(cand_type);
+		} else {
+			real_kind = cand_kind;
+			fwd_kind = btf_fwd_kind(canon_type);
+		}
+		return fwd_kind == real_kind;
+	}
+
+	if (cand_kind != canon_kind)
+		return 0;
+
+	switch (cand_kind) {
+	case BTF_KIND_INT:
+		return btf_equal_int(cand_type, canon_type);
+
+	case BTF_KIND_ENUM:
+		if (d->opts.dont_resolve_fwds)
+			return btf_equal_enum(cand_type, canon_type);
+		else
+			return btf_compat_enum(cand_type, canon_type);
+
+	case BTF_KIND_FWD:
+		return btf_equal_common(cand_type, canon_type);
+
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+		if (cand_type->info != canon_type->info)
+			return 0;
+		return btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+
+	case BTF_KIND_ARRAY: {
+		const struct btf_array *cand_arr, *canon_arr;
+
+		if (!btf_compat_array(cand_type, canon_type))
+			return 0;
+		cand_arr = btf_array(cand_type);
+		canon_arr = btf_array(canon_type);
+		eq = btf_dedup_is_equiv(d,
+			cand_arr->index_type, canon_arr->index_type);
+		if (eq <= 0)
+			return eq;
+		return btf_dedup_is_equiv(d, cand_arr->type, canon_arr->type);
+	}
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *cand_m, *canon_m;
+		__u16 vlen;
+
+		if (!btf_shallow_equal_struct(cand_type, canon_type))
+			return 0;
+		vlen = btf_vlen(cand_type);
+		cand_m = btf_members(cand_type);
+		canon_m = btf_members(canon_type);
+		for (i = 0; i < vlen; i++) {
+			eq = btf_dedup_is_equiv(d, cand_m->type, canon_m->type);
+			if (eq <= 0)
+				return eq;
+			cand_m++;
+			canon_m++;
+		}
+
+		return 1;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *cand_p, *canon_p;
+		__u16 vlen;
+
+		if (!btf_compat_fnproto(cand_type, canon_type))
+			return 0;
+		eq = btf_dedup_is_equiv(d, cand_type->type, canon_type->type);
+		if (eq <= 0)
+			return eq;
+		vlen = btf_vlen(cand_type);
+		cand_p = btf_params(cand_type);
+		canon_p = btf_params(canon_type);
+		for (i = 0; i < vlen; i++) {
+			eq = btf_dedup_is_equiv(d, cand_p->type, canon_p->type);
+			if (eq <= 0)
+				return eq;
+			cand_p++;
+			canon_p++;
+		}
+		return 1;
+	}
+
+	default:
+		return -EINVAL;
+	}
+	return 0;
+}
+
+/*
+ * Use hypothetical mapping, produced by successful type graph equivalence
+ * check, to augment existing struct/union canonical mapping, where possible.
+ *
+ * If BTF_KIND_FWD resolution is allowed, this mapping is also used to record
+ * FWD -> STRUCT/UNION correspondence as well. FWD resolution is bidirectional:
+ * it doesn't matter if FWD type was part of canonical graph or candidate one,
+ * we are recording the mapping anyway. As opposed to carefulness required
+ * for struct/union correspondence mapping (described below), for FWD resolution
+ * it's not important, as by the time that FWD type (reference type) will be
+ * deduplicated all structs/unions will be deduped already anyway.
+ *
+ * Recording STRUCT/UNION mapping is purely a performance optimization and is
+ * not required for correctness. It needs to be done carefully to ensure that
+ * struct/union from candidate's type graph is not mapped into corresponding
+ * struct/union from canonical type graph that itself hasn't been resolved into
+ * canonical representative. The only guarantee we have is that canonical
+ * struct/union was determined as canonical and that won't change. But any
+ * types referenced through that struct/union fields could have been not yet
+ * resolved, so in case like that it's too early to establish any kind of
+ * correspondence between structs/unions.
+ *
+ * No canonical correspondence is derived for primitive types (they are already
+ * deduplicated completely already anyway) or reference types (they rely on
+ * stability of struct/union canonical relationship for equivalence checks).
+ */
+static void btf_dedup_merge_hypot_map(struct btf_dedup *d)
+{
+	__u32 cand_type_id, targ_type_id;
+	__u16 t_kind, c_kind;
+	__u32 t_id, c_id;
+	int i;
+
+	for (i = 0; i < d->hypot_cnt; i++) {
+		cand_type_id = d->hypot_list[i];
+		targ_type_id = d->hypot_map[cand_type_id];
+		t_id = resolve_type_id(d, targ_type_id);
+		c_id = resolve_type_id(d, cand_type_id);
+		t_kind = btf_kind(d->btf->types[t_id]);
+		c_kind = btf_kind(d->btf->types[c_id]);
+		/*
+		 * Resolve FWD into STRUCT/UNION.
+		 * It's ok to resolve FWD into STRUCT/UNION that's not yet
+		 * mapped to canonical representative (as opposed to
+		 * STRUCT/UNION <--> STRUCT/UNION mapping logic below), because
+		 * eventually that struct is going to be mapped and all resolved
+		 * FWDs will automatically resolve to correct canonical
+		 * representative. This will happen before ref type deduping,
+		 * which critically depends on stability of these mapping. This
+		 * stability is not a requirement for STRUCT/UNION equivalence
+		 * checks, though.
+		 */
+		if (t_kind != BTF_KIND_FWD && c_kind == BTF_KIND_FWD)
+			d->map[c_id] = t_id;
+		else if (t_kind == BTF_KIND_FWD && c_kind != BTF_KIND_FWD)
+			d->map[t_id] = c_id;
+
+		if ((t_kind == BTF_KIND_STRUCT || t_kind == BTF_KIND_UNION) &&
+		    c_kind != BTF_KIND_FWD &&
+		    is_type_mapped(d, c_id) &&
+		    !is_type_mapped(d, t_id)) {
+			/*
+			 * as a perf optimization, we can map struct/union
+			 * that's part of type graph we just verified for
+			 * equivalence. We can do that for struct/union that has
+			 * canonical representative only, though.
+			 */
+			d->map[t_id] = c_id;
+		}
+	}
+}
+
+/*
+ * Deduplicate struct/union types.
+ *
+ * For each struct/union type its type signature hash is calculated, taking
+ * into account type's name, size, number, order and names of fields, but
+ * ignoring type ID's referenced from fields, because they might not be deduped
+ * completely until after reference types deduplication phase. This type hash
+ * is used to iterate over all potential canonical types, sharing same hash.
+ * For each canonical candidate we check whether type graphs that they form
+ * (through referenced types in fields and so on) are equivalent using algorithm
+ * implemented in `btf_dedup_is_equiv`. If such equivalence is found and
+ * BTF_KIND_FWD resolution is allowed, then hypothetical mapping
+ * (btf_dedup->hypot_map) produced by aforementioned type graph equivalence
+ * algorithm is used to record FWD -> STRUCT/UNION mapping. It's also used to
+ * potentially map other structs/unions to their canonical representatives,
+ * if such relationship hasn't yet been established. This speeds up algorithm
+ * by eliminating some of the duplicate work.
+ *
+ * If no matching canonical representative was found, struct/union is marked
+ * as canonical for itself and is added into btf_dedup->dedup_table hash map
+ * for further look ups.
+ */
+static int btf_dedup_struct_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct btf_type *cand_type, *t;
+	struct hashmap_entry *hash_entry;
+	/* if we don't find equivalent type, then we are canonical */
+	__u32 new_id = type_id;
+	__u16 kind;
+	long h;
+
+	/* already deduped or is in process of deduping (loop detected) */
+	if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+		return 0;
+
+	t = d->btf->types[type_id];
+	kind = btf_kind(t);
+
+	if (kind != BTF_KIND_STRUCT && kind != BTF_KIND_UNION)
+		return 0;
+
+	h = btf_hash_struct(t);
+	for_each_dedup_cand(d, hash_entry, h) {
+		__u32 cand_id = (__u32)(long)hash_entry->value;
+		int eq;
+
+		/*
+		 * Even though btf_dedup_is_equiv() checks for
+		 * btf_shallow_equal_struct() internally when checking two
+		 * structs (unions) for equivalence, we need to guard here
+		 * from picking matching FWD type as a dedup candidate.
+		 * This can happen due to hash collision. In such case just
+		 * relying on btf_dedup_is_equiv() would lead to potentially
+		 * creating a loop (FWD -> STRUCT and STRUCT -> FWD), because
+		 * FWD and compatible STRUCT/UNION are considered equivalent.
+		 */
+		cand_type = d->btf->types[cand_id];
+		if (!btf_shallow_equal_struct(t, cand_type))
+			continue;
+
+		btf_dedup_clear_hypot_map(d);
+		eq = btf_dedup_is_equiv(d, type_id, cand_id);
+		if (eq < 0)
+			return eq;
+		if (!eq)
+			continue;
+		new_id = cand_id;
+		btf_dedup_merge_hypot_map(d);
+		break;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return 0;
+}
+
+static int btf_dedup_struct_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		err = btf_dedup_struct_type(d, i);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+/*
+ * Deduplicate reference type.
+ *
+ * Once all primitive and struct/union types got deduplicated, we can easily
+ * deduplicate all other (reference) BTF types. This is done in two steps:
+ *
+ * 1. Resolve all referenced type IDs into their canonical type IDs. This
+ * resolution can be done either immediately for primitive or struct/union types
+ * (because they were deduped in previous two phases) or recursively for
+ * reference types. Recursion will always terminate at either primitive or
+ * struct/union type, at which point we can "unwind" chain of reference types
+ * one by one. There is no danger of encountering cycles because in C type
+ * system the only way to form type cycle is through struct/union, so any chain
+ * of reference types, even those taking part in a type cycle, will inevitably
+ * reach struct/union at some point.
+ *
+ * 2. Once all referenced type IDs are resolved into canonical ones, BTF type
+ * becomes "stable", in the sense that no further deduplication will cause
+ * any changes to it. With that, it's now possible to calculate type's signature
+ * hash (this time taking into account referenced type IDs) and loop over all
+ * potential canonical representatives. If no match was found, current type
+ * will become canonical representative of itself and will be added into
+ * btf_dedup->dedup_table as another possible canonical representative.
+ */
+static int btf_dedup_ref_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct hashmap_entry *hash_entry;
+	__u32 new_id = type_id, cand_id;
+	struct btf_type *t, *cand;
+	/* if we don't find equivalent type, then we are representative type */
+	int ref_type_id;
+	long h;
+
+	if (d->map[type_id] == BTF_IN_PROGRESS_ID)
+		return -ELOOP;
+	if (d->map[type_id] <= BTF_MAX_NR_TYPES)
+		return resolve_type_id(d, type_id);
+
+	t = d->btf->types[type_id];
+	d->map[type_id] = BTF_IN_PROGRESS_ID;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+		ref_type_id = btf_dedup_ref_type(d, t->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		t->type = ref_type_id;
+
+		h = btf_hash_common(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_common(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+
+	case BTF_KIND_ARRAY: {
+		struct btf_array *info = btf_array(t);
+
+		ref_type_id = btf_dedup_ref_type(d, info->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		info->type = ref_type_id;
+
+		ref_type_id = btf_dedup_ref_type(d, info->index_type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		info->index_type = ref_type_id;
+
+		h = btf_hash_array(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_array(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *param;
+		__u16 vlen;
+		int i;
+
+		ref_type_id = btf_dedup_ref_type(d, t->type);
+		if (ref_type_id < 0)
+			return ref_type_id;
+		t->type = ref_type_id;
+
+		vlen = btf_vlen(t);
+		param = btf_params(t);
+		for (i = 0; i < vlen; i++) {
+			ref_type_id = btf_dedup_ref_type(d, param->type);
+			if (ref_type_id < 0)
+				return ref_type_id;
+			param->type = ref_type_id;
+			param++;
+		}
+
+		h = btf_hash_fnproto(t);
+		for_each_dedup_cand(d, hash_entry, h) {
+			cand_id = (__u32)(long)hash_entry->value;
+			cand = d->btf->types[cand_id];
+			if (btf_equal_fnproto(t, cand)) {
+				new_id = cand_id;
+				break;
+			}
+		}
+		break;
+	}
+
+	default:
+		return -EINVAL;
+	}
+
+	d->map[type_id] = new_id;
+	if (type_id == new_id && btf_dedup_table_add(d, h, type_id))
+		return -ENOMEM;
+
+	return new_id;
+}
+
+static int btf_dedup_ref_types(struct btf_dedup *d)
+{
+	int i, err;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		err = btf_dedup_ref_type(d, i);
+		if (err < 0)
+			return err;
+	}
+	/* we won't need d->dedup_table anymore */
+	hashmap__free(d->dedup_table);
+	d->dedup_table = NULL;
+	return 0;
+}
+
+/*
+ * Compact types.
+ *
+ * After we established for each type its corresponding canonical representative
+ * type, we now can eliminate types that are not canonical and leave only
+ * canonical ones layed out sequentially in memory by copying them over
+ * duplicates. During compaction btf_dedup->hypot_map array is reused to store
+ * a map from original type ID to a new compacted type ID, which will be used
+ * during next phase to "fix up" type IDs, referenced from struct/union and
+ * reference types.
+ */
+static int btf_dedup_compact_types(struct btf_dedup *d)
+{
+	struct btf_type **new_types;
+	__u32 next_type_id = 1;
+	char *types_start, *p;
+	int i, len;
+
+	/* we are going to reuse hypot_map to store compaction remapping */
+	d->hypot_map[0] = 0;
+	for (i = 1; i <= d->btf->nr_types; i++)
+		d->hypot_map[i] = BTF_UNPROCESSED_ID;
+
+	types_start = d->btf->nohdr_data + d->btf->hdr->type_off;
+	p = types_start;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		if (d->map[i] != i)
+			continue;
+
+		len = btf_type_size(d->btf->types[i]);
+		if (len < 0)
+			return len;
+
+		memmove(p, d->btf->types[i], len);
+		d->hypot_map[i] = next_type_id;
+		d->btf->types[next_type_id] = (struct btf_type *)p;
+		p += len;
+		next_type_id++;
+	}
+
+	/* shrink struct btf's internal types index and update btf_header */
+	d->btf->nr_types = next_type_id - 1;
+	d->btf->types_size = d->btf->nr_types;
+	d->btf->hdr->type_len = p - types_start;
+	new_types = realloc(d->btf->types,
+			    (1 + d->btf->nr_types) * sizeof(struct btf_type *));
+	if (!new_types)
+		return -ENOMEM;
+	d->btf->types = new_types;
+
+	/* make sure string section follows type information without gaps */
+	d->btf->hdr->str_off = p - (char *)d->btf->nohdr_data;
+	memmove(p, d->btf->strings, d->btf->hdr->str_len);
+	d->btf->strings = p;
+	p += d->btf->hdr->str_len;
+
+	d->btf->data_size = p - (char *)d->btf->data;
+	return 0;
+}
+
+/*
+ * Figure out final (deduplicated and compacted) type ID for provided original
+ * `type_id` by first resolving it into corresponding canonical type ID and
+ * then mapping it to a deduplicated type ID, stored in btf_dedup->hypot_map,
+ * which is populated during compaction phase.
+ */
+static int btf_dedup_remap_type_id(struct btf_dedup *d, __u32 type_id)
+{
+	__u32 resolved_type_id, new_type_id;
+
+	resolved_type_id = resolve_type_id(d, type_id);
+	new_type_id = d->hypot_map[resolved_type_id];
+	if (new_type_id > BTF_MAX_NR_TYPES)
+		return -EINVAL;
+	return new_type_id;
+}
+
+/*
+ * Remap referenced type IDs into deduped type IDs.
+ *
+ * After BTF types are deduplicated and compacted, their final type IDs may
+ * differ from original ones. The map from original to a corresponding
+ * deduped type ID is stored in btf_dedup->hypot_map and is populated during
+ * compaction phase. During remapping phase we are rewriting all type IDs
+ * referenced from any BTF type (e.g., struct fields, func proto args, etc) to
+ * their final deduped type IDs.
+ */
+static int btf_dedup_remap_type(struct btf_dedup *d, __u32 type_id)
+{
+	struct btf_type *t = d->btf->types[type_id];
+	int i, r;
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+	case BTF_KIND_ENUM:
+		break;
+
+	case BTF_KIND_FWD:
+	case BTF_KIND_CONST:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_RESTRICT:
+	case BTF_KIND_PTR:
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
+		r = btf_dedup_remap_type_id(d, t->type);
+		if (r < 0)
+			return r;
+		t->type = r;
+		break;
+
+	case BTF_KIND_ARRAY: {
+		struct btf_array *arr_info = btf_array(t);
+
+		r = btf_dedup_remap_type_id(d, arr_info->type);
+		if (r < 0)
+			return r;
+		arr_info->type = r;
+		r = btf_dedup_remap_type_id(d, arr_info->index_type);
+		if (r < 0)
+			return r;
+		arr_info->index_type = r;
+		break;
+	}
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		struct btf_member *member = btf_members(t);
+		__u16 vlen = btf_vlen(t);
+
+		for (i = 0; i < vlen; i++) {
+			r = btf_dedup_remap_type_id(d, member->type);
+			if (r < 0)
+				return r;
+			member->type = r;
+			member++;
+		}
+		break;
+	}
+
+	case BTF_KIND_FUNC_PROTO: {
+		struct btf_param *param = btf_params(t);
+		__u16 vlen = btf_vlen(t);
+
+		r = btf_dedup_remap_type_id(d, t->type);
+		if (r < 0)
+			return r;
+		t->type = r;
+
+		for (i = 0; i < vlen; i++) {
+			r = btf_dedup_remap_type_id(d, param->type);
+			if (r < 0)
+				return r;
+			param->type = r;
+			param++;
+		}
+		break;
+	}
+
+	case BTF_KIND_DATASEC: {
+		struct btf_var_secinfo *var = btf_var_secinfos(t);
+		__u16 vlen = btf_vlen(t);
+
+		for (i = 0; i < vlen; i++) {
+			r = btf_dedup_remap_type_id(d, var->type);
+			if (r < 0)
+				return r;
+			var->type = r;
+			var++;
+		}
+		break;
+	}
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int btf_dedup_remap_types(struct btf_dedup *d)
+{
+	int i, r;
+
+	for (i = 1; i <= d->btf->nr_types; i++) {
+		r = btf_dedup_remap_type(d, i);
+		if (r < 0)
+			return r;
+	}
+	return 0;
+}
diff --git a/src/contrib/libbpf/bpf/btf.h b/src/contrib/libbpf/bpf/btf.h
new file mode 100644
index 0000000..d9ac73a
--- /dev/null
+++ b/src/contrib/libbpf/bpf/btf.h
@@ -0,0 +1,311 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2018 Facebook */
+
+#ifndef __LIBBPF_BTF_H
+#define __LIBBPF_BTF_H
+
+#include <stdarg.h>
+#include <linux/btf.h>
+#include <linux/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef LIBBPF_API
+#define LIBBPF_API __attribute__((visibility("default")))
+#endif
+
+#define BTF_ELF_SEC ".BTF"
+#define BTF_EXT_ELF_SEC ".BTF.ext"
+#define MAPS_ELF_SEC ".maps"
+
+struct btf;
+struct btf_ext;
+struct btf_type;
+
+struct bpf_object;
+
+/*
+ * The .BTF.ext ELF section layout defined as
+ *   struct btf_ext_header
+ *   func_info subsection
+ *
+ * The func_info subsection layout:
+ *   record size for struct bpf_func_info in the func_info subsection
+ *   struct btf_sec_func_info for section #1
+ *   a list of bpf_func_info records for section #1
+ *     where struct bpf_func_info mimics one in include/uapi/linux/bpf.h
+ *     but may not be identical
+ *   struct btf_sec_func_info for section #2
+ *   a list of bpf_func_info records for section #2
+ *   ......
+ *
+ * Note that the bpf_func_info record size in .BTF.ext may not
+ * be the same as the one defined in include/uapi/linux/bpf.h.
+ * The loader should ensure that record_size meets minimum
+ * requirement and pass the record as is to the kernel. The
+ * kernel will handle the func_info properly based on its contents.
+ */
+struct btf_ext_header {
+	__u16	magic;
+	__u8	version;
+	__u8	flags;
+	__u32	hdr_len;
+
+	/* All offsets are in bytes relative to the end of this header */
+	__u32	func_info_off;
+	__u32	func_info_len;
+	__u32	line_info_off;
+	__u32	line_info_len;
+
+	/* optional part of .BTF.ext header */
+	__u32	field_reloc_off;
+	__u32	field_reloc_len;
+};
+
+LIBBPF_API void btf__free(struct btf *btf);
+LIBBPF_API struct btf *btf__new(__u8 *data, __u32 size);
+LIBBPF_API struct btf *btf__parse_elf(const char *path,
+				      struct btf_ext **btf_ext);
+LIBBPF_API int btf__finalize_data(struct bpf_object *obj, struct btf *btf);
+LIBBPF_API int btf__load(struct btf *btf);
+LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
+				   const char *type_name);
+LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf,
+					const char *type_name, __u32 kind);
+LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf);
+LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
+						  __u32 id);
+LIBBPF_API __s64 btf__resolve_size(const struct btf *btf, __u32 type_id);
+LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
+LIBBPF_API int btf__fd(const struct btf *btf);
+LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
+LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
+LIBBPF_API int btf__get_from_id(__u32 id, struct btf **btf);
+LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,
+				    __u32 expected_key_size,
+				    __u32 expected_value_size,
+				    __u32 *key_type_id, __u32 *value_type_id);
+
+LIBBPF_API struct btf_ext *btf_ext__new(__u8 *data, __u32 size);
+LIBBPF_API void btf_ext__free(struct btf_ext *btf_ext);
+LIBBPF_API const void *btf_ext__get_raw_data(const struct btf_ext *btf_ext,
+					     __u32 *size);
+LIBBPF_API int btf_ext__reloc_func_info(const struct btf *btf,
+					const struct btf_ext *btf_ext,
+					const char *sec_name, __u32 insns_cnt,
+					void **func_info, __u32 *cnt);
+LIBBPF_API int btf_ext__reloc_line_info(const struct btf *btf,
+					const struct btf_ext *btf_ext,
+					const char *sec_name, __u32 insns_cnt,
+					void **line_info, __u32 *cnt);
+LIBBPF_API __u32 btf_ext__func_info_rec_size(const struct btf_ext *btf_ext);
+LIBBPF_API __u32 btf_ext__line_info_rec_size(const struct btf_ext *btf_ext);
+
+struct btf_dedup_opts {
+	unsigned int dedup_table_size;
+	bool dont_resolve_fwds;
+};
+
+LIBBPF_API int btf__dedup(struct btf *btf, struct btf_ext *btf_ext,
+			  const struct btf_dedup_opts *opts);
+
+struct btf_dump;
+
+struct btf_dump_opts {
+	void *ctx;
+};
+
+typedef void (*btf_dump_printf_fn_t)(void *ctx, const char *fmt, va_list args);
+
+LIBBPF_API struct btf_dump *btf_dump__new(const struct btf *btf,
+					  const struct btf_ext *btf_ext,
+					  const struct btf_dump_opts *opts,
+					  btf_dump_printf_fn_t printf_fn);
+LIBBPF_API void btf_dump__free(struct btf_dump *d);
+
+LIBBPF_API int btf_dump__dump_type(struct btf_dump *d, __u32 id);
+
+/*
+ * A set of helpers for easier BTF types handling
+ */
+static inline __u16 btf_kind(const struct btf_type *t)
+{
+	return BTF_INFO_KIND(t->info);
+}
+
+static inline __u16 btf_vlen(const struct btf_type *t)
+{
+	return BTF_INFO_VLEN(t->info);
+}
+
+static inline bool btf_kflag(const struct btf_type *t)
+{
+	return BTF_INFO_KFLAG(t->info);
+}
+
+static inline bool btf_is_int(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_INT;
+}
+
+static inline bool btf_is_ptr(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_PTR;
+}
+
+static inline bool btf_is_array(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_ARRAY;
+}
+
+static inline bool btf_is_struct(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_STRUCT;
+}
+
+static inline bool btf_is_union(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_UNION;
+}
+
+static inline bool btf_is_composite(const struct btf_type *t)
+{
+	__u16 kind = btf_kind(t);
+
+	return kind == BTF_KIND_STRUCT || kind == BTF_KIND_UNION;
+}
+
+static inline bool btf_is_enum(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_ENUM;
+}
+
+static inline bool btf_is_fwd(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FWD;
+}
+
+static inline bool btf_is_typedef(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_TYPEDEF;
+}
+
+static inline bool btf_is_volatile(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_VOLATILE;
+}
+
+static inline bool btf_is_const(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_CONST;
+}
+
+static inline bool btf_is_restrict(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_RESTRICT;
+}
+
+static inline bool btf_is_mod(const struct btf_type *t)
+{
+	__u16 kind = btf_kind(t);
+
+	return kind == BTF_KIND_VOLATILE ||
+	       kind == BTF_KIND_CONST ||
+	       kind == BTF_KIND_RESTRICT;
+}
+
+static inline bool btf_is_func(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FUNC;
+}
+
+static inline bool btf_is_func_proto(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_FUNC_PROTO;
+}
+
+static inline bool btf_is_var(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_VAR;
+}
+
+static inline bool btf_is_datasec(const struct btf_type *t)
+{
+	return btf_kind(t) == BTF_KIND_DATASEC;
+}
+
+static inline __u8 btf_int_encoding(const struct btf_type *t)
+{
+	return BTF_INT_ENCODING(*(__u32 *)(t + 1));
+}
+
+static inline __u8 btf_int_offset(const struct btf_type *t)
+{
+	return BTF_INT_OFFSET(*(__u32 *)(t + 1));
+}
+
+static inline __u8 btf_int_bits(const struct btf_type *t)
+{
+	return BTF_INT_BITS(*(__u32 *)(t + 1));
+}
+
+static inline struct btf_array *btf_array(const struct btf_type *t)
+{
+	return (struct btf_array *)(t + 1);
+}
+
+static inline struct btf_enum *btf_enum(const struct btf_type *t)
+{
+	return (struct btf_enum *)(t + 1);
+}
+
+static inline struct btf_member *btf_members(const struct btf_type *t)
+{
+	return (struct btf_member *)(t + 1);
+}
+
+/* Get bit offset of a member with specified index. */
+static inline __u32 btf_member_bit_offset(const struct btf_type *t,
+					  __u32 member_idx)
+{
+	const struct btf_member *m = btf_members(t) + member_idx;
+	bool kflag = btf_kflag(t);
+
+	return kflag ? BTF_MEMBER_BIT_OFFSET(m->offset) : m->offset;
+}
+/*
+ * Get bitfield size of a member, assuming t is BTF_KIND_STRUCT or
+ * BTF_KIND_UNION. If member is not a bitfield, zero is returned.
+ */
+static inline __u32 btf_member_bitfield_size(const struct btf_type *t,
+					     __u32 member_idx)
+{
+	const struct btf_member *m = btf_members(t) + member_idx;
+	bool kflag = btf_kflag(t);
+
+	return kflag ? BTF_MEMBER_BITFIELD_SIZE(m->offset) : 0;
+}
+
+static inline struct btf_param *btf_params(const struct btf_type *t)
+{
+	return (struct btf_param *)(t + 1);
+}
+
+static inline struct btf_var *btf_var(const struct btf_type *t)
+{
+	return (struct btf_var *)(t + 1);
+}
+
+static inline struct btf_var_secinfo *
+btf_var_secinfos(const struct btf_type *t)
+{
+	return (struct btf_var_secinfo *)(t + 1);
+}
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_BTF_H */
diff --git a/src/contrib/libbpf/bpf/btf_dump.c b/src/contrib/libbpf/bpf/btf_dump.c
new file mode 100644
index 0000000..cb126d8
--- /dev/null
+++ b/src/contrib/libbpf/bpf/btf_dump.c
@@ -0,0 +1,1386 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * BTF-to-C type converter.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <linux/err.h>
+#include <linux/btf.h>
+#include "btf.h"
+#include "hashmap.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+static const char PREFIXES[] = "\t\t\t\t\t\t\t\t\t\t\t\t\t";
+static const size_t PREFIX_CNT = sizeof(PREFIXES) - 1;
+
+static const char *pfx(int lvl)
+{
+	return lvl >= PREFIX_CNT ? PREFIXES : &PREFIXES[PREFIX_CNT - lvl];
+}
+
+enum btf_dump_type_order_state {
+	NOT_ORDERED,
+	ORDERING,
+	ORDERED,
+};
+
+enum btf_dump_type_emit_state {
+	NOT_EMITTED,
+	EMITTING,
+	EMITTED,
+};
+
+/* per-type auxiliary state */
+struct btf_dump_type_aux_state {
+	/* topological sorting state */
+	enum btf_dump_type_order_state order_state: 2;
+	/* emitting state used to determine the need for forward declaration */
+	enum btf_dump_type_emit_state emit_state: 2;
+	/* whether forward declaration was already emitted */
+	__u8 fwd_emitted: 1;
+	/* whether unique non-duplicate name was already assigned */
+	__u8 name_resolved: 1;
+	/* whether type is referenced from any other type */
+	__u8 referenced: 1;
+};
+
+struct btf_dump {
+	const struct btf *btf;
+	const struct btf_ext *btf_ext;
+	btf_dump_printf_fn_t printf_fn;
+	struct btf_dump_opts opts;
+
+	/* per-type auxiliary state */
+	struct btf_dump_type_aux_state *type_states;
+	/* per-type optional cached unique name, must be freed, if present */
+	const char **cached_names;
+
+	/* topo-sorted list of dependent type definitions */
+	__u32 *emit_queue;
+	int emit_queue_cap;
+	int emit_queue_cnt;
+
+	/*
+	 * stack of type declarations (e.g., chain of modifiers, arrays,
+	 * funcs, etc)
+	 */
+	__u32 *decl_stack;
+	int decl_stack_cap;
+	int decl_stack_cnt;
+
+	/* maps struct/union/enum name to a number of name occurrences */
+	struct hashmap *type_names;
+	/*
+	 * maps typedef identifiers and enum value names to a number of such
+	 * name occurrences
+	 */
+	struct hashmap *ident_names;
+};
+
+static size_t str_hash_fn(const void *key, void *ctx)
+{
+	const char *s = key;
+	size_t h = 0;
+
+	while (*s) {
+		h = h * 31 + *s;
+		s++;
+	}
+	return h;
+}
+
+static bool str_equal_fn(const void *a, const void *b, void *ctx)
+{
+	return strcmp(a, b) == 0;
+}
+
+static const char *btf_name_of(const struct btf_dump *d, __u32 name_off)
+{
+	return btf__name_by_offset(d->btf, name_off);
+}
+
+static void btf_dump_printf(const struct btf_dump *d, const char *fmt, ...)
+{
+	va_list args;
+
+	va_start(args, fmt);
+	d->printf_fn(d->opts.ctx, fmt, args);
+	va_end(args);
+}
+
+struct btf_dump *btf_dump__new(const struct btf *btf,
+			       const struct btf_ext *btf_ext,
+			       const struct btf_dump_opts *opts,
+			       btf_dump_printf_fn_t printf_fn)
+{
+	struct btf_dump *d;
+	int err;
+
+	d = calloc(1, sizeof(struct btf_dump));
+	if (!d)
+		return ERR_PTR(-ENOMEM);
+
+	d->btf = btf;
+	d->btf_ext = btf_ext;
+	d->printf_fn = printf_fn;
+	d->opts.ctx = opts ? opts->ctx : NULL;
+
+	d->type_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
+	if (IS_ERR(d->type_names)) {
+		err = PTR_ERR(d->type_names);
+		d->type_names = NULL;
+		btf_dump__free(d);
+		return ERR_PTR(err);
+	}
+	d->ident_names = hashmap__new(str_hash_fn, str_equal_fn, NULL);
+	if (IS_ERR(d->ident_names)) {
+		err = PTR_ERR(d->ident_names);
+		d->ident_names = NULL;
+		btf_dump__free(d);
+		return ERR_PTR(err);
+	}
+
+	return d;
+}
+
+void btf_dump__free(struct btf_dump *d)
+{
+	int i, cnt;
+
+	if (!d)
+		return;
+
+	free(d->type_states);
+	if (d->cached_names) {
+		/* any set cached name is owned by us and should be freed */
+		for (i = 0, cnt = btf__get_nr_types(d->btf); i <= cnt; i++) {
+			if (d->cached_names[i])
+				free((void *)d->cached_names[i]);
+		}
+	}
+	free(d->cached_names);
+	free(d->emit_queue);
+	free(d->decl_stack);
+	hashmap__free(d->type_names);
+	hashmap__free(d->ident_names);
+
+	free(d);
+}
+
+static int btf_dump_mark_referenced(struct btf_dump *d);
+static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr);
+static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id);
+
+/*
+ * Dump BTF type in a compilable C syntax, including all the necessary
+ * dependent types, necessary for compilation. If some of the dependent types
+ * were already emitted as part of previous btf_dump__dump_type() invocation
+ * for another type, they won't be emitted again. This API allows callers to
+ * filter out BTF types according to user-defined criterias and emitted only
+ * minimal subset of types, necessary to compile everything. Full struct/union
+ * definitions will still be emitted, even if the only usage is through
+ * pointer and could be satisfied with just a forward declaration.
+ *
+ * Dumping is done in two high-level passes:
+ *   1. Topologically sort type definitions to satisfy C rules of compilation.
+ *   2. Emit type definitions in C syntax.
+ *
+ * Returns 0 on success; <0, otherwise.
+ */
+int btf_dump__dump_type(struct btf_dump *d, __u32 id)
+{
+	int err, i;
+
+	if (id > btf__get_nr_types(d->btf))
+		return -EINVAL;
+
+	/* type states are lazily allocated, as they might not be needed */
+	if (!d->type_states) {
+		d->type_states = calloc(1 + btf__get_nr_types(d->btf),
+					sizeof(d->type_states[0]));
+		if (!d->type_states)
+			return -ENOMEM;
+		d->cached_names = calloc(1 + btf__get_nr_types(d->btf),
+					 sizeof(d->cached_names[0]));
+		if (!d->cached_names)
+			return -ENOMEM;
+
+		/* VOID is special */
+		d->type_states[0].order_state = ORDERED;
+		d->type_states[0].emit_state = EMITTED;
+
+		/* eagerly determine referenced types for anon enums */
+		err = btf_dump_mark_referenced(d);
+		if (err)
+			return err;
+	}
+
+	d->emit_queue_cnt = 0;
+	err = btf_dump_order_type(d, id, false);
+	if (err < 0)
+		return err;
+
+	for (i = 0; i < d->emit_queue_cnt; i++)
+		btf_dump_emit_type(d, d->emit_queue[i], 0 /*top-level*/);
+
+	return 0;
+}
+
+/*
+ * Mark all types that are referenced from any other type. This is used to
+ * determine top-level anonymous enums that need to be emitted as an
+ * independent type declarations.
+ * Anonymous enums come in two flavors: either embedded in a struct's field
+ * definition, in which case they have to be declared inline as part of field
+ * type declaration; or as a top-level anonymous enum, typically used for
+ * declaring global constants. It's impossible to distinguish between two
+ * without knowning whether given enum type was referenced from other type:
+ * top-level anonymous enum won't be referenced by anything, while embedded
+ * one will.
+ */
+static int btf_dump_mark_referenced(struct btf_dump *d)
+{
+	int i, j, n = btf__get_nr_types(d->btf);
+	const struct btf_type *t;
+	__u16 vlen;
+
+	for (i = 1; i <= n; i++) {
+		t = btf__type_by_id(d->btf, i);
+		vlen = btf_vlen(t);
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_INT:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_FWD:
+			break;
+
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_PTR:
+		case BTF_KIND_TYPEDEF:
+		case BTF_KIND_FUNC:
+		case BTF_KIND_VAR:
+			d->type_states[t->type].referenced = 1;
+			break;
+
+		case BTF_KIND_ARRAY: {
+			const struct btf_array *a = btf_array(t);
+
+			d->type_states[a->index_type].referenced = 1;
+			d->type_states[a->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION: {
+			const struct btf_member *m = btf_members(t);
+
+			for (j = 0; j < vlen; j++, m++)
+				d->type_states[m->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_FUNC_PROTO: {
+			const struct btf_param *p = btf_params(t);
+
+			for (j = 0; j < vlen; j++, p++)
+				d->type_states[p->type].referenced = 1;
+			break;
+		}
+		case BTF_KIND_DATASEC: {
+			const struct btf_var_secinfo *v = btf_var_secinfos(t);
+
+			for (j = 0; j < vlen; j++, v++)
+				d->type_states[v->type].referenced = 1;
+			break;
+		}
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)
+{
+	__u32 *new_queue;
+	size_t new_cap;
+
+	if (d->emit_queue_cnt >= d->emit_queue_cap) {
+		new_cap = max(16, d->emit_queue_cap * 3 / 2);
+		new_queue = realloc(d->emit_queue,
+				    new_cap * sizeof(new_queue[0]));
+		if (!new_queue)
+			return -ENOMEM;
+		d->emit_queue = new_queue;
+		d->emit_queue_cap = new_cap;
+	}
+
+	d->emit_queue[d->emit_queue_cnt++] = id;
+	return 0;
+}
+
+/*
+ * Determine order of emitting dependent types and specified type to satisfy
+ * C compilation rules.  This is done through topological sorting with an
+ * additional complication which comes from C rules. The main idea for C is
+ * that if some type is "embedded" into a struct/union, it's size needs to be
+ * known at the time of definition of containing type. E.g., for:
+ *
+ *	struct A {};
+ *	struct B { struct A x; }
+ *
+ * struct A *HAS* to be defined before struct B, because it's "embedded",
+ * i.e., it is part of struct B layout. But in the following case:
+ *
+ *	struct A;
+ *	struct B { struct A *x; }
+ *	struct A {};
+ *
+ * it's enough to just have a forward declaration of struct A at the time of
+ * struct B definition, as struct B has a pointer to struct A, so the size of
+ * field x is known without knowing struct A size: it's sizeof(void *).
+ *
+ * Unfortunately, there are some trickier cases we need to handle, e.g.:
+ *
+ *	struct A {}; // if this was forward-declaration: compilation error
+ *	struct B {
+ *		struct { // anonymous struct
+ *			struct A y;
+ *		} *x;
+ *	};
+ *
+ * In this case, struct B's field x is a pointer, so it's size is known
+ * regardless of the size of (anonymous) struct it points to. But because this
+ * struct is anonymous and thus defined inline inside struct B, *and* it
+ * embeds struct A, compiler requires full definition of struct A to be known
+ * before struct B can be defined. This creates a transitive dependency
+ * between struct A and struct B. If struct A was forward-declared before
+ * struct B definition and fully defined after struct B definition, that would
+ * trigger compilation error.
+ *
+ * All this means that while we are doing topological sorting on BTF type
+ * graph, we need to determine relationships between different types (graph
+ * nodes):
+ *   - weak link (relationship) between X and Y, if Y *CAN* be
+ *   forward-declared at the point of X definition;
+ *   - strong link, if Y *HAS* to be fully-defined before X can be defined.
+ *
+ * The rule is as follows. Given a chain of BTF types from X to Y, if there is
+ * BTF_KIND_PTR type in the chain and at least one non-anonymous type
+ * Z (excluding X, including Y), then link is weak. Otherwise, it's strong.
+ * Weak/strong relationship is determined recursively during DFS traversal and
+ * is returned as a result from btf_dump_order_type().
+ *
+ * btf_dump_order_type() is trying to avoid unnecessary forward declarations,
+ * but it is not guaranteeing that no extraneous forward declarations will be
+ * emitted.
+ *
+ * To avoid extra work, algorithm marks some of BTF types as ORDERED, when
+ * it's done with them, but not for all (e.g., VOLATILE, CONST, RESTRICT,
+ * ARRAY, FUNC_PROTO), as weak/strong semantics for those depends on the
+ * entire graph path, so depending where from one came to that BTF type, it
+ * might cause weak or strong ordering. For types like STRUCT/UNION/INT/ENUM,
+ * once they are processed, there is no need to do it again, so they are
+ * marked as ORDERED. We can mark PTR as ORDERED as well, as it semi-forces
+ * weak link, unless subsequent referenced STRUCT/UNION/ENUM is anonymous. But
+ * in any case, once those are processed, no need to do it again, as the
+ * result won't change.
+ *
+ * Returns:
+ *   - 1, if type is part of strong link (so there is strong topological
+ *   ordering requirements);
+ *   - 0, if type is part of weak link (so can be satisfied through forward
+ *   declaration);
+ *   - <0, on error (e.g., unsatisfiable type loop detected).
+ */
+static int btf_dump_order_type(struct btf_dump *d, __u32 id, bool through_ptr)
+{
+	/*
+	 * Order state is used to detect strong link cycles, but only for BTF
+	 * kinds that are or could be an independent definition (i.e.,
+	 * stand-alone fwd decl, enum, typedef, struct, union). Ptrs, arrays,
+	 * func_protos, modifiers are just means to get to these definitions.
+	 * Int/void don't need definitions, they are assumed to be always
+	 * properly defined.  We also ignore datasec, var, and funcs for now.
+	 * So for all non-defining kinds, we never even set ordering state,
+	 * for defining kinds we set ORDERING and subsequently ORDERED if it
+	 * forms a strong link.
+	 */
+	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
+	const struct btf_type *t;
+	__u16 vlen;
+	int err, i;
+
+	/* return true, letting typedefs know that it's ok to be emitted */
+	if (tstate->order_state == ORDERED)
+		return 1;
+
+	t = btf__type_by_id(d->btf, id);
+
+	if (tstate->order_state == ORDERING) {
+		/* type loop, but resolvable through fwd declaration */
+		if (btf_is_composite(t) && through_ptr && t->name_off != 0)
+			return 0;
+		pr_warn("unsatisfiable type cycle, id:[%u]\n", id);
+		return -ELOOP;
+	}
+
+	switch (btf_kind(t)) {
+	case BTF_KIND_INT:
+		tstate->order_state = ORDERED;
+		return 0;
+
+	case BTF_KIND_PTR:
+		err = btf_dump_order_type(d, t->type, true);
+		tstate->order_state = ORDERED;
+		return err;
+
+	case BTF_KIND_ARRAY:
+		return btf_dump_order_type(d, btf_array(t)->type, through_ptr);
+
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m = btf_members(t);
+		/*
+		 * struct/union is part of strong link, only if it's embedded
+		 * (so no ptr in a path) or it's anonymous (so has to be
+		 * defined inline, even if declared through ptr)
+		 */
+		if (through_ptr && t->name_off != 0)
+			return 0;
+
+		tstate->order_state = ORDERING;
+
+		vlen = btf_vlen(t);
+		for (i = 0; i < vlen; i++, m++) {
+			err = btf_dump_order_type(d, m->type, false);
+			if (err < 0)
+				return err;
+		}
+
+		if (t->name_off != 0) {
+			err = btf_dump_add_emit_queue_id(d, id);
+			if (err < 0)
+				return err;
+		}
+
+		tstate->order_state = ORDERED;
+		return 1;
+	}
+	case BTF_KIND_ENUM:
+	case BTF_KIND_FWD:
+		/*
+		 * non-anonymous or non-referenced enums are top-level
+		 * declarations and should be emitted. Same logic can be
+		 * applied to FWDs, it won't hurt anyways.
+		 */
+		if (t->name_off != 0 || !tstate->referenced) {
+			err = btf_dump_add_emit_queue_id(d, id);
+			if (err)
+				return err;
+		}
+		tstate->order_state = ORDERED;
+		return 1;
+
+	case BTF_KIND_TYPEDEF: {
+		int is_strong;
+
+		is_strong = btf_dump_order_type(d, t->type, through_ptr);
+		if (is_strong < 0)
+			return is_strong;
+
+		/* typedef is similar to struct/union w.r.t. fwd-decls */
+		if (through_ptr && !is_strong)
+			return 0;
+
+		/* typedef is always a named definition */
+		err = btf_dump_add_emit_queue_id(d, id);
+		if (err)
+			return err;
+
+		d->type_states[id].order_state = ORDERED;
+		return 1;
+	}
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		return btf_dump_order_type(d, t->type, through_ptr);
+
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *p = btf_params(t);
+		bool is_strong;
+
+		err = btf_dump_order_type(d, t->type, through_ptr);
+		if (err < 0)
+			return err;
+		is_strong = err > 0;
+
+		vlen = btf_vlen(t);
+		for (i = 0; i < vlen; i++, p++) {
+			err = btf_dump_order_type(d, p->type, through_ptr);
+			if (err < 0)
+				return err;
+			if (err > 0)
+				is_strong = true;
+		}
+		return is_strong;
+	}
+	case BTF_KIND_FUNC:
+	case BTF_KIND_VAR:
+	case BTF_KIND_DATASEC:
+		d->type_states[id].order_state = ORDERED;
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t);
+static void btf_dump_emit_struct_def(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t, int lvl);
+
+static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t);
+static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t, int lvl);
+
+static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
+				  const struct btf_type *t);
+
+static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
+				      const struct btf_type *t, int lvl);
+
+/* a local view into a shared stack */
+struct id_stack {
+	const __u32 *ids;
+	int cnt;
+};
+
+static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
+				    const char *fname, int lvl);
+static void btf_dump_emit_type_chain(struct btf_dump *d,
+				     struct id_stack *decl_stack,
+				     const char *fname, int lvl);
+
+static const char *btf_dump_type_name(struct btf_dump *d, __u32 id);
+static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id);
+static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
+				 const char *orig_name);
+
+static bool btf_dump_is_blacklisted(struct btf_dump *d, __u32 id)
+{
+	const struct btf_type *t = btf__type_by_id(d->btf, id);
+
+	/* __builtin_va_list is a compiler built-in, which causes compilation
+	 * errors, when compiling w/ different compiler, then used to compile
+	 * original code (e.g., GCC to compile kernel, Clang to use generated
+	 * C header from BTF). As it is built-in, it should be already defined
+	 * properly internally in compiler.
+	 */
+	if (t->name_off == 0)
+		return false;
+	return strcmp(btf_name_of(d, t->name_off), "__builtin_va_list") == 0;
+}
+
+/*
+ * Emit C-syntax definitions of types from chains of BTF types.
+ *
+ * High-level handling of determining necessary forward declarations are handled
+ * by btf_dump_emit_type() itself, but all nitty-gritty details of emitting type
+ * declarations/definitions in C syntax  are handled by a combo of
+ * btf_dump_emit_type_decl()/btf_dump_emit_type_chain() w/ delegation to
+ * corresponding btf_dump_emit_*_{def,fwd}() functions.
+ *
+ * We also keep track of "containing struct/union type ID" to determine when
+ * we reference it from inside and thus can avoid emitting unnecessary forward
+ * declaration.
+ *
+ * This algorithm is designed in such a way, that even if some error occurs
+ * (either technical, e.g., out of memory, or logical, i.e., malformed BTF
+ * that doesn't comply to C rules completely), algorithm will try to proceed
+ * and produce as much meaningful output as possible.
+ */
+static void btf_dump_emit_type(struct btf_dump *d, __u32 id, __u32 cont_id)
+{
+	struct btf_dump_type_aux_state *tstate = &d->type_states[id];
+	bool top_level_def = cont_id == 0;
+	const struct btf_type *t;
+	__u16 kind;
+
+	if (tstate->emit_state == EMITTED)
+		return;
+
+	t = btf__type_by_id(d->btf, id);
+	kind = btf_kind(t);
+
+	if (tstate->emit_state == EMITTING) {
+		if (tstate->fwd_emitted)
+			return;
+
+		switch (kind) {
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			/*
+			 * if we are referencing a struct/union that we are
+			 * part of - then no need for fwd declaration
+			 */
+			if (id == cont_id)
+				return;
+			if (t->name_off == 0) {
+				pr_warn("anonymous struct/union loop, id:[%u]\n",
+					id);
+				return;
+			}
+			btf_dump_emit_struct_fwd(d, id, t);
+			btf_dump_printf(d, ";\n\n");
+			tstate->fwd_emitted = 1;
+			break;
+		case BTF_KIND_TYPEDEF:
+			/*
+			 * for typedef fwd_emitted means typedef definition
+			 * was emitted, but it can be used only for "weak"
+			 * references through pointer only, not for embedding
+			 */
+			if (!btf_dump_is_blacklisted(d, id)) {
+				btf_dump_emit_typedef_def(d, id, t, 0);
+				btf_dump_printf(d, ";\n\n");
+			};
+			tstate->fwd_emitted = 1;
+			break;
+		default:
+			break;
+		}
+
+		return;
+	}
+
+	switch (kind) {
+	case BTF_KIND_INT:
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_ENUM:
+		if (top_level_def) {
+			btf_dump_emit_enum_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+		}
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_PTR:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		btf_dump_emit_type(d, t->type, cont_id);
+		break;
+	case BTF_KIND_ARRAY:
+		btf_dump_emit_type(d, btf_array(t)->type, cont_id);
+		break;
+	case BTF_KIND_FWD:
+		btf_dump_emit_fwd_def(d, id, t);
+		btf_dump_printf(d, ";\n\n");
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_TYPEDEF:
+		tstate->emit_state = EMITTING;
+		btf_dump_emit_type(d, t->type, id);
+		/*
+		 * typedef can server as both definition and forward
+		 * declaration; at this stage someone depends on
+		 * typedef as a forward declaration (refers to it
+		 * through pointer), so unless we already did it,
+		 * emit typedef as a forward declaration
+		 */
+		if (!tstate->fwd_emitted && !btf_dump_is_blacklisted(d, id)) {
+			btf_dump_emit_typedef_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+		}
+		tstate->emit_state = EMITTED;
+		break;
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION:
+		tstate->emit_state = EMITTING;
+		/* if it's a top-level struct/union definition or struct/union
+		 * is anonymous, then in C we'll be emitting all fields and
+		 * their types (as opposed to just `struct X`), so we need to
+		 * make sure that all types, referenced from struct/union
+		 * members have necessary forward-declarations, where
+		 * applicable
+		 */
+		if (top_level_def || t->name_off == 0) {
+			const struct btf_member *m = btf_members(t);
+			__u16 vlen = btf_vlen(t);
+			int i, new_cont_id;
+
+			new_cont_id = t->name_off == 0 ? cont_id : id;
+			for (i = 0; i < vlen; i++, m++)
+				btf_dump_emit_type(d, m->type, new_cont_id);
+		} else if (!tstate->fwd_emitted && id != cont_id) {
+			btf_dump_emit_struct_fwd(d, id, t);
+			btf_dump_printf(d, ";\n\n");
+			tstate->fwd_emitted = 1;
+		}
+
+		if (top_level_def) {
+			btf_dump_emit_struct_def(d, id, t, 0);
+			btf_dump_printf(d, ";\n\n");
+			tstate->emit_state = EMITTED;
+		} else {
+			tstate->emit_state = NOT_EMITTED;
+		}
+		break;
+	case BTF_KIND_FUNC_PROTO: {
+		const struct btf_param *p = btf_params(t);
+		__u16 vlen = btf_vlen(t);
+		int i;
+
+		btf_dump_emit_type(d, t->type, cont_id);
+		for (i = 0; i < vlen; i++, p++)
+			btf_dump_emit_type(d, p->type, cont_id);
+
+		break;
+	}
+	default:
+		break;
+	}
+}
+
+static int btf_align_of(const struct btf *btf, __u32 id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
+	__u16 kind = btf_kind(t);
+
+	switch (kind) {
+	case BTF_KIND_INT:
+	case BTF_KIND_ENUM:
+		return min(sizeof(void *), t->size);
+	case BTF_KIND_PTR:
+		return sizeof(void *);
+	case BTF_KIND_TYPEDEF:
+	case BTF_KIND_VOLATILE:
+	case BTF_KIND_CONST:
+	case BTF_KIND_RESTRICT:
+		return btf_align_of(btf, t->type);
+	case BTF_KIND_ARRAY:
+		return btf_align_of(btf, btf_array(t)->type);
+	case BTF_KIND_STRUCT:
+	case BTF_KIND_UNION: {
+		const struct btf_member *m = btf_members(t);
+		__u16 vlen = btf_vlen(t);
+		int i, align = 1;
+
+		for (i = 0; i < vlen; i++, m++)
+			align = max(align, btf_align_of(btf, m->type));
+
+		return align;
+	}
+	default:
+		pr_warn("unsupported BTF_KIND:%u\n", btf_kind(t));
+		return 1;
+	}
+}
+
+static bool btf_is_struct_packed(const struct btf *btf, __u32 id,
+				 const struct btf_type *t)
+{
+	const struct btf_member *m;
+	int align, i, bit_sz;
+	__u16 vlen;
+
+	align = btf_align_of(btf, id);
+	/* size of a non-packed struct has to be a multiple of its alignment*/
+	if (t->size % align)
+		return true;
+
+	m = btf_members(t);
+	vlen = btf_vlen(t);
+	/* all non-bitfield fields have to be naturally aligned */
+	for (i = 0; i < vlen; i++, m++) {
+		align = btf_align_of(btf, m->type);
+		bit_sz = btf_member_bitfield_size(t, i);
+		if (bit_sz == 0 && m->offset % (8 * align) != 0)
+			return true;
+	}
+
+	/*
+	 * if original struct was marked as packed, but its layout is
+	 * naturally aligned, we'll detect that it's not packed
+	 */
+	return false;
+}
+
+static int chip_away_bits(int total, int at_most)
+{
+	return total % at_most ? : at_most;
+}
+
+static void btf_dump_emit_bit_padding(const struct btf_dump *d,
+				      int cur_off, int m_off, int m_bit_sz,
+				      int align, int lvl)
+{
+	int off_diff = m_off - cur_off;
+	int ptr_bits = sizeof(void *) * 8;
+
+	if (off_diff <= 0)
+		/* no gap */
+		return;
+	if (m_bit_sz == 0 && off_diff < align * 8)
+		/* natural padding will take care of a gap */
+		return;
+
+	while (off_diff > 0) {
+		const char *pad_type;
+		int pad_bits;
+
+		if (ptr_bits > 32 && off_diff > 32) {
+			pad_type = "long";
+			pad_bits = chip_away_bits(off_diff, ptr_bits);
+		} else if (off_diff > 16) {
+			pad_type = "int";
+			pad_bits = chip_away_bits(off_diff, 32);
+		} else if (off_diff > 8) {
+			pad_type = "short";
+			pad_bits = chip_away_bits(off_diff, 16);
+		} else {
+			pad_type = "char";
+			pad_bits = chip_away_bits(off_diff, 8);
+		}
+		btf_dump_printf(d, "\n%s%s: %d;", pfx(lvl), pad_type, pad_bits);
+		off_diff -= pad_bits;
+	}
+}
+
+static void btf_dump_emit_struct_fwd(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t)
+{
+	btf_dump_printf(d, "%s %s",
+			btf_is_struct(t) ? "struct" : "union",
+			btf_dump_type_name(d, id));
+}
+
+static void btf_dump_emit_struct_def(struct btf_dump *d,
+				     __u32 id,
+				     const struct btf_type *t,
+				     int lvl)
+{
+	const struct btf_member *m = btf_members(t);
+	bool is_struct = btf_is_struct(t);
+	int align, i, packed, off = 0;
+	__u16 vlen = btf_vlen(t);
+
+	packed = is_struct ? btf_is_struct_packed(d->btf, id, t) : 0;
+
+	btf_dump_printf(d, "%s%s%s {",
+			is_struct ? "struct" : "union",
+			t->name_off ? " " : "",
+			btf_dump_type_name(d, id));
+
+	for (i = 0; i < vlen; i++, m++) {
+		const char *fname;
+		int m_off, m_sz;
+
+		fname = btf_name_of(d, m->name_off);
+		m_sz = btf_member_bitfield_size(t, i);
+		m_off = btf_member_bit_offset(t, i);
+		align = packed ? 1 : btf_align_of(d->btf, m->type);
+
+		btf_dump_emit_bit_padding(d, off, m_off, m_sz, align, lvl + 1);
+		btf_dump_printf(d, "\n%s", pfx(lvl + 1));
+		btf_dump_emit_type_decl(d, m->type, fname, lvl + 1);
+
+		if (m_sz) {
+			btf_dump_printf(d, ": %d", m_sz);
+			off = m_off + m_sz;
+		} else {
+			m_sz = max(0, btf__resolve_size(d->btf, m->type));
+			off = m_off + m_sz * 8;
+		}
+		btf_dump_printf(d, ";");
+	}
+
+	/* pad at the end, if necessary */
+	if (is_struct) {
+		align = packed ? 1 : btf_align_of(d->btf, id);
+		btf_dump_emit_bit_padding(d, off, t->size * 8, 0, align,
+					  lvl + 1);
+	}
+
+	if (vlen)
+		btf_dump_printf(d, "\n");
+	btf_dump_printf(d, "%s}", pfx(lvl));
+	if (packed)
+		btf_dump_printf(d, " __attribute__((packed))");
+}
+
+static void btf_dump_emit_enum_fwd(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t)
+{
+	btf_dump_printf(d, "enum %s", btf_dump_type_name(d, id));
+}
+
+static void btf_dump_emit_enum_def(struct btf_dump *d, __u32 id,
+				   const struct btf_type *t,
+				   int lvl)
+{
+	const struct btf_enum *v = btf_enum(t);
+	__u16 vlen = btf_vlen(t);
+	const char *name;
+	size_t dup_cnt;
+	int i;
+
+	btf_dump_printf(d, "enum%s%s",
+			t->name_off ? " " : "",
+			btf_dump_type_name(d, id));
+
+	if (vlen) {
+		btf_dump_printf(d, " {");
+		for (i = 0; i < vlen; i++, v++) {
+			name = btf_name_of(d, v->name_off);
+			/* enumerators share namespace with typedef idents */
+			dup_cnt = btf_dump_name_dups(d, d->ident_names, name);
+			if (dup_cnt > 1) {
+				btf_dump_printf(d, "\n%s%s___%zu = %d,",
+						pfx(lvl + 1), name, dup_cnt,
+						(__s32)v->val);
+			} else {
+				btf_dump_printf(d, "\n%s%s = %d,",
+						pfx(lvl + 1), name,
+						(__s32)v->val);
+			}
+		}
+		btf_dump_printf(d, "\n%s}", pfx(lvl));
+	}
+}
+
+static void btf_dump_emit_fwd_def(struct btf_dump *d, __u32 id,
+				  const struct btf_type *t)
+{
+	const char *name = btf_dump_type_name(d, id);
+
+	if (btf_kflag(t))
+		btf_dump_printf(d, "union %s", name);
+	else
+		btf_dump_printf(d, "struct %s", name);
+}
+
+static void btf_dump_emit_typedef_def(struct btf_dump *d, __u32 id,
+				     const struct btf_type *t, int lvl)
+{
+	const char *name = btf_dump_ident_name(d, id);
+
+	/*
+	 * Old GCC versions are emitting invalid typedef for __gnuc_va_list
+	 * pointing to VOID. This generates warnings from btf_dump() and
+	 * results in uncompilable header file, so we are fixing it up here
+	 * with valid typedef into __builtin_va_list.
+	 */
+	if (t->type == 0 && strcmp(name, "__gnuc_va_list") == 0) {
+		btf_dump_printf(d, "typedef __builtin_va_list __gnuc_va_list");
+		return;
+	}
+
+	btf_dump_printf(d, "typedef ");
+	btf_dump_emit_type_decl(d, t->type, name, lvl);
+}
+
+static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
+{
+	__u32 *new_stack;
+	size_t new_cap;
+
+	if (d->decl_stack_cnt >= d->decl_stack_cap) {
+		new_cap = max(16, d->decl_stack_cap * 3 / 2);
+		new_stack = realloc(d->decl_stack,
+				    new_cap * sizeof(new_stack[0]));
+		if (!new_stack)
+			return -ENOMEM;
+		d->decl_stack = new_stack;
+		d->decl_stack_cap = new_cap;
+	}
+
+	d->decl_stack[d->decl_stack_cnt++] = id;
+
+	return 0;
+}
+
+/*
+ * Emit type declaration (e.g., field type declaration in a struct or argument
+ * declaration in function prototype) in correct C syntax.
+ *
+ * For most types it's trivial, but there are few quirky type declaration
+ * cases worth mentioning:
+ *   - function prototypes (especially nesting of function prototypes);
+ *   - arrays;
+ *   - const/volatile/restrict for pointers vs other types.
+ *
+ * For a good discussion of *PARSING* C syntax (as a human), see
+ * Peter van der Linden's "Expert C Programming: Deep C Secrets",
+ * Ch.3 "Unscrambling Declarations in C".
+ *
+ * It won't help with BTF to C conversion much, though, as it's an opposite
+ * problem. So we came up with this algorithm in reverse to van der Linden's
+ * parsing algorithm. It goes from structured BTF representation of type
+ * declaration to a valid compilable C syntax.
+ *
+ * For instance, consider this C typedef:
+ *	typedef const int * const * arr[10] arr_t;
+ * It will be represented in BTF with this chain of BTF types:
+ *	[typedef] -> [array] -> [ptr] -> [const] -> [ptr] -> [const] -> [int]
+ *
+ * Notice how [const] modifier always goes before type it modifies in BTF type
+ * graph, but in C syntax, const/volatile/restrict modifiers are written to
+ * the right of pointers, but to the left of other types. There are also other
+ * quirks, like function pointers, arrays of them, functions returning other
+ * functions, etc.
+ *
+ * We handle that by pushing all the types to a stack, until we hit "terminal"
+ * type (int/enum/struct/union/fwd). Then depending on the kind of a type on
+ * top of a stack, modifiers are handled differently. Array/function pointers
+ * have also wildly different syntax and how nesting of them are done. See
+ * code for authoritative definition.
+ *
+ * To avoid allocating new stack for each independent chain of BTF types, we
+ * share one bigger stack, with each chain working only on its own local view
+ * of a stack frame. Some care is required to "pop" stack frames after
+ * processing type declaration chain.
+ */
+static void btf_dump_emit_type_decl(struct btf_dump *d, __u32 id,
+				    const char *fname, int lvl)
+{
+	struct id_stack decl_stack;
+	const struct btf_type *t;
+	int err, stack_start;
+
+	stack_start = d->decl_stack_cnt;
+	for (;;) {
+		err = btf_dump_push_decl_stack_id(d, id);
+		if (err < 0) {
+			/*
+			 * if we don't have enough memory for entire type decl
+			 * chain, restore stack, emit warning, and try to
+			 * proceed nevertheless
+			 */
+			pr_warn("not enough memory for decl stack:%d", err);
+			d->decl_stack_cnt = stack_start;
+			return;
+		}
+
+		/* VOID */
+		if (id == 0)
+			break;
+
+		t = btf__type_by_id(d->btf, id);
+		switch (btf_kind(t)) {
+		case BTF_KIND_PTR:
+		case BTF_KIND_VOLATILE:
+		case BTF_KIND_CONST:
+		case BTF_KIND_RESTRICT:
+		case BTF_KIND_FUNC_PROTO:
+			id = t->type;
+			break;
+		case BTF_KIND_ARRAY:
+			id = btf_array(t)->type;
+			break;
+		case BTF_KIND_INT:
+		case BTF_KIND_ENUM:
+		case BTF_KIND_FWD:
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+		case BTF_KIND_TYPEDEF:
+			goto done;
+		default:
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				btf_kind(t), id);
+			goto done;
+		}
+	}
+done:
+	/*
+	 * We might be inside a chain of declarations (e.g., array of function
+	 * pointers returning anonymous (so inlined) structs, having another
+	 * array field). Each of those needs its own "stack frame" to handle
+	 * emitting of declarations. Those stack frames are non-overlapping
+	 * portions of shared btf_dump->decl_stack. To make it a bit nicer to
+	 * handle this set of nested stacks, we create a view corresponding to
+	 * our own "stack frame" and work with it as an independent stack.
+	 * We'll need to clean up after emit_type_chain() returns, though.
+	 */
+	decl_stack.ids = d->decl_stack + stack_start;
+	decl_stack.cnt = d->decl_stack_cnt - stack_start;
+	btf_dump_emit_type_chain(d, &decl_stack, fname, lvl);
+	/*
+	 * emit_type_chain() guarantees that it will pop its entire decl_stack
+	 * frame before returning. But it works with a read-only view into
+	 * decl_stack, so it doesn't actually pop anything from the
+	 * perspective of shared btf_dump->decl_stack, per se. We need to
+	 * reset decl_stack state to how it was before us to avoid it growing
+	 * all the time.
+	 */
+	d->decl_stack_cnt = stack_start;
+}
+
+static void btf_dump_emit_mods(struct btf_dump *d, struct id_stack *decl_stack)
+{
+	const struct btf_type *t;
+	__u32 id;
+
+	while (decl_stack->cnt) {
+		id = decl_stack->ids[decl_stack->cnt - 1];
+		t = btf__type_by_id(d->btf, id);
+
+		switch (btf_kind(t)) {
+		case BTF_KIND_VOLATILE:
+			btf_dump_printf(d, "volatile ");
+			break;
+		case BTF_KIND_CONST:
+			btf_dump_printf(d, "const ");
+			break;
+		case BTF_KIND_RESTRICT:
+			btf_dump_printf(d, "restrict ");
+			break;
+		default:
+			return;
+		}
+		decl_stack->cnt--;
+	}
+}
+
+static void btf_dump_emit_name(const struct btf_dump *d,
+			       const char *name, bool last_was_ptr)
+{
+	bool separate = name[0] && !last_was_ptr;
+
+	btf_dump_printf(d, "%s%s", separate ? " " : "", name);
+}
+
+static void btf_dump_emit_type_chain(struct btf_dump *d,
+				     struct id_stack *decls,
+				     const char *fname, int lvl)
+{
+	/*
+	 * last_was_ptr is used to determine if we need to separate pointer
+	 * asterisk (*) from previous part of type signature with space, so
+	 * that we get `int ***`, instead of `int * * *`. We default to true
+	 * for cases where we have single pointer in a chain. E.g., in ptr ->
+	 * func_proto case. func_proto will start a new emit_type_chain call
+	 * with just ptr, which should be emitted as (*) or (*<fname>), so we
+	 * don't want to prepend space for that last pointer.
+	 */
+	bool last_was_ptr = true;
+	const struct btf_type *t;
+	const char *name;
+	__u16 kind;
+	__u32 id;
+
+	while (decls->cnt) {
+		id = decls->ids[--decls->cnt];
+		if (id == 0) {
+			/* VOID is a special snowflake */
+			btf_dump_emit_mods(d, decls);
+			btf_dump_printf(d, "void");
+			last_was_ptr = false;
+			continue;
+		}
+
+		t = btf__type_by_id(d->btf, id);
+		kind = btf_kind(t);
+
+		switch (kind) {
+		case BTF_KIND_INT:
+			btf_dump_emit_mods(d, decls);
+			name = btf_name_of(d, t->name_off);
+			btf_dump_printf(d, "%s", name);
+			break;
+		case BTF_KIND_STRUCT:
+		case BTF_KIND_UNION:
+			btf_dump_emit_mods(d, decls);
+			/* inline anonymous struct/union */
+			if (t->name_off == 0)
+				btf_dump_emit_struct_def(d, id, t, lvl);
+			else
+				btf_dump_emit_struct_fwd(d, id, t);
+			break;
+		case BTF_KIND_ENUM:
+			btf_dump_emit_mods(d, decls);
+			/* inline anonymous enum */
+			if (t->name_off == 0)
+				btf_dump_emit_enum_def(d, id, t, lvl);
+			else
+				btf_dump_emit_enum_fwd(d, id, t);
+			break;
+		case BTF_KIND_FWD:
+			btf_dump_emit_mods(d, decls);
+			btf_dump_emit_fwd_def(d, id, t);
+			break;
+		case BTF_KIND_TYPEDEF:
+			btf_dump_emit_mods(d, decls);
+			btf_dump_printf(d, "%s", btf_dump_ident_name(d, id));
+			break;
+		case BTF_KIND_PTR:
+			btf_dump_printf(d, "%s", last_was_ptr ? "*" : " *");
+			break;
+		case BTF_KIND_VOLATILE:
+			btf_dump_printf(d, " volatile");
+			break;
+		case BTF_KIND_CONST:
+			btf_dump_printf(d, " const");
+			break;
+		case BTF_KIND_RESTRICT:
+			btf_dump_printf(d, " restrict");
+			break;
+		case BTF_KIND_ARRAY: {
+			const struct btf_array *a = btf_array(t);
+			const struct btf_type *next_t;
+			__u32 next_id;
+			bool multidim;
+			/*
+			 * GCC has a bug
+			 * (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=8354)
+			 * which causes it to emit extra const/volatile
+			 * modifiers for an array, if array's element type has
+			 * const/volatile modifiers. Clang doesn't do that.
+			 * In general, it doesn't seem very meaningful to have
+			 * a const/volatile modifier for array, so we are
+			 * going to silently skip them here.
+			 */
+			while (decls->cnt) {
+				next_id = decls->ids[decls->cnt - 1];
+				next_t = btf__type_by_id(d->btf, next_id);
+				if (btf_is_mod(next_t))
+					decls->cnt--;
+				else
+					break;
+			}
+
+			if (decls->cnt == 0) {
+				btf_dump_emit_name(d, fname, last_was_ptr);
+				btf_dump_printf(d, "[%u]", a->nelems);
+				return;
+			}
+
+			next_id = decls->ids[decls->cnt - 1];
+			next_t = btf__type_by_id(d->btf, next_id);
+			multidim = btf_is_array(next_t);
+			/* we need space if we have named non-pointer */
+			if (fname[0] && !last_was_ptr)
+				btf_dump_printf(d, " ");
+			/* no parentheses for multi-dimensional array */
+			if (!multidim)
+				btf_dump_printf(d, "(");
+			btf_dump_emit_type_chain(d, decls, fname, lvl);
+			if (!multidim)
+				btf_dump_printf(d, ")");
+			btf_dump_printf(d, "[%u]", a->nelems);
+			return;
+		}
+		case BTF_KIND_FUNC_PROTO: {
+			const struct btf_param *p = btf_params(t);
+			__u16 vlen = btf_vlen(t);
+			int i;
+
+			btf_dump_emit_mods(d, decls);
+			if (decls->cnt) {
+				btf_dump_printf(d, " (");
+				btf_dump_emit_type_chain(d, decls, fname, lvl);
+				btf_dump_printf(d, ")");
+			} else {
+				btf_dump_emit_name(d, fname, last_was_ptr);
+			}
+			btf_dump_printf(d, "(");
+			/*
+			 * Clang for BPF target generates func_proto with no
+			 * args as a func_proto with a single void arg (e.g.,
+			 * `int (*f)(void)` vs just `int (*f)()`). We are
+			 * going to pretend there are no args for such case.
+			 */
+			if (vlen == 1 && p->type == 0) {
+				btf_dump_printf(d, ")");
+				return;
+			}
+
+			for (i = 0; i < vlen; i++, p++) {
+				if (i > 0)
+					btf_dump_printf(d, ", ");
+
+				/* last arg of type void is vararg */
+				if (i == vlen - 1 && p->type == 0) {
+					btf_dump_printf(d, "...");
+					break;
+				}
+
+				name = btf_name_of(d, p->name_off);
+				btf_dump_emit_type_decl(d, p->type, name, lvl);
+			}
+
+			btf_dump_printf(d, ")");
+			return;
+		}
+		default:
+			pr_warn("unexpected type in decl chain, kind:%u, id:[%u]\n",
+				kind, id);
+			return;
+		}
+
+		last_was_ptr = kind == BTF_KIND_PTR;
+	}
+
+	btf_dump_emit_name(d, fname, last_was_ptr);
+}
+
+/* return number of duplicates (occurrences) of a given name */
+static size_t btf_dump_name_dups(struct btf_dump *d, struct hashmap *name_map,
+				 const char *orig_name)
+{
+	size_t dup_cnt = 0;
+
+	hashmap__find(name_map, orig_name, (void **)&dup_cnt);
+	dup_cnt++;
+	hashmap__set(name_map, orig_name, (void *)dup_cnt, NULL, NULL);
+
+	return dup_cnt;
+}
+
+static const char *btf_dump_resolve_name(struct btf_dump *d, __u32 id,
+					 struct hashmap *name_map)
+{
+	struct btf_dump_type_aux_state *s = &d->type_states[id];
+	const struct btf_type *t = btf__type_by_id(d->btf, id);
+	const char *orig_name = btf_name_of(d, t->name_off);
+	const char **cached_name = &d->cached_names[id];
+	size_t dup_cnt;
+
+	if (t->name_off == 0)
+		return "";
+
+	if (s->name_resolved)
+		return *cached_name ? *cached_name : orig_name;
+
+	dup_cnt = btf_dump_name_dups(d, name_map, orig_name);
+	if (dup_cnt > 1) {
+		const size_t max_len = 256;
+		char new_name[max_len];
+
+		snprintf(new_name, max_len, "%s___%zu", orig_name, dup_cnt);
+		*cached_name = strdup(new_name);
+	}
+
+	s->name_resolved = 1;
+	return *cached_name ? *cached_name : orig_name;
+}
+
+static const char *btf_dump_type_name(struct btf_dump *d, __u32 id)
+{
+	return btf_dump_resolve_name(d, id, d->type_names);
+}
+
+static const char *btf_dump_ident_name(struct btf_dump *d, __u32 id)
+{
+	return btf_dump_resolve_name(d, id, d->ident_names);
+}
diff --git a/src/contrib/libbpf/bpf/hashmap.c b/src/contrib/libbpf/bpf/hashmap.c
new file mode 100644
index 0000000..6122272
--- /dev/null
+++ b/src/contrib/libbpf/bpf/hashmap.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#include <stdint.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <linux/err.h>
+#include "hashmap.h"
+
+/* start with 4 buckets */
+#define HASHMAP_MIN_CAP_BITS 2
+
+static void hashmap_add_entry(struct hashmap_entry **pprev,
+			      struct hashmap_entry *entry)
+{
+	entry->next = *pprev;
+	*pprev = entry;
+}
+
+static void hashmap_del_entry(struct hashmap_entry **pprev,
+			      struct hashmap_entry *entry)
+{
+	*pprev = entry->next;
+	entry->next = NULL;
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+		   hashmap_equal_fn equal_fn, void *ctx)
+{
+	map->hash_fn = hash_fn;
+	map->equal_fn = equal_fn;
+	map->ctx = ctx;
+
+	map->buckets = NULL;
+	map->cap = 0;
+	map->cap_bits = 0;
+	map->sz = 0;
+}
+
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+			     hashmap_equal_fn equal_fn,
+			     void *ctx)
+{
+	struct hashmap *map = malloc(sizeof(struct hashmap));
+
+	if (!map)
+		return ERR_PTR(-ENOMEM);
+	hashmap__init(map, hash_fn, equal_fn, ctx);
+	return map;
+}
+
+void hashmap__clear(struct hashmap *map)
+{
+	free(map->buckets);
+	map->cap = map->cap_bits = map->sz = 0;
+}
+
+void hashmap__free(struct hashmap *map)
+{
+	if (!map)
+		return;
+
+	hashmap__clear(map);
+	free(map);
+}
+
+size_t hashmap__size(const struct hashmap *map)
+{
+	return map->sz;
+}
+
+size_t hashmap__capacity(const struct hashmap *map)
+{
+	return map->cap;
+}
+
+static bool hashmap_needs_to_grow(struct hashmap *map)
+{
+	/* grow if empty or more than 75% filled */
+	return (map->cap == 0) || ((map->sz + 1) * 4 / 3 > map->cap);
+}
+
+static int hashmap_grow(struct hashmap *map)
+{
+	struct hashmap_entry **new_buckets;
+	struct hashmap_entry *cur, *tmp;
+	size_t new_cap_bits, new_cap;
+	size_t h;
+	int bkt;
+
+	new_cap_bits = map->cap_bits + 1;
+	if (new_cap_bits < HASHMAP_MIN_CAP_BITS)
+		new_cap_bits = HASHMAP_MIN_CAP_BITS;
+
+	new_cap = 1UL << new_cap_bits;
+	new_buckets = calloc(new_cap, sizeof(new_buckets[0]));
+	if (!new_buckets)
+		return -ENOMEM;
+
+	hashmap__for_each_entry_safe(map, cur, tmp, bkt) {
+		h = hash_bits(map->hash_fn(cur->key, map->ctx), new_cap_bits);
+		hashmap_add_entry(&new_buckets[h], cur);
+	}
+
+	map->cap = new_cap;
+	map->cap_bits = new_cap_bits;
+	free(map->buckets);
+	map->buckets = new_buckets;
+
+	return 0;
+}
+
+static bool hashmap_find_entry(const struct hashmap *map,
+			       const void *key, size_t hash,
+			       struct hashmap_entry ***pprev,
+			       struct hashmap_entry **entry)
+{
+	struct hashmap_entry *cur, **prev_ptr;
+
+	if (!map->buckets)
+		return false;
+
+	for (prev_ptr = &map->buckets[hash], cur = *prev_ptr;
+	     cur;
+	     prev_ptr = &cur->next, cur = cur->next) {
+		if (map->equal_fn(cur->key, key, map->ctx)) {
+			if (pprev)
+				*pprev = prev_ptr;
+			*entry = cur;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+int hashmap__insert(struct hashmap *map, const void *key, void *value,
+		    enum hashmap_insert_strategy strategy,
+		    const void **old_key, void **old_value)
+{
+	struct hashmap_entry *entry;
+	size_t h;
+	int err;
+
+	if (old_key)
+		*old_key = NULL;
+	if (old_value)
+		*old_value = NULL;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (strategy != HASHMAP_APPEND &&
+	    hashmap_find_entry(map, key, h, NULL, &entry)) {
+		if (old_key)
+			*old_key = entry->key;
+		if (old_value)
+			*old_value = entry->value;
+
+		if (strategy == HASHMAP_SET || strategy == HASHMAP_UPDATE) {
+			entry->key = key;
+			entry->value = value;
+			return 0;
+		} else if (strategy == HASHMAP_ADD) {
+			return -EEXIST;
+		}
+	}
+
+	if (strategy == HASHMAP_UPDATE)
+		return -ENOENT;
+
+	if (hashmap_needs_to_grow(map)) {
+		err = hashmap_grow(map);
+		if (err)
+			return err;
+		h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	}
+
+	entry = malloc(sizeof(struct hashmap_entry));
+	if (!entry)
+		return -ENOMEM;
+
+	entry->key = key;
+	entry->value = value;
+	hashmap_add_entry(&map->buckets[h], entry);
+	map->sz++;
+
+	return 0;
+}
+
+bool hashmap__find(const struct hashmap *map, const void *key, void **value)
+{
+	struct hashmap_entry *entry;
+	size_t h;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (!hashmap_find_entry(map, key, h, NULL, &entry))
+		return false;
+
+	if (value)
+		*value = entry->value;
+	return true;
+}
+
+bool hashmap__delete(struct hashmap *map, const void *key,
+		     const void **old_key, void **old_value)
+{
+	struct hashmap_entry **pprev, *entry;
+	size_t h;
+
+	h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits);
+	if (!hashmap_find_entry(map, key, h, &pprev, &entry))
+		return false;
+
+	if (old_key)
+		*old_key = entry->key;
+	if (old_value)
+		*old_value = entry->value;
+
+	hashmap_del_entry(pprev, entry);
+	free(entry);
+	map->sz--;
+
+	return true;
+}
+
diff --git a/src/contrib/libbpf/bpf/hashmap.h b/src/contrib/libbpf/bpf/hashmap.h
new file mode 100644
index 0000000..bae8879
--- /dev/null
+++ b/src/contrib/libbpf/bpf/hashmap.h
@@ -0,0 +1,178 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Generic non-thread safe hash map implementation.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+#ifndef __LIBBPF_HASHMAP_H
+#define __LIBBPF_HASHMAP_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#ifdef __GLIBC__
+#include <bits/wordsize.h>
+#else
+#include <bits/reg.h>
+#endif
+#include "libbpf_internal.h"
+
+static inline size_t hash_bits(size_t h, int bits)
+{
+	/* shuffle bits and return requested number of upper bits */
+	return (h * 11400714819323198485llu) >> (__WORDSIZE - bits);
+}
+
+typedef size_t (*hashmap_hash_fn)(const void *key, void *ctx);
+typedef bool (*hashmap_equal_fn)(const void *key1, const void *key2, void *ctx);
+
+struct hashmap_entry {
+	const void *key;
+	void *value;
+	struct hashmap_entry *next;
+};
+
+struct hashmap {
+	hashmap_hash_fn hash_fn;
+	hashmap_equal_fn equal_fn;
+	void *ctx;
+
+	struct hashmap_entry **buckets;
+	size_t cap;
+	size_t cap_bits;
+	size_t sz;
+};
+
+#define HASHMAP_INIT(hash_fn, equal_fn, ctx) {	\
+	.hash_fn = (hash_fn),			\
+	.equal_fn = (equal_fn),			\
+	.ctx = (ctx),				\
+	.buckets = NULL,			\
+	.cap = 0,				\
+	.cap_bits = 0,				\
+	.sz = 0,				\
+}
+
+void hashmap__init(struct hashmap *map, hashmap_hash_fn hash_fn,
+		   hashmap_equal_fn equal_fn, void *ctx);
+struct hashmap *hashmap__new(hashmap_hash_fn hash_fn,
+			     hashmap_equal_fn equal_fn,
+			     void *ctx);
+void hashmap__clear(struct hashmap *map);
+void hashmap__free(struct hashmap *map);
+
+size_t hashmap__size(const struct hashmap *map);
+size_t hashmap__capacity(const struct hashmap *map);
+
+/*
+ * Hashmap insertion strategy:
+ * - HASHMAP_ADD - only add key/value if key doesn't exist yet;
+ * - HASHMAP_SET - add key/value pair if key doesn't exist yet; otherwise,
+ *   update value;
+ * - HASHMAP_UPDATE - update value, if key already exists; otherwise, do
+ *   nothing and return -ENOENT;
+ * - HASHMAP_APPEND - always add key/value pair, even if key already exists.
+ *   This turns hashmap into a multimap by allowing multiple values to be
+ *   associated with the same key. Most useful read API for such hashmap is
+ *   hashmap__for_each_key_entry() iteration. If hashmap__find() is still
+ *   used, it will return last inserted key/value entry (first in a bucket
+ *   chain).
+ */
+enum hashmap_insert_strategy {
+	HASHMAP_ADD,
+	HASHMAP_SET,
+	HASHMAP_UPDATE,
+	HASHMAP_APPEND,
+};
+
+/*
+ * hashmap__insert() adds key/value entry w/ various semantics, depending on
+ * provided strategy value. If a given key/value pair replaced already
+ * existing key/value pair, both old key and old value will be returned
+ * through old_key and old_value to allow calling code do proper memory
+ * management.
+ */
+int hashmap__insert(struct hashmap *map, const void *key, void *value,
+		    enum hashmap_insert_strategy strategy,
+		    const void **old_key, void **old_value);
+
+static inline int hashmap__add(struct hashmap *map,
+			       const void *key, void *value)
+{
+	return hashmap__insert(map, key, value, HASHMAP_ADD, NULL, NULL);
+}
+
+static inline int hashmap__set(struct hashmap *map,
+			       const void *key, void *value,
+			       const void **old_key, void **old_value)
+{
+	return hashmap__insert(map, key, value, HASHMAP_SET,
+			       old_key, old_value);
+}
+
+static inline int hashmap__update(struct hashmap *map,
+				  const void *key, void *value,
+				  const void **old_key, void **old_value)
+{
+	return hashmap__insert(map, key, value, HASHMAP_UPDATE,
+			       old_key, old_value);
+}
+
+static inline int hashmap__append(struct hashmap *map,
+				  const void *key, void *value)
+{
+	return hashmap__insert(map, key, value, HASHMAP_APPEND, NULL, NULL);
+}
+
+bool hashmap__delete(struct hashmap *map, const void *key,
+		     const void **old_key, void **old_value);
+
+bool hashmap__find(const struct hashmap *map, const void *key, void **value);
+
+/*
+ * hashmap__for_each_entry - iterate over all entries in hashmap
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry(map, cur, bkt)				    \
+	for (bkt = 0; bkt < map->cap; bkt++)				    \
+		for (cur = map->buckets[bkt]; cur; cur = cur->next)
+
+/*
+ * hashmap__for_each_entry_safe - iterate over all entries in hashmap, safe
+ * against removals
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @tmp: struct hashmap_entry * used as a temporary next cursor storage
+ * @bkt: integer used as a bucket loop cursor
+ */
+#define hashmap__for_each_entry_safe(map, cur, tmp, bkt)		    \
+	for (bkt = 0; bkt < map->cap; bkt++)				    \
+		for (cur = map->buckets[bkt];				    \
+		     cur && ({tmp = cur->next; true; });		    \
+		     cur = tmp)
+
+/*
+ * hashmap__for_each_key_entry - iterate over entries associated with given key
+ * @map: hashmap to iterate
+ * @cur: struct hashmap_entry * used as a loop cursor
+ * @key: key to iterate entries for
+ */
+#define hashmap__for_each_key_entry(map, cur, _key)			    \
+	for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\
+					     map->cap_bits);		    \
+		     map->buckets ? map->buckets[bkt] : NULL; });	    \
+	     cur;							    \
+	     cur = cur->next)						    \
+		if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#define hashmap__for_each_key_entry_safe(map, cur, tmp, _key)		    \
+	for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\
+					     map->cap_bits);		    \
+		     cur = map->buckets ? map->buckets[bkt] : NULL; });	    \
+	     cur && ({ tmp = cur->next; true; });			    \
+	     cur = tmp)							    \
+		if (map->equal_fn(cur->key, (_key), map->ctx))
+
+#endif /* __LIBBPF_HASHMAP_H */
diff --git a/src/contrib/libbpf/bpf/libbpf.c b/src/contrib/libbpf/bpf/libbpf.c
new file mode 100644
index 0000000..29d8d03
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf.c
@@ -0,0 +1,6581 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Common eBPF ELF object loading operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ * Copyright (C) 2019 Isovalent, Inc.
+ */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdarg.h>
+#include <libgen.h>
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+#include <endian.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <asm/unistd.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/bpf.h>
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/list.h>
+#include <linux/limits.h>
+#include <linux/perf_event.h>
+#include <linux/ring_buffer.h>
+#include <linux/version.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/vfs.h>
+#include <sys/utsname.h>
+#include <libelf.h>
+#include <gelf.h>
+
+#include "libbpf.h"
+#include "bpf.h"
+#include "btf.h"
+#include "str_error.h"
+#include "libbpf_internal.h"
+#include "hashmap.h"
+
+#ifndef EM_BPF
+#define EM_BPF 247
+#endif
+
+#ifndef BPF_FS_MAGIC
+#define BPF_FS_MAGIC		0xcafe4a11
+#endif
+
+/* vsprintf() in __base_pr() uses nonliteral format string. It may break
+ * compilation if user enables corresponding warning. Disable it explicitly.
+ */
+#pragma GCC diagnostic ignored "-Wformat-nonliteral"
+
+#define __printf(a, b)	__attribute__((format(printf, a, b)))
+
+static int __base_pr(enum libbpf_print_level level, const char *format,
+		     va_list args)
+{
+	if (level == LIBBPF_DEBUG)
+		return 0;
+
+	return vfprintf(stderr, format, args);
+}
+
+static libbpf_print_fn_t __libbpf_pr = __base_pr;
+
+libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn)
+{
+	libbpf_print_fn_t old_print_fn = __libbpf_pr;
+
+	__libbpf_pr = fn;
+	return old_print_fn;
+}
+
+__printf(2, 3)
+void libbpf_print(enum libbpf_print_level level, const char *format, ...)
+{
+	va_list args;
+
+	if (!__libbpf_pr)
+		return;
+
+	va_start(args, format);
+	__libbpf_pr(level, format, args);
+	va_end(args);
+}
+
+#define STRERR_BUFSIZE  128
+
+#define CHECK_ERR(action, err, out) do {	\
+	err = action;			\
+	if (err)			\
+		goto out;		\
+} while (0)
+
+
+/* Copied from tools/perf/util/util.h */
+#ifndef zfree
+# define zfree(ptr) ({ free(*ptr); *ptr = NULL; })
+#endif
+
+#ifndef zclose
+# define zclose(fd) ({			\
+	int ___err = 0;			\
+	if ((fd) >= 0)			\
+		___err = close((fd));	\
+	fd = -1;			\
+	___err; })
+#endif
+
+#ifdef HAVE_LIBELF_MMAP_SUPPORT
+# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
+#else
+# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
+#endif
+
+static inline __u64 ptr_to_u64(const void *ptr)
+{
+	return (__u64) (unsigned long) ptr;
+}
+
+struct bpf_capabilities {
+	/* v4.14: kernel support for program & map names. */
+	__u32 name:1;
+	/* v5.2: kernel support for global data sections. */
+	__u32 global_data:1;
+	/* BTF_KIND_FUNC and BTF_KIND_FUNC_PROTO support */
+	__u32 btf_func:1;
+	/* BTF_KIND_VAR and BTF_KIND_DATASEC support */
+	__u32 btf_datasec:1;
+	/* BPF_F_MMAPABLE is supported for arrays */
+	__u32 array_mmap:1;
+};
+
+/*
+ * bpf_prog should be a better name but it has been used in
+ * linux/filter.h.
+ */
+struct bpf_program {
+	/* Index in elf obj file, for relocation use. */
+	int idx;
+	char *name;
+	int prog_ifindex;
+	char *section_name;
+	/* section_name with / replaced by _; makes recursive pinning
+	 * in bpf_object__pin_programs easier
+	 */
+	char *pin_name;
+	struct bpf_insn *insns;
+	size_t insns_cnt, main_prog_cnt;
+	enum bpf_prog_type type;
+
+	struct reloc_desc {
+		enum {
+			RELO_LD64,
+			RELO_CALL,
+			RELO_DATA,
+		} type;
+		int insn_idx;
+		int map_idx;
+		int sym_off;
+	} *reloc_desc;
+	int nr_reloc;
+	int log_level;
+
+	struct {
+		int nr;
+		int *fds;
+	} instances;
+	bpf_program_prep_t preprocessor;
+
+	struct bpf_object *obj;
+	void *priv;
+	bpf_program_clear_priv_t clear_priv;
+
+	enum bpf_attach_type expected_attach_type;
+	__u32 attach_btf_id;
+	__u32 attach_prog_fd;
+	void *func_info;
+	__u32 func_info_rec_size;
+	__u32 func_info_cnt;
+
+	struct bpf_capabilities *caps;
+
+	void *line_info;
+	__u32 line_info_rec_size;
+	__u32 line_info_cnt;
+	__u32 prog_flags;
+};
+
+enum libbpf_map_type {
+	LIBBPF_MAP_UNSPEC,
+	LIBBPF_MAP_DATA,
+	LIBBPF_MAP_BSS,
+	LIBBPF_MAP_RODATA,
+};
+
+static const char * const libbpf_type_to_btf_name[] = {
+	[LIBBPF_MAP_DATA]	= ".data",
+	[LIBBPF_MAP_BSS]	= ".bss",
+	[LIBBPF_MAP_RODATA]	= ".rodata",
+};
+
+struct bpf_map {
+	int fd;
+	char *name;
+	int sec_idx;
+	size_t sec_offset;
+	int map_ifindex;
+	int inner_map_fd;
+	struct bpf_map_def def;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+	void *priv;
+	bpf_map_clear_priv_t clear_priv;
+	enum libbpf_map_type libbpf_type;
+	char *pin_path;
+	bool pinned;
+	bool reused;
+};
+
+struct bpf_secdata {
+	void *rodata;
+	void *data;
+};
+
+static LIST_HEAD(bpf_objects_list);
+
+struct bpf_object {
+	char name[BPF_OBJ_NAME_LEN];
+	char license[64];
+	__u32 kern_version;
+
+	struct bpf_program *programs;
+	size_t nr_programs;
+	struct bpf_map *maps;
+	size_t nr_maps;
+	size_t maps_cap;
+	struct bpf_secdata sections;
+
+	bool loaded;
+	bool has_pseudo_calls;
+	bool relaxed_core_relocs;
+
+	/*
+	 * Information when doing elf related work. Only valid if fd
+	 * is valid.
+	 */
+	struct {
+		int fd;
+		const void *obj_buf;
+		size_t obj_buf_sz;
+		Elf *elf;
+		GElf_Ehdr ehdr;
+		Elf_Data *symbols;
+		Elf_Data *data;
+		Elf_Data *rodata;
+		Elf_Data *bss;
+		size_t strtabidx;
+		struct {
+			GElf_Shdr shdr;
+			Elf_Data *data;
+		} *reloc_sects;
+		int nr_reloc_sects;
+		int maps_shndx;
+		int btf_maps_shndx;
+		int text_shndx;
+		int data_shndx;
+		int rodata_shndx;
+		int bss_shndx;
+	} efile;
+	/*
+	 * All loaded bpf_object is linked in a list, which is
+	 * hidden to caller. bpf_objects__<func> handlers deal with
+	 * all objects.
+	 */
+	struct list_head list;
+
+	struct btf *btf;
+	struct btf_ext *btf_ext;
+
+	void *priv;
+	bpf_object_clear_priv_t clear_priv;
+
+	struct bpf_capabilities caps;
+
+	char path[];
+};
+#define obj_elf_valid(o)	((o)->efile.elf)
+
+void bpf_program__unload(struct bpf_program *prog)
+{
+	int i;
+
+	if (!prog)
+		return;
+
+	/*
+	 * If the object is opened but the program was never loaded,
+	 * it is possible that prog->instances.nr == -1.
+	 */
+	if (prog->instances.nr > 0) {
+		for (i = 0; i < prog->instances.nr; i++)
+			zclose(prog->instances.fds[i]);
+	} else if (prog->instances.nr != -1) {
+		pr_warn("Internal error: instances.nr is %d\n",
+			prog->instances.nr);
+	}
+
+	prog->instances.nr = -1;
+	zfree(&prog->instances.fds);
+
+	zfree(&prog->func_info);
+	zfree(&prog->line_info);
+}
+
+static void bpf_program__exit(struct bpf_program *prog)
+{
+	if (!prog)
+		return;
+
+	if (prog->clear_priv)
+		prog->clear_priv(prog, prog->priv);
+
+	prog->priv = NULL;
+	prog->clear_priv = NULL;
+
+	bpf_program__unload(prog);
+	zfree(&prog->name);
+	zfree(&prog->section_name);
+	zfree(&prog->pin_name);
+	zfree(&prog->insns);
+	zfree(&prog->reloc_desc);
+
+	prog->nr_reloc = 0;
+	prog->insns_cnt = 0;
+	prog->idx = -1;
+}
+
+static char *__bpf_program__pin_name(struct bpf_program *prog)
+{
+	char *name, *p;
+
+	name = p = strdup(prog->section_name);
+	while ((p = strchr(p, '/')))
+		*p = '_';
+
+	return name;
+}
+
+static int
+bpf_program__init(void *data, size_t size, char *section_name, int idx,
+		  struct bpf_program *prog)
+{
+	const size_t bpf_insn_sz = sizeof(struct bpf_insn);
+
+	if (size == 0 || size % bpf_insn_sz) {
+		pr_warn("corrupted section '%s', size: %zu\n",
+			section_name, size);
+		return -EINVAL;
+	}
+
+	memset(prog, 0, sizeof(*prog));
+
+	prog->section_name = strdup(section_name);
+	if (!prog->section_name) {
+		pr_warn("failed to alloc name for prog under section(%d) %s\n",
+			idx, section_name);
+		goto errout;
+	}
+
+	prog->pin_name = __bpf_program__pin_name(prog);
+	if (!prog->pin_name) {
+		pr_warn("failed to alloc pin name for prog under section(%d) %s\n",
+			idx, section_name);
+		goto errout;
+	}
+
+	prog->insns = malloc(size);
+	if (!prog->insns) {
+		pr_warn("failed to alloc insns for prog under section %s\n",
+			section_name);
+		goto errout;
+	}
+	prog->insns_cnt = size / bpf_insn_sz;
+	memcpy(prog->insns, data, size);
+	prog->idx = idx;
+	prog->instances.fds = NULL;
+	prog->instances.nr = -1;
+	prog->type = BPF_PROG_TYPE_UNSPEC;
+
+	return 0;
+errout:
+	bpf_program__exit(prog);
+	return -ENOMEM;
+}
+
+static int
+bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
+			char *section_name, int idx)
+{
+	struct bpf_program prog, *progs;
+	int nr_progs, err;
+
+	err = bpf_program__init(data, size, section_name, idx, &prog);
+	if (err)
+		return err;
+
+	prog.caps = &obj->caps;
+	progs = obj->programs;
+	nr_progs = obj->nr_programs;
+
+	progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
+	if (!progs) {
+		/*
+		 * In this case the original obj->programs
+		 * is still valid, so don't need special treat for
+		 * bpf_close_object().
+		 */
+		pr_warn("failed to alloc a new program under section '%s'\n",
+			section_name);
+		bpf_program__exit(&prog);
+		return -ENOMEM;
+	}
+
+	pr_debug("found program %s\n", prog.section_name);
+	obj->programs = progs;
+	obj->nr_programs = nr_progs + 1;
+	prog.obj = obj;
+	progs[nr_progs] = prog;
+	return 0;
+}
+
+static int
+bpf_object__init_prog_names(struct bpf_object *obj)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	struct bpf_program *prog;
+	size_t pi, si;
+
+	for (pi = 0; pi < obj->nr_programs; pi++) {
+		const char *name = NULL;
+
+		prog = &obj->programs[pi];
+
+		for (si = 0; si < symbols->d_size / sizeof(GElf_Sym) && !name;
+		     si++) {
+			GElf_Sym sym;
+
+			if (!gelf_getsym(symbols, si, &sym))
+				continue;
+			if (sym.st_shndx != prog->idx)
+				continue;
+			if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL)
+				continue;
+
+			name = elf_strptr(obj->efile.elf,
+					  obj->efile.strtabidx,
+					  sym.st_name);
+			if (!name) {
+				pr_warn("failed to get sym name string for prog %s\n",
+					prog->section_name);
+				return -LIBBPF_ERRNO__LIBELF;
+			}
+		}
+
+		if (!name && prog->idx == obj->efile.text_shndx)
+			name = ".text";
+
+		if (!name) {
+			pr_warn("failed to find sym for prog %s\n",
+				prog->section_name);
+			return -EINVAL;
+		}
+
+		prog->name = strdup(name);
+		if (!prog->name) {
+			pr_warn("failed to allocate memory for prog sym %s\n",
+				name);
+			return -ENOMEM;
+		}
+	}
+
+	return 0;
+}
+
+static __u32 get_kernel_version(void)
+{
+	__u32 major, minor, patch;
+	struct utsname info;
+
+	uname(&info);
+	if (sscanf(info.release, "%u.%u.%u", &major, &minor, &patch) != 3)
+		return 0;
+	return KERNEL_VERSION(major, minor, patch);
+}
+
+static struct bpf_object *bpf_object__new(const char *path,
+					  const void *obj_buf,
+					  size_t obj_buf_sz,
+					  const char *obj_name)
+{
+	struct bpf_object *obj;
+	char *end;
+
+	obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1);
+	if (!obj) {
+		pr_warn("alloc memory failed for %s\n", path);
+		return ERR_PTR(-ENOMEM);
+	}
+
+	strcpy(obj->path, path);
+	if (obj_name) {
+		strncpy(obj->name, obj_name, sizeof(obj->name) - 1);
+		obj->name[sizeof(obj->name) - 1] = 0;
+	} else {
+		/* Using basename() GNU version which doesn't modify arg. */
+		strncpy(obj->name, basename((void *)path),
+			sizeof(obj->name) - 1);
+		end = strchr(obj->name, '.');
+		if (end)
+			*end = 0;
+	}
+
+	obj->efile.fd = -1;
+	/*
+	 * Caller of this function should also call
+	 * bpf_object__elf_finish() after data collection to return
+	 * obj_buf to user. If not, we should duplicate the buffer to
+	 * avoid user freeing them before elf finish.
+	 */
+	obj->efile.obj_buf = obj_buf;
+	obj->efile.obj_buf_sz = obj_buf_sz;
+	obj->efile.maps_shndx = -1;
+	obj->efile.btf_maps_shndx = -1;
+	obj->efile.data_shndx = -1;
+	obj->efile.rodata_shndx = -1;
+	obj->efile.bss_shndx = -1;
+
+	obj->kern_version = get_kernel_version();
+	obj->loaded = false;
+
+	INIT_LIST_HEAD(&obj->list);
+	list_add(&obj->list, &bpf_objects_list);
+	return obj;
+}
+
+static void bpf_object__elf_finish(struct bpf_object *obj)
+{
+	if (!obj_elf_valid(obj))
+		return;
+
+	if (obj->efile.elf) {
+		elf_end(obj->efile.elf);
+		obj->efile.elf = NULL;
+	}
+	obj->efile.symbols = NULL;
+	obj->efile.data = NULL;
+	obj->efile.rodata = NULL;
+	obj->efile.bss = NULL;
+
+	zfree(&obj->efile.reloc_sects);
+	obj->efile.nr_reloc_sects = 0;
+	zclose(obj->efile.fd);
+	obj->efile.obj_buf = NULL;
+	obj->efile.obj_buf_sz = 0;
+}
+
+static int bpf_object__elf_init(struct bpf_object *obj)
+{
+	int err = 0;
+	GElf_Ehdr *ep;
+
+	if (obj_elf_valid(obj)) {
+		pr_warn("elf init: internal error\n");
+		return -LIBBPF_ERRNO__LIBELF;
+	}
+
+	if (obj->efile.obj_buf_sz > 0) {
+		/*
+		 * obj_buf should have been validated by
+		 * bpf_object__open_buffer().
+		 */
+		obj->efile.elf = elf_memory((char *)obj->efile.obj_buf,
+					    obj->efile.obj_buf_sz);
+	} else {
+		obj->efile.fd = open(obj->path, O_RDONLY);
+		if (obj->efile.fd < 0) {
+			char errmsg[STRERR_BUFSIZE], *cp;
+
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("failed to open %s: %s\n", obj->path, cp);
+			return err;
+		}
+
+		obj->efile.elf = elf_begin(obj->efile.fd,
+					   LIBBPF_ELF_C_READ_MMAP, NULL);
+	}
+
+	if (!obj->efile.elf) {
+		pr_warn("failed to open %s as ELF file\n", obj->path);
+		err = -LIBBPF_ERRNO__LIBELF;
+		goto errout;
+	}
+
+	if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) {
+		pr_warn("failed to get EHDR from %s\n", obj->path);
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+	ep = &obj->efile.ehdr;
+
+	/* Old LLVM set e_machine to EM_NONE */
+	if (ep->e_type != ET_REL ||
+	    (ep->e_machine && ep->e_machine != EM_BPF)) {
+		pr_warn("%s is not an eBPF object file\n", obj->path);
+		err = -LIBBPF_ERRNO__FORMAT;
+		goto errout;
+	}
+
+	return 0;
+errout:
+	bpf_object__elf_finish(obj);
+	return err;
+}
+
+static int bpf_object__check_endianness(struct bpf_object *obj)
+{
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2LSB)
+		return 0;
+#elif __BYTE_ORDER == __BIG_ENDIAN
+	if (obj->efile.ehdr.e_ident[EI_DATA] == ELFDATA2MSB)
+		return 0;
+#else
+# error "Unrecognized __BYTE_ORDER__"
+#endif
+	pr_warn("endianness mismatch.\n");
+	return -LIBBPF_ERRNO__ENDIAN;
+}
+
+static int
+bpf_object__init_license(struct bpf_object *obj, void *data, size_t size)
+{
+	memcpy(obj->license, data, min(size, sizeof(obj->license) - 1));
+	pr_debug("license of %s is %s\n", obj->path, obj->license);
+	return 0;
+}
+
+static int
+bpf_object__init_kversion(struct bpf_object *obj, void *data, size_t size)
+{
+	__u32 kver;
+
+	if (size != sizeof(kver)) {
+		pr_warn("invalid kver section in %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	memcpy(&kver, data, sizeof(kver));
+	obj->kern_version = kver;
+	pr_debug("kernel version of %s is %x\n", obj->path, obj->kern_version);
+	return 0;
+}
+
+static int compare_bpf_map(const void *_a, const void *_b)
+{
+	const struct bpf_map *a = _a;
+	const struct bpf_map *b = _b;
+
+	if (a->sec_idx != b->sec_idx)
+		return a->sec_idx - b->sec_idx;
+	return a->sec_offset - b->sec_offset;
+}
+
+static bool bpf_map_type__is_map_in_map(enum bpf_map_type type)
+{
+	if (type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+	    type == BPF_MAP_TYPE_HASH_OF_MAPS)
+		return true;
+	return false;
+}
+
+static int bpf_object_search_section_size(const struct bpf_object *obj,
+					  const char *name, size_t *d_size)
+{
+	const GElf_Ehdr *ep = &obj->efile.ehdr;
+	Elf *elf = obj->efile.elf;
+	Elf_Scn *scn = NULL;
+	int idx = 0;
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		const char *sec_name;
+		Elf_Data *data;
+		GElf_Shdr sh;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
+			return -EIO;
+		}
+
+		sec_name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
+		if (!sec_name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
+			return -EIO;
+		}
+
+		if (strcmp(name, sec_name))
+			continue;
+
+		data = elf_getdata(scn, 0);
+		if (!data) {
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
+			return -EIO;
+		}
+
+		*d_size = data->d_size;
+		return 0;
+	}
+
+	return -ENOENT;
+}
+
+int bpf_object__section_size(const struct bpf_object *obj, const char *name,
+			     __u32 *size)
+{
+	int ret = -ENOENT;
+	size_t d_size;
+
+	*size = 0;
+	if (!name) {
+		return -EINVAL;
+	} else if (!strcmp(name, ".data")) {
+		if (obj->efile.data)
+			*size = obj->efile.data->d_size;
+	} else if (!strcmp(name, ".bss")) {
+		if (obj->efile.bss)
+			*size = obj->efile.bss->d_size;
+	} else if (!strcmp(name, ".rodata")) {
+		if (obj->efile.rodata)
+			*size = obj->efile.rodata->d_size;
+	} else {
+		ret = bpf_object_search_section_size(obj, name, &d_size);
+		if (!ret)
+			*size = d_size;
+	}
+
+	return *size ? 0 : ret;
+}
+
+int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
+				__u32 *off)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	const char *sname;
+	size_t si;
+
+	if (!name || !off)
+		return -EINVAL;
+
+	for (si = 0; si < symbols->d_size / sizeof(GElf_Sym); si++) {
+		GElf_Sym sym;
+
+		if (!gelf_getsym(symbols, si, &sym))
+			continue;
+		if (GELF_ST_BIND(sym.st_info) != STB_GLOBAL ||
+		    GELF_ST_TYPE(sym.st_info) != STT_OBJECT)
+			continue;
+
+		sname = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				   sym.st_name);
+		if (!sname) {
+			pr_warn("failed to get sym name string for var %s\n",
+				name);
+			return -EIO;
+		}
+		if (strcmp(name, sname) == 0) {
+			*off = sym.st_value;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
+{
+	struct bpf_map *new_maps;
+	size_t new_cap;
+	int i;
+
+	if (obj->nr_maps < obj->maps_cap)
+		return &obj->maps[obj->nr_maps++];
+
+	new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
+	new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
+	if (!new_maps) {
+		pr_warn("alloc maps for object failed\n");
+		return ERR_PTR(-ENOMEM);
+	}
+
+	obj->maps_cap = new_cap;
+	obj->maps = new_maps;
+
+	/* zero out new maps */
+	memset(obj->maps + obj->nr_maps, 0,
+	       (obj->maps_cap - obj->nr_maps) * sizeof(*obj->maps));
+	/*
+	 * fill all fd with -1 so won't close incorrect fd (fd=0 is stdin)
+	 * when failure (zclose won't close negative fd)).
+	 */
+	for (i = obj->nr_maps; i < obj->maps_cap; i++) {
+		obj->maps[i].fd = -1;
+		obj->maps[i].inner_map_fd = -1;
+	}
+
+	return &obj->maps[obj->nr_maps++];
+}
+
+static int
+bpf_object__init_internal_map(struct bpf_object *obj, enum libbpf_map_type type,
+			      int sec_idx, Elf_Data *data, void **data_buff)
+{
+	char map_name[BPF_OBJ_NAME_LEN];
+	struct bpf_map_def *def;
+	struct bpf_map *map;
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+
+	map->libbpf_type = type;
+	map->sec_idx = sec_idx;
+	map->sec_offset = 0;
+	snprintf(map_name, sizeof(map_name), "%.8s%.7s", obj->name,
+		 libbpf_type_to_btf_name[type]);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("failed to alloc map name\n");
+		return -ENOMEM;
+	}
+
+	def = &map->def;
+	def->type = BPF_MAP_TYPE_ARRAY;
+	def->key_size = sizeof(int);
+	def->value_size = data->d_size;
+	def->max_entries = 1;
+	def->map_flags = type == LIBBPF_MAP_RODATA ? BPF_F_RDONLY_PROG : 0;
+	if (obj->caps.array_mmap)
+		def->map_flags |= BPF_F_MMAPABLE;
+
+	pr_debug("map '%s' (global data): at sec_idx %d, offset %zu, flags %x.\n",
+		 map_name, map->sec_idx, map->sec_offset, def->map_flags);
+
+	if (data_buff) {
+		*data_buff = malloc(data->d_size);
+		if (!*data_buff) {
+			zfree(&map->name);
+			pr_warn("failed to alloc map content buffer\n");
+			return -ENOMEM;
+		}
+		memcpy(*data_buff, data->d_buf, data->d_size);
+	}
+
+	pr_debug("map %td is \"%s\"\n", map - obj->maps, map->name);
+	return 0;
+}
+
+static int bpf_object__init_global_data_maps(struct bpf_object *obj)
+{
+	int err;
+
+	if (!obj->caps.global_data)
+		return 0;
+	/*
+	 * Populate obj->maps with libbpf internal maps.
+	 */
+	if (obj->efile.data_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_DATA,
+						    obj->efile.data_shndx,
+						    obj->efile.data,
+						    &obj->sections.data);
+		if (err)
+			return err;
+	}
+	if (obj->efile.rodata_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_RODATA,
+						    obj->efile.rodata_shndx,
+						    obj->efile.rodata,
+						    &obj->sections.rodata);
+		if (err)
+			return err;
+	}
+	if (obj->efile.bss_shndx >= 0) {
+		err = bpf_object__init_internal_map(obj, LIBBPF_MAP_BSS,
+						    obj->efile.bss_shndx,
+						    obj->efile.bss, NULL);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__init_user_maps(struct bpf_object *obj, bool strict)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	int i, map_def_sz = 0, nr_maps = 0, nr_syms;
+	Elf_Data *data = NULL;
+	Elf_Scn *scn;
+
+	if (obj->efile.maps_shndx < 0)
+		return 0;
+
+	if (!symbols)
+		return -EINVAL;
+
+	scn = elf_getscn(obj->efile.elf, obj->efile.maps_shndx);
+	if (scn)
+		data = elf_getdata(scn, NULL);
+	if (!scn || !data) {
+		pr_warn("failed to get Elf_Data from map section %d\n",
+			obj->efile.maps_shndx);
+		return -EINVAL;
+	}
+
+	/*
+	 * Count number of maps. Each map has a name.
+	 * Array of maps is not supported: only the first element is
+	 * considered.
+	 *
+	 * TODO: Detect array of map and report error.
+	 */
+	nr_syms = symbols->d_size / sizeof(GElf_Sym);
+	for (i = 0; i < nr_syms; i++) {
+		GElf_Sym sym;
+
+		if (!gelf_getsym(symbols, i, &sym))
+			continue;
+		if (sym.st_shndx != obj->efile.maps_shndx)
+			continue;
+		nr_maps++;
+	}
+	/* Assume equally sized map definitions */
+	pr_debug("maps in %s: %d maps in %zd bytes\n",
+		 obj->path, nr_maps, data->d_size);
+
+	if (!data->d_size || nr_maps == 0 || (data->d_size % nr_maps) != 0) {
+		pr_warn("unable to determine map definition size section %s, %d maps in %zd bytes\n",
+			obj->path, nr_maps, data->d_size);
+		return -EINVAL;
+	}
+	map_def_sz = data->d_size / nr_maps;
+
+	/* Fill obj->maps using data in "maps" section.  */
+	for (i = 0; i < nr_syms; i++) {
+		GElf_Sym sym;
+		const char *map_name;
+		struct bpf_map_def *def;
+		struct bpf_map *map;
+
+		if (!gelf_getsym(symbols, i, &sym))
+			continue;
+		if (sym.st_shndx != obj->efile.maps_shndx)
+			continue;
+
+		map = bpf_object__add_map(obj);
+		if (IS_ERR(map))
+			return PTR_ERR(map);
+
+		map_name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				      sym.st_name);
+		if (!map_name) {
+			pr_warn("failed to get map #%d name sym string for obj %s\n",
+				i, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		map->libbpf_type = LIBBPF_MAP_UNSPEC;
+		map->sec_idx = sym.st_shndx;
+		map->sec_offset = sym.st_value;
+		pr_debug("map '%s' (legacy): at sec_idx %d, offset %zu.\n",
+			 map_name, map->sec_idx, map->sec_offset);
+		if (sym.st_value + map_def_sz > data->d_size) {
+			pr_warn("corrupted maps section in %s: last map \"%s\" too small\n",
+				obj->path, map_name);
+			return -EINVAL;
+		}
+
+		map->name = strdup(map_name);
+		if (!map->name) {
+			pr_warn("failed to alloc map name\n");
+			return -ENOMEM;
+		}
+		pr_debug("map %d is \"%s\"\n", i, map->name);
+		def = (struct bpf_map_def *)(data->d_buf + sym.st_value);
+		/*
+		 * If the definition of the map in the object file fits in
+		 * bpf_map_def, copy it.  Any extra fields in our version
+		 * of bpf_map_def will default to zero as a result of the
+		 * calloc above.
+		 */
+		if (map_def_sz <= sizeof(struct bpf_map_def)) {
+			memcpy(&map->def, def, map_def_sz);
+		} else {
+			/*
+			 * Here the map structure being read is bigger than what
+			 * we expect, truncate if the excess bits are all zero.
+			 * If they are not zero, reject this map as
+			 * incompatible.
+			 */
+			char *b;
+
+			for (b = ((char *)def) + sizeof(struct bpf_map_def);
+			     b < ((char *)def) + map_def_sz; b++) {
+				if (*b != 0) {
+					pr_warn("maps section in %s: \"%s\" has unrecognized, non-zero options\n",
+						obj->path, map_name);
+					if (strict)
+						return -EINVAL;
+				}
+			}
+			memcpy(&map->def, def, sizeof(struct bpf_map_def));
+		}
+	}
+	return 0;
+}
+
+static const struct btf_type *
+skip_mods_and_typedefs(const struct btf *btf, __u32 id, __u32 *res_id)
+{
+	const struct btf_type *t = btf__type_by_id(btf, id);
+
+	if (res_id)
+		*res_id = id;
+
+	while (btf_is_mod(t) || btf_is_typedef(t)) {
+		if (res_id)
+			*res_id = t->type;
+		t = btf__type_by_id(btf, t->type);
+	}
+
+	return t;
+}
+
+/*
+ * Fetch integer attribute of BTF map definition. Such attributes are
+ * represented using a pointer to an array, in which dimensionality of array
+ * encodes specified integer value. E.g., int (*type)[BPF_MAP_TYPE_ARRAY];
+ * encodes `type => BPF_MAP_TYPE_ARRAY` key/value pair completely using BTF
+ * type definition, while using only sizeof(void *) space in ELF data section.
+ */
+static bool get_map_field_int(const char *map_name, const struct btf *btf,
+			      const struct btf_type *def,
+			      const struct btf_member *m, __u32 *res)
+{
+	const struct btf_type *t = skip_mods_and_typedefs(btf, m->type, NULL);
+	const char *name = btf__name_by_offset(btf, m->name_off);
+	const struct btf_array *arr_info;
+	const struct btf_type *arr_t;
+
+	if (!btf_is_ptr(t)) {
+		pr_warn("map '%s': attr '%s': expected PTR, got %u.\n",
+			map_name, name, btf_kind(t));
+		return false;
+	}
+
+	arr_t = btf__type_by_id(btf, t->type);
+	if (!arr_t) {
+		pr_warn("map '%s': attr '%s': type [%u] not found.\n",
+			map_name, name, t->type);
+		return false;
+	}
+	if (!btf_is_array(arr_t)) {
+		pr_warn("map '%s': attr '%s': expected ARRAY, got %u.\n",
+			map_name, name, btf_kind(arr_t));
+		return false;
+	}
+	arr_info = btf_array(arr_t);
+	*res = arr_info->nelems;
+	return true;
+}
+
+static int build_map_pin_path(struct bpf_map *map, const char *path)
+{
+	char buf[PATH_MAX];
+	int err, len;
+
+	if (!path)
+		path = "/sys/fs/bpf";
+
+	len = snprintf(buf, PATH_MAX, "%s/%s", path, bpf_map__name(map));
+	if (len < 0)
+		return -EINVAL;
+	else if (len >= PATH_MAX)
+		return -ENAMETOOLONG;
+
+	err = bpf_map__set_pin_path(map, buf);
+	if (err)
+		return err;
+
+	return 0;
+}
+
+static int bpf_object__init_user_btf_map(struct bpf_object *obj,
+					 const struct btf_type *sec,
+					 int var_idx, int sec_idx,
+					 const Elf_Data *data, bool strict,
+					 const char *pin_root_path)
+{
+	const struct btf_type *var, *def, *t;
+	const struct btf_var_secinfo *vi;
+	const struct btf_var *var_extra;
+	const struct btf_member *m;
+	const char *map_name;
+	struct bpf_map *map;
+	int vlen, i;
+
+	vi = btf_var_secinfos(sec) + var_idx;
+	var = btf__type_by_id(obj->btf, vi->type);
+	var_extra = btf_var(var);
+	map_name = btf__name_by_offset(obj->btf, var->name_off);
+	vlen = btf_vlen(var);
+
+	if (map_name == NULL || map_name[0] == '\0') {
+		pr_warn("map #%d: empty name.\n", var_idx);
+		return -EINVAL;
+	}
+	if ((__u64)vi->offset + vi->size > data->d_size) {
+		pr_warn("map '%s' BTF data is corrupted.\n", map_name);
+		return -EINVAL;
+	}
+	if (!btf_is_var(var)) {
+		pr_warn("map '%s': unexpected var kind %u.\n",
+			map_name, btf_kind(var));
+		return -EINVAL;
+	}
+	if (var_extra->linkage != BTF_VAR_GLOBAL_ALLOCATED &&
+	    var_extra->linkage != BTF_VAR_STATIC) {
+		pr_warn("map '%s': unsupported var linkage %u.\n",
+			map_name, var_extra->linkage);
+		return -EOPNOTSUPP;
+	}
+
+	def = skip_mods_and_typedefs(obj->btf, var->type, NULL);
+	if (!btf_is_struct(def)) {
+		pr_warn("map '%s': unexpected def kind %u.\n",
+			map_name, btf_kind(var));
+		return -EINVAL;
+	}
+	if (def->size > vi->size) {
+		pr_warn("map '%s': invalid def size.\n", map_name);
+		return -EINVAL;
+	}
+
+	map = bpf_object__add_map(obj);
+	if (IS_ERR(map))
+		return PTR_ERR(map);
+	map->name = strdup(map_name);
+	if (!map->name) {
+		pr_warn("map '%s': failed to alloc map name.\n", map_name);
+		return -ENOMEM;
+	}
+	map->libbpf_type = LIBBPF_MAP_UNSPEC;
+	map->def.type = BPF_MAP_TYPE_UNSPEC;
+	map->sec_idx = sec_idx;
+	map->sec_offset = vi->offset;
+	pr_debug("map '%s': at sec_idx %d, offset %zu.\n",
+		 map_name, map->sec_idx, map->sec_offset);
+
+	vlen = btf_vlen(def);
+	m = btf_members(def);
+	for (i = 0; i < vlen; i++, m++) {
+		const char *name = btf__name_by_offset(obj->btf, m->name_off);
+
+		if (!name) {
+			pr_warn("map '%s': invalid field #%d.\n", map_name, i);
+			return -EINVAL;
+		}
+		if (strcmp(name, "type") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.type))
+				return -EINVAL;
+			pr_debug("map '%s': found type = %u.\n",
+				 map_name, map->def.type);
+		} else if (strcmp(name, "max_entries") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.max_entries))
+				return -EINVAL;
+			pr_debug("map '%s': found max_entries = %u.\n",
+				 map_name, map->def.max_entries);
+		} else if (strcmp(name, "map_flags") == 0) {
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &map->def.map_flags))
+				return -EINVAL;
+			pr_debug("map '%s': found map_flags = %u.\n",
+				 map_name, map->def.map_flags);
+		} else if (strcmp(name, "key_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			pr_debug("map '%s': found key_size = %u.\n",
+				 map_name, sz);
+			if (map->def.key_size && map->def.key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %u.\n",
+					map_name, map->def.key_size, sz);
+				return -EINVAL;
+			}
+			map->def.key_size = sz;
+		} else if (strcmp(name, "key") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(obj->btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': key type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': key spec is not PTR: %u.\n",
+					map_name, btf_kind(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(obj->btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine key size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
+				return sz;
+			}
+			pr_debug("map '%s': found key [%u], sz = %lld.\n",
+				 map_name, t->type, sz);
+			if (map->def.key_size && map->def.key_size != sz) {
+				pr_warn("map '%s': conflicting key size %u != %lld.\n",
+					map_name, map->def.key_size, sz);
+				return -EINVAL;
+			}
+			map->def.key_size = sz;
+			map->btf_key_type_id = t->type;
+		} else if (strcmp(name, "value_size") == 0) {
+			__u32 sz;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &sz))
+				return -EINVAL;
+			pr_debug("map '%s': found value_size = %u.\n",
+				 map_name, sz);
+			if (map->def.value_size && map->def.value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %u.\n",
+					map_name, map->def.value_size, sz);
+				return -EINVAL;
+			}
+			map->def.value_size = sz;
+		} else if (strcmp(name, "value") == 0) {
+			__s64 sz;
+
+			t = btf__type_by_id(obj->btf, m->type);
+			if (!t) {
+				pr_warn("map '%s': value type [%d] not found.\n",
+					map_name, m->type);
+				return -EINVAL;
+			}
+			if (!btf_is_ptr(t)) {
+				pr_warn("map '%s': value spec is not PTR: %u.\n",
+					map_name, btf_kind(t));
+				return -EINVAL;
+			}
+			sz = btf__resolve_size(obj->btf, t->type);
+			if (sz < 0) {
+				pr_warn("map '%s': can't determine value size for type [%u]: %lld.\n",
+					map_name, t->type, sz);
+				return sz;
+			}
+			pr_debug("map '%s': found value [%u], sz = %lld.\n",
+				 map_name, t->type, sz);
+			if (map->def.value_size && map->def.value_size != sz) {
+				pr_warn("map '%s': conflicting value size %u != %lld.\n",
+					map_name, map->def.value_size, sz);
+				return -EINVAL;
+			}
+			map->def.value_size = sz;
+			map->btf_value_type_id = t->type;
+		} else if (strcmp(name, "pinning") == 0) {
+			__u32 val;
+			int err;
+
+			if (!get_map_field_int(map_name, obj->btf, def, m,
+					       &val))
+				return -EINVAL;
+			pr_debug("map '%s': found pinning = %u.\n",
+				 map_name, val);
+
+			if (val != LIBBPF_PIN_NONE &&
+			    val != LIBBPF_PIN_BY_NAME) {
+				pr_warn("map '%s': invalid pinning value %u.\n",
+					map_name, val);
+				return -EINVAL;
+			}
+			if (val == LIBBPF_PIN_BY_NAME) {
+				err = build_map_pin_path(map, pin_root_path);
+				if (err) {
+					pr_warn("map '%s': couldn't build pin path.\n",
+						map_name);
+					return err;
+				}
+			}
+		} else {
+			if (strict) {
+				pr_warn("map '%s': unknown field '%s'.\n",
+					map_name, name);
+				return -ENOTSUP;
+			}
+			pr_debug("map '%s': ignoring unknown field '%s'.\n",
+				 map_name, name);
+		}
+	}
+
+	if (map->def.type == BPF_MAP_TYPE_UNSPEC) {
+		pr_warn("map '%s': map type isn't specified.\n", map_name);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
+					  const char *pin_root_path)
+{
+	const struct btf_type *sec = NULL;
+	int nr_types, i, vlen, err;
+	const struct btf_type *t;
+	const char *name;
+	Elf_Data *data;
+	Elf_Scn *scn;
+
+	if (obj->efile.btf_maps_shndx < 0)
+		return 0;
+
+	scn = elf_getscn(obj->efile.elf, obj->efile.btf_maps_shndx);
+	if (scn)
+		data = elf_getdata(scn, NULL);
+	if (!scn || !data) {
+		pr_warn("failed to get Elf_Data from map section %d (%s)\n",
+			obj->efile.maps_shndx, MAPS_ELF_SEC);
+		return -EINVAL;
+	}
+
+	nr_types = btf__get_nr_types(obj->btf);
+	for (i = 1; i <= nr_types; i++) {
+		t = btf__type_by_id(obj->btf, i);
+		if (!btf_is_datasec(t))
+			continue;
+		name = btf__name_by_offset(obj->btf, t->name_off);
+		if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			sec = t;
+			break;
+		}
+	}
+
+	if (!sec) {
+		pr_warn("DATASEC '%s' not found.\n", MAPS_ELF_SEC);
+		return -ENOENT;
+	}
+
+	vlen = btf_vlen(sec);
+	for (i = 0; i < vlen; i++) {
+		err = bpf_object__init_user_btf_map(obj, sec, i,
+						    obj->efile.btf_maps_shndx,
+						    data, strict,
+						    pin_root_path);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static int bpf_object__init_maps(struct bpf_object *obj, bool relaxed_maps,
+				 const char *pin_root_path)
+{
+	bool strict = !relaxed_maps;
+	int err;
+
+	err = bpf_object__init_user_maps(obj, strict);
+	if (err)
+		return err;
+
+	err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+	if (err)
+		return err;
+
+	err = bpf_object__init_global_data_maps(obj);
+	if (err)
+		return err;
+
+	if (obj->nr_maps) {
+		qsort(obj->maps, obj->nr_maps, sizeof(obj->maps[0]),
+		      compare_bpf_map);
+	}
+	return 0;
+}
+
+static bool section_have_execinstr(struct bpf_object *obj, int idx)
+{
+	Elf_Scn *scn;
+	GElf_Shdr sh;
+
+	scn = elf_getscn(obj->efile.elf, idx);
+	if (!scn)
+		return false;
+
+	if (gelf_getshdr(scn, &sh) != &sh)
+		return false;
+
+	if (sh.sh_flags & SHF_EXECINSTR)
+		return true;
+
+	return false;
+}
+
+static void bpf_object__sanitize_btf(struct bpf_object *obj)
+{
+	bool has_datasec = obj->caps.btf_datasec;
+	bool has_func = obj->caps.btf_func;
+	struct btf *btf = obj->btf;
+	struct btf_type *t;
+	int i, j, vlen;
+
+	if (!obj->btf || (has_func && has_datasec))
+		return;
+
+	for (i = 1; i <= btf__get_nr_types(btf); i++) {
+		t = (struct btf_type *)btf__type_by_id(btf, i);
+
+		if (!has_datasec && btf_is_var(t)) {
+			/* replace VAR with INT */
+			t->info = BTF_INFO_ENC(BTF_KIND_INT, 0, 0);
+			/*
+			 * using size = 1 is the safest choice, 4 will be too
+			 * big and cause kernel BTF validation failure if
+			 * original variable took less than 4 bytes
+			 */
+			t->size = 1;
+			*(int *)(t + 1) = BTF_INT_ENC(0, 0, 8);
+		} else if (!has_datasec && btf_is_datasec(t)) {
+			/* replace DATASEC with STRUCT */
+			const struct btf_var_secinfo *v = btf_var_secinfos(t);
+			struct btf_member *m = btf_members(t);
+			struct btf_type *vt;
+			char *name;
+
+			name = (char *)btf__name_by_offset(btf, t->name_off);
+			while (*name) {
+				if (*name == '.')
+					*name = '_';
+				name++;
+			}
+
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_STRUCT, 0, vlen);
+			for (j = 0; j < vlen; j++, v++, m++) {
+				/* order of field assignments is important */
+				m->offset = v->offset * 8;
+				m->type = v->type;
+				/* preserve variable name as member name */
+				vt = (void *)btf__type_by_id(btf, v->type);
+				m->name_off = vt->name_off;
+			}
+		} else if (!has_func && btf_is_func_proto(t)) {
+			/* replace FUNC_PROTO with ENUM */
+			vlen = btf_vlen(t);
+			t->info = BTF_INFO_ENC(BTF_KIND_ENUM, 0, vlen);
+			t->size = sizeof(__u32); /* kernel enforced */
+		} else if (!has_func && btf_is_func(t)) {
+			/* replace FUNC with TYPEDEF */
+			t->info = BTF_INFO_ENC(BTF_KIND_TYPEDEF, 0, 0);
+		}
+	}
+}
+
+static void bpf_object__sanitize_btf_ext(struct bpf_object *obj)
+{
+	if (!obj->btf_ext)
+		return;
+
+	if (!obj->caps.btf_func) {
+		btf_ext__free(obj->btf_ext);
+		obj->btf_ext = NULL;
+	}
+}
+
+static bool bpf_object__is_btf_mandatory(const struct bpf_object *obj)
+{
+	return obj->efile.btf_maps_shndx >= 0;
+}
+
+static int bpf_object__init_btf(struct bpf_object *obj,
+				Elf_Data *btf_data,
+				Elf_Data *btf_ext_data)
+{
+	bool btf_required = bpf_object__is_btf_mandatory(obj);
+	int err = 0;
+
+	if (btf_data) {
+		obj->btf = btf__new(btf_data->d_buf, btf_data->d_size);
+		if (IS_ERR(obj->btf)) {
+			pr_warn("Error loading ELF section %s: %d.\n",
+				BTF_ELF_SEC, err);
+			goto out;
+		}
+		err = btf__finalize_data(obj, obj->btf);
+		if (err) {
+			pr_warn("Error finalizing %s: %d.\n", BTF_ELF_SEC, err);
+			goto out;
+		}
+	}
+	if (btf_ext_data) {
+		if (!obj->btf) {
+			pr_debug("Ignore ELF section %s because its depending ELF section %s is not found.\n",
+				 BTF_EXT_ELF_SEC, BTF_ELF_SEC);
+			goto out;
+		}
+		obj->btf_ext = btf_ext__new(btf_ext_data->d_buf,
+					    btf_ext_data->d_size);
+		if (IS_ERR(obj->btf_ext)) {
+			pr_warn("Error loading ELF section %s: %ld. Ignored and continue.\n",
+				BTF_EXT_ELF_SEC, PTR_ERR(obj->btf_ext));
+			obj->btf_ext = NULL;
+			goto out;
+		}
+	}
+out:
+	if (err || IS_ERR(obj->btf)) {
+		if (btf_required)
+			err = err ? : PTR_ERR(obj->btf);
+		else
+			err = 0;
+		if (!IS_ERR_OR_NULL(obj->btf))
+			btf__free(obj->btf);
+		obj->btf = NULL;
+	}
+	if (btf_required && !obj->btf) {
+		pr_warn("BTF is required, but is missing or corrupted.\n");
+		return err == 0 ? -ENOENT : err;
+	}
+	return 0;
+}
+
+static int bpf_object__sanitize_and_load_btf(struct bpf_object *obj)
+{
+	int err = 0;
+
+	if (!obj->btf)
+		return 0;
+
+	bpf_object__sanitize_btf(obj);
+	bpf_object__sanitize_btf_ext(obj);
+
+	err = btf__load(obj->btf);
+	if (err) {
+		pr_warn("Error loading %s into kernel: %d.\n",
+			BTF_ELF_SEC, err);
+		btf__free(obj->btf);
+		obj->btf = NULL;
+		/* btf_ext can't exist without btf, so free it as well */
+		if (obj->btf_ext) {
+			btf_ext__free(obj->btf_ext);
+			obj->btf_ext = NULL;
+		}
+
+		if (bpf_object__is_btf_mandatory(obj))
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_object__elf_collect(struct bpf_object *obj, bool relaxed_maps,
+				   const char *pin_root_path)
+{
+	Elf *elf = obj->efile.elf;
+	GElf_Ehdr *ep = &obj->efile.ehdr;
+	Elf_Data *btf_ext_data = NULL;
+	Elf_Data *btf_data = NULL;
+	Elf_Scn *scn = NULL;
+	int idx = 0, err = 0;
+
+	/* Elf is corrupted/truncated, avoid calling elf_strptr. */
+	if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) {
+		pr_warn("failed to get e_shstrndx from %s\n", obj->path);
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+
+	while ((scn = elf_nextscn(elf, scn)) != NULL) {
+		char *name;
+		GElf_Shdr sh;
+		Elf_Data *data;
+
+		idx++;
+		if (gelf_getshdr(scn, &sh) != &sh) {
+			pr_warn("failed to get section(%d) header from %s\n",
+				idx, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name);
+		if (!name) {
+			pr_warn("failed to get section(%d) name from %s\n",
+				idx, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+
+		data = elf_getdata(scn, 0);
+		if (!data) {
+			pr_warn("failed to get section(%d) data from %s(%s)\n",
+				idx, name, obj->path);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		pr_debug("section(%d) %s, size %ld, link %d, flags %lx, type=%d\n",
+			 idx, name, (unsigned long)data->d_size,
+			 (int)sh.sh_link, (unsigned long)sh.sh_flags,
+			 (int)sh.sh_type);
+
+		if (strcmp(name, "license") == 0) {
+			err = bpf_object__init_license(obj,
+						       data->d_buf,
+						       data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "version") == 0) {
+			err = bpf_object__init_kversion(obj,
+							data->d_buf,
+							data->d_size);
+			if (err)
+				return err;
+		} else if (strcmp(name, "maps") == 0) {
+			obj->efile.maps_shndx = idx;
+		} else if (strcmp(name, MAPS_ELF_SEC) == 0) {
+			obj->efile.btf_maps_shndx = idx;
+		} else if (strcmp(name, BTF_ELF_SEC) == 0) {
+			btf_data = data;
+		} else if (strcmp(name, BTF_EXT_ELF_SEC) == 0) {
+			btf_ext_data = data;
+		} else if (sh.sh_type == SHT_SYMTAB) {
+			if (obj->efile.symbols) {
+				pr_warn("bpf: multiple SYMTAB in %s\n",
+					obj->path);
+				return -LIBBPF_ERRNO__FORMAT;
+			}
+			obj->efile.symbols = data;
+			obj->efile.strtabidx = sh.sh_link;
+		} else if (sh.sh_type == SHT_PROGBITS && data->d_size > 0) {
+			if (sh.sh_flags & SHF_EXECINSTR) {
+				if (strcmp(name, ".text") == 0)
+					obj->efile.text_shndx = idx;
+				err = bpf_object__add_program(obj, data->d_buf,
+							      data->d_size,
+							      name, idx);
+				if (err) {
+					char errmsg[STRERR_BUFSIZE];
+					char *cp;
+
+					cp = libbpf_strerror_r(-err, errmsg,
+							       sizeof(errmsg));
+					pr_warn("failed to alloc program %s (%s): %s",
+						name, obj->path, cp);
+					return err;
+				}
+			} else if (strcmp(name, ".data") == 0) {
+				obj->efile.data = data;
+				obj->efile.data_shndx = idx;
+			} else if (strcmp(name, ".rodata") == 0) {
+				obj->efile.rodata = data;
+				obj->efile.rodata_shndx = idx;
+			} else {
+				pr_debug("skip section(%d) %s\n", idx, name);
+			}
+		} else if (sh.sh_type == SHT_REL) {
+			int nr_sects = obj->efile.nr_reloc_sects;
+			void *sects = obj->efile.reloc_sects;
+			int sec = sh.sh_info; /* points to other section */
+
+			/* Only do relo for section with exec instructions */
+			if (!section_have_execinstr(obj, sec)) {
+				pr_debug("skip relo %s(%d) for section(%d)\n",
+					 name, idx, sec);
+				continue;
+			}
+
+			sects = reallocarray(sects, nr_sects + 1,
+					     sizeof(*obj->efile.reloc_sects));
+			if (!sects) {
+				pr_warn("reloc_sects realloc failed\n");
+				return -ENOMEM;
+			}
+
+			obj->efile.reloc_sects = sects;
+			obj->efile.nr_reloc_sects++;
+
+			obj->efile.reloc_sects[nr_sects].shdr = sh;
+			obj->efile.reloc_sects[nr_sects].data = data;
+		} else if (sh.sh_type == SHT_NOBITS && strcmp(name, ".bss") == 0) {
+			obj->efile.bss = data;
+			obj->efile.bss_shndx = idx;
+		} else {
+			pr_debug("skip section(%d) %s\n", idx, name);
+		}
+	}
+
+	if (!obj->efile.strtabidx || obj->efile.strtabidx > idx) {
+		pr_warn("Corrupted ELF file: index of strtab invalid\n");
+		return -LIBBPF_ERRNO__FORMAT;
+	}
+	err = bpf_object__init_btf(obj, btf_data, btf_ext_data);
+	if (!err)
+		err = bpf_object__init_maps(obj, relaxed_maps, pin_root_path);
+	if (!err)
+		err = bpf_object__sanitize_and_load_btf(obj);
+	if (!err)
+		err = bpf_object__init_prog_names(obj);
+	return err;
+}
+
+static struct bpf_program *
+bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx)
+{
+	struct bpf_program *prog;
+	size_t i;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+		if (prog->idx == idx)
+			return prog;
+	}
+	return NULL;
+}
+
+struct bpf_program *
+bpf_object__find_program_by_title(const struct bpf_object *obj,
+				  const char *title)
+{
+	struct bpf_program *pos;
+
+	bpf_object__for_each_program(pos, obj) {
+		if (pos->section_name && !strcmp(pos->section_name, title))
+			return pos;
+	}
+	return NULL;
+}
+
+static bool bpf_object__shndx_is_data(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.data_shndx ||
+	       shndx == obj->efile.bss_shndx ||
+	       shndx == obj->efile.rodata_shndx;
+}
+
+static bool bpf_object__shndx_is_maps(const struct bpf_object *obj,
+				      int shndx)
+{
+	return shndx == obj->efile.maps_shndx ||
+	       shndx == obj->efile.btf_maps_shndx;
+}
+
+static enum libbpf_map_type
+bpf_object__section_to_libbpf_map_type(const struct bpf_object *obj, int shndx)
+{
+	if (shndx == obj->efile.data_shndx)
+		return LIBBPF_MAP_DATA;
+	else if (shndx == obj->efile.bss_shndx)
+		return LIBBPF_MAP_BSS;
+	else if (shndx == obj->efile.rodata_shndx)
+		return LIBBPF_MAP_RODATA;
+	else
+		return LIBBPF_MAP_UNSPEC;
+}
+
+static int bpf_program__record_reloc(struct bpf_program *prog,
+				     struct reloc_desc *reloc_desc,
+				     __u32 insn_idx, const char *name,
+				     const GElf_Sym *sym, const GElf_Rel *rel)
+{
+	struct bpf_insn *insn = &prog->insns[insn_idx];
+	size_t map_idx, nr_maps = prog->obj->nr_maps;
+	struct bpf_object *obj = prog->obj;
+	__u32 shdr_idx = sym->st_shndx;
+	enum libbpf_map_type type;
+	struct bpf_map *map;
+
+	/* sub-program call relocation */
+	if (insn->code == (BPF_JMP | BPF_CALL)) {
+		if (insn->src_reg != BPF_PSEUDO_CALL) {
+			pr_warn("incorrect bpf_call opcode\n");
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		/* text_shndx can be 0, if no default "main" program exists */
+		if (!shdr_idx || shdr_idx != obj->efile.text_shndx) {
+			pr_warn("bad call relo against section %u\n", shdr_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		if (sym->st_value % 8) {
+			pr_warn("bad call relo offset: %llu\n", (__u64)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_CALL;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->sym_off = sym->st_value;
+		obj->has_pseudo_calls = true;
+		return 0;
+	}
+
+	if (insn->code != (BPF_LD | BPF_IMM | BPF_DW)) {
+		pr_warn("invalid relo for insns[%d].code 0x%x\n",
+			insn_idx, insn->code);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	if (!shdr_idx || shdr_idx >= SHN_LORESERVE) {
+		pr_warn("invalid relo for \'%s\' in special section 0x%x; forgot to initialize global var?..\n",
+			name, shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	type = bpf_object__section_to_libbpf_map_type(obj, shdr_idx);
+
+	/* generic map reference relocation */
+	if (type == LIBBPF_MAP_UNSPEC) {
+		if (!bpf_object__shndx_is_maps(obj, shdr_idx)) {
+			pr_warn("bad map relo against section %u\n",
+				shdr_idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+			map = &obj->maps[map_idx];
+			if (map->libbpf_type != type ||
+			    map->sec_idx != sym->st_shndx ||
+			    map->sec_offset != sym->st_value)
+				continue;
+			pr_debug("found map %zd (%s, sec %d, off %zu) for insn %u\n",
+				 map_idx, map->name, map->sec_idx,
+				 map->sec_offset, insn_idx);
+			break;
+		}
+		if (map_idx >= nr_maps) {
+			pr_warn("map relo failed to find map for sec %u, off %llu\n",
+				shdr_idx, (__u64)sym->st_value);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		reloc_desc->type = RELO_LD64;
+		reloc_desc->insn_idx = insn_idx;
+		reloc_desc->map_idx = map_idx;
+		reloc_desc->sym_off = 0; /* sym->st_value determines map_idx */
+		return 0;
+	}
+
+	/* global data map relocation */
+	if (!bpf_object__shndx_is_data(obj, shdr_idx)) {
+		pr_warn("bad data relo against section %u\n", shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	if (!obj->caps.global_data) {
+		pr_warn("relocation: kernel does not support global \'%s\' variable access in insns[%d]\n",
+			name, insn_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+	for (map_idx = 0; map_idx < nr_maps; map_idx++) {
+		map = &obj->maps[map_idx];
+		if (map->libbpf_type != type)
+			continue;
+		pr_debug("found data map %zd (%s, sec %d, off %zu) for insn %u\n",
+			 map_idx, map->name, map->sec_idx, map->sec_offset,
+			 insn_idx);
+		break;
+	}
+	if (map_idx >= nr_maps) {
+		pr_warn("data relo failed to find map for sec %u\n",
+			shdr_idx);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	reloc_desc->type = RELO_DATA;
+	reloc_desc->insn_idx = insn_idx;
+	reloc_desc->map_idx = map_idx;
+	reloc_desc->sym_off = sym->st_value;
+	return 0;
+}
+
+static int
+bpf_program__collect_reloc(struct bpf_program *prog, GElf_Shdr *shdr,
+			   Elf_Data *data, struct bpf_object *obj)
+{
+	Elf_Data *symbols = obj->efile.symbols;
+	int err, i, nrels;
+
+	pr_debug("collecting relocating info for: '%s'\n", prog->section_name);
+	nrels = shdr->sh_size / shdr->sh_entsize;
+
+	prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels);
+	if (!prog->reloc_desc) {
+		pr_warn("failed to alloc memory in relocation\n");
+		return -ENOMEM;
+	}
+	prog->nr_reloc = nrels;
+
+	for (i = 0; i < nrels; i++) {
+		const char *name;
+		__u32 insn_idx;
+		GElf_Sym sym;
+		GElf_Rel rel;
+
+		if (!gelf_getrel(data, i, &rel)) {
+			pr_warn("relocation: failed to get %d reloc\n", i);
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		if (!gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym)) {
+			pr_warn("relocation: symbol %"PRIx64" not found\n",
+				GELF_R_SYM(rel.r_info));
+			return -LIBBPF_ERRNO__FORMAT;
+		}
+		if (rel.r_offset % sizeof(struct bpf_insn))
+			return -LIBBPF_ERRNO__FORMAT;
+
+		insn_idx = rel.r_offset / sizeof(struct bpf_insn);
+		name = elf_strptr(obj->efile.elf, obj->efile.strtabidx,
+				  sym.st_name) ? : "<?>";
+
+		pr_debug("relo for shdr %u, symb %llu, value %llu, type %d, bind %d, name %d (\'%s\'), insn %u\n",
+			 (__u32)sym.st_shndx, (__u64)GELF_R_SYM(rel.r_info),
+			 (__u64)sym.st_value, GELF_ST_TYPE(sym.st_info),
+			 GELF_ST_BIND(sym.st_info), sym.st_name, name,
+			 insn_idx);
+
+		err = bpf_program__record_reloc(prog, &prog->reloc_desc[i],
+						insn_idx, name, &sym, &rel);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int bpf_map_find_btf_info(struct bpf_object *obj, struct bpf_map *map)
+{
+	struct bpf_map_def *def = &map->def;
+	__u32 key_type_id = 0, value_type_id = 0;
+	int ret;
+
+	/* if it's BTF-defined map, we don't need to search for type IDs */
+	if (map->sec_idx == obj->efile.btf_maps_shndx)
+		return 0;
+
+	if (!bpf_map__is_internal(map)) {
+		ret = btf__get_map_kv_tids(obj->btf, map->name, def->key_size,
+					   def->value_size, &key_type_id,
+					   &value_type_id);
+	} else {
+		/*
+		 * LLVM annotates global data differently in BTF, that is,
+		 * only as '.data', '.bss' or '.rodata'.
+		 */
+		ret = btf__find_by_name(obj->btf,
+				libbpf_type_to_btf_name[map->libbpf_type]);
+	}
+	if (ret < 0)
+		return ret;
+
+	map->btf_key_type_id = key_type_id;
+	map->btf_value_type_id = bpf_map__is_internal(map) ?
+				 ret : value_type_id;
+	return 0;
+}
+
+int bpf_map__reuse_fd(struct bpf_map *map, int fd)
+{
+	struct bpf_map_info info = {};
+	__u32 len = sizeof(info);
+	int new_fd, err;
+	char *new_name;
+
+	err = bpf_obj_get_info_by_fd(fd, &info, &len);
+	if (err)
+		return err;
+
+	new_name = strdup(info.name);
+	if (!new_name)
+		return -errno;
+
+	new_fd = open("/", O_RDONLY | O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_free_new_name;
+	}
+
+	new_fd = dup3(fd, new_fd, O_CLOEXEC);
+	if (new_fd < 0) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+
+	err = zclose(map->fd);
+	if (err) {
+		err = -errno;
+		goto err_close_new_fd;
+	}
+	free(map->name);
+
+	map->fd = new_fd;
+	map->name = new_name;
+	map->def.type = info.type;
+	map->def.key_size = info.key_size;
+	map->def.value_size = info.value_size;
+	map->def.max_entries = info.max_entries;
+	map->def.map_flags = info.map_flags;
+	map->btf_key_type_id = info.btf_key_type_id;
+	map->btf_value_type_id = info.btf_value_type_id;
+	map->reused = true;
+
+	return 0;
+
+err_close_new_fd:
+	close(new_fd);
+err_free_new_name:
+	free(new_name);
+	return err;
+}
+
+int bpf_map__resize(struct bpf_map *map, __u32 max_entries)
+{
+	if (!map || !max_entries)
+		return -EINVAL;
+
+	/* If map already created, its attributes can't be changed. */
+	if (map->fd >= 0)
+		return -EBUSY;
+
+	map->def.max_entries = max_entries;
+
+	return 0;
+}
+
+static int
+bpf_object__probe_name(struct bpf_object *obj)
+{
+	struct bpf_load_program_attr attr;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret;
+
+	/* make sure basic loading works */
+
+	memset(&attr, 0, sizeof(attr));
+	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	attr.insns = insns;
+	attr.insns_cnt = ARRAY_SIZE(insns);
+	attr.license = "GPL";
+
+	ret = bpf_load_program_xattr(&attr, NULL, 0);
+	if (ret < 0) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't load basic 'r0 = 0' BPF program.\n",
+			__func__, cp, errno);
+		return -errno;
+	}
+	close(ret);
+
+	/* now try the same program, but with the name */
+
+	attr.name = "test";
+	ret = bpf_load_program_xattr(&attr, NULL, 0);
+	if (ret >= 0) {
+		obj->caps.name = 1;
+		close(ret);
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__probe_global_data(struct bpf_object *obj)
+{
+	struct bpf_load_program_attr prg_attr;
+	struct bpf_create_map_attr map_attr;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct bpf_insn insns[] = {
+		BPF_LD_MAP_VALUE(BPF_REG_1, 0, 16),
+		BPF_ST_MEM(BPF_DW, BPF_REG_1, 0, 42),
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN(),
+	};
+	int ret, map;
+
+	memset(&map_attr, 0, sizeof(map_attr));
+	map_attr.map_type = BPF_MAP_TYPE_ARRAY;
+	map_attr.key_size = sizeof(int);
+	map_attr.value_size = 32;
+	map_attr.max_entries = 1;
+
+	map = bpf_create_map_xattr(&map_attr);
+	if (map < 0) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("Error in %s():%s(%d). Couldn't create simple array map.\n",
+			__func__, cp, errno);
+		return -errno;
+	}
+
+	insns[0].imm = map;
+
+	memset(&prg_attr, 0, sizeof(prg_attr));
+	prg_attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;
+	prg_attr.insns = insns;
+	prg_attr.insns_cnt = ARRAY_SIZE(insns);
+	prg_attr.license = "GPL";
+
+	ret = bpf_load_program_xattr(&prg_attr, NULL, 0);
+	if (ret >= 0) {
+		obj->caps.global_data = 1;
+		close(ret);
+	}
+
+	close(map);
+	return 0;
+}
+
+static int bpf_object__probe_btf_func(struct bpf_object *obj)
+{
+	static const char strs[] = "\0int\0x\0a";
+	/* void x(int a) {} */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(1, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* FUNC_PROTO */                                /* [2] */
+		BTF_TYPE_ENC(0, BTF_INFO_ENC(BTF_KIND_FUNC_PROTO, 0, 1), 0),
+		BTF_PARAM_ENC(7, 1),
+		/* FUNC x */                                    /* [3] */
+		BTF_TYPE_ENC(5, BTF_INFO_ENC(BTF_KIND_FUNC, 0, 0), 2),
+	};
+	int btf_fd;
+
+	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+				      strs, sizeof(strs));
+	if (btf_fd >= 0) {
+		obj->caps.btf_func = 1;
+		close(btf_fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int bpf_object__probe_btf_datasec(struct bpf_object *obj)
+{
+	static const char strs[] = "\0x\0.data";
+	/* static int a; */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* VAR x */                                     /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1),
+		BTF_VAR_STATIC,
+		/* DATASEC val */                               /* [3] */
+		BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4),
+		BTF_VAR_SECINFO_ENC(2, 0, 4),
+	};
+	int btf_fd;
+
+	btf_fd = libbpf__load_raw_btf((char *)types, sizeof(types),
+				      strs, sizeof(strs));
+	if (btf_fd >= 0) {
+		obj->caps.btf_datasec = 1;
+		close(btf_fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int bpf_object__probe_array_mmap(struct bpf_object *obj)
+{
+	struct bpf_create_map_attr attr = {
+		.map_type = BPF_MAP_TYPE_ARRAY,
+		.map_flags = BPF_F_MMAPABLE,
+		.key_size = sizeof(int),
+		.value_size = sizeof(int),
+		.max_entries = 1,
+	};
+	int fd;
+
+	fd = bpf_create_map_xattr(&attr);
+	if (fd >= 0) {
+		obj->caps.array_mmap = 1;
+		close(fd);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int
+bpf_object__probe_caps(struct bpf_object *obj)
+{
+	int (*probe_fn[])(struct bpf_object *obj) = {
+		bpf_object__probe_name,
+		bpf_object__probe_global_data,
+		bpf_object__probe_btf_func,
+		bpf_object__probe_btf_datasec,
+		bpf_object__probe_array_mmap,
+	};
+	int i, ret;
+
+	for (i = 0; i < ARRAY_SIZE(probe_fn); i++) {
+		ret = probe_fn[i](obj);
+		if (ret < 0)
+			pr_debug("Probe #%d failed with %d.\n", i, ret);
+	}
+
+	return 0;
+}
+
+static bool map_is_reuse_compat(const struct bpf_map *map, int map_fd)
+{
+	struct bpf_map_info map_info = {};
+	char msg[STRERR_BUFSIZE];
+	__u32 map_info_len;
+
+	map_info_len = sizeof(map_info);
+
+	if (bpf_obj_get_info_by_fd(map_fd, &map_info, &map_info_len)) {
+		pr_warn("failed to get map info for map FD %d: %s\n",
+			map_fd, libbpf_strerror_r(errno, msg, sizeof(msg)));
+		return false;
+	}
+
+	return (map_info.type == map->def.type &&
+		map_info.key_size == map->def.key_size &&
+		map_info.value_size == map->def.value_size &&
+		map_info.max_entries == map->def.max_entries &&
+		map_info.map_flags == map->def.map_flags);
+}
+
+static int
+bpf_object__reuse_map(struct bpf_map *map)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, pin_fd;
+
+	pin_fd = bpf_obj_get(map->pin_path);
+	if (pin_fd < 0) {
+		err = -errno;
+		if (err == -ENOENT) {
+			pr_debug("found no pinned map to reuse at '%s'\n",
+				 map->pin_path);
+			return 0;
+		}
+
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("couldn't retrieve pinned map '%s': %s\n",
+			map->pin_path, cp);
+		return err;
+	}
+
+	if (!map_is_reuse_compat(map, pin_fd)) {
+		pr_warn("couldn't reuse pinned map at '%s': parameter mismatch\n",
+			map->pin_path);
+		close(pin_fd);
+		return -EINVAL;
+	}
+
+	err = bpf_map__reuse_fd(map, pin_fd);
+	if (err) {
+		close(pin_fd);
+		return err;
+	}
+	map->pinned = true;
+	pr_debug("reused pinned map at '%s'\n", map->pin_path);
+
+	return 0;
+}
+
+static int
+bpf_object__populate_internal_map(struct bpf_object *obj, struct bpf_map *map)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err, zero = 0;
+	__u8 *data;
+
+	/* Nothing to do here since kernel already zero-initializes .bss map. */
+	if (map->libbpf_type == LIBBPF_MAP_BSS)
+		return 0;
+
+	data = map->libbpf_type == LIBBPF_MAP_DATA ?
+	       obj->sections.data : obj->sections.rodata;
+
+	err = bpf_map_update_elem(map->fd, &zero, data, 0);
+	/* Freeze .rodata map as read-only from syscall side. */
+	if (!err && map->libbpf_type == LIBBPF_MAP_RODATA) {
+		err = bpf_map_freeze(map->fd);
+		if (err) {
+			cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+			pr_warn("Error freezing map(%s) as read-only: %s\n",
+				map->name, cp);
+			err = 0;
+		}
+	}
+	return err;
+}
+
+static int
+bpf_object__create_maps(struct bpf_object *obj)
+{
+	struct bpf_create_map_attr create_attr = {};
+	int nr_cpus = 0;
+	unsigned int i;
+	int err;
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		struct bpf_map *map = &obj->maps[i];
+		struct bpf_map_def *def = &map->def;
+		char *cp, errmsg[STRERR_BUFSIZE];
+		int *pfd = &map->fd;
+
+		if (map->pin_path) {
+			err = bpf_object__reuse_map(map);
+			if (err) {
+				pr_warn("error reusing pinned map %s\n",
+					map->name);
+				return err;
+			}
+		}
+
+		if (map->fd >= 0) {
+			pr_debug("skip map create (preset) %s: fd=%d\n",
+				 map->name, map->fd);
+			continue;
+		}
+
+		if (obj->caps.name)
+			create_attr.name = map->name;
+		create_attr.map_ifindex = map->map_ifindex;
+		create_attr.map_type = def->type;
+		create_attr.map_flags = def->map_flags;
+		create_attr.key_size = def->key_size;
+		create_attr.value_size = def->value_size;
+		if (def->type == BPF_MAP_TYPE_PERF_EVENT_ARRAY &&
+		    !def->max_entries) {
+			if (!nr_cpus)
+				nr_cpus = libbpf_num_possible_cpus();
+			if (nr_cpus < 0) {
+				pr_warn("failed to determine number of system CPUs: %d\n",
+					nr_cpus);
+				err = nr_cpus;
+				goto err_out;
+			}
+			pr_debug("map '%s': setting size to %d\n",
+				 map->name, nr_cpus);
+			create_attr.max_entries = nr_cpus;
+		} else {
+			create_attr.max_entries = def->max_entries;
+		}
+		create_attr.btf_fd = 0;
+		create_attr.btf_key_type_id = 0;
+		create_attr.btf_value_type_id = 0;
+		if (bpf_map_type__is_map_in_map(def->type) &&
+		    map->inner_map_fd >= 0)
+			create_attr.inner_map_fd = map->inner_map_fd;
+
+		if (obj->btf && !bpf_map_find_btf_info(obj, map)) {
+			create_attr.btf_fd = btf__fd(obj->btf);
+			create_attr.btf_key_type_id = map->btf_key_type_id;
+			create_attr.btf_value_type_id = map->btf_value_type_id;
+		}
+
+		*pfd = bpf_create_map_xattr(&create_attr);
+		if (*pfd < 0 && (create_attr.btf_key_type_id ||
+				 create_attr.btf_value_type_id)) {
+			err = -errno;
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("Error in bpf_create_map_xattr(%s):%s(%d). Retrying without BTF.\n",
+				map->name, cp, err);
+			create_attr.btf_fd = 0;
+			create_attr.btf_key_type_id = 0;
+			create_attr.btf_value_type_id = 0;
+			map->btf_key_type_id = 0;
+			map->btf_value_type_id = 0;
+			*pfd = bpf_create_map_xattr(&create_attr);
+		}
+
+		if (*pfd < 0) {
+			size_t j;
+
+			err = -errno;
+err_out:
+			cp = libbpf_strerror_r(err, errmsg, sizeof(errmsg));
+			pr_warn("failed to create map (name: '%s'): %s(%d)\n",
+				map->name, cp, err);
+			for (j = 0; j < i; j++)
+				zclose(obj->maps[j].fd);
+			return err;
+		}
+
+		if (bpf_map__is_internal(map)) {
+			err = bpf_object__populate_internal_map(obj, map);
+			if (err < 0) {
+				zclose(*pfd);
+				goto err_out;
+			}
+		}
+
+		if (map->pin_path && !map->pinned) {
+			err = bpf_map__pin(map, NULL);
+			if (err) {
+				pr_warn("failed to auto-pin map name '%s' at '%s'\n",
+					map->name, map->pin_path);
+				return err;
+			}
+		}
+
+		pr_debug("created map %s: fd=%d\n", map->name, *pfd);
+	}
+
+	return 0;
+}
+
+static int
+check_btf_ext_reloc_err(struct bpf_program *prog, int err,
+			void *btf_prog_info, const char *info_name)
+{
+	if (err != -ENOENT) {
+		pr_warn("Error in loading %s for sec %s.\n",
+			info_name, prog->section_name);
+		return err;
+	}
+
+	/* err == -ENOENT (i.e. prog->section_name not found in btf_ext) */
+
+	if (btf_prog_info) {
+		/*
+		 * Some info has already been found but has problem
+		 * in the last btf_ext reloc. Must have to error out.
+		 */
+		pr_warn("Error in relocating %s for sec %s.\n",
+			info_name, prog->section_name);
+		return err;
+	}
+
+	/* Have problem loading the very first info. Ignore the rest. */
+	pr_warn("Cannot find %s for main program sec %s. Ignore all %s.\n",
+		info_name, prog->section_name, info_name);
+	return 0;
+}
+
+static int
+bpf_program_reloc_btf_ext(struct bpf_program *prog, struct bpf_object *obj,
+			  const char *section_name,  __u32 insn_offset)
+{
+	int err;
+
+	if (!insn_offset || prog->func_info) {
+		/*
+		 * !insn_offset => main program
+		 *
+		 * For sub prog, the main program's func_info has to
+		 * be loaded first (i.e. prog->func_info != NULL)
+		 */
+		err = btf_ext__reloc_func_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->func_info,
+					       &prog->func_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->func_info,
+						       "bpf_func_info");
+
+		prog->func_info_rec_size = btf_ext__func_info_rec_size(obj->btf_ext);
+	}
+
+	if (!insn_offset || prog->line_info) {
+		err = btf_ext__reloc_line_info(obj->btf, obj->btf_ext,
+					       section_name, insn_offset,
+					       &prog->line_info,
+					       &prog->line_info_cnt);
+		if (err)
+			return check_btf_ext_reloc_err(prog, err,
+						       prog->line_info,
+						       "bpf_line_info");
+
+		prog->line_info_rec_size = btf_ext__line_info_rec_size(obj->btf_ext);
+	}
+
+	return 0;
+}
+
+#define BPF_CORE_SPEC_MAX_LEN 64
+
+/* represents BPF CO-RE field or array element accessor */
+struct bpf_core_accessor {
+	__u32 type_id;		/* struct/union type or array element type */
+	__u32 idx;		/* field index or array index */
+	const char *name;	/* field name or NULL for array accessor */
+};
+
+struct bpf_core_spec {
+	const struct btf *btf;
+	/* high-level spec: named fields and array indices only */
+	struct bpf_core_accessor spec[BPF_CORE_SPEC_MAX_LEN];
+	/* high-level spec length */
+	int len;
+	/* raw, low-level spec: 1-to-1 with accessor spec string */
+	int raw_spec[BPF_CORE_SPEC_MAX_LEN];
+	/* raw spec length */
+	int raw_len;
+	/* field bit offset represented by spec */
+	__u32 bit_offset;
+};
+
+static bool str_is_empty(const char *s)
+{
+	return !s || !s[0];
+}
+
+/*
+ * Turn bpf_field_reloc into a low- and high-level spec representation,
+ * validating correctness along the way, as well as calculating resulting
+ * field bit offset, specified by accessor string. Low-level spec captures
+ * every single level of nestedness, including traversing anonymous
+ * struct/union members. High-level one only captures semantically meaningful
+ * "turning points": named fields and array indicies.
+ * E.g., for this case:
+ *
+ *   struct sample {
+ *       int __unimportant;
+ *       struct {
+ *           int __1;
+ *           int __2;
+ *           int a[7];
+ *       };
+ *   };
+ *
+ *   struct sample *s = ...;
+ *
+ *   int x = &s->a[3]; // access string = '0:1:2:3'
+ *
+ * Low-level spec has 1:1 mapping with each element of access string (it's
+ * just a parsed access string representation): [0, 1, 2, 3].
+ *
+ * High-level spec will capture only 3 points:
+ *   - intial zero-index access by pointer (&s->... is the same as &s[0]...);
+ *   - field 'a' access (corresponds to '2' in low-level spec);
+ *   - array element #3 access (corresponds to '3' in low-level spec).
+ *
+ */
+static int bpf_core_spec_parse(const struct btf *btf,
+			       __u32 type_id,
+			       const char *spec_str,
+			       struct bpf_core_spec *spec)
+{
+	int access_idx, parsed_len, i;
+	const struct btf_type *t;
+	const char *name;
+	__u32 id;
+	__s64 sz;
+
+	if (str_is_empty(spec_str) || *spec_str == ':')
+		return -EINVAL;
+
+	memset(spec, 0, sizeof(*spec));
+	spec->btf = btf;
+
+	/* parse spec_str="0:1:2:3:4" into array raw_spec=[0, 1, 2, 3, 4] */
+	while (*spec_str) {
+		if (*spec_str == ':')
+			++spec_str;
+		if (sscanf(spec_str, "%d%n", &access_idx, &parsed_len) != 1)
+			return -EINVAL;
+		if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+			return -E2BIG;
+		spec_str += parsed_len;
+		spec->raw_spec[spec->raw_len++] = access_idx;
+	}
+
+	if (spec->raw_len == 0)
+		return -EINVAL;
+
+	/* first spec value is always reloc type array index */
+	t = skip_mods_and_typedefs(btf, type_id, &id);
+	if (!t)
+		return -EINVAL;
+
+	access_idx = spec->raw_spec[0];
+	spec->spec[0].type_id = id;
+	spec->spec[0].idx = access_idx;
+	spec->len++;
+
+	sz = btf__resolve_size(btf, id);
+	if (sz < 0)
+		return sz;
+	spec->bit_offset = access_idx * sz * 8;
+
+	for (i = 1; i < spec->raw_len; i++) {
+		t = skip_mods_and_typedefs(btf, id, &id);
+		if (!t)
+			return -EINVAL;
+
+		access_idx = spec->raw_spec[i];
+
+		if (btf_is_composite(t)) {
+			const struct btf_member *m;
+			__u32 bit_offset;
+
+			if (access_idx >= btf_vlen(t))
+				return -EINVAL;
+
+			bit_offset = btf_member_bit_offset(t, access_idx);
+			spec->bit_offset += bit_offset;
+
+			m = btf_members(t) + access_idx;
+			if (m->name_off) {
+				name = btf__name_by_offset(btf, m->name_off);
+				if (str_is_empty(name))
+					return -EINVAL;
+
+				spec->spec[spec->len].type_id = id;
+				spec->spec[spec->len].idx = access_idx;
+				spec->spec[spec->len].name = name;
+				spec->len++;
+			}
+
+			id = m->type;
+		} else if (btf_is_array(t)) {
+			const struct btf_array *a = btf_array(t);
+
+			t = skip_mods_and_typedefs(btf, a->type, &id);
+			if (!t || access_idx >= a->nelems)
+				return -EINVAL;
+
+			spec->spec[spec->len].type_id = id;
+			spec->spec[spec->len].idx = access_idx;
+			spec->len++;
+
+			sz = btf__resolve_size(btf, id);
+			if (sz < 0)
+				return sz;
+			spec->bit_offset += access_idx * sz * 8;
+		} else {
+			pr_warn("relo for [%u] %s (at idx %d) captures type [%d] of unexpected kind %d\n",
+				type_id, spec_str, i, id, btf_kind(t));
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+static bool bpf_core_is_flavor_sep(const char *s)
+{
+	/* check X___Y name pattern, where X and Y are not underscores */
+	return s[0] != '_' &&				      /* X */
+	       s[1] == '_' && s[2] == '_' && s[3] == '_' &&   /* ___ */
+	       s[4] != '_';				      /* Y */
+}
+
+/* Given 'some_struct_name___with_flavor' return the length of a name prefix
+ * before last triple underscore. Struct name part after last triple
+ * underscore is ignored by BPF CO-RE relocation during relocation matching.
+ */
+static size_t bpf_core_essential_name_len(const char *name)
+{
+	size_t n = strlen(name);
+	int i;
+
+	for (i = n - 5; i >= 0; i--) {
+		if (bpf_core_is_flavor_sep(name + i))
+			return i + 1;
+	}
+	return n;
+}
+
+/* dynamically sized list of type IDs */
+struct ids_vec {
+	__u32 *data;
+	int len;
+};
+
+static void bpf_core_free_cands(struct ids_vec *cand_ids)
+{
+	free(cand_ids->data);
+	free(cand_ids);
+}
+
+static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
+					   __u32 local_type_id,
+					   const struct btf *targ_btf)
+{
+	size_t local_essent_len, targ_essent_len;
+	const char *local_name, *targ_name;
+	const struct btf_type *t;
+	struct ids_vec *cand_ids;
+	__u32 *new_ids;
+	int i, err, n;
+
+	t = btf__type_by_id(local_btf, local_type_id);
+	if (!t)
+		return ERR_PTR(-EINVAL);
+
+	local_name = btf__name_by_offset(local_btf, t->name_off);
+	if (str_is_empty(local_name))
+		return ERR_PTR(-EINVAL);
+	local_essent_len = bpf_core_essential_name_len(local_name);
+
+	cand_ids = calloc(1, sizeof(*cand_ids));
+	if (!cand_ids)
+		return ERR_PTR(-ENOMEM);
+
+	n = btf__get_nr_types(targ_btf);
+	for (i = 1; i <= n; i++) {
+		t = btf__type_by_id(targ_btf, i);
+		targ_name = btf__name_by_offset(targ_btf, t->name_off);
+		if (str_is_empty(targ_name))
+			continue;
+
+		targ_essent_len = bpf_core_essential_name_len(targ_name);
+		if (targ_essent_len != local_essent_len)
+			continue;
+
+		if (strncmp(local_name, targ_name, local_essent_len) == 0) {
+			pr_debug("[%d] %s: found candidate [%d] %s\n",
+				 local_type_id, local_name, i, targ_name);
+			new_ids = realloc(cand_ids->data, cand_ids->len + 1);
+			if (!new_ids) {
+				err = -ENOMEM;
+				goto err_out;
+			}
+			cand_ids->data = new_ids;
+			cand_ids->data[cand_ids->len++] = i;
+		}
+	}
+	return cand_ids;
+err_out:
+	bpf_core_free_cands(cand_ids);
+	return ERR_PTR(err);
+}
+
+/* Check two types for compatibility, skipping const/volatile/restrict and
+ * typedefs, to ensure we are relocating compatible entities:
+ *   - any two STRUCTs/UNIONs are compatible and can be mixed;
+ *   - any two FWDs are compatible, if their names match (modulo flavor suffix);
+ *   - any two PTRs are always compatible;
+ *   - for ENUMs, names should be the same (ignoring flavor suffix) or at
+ *     least one of enums should be anonymous;
+ *   - for ENUMs, check sizes, names are ignored;
+ *   - for INT, size and signedness are ignored;
+ *   - for ARRAY, dimensionality is ignored, element types are checked for
+ *     compatibility recursively;
+ *   - everything else shouldn't be ever a target of relocation.
+ * These rules are not set in stone and probably will be adjusted as we get
+ * more experience with using BPF CO-RE relocations.
+ */
+static int bpf_core_fields_are_compat(const struct btf *local_btf,
+				      __u32 local_id,
+				      const struct btf *targ_btf,
+				      __u32 targ_id)
+{
+	const struct btf_type *local_type, *targ_type;
+
+recur:
+	local_type = skip_mods_and_typedefs(local_btf, local_id, &local_id);
+	targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!local_type || !targ_type)
+		return -EINVAL;
+
+	if (btf_is_composite(local_type) && btf_is_composite(targ_type))
+		return 1;
+	if (btf_kind(local_type) != btf_kind(targ_type))
+		return 0;
+
+	switch (btf_kind(local_type)) {
+	case BTF_KIND_PTR:
+		return 1;
+	case BTF_KIND_FWD:
+	case BTF_KIND_ENUM: {
+		const char *local_name, *targ_name;
+		size_t local_len, targ_len;
+
+		local_name = btf__name_by_offset(local_btf,
+						 local_type->name_off);
+		targ_name = btf__name_by_offset(targ_btf, targ_type->name_off);
+		local_len = bpf_core_essential_name_len(local_name);
+		targ_len = bpf_core_essential_name_len(targ_name);
+		/* one of them is anonymous or both w/ same flavor-less names */
+		return local_len == 0 || targ_len == 0 ||
+		       (local_len == targ_len &&
+			strncmp(local_name, targ_name, local_len) == 0);
+	}
+	case BTF_KIND_INT:
+		/* just reject deprecated bitfield-like integers; all other
+		 * integers are by default compatible between each other
+		 */
+		return btf_int_offset(local_type) == 0 &&
+		       btf_int_offset(targ_type) == 0;
+	case BTF_KIND_ARRAY:
+		local_id = btf_array(local_type)->type;
+		targ_id = btf_array(targ_type)->type;
+		goto recur;
+	default:
+		pr_warn("unexpected kind %d relocated, local [%d], target [%d]\n",
+			btf_kind(local_type), local_id, targ_id);
+		return 0;
+	}
+}
+
+/*
+ * Given single high-level named field accessor in local type, find
+ * corresponding high-level accessor for a target type. Along the way,
+ * maintain low-level spec for target as well. Also keep updating target
+ * bit offset.
+ *
+ * Searching is performed through recursive exhaustive enumeration of all
+ * fields of a struct/union. If there are any anonymous (embedded)
+ * structs/unions, they are recursively searched as well. If field with
+ * desired name is found, check compatibility between local and target types,
+ * before returning result.
+ *
+ * 1 is returned, if field is found.
+ * 0 is returned if no compatible field is found.
+ * <0 is returned on error.
+ */
+static int bpf_core_match_member(const struct btf *local_btf,
+				 const struct bpf_core_accessor *local_acc,
+				 const struct btf *targ_btf,
+				 __u32 targ_id,
+				 struct bpf_core_spec *spec,
+				 __u32 *next_targ_id)
+{
+	const struct btf_type *local_type, *targ_type;
+	const struct btf_member *local_member, *m;
+	const char *local_name, *targ_name;
+	__u32 local_id;
+	int i, n, found;
+
+	targ_type = skip_mods_and_typedefs(targ_btf, targ_id, &targ_id);
+	if (!targ_type)
+		return -EINVAL;
+	if (!btf_is_composite(targ_type))
+		return 0;
+
+	local_id = local_acc->type_id;
+	local_type = btf__type_by_id(local_btf, local_id);
+	local_member = btf_members(local_type) + local_acc->idx;
+	local_name = btf__name_by_offset(local_btf, local_member->name_off);
+
+	n = btf_vlen(targ_type);
+	m = btf_members(targ_type);
+	for (i = 0; i < n; i++, m++) {
+		__u32 bit_offset;
+
+		bit_offset = btf_member_bit_offset(targ_type, i);
+
+		/* too deep struct/union/array nesting */
+		if (spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+			return -E2BIG;
+
+		/* speculate this member will be the good one */
+		spec->bit_offset += bit_offset;
+		spec->raw_spec[spec->raw_len++] = i;
+
+		targ_name = btf__name_by_offset(targ_btf, m->name_off);
+		if (str_is_empty(targ_name)) {
+			/* embedded struct/union, we need to go deeper */
+			found = bpf_core_match_member(local_btf, local_acc,
+						      targ_btf, m->type,
+						      spec, next_targ_id);
+			if (found) /* either found or error */
+				return found;
+		} else if (strcmp(local_name, targ_name) == 0) {
+			/* matching named field */
+			struct bpf_core_accessor *targ_acc;
+
+			targ_acc = &spec->spec[spec->len++];
+			targ_acc->type_id = targ_id;
+			targ_acc->idx = i;
+			targ_acc->name = targ_name;
+
+			*next_targ_id = m->type;
+			found = bpf_core_fields_are_compat(local_btf,
+							   local_member->type,
+							   targ_btf, m->type);
+			if (!found)
+				spec->len--; /* pop accessor */
+			return found;
+		}
+		/* member turned out not to be what we looked for */
+		spec->bit_offset -= bit_offset;
+		spec->raw_len--;
+	}
+
+	return 0;
+}
+
+/*
+ * Try to match local spec to a target type and, if successful, produce full
+ * target spec (high-level, low-level + bit offset).
+ */
+static int bpf_core_spec_match(struct bpf_core_spec *local_spec,
+			       const struct btf *targ_btf, __u32 targ_id,
+			       struct bpf_core_spec *targ_spec)
+{
+	const struct btf_type *targ_type;
+	const struct bpf_core_accessor *local_acc;
+	struct bpf_core_accessor *targ_acc;
+	int i, sz, matched;
+
+	memset(targ_spec, 0, sizeof(*targ_spec));
+	targ_spec->btf = targ_btf;
+
+	local_acc = &local_spec->spec[0];
+	targ_acc = &targ_spec->spec[0];
+
+	for (i = 0; i < local_spec->len; i++, local_acc++, targ_acc++) {
+		targ_type = skip_mods_and_typedefs(targ_spec->btf, targ_id,
+						   &targ_id);
+		if (!targ_type)
+			return -EINVAL;
+
+		if (local_acc->name) {
+			matched = bpf_core_match_member(local_spec->btf,
+							local_acc,
+							targ_btf, targ_id,
+							targ_spec, &targ_id);
+			if (matched <= 0)
+				return matched;
+		} else {
+			/* for i=0, targ_id is already treated as array element
+			 * type (because it's the original struct), for others
+			 * we should find array element type first
+			 */
+			if (i > 0) {
+				const struct btf_array *a;
+
+				if (!btf_is_array(targ_type))
+					return 0;
+
+				a = btf_array(targ_type);
+				if (local_acc->idx >= a->nelems)
+					return 0;
+				if (!skip_mods_and_typedefs(targ_btf, a->type,
+							    &targ_id))
+					return -EINVAL;
+			}
+
+			/* too deep struct/union/array nesting */
+			if (targ_spec->raw_len == BPF_CORE_SPEC_MAX_LEN)
+				return -E2BIG;
+
+			targ_acc->type_id = targ_id;
+			targ_acc->idx = local_acc->idx;
+			targ_acc->name = NULL;
+			targ_spec->len++;
+			targ_spec->raw_spec[targ_spec->raw_len] = targ_acc->idx;
+			targ_spec->raw_len++;
+
+			sz = btf__resolve_size(targ_btf, targ_id);
+			if (sz < 0)
+				return sz;
+			targ_spec->bit_offset += local_acc->idx * sz * 8;
+		}
+	}
+
+	return 1;
+}
+
+static int bpf_core_calc_field_relo(const struct bpf_program *prog,
+				    const struct bpf_field_reloc *relo,
+				    const struct bpf_core_spec *spec,
+				    __u32 *val, bool *validate)
+{
+	const struct bpf_core_accessor *acc = &spec->spec[spec->len - 1];
+	const struct btf_type *t = btf__type_by_id(spec->btf, acc->type_id);
+	__u32 byte_off, byte_sz, bit_off, bit_sz;
+	const struct btf_member *m;
+	const struct btf_type *mt;
+	bool bitfield;
+	__s64 sz;
+
+	/* a[n] accessor needs special handling */
+	if (!acc->name) {
+		if (relo->kind == BPF_FIELD_BYTE_OFFSET) {
+			*val = spec->bit_offset / 8;
+		} else if (relo->kind == BPF_FIELD_BYTE_SIZE) {
+			sz = btf__resolve_size(spec->btf, acc->type_id);
+			if (sz < 0)
+				return -EINVAL;
+			*val = sz;
+		} else {
+			pr_warn("prog '%s': relo %d at insn #%d can't be applied to array access\n",
+				bpf_program__title(prog, false),
+				relo->kind, relo->insn_off / 8);
+			return -EINVAL;
+		}
+		if (validate)
+			*validate = true;
+		return 0;
+	}
+
+	m = btf_members(t) + acc->idx;
+	mt = skip_mods_and_typedefs(spec->btf, m->type, NULL);
+	bit_off = spec->bit_offset;
+	bit_sz = btf_member_bitfield_size(t, acc->idx);
+
+	bitfield = bit_sz > 0;
+	if (bitfield) {
+		byte_sz = mt->size;
+		byte_off = bit_off / 8 / byte_sz * byte_sz;
+		/* figure out smallest int size necessary for bitfield load */
+		while (bit_off + bit_sz - byte_off * 8 > byte_sz * 8) {
+			if (byte_sz >= 8) {
+				/* bitfield can't be read with 64-bit read */
+				pr_warn("prog '%s': relo %d at insn #%d can't be satisfied for bitfield\n",
+					bpf_program__title(prog, false),
+					relo->kind, relo->insn_off / 8);
+				return -E2BIG;
+			}
+			byte_sz *= 2;
+			byte_off = bit_off / 8 / byte_sz * byte_sz;
+		}
+	} else {
+		sz = btf__resolve_size(spec->btf, m->type);
+		if (sz < 0)
+			return -EINVAL;
+		byte_sz = sz;
+		byte_off = spec->bit_offset / 8;
+		bit_sz = byte_sz * 8;
+	}
+
+	/* for bitfields, all the relocatable aspects are ambiguous and we
+	 * might disagree with compiler, so turn off validation of expected
+	 * value, except for signedness
+	 */
+	if (validate)
+		*validate = !bitfield;
+
+	switch (relo->kind) {
+	case BPF_FIELD_BYTE_OFFSET:
+		*val = byte_off;
+		break;
+	case BPF_FIELD_BYTE_SIZE:
+		*val = byte_sz;
+		break;
+	case BPF_FIELD_SIGNED:
+		/* enums will be assumed unsigned */
+		*val = btf_is_enum(mt) ||
+		       (btf_int_encoding(mt) & BTF_INT_SIGNED);
+		if (validate)
+			*validate = true; /* signedness is never ambiguous */
+		break;
+	case BPF_FIELD_LSHIFT_U64:
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+		*val = 64 - (bit_off + bit_sz - byte_off  * 8);
+#else
+		*val = (8 - byte_sz) * 8 + (bit_off - byte_off * 8);
+#endif
+		break;
+	case BPF_FIELD_RSHIFT_U64:
+		*val = 64 - bit_sz;
+		if (validate)
+			*validate = true; /* right shift is never ambiguous */
+		break;
+	case BPF_FIELD_EXISTS:
+	default:
+		pr_warn("prog '%s': unknown relo %d at insn #%d\n",
+			bpf_program__title(prog, false),
+			relo->kind, relo->insn_off / 8);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * Patch relocatable BPF instruction.
+ *
+ * Patched value is determined by relocation kind and target specification.
+ * For field existence relocation target spec will be NULL if field is not
+ * found.
+ * Expected insn->imm value is determined using relocation kind and local
+ * spec, and is checked before patching instruction. If actual insn->imm value
+ * is wrong, bail out with error.
+ *
+ * Currently three kinds of BPF instructions are supported:
+ * 1. rX = <imm> (assignment with immediate operand);
+ * 2. rX += <imm> (arithmetic operations with immediate operand);
+ */
+static int bpf_core_reloc_insn(struct bpf_program *prog,
+			       const struct bpf_field_reloc *relo,
+			       const struct bpf_core_spec *local_spec,
+			       const struct bpf_core_spec *targ_spec)
+{
+	bool failed = false, validate = true;
+	__u32 orig_val, new_val;
+	struct bpf_insn *insn;
+	int insn_idx, err;
+	__u8 class;
+
+	if (relo->insn_off % sizeof(struct bpf_insn))
+		return -EINVAL;
+	insn_idx = relo->insn_off / sizeof(struct bpf_insn);
+
+	if (relo->kind == BPF_FIELD_EXISTS) {
+		orig_val = 1; /* can't generate EXISTS relo w/o local field */
+		new_val = targ_spec ? 1 : 0;
+	} else if (!targ_spec) {
+		failed = true;
+		new_val = (__u32)-1;
+	} else {
+		err = bpf_core_calc_field_relo(prog, relo, local_spec,
+					       &orig_val, &validate);
+		if (err)
+			return err;
+		err = bpf_core_calc_field_relo(prog, relo, targ_spec,
+					       &new_val, NULL);
+		if (err)
+			return err;
+	}
+
+	insn = &prog->insns[insn_idx];
+	class = BPF_CLASS(insn->code);
+
+	if (class == BPF_ALU || class == BPF_ALU64) {
+		if (BPF_SRC(insn->code) != BPF_K)
+			return -EINVAL;
+		if (!failed && validate && insn->imm != orig_val) {
+			pr_warn("prog '%s': unexpected insn #%d value: got %u, exp %u -> %u\n",
+				bpf_program__title(prog, false), insn_idx,
+				insn->imm, orig_val, new_val);
+			return -EINVAL;
+		}
+		orig_val = insn->imm;
+		insn->imm = new_val;
+		pr_debug("prog '%s': patched insn #%d (ALU/ALU64)%s imm %u -> %u\n",
+			 bpf_program__title(prog, false), insn_idx,
+			 failed ? " w/ failed reloc" : "", orig_val, new_val);
+	} else {
+		pr_warn("prog '%s': trying to relocate unrecognized insn #%d, code:%x, src:%x, dst:%x, off:%x, imm:%x\n",
+			bpf_program__title(prog, false),
+			insn_idx, insn->code, insn->src_reg, insn->dst_reg,
+			insn->off, insn->imm);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct btf *btf_load_raw(const char *path)
+{
+	struct btf *btf;
+	size_t read_cnt;
+	struct stat st;
+	void *data;
+	FILE *f;
+
+	if (stat(path, &st))
+		return ERR_PTR(-errno);
+
+	data = malloc(st.st_size);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	f = fopen(path, "rb");
+	if (!f) {
+		btf = ERR_PTR(-errno);
+		goto cleanup;
+	}
+
+	read_cnt = fread(data, 1, st.st_size, f);
+	fclose(f);
+	if (read_cnt < st.st_size) {
+		btf = ERR_PTR(-EBADF);
+		goto cleanup;
+	}
+
+	btf = btf__new(data, read_cnt);
+
+cleanup:
+	free(data);
+	return btf;
+}
+
+/*
+ * Probe few well-known locations for vmlinux kernel image and try to load BTF
+ * data out of it to use for target BTF.
+ */
+static struct btf *bpf_core_find_kernel_btf(void)
+{
+	struct {
+		const char *path_fmt;
+		bool raw_btf;
+	} locations[] = {
+		/* try canonical vmlinux BTF through sysfs first */
+		{ "/sys/kernel/btf/vmlinux", true /* raw BTF */ },
+		/* fall back to trying to find vmlinux ELF on disk otherwise */
+		{ "/boot/vmlinux-%1$s" },
+		{ "/lib/modules/%1$s/vmlinux-%1$s" },
+		{ "/lib/modules/%1$s/build/vmlinux" },
+		{ "/usr/lib/modules/%1$s/kernel/vmlinux" },
+		{ "/usr/lib/debug/boot/vmlinux-%1$s" },
+		{ "/usr/lib/debug/boot/vmlinux-%1$s.debug" },
+		{ "/usr/lib/debug/lib/modules/%1$s/vmlinux" },
+	};
+	char path[PATH_MAX + 1];
+	struct utsname buf;
+	struct btf *btf;
+	int i;
+
+	uname(&buf);
+
+	for (i = 0; i < ARRAY_SIZE(locations); i++) {
+		snprintf(path, PATH_MAX, locations[i].path_fmt, buf.release);
+
+		if (access(path, R_OK))
+			continue;
+
+		if (locations[i].raw_btf)
+			btf = btf_load_raw(path);
+		else
+			btf = btf__parse_elf(path, NULL);
+
+		pr_debug("loading kernel BTF '%s': %ld\n",
+			 path, IS_ERR(btf) ? PTR_ERR(btf) : 0);
+		if (IS_ERR(btf))
+			continue;
+
+		return btf;
+	}
+
+	pr_warn("failed to find valid kernel BTF\n");
+	return ERR_PTR(-ESRCH);
+}
+
+/* Output spec definition in the format:
+ * [<type-id>] (<type-name>) + <raw-spec> => <offset>@<spec>,
+ * where <spec> is a C-syntax view of recorded field access, e.g.: x.a[3].b
+ */
+static void bpf_core_dump_spec(int level, const struct bpf_core_spec *spec)
+{
+	const struct btf_type *t;
+	const char *s;
+	__u32 type_id;
+	int i;
+
+	type_id = spec->spec[0].type_id;
+	t = btf__type_by_id(spec->btf, type_id);
+	s = btf__name_by_offset(spec->btf, t->name_off);
+	libbpf_print(level, "[%u] %s + ", type_id, s);
+
+	for (i = 0; i < spec->raw_len; i++)
+		libbpf_print(level, "%d%s", spec->raw_spec[i],
+			     i == spec->raw_len - 1 ? " => " : ":");
+
+	libbpf_print(level, "%u.%u @ &x",
+		     spec->bit_offset / 8, spec->bit_offset % 8);
+
+	for (i = 0; i < spec->len; i++) {
+		if (spec->spec[i].name)
+			libbpf_print(level, ".%s", spec->spec[i].name);
+		else
+			libbpf_print(level, "[%u]", spec->spec[i].idx);
+	}
+
+}
+
+static size_t bpf_core_hash_fn(const void *key, void *ctx)
+{
+	return (size_t)key;
+}
+
+static bool bpf_core_equal_fn(const void *k1, const void *k2, void *ctx)
+{
+	return k1 == k2;
+}
+
+static void *u32_as_hash_key(__u32 x)
+{
+	return (void *)(uintptr_t)x;
+}
+
+/*
+ * CO-RE relocate single instruction.
+ *
+ * The outline and important points of the algorithm:
+ * 1. For given local type, find corresponding candidate target types.
+ *    Candidate type is a type with the same "essential" name, ignoring
+ *    everything after last triple underscore (___). E.g., `sample`,
+ *    `sample___flavor_one`, `sample___flavor_another_one`, are all candidates
+ *    for each other. Names with triple underscore are referred to as
+ *    "flavors" and are useful, among other things, to allow to
+ *    specify/support incompatible variations of the same kernel struct, which
+ *    might differ between different kernel versions and/or build
+ *    configurations.
+ *
+ *    N.B. Struct "flavors" could be generated by bpftool's BTF-to-C
+ *    converter, when deduplicated BTF of a kernel still contains more than
+ *    one different types with the same name. In that case, ___2, ___3, etc
+ *    are appended starting from second name conflict. But start flavors are
+ *    also useful to be defined "locally", in BPF program, to extract same
+ *    data from incompatible changes between different kernel
+ *    versions/configurations. For instance, to handle field renames between
+ *    kernel versions, one can use two flavors of the struct name with the
+ *    same common name and use conditional relocations to extract that field,
+ *    depending on target kernel version.
+ * 2. For each candidate type, try to match local specification to this
+ *    candidate target type. Matching involves finding corresponding
+ *    high-level spec accessors, meaning that all named fields should match,
+ *    as well as all array accesses should be within the actual bounds. Also,
+ *    types should be compatible (see bpf_core_fields_are_compat for details).
+ * 3. It is supported and expected that there might be multiple flavors
+ *    matching the spec. As long as all the specs resolve to the same set of
+ *    offsets across all candidates, there is no error. If there is any
+ *    ambiguity, CO-RE relocation will fail. This is necessary to accomodate
+ *    imprefection of BTF deduplication, which can cause slight duplication of
+ *    the same BTF type, if some directly or indirectly referenced (by
+ *    pointer) type gets resolved to different actual types in different
+ *    object files. If such situation occurs, deduplicated BTF will end up
+ *    with two (or more) structurally identical types, which differ only in
+ *    types they refer to through pointer. This should be OK in most cases and
+ *    is not an error.
+ * 4. Candidate types search is performed by linearly scanning through all
+ *    types in target BTF. It is anticipated that this is overall more
+ *    efficient memory-wise and not significantly worse (if not better)
+ *    CPU-wise compared to prebuilding a map from all local type names to
+ *    a list of candidate type names. It's also sped up by caching resolved
+ *    list of matching candidates per each local "root" type ID, that has at
+ *    least one bpf_field_reloc associated with it. This list is shared
+ *    between multiple relocations for the same type ID and is updated as some
+ *    of the candidates are pruned due to structural incompatibility.
+ */
+static int bpf_core_reloc_field(struct bpf_program *prog,
+				 const struct bpf_field_reloc *relo,
+				 int relo_idx,
+				 const struct btf *local_btf,
+				 const struct btf *targ_btf,
+				 struct hashmap *cand_cache)
+{
+	const char *prog_name = bpf_program__title(prog, false);
+	struct bpf_core_spec local_spec, cand_spec, targ_spec;
+	const void *type_key = u32_as_hash_key(relo->type_id);
+	const struct btf_type *local_type, *cand_type;
+	const char *local_name, *cand_name;
+	struct ids_vec *cand_ids;
+	__u32 local_id, cand_id;
+	const char *spec_str;
+	int i, j, err;
+
+	local_id = relo->type_id;
+	local_type = btf__type_by_id(local_btf, local_id);
+	if (!local_type)
+		return -EINVAL;
+
+	local_name = btf__name_by_offset(local_btf, local_type->name_off);
+	if (str_is_empty(local_name))
+		return -EINVAL;
+
+	spec_str = btf__name_by_offset(local_btf, relo->access_str_off);
+	if (str_is_empty(spec_str))
+		return -EINVAL;
+
+	err = bpf_core_spec_parse(local_btf, local_id, spec_str, &local_spec);
+	if (err) {
+		pr_warn("prog '%s': relo #%d: parsing [%d] %s + %s failed: %d\n",
+			prog_name, relo_idx, local_id, local_name, spec_str,
+			err);
+		return -EINVAL;
+	}
+
+	pr_debug("prog '%s': relo #%d: kind %d, spec is ", prog_name, relo_idx,
+		 relo->kind);
+	bpf_core_dump_spec(LIBBPF_DEBUG, &local_spec);
+	libbpf_print(LIBBPF_DEBUG, "\n");
+
+	if (!hashmap__find(cand_cache, type_key, (void **)&cand_ids)) {
+		cand_ids = bpf_core_find_cands(local_btf, local_id, targ_btf);
+		if (IS_ERR(cand_ids)) {
+			pr_warn("prog '%s': relo #%d: target candidate search failed for [%d] %s: %ld",
+				prog_name, relo_idx, local_id, local_name,
+				PTR_ERR(cand_ids));
+			return PTR_ERR(cand_ids);
+		}
+		err = hashmap__set(cand_cache, type_key, cand_ids, NULL, NULL);
+		if (err) {
+			bpf_core_free_cands(cand_ids);
+			return err;
+		}
+	}
+
+	for (i = 0, j = 0; i < cand_ids->len; i++) {
+		cand_id = cand_ids->data[i];
+		cand_type = btf__type_by_id(targ_btf, cand_id);
+		cand_name = btf__name_by_offset(targ_btf, cand_type->name_off);
+
+		err = bpf_core_spec_match(&local_spec, targ_btf,
+					  cand_id, &cand_spec);
+		pr_debug("prog '%s': relo #%d: matching candidate #%d %s against spec ",
+			 prog_name, relo_idx, i, cand_name);
+		bpf_core_dump_spec(LIBBPF_DEBUG, &cand_spec);
+		libbpf_print(LIBBPF_DEBUG, ": %d\n", err);
+		if (err < 0) {
+			pr_warn("prog '%s': relo #%d: matching error: %d\n",
+				prog_name, relo_idx, err);
+			return err;
+		}
+		if (err == 0)
+			continue;
+
+		if (j == 0) {
+			targ_spec = cand_spec;
+		} else if (cand_spec.bit_offset != targ_spec.bit_offset) {
+			/* if there are many candidates, they should all
+			 * resolve to the same bit offset
+			 */
+			pr_warn("prog '%s': relo #%d: offset ambiguity: %u != %u\n",
+				prog_name, relo_idx, cand_spec.bit_offset,
+				targ_spec.bit_offset);
+			return -EINVAL;
+		}
+
+		cand_ids->data[j++] = cand_spec.spec[0].type_id;
+	}
+
+	/*
+	 * For BPF_FIELD_EXISTS relo or when relaxed CO-RE reloc mode is
+	 * requested, it's expected that we might not find any candidates.
+	 * In this case, if field wasn't found in any candidate, the list of
+	 * candidates shouldn't change at all, we'll just handle relocating
+	 * appropriately, depending on relo's kind.
+	 */
+	if (j > 0)
+		cand_ids->len = j;
+
+	if (j == 0 && !prog->obj->relaxed_core_relocs &&
+	    relo->kind != BPF_FIELD_EXISTS) {
+		pr_warn("prog '%s': relo #%d: no matching targets found for [%d] %s + %s\n",
+			prog_name, relo_idx, local_id, local_name, spec_str);
+		return -ESRCH;
+	}
+
+	/* bpf_core_reloc_insn should know how to handle missing targ_spec */
+	err = bpf_core_reloc_insn(prog, relo, &local_spec,
+				  j ? &targ_spec : NULL);
+	if (err) {
+		pr_warn("prog '%s': relo #%d: failed to patch insn at offset %d: %d\n",
+			prog_name, relo_idx, relo->insn_off, err);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int
+bpf_core_reloc_fields(struct bpf_object *obj, const char *targ_btf_path)
+{
+	const struct btf_ext_info_sec *sec;
+	const struct bpf_field_reloc *rec;
+	const struct btf_ext_info *seg;
+	struct hashmap_entry *entry;
+	struct hashmap *cand_cache = NULL;
+	struct bpf_program *prog;
+	struct btf *targ_btf;
+	const char *sec_name;
+	int i, err = 0;
+
+	if (targ_btf_path)
+		targ_btf = btf__parse_elf(targ_btf_path, NULL);
+	else
+		targ_btf = bpf_core_find_kernel_btf();
+	if (IS_ERR(targ_btf)) {
+		pr_warn("failed to get target BTF: %ld\n", PTR_ERR(targ_btf));
+		return PTR_ERR(targ_btf);
+	}
+
+	cand_cache = hashmap__new(bpf_core_hash_fn, bpf_core_equal_fn, NULL);
+	if (IS_ERR(cand_cache)) {
+		err = PTR_ERR(cand_cache);
+		goto out;
+	}
+
+	seg = &obj->btf_ext->field_reloc_info;
+	for_each_btf_ext_sec(seg, sec) {
+		sec_name = btf__name_by_offset(obj->btf, sec->sec_name_off);
+		if (str_is_empty(sec_name)) {
+			err = -EINVAL;
+			goto out;
+		}
+		prog = bpf_object__find_program_by_title(obj, sec_name);
+		if (!prog) {
+			pr_warn("failed to find program '%s' for CO-RE offset relocation\n",
+				sec_name);
+			err = -EINVAL;
+			goto out;
+		}
+
+		pr_debug("prog '%s': performing %d CO-RE offset relocs\n",
+			 sec_name, sec->num_info);
+
+		for_each_btf_ext_rec(seg, sec, i, rec) {
+			err = bpf_core_reloc_field(prog, rec, i, obj->btf,
+						   targ_btf, cand_cache);
+			if (err) {
+				pr_warn("prog '%s': relo #%d: failed to relocate: %d\n",
+					sec_name, i, err);
+				goto out;
+			}
+		}
+	}
+
+out:
+	btf__free(targ_btf);
+	if (!IS_ERR_OR_NULL(cand_cache)) {
+		hashmap__for_each_entry(cand_cache, entry, i) {
+			bpf_core_free_cands(entry->value);
+		}
+		hashmap__free(cand_cache);
+	}
+	return err;
+}
+
+static int
+bpf_object__relocate_core(struct bpf_object *obj, const char *targ_btf_path)
+{
+	int err = 0;
+
+	if (obj->btf_ext->field_reloc_info.len)
+		err = bpf_core_reloc_fields(obj, targ_btf_path);
+
+	return err;
+}
+
+static int
+bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj,
+			struct reloc_desc *relo)
+{
+	struct bpf_insn *insn, *new_insn;
+	struct bpf_program *text;
+	size_t new_cnt;
+	int err;
+
+	if (relo->type != RELO_CALL)
+		return -LIBBPF_ERRNO__RELOC;
+
+	if (prog->idx == obj->efile.text_shndx) {
+		pr_warn("relo in .text insn %d into off %d (insn #%d)\n",
+			relo->insn_idx, relo->sym_off, relo->sym_off / 8);
+		return -LIBBPF_ERRNO__RELOC;
+	}
+
+	if (prog->main_prog_cnt == 0) {
+		text = bpf_object__find_prog_by_idx(obj, obj->efile.text_shndx);
+		if (!text) {
+			pr_warn("no .text section found yet relo into text exist\n");
+			return -LIBBPF_ERRNO__RELOC;
+		}
+		new_cnt = prog->insns_cnt + text->insns_cnt;
+		new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
+		if (!new_insn) {
+			pr_warn("oom in prog realloc\n");
+			return -ENOMEM;
+		}
+		prog->insns = new_insn;
+
+		if (obj->btf_ext) {
+			err = bpf_program_reloc_btf_ext(prog, obj,
+							text->section_name,
+							prog->insns_cnt);
+			if (err)
+				return err;
+		}
+
+		memcpy(new_insn + prog->insns_cnt, text->insns,
+		       text->insns_cnt * sizeof(*insn));
+		prog->main_prog_cnt = prog->insns_cnt;
+		prog->insns_cnt = new_cnt;
+		pr_debug("added %zd insn from %s to prog %s\n",
+			 text->insns_cnt, text->section_name,
+			 prog->section_name);
+	}
+	insn = &prog->insns[relo->insn_idx];
+	insn->imm += relo->sym_off / 8 + prog->main_prog_cnt - relo->insn_idx;
+	return 0;
+}
+
+static int
+bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj)
+{
+	int i, err;
+
+	if (!prog)
+		return 0;
+
+	if (obj->btf_ext) {
+		err = bpf_program_reloc_btf_ext(prog, obj,
+						prog->section_name, 0);
+		if (err)
+			return err;
+	}
+
+	if (!prog->reloc_desc)
+		return 0;
+
+	for (i = 0; i < prog->nr_reloc; i++) {
+		struct reloc_desc *relo = &prog->reloc_desc[i];
+
+		if (relo->type == RELO_LD64 || relo->type == RELO_DATA) {
+			struct bpf_insn *insn = &prog->insns[relo->insn_idx];
+
+			if (relo->insn_idx + 1 >= (int)prog->insns_cnt) {
+				pr_warn("relocation out of range: '%s'\n",
+					prog->section_name);
+				return -LIBBPF_ERRNO__RELOC;
+			}
+
+			if (relo->type != RELO_DATA) {
+				insn[0].src_reg = BPF_PSEUDO_MAP_FD;
+			} else {
+				insn[0].src_reg = BPF_PSEUDO_MAP_VALUE;
+				insn[1].imm = insn[0].imm + relo->sym_off;
+			}
+			insn[0].imm = obj->maps[relo->map_idx].fd;
+		} else if (relo->type == RELO_CALL) {
+			err = bpf_program__reloc_text(prog, obj, relo);
+			if (err)
+				return err;
+		}
+	}
+
+	zfree(&prog->reloc_desc);
+	prog->nr_reloc = 0;
+	return 0;
+}
+
+static int
+bpf_object__relocate(struct bpf_object *obj, const char *targ_btf_path)
+{
+	struct bpf_program *prog;
+	size_t i;
+	int err;
+
+	if (obj->btf_ext) {
+		err = bpf_object__relocate_core(obj, targ_btf_path);
+		if (err) {
+			pr_warn("failed to perform CO-RE relocations: %d\n",
+				err);
+			return err;
+		}
+	}
+	for (i = 0; i < obj->nr_programs; i++) {
+		prog = &obj->programs[i];
+
+		err = bpf_program__relocate(prog, obj);
+		if (err) {
+			pr_warn("failed to relocate '%s'\n", prog->section_name);
+			return err;
+		}
+	}
+	return 0;
+}
+
+static int bpf_object__collect_reloc(struct bpf_object *obj)
+{
+	int i, err;
+
+	if (!obj_elf_valid(obj)) {
+		pr_warn("Internal error: elf object is closed\n");
+		return -LIBBPF_ERRNO__INTERNAL;
+	}
+
+	for (i = 0; i < obj->efile.nr_reloc_sects; i++) {
+		GElf_Shdr *shdr = &obj->efile.reloc_sects[i].shdr;
+		Elf_Data *data = obj->efile.reloc_sects[i].data;
+		int idx = shdr->sh_info;
+		struct bpf_program *prog;
+
+		if (shdr->sh_type != SHT_REL) {
+			pr_warn("internal error at %d\n", __LINE__);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		prog = bpf_object__find_prog_by_idx(obj, idx);
+		if (!prog) {
+			pr_warn("relocation failed: no section(%d)\n", idx);
+			return -LIBBPF_ERRNO__RELOC;
+		}
+
+		err = bpf_program__collect_reloc(prog, shdr, data, obj);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int
+load_program(struct bpf_program *prog, struct bpf_insn *insns, int insns_cnt,
+	     char *license, __u32 kern_version, int *pfd)
+{
+	struct bpf_load_program_attr load_attr;
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int log_buf_size = BPF_LOG_BUF_SIZE;
+	char *log_buf;
+	int btf_fd, ret;
+
+	if (!insns || !insns_cnt)
+		return -EINVAL;
+
+	memset(&load_attr, 0, sizeof(struct bpf_load_program_attr));
+	load_attr.prog_type = prog->type;
+	load_attr.expected_attach_type = prog->expected_attach_type;
+	if (prog->caps->name)
+		load_attr.name = prog->name;
+	load_attr.insns = insns;
+	load_attr.insns_cnt = insns_cnt;
+	load_attr.license = license;
+	if (prog->type == BPF_PROG_TYPE_TRACING) {
+		load_attr.attach_prog_fd = prog->attach_prog_fd;
+		load_attr.attach_btf_id = prog->attach_btf_id;
+	} else {
+		load_attr.kern_version = kern_version;
+		load_attr.prog_ifindex = prog->prog_ifindex;
+	}
+	/* if .BTF.ext was loaded, kernel supports associated BTF for prog */
+	if (prog->obj->btf_ext)
+		btf_fd = bpf_object__btf_fd(prog->obj);
+	else
+		btf_fd = -1;
+	load_attr.prog_btf_fd = btf_fd >= 0 ? btf_fd : 0;
+	load_attr.func_info = prog->func_info;
+	load_attr.func_info_rec_size = prog->func_info_rec_size;
+	load_attr.func_info_cnt = prog->func_info_cnt;
+	load_attr.line_info = prog->line_info;
+	load_attr.line_info_rec_size = prog->line_info_rec_size;
+	load_attr.line_info_cnt = prog->line_info_cnt;
+	load_attr.log_level = prog->log_level;
+	load_attr.prog_flags = prog->prog_flags;
+
+retry_load:
+	log_buf = malloc(log_buf_size);
+	if (!log_buf)
+		pr_warn("Alloc log buffer for bpf loader error, continue without log\n");
+
+	ret = bpf_load_program_xattr(&load_attr, log_buf, log_buf_size);
+
+	if (ret >= 0) {
+		if (load_attr.log_level)
+			pr_debug("verifier log:\n%s", log_buf);
+		*pfd = ret;
+		ret = 0;
+		goto out;
+	}
+
+	if (errno == ENOSPC) {
+		log_buf_size <<= 1;
+		free(log_buf);
+		goto retry_load;
+	}
+	ret = -errno;
+	cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+	pr_warn("load bpf program failed: %s\n", cp);
+
+	if (log_buf && log_buf[0] != '\0') {
+		ret = -LIBBPF_ERRNO__VERIFY;
+		pr_warn("-- BEGIN DUMP LOG ---\n");
+		pr_warn("\n%s\n", log_buf);
+		pr_warn("-- END LOG --\n");
+	} else if (load_attr.insns_cnt >= BPF_MAXINSNS) {
+		pr_warn("Program too large (%zu insns), at most %d insns\n",
+			load_attr.insns_cnt, BPF_MAXINSNS);
+		ret = -LIBBPF_ERRNO__PROG2BIG;
+	} else if (load_attr.prog_type != BPF_PROG_TYPE_KPROBE) {
+		/* Wrong program type? */
+		int fd;
+
+		load_attr.prog_type = BPF_PROG_TYPE_KPROBE;
+		load_attr.expected_attach_type = 0;
+		fd = bpf_load_program_xattr(&load_attr, NULL, 0);
+		if (fd >= 0) {
+			close(fd);
+			ret = -LIBBPF_ERRNO__PROGTYPE;
+			goto out;
+		}
+	}
+
+out:
+	free(log_buf);
+	return ret;
+}
+
+int
+bpf_program__load(struct bpf_program *prog,
+		  char *license, __u32 kern_version)
+{
+	int err = 0, fd, i;
+
+	if (prog->instances.nr < 0 || !prog->instances.fds) {
+		if (prog->preprocessor) {
+			pr_warn("Internal error: can't load program '%s'\n",
+				prog->section_name);
+			return -LIBBPF_ERRNO__INTERNAL;
+		}
+
+		prog->instances.fds = malloc(sizeof(int));
+		if (!prog->instances.fds) {
+			pr_warn("Not enough memory for BPF fds\n");
+			return -ENOMEM;
+		}
+		prog->instances.nr = 1;
+		prog->instances.fds[0] = -1;
+	}
+
+	if (!prog->preprocessor) {
+		if (prog->instances.nr != 1) {
+			pr_warn("Program '%s' is inconsistent: nr(%d) != 1\n",
+				prog->section_name, prog->instances.nr);
+		}
+		err = load_program(prog, prog->insns, prog->insns_cnt,
+				   license, kern_version, &fd);
+		if (!err)
+			prog->instances.fds[0] = fd;
+		goto out;
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		struct bpf_prog_prep_result result;
+		bpf_program_prep_t preprocessor = prog->preprocessor;
+
+		memset(&result, 0, sizeof(result));
+		err = preprocessor(prog, i, prog->insns,
+				   prog->insns_cnt, &result);
+		if (err) {
+			pr_warn("Preprocessing the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
+			goto out;
+		}
+
+		if (!result.new_insn_ptr || !result.new_insn_cnt) {
+			pr_debug("Skip loading the %dth instance of program '%s'\n",
+				 i, prog->section_name);
+			prog->instances.fds[i] = -1;
+			if (result.pfd)
+				*result.pfd = -1;
+			continue;
+		}
+
+		err = load_program(prog, result.new_insn_ptr,
+				   result.new_insn_cnt,
+				   license, kern_version, &fd);
+
+		if (err) {
+			pr_warn("Loading the %dth instance of program '%s' failed\n",
+				i, prog->section_name);
+			goto out;
+		}
+
+		if (result.pfd)
+			*result.pfd = fd;
+		prog->instances.fds[i] = fd;
+	}
+out:
+	if (err)
+		pr_warn("failed to load program '%s'\n", prog->section_name);
+	zfree(&prog->insns);
+	prog->insns_cnt = 0;
+	return err;
+}
+
+static bool bpf_program__is_function_storage(const struct bpf_program *prog,
+					     const struct bpf_object *obj)
+{
+	return prog->idx == obj->efile.text_shndx && obj->has_pseudo_calls;
+}
+
+static int
+bpf_object__load_progs(struct bpf_object *obj, int log_level)
+{
+	size_t i;
+	int err;
+
+	for (i = 0; i < obj->nr_programs; i++) {
+		if (bpf_program__is_function_storage(&obj->programs[i], obj))
+			continue;
+		obj->programs[i].log_level |= log_level;
+		err = bpf_program__load(&obj->programs[i],
+					obj->license,
+					obj->kern_version);
+		if (err)
+			return err;
+	}
+	return 0;
+}
+
+static int libbpf_find_attach_btf_id(const char *name,
+				     enum bpf_attach_type attach_type,
+				     __u32 attach_prog_fd);
+static struct bpf_object *
+__bpf_object__open(const char *path, const void *obj_buf, size_t obj_buf_sz,
+		   struct bpf_object_open_opts *opts)
+{
+	const char *pin_root_path;
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	const char *obj_name;
+	char tmp_name[64];
+	bool relaxed_maps;
+	__u32 attach_prog_fd;
+	int err;
+
+	if (elf_version(EV_CURRENT) == EV_NONE) {
+		pr_warn("failed to init libelf for %s\n",
+			path ? : "(mem buf)");
+		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
+	}
+
+	if (!OPTS_VALID(opts, bpf_object_open_opts))
+		return ERR_PTR(-EINVAL);
+
+	obj_name = OPTS_GET(opts, object_name, NULL);
+	if (obj_buf) {
+		if (!obj_name) {
+			snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx",
+				 (unsigned long)obj_buf,
+				 (unsigned long)obj_buf_sz);
+			obj_name = tmp_name;
+		}
+		path = obj_name;
+		pr_debug("loading object '%s' from buffer\n", obj_name);
+	}
+
+	obj = bpf_object__new(path, obj_buf, obj_buf_sz, obj_name);
+	if (IS_ERR(obj))
+		return obj;
+
+	obj->relaxed_core_relocs = OPTS_GET(opts, relaxed_core_relocs, false);
+	relaxed_maps = OPTS_GET(opts, relaxed_maps, false);
+	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
+	attach_prog_fd = OPTS_GET(opts, attach_prog_fd, 0);
+
+	CHECK_ERR(bpf_object__elf_init(obj), err, out);
+	CHECK_ERR(bpf_object__check_endianness(obj), err, out);
+	CHECK_ERR(bpf_object__probe_caps(obj), err, out);
+	CHECK_ERR(bpf_object__elf_collect(obj, relaxed_maps, pin_root_path),
+		  err, out);
+	CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
+	bpf_object__elf_finish(obj);
+
+	bpf_object__for_each_program(prog, obj) {
+		enum bpf_prog_type prog_type;
+		enum bpf_attach_type attach_type;
+
+		err = libbpf_prog_type_by_name(prog->section_name, &prog_type,
+					       &attach_type);
+		if (err == -ESRCH)
+			/* couldn't guess, but user might manually specify */
+			continue;
+		if (err)
+			goto out;
+
+		bpf_program__set_type(prog, prog_type);
+		bpf_program__set_expected_attach_type(prog, attach_type);
+		if (prog_type == BPF_PROG_TYPE_TRACING) {
+			err = libbpf_find_attach_btf_id(prog->section_name,
+							attach_type,
+							attach_prog_fd);
+			if (err <= 0)
+				goto out;
+			prog->attach_btf_id = err;
+			prog->attach_prog_fd = attach_prog_fd;
+		}
+	}
+
+	return obj;
+out:
+	bpf_object__close(obj);
+	return ERR_PTR(err);
+}
+
+static struct bpf_object *
+__bpf_object__open_xattr(struct bpf_object_open_attr *attr, int flags)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.relaxed_maps = flags & MAPS_RELAX_COMPAT,
+	);
+
+	/* param validation */
+	if (!attr->file)
+		return NULL;
+
+	pr_debug("loading %s\n", attr->file);
+	return __bpf_object__open(attr->file, NULL, 0, &opts);
+}
+
+struct bpf_object *bpf_object__open_xattr(struct bpf_object_open_attr *attr)
+{
+	return __bpf_object__open_xattr(attr, 0);
+}
+
+struct bpf_object *bpf_object__open(const char *path)
+{
+	struct bpf_object_open_attr attr = {
+		.file		= path,
+		.prog_type	= BPF_PROG_TYPE_UNSPEC,
+	};
+
+	return bpf_object__open_xattr(&attr);
+}
+
+struct bpf_object *
+bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts)
+{
+	if (!path)
+		return ERR_PTR(-EINVAL);
+
+	pr_debug("loading %s\n", path);
+
+	return __bpf_object__open(path, NULL, 0, opts);
+}
+
+struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     struct bpf_object_open_opts *opts)
+{
+	if (!obj_buf || obj_buf_sz == 0)
+		return ERR_PTR(-EINVAL);
+
+	return __bpf_object__open(NULL, obj_buf, obj_buf_sz, opts);
+}
+
+struct bpf_object *
+bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
+			const char *name)
+{
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts,
+		.object_name = name,
+		/* wrong default, but backwards-compatible */
+		.relaxed_maps = true,
+	);
+
+	/* returning NULL is wrong, but backwards-compatible */
+	if (!obj_buf || obj_buf_sz == 0)
+		return NULL;
+
+	return bpf_object__open_mem(obj_buf, obj_buf_sz, &opts);
+}
+
+int bpf_object__unload(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return -EINVAL;
+
+	for (i = 0; i < obj->nr_maps; i++)
+		zclose(obj->maps[i].fd);
+
+	for (i = 0; i < obj->nr_programs; i++)
+		bpf_program__unload(&obj->programs[i]);
+
+	return 0;
+}
+
+int bpf_object__load_xattr(struct bpf_object_load_attr *attr)
+{
+	struct bpf_object *obj;
+	int err, i;
+
+	if (!attr)
+		return -EINVAL;
+	obj = attr->obj;
+	if (!obj)
+		return -EINVAL;
+
+	if (obj->loaded) {
+		pr_warn("object should not be loaded twice\n");
+		return -EINVAL;
+	}
+
+	obj->loaded = true;
+
+	CHECK_ERR(bpf_object__create_maps(obj), err, out);
+	CHECK_ERR(bpf_object__relocate(obj, attr->target_btf_path), err, out);
+	CHECK_ERR(bpf_object__load_progs(obj, attr->log_level), err, out);
+
+	return 0;
+out:
+	/* unpin any maps that were auto-pinned during load */
+	for (i = 0; i < obj->nr_maps; i++)
+		if (obj->maps[i].pinned && !obj->maps[i].reused)
+			bpf_map__unpin(&obj->maps[i], NULL);
+
+	bpf_object__unload(obj);
+	pr_warn("failed to load object '%s'\n", obj->path);
+	return err;
+}
+
+int bpf_object__load(struct bpf_object *obj)
+{
+	struct bpf_object_load_attr attr = {
+		.obj = obj,
+	};
+
+	return bpf_object__load_xattr(&attr);
+}
+
+static int make_parent_dir(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	char *dname, *dir;
+	int err = 0;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (mkdir(dir, 0700) && errno != EEXIST)
+		err = -errno;
+
+	free(dname);
+	if (err) {
+		cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+		pr_warn("failed to mkdir %s: %s\n", path, cp);
+	}
+	return err;
+}
+
+static int check_path(const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	struct statfs st_fs;
+	char *dname, *dir;
+	int err = 0;
+
+	if (path == NULL)
+		return -EINVAL;
+
+	dname = strdup(path);
+	if (dname == NULL)
+		return -ENOMEM;
+
+	dir = dirname(dname);
+	if (statfs(dir, &st_fs)) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("failed to statfs %s: %s\n", dir, cp);
+		err = -errno;
+	}
+	free(dname);
+
+	if (!err && st_fs.f_type != BPF_FS_MAGIC) {
+		pr_warn("specified path %s is not on BPF FS\n", path);
+		err = -EINVAL;
+	}
+
+	return err;
+}
+
+int bpf_program__pin_instance(struct bpf_program *prog, const char *path,
+			      int instance)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	err = make_parent_dir(path);
+	if (err)
+		return err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (instance < 0 || instance >= prog->instances.nr) {
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	if (bpf_obj_pin(prog->instances.fds[instance], path)) {
+		cp = libbpf_strerror_r(errno, errmsg, sizeof(errmsg));
+		pr_warn("failed to pin program: %s\n", cp);
+		return -errno;
+	}
+	pr_debug("pinned program '%s'\n", path);
+
+	return 0;
+}
+
+int bpf_program__unpin_instance(struct bpf_program *prog, const char *path,
+				int instance)
+{
+	int err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (instance < 0 || instance >= prog->instances.nr) {
+		pr_warn("invalid prog instance %d of prog %s (max %d)\n",
+			instance, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	err = unlink(path);
+	if (err != 0)
+		return -errno;
+	pr_debug("unpinned program '%s'\n", path);
+
+	return 0;
+}
+
+int bpf_program__pin(struct bpf_program *prog, const char *path)
+{
+	int i, err;
+
+	err = make_parent_dir(path);
+	if (err)
+		return err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr <= 0) {
+		pr_warn("no instances of prog %s to pin\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr == 1) {
+		/* don't create subdirs when pinning single instance */
+		return bpf_program__pin_instance(prog, path, 0);
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0) {
+			err = -EINVAL;
+			goto err_unpin;
+		} else if (len >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto err_unpin;
+		}
+
+		err = bpf_program__pin_instance(prog, buf, i);
+		if (err)
+			goto err_unpin;
+	}
+
+	return 0;
+
+err_unpin:
+	for (i = i - 1; i >= 0; i--) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0)
+			continue;
+		else if (len >= PATH_MAX)
+			continue;
+
+		bpf_program__unpin_instance(prog, buf, i);
+	}
+
+	rmdir(path);
+
+	return err;
+}
+
+int bpf_program__unpin(struct bpf_program *prog, const char *path)
+{
+	int i, err;
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	if (prog == NULL) {
+		pr_warn("invalid program pointer\n");
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr <= 0) {
+		pr_warn("no instances of prog %s to pin\n",
+			   prog->section_name);
+		return -EINVAL;
+	}
+
+	if (prog->instances.nr == 1) {
+		/* don't create subdirs when pinning single instance */
+		return bpf_program__unpin_instance(prog, path, 0);
+	}
+
+	for (i = 0; i < prog->instances.nr; i++) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%d", path, i);
+		if (len < 0)
+			return -EINVAL;
+		else if (len >= PATH_MAX)
+			return -ENAMETOOLONG;
+
+		err = bpf_program__unpin_instance(prog, buf, i);
+		if (err)
+			return err;
+	}
+
+	err = rmdir(path);
+	if (err)
+		return -errno;
+
+	return 0;
+}
+
+int bpf_map__pin(struct bpf_map *map, const char *path)
+{
+	char *cp, errmsg[STRERR_BUFSIZE];
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return -EINVAL;
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return -EINVAL;
+		} else if (map->pinned) {
+			pr_debug("map '%s' already pinned at '%s'; not re-pinning\n",
+				 bpf_map__name(map), map->pin_path);
+			return 0;
+		}
+	} else {
+		if (!path) {
+			pr_warn("missing a path to pin map '%s' at\n",
+				bpf_map__name(map));
+			return -EINVAL;
+		} else if (map->pinned) {
+			pr_warn("map '%s' already pinned\n", bpf_map__name(map));
+			return -EEXIST;
+		}
+
+		map->pin_path = strdup(path);
+		if (!map->pin_path) {
+			err = -errno;
+			goto out_err;
+		}
+	}
+
+	err = make_parent_dir(map->pin_path);
+	if (err)
+		return err;
+
+	err = check_path(map->pin_path);
+	if (err)
+		return err;
+
+	if (bpf_obj_pin(map->fd, map->pin_path)) {
+		err = -errno;
+		goto out_err;
+	}
+
+	map->pinned = true;
+	pr_debug("pinned map '%s'\n", map->pin_path);
+
+	return 0;
+
+out_err:
+	cp = libbpf_strerror_r(-err, errmsg, sizeof(errmsg));
+	pr_warn("failed to pin map: %s\n", cp);
+	return err;
+}
+
+int bpf_map__unpin(struct bpf_map *map, const char *path)
+{
+	int err;
+
+	if (map == NULL) {
+		pr_warn("invalid map pointer\n");
+		return -EINVAL;
+	}
+
+	if (map->pin_path) {
+		if (path && strcmp(path, map->pin_path)) {
+			pr_warn("map '%s' already has pin path '%s' different from '%s'\n",
+				bpf_map__name(map), map->pin_path, path);
+			return -EINVAL;
+		}
+		path = map->pin_path;
+	} else if (!path) {
+		pr_warn("no path to unpin map '%s' from\n",
+			bpf_map__name(map));
+		return -EINVAL;
+	}
+
+	err = check_path(path);
+	if (err)
+		return err;
+
+	err = unlink(path);
+	if (err != 0)
+		return -errno;
+
+	map->pinned = false;
+	pr_debug("unpinned map '%s' from '%s'\n", bpf_map__name(map), path);
+
+	return 0;
+}
+
+int bpf_map__set_pin_path(struct bpf_map *map, const char *path)
+{
+	char *new = NULL;
+
+	if (path) {
+		new = strdup(path);
+		if (!new)
+			return -errno;
+	}
+
+	free(map->pin_path);
+	map->pin_path = new;
+	return 0;
+}
+
+const char *bpf_map__get_pin_path(const struct bpf_map *map)
+{
+	return map->pin_path;
+}
+
+bool bpf_map__is_pinned(const struct bpf_map *map)
+{
+	return map->pinned;
+}
+
+int bpf_object__pin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return -ENOENT;
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			int len;
+
+			len = snprintf(buf, PATH_MAX, "%s/%s", path,
+				       bpf_map__name(map));
+			if (len < 0) {
+				err = -EINVAL;
+				goto err_unpin_maps;
+			} else if (len >= PATH_MAX) {
+				err = -ENAMETOOLONG;
+				goto err_unpin_maps;
+			}
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__pin(map, pin_path);
+		if (err)
+			goto err_unpin_maps;
+	}
+
+	return 0;
+
+err_unpin_maps:
+	while ((map = bpf_map__prev(map, obj))) {
+		if (!map->pin_path)
+			continue;
+
+		bpf_map__unpin(map, NULL);
+	}
+
+	return err;
+}
+
+int bpf_object__unpin_maps(struct bpf_object *obj, const char *path)
+{
+	struct bpf_map *map;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	bpf_object__for_each_map(map, obj) {
+		char *pin_path = NULL;
+		char buf[PATH_MAX];
+
+		if (path) {
+			int len;
+
+			len = snprintf(buf, PATH_MAX, "%s/%s", path,
+				       bpf_map__name(map));
+			if (len < 0)
+				return -EINVAL;
+			else if (len >= PATH_MAX)
+				return -ENAMETOOLONG;
+			pin_path = buf;
+		} else if (!map->pin_path) {
+			continue;
+		}
+
+		err = bpf_map__unpin(map, pin_path);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int bpf_object__pin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	if (!obj->loaded) {
+		pr_warn("object not yet loaded; load it first\n");
+		return -ENOENT;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0) {
+			err = -EINVAL;
+			goto err_unpin_programs;
+		} else if (len >= PATH_MAX) {
+			err = -ENAMETOOLONG;
+			goto err_unpin_programs;
+		}
+
+		err = bpf_program__pin(prog, buf);
+		if (err)
+			goto err_unpin_programs;
+	}
+
+	return 0;
+
+err_unpin_programs:
+	while ((prog = bpf_program__prev(prog, obj))) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0)
+			continue;
+		else if (len >= PATH_MAX)
+			continue;
+
+		bpf_program__unpin(prog, buf);
+	}
+
+	return err;
+}
+
+int bpf_object__unpin_programs(struct bpf_object *obj, const char *path)
+{
+	struct bpf_program *prog;
+	int err;
+
+	if (!obj)
+		return -ENOENT;
+
+	bpf_object__for_each_program(prog, obj) {
+		char buf[PATH_MAX];
+		int len;
+
+		len = snprintf(buf, PATH_MAX, "%s/%s", path,
+			       prog->pin_name);
+		if (len < 0)
+			return -EINVAL;
+		else if (len >= PATH_MAX)
+			return -ENAMETOOLONG;
+
+		err = bpf_program__unpin(prog, buf);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+int bpf_object__pin(struct bpf_object *obj, const char *path)
+{
+	int err;
+
+	err = bpf_object__pin_maps(obj, path);
+	if (err)
+		return err;
+
+	err = bpf_object__pin_programs(obj, path);
+	if (err) {
+		bpf_object__unpin_maps(obj, path);
+		return err;
+	}
+
+	return 0;
+}
+
+void bpf_object__close(struct bpf_object *obj)
+{
+	size_t i;
+
+	if (!obj)
+		return;
+
+	if (obj->clear_priv)
+		obj->clear_priv(obj, obj->priv);
+
+	bpf_object__elf_finish(obj);
+	bpf_object__unload(obj);
+	btf__free(obj->btf);
+	btf_ext__free(obj->btf_ext);
+
+	for (i = 0; i < obj->nr_maps; i++) {
+		zfree(&obj->maps[i].name);
+		zfree(&obj->maps[i].pin_path);
+		if (obj->maps[i].clear_priv)
+			obj->maps[i].clear_priv(&obj->maps[i],
+						obj->maps[i].priv);
+		obj->maps[i].priv = NULL;
+		obj->maps[i].clear_priv = NULL;
+	}
+
+	zfree(&obj->sections.rodata);
+	zfree(&obj->sections.data);
+	zfree(&obj->maps);
+	obj->nr_maps = 0;
+
+	if (obj->programs && obj->nr_programs) {
+		for (i = 0; i < obj->nr_programs; i++)
+			bpf_program__exit(&obj->programs[i]);
+	}
+	zfree(&obj->programs);
+
+	list_del(&obj->list);
+	free(obj);
+}
+
+struct bpf_object *
+bpf_object__next(struct bpf_object *prev)
+{
+	struct bpf_object *next;
+
+	if (!prev)
+		next = list_first_entry(&bpf_objects_list,
+					struct bpf_object,
+					list);
+	else
+		next = list_next_entry(prev, list);
+
+	/* Empty list is noticed here so don't need checking on entry. */
+	if (&next->list == &bpf_objects_list)
+		return NULL;
+
+	return next;
+}
+
+const char *bpf_object__name(const struct bpf_object *obj)
+{
+	return obj ? obj->name : ERR_PTR(-EINVAL);
+}
+
+unsigned int bpf_object__kversion(const struct bpf_object *obj)
+{
+	return obj ? obj->kern_version : 0;
+}
+
+struct btf *bpf_object__btf(const struct bpf_object *obj)
+{
+	return obj ? obj->btf : NULL;
+}
+
+int bpf_object__btf_fd(const struct bpf_object *obj)
+{
+	return obj->btf ? btf__fd(obj->btf) : -1;
+}
+
+int bpf_object__set_priv(struct bpf_object *obj, void *priv,
+			 bpf_object_clear_priv_t clear_priv)
+{
+	if (obj->priv && obj->clear_priv)
+		obj->clear_priv(obj, obj->priv);
+
+	obj->priv = priv;
+	obj->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_object__priv(const struct bpf_object *obj)
+{
+	return obj ? obj->priv : ERR_PTR(-EINVAL);
+}
+
+static struct bpf_program *
+__bpf_program__iter(const struct bpf_program *p, const struct bpf_object *obj,
+		    bool forward)
+{
+	size_t nr_programs = obj->nr_programs;
+	ssize_t idx;
+
+	if (!nr_programs)
+		return NULL;
+
+	if (!p)
+		/* Iter from the beginning */
+		return forward ? &obj->programs[0] :
+			&obj->programs[nr_programs - 1];
+
+	if (p->obj != obj) {
+		pr_warn("error: program handler doesn't match object\n");
+		return NULL;
+	}
+
+	idx = (p - obj->programs) + (forward ? 1 : -1);
+	if (idx >= obj->nr_programs || idx < 0)
+		return NULL;
+	return &obj->programs[idx];
+}
+
+struct bpf_program *
+bpf_program__next(struct bpf_program *prev, const struct bpf_object *obj)
+{
+	struct bpf_program *prog = prev;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, true);
+	} while (prog && bpf_program__is_function_storage(prog, obj));
+
+	return prog;
+}
+
+struct bpf_program *
+bpf_program__prev(struct bpf_program *next, const struct bpf_object *obj)
+{
+	struct bpf_program *prog = next;
+
+	do {
+		prog = __bpf_program__iter(prog, obj, false);
+	} while (prog && bpf_program__is_function_storage(prog, obj));
+
+	return prog;
+}
+
+int bpf_program__set_priv(struct bpf_program *prog, void *priv,
+			  bpf_program_clear_priv_t clear_priv)
+{
+	if (prog->priv && prog->clear_priv)
+		prog->clear_priv(prog, prog->priv);
+
+	prog->priv = priv;
+	prog->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_program__priv(const struct bpf_program *prog)
+{
+	return prog ? prog->priv : ERR_PTR(-EINVAL);
+}
+
+void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
+{
+	prog->prog_ifindex = ifindex;
+}
+
+const char *bpf_program__title(const struct bpf_program *prog, bool needs_copy)
+{
+	const char *title;
+
+	title = prog->section_name;
+	if (needs_copy) {
+		title = strdup(title);
+		if (!title) {
+			pr_warn("failed to strdup program title\n");
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	return title;
+}
+
+int bpf_program__fd(const struct bpf_program *prog)
+{
+	return bpf_program__nth_fd(prog, 0);
+}
+
+size_t bpf_program__size(const struct bpf_program *prog)
+{
+	return prog->insns_cnt * sizeof(struct bpf_insn);
+}
+
+int bpf_program__set_prep(struct bpf_program *prog, int nr_instances,
+			  bpf_program_prep_t prep)
+{
+	int *instances_fds;
+
+	if (nr_instances <= 0 || !prep)
+		return -EINVAL;
+
+	if (prog->instances.nr > 0 || prog->instances.fds) {
+		pr_warn("Can't set pre-processor after loading\n");
+		return -EINVAL;
+	}
+
+	instances_fds = malloc(sizeof(int) * nr_instances);
+	if (!instances_fds) {
+		pr_warn("alloc memory failed for fds\n");
+		return -ENOMEM;
+	}
+
+	/* fill all fd with -1 */
+	memset(instances_fds, -1, sizeof(int) * nr_instances);
+
+	prog->instances.nr = nr_instances;
+	prog->instances.fds = instances_fds;
+	prog->preprocessor = prep;
+	return 0;
+}
+
+int bpf_program__nth_fd(const struct bpf_program *prog, int n)
+{
+	int fd;
+
+	if (!prog)
+		return -EINVAL;
+
+	if (n >= prog->instances.nr || n < 0) {
+		pr_warn("Can't get the %dth fd from program %s: only %d instances\n",
+			n, prog->section_name, prog->instances.nr);
+		return -EINVAL;
+	}
+
+	fd = prog->instances.fds[n];
+	if (fd < 0) {
+		pr_warn("%dth instance of program '%s' is invalid\n",
+			n, prog->section_name);
+		return -ENOENT;
+	}
+
+	return fd;
+}
+
+enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog)
+{
+	return prog->type;
+}
+
+void bpf_program__set_type(struct bpf_program *prog, enum bpf_prog_type type)
+{
+	prog->type = type;
+}
+
+static bool bpf_program__is_type(const struct bpf_program *prog,
+				 enum bpf_prog_type type)
+{
+	return prog ? (prog->type == type) : false;
+}
+
+#define BPF_PROG_TYPE_FNS(NAME, TYPE)				\
+int bpf_program__set_##NAME(struct bpf_program *prog)		\
+{								\
+	if (!prog)						\
+		return -EINVAL;					\
+	bpf_program__set_type(prog, TYPE);			\
+	return 0;						\
+}								\
+								\
+bool bpf_program__is_##NAME(const struct bpf_program *prog)	\
+{								\
+	return bpf_program__is_type(prog, TYPE);		\
+}								\
+
+BPF_PROG_TYPE_FNS(socket_filter, BPF_PROG_TYPE_SOCKET_FILTER);
+BPF_PROG_TYPE_FNS(kprobe, BPF_PROG_TYPE_KPROBE);
+BPF_PROG_TYPE_FNS(sched_cls, BPF_PROG_TYPE_SCHED_CLS);
+BPF_PROG_TYPE_FNS(sched_act, BPF_PROG_TYPE_SCHED_ACT);
+BPF_PROG_TYPE_FNS(tracepoint, BPF_PROG_TYPE_TRACEPOINT);
+BPF_PROG_TYPE_FNS(raw_tracepoint, BPF_PROG_TYPE_RAW_TRACEPOINT);
+BPF_PROG_TYPE_FNS(xdp, BPF_PROG_TYPE_XDP);
+BPF_PROG_TYPE_FNS(perf_event, BPF_PROG_TYPE_PERF_EVENT);
+BPF_PROG_TYPE_FNS(tracing, BPF_PROG_TYPE_TRACING);
+
+enum bpf_attach_type
+bpf_program__get_expected_attach_type(struct bpf_program *prog)
+{
+	return prog->expected_attach_type;
+}
+
+void bpf_program__set_expected_attach_type(struct bpf_program *prog,
+					   enum bpf_attach_type type)
+{
+	prog->expected_attach_type = type;
+}
+
+#define BPF_PROG_SEC_IMPL(string, ptype, eatype, is_attachable, btf, atype) \
+	{ string, sizeof(string) - 1, ptype, eatype, is_attachable, btf, atype }
+
+/* Programs that can NOT be attached. */
+#define BPF_PROG_SEC(string, ptype) BPF_PROG_SEC_IMPL(string, ptype, 0, 0, 0, 0)
+
+/* Programs that can be attached. */
+#define BPF_APROG_SEC(string, ptype, atype) \
+	BPF_PROG_SEC_IMPL(string, ptype, 0, 1, 0, atype)
+
+/* Programs that must specify expected attach type at load time. */
+#define BPF_EAPROG_SEC(string, ptype, eatype) \
+	BPF_PROG_SEC_IMPL(string, ptype, eatype, 1, 0, eatype)
+
+/* Programs that use BTF to identify attach point */
+#define BPF_PROG_BTF(string, ptype, eatype) \
+	BPF_PROG_SEC_IMPL(string, ptype, eatype, 0, 1, 0)
+
+/* Programs that can be attached but attach type can't be identified by section
+ * name. Kept for backward compatibility.
+ */
+#define BPF_APROG_COMPAT(string, ptype) BPF_PROG_SEC(string, ptype)
+
+static const struct {
+	const char *sec;
+	size_t len;
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	bool is_attachable;
+	bool is_attach_btf;
+	enum bpf_attach_type attach_type;
+} section_names[] = {
+	BPF_PROG_SEC("socket",			BPF_PROG_TYPE_SOCKET_FILTER),
+	BPF_PROG_SEC("kprobe/",			BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uprobe/",			BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("kretprobe/",		BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("uretprobe/",		BPF_PROG_TYPE_KPROBE),
+	BPF_PROG_SEC("classifier",		BPF_PROG_TYPE_SCHED_CLS),
+	BPF_PROG_SEC("action",			BPF_PROG_TYPE_SCHED_ACT),
+	BPF_PROG_SEC("tracepoint/",		BPF_PROG_TYPE_TRACEPOINT),
+	BPF_PROG_SEC("tp/",			BPF_PROG_TYPE_TRACEPOINT),
+	BPF_PROG_SEC("raw_tracepoint/",		BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_SEC("raw_tp/",			BPF_PROG_TYPE_RAW_TRACEPOINT),
+	BPF_PROG_BTF("tp_btf/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_RAW_TP),
+	BPF_PROG_BTF("fentry/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_FENTRY),
+	BPF_PROG_BTF("fexit/",			BPF_PROG_TYPE_TRACING,
+						BPF_TRACE_FEXIT),
+	BPF_PROG_SEC("xdp",			BPF_PROG_TYPE_XDP),
+	BPF_PROG_SEC("perf_event",		BPF_PROG_TYPE_PERF_EVENT),
+	BPF_PROG_SEC("lwt_in",			BPF_PROG_TYPE_LWT_IN),
+	BPF_PROG_SEC("lwt_out",			BPF_PROG_TYPE_LWT_OUT),
+	BPF_PROG_SEC("lwt_xmit",		BPF_PROG_TYPE_LWT_XMIT),
+	BPF_PROG_SEC("lwt_seg6local",		BPF_PROG_TYPE_LWT_SEG6LOCAL),
+	BPF_APROG_SEC("cgroup_skb/ingress",	BPF_PROG_TYPE_CGROUP_SKB,
+						BPF_CGROUP_INET_INGRESS),
+	BPF_APROG_SEC("cgroup_skb/egress",	BPF_PROG_TYPE_CGROUP_SKB,
+						BPF_CGROUP_INET_EGRESS),
+	BPF_APROG_COMPAT("cgroup/skb",		BPF_PROG_TYPE_CGROUP_SKB),
+	BPF_APROG_SEC("cgroup/sock",		BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET_SOCK_CREATE),
+	BPF_EAPROG_SEC("cgroup/post_bind4",	BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET4_POST_BIND),
+	BPF_EAPROG_SEC("cgroup/post_bind6",	BPF_PROG_TYPE_CGROUP_SOCK,
+						BPF_CGROUP_INET6_POST_BIND),
+	BPF_APROG_SEC("cgroup/dev",		BPF_PROG_TYPE_CGROUP_DEVICE,
+						BPF_CGROUP_DEVICE),
+	BPF_APROG_SEC("sockops",		BPF_PROG_TYPE_SOCK_OPS,
+						BPF_CGROUP_SOCK_OPS),
+	BPF_APROG_SEC("sk_skb/stream_parser",	BPF_PROG_TYPE_SK_SKB,
+						BPF_SK_SKB_STREAM_PARSER),
+	BPF_APROG_SEC("sk_skb/stream_verdict",	BPF_PROG_TYPE_SK_SKB,
+						BPF_SK_SKB_STREAM_VERDICT),
+	BPF_APROG_COMPAT("sk_skb",		BPF_PROG_TYPE_SK_SKB),
+	BPF_APROG_SEC("sk_msg",			BPF_PROG_TYPE_SK_MSG,
+						BPF_SK_MSG_VERDICT),
+	BPF_APROG_SEC("lirc_mode2",		BPF_PROG_TYPE_LIRC_MODE2,
+						BPF_LIRC_MODE2),
+	BPF_APROG_SEC("flow_dissector",		BPF_PROG_TYPE_FLOW_DISSECTOR,
+						BPF_FLOW_DISSECTOR),
+	BPF_EAPROG_SEC("cgroup/bind4",		BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_BIND),
+	BPF_EAPROG_SEC("cgroup/bind6",		BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_BIND),
+	BPF_EAPROG_SEC("cgroup/connect4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET4_CONNECT),
+	BPF_EAPROG_SEC("cgroup/connect6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_INET6_CONNECT),
+	BPF_EAPROG_SEC("cgroup/sendmsg4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP4_SENDMSG),
+	BPF_EAPROG_SEC("cgroup/sendmsg6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP6_SENDMSG),
+	BPF_EAPROG_SEC("cgroup/recvmsg4",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP4_RECVMSG),
+	BPF_EAPROG_SEC("cgroup/recvmsg6",	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+						BPF_CGROUP_UDP6_RECVMSG),
+	BPF_EAPROG_SEC("cgroup/sysctl",		BPF_PROG_TYPE_CGROUP_SYSCTL,
+						BPF_CGROUP_SYSCTL),
+	BPF_EAPROG_SEC("cgroup/getsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_GETSOCKOPT),
+	BPF_EAPROG_SEC("cgroup/setsockopt",	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+						BPF_CGROUP_SETSOCKOPT),
+};
+
+#undef BPF_PROG_SEC_IMPL
+#undef BPF_PROG_SEC
+#undef BPF_APROG_SEC
+#undef BPF_EAPROG_SEC
+#undef BPF_APROG_COMPAT
+
+#define MAX_TYPE_NAME_SIZE 32
+
+static char *libbpf_get_type_names(bool attach_type)
+{
+	int i, len = ARRAY_SIZE(section_names) * MAX_TYPE_NAME_SIZE;
+	char *buf;
+
+	buf = malloc(len);
+	if (!buf)
+		return NULL;
+
+	buf[0] = '\0';
+	/* Forge string buf with all available names */
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (attach_type && !section_names[i].is_attachable)
+			continue;
+
+		if (strlen(buf) + strlen(section_names[i].sec) + 2 > len) {
+			free(buf);
+			return NULL;
+		}
+		strcat(buf, " ");
+		strcat(buf, section_names[i].sec);
+	}
+
+	return buf;
+}
+
+int libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			     enum bpf_attach_type *expected_attach_type)
+{
+	char *type_names;
+	int i;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		*prog_type = section_names[i].prog_type;
+		*expected_attach_type = section_names[i].expected_attach_type;
+		return 0;
+	}
+	pr_warn("failed to guess program type from ELF section '%s'\n", name);
+	type_names = libbpf_get_type_names(false);
+	if (type_names != NULL) {
+		pr_info("supported section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return -ESRCH;
+}
+
+#define BTF_PREFIX "btf_trace_"
+int libbpf_find_vmlinux_btf_id(const char *name,
+			       enum bpf_attach_type attach_type)
+{
+	struct btf *btf = bpf_core_find_kernel_btf();
+	char raw_tp_btf[128] = BTF_PREFIX;
+	char *dst = raw_tp_btf + sizeof(BTF_PREFIX) - 1;
+	const char *btf_name;
+	int err = -EINVAL;
+	__u32 kind;
+
+	if (IS_ERR(btf)) {
+		pr_warn("vmlinux BTF is not found\n");
+		return -EINVAL;
+	}
+
+	if (attach_type == BPF_TRACE_RAW_TP) {
+		/* prepend "btf_trace_" prefix per kernel convention */
+		strncat(dst, name, sizeof(raw_tp_btf) - sizeof(BTF_PREFIX));
+		btf_name = raw_tp_btf;
+		kind = BTF_KIND_TYPEDEF;
+	} else {
+		btf_name = name;
+		kind = BTF_KIND_FUNC;
+	}
+	err = btf__find_by_name_kind(btf, btf_name, kind);
+	btf__free(btf);
+	return err;
+}
+
+static int libbpf_find_prog_btf_id(const char *name, __u32 attach_prog_fd)
+{
+	struct bpf_prog_info_linear *info_linear;
+	struct bpf_prog_info *info;
+	struct btf *btf = NULL;
+	int err = -EINVAL;
+
+	info_linear = bpf_program__get_prog_info_linear(attach_prog_fd, 0);
+	if (IS_ERR_OR_NULL(info_linear)) {
+		pr_warn("failed get_prog_info_linear for FD %d\n",
+			attach_prog_fd);
+		return -EINVAL;
+	}
+	info = &info_linear->info;
+	if (!info->btf_id) {
+		pr_warn("The target program doesn't have BTF\n");
+		goto out;
+	}
+	if (btf__get_from_id(info->btf_id, &btf)) {
+		pr_warn("Failed to get BTF of the program\n");
+		goto out;
+	}
+	err = btf__find_by_name_kind(btf, name, BTF_KIND_FUNC);
+	btf__free(btf);
+	if (err <= 0) {
+		pr_warn("%s is not found in prog's BTF\n", name);
+		goto out;
+	}
+out:
+	free(info_linear);
+	return err;
+}
+
+static int libbpf_find_attach_btf_id(const char *name,
+				     enum bpf_attach_type attach_type,
+				     __u32 attach_prog_fd)
+{
+	int i, err;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (!section_names[i].is_attach_btf)
+			continue;
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		if (attach_prog_fd)
+			err = libbpf_find_prog_btf_id(name + section_names[i].len,
+						      attach_prog_fd);
+		else
+			err = libbpf_find_vmlinux_btf_id(name + section_names[i].len,
+							 attach_type);
+		if (err <= 0)
+			pr_warn("%s is not found in vmlinux BTF\n", name);
+		return err;
+	}
+	pr_warn("failed to identify btf_id based on ELF section name '%s'\n", name);
+	return -ESRCH;
+}
+
+int libbpf_attach_type_by_name(const char *name,
+			       enum bpf_attach_type *attach_type)
+{
+	char *type_names;
+	int i;
+
+	if (!name)
+		return -EINVAL;
+
+	for (i = 0; i < ARRAY_SIZE(section_names); i++) {
+		if (strncmp(name, section_names[i].sec, section_names[i].len))
+			continue;
+		if (!section_names[i].is_attachable)
+			return -EINVAL;
+		*attach_type = section_names[i].attach_type;
+		return 0;
+	}
+	pr_warn("failed to guess attach type based on ELF section name '%s'\n", name);
+	type_names = libbpf_get_type_names(true);
+	if (type_names != NULL) {
+		pr_info("attachable section(type) names are:%s\n", type_names);
+		free(type_names);
+	}
+
+	return -EINVAL;
+}
+
+int bpf_map__fd(const struct bpf_map *map)
+{
+	return map ? map->fd : -EINVAL;
+}
+
+const struct bpf_map_def *bpf_map__def(const struct bpf_map *map)
+{
+	return map ? &map->def : ERR_PTR(-EINVAL);
+}
+
+const char *bpf_map__name(const struct bpf_map *map)
+{
+	return map ? map->name : NULL;
+}
+
+__u32 bpf_map__btf_key_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_key_type_id : 0;
+}
+
+__u32 bpf_map__btf_value_type_id(const struct bpf_map *map)
+{
+	return map ? map->btf_value_type_id : 0;
+}
+
+int bpf_map__set_priv(struct bpf_map *map, void *priv,
+		     bpf_map_clear_priv_t clear_priv)
+{
+	if (!map)
+		return -EINVAL;
+
+	if (map->priv) {
+		if (map->clear_priv)
+			map->clear_priv(map, map->priv);
+	}
+
+	map->priv = priv;
+	map->clear_priv = clear_priv;
+	return 0;
+}
+
+void *bpf_map__priv(const struct bpf_map *map)
+{
+	return map ? map->priv : ERR_PTR(-EINVAL);
+}
+
+bool bpf_map__is_offload_neutral(const struct bpf_map *map)
+{
+	return map->def.type == BPF_MAP_TYPE_PERF_EVENT_ARRAY;
+}
+
+bool bpf_map__is_internal(const struct bpf_map *map)
+{
+	return map->libbpf_type != LIBBPF_MAP_UNSPEC;
+}
+
+void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex)
+{
+	map->map_ifindex = ifindex;
+}
+
+int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
+{
+	if (!bpf_map_type__is_map_in_map(map->def.type)) {
+		pr_warn("error: unsupported map type\n");
+		return -EINVAL;
+	}
+	if (map->inner_map_fd != -1) {
+		pr_warn("error: inner_map_fd already specified\n");
+		return -EINVAL;
+	}
+	map->inner_map_fd = fd;
+	return 0;
+}
+
+static struct bpf_map *
+__bpf_map__iter(const struct bpf_map *m, const struct bpf_object *obj, int i)
+{
+	ssize_t idx;
+	struct bpf_map *s, *e;
+
+	if (!obj || !obj->maps)
+		return NULL;
+
+	s = obj->maps;
+	e = obj->maps + obj->nr_maps;
+
+	if ((m < s) || (m >= e)) {
+		pr_warn("error in %s: map handler doesn't belong to object\n",
+			 __func__);
+		return NULL;
+	}
+
+	idx = (m - obj->maps) + i;
+	if (idx >= obj->nr_maps || idx < 0)
+		return NULL;
+	return &obj->maps[idx];
+}
+
+struct bpf_map *
+bpf_map__next(const struct bpf_map *prev, const struct bpf_object *obj)
+{
+	if (prev == NULL)
+		return obj->maps;
+
+	return __bpf_map__iter(prev, obj, 1);
+}
+
+struct bpf_map *
+bpf_map__prev(const struct bpf_map *next, const struct bpf_object *obj)
+{
+	if (next == NULL) {
+		if (!obj->nr_maps)
+			return NULL;
+		return obj->maps + obj->nr_maps - 1;
+	}
+
+	return __bpf_map__iter(next, obj, -1);
+}
+
+struct bpf_map *
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name)
+{
+	struct bpf_map *pos;
+
+	bpf_object__for_each_map(pos, obj) {
+		if (pos->name && !strcmp(pos->name, name))
+			return pos;
+	}
+	return NULL;
+}
+
+int
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name)
+{
+	return bpf_map__fd(bpf_object__find_map_by_name(obj, name));
+}
+
+struct bpf_map *
+bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset)
+{
+	return ERR_PTR(-ENOTSUP);
+}
+
+long libbpf_get_error(const void *ptr)
+{
+	return PTR_ERR_OR_ZERO(ptr);
+}
+
+int bpf_prog_load(const char *file, enum bpf_prog_type type,
+		  struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_prog_load_attr attr;
+
+	memset(&attr, 0, sizeof(struct bpf_prog_load_attr));
+	attr.file = file;
+	attr.prog_type = type;
+	attr.expected_attach_type = 0;
+
+	return bpf_prog_load_xattr(&attr, pobj, prog_fd);
+}
+
+int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
+			struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_object_open_attr open_attr = {};
+	struct bpf_program *prog, *first_prog = NULL;
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int err;
+
+	if (!attr)
+		return -EINVAL;
+	if (!attr->file)
+		return -EINVAL;
+
+	open_attr.file = attr->file;
+	open_attr.prog_type = attr->prog_type;
+
+	obj = bpf_object__open_xattr(&open_attr);
+	if (IS_ERR_OR_NULL(obj))
+		return -ENOENT;
+
+	bpf_object__for_each_program(prog, obj) {
+		enum bpf_attach_type attach_type = attr->expected_attach_type;
+		/*
+		 * to preserve backwards compatibility, bpf_prog_load treats
+		 * attr->prog_type, if specified, as an override to whatever
+		 * bpf_object__open guessed
+		 */
+		if (attr->prog_type != BPF_PROG_TYPE_UNSPEC) {
+			bpf_program__set_type(prog, attr->prog_type);
+			bpf_program__set_expected_attach_type(prog,
+							      attach_type);
+		}
+		if (bpf_program__get_type(prog) == BPF_PROG_TYPE_UNSPEC) {
+			/*
+			 * we haven't guessed from section name and user
+			 * didn't provide a fallback type, too bad...
+			 */
+			bpf_object__close(obj);
+			return -EINVAL;
+		}
+
+		prog->prog_ifindex = attr->ifindex;
+		prog->log_level = attr->log_level;
+		prog->prog_flags = attr->prog_flags;
+		if (!first_prog)
+			first_prog = prog;
+	}
+
+	bpf_object__for_each_map(map, obj) {
+		if (!bpf_map__is_offload_neutral(map))
+			map->map_ifindex = attr->ifindex;
+	}
+
+	if (!first_prog) {
+		pr_warn("object file doesn't contain bpf program\n");
+		bpf_object__close(obj);
+		return -ENOENT;
+	}
+
+	err = bpf_object__load(obj);
+	if (err) {
+		bpf_object__close(obj);
+		return -EINVAL;
+	}
+
+	*pobj = obj;
+	*prog_fd = bpf_program__fd(first_prog);
+	return 0;
+}
+
+struct bpf_link {
+	int (*destroy)(struct bpf_link *link);
+};
+
+int bpf_link__destroy(struct bpf_link *link)
+{
+	int err;
+
+	if (!link)
+		return 0;
+
+	err = link->destroy(link);
+	free(link);
+
+	return err;
+}
+
+struct bpf_link_fd {
+	struct bpf_link link; /* has to be at the top of struct */
+	int fd; /* hook FD */
+};
+
+static int bpf_link__destroy_perf_event(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+	int err;
+
+	err = ioctl(l->fd, PERF_EVENT_IOC_DISABLE, 0);
+	if (err)
+		err = -errno;
+
+	close(l->fd);
+	return err;
+}
+
+struct bpf_link *bpf_program__attach_perf_event(struct bpf_program *prog,
+						int pfd)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, err;
+
+	if (pfd < 0) {
+		pr_warn("program '%s': invalid perf event FD %d\n",
+			bpf_program__title(prog, false), pfd);
+		return ERR_PTR(-EINVAL);
+	}
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach BPF program w/o FD (did you load it?)\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_perf_event;
+	link->fd = pfd;
+
+	if (ioctl(pfd, PERF_EVENT_IOC_SET_BPF, prog_fd) < 0) {
+		err = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
+			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return ERR_PTR(err);
+	}
+	if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		free(link);
+		pr_warn("program '%s': failed to enable pfd %d: %s\n",
+			bpf_program__title(prog, false), pfd,
+			   libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return ERR_PTR(err);
+	}
+	return (struct bpf_link *)link;
+}
+
+/*
+ * this function is expected to parse integer in the range of [0, 2^31-1] from
+ * given file using scanf format string fmt. If actual parsed value is
+ * negative, the result might be indistinguishable from error
+ */
+static int parse_uint_from_file(const char *file, const char *fmt)
+{
+	char buf[STRERR_BUFSIZE];
+	int err, ret;
+	FILE *f;
+
+	f = fopen(file, "r");
+	if (!f) {
+		err = -errno;
+		pr_debug("failed to open '%s': %s\n", file,
+			 libbpf_strerror_r(err, buf, sizeof(buf)));
+		return err;
+	}
+	err = fscanf(f, fmt, &ret);
+	if (err != 1) {
+		err = err == EOF ? -EIO : -errno;
+		pr_debug("failed to parse '%s': %s\n", file,
+			libbpf_strerror_r(err, buf, sizeof(buf)));
+		fclose(f);
+		return err;
+	}
+	fclose(f);
+	return ret;
+}
+
+static int determine_kprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_uprobe_perf_type(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/type";
+
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int determine_kprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/kprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int determine_uprobe_retprobe_bit(void)
+{
+	const char *file = "/sys/bus/event_source/devices/uprobe/format/retprobe";
+
+	return parse_uint_from_file(file, "config:%d\n");
+}
+
+static int perf_event_open_probe(bool uprobe, bool retprobe, const char *name,
+				 uint64_t offset, int pid)
+{
+	struct perf_event_attr attr = {};
+	char errmsg[STRERR_BUFSIZE];
+	int type, pfd, err;
+
+	type = uprobe ? determine_uprobe_perf_type()
+		      : determine_kprobe_perf_type();
+	if (type < 0) {
+		pr_warn("failed to determine %s perf type: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(type, errmsg, sizeof(errmsg)));
+		return type;
+	}
+	if (retprobe) {
+		int bit = uprobe ? determine_uprobe_retprobe_bit()
+				 : determine_kprobe_retprobe_bit();
+
+		if (bit < 0) {
+			pr_warn("failed to determine %s retprobe bit: %s\n",
+				uprobe ? "uprobe" : "kprobe",
+				libbpf_strerror_r(bit, errmsg, sizeof(errmsg)));
+			return bit;
+		}
+		attr.config |= 1 << bit;
+	}
+	attr.size = sizeof(attr);
+	attr.type = type;
+	attr.config1 = ptr_to_u64(name); /* kprobe_func or uprobe_path */
+	attr.config2 = offset;		 /* kprobe_addr or probe_offset */
+
+	/* pid filter is meaningful only for uprobes */
+	pfd = syscall(__NR_perf_event_open, &attr,
+		      pid < 0 ? -1 : pid /* pid */,
+		      pid == -1 ? 0 : -1 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("%s perf_event_open() failed: %s\n",
+			uprobe ? "uprobe" : "kprobe",
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_kprobe(struct bpf_program *prog,
+					    bool retprobe,
+					    const char *func_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_probe(false /* uprobe */, retprobe, func_name,
+				    0 /* offset */, -1 /* pid */);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create %s '%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to %s '%s': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "kretprobe" : "kprobe", func_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+struct bpf_link *bpf_program__attach_uprobe(struct bpf_program *prog,
+					    bool retprobe, pid_t pid,
+					    const char *binary_path,
+					    size_t func_offset)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_probe(true /* uprobe */, retprobe,
+				    binary_path, func_offset, pid);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create %s '%s:0x%zx' perf event: %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to %s '%s:0x%zx': %s\n",
+			bpf_program__title(prog, false),
+			retprobe ? "uretprobe" : "uprobe",
+			binary_path, func_offset,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+static int determine_tracepoint_id(const char *tp_category,
+				   const char *tp_name)
+{
+	char file[PATH_MAX];
+	int ret;
+
+	ret = snprintf(file, sizeof(file),
+		       "/sys/kernel/debug/tracing/events/%s/%s/id",
+		       tp_category, tp_name);
+	if (ret < 0)
+		return -errno;
+	if (ret >= sizeof(file)) {
+		pr_debug("tracepoint %s/%s path is too long\n",
+			 tp_category, tp_name);
+		return -E2BIG;
+	}
+	return parse_uint_from_file(file, "%d\n");
+}
+
+static int perf_event_open_tracepoint(const char *tp_category,
+				      const char *tp_name)
+{
+	struct perf_event_attr attr = {};
+	char errmsg[STRERR_BUFSIZE];
+	int tp_id, pfd, err;
+
+	tp_id = determine_tracepoint_id(tp_category, tp_name);
+	if (tp_id < 0) {
+		pr_warn("failed to determine tracepoint '%s/%s' perf event ID: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(tp_id, errmsg, sizeof(errmsg)));
+		return tp_id;
+	}
+
+	attr.type = PERF_TYPE_TRACEPOINT;
+	attr.size = sizeof(attr);
+	attr.config = tp_id;
+
+	pfd = syscall(__NR_perf_event_open, &attr, -1 /* pid */, 0 /* cpu */,
+		      -1 /* group_fd */, PERF_FLAG_FD_CLOEXEC);
+	if (pfd < 0) {
+		err = -errno;
+		pr_warn("tracepoint '%s/%s' perf_event_open() failed: %s\n",
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return err;
+	}
+	return pfd;
+}
+
+struct bpf_link *bpf_program__attach_tracepoint(struct bpf_program *prog,
+						const char *tp_category,
+						const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link *link;
+	int pfd, err;
+
+	pfd = perf_event_open_tracepoint(tp_category, tp_name);
+	if (pfd < 0) {
+		pr_warn("program '%s': failed to create tracepoint '%s/%s' perf event: %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link = bpf_program__attach_perf_event(prog, pfd);
+	if (IS_ERR(link)) {
+		close(pfd);
+		err = PTR_ERR(link);
+		pr_warn("program '%s': failed to attach to tracepoint '%s/%s': %s\n",
+			bpf_program__title(prog, false),
+			tp_category, tp_name,
+			libbpf_strerror_r(err, errmsg, sizeof(errmsg)));
+		return link;
+	}
+	return link;
+}
+
+static int bpf_link__destroy_fd(struct bpf_link *link)
+{
+	struct bpf_link_fd *l = (void *)link;
+
+	return close(l->fd);
+}
+
+struct bpf_link *bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+						    const char *tp_name)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach before loaded\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_fd;
+
+	pfd = bpf_raw_tracepoint_open(tp_name, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to raw tracepoint '%s': %s\n",
+			bpf_program__title(prog, false), tp_name,
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
+struct bpf_link *bpf_program__attach_trace(struct bpf_program *prog)
+{
+	char errmsg[STRERR_BUFSIZE];
+	struct bpf_link_fd *link;
+	int prog_fd, pfd;
+
+	prog_fd = bpf_program__fd(prog);
+	if (prog_fd < 0) {
+		pr_warn("program '%s': can't attach before loaded\n",
+			bpf_program__title(prog, false));
+		return ERR_PTR(-EINVAL);
+	}
+
+	link = malloc(sizeof(*link));
+	if (!link)
+		return ERR_PTR(-ENOMEM);
+	link->link.destroy = &bpf_link__destroy_fd;
+
+	pfd = bpf_raw_tracepoint_open(NULL, prog_fd);
+	if (pfd < 0) {
+		pfd = -errno;
+		free(link);
+		pr_warn("program '%s': failed to attach to trace: %s\n",
+			bpf_program__title(prog, false),
+			libbpf_strerror_r(pfd, errmsg, sizeof(errmsg)));
+		return ERR_PTR(pfd);
+	}
+	link->fd = pfd;
+	return (struct bpf_link *)link;
+}
+
+enum bpf_perf_event_ret
+bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
+			   void **copy_mem, size_t *copy_size,
+			   bpf_perf_event_print_t fn, void *private_data)
+{
+	struct perf_event_mmap_page *header = mmap_mem;
+	__u64 data_head = ring_buffer_read_head(header);
+	__u64 data_tail = header->data_tail;
+	void *base = ((__u8 *)header) + page_size;
+	int ret = LIBBPF_PERF_EVENT_CONT;
+	struct perf_event_header *ehdr;
+	size_t ehdr_size;
+
+	while (data_head != data_tail) {
+		ehdr = base + (data_tail & (mmap_size - 1));
+		ehdr_size = ehdr->size;
+
+		if (((void *)ehdr) + ehdr_size > base + mmap_size) {
+			void *copy_start = ehdr;
+			size_t len_first = base + mmap_size - copy_start;
+			size_t len_secnd = ehdr_size - len_first;
+
+			if (*copy_size < ehdr_size) {
+				free(*copy_mem);
+				*copy_mem = malloc(ehdr_size);
+				if (!*copy_mem) {
+					*copy_size = 0;
+					ret = LIBBPF_PERF_EVENT_ERROR;
+					break;
+				}
+				*copy_size = ehdr_size;
+			}
+
+			memcpy(*copy_mem, copy_start, len_first);
+			memcpy(*copy_mem + len_first, base, len_secnd);
+			ehdr = *copy_mem;
+		}
+
+		ret = fn(ehdr, private_data);
+		data_tail += ehdr_size;
+		if (ret != LIBBPF_PERF_EVENT_CONT)
+			break;
+	}
+
+	ring_buffer_write_tail(header, data_tail);
+	return ret;
+}
+
+struct perf_buffer;
+
+struct perf_buffer_params {
+	struct perf_event_attr *attr;
+	/* if event_cb is specified, it takes precendence */
+	perf_buffer_event_fn event_cb;
+	/* sample_cb and lost_cb are higher-level common-case callbacks */
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx;
+	int cpu_cnt;
+	int *cpus;
+	int *map_keys;
+};
+
+struct perf_cpu_buf {
+	struct perf_buffer *pb;
+	void *base; /* mmap()'ed memory */
+	void *buf; /* for reconstructing segmented data */
+	size_t buf_size;
+	int fd;
+	int cpu;
+	int map_key;
+};
+
+struct perf_buffer {
+	perf_buffer_event_fn event_cb;
+	perf_buffer_sample_fn sample_cb;
+	perf_buffer_lost_fn lost_cb;
+	void *ctx; /* passed into callbacks */
+
+	size_t page_size;
+	size_t mmap_size;
+	struct perf_cpu_buf **cpu_bufs;
+	struct epoll_event *events;
+	int cpu_cnt;
+	int epoll_fd; /* perf event FD */
+	int map_fd; /* BPF_MAP_TYPE_PERF_EVENT_ARRAY BPF map FD */
+};
+
+static void perf_buffer__free_cpu_buf(struct perf_buffer *pb,
+				      struct perf_cpu_buf *cpu_buf)
+{
+	if (!cpu_buf)
+		return;
+	if (cpu_buf->base &&
+	    munmap(cpu_buf->base, pb->mmap_size + pb->page_size))
+		pr_warn("failed to munmap cpu_buf #%d\n", cpu_buf->cpu);
+	if (cpu_buf->fd >= 0) {
+		ioctl(cpu_buf->fd, PERF_EVENT_IOC_DISABLE, 0);
+		close(cpu_buf->fd);
+	}
+	free(cpu_buf->buf);
+	free(cpu_buf);
+}
+
+void perf_buffer__free(struct perf_buffer *pb)
+{
+	int i;
+
+	if (!pb)
+		return;
+	if (pb->cpu_bufs) {
+		for (i = 0; i < pb->cpu_cnt && pb->cpu_bufs[i]; i++) {
+			struct perf_cpu_buf *cpu_buf = pb->cpu_bufs[i];
+
+			bpf_map_delete_elem(pb->map_fd, &cpu_buf->map_key);
+			perf_buffer__free_cpu_buf(pb, cpu_buf);
+		}
+		free(pb->cpu_bufs);
+	}
+	if (pb->epoll_fd >= 0)
+		close(pb->epoll_fd);
+	free(pb->events);
+	free(pb);
+}
+
+static struct perf_cpu_buf *
+perf_buffer__open_cpu_buf(struct perf_buffer *pb, struct perf_event_attr *attr,
+			  int cpu, int map_key)
+{
+	struct perf_cpu_buf *cpu_buf;
+	char msg[STRERR_BUFSIZE];
+	int err;
+
+	cpu_buf = calloc(1, sizeof(*cpu_buf));
+	if (!cpu_buf)
+		return ERR_PTR(-ENOMEM);
+
+	cpu_buf->pb = pb;
+	cpu_buf->cpu = cpu;
+	cpu_buf->map_key = map_key;
+
+	cpu_buf->fd = syscall(__NR_perf_event_open, attr, -1 /* pid */, cpu,
+			      -1, PERF_FLAG_FD_CLOEXEC);
+	if (cpu_buf->fd < 0) {
+		err = -errno;
+		pr_warn("failed to open perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	cpu_buf->base = mmap(NULL, pb->mmap_size + pb->page_size,
+			     PROT_READ | PROT_WRITE, MAP_SHARED,
+			     cpu_buf->fd, 0);
+	if (cpu_buf->base == MAP_FAILED) {
+		cpu_buf->base = NULL;
+		err = -errno;
+		pr_warn("failed to mmap perf buffer on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (ioctl(cpu_buf->fd, PERF_EVENT_IOC_ENABLE, 0) < 0) {
+		err = -errno;
+		pr_warn("failed to enable perf buffer event on cpu #%d: %s\n",
+			cpu, libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	return cpu_buf;
+
+error:
+	perf_buffer__free_cpu_buf(pb, cpu_buf);
+	return (struct perf_cpu_buf *)ERR_PTR(err);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p);
+
+struct perf_buffer *perf_buffer__new(int map_fd, size_t page_cnt,
+				     const struct perf_buffer_opts *opts)
+{
+	struct perf_buffer_params p = {};
+	struct perf_event_attr attr = { 0, };
+
+	attr.config = PERF_COUNT_SW_BPF_OUTPUT,
+	attr.type = PERF_TYPE_SOFTWARE;
+	attr.sample_type = PERF_SAMPLE_RAW;
+	attr.sample_period = 1;
+	attr.wakeup_events = 1;
+
+	p.attr = &attr;
+	p.sample_cb = opts ? opts->sample_cb : NULL;
+	p.lost_cb = opts ? opts->lost_cb : NULL;
+	p.ctx = opts ? opts->ctx : NULL;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts)
+{
+	struct perf_buffer_params p = {};
+
+	p.attr = opts->attr;
+	p.event_cb = opts->event_cb;
+	p.ctx = opts->ctx;
+	p.cpu_cnt = opts->cpu_cnt;
+	p.cpus = opts->cpus;
+	p.map_keys = opts->map_keys;
+
+	return __perf_buffer__new(map_fd, page_cnt, &p);
+}
+
+static struct perf_buffer *__perf_buffer__new(int map_fd, size_t page_cnt,
+					      struct perf_buffer_params *p)
+{
+	struct bpf_map_info map = {};
+	char msg[STRERR_BUFSIZE];
+	struct perf_buffer *pb;
+	__u32 map_info_len;
+	int err, i;
+
+	if (page_cnt & (page_cnt - 1)) {
+		pr_warn("page count should be power of two, but is %zu\n",
+			page_cnt);
+		return ERR_PTR(-EINVAL);
+	}
+
+	map_info_len = sizeof(map);
+	err = bpf_obj_get_info_by_fd(map_fd, &map, &map_info_len);
+	if (err) {
+		err = -errno;
+		pr_warn("failed to get map info for map FD %d: %s\n",
+			map_fd, libbpf_strerror_r(err, msg, sizeof(msg)));
+		return ERR_PTR(err);
+	}
+
+	if (map.type != BPF_MAP_TYPE_PERF_EVENT_ARRAY) {
+		pr_warn("map '%s' should be BPF_MAP_TYPE_PERF_EVENT_ARRAY\n",
+			map.name);
+		return ERR_PTR(-EINVAL);
+	}
+
+	pb = calloc(1, sizeof(*pb));
+	if (!pb)
+		return ERR_PTR(-ENOMEM);
+
+	pb->event_cb = p->event_cb;
+	pb->sample_cb = p->sample_cb;
+	pb->lost_cb = p->lost_cb;
+	pb->ctx = p->ctx;
+
+	pb->page_size = getpagesize();
+	pb->mmap_size = pb->page_size * page_cnt;
+	pb->map_fd = map_fd;
+
+	pb->epoll_fd = epoll_create1(EPOLL_CLOEXEC);
+	if (pb->epoll_fd < 0) {
+		err = -errno;
+		pr_warn("failed to create epoll instance: %s\n",
+			libbpf_strerror_r(err, msg, sizeof(msg)));
+		goto error;
+	}
+
+	if (p->cpu_cnt > 0) {
+		pb->cpu_cnt = p->cpu_cnt;
+	} else {
+		pb->cpu_cnt = libbpf_num_possible_cpus();
+		if (pb->cpu_cnt < 0) {
+			err = pb->cpu_cnt;
+			goto error;
+		}
+		if (map.max_entries < pb->cpu_cnt)
+			pb->cpu_cnt = map.max_entries;
+	}
+
+	pb->events = calloc(pb->cpu_cnt, sizeof(*pb->events));
+	if (!pb->events) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate events: out of memory\n");
+		goto error;
+	}
+	pb->cpu_bufs = calloc(pb->cpu_cnt, sizeof(*pb->cpu_bufs));
+	if (!pb->cpu_bufs) {
+		err = -ENOMEM;
+		pr_warn("failed to allocate buffers: out of memory\n");
+		goto error;
+	}
+
+	for (i = 0; i < pb->cpu_cnt; i++) {
+		struct perf_cpu_buf *cpu_buf;
+		int cpu, map_key;
+
+		cpu = p->cpu_cnt > 0 ? p->cpus[i] : i;
+		map_key = p->cpu_cnt > 0 ? p->map_keys[i] : i;
+
+		cpu_buf = perf_buffer__open_cpu_buf(pb, p->attr, cpu, map_key);
+		if (IS_ERR(cpu_buf)) {
+			err = PTR_ERR(cpu_buf);
+			goto error;
+		}
+
+		pb->cpu_bufs[i] = cpu_buf;
+
+		err = bpf_map_update_elem(pb->map_fd, &map_key,
+					  &cpu_buf->fd, 0);
+		if (err) {
+			err = -errno;
+			pr_warn("failed to set cpu #%d, key %d -> perf FD %d: %s\n",
+				cpu, map_key, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+
+		pb->events[i].events = EPOLLIN;
+		pb->events[i].data.ptr = cpu_buf;
+		if (epoll_ctl(pb->epoll_fd, EPOLL_CTL_ADD, cpu_buf->fd,
+			      &pb->events[i]) < 0) {
+			err = -errno;
+			pr_warn("failed to epoll_ctl cpu #%d perf FD %d: %s\n",
+				cpu, cpu_buf->fd,
+				libbpf_strerror_r(err, msg, sizeof(msg)));
+			goto error;
+		}
+	}
+
+	return pb;
+
+error:
+	if (pb)
+		perf_buffer__free(pb);
+	return ERR_PTR(err);
+}
+
+struct perf_sample_raw {
+	struct perf_event_header header;
+	uint32_t size;
+	char data[0];
+};
+
+struct perf_sample_lost {
+	struct perf_event_header header;
+	uint64_t id;
+	uint64_t lost;
+	uint64_t sample_id;
+};
+
+static enum bpf_perf_event_ret
+perf_buffer__process_record(struct perf_event_header *e, void *ctx)
+{
+	struct perf_cpu_buf *cpu_buf = ctx;
+	struct perf_buffer *pb = cpu_buf->pb;
+	void *data = e;
+
+	/* user wants full control over parsing perf event */
+	if (pb->event_cb)
+		return pb->event_cb(pb->ctx, cpu_buf->cpu, e);
+
+	switch (e->type) {
+	case PERF_RECORD_SAMPLE: {
+		struct perf_sample_raw *s = data;
+
+		if (pb->sample_cb)
+			pb->sample_cb(pb->ctx, cpu_buf->cpu, s->data, s->size);
+		break;
+	}
+	case PERF_RECORD_LOST: {
+		struct perf_sample_lost *s = data;
+
+		if (pb->lost_cb)
+			pb->lost_cb(pb->ctx, cpu_buf->cpu, s->lost);
+		break;
+	}
+	default:
+		pr_warn("unknown perf sample type %d\n", e->type);
+		return LIBBPF_PERF_EVENT_ERROR;
+	}
+	return LIBBPF_PERF_EVENT_CONT;
+}
+
+static int perf_buffer__process_records(struct perf_buffer *pb,
+					struct perf_cpu_buf *cpu_buf)
+{
+	enum bpf_perf_event_ret ret;
+
+	ret = bpf_perf_event_read_simple(cpu_buf->base, pb->mmap_size,
+					 pb->page_size, &cpu_buf->buf,
+					 &cpu_buf->buf_size,
+					 perf_buffer__process_record, cpu_buf);
+	if (ret != LIBBPF_PERF_EVENT_CONT)
+		return ret;
+	return 0;
+}
+
+int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms)
+{
+	int i, cnt, err;
+
+	cnt = epoll_wait(pb->epoll_fd, pb->events, pb->cpu_cnt, timeout_ms);
+	for (i = 0; i < cnt; i++) {
+		struct perf_cpu_buf *cpu_buf = pb->events[i].data.ptr;
+
+		err = perf_buffer__process_records(pb, cpu_buf);
+		if (err) {
+			pr_warn("error while processing records: %d\n", err);
+			return err;
+		}
+	}
+	return cnt < 0 ? -errno : cnt;
+}
+
+struct bpf_prog_info_array_desc {
+	int	array_offset;	/* e.g. offset of jited_prog_insns */
+	int	count_offset;	/* e.g. offset of jited_prog_len */
+	int	size_offset;	/* > 0: offset of rec size,
+				 * < 0: fix size of -size_offset
+				 */
+};
+
+static struct bpf_prog_info_array_desc bpf_prog_info_array_desc[] = {
+	[BPF_PROG_INFO_JITED_INSNS] = {
+		offsetof(struct bpf_prog_info, jited_prog_insns),
+		offsetof(struct bpf_prog_info, jited_prog_len),
+		-1,
+	},
+	[BPF_PROG_INFO_XLATED_INSNS] = {
+		offsetof(struct bpf_prog_info, xlated_prog_insns),
+		offsetof(struct bpf_prog_info, xlated_prog_len),
+		-1,
+	},
+	[BPF_PROG_INFO_MAP_IDS] = {
+		offsetof(struct bpf_prog_info, map_ids),
+		offsetof(struct bpf_prog_info, nr_map_ids),
+		-(int)sizeof(__u32),
+	},
+	[BPF_PROG_INFO_JITED_KSYMS] = {
+		offsetof(struct bpf_prog_info, jited_ksyms),
+		offsetof(struct bpf_prog_info, nr_jited_ksyms),
+		-(int)sizeof(__u64),
+	},
+	[BPF_PROG_INFO_JITED_FUNC_LENS] = {
+		offsetof(struct bpf_prog_info, jited_func_lens),
+		offsetof(struct bpf_prog_info, nr_jited_func_lens),
+		-(int)sizeof(__u32),
+	},
+	[BPF_PROG_INFO_FUNC_INFO] = {
+		offsetof(struct bpf_prog_info, func_info),
+		offsetof(struct bpf_prog_info, nr_func_info),
+		offsetof(struct bpf_prog_info, func_info_rec_size),
+	},
+	[BPF_PROG_INFO_LINE_INFO] = {
+		offsetof(struct bpf_prog_info, line_info),
+		offsetof(struct bpf_prog_info, nr_line_info),
+		offsetof(struct bpf_prog_info, line_info_rec_size),
+	},
+	[BPF_PROG_INFO_JITED_LINE_INFO] = {
+		offsetof(struct bpf_prog_info, jited_line_info),
+		offsetof(struct bpf_prog_info, nr_jited_line_info),
+		offsetof(struct bpf_prog_info, jited_line_info_rec_size),
+	},
+	[BPF_PROG_INFO_PROG_TAGS] = {
+		offsetof(struct bpf_prog_info, prog_tags),
+		offsetof(struct bpf_prog_info, nr_prog_tags),
+		-(int)sizeof(__u8) * BPF_TAG_SIZE,
+	},
+
+};
+
+static __u32 bpf_prog_info_read_offset_u32(struct bpf_prog_info *info,
+					   int offset)
+{
+	__u32 *array = (__u32 *)info;
+
+	if (offset >= 0)
+		return array[offset / sizeof(__u32)];
+	return -(int)offset;
+}
+
+static __u64 bpf_prog_info_read_offset_u64(struct bpf_prog_info *info,
+					   int offset)
+{
+	__u64 *array = (__u64 *)info;
+
+	if (offset >= 0)
+		return array[offset / sizeof(__u64)];
+	return -(int)offset;
+}
+
+static void bpf_prog_info_set_offset_u32(struct bpf_prog_info *info, int offset,
+					 __u32 val)
+{
+	__u32 *array = (__u32 *)info;
+
+	if (offset >= 0)
+		array[offset / sizeof(__u32)] = val;
+}
+
+static void bpf_prog_info_set_offset_u64(struct bpf_prog_info *info, int offset,
+					 __u64 val)
+{
+	__u64 *array = (__u64 *)info;
+
+	if (offset >= 0)
+		array[offset / sizeof(__u64)] = val;
+}
+
+struct bpf_prog_info_linear *
+bpf_program__get_prog_info_linear(int fd, __u64 arrays)
+{
+	struct bpf_prog_info_linear *info_linear;
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
+	__u32 data_len = 0;
+	int i, err;
+	void *ptr;
+
+	if (arrays >> BPF_PROG_INFO_LAST_ARRAY)
+		return ERR_PTR(-EINVAL);
+
+	/* step 1: get array dimensions */
+	err = bpf_obj_get_info_by_fd(fd, &info, &info_len);
+	if (err) {
+		pr_debug("can't get prog info: %s", strerror(errno));
+		return ERR_PTR(-EFAULT);
+	}
+
+	/* step 2: calculate total size of all arrays */
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		bool include_array = (arrays & (1UL << i)) > 0;
+		struct bpf_prog_info_array_desc *desc;
+		__u32 count, size;
+
+		desc = bpf_prog_info_array_desc + i;
+
+		/* kernel is too old to support this field */
+		if (info_len < desc->array_offset + sizeof(__u32) ||
+		    info_len < desc->count_offset + sizeof(__u32) ||
+		    (desc->size_offset > 0 && info_len < desc->size_offset))
+			include_array = false;
+
+		if (!include_array) {
+			arrays &= ~(1UL << i);	/* clear the bit */
+			continue;
+		}
+
+		count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+
+		data_len += count * size;
+	}
+
+	/* step 3: allocate continuous memory */
+	data_len = roundup(data_len, sizeof(__u64));
+	info_linear = malloc(sizeof(struct bpf_prog_info_linear) + data_len);
+	if (!info_linear)
+		return ERR_PTR(-ENOMEM);
+
+	/* step 4: fill data to info_linear->info */
+	info_linear->arrays = arrays;
+	memset(&info_linear->info, 0, sizeof(info));
+	ptr = info_linear->data;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u32 count, size;
+
+		if ((arrays & (1UL << i)) == 0)
+			continue;
+
+		desc  = bpf_prog_info_array_desc + i;
+		count = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		size  = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+		bpf_prog_info_set_offset_u32(&info_linear->info,
+					     desc->count_offset, count);
+		bpf_prog_info_set_offset_u32(&info_linear->info,
+					     desc->size_offset, size);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset,
+					     ptr_to_u64(ptr));
+		ptr += count * size;
+	}
+
+	/* step 5: call syscall again to get required arrays */
+	err = bpf_obj_get_info_by_fd(fd, &info_linear->info, &info_len);
+	if (err) {
+		pr_debug("can't get prog info: %s", strerror(errno));
+		free(info_linear);
+		return ERR_PTR(-EFAULT);
+	}
+
+	/* step 6: verify the data */
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u32 v1, v2;
+
+		if ((arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		v1 = bpf_prog_info_read_offset_u32(&info, desc->count_offset);
+		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
+						   desc->count_offset);
+		if (v1 != v2)
+			pr_warn("%s: mismatch in element count\n", __func__);
+
+		v1 = bpf_prog_info_read_offset_u32(&info, desc->size_offset);
+		v2 = bpf_prog_info_read_offset_u32(&info_linear->info,
+						   desc->size_offset);
+		if (v1 != v2)
+			pr_warn("%s: mismatch in rec size\n", __func__);
+	}
+
+	/* step 7: update info_len and data_len */
+	info_linear->info_len = sizeof(struct bpf_prog_info);
+	info_linear->data_len = data_len;
+
+	return info_linear;
+}
+
+void bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear)
+{
+	int i;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u64 addr, offs;
+
+		if ((info_linear->arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		addr = bpf_prog_info_read_offset_u64(&info_linear->info,
+						     desc->array_offset);
+		offs = addr - ptr_to_u64(info_linear->data);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset, offs);
+	}
+}
+
+void bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear)
+{
+	int i;
+
+	for (i = BPF_PROG_INFO_FIRST_ARRAY; i < BPF_PROG_INFO_LAST_ARRAY; ++i) {
+		struct bpf_prog_info_array_desc *desc;
+		__u64 addr, offs;
+
+		if ((info_linear->arrays & (1UL << i)) == 0)
+			continue;
+
+		desc = bpf_prog_info_array_desc + i;
+		offs = bpf_prog_info_read_offset_u64(&info_linear->info,
+						     desc->array_offset);
+		addr = offs + ptr_to_u64(info_linear->data);
+		bpf_prog_info_set_offset_u64(&info_linear->info,
+					     desc->array_offset, addr);
+	}
+}
+
+int libbpf_num_possible_cpus(void)
+{
+	static const char *fcpu = "/sys/devices/system/cpu/possible";
+	int len = 0, n = 0, il = 0, ir = 0;
+	unsigned int start = 0, end = 0;
+	int tmp_cpus = 0;
+	static int cpus;
+	char buf[128];
+	int error = 0;
+	int fd = -1;
+
+	tmp_cpus = READ_ONCE(cpus);
+	if (tmp_cpus > 0)
+		return tmp_cpus;
+
+	fd = open(fcpu, O_RDONLY);
+	if (fd < 0) {
+		error = errno;
+		pr_warn("Failed to open file %s: %s\n", fcpu, strerror(error));
+		return -error;
+	}
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len <= 0) {
+		error = len ? errno : EINVAL;
+		pr_warn("Failed to read # of possible cpus from %s: %s\n",
+			fcpu, strerror(error));
+		return -error;
+	}
+	if (len == sizeof(buf)) {
+		pr_warn("File %s size overflow\n", fcpu);
+		return -EOVERFLOW;
+	}
+	buf[len] = '\0';
+
+	for (ir = 0, tmp_cpus = 0; ir <= len; ir++) {
+		/* Each sub string separated by ',' has format \d+-\d+ or \d+ */
+		if (buf[ir] == ',' || buf[ir] == '\0') {
+			buf[ir] = '\0';
+			n = sscanf(&buf[il], "%u-%u", &start, &end);
+			if (n <= 0) {
+				pr_warn("Failed to get # CPUs from %s\n",
+					&buf[il]);
+				return -EINVAL;
+			} else if (n == 1) {
+				end = start;
+			}
+			tmp_cpus += end - start + 1;
+			il = ir + 1;
+		}
+	}
+	if (tmp_cpus <= 0) {
+		pr_warn("Invalid #CPUs %d from %s\n", tmp_cpus, fcpu);
+		return -EINVAL;
+	}
+
+	WRITE_ONCE(cpus, tmp_cpus);
+	return tmp_cpus;
+}
diff --git a/src/contrib/libbpf/bpf/libbpf.h b/src/contrib/libbpf/bpf/libbpf.h
new file mode 100644
index 0000000..0dbf4bf
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf.h
@@ -0,0 +1,637 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Common eBPF ELF object loading operations.
+ *
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ */
+#ifndef __LIBBPF_LIBBPF_H
+#define __LIBBPF_LIBBPF_H
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <sys/types.h>  // for size_t
+#include <linux/bpf.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef LIBBPF_API
+#define LIBBPF_API __attribute__((visibility("default")))
+#endif
+
+enum libbpf_errno {
+	__LIBBPF_ERRNO__START = 4000,
+
+	/* Something wrong in libelf */
+	LIBBPF_ERRNO__LIBELF = __LIBBPF_ERRNO__START,
+	LIBBPF_ERRNO__FORMAT,	/* BPF object format invalid */
+	LIBBPF_ERRNO__KVERSION,	/* Incorrect or no 'version' section */
+	LIBBPF_ERRNO__ENDIAN,	/* Endian mismatch */
+	LIBBPF_ERRNO__INTERNAL,	/* Internal error in libbpf */
+	LIBBPF_ERRNO__RELOC,	/* Relocation failed */
+	LIBBPF_ERRNO__LOAD,	/* Load program failure for unknown reason */
+	LIBBPF_ERRNO__VERIFY,	/* Kernel verifier blocks program loading */
+	LIBBPF_ERRNO__PROG2BIG,	/* Program too big */
+	LIBBPF_ERRNO__KVER,	/* Incorrect kernel version */
+	LIBBPF_ERRNO__PROGTYPE,	/* Kernel doesn't support this program type */
+	LIBBPF_ERRNO__WRNGPID,	/* Wrong pid in netlink message */
+	LIBBPF_ERRNO__INVSEQ,	/* Invalid netlink sequence */
+	LIBBPF_ERRNO__NLPARSE,	/* netlink parsing error */
+	__LIBBPF_ERRNO__END,
+};
+
+LIBBPF_API int libbpf_strerror(int err, char *buf, size_t size);
+
+enum libbpf_print_level {
+        LIBBPF_WARN,
+        LIBBPF_INFO,
+        LIBBPF_DEBUG,
+};
+
+typedef int (*libbpf_print_fn_t)(enum libbpf_print_level level,
+				 const char *, va_list ap);
+
+LIBBPF_API libbpf_print_fn_t libbpf_set_print(libbpf_print_fn_t fn);
+
+/* Hide internal to user */
+struct bpf_object;
+
+struct bpf_object_open_attr {
+	const char *file;
+	enum bpf_prog_type prog_type;
+};
+
+/* Helper macro to declare and initialize libbpf options struct
+ *
+ * This dance with uninitialized declaration, followed by memset to zero,
+ * followed by assignment using compound literal syntax is done to preserve
+ * ability to use a nice struct field initialization syntax and **hopefully**
+ * have all the padding bytes initialized to zero. It's not guaranteed though,
+ * when copying literal, that compiler won't copy garbage in literal's padding
+ * bytes, but that's the best way I've found and it seems to work in practice.
+ *
+ * Macro declares opts struct of given type and name, zero-initializes,
+ * including any extra padding, it with memset() and then assigns initial
+ * values provided by users in struct initializer-syntax as varargs.
+ */
+#define DECLARE_LIBBPF_OPTS(TYPE, NAME, ...)				    \
+	struct TYPE NAME = ({ 						    \
+		memset(&NAME, 0, sizeof(struct TYPE));			    \
+		(struct TYPE) {						    \
+			.sz = sizeof(struct TYPE),			    \
+			__VA_ARGS__					    \
+		};							    \
+	})
+
+struct bpf_object_open_opts {
+	/* size of this struct, for forward/backward compatiblity */
+	size_t sz;
+	/* object name override, if provided:
+	 * - for object open from file, this will override setting object
+	 *   name from file path's base name;
+	 * - for object open from memory buffer, this will specify an object
+	 *   name and will override default "<addr>-<buf-size>" name;
+	 */
+	const char *object_name;
+	/* parse map definitions non-strictly, allowing extra attributes/data */
+	bool relaxed_maps;
+	/* process CO-RE relocations non-strictly, allowing them to fail */
+	bool relaxed_core_relocs;
+	/* maps that set the 'pinning' attribute in their definition will have
+	 * their pin_path attribute set to a file in this directory, and be
+	 * auto-pinned to that path on load; defaults to "/sys/fs/bpf".
+	 */
+	const char *pin_root_path;
+	__u32 attach_prog_fd;
+};
+#define bpf_object_open_opts__last_field attach_prog_fd
+
+LIBBPF_API struct bpf_object *bpf_object__open(const char *path);
+LIBBPF_API struct bpf_object *
+bpf_object__open_file(const char *path, struct bpf_object_open_opts *opts);
+LIBBPF_API struct bpf_object *
+bpf_object__open_mem(const void *obj_buf, size_t obj_buf_sz,
+		     struct bpf_object_open_opts *opts);
+
+/* deprecated bpf_object__open variants */
+LIBBPF_API struct bpf_object *
+bpf_object__open_buffer(const void *obj_buf, size_t obj_buf_sz,
+			const char *name);
+LIBBPF_API struct bpf_object *
+bpf_object__open_xattr(struct bpf_object_open_attr *attr);
+
+int bpf_object__section_size(const struct bpf_object *obj, const char *name,
+			     __u32 *size);
+int bpf_object__variable_offset(const struct bpf_object *obj, const char *name,
+				__u32 *off);
+
+enum libbpf_pin_type {
+	LIBBPF_PIN_NONE,
+	/* PIN_BY_NAME: pin maps by name (in /sys/fs/bpf by default) */
+	LIBBPF_PIN_BY_NAME,
+};
+
+/* pin_maps and unpin_maps can both be called with a NULL path, in which case
+ * they will use the pin_path attribute of each map (and ignore all maps that
+ * don't have a pin_path set).
+ */
+LIBBPF_API int bpf_object__pin_maps(struct bpf_object *obj, const char *path);
+LIBBPF_API int bpf_object__unpin_maps(struct bpf_object *obj,
+				      const char *path);
+LIBBPF_API int bpf_object__pin_programs(struct bpf_object *obj,
+					const char *path);
+LIBBPF_API int bpf_object__unpin_programs(struct bpf_object *obj,
+					  const char *path);
+LIBBPF_API int bpf_object__pin(struct bpf_object *object, const char *path);
+LIBBPF_API void bpf_object__close(struct bpf_object *object);
+
+struct bpf_object_load_attr {
+	struct bpf_object *obj;
+	int log_level;
+	const char *target_btf_path;
+};
+
+/* Load/unload object into/from kernel */
+LIBBPF_API int bpf_object__load(struct bpf_object *obj);
+LIBBPF_API int bpf_object__load_xattr(struct bpf_object_load_attr *attr);
+LIBBPF_API int bpf_object__unload(struct bpf_object *obj);
+LIBBPF_API const char *bpf_object__name(const struct bpf_object *obj);
+LIBBPF_API unsigned int bpf_object__kversion(const struct bpf_object *obj);
+
+struct btf;
+LIBBPF_API struct btf *bpf_object__btf(const struct bpf_object *obj);
+LIBBPF_API int bpf_object__btf_fd(const struct bpf_object *obj);
+
+LIBBPF_API struct bpf_program *
+bpf_object__find_program_by_title(const struct bpf_object *obj,
+				  const char *title);
+
+LIBBPF_API struct bpf_object *bpf_object__next(struct bpf_object *prev);
+#define bpf_object__for_each_safe(pos, tmp)			\
+	for ((pos) = bpf_object__next(NULL),		\
+		(tmp) = bpf_object__next(pos);		\
+	     (pos) != NULL;				\
+	     (pos) = (tmp), (tmp) = bpf_object__next(tmp))
+
+typedef void (*bpf_object_clear_priv_t)(struct bpf_object *, void *);
+LIBBPF_API int bpf_object__set_priv(struct bpf_object *obj, void *priv,
+				    bpf_object_clear_priv_t clear_priv);
+LIBBPF_API void *bpf_object__priv(const struct bpf_object *prog);
+
+LIBBPF_API int
+libbpf_prog_type_by_name(const char *name, enum bpf_prog_type *prog_type,
+			 enum bpf_attach_type *expected_attach_type);
+LIBBPF_API int libbpf_attach_type_by_name(const char *name,
+					  enum bpf_attach_type *attach_type);
+LIBBPF_API int libbpf_find_vmlinux_btf_id(const char *name,
+					  enum bpf_attach_type attach_type);
+
+/* Accessors of bpf_program */
+struct bpf_program;
+LIBBPF_API struct bpf_program *bpf_program__next(struct bpf_program *prog,
+						 const struct bpf_object *obj);
+
+#define bpf_object__for_each_program(pos, obj)		\
+	for ((pos) = bpf_program__next(NULL, (obj));	\
+	     (pos) != NULL;				\
+	     (pos) = bpf_program__next((pos), (obj)))
+
+LIBBPF_API struct bpf_program *bpf_program__prev(struct bpf_program *prog,
+						 const struct bpf_object *obj);
+
+typedef void (*bpf_program_clear_priv_t)(struct bpf_program *, void *);
+
+LIBBPF_API int bpf_program__set_priv(struct bpf_program *prog, void *priv,
+				     bpf_program_clear_priv_t clear_priv);
+
+LIBBPF_API void *bpf_program__priv(const struct bpf_program *prog);
+LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
+					 __u32 ifindex);
+
+LIBBPF_API const char *bpf_program__title(const struct bpf_program *prog,
+					  bool needs_copy);
+
+/* returns program size in bytes */
+LIBBPF_API size_t bpf_program__size(const struct bpf_program *prog);
+
+LIBBPF_API int bpf_program__load(struct bpf_program *prog, char *license,
+				 __u32 kern_version);
+LIBBPF_API int bpf_program__fd(const struct bpf_program *prog);
+LIBBPF_API int bpf_program__pin_instance(struct bpf_program *prog,
+					 const char *path,
+					 int instance);
+LIBBPF_API int bpf_program__unpin_instance(struct bpf_program *prog,
+					   const char *path,
+					   int instance);
+LIBBPF_API int bpf_program__pin(struct bpf_program *prog, const char *path);
+LIBBPF_API int bpf_program__unpin(struct bpf_program *prog, const char *path);
+LIBBPF_API void bpf_program__unload(struct bpf_program *prog);
+
+struct bpf_link;
+
+LIBBPF_API int bpf_link__destroy(struct bpf_link *link);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_perf_event(struct bpf_program *prog, int pfd);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_kprobe(struct bpf_program *prog, bool retprobe,
+			   const char *func_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_uprobe(struct bpf_program *prog, bool retprobe,
+			   pid_t pid, const char *binary_path,
+			   size_t func_offset);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_tracepoint(struct bpf_program *prog,
+			       const char *tp_category,
+			       const char *tp_name);
+LIBBPF_API struct bpf_link *
+bpf_program__attach_raw_tracepoint(struct bpf_program *prog,
+				   const char *tp_name);
+
+LIBBPF_API struct bpf_link *
+bpf_program__attach_trace(struct bpf_program *prog);
+struct bpf_insn;
+
+/*
+ * Libbpf allows callers to adjust BPF programs before being loaded
+ * into kernel. One program in an object file can be transformed into
+ * multiple variants to be attached to different hooks.
+ *
+ * bpf_program_prep_t, bpf_program__set_prep and bpf_program__nth_fd
+ * form an API for this purpose.
+ *
+ * - bpf_program_prep_t:
+ *   Defines a 'preprocessor', which is a caller defined function
+ *   passed to libbpf through bpf_program__set_prep(), and will be
+ *   called before program is loaded. The processor should adjust
+ *   the program one time for each instance according to the instance id
+ *   passed to it.
+ *
+ * - bpf_program__set_prep:
+ *   Attaches a preprocessor to a BPF program. The number of instances
+ *   that should be created is also passed through this function.
+ *
+ * - bpf_program__nth_fd:
+ *   After the program is loaded, get resulting FD of a given instance
+ *   of the BPF program.
+ *
+ * If bpf_program__set_prep() is not used, the program would be loaded
+ * without adjustment during bpf_object__load(). The program has only
+ * one instance. In this case bpf_program__fd(prog) is equal to
+ * bpf_program__nth_fd(prog, 0).
+ */
+
+struct bpf_prog_prep_result {
+	/*
+	 * If not NULL, load new instruction array.
+	 * If set to NULL, don't load this instance.
+	 */
+	struct bpf_insn *new_insn_ptr;
+	int new_insn_cnt;
+
+	/* If not NULL, result FD is written to it. */
+	int *pfd;
+};
+
+/*
+ * Parameters of bpf_program_prep_t:
+ *  - prog:	The bpf_program being loaded.
+ *  - n:	Index of instance being generated.
+ *  - insns:	BPF instructions array.
+ *  - insns_cnt:Number of instructions in insns.
+ *  - res:	Output parameter, result of transformation.
+ *
+ * Return value:
+ *  - Zero:	pre-processing success.
+ *  - Non-zero:	pre-processing error, stop loading.
+ */
+typedef int (*bpf_program_prep_t)(struct bpf_program *prog, int n,
+				  struct bpf_insn *insns, int insns_cnt,
+				  struct bpf_prog_prep_result *res);
+
+LIBBPF_API int bpf_program__set_prep(struct bpf_program *prog, int nr_instance,
+				     bpf_program_prep_t prep);
+
+LIBBPF_API int bpf_program__nth_fd(const struct bpf_program *prog, int n);
+
+/*
+ * Adjust type of BPF program. Default is kprobe.
+ */
+LIBBPF_API int bpf_program__set_socket_filter(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_tracepoint(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_raw_tracepoint(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_kprobe(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_sched_cls(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_sched_act(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_xdp(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_perf_event(struct bpf_program *prog);
+LIBBPF_API int bpf_program__set_tracing(struct bpf_program *prog);
+
+LIBBPF_API enum bpf_prog_type bpf_program__get_type(struct bpf_program *prog);
+LIBBPF_API void bpf_program__set_type(struct bpf_program *prog,
+				      enum bpf_prog_type type);
+
+LIBBPF_API enum bpf_attach_type
+bpf_program__get_expected_attach_type(struct bpf_program *prog);
+LIBBPF_API void
+bpf_program__set_expected_attach_type(struct bpf_program *prog,
+				      enum bpf_attach_type type);
+
+LIBBPF_API bool bpf_program__is_socket_filter(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_tracepoint(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_raw_tracepoint(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_kprobe(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_sched_cls(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_sched_act(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_xdp(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_perf_event(const struct bpf_program *prog);
+LIBBPF_API bool bpf_program__is_tracing(const struct bpf_program *prog);
+
+/*
+ * No need for __attribute__((packed)), all members of 'bpf_map_def'
+ * are all aligned.  In addition, using __attribute__((packed))
+ * would trigger a -Wpacked warning message, and lead to an error
+ * if -Werror is set.
+ */
+struct bpf_map_def {
+	unsigned int type;
+	unsigned int key_size;
+	unsigned int value_size;
+	unsigned int max_entries;
+	unsigned int map_flags;
+};
+
+/*
+ * The 'struct bpf_map' in include/linux/bpf.h is internal to the kernel,
+ * so no need to worry about a name clash.
+ */
+struct bpf_map;
+LIBBPF_API struct bpf_map *
+bpf_object__find_map_by_name(const struct bpf_object *obj, const char *name);
+
+LIBBPF_API int
+bpf_object__find_map_fd_by_name(const struct bpf_object *obj, const char *name);
+
+/*
+ * Get bpf_map through the offset of corresponding struct bpf_map_def
+ * in the BPF object file.
+ */
+LIBBPF_API struct bpf_map *
+bpf_object__find_map_by_offset(struct bpf_object *obj, size_t offset);
+
+LIBBPF_API struct bpf_map *
+bpf_map__next(const struct bpf_map *map, const struct bpf_object *obj);
+#define bpf_object__for_each_map(pos, obj)		\
+	for ((pos) = bpf_map__next(NULL, (obj));	\
+	     (pos) != NULL;				\
+	     (pos) = bpf_map__next((pos), (obj)))
+#define bpf_map__for_each bpf_object__for_each_map
+
+LIBBPF_API struct bpf_map *
+bpf_map__prev(const struct bpf_map *map, const struct bpf_object *obj);
+
+LIBBPF_API int bpf_map__fd(const struct bpf_map *map);
+LIBBPF_API const struct bpf_map_def *bpf_map__def(const struct bpf_map *map);
+LIBBPF_API const char *bpf_map__name(const struct bpf_map *map);
+LIBBPF_API __u32 bpf_map__btf_key_type_id(const struct bpf_map *map);
+LIBBPF_API __u32 bpf_map__btf_value_type_id(const struct bpf_map *map);
+
+typedef void (*bpf_map_clear_priv_t)(struct bpf_map *, void *);
+LIBBPF_API int bpf_map__set_priv(struct bpf_map *map, void *priv,
+				 bpf_map_clear_priv_t clear_priv);
+LIBBPF_API void *bpf_map__priv(const struct bpf_map *map);
+LIBBPF_API int bpf_map__reuse_fd(struct bpf_map *map, int fd);
+LIBBPF_API int bpf_map__resize(struct bpf_map *map, __u32 max_entries);
+LIBBPF_API bool bpf_map__is_offload_neutral(const struct bpf_map *map);
+LIBBPF_API bool bpf_map__is_internal(const struct bpf_map *map);
+LIBBPF_API void bpf_map__set_ifindex(struct bpf_map *map, __u32 ifindex);
+LIBBPF_API int bpf_map__set_pin_path(struct bpf_map *map, const char *path);
+LIBBPF_API const char *bpf_map__get_pin_path(const struct bpf_map *map);
+LIBBPF_API bool bpf_map__is_pinned(const struct bpf_map *map);
+LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
+LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
+
+LIBBPF_API int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd);
+
+LIBBPF_API long libbpf_get_error(const void *ptr);
+
+struct bpf_prog_load_attr {
+	const char *file;
+	enum bpf_prog_type prog_type;
+	enum bpf_attach_type expected_attach_type;
+	int ifindex;
+	int log_level;
+	int prog_flags;
+};
+
+LIBBPF_API int bpf_prog_load_xattr(const struct bpf_prog_load_attr *attr,
+				   struct bpf_object **pobj, int *prog_fd);
+LIBBPF_API int bpf_prog_load(const char *file, enum bpf_prog_type type,
+			     struct bpf_object **pobj, int *prog_fd);
+
+struct xdp_link_info {
+	__u32 prog_id;
+	__u32 drv_prog_id;
+	__u32 hw_prog_id;
+	__u32 skb_prog_id;
+	__u8 attach_mode;
+};
+
+LIBBPF_API int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags);
+LIBBPF_API int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags);
+LIBBPF_API int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
+				     size_t info_size, __u32 flags);
+
+struct perf_buffer;
+
+typedef void (*perf_buffer_sample_fn)(void *ctx, int cpu,
+				      void *data, __u32 size);
+typedef void (*perf_buffer_lost_fn)(void *ctx, int cpu, __u64 cnt);
+
+/* common use perf buffer options */
+struct perf_buffer_opts {
+	/* if specified, sample_cb is called for each sample */
+	perf_buffer_sample_fn sample_cb;
+	/* if specified, lost_cb is called for each batch of lost samples */
+	perf_buffer_lost_fn lost_cb;
+	/* ctx is provided to sample_cb and lost_cb */
+	void *ctx;
+};
+
+LIBBPF_API struct perf_buffer *
+perf_buffer__new(int map_fd, size_t page_cnt,
+		 const struct perf_buffer_opts *opts);
+
+enum bpf_perf_event_ret {
+	LIBBPF_PERF_EVENT_DONE	= 0,
+	LIBBPF_PERF_EVENT_ERROR	= -1,
+	LIBBPF_PERF_EVENT_CONT	= -2,
+};
+
+struct perf_event_header;
+
+typedef enum bpf_perf_event_ret
+(*perf_buffer_event_fn)(void *ctx, int cpu, struct perf_event_header *event);
+
+/* raw perf buffer options, giving most power and control */
+struct perf_buffer_raw_opts {
+	/* perf event attrs passed directly into perf_event_open() */
+	struct perf_event_attr *attr;
+	/* raw event callback */
+	perf_buffer_event_fn event_cb;
+	/* ctx is provided to event_cb */
+	void *ctx;
+	/* if cpu_cnt == 0, open all on all possible CPUs (up to the number of
+	 * max_entries of given PERF_EVENT_ARRAY map)
+	 */
+	int cpu_cnt;
+	/* if cpu_cnt > 0, cpus is an array of CPUs to open ring buffers on */
+	int *cpus;
+	/* if cpu_cnt > 0, map_keys specify map keys to set per-CPU FDs for */
+	int *map_keys;
+};
+
+LIBBPF_API struct perf_buffer *
+perf_buffer__new_raw(int map_fd, size_t page_cnt,
+		     const struct perf_buffer_raw_opts *opts);
+
+LIBBPF_API void perf_buffer__free(struct perf_buffer *pb);
+LIBBPF_API int perf_buffer__poll(struct perf_buffer *pb, int timeout_ms);
+
+typedef enum bpf_perf_event_ret
+	(*bpf_perf_event_print_t)(struct perf_event_header *hdr,
+				  void *private_data);
+LIBBPF_API enum bpf_perf_event_ret
+bpf_perf_event_read_simple(void *mmap_mem, size_t mmap_size, size_t page_size,
+			   void **copy_mem, size_t *copy_size,
+			   bpf_perf_event_print_t fn, void *private_data);
+
+struct nlattr;
+typedef int (*libbpf_dump_nlmsg_t)(void *cookie, void *msg, struct nlattr **tb);
+int libbpf_netlink_open(unsigned int *nl_pid);
+int libbpf_nl_get_link(int sock, unsigned int nl_pid,
+		       libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie);
+int libbpf_nl_get_class(int sock, unsigned int nl_pid, int ifindex,
+			libbpf_dump_nlmsg_t dump_class_nlmsg, void *cookie);
+int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
+			libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie);
+int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
+			 libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie);
+
+struct bpf_prog_linfo;
+struct bpf_prog_info;
+
+LIBBPF_API void bpf_prog_linfo__free(struct bpf_prog_linfo *prog_linfo);
+LIBBPF_API struct bpf_prog_linfo *
+bpf_prog_linfo__new(const struct bpf_prog_info *info);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind_addr_func(const struct bpf_prog_linfo *prog_linfo,
+				__u64 addr, __u32 func_idx, __u32 nr_skip);
+LIBBPF_API const struct bpf_line_info *
+bpf_prog_linfo__lfind(const struct bpf_prog_linfo *prog_linfo,
+		      __u32 insn_off, __u32 nr_skip);
+
+/*
+ * Probe for supported system features
+ *
+ * Note that running many of these probes in a short amount of time can cause
+ * the kernel to reach the maximal size of lockable memory allowed for the
+ * user, causing subsequent probes to fail. In this case, the caller may want
+ * to adjust that limit with setrlimit().
+ */
+LIBBPF_API bool bpf_probe_prog_type(enum bpf_prog_type prog_type,
+				    __u32 ifindex);
+LIBBPF_API bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex);
+LIBBPF_API bool bpf_probe_helper(enum bpf_func_id id,
+				 enum bpf_prog_type prog_type, __u32 ifindex);
+
+/*
+ * Get bpf_prog_info in continuous memory
+ *
+ * struct bpf_prog_info has multiple arrays. The user has option to choose
+ * arrays to fetch from kernel. The following APIs provide an uniform way to
+ * fetch these data. All arrays in bpf_prog_info are stored in a single
+ * continuous memory region. This makes it easy to store the info in a
+ * file.
+ *
+ * Before writing bpf_prog_info_linear to files, it is necessary to
+ * translate pointers in bpf_prog_info to offsets. Helper functions
+ * bpf_program__bpil_addr_to_offs() and bpf_program__bpil_offs_to_addr()
+ * are introduced to switch between pointers and offsets.
+ *
+ * Examples:
+ *   # To fetch map_ids and prog_tags:
+ *   __u64 arrays = (1UL << BPF_PROG_INFO_MAP_IDS) |
+ *           (1UL << BPF_PROG_INFO_PROG_TAGS);
+ *   struct bpf_prog_info_linear *info_linear =
+ *           bpf_program__get_prog_info_linear(fd, arrays);
+ *
+ *   # To save data in file
+ *   bpf_program__bpil_addr_to_offs(info_linear);
+ *   write(f, info_linear, sizeof(*info_linear) + info_linear->data_len);
+ *
+ *   # To read data from file
+ *   read(f, info_linear, <proper_size>);
+ *   bpf_program__bpil_offs_to_addr(info_linear);
+ */
+enum bpf_prog_info_array {
+	BPF_PROG_INFO_FIRST_ARRAY = 0,
+	BPF_PROG_INFO_JITED_INSNS = 0,
+	BPF_PROG_INFO_XLATED_INSNS,
+	BPF_PROG_INFO_MAP_IDS,
+	BPF_PROG_INFO_JITED_KSYMS,
+	BPF_PROG_INFO_JITED_FUNC_LENS,
+	BPF_PROG_INFO_FUNC_INFO,
+	BPF_PROG_INFO_LINE_INFO,
+	BPF_PROG_INFO_JITED_LINE_INFO,
+	BPF_PROG_INFO_PROG_TAGS,
+	BPF_PROG_INFO_LAST_ARRAY,
+};
+
+struct bpf_prog_info_linear {
+	/* size of struct bpf_prog_info, when the tool is compiled */
+	__u32			info_len;
+	/* total bytes allocated for data, round up to 8 bytes */
+	__u32			data_len;
+	/* which arrays are included in data */
+	__u64			arrays;
+	struct bpf_prog_info	info;
+	__u8			data[];
+};
+
+LIBBPF_API struct bpf_prog_info_linear *
+bpf_program__get_prog_info_linear(int fd, __u64 arrays);
+
+LIBBPF_API void
+bpf_program__bpil_addr_to_offs(struct bpf_prog_info_linear *info_linear);
+
+LIBBPF_API void
+bpf_program__bpil_offs_to_addr(struct bpf_prog_info_linear *info_linear);
+
+/*
+ * A helper function to get the number of possible CPUs before looking up
+ * per-CPU maps. Negative errno is returned on failure.
+ *
+ * Example usage:
+ *
+ *     int ncpus = libbpf_num_possible_cpus();
+ *     if (ncpus < 0) {
+ *          // error handling
+ *     }
+ *     long values[ncpus];
+ *     bpf_map_lookup_elem(per_cpu_map_fd, key, values);
+ *
+ */
+LIBBPF_API int libbpf_num_possible_cpus(void);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_LIBBPF_H */
diff --git a/src/contrib/libbpf/bpf/libbpf_errno.c b/src/contrib/libbpf/bpf/libbpf_errno.c
new file mode 100644
index 0000000..4343e40
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf_errno.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org>
+ * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
+ * Copyright (C) 2015 Huawei Inc.
+ * Copyright (C) 2017 Nicira, Inc.
+ */
+
+#undef _GNU_SOURCE
+#include <stdio.h>
+#include <string.h>
+
+#include "libbpf.h"
+
+#define ERRNO_OFFSET(e)		((e) - __LIBBPF_ERRNO__START)
+#define ERRCODE_OFFSET(c)	ERRNO_OFFSET(LIBBPF_ERRNO__##c)
+#define NR_ERRNO	(__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START)
+
+static const char *libbpf_strerror_table[NR_ERRNO] = {
+	[ERRCODE_OFFSET(LIBELF)]	= "Something wrong in libelf",
+	[ERRCODE_OFFSET(FORMAT)]	= "BPF object format invalid",
+	[ERRCODE_OFFSET(KVERSION)]	= "'version' section incorrect or lost",
+	[ERRCODE_OFFSET(ENDIAN)]	= "Endian mismatch",
+	[ERRCODE_OFFSET(INTERNAL)]	= "Internal error in libbpf",
+	[ERRCODE_OFFSET(RELOC)]		= "Relocation failed",
+	[ERRCODE_OFFSET(VERIFY)]	= "Kernel verifier blocks program loading",
+	[ERRCODE_OFFSET(PROG2BIG)]	= "Program too big",
+	[ERRCODE_OFFSET(KVER)]		= "Incorrect kernel version",
+	[ERRCODE_OFFSET(PROGTYPE)]	= "Kernel doesn't support this program type",
+	[ERRCODE_OFFSET(WRNGPID)]	= "Wrong pid in netlink message",
+	[ERRCODE_OFFSET(INVSEQ)]	= "Invalid netlink sequence",
+	[ERRCODE_OFFSET(NLPARSE)]	= "Incorrect netlink message parsing",
+};
+
+int libbpf_strerror(int err, char *buf, size_t size)
+{
+	if (!buf || !size)
+		return -1;
+
+	err = err > 0 ? err : -err;
+
+	if (err < __LIBBPF_ERRNO__START) {
+		int ret;
+
+		ret = strerror_r(err, buf, size);
+		buf[size - 1] = '\0';
+		return ret;
+	}
+
+	if (err < __LIBBPF_ERRNO__END) {
+		const char *msg;
+
+		msg = libbpf_strerror_table[ERRNO_OFFSET(err)];
+		snprintf(buf, size, "%s", msg);
+		buf[size - 1] = '\0';
+		return 0;
+	}
+
+	snprintf(buf, size, "Unknown libbpf error %d", err);
+	buf[size - 1] = '\0';
+	return -1;
+}
diff --git a/src/contrib/libbpf/bpf/libbpf_internal.h b/src/contrib/libbpf/bpf/libbpf_internal.h
new file mode 100644
index 0000000..97ac17a
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf_internal.h
@@ -0,0 +1,217 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * Internal libbpf helpers.
+ *
+ * Copyright (c) 2019 Facebook
+ */
+
+#ifndef __LIBBPF_LIBBPF_INTERNAL_H
+#define __LIBBPF_LIBBPF_INTERNAL_H
+
+#include "libbpf.h"
+
+#define BTF_INFO_ENC(kind, kind_flag, vlen) \
+	((!!(kind_flag) << 31) | ((kind) << 24) | ((vlen) & BTF_MAX_VLEN))
+#define BTF_TYPE_ENC(name, info, size_or_type) (name), (info), (size_or_type)
+#define BTF_INT_ENC(encoding, bits_offset, nr_bits) \
+	((encoding) << 24 | (bits_offset) << 16 | (nr_bits))
+#define BTF_TYPE_INT_ENC(name, encoding, bits_offset, bits, sz) \
+	BTF_TYPE_ENC(name, BTF_INFO_ENC(BTF_KIND_INT, 0, 0), sz), \
+	BTF_INT_ENC(encoding, bits_offset, bits)
+#define BTF_MEMBER_ENC(name, type, bits_offset) (name), (type), (bits_offset)
+#define BTF_PARAM_ENC(name, type) (name), (type)
+#define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
+
+#ifndef min
+# define min(x, y) ((x) < (y) ? (x) : (y))
+#endif
+#ifndef max
+# define max(x, y) ((x) < (y) ? (y) : (x))
+#endif
+#ifndef offsetofend
+# define offsetofend(TYPE, FIELD) \
+	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
+#endif
+
+/* Symbol versioning is different between static and shared library.
+ * Properly versioned symbols are needed for shared library, but
+ * only the symbol of the new version is needed for static library.
+ */
+#ifdef SHARED
+# define COMPAT_VERSION(internal_name, api_name, version) \
+	asm(".symver " #internal_name "," #api_name "@" #version);
+# define DEFAULT_VERSION(internal_name, api_name, version) \
+	asm(".symver " #internal_name "," #api_name "@@" #version);
+#else
+# define COMPAT_VERSION(internal_name, api_name, version)
+# define DEFAULT_VERSION(internal_name, api_name, version) \
+	extern typeof(internal_name) api_name \
+	__attribute__((alias(#internal_name)));
+#endif
+
+extern void libbpf_print(enum libbpf_print_level level,
+			 const char *format, ...)
+	__attribute__((format(printf, 2, 3)));
+
+#define __pr(level, fmt, ...)	\
+do {				\
+	libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__);	\
+} while (0)
+
+#define pr_warn(fmt, ...)	__pr(LIBBPF_WARN, fmt, ##__VA_ARGS__)
+#define pr_info(fmt, ...)	__pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
+#define pr_debug(fmt, ...)	__pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
+
+static inline bool libbpf_validate_opts(const char *opts,
+					size_t opts_sz, size_t user_sz,
+					const char *type_name)
+{
+	if (user_sz < sizeof(size_t)) {
+		pr_warn("%s size (%zu) is too small\n", type_name, user_sz);
+		return false;
+	}
+	if (user_sz > opts_sz) {
+		size_t i;
+
+		for (i = opts_sz; i < user_sz; i++) {
+			if (opts[i]) {
+				pr_warn("%s has non-zero extra bytes",
+					type_name);
+				return false;
+			}
+		}
+	}
+	return true;
+}
+
+#define OPTS_VALID(opts, type)						      \
+	(!(opts) || libbpf_validate_opts((const char *)opts,		      \
+					 offsetofend(struct type,	      \
+						     type##__last_field),     \
+					 (opts)->sz, #type))
+#define OPTS_HAS(opts, field) \
+	((opts) && opts->sz >= offsetofend(typeof(*(opts)), field))
+#define OPTS_GET(opts, field, fallback_value) \
+	(OPTS_HAS(opts, field) ? (opts)->field : fallback_value)
+
+int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
+			 const char *str_sec, size_t str_len);
+
+struct btf_ext_info {
+	/*
+	 * info points to the individual info section (e.g. func_info and
+	 * line_info) from the .BTF.ext. It does not include the __u32 rec_size.
+	 */
+	void *info;
+	__u32 rec_size;
+	__u32 len;
+};
+
+#define for_each_btf_ext_sec(seg, sec)					\
+	for (sec = (seg)->info;						\
+	     (void *)sec < (seg)->info + (seg)->len;			\
+	     sec = (void *)sec + sizeof(struct btf_ext_info_sec) +	\
+		   (seg)->rec_size * sec->num_info)
+
+#define for_each_btf_ext_rec(seg, sec, i, rec)				\
+	for (i = 0, rec = (void *)&(sec)->data;				\
+	     i < (sec)->num_info;					\
+	     i++, rec = (void *)rec + (seg)->rec_size)
+
+struct btf_ext {
+	union {
+		struct btf_ext_header *hdr;
+		void *data;
+	};
+	struct btf_ext_info func_info;
+	struct btf_ext_info line_info;
+	struct btf_ext_info field_reloc_info;
+	__u32 data_size;
+};
+
+struct btf_ext_info_sec {
+	__u32	sec_name_off;
+	__u32	num_info;
+	/* Followed by num_info * record_size number of bytes */
+	__u8	data[0];
+};
+
+/* The minimum bpf_func_info checked by the loader */
+struct bpf_func_info_min {
+	__u32   insn_off;
+	__u32   type_id;
+};
+
+/* The minimum bpf_line_info checked by the loader */
+struct bpf_line_info_min {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
+/* bpf_field_info_kind encodes which aspect of captured field has to be
+ * adjusted by relocations. Currently supported values are:
+ *   - BPF_FIELD_BYTE_OFFSET: field offset (in bytes);
+ *   - BPF_FIELD_EXISTS: field existence (1, if field exists; 0, otherwise);
+ */
+enum bpf_field_info_kind {
+	BPF_FIELD_BYTE_OFFSET = 0,	/* field byte offset */
+	BPF_FIELD_BYTE_SIZE = 1,
+	BPF_FIELD_EXISTS = 2,		/* field existence in target kernel */
+	BPF_FIELD_SIGNED = 3,
+	BPF_FIELD_LSHIFT_U64 = 4,
+	BPF_FIELD_RSHIFT_U64 = 5,
+};
+
+/* The minimum bpf_field_reloc checked by the loader
+ *
+ * Field relocation captures the following data:
+ * - insn_off - instruction offset (in bytes) within a BPF program that needs
+ *   its insn->imm field to be relocated with actual field info;
+ * - type_id - BTF type ID of the "root" (containing) entity of a relocatable
+ *   field;
+ * - access_str_off - offset into corresponding .BTF string section. String
+ *   itself encodes an accessed field using a sequence of field and array
+ *   indicies, separated by colon (:). It's conceptually very close to LLVM's
+ *   getelementptr ([0]) instruction's arguments for identifying offset to 
+ *   a field.
+ *
+ * Example to provide a better feel.
+ *
+ *   struct sample {
+ *       int a;
+ *       struct {
+ *           int b[10];
+ *       };
+ *   };
+ *
+ *   struct sample *s = ...;
+ *   int x = &s->a;     // encoded as "0:0" (a is field #0)
+ *   int y = &s->b[5];  // encoded as "0:1:0:5" (anon struct is field #1, 
+ *                      // b is field #0 inside anon struct, accessing elem #5)
+ *   int z = &s[10]->b; // encoded as "10:1" (ptr is used as an array)
+ *
+ * type_id for all relocs in this example  will capture BTF type id of
+ * `struct sample`.
+ *
+ * Such relocation is emitted when using __builtin_preserve_access_index()
+ * Clang built-in, passing expression that captures field address, e.g.:
+ *
+ * bpf_probe_read(&dst, sizeof(dst),
+ *		  __builtin_preserve_access_index(&src->a.b.c));
+ *
+ * In this case Clang will emit field relocation recording necessary data to
+ * be able to find offset of embedded `a.b.c` field within `src` struct.
+ *
+ *   [0] https://llvm.org/docs/LangRef.html#getelementptr-instruction
+ */
+struct bpf_field_reloc {
+	__u32   insn_off;
+	__u32   type_id;
+	__u32   access_str_off;
+	enum bpf_field_info_kind kind;
+};
+
+#endif /* __LIBBPF_LIBBPF_INTERNAL_H */
diff --git a/src/contrib/libbpf/bpf/libbpf_probes.c b/src/contrib/libbpf/bpf/libbpf_probes.c
new file mode 100644
index 0000000..a9eb8b3
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf_probes.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2019 Netronome Systems, Inc. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <net/if.h>
+#include <sys/utsname.h>
+
+#include <linux/btf.h>
+#include <linux/filter.h>
+#include <linux/kernel.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+
+static bool grep(const char *buffer, const char *pattern)
+{
+	return !!strstr(buffer, pattern);
+}
+
+static int get_vendor_id(int ifindex)
+{
+	char ifname[IF_NAMESIZE], path[64], buf[8];
+	ssize_t len;
+	int fd;
+
+	if (!if_indextoname(ifindex, ifname))
+		return -1;
+
+	snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	len = read(fd, buf, sizeof(buf));
+	close(fd);
+	if (len < 0)
+		return -1;
+	if (len >= (ssize_t)sizeof(buf))
+		return -1;
+	buf[len] = '\0';
+
+	return strtol(buf, NULL, 0);
+}
+
+static int get_kernel_version(void)
+{
+	int version, subversion, patchlevel;
+	struct utsname utsn;
+
+	/* Return 0 on failure, and attempt to probe with empty kversion */
+	if (uname(&utsn))
+		return 0;
+
+	if (sscanf(utsn.release, "%d.%d.%d",
+		   &version, &subversion, &patchlevel) != 3)
+		return 0;
+
+	return (version << 16) + (subversion << 8) + patchlevel;
+}
+
+static void
+probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
+	   size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
+{
+	struct bpf_load_program_attr xattr = {};
+	int fd;
+
+	switch (prog_type) {
+	case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
+		xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
+		break;
+	case BPF_PROG_TYPE_KPROBE:
+		xattr.kern_version = get_kernel_version();
+		break;
+	case BPF_PROG_TYPE_UNSPEC:
+	case BPF_PROG_TYPE_SOCKET_FILTER:
+	case BPF_PROG_TYPE_SCHED_CLS:
+	case BPF_PROG_TYPE_SCHED_ACT:
+	case BPF_PROG_TYPE_TRACEPOINT:
+	case BPF_PROG_TYPE_XDP:
+	case BPF_PROG_TYPE_PERF_EVENT:
+	case BPF_PROG_TYPE_CGROUP_SKB:
+	case BPF_PROG_TYPE_CGROUP_SOCK:
+	case BPF_PROG_TYPE_LWT_IN:
+	case BPF_PROG_TYPE_LWT_OUT:
+	case BPF_PROG_TYPE_LWT_XMIT:
+	case BPF_PROG_TYPE_SOCK_OPS:
+	case BPF_PROG_TYPE_SK_SKB:
+	case BPF_PROG_TYPE_CGROUP_DEVICE:
+	case BPF_PROG_TYPE_SK_MSG:
+	case BPF_PROG_TYPE_RAW_TRACEPOINT:
+	case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
+	case BPF_PROG_TYPE_LWT_SEG6LOCAL:
+	case BPF_PROG_TYPE_LIRC_MODE2:
+	case BPF_PROG_TYPE_SK_REUSEPORT:
+	case BPF_PROG_TYPE_FLOW_DISSECTOR:
+	case BPF_PROG_TYPE_CGROUP_SYSCTL:
+	case BPF_PROG_TYPE_CGROUP_SOCKOPT:
+	case BPF_PROG_TYPE_TRACING:
+	default:
+		break;
+	}
+
+	xattr.prog_type = prog_type;
+	xattr.insns = insns;
+	xattr.insns_cnt = insns_cnt;
+	xattr.license = "GPL";
+	xattr.prog_ifindex = ifindex;
+
+	fd = bpf_load_program_xattr(&xattr, buf, buf_len);
+	if (fd >= 0)
+		close(fd);
+}
+
+bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
+{
+	struct bpf_insn insns[2] = {
+		BPF_MOV64_IMM(BPF_REG_0, 0),
+		BPF_EXIT_INSN()
+	};
+
+	if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
+		/* nfp returns -EINVAL on exit(0) with TC offload */
+		insns[0].imm = 2;
+
+	errno = 0;
+	probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
+
+	return errno != EINVAL && errno != EOPNOTSUPP;
+}
+
+int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
+			 const char *str_sec, size_t str_len)
+{
+	struct btf_header hdr = {
+		.magic = BTF_MAGIC,
+		.version = BTF_VERSION,
+		.hdr_len = sizeof(struct btf_header),
+		.type_len = types_len,
+		.str_off = types_len,
+		.str_len = str_len,
+	};
+	int btf_fd, btf_len;
+	__u8 *raw_btf;
+
+	btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
+	raw_btf = malloc(btf_len);
+	if (!raw_btf)
+		return -ENOMEM;
+
+	memcpy(raw_btf, &hdr, sizeof(hdr));
+	memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
+	memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
+
+	btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
+
+	free(raw_btf);
+	return btf_fd;
+}
+
+static int load_sk_storage_btf(void)
+{
+	const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
+	/* struct bpf_spin_lock {
+	 *   int val;
+	 * };
+	 * struct val {
+	 *   int cnt;
+	 *   struct bpf_spin_lock l;
+	 * };
+	 */
+	__u32 types[] = {
+		/* int */
+		BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
+		/* struct bpf_spin_lock */                      /* [2] */
+		BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
+		BTF_MEMBER_ENC(15, 1, 0), /* int val; */
+		/* struct val */                                /* [3] */
+		BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
+		BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
+		BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
+	};
+
+	return libbpf__load_raw_btf((char *)types, sizeof(types),
+				     strs, sizeof(strs));
+}
+
+bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
+{
+	int key_size, value_size, max_entries, map_flags;
+	__u32 btf_key_type_id = 0, btf_value_type_id = 0;
+	struct bpf_create_map_attr attr = {};
+	int fd = -1, btf_fd = -1, fd_inner;
+
+	key_size	= sizeof(__u32);
+	value_size	= sizeof(__u32);
+	max_entries	= 1;
+	map_flags	= 0;
+
+	switch (map_type) {
+	case BPF_MAP_TYPE_STACK_TRACE:
+		value_size	= sizeof(__u64);
+		break;
+	case BPF_MAP_TYPE_LPM_TRIE:
+		key_size	= sizeof(__u64);
+		value_size	= sizeof(__u64);
+		map_flags	= BPF_F_NO_PREALLOC;
+		break;
+	case BPF_MAP_TYPE_CGROUP_STORAGE:
+	case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
+		key_size	= sizeof(struct bpf_cgroup_storage_key);
+		value_size	= sizeof(__u64);
+		max_entries	= 0;
+		break;
+	case BPF_MAP_TYPE_QUEUE:
+	case BPF_MAP_TYPE_STACK:
+		key_size	= 0;
+		break;
+	case BPF_MAP_TYPE_SK_STORAGE:
+		btf_key_type_id = 1;
+		btf_value_type_id = 3;
+		value_size = 8;
+		max_entries = 0;
+		map_flags = BPF_F_NO_PREALLOC;
+		btf_fd = load_sk_storage_btf();
+		if (btf_fd < 0)
+			return false;
+		break;
+	case BPF_MAP_TYPE_UNSPEC:
+	case BPF_MAP_TYPE_HASH:
+	case BPF_MAP_TYPE_ARRAY:
+	case BPF_MAP_TYPE_PROG_ARRAY:
+	case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
+	case BPF_MAP_TYPE_PERCPU_HASH:
+	case BPF_MAP_TYPE_PERCPU_ARRAY:
+	case BPF_MAP_TYPE_CGROUP_ARRAY:
+	case BPF_MAP_TYPE_LRU_HASH:
+	case BPF_MAP_TYPE_LRU_PERCPU_HASH:
+	case BPF_MAP_TYPE_ARRAY_OF_MAPS:
+	case BPF_MAP_TYPE_HASH_OF_MAPS:
+	case BPF_MAP_TYPE_DEVMAP:
+	case BPF_MAP_TYPE_DEVMAP_HASH:
+	case BPF_MAP_TYPE_SOCKMAP:
+	case BPF_MAP_TYPE_CPUMAP:
+	case BPF_MAP_TYPE_XSKMAP:
+	case BPF_MAP_TYPE_SOCKHASH:
+	case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
+	default:
+		break;
+	}
+
+	if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
+	    map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
+		/* TODO: probe for device, once libbpf has a function to create
+		 * map-in-map for offload
+		 */
+		if (ifindex)
+			return false;
+
+		fd_inner = bpf_create_map(BPF_MAP_TYPE_HASH,
+					  sizeof(__u32), sizeof(__u32), 1, 0);
+		if (fd_inner < 0)
+			return false;
+		fd = bpf_create_map_in_map(map_type, NULL, sizeof(__u32),
+					   fd_inner, 1, 0);
+		close(fd_inner);
+	} else {
+		/* Note: No other restriction on map type probes for offload */
+		attr.map_type = map_type;
+		attr.key_size = key_size;
+		attr.value_size = value_size;
+		attr.max_entries = max_entries;
+		attr.map_flags = map_flags;
+		attr.map_ifindex = ifindex;
+		if (btf_fd >= 0) {
+			attr.btf_fd = btf_fd;
+			attr.btf_key_type_id = btf_key_type_id;
+			attr.btf_value_type_id = btf_value_type_id;
+		}
+
+		fd = bpf_create_map_xattr(&attr);
+	}
+	if (fd >= 0)
+		close(fd);
+	if (btf_fd >= 0)
+		close(btf_fd);
+
+	return fd >= 0;
+}
+
+bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
+		      __u32 ifindex)
+{
+	struct bpf_insn insns[2] = {
+		BPF_EMIT_CALL(id),
+		BPF_EXIT_INSN()
+	};
+	char buf[4096] = {};
+	bool res;
+
+	probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf),
+		   ifindex);
+	res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
+
+	if (ifindex) {
+		switch (get_vendor_id(ifindex)) {
+		case 0x19ee: /* Netronome specific */
+			res = res && !grep(buf, "not supported by FW") &&
+				!grep(buf, "unsupported function id");
+			break;
+		default:
+			break;
+		}
+	}
+
+	return res;
+}
diff --git a/src/contrib/libbpf/bpf/libbpf_util.h b/src/contrib/libbpf/bpf/libbpf_util.h
new file mode 100644
index 0000000..59c779c
--- /dev/null
+++ b/src/contrib/libbpf/bpf/libbpf_util.h
@@ -0,0 +1,47 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+/* Copyright (c) 2019 Facebook */
+
+#ifndef __LIBBPF_LIBBPF_UTIL_H
+#define __LIBBPF_LIBBPF_UTIL_H
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Use these barrier functions instead of smp_[rw]mb() when they are
+ * used in a libbpf header file. That way they can be built into the
+ * application that uses libbpf.
+ */
+#if defined(__i386__) || defined(__x86_64__)
+# define libbpf_smp_rmb() asm volatile("" : : : "memory")
+# define libbpf_smp_wmb() asm volatile("" : : : "memory")
+# define libbpf_smp_mb() \
+	asm volatile("lock; addl $0,-4(%%rsp)" : : : "memory", "cc")
+/* Hinders stores to be observed before older loads. */
+# define libbpf_smp_rwmb() asm volatile("" : : : "memory")
+#elif defined(__aarch64__)
+# define libbpf_smp_rmb() asm volatile("dmb ishld" : : : "memory")
+# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
+# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
+# define libbpf_smp_rwmb() libbpf_smp_mb()
+#elif defined(__arm__)
+/* These are only valid for armv7 and above */
+# define libbpf_smp_rmb() asm volatile("dmb ish" : : : "memory")
+# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
+# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
+# define libbpf_smp_rwmb() libbpf_smp_mb()
+#else
+/* Architecture missing native barrier functions. */
+# define libbpf_smp_rmb() __sync_synchronize()
+# define libbpf_smp_wmb() __sync_synchronize()
+# define libbpf_smp_mb() __sync_synchronize()
+# define libbpf_smp_rwmb() __sync_synchronize()
+#endif
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif
diff --git a/src/contrib/libbpf/bpf/netlink.c b/src/contrib/libbpf/bpf/netlink.c
new file mode 100644
index 0000000..5065c1a
--- /dev/null
+++ b/src/contrib/libbpf/bpf/netlink.c
@@ -0,0 +1,451 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+/* Copyright (c) 2018 Facebook */
+
+#include <stdlib.h>
+#include <memory.h>
+#include <unistd.h>
+#include <linux/bpf.h>
+#include <linux/rtnetlink.h>
+#include <sys/socket.h>
+#include <errno.h>
+#include <time.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "nlattr.h"
+
+#ifndef SOL_NETLINK
+#define SOL_NETLINK 270
+#endif
+
+typedef int (*__dump_nlmsg_t)(struct nlmsghdr *nlmsg, libbpf_dump_nlmsg_t,
+			      void *cookie);
+
+struct xdp_id_md {
+	int ifindex;
+	__u32 flags;
+	struct xdp_link_info info;
+};
+
+int libbpf_netlink_open(__u32 *nl_pid)
+{
+	struct sockaddr_nl sa;
+	socklen_t addrlen;
+	int one = 1, ret;
+	int sock;
+
+	memset(&sa, 0, sizeof(sa));
+	sa.nl_family = AF_NETLINK;
+
+	sock = socket(AF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
+	if (sock < 0)
+		return -errno;
+
+	if (setsockopt(sock, SOL_NETLINK, NETLINK_EXT_ACK,
+		       &one, sizeof(one)) < 0) {
+		pr_warn("Netlink error reporting not supported\n");
+	}
+
+	if (bind(sock, (struct sockaddr *)&sa, sizeof(sa)) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+
+	addrlen = sizeof(sa);
+	if (getsockname(sock, (struct sockaddr *)&sa, &addrlen) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+
+	if (addrlen != sizeof(sa)) {
+		ret = -LIBBPF_ERRNO__INTERNAL;
+		goto cleanup;
+	}
+
+	*nl_pid = sa.nl_pid;
+	return sock;
+
+cleanup:
+	close(sock);
+	return ret;
+}
+
+static int bpf_netlink_recv(int sock, __u32 nl_pid, int seq,
+			    __dump_nlmsg_t _fn, libbpf_dump_nlmsg_t fn,
+			    void *cookie)
+{
+	bool multipart = true;
+	struct nlmsgerr *err;
+	struct nlmsghdr *nh;
+	char buf[4096];
+	int len, ret;
+
+	while (multipart) {
+		multipart = false;
+		len = recv(sock, buf, sizeof(buf), 0);
+		if (len < 0) {
+			ret = -errno;
+			goto done;
+		}
+
+		if (len == 0)
+			break;
+
+		for (nh = (struct nlmsghdr *)buf; NLMSG_OK(nh, len);
+		     nh = NLMSG_NEXT(nh, len)) {
+			if (nh->nlmsg_pid != nl_pid) {
+				ret = -LIBBPF_ERRNO__WRNGPID;
+				goto done;
+			}
+			if (nh->nlmsg_seq != seq) {
+				ret = -LIBBPF_ERRNO__INVSEQ;
+				goto done;
+			}
+			if (nh->nlmsg_flags & NLM_F_MULTI)
+				multipart = true;
+			switch (nh->nlmsg_type) {
+			case NLMSG_ERROR:
+				err = (struct nlmsgerr *)NLMSG_DATA(nh);
+				if (!err->error)
+					continue;
+				ret = err->error;
+				libbpf_nla_dump_errormsg(nh);
+				goto done;
+			case NLMSG_DONE:
+				return 0;
+			default:
+				break;
+			}
+			if (_fn) {
+				ret = _fn(nh, fn, cookie);
+				if (ret)
+					return ret;
+			}
+		}
+	}
+	ret = 0;
+done:
+	return ret;
+}
+
+int bpf_set_link_xdp_fd(int ifindex, int fd, __u32 flags)
+{
+	int sock, seq = 0, ret;
+	struct nlattr *nla, *nla_xdp;
+	struct {
+		struct nlmsghdr  nh;
+		struct ifinfomsg ifinfo;
+		char             attrbuf[64];
+	} req;
+	__u32 nl_pid;
+
+	sock = libbpf_netlink_open(&nl_pid);
+	if (sock < 0)
+		return sock;
+
+	memset(&req, 0, sizeof(req));
+	req.nh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
+	req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_ACK;
+	req.nh.nlmsg_type = RTM_SETLINK;
+	req.nh.nlmsg_pid = 0;
+	req.nh.nlmsg_seq = ++seq;
+	req.ifinfo.ifi_family = AF_UNSPEC;
+	req.ifinfo.ifi_index = ifindex;
+
+	/* started nested attribute for XDP */
+	nla = (struct nlattr *)(((char *)&req)
+				+ NLMSG_ALIGN(req.nh.nlmsg_len));
+	nla->nla_type = NLA_F_NESTED | IFLA_XDP;
+	nla->nla_len = NLA_HDRLEN;
+
+	/* add XDP fd */
+	nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
+	nla_xdp->nla_type = IFLA_XDP_FD;
+	nla_xdp->nla_len = NLA_HDRLEN + sizeof(int);
+	memcpy((char *)nla_xdp + NLA_HDRLEN, &fd, sizeof(fd));
+	nla->nla_len += nla_xdp->nla_len;
+
+	/* if user passed in any flags, add those too */
+	if (flags) {
+		nla_xdp = (struct nlattr *)((char *)nla + nla->nla_len);
+		nla_xdp->nla_type = IFLA_XDP_FLAGS;
+		nla_xdp->nla_len = NLA_HDRLEN + sizeof(flags);
+		memcpy((char *)nla_xdp + NLA_HDRLEN, &flags, sizeof(flags));
+		nla->nla_len += nla_xdp->nla_len;
+	}
+
+	req.nh.nlmsg_len += NLA_ALIGN(nla->nla_len);
+
+	if (send(sock, &req, req.nh.nlmsg_len, 0) < 0) {
+		ret = -errno;
+		goto cleanup;
+	}
+	ret = bpf_netlink_recv(sock, nl_pid, seq, NULL, NULL, NULL);
+
+cleanup:
+	close(sock);
+	return ret;
+}
+
+static int __dump_link_nlmsg(struct nlmsghdr *nlh,
+			     libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
+{
+	struct nlattr *tb[IFLA_MAX + 1], *attr;
+	struct ifinfomsg *ifi = NLMSG_DATA(nlh);
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*ifi));
+	attr = (struct nlattr *) ((void *) ifi + NLMSG_ALIGN(sizeof(*ifi)));
+	if (libbpf_nla_parse(tb, IFLA_MAX, attr, len, NULL) != 0)
+		return -LIBBPF_ERRNO__NLPARSE;
+
+	return dump_link_nlmsg(cookie, ifi, tb);
+}
+
+static int get_xdp_info(void *cookie, void *msg, struct nlattr **tb)
+{
+	struct nlattr *xdp_tb[IFLA_XDP_MAX + 1];
+	struct xdp_id_md *xdp_id = cookie;
+	struct ifinfomsg *ifinfo = msg;
+	int ret;
+
+	if (xdp_id->ifindex && xdp_id->ifindex != ifinfo->ifi_index)
+		return 0;
+
+	if (!tb[IFLA_XDP])
+		return 0;
+
+	ret = libbpf_nla_parse_nested(xdp_tb, IFLA_XDP_MAX, tb[IFLA_XDP], NULL);
+	if (ret)
+		return ret;
+
+	if (!xdp_tb[IFLA_XDP_ATTACHED])
+		return 0;
+
+	xdp_id->info.attach_mode = libbpf_nla_getattr_u8(
+		xdp_tb[IFLA_XDP_ATTACHED]);
+
+	if (xdp_id->info.attach_mode == XDP_ATTACHED_NONE)
+		return 0;
+
+	if (xdp_tb[IFLA_XDP_PROG_ID])
+		xdp_id->info.prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_SKB_PROG_ID])
+		xdp_id->info.skb_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_SKB_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_DRV_PROG_ID])
+		xdp_id->info.drv_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_DRV_PROG_ID]);
+
+	if (xdp_tb[IFLA_XDP_HW_PROG_ID])
+		xdp_id->info.hw_prog_id = libbpf_nla_getattr_u32(
+			xdp_tb[IFLA_XDP_HW_PROG_ID]);
+
+	return 0;
+}
+
+int bpf_get_link_xdp_info(int ifindex, struct xdp_link_info *info,
+			  size_t info_size, __u32 flags)
+{
+	struct xdp_id_md xdp_id = {};
+	int sock, ret;
+	__u32 nl_pid;
+	__u32 mask;
+
+	if (flags & ~XDP_FLAGS_MASK || !info_size)
+		return -EINVAL;
+
+	/* Check whether the single {HW,DRV,SKB} mode is set */
+	flags &= (XDP_FLAGS_SKB_MODE | XDP_FLAGS_DRV_MODE | XDP_FLAGS_HW_MODE);
+	mask = flags - 1;
+	if (flags && flags & mask)
+		return -EINVAL;
+
+	sock = libbpf_netlink_open(&nl_pid);
+	if (sock < 0)
+		return sock;
+
+	xdp_id.ifindex = ifindex;
+	xdp_id.flags = flags;
+
+	ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_info, &xdp_id);
+	if (!ret) {
+		size_t sz = min(info_size, sizeof(xdp_id.info));
+
+		memcpy(info, &xdp_id.info, sz);
+		memset((void *) info + sz, 0, info_size - sz);
+	}
+
+	close(sock);
+	return ret;
+}
+
+static __u32 get_xdp_id(struct xdp_link_info *info, __u32 flags)
+{
+	if (info->attach_mode != XDP_ATTACHED_MULTI)
+		return info->prog_id;
+	if (flags & XDP_FLAGS_DRV_MODE)
+		return info->drv_prog_id;
+	if (flags & XDP_FLAGS_HW_MODE)
+		return info->hw_prog_id;
+	if (flags & XDP_FLAGS_SKB_MODE)
+		return info->skb_prog_id;
+
+	return 0;
+}
+
+int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
+{
+	struct xdp_link_info info;
+	int ret;
+
+	ret = bpf_get_link_xdp_info(ifindex, &info, sizeof(info), flags);
+	if (!ret)
+		*prog_id = get_xdp_id(&info, flags);
+
+	return ret;
+}
+
+int libbpf_nl_get_link(int sock, unsigned int nl_pid,
+		       libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct ifinfomsg ifm;
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg)),
+		.nlh.nlmsg_type = RTM_GETLINK,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.ifm.ifi_family = AF_PACKET,
+	};
+	int seq = time(NULL);
+
+	req.nlh.nlmsg_seq = seq;
+	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
+		return -errno;
+
+	return bpf_netlink_recv(sock, nl_pid, seq, __dump_link_nlmsg,
+				dump_link_nlmsg, cookie);
+}
+
+static int __dump_class_nlmsg(struct nlmsghdr *nlh,
+			      libbpf_dump_nlmsg_t dump_class_nlmsg,
+			      void *cookie)
+{
+	struct nlattr *tb[TCA_MAX + 1], *attr;
+	struct tcmsg *t = NLMSG_DATA(nlh);
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
+	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
+	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
+		return -LIBBPF_ERRNO__NLPARSE;
+
+	return dump_class_nlmsg(cookie, t, tb);
+}
+
+int libbpf_nl_get_class(int sock, unsigned int nl_pid, int ifindex,
+			libbpf_dump_nlmsg_t dump_class_nlmsg, void *cookie)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct tcmsg t;
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
+		.nlh.nlmsg_type = RTM_GETTCLASS,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.t.tcm_family = AF_UNSPEC,
+		.t.tcm_ifindex = ifindex,
+	};
+	int seq = time(NULL);
+
+	req.nlh.nlmsg_seq = seq;
+	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
+		return -errno;
+
+	return bpf_netlink_recv(sock, nl_pid, seq, __dump_class_nlmsg,
+				dump_class_nlmsg, cookie);
+}
+
+static int __dump_qdisc_nlmsg(struct nlmsghdr *nlh,
+			      libbpf_dump_nlmsg_t dump_qdisc_nlmsg,
+			      void *cookie)
+{
+	struct nlattr *tb[TCA_MAX + 1], *attr;
+	struct tcmsg *t = NLMSG_DATA(nlh);
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
+	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
+	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
+		return -LIBBPF_ERRNO__NLPARSE;
+
+	return dump_qdisc_nlmsg(cookie, t, tb);
+}
+
+int libbpf_nl_get_qdisc(int sock, unsigned int nl_pid, int ifindex,
+			libbpf_dump_nlmsg_t dump_qdisc_nlmsg, void *cookie)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct tcmsg t;
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
+		.nlh.nlmsg_type = RTM_GETQDISC,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.t.tcm_family = AF_UNSPEC,
+		.t.tcm_ifindex = ifindex,
+	};
+	int seq = time(NULL);
+
+	req.nlh.nlmsg_seq = seq;
+	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
+		return -errno;
+
+	return bpf_netlink_recv(sock, nl_pid, seq, __dump_qdisc_nlmsg,
+				dump_qdisc_nlmsg, cookie);
+}
+
+static int __dump_filter_nlmsg(struct nlmsghdr *nlh,
+			       libbpf_dump_nlmsg_t dump_filter_nlmsg,
+			       void *cookie)
+{
+	struct nlattr *tb[TCA_MAX + 1], *attr;
+	struct tcmsg *t = NLMSG_DATA(nlh);
+	int len;
+
+	len = nlh->nlmsg_len - NLMSG_LENGTH(sizeof(*t));
+	attr = (struct nlattr *) ((void *) t + NLMSG_ALIGN(sizeof(*t)));
+	if (libbpf_nla_parse(tb, TCA_MAX, attr, len, NULL) != 0)
+		return -LIBBPF_ERRNO__NLPARSE;
+
+	return dump_filter_nlmsg(cookie, t, tb);
+}
+
+int libbpf_nl_get_filter(int sock, unsigned int nl_pid, int ifindex, int handle,
+			 libbpf_dump_nlmsg_t dump_filter_nlmsg, void *cookie)
+{
+	struct {
+		struct nlmsghdr nlh;
+		struct tcmsg t;
+	} req = {
+		.nlh.nlmsg_len = NLMSG_LENGTH(sizeof(struct tcmsg)),
+		.nlh.nlmsg_type = RTM_GETTFILTER,
+		.nlh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+		.t.tcm_family = AF_UNSPEC,
+		.t.tcm_ifindex = ifindex,
+		.t.tcm_parent = handle,
+	};
+	int seq = time(NULL);
+
+	req.nlh.nlmsg_seq = seq;
+	if (send(sock, &req, req.nlh.nlmsg_len, 0) < 0)
+		return -errno;
+
+	return bpf_netlink_recv(sock, nl_pid, seq, __dump_filter_nlmsg,
+				dump_filter_nlmsg, cookie);
+}
diff --git a/src/contrib/libbpf/bpf/nlattr.c b/src/contrib/libbpf/bpf/nlattr.c
new file mode 100644
index 0000000..8db44bb
--- /dev/null
+++ b/src/contrib/libbpf/bpf/nlattr.c
@@ -0,0 +1,195 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * NETLINK      Netlink attributes
+ *
+ * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
+ */
+
+#include <errno.h>
+#include "nlattr.h"
+#include "libbpf_internal.h"
+#include <linux/rtnetlink.h>
+#include <string.h>
+#include <stdio.h>
+
+static uint16_t nla_attr_minlen[LIBBPF_NLA_TYPE_MAX+1] = {
+	[LIBBPF_NLA_U8]		= sizeof(uint8_t),
+	[LIBBPF_NLA_U16]	= sizeof(uint16_t),
+	[LIBBPF_NLA_U32]	= sizeof(uint32_t),
+	[LIBBPF_NLA_U64]	= sizeof(uint64_t),
+	[LIBBPF_NLA_STRING]	= 1,
+	[LIBBPF_NLA_FLAG]	= 0,
+};
+
+static struct nlattr *nla_next(const struct nlattr *nla, int *remaining)
+{
+	int totlen = NLA_ALIGN(nla->nla_len);
+
+	*remaining -= totlen;
+	return (struct nlattr *) ((char *) nla + totlen);
+}
+
+static int nla_ok(const struct nlattr *nla, int remaining)
+{
+	return remaining >= sizeof(*nla) &&
+	       nla->nla_len >= sizeof(*nla) &&
+	       nla->nla_len <= remaining;
+}
+
+static int nla_type(const struct nlattr *nla)
+{
+	return nla->nla_type & NLA_TYPE_MASK;
+}
+
+static int validate_nla(struct nlattr *nla, int maxtype,
+			struct libbpf_nla_policy *policy)
+{
+	struct libbpf_nla_policy *pt;
+	unsigned int minlen = 0;
+	int type = nla_type(nla);
+
+	if (type < 0 || type > maxtype)
+		return 0;
+
+	pt = &policy[type];
+
+	if (pt->type > LIBBPF_NLA_TYPE_MAX)
+		return 0;
+
+	if (pt->minlen)
+		minlen = pt->minlen;
+	else if (pt->type != LIBBPF_NLA_UNSPEC)
+		minlen = nla_attr_minlen[pt->type];
+
+	if (libbpf_nla_len(nla) < minlen)
+		return -1;
+
+	if (pt->maxlen && libbpf_nla_len(nla) > pt->maxlen)
+		return -1;
+
+	if (pt->type == LIBBPF_NLA_STRING) {
+		char *data = libbpf_nla_data(nla);
+
+		if (data[libbpf_nla_len(nla) - 1] != '\0')
+			return -1;
+	}
+
+	return 0;
+}
+
+static inline int nlmsg_len(const struct nlmsghdr *nlh)
+{
+	return nlh->nlmsg_len - NLMSG_HDRLEN;
+}
+
+/**
+ * Create attribute index based on a stream of attributes.
+ * @arg tb		Index array to be filled (maxtype+1 elements).
+ * @arg maxtype		Maximum attribute type expected and accepted.
+ * @arg head		Head of attribute stream.
+ * @arg len		Length of attribute stream.
+ * @arg policy		Attribute validation policy.
+ *
+ * Iterates over the stream of attributes and stores a pointer to each
+ * attribute in the index array using the attribute type as index to
+ * the array. Attribute with a type greater than the maximum type
+ * specified will be silently ignored in order to maintain backwards
+ * compatibility. If \a policy is not NULL, the attribute will be
+ * validated using the specified policy.
+ *
+ * @see nla_validate
+ * @return 0 on success or a negative error code.
+ */
+int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
+		     int len, struct libbpf_nla_policy *policy)
+{
+	struct nlattr *nla;
+	int rem, err;
+
+	memset(tb, 0, sizeof(struct nlattr *) * (maxtype + 1));
+
+	libbpf_nla_for_each_attr(nla, head, len, rem) {
+		int type = nla_type(nla);
+
+		if (type > maxtype)
+			continue;
+
+		if (policy) {
+			err = validate_nla(nla, maxtype, policy);
+			if (err < 0)
+				goto errout;
+		}
+
+		if (tb[type])
+			pr_warn("Attribute of type %#x found multiple times in message, "
+				"previous attribute is being ignored.\n", type);
+
+		tb[type] = nla;
+	}
+
+	err = 0;
+errout:
+	return err;
+}
+
+/**
+ * Create attribute index based on nested attribute
+ * @arg tb              Index array to be filled (maxtype+1 elements).
+ * @arg maxtype         Maximum attribute type expected and accepted.
+ * @arg nla             Nested Attribute.
+ * @arg policy          Attribute validation policy.
+ *
+ * Feeds the stream of attributes nested into the specified attribute
+ * to libbpf_nla_parse().
+ *
+ * @see libbpf_nla_parse
+ * @return 0 on success or a negative error code.
+ */
+int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
+			    struct nlattr *nla,
+			    struct libbpf_nla_policy *policy)
+{
+	return libbpf_nla_parse(tb, maxtype, libbpf_nla_data(nla),
+				libbpf_nla_len(nla), policy);
+}
+
+/* dump netlink extended ack error message */
+int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh)
+{
+	struct libbpf_nla_policy extack_policy[NLMSGERR_ATTR_MAX + 1] = {
+		[NLMSGERR_ATTR_MSG]	= { .type = LIBBPF_NLA_STRING },
+		[NLMSGERR_ATTR_OFFS]	= { .type = LIBBPF_NLA_U32 },
+	};
+	struct nlattr *tb[NLMSGERR_ATTR_MAX + 1], *attr;
+	struct nlmsgerr *err;
+	char *errmsg = NULL;
+	int hlen, alen;
+
+	/* no TLVs, nothing to do here */
+	if (!(nlh->nlmsg_flags & NLM_F_ACK_TLVS))
+		return 0;
+
+	err = (struct nlmsgerr *)NLMSG_DATA(nlh);
+	hlen = sizeof(*err);
+
+	/* if NLM_F_CAPPED is set then the inner err msg was capped */
+	if (!(nlh->nlmsg_flags & NLM_F_CAPPED))
+		hlen += nlmsg_len(&err->msg);
+
+	attr = (struct nlattr *) ((void *) err + hlen);
+	alen = nlh->nlmsg_len - hlen;
+
+	if (libbpf_nla_parse(tb, NLMSGERR_ATTR_MAX, attr, alen,
+			     extack_policy) != 0) {
+		pr_warn("Failed to parse extended error attributes\n");
+		return 0;
+	}
+
+	if (tb[NLMSGERR_ATTR_MSG])
+		errmsg = (char *) libbpf_nla_data(tb[NLMSGERR_ATTR_MSG]);
+
+	pr_warn("Kernel error message: %s\n", errmsg);
+
+	return 0;
+}
diff --git a/src/contrib/libbpf/bpf/nlattr.h b/src/contrib/libbpf/bpf/nlattr.h
new file mode 100644
index 0000000..6cc3ac9
--- /dev/null
+++ b/src/contrib/libbpf/bpf/nlattr.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * NETLINK      Netlink attributes
+ *
+ * Copyright (c) 2003-2013 Thomas Graf <tgraf@suug.ch>
+ */
+
+#ifndef __LIBBPF_NLATTR_H
+#define __LIBBPF_NLATTR_H
+
+#include <stdint.h>
+#include <linux/netlink.h>
+/* avoid multiple definition of netlink features */
+#define __LINUX_NETLINK_H
+
+/**
+ * Standard attribute types to specify validation policy
+ */
+enum {
+	LIBBPF_NLA_UNSPEC,	/**< Unspecified type, binary data chunk */
+	LIBBPF_NLA_U8,		/**< 8 bit integer */
+	LIBBPF_NLA_U16,		/**< 16 bit integer */
+	LIBBPF_NLA_U32,		/**< 32 bit integer */
+	LIBBPF_NLA_U64,		/**< 64 bit integer */
+	LIBBPF_NLA_STRING,	/**< NUL terminated character string */
+	LIBBPF_NLA_FLAG,	/**< Flag */
+	LIBBPF_NLA_MSECS,	/**< Micro seconds (64bit) */
+	LIBBPF_NLA_NESTED,	/**< Nested attributes */
+	__LIBBPF_NLA_TYPE_MAX,
+};
+
+#define LIBBPF_NLA_TYPE_MAX (__LIBBPF_NLA_TYPE_MAX - 1)
+
+/**
+ * @ingroup attr
+ * Attribute validation policy.
+ *
+ * See section @core_doc{core_attr_parse,Attribute Parsing} for more details.
+ */
+struct libbpf_nla_policy {
+	/** Type of attribute or LIBBPF_NLA_UNSPEC */
+	uint16_t	type;
+
+	/** Minimal length of payload required */
+	uint16_t	minlen;
+
+	/** Maximal length of payload allowed */
+	uint16_t	maxlen;
+};
+
+/**
+ * @ingroup attr
+ * Iterate over a stream of attributes
+ * @arg pos	loop counter, set to current attribute
+ * @arg head	head of attribute stream
+ * @arg len	length of attribute stream
+ * @arg rem	initialized to len, holds bytes currently remaining in stream
+ */
+#define libbpf_nla_for_each_attr(pos, head, len, rem) \
+	for (pos = head, rem = len; \
+	     nla_ok(pos, rem); \
+	     pos = nla_next(pos, &(rem)))
+
+/**
+ * libbpf_nla_data - head of payload
+ * @nla: netlink attribute
+ */
+static inline void *libbpf_nla_data(const struct nlattr *nla)
+{
+	return (char *) nla + NLA_HDRLEN;
+}
+
+static inline uint8_t libbpf_nla_getattr_u8(const struct nlattr *nla)
+{
+	return *(uint8_t *)libbpf_nla_data(nla);
+}
+
+static inline uint32_t libbpf_nla_getattr_u32(const struct nlattr *nla)
+{
+	return *(uint32_t *)libbpf_nla_data(nla);
+}
+
+static inline const char *libbpf_nla_getattr_str(const struct nlattr *nla)
+{
+	return (const char *)libbpf_nla_data(nla);
+}
+
+/**
+ * libbpf_nla_len - length of payload
+ * @nla: netlink attribute
+ */
+static inline int libbpf_nla_len(const struct nlattr *nla)
+{
+	return nla->nla_len - NLA_HDRLEN;
+}
+
+int libbpf_nla_parse(struct nlattr *tb[], int maxtype, struct nlattr *head,
+		     int len, struct libbpf_nla_policy *policy);
+int libbpf_nla_parse_nested(struct nlattr *tb[], int maxtype,
+			    struct nlattr *nla,
+			    struct libbpf_nla_policy *policy);
+
+int libbpf_nla_dump_errormsg(struct nlmsghdr *nlh);
+
+#endif /* __LIBBPF_NLATTR_H */
diff --git a/src/contrib/libbpf/bpf/str_error.c b/src/contrib/libbpf/bpf/str_error.c
new file mode 100644
index 0000000..b8064ee
--- /dev/null
+++ b/src/contrib/libbpf/bpf/str_error.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+#undef _GNU_SOURCE
+#include <string.h>
+#include <stdio.h>
+#include "str_error.h"
+
+/*
+ * Wrapper to allow for building in non-GNU systems such as Alpine Linux's musl
+ * libc, while checking strerror_r() return to avoid having to check this in
+ * all places calling it.
+ */
+char *libbpf_strerror_r(int err, char *dst, int len)
+{
+	int ret = strerror_r(err < 0 ? -err : err, dst, len);
+	if (ret)
+		snprintf(dst, len, "ERROR: strerror_r(%d)=%d", err, ret);
+	return dst;
+}
diff --git a/src/contrib/libbpf/bpf/str_error.h b/src/contrib/libbpf/bpf/str_error.h
new file mode 100644
index 0000000..a139334
--- /dev/null
+++ b/src/contrib/libbpf/bpf/str_error.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __LIBBPF_STR_ERROR_H
+#define __LIBBPF_STR_ERROR_H
+
+char *libbpf_strerror_r(int err, char *dst, int len);
+#endif /* __LIBBPF_STR_ERROR_H */
diff --git a/src/contrib/libbpf/bpf/xsk.c b/src/contrib/libbpf/bpf/xsk.c
new file mode 100644
index 0000000..8e0ffa8
--- /dev/null
+++ b/src/contrib/libbpf/bpf/xsk.c
@@ -0,0 +1,797 @@
+// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+/*
+ * AF_XDP user-space access library.
+ *
+ * Copyright(c) 2018 - 2019 Intel Corporation.
+ *
+ * Author(s): Magnus Karlsson <magnus.karlsson@intel.com>
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <asm/barrier.h>
+#include <linux/compiler.h>
+#include <linux/ethtool.h>
+#include <linux/filter.h>
+#include <linux/if_ether.h>
+#include <linux/if_packet.h>
+#include <linux/if_xdp.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+
+#include "bpf.h"
+#include "libbpf.h"
+#include "libbpf_internal.h"
+#include "xsk.h"
+
+#ifndef SOL_XDP
+ #define SOL_XDP 283
+#endif
+
+#ifndef AF_XDP
+ #define AF_XDP 44
+#endif
+
+#ifndef PF_XDP
+ #define PF_XDP AF_XDP
+#endif
+
+struct xsk_umem {
+	struct xsk_ring_prod *fill;
+	struct xsk_ring_cons *comp;
+	char *umem_area;
+	struct xsk_umem_config config;
+	int fd;
+	int refcount;
+};
+
+struct xsk_socket {
+	struct xsk_ring_cons *rx;
+	struct xsk_ring_prod *tx;
+	__u64 outstanding_tx;
+	struct xsk_umem *umem;
+	struct xsk_socket_config config;
+	int fd;
+	int ifindex;
+	int prog_fd;
+	int xsks_map_fd;
+	__u32 queue_id;
+	char ifname[IFNAMSIZ];
+};
+
+struct xsk_nl_info {
+	bool xdp_prog_attached;
+	int ifindex;
+	int fd;
+};
+
+/* Up until and including Linux 5.3 */
+struct xdp_ring_offset_v1 {
+	__u64 producer;
+	__u64 consumer;
+	__u64 desc;
+};
+
+/* Up until and including Linux 5.3 */
+struct xdp_mmap_offsets_v1 {
+	struct xdp_ring_offset_v1 rx;
+	struct xdp_ring_offset_v1 tx;
+	struct xdp_ring_offset_v1 fr;
+	struct xdp_ring_offset_v1 cr;
+};
+
+int xsk_umem__fd(const struct xsk_umem *umem)
+{
+	return umem ? umem->fd : -EINVAL;
+}
+
+int xsk_socket__fd(const struct xsk_socket *xsk)
+{
+	return xsk ? xsk->fd : -EINVAL;
+}
+
+static bool xsk_page_aligned(void *buffer)
+{
+	unsigned long addr = (unsigned long)buffer;
+
+	return !(addr & (getpagesize() - 1));
+}
+
+static void xsk_set_umem_config(struct xsk_umem_config *cfg,
+				const struct xsk_umem_config *usr_cfg)
+{
+	if (!usr_cfg) {
+		cfg->fill_size = XSK_RING_PROD__DEFAULT_NUM_DESCS;
+		cfg->comp_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
+		cfg->frame_size = XSK_UMEM__DEFAULT_FRAME_SIZE;
+		cfg->frame_headroom = XSK_UMEM__DEFAULT_FRAME_HEADROOM;
+		cfg->flags = XSK_UMEM__DEFAULT_FLAGS;
+		return;
+	}
+
+	cfg->fill_size = usr_cfg->fill_size;
+	cfg->comp_size = usr_cfg->comp_size;
+	cfg->frame_size = usr_cfg->frame_size;
+	cfg->frame_headroom = usr_cfg->frame_headroom;
+	cfg->flags = usr_cfg->flags;
+}
+
+static int xsk_set_xdp_socket_config(struct xsk_socket_config *cfg,
+				     const struct xsk_socket_config *usr_cfg)
+{
+	if (!usr_cfg) {
+		cfg->rx_size = XSK_RING_CONS__DEFAULT_NUM_DESCS;
+		cfg->tx_size = XSK_RING_PROD__DEFAULT_NUM_DESCS;
+		cfg->libbpf_flags = 0;
+		cfg->xdp_flags = 0;
+		cfg->bind_flags = 0;
+		return 0;
+	}
+
+	if (usr_cfg->libbpf_flags & ~XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)
+		return -EINVAL;
+
+	cfg->rx_size = usr_cfg->rx_size;
+	cfg->tx_size = usr_cfg->tx_size;
+	cfg->libbpf_flags = usr_cfg->libbpf_flags;
+	cfg->xdp_flags = usr_cfg->xdp_flags;
+	cfg->bind_flags = usr_cfg->bind_flags;
+
+	return 0;
+}
+
+static void xsk_mmap_offsets_v1(struct xdp_mmap_offsets *off)
+{
+	struct xdp_mmap_offsets_v1 off_v1;
+
+	/* getsockopt on a kernel <= 5.3 has no flags fields.
+	 * Copy over the offsets to the correct places in the >=5.4 format
+	 * and put the flags where they would have been on that kernel.
+	 */
+	memcpy(&off_v1, off, sizeof(off_v1));
+
+	off->rx.producer = off_v1.rx.producer;
+	off->rx.consumer = off_v1.rx.consumer;
+	off->rx.desc = off_v1.rx.desc;
+	off->rx.flags = off_v1.rx.consumer + sizeof(__u32);
+
+	off->tx.producer = off_v1.tx.producer;
+	off->tx.consumer = off_v1.tx.consumer;
+	off->tx.desc = off_v1.tx.desc;
+	off->tx.flags = off_v1.tx.consumer + sizeof(__u32);
+
+	off->fr.producer = off_v1.fr.producer;
+	off->fr.consumer = off_v1.fr.consumer;
+	off->fr.desc = off_v1.fr.desc;
+	off->fr.flags = off_v1.fr.consumer + sizeof(__u32);
+
+	off->cr.producer = off_v1.cr.producer;
+	off->cr.consumer = off_v1.cr.consumer;
+	off->cr.desc = off_v1.cr.desc;
+	off->cr.flags = off_v1.cr.consumer + sizeof(__u32);
+}
+
+static int xsk_get_mmap_offsets(int fd, struct xdp_mmap_offsets *off)
+{
+	socklen_t optlen;
+	int err;
+
+	optlen = sizeof(*off);
+	err = getsockopt(fd, SOL_XDP, XDP_MMAP_OFFSETS, off, &optlen);
+	if (err)
+		return err;
+
+	if (optlen == sizeof(*off))
+		return 0;
+
+	if (optlen == sizeof(struct xdp_mmap_offsets_v1)) {
+		xsk_mmap_offsets_v1(off);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+int xsk_umem__create_v0_0_4(struct xsk_umem **umem_ptr, void *umem_area,
+			    __u64 size, struct xsk_ring_prod *fill,
+			    struct xsk_ring_cons *comp,
+			    const struct xsk_umem_config *usr_config)
+{
+	struct xdp_mmap_offsets off;
+	struct xdp_umem_reg mr;
+	struct xsk_umem *umem;
+	void *map;
+	int err;
+
+	if (!umem_area || !umem_ptr || !fill || !comp)
+		return -EFAULT;
+	if (!size && !xsk_page_aligned(umem_area))
+		return -EINVAL;
+
+	umem = calloc(1, sizeof(*umem));
+	if (!umem)
+		return -ENOMEM;
+
+	umem->fd = socket(AF_XDP, SOCK_RAW, 0);
+	if (umem->fd < 0) {
+		err = -errno;
+		goto out_umem_alloc;
+	}
+
+	umem->umem_area = umem_area;
+	xsk_set_umem_config(&umem->config, usr_config);
+
+	memset(&mr, 0, sizeof(mr));
+	mr.addr = (uintptr_t)umem_area;
+	mr.len = size;
+	mr.chunk_size = umem->config.frame_size;
+	mr.headroom = umem->config.frame_headroom;
+	mr.flags = umem->config.flags;
+
+	err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_REG, &mr, sizeof(mr));
+	if (err) {
+		err = -errno;
+		goto out_socket;
+	}
+	err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_FILL_RING,
+			 &umem->config.fill_size,
+			 sizeof(umem->config.fill_size));
+	if (err) {
+		err = -errno;
+		goto out_socket;
+	}
+	err = setsockopt(umem->fd, SOL_XDP, XDP_UMEM_COMPLETION_RING,
+			 &umem->config.comp_size,
+			 sizeof(umem->config.comp_size));
+	if (err) {
+		err = -errno;
+		goto out_socket;
+	}
+
+	err = xsk_get_mmap_offsets(umem->fd, &off);
+	if (err) {
+		err = -errno;
+		goto out_socket;
+	}
+
+	map = mmap(NULL, off.fr.desc + umem->config.fill_size * sizeof(__u64),
+		   PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
+		   XDP_UMEM_PGOFF_FILL_RING);
+	if (map == MAP_FAILED) {
+		err = -errno;
+		goto out_socket;
+	}
+
+	umem->fill = fill;
+	fill->mask = umem->config.fill_size - 1;
+	fill->size = umem->config.fill_size;
+	fill->producer = map + off.fr.producer;
+	fill->consumer = map + off.fr.consumer;
+	fill->flags = map + off.fr.flags;
+	fill->ring = map + off.fr.desc;
+	fill->cached_cons = umem->config.fill_size;
+
+	map = mmap(NULL, off.cr.desc + umem->config.comp_size * sizeof(__u64),
+		   PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE, umem->fd,
+		   XDP_UMEM_PGOFF_COMPLETION_RING);
+	if (map == MAP_FAILED) {
+		err = -errno;
+		goto out_mmap;
+	}
+
+	umem->comp = comp;
+	comp->mask = umem->config.comp_size - 1;
+	comp->size = umem->config.comp_size;
+	comp->producer = map + off.cr.producer;
+	comp->consumer = map + off.cr.consumer;
+	comp->flags = map + off.cr.flags;
+	comp->ring = map + off.cr.desc;
+
+	*umem_ptr = umem;
+	return 0;
+
+out_mmap:
+	munmap(map, off.fr.desc + umem->config.fill_size * sizeof(__u64));
+out_socket:
+	close(umem->fd);
+out_umem_alloc:
+	free(umem);
+	return err;
+}
+
+struct xsk_umem_config_v1 {
+	__u32 fill_size;
+	__u32 comp_size;
+	__u32 frame_size;
+	__u32 frame_headroom;
+};
+
+int xsk_umem__create_v0_0_2(struct xsk_umem **umem_ptr, void *umem_area,
+			    __u64 size, struct xsk_ring_prod *fill,
+			    struct xsk_ring_cons *comp,
+			    const struct xsk_umem_config *usr_config)
+{
+	struct xsk_umem_config config;
+
+	memcpy(&config, usr_config, sizeof(struct xsk_umem_config_v1));
+	config.flags = 0;
+
+	return xsk_umem__create_v0_0_4(umem_ptr, umem_area, size, fill, comp,
+					&config);
+}
+COMPAT_VERSION(xsk_umem__create_v0_0_2, xsk_umem__create, LIBBPF_0.0.2)
+DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, LIBBPF_0.0.4)
+
+static int xsk_load_xdp_prog(struct xsk_socket *xsk)
+{
+	static const int log_buf_size = 16 * 1024;
+	char log_buf[log_buf_size];
+	int err, prog_fd;
+
+	/* This is the C-program:
+	 * SEC("xdp_sock") int xdp_sock_prog(struct xdp_md *ctx)
+	 * {
+	 *     int ret, index = ctx->rx_queue_index;
+	 *
+	 *     // A set entry here means that the correspnding queue_id
+	 *     // has an active AF_XDP socket bound to it.
+	 *     ret = bpf_redirect_map(&xsks_map, index, XDP_PASS);
+	 *     if (ret > 0)
+	 *         return ret;
+	 *
+	 *     // Fallback for pre-5.3 kernels, not supporting default
+	 *     // action in the flags parameter.
+	 *     if (bpf_map_lookup_elem(&xsks_map, &index))
+	 *         return bpf_redirect_map(&xsks_map, index, 0);
+	 *     return XDP_PASS;
+	 * }
+	 */
+	struct bpf_insn prog[] = {
+		/* r2 = *(u32 *)(r1 + 16) */
+		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_1, 16),
+		/* *(u32 *)(r10 - 4) = r2 */
+		BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_2, -4),
+		/* r1 = xskmap[] */
+		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* r3 = XDP_PASS */
+		BPF_MOV64_IMM(BPF_REG_3, 2),
+		/* call bpf_redirect_map */
+		BPF_EMIT_CALL(BPF_FUNC_redirect_map),
+		/* if w0 != 0 goto pc+13 */
+		BPF_JMP32_IMM(BPF_JSGT, BPF_REG_0, 0, 13),
+		/* r2 = r10 */
+		BPF_MOV64_REG(BPF_REG_2, BPF_REG_10),
+		/* r2 += -4 */
+		BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4),
+		/* r1 = xskmap[] */
+		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* call bpf_map_lookup_elem */
+		BPF_EMIT_CALL(BPF_FUNC_map_lookup_elem),
+		/* r1 = r0 */
+		BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
+		/* r0 = XDP_PASS */
+		BPF_MOV64_IMM(BPF_REG_0, 2),
+		/* if r1 == 0 goto pc+5 */
+		BPF_JMP_IMM(BPF_JEQ, BPF_REG_1, 0, 5),
+		/* r2 = *(u32 *)(r10 - 4) */
+		BPF_LDX_MEM(BPF_W, BPF_REG_2, BPF_REG_10, -4),
+		/* r1 = xskmap[] */
+		BPF_LD_MAP_FD(BPF_REG_1, xsk->xsks_map_fd),
+		/* r3 = 0 */
+		BPF_MOV64_IMM(BPF_REG_3, 0),
+		/* call bpf_redirect_map */
+		BPF_EMIT_CALL(BPF_FUNC_redirect_map),
+		/* The jumps are to this instruction */
+		BPF_EXIT_INSN(),
+	};
+	size_t insns_cnt = sizeof(prog) / sizeof(struct bpf_insn);
+
+	prog_fd = bpf_load_program(BPF_PROG_TYPE_XDP, prog, insns_cnt,
+				   "LGPL-2.1 or BSD-2-Clause", 0, log_buf,
+				   log_buf_size);
+	if (prog_fd < 0) {
+		pr_warn("BPF log buffer:\n%s", log_buf);
+		return prog_fd;
+	}
+
+	err = bpf_set_link_xdp_fd(xsk->ifindex, prog_fd, xsk->config.xdp_flags);
+	if (err) {
+		close(prog_fd);
+		return err;
+	}
+
+	xsk->prog_fd = prog_fd;
+	return 0;
+}
+
+static int xsk_get_max_queues(struct xsk_socket *xsk)
+{
+	struct ethtool_channels channels = { .cmd = ETHTOOL_GCHANNELS };
+	struct ifreq ifr = {};
+	int fd, err, ret;
+
+	fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0)
+		return -errno;
+
+	ifr.ifr_data = (void *)&channels;
+	memcpy(ifr.ifr_name, xsk->ifname, IFNAMSIZ - 1);
+	ifr.ifr_name[IFNAMSIZ - 1] = '\0';
+	err = ioctl(fd, SIOCETHTOOL, &ifr);
+	if (err && errno != EOPNOTSUPP) {
+		ret = -errno;
+		goto out;
+	}
+
+	if (err) {
+		/* If the device says it has no channels, then all traffic
+		 * is sent to a single stream, so max queues = 1.
+		 */
+		ret = 1;
+	} else {
+		/* Take the max of rx, tx, combined. Drivers return
+		 * the number of channels in different ways.
+		 */
+		ret = max(channels.max_rx, channels.max_tx);
+		ret = max(ret, (int)channels.max_combined);
+	}
+
+out:
+	close(fd);
+	return ret;
+}
+
+static int xsk_create_bpf_maps(struct xsk_socket *xsk)
+{
+	int max_queues;
+	int fd;
+
+	max_queues = xsk_get_max_queues(xsk);
+	if (max_queues < 0)
+		return max_queues;
+
+	fd = bpf_create_map_name(BPF_MAP_TYPE_XSKMAP, "xsks_map",
+				 sizeof(int), sizeof(int), max_queues, 0);
+	if (fd < 0)
+		return fd;
+
+	xsk->xsks_map_fd = fd;
+
+	return 0;
+}
+
+static void xsk_delete_bpf_maps(struct xsk_socket *xsk)
+{
+	bpf_map_delete_elem(xsk->xsks_map_fd, &xsk->queue_id);
+	close(xsk->xsks_map_fd);
+}
+
+static int xsk_lookup_bpf_maps(struct xsk_socket *xsk)
+{
+	__u32 i, *map_ids, num_maps, prog_len = sizeof(struct bpf_prog_info);
+	__u32 map_len = sizeof(struct bpf_map_info);
+	struct bpf_prog_info prog_info = {};
+	struct bpf_map_info map_info;
+	int fd, err;
+
+	err = bpf_obj_get_info_by_fd(xsk->prog_fd, &prog_info, &prog_len);
+	if (err)
+		return err;
+
+	num_maps = prog_info.nr_map_ids;
+
+	map_ids = calloc(prog_info.nr_map_ids, sizeof(*map_ids));
+	if (!map_ids)
+		return -ENOMEM;
+
+	memset(&prog_info, 0, prog_len);
+	prog_info.nr_map_ids = num_maps;
+	prog_info.map_ids = (__u64)(unsigned long)map_ids;
+
+	err = bpf_obj_get_info_by_fd(xsk->prog_fd, &prog_info, &prog_len);
+	if (err)
+		goto out_map_ids;
+
+	xsk->xsks_map_fd = -1;
+
+	for (i = 0; i < prog_info.nr_map_ids; i++) {
+		fd = bpf_map_get_fd_by_id(map_ids[i]);
+		if (fd < 0)
+			continue;
+
+		err = bpf_obj_get_info_by_fd(fd, &map_info, &map_len);
+		if (err) {
+			close(fd);
+			continue;
+		}
+
+		if (!strcmp(map_info.name, "xsks_map")) {
+			xsk->xsks_map_fd = fd;
+			continue;
+		}
+
+		close(fd);
+	}
+
+	err = 0;
+	if (xsk->xsks_map_fd == -1)
+		err = -ENOENT;
+
+out_map_ids:
+	free(map_ids);
+	return err;
+}
+
+static int xsk_set_bpf_maps(struct xsk_socket *xsk)
+{
+	return bpf_map_update_elem(xsk->xsks_map_fd, &xsk->queue_id,
+				   &xsk->fd, 0);
+}
+
+static int xsk_setup_xdp_prog(struct xsk_socket *xsk)
+{
+	__u32 prog_id = 0;
+	int err;
+
+	err = bpf_get_link_xdp_id(xsk->ifindex, &prog_id,
+				  xsk->config.xdp_flags);
+	if (err)
+		return err;
+
+	if (!prog_id) {
+		err = xsk_create_bpf_maps(xsk);
+		if (err)
+			return err;
+
+		err = xsk_load_xdp_prog(xsk);
+		if (err) {
+			xsk_delete_bpf_maps(xsk);
+			return err;
+		}
+	} else {
+		xsk->prog_fd = bpf_prog_get_fd_by_id(prog_id);
+		if (xsk->prog_fd < 0)
+			return -errno;
+		err = xsk_lookup_bpf_maps(xsk);
+		if (err) {
+			close(xsk->prog_fd);
+			return err;
+		}
+	}
+
+	if (xsk->rx)
+		err = xsk_set_bpf_maps(xsk);
+	if (err) {
+		xsk_delete_bpf_maps(xsk);
+		close(xsk->prog_fd);
+		return err;
+	}
+
+	return 0;
+}
+
+int xsk_socket__create(struct xsk_socket **xsk_ptr, const char *ifname,
+		       __u32 queue_id, struct xsk_umem *umem,
+		       struct xsk_ring_cons *rx, struct xsk_ring_prod *tx,
+		       const struct xsk_socket_config *usr_config)
+{
+	void *rx_map = NULL, *tx_map = NULL;
+	struct sockaddr_xdp sxdp = {};
+	struct xdp_mmap_offsets off;
+	struct xsk_socket *xsk;
+	int err;
+
+	if (!umem || !xsk_ptr || !(rx || tx))
+		return -EFAULT;
+
+	xsk = calloc(1, sizeof(*xsk));
+	if (!xsk)
+		return -ENOMEM;
+
+	err = xsk_set_xdp_socket_config(&xsk->config, usr_config);
+	if (err)
+		goto out_xsk_alloc;
+
+	if (umem->refcount &&
+	    !(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
+		pr_warn("Error: shared umems not supported by libbpf supplied XDP program.\n");
+		err = -EBUSY;
+		goto out_xsk_alloc;
+	}
+
+	if (umem->refcount++ > 0) {
+		xsk->fd = socket(AF_XDP, SOCK_RAW, 0);
+		if (xsk->fd < 0) {
+			err = -errno;
+			goto out_xsk_alloc;
+		}
+	} else {
+		xsk->fd = umem->fd;
+	}
+
+	xsk->outstanding_tx = 0;
+	xsk->queue_id = queue_id;
+	xsk->umem = umem;
+	xsk->ifindex = if_nametoindex(ifname);
+	if (!xsk->ifindex) {
+		err = -errno;
+		goto out_socket;
+	}
+	memcpy(xsk->ifname, ifname, IFNAMSIZ - 1);
+	xsk->ifname[IFNAMSIZ - 1] = '\0';
+
+	if (rx) {
+		err = setsockopt(xsk->fd, SOL_XDP, XDP_RX_RING,
+				 &xsk->config.rx_size,
+				 sizeof(xsk->config.rx_size));
+		if (err) {
+			err = -errno;
+			goto out_socket;
+		}
+	}
+	if (tx) {
+		err = setsockopt(xsk->fd, SOL_XDP, XDP_TX_RING,
+				 &xsk->config.tx_size,
+				 sizeof(xsk->config.tx_size));
+		if (err) {
+			err = -errno;
+			goto out_socket;
+		}
+	}
+
+	err = xsk_get_mmap_offsets(xsk->fd, &off);
+	if (err) {
+		err = -errno;
+		goto out_socket;
+	}
+
+	if (rx) {
+		rx_map = mmap(NULL, off.rx.desc +
+			      xsk->config.rx_size * sizeof(struct xdp_desc),
+			      PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
+			      xsk->fd, XDP_PGOFF_RX_RING);
+		if (rx_map == MAP_FAILED) {
+			err = -errno;
+			goto out_socket;
+		}
+
+		rx->mask = xsk->config.rx_size - 1;
+		rx->size = xsk->config.rx_size;
+		rx->producer = rx_map + off.rx.producer;
+		rx->consumer = rx_map + off.rx.consumer;
+		rx->flags = rx_map + off.rx.flags;
+		rx->ring = rx_map + off.rx.desc;
+	}
+	xsk->rx = rx;
+
+	if (tx) {
+		tx_map = mmap(NULL, off.tx.desc +
+			      xsk->config.tx_size * sizeof(struct xdp_desc),
+			      PROT_READ | PROT_WRITE, MAP_SHARED | MAP_POPULATE,
+			      xsk->fd, XDP_PGOFF_TX_RING);
+		if (tx_map == MAP_FAILED) {
+			err = -errno;
+			goto out_mmap_rx;
+		}
+
+		tx->mask = xsk->config.tx_size - 1;
+		tx->size = xsk->config.tx_size;
+		tx->producer = tx_map + off.tx.producer;
+		tx->consumer = tx_map + off.tx.consumer;
+		tx->flags = tx_map + off.tx.flags;
+		tx->ring = tx_map + off.tx.desc;
+		tx->cached_cons = xsk->config.tx_size;
+	}
+	xsk->tx = tx;
+
+	sxdp.sxdp_family = PF_XDP;
+	sxdp.sxdp_ifindex = xsk->ifindex;
+	sxdp.sxdp_queue_id = xsk->queue_id;
+	if (umem->refcount > 1) {
+		sxdp.sxdp_flags = XDP_SHARED_UMEM;
+		sxdp.sxdp_shared_umem_fd = umem->fd;
+	} else {
+		sxdp.sxdp_flags = xsk->config.bind_flags;
+	}
+
+	err = bind(xsk->fd, (struct sockaddr *)&sxdp, sizeof(sxdp));
+	if (err) {
+		err = -errno;
+		goto out_mmap_tx;
+	}
+
+	xsk->prog_fd = -1;
+
+	if (!(xsk->config.libbpf_flags & XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD)) {
+		err = xsk_setup_xdp_prog(xsk);
+		if (err)
+			goto out_mmap_tx;
+	}
+
+	*xsk_ptr = xsk;
+	return 0;
+
+out_mmap_tx:
+	if (tx)
+		munmap(tx_map, off.tx.desc +
+		       xsk->config.tx_size * sizeof(struct xdp_desc));
+out_mmap_rx:
+	if (rx)
+		munmap(rx_map, off.rx.desc +
+		       xsk->config.rx_size * sizeof(struct xdp_desc));
+out_socket:
+	if (--umem->refcount)
+		close(xsk->fd);
+out_xsk_alloc:
+	free(xsk);
+	return err;
+}
+
+int xsk_umem__delete(struct xsk_umem *umem)
+{
+	struct xdp_mmap_offsets off;
+	int err;
+
+	if (!umem)
+		return 0;
+
+	if (umem->refcount)
+		return -EBUSY;
+
+	err = xsk_get_mmap_offsets(umem->fd, &off);
+	if (!err) {
+		munmap(umem->fill->ring - off.fr.desc,
+		       off.fr.desc + umem->config.fill_size * sizeof(__u64));
+		munmap(umem->comp->ring - off.cr.desc,
+		       off.cr.desc + umem->config.comp_size * sizeof(__u64));
+	}
+
+	close(umem->fd);
+	free(umem);
+
+	return 0;
+}
+
+void xsk_socket__delete(struct xsk_socket *xsk)
+{
+	size_t desc_sz = sizeof(struct xdp_desc);
+	struct xdp_mmap_offsets off;
+	int err;
+
+	if (!xsk)
+		return;
+
+	if (xsk->prog_fd != -1) {
+		xsk_delete_bpf_maps(xsk);
+		close(xsk->prog_fd);
+	}
+
+	err = xsk_get_mmap_offsets(xsk->fd, &off);
+	if (!err) {
+		if (xsk->rx) {
+			munmap(xsk->rx->ring - off.rx.desc,
+			       off.rx.desc + xsk->config.rx_size * desc_sz);
+		}
+		if (xsk->tx) {
+			munmap(xsk->tx->ring - off.tx.desc,
+			       off.tx.desc + xsk->config.tx_size * desc_sz);
+		}
+
+	}
+
+	xsk->umem->refcount--;
+	/* Do not close an fd that also has an associated umem connected
+	 * to it.
+	 */
+	if (xsk->fd != xsk->umem->fd)
+		close(xsk->fd);
+	free(xsk);
+}
diff --git a/src/contrib/libbpf/bpf/xsk.h b/src/contrib/libbpf/bpf/xsk.h
new file mode 100644
index 0000000..584f682
--- /dev/null
+++ b/src/contrib/libbpf/bpf/xsk.h
@@ -0,0 +1,246 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+/*
+ * AF_XDP user-space access library.
+ *
+ * Copyright(c) 2018 - 2019 Intel Corporation.
+ *
+ * Author(s): Magnus Karlsson <magnus.karlsson@intel.com>
+ */
+
+#ifndef __LIBBPF_XSK_H
+#define __LIBBPF_XSK_H
+
+#include <stdio.h>
+#include <stdint.h>
+#include <linux/if_xdp.h>
+
+#include "libbpf.h"
+#include "libbpf_util.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* Do not access these members directly. Use the functions below. */
+#define DEFINE_XSK_RING(name) \
+struct name { \
+	__u32 cached_prod; \
+	__u32 cached_cons; \
+	__u32 mask; \
+	__u32 size; \
+	__u32 *producer; \
+	__u32 *consumer; \
+	void *ring; \
+	__u32 *flags; \
+}
+
+DEFINE_XSK_RING(xsk_ring_prod);
+DEFINE_XSK_RING(xsk_ring_cons);
+
+/* For a detailed explanation on the memory barriers associated with the
+ * ring, please take a look at net/xdp/xsk_queue.h.
+ */
+
+struct xsk_umem;
+struct xsk_socket;
+
+static inline __u64 *xsk_ring_prod__fill_addr(struct xsk_ring_prod *fill,
+					      __u32 idx)
+{
+	__u64 *addrs = (__u64 *)fill->ring;
+
+	return &addrs[idx & fill->mask];
+}
+
+static inline const __u64 *
+xsk_ring_cons__comp_addr(const struct xsk_ring_cons *comp, __u32 idx)
+{
+	const __u64 *addrs = (const __u64 *)comp->ring;
+
+	return &addrs[idx & comp->mask];
+}
+
+static inline struct xdp_desc *xsk_ring_prod__tx_desc(struct xsk_ring_prod *tx,
+						      __u32 idx)
+{
+	struct xdp_desc *descs = (struct xdp_desc *)tx->ring;
+
+	return &descs[idx & tx->mask];
+}
+
+static inline const struct xdp_desc *
+xsk_ring_cons__rx_desc(const struct xsk_ring_cons *rx, __u32 idx)
+{
+	const struct xdp_desc *descs = (const struct xdp_desc *)rx->ring;
+
+	return &descs[idx & rx->mask];
+}
+
+static inline int xsk_ring_prod__needs_wakeup(const struct xsk_ring_prod *r)
+{
+	return *r->flags & XDP_RING_NEED_WAKEUP;
+}
+
+static inline __u32 xsk_prod_nb_free(struct xsk_ring_prod *r, __u32 nb)
+{
+	__u32 free_entries = r->cached_cons - r->cached_prod;
+
+	if (free_entries >= nb)
+		return free_entries;
+
+	/* Refresh the local tail pointer.
+	 * cached_cons is r->size bigger than the real consumer pointer so
+	 * that this addition can be avoided in the more frequently
+	 * executed code that computs free_entries in the beginning of
+	 * this function. Without this optimization it whould have been
+	 * free_entries = r->cached_prod - r->cached_cons + r->size.
+	 */
+	r->cached_cons = *r->consumer + r->size;
+
+	return r->cached_cons - r->cached_prod;
+}
+
+static inline __u32 xsk_cons_nb_avail(struct xsk_ring_cons *r, __u32 nb)
+{
+	__u32 entries = r->cached_prod - r->cached_cons;
+
+	if (entries == 0) {
+		r->cached_prod = *r->producer;
+		entries = r->cached_prod - r->cached_cons;
+	}
+
+	return (entries > nb) ? nb : entries;
+}
+
+static inline size_t xsk_ring_prod__reserve(struct xsk_ring_prod *prod,
+					    size_t nb, __u32 *idx)
+{
+	if (xsk_prod_nb_free(prod, nb) < nb)
+		return 0;
+
+	*idx = prod->cached_prod;
+	prod->cached_prod += nb;
+
+	return nb;
+}
+
+static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
+{
+	/* Make sure everything has been written to the ring before indicating
+	 * this to the kernel by writing the producer pointer.
+	 */
+	libbpf_smp_wmb();
+
+	*prod->producer += nb;
+}
+
+static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
+					 size_t nb, __u32 *idx)
+{
+	size_t entries = xsk_cons_nb_avail(cons, nb);
+
+	if (entries > 0) {
+		/* Make sure we do not speculatively read the data before
+		 * we have received the packet buffers from the ring.
+		 */
+		libbpf_smp_rmb();
+
+		*idx = cons->cached_cons;
+		cons->cached_cons += entries;
+	}
+
+	return entries;
+}
+
+static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, size_t nb)
+{
+	/* Make sure data has been read before indicating we are done
+	 * with the entries by updating the consumer pointer.
+	 */
+	libbpf_smp_rwmb();
+
+	*cons->consumer += nb;
+}
+
+static inline void *xsk_umem__get_data(void *umem_area, __u64 addr)
+{
+	return &((char *)umem_area)[addr];
+}
+
+static inline __u64 xsk_umem__extract_addr(__u64 addr)
+{
+	return addr & XSK_UNALIGNED_BUF_ADDR_MASK;
+}
+
+static inline __u64 xsk_umem__extract_offset(__u64 addr)
+{
+	return addr >> XSK_UNALIGNED_BUF_OFFSET_SHIFT;
+}
+
+static inline __u64 xsk_umem__add_offset_to_addr(__u64 addr)
+{
+	return xsk_umem__extract_addr(addr) + xsk_umem__extract_offset(addr);
+}
+
+LIBBPF_API int xsk_umem__fd(const struct xsk_umem *umem);
+LIBBPF_API int xsk_socket__fd(const struct xsk_socket *xsk);
+
+#define XSK_RING_CONS__DEFAULT_NUM_DESCS      2048
+#define XSK_RING_PROD__DEFAULT_NUM_DESCS      2048
+#define XSK_UMEM__DEFAULT_FRAME_SHIFT    12 /* 4096 bytes */
+#define XSK_UMEM__DEFAULT_FRAME_SIZE     (1 << XSK_UMEM__DEFAULT_FRAME_SHIFT)
+#define XSK_UMEM__DEFAULT_FRAME_HEADROOM 0
+#define XSK_UMEM__DEFAULT_FLAGS 0
+
+struct xsk_umem_config {
+	__u32 fill_size;
+	__u32 comp_size;
+	__u32 frame_size;
+	__u32 frame_headroom;
+	__u32 flags;
+};
+
+/* Flags for the libbpf_flags field. */
+#define XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD (1 << 0)
+
+struct xsk_socket_config {
+	__u32 rx_size;
+	__u32 tx_size;
+	__u32 libbpf_flags;
+	__u32 xdp_flags;
+	__u16 bind_flags;
+};
+
+/* Set config to NULL to get the default configuration. */
+LIBBPF_API int xsk_umem__create(struct xsk_umem **umem,
+				void *umem_area, __u64 size,
+				struct xsk_ring_prod *fill,
+				struct xsk_ring_cons *comp,
+				const struct xsk_umem_config *config);
+LIBBPF_API int xsk_umem__create_v0_0_2(struct xsk_umem **umem,
+				       void *umem_area, __u64 size,
+				       struct xsk_ring_prod *fill,
+				       struct xsk_ring_cons *comp,
+				       const struct xsk_umem_config *config);
+LIBBPF_API int xsk_umem__create_v0_0_4(struct xsk_umem **umem,
+				       void *umem_area, __u64 size,
+				       struct xsk_ring_prod *fill,
+				       struct xsk_ring_cons *comp,
+				       const struct xsk_umem_config *config);
+LIBBPF_API int xsk_socket__create(struct xsk_socket **xsk,
+				  const char *ifname, __u32 queue_id,
+				  struct xsk_umem *umem,
+				  struct xsk_ring_cons *rx,
+				  struct xsk_ring_prod *tx,
+				  const struct xsk_socket_config *config);
+
+/* Returns 0 for success and -EBUSY if the umem is still in use. */
+LIBBPF_API int xsk_umem__delete(struct xsk_umem *umem);
+LIBBPF_API void xsk_socket__delete(struct xsk_socket *xsk);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* __LIBBPF_XSK_H */
diff --git a/src/contrib/libbpf/include/asm/barrier.h b/src/contrib/libbpf/include/asm/barrier.h
new file mode 100644
index 0000000..1fc6aee
--- /dev/null
+++ b/src/contrib/libbpf/include/asm/barrier.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef __ASM_BARRIER_H
+#define __ASM_BARRIER_H
+
+#include <linux/compiler.h>
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/compiler.h b/src/contrib/libbpf/include/linux/compiler.h
new file mode 100644
index 0000000..26336dc
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/compiler.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_COMPILER_H
+#define __LINUX_COMPILER_H
+
+#define likely(x)		__builtin_expect(!!(x), 1)
+#define unlikely(x)		__builtin_expect(!!(x), 0)
+
+#define READ_ONCE(x)		(*(volatile typeof(x) *)&x)
+#define WRITE_ONCE(x, v)	(*(volatile typeof(x) *)&x) = (v)
+
+#define barrier()		asm volatile("" ::: "memory")
+
+#if defined(__x86_64__)
+
+# define smp_rmb()		barrier()
+# define smp_wmb()		barrier()
+# define smp_mb()		asm volatile("lock; addl $0,-132(%%rsp)" ::: "memory", "cc")
+
+# define smp_store_release(p, v)		\
+do {						\
+	barrier();				\
+	WRITE_ONCE(*p, v);			\
+} while (0)
+
+# define smp_load_acquire(p)			\
+({						\
+	typeof(*p) ___p = READ_ONCE(*p);	\
+	barrier();				\
+	___p;					\
+})
+
+#elif defined(__aarch64__)
+
+# define smp_rmb()		asm volatile("dmb ishld" ::: "memory")
+# define smp_wmb()		asm volatile("dmb ishst" ::: "memory")
+# define smp_mb()		asm volatile("dmb ish" ::: "memory")
+
+#endif
+
+#ifndef smp_mb
+# define smp_mb()		__sync_synchronize()
+#endif
+
+#ifndef smp_rmb
+# define smp_rmb()		smp_mb()
+#endif
+
+#ifndef smp_wmb
+# define smp_wmb()		smp_mb()
+#endif
+
+#ifndef smp_store_release
+# define smp_store_release(p, v)		\
+do {						\
+	smp_mb();				\
+	WRITE_ONCE(*p, v);			\
+} while (0)
+#endif
+
+#ifndef smp_load_acquire
+# define smp_load_acquire(p)			\
+({						\
+	typeof(*p) ___p = READ_ONCE(*p);	\
+	smp_mb();				\
+	___p;					\
+})
+#endif
+
+#endif /* __LINUX_COMPILER_H */
diff --git a/src/contrib/libbpf/include/linux/err.h b/src/contrib/libbpf/include/linux/err.h
new file mode 100644
index 0000000..1b1dafb
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/err.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_ERR_H
+#define __LINUX_ERR_H
+
+#include <linux/types.h>
+#include <asm/errno.h>
+
+#define MAX_ERRNO       4095
+
+#define IS_ERR_VALUE(x) ((x) >= (unsigned long)-MAX_ERRNO)
+
+static inline void * ERR_PTR(long error_)
+{
+	return (void *) error_;
+}
+
+static inline long PTR_ERR(const void *ptr)
+{
+	return (long) ptr;
+}
+
+static inline bool IS_ERR(const void *ptr)
+{
+	return IS_ERR_VALUE((unsigned long)ptr);
+}
+
+static inline bool IS_ERR_OR_NULL(const void *ptr)
+{
+	return (!ptr) || IS_ERR_VALUE((unsigned long)ptr);
+}
+
+static inline long PTR_ERR_OR_ZERO(const void *ptr)
+{
+	return IS_ERR(ptr) ? PTR_ERR(ptr) : 0;
+}
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/filter.h b/src/contrib/libbpf/include/linux/filter.h
new file mode 100644
index 0000000..b0700e2
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/filter.h
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_FILTER_H
+#define __LINUX_FILTER_H
+
+#include <linux/bpf.h>
+
+#define BPF_ALU64_IMM(OP, DST, IMM)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_ALU64 | BPF_OP(OP) | BPF_K,	\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = 0,					\
+		.imm   = IMM })
+
+#define BPF_MOV64_IMM(DST, IMM)					\
+	((struct bpf_insn) {					\
+		.code  = BPF_ALU64 | BPF_MOV | BPF_K,		\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = 0,					\
+		.imm   = IMM })
+
+#define BPF_EXIT_INSN()						\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP | BPF_EXIT,			\
+		.dst_reg = 0,					\
+		.src_reg = 0,					\
+		.off   = 0,					\
+		.imm   = 0 })
+
+#define BPF_EMIT_CALL(FUNC)					\
+	((struct bpf_insn) {					\
+		.code  = BPF_JMP | BPF_CALL,			\
+		.dst_reg = 0,					\
+		.src_reg = 0,					\
+		.off   = 0,					\
+		.imm   = ((FUNC) - BPF_FUNC_unspec) })
+
+#define BPF_LDX_MEM(SIZE, DST, SRC, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_LDX | BPF_SIZE(SIZE) | BPF_MEM,	\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = OFF,					\
+		.imm   = 0 })
+
+#define BPF_STX_MEM(SIZE, DST, SRC, OFF)			\
+	((struct bpf_insn) {					\
+		.code  = BPF_STX | BPF_SIZE(SIZE) | BPF_MEM,	\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = OFF,					\
+		.imm   = 0 })
+
+#define BPF_ST_MEM(SIZE, DST, OFF, IMM)				\
+	((struct bpf_insn) {					\
+		.code  = BPF_ST | BPF_SIZE(SIZE) | BPF_MEM,	\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = OFF,					\
+		.imm   = IMM })
+
+#define BPF_MOV64_REG(DST, SRC)					\
+	((struct bpf_insn) {					\
+		.code  = BPF_ALU64 | BPF_MOV | BPF_X,		\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = 0,					\
+		.imm   = 0 })
+
+#define BPF_MOV32_IMM(DST, IMM)					\
+	((struct bpf_insn) {					\
+		.code = BPF_ALU | BPF_MOV | BPF_K,		\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off   = 0,					\
+		.imm   = IMM })
+
+#define BPF_LD_IMM64_RAW_FULL(DST, SRC, OFF1, OFF2, IMM1, IMM2)	\
+	((struct bpf_insn) {					\
+		.code = BPF_LD | BPF_DW | BPF_IMM,		\
+		.dst_reg = DST,					\
+		.src_reg = SRC,					\
+		.off   = OFF1,					\
+		.imm   = IMM1 }),			\
+	((struct bpf_insn) {					\
+		.code  = 0,					\
+		.dst_reg = 0,					\
+		.src_reg = 0,					\
+		.off   = OFF2,					\
+		.imm   = IMM2 })
+
+#define BPF_LD_MAP_FD(DST, MAP_FD)				\
+	BPF_LD_IMM64_RAW_FULL(DST, BPF_PSEUDO_MAP_FD, 0, 0,	\
+			      MAP_FD, 0)
+
+#define BPF_LD_MAP_VALUE(DST, MAP_FD, VALUE_OFF)		\
+	BPF_LD_IMM64_RAW_FULL(DST, BPF_PSEUDO_MAP_VALUE, 0, 0,	\
+			      MAP_FD, VALUE_OFF)
+
+#define BPF_JMP_IMM(OP, DST, IMM, OFF)				\
+	((struct bpf_insn) {					\
+		.code = BPF_JMP | BPF_OP(OP) | BPF_K,		\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off  = OFF,					\
+		.imm  = IMM })
+
+#define BPF_JMP32_IMM(OP, DST, IMM, OFF)			\
+	((struct bpf_insn) {					\
+		.code = BPF_JMP32 | BPF_OP(OP) | BPF_K,		\
+		.dst_reg = DST,					\
+		.src_reg = 0,					\
+		.off  = OFF,					\
+		.imm  = IMM })
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/kernel.h b/src/contrib/libbpf/include/linux/kernel.h
new file mode 100644
index 0000000..a4a7a9d
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/kernel.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_KERNEL_H
+#define __LINUX_KERNEL_H
+
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#endif
+
+#ifndef container_of
+#define container_of(ptr, type, member) ({			\
+	const typeof(((type *)0)->member) * __mptr = (ptr);	\
+	(type *)((char *)__mptr - offsetof(type, member)); })
+#endif
+
+#ifndef max
+#define max(x, y) ({				\
+	typeof(x) _max1 = (x);			\
+	typeof(y) _max2 = (y);			\
+	(void) (&_max1 == &_max2);		\
+	_max1 > _max2 ? _max1 : _max2; })
+#endif
+
+#ifndef min
+#define min(x, y) ({				\
+	typeof(x) _min1 = (x);			\
+	typeof(y) _min2 = (y);			\
+	(void) (&_min1 == &_min2);		\
+	_min1 < _min2 ? _min1 : _min2; })
+#endif
+
+#ifndef roundup
+#define roundup(x, y) (				\
+{						\
+	const typeof(y) __y = y;		\
+	(((x) + (__y - 1)) / __y) * __y;	\
+}						\
+)
+#endif
+
+#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
+#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/list.h b/src/contrib/libbpf/include/linux/list.h
new file mode 100644
index 0000000..e3814f7
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/list.h
@@ -0,0 +1,82 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_LIST_H
+#define __LINUX_LIST_H
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+#define LIST_HEAD(name) \
+        struct list_head name = LIST_HEAD_INIT(name)
+
+#define POISON_POINTER_DELTA 0
+#define LIST_POISON1  ((void *) 0x100 + POISON_POINTER_DELTA)
+#define LIST_POISON2  ((void *) 0x200 + POISON_POINTER_DELTA)
+
+
+static inline void INIT_LIST_HEAD(struct list_head *list)
+{
+        list->next = list;
+        list->prev = list;
+}
+
+static inline void __list_add(struct list_head *new,
+                              struct list_head *prev,
+                              struct list_head *next)
+{
+        next->prev = new;
+        new->next = next;
+        new->prev = prev;
+        prev->next = new;
+}
+
+/**
+ * list_add - add a new entry
+ * @new: new entry to be added
+ * @head: list head to add it after
+ *
+ * Insert a new entry after the specified head.
+ * This is good for implementing stacks.
+ */
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+        __list_add(new, head, head->next);
+}
+
+/*
+ * Delete a list entry by making the prev/next entries
+ * point to each other.
+ *
+ * This is only for internal list manipulation where we know
+ * the prev/next entries already!
+ */
+static inline void __list_del(struct list_head * prev, struct list_head * next)
+{
+        next->prev = prev;
+        prev->next = next;
+}
+
+/**
+ * list_del - deletes entry from list.
+ * @entry: the element to delete from the list.
+ * Note: list_empty() on entry does not return true after this, the entry is
+ * in an undefined state.
+ */
+static inline void __list_del_entry(struct list_head *entry)
+{
+        __list_del(entry->prev, entry->next);
+}
+
+static inline void list_del(struct list_head *entry)
+{
+        __list_del(entry->prev, entry->next);
+        entry->next = LIST_POISON1;
+        entry->prev = LIST_POISON2;
+}
+
+#define list_entry(ptr, type, member) \
+        container_of(ptr, type, member)
+#define list_first_entry(ptr, type, member) \
+        list_entry((ptr)->next, type, member)
+#define list_next_entry(pos, member) \
+        list_entry((pos)->member.next, typeof(*(pos)), member)
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/overflow.h b/src/contrib/libbpf/include/linux/overflow.h
new file mode 100644
index 0000000..53d7580
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/overflow.h
@@ -0,0 +1,90 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_OVERFLOW_H
+#define __LINUX_OVERFLOW_H
+
+#define is_signed_type(type)	(((type)(-1)) < (type)1)
+#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
+#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
+#define type_min(T) ((T)((T)-type_max(T)-(T)1))
+
+#ifndef unlikely
+#define unlikely(x)	__builtin_expect(!!(x), 0)
+#endif
+
+#ifdef __GNUC__
+#define GCC_VERSION (__GNUC__ * 10000           \
+                     + __GNUC_MINOR__ * 100     \
+                     + __GNUC_PATCHLEVEL__)
+#if GCC_VERSION >= 50100
+#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
+#endif
+#endif
+
+#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW
+
+#define check_mul_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);			\
+	typeof(b) __b = (b);			\
+	typeof(d) __d = (d);			\
+	(void) (&__a == &__b);			\
+	(void) (&__a == __d);			\
+	__builtin_mul_overflow(__a, __b, __d);	\
+})
+
+#else
+
+/*
+ * If one of a or b is a compile-time constant, this avoids a division.
+ */
+#define __unsigned_mul_overflow(a, b, d) ({		\
+	typeof(a) __a = (a);				\
+	typeof(b) __b = (b);				\
+	typeof(d) __d = (d);				\
+	(void) (&__a == &__b);				\
+	(void) (&__a == __d);				\
+	*__d = __a * __b;				\
+	__builtin_constant_p(__b) ?			\
+	  __b > 0 && __a > type_max(typeof(__a)) / __b : \
+	  __a > 0 && __b > type_max(typeof(__b)) / __a;	 \
+})
+
+/*
+ * Signed multiplication is rather hard. gcc always follows C99, so
+ * division is truncated towards 0. This means that we can write the
+ * overflow check like this:
+ *
+ * (a > 0 && (b > MAX/a || b < MIN/a)) ||
+ * (a < -1 && (b > MIN/a || b < MAX/a) ||
+ * (a == -1 && b == MIN)
+ *
+ * The redundant casts of -1 are to silence an annoying -Wtype-limits
+ * (included in -Wextra) warning: When the type is u8 or u16, the
+ * __b_c_e in check_mul_overflow obviously selects
+ * __unsigned_mul_overflow, but unfortunately gcc still parses this
+ * code and warns about the limited range of __b.
+ */
+
+#define __signed_mul_overflow(a, b, d) ({				\
+	typeof(a) __a = (a);						\
+	typeof(b) __b = (b);						\
+	typeof(d) __d = (d);						\
+	typeof(a) __tmax = type_max(typeof(a));				\
+	typeof(a) __tmin = type_min(typeof(a));				\
+	(void) (&__a == &__b);						\
+	(void) (&__a == __d);						\
+	*__d = (__u64)__a * (__u64)__b;					\
+	(__b > 0   && (__a > __tmax/__b || __a < __tmin/__b)) ||	\
+	(__b < (typeof(__b))-1  && (__a > __tmin/__b || __a < __tmax/__b)) || \
+	(__b == (typeof(__b))-1 && __a == __tmin);			\
+})
+
+#define check_mul_overflow(a, b, d)					\
+	__builtin_choose_expr(is_signed_type(typeof(a)),		\
+			__signed_mul_overflow(a, b, d),			\
+			__unsigned_mul_overflow(a, b, d))
+
+
+#endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */
+
+#endif
diff --git a/src/contrib/libbpf/include/linux/ring_buffer.h b/src/contrib/libbpf/include/linux/ring_buffer.h
new file mode 100644
index 0000000..fc4677b
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/ring_buffer.h
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+#ifndef _TOOLS_LINUX_RING_BUFFER_H_
+#define _TOOLS_LINUX_RING_BUFFER_H_
+
+#include <linux/compiler.h>
+
+static inline __u64 ring_buffer_read_head(struct perf_event_mmap_page *base)
+{
+	return smp_load_acquire(&base->data_head);
+}
+
+static inline void ring_buffer_write_tail(struct perf_event_mmap_page *base,
+					  __u64 tail)
+{
+	smp_store_release(&base->data_tail, tail);
+}
+
+#endif /* _TOOLS_LINUX_RING_BUFFER_H_ */
diff --git a/src/contrib/libbpf/include/linux/types.h b/src/contrib/libbpf/include/linux/types.h
new file mode 100644
index 0000000..bae1ed8
--- /dev/null
+++ b/src/contrib/libbpf/include/linux/types.h
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
+
+#ifndef __LINUX_TYPES_H
+#define __LINUX_TYPES_H
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include <asm/types.h>
+#include <asm/posix_types.h>
+
+#define __bitwise__
+#define __bitwise __bitwise__
+
+typedef __u16 __bitwise __le16;
+typedef __u16 __bitwise __be16;
+typedef __u32 __bitwise __le32;
+typedef __u32 __bitwise __be32;
+typedef __u64 __bitwise __le64;
+typedef __u64 __bitwise __be64;
+
+#ifndef __aligned_u64
+# define __aligned_u64 __u64 __attribute__((aligned(8)))
+#endif
+
+struct list_head {
+	struct list_head *next, *prev;
+};
+
+#endif
diff --git a/src/contrib/libbpf/include/uapi/linux/bpf.h b/src/contrib/libbpf/include/uapi/linux/bpf.h
new file mode 100644
index 0000000..dbbcf0b
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/bpf.h
@@ -0,0 +1,3692 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ */
+#ifndef _UAPI__LINUX_BPF_H__
+#define _UAPI__LINUX_BPF_H__
+
+#include <linux/types.h>
+#include <linux/bpf_common.h>
+
+/* Extended instruction set based on top of classic BPF */
+
+/* instruction classes */
+#define BPF_JMP32	0x06	/* jmp mode in word width */
+#define BPF_ALU64	0x07	/* alu mode in double word width */
+
+/* ld/ldx fields */
+#define BPF_DW		0x18	/* double word (64-bit) */
+#define BPF_XADD	0xc0	/* exclusive add */
+
+/* alu/jmp fields */
+#define BPF_MOV		0xb0	/* mov reg to reg */
+#define BPF_ARSH	0xc0	/* sign extending arithmetic shift right */
+
+/* change endianness of a register */
+#define BPF_END		0xd0	/* flags for endianness conversion: */
+#define BPF_TO_LE	0x00	/* convert to little-endian */
+#define BPF_TO_BE	0x08	/* convert to big-endian */
+#define BPF_FROM_LE	BPF_TO_LE
+#define BPF_FROM_BE	BPF_TO_BE
+
+/* jmp encodings */
+#define BPF_JNE		0x50	/* jump != */
+#define BPF_JLT		0xa0	/* LT is unsigned, '<' */
+#define BPF_JLE		0xb0	/* LE is unsigned, '<=' */
+#define BPF_JSGT	0x60	/* SGT is signed '>', GT in x86 */
+#define BPF_JSGE	0x70	/* SGE is signed '>=', GE in x86 */
+#define BPF_JSLT	0xc0	/* SLT is signed, '<' */
+#define BPF_JSLE	0xd0	/* SLE is signed, '<=' */
+#define BPF_CALL	0x80	/* function call */
+#define BPF_EXIT	0x90	/* function return */
+
+/* Register numbers */
+enum {
+	BPF_REG_0 = 0,
+	BPF_REG_1,
+	BPF_REG_2,
+	BPF_REG_3,
+	BPF_REG_4,
+	BPF_REG_5,
+	BPF_REG_6,
+	BPF_REG_7,
+	BPF_REG_8,
+	BPF_REG_9,
+	BPF_REG_10,
+	__MAX_BPF_REG,
+};
+
+/* BPF has 10 general purpose 64-bit registers and stack frame. */
+#define MAX_BPF_REG	__MAX_BPF_REG
+
+struct bpf_insn {
+	__u8	code;		/* opcode */
+	__u8	dst_reg:4;	/* dest register */
+	__u8	src_reg:4;	/* source register */
+	__s16	off;		/* signed offset */
+	__s32	imm;		/* signed immediate constant */
+};
+
+/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */
+struct bpf_lpm_trie_key {
+	__u32	prefixlen;	/* up to 32 for AF_INET, 128 for AF_INET6 */
+	__u8	data[0];	/* Arbitrary size */
+};
+
+struct bpf_cgroup_storage_key {
+	__u64	cgroup_inode_id;	/* cgroup inode id */
+	__u32	attach_type;		/* program attach type */
+};
+
+/* BPF syscall commands, see bpf(2) man-page for details. */
+enum bpf_cmd {
+	BPF_MAP_CREATE,
+	BPF_MAP_LOOKUP_ELEM,
+	BPF_MAP_UPDATE_ELEM,
+	BPF_MAP_DELETE_ELEM,
+	BPF_MAP_GET_NEXT_KEY,
+	BPF_PROG_LOAD,
+	BPF_OBJ_PIN,
+	BPF_OBJ_GET,
+	BPF_PROG_ATTACH,
+	BPF_PROG_DETACH,
+	BPF_PROG_TEST_RUN,
+	BPF_PROG_GET_NEXT_ID,
+	BPF_MAP_GET_NEXT_ID,
+	BPF_PROG_GET_FD_BY_ID,
+	BPF_MAP_GET_FD_BY_ID,
+	BPF_OBJ_GET_INFO_BY_FD,
+	BPF_PROG_QUERY,
+	BPF_RAW_TRACEPOINT_OPEN,
+	BPF_BTF_LOAD,
+	BPF_BTF_GET_FD_BY_ID,
+	BPF_TASK_FD_QUERY,
+	BPF_MAP_LOOKUP_AND_DELETE_ELEM,
+	BPF_MAP_FREEZE,
+	BPF_BTF_GET_NEXT_ID,
+};
+
+enum bpf_map_type {
+	BPF_MAP_TYPE_UNSPEC,
+	BPF_MAP_TYPE_HASH,
+	BPF_MAP_TYPE_ARRAY,
+	BPF_MAP_TYPE_PROG_ARRAY,
+	BPF_MAP_TYPE_PERF_EVENT_ARRAY,
+	BPF_MAP_TYPE_PERCPU_HASH,
+	BPF_MAP_TYPE_PERCPU_ARRAY,
+	BPF_MAP_TYPE_STACK_TRACE,
+	BPF_MAP_TYPE_CGROUP_ARRAY,
+	BPF_MAP_TYPE_LRU_HASH,
+	BPF_MAP_TYPE_LRU_PERCPU_HASH,
+	BPF_MAP_TYPE_LPM_TRIE,
+	BPF_MAP_TYPE_ARRAY_OF_MAPS,
+	BPF_MAP_TYPE_HASH_OF_MAPS,
+	BPF_MAP_TYPE_DEVMAP,
+	BPF_MAP_TYPE_SOCKMAP,
+	BPF_MAP_TYPE_CPUMAP,
+	BPF_MAP_TYPE_XSKMAP,
+	BPF_MAP_TYPE_SOCKHASH,
+	BPF_MAP_TYPE_CGROUP_STORAGE,
+	BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
+	BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
+	BPF_MAP_TYPE_QUEUE,
+	BPF_MAP_TYPE_STACK,
+	BPF_MAP_TYPE_SK_STORAGE,
+	BPF_MAP_TYPE_DEVMAP_HASH,
+};
+
+/* Note that tracing related programs such as
+ * BPF_PROG_TYPE_{KPROBE,TRACEPOINT,PERF_EVENT,RAW_TRACEPOINT}
+ * are not subject to a stable API since kernel internal data
+ * structures can change from release to release and may
+ * therefore break existing tracing BPF programs. Tracing BPF
+ * programs correspond to /a/ specific kernel which is to be
+ * analyzed, and not /a/ specific kernel /and/ all future ones.
+ */
+enum bpf_prog_type {
+	BPF_PROG_TYPE_UNSPEC,
+	BPF_PROG_TYPE_SOCKET_FILTER,
+	BPF_PROG_TYPE_KPROBE,
+	BPF_PROG_TYPE_SCHED_CLS,
+	BPF_PROG_TYPE_SCHED_ACT,
+	BPF_PROG_TYPE_TRACEPOINT,
+	BPF_PROG_TYPE_XDP,
+	BPF_PROG_TYPE_PERF_EVENT,
+	BPF_PROG_TYPE_CGROUP_SKB,
+	BPF_PROG_TYPE_CGROUP_SOCK,
+	BPF_PROG_TYPE_LWT_IN,
+	BPF_PROG_TYPE_LWT_OUT,
+	BPF_PROG_TYPE_LWT_XMIT,
+	BPF_PROG_TYPE_SOCK_OPS,
+	BPF_PROG_TYPE_SK_SKB,
+	BPF_PROG_TYPE_CGROUP_DEVICE,
+	BPF_PROG_TYPE_SK_MSG,
+	BPF_PROG_TYPE_RAW_TRACEPOINT,
+	BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
+	BPF_PROG_TYPE_LWT_SEG6LOCAL,
+	BPF_PROG_TYPE_LIRC_MODE2,
+	BPF_PROG_TYPE_SK_REUSEPORT,
+	BPF_PROG_TYPE_FLOW_DISSECTOR,
+	BPF_PROG_TYPE_CGROUP_SYSCTL,
+	BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
+	BPF_PROG_TYPE_CGROUP_SOCKOPT,
+	BPF_PROG_TYPE_TRACING,
+};
+
+enum bpf_attach_type {
+	BPF_CGROUP_INET_INGRESS,
+	BPF_CGROUP_INET_EGRESS,
+	BPF_CGROUP_INET_SOCK_CREATE,
+	BPF_CGROUP_SOCK_OPS,
+	BPF_SK_SKB_STREAM_PARSER,
+	BPF_SK_SKB_STREAM_VERDICT,
+	BPF_CGROUP_DEVICE,
+	BPF_SK_MSG_VERDICT,
+	BPF_CGROUP_INET4_BIND,
+	BPF_CGROUP_INET6_BIND,
+	BPF_CGROUP_INET4_CONNECT,
+	BPF_CGROUP_INET6_CONNECT,
+	BPF_CGROUP_INET4_POST_BIND,
+	BPF_CGROUP_INET6_POST_BIND,
+	BPF_CGROUP_UDP4_SENDMSG,
+	BPF_CGROUP_UDP6_SENDMSG,
+	BPF_LIRC_MODE2,
+	BPF_FLOW_DISSECTOR,
+	BPF_CGROUP_SYSCTL,
+	BPF_CGROUP_UDP4_RECVMSG,
+	BPF_CGROUP_UDP6_RECVMSG,
+	BPF_CGROUP_GETSOCKOPT,
+	BPF_CGROUP_SETSOCKOPT,
+	BPF_TRACE_RAW_TP,
+	BPF_TRACE_FENTRY,
+	BPF_TRACE_FEXIT,
+	__MAX_BPF_ATTACH_TYPE
+};
+
+#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
+
+/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
+ *
+ * NONE(default): No further bpf programs allowed in the subtree.
+ *
+ * BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
+ * the program in this cgroup yields to sub-cgroup program.
+ *
+ * BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
+ * that cgroup program gets run in addition to the program in this cgroup.
+ *
+ * Only one program is allowed to be attached to a cgroup with
+ * NONE or BPF_F_ALLOW_OVERRIDE flag.
+ * Attaching another program on top of NONE or BPF_F_ALLOW_OVERRIDE will
+ * release old program and attach the new one. Attach flags has to match.
+ *
+ * Multiple programs are allowed to be attached to a cgroup with
+ * BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
+ * (those that were attached first, run first)
+ * The programs of sub-cgroup are executed first, then programs of
+ * this cgroup and then programs of parent cgroup.
+ * When children program makes decision (like picking TCP CA or sock bind)
+ * parent program has a chance to override it.
+ *
+ * A cgroup with MULTI or OVERRIDE flag allows any attach flags in sub-cgroups.
+ * A cgroup with NONE doesn't allow any programs in sub-cgroups.
+ * Ex1:
+ * cgrp1 (MULTI progs A, B) ->
+ *    cgrp2 (OVERRIDE prog C) ->
+ *      cgrp3 (MULTI prog D) ->
+ *        cgrp4 (OVERRIDE prog E) ->
+ *          cgrp5 (NONE prog F)
+ * the event in cgrp5 triggers execution of F,D,A,B in that order.
+ * if prog F is detached, the execution is E,D,A,B
+ * if prog F and D are detached, the execution is E,A,B
+ * if prog F, E and D are detached, the execution is C,A,B
+ *
+ * All eligible programs are executed regardless of return code from
+ * earlier programs.
+ */
+#define BPF_F_ALLOW_OVERRIDE	(1U << 0)
+#define BPF_F_ALLOW_MULTI	(1U << 1)
+
+/* If BPF_F_STRICT_ALIGNMENT is used in BPF_PROG_LOAD command, the
+ * verifier will perform strict alignment checking as if the kernel
+ * has been built with CONFIG_EFFICIENT_UNALIGNED_ACCESS not set,
+ * and NET_IP_ALIGN defined to 2.
+ */
+#define BPF_F_STRICT_ALIGNMENT	(1U << 0)
+
+/* If BPF_F_ANY_ALIGNMENT is used in BPF_PROF_LOAD command, the
+ * verifier will allow any alignment whatsoever.  On platforms
+ * with strict alignment requirements for loads ands stores (such
+ * as sparc and mips) the verifier validates that all loads and
+ * stores provably follow this requirement.  This flag turns that
+ * checking and enforcement off.
+ *
+ * It is mostly used for testing when we want to validate the
+ * context and memory access aspects of the verifier, but because
+ * of an unaligned access the alignment check would trigger before
+ * the one we are interested in.
+ */
+#define BPF_F_ANY_ALIGNMENT	(1U << 1)
+
+/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose.
+ * Verifier does sub-register def/use analysis and identifies instructions whose
+ * def only matters for low 32-bit, high 32-bit is never referenced later
+ * through implicit zero extension. Therefore verifier notifies JIT back-ends
+ * that it is safe to ignore clearing high 32-bit for these instructions. This
+ * saves some back-ends a lot of code-gen. However such optimization is not
+ * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends
+ * hence hasn't used verifier's analysis result. But, we really want to have a
+ * way to be able to verify the correctness of the described optimization on
+ * x86_64 on which testsuites are frequently exercised.
+ *
+ * So, this flag is introduced. Once it is set, verifier will randomize high
+ * 32-bit for those instructions who has been identified as safe to ignore them.
+ * Then, if verifier is not doing correct analysis, such randomization will
+ * regress tests to expose bugs.
+ */
+#define BPF_F_TEST_RND_HI32	(1U << 2)
+
+/* The verifier internal test flag. Behavior is undefined */
+#define BPF_F_TEST_STATE_FREQ	(1U << 3)
+
+/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
+ * two extensions:
+ *
+ * insn[0].src_reg:  BPF_PSEUDO_MAP_FD   BPF_PSEUDO_MAP_VALUE
+ * insn[0].imm:      map fd              map fd
+ * insn[1].imm:      0                   offset into value
+ * insn[0].off:      0                   0
+ * insn[1].off:      0                   0
+ * ldimm64 rewrite:  address of map      address of map[0]+offset
+ * verifier type:    CONST_PTR_TO_MAP    PTR_TO_MAP_VALUE
+ */
+#define BPF_PSEUDO_MAP_FD	1
+#define BPF_PSEUDO_MAP_VALUE	2
+
+/* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
+ * offset to another bpf function
+ */
+#define BPF_PSEUDO_CALL		1
+
+/* flags for BPF_MAP_UPDATE_ELEM command */
+#define BPF_ANY		0 /* create new element or update existing */
+#define BPF_NOEXIST	1 /* create new element if it didn't exist */
+#define BPF_EXIST	2 /* update existing element */
+#define BPF_F_LOCK	4 /* spin_lock-ed map_lookup/map_update */
+
+/* flags for BPF_MAP_CREATE command */
+#define BPF_F_NO_PREALLOC	(1U << 0)
+/* Instead of having one common LRU list in the
+ * BPF_MAP_TYPE_LRU_[PERCPU_]HASH map, use a percpu LRU list
+ * which can scale and perform better.
+ * Note, the LRU nodes (including free nodes) cannot be moved
+ * across different LRU lists.
+ */
+#define BPF_F_NO_COMMON_LRU	(1U << 1)
+/* Specify numa node during map creation */
+#define BPF_F_NUMA_NODE		(1U << 2)
+
+#define BPF_OBJ_NAME_LEN 16U
+
+/* Flags for accessing BPF object from syscall side. */
+#define BPF_F_RDONLY		(1U << 3)
+#define BPF_F_WRONLY		(1U << 4)
+
+/* Flag for stack_map, store build_id+offset instead of pointer */
+#define BPF_F_STACK_BUILD_ID	(1U << 5)
+
+/* Zero-initialize hash function seed. This should only be used for testing. */
+#define BPF_F_ZERO_SEED		(1U << 6)
+
+/* Flags for accessing BPF object from program side. */
+#define BPF_F_RDONLY_PROG	(1U << 7)
+#define BPF_F_WRONLY_PROG	(1U << 8)
+
+/* Clone map from listener for newly accepted socket */
+#define BPF_F_CLONE		(1U << 9)
+
+/* Enable memory-mapping BPF map */
+#define BPF_F_MMAPABLE		(1U << 10)
+
+/* flags for BPF_PROG_QUERY */
+#define BPF_F_QUERY_EFFECTIVE	(1U << 0)
+
+enum bpf_stack_build_id_status {
+	/* user space need an empty entry to identify end of a trace */
+	BPF_STACK_BUILD_ID_EMPTY = 0,
+	/* with valid build_id and offset */
+	BPF_STACK_BUILD_ID_VALID = 1,
+	/* couldn't get build_id, fallback to ip */
+	BPF_STACK_BUILD_ID_IP = 2,
+};
+
+#define BPF_BUILD_ID_SIZE 20
+struct bpf_stack_build_id {
+	__s32		status;
+	unsigned char	build_id[BPF_BUILD_ID_SIZE];
+	union {
+		__u64	offset;
+		__u64	ip;
+	};
+};
+
+union bpf_attr {
+	struct { /* anonymous struct used by BPF_MAP_CREATE command */
+		__u32	map_type;	/* one of enum bpf_map_type */
+		__u32	key_size;	/* size of key in bytes */
+		__u32	value_size;	/* size of value in bytes */
+		__u32	max_entries;	/* max number of entries in a map */
+		__u32	map_flags;	/* BPF_MAP_CREATE related
+					 * flags defined above.
+					 */
+		__u32	inner_map_fd;	/* fd pointing to the inner map */
+		__u32	numa_node;	/* numa node (effective only if
+					 * BPF_F_NUMA_NODE is set).
+					 */
+		char	map_name[BPF_OBJ_NAME_LEN];
+		__u32	map_ifindex;	/* ifindex of netdev to create on */
+		__u32	btf_fd;		/* fd pointing to a BTF type data */
+		__u32	btf_key_type_id;	/* BTF type_id of the key */
+		__u32	btf_value_type_id;	/* BTF type_id of the value */
+	};
+
+	struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
+		__u32		map_fd;
+		__aligned_u64	key;
+		union {
+			__aligned_u64 value;
+			__aligned_u64 next_key;
+		};
+		__u64		flags;
+	};
+
+	struct { /* anonymous struct used by BPF_PROG_LOAD command */
+		__u32		prog_type;	/* one of enum bpf_prog_type */
+		__u32		insn_cnt;
+		__aligned_u64	insns;
+		__aligned_u64	license;
+		__u32		log_level;	/* verbosity level of verifier */
+		__u32		log_size;	/* size of user buffer */
+		__aligned_u64	log_buf;	/* user supplied buffer */
+		__u32		kern_version;	/* not used */
+		__u32		prog_flags;
+		char		prog_name[BPF_OBJ_NAME_LEN];
+		__u32		prog_ifindex;	/* ifindex of netdev to prep for */
+		/* For some prog types expected attach type must be known at
+		 * load time to verify attach type specific parts of prog
+		 * (context accesses, allowed helpers, etc).
+		 */
+		__u32		expected_attach_type;
+		__u32		prog_btf_fd;	/* fd pointing to BTF type data */
+		__u32		func_info_rec_size;	/* userspace bpf_func_info size */
+		__aligned_u64	func_info;	/* func info */
+		__u32		func_info_cnt;	/* number of bpf_func_info records */
+		__u32		line_info_rec_size;	/* userspace bpf_line_info size */
+		__aligned_u64	line_info;	/* line info */
+		__u32		line_info_cnt;	/* number of bpf_line_info records */
+		__u32		attach_btf_id;	/* in-kernel BTF type id to attach to */
+		__u32		attach_prog_fd; /* 0 to attach to vmlinux */
+	};
+
+	struct { /* anonymous struct used by BPF_OBJ_* commands */
+		__aligned_u64	pathname;
+		__u32		bpf_fd;
+		__u32		file_flags;
+	};
+
+	struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
+		__u32		target_fd;	/* container object to attach to */
+		__u32		attach_bpf_fd;	/* eBPF program to attach */
+		__u32		attach_type;
+		__u32		attach_flags;
+	};
+
+	struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */
+		__u32		prog_fd;
+		__u32		retval;
+		__u32		data_size_in;	/* input: len of data_in */
+		__u32		data_size_out;	/* input/output: len of data_out
+						 *   returns ENOSPC if data_out
+						 *   is too small.
+						 */
+		__aligned_u64	data_in;
+		__aligned_u64	data_out;
+		__u32		repeat;
+		__u32		duration;
+		__u32		ctx_size_in;	/* input: len of ctx_in */
+		__u32		ctx_size_out;	/* input/output: len of ctx_out
+						 *   returns ENOSPC if ctx_out
+						 *   is too small.
+						 */
+		__aligned_u64	ctx_in;
+		__aligned_u64	ctx_out;
+	} test;
+
+	struct { /* anonymous struct used by BPF_*_GET_*_ID */
+		union {
+			__u32		start_id;
+			__u32		prog_id;
+			__u32		map_id;
+			__u32		btf_id;
+		};
+		__u32		next_id;
+		__u32		open_flags;
+	};
+
+	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
+		__u32		bpf_fd;
+		__u32		info_len;
+		__aligned_u64	info;
+	} info;
+
+	struct { /* anonymous struct used by BPF_PROG_QUERY command */
+		__u32		target_fd;	/* container object to query */
+		__u32		attach_type;
+		__u32		query_flags;
+		__u32		attach_flags;
+		__aligned_u64	prog_ids;
+		__u32		prog_cnt;
+	} query;
+
+	struct {
+		__u64 name;
+		__u32 prog_fd;
+	} raw_tracepoint;
+
+	struct { /* anonymous struct for BPF_BTF_LOAD */
+		__aligned_u64	btf;
+		__aligned_u64	btf_log_buf;
+		__u32		btf_size;
+		__u32		btf_log_size;
+		__u32		btf_log_level;
+	};
+
+	struct {
+		__u32		pid;		/* input: pid */
+		__u32		fd;		/* input: fd */
+		__u32		flags;		/* input: flags */
+		__u32		buf_len;	/* input/output: buf len */
+		__aligned_u64	buf;		/* input/output:
+						 *   tp_name for tracepoint
+						 *   symbol for kprobe
+						 *   filename for uprobe
+						 */
+		__u32		prog_id;	/* output: prod_id */
+		__u32		fd_type;	/* output: BPF_FD_TYPE_* */
+		__u64		probe_offset;	/* output: probe_offset */
+		__u64		probe_addr;	/* output: probe_addr */
+	} task_fd_query;
+} __attribute__((aligned(8)));
+
+/* The description below is an attempt at providing documentation to eBPF
+ * developers about the multiple available eBPF helper functions. It can be
+ * parsed and used to produce a manual page. The workflow is the following,
+ * and requires the rst2man utility:
+ *
+ *     $ ./scripts/bpf_helpers_doc.py \
+ *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
+ *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
+ *     $ man /tmp/bpf-helpers.7
+ *
+ * Note that in order to produce this external documentation, some RST
+ * formatting is used in the descriptions to get "bold" and "italics" in
+ * manual pages. Also note that the few trailing white spaces are
+ * intentional, removing them would break paragraphs for rst2man.
+ *
+ * Start of BPF helper function descriptions:
+ *
+ * void *bpf_map_lookup_elem(struct bpf_map *map, const void *key)
+ * 	Description
+ * 		Perform a lookup in *map* for an entry associated to *key*.
+ * 	Return
+ * 		Map value associated to *key*, or **NULL** if no entry was
+ * 		found.
+ *
+ * int bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags)
+ * 	Description
+ * 		Add or update the value of the entry associated to *key* in
+ * 		*map* with *value*. *flags* is one of:
+ *
+ * 		**BPF_NOEXIST**
+ * 			The entry for *key* must not exist in the map.
+ * 		**BPF_EXIST**
+ * 			The entry for *key* must already exist in the map.
+ * 		**BPF_ANY**
+ * 			No condition on the existence of the entry for *key*.
+ *
+ * 		Flag value **BPF_NOEXIST** cannot be used for maps of types
+ * 		**BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
+ * 		elements always exist), the helper would return an error.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_map_delete_elem(struct bpf_map *map, const void *key)
+ * 	Description
+ * 		Delete entry with *key* from *map*.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_probe_read(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		For tracing programs, safely attempt to read *size* bytes from
+ * 		kernel space address *unsafe_ptr* and store the data in *dst*.
+ *
+ * 		Generally, use bpf_probe_read_user() or bpf_probe_read_kernel()
+ * 		instead.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * u64 bpf_ktime_get_ns(void)
+ * 	Description
+ * 		Return the time elapsed since system boot, in nanoseconds.
+ * 	Return
+ * 		Current *ktime*.
+ *
+ * int bpf_trace_printk(const char *fmt, u32 fmt_size, ...)
+ * 	Description
+ * 		This helper is a "printk()-like" facility for debugging. It
+ * 		prints a message defined by format *fmt* (of size *fmt_size*)
+ * 		to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
+ * 		available. It can take up to three additional **u64**
+ * 		arguments (as an eBPF helpers, the total number of arguments is
+ * 		limited to five).
+ *
+ * 		Each time the helper is called, it appends a line to the trace.
+ * 		Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
+ * 		open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
+ * 		The format of the trace is customizable, and the exact output
+ * 		one will get depends on the options set in
+ * 		*\/sys/kernel/debug/tracing/trace_options* (see also the
+ * 		*README* file under the same directory). However, it usually
+ * 		defaults to something like:
+ *
+ * 		::
+ *
+ * 			telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
+ *
+ * 		In the above:
+ *
+ * 			* ``telnet`` is the name of the current task.
+ * 			* ``470`` is the PID of the current task.
+ * 			* ``001`` is the CPU number on which the task is
+ * 			  running.
+ * 			* In ``.N..``, each character refers to a set of
+ * 			  options (whether irqs are enabled, scheduling
+ * 			  options, whether hard/softirqs are running, level of
+ * 			  preempt_disabled respectively). **N** means that
+ * 			  **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
+ * 			  are set.
+ * 			* ``419421.045894`` is a timestamp.
+ * 			* ``0x00000001`` is a fake value used by BPF for the
+ * 			  instruction pointer register.
+ * 			* ``<formatted msg>`` is the message formatted with
+ * 			  *fmt*.
+ *
+ * 		The conversion specifiers supported by *fmt* are similar, but
+ * 		more limited than for printk(). They are **%d**, **%i**,
+ * 		**%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
+ * 		**%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
+ * 		of field, padding with zeroes, etc.) is available, and the
+ * 		helper will return **-EINVAL** (but print nothing) if it
+ * 		encounters an unknown specifier.
+ *
+ * 		Also, note that **bpf_trace_printk**\ () is slow, and should
+ * 		only be used for debugging purposes. For this reason, a notice
+ * 		bloc (spanning several lines) is printed to kernel logs and
+ * 		states that the helper should not be used "for production use"
+ * 		the first time this helper is used (or more precisely, when
+ * 		**trace_printk**\ () buffers are allocated). For passing values
+ * 		to user space, perf events should be preferred.
+ * 	Return
+ * 		The number of bytes written to the buffer, or a negative error
+ * 		in case of failure.
+ *
+ * u32 bpf_get_prandom_u32(void)
+ * 	Description
+ * 		Get a pseudo-random number.
+ *
+ * 		From a security point of view, this helper uses its own
+ * 		pseudo-random internal state, and cannot be used to infer the
+ * 		seed of other random functions in the kernel. However, it is
+ * 		essential to note that the generator used by the helper is not
+ * 		cryptographically secure.
+ * 	Return
+ * 		A random 32-bit unsigned value.
+ *
+ * u32 bpf_get_smp_processor_id(void)
+ * 	Description
+ * 		Get the SMP (symmetric multiprocessing) processor id. Note that
+ * 		all programs run with preemption disabled, which means that the
+ * 		SMP processor id is stable during all the execution of the
+ * 		program.
+ * 	Return
+ * 		The SMP id of the processor running the program.
+ *
+ * int bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len, u64 flags)
+ * 	Description
+ * 		Store *len* bytes from address *from* into the packet
+ * 		associated to *skb*, at *offset*. *flags* are a combination of
+ * 		**BPF_F_RECOMPUTE_CSUM** (automatically recompute the
+ * 		checksum for the packet after storing the bytes) and
+ * 		**BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
+ * 		**->swhash** and *skb*\ **->l4hash** to 0).
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_l3_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 size)
+ * 	Description
+ * 		Recompute the layer 3 (e.g. IP) checksum for the packet
+ * 		associated to *skb*. Computation is incremental, so the helper
+ * 		must know the former value of the header field that was
+ * 		modified (*from*), the new value of this field (*to*), and the
+ * 		number of bytes (2 or 4) for this field, stored in *size*.
+ * 		Alternatively, it is possible to store the difference between
+ * 		the previous and the new values of the header field in *to*, by
+ * 		setting *from* and *size* to 0. For both methods, *offset*
+ * 		indicates the location of the IP checksum within the packet.
+ *
+ * 		This helper works in combination with **bpf_csum_diff**\ (),
+ * 		which does not update the checksum in-place, but offers more
+ * 		flexibility and can handle sizes larger than 2 or 4 for the
+ * 		checksum to update.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_l4_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 flags)
+ * 	Description
+ * 		Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
+ * 		packet associated to *skb*. Computation is incremental, so the
+ * 		helper must know the former value of the header field that was
+ * 		modified (*from*), the new value of this field (*to*), and the
+ * 		number of bytes (2 or 4) for this field, stored on the lowest
+ * 		four bits of *flags*. Alternatively, it is possible to store
+ * 		the difference between the previous and the new values of the
+ * 		header field in *to*, by setting *from* and the four lowest
+ * 		bits of *flags* to 0. For both methods, *offset* indicates the
+ * 		location of the IP checksum within the packet. In addition to
+ * 		the size of the field, *flags* can be added (bitwise OR) actual
+ * 		flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
+ * 		untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
+ * 		for updates resulting in a null checksum the value is set to
+ * 		**CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
+ * 		the checksum is to be computed against a pseudo-header.
+ *
+ * 		This helper works in combination with **bpf_csum_diff**\ (),
+ * 		which does not update the checksum in-place, but offers more
+ * 		flexibility and can handle sizes larger than 2 or 4 for the
+ * 		checksum to update.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_tail_call(void *ctx, struct bpf_map *prog_array_map, u32 index)
+ * 	Description
+ * 		This special helper is used to trigger a "tail call", or in
+ * 		other words, to jump into another eBPF program. The same stack
+ * 		frame is used (but values on stack and in registers for the
+ * 		caller are not accessible to the callee). This mechanism allows
+ * 		for program chaining, either for raising the maximum number of
+ * 		available eBPF instructions, or to execute given programs in
+ * 		conditional blocks. For security reasons, there is an upper
+ * 		limit to the number of successive tail calls that can be
+ * 		performed.
+ *
+ * 		Upon call of this helper, the program attempts to jump into a
+ * 		program referenced at index *index* in *prog_array_map*, a
+ * 		special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
+ * 		*ctx*, a pointer to the context.
+ *
+ * 		If the call succeeds, the kernel immediately runs the first
+ * 		instruction of the new program. This is not a function call,
+ * 		and it never returns to the previous program. If the call
+ * 		fails, then the helper has no effect, and the caller continues
+ * 		to run its subsequent instructions. A call can fail if the
+ * 		destination program for the jump does not exist (i.e. *index*
+ * 		is superior to the number of entries in *prog_array_map*), or
+ * 		if the maximum number of tail calls has been reached for this
+ * 		chain of programs. This limit is defined in the kernel by the
+ * 		macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
+ * 		which is currently set to 32.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_clone_redirect(struct sk_buff *skb, u32 ifindex, u64 flags)
+ * 	Description
+ * 		Clone and redirect the packet associated to *skb* to another
+ * 		net device of index *ifindex*. Both ingress and egress
+ * 		interfaces can be used for redirection. The **BPF_F_INGRESS**
+ * 		value in *flags* is used to make the distinction (ingress path
+ * 		is selected if the flag is present, egress path otherwise).
+ * 		This is the only flag supported for now.
+ *
+ * 		In comparison with **bpf_redirect**\ () helper,
+ * 		**bpf_clone_redirect**\ () has the associated cost of
+ * 		duplicating the packet buffer, but this can be executed out of
+ * 		the eBPF program. Conversely, **bpf_redirect**\ () is more
+ * 		efficient, but it is handled through an action code where the
+ * 		redirection happens only after the eBPF program has returned.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * u64 bpf_get_current_pid_tgid(void)
+ * 	Return
+ * 		A 64-bit integer containing the current tgid and pid, and
+ * 		created as such:
+ * 		*current_task*\ **->tgid << 32 \|**
+ * 		*current_task*\ **->pid**.
+ *
+ * u64 bpf_get_current_uid_gid(void)
+ * 	Return
+ * 		A 64-bit integer containing the current GID and UID, and
+ * 		created as such: *current_gid* **<< 32 \|** *current_uid*.
+ *
+ * int bpf_get_current_comm(void *buf, u32 size_of_buf)
+ * 	Description
+ * 		Copy the **comm** attribute of the current task into *buf* of
+ * 		*size_of_buf*. The **comm** attribute contains the name of
+ * 		the executable (excluding the path) for the current task. The
+ * 		*size_of_buf* must be strictly positive. On success, the
+ * 		helper makes sure that the *buf* is NUL-terminated. On failure,
+ * 		it is filled with zeroes.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * u32 bpf_get_cgroup_classid(struct sk_buff *skb)
+ * 	Description
+ * 		Retrieve the classid for the current task, i.e. for the net_cls
+ * 		cgroup to which *skb* belongs.
+ *
+ * 		This helper can be used on TC egress path, but not on ingress.
+ *
+ * 		The net_cls cgroup provides an interface to tag network packets
+ * 		based on a user-provided identifier for all traffic coming from
+ * 		the tasks belonging to the related cgroup. See also the related
+ * 		kernel documentation, available from the Linux sources in file
+ * 		*Documentation/admin-guide/cgroup-v1/net_cls.rst*.
+ *
+ * 		The Linux kernel has two versions for cgroups: there are
+ * 		cgroups v1 and cgroups v2. Both are available to users, who can
+ * 		use a mixture of them, but note that the net_cls cgroup is for
+ * 		cgroup v1 only. This makes it incompatible with BPF programs
+ * 		run on cgroups, which is a cgroup-v2-only feature (a socket can
+ * 		only hold data for one version of cgroups at a time).
+ *
+ * 		This helper is only available is the kernel was compiled with
+ * 		the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
+ * 		"**y**" or to "**m**".
+ * 	Return
+ * 		The classid, or 0 for the default unconfigured classid.
+ *
+ * int bpf_skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
+ * 	Description
+ * 		Push a *vlan_tci* (VLAN tag control information) of protocol
+ * 		*vlan_proto* to the packet associated to *skb*, then update
+ * 		the checksum. Note that if *vlan_proto* is different from
+ * 		**ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
+ * 		be **ETH_P_8021Q**.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_vlan_pop(struct sk_buff *skb)
+ * 	Description
+ * 		Pop a VLAN header from the packet associated to *skb*.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_get_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
+ * 	Description
+ * 		Get tunnel metadata. This helper takes a pointer *key* to an
+ * 		empty **struct bpf_tunnel_key** of **size**, that will be
+ * 		filled with tunnel metadata for the packet associated to *skb*.
+ * 		The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
+ * 		indicates that the tunnel is based on IPv6 protocol instead of
+ * 		IPv4.
+ *
+ * 		The **struct bpf_tunnel_key** is an object that generalizes the
+ * 		principal parameters used by various tunneling protocols into a
+ * 		single struct. This way, it can be used to easily make a
+ * 		decision based on the contents of the encapsulation header,
+ * 		"summarized" in this struct. In particular, it holds the IP
+ * 		address of the remote end (IPv4 or IPv6, depending on the case)
+ * 		in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
+ * 		this struct exposes the *key*\ **->tunnel_id**, which is
+ * 		generally mapped to a VNI (Virtual Network Identifier), making
+ * 		it programmable together with the **bpf_skb_set_tunnel_key**\
+ * 		() helper.
+ *
+ * 		Let's imagine that the following code is part of a program
+ * 		attached to the TC ingress interface, on one end of a GRE
+ * 		tunnel, and is supposed to filter out all messages coming from
+ * 		remote ends with IPv4 address other than 10.0.0.1:
+ *
+ * 		::
+ *
+ * 			int ret;
+ * 			struct bpf_tunnel_key key = {};
+ * 			
+ * 			ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
+ * 			if (ret < 0)
+ * 				return TC_ACT_SHOT;	// drop packet
+ * 			
+ * 			if (key.remote_ipv4 != 0x0a000001)
+ * 				return TC_ACT_SHOT;	// drop packet
+ * 			
+ * 			return TC_ACT_OK;		// accept packet
+ *
+ * 		This interface can also be used with all encapsulation devices
+ * 		that can operate in "collect metadata" mode: instead of having
+ * 		one network device per specific configuration, the "collect
+ * 		metadata" mode only requires a single device where the
+ * 		configuration can be extracted from this helper.
+ *
+ * 		This can be used together with various tunnels such as VXLan,
+ * 		Geneve, GRE or IP in IP (IPIP).
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_set_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
+ * 	Description
+ * 		Populate tunnel metadata for packet associated to *skb.* The
+ * 		tunnel metadata is set to the contents of *key*, of *size*. The
+ * 		*flags* can be set to a combination of the following values:
+ *
+ * 		**BPF_F_TUNINFO_IPV6**
+ * 			Indicate that the tunnel is based on IPv6 protocol
+ * 			instead of IPv4.
+ * 		**BPF_F_ZERO_CSUM_TX**
+ * 			For IPv4 packets, add a flag to tunnel metadata
+ * 			indicating that checksum computation should be skipped
+ * 			and checksum set to zeroes.
+ * 		**BPF_F_DONT_FRAGMENT**
+ * 			Add a flag to tunnel metadata indicating that the
+ * 			packet should not be fragmented.
+ * 		**BPF_F_SEQ_NUMBER**
+ * 			Add a flag to tunnel metadata indicating that a
+ * 			sequence number should be added to tunnel header before
+ * 			sending the packet. This flag was added for GRE
+ * 			encapsulation, but might be used with other protocols
+ * 			as well in the future.
+ *
+ * 		Here is a typical usage on the transmit path:
+ *
+ * 		::
+ *
+ * 			struct bpf_tunnel_key key;
+ * 			     populate key ...
+ * 			bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
+ * 			bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
+ *
+ * 		See also the description of the **bpf_skb_get_tunnel_key**\ ()
+ * 		helper for additional information.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * u64 bpf_perf_event_read(struct bpf_map *map, u64 flags)
+ * 	Description
+ * 		Read the value of a perf event counter. This helper relies on a
+ * 		*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
+ * 		the perf event counter is selected when *map* is updated with
+ * 		perf event file descriptors. The *map* is an array whose size
+ * 		is the number of available CPUs, and each cell contains a value
+ * 		relative to one CPU. The value to retrieve is indicated by
+ * 		*flags*, that contains the index of the CPU to look up, masked
+ * 		with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 		**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 		current CPU should be retrieved.
+ *
+ * 		Note that before Linux 4.13, only hardware perf event can be
+ * 		retrieved.
+ *
+ * 		Also, be aware that the newer helper
+ * 		**bpf_perf_event_read_value**\ () is recommended over
+ * 		**bpf_perf_event_read**\ () in general. The latter has some ABI
+ * 		quirks where error and counter value are used as a return code
+ * 		(which is wrong to do since ranges may overlap). This issue is
+ * 		fixed with **bpf_perf_event_read_value**\ (), which at the same
+ * 		time provides more features over the **bpf_perf_event_read**\
+ * 		() interface. Please refer to the description of
+ * 		**bpf_perf_event_read_value**\ () for details.
+ * 	Return
+ * 		The value of the perf event counter read from the map, or a
+ * 		negative error code in case of failure.
+ *
+ * int bpf_redirect(u32 ifindex, u64 flags)
+ * 	Description
+ * 		Redirect the packet to another net device of index *ifindex*.
+ * 		This helper is somewhat similar to **bpf_clone_redirect**\
+ * 		(), except that the packet is not cloned, which provides
+ * 		increased performance.
+ *
+ * 		Except for XDP, both ingress and egress interfaces can be used
+ * 		for redirection. The **BPF_F_INGRESS** value in *flags* is used
+ * 		to make the distinction (ingress path is selected if the flag
+ * 		is present, egress path otherwise). Currently, XDP only
+ * 		supports redirection to the egress interface, and accepts no
+ * 		flag at all.
+ *
+ * 		The same effect can be attained with the more generic
+ * 		**bpf_redirect_map**\ (), which requires specific maps to be
+ * 		used but offers better performance.
+ * 	Return
+ * 		For XDP, the helper returns **XDP_REDIRECT** on success or
+ * 		**XDP_ABORTED** on error. For other program types, the values
+ * 		are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
+ * 		error.
+ *
+ * u32 bpf_get_route_realm(struct sk_buff *skb)
+ * 	Description
+ * 		Retrieve the realm or the route, that is to say the
+ * 		**tclassid** field of the destination for the *skb*. The
+ * 		indentifier retrieved is a user-provided tag, similar to the
+ * 		one used with the net_cls cgroup (see description for
+ * 		**bpf_get_cgroup_classid**\ () helper), but here this tag is
+ * 		held by a route (a destination entry), not by a task.
+ *
+ * 		Retrieving this identifier works with the clsact TC egress hook
+ * 		(see also **tc-bpf(8)**), or alternatively on conventional
+ * 		classful egress qdiscs, but not on TC ingress path. In case of
+ * 		clsact TC egress hook, this has the advantage that, internally,
+ * 		the destination entry has not been dropped yet in the transmit
+ * 		path. Therefore, the destination entry does not need to be
+ * 		artificially held via **netif_keep_dst**\ () for a classful
+ * 		qdisc until the *skb* is freed.
+ *
+ * 		This helper is available only if the kernel was compiled with
+ * 		**CONFIG_IP_ROUTE_CLASSID** configuration option.
+ * 	Return
+ * 		The realm of the route for the packet associated to *skb*, or 0
+ * 		if none was found.
+ *
+ * int bpf_perf_event_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
+ * 	Description
+ * 		Write raw *data* blob into a special BPF perf event held by
+ * 		*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 		event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 		as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 		**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 		The *flags* are used to indicate the index in *map* for which
+ * 		the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 		Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 		to indicate that the index of the current CPU core should be
+ * 		used.
+ *
+ * 		The value to write, of *size*, is passed through eBPF stack and
+ * 		pointed by *data*.
+ *
+ * 		The context of the program *ctx* needs also be passed to the
+ * 		helper.
+ *
+ * 		On user space, a program willing to read the values needs to
+ * 		call **perf_event_open**\ () on the perf event (either for
+ * 		one or for all CPUs) and to store the file descriptor into the
+ * 		*map*. This must be done before the eBPF program can send data
+ * 		into it. An example is available in file
+ * 		*samples/bpf/trace_output_user.c* in the Linux kernel source
+ * 		tree (the eBPF program counterpart is in
+ * 		*samples/bpf/trace_output_kern.c*).
+ *
+ * 		**bpf_perf_event_output**\ () achieves better performance
+ * 		than **bpf_trace_printk**\ () for sharing data with user
+ * 		space, and is much better suitable for streaming data from eBPF
+ * 		programs.
+ *
+ * 		Note that this helper is not restricted to tracing use cases
+ * 		and can be used with programs attached to TC or XDP as well,
+ * 		where it allows for passing data to user space listeners. Data
+ * 		can be:
+ *
+ * 		* Only custom structs,
+ * 		* Only the packet payload, or
+ * 		* A combination of both.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_load_bytes(const void *skb, u32 offset, void *to, u32 len)
+ * 	Description
+ * 		This helper was provided as an easy way to load data from a
+ * 		packet. It can be used to load *len* bytes from *offset* from
+ * 		the packet associated to *skb*, into the buffer pointed by
+ * 		*to*.
+ *
+ * 		Since Linux 4.7, usage of this helper has mostly been replaced
+ * 		by "direct packet access", enabling packet data to be
+ * 		manipulated with *skb*\ **->data** and *skb*\ **->data_end**
+ * 		pointing respectively to the first byte of packet data and to
+ * 		the byte after the last byte of packet data. However, it
+ * 		remains useful if one wishes to read large quantities of data
+ * 		at once from a packet into the eBPF stack.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_get_stackid(void *ctx, struct bpf_map *map, u64 flags)
+ * 	Description
+ * 		Walk a user or a kernel stack and return its id. To achieve
+ * 		this, the helper needs *ctx*, which is a pointer to the context
+ * 		on which the tracing program is executed, and a pointer to a
+ * 		*map* of type **BPF_MAP_TYPE_STACK_TRACE**.
+ *
+ * 		The last argument, *flags*, holds the number of stack frames to
+ * 		skip (from 0 to 255), masked with
+ * 		**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 		a combination of the following flags:
+ *
+ * 		**BPF_F_USER_STACK**
+ * 			Collect a user space stack instead of a kernel stack.
+ * 		**BPF_F_FAST_STACK_CMP**
+ * 			Compare stacks by hash only.
+ * 		**BPF_F_REUSE_STACKID**
+ * 			If two different stacks hash into the same *stackid*,
+ * 			discard the old one.
+ *
+ * 		The stack id retrieved is a 32 bit long integer handle which
+ * 		can be further combined with other data (including other stack
+ * 		ids) and used as a key into maps. This can be useful for
+ * 		generating a variety of graphs (such as flame graphs or off-cpu
+ * 		graphs).
+ *
+ * 		For walking a stack, this helper is an improvement over
+ * 		**bpf_probe_read**\ (), which can be used with unrolled loops
+ * 		but is not efficient and consumes a lot of eBPF instructions.
+ * 		Instead, **bpf_get_stackid**\ () can collect up to
+ * 		**PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
+ * 		this limit can be controlled with the **sysctl** program, and
+ * 		that it should be manually increased in order to profile long
+ * 		user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 		::
+ *
+ * 			# sysctl kernel.perf_event_max_stack=<new value>
+ * 	Return
+ * 		The positive or null stack id on success, or a negative error
+ * 		in case of failure.
+ *
+ * s64 bpf_csum_diff(__be32 *from, u32 from_size, __be32 *to, u32 to_size, __wsum seed)
+ * 	Description
+ * 		Compute a checksum difference, from the raw buffer pointed by
+ * 		*from*, of length *from_size* (that must be a multiple of 4),
+ * 		towards the raw buffer pointed by *to*, of size *to_size*
+ * 		(same remark). An optional *seed* can be added to the value
+ * 		(this can be cascaded, the seed may come from a previous call
+ * 		to the helper).
+ *
+ * 		This is flexible enough to be used in several ways:
+ *
+ * 		* With *from_size* == 0, *to_size* > 0 and *seed* set to
+ * 		  checksum, it can be used when pushing new data.
+ * 		* With *from_size* > 0, *to_size* == 0 and *seed* set to
+ * 		  checksum, it can be used when removing data from a packet.
+ * 		* With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
+ * 		  can be used to compute a diff. Note that *from_size* and
+ * 		  *to_size* do not need to be equal.
+ *
+ * 		This helper can be used in combination with
+ * 		**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
+ * 		which one can feed in the difference computed with
+ * 		**bpf_csum_diff**\ ().
+ * 	Return
+ * 		The checksum result, or a negative error code in case of
+ * 		failure.
+ *
+ * int bpf_skb_get_tunnel_opt(struct sk_buff *skb, void *opt, u32 size)
+ * 	Description
+ * 		Retrieve tunnel options metadata for the packet associated to
+ * 		*skb*, and store the raw tunnel option data to the buffer *opt*
+ * 		of *size*.
+ *
+ * 		This helper can be used with encapsulation devices that can
+ * 		operate in "collect metadata" mode (please refer to the related
+ * 		note in the description of **bpf_skb_get_tunnel_key**\ () for
+ * 		more details). A particular example where this can be used is
+ * 		in combination with the Geneve encapsulation protocol, where it
+ * 		allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
+ * 		and retrieving arbitrary TLVs (Type-Length-Value headers) from
+ * 		the eBPF program. This allows for full customization of these
+ * 		headers.
+ * 	Return
+ * 		The size of the option data retrieved.
+ *
+ * int bpf_skb_set_tunnel_opt(struct sk_buff *skb, void *opt, u32 size)
+ * 	Description
+ * 		Set tunnel options metadata for the packet associated to *skb*
+ * 		to the option data contained in the raw buffer *opt* of *size*.
+ *
+ * 		See also the description of the **bpf_skb_get_tunnel_opt**\ ()
+ * 		helper for additional information.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_change_proto(struct sk_buff *skb, __be16 proto, u64 flags)
+ * 	Description
+ * 		Change the protocol of the *skb* to *proto*. Currently
+ * 		supported are transition from IPv4 to IPv6, and from IPv6 to
+ * 		IPv4. The helper takes care of the groundwork for the
+ * 		transition, including resizing the socket buffer. The eBPF
+ * 		program is expected to fill the new headers, if any, via
+ * 		**skb_store_bytes**\ () and to recompute the checksums with
+ * 		**bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
+ * 		(). The main case for this helper is to perform NAT64
+ * 		operations out of an eBPF program.
+ *
+ * 		Internally, the GSO type is marked as dodgy so that headers are
+ * 		checked and segments are recalculated by the GSO/GRO engine.
+ * 		The size for GSO target is adapted as well.
+ *
+ * 		All values for *flags* are reserved for future usage, and must
+ * 		be left at zero.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_change_type(struct sk_buff *skb, u32 type)
+ * 	Description
+ * 		Change the packet type for the packet associated to *skb*. This
+ * 		comes down to setting *skb*\ **->pkt_type** to *type*, except
+ * 		the eBPF program does not have a write access to *skb*\
+ * 		**->pkt_type** beside this helper. Using a helper here allows
+ * 		for graceful handling of errors.
+ *
+ * 		The major use case is to change incoming *skb*s to
+ * 		**PACKET_HOST** in a programmatic way instead of having to
+ * 		recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
+ * 		example.
+ *
+ * 		Note that *type* only allows certain values. At this time, they
+ * 		are:
+ *
+ * 		**PACKET_HOST**
+ * 			Packet is for us.
+ * 		**PACKET_BROADCAST**
+ * 			Send packet to all.
+ * 		**PACKET_MULTICAST**
+ * 			Send packet to group.
+ * 		**PACKET_OTHERHOST**
+ * 			Send packet to someone else.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_under_cgroup(struct sk_buff *skb, struct bpf_map *map, u32 index)
+ * 	Description
+ * 		Check whether *skb* is a descendant of the cgroup2 held by
+ * 		*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ * 	Return
+ * 		The return value depends on the result of the test, and can be:
+ *
+ * 		* 0, if the *skb* failed the cgroup2 descendant test.
+ * 		* 1, if the *skb* succeeded the cgroup2 descendant test.
+ * 		* A negative error code, if an error occurred.
+ *
+ * u32 bpf_get_hash_recalc(struct sk_buff *skb)
+ * 	Description
+ * 		Retrieve the hash of the packet, *skb*\ **->hash**. If it is
+ * 		not set, in particular if the hash was cleared due to mangling,
+ * 		recompute this hash. Later accesses to the hash can be done
+ * 		directly with *skb*\ **->hash**.
+ *
+ * 		Calling **bpf_set_hash_invalid**\ (), changing a packet
+ * 		prototype with **bpf_skb_change_proto**\ (), or calling
+ * 		**bpf_skb_store_bytes**\ () with the
+ * 		**BPF_F_INVALIDATE_HASH** are actions susceptible to clear
+ * 		the hash and to trigger a new computation for the next call to
+ * 		**bpf_get_hash_recalc**\ ().
+ * 	Return
+ * 		The 32-bit hash.
+ *
+ * u64 bpf_get_current_task(void)
+ * 	Return
+ * 		A pointer to the current task struct.
+ *
+ * int bpf_probe_write_user(void *dst, const void *src, u32 len)
+ * 	Description
+ * 		Attempt in a safe way to write *len* bytes from the buffer
+ * 		*src* to *dst* in memory. It only works for threads that are in
+ * 		user context, and *dst* must be a valid user space address.
+ *
+ * 		This helper should not be used to implement any kind of
+ * 		security mechanism because of TOC-TOU attacks, but rather to
+ * 		debug, divert, and manipulate execution of semi-cooperative
+ * 		processes.
+ *
+ * 		Keep in mind that this feature is meant for experiments, and it
+ * 		has a risk of crashing the system and running programs.
+ * 		Therefore, when an eBPF program using this helper is attached,
+ * 		a warning including PID and process name is printed to kernel
+ * 		logs.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_current_task_under_cgroup(struct bpf_map *map, u32 index)
+ * 	Description
+ * 		Check whether the probe is being run is the context of a given
+ * 		subset of the cgroup2 hierarchy. The cgroup2 to test is held by
+ * 		*map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
+ * 	Return
+ * 		The return value depends on the result of the test, and can be:
+ *
+ * 		* 0, if the *skb* task belongs to the cgroup2.
+ * 		* 1, if the *skb* task does not belong to the cgroup2.
+ * 		* A negative error code, if an error occurred.
+ *
+ * int bpf_skb_change_tail(struct sk_buff *skb, u32 len, u64 flags)
+ * 	Description
+ * 		Resize (trim or grow) the packet associated to *skb* to the
+ * 		new *len*. The *flags* are reserved for future usage, and must
+ * 		be left at zero.
+ *
+ * 		The basic idea is that the helper performs the needed work to
+ * 		change the size of the packet, then the eBPF program rewrites
+ * 		the rest via helpers like **bpf_skb_store_bytes**\ (),
+ * 		**bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
+ * 		and others. This helper is a slow path utility intended for
+ * 		replies with control messages. And because it is targeted for
+ * 		slow path, the helper itself can afford to be slow: it
+ * 		implicitly linearizes, unclones and drops offloads from the
+ * 		*skb*.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_pull_data(struct sk_buff *skb, u32 len)
+ * 	Description
+ * 		Pull in non-linear data in case the *skb* is non-linear and not
+ * 		all of *len* are part of the linear section. Make *len* bytes
+ * 		from *skb* readable and writable. If a zero value is passed for
+ * 		*len*, then the whole length of the *skb* is pulled.
+ *
+ * 		This helper is only needed for reading and writing with direct
+ * 		packet access.
+ *
+ * 		For direct packet access, testing that offsets to access
+ * 		are within packet boundaries (test on *skb*\ **->data_end**) is
+ * 		susceptible to fail if offsets are invalid, or if the requested
+ * 		data is in non-linear parts of the *skb*. On failure the
+ * 		program can just bail out, or in the case of a non-linear
+ * 		buffer, use a helper to make the data available. The
+ * 		**bpf_skb_load_bytes**\ () helper is a first solution to access
+ * 		the data. Another one consists in using **bpf_skb_pull_data**
+ * 		to pull in once the non-linear parts, then retesting and
+ * 		eventually access the data.
+ *
+ * 		At the same time, this also makes sure the *skb* is uncloned,
+ * 		which is a necessary condition for direct write. As this needs
+ * 		to be an invariant for the write part only, the verifier
+ * 		detects writes and adds a prologue that is calling
+ * 		**bpf_skb_pull_data()** to effectively unclone the *skb* from
+ * 		the very beginning in case it is indeed cloned.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * s64 bpf_csum_update(struct sk_buff *skb, __wsum csum)
+ * 	Description
+ * 		Add the checksum *csum* into *skb*\ **->csum** in case the
+ * 		driver has supplied a checksum for the entire packet into that
+ * 		field. Return an error otherwise. This helper is intended to be
+ * 		used in combination with **bpf_csum_diff**\ (), in particular
+ * 		when the checksum needs to be updated after data has been
+ * 		written into the packet through direct packet access.
+ * 	Return
+ * 		The checksum on success, or a negative error code in case of
+ * 		failure.
+ *
+ * void bpf_set_hash_invalid(struct sk_buff *skb)
+ * 	Description
+ * 		Invalidate the current *skb*\ **->hash**. It can be used after
+ * 		mangling on headers through direct packet access, in order to
+ * 		indicate that the hash is outdated and to trigger a
+ * 		recalculation the next time the kernel tries to access this
+ * 		hash or when the **bpf_get_hash_recalc**\ () helper is called.
+ *
+ * int bpf_get_numa_node_id(void)
+ * 	Description
+ * 		Return the id of the current NUMA node. The primary use case
+ * 		for this helper is the selection of sockets for the local NUMA
+ * 		node, when the program is attached to sockets using the
+ * 		**SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
+ * 		but the helper is also available to other eBPF program types,
+ * 		similarly to **bpf_get_smp_processor_id**\ ().
+ * 	Return
+ * 		The id of current NUMA node.
+ *
+ * int bpf_skb_change_head(struct sk_buff *skb, u32 len, u64 flags)
+ * 	Description
+ * 		Grows headroom of packet associated to *skb* and adjusts the
+ * 		offset of the MAC header accordingly, adding *len* bytes of
+ * 		space. It automatically extends and reallocates memory as
+ * 		required.
+ *
+ * 		This helper can be used on a layer 3 *skb* to push a MAC header
+ * 		for redirection into a layer 2 device.
+ *
+ * 		All values for *flags* are reserved for future usage, and must
+ * 		be left at zero.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_xdp_adjust_head(struct xdp_buff *xdp_md, int delta)
+ * 	Description
+ * 		Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
+ * 		it is possible to use a negative value for *delta*. This helper
+ * 		can be used to prepare the packet for pushing or popping
+ * 		headers.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_probe_read_str(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		Copy a NUL terminated string from an unsafe kernel address
+ * 		*unsafe_ptr* to *dst*. See bpf_probe_read_kernel_str() for
+ * 		more details.
+ *
+ * 		Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str()
+ * 		instead.
+ * 	Return
+ * 		On success, the strictly positive length of the string,
+ * 		including the trailing NUL character. On error, a negative
+ * 		value.
+ *
+ * u64 bpf_get_socket_cookie(struct sk_buff *skb)
+ * 	Description
+ * 		If the **struct sk_buff** pointed by *skb* has a known socket,
+ * 		retrieve the cookie (generated by the kernel) of this socket.
+ * 		If no cookie has been set yet, generate a new cookie. Once
+ * 		generated, the socket cookie remains stable for the life of the
+ * 		socket. This helper can be useful for monitoring per socket
+ * 		networking traffic statistics as it provides a global socket
+ * 		identifier that can be assumed unique.
+ * 	Return
+ * 		A 8-byte long non-decreasing number on success, or 0 if the
+ * 		socket field is missing inside *skb*.
+ *
+ * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
+ * 	Description
+ * 		Equivalent to bpf_get_socket_cookie() helper that accepts
+ * 		*skb*, but gets socket from **struct bpf_sock_addr** context.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
+ * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
+ * 	Description
+ * 		Equivalent to bpf_get_socket_cookie() helper that accepts
+ * 		*skb*, but gets socket from **struct bpf_sock_ops** context.
+ * 	Return
+ * 		A 8-byte long non-decreasing number.
+ *
+ * u32 bpf_get_socket_uid(struct sk_buff *skb)
+ * 	Return
+ * 		The owner UID of the socket associated to *skb*. If the socket
+ * 		is **NULL**, or if it is not a full socket (i.e. if it is a
+ * 		time-wait or a request socket instead), **overflowuid** value
+ * 		is returned (note that **overflowuid** might also be the actual
+ * 		UID value for the socket).
+ *
+ * u32 bpf_set_hash(struct sk_buff *skb, u32 hash)
+ * 	Description
+ * 		Set the full hash for *skb* (set the field *skb*\ **->hash**)
+ * 		to value *hash*.
+ * 	Return
+ * 		0
+ *
+ * int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
+ * 	Description
+ * 		Emulate a call to **setsockopt()** on the socket associated to
+ * 		*bpf_socket*, which must be a full socket. The *level* at
+ * 		which the option resides and the name *optname* of the option
+ * 		must be specified, see **setsockopt(2)** for more information.
+ * 		The option value of length *optlen* is pointed by *optval*.
+ *
+ * 		This helper actually implements a subset of **setsockopt()**.
+ * 		It supports the following *level*\ s:
+ *
+ * 		* **SOL_SOCKET**, which supports the following *optname*\ s:
+ * 		  **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
+ * 		  **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**.
+ * 		* **IPPROTO_TCP**, which supports the following *optname*\ s:
+ * 		  **TCP_CONGESTION**, **TCP_BPF_IW**,
+ * 		  **TCP_BPF_SNDCWND_CLAMP**.
+ * 		* **IPPROTO_IP**, which supports *optname* **IP_TOS**.
+ * 		* **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_adjust_room(struct sk_buff *skb, s32 len_diff, u32 mode, u64 flags)
+ * 	Description
+ * 		Grow or shrink the room for data in the packet associated to
+ * 		*skb* by *len_diff*, and according to the selected *mode*.
+ *
+ *		There are two supported modes at this time:
+ *
+ *		* **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
+ *		  (room space is added or removed below the layer 2 header).
+ *
+ * 		* **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
+ * 		  (room space is added or removed below the layer 3 header).
+ *
+ *		The following flags are supported at this time:
+ *
+ *		* **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
+ *		  Adjusting mss in this way is not allowed for datagrams.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
+ *		  **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
+ *		  Any new space is reserved to hold a tunnel header.
+ *		  Configure skb offsets and other fields accordingly.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
+ *		  **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
+ *		  Use with ENCAP_L3 flags to further specify the tunnel type.
+ *
+ *		* **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
+ *		  Use with ENCAP_L3/L4 flags to further specify the tunnel
+ *		  type; *len* is the length of the inner MAC header.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags)
+ * 	Description
+ * 		Redirect the packet to the endpoint referenced by *map* at
+ * 		index *key*. Depending on its type, this *map* can contain
+ * 		references to net devices (for forwarding packets through other
+ * 		ports), or to CPUs (for redirecting XDP frames to another CPU;
+ * 		but this is only implemented for native XDP (with driver
+ * 		support) as of this writing).
+ *
+ * 		The lower two bits of *flags* are used as the return code if
+ * 		the map lookup fails. This is so that the return value can be
+ * 		one of the XDP program return codes up to XDP_TX, as chosen by
+ * 		the caller. Any higher bits in the *flags* argument must be
+ * 		unset.
+ *
+ * 		When used to redirect packets to net devices, this helper
+ * 		provides a high performance increase over **bpf_redirect**\ ().
+ * 		This is due to various implementation details of the underlying
+ * 		mechanisms, one of which is the fact that **bpf_redirect_map**\
+ * 		() tries to send packet as a "bulk" to the device.
+ * 	Return
+ * 		**XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
+ *
+ * int bpf_sk_redirect_map(struct sk_buff *skb, struct bpf_map *map, u32 key, u64 flags)
+ * 	Description
+ * 		Redirect the packet to the socket referenced by *map* (of type
+ * 		**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 		egress interfaces can be used for redirection. The
+ * 		**BPF_F_INGRESS** value in *flags* is used to make the
+ * 		distinction (ingress path is selected if the flag is present,
+ * 		egress path otherwise). This is the only flag supported for now.
+ * 	Return
+ * 		**SK_PASS** on success, or **SK_DROP** on error.
+ *
+ * int bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
+ * 	Description
+ * 		Add an entry to, or update a *map* referencing sockets. The
+ * 		*skops* is used as a new value for the entry associated to
+ * 		*key*. *flags* is one of:
+ *
+ * 		**BPF_NOEXIST**
+ * 			The entry for *key* must not exist in the map.
+ * 		**BPF_EXIST**
+ * 			The entry for *key* must already exist in the map.
+ * 		**BPF_ANY**
+ * 			No condition on the existence of the entry for *key*.
+ *
+ * 		If the *map* has eBPF programs (parser and verdict), those will
+ * 		be inherited by the socket being added. If the socket is
+ * 		already attached to eBPF programs, this results in an error.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_xdp_adjust_meta(struct xdp_buff *xdp_md, int delta)
+ * 	Description
+ * 		Adjust the address pointed by *xdp_md*\ **->data_meta** by
+ * 		*delta* (which can be positive or negative). Note that this
+ * 		operation modifies the address stored in *xdp_md*\ **->data**,
+ * 		so the latter must be loaded only after the helper has been
+ * 		called.
+ *
+ * 		The use of *xdp_md*\ **->data_meta** is optional and programs
+ * 		are not required to use it. The rationale is that when the
+ * 		packet is processed with XDP (e.g. as DoS filter), it is
+ * 		possible to push further meta data along with it before passing
+ * 		to the stack, and to give the guarantee that an ingress eBPF
+ * 		program attached as a TC classifier on the same device can pick
+ * 		this up for further post-processing. Since TC works with socket
+ * 		buffers, it remains possible to set from XDP the **mark** or
+ * 		**priority** pointers, or other pointers for the socket buffer.
+ * 		Having this scratch space generic and programmable allows for
+ * 		more flexibility as the user is free to store whatever meta
+ * 		data they need.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_perf_event_read_value(struct bpf_map *map, u64 flags, struct bpf_perf_event_value *buf, u32 buf_size)
+ * 	Description
+ * 		Read the value of a perf event counter, and store it into *buf*
+ * 		of size *buf_size*. This helper relies on a *map* of type
+ * 		**BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
+ * 		counter is selected when *map* is updated with perf event file
+ * 		descriptors. The *map* is an array whose size is the number of
+ * 		available CPUs, and each cell contains a value relative to one
+ * 		CPU. The value to retrieve is indicated by *flags*, that
+ * 		contains the index of the CPU to look up, masked with
+ * 		**BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
+ * 		**BPF_F_CURRENT_CPU** to indicate that the value for the
+ * 		current CPU should be retrieved.
+ *
+ * 		This helper behaves in a way close to
+ * 		**bpf_perf_event_read**\ () helper, save that instead of
+ * 		just returning the value observed, it fills the *buf*
+ * 		structure. This allows for additional data to be retrieved: in
+ * 		particular, the enabled and running times (in *buf*\
+ * 		**->enabled** and *buf*\ **->running**, respectively) are
+ * 		copied. In general, **bpf_perf_event_read_value**\ () is
+ * 		recommended over **bpf_perf_event_read**\ (), which has some
+ * 		ABI issues and provides fewer functionalities.
+ *
+ * 		These values are interesting, because hardware PMU (Performance
+ * 		Monitoring Unit) counters are limited resources. When there are
+ * 		more PMU based perf events opened than available counters,
+ * 		kernel will multiplex these events so each event gets certain
+ * 		percentage (but not all) of the PMU time. In case that
+ * 		multiplexing happens, the number of samples or counter value
+ * 		will not reflect the case compared to when no multiplexing
+ * 		occurs. This makes comparison between different runs difficult.
+ * 		Typically, the counter value should be normalized before
+ * 		comparing to other experiments. The usual normalization is done
+ * 		as follows.
+ *
+ * 		::
+ *
+ * 			normalized_counter = counter * t_enabled / t_running
+ *
+ * 		Where t_enabled is the time enabled for event and t_running is
+ * 		the time running for event since last normalization. The
+ * 		enabled and running times are accumulated since the perf event
+ * 		open. To achieve scaling factor between two invocations of an
+ * 		eBPF program, users can can use CPU id as the key (which is
+ * 		typical for perf array usage model) to remember the previous
+ * 		value and do the calculation inside the eBPF program.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_perf_prog_read_value(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
+ * 	Description
+ * 		For en eBPF program attached to a perf event, retrieve the
+ * 		value of the event counter associated to *ctx* and store it in
+ * 		the structure pointed by *buf* and of size *buf_size*. Enabled
+ * 		and running times are also stored in the structure (see
+ * 		description of helper **bpf_perf_event_read_value**\ () for
+ * 		more details).
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
+ * 	Description
+ * 		Emulate a call to **getsockopt()** on the socket associated to
+ * 		*bpf_socket*, which must be a full socket. The *level* at
+ * 		which the option resides and the name *optname* of the option
+ * 		must be specified, see **getsockopt(2)** for more information.
+ * 		The retrieved value is stored in the structure pointed by
+ * 		*opval* and of length *optlen*.
+ *
+ * 		This helper actually implements a subset of **getsockopt()**.
+ * 		It supports the following *level*\ s:
+ *
+ * 		* **IPPROTO_TCP**, which supports *optname*
+ * 		  **TCP_CONGESTION**.
+ * 		* **IPPROTO_IP**, which supports *optname* **IP_TOS**.
+ * 		* **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_override_return(struct pt_regs *regs, u64 rc)
+ * 	Description
+ * 		Used for error injection, this helper uses kprobes to override
+ * 		the return value of the probed function, and to set it to *rc*.
+ * 		The first argument is the context *regs* on which the kprobe
+ * 		works.
+ *
+ * 		This helper works by setting setting the PC (program counter)
+ * 		to an override function which is run in place of the original
+ * 		probed function. This means the probed function is not run at
+ * 		all. The replacement function just returns with the required
+ * 		value.
+ *
+ * 		This helper has security implications, and thus is subject to
+ * 		restrictions. It is only available if the kernel was compiled
+ * 		with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
+ * 		option, and in this case it only works on functions tagged with
+ * 		**ALLOW_ERROR_INJECTION** in the kernel code.
+ *
+ * 		Also, the helper is only available for the architectures having
+ * 		the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
+ * 		x86 architecture is the only one to support this feature.
+ * 	Return
+ * 		0
+ *
+ * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *bpf_sock, int argval)
+ * 	Description
+ * 		Attempt to set the value of the **bpf_sock_ops_cb_flags** field
+ * 		for the full TCP socket associated to *bpf_sock_ops* to
+ * 		*argval*.
+ *
+ * 		The primary use of this field is to determine if there should
+ * 		be calls to eBPF programs of type
+ * 		**BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
+ * 		code. A program of the same type can change its value, per
+ * 		connection and as necessary, when the connection is
+ * 		established. This field is directly accessible for reading, but
+ * 		this helper must be used for updates in order to return an
+ * 		error if an eBPF program tries to set a callback that is not
+ * 		supported in the current kernel.
+ *
+ * 		*argval* is a flag array which can combine these flags:
+ *
+ * 		* **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
+ * 		* **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
+ * 		* **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
+ * 		* **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
+ *
+ * 		Therefore, this function can be used to clear a callback flag by
+ * 		setting the appropriate bit to zero. e.g. to disable the RTO
+ * 		callback:
+ *
+ * 		**bpf_sock_ops_cb_flags_set(bpf_sock,**
+ * 			**bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
+ *
+ * 		Here are some examples of where one could call such eBPF
+ * 		program:
+ *
+ * 		* When RTO fires.
+ * 		* When a packet is retransmitted.
+ * 		* When the connection terminates.
+ * 		* When a packet is sent.
+ * 		* When a packet is received.
+ * 	Return
+ * 		Code **-EINVAL** if the socket is not a full TCP socket;
+ * 		otherwise, a positive number containing the bits that could not
+ * 		be set is returned (which comes down to 0 if all bits were set
+ * 		as required).
+ *
+ * int bpf_msg_redirect_map(struct sk_msg_buff *msg, struct bpf_map *map, u32 key, u64 flags)
+ * 	Description
+ * 		This helper is used in programs implementing policies at the
+ * 		socket level. If the message *msg* is allowed to pass (i.e. if
+ * 		the verdict eBPF program returns **SK_PASS**), redirect it to
+ * 		the socket referenced by *map* (of type
+ * 		**BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
+ * 		egress interfaces can be used for redirection. The
+ * 		**BPF_F_INGRESS** value in *flags* is used to make the
+ * 		distinction (ingress path is selected if the flag is present,
+ * 		egress path otherwise). This is the only flag supported for now.
+ * 	Return
+ * 		**SK_PASS** on success, or **SK_DROP** on error.
+ *
+ * int bpf_msg_apply_bytes(struct sk_msg_buff *msg, u32 bytes)
+ * 	Description
+ * 		For socket policies, apply the verdict of the eBPF program to
+ * 		the next *bytes* (number of bytes) of message *msg*.
+ *
+ * 		For example, this helper can be used in the following cases:
+ *
+ * 		* A single **sendmsg**\ () or **sendfile**\ () system call
+ * 		  contains multiple logical messages that the eBPF program is
+ * 		  supposed to read and for which it should apply a verdict.
+ * 		* An eBPF program only cares to read the first *bytes* of a
+ * 		  *msg*. If the message has a large payload, then setting up
+ * 		  and calling the eBPF program repeatedly for all bytes, even
+ * 		  though the verdict is already known, would create unnecessary
+ * 		  overhead.
+ *
+ * 		When called from within an eBPF program, the helper sets a
+ * 		counter internal to the BPF infrastructure, that is used to
+ * 		apply the last verdict to the next *bytes*. If *bytes* is
+ * 		smaller than the current data being processed from a
+ * 		**sendmsg**\ () or **sendfile**\ () system call, the first
+ * 		*bytes* will be sent and the eBPF program will be re-run with
+ * 		the pointer for start of data pointing to byte number *bytes*
+ * 		**+ 1**. If *bytes* is larger than the current data being
+ * 		processed, then the eBPF verdict will be applied to multiple
+ * 		**sendmsg**\ () or **sendfile**\ () calls until *bytes* are
+ * 		consumed.
+ *
+ * 		Note that if a socket closes with the internal counter holding
+ * 		a non-zero value, this is not a problem because data is not
+ * 		being buffered for *bytes* and is sent as it is received.
+ * 	Return
+ * 		0
+ *
+ * int bpf_msg_cork_bytes(struct sk_msg_buff *msg, u32 bytes)
+ * 	Description
+ * 		For socket policies, prevent the execution of the verdict eBPF
+ * 		program for message *msg* until *bytes* (byte number) have been
+ * 		accumulated.
+ *
+ * 		This can be used when one needs a specific number of bytes
+ * 		before a verdict can be assigned, even if the data spans
+ * 		multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
+ * 		case would be a user calling **sendmsg**\ () repeatedly with
+ * 		1-byte long message segments. Obviously, this is bad for
+ * 		performance, but it is still valid. If the eBPF program needs
+ * 		*bytes* bytes to validate a header, this helper can be used to
+ * 		prevent the eBPF program to be called again until *bytes* have
+ * 		been accumulated.
+ * 	Return
+ * 		0
+ *
+ * int bpf_msg_pull_data(struct sk_msg_buff *msg, u32 start, u32 end, u64 flags)
+ * 	Description
+ * 		For socket policies, pull in non-linear data from user space
+ * 		for *msg* and set pointers *msg*\ **->data** and *msg*\
+ * 		**->data_end** to *start* and *end* bytes offsets into *msg*,
+ * 		respectively.
+ *
+ * 		If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ * 		*msg* it can only parse data that the (**data**, **data_end**)
+ * 		pointers have already consumed. For **sendmsg**\ () hooks this
+ * 		is likely the first scatterlist element. But for calls relying
+ * 		on the **sendpage** handler (e.g. **sendfile**\ ()) this will
+ * 		be the range (**0**, **0**) because the data is shared with
+ * 		user space and by default the objective is to avoid allowing
+ * 		user space to modify data while (or after) eBPF verdict is
+ * 		being decided. This helper can be used to pull in data and to
+ * 		set the start and end pointer to given values. Data will be
+ * 		copied if necessary (i.e. if data was not linear and if start
+ * 		and end pointers do not point to the same chunk).
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ *
+ * 		All values for *flags* are reserved for future usage, and must
+ * 		be left at zero.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_bind(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len)
+ * 	Description
+ * 		Bind the socket associated to *ctx* to the address pointed by
+ * 		*addr*, of length *addr_len*. This allows for making outgoing
+ * 		connection from the desired IP address, which can be useful for
+ * 		example when all processes inside a cgroup should use one
+ * 		single IP address on a host that has multiple IP configured.
+ *
+ * 		This helper works for IPv4 and IPv6, TCP and UDP sockets. The
+ * 		domain (*addr*\ **->sa_family**) must be **AF_INET** (or
+ * 		**AF_INET6**). Looking for a free port to bind to can be
+ * 		expensive, therefore binding to port is not permitted by the
+ * 		helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
+ * 		must be set to zero.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta)
+ * 	Description
+ * 		Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
+ * 		only possible to shrink the packet as of this writing,
+ * 		therefore *delta* must be a negative integer.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_skb_get_xfrm_state(struct sk_buff *skb, u32 index, struct bpf_xfrm_state *xfrm_state, u32 size, u64 flags)
+ * 	Description
+ * 		Retrieve the XFRM state (IP transform framework, see also
+ * 		**ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
+ *
+ * 		The retrieved value is stored in the **struct bpf_xfrm_state**
+ * 		pointed by *xfrm_state* and of length *size*.
+ *
+ * 		All values for *flags* are reserved for future usage, and must
+ * 		be left at zero.
+ *
+ * 		This helper is available only if the kernel was compiled with
+ * 		**CONFIG_XFRM** configuration option.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_get_stack(void *ctx, void *buf, u32 size, u64 flags)
+ * 	Description
+ * 		Return a user or a kernel stack in bpf program provided buffer.
+ * 		To achieve this, the helper needs *ctx*, which is a pointer
+ * 		to the context on which the tracing program is executed.
+ * 		To store the stacktrace, the bpf program provides *buf* with
+ * 		a nonnegative *size*.
+ *
+ * 		The last argument, *flags*, holds the number of stack frames to
+ * 		skip (from 0 to 255), masked with
+ * 		**BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ * 		the following flags:
+ *
+ * 		**BPF_F_USER_STACK**
+ * 			Collect a user space stack instead of a kernel stack.
+ * 		**BPF_F_USER_BUILD_ID**
+ * 			Collect buildid+offset instead of ips for user stack,
+ * 			only valid if **BPF_F_USER_STACK** is also specified.
+ *
+ * 		**bpf_get_stack**\ () can collect up to
+ * 		**PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
+ * 		to sufficient large buffer size. Note that
+ * 		this limit can be controlled with the **sysctl** program, and
+ * 		that it should be manually increased in order to profile long
+ * 		user stacks (such as stacks for Java programs). To do so, use:
+ *
+ * 		::
+ *
+ * 			# sysctl kernel.perf_event_max_stack=<new value>
+ * 	Return
+ * 		A non-negative value equal to or less than *size* on success,
+ * 		or a negative error in case of failure.
+ *
+ * int bpf_skb_load_bytes_relative(const void *skb, u32 offset, void *to, u32 len, u32 start_header)
+ * 	Description
+ * 		This helper is similar to **bpf_skb_load_bytes**\ () in that
+ * 		it provides an easy way to load *len* bytes from *offset*
+ * 		from the packet associated to *skb*, into the buffer pointed
+ * 		by *to*. The difference to **bpf_skb_load_bytes**\ () is that
+ * 		a fifth argument *start_header* exists in order to select a
+ * 		base offset to start from. *start_header* can be one of:
+ *
+ * 		**BPF_HDR_START_MAC**
+ * 			Base offset to load data from is *skb*'s mac header.
+ * 		**BPF_HDR_START_NET**
+ * 			Base offset to load data from is *skb*'s network header.
+ *
+ * 		In general, "direct packet access" is the preferred method to
+ * 		access packet data, however, this helper is in particular useful
+ * 		in socket filters where *skb*\ **->data** does not always point
+ * 		to the start of the mac header and where "direct packet access"
+ * 		is not available.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_fib_lookup(void *ctx, struct bpf_fib_lookup *params, int plen, u32 flags)
+ *	Description
+ *		Do FIB lookup in kernel tables using parameters in *params*.
+ *		If lookup is successful and result shows packet is to be
+ *		forwarded, the neighbor tables are searched for the nexthop.
+ *		If successful (ie., FIB lookup shows forwarding and nexthop
+ *		is resolved), the nexthop address is returned in ipv4_dst
+ *		or ipv6_dst based on family, smac is set to mac address of
+ *		egress device, dmac is set to nexthop mac address, rt_metric
+ *		is set to metric from route (IPv4/IPv6 only), and ifindex
+ *		is set to the device index of the nexthop from the FIB lookup.
+ *
+ *		*plen* argument is the size of the passed in struct.
+ *		*flags* argument can be a combination of one or more of the
+ *		following values:
+ *
+ *		**BPF_FIB_LOOKUP_DIRECT**
+ *			Do a direct table lookup vs full lookup using FIB
+ *			rules.
+ *		**BPF_FIB_LOOKUP_OUTPUT**
+ *			Perform lookup from an egress perspective (default is
+ *			ingress).
+ *
+ *		*ctx* is either **struct xdp_md** for XDP programs or
+ *		**struct sk_buff** tc cls_act programs.
+ *	Return
+ *		* < 0 if any input argument is invalid
+ *		*   0 on success (packet is forwarded, nexthop neighbor exists)
+ *		* > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
+ *		  packet is not forwarded or needs assist from full stack
+ *
+ * int bpf_sock_hash_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
+ *	Description
+ *		Add an entry to, or update a sockhash *map* referencing sockets.
+ *		The *skops* is used as a new value for the entry associated to
+ *		*key*. *flags* is one of:
+ *
+ *		**BPF_NOEXIST**
+ *			The entry for *key* must not exist in the map.
+ *		**BPF_EXIST**
+ *			The entry for *key* must already exist in the map.
+ *		**BPF_ANY**
+ *			No condition on the existence of the entry for *key*.
+ *
+ *		If the *map* has eBPF programs (parser and verdict), those will
+ *		be inherited by the socket being added. If the socket is
+ *		already attached to eBPF programs, this results in an error.
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_msg_redirect_hash(struct sk_msg_buff *msg, struct bpf_map *map, void *key, u64 flags)
+ *	Description
+ *		This helper is used in programs implementing policies at the
+ *		socket level. If the message *msg* is allowed to pass (i.e. if
+ *		the verdict eBPF program returns **SK_PASS**), redirect it to
+ *		the socket referenced by *map* (of type
+ *		**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ *		egress interfaces can be used for redirection. The
+ *		**BPF_F_INGRESS** value in *flags* is used to make the
+ *		distinction (ingress path is selected if the flag is present,
+ *		egress path otherwise). This is the only flag supported for now.
+ *	Return
+ *		**SK_PASS** on success, or **SK_DROP** on error.
+ *
+ * int bpf_sk_redirect_hash(struct sk_buff *skb, struct bpf_map *map, void *key, u64 flags)
+ *	Description
+ *		This helper is used in programs implementing policies at the
+ *		skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
+ *		if the verdeict eBPF program returns **SK_PASS**), redirect it
+ *		to the socket referenced by *map* (of type
+ *		**BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
+ *		egress interfaces can be used for redirection. The
+ *		**BPF_F_INGRESS** value in *flags* is used to make the
+ *		distinction (ingress path is selected if the flag is present,
+ *		egress otherwise). This is the only flag supported for now.
+ *	Return
+ *		**SK_PASS** on success, or **SK_DROP** on error.
+ *
+ * int bpf_lwt_push_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len)
+ *	Description
+ *		Encapsulate the packet associated to *skb* within a Layer 3
+ *		protocol header. This header is provided in the buffer at
+ *		address *hdr*, with *len* its size in bytes. *type* indicates
+ *		the protocol of the header and can be one of:
+ *
+ *		**BPF_LWT_ENCAP_SEG6**
+ *			IPv6 encapsulation with Segment Routing Header
+ *			(**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
+ *			the IPv6 header is computed by the kernel.
+ *		**BPF_LWT_ENCAP_SEG6_INLINE**
+ *			Only works if *skb* contains an IPv6 packet. Insert a
+ *			Segment Routing Header (**struct ipv6_sr_hdr**) inside
+ *			the IPv6 header.
+ *		**BPF_LWT_ENCAP_IP**
+ *			IP encapsulation (GRE/GUE/IPIP/etc). The outer header
+ *			must be IPv4 or IPv6, followed by zero or more
+ *			additional headers, up to **LWT_BPF_MAX_HEADROOM**
+ *			total bytes in all prepended headers. Please note that
+ *			if **skb_is_gso**\ (*skb*) is true, no more than two
+ *			headers can be prepended, and the inner header, if
+ *			present, should be either GRE or UDP/GUE.
+ *
+ *		**BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
+ *		of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
+ *		be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
+ *		**BPF_PROG_TYPE_LWT_XMIT**.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ *	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_lwt_seg6_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len)
+ *	Description
+ *		Store *len* bytes from address *from* into the packet
+ *		associated to *skb*, at *offset*. Only the flags, tag and TLVs
+ *		inside the outermost IPv6 Segment Routing Header can be
+ *		modified through this helper.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ *	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_lwt_seg6_adjust_srh(struct sk_buff *skb, u32 offset, s32 delta)
+ *	Description
+ *		Adjust the size allocated to TLVs in the outermost IPv6
+ *		Segment Routing Header contained in the packet associated to
+ *		*skb*, at position *offset* by *delta* bytes. Only offsets
+ *		after the segments are accepted. *delta* can be as well
+ *		positive (growing) as negative (shrinking).
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ *	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_lwt_seg6_action(struct sk_buff *skb, u32 action, void *param, u32 param_len)
+ *	Description
+ *		Apply an IPv6 Segment Routing action of type *action* to the
+ *		packet associated to *skb*. Each action takes a parameter
+ *		contained at address *param*, and of length *param_len* bytes.
+ *		*action* can be one of:
+ *
+ *		**SEG6_LOCAL_ACTION_END_X**
+ *			End.X action: Endpoint with Layer-3 cross-connect.
+ *			Type of *param*: **struct in6_addr**.
+ *		**SEG6_LOCAL_ACTION_END_T**
+ *			End.T action: Endpoint with specific IPv6 table lookup.
+ *			Type of *param*: **int**.
+ *		**SEG6_LOCAL_ACTION_END_B6**
+ *			End.B6 action: Endpoint bound to an SRv6 policy.
+ *			Type of *param*: **struct ipv6_sr_hdr**.
+ *		**SEG6_LOCAL_ACTION_END_B6_ENCAP**
+ *			End.B6.Encap action: Endpoint bound to an SRv6
+ *			encapsulation policy.
+ *			Type of *param*: **struct ipv6_sr_hdr**.
+ *
+ * 		A call to this helper is susceptible to change the underlying
+ * 		packet buffer. Therefore, at load time, all checks on pointers
+ * 		previously done by the verifier are invalidated and must be
+ * 		performed again, if the helper is used in combination with
+ * 		direct packet access.
+ *	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_rc_repeat(void *ctx)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded repeat key message. This delays
+ *		the generation of a key up event for previously generated
+ *		key down event.
+ *
+ *		Some IR protocols like NEC have a special IR message for
+ *		repeating last button, for when a button is held down.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *	Return
+ *		0
+ *
+ * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded key press with *scancode*,
+ *		*toggle* value in the given *protocol*. The scancode will be
+ *		translated to a keycode using the rc keymap, and reported as
+ *		an input key down event. After a period a key up event is
+ *		generated. This period can be extended by calling either
+ *		**bpf_rc_keydown**\ () again with the same values, or calling
+ *		**bpf_rc_repeat**\ ().
+ *
+ *		Some protocols include a toggle bit, in case the button	was
+ *		released and pressed again between consecutive scancodes.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		The *protocol* is the decoded protocol number (see
+ *		**enum rc_proto** for some predefined values).
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *	Return
+ *		0
+ *
+ * u64 bpf_skb_cgroup_id(struct sk_buff *skb)
+ * 	Description
+ * 		Return the cgroup v2 id of the socket associated with the *skb*.
+ * 		This is roughly similar to the **bpf_get_cgroup_classid**\ ()
+ * 		helper for cgroup v1 by providing a tag resp. identifier that
+ * 		can be matched on or used for map lookups e.g. to implement
+ * 		policy. The cgroup v2 id of a given path in the hierarchy is
+ * 		exposed in user space through the f_handle API in order to get
+ * 		to the same 64-bit id.
+ *
+ * 		This helper can be used on TC egress path, but not on ingress,
+ * 		and is available only if the kernel was compiled with the
+ * 		**CONFIG_SOCK_CGROUP_DATA** configuration option.
+ * 	Return
+ * 		The id is returned or 0 in case the id could not be retrieved.
+ *
+ * u64 bpf_get_current_cgroup_id(void)
+ * 	Return
+ * 		A 64-bit integer containing the current cgroup id based
+ * 		on the cgroup within which the current task is running.
+ *
+ * void *bpf_get_local_storage(void *map, u64 flags)
+ *	Description
+ *		Get the pointer to the local storage area.
+ *		The type and the size of the local storage is defined
+ *		by the *map* argument.
+ *		The *flags* meaning is specific for each map type,
+ *		and has to be 0 for cgroup local storage.
+ *
+ *		Depending on the BPF program type, a local storage area
+ *		can be shared between multiple instances of the BPF program,
+ *		running simultaneously.
+ *
+ *		A user should care about the synchronization by himself.
+ *		For example, by using the **BPF_STX_XADD** instruction to alter
+ *		the shared data.
+ *	Return
+ *		A pointer to the local storage area.
+ *
+ * int bpf_sk_select_reuseport(struct sk_reuseport_md *reuse, struct bpf_map *map, void *key, u64 flags)
+ *	Description
+ *		Select a **SO_REUSEPORT** socket from a
+ *		**BPF_MAP_TYPE_REUSEPORT_ARRAY** *map*.
+ *		It checks the selected socket is matching the incoming
+ *		request in the socket buffer.
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)
+ *	Description
+ *		Return id of cgroup v2 that is ancestor of cgroup associated
+ *		with the *skb* at the *ancestor_level*.  The root cgroup is at
+ *		*ancestor_level* zero and each step down the hierarchy
+ *		increments the level. If *ancestor_level* == level of cgroup
+ *		associated with *skb*, then return value will be same as that
+ *		of **bpf_skb_cgroup_id**\ ().
+ *
+ *		The helper is useful to implement policies based on cgroups
+ *		that are upper in hierarchy than immediate cgroup associated
+ *		with *skb*.
+ *
+ *		The format of returned id and helper limitations are same as in
+ *		**bpf_skb_cgroup_id**\ ().
+ *	Return
+ *		The id is returned or 0 in case the id could not be retrieved.
+ *
+ * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
+ *	Description
+ *		Look for TCP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is a negative signed 32-bit integer, then the
+ *		socket lookup table in the netns associated with the *ctx* will
+ *		will be used. For the TC hooks, this is the netns of the device
+ *		in the skb. For socket hooks, this is the netns of the socket.
+ *		If *netns* is any other signed 32-bit value greater than or
+ *		equal to zero then it specifies the ID of the netns relative to
+ *		the netns associated with the *ctx*. *netns* values beyond the
+ *		range of 32-bit integers are reserved for future use.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ *		For sockets with reuseport option, the **struct bpf_sock**
+ *		result is from *reuse*\ **->socks**\ [] using the hash of the
+ *		tuple.
+ *
+ * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
+ *	Description
+ *		Look for UDP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ *		The *ctx* should point to the context of the program, such as
+ *		the skb or socket (depending on the hook in use). This is used
+ *		to determine the base network namespace for the lookup.
+ *
+ *		*tuple_size* must be one of:
+ *
+ *		**sizeof**\ (*tuple*\ **->ipv4**)
+ *			Look for an IPv4 socket.
+ *		**sizeof**\ (*tuple*\ **->ipv6**)
+ *			Look for an IPv6 socket.
+ *
+ *		If the *netns* is a negative signed 32-bit integer, then the
+ *		socket lookup table in the netns associated with the *ctx* will
+ *		will be used. For the TC hooks, this is the netns of the device
+ *		in the skb. For socket hooks, this is the netns of the socket.
+ *		If *netns* is any other signed 32-bit value greater than or
+ *		equal to zero then it specifies the ID of the netns relative to
+ *		the netns associated with the *ctx*. *netns* values beyond the
+ *		range of 32-bit integers are reserved for future use.
+ *
+ *		All values for *flags* are reserved for future usage, and must
+ *		be left at zero.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ *		For sockets with reuseport option, the **struct bpf_sock**
+ *		result is from *reuse*\ **->socks**\ [] using the hash of the
+ *		tuple.
+ *
+ * int bpf_sk_release(struct bpf_sock *sock)
+ *	Description
+ *		Release the reference held by *sock*. *sock* must be a
+ *		non-**NULL** pointer that was returned from
+ *		**bpf_sk_lookup_xxx**\ ().
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)
+ * 	Description
+ * 		Push an element *value* in *map*. *flags* is one of:
+ *
+ * 		**BPF_EXIST**
+ * 			If the queue/stack is full, the oldest element is
+ * 			removed to make room for this.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_map_pop_elem(struct bpf_map *map, void *value)
+ * 	Description
+ * 		Pop an element from *map*.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_map_peek_elem(struct bpf_map *map, void *value)
+ * 	Description
+ * 		Get an element from *map* without removing it.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_msg_push_data(struct sk_msg_buff *msg, u32 start, u32 len, u64 flags)
+ *	Description
+ *		For socket policies, insert *len* bytes into *msg* at offset
+ *		*start*.
+ *
+ *		If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
+ *		*msg* it may want to insert metadata or options into the *msg*.
+ *		This can later be read and used by any of the lower layer BPF
+ *		hooks.
+ *
+ *		This helper may fail if under memory pressure (a malloc
+ *		fails) in these cases BPF programs will get an appropriate
+ *		error and BPF programs will need to handle them.
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_msg_pop_data(struct sk_msg_buff *msg, u32 start, u32 len, u64 flags)
+ *	Description
+ *		Will remove *len* bytes from a *msg* starting at byte *start*.
+ *		This may result in **ENOMEM** errors under certain situations if
+ *		an allocation and copy are required due to a full ring buffer.
+ *		However, the helper will try to avoid doing the allocation
+ *		if possible. Other errors can occur if input parameters are
+ *		invalid either due to *start* byte not being valid part of *msg*
+ *		payload and/or *pop* value being to large.
+ *	Return
+ *		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_rc_pointer_rel(void *ctx, s32 rel_x, s32 rel_y)
+ *	Description
+ *		This helper is used in programs implementing IR decoding, to
+ *		report a successfully decoded pointer movement.
+ *
+ *		The *ctx* should point to the lirc sample as passed into
+ *		the program.
+ *
+ *		This helper is only available is the kernel was compiled with
+ *		the **CONFIG_BPF_LIRC_MODE2** configuration option set to
+ *		"**y**".
+ *	Return
+ *		0
+ *
+ * int bpf_spin_lock(struct bpf_spin_lock *lock)
+ *	Description
+ *		Acquire a spinlock represented by the pointer *lock*, which is
+ *		stored as part of a value of a map. Taking the lock allows to
+ *		safely update the rest of the fields in that value. The
+ *		spinlock can (and must) later be released with a call to
+ *		**bpf_spin_unlock**\ (\ *lock*\ ).
+ *
+ *		Spinlocks in BPF programs come with a number of restrictions
+ *		and constraints:
+ *
+ *		* **bpf_spin_lock** objects are only allowed inside maps of
+ *		  types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
+ *		  list could be extended in the future).
+ *		* BTF description of the map is mandatory.
+ *		* The BPF program can take ONE lock at a time, since taking two
+ *		  or more could cause dead locks.
+ *		* Only one **struct bpf_spin_lock** is allowed per map element.
+ *		* When the lock is taken, calls (either BPF to BPF or helpers)
+ *		  are not allowed.
+ *		* The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
+ *		  allowed inside a spinlock-ed region.
+ *		* The BPF program MUST call **bpf_spin_unlock**\ () to release
+ *		  the lock, on all execution paths, before it returns.
+ *		* The BPF program can access **struct bpf_spin_lock** only via
+ *		  the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
+ *		  helpers. Loading or storing data into the **struct
+ *		  bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
+ *		* To use the **bpf_spin_lock**\ () helper, the BTF description
+ *		  of the map value must be a struct and have **struct
+ *		  bpf_spin_lock** *anyname*\ **;** field at the top level.
+ *		  Nested lock inside another struct is not allowed.
+ *		* The **struct bpf_spin_lock** *lock* field in a map value must
+ *		  be aligned on a multiple of 4 bytes in that value.
+ *		* Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
+ *		  the **bpf_spin_lock** field to user space.
+ *		* Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
+ *		  a BPF program, do not update the **bpf_spin_lock** field.
+ *		* **bpf_spin_lock** cannot be on the stack or inside a
+ *		  networking packet (it can only be inside of a map values).
+ *		* **bpf_spin_lock** is available to root only.
+ *		* Tracing programs and socket filter programs cannot use
+ *		  **bpf_spin_lock**\ () due to insufficient preemption checks
+ *		  (but this may change in the future).
+ *		* **bpf_spin_lock** is not allowed in inner maps of map-in-map.
+ *	Return
+ *		0
+ *
+ * int bpf_spin_unlock(struct bpf_spin_lock *lock)
+ *	Description
+ *		Release the *lock* previously locked by a call to
+ *		**bpf_spin_lock**\ (\ *lock*\ ).
+ *	Return
+ *		0
+ *
+ * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)
+ *	Description
+ *		This helper gets a **struct bpf_sock** pointer such
+ *		that all the fields in this **bpf_sock** can be accessed.
+ *	Return
+ *		A **struct bpf_sock** pointer on success, or **NULL** in
+ *		case of failure.
+ *
+ * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)
+ *	Description
+ *		This helper gets a **struct bpf_tcp_sock** pointer from a
+ *		**struct bpf_sock** pointer.
+ *	Return
+ *		A **struct bpf_tcp_sock** pointer on success, or **NULL** in
+ *		case of failure.
+ *
+ * int bpf_skb_ecn_set_ce(struct sk_buff *skb)
+ *	Description
+ *		Set ECN (Explicit Congestion Notification) field of IP header
+ *		to **CE** (Congestion Encountered) if current value is **ECT**
+ *		(ECN Capable Transport). Otherwise, do nothing. Works with IPv6
+ *		and IPv4.
+ *	Return
+ *		1 if the **CE** flag is set (either by the current helper call
+ *		or because it was already present), 0 if it is not set.
+ *
+ * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)
+ *	Description
+ *		Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
+ *		**bpf_sk_release**\ () is unnecessary and not allowed.
+ *	Return
+ *		A **struct bpf_sock** pointer on success, or **NULL** in
+ *		case of failure.
+ *
+ * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
+ *	Description
+ *		Look for TCP socket matching *tuple*, optionally in a child
+ *		network namespace *netns*. The return value must be checked,
+ *		and if non-**NULL**, released via **bpf_sk_release**\ ().
+ *
+ *		This function is identical to **bpf_sk_lookup_tcp**\ (), except
+ *		that it also returns timewait or request sockets. Use
+ *		**bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
+ *		full structure.
+ *
+ *		This helper is available only if the kernel was compiled with
+ *		**CONFIG_NET** configuration option.
+ *	Return
+ *		Pointer to **struct bpf_sock**, or **NULL** in case of failure.
+ *		For sockets with reuseport option, the **struct bpf_sock**
+ *		result is from *reuse*\ **->socks**\ [] using the hash of the
+ *		tuple.
+ *
+ * int bpf_tcp_check_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
+ * 	Description
+ * 		Check whether *iph* and *th* contain a valid SYN cookie ACK for
+ * 		the listening socket in *sk*.
+ *
+ * 		*iph* points to the start of the IPv4 or IPv6 header, while
+ * 		*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ * 		**sizeof**\ (**struct ip6hdr**).
+ *
+ * 		*th* points to the start of the TCP header, while *th_len*
+ * 		contains **sizeof**\ (**struct tcphdr**).
+ *
+ * 	Return
+ * 		0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
+ * 		error otherwise.
+ *
+ * int bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags)
+ *	Description
+ *		Get name of sysctl in /proc/sys/ and copy it into provided by
+ *		program buffer *buf* of size *buf_len*.
+ *
+ *		The buffer is always NUL terminated, unless it's zero-sized.
+ *
+ *		If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
+ *		copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
+ *		only (e.g. "tcp_mem").
+ *	Return
+ *		Number of character copied (not including the trailing NUL).
+ *
+ *		**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ *		truncated name in this case).
+ *
+ * int bpf_sysctl_get_current_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
+ *	Description
+ *		Get current value of sysctl as it is presented in /proc/sys
+ *		(incl. newline, etc), and copy it as a string into provided
+ *		by program buffer *buf* of size *buf_len*.
+ *
+ *		The whole value is copied, no matter what file position user
+ *		space issued e.g. sys_read at.
+ *
+ *		The buffer is always NUL terminated, unless it's zero-sized.
+ *	Return
+ *		Number of character copied (not including the trailing NUL).
+ *
+ *		**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ *		truncated name in this case).
+ *
+ *		**-EINVAL** if current value was unavailable, e.g. because
+ *		sysctl is uninitialized and read returns -EIO for it.
+ *
+ * int bpf_sysctl_get_new_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
+ *	Description
+ *		Get new value being written by user space to sysctl (before
+ *		the actual write happens) and copy it as a string into
+ *		provided by program buffer *buf* of size *buf_len*.
+ *
+ *		User space may write new value at file position > 0.
+ *
+ *		The buffer is always NUL terminated, unless it's zero-sized.
+ *	Return
+ *		Number of character copied (not including the trailing NUL).
+ *
+ *		**-E2BIG** if the buffer wasn't big enough (*buf* will contain
+ *		truncated name in this case).
+ *
+ *		**-EINVAL** if sysctl is being read.
+ *
+ * int bpf_sysctl_set_new_value(struct bpf_sysctl *ctx, const char *buf, size_t buf_len)
+ *	Description
+ *		Override new value being written by user space to sysctl with
+ *		value provided by program in buffer *buf* of size *buf_len*.
+ *
+ *		*buf* should contain a string in same form as provided by user
+ *		space on sysctl write.
+ *
+ *		User space may write new value at file position > 0. To override
+ *		the whole sysctl value file position should be set to zero.
+ *	Return
+ *		0 on success.
+ *
+ *		**-E2BIG** if the *buf_len* is too big.
+ *
+ *		**-EINVAL** if sysctl is being read.
+ *
+ * int bpf_strtol(const char *buf, size_t buf_len, u64 flags, long *res)
+ *	Description
+ *		Convert the initial part of the string from buffer *buf* of
+ *		size *buf_len* to a long integer according to the given base
+ *		and save the result in *res*.
+ *
+ *		The string may begin with an arbitrary amount of white space
+ *		(as determined by **isspace**\ (3)) followed by a single
+ *		optional '**-**' sign.
+ *
+ *		Five least significant bits of *flags* encode base, other bits
+ *		are currently unused.
+ *
+ *		Base must be either 8, 10, 16 or 0 to detect it automatically
+ *		similar to user space **strtol**\ (3).
+ *	Return
+ *		Number of characters consumed on success. Must be positive but
+ *		no more than *buf_len*.
+ *
+ *		**-EINVAL** if no valid digits were found or unsupported base
+ *		was provided.
+ *
+ *		**-ERANGE** if resulting value was out of range.
+ *
+ * int bpf_strtoul(const char *buf, size_t buf_len, u64 flags, unsigned long *res)
+ *	Description
+ *		Convert the initial part of the string from buffer *buf* of
+ *		size *buf_len* to an unsigned long integer according to the
+ *		given base and save the result in *res*.
+ *
+ *		The string may begin with an arbitrary amount of white space
+ *		(as determined by **isspace**\ (3)).
+ *
+ *		Five least significant bits of *flags* encode base, other bits
+ *		are currently unused.
+ *
+ *		Base must be either 8, 10, 16 or 0 to detect it automatically
+ *		similar to user space **strtoul**\ (3).
+ *	Return
+ *		Number of characters consumed on success. Must be positive but
+ *		no more than *buf_len*.
+ *
+ *		**-EINVAL** if no valid digits were found or unsupported base
+ *		was provided.
+ *
+ *		**-ERANGE** if resulting value was out of range.
+ *
+ * void *bpf_sk_storage_get(struct bpf_map *map, struct bpf_sock *sk, void *value, u64 flags)
+ *	Description
+ *		Get a bpf-local-storage from a *sk*.
+ *
+ *		Logically, it could be thought of getting the value from
+ *		a *map* with *sk* as the **key**.  From this
+ *		perspective,  the usage is not much different from
+ *		**bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
+ *		helper enforces the key must be a full socket and the map must
+ *		be a **BPF_MAP_TYPE_SK_STORAGE** also.
+ *
+ *		Underneath, the value is stored locally at *sk* instead of
+ *		the *map*.  The *map* is used as the bpf-local-storage
+ *		"type". The bpf-local-storage "type" (i.e. the *map*) is
+ *		searched against all bpf-local-storages residing at *sk*.
+ *
+ *		An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
+ *		used such that a new bpf-local-storage will be
+ *		created if one does not exist.  *value* can be used
+ *		together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
+ *		the initial value of a bpf-local-storage.  If *value* is
+ *		**NULL**, the new bpf-local-storage will be zero initialized.
+ *	Return
+ *		A bpf-local-storage pointer is returned on success.
+ *
+ *		**NULL** if not found or there was an error in adding
+ *		a new bpf-local-storage.
+ *
+ * int bpf_sk_storage_delete(struct bpf_map *map, struct bpf_sock *sk)
+ *	Description
+ *		Delete a bpf-local-storage from a *sk*.
+ *	Return
+ *		0 on success.
+ *
+ *		**-ENOENT** if the bpf-local-storage cannot be found.
+ *
+ * int bpf_send_signal(u32 sig)
+ *	Description
+ *		Send signal *sig* to the current task.
+ *	Return
+ *		0 on success or successfully queued.
+ *
+ *		**-EBUSY** if work queue under nmi is full.
+ *
+ *		**-EINVAL** if *sig* is invalid.
+ *
+ *		**-EPERM** if no permission to send the *sig*.
+ *
+ *		**-EAGAIN** if bpf program can try again.
+ *
+ * s64 bpf_tcp_gen_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
+ *	Description
+ *		Try to issue a SYN cookie for the packet with corresponding
+ *		IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
+ *
+ *		*iph* points to the start of the IPv4 or IPv6 header, while
+ *		*iph_len* contains **sizeof**\ (**struct iphdr**) or
+ *		**sizeof**\ (**struct ip6hdr**).
+ *
+ *		*th* points to the start of the TCP header, while *th_len*
+ *		contains the length of the TCP header.
+ *
+ *	Return
+ *		On success, lower 32 bits hold the generated SYN cookie in
+ *		followed by 16 bits which hold the MSS value for that cookie,
+ *		and the top 16 bits are unused.
+ *
+ *		On failure, the returned value is one of the following:
+ *
+ *		**-EINVAL** SYN cookie cannot be issued due to error
+ *
+ *		**-ENOENT** SYN cookie should not be issued (no SYN flood)
+ *
+ *		**-EOPNOTSUPP** kernel configuration does not enable SYN cookies
+ *
+ *		**-EPROTONOSUPPORT** IP packet version is not 4 or 6
+ *
+ * int bpf_skb_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
+ * 	Description
+ * 		Write raw *data* blob into a special BPF perf event held by
+ * 		*map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
+ * 		event must have the following attributes: **PERF_SAMPLE_RAW**
+ * 		as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
+ * 		**PERF_COUNT_SW_BPF_OUTPUT** as **config**.
+ *
+ * 		The *flags* are used to indicate the index in *map* for which
+ * 		the value must be put, masked with **BPF_F_INDEX_MASK**.
+ * 		Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
+ * 		to indicate that the index of the current CPU core should be
+ * 		used.
+ *
+ * 		The value to write, of *size*, is passed through eBPF stack and
+ * 		pointed by *data*.
+ *
+ * 		*ctx* is a pointer to in-kernel struct sk_buff.
+ *
+ * 		This helper is similar to **bpf_perf_event_output**\ () but
+ * 		restricted to raw_tracepoint bpf programs.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_probe_read_user(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		Safely attempt to read *size* bytes from user space address
+ * 		*unsafe_ptr* and store the data in *dst*.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		Safely attempt to read *size* bytes from kernel space address
+ * 		*unsafe_ptr* and store the data in *dst*.
+ * 	Return
+ * 		0 on success, or a negative error in case of failure.
+ *
+ * int bpf_probe_read_user_str(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		Copy a NUL terminated string from an unsafe user address
+ * 		*unsafe_ptr* to *dst*. The *size* should include the
+ * 		terminating NUL byte. In case the string length is smaller than
+ * 		*size*, the target is not padded with further NUL bytes. If the
+ * 		string length is larger than *size*, just *size*-1 bytes are
+ * 		copied and the last byte is set to NUL.
+ *
+ * 		On success, the length of the copied string is returned. This
+ * 		makes this helper useful in tracing programs for reading
+ * 		strings, and more importantly to get its length at runtime. See
+ * 		the following snippet:
+ *
+ * 		::
+ *
+ * 			SEC("kprobe/sys_open")
+ * 			void bpf_sys_open(struct pt_regs *ctx)
+ * 			{
+ * 			        char buf[PATHLEN]; // PATHLEN is defined to 256
+ * 			        int res = bpf_probe_read_user_str(buf, sizeof(buf),
+ * 				                                  ctx->di);
+ *
+ * 				// Consume buf, for example push it to
+ * 				// userspace via bpf_perf_event_output(); we
+ * 				// can use res (the string length) as event
+ * 				// size, after checking its boundaries.
+ * 			}
+ *
+ * 		In comparison, using **bpf_probe_read_user()** helper here
+ * 		instead to read the string would require to estimate the length
+ * 		at compile time, and would often result in copying more memory
+ * 		than necessary.
+ *
+ * 		Another useful use case is when parsing individual process
+ * 		arguments or individual environment variables navigating
+ * 		*current*\ **->mm->arg_start** and *current*\
+ * 		**->mm->env_start**: using this helper and the return value,
+ * 		one can quickly iterate at the right offset of the memory area.
+ * 	Return
+ * 		On success, the strictly positive length of the string,
+ * 		including the trailing NUL character. On error, a negative
+ * 		value.
+ *
+ * int bpf_probe_read_kernel_str(void *dst, u32 size, const void *unsafe_ptr)
+ * 	Description
+ * 		Copy a NUL terminated string from an unsafe kernel address *unsafe_ptr*
+ * 		to *dst*. Same semantics as with bpf_probe_read_user_str() apply.
+ * 	Return
+ * 		On success, the strictly positive length of the string,	including
+ * 		the trailing NUL character. On error, a negative value.
+ */
+#define __BPF_FUNC_MAPPER(FN)		\
+	FN(unspec),			\
+	FN(map_lookup_elem),		\
+	FN(map_update_elem),		\
+	FN(map_delete_elem),		\
+	FN(probe_read),			\
+	FN(ktime_get_ns),		\
+	FN(trace_printk),		\
+	FN(get_prandom_u32),		\
+	FN(get_smp_processor_id),	\
+	FN(skb_store_bytes),		\
+	FN(l3_csum_replace),		\
+	FN(l4_csum_replace),		\
+	FN(tail_call),			\
+	FN(clone_redirect),		\
+	FN(get_current_pid_tgid),	\
+	FN(get_current_uid_gid),	\
+	FN(get_current_comm),		\
+	FN(get_cgroup_classid),		\
+	FN(skb_vlan_push),		\
+	FN(skb_vlan_pop),		\
+	FN(skb_get_tunnel_key),		\
+	FN(skb_set_tunnel_key),		\
+	FN(perf_event_read),		\
+	FN(redirect),			\
+	FN(get_route_realm),		\
+	FN(perf_event_output),		\
+	FN(skb_load_bytes),		\
+	FN(get_stackid),		\
+	FN(csum_diff),			\
+	FN(skb_get_tunnel_opt),		\
+	FN(skb_set_tunnel_opt),		\
+	FN(skb_change_proto),		\
+	FN(skb_change_type),		\
+	FN(skb_under_cgroup),		\
+	FN(get_hash_recalc),		\
+	FN(get_current_task),		\
+	FN(probe_write_user),		\
+	FN(current_task_under_cgroup),	\
+	FN(skb_change_tail),		\
+	FN(skb_pull_data),		\
+	FN(csum_update),		\
+	FN(set_hash_invalid),		\
+	FN(get_numa_node_id),		\
+	FN(skb_change_head),		\
+	FN(xdp_adjust_head),		\
+	FN(probe_read_str),		\
+	FN(get_socket_cookie),		\
+	FN(get_socket_uid),		\
+	FN(set_hash),			\
+	FN(setsockopt),			\
+	FN(skb_adjust_room),		\
+	FN(redirect_map),		\
+	FN(sk_redirect_map),		\
+	FN(sock_map_update),		\
+	FN(xdp_adjust_meta),		\
+	FN(perf_event_read_value),	\
+	FN(perf_prog_read_value),	\
+	FN(getsockopt),			\
+	FN(override_return),		\
+	FN(sock_ops_cb_flags_set),	\
+	FN(msg_redirect_map),		\
+	FN(msg_apply_bytes),		\
+	FN(msg_cork_bytes),		\
+	FN(msg_pull_data),		\
+	FN(bind),			\
+	FN(xdp_adjust_tail),		\
+	FN(skb_get_xfrm_state),		\
+	FN(get_stack),			\
+	FN(skb_load_bytes_relative),	\
+	FN(fib_lookup),			\
+	FN(sock_hash_update),		\
+	FN(msg_redirect_hash),		\
+	FN(sk_redirect_hash),		\
+	FN(lwt_push_encap),		\
+	FN(lwt_seg6_store_bytes),	\
+	FN(lwt_seg6_adjust_srh),	\
+	FN(lwt_seg6_action),		\
+	FN(rc_repeat),			\
+	FN(rc_keydown),			\
+	FN(skb_cgroup_id),		\
+	FN(get_current_cgroup_id),	\
+	FN(get_local_storage),		\
+	FN(sk_select_reuseport),	\
+	FN(skb_ancestor_cgroup_id),	\
+	FN(sk_lookup_tcp),		\
+	FN(sk_lookup_udp),		\
+	FN(sk_release),			\
+	FN(map_push_elem),		\
+	FN(map_pop_elem),		\
+	FN(map_peek_elem),		\
+	FN(msg_push_data),		\
+	FN(msg_pop_data),		\
+	FN(rc_pointer_rel),		\
+	FN(spin_lock),			\
+	FN(spin_unlock),		\
+	FN(sk_fullsock),		\
+	FN(tcp_sock),			\
+	FN(skb_ecn_set_ce),		\
+	FN(get_listener_sock),		\
+	FN(skc_lookup_tcp),		\
+	FN(tcp_check_syncookie),	\
+	FN(sysctl_get_name),		\
+	FN(sysctl_get_current_value),	\
+	FN(sysctl_get_new_value),	\
+	FN(sysctl_set_new_value),	\
+	FN(strtol),			\
+	FN(strtoul),			\
+	FN(sk_storage_get),		\
+	FN(sk_storage_delete),		\
+	FN(send_signal),		\
+	FN(tcp_gen_syncookie),		\
+	FN(skb_output),			\
+	FN(probe_read_user),		\
+	FN(probe_read_kernel),		\
+	FN(probe_read_user_str),	\
+	FN(probe_read_kernel_str),
+
+/* integer value in 'imm' field of BPF_CALL instruction selects which helper
+ * function eBPF program intends to call
+ */
+#define __BPF_ENUM_FN(x) BPF_FUNC_ ## x
+enum bpf_func_id {
+	__BPF_FUNC_MAPPER(__BPF_ENUM_FN)
+	__BPF_FUNC_MAX_ID,
+};
+#undef __BPF_ENUM_FN
+
+/* All flags used by eBPF helper functions, placed here. */
+
+/* BPF_FUNC_skb_store_bytes flags. */
+#define BPF_F_RECOMPUTE_CSUM		(1ULL << 0)
+#define BPF_F_INVALIDATE_HASH		(1ULL << 1)
+
+/* BPF_FUNC_l3_csum_replace and BPF_FUNC_l4_csum_replace flags.
+ * First 4 bits are for passing the header field size.
+ */
+#define BPF_F_HDR_FIELD_MASK		0xfULL
+
+/* BPF_FUNC_l4_csum_replace flags. */
+#define BPF_F_PSEUDO_HDR		(1ULL << 4)
+#define BPF_F_MARK_MANGLED_0		(1ULL << 5)
+#define BPF_F_MARK_ENFORCE		(1ULL << 6)
+
+/* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */
+#define BPF_F_INGRESS			(1ULL << 0)
+
+/* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
+#define BPF_F_TUNINFO_IPV6		(1ULL << 0)
+
+/* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
+#define BPF_F_SKIP_FIELD_MASK		0xffULL
+#define BPF_F_USER_STACK		(1ULL << 8)
+/* flags used by BPF_FUNC_get_stackid only. */
+#define BPF_F_FAST_STACK_CMP		(1ULL << 9)
+#define BPF_F_REUSE_STACKID		(1ULL << 10)
+/* flags used by BPF_FUNC_get_stack only. */
+#define BPF_F_USER_BUILD_ID		(1ULL << 11)
+
+/* BPF_FUNC_skb_set_tunnel_key flags. */
+#define BPF_F_ZERO_CSUM_TX		(1ULL << 1)
+#define BPF_F_DONT_FRAGMENT		(1ULL << 2)
+#define BPF_F_SEQ_NUMBER		(1ULL << 3)
+
+/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
+ * BPF_FUNC_perf_event_read_value flags.
+ */
+#define BPF_F_INDEX_MASK		0xffffffffULL
+#define BPF_F_CURRENT_CPU		BPF_F_INDEX_MASK
+/* BPF_FUNC_perf_event_output for sk_buff input context. */
+#define BPF_F_CTXLEN_MASK		(0xfffffULL << 32)
+
+/* Current network namespace */
+#define BPF_F_CURRENT_NETNS		(-1L)
+
+/* BPF_FUNC_skb_adjust_room flags. */
+#define BPF_F_ADJ_ROOM_FIXED_GSO	(1ULL << 0)
+
+#define BPF_ADJ_ROOM_ENCAP_L2_MASK	0xff
+#define BPF_ADJ_ROOM_ENCAP_L2_SHIFT	56
+
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4	(1ULL << 1)
+#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6	(1ULL << 2)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE	(1ULL << 3)
+#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP	(1ULL << 4)
+#define BPF_F_ADJ_ROOM_ENCAP_L2(len)	(((__u64)len & \
+					  BPF_ADJ_ROOM_ENCAP_L2_MASK) \
+					 << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)
+
+/* BPF_FUNC_sysctl_get_name flags. */
+#define BPF_F_SYSCTL_BASE_NAME		(1ULL << 0)
+
+/* BPF_FUNC_sk_storage_get flags */
+#define BPF_SK_STORAGE_GET_F_CREATE	(1ULL << 0)
+
+/* Mode for BPF_FUNC_skb_adjust_room helper. */
+enum bpf_adj_room_mode {
+	BPF_ADJ_ROOM_NET,
+	BPF_ADJ_ROOM_MAC,
+};
+
+/* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
+enum bpf_hdr_start_off {
+	BPF_HDR_START_MAC,
+	BPF_HDR_START_NET,
+};
+
+/* Encapsulation type for BPF_FUNC_lwt_push_encap helper. */
+enum bpf_lwt_encap_mode {
+	BPF_LWT_ENCAP_SEG6,
+	BPF_LWT_ENCAP_SEG6_INLINE,
+	BPF_LWT_ENCAP_IP,
+};
+
+#define __bpf_md_ptr(type, name)	\
+union {					\
+	type name;			\
+	__u64 :64;			\
+} __attribute__((aligned(8)))
+
+/* user accessible mirror of in-kernel sk_buff.
+ * new fields can only be added to the end of this structure
+ */
+struct __sk_buff {
+	__u32 len;
+	__u32 pkt_type;
+	__u32 mark;
+	__u32 queue_mapping;
+	__u32 protocol;
+	__u32 vlan_present;
+	__u32 vlan_tci;
+	__u32 vlan_proto;
+	__u32 priority;
+	__u32 ingress_ifindex;
+	__u32 ifindex;
+	__u32 tc_index;
+	__u32 cb[5];
+	__u32 hash;
+	__u32 tc_classid;
+	__u32 data;
+	__u32 data_end;
+	__u32 napi_id;
+
+	/* Accessed by BPF_PROG_TYPE_sk_skb types from here to ... */
+	__u32 family;
+	__u32 remote_ip4;	/* Stored in network byte order */
+	__u32 local_ip4;	/* Stored in network byte order */
+	__u32 remote_ip6[4];	/* Stored in network byte order */
+	__u32 local_ip6[4];	/* Stored in network byte order */
+	__u32 remote_port;	/* Stored in network byte order */
+	__u32 local_port;	/* stored in host byte order */
+	/* ... here. */
+
+	__u32 data_meta;
+	__bpf_md_ptr(struct bpf_flow_keys *, flow_keys);
+	__u64 tstamp;
+	__u32 wire_len;
+	__u32 gso_segs;
+	__bpf_md_ptr(struct bpf_sock *, sk);
+};
+
+struct bpf_tunnel_key {
+	__u32 tunnel_id;
+	union {
+		__u32 remote_ipv4;
+		__u32 remote_ipv6[4];
+	};
+	__u8 tunnel_tos;
+	__u8 tunnel_ttl;
+	__u16 tunnel_ext;	/* Padding, future use. */
+	__u32 tunnel_label;
+};
+
+/* user accessible mirror of in-kernel xfrm_state.
+ * new fields can only be added to the end of this structure
+ */
+struct bpf_xfrm_state {
+	__u32 reqid;
+	__u32 spi;	/* Stored in network byte order */
+	__u16 family;
+	__u16 ext;	/* Padding, future use. */
+	union {
+		__u32 remote_ipv4;	/* Stored in network byte order */
+		__u32 remote_ipv6[4];	/* Stored in network byte order */
+	};
+};
+
+/* Generic BPF return codes which all BPF program types may support.
+ * The values are binary compatible with their TC_ACT_* counter-part to
+ * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT
+ * programs.
+ *
+ * XDP is handled seprately, see XDP_*.
+ */
+enum bpf_ret_code {
+	BPF_OK = 0,
+	/* 1 reserved */
+	BPF_DROP = 2,
+	/* 3-6 reserved */
+	BPF_REDIRECT = 7,
+	/* >127 are reserved for prog type specific return codes.
+	 *
+	 * BPF_LWT_REROUTE: used by BPF_PROG_TYPE_LWT_IN and
+	 *    BPF_PROG_TYPE_LWT_XMIT to indicate that skb had been
+	 *    changed and should be routed based on its new L3 header.
+	 *    (This is an L3 redirect, as opposed to L2 redirect
+	 *    represented by BPF_REDIRECT above).
+	 */
+	BPF_LWT_REROUTE = 128,
+};
+
+struct bpf_sock {
+	__u32 bound_dev_if;
+	__u32 family;
+	__u32 type;
+	__u32 protocol;
+	__u32 mark;
+	__u32 priority;
+	/* IP address also allows 1 and 2 bytes access */
+	__u32 src_ip4;
+	__u32 src_ip6[4];
+	__u32 src_port;		/* host byte order */
+	__u32 dst_port;		/* network byte order */
+	__u32 dst_ip4;
+	__u32 dst_ip6[4];
+	__u32 state;
+};
+
+struct bpf_tcp_sock {
+	__u32 snd_cwnd;		/* Sending congestion window		*/
+	__u32 srtt_us;		/* smoothed round trip time << 3 in usecs */
+	__u32 rtt_min;
+	__u32 snd_ssthresh;	/* Slow start size threshold		*/
+	__u32 rcv_nxt;		/* What we want to receive next		*/
+	__u32 snd_nxt;		/* Next sequence we send		*/
+	__u32 snd_una;		/* First byte we want an ack for	*/
+	__u32 mss_cache;	/* Cached effective mss, not including SACKS */
+	__u32 ecn_flags;	/* ECN status bits.			*/
+	__u32 rate_delivered;	/* saved rate sample: packets delivered */
+	__u32 rate_interval_us;	/* saved rate sample: time elapsed */
+	__u32 packets_out;	/* Packets which are "in flight"	*/
+	__u32 retrans_out;	/* Retransmitted packets out		*/
+	__u32 total_retrans;	/* Total retransmits for entire connection */
+	__u32 segs_in;		/* RFC4898 tcpEStatsPerfSegsIn
+				 * total number of segments in.
+				 */
+	__u32 data_segs_in;	/* RFC4898 tcpEStatsPerfDataSegsIn
+				 * total number of data segments in.
+				 */
+	__u32 segs_out;		/* RFC4898 tcpEStatsPerfSegsOut
+				 * The total number of segments sent.
+				 */
+	__u32 data_segs_out;	/* RFC4898 tcpEStatsPerfDataSegsOut
+				 * total number of data segments sent.
+				 */
+	__u32 lost_out;		/* Lost packets			*/
+	__u32 sacked_out;	/* SACK'd packets			*/
+	__u64 bytes_received;	/* RFC4898 tcpEStatsAppHCThruOctetsReceived
+				 * sum(delta(rcv_nxt)), or how many bytes
+				 * were acked.
+				 */
+	__u64 bytes_acked;	/* RFC4898 tcpEStatsAppHCThruOctetsAcked
+				 * sum(delta(snd_una)), or how many bytes
+				 * were acked.
+				 */
+	__u32 dsack_dups;	/* RFC4898 tcpEStatsStackDSACKDups
+				 * total number of DSACK blocks received
+				 */
+	__u32 delivered;	/* Total data packets delivered incl. rexmits */
+	__u32 delivered_ce;	/* Like the above but only ECE marked packets */
+	__u32 icsk_retransmits;	/* Number of unrecovered [RTO] timeouts */
+};
+
+struct bpf_sock_tuple {
+	union {
+		struct {
+			__be32 saddr;
+			__be32 daddr;
+			__be16 sport;
+			__be16 dport;
+		} ipv4;
+		struct {
+			__be32 saddr[4];
+			__be32 daddr[4];
+			__be16 sport;
+			__be16 dport;
+		} ipv6;
+	};
+};
+
+struct bpf_xdp_sock {
+	__u32 queue_id;
+};
+
+#define XDP_PACKET_HEADROOM 256
+
+/* User return codes for XDP prog type.
+ * A valid XDP program must return one of these defined values. All other
+ * return codes are reserved for future use. Unknown return codes will
+ * result in packet drops and a warning via bpf_warn_invalid_xdp_action().
+ */
+enum xdp_action {
+	XDP_ABORTED = 0,
+	XDP_DROP,
+	XDP_PASS,
+	XDP_TX,
+	XDP_REDIRECT,
+};
+
+/* user accessible metadata for XDP packet hook
+ * new fields must be added to the end of this structure
+ */
+struct xdp_md {
+	__u32 data;
+	__u32 data_end;
+	__u32 data_meta;
+	/* Below access go through struct xdp_rxq_info */
+	__u32 ingress_ifindex; /* rxq->dev->ifindex */
+	__u32 rx_queue_index;  /* rxq->queue_index  */
+};
+
+enum sk_action {
+	SK_DROP = 0,
+	SK_PASS,
+};
+
+/* user accessible metadata for SK_MSG packet hook, new fields must
+ * be added to the end of this structure
+ */
+struct sk_msg_md {
+	__bpf_md_ptr(void *, data);
+	__bpf_md_ptr(void *, data_end);
+
+	__u32 family;
+	__u32 remote_ip4;	/* Stored in network byte order */
+	__u32 local_ip4;	/* Stored in network byte order */
+	__u32 remote_ip6[4];	/* Stored in network byte order */
+	__u32 local_ip6[4];	/* Stored in network byte order */
+	__u32 remote_port;	/* Stored in network byte order */
+	__u32 local_port;	/* stored in host byte order */
+	__u32 size;		/* Total size of sk_msg */
+};
+
+struct sk_reuseport_md {
+	/*
+	 * Start of directly accessible data. It begins from
+	 * the tcp/udp header.
+	 */
+	__bpf_md_ptr(void *, data);
+	/* End of directly accessible data */
+	__bpf_md_ptr(void *, data_end);
+	/*
+	 * Total length of packet (starting from the tcp/udp header).
+	 * Note that the directly accessible bytes (data_end - data)
+	 * could be less than this "len".  Those bytes could be
+	 * indirectly read by a helper "bpf_skb_load_bytes()".
+	 */
+	__u32 len;
+	/*
+	 * Eth protocol in the mac header (network byte order). e.g.
+	 * ETH_P_IP(0x0800) and ETH_P_IPV6(0x86DD)
+	 */
+	__u32 eth_protocol;
+	__u32 ip_protocol;	/* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
+	__u32 bind_inany;	/* Is sock bound to an INANY address? */
+	__u32 hash;		/* A hash of the packet 4 tuples */
+};
+
+#define BPF_TAG_SIZE	8
+
+struct bpf_prog_info {
+	__u32 type;
+	__u32 id;
+	__u8  tag[BPF_TAG_SIZE];
+	__u32 jited_prog_len;
+	__u32 xlated_prog_len;
+	__aligned_u64 jited_prog_insns;
+	__aligned_u64 xlated_prog_insns;
+	__u64 load_time;	/* ns since boottime */
+	__u32 created_by_uid;
+	__u32 nr_map_ids;
+	__aligned_u64 map_ids;
+	char name[BPF_OBJ_NAME_LEN];
+	__u32 ifindex;
+	__u32 gpl_compatible:1;
+	__u32 :31; /* alignment pad */
+	__u64 netns_dev;
+	__u64 netns_ino;
+	__u32 nr_jited_ksyms;
+	__u32 nr_jited_func_lens;
+	__aligned_u64 jited_ksyms;
+	__aligned_u64 jited_func_lens;
+	__u32 btf_id;
+	__u32 func_info_rec_size;
+	__aligned_u64 func_info;
+	__u32 nr_func_info;
+	__u32 nr_line_info;
+	__aligned_u64 line_info;
+	__aligned_u64 jited_line_info;
+	__u32 nr_jited_line_info;
+	__u32 line_info_rec_size;
+	__u32 jited_line_info_rec_size;
+	__u32 nr_prog_tags;
+	__aligned_u64 prog_tags;
+	__u64 run_time_ns;
+	__u64 run_cnt;
+} __attribute__((aligned(8)));
+
+struct bpf_map_info {
+	__u32 type;
+	__u32 id;
+	__u32 key_size;
+	__u32 value_size;
+	__u32 max_entries;
+	__u32 map_flags;
+	char  name[BPF_OBJ_NAME_LEN];
+	__u32 ifindex;
+	__u32 :32;
+	__u64 netns_dev;
+	__u64 netns_ino;
+	__u32 btf_id;
+	__u32 btf_key_type_id;
+	__u32 btf_value_type_id;
+} __attribute__((aligned(8)));
+
+struct bpf_btf_info {
+	__aligned_u64 btf;
+	__u32 btf_size;
+	__u32 id;
+} __attribute__((aligned(8)));
+
+/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
+ * by user and intended to be used by socket (e.g. to bind to, depends on
+ * attach attach type).
+ */
+struct bpf_sock_addr {
+	__u32 user_family;	/* Allows 4-byte read, but no write. */
+	__u32 user_ip4;		/* Allows 1,2,4-byte read and 4-byte write.
+				 * Stored in network byte order.
+				 */
+	__u32 user_ip6[4];	/* Allows 1,2,4,8-byte read and 4,8-byte write.
+				 * Stored in network byte order.
+				 */
+	__u32 user_port;	/* Allows 4-byte read and write.
+				 * Stored in network byte order
+				 */
+	__u32 family;		/* Allows 4-byte read, but no write */
+	__u32 type;		/* Allows 4-byte read, but no write */
+	__u32 protocol;		/* Allows 4-byte read, but no write */
+	__u32 msg_src_ip4;	/* Allows 1,2,4-byte read and 4-byte write.
+				 * Stored in network byte order.
+				 */
+	__u32 msg_src_ip6[4];	/* Allows 1,2,4,8-byte read and 4,8-byte write.
+				 * Stored in network byte order.
+				 */
+	__bpf_md_ptr(struct bpf_sock *, sk);
+};
+
+/* User bpf_sock_ops struct to access socket values and specify request ops
+ * and their replies.
+ * Some of this fields are in network (bigendian) byte order and may need
+ * to be converted before use (bpf_ntohl() defined in samples/bpf/bpf_endian.h).
+ * New fields can only be added at the end of this structure
+ */
+struct bpf_sock_ops {
+	__u32 op;
+	union {
+		__u32 args[4];		/* Optionally passed to bpf program */
+		__u32 reply;		/* Returned by bpf program	    */
+		__u32 replylong[4];	/* Optionally returned by bpf prog  */
+	};
+	__u32 family;
+	__u32 remote_ip4;	/* Stored in network byte order */
+	__u32 local_ip4;	/* Stored in network byte order */
+	__u32 remote_ip6[4];	/* Stored in network byte order */
+	__u32 local_ip6[4];	/* Stored in network byte order */
+	__u32 remote_port;	/* Stored in network byte order */
+	__u32 local_port;	/* stored in host byte order */
+	__u32 is_fullsock;	/* Some TCP fields are only valid if
+				 * there is a full socket. If not, the
+				 * fields read as zero.
+				 */
+	__u32 snd_cwnd;
+	__u32 srtt_us;		/* Averaged RTT << 3 in usecs */
+	__u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
+	__u32 state;
+	__u32 rtt_min;
+	__u32 snd_ssthresh;
+	__u32 rcv_nxt;
+	__u32 snd_nxt;
+	__u32 snd_una;
+	__u32 mss_cache;
+	__u32 ecn_flags;
+	__u32 rate_delivered;
+	__u32 rate_interval_us;
+	__u32 packets_out;
+	__u32 retrans_out;
+	__u32 total_retrans;
+	__u32 segs_in;
+	__u32 data_segs_in;
+	__u32 segs_out;
+	__u32 data_segs_out;
+	__u32 lost_out;
+	__u32 sacked_out;
+	__u32 sk_txhash;
+	__u64 bytes_received;
+	__u64 bytes_acked;
+	__bpf_md_ptr(struct bpf_sock *, sk);
+};
+
+/* Definitions for bpf_sock_ops_cb_flags */
+#define BPF_SOCK_OPS_RTO_CB_FLAG	(1<<0)
+#define BPF_SOCK_OPS_RETRANS_CB_FLAG	(1<<1)
+#define BPF_SOCK_OPS_STATE_CB_FLAG	(1<<2)
+#define BPF_SOCK_OPS_RTT_CB_FLAG	(1<<3)
+#define BPF_SOCK_OPS_ALL_CB_FLAGS       0xF		/* Mask of all currently
+							 * supported cb flags
+							 */
+
+/* List of known BPF sock_ops operators.
+ * New entries can only be added at the end
+ */
+enum {
+	BPF_SOCK_OPS_VOID,
+	BPF_SOCK_OPS_TIMEOUT_INIT,	/* Should return SYN-RTO value to use or
+					 * -1 if default value should be used
+					 */
+	BPF_SOCK_OPS_RWND_INIT,		/* Should return initial advertized
+					 * window (in packets) or -1 if default
+					 * value should be used
+					 */
+	BPF_SOCK_OPS_TCP_CONNECT_CB,	/* Calls BPF program right before an
+					 * active connection is initialized
+					 */
+	BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB,	/* Calls BPF program when an
+						 * active connection is
+						 * established
+						 */
+	BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB,	/* Calls BPF program when a
+						 * passive connection is
+						 * established
+						 */
+	BPF_SOCK_OPS_NEEDS_ECN,		/* If connection's congestion control
+					 * needs ECN
+					 */
+	BPF_SOCK_OPS_BASE_RTT,		/* Get base RTT. The correct value is
+					 * based on the path and may be
+					 * dependent on the congestion control
+					 * algorithm. In general it indicates
+					 * a congestion threshold. RTTs above
+					 * this indicate congestion
+					 */
+	BPF_SOCK_OPS_RTO_CB,		/* Called when an RTO has triggered.
+					 * Arg1: value of icsk_retransmits
+					 * Arg2: value of icsk_rto
+					 * Arg3: whether RTO has expired
+					 */
+	BPF_SOCK_OPS_RETRANS_CB,	/* Called when skb is retransmitted.
+					 * Arg1: sequence number of 1st byte
+					 * Arg2: # segments
+					 * Arg3: return value of
+					 *       tcp_transmit_skb (0 => success)
+					 */
+	BPF_SOCK_OPS_STATE_CB,		/* Called when TCP changes state.
+					 * Arg1: old_state
+					 * Arg2: new_state
+					 */
+	BPF_SOCK_OPS_TCP_LISTEN_CB,	/* Called on listen(2), right after
+					 * socket transition to LISTEN state.
+					 */
+	BPF_SOCK_OPS_RTT_CB,		/* Called on every RTT.
+					 */
+};
+
+/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
+ * changes between the TCP and BPF versions. Ideally this should never happen.
+ * If it does, we need to add code to convert them before calling
+ * the BPF sock_ops function.
+ */
+enum {
+	BPF_TCP_ESTABLISHED = 1,
+	BPF_TCP_SYN_SENT,
+	BPF_TCP_SYN_RECV,
+	BPF_TCP_FIN_WAIT1,
+	BPF_TCP_FIN_WAIT2,
+	BPF_TCP_TIME_WAIT,
+	BPF_TCP_CLOSE,
+	BPF_TCP_CLOSE_WAIT,
+	BPF_TCP_LAST_ACK,
+	BPF_TCP_LISTEN,
+	BPF_TCP_CLOSING,	/* Now a valid state */
+	BPF_TCP_NEW_SYN_RECV,
+
+	BPF_TCP_MAX_STATES	/* Leave at the end! */
+};
+
+#define TCP_BPF_IW		1001	/* Set TCP initial congestion window */
+#define TCP_BPF_SNDCWND_CLAMP	1002	/* Set sndcwnd_clamp */
+
+struct bpf_perf_event_value {
+	__u64 counter;
+	__u64 enabled;
+	__u64 running;
+};
+
+#define BPF_DEVCG_ACC_MKNOD	(1ULL << 0)
+#define BPF_DEVCG_ACC_READ	(1ULL << 1)
+#define BPF_DEVCG_ACC_WRITE	(1ULL << 2)
+
+#define BPF_DEVCG_DEV_BLOCK	(1ULL << 0)
+#define BPF_DEVCG_DEV_CHAR	(1ULL << 1)
+
+struct bpf_cgroup_dev_ctx {
+	/* access_type encoded as (BPF_DEVCG_ACC_* << 16) | BPF_DEVCG_DEV_* */
+	__u32 access_type;
+	__u32 major;
+	__u32 minor;
+};
+
+struct bpf_raw_tracepoint_args {
+	__u64 args[0];
+};
+
+/* DIRECT:  Skip the FIB rules and go to FIB table associated with device
+ * OUTPUT:  Do lookup from egress perspective; default is ingress
+ */
+#define BPF_FIB_LOOKUP_DIRECT  (1U << 0)
+#define BPF_FIB_LOOKUP_OUTPUT  (1U << 1)
+
+enum {
+	BPF_FIB_LKUP_RET_SUCCESS,      /* lookup successful */
+	BPF_FIB_LKUP_RET_BLACKHOLE,    /* dest is blackholed; can be dropped */
+	BPF_FIB_LKUP_RET_UNREACHABLE,  /* dest is unreachable; can be dropped */
+	BPF_FIB_LKUP_RET_PROHIBIT,     /* dest not allowed; can be dropped */
+	BPF_FIB_LKUP_RET_NOT_FWDED,    /* packet is not forwarded */
+	BPF_FIB_LKUP_RET_FWD_DISABLED, /* fwding is not enabled on ingress */
+	BPF_FIB_LKUP_RET_UNSUPP_LWT,   /* fwd requires encapsulation */
+	BPF_FIB_LKUP_RET_NO_NEIGH,     /* no neighbor entry for nh */
+	BPF_FIB_LKUP_RET_FRAG_NEEDED,  /* fragmentation required to fwd */
+};
+
+struct bpf_fib_lookup {
+	/* input:  network family for lookup (AF_INET, AF_INET6)
+	 * output: network family of egress nexthop
+	 */
+	__u8	family;
+
+	/* set if lookup is to consider L4 data - e.g., FIB rules */
+	__u8	l4_protocol;
+	__be16	sport;
+	__be16	dport;
+
+	/* total length of packet from network header - used for MTU check */
+	__u16	tot_len;
+
+	/* input: L3 device index for lookup
+	 * output: device index from FIB lookup
+	 */
+	__u32	ifindex;
+
+	union {
+		/* inputs to lookup */
+		__u8	tos;		/* AF_INET  */
+		__be32	flowinfo;	/* AF_INET6, flow_label + priority */
+
+		/* output: metric of fib result (IPv4/IPv6 only) */
+		__u32	rt_metric;
+	};
+
+	union {
+		__be32		ipv4_src;
+		__u32		ipv6_src[4];  /* in6_addr; network order */
+	};
+
+	/* input to bpf_fib_lookup, ipv{4,6}_dst is destination address in
+	 * network header. output: bpf_fib_lookup sets to gateway address
+	 * if FIB lookup returns gateway route
+	 */
+	union {
+		__be32		ipv4_dst;
+		__u32		ipv6_dst[4];  /* in6_addr; network order */
+	};
+
+	/* output */
+	__be16	h_vlan_proto;
+	__be16	h_vlan_TCI;
+	__u8	smac[6];     /* ETH_ALEN */
+	__u8	dmac[6];     /* ETH_ALEN */
+};
+
+enum bpf_task_fd_type {
+	BPF_FD_TYPE_RAW_TRACEPOINT,	/* tp name */
+	BPF_FD_TYPE_TRACEPOINT,		/* tp name */
+	BPF_FD_TYPE_KPROBE,		/* (symbol + offset) or addr */
+	BPF_FD_TYPE_KRETPROBE,		/* (symbol + offset) or addr */
+	BPF_FD_TYPE_UPROBE,		/* filename + offset */
+	BPF_FD_TYPE_URETPROBE,		/* filename + offset */
+};
+
+#define BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG		(1U << 0)
+#define BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL		(1U << 1)
+#define BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP		(1U << 2)
+
+struct bpf_flow_keys {
+	__u16	nhoff;
+	__u16	thoff;
+	__u16	addr_proto;			/* ETH_P_* of valid addrs */
+	__u8	is_frag;
+	__u8	is_first_frag;
+	__u8	is_encap;
+	__u8	ip_proto;
+	__be16	n_proto;
+	__be16	sport;
+	__be16	dport;
+	union {
+		struct {
+			__be32	ipv4_src;
+			__be32	ipv4_dst;
+		};
+		struct {
+			__u32	ipv6_src[4];	/* in6_addr; network order */
+			__u32	ipv6_dst[4];	/* in6_addr; network order */
+		};
+	};
+	__u32	flags;
+	__be32	flow_label;
+};
+
+struct bpf_func_info {
+	__u32	insn_off;
+	__u32	type_id;
+};
+
+#define BPF_LINE_INFO_LINE_NUM(line_col)	((line_col) >> 10)
+#define BPF_LINE_INFO_LINE_COL(line_col)	((line_col) & 0x3ff)
+
+struct bpf_line_info {
+	__u32	insn_off;
+	__u32	file_name_off;
+	__u32	line_off;
+	__u32	line_col;
+};
+
+struct bpf_spin_lock {
+	__u32	val;
+};
+
+struct bpf_sysctl {
+	__u32	write;		/* Sysctl is being read (= 0) or written (= 1).
+				 * Allows 1,2,4-byte read, but no write.
+				 */
+	__u32	file_pos;	/* Sysctl file position to read from, write to.
+				 * Allows 1,2,4-byte read an 4-byte write.
+				 */
+};
+
+struct bpf_sockopt {
+	__bpf_md_ptr(struct bpf_sock *, sk);
+	__bpf_md_ptr(void *, optval);
+	__bpf_md_ptr(void *, optval_end);
+
+	__s32	level;
+	__s32	optname;
+	__s32	optlen;
+	__s32	retval;
+};
+
+#endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/src/contrib/libbpf/include/uapi/linux/bpf_common.h b/src/contrib/libbpf/include/uapi/linux/bpf_common.h
new file mode 100644
index 0000000..ee97668
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/bpf_common.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI__LINUX_BPF_COMMON_H__
+#define _UAPI__LINUX_BPF_COMMON_H__
+
+/* Instruction classes */
+#define BPF_CLASS(code) ((code) & 0x07)
+#define		BPF_LD		0x00
+#define		BPF_LDX		0x01
+#define		BPF_ST		0x02
+#define		BPF_STX		0x03
+#define		BPF_ALU		0x04
+#define		BPF_JMP		0x05
+#define		BPF_RET		0x06
+#define		BPF_MISC        0x07
+
+/* ld/ldx fields */
+#define BPF_SIZE(code)  ((code) & 0x18)
+#define		BPF_W		0x00 /* 32-bit */
+#define		BPF_H		0x08 /* 16-bit */
+#define		BPF_B		0x10 /*  8-bit */
+/* eBPF		BPF_DW		0x18    64-bit */
+#define BPF_MODE(code)  ((code) & 0xe0)
+#define		BPF_IMM		0x00
+#define		BPF_ABS		0x20
+#define		BPF_IND		0x40
+#define		BPF_MEM		0x60
+#define		BPF_LEN		0x80
+#define		BPF_MSH		0xa0
+
+/* alu/jmp fields */
+#define BPF_OP(code)    ((code) & 0xf0)
+#define		BPF_ADD		0x00
+#define		BPF_SUB		0x10
+#define		BPF_MUL		0x20
+#define		BPF_DIV		0x30
+#define		BPF_OR		0x40
+#define		BPF_AND		0x50
+#define		BPF_LSH		0x60
+#define		BPF_RSH		0x70
+#define		BPF_NEG		0x80
+#define		BPF_MOD		0x90
+#define		BPF_XOR		0xa0
+
+#define		BPF_JA		0x00
+#define		BPF_JEQ		0x10
+#define		BPF_JGT		0x20
+#define		BPF_JGE		0x30
+#define		BPF_JSET        0x40
+#define BPF_SRC(code)   ((code) & 0x08)
+#define		BPF_K		0x00
+#define		BPF_X		0x08
+
+#ifndef BPF_MAXINSNS
+#define BPF_MAXINSNS 4096
+#endif
+
+#endif /* _UAPI__LINUX_BPF_COMMON_H__ */
diff --git a/src/contrib/libbpf/include/uapi/linux/btf.h b/src/contrib/libbpf/include/uapi/linux/btf.h
new file mode 100644
index 0000000..63ae4a3
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/btf.h
@@ -0,0 +1,165 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/* Copyright (c) 2018 Facebook */
+#ifndef _UAPI__LINUX_BTF_H__
+#define _UAPI__LINUX_BTF_H__
+
+#include <linux/types.h>
+
+#define BTF_MAGIC	0xeB9F
+#define BTF_VERSION	1
+
+struct btf_header {
+	__u16	magic;
+	__u8	version;
+	__u8	flags;
+	__u32	hdr_len;
+
+	/* All offsets are in bytes relative to the end of this header */
+	__u32	type_off;	/* offset of type section	*/
+	__u32	type_len;	/* length of type section	*/
+	__u32	str_off;	/* offset of string section	*/
+	__u32	str_len;	/* length of string section	*/
+};
+
+/* Max # of type identifier */
+#define BTF_MAX_TYPE	0x0000ffff
+/* Max offset into the string section */
+#define BTF_MAX_NAME_OFFSET	0x0000ffff
+/* Max # of struct/union/enum members or func args */
+#define BTF_MAX_VLEN	0xffff
+
+struct btf_type {
+	__u32 name_off;
+	/* "info" bits arrangement
+	 * bits  0-15: vlen (e.g. # of struct's members)
+	 * bits 16-23: unused
+	 * bits 24-27: kind (e.g. int, ptr, array...etc)
+	 * bits 28-30: unused
+	 * bit     31: kind_flag, currently used by
+	 *             struct, union and fwd
+	 */
+	__u32 info;
+	/* "size" is used by INT, ENUM, STRUCT, UNION and DATASEC.
+	 * "size" tells the size of the type it is describing.
+	 *
+	 * "type" is used by PTR, TYPEDEF, VOLATILE, CONST, RESTRICT,
+	 * FUNC, FUNC_PROTO and VAR.
+	 * "type" is a type_id referring to another type.
+	 */
+	union {
+		__u32 size;
+		__u32 type;
+	};
+};
+
+#define BTF_INFO_KIND(info)	(((info) >> 24) & 0x0f)
+#define BTF_INFO_VLEN(info)	((info) & 0xffff)
+#define BTF_INFO_KFLAG(info)	((info) >> 31)
+
+#define BTF_KIND_UNKN		0	/* Unknown	*/
+#define BTF_KIND_INT		1	/* Integer	*/
+#define BTF_KIND_PTR		2	/* Pointer	*/
+#define BTF_KIND_ARRAY		3	/* Array	*/
+#define BTF_KIND_STRUCT		4	/* Struct	*/
+#define BTF_KIND_UNION		5	/* Union	*/
+#define BTF_KIND_ENUM		6	/* Enumeration	*/
+#define BTF_KIND_FWD		7	/* Forward	*/
+#define BTF_KIND_TYPEDEF	8	/* Typedef	*/
+#define BTF_KIND_VOLATILE	9	/* Volatile	*/
+#define BTF_KIND_CONST		10	/* Const	*/
+#define BTF_KIND_RESTRICT	11	/* Restrict	*/
+#define BTF_KIND_FUNC		12	/* Function	*/
+#define BTF_KIND_FUNC_PROTO	13	/* Function Proto	*/
+#define BTF_KIND_VAR		14	/* Variable	*/
+#define BTF_KIND_DATASEC	15	/* Section	*/
+#define BTF_KIND_MAX		BTF_KIND_DATASEC
+#define NR_BTF_KINDS		(BTF_KIND_MAX + 1)
+
+/* For some specific BTF_KIND, "struct btf_type" is immediately
+ * followed by extra data.
+ */
+
+/* BTF_KIND_INT is followed by a u32 and the following
+ * is the 32 bits arrangement:
+ */
+#define BTF_INT_ENCODING(VAL)	(((VAL) & 0x0f000000) >> 24)
+#define BTF_INT_OFFSET(VAL)	(((VAL) & 0x00ff0000) >> 16)
+#define BTF_INT_BITS(VAL)	((VAL)  & 0x000000ff)
+
+/* Attributes stored in the BTF_INT_ENCODING */
+#define BTF_INT_SIGNED	(1 << 0)
+#define BTF_INT_CHAR	(1 << 1)
+#define BTF_INT_BOOL	(1 << 2)
+
+/* BTF_KIND_ENUM is followed by multiple "struct btf_enum".
+ * The exact number of btf_enum is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_enum {
+	__u32	name_off;
+	__s32	val;
+};
+
+/* BTF_KIND_ARRAY is followed by one "struct btf_array" */
+struct btf_array {
+	__u32	type;
+	__u32	index_type;
+	__u32	nelems;
+};
+
+/* BTF_KIND_STRUCT and BTF_KIND_UNION are followed
+ * by multiple "struct btf_member".  The exact number
+ * of btf_member is stored in the vlen (of the info in
+ * "struct btf_type").
+ */
+struct btf_member {
+	__u32	name_off;
+	__u32	type;
+	/* If the type info kind_flag is set, the btf_member offset
+	 * contains both member bitfield size and bit offset. The
+	 * bitfield size is set for bitfield members. If the type
+	 * info kind_flag is not set, the offset contains only bit
+	 * offset.
+	 */
+	__u32	offset;
+};
+
+/* If the struct/union type info kind_flag is set, the
+ * following two macros are used to access bitfield_size
+ * and bit_offset from btf_member.offset.
+ */
+#define BTF_MEMBER_BITFIELD_SIZE(val)	((val) >> 24)
+#define BTF_MEMBER_BIT_OFFSET(val)	((val) & 0xffffff)
+
+/* BTF_KIND_FUNC_PROTO is followed by multiple "struct btf_param".
+ * The exact number of btf_param is stored in the vlen (of the
+ * info in "struct btf_type").
+ */
+struct btf_param {
+	__u32	name_off;
+	__u32	type;
+};
+
+enum {
+	BTF_VAR_STATIC = 0,
+	BTF_VAR_GLOBAL_ALLOCATED,
+};
+
+/* BTF_KIND_VAR is followed by a single "struct btf_var" to describe
+ * additional information related to the variable such as its linkage.
+ */
+struct btf_var {
+	__u32	linkage;
+};
+
+/* BTF_KIND_DATASEC is followed by multiple "struct btf_var_secinfo"
+ * to describe all BTF_KIND_VAR types it contains along with it's
+ * in-section offset as well as size.
+ */
+struct btf_var_secinfo {
+	__u32	type;
+	__u32	offset;
+	__u32	size;
+};
+
+#endif /* _UAPI__LINUX_BTF_H__ */
diff --git a/src/contrib/libbpf/include/uapi/linux/if_link.h b/src/contrib/libbpf/include/uapi/linux/if_link.h
new file mode 100644
index 0000000..8aec876
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/if_link.h
@@ -0,0 +1,1033 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_IF_LINK_H
+#define _UAPI_LINUX_IF_LINK_H
+
+#include <linux/types.h>
+#include <linux/netlink.h>
+
+/* This struct should be in sync with struct rtnl_link_stats64 */
+struct rtnl_link_stats {
+	__u32	rx_packets;		/* total packets received	*/
+	__u32	tx_packets;		/* total packets transmitted	*/
+	__u32	rx_bytes;		/* total bytes received 	*/
+	__u32	tx_bytes;		/* total bytes transmitted	*/
+	__u32	rx_errors;		/* bad packets received		*/
+	__u32	tx_errors;		/* packet transmit problems	*/
+	__u32	rx_dropped;		/* no space in linux buffers	*/
+	__u32	tx_dropped;		/* no space available in linux	*/
+	__u32	multicast;		/* multicast packets received	*/
+	__u32	collisions;
+
+	/* detailed rx_errors: */
+	__u32	rx_length_errors;
+	__u32	rx_over_errors;		/* receiver ring buff overflow	*/
+	__u32	rx_crc_errors;		/* recved pkt with crc error	*/
+	__u32	rx_frame_errors;	/* recv'd frame alignment error */
+	__u32	rx_fifo_errors;		/* recv'r fifo overrun		*/
+	__u32	rx_missed_errors;	/* receiver missed packet	*/
+
+	/* detailed tx_errors */
+	__u32	tx_aborted_errors;
+	__u32	tx_carrier_errors;
+	__u32	tx_fifo_errors;
+	__u32	tx_heartbeat_errors;
+	__u32	tx_window_errors;
+
+	/* for cslip etc */
+	__u32	rx_compressed;
+	__u32	tx_compressed;
+
+	__u32	rx_nohandler;		/* dropped, no handler found	*/
+};
+
+/* The main device statistics structure */
+struct rtnl_link_stats64 {
+	__u64	rx_packets;		/* total packets received	*/
+	__u64	tx_packets;		/* total packets transmitted	*/
+	__u64	rx_bytes;		/* total bytes received 	*/
+	__u64	tx_bytes;		/* total bytes transmitted	*/
+	__u64	rx_errors;		/* bad packets received		*/
+	__u64	tx_errors;		/* packet transmit problems	*/
+	__u64	rx_dropped;		/* no space in linux buffers	*/
+	__u64	tx_dropped;		/* no space available in linux	*/
+	__u64	multicast;		/* multicast packets received	*/
+	__u64	collisions;
+
+	/* detailed rx_errors: */
+	__u64	rx_length_errors;
+	__u64	rx_over_errors;		/* receiver ring buff overflow	*/
+	__u64	rx_crc_errors;		/* recved pkt with crc error	*/
+	__u64	rx_frame_errors;	/* recv'd frame alignment error */
+	__u64	rx_fifo_errors;		/* recv'r fifo overrun		*/
+	__u64	rx_missed_errors;	/* receiver missed packet	*/
+
+	/* detailed tx_errors */
+	__u64	tx_aborted_errors;
+	__u64	tx_carrier_errors;
+	__u64	tx_fifo_errors;
+	__u64	tx_heartbeat_errors;
+	__u64	tx_window_errors;
+
+	/* for cslip etc */
+	__u64	rx_compressed;
+	__u64	tx_compressed;
+
+	__u64	rx_nohandler;		/* dropped, no handler found	*/
+};
+
+/* The struct should be in sync with struct ifmap */
+struct rtnl_link_ifmap {
+	__u64	mem_start;
+	__u64	mem_end;
+	__u64	base_addr;
+	__u16	irq;
+	__u8	dma;
+	__u8	port;
+};
+
+/*
+ * IFLA_AF_SPEC
+ *   Contains nested attributes for address family specific attributes.
+ *   Each address family may create a attribute with the address family
+ *   number as type and create its own attribute structure in it.
+ *
+ *   Example:
+ *   [IFLA_AF_SPEC] = {
+ *       [AF_INET] = {
+ *           [IFLA_INET_CONF] = ...,
+ *       },
+ *       [AF_INET6] = {
+ *           [IFLA_INET6_FLAGS] = ...,
+ *           [IFLA_INET6_CONF] = ...,
+ *       }
+ *   }
+ */
+
+enum {
+	IFLA_UNSPEC,
+	IFLA_ADDRESS,
+	IFLA_BROADCAST,
+	IFLA_IFNAME,
+	IFLA_MTU,
+	IFLA_LINK,
+	IFLA_QDISC,
+	IFLA_STATS,
+	IFLA_COST,
+#define IFLA_COST IFLA_COST
+	IFLA_PRIORITY,
+#define IFLA_PRIORITY IFLA_PRIORITY
+	IFLA_MASTER,
+#define IFLA_MASTER IFLA_MASTER
+	IFLA_WIRELESS,		/* Wireless Extension event - see wireless.h */
+#define IFLA_WIRELESS IFLA_WIRELESS
+	IFLA_PROTINFO,		/* Protocol specific information for a link */
+#define IFLA_PROTINFO IFLA_PROTINFO
+	IFLA_TXQLEN,
+#define IFLA_TXQLEN IFLA_TXQLEN
+	IFLA_MAP,
+#define IFLA_MAP IFLA_MAP
+	IFLA_WEIGHT,
+#define IFLA_WEIGHT IFLA_WEIGHT
+	IFLA_OPERSTATE,
+	IFLA_LINKMODE,
+	IFLA_LINKINFO,
+#define IFLA_LINKINFO IFLA_LINKINFO
+	IFLA_NET_NS_PID,
+	IFLA_IFALIAS,
+	IFLA_NUM_VF,		/* Number of VFs if device is SR-IOV PF */
+	IFLA_VFINFO_LIST,
+	IFLA_STATS64,
+	IFLA_VF_PORTS,
+	IFLA_PORT_SELF,
+	IFLA_AF_SPEC,
+	IFLA_GROUP,		/* Group the device belongs to */
+	IFLA_NET_NS_FD,
+	IFLA_EXT_MASK,		/* Extended info mask, VFs, etc */
+	IFLA_PROMISCUITY,	/* Promiscuity count: > 0 means acts PROMISC */
+#define IFLA_PROMISCUITY IFLA_PROMISCUITY
+	IFLA_NUM_TX_QUEUES,
+	IFLA_NUM_RX_QUEUES,
+	IFLA_CARRIER,
+	IFLA_PHYS_PORT_ID,
+	IFLA_CARRIER_CHANGES,
+	IFLA_PHYS_SWITCH_ID,
+	IFLA_LINK_NETNSID,
+	IFLA_PHYS_PORT_NAME,
+	IFLA_PROTO_DOWN,
+	IFLA_GSO_MAX_SEGS,
+	IFLA_GSO_MAX_SIZE,
+	IFLA_PAD,
+	IFLA_XDP,
+	IFLA_EVENT,
+	IFLA_NEW_NETNSID,
+	IFLA_IF_NETNSID,
+	IFLA_TARGET_NETNSID = IFLA_IF_NETNSID, /* new alias */
+	IFLA_CARRIER_UP_COUNT,
+	IFLA_CARRIER_DOWN_COUNT,
+	IFLA_NEW_IFINDEX,
+	IFLA_MIN_MTU,
+	IFLA_MAX_MTU,
+	IFLA_PROP_LIST,
+	IFLA_ALT_IFNAME, /* Alternative ifname */
+	__IFLA_MAX
+};
+
+
+#define IFLA_MAX (__IFLA_MAX - 1)
+
+/* backwards compatibility for userspace */
+#ifndef __KERNEL__
+#define IFLA_RTA(r)  ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifinfomsg))))
+#define IFLA_PAYLOAD(n) NLMSG_PAYLOAD(n,sizeof(struct ifinfomsg))
+#endif
+
+enum {
+	IFLA_INET_UNSPEC,
+	IFLA_INET_CONF,
+	__IFLA_INET_MAX,
+};
+
+#define IFLA_INET_MAX (__IFLA_INET_MAX - 1)
+
+/* ifi_flags.
+
+   IFF_* flags.
+
+   The only change is:
+   IFF_LOOPBACK, IFF_BROADCAST and IFF_POINTOPOINT are
+   more not changeable by user. They describe link media
+   characteristics and set by device driver.
+
+   Comments:
+   - Combination IFF_BROADCAST|IFF_POINTOPOINT is invalid
+   - If neither of these three flags are set;
+     the interface is NBMA.
+
+   - IFF_MULTICAST does not mean anything special:
+   multicasts can be used on all not-NBMA links.
+   IFF_MULTICAST means that this media uses special encapsulation
+   for multicast frames. Apparently, all IFF_POINTOPOINT and
+   IFF_BROADCAST devices are able to use multicasts too.
+ */
+
+/* IFLA_LINK.
+   For usual devices it is equal ifi_index.
+   If it is a "virtual interface" (f.e. tunnel), ifi_link
+   can point to real physical interface (f.e. for bandwidth calculations),
+   or maybe 0, what means, that real media is unknown (usual
+   for IPIP tunnels, when route to endpoint is allowed to change)
+ */
+
+/* Subtype attributes for IFLA_PROTINFO */
+enum {
+	IFLA_INET6_UNSPEC,
+	IFLA_INET6_FLAGS,	/* link flags			*/
+	IFLA_INET6_CONF,	/* sysctl parameters		*/
+	IFLA_INET6_STATS,	/* statistics			*/
+	IFLA_INET6_MCAST,	/* MC things. What of them?	*/
+	IFLA_INET6_CACHEINFO,	/* time values and max reasm size */
+	IFLA_INET6_ICMP6STATS,	/* statistics (icmpv6)		*/
+	IFLA_INET6_TOKEN,	/* device token			*/
+	IFLA_INET6_ADDR_GEN_MODE, /* implicit address generator mode */
+	__IFLA_INET6_MAX
+};
+
+#define IFLA_INET6_MAX	(__IFLA_INET6_MAX - 1)
+
+enum in6_addr_gen_mode {
+	IN6_ADDR_GEN_MODE_EUI64,
+	IN6_ADDR_GEN_MODE_NONE,
+	IN6_ADDR_GEN_MODE_STABLE_PRIVACY,
+	IN6_ADDR_GEN_MODE_RANDOM,
+};
+
+/* Bridge section */
+
+enum {
+	IFLA_BR_UNSPEC,
+	IFLA_BR_FORWARD_DELAY,
+	IFLA_BR_HELLO_TIME,
+	IFLA_BR_MAX_AGE,
+	IFLA_BR_AGEING_TIME,
+	IFLA_BR_STP_STATE,
+	IFLA_BR_PRIORITY,
+	IFLA_BR_VLAN_FILTERING,
+	IFLA_BR_VLAN_PROTOCOL,
+	IFLA_BR_GROUP_FWD_MASK,
+	IFLA_BR_ROOT_ID,
+	IFLA_BR_BRIDGE_ID,
+	IFLA_BR_ROOT_PORT,
+	IFLA_BR_ROOT_PATH_COST,
+	IFLA_BR_TOPOLOGY_CHANGE,
+	IFLA_BR_TOPOLOGY_CHANGE_DETECTED,
+	IFLA_BR_HELLO_TIMER,
+	IFLA_BR_TCN_TIMER,
+	IFLA_BR_TOPOLOGY_CHANGE_TIMER,
+	IFLA_BR_GC_TIMER,
+	IFLA_BR_GROUP_ADDR,
+	IFLA_BR_FDB_FLUSH,
+	IFLA_BR_MCAST_ROUTER,
+	IFLA_BR_MCAST_SNOOPING,
+	IFLA_BR_MCAST_QUERY_USE_IFADDR,
+	IFLA_BR_MCAST_QUERIER,
+	IFLA_BR_MCAST_HASH_ELASTICITY,
+	IFLA_BR_MCAST_HASH_MAX,
+	IFLA_BR_MCAST_LAST_MEMBER_CNT,
+	IFLA_BR_MCAST_STARTUP_QUERY_CNT,
+	IFLA_BR_MCAST_LAST_MEMBER_INTVL,
+	IFLA_BR_MCAST_MEMBERSHIP_INTVL,
+	IFLA_BR_MCAST_QUERIER_INTVL,
+	IFLA_BR_MCAST_QUERY_INTVL,
+	IFLA_BR_MCAST_QUERY_RESPONSE_INTVL,
+	IFLA_BR_MCAST_STARTUP_QUERY_INTVL,
+	IFLA_BR_NF_CALL_IPTABLES,
+	IFLA_BR_NF_CALL_IP6TABLES,
+	IFLA_BR_NF_CALL_ARPTABLES,
+	IFLA_BR_VLAN_DEFAULT_PVID,
+	IFLA_BR_PAD,
+	IFLA_BR_VLAN_STATS_ENABLED,
+	IFLA_BR_MCAST_STATS_ENABLED,
+	IFLA_BR_MCAST_IGMP_VERSION,
+	IFLA_BR_MCAST_MLD_VERSION,
+	IFLA_BR_VLAN_STATS_PER_PORT,
+	IFLA_BR_MULTI_BOOLOPT,
+	__IFLA_BR_MAX,
+};
+
+#define IFLA_BR_MAX	(__IFLA_BR_MAX - 1)
+
+struct ifla_bridge_id {
+	__u8	prio[2];
+	__u8	addr[6]; /* ETH_ALEN */
+};
+
+enum {
+	BRIDGE_MODE_UNSPEC,
+	BRIDGE_MODE_HAIRPIN,
+};
+
+enum {
+	IFLA_BRPORT_UNSPEC,
+	IFLA_BRPORT_STATE,	/* Spanning tree state     */
+	IFLA_BRPORT_PRIORITY,	/* "             priority  */
+	IFLA_BRPORT_COST,	/* "             cost      */
+	IFLA_BRPORT_MODE,	/* mode (hairpin)          */
+	IFLA_BRPORT_GUARD,	/* bpdu guard              */
+	IFLA_BRPORT_PROTECT,	/* root port protection    */
+	IFLA_BRPORT_FAST_LEAVE,	/* multicast fast leave    */
+	IFLA_BRPORT_LEARNING,	/* mac learning */
+	IFLA_BRPORT_UNICAST_FLOOD, /* flood unicast traffic */
+	IFLA_BRPORT_PROXYARP,	/* proxy ARP */
+	IFLA_BRPORT_LEARNING_SYNC, /* mac learning sync from device */
+	IFLA_BRPORT_PROXYARP_WIFI, /* proxy ARP for Wi-Fi */
+	IFLA_BRPORT_ROOT_ID,	/* designated root */
+	IFLA_BRPORT_BRIDGE_ID,	/* designated bridge */
+	IFLA_BRPORT_DESIGNATED_PORT,
+	IFLA_BRPORT_DESIGNATED_COST,
+	IFLA_BRPORT_ID,
+	IFLA_BRPORT_NO,
+	IFLA_BRPORT_TOPOLOGY_CHANGE_ACK,
+	IFLA_BRPORT_CONFIG_PENDING,
+	IFLA_BRPORT_MESSAGE_AGE_TIMER,
+	IFLA_BRPORT_FORWARD_DELAY_TIMER,
+	IFLA_BRPORT_HOLD_TIMER,
+	IFLA_BRPORT_FLUSH,
+	IFLA_BRPORT_MULTICAST_ROUTER,
+	IFLA_BRPORT_PAD,
+	IFLA_BRPORT_MCAST_FLOOD,
+	IFLA_BRPORT_MCAST_TO_UCAST,
+	IFLA_BRPORT_VLAN_TUNNEL,
+	IFLA_BRPORT_BCAST_FLOOD,
+	IFLA_BRPORT_GROUP_FWD_MASK,
+	IFLA_BRPORT_NEIGH_SUPPRESS,
+	IFLA_BRPORT_ISOLATED,
+	IFLA_BRPORT_BACKUP_PORT,
+	__IFLA_BRPORT_MAX
+};
+#define IFLA_BRPORT_MAX (__IFLA_BRPORT_MAX - 1)
+
+struct ifla_cacheinfo {
+	__u32	max_reasm_len;
+	__u32	tstamp;		/* ipv6InterfaceTable updated timestamp */
+	__u32	reachable_time;
+	__u32	retrans_time;
+};
+
+enum {
+	IFLA_INFO_UNSPEC,
+	IFLA_INFO_KIND,
+	IFLA_INFO_DATA,
+	IFLA_INFO_XSTATS,
+	IFLA_INFO_SLAVE_KIND,
+	IFLA_INFO_SLAVE_DATA,
+	__IFLA_INFO_MAX,
+};
+
+#define IFLA_INFO_MAX	(__IFLA_INFO_MAX - 1)
+
+/* VLAN section */
+
+enum {
+	IFLA_VLAN_UNSPEC,
+	IFLA_VLAN_ID,
+	IFLA_VLAN_FLAGS,
+	IFLA_VLAN_EGRESS_QOS,
+	IFLA_VLAN_INGRESS_QOS,
+	IFLA_VLAN_PROTOCOL,
+	__IFLA_VLAN_MAX,
+};
+
+#define IFLA_VLAN_MAX	(__IFLA_VLAN_MAX - 1)
+
+struct ifla_vlan_flags {
+	__u32	flags;
+	__u32	mask;
+};
+
+enum {
+	IFLA_VLAN_QOS_UNSPEC,
+	IFLA_VLAN_QOS_MAPPING,
+	__IFLA_VLAN_QOS_MAX
+};
+
+#define IFLA_VLAN_QOS_MAX	(__IFLA_VLAN_QOS_MAX - 1)
+
+struct ifla_vlan_qos_mapping {
+	__u32 from;
+	__u32 to;
+};
+
+/* MACVLAN section */
+enum {
+	IFLA_MACVLAN_UNSPEC,
+	IFLA_MACVLAN_MODE,
+	IFLA_MACVLAN_FLAGS,
+	IFLA_MACVLAN_MACADDR_MODE,
+	IFLA_MACVLAN_MACADDR,
+	IFLA_MACVLAN_MACADDR_DATA,
+	IFLA_MACVLAN_MACADDR_COUNT,
+	__IFLA_MACVLAN_MAX,
+};
+
+#define IFLA_MACVLAN_MAX (__IFLA_MACVLAN_MAX - 1)
+
+enum macvlan_mode {
+	MACVLAN_MODE_PRIVATE = 1, /* don't talk to other macvlans */
+	MACVLAN_MODE_VEPA    = 2, /* talk to other ports through ext bridge */
+	MACVLAN_MODE_BRIDGE  = 4, /* talk to bridge ports directly */
+	MACVLAN_MODE_PASSTHRU = 8,/* take over the underlying device */
+	MACVLAN_MODE_SOURCE  = 16,/* use source MAC address list to assign */
+};
+
+enum macvlan_macaddr_mode {
+	MACVLAN_MACADDR_ADD,
+	MACVLAN_MACADDR_DEL,
+	MACVLAN_MACADDR_FLUSH,
+	MACVLAN_MACADDR_SET,
+};
+
+#define MACVLAN_FLAG_NOPROMISC	1
+
+/* VRF section */
+enum {
+	IFLA_VRF_UNSPEC,
+	IFLA_VRF_TABLE,
+	__IFLA_VRF_MAX
+};
+
+#define IFLA_VRF_MAX (__IFLA_VRF_MAX - 1)
+
+enum {
+	IFLA_VRF_PORT_UNSPEC,
+	IFLA_VRF_PORT_TABLE,
+	__IFLA_VRF_PORT_MAX
+};
+
+#define IFLA_VRF_PORT_MAX (__IFLA_VRF_PORT_MAX - 1)
+
+/* MACSEC section */
+enum {
+	IFLA_MACSEC_UNSPEC,
+	IFLA_MACSEC_SCI,
+	IFLA_MACSEC_PORT,
+	IFLA_MACSEC_ICV_LEN,
+	IFLA_MACSEC_CIPHER_SUITE,
+	IFLA_MACSEC_WINDOW,
+	IFLA_MACSEC_ENCODING_SA,
+	IFLA_MACSEC_ENCRYPT,
+	IFLA_MACSEC_PROTECT,
+	IFLA_MACSEC_INC_SCI,
+	IFLA_MACSEC_ES,
+	IFLA_MACSEC_SCB,
+	IFLA_MACSEC_REPLAY_PROTECT,
+	IFLA_MACSEC_VALIDATION,
+	IFLA_MACSEC_PAD,
+	__IFLA_MACSEC_MAX,
+};
+
+#define IFLA_MACSEC_MAX (__IFLA_MACSEC_MAX - 1)
+
+/* XFRM section */
+enum {
+	IFLA_XFRM_UNSPEC,
+	IFLA_XFRM_LINK,
+	IFLA_XFRM_IF_ID,
+	__IFLA_XFRM_MAX
+};
+
+#define IFLA_XFRM_MAX (__IFLA_XFRM_MAX - 1)
+
+enum macsec_validation_type {
+	MACSEC_VALIDATE_DISABLED = 0,
+	MACSEC_VALIDATE_CHECK = 1,
+	MACSEC_VALIDATE_STRICT = 2,
+	__MACSEC_VALIDATE_END,
+	MACSEC_VALIDATE_MAX = __MACSEC_VALIDATE_END - 1,
+};
+
+/* IPVLAN section */
+enum {
+	IFLA_IPVLAN_UNSPEC,
+	IFLA_IPVLAN_MODE,
+	IFLA_IPVLAN_FLAGS,
+	__IFLA_IPVLAN_MAX
+};
+
+#define IFLA_IPVLAN_MAX (__IFLA_IPVLAN_MAX - 1)
+
+enum ipvlan_mode {
+	IPVLAN_MODE_L2 = 0,
+	IPVLAN_MODE_L3,
+	IPVLAN_MODE_L3S,
+	IPVLAN_MODE_MAX
+};
+
+#define IPVLAN_F_PRIVATE	0x01
+#define IPVLAN_F_VEPA		0x02
+
+/* VXLAN section */
+enum {
+	IFLA_VXLAN_UNSPEC,
+	IFLA_VXLAN_ID,
+	IFLA_VXLAN_GROUP,	/* group or remote address */
+	IFLA_VXLAN_LINK,
+	IFLA_VXLAN_LOCAL,
+	IFLA_VXLAN_TTL,
+	IFLA_VXLAN_TOS,
+	IFLA_VXLAN_LEARNING,
+	IFLA_VXLAN_AGEING,
+	IFLA_VXLAN_LIMIT,
+	IFLA_VXLAN_PORT_RANGE,	/* source port */
+	IFLA_VXLAN_PROXY,
+	IFLA_VXLAN_RSC,
+	IFLA_VXLAN_L2MISS,
+	IFLA_VXLAN_L3MISS,
+	IFLA_VXLAN_PORT,	/* destination port */
+	IFLA_VXLAN_GROUP6,
+	IFLA_VXLAN_LOCAL6,
+	IFLA_VXLAN_UDP_CSUM,
+	IFLA_VXLAN_UDP_ZERO_CSUM6_TX,
+	IFLA_VXLAN_UDP_ZERO_CSUM6_RX,
+	IFLA_VXLAN_REMCSUM_TX,
+	IFLA_VXLAN_REMCSUM_RX,
+	IFLA_VXLAN_GBP,
+	IFLA_VXLAN_REMCSUM_NOPARTIAL,
+	IFLA_VXLAN_COLLECT_METADATA,
+	IFLA_VXLAN_LABEL,
+	IFLA_VXLAN_GPE,
+	IFLA_VXLAN_TTL_INHERIT,
+	IFLA_VXLAN_DF,
+	__IFLA_VXLAN_MAX
+};
+#define IFLA_VXLAN_MAX	(__IFLA_VXLAN_MAX - 1)
+
+struct ifla_vxlan_port_range {
+	__be16	low;
+	__be16	high;
+};
+
+enum ifla_vxlan_df {
+	VXLAN_DF_UNSET = 0,
+	VXLAN_DF_SET,
+	VXLAN_DF_INHERIT,
+	__VXLAN_DF_END,
+	VXLAN_DF_MAX = __VXLAN_DF_END - 1,
+};
+
+/* GENEVE section */
+enum {
+	IFLA_GENEVE_UNSPEC,
+	IFLA_GENEVE_ID,
+	IFLA_GENEVE_REMOTE,
+	IFLA_GENEVE_TTL,
+	IFLA_GENEVE_TOS,
+	IFLA_GENEVE_PORT,	/* destination port */
+	IFLA_GENEVE_COLLECT_METADATA,
+	IFLA_GENEVE_REMOTE6,
+	IFLA_GENEVE_UDP_CSUM,
+	IFLA_GENEVE_UDP_ZERO_CSUM6_TX,
+	IFLA_GENEVE_UDP_ZERO_CSUM6_RX,
+	IFLA_GENEVE_LABEL,
+	IFLA_GENEVE_TTL_INHERIT,
+	IFLA_GENEVE_DF,
+	__IFLA_GENEVE_MAX
+};
+#define IFLA_GENEVE_MAX	(__IFLA_GENEVE_MAX - 1)
+
+enum ifla_geneve_df {
+	GENEVE_DF_UNSET = 0,
+	GENEVE_DF_SET,
+	GENEVE_DF_INHERIT,
+	__GENEVE_DF_END,
+	GENEVE_DF_MAX = __GENEVE_DF_END - 1,
+};
+
+/* PPP section */
+enum {
+	IFLA_PPP_UNSPEC,
+	IFLA_PPP_DEV_FD,
+	__IFLA_PPP_MAX
+};
+#define IFLA_PPP_MAX (__IFLA_PPP_MAX - 1)
+
+/* GTP section */
+
+enum ifla_gtp_role {
+	GTP_ROLE_GGSN = 0,
+	GTP_ROLE_SGSN,
+};
+
+enum {
+	IFLA_GTP_UNSPEC,
+	IFLA_GTP_FD0,
+	IFLA_GTP_FD1,
+	IFLA_GTP_PDP_HASHSIZE,
+	IFLA_GTP_ROLE,
+	__IFLA_GTP_MAX,
+};
+#define IFLA_GTP_MAX (__IFLA_GTP_MAX - 1)
+
+/* Bonding section */
+
+enum {
+	IFLA_BOND_UNSPEC,
+	IFLA_BOND_MODE,
+	IFLA_BOND_ACTIVE_SLAVE,
+	IFLA_BOND_MIIMON,
+	IFLA_BOND_UPDELAY,
+	IFLA_BOND_DOWNDELAY,
+	IFLA_BOND_USE_CARRIER,
+	IFLA_BOND_ARP_INTERVAL,
+	IFLA_BOND_ARP_IP_TARGET,
+	IFLA_BOND_ARP_VALIDATE,
+	IFLA_BOND_ARP_ALL_TARGETS,
+	IFLA_BOND_PRIMARY,
+	IFLA_BOND_PRIMARY_RESELECT,
+	IFLA_BOND_FAIL_OVER_MAC,
+	IFLA_BOND_XMIT_HASH_POLICY,
+	IFLA_BOND_RESEND_IGMP,
+	IFLA_BOND_NUM_PEER_NOTIF,
+	IFLA_BOND_ALL_SLAVES_ACTIVE,
+	IFLA_BOND_MIN_LINKS,
+	IFLA_BOND_LP_INTERVAL,
+	IFLA_BOND_PACKETS_PER_SLAVE,
+	IFLA_BOND_AD_LACP_RATE,
+	IFLA_BOND_AD_SELECT,
+	IFLA_BOND_AD_INFO,
+	IFLA_BOND_AD_ACTOR_SYS_PRIO,
+	IFLA_BOND_AD_USER_PORT_KEY,
+	IFLA_BOND_AD_ACTOR_SYSTEM,
+	IFLA_BOND_TLB_DYNAMIC_LB,
+	IFLA_BOND_PEER_NOTIF_DELAY,
+	__IFLA_BOND_MAX,
+};
+
+#define IFLA_BOND_MAX	(__IFLA_BOND_MAX - 1)
+
+enum {
+	IFLA_BOND_AD_INFO_UNSPEC,
+	IFLA_BOND_AD_INFO_AGGREGATOR,
+	IFLA_BOND_AD_INFO_NUM_PORTS,
+	IFLA_BOND_AD_INFO_ACTOR_KEY,
+	IFLA_BOND_AD_INFO_PARTNER_KEY,
+	IFLA_BOND_AD_INFO_PARTNER_MAC,
+	__IFLA_BOND_AD_INFO_MAX,
+};
+
+#define IFLA_BOND_AD_INFO_MAX	(__IFLA_BOND_AD_INFO_MAX - 1)
+
+enum {
+	IFLA_BOND_SLAVE_UNSPEC,
+	IFLA_BOND_SLAVE_STATE,
+	IFLA_BOND_SLAVE_MII_STATUS,
+	IFLA_BOND_SLAVE_LINK_FAILURE_COUNT,
+	IFLA_BOND_SLAVE_PERM_HWADDR,
+	IFLA_BOND_SLAVE_QUEUE_ID,
+	IFLA_BOND_SLAVE_AD_AGGREGATOR_ID,
+	IFLA_BOND_SLAVE_AD_ACTOR_OPER_PORT_STATE,
+	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE,
+	__IFLA_BOND_SLAVE_MAX,
+};
+
+#define IFLA_BOND_SLAVE_MAX	(__IFLA_BOND_SLAVE_MAX - 1)
+
+/* SR-IOV virtual function management section */
+
+enum {
+	IFLA_VF_INFO_UNSPEC,
+	IFLA_VF_INFO,
+	__IFLA_VF_INFO_MAX,
+};
+
+#define IFLA_VF_INFO_MAX (__IFLA_VF_INFO_MAX - 1)
+
+enum {
+	IFLA_VF_UNSPEC,
+	IFLA_VF_MAC,		/* Hardware queue specific attributes */
+	IFLA_VF_VLAN,		/* VLAN ID and QoS */
+	IFLA_VF_TX_RATE,	/* Max TX Bandwidth Allocation */
+	IFLA_VF_SPOOFCHK,	/* Spoof Checking on/off switch */
+	IFLA_VF_LINK_STATE,	/* link state enable/disable/auto switch */
+	IFLA_VF_RATE,		/* Min and Max TX Bandwidth Allocation */
+	IFLA_VF_RSS_QUERY_EN,	/* RSS Redirection Table and Hash Key query
+				 * on/off switch
+				 */
+	IFLA_VF_STATS,		/* network device statistics */
+	IFLA_VF_TRUST,		/* Trust VF */
+	IFLA_VF_IB_NODE_GUID,	/* VF Infiniband node GUID */
+	IFLA_VF_IB_PORT_GUID,	/* VF Infiniband port GUID */
+	IFLA_VF_VLAN_LIST,	/* nested list of vlans, option for QinQ */
+	IFLA_VF_BROADCAST,	/* VF broadcast */
+	__IFLA_VF_MAX,
+};
+
+#define IFLA_VF_MAX (__IFLA_VF_MAX - 1)
+
+struct ifla_vf_mac {
+	__u32 vf;
+	__u8 mac[32]; /* MAX_ADDR_LEN */
+};
+
+struct ifla_vf_broadcast {
+	__u8 broadcast[32];
+};
+
+struct ifla_vf_vlan {
+	__u32 vf;
+	__u32 vlan; /* 0 - 4095, 0 disables VLAN filter */
+	__u32 qos;
+};
+
+enum {
+	IFLA_VF_VLAN_INFO_UNSPEC,
+	IFLA_VF_VLAN_INFO,	/* VLAN ID, QoS and VLAN protocol */
+	__IFLA_VF_VLAN_INFO_MAX,
+};
+
+#define IFLA_VF_VLAN_INFO_MAX (__IFLA_VF_VLAN_INFO_MAX - 1)
+#define MAX_VLAN_LIST_LEN 1
+
+struct ifla_vf_vlan_info {
+	__u32 vf;
+	__u32 vlan; /* 0 - 4095, 0 disables VLAN filter */
+	__u32 qos;
+	__be16 vlan_proto; /* VLAN protocol either 802.1Q or 802.1ad */
+};
+
+struct ifla_vf_tx_rate {
+	__u32 vf;
+	__u32 rate; /* Max TX bandwidth in Mbps, 0 disables throttling */
+};
+
+struct ifla_vf_rate {
+	__u32 vf;
+	__u32 min_tx_rate; /* Min Bandwidth in Mbps */
+	__u32 max_tx_rate; /* Max Bandwidth in Mbps */
+};
+
+struct ifla_vf_spoofchk {
+	__u32 vf;
+	__u32 setting;
+};
+
+struct ifla_vf_guid {
+	__u32 vf;
+	__u64 guid;
+};
+
+enum {
+	IFLA_VF_LINK_STATE_AUTO,	/* link state of the uplink */
+	IFLA_VF_LINK_STATE_ENABLE,	/* link always up */
+	IFLA_VF_LINK_STATE_DISABLE,	/* link always down */
+	__IFLA_VF_LINK_STATE_MAX,
+};
+
+struct ifla_vf_link_state {
+	__u32 vf;
+	__u32 link_state;
+};
+
+struct ifla_vf_rss_query_en {
+	__u32 vf;
+	__u32 setting;
+};
+
+enum {
+	IFLA_VF_STATS_RX_PACKETS,
+	IFLA_VF_STATS_TX_PACKETS,
+	IFLA_VF_STATS_RX_BYTES,
+	IFLA_VF_STATS_TX_BYTES,
+	IFLA_VF_STATS_BROADCAST,
+	IFLA_VF_STATS_MULTICAST,
+	IFLA_VF_STATS_PAD,
+	IFLA_VF_STATS_RX_DROPPED,
+	IFLA_VF_STATS_TX_DROPPED,
+	__IFLA_VF_STATS_MAX,
+};
+
+#define IFLA_VF_STATS_MAX (__IFLA_VF_STATS_MAX - 1)
+
+struct ifla_vf_trust {
+	__u32 vf;
+	__u32 setting;
+};
+
+/* VF ports management section
+ *
+ *	Nested layout of set/get msg is:
+ *
+ *		[IFLA_NUM_VF]
+ *		[IFLA_VF_PORTS]
+ *			[IFLA_VF_PORT]
+ *				[IFLA_PORT_*], ...
+ *			[IFLA_VF_PORT]
+ *				[IFLA_PORT_*], ...
+ *			...
+ *		[IFLA_PORT_SELF]
+ *			[IFLA_PORT_*], ...
+ */
+
+enum {
+	IFLA_VF_PORT_UNSPEC,
+	IFLA_VF_PORT,			/* nest */
+	__IFLA_VF_PORT_MAX,
+};
+
+#define IFLA_VF_PORT_MAX (__IFLA_VF_PORT_MAX - 1)
+
+enum {
+	IFLA_PORT_UNSPEC,
+	IFLA_PORT_VF,			/* __u32 */
+	IFLA_PORT_PROFILE,		/* string */
+	IFLA_PORT_VSI_TYPE,		/* 802.1Qbg (pre-)standard VDP */
+	IFLA_PORT_INSTANCE_UUID,	/* binary UUID */
+	IFLA_PORT_HOST_UUID,		/* binary UUID */
+	IFLA_PORT_REQUEST,		/* __u8 */
+	IFLA_PORT_RESPONSE,		/* __u16, output only */
+	__IFLA_PORT_MAX,
+};
+
+#define IFLA_PORT_MAX (__IFLA_PORT_MAX - 1)
+
+#define PORT_PROFILE_MAX	40
+#define PORT_UUID_MAX		16
+#define PORT_SELF_VF		-1
+
+enum {
+	PORT_REQUEST_PREASSOCIATE = 0,
+	PORT_REQUEST_PREASSOCIATE_RR,
+	PORT_REQUEST_ASSOCIATE,
+	PORT_REQUEST_DISASSOCIATE,
+};
+
+enum {
+	PORT_VDP_RESPONSE_SUCCESS = 0,
+	PORT_VDP_RESPONSE_INVALID_FORMAT,
+	PORT_VDP_RESPONSE_INSUFFICIENT_RESOURCES,
+	PORT_VDP_RESPONSE_UNUSED_VTID,
+	PORT_VDP_RESPONSE_VTID_VIOLATION,
+	PORT_VDP_RESPONSE_VTID_VERSION_VIOALTION,
+	PORT_VDP_RESPONSE_OUT_OF_SYNC,
+	/* 0x08-0xFF reserved for future VDP use */
+	PORT_PROFILE_RESPONSE_SUCCESS = 0x100,
+	PORT_PROFILE_RESPONSE_INPROGRESS,
+	PORT_PROFILE_RESPONSE_INVALID,
+	PORT_PROFILE_RESPONSE_BADSTATE,
+	PORT_PROFILE_RESPONSE_INSUFFICIENT_RESOURCES,
+	PORT_PROFILE_RESPONSE_ERROR,
+};
+
+struct ifla_port_vsi {
+	__u8 vsi_mgr_id;
+	__u8 vsi_type_id[3];
+	__u8 vsi_type_version;
+	__u8 pad[3];
+};
+
+
+/* IPoIB section */
+
+enum {
+	IFLA_IPOIB_UNSPEC,
+	IFLA_IPOIB_PKEY,
+	IFLA_IPOIB_MODE,
+	IFLA_IPOIB_UMCAST,
+	__IFLA_IPOIB_MAX
+};
+
+enum {
+	IPOIB_MODE_DATAGRAM  = 0, /* using unreliable datagram QPs */
+	IPOIB_MODE_CONNECTED = 1, /* using connected QPs */
+};
+
+#define IFLA_IPOIB_MAX (__IFLA_IPOIB_MAX - 1)
+
+
+/* HSR section */
+
+enum {
+	IFLA_HSR_UNSPEC,
+	IFLA_HSR_SLAVE1,
+	IFLA_HSR_SLAVE2,
+	IFLA_HSR_MULTICAST_SPEC,	/* Last byte of supervision addr */
+	IFLA_HSR_SUPERVISION_ADDR,	/* Supervision frame multicast addr */
+	IFLA_HSR_SEQ_NR,
+	IFLA_HSR_VERSION,		/* HSR version */
+	__IFLA_HSR_MAX,
+};
+
+#define IFLA_HSR_MAX (__IFLA_HSR_MAX - 1)
+
+/* STATS section */
+
+struct if_stats_msg {
+	__u8  family;
+	__u8  pad1;
+	__u16 pad2;
+	__u32 ifindex;
+	__u32 filter_mask;
+};
+
+/* A stats attribute can be netdev specific or a global stat.
+ * For netdev stats, lets use the prefix IFLA_STATS_LINK_*
+ */
+enum {
+	IFLA_STATS_UNSPEC, /* also used as 64bit pad attribute */
+	IFLA_STATS_LINK_64,
+	IFLA_STATS_LINK_XSTATS,
+	IFLA_STATS_LINK_XSTATS_SLAVE,
+	IFLA_STATS_LINK_OFFLOAD_XSTATS,
+	IFLA_STATS_AF_SPEC,
+	__IFLA_STATS_MAX,
+};
+
+#define IFLA_STATS_MAX (__IFLA_STATS_MAX - 1)
+
+#define IFLA_STATS_FILTER_BIT(ATTR)	(1 << (ATTR - 1))
+
+/* These are embedded into IFLA_STATS_LINK_XSTATS:
+ * [IFLA_STATS_LINK_XSTATS]
+ * -> [LINK_XSTATS_TYPE_xxx]
+ *    -> [rtnl link type specific attributes]
+ */
+enum {
+	LINK_XSTATS_TYPE_UNSPEC,
+	LINK_XSTATS_TYPE_BRIDGE,
+	LINK_XSTATS_TYPE_BOND,
+	__LINK_XSTATS_TYPE_MAX
+};
+#define LINK_XSTATS_TYPE_MAX (__LINK_XSTATS_TYPE_MAX - 1)
+
+/* These are stats embedded into IFLA_STATS_LINK_OFFLOAD_XSTATS */
+enum {
+	IFLA_OFFLOAD_XSTATS_UNSPEC,
+	IFLA_OFFLOAD_XSTATS_CPU_HIT, /* struct rtnl_link_stats64 */
+	__IFLA_OFFLOAD_XSTATS_MAX
+};
+#define IFLA_OFFLOAD_XSTATS_MAX (__IFLA_OFFLOAD_XSTATS_MAX - 1)
+
+/* XDP section */
+
+#define XDP_FLAGS_UPDATE_IF_NOEXIST	(1U << 0)
+#define XDP_FLAGS_SKB_MODE		(1U << 1)
+#define XDP_FLAGS_DRV_MODE		(1U << 2)
+#define XDP_FLAGS_HW_MODE		(1U << 3)
+#define XDP_FLAGS_MODES			(XDP_FLAGS_SKB_MODE | \
+					 XDP_FLAGS_DRV_MODE | \
+					 XDP_FLAGS_HW_MODE)
+#define XDP_FLAGS_MASK			(XDP_FLAGS_UPDATE_IF_NOEXIST | \
+					 XDP_FLAGS_MODES)
+
+/* These are stored into IFLA_XDP_ATTACHED on dump. */
+enum {
+	XDP_ATTACHED_NONE = 0,
+	XDP_ATTACHED_DRV,
+	XDP_ATTACHED_SKB,
+	XDP_ATTACHED_HW,
+	XDP_ATTACHED_MULTI,
+};
+
+enum {
+	IFLA_XDP_UNSPEC,
+	IFLA_XDP_FD,
+	IFLA_XDP_ATTACHED,
+	IFLA_XDP_FLAGS,
+	IFLA_XDP_PROG_ID,
+	IFLA_XDP_DRV_PROG_ID,
+	IFLA_XDP_SKB_PROG_ID,
+	IFLA_XDP_HW_PROG_ID,
+	__IFLA_XDP_MAX,
+};
+
+#define IFLA_XDP_MAX (__IFLA_XDP_MAX - 1)
+
+enum {
+	IFLA_EVENT_NONE,
+	IFLA_EVENT_REBOOT,		/* internal reset / reboot */
+	IFLA_EVENT_FEATURES,		/* change in offload features */
+	IFLA_EVENT_BONDING_FAILOVER,	/* change in active slave */
+	IFLA_EVENT_NOTIFY_PEERS,	/* re-sent grat. arp/ndisc */
+	IFLA_EVENT_IGMP_RESEND,		/* re-sent IGMP JOIN */
+	IFLA_EVENT_BONDING_OPTIONS,	/* change in bonding options */
+};
+
+/* tun section */
+
+enum {
+	IFLA_TUN_UNSPEC,
+	IFLA_TUN_OWNER,
+	IFLA_TUN_GROUP,
+	IFLA_TUN_TYPE,
+	IFLA_TUN_PI,
+	IFLA_TUN_VNET_HDR,
+	IFLA_TUN_PERSIST,
+	IFLA_TUN_MULTI_QUEUE,
+	IFLA_TUN_NUM_QUEUES,
+	IFLA_TUN_NUM_DISABLED_QUEUES,
+	__IFLA_TUN_MAX,
+};
+
+#define IFLA_TUN_MAX (__IFLA_TUN_MAX - 1)
+
+/* rmnet section */
+
+#define RMNET_FLAGS_INGRESS_DEAGGREGATION         (1U << 0)
+#define RMNET_FLAGS_INGRESS_MAP_COMMANDS          (1U << 1)
+#define RMNET_FLAGS_INGRESS_MAP_CKSUMV4           (1U << 2)
+#define RMNET_FLAGS_EGRESS_MAP_CKSUMV4            (1U << 3)
+
+enum {
+	IFLA_RMNET_UNSPEC,
+	IFLA_RMNET_MUX_ID,
+	IFLA_RMNET_FLAGS,
+	__IFLA_RMNET_MAX,
+};
+
+#define IFLA_RMNET_MAX	(__IFLA_RMNET_MAX - 1)
+
+struct ifla_rmnet_flags {
+	__u32	flags;
+	__u32	mask;
+};
+
+#endif /* _UAPI_LINUX_IF_LINK_H */
diff --git a/src/contrib/libbpf/include/uapi/linux/if_xdp.h b/src/contrib/libbpf/include/uapi/linux/if_xdp.h
new file mode 100644
index 0000000..be328c5
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/if_xdp.h
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * if_xdp: XDP socket user-space interface
+ * Copyright(c) 2018 Intel Corporation.
+ *
+ * Author(s): Björn Töpel <bjorn.topel@intel.com>
+ *	      Magnus Karlsson <magnus.karlsson@intel.com>
+ */
+
+#ifndef _LINUX_IF_XDP_H
+#define _LINUX_IF_XDP_H
+
+#include <linux/types.h>
+
+/* Options for the sxdp_flags field */
+#define XDP_SHARED_UMEM	(1 << 0)
+#define XDP_COPY	(1 << 1) /* Force copy-mode */
+#define XDP_ZEROCOPY	(1 << 2) /* Force zero-copy mode */
+/* If this option is set, the driver might go sleep and in that case
+ * the XDP_RING_NEED_WAKEUP flag in the fill and/or Tx rings will be
+ * set. If it is set, the application need to explicitly wake up the
+ * driver with a poll() (Rx and Tx) or sendto() (Tx only). If you are
+ * running the driver and the application on the same core, you should
+ * use this option so that the kernel will yield to the user space
+ * application.
+ */
+#define XDP_USE_NEED_WAKEUP (1 << 3)
+
+/* Flags for xsk_umem_config flags */
+#define XDP_UMEM_UNALIGNED_CHUNK_FLAG (1 << 0)
+
+struct sockaddr_xdp {
+	__u16 sxdp_family;
+	__u16 sxdp_flags;
+	__u32 sxdp_ifindex;
+	__u32 sxdp_queue_id;
+	__u32 sxdp_shared_umem_fd;
+};
+
+/* XDP_RING flags */
+#define XDP_RING_NEED_WAKEUP (1 << 0)
+
+struct xdp_ring_offset {
+	__u64 producer;
+	__u64 consumer;
+	__u64 desc;
+	__u64 flags;
+};
+
+struct xdp_mmap_offsets {
+	struct xdp_ring_offset rx;
+	struct xdp_ring_offset tx;
+	struct xdp_ring_offset fr; /* Fill */
+	struct xdp_ring_offset cr; /* Completion */
+};
+
+/* XDP socket options */
+#define XDP_MMAP_OFFSETS		1
+#define XDP_RX_RING			2
+#define XDP_TX_RING			3
+#define XDP_UMEM_REG			4
+#define XDP_UMEM_FILL_RING		5
+#define XDP_UMEM_COMPLETION_RING	6
+#define XDP_STATISTICS			7
+#define XDP_OPTIONS			8
+
+struct xdp_umem_reg {
+	__u64 addr; /* Start of packet data area */
+	__u64 len; /* Length of packet data area */
+	__u32 chunk_size;
+	__u32 headroom;
+	__u32 flags;
+};
+
+struct xdp_statistics {
+	__u64 rx_dropped; /* Dropped for reasons other than invalid desc */
+	__u64 rx_invalid_descs; /* Dropped due to invalid descriptor */
+	__u64 tx_invalid_descs; /* Dropped due to invalid descriptor */
+};
+
+struct xdp_options {
+	__u32 flags;
+};
+
+/* Flags for the flags field of struct xdp_options */
+#define XDP_OPTIONS_ZEROCOPY (1 << 0)
+
+/* Pgoff for mmaping the rings */
+#define XDP_PGOFF_RX_RING			  0
+#define XDP_PGOFF_TX_RING		 0x80000000
+#define XDP_UMEM_PGOFF_FILL_RING	0x100000000ULL
+#define XDP_UMEM_PGOFF_COMPLETION_RING	0x180000000ULL
+
+/* Masks for unaligned chunks mode */
+#define XSK_UNALIGNED_BUF_OFFSET_SHIFT 48
+#define XSK_UNALIGNED_BUF_ADDR_MASK \
+	((1ULL << XSK_UNALIGNED_BUF_OFFSET_SHIFT) - 1)
+
+/* Rx/Tx descriptor */
+struct xdp_desc {
+	__u64 addr;
+	__u32 len;
+	__u32 options;
+};
+
+/* UMEM descriptor is __u64 */
+
+#endif /* _LINUX_IF_XDP_H */
diff --git a/src/contrib/libbpf/include/uapi/linux/netlink.h b/src/contrib/libbpf/include/uapi/linux/netlink.h
new file mode 100644
index 0000000..0a4d733
--- /dev/null
+++ b/src/contrib/libbpf/include/uapi/linux/netlink.h
@@ -0,0 +1,252 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI__LINUX_NETLINK_H
+#define _UAPI__LINUX_NETLINK_H
+
+#include <linux/kernel.h>
+#include <linux/socket.h> /* for __kernel_sa_family_t */
+#include <linux/types.h>
+
+#define NETLINK_ROUTE		0	/* Routing/device hook				*/
+#define NETLINK_UNUSED		1	/* Unused number				*/
+#define NETLINK_USERSOCK	2	/* Reserved for user mode socket protocols 	*/
+#define NETLINK_FIREWALL	3	/* Unused number, formerly ip_queue		*/
+#define NETLINK_SOCK_DIAG	4	/* socket monitoring				*/
+#define NETLINK_NFLOG		5	/* netfilter/iptables ULOG */
+#define NETLINK_XFRM		6	/* ipsec */
+#define NETLINK_SELINUX		7	/* SELinux event notifications */
+#define NETLINK_ISCSI		8	/* Open-iSCSI */
+#define NETLINK_AUDIT		9	/* auditing */
+#define NETLINK_FIB_LOOKUP	10	
+#define NETLINK_CONNECTOR	11
+#define NETLINK_NETFILTER	12	/* netfilter subsystem */
+#define NETLINK_IP6_FW		13
+#define NETLINK_DNRTMSG		14	/* DECnet routing messages */
+#define NETLINK_KOBJECT_UEVENT	15	/* Kernel messages to userspace */
+#define NETLINK_GENERIC		16
+/* leave room for NETLINK_DM (DM Events) */
+#define NETLINK_SCSITRANSPORT	18	/* SCSI Transports */
+#define NETLINK_ECRYPTFS	19
+#define NETLINK_RDMA		20
+#define NETLINK_CRYPTO		21	/* Crypto layer */
+#define NETLINK_SMC		22	/* SMC monitoring */
+
+#define NETLINK_INET_DIAG	NETLINK_SOCK_DIAG
+
+#define MAX_LINKS 32		
+
+struct sockaddr_nl {
+	__kernel_sa_family_t	nl_family;	/* AF_NETLINK	*/
+	unsigned short	nl_pad;		/* zero		*/
+	__u32		nl_pid;		/* port ID	*/
+       	__u32		nl_groups;	/* multicast groups mask */
+};
+
+struct nlmsghdr {
+	__u32		nlmsg_len;	/* Length of message including header */
+	__u16		nlmsg_type;	/* Message content */
+	__u16		nlmsg_flags;	/* Additional flags */
+	__u32		nlmsg_seq;	/* Sequence number */
+	__u32		nlmsg_pid;	/* Sending process port ID */
+};
+
+/* Flags values */
+
+#define NLM_F_REQUEST		0x01	/* It is request message. 	*/
+#define NLM_F_MULTI		0x02	/* Multipart message, terminated by NLMSG_DONE */
+#define NLM_F_ACK		0x04	/* Reply with ack, with zero or error code */
+#define NLM_F_ECHO		0x08	/* Echo this request 		*/
+#define NLM_F_DUMP_INTR		0x10	/* Dump was inconsistent due to sequence change */
+#define NLM_F_DUMP_FILTERED	0x20	/* Dump was filtered as requested */
+
+/* Modifiers to GET request */
+#define NLM_F_ROOT	0x100	/* specify tree	root	*/
+#define NLM_F_MATCH	0x200	/* return all matching	*/
+#define NLM_F_ATOMIC	0x400	/* atomic GET		*/
+#define NLM_F_DUMP	(NLM_F_ROOT|NLM_F_MATCH)
+
+/* Modifiers to NEW request */
+#define NLM_F_REPLACE	0x100	/* Override existing		*/
+#define NLM_F_EXCL	0x200	/* Do not touch, if it exists	*/
+#define NLM_F_CREATE	0x400	/* Create, if it does not exist	*/
+#define NLM_F_APPEND	0x800	/* Add to end of list		*/
+
+/* Modifiers to DELETE request */
+#define NLM_F_NONREC	0x100	/* Do not delete recursively	*/
+
+/* Flags for ACK message */
+#define NLM_F_CAPPED	0x100	/* request was capped */
+#define NLM_F_ACK_TLVS	0x200	/* extended ACK TVLs were included */
+
+/*
+   4.4BSD ADD		NLM_F_CREATE|NLM_F_EXCL
+   4.4BSD CHANGE	NLM_F_REPLACE
+
+   True CHANGE		NLM_F_CREATE|NLM_F_REPLACE
+   Append		NLM_F_CREATE
+   Check		NLM_F_EXCL
+ */
+
+#define NLMSG_ALIGNTO	4U
+#define NLMSG_ALIGN(len) ( ((len)+NLMSG_ALIGNTO-1) & ~(NLMSG_ALIGNTO-1) )
+#define NLMSG_HDRLEN	 ((int) NLMSG_ALIGN(sizeof(struct nlmsghdr)))
+#define NLMSG_LENGTH(len) ((len) + NLMSG_HDRLEN)
+#define NLMSG_SPACE(len) NLMSG_ALIGN(NLMSG_LENGTH(len))
+#define NLMSG_DATA(nlh)  ((void*)(((char*)nlh) + NLMSG_LENGTH(0)))
+#define NLMSG_NEXT(nlh,len)	 ((len) -= NLMSG_ALIGN((nlh)->nlmsg_len), \
+				  (struct nlmsghdr*)(((char*)(nlh)) + NLMSG_ALIGN((nlh)->nlmsg_len)))
+#define NLMSG_OK(nlh,len) ((len) >= (int)sizeof(struct nlmsghdr) && \
+			   (nlh)->nlmsg_len >= sizeof(struct nlmsghdr) && \
+			   (nlh)->nlmsg_len <= (len))
+#define NLMSG_PAYLOAD(nlh,len) ((nlh)->nlmsg_len - NLMSG_SPACE((len)))
+
+#define NLMSG_NOOP		0x1	/* Nothing.		*/
+#define NLMSG_ERROR		0x2	/* Error		*/
+#define NLMSG_DONE		0x3	/* End of a dump	*/
+#define NLMSG_OVERRUN		0x4	/* Data lost		*/
+
+#define NLMSG_MIN_TYPE		0x10	/* < 0x10: reserved control messages */
+
+struct nlmsgerr {
+	int		error;
+	struct nlmsghdr msg;
+	/*
+	 * followed by the message contents unless NETLINK_CAP_ACK was set
+	 * or the ACK indicates success (error == 0)
+	 * message length is aligned with NLMSG_ALIGN()
+	 */
+	/*
+	 * followed by TLVs defined in enum nlmsgerr_attrs
+	 * if NETLINK_EXT_ACK was set
+	 */
+};
+
+/**
+ * enum nlmsgerr_attrs - nlmsgerr attributes
+ * @NLMSGERR_ATTR_UNUSED: unused
+ * @NLMSGERR_ATTR_MSG: error message string (string)
+ * @NLMSGERR_ATTR_OFFS: offset of the invalid attribute in the original
+ *	 message, counting from the beginning of the header (u32)
+ * @NLMSGERR_ATTR_COOKIE: arbitrary subsystem specific cookie to
+ *	be used - in the success case - to identify a created
+ *	object or operation or similar (binary)
+ * @__NLMSGERR_ATTR_MAX: number of attributes
+ * @NLMSGERR_ATTR_MAX: highest attribute number
+ */
+enum nlmsgerr_attrs {
+	NLMSGERR_ATTR_UNUSED,
+	NLMSGERR_ATTR_MSG,
+	NLMSGERR_ATTR_OFFS,
+	NLMSGERR_ATTR_COOKIE,
+
+	__NLMSGERR_ATTR_MAX,
+	NLMSGERR_ATTR_MAX = __NLMSGERR_ATTR_MAX - 1
+};
+
+#define NETLINK_ADD_MEMBERSHIP		1
+#define NETLINK_DROP_MEMBERSHIP		2
+#define NETLINK_PKTINFO			3
+#define NETLINK_BROADCAST_ERROR		4
+#define NETLINK_NO_ENOBUFS		5
+#ifndef __KERNEL__
+#define NETLINK_RX_RING			6
+#define NETLINK_TX_RING			7
+#endif
+#define NETLINK_LISTEN_ALL_NSID		8
+#define NETLINK_LIST_MEMBERSHIPS	9
+#define NETLINK_CAP_ACK			10
+#define NETLINK_EXT_ACK			11
+#define NETLINK_GET_STRICT_CHK		12
+
+struct nl_pktinfo {
+	__u32	group;
+};
+
+struct nl_mmap_req {
+	unsigned int	nm_block_size;
+	unsigned int	nm_block_nr;
+	unsigned int	nm_frame_size;
+	unsigned int	nm_frame_nr;
+};
+
+struct nl_mmap_hdr {
+	unsigned int	nm_status;
+	unsigned int	nm_len;
+	__u32		nm_group;
+	/* credentials */
+	__u32		nm_pid;
+	__u32		nm_uid;
+	__u32		nm_gid;
+};
+
+#ifndef __KERNEL__
+enum nl_mmap_status {
+	NL_MMAP_STATUS_UNUSED,
+	NL_MMAP_STATUS_RESERVED,
+	NL_MMAP_STATUS_VALID,
+	NL_MMAP_STATUS_COPY,
+	NL_MMAP_STATUS_SKIP,
+};
+
+#define NL_MMAP_MSG_ALIGNMENT		NLMSG_ALIGNTO
+#define NL_MMAP_MSG_ALIGN(sz)		__ALIGN_KERNEL(sz, NL_MMAP_MSG_ALIGNMENT)
+#define NL_MMAP_HDRLEN			NL_MMAP_MSG_ALIGN(sizeof(struct nl_mmap_hdr))
+#endif
+
+#define NET_MAJOR 36		/* Major 36 is reserved for networking 						*/
+
+enum {
+	NETLINK_UNCONNECTED = 0,
+	NETLINK_CONNECTED,
+};
+
+/*
+ *  <------- NLA_HDRLEN ------> <-- NLA_ALIGN(payload)-->
+ * +---------------------+- - -+- - - - - - - - - -+- - -+
+ * |        Header       | Pad |     Payload       | Pad |
+ * |   (struct nlattr)   | ing |                   | ing |
+ * +---------------------+- - -+- - - - - - - - - -+- - -+
+ *  <-------------- nlattr->nla_len -------------->
+ */
+
+struct nlattr {
+	__u16           nla_len;
+	__u16           nla_type;
+};
+
+/*
+ * nla_type (16 bits)
+ * +---+---+-------------------------------+
+ * | N | O | Attribute Type                |
+ * +---+---+-------------------------------+
+ * N := Carries nested attributes
+ * O := Payload stored in network byte order
+ *
+ * Note: The N and O flag are mutually exclusive.
+ */
+#define NLA_F_NESTED		(1 << 15)
+#define NLA_F_NET_BYTEORDER	(1 << 14)
+#define NLA_TYPE_MASK		~(NLA_F_NESTED | NLA_F_NET_BYTEORDER)
+
+#define NLA_ALIGNTO		4
+#define NLA_ALIGN(len)		(((len) + NLA_ALIGNTO - 1) & ~(NLA_ALIGNTO - 1))
+#define NLA_HDRLEN		((int) NLA_ALIGN(sizeof(struct nlattr)))
+
+/* Generic 32 bitflags attribute content sent to the kernel.
+ *
+ * The value is a bitmap that defines the values being set
+ * The selector is a bitmask that defines which value is legit
+ *
+ * Examples:
+ *  value = 0x0, and selector = 0x1
+ *  implies we are selecting bit 1 and we want to set its value to 0.
+ *
+ *  value = 0x2, and selector = 0x2
+ *  implies we are selecting bit 2 and we want to set its value to 1.
+ *
+ */
+struct nla_bitfield32 {
+	__u32 value;
+	__u32 selector;
+};
+
+#endif /* _UAPI__LINUX_NETLINK_H */
diff --git a/src/contrib/licenses/0BSD b/src/contrib/licenses/0BSD
new file mode 100644
index 0000000..56c5528
--- /dev/null
+++ b/src/contrib/licenses/0BSD
@@ -0,0 +1,12 @@
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
diff --git a/src/contrib/licenses/BSD-3-Clause b/src/contrib/licenses/BSD-3-Clause
new file mode 100644
index 0000000..8041f21
--- /dev/null
+++ b/src/contrib/licenses/BSD-3-Clause
@@ -0,0 +1,21 @@
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+3. Neither the name of the copyright holder nor the names of its contributors
+   may be used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
+INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
+OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/src/contrib/licenses/LGPL-2.0 b/src/contrib/licenses/LGPL-2.0
new file mode 100644
index 0000000..d159169
--- /dev/null
+++ b/src/contrib/licenses/LGPL-2.0
@@ -0,0 +1,339 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+                            Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Lesser General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
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+
+  Finally, any free program is threatened constantly by software
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+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+                    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
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+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
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+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
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+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
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+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
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+These requirements apply to the modified work as a whole.  If
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diff --git a/src/contrib/licenses/LGPL-2.1 b/src/contrib/licenses/LGPL-2.1
new file mode 100644
index 0000000..27bb434
--- /dev/null
+++ b/src/contrib/licenses/LGPL-2.1
@@ -0,0 +1,503 @@
+Valid-License-Identifier: LGPL-2.1
+Valid-License-Identifier: LGPL-2.1+
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+
+14. If you wish to incorporate parts of the Library into other free
+    programs whose distribution conditions are incompatible with these,
+    write to the author to ask for permission. For software which is
+    copyrighted by the Free Software Foundation, write to the Free Software
+    Foundation; we sometimes make exceptions for this. Our decision will be
+    guided by the two goals of preserving the free status of all
+    derivatives of our free software and of promoting the sharing and reuse
+    of software generally.
+
+NO WARRANTY
+
+15. BECAUSE THE LIBRARY IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+    FOR THE LIBRARY, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN
+    OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+    PROVIDE THE LIBRARY "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER
+    EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+    WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE
+    ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE LIBRARY IS WITH
+    YOU. SHOULD THE LIBRARY PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL
+    NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+16. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+    WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+    REDISTRIBUTE THE LIBRARY AS PERMITTED ABOVE, BE LIABLE TO YOU FOR
+    DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL
+    DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE LIBRARY
+    (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED
+    INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF
+    THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR
+    OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
+
+END OF TERMS AND CONDITIONS
+
+How to Apply These Terms to Your New Libraries
+
+If you develop a new library, and you want it to be of the greatest
+possible use to the public, we recommend making it free software that
+everyone can redistribute and change. You can do so by permitting
+redistribution under these terms (or, alternatively, under the terms of the
+ordinary General Public License).
+
+To apply these terms, attach the following notices to the library. It is
+safest to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least the
+"copyright" line and a pointer to where the full notice is found.
+
+one line to give the library's name and an idea of what it does.
+Copyright (C) year name of author
+
+This library is free software; you can redistribute it and/or modify it
+under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or (at
+your option) any later version.
+
+This library is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+for more details.
+
+You should have received a copy of the GNU Lesser General Public License
+along with this library; if not, write to the Free Software Foundation,
+Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA Also add
+information on how to contact you by electronic and paper mail.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the library, if
+necessary. Here is a sample; alter the names:
+
+Yoyodyne, Inc., hereby disclaims all copyright interest in
+the library `Frob' (a library for tweaking knobs) written
+by James Random Hacker.
+
+signature of Ty Coon, 1 April 1990
+Ty Coon, President of Vice
+That's all there is to it!
diff --git a/src/contrib/macros.h b/src/contrib/macros.h
new file mode 100644
index 0000000..39a5f27
--- /dev/null
+++ b/src/contrib/macros.h
@@ -0,0 +1,44 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Common macros.
+ */
+
+#pragma once
+
+/*! \brief Eliminate compiler warning with unused parameters. */
+#define UNUSED(param) (void)(param)
+
+#ifndef MIN
+/*! \brief Type-safe minimum macro. */
+#define MIN(a, b) \
+	({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); _a < _b ? _a : _b; })
+
+/*! \brief Type-safe maximum macro. */
+#define MAX(a, b) \
+	({ __typeof__ (a) _a = (a); __typeof__ (b) _b = (b); _a > _b ? _a : _b; })
+#endif
+
+#ifndef likely
+/*! \brief Optimize for x to be true value. */
+#define likely(x) __builtin_expect((x), 1)
+#endif
+
+#ifndef unlikely
+/*! \brief Optimize for x to be false value. */
+#define unlikely(x) __builtin_expect((x), 0)
+#endif
diff --git a/src/contrib/mempattern.c b/src/contrib/mempattern.c
new file mode 100644
index 0000000..f57139d
--- /dev/null
+++ b/src/contrib/mempattern.c
@@ -0,0 +1,122 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdlib.h>
+
+#include "contrib/mempattern.h"
+#include "contrib/string.h"
+#include "contrib/ucw/mempool.h"
+
+static void mm_nofree(void *p)
+{
+	/* nop */
+}
+
+static void *mm_malloc(void *ctx, size_t n)
+{
+	(void)ctx;
+	return malloc(n);
+}
+
+void *mm_alloc(knot_mm_t *mm, size_t size)
+{
+	if (mm) {
+		return mm->alloc(mm->ctx, size);
+	} else {
+		return malloc(size);
+	}
+}
+
+void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size)
+{
+	if (nmemb == 0 || size == 0) {
+		return NULL;
+	}
+	if (mm) {
+		size_t total_size = nmemb * size;
+		if (total_size / nmemb != size) { // Overflow check
+			return NULL;
+		}
+		void *mem = mm_alloc(mm, total_size);
+		if (mem == NULL) {
+			return NULL;
+		}
+		return memzero(mem, total_size);
+	} else {
+		return calloc(nmemb, size);
+	}
+}
+
+void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size)
+{
+	if (mm) {
+		void *p = mm->alloc(mm->ctx, size);
+		if (p == NULL) {
+			return NULL;
+		} else {
+			if (what) {
+				memcpy(p, what,
+				       prev_size < size ? prev_size : size);
+			}
+			mm_free(mm, what);
+			return p;
+		}
+	} else {
+		return realloc(what, size);
+	}
+}
+
+char *mm_strdup(knot_mm_t *mm, const char *s)
+{
+	if (s == NULL) {
+		return NULL;
+	}
+	if (mm) {
+		size_t len = strlen(s) + 1;
+		void *mem = mm_alloc(mm, len);
+		if (mem == NULL) {
+			return NULL;
+		}
+		return memcpy(mem, s, len);
+	} else {
+		return strdup(s);
+	}
+}
+
+void mm_free(knot_mm_t *mm, void *what)
+{
+	if (mm) {
+		if (mm->free) {
+			mm->free(what);
+		}
+	} else {
+		free(what);
+	}
+}
+
+void mm_ctx_init(knot_mm_t *mm)
+{
+	mm->ctx = NULL;
+	mm->alloc = mm_malloc;
+	mm->free = free;
+}
+
+void mm_ctx_mempool(knot_mm_t *mm, size_t chunk_size)
+{
+	mm->ctx = mp_new(chunk_size);
+	mm->alloc = (knot_mm_alloc_t)mp_alloc;
+	mm->free = mm_nofree;
+}
diff --git a/src/contrib/mempattern.h b/src/contrib/mempattern.h
new file mode 100644
index 0000000..c74f983
--- /dev/null
+++ b/src/contrib/mempattern.h
@@ -0,0 +1,47 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Memory allocation related functions.
+ */
+
+#pragma once
+
+#include "libknot/mm_ctx.h"
+
+/*! \brief Default memory block size. */
+#define MM_DEFAULT_BLKSIZE 4096
+
+/*! \brief Allocs using 'mm' if any, uses system malloc() otherwise. */
+void *mm_alloc(knot_mm_t *mm, size_t size);
+
+/*! \brief Callocs using 'mm' if any, uses system calloc() otherwise. */
+void *mm_calloc(knot_mm_t *mm, size_t nmemb, size_t size);
+
+/*! \brief Reallocs using 'mm' if any, uses system realloc() otherwise. */
+void *mm_realloc(knot_mm_t *mm, void *what, size_t size, size_t prev_size);
+
+/*! \brief Strdups using 'mm' if any, uses system strdup() otherwise. */
+char *mm_strdup(knot_mm_t *mm, const char *s);
+
+/*! \brief Free using 'mm' if any, uses system free() otherwise. */
+void mm_free(knot_mm_t *mm, void *what);
+
+/*! \brief Initialize default memory allocation context. */
+void mm_ctx_init(knot_mm_t *mm);
+
+/*! \brief Memory pool context. */
+void mm_ctx_mempool(knot_mm_t *mm, size_t chunk_size);
diff --git a/src/contrib/net.c b/src/contrib/net.c
new file mode 100644
index 0000000..d0fd114
--- /dev/null
+++ b/src/contrib/net.c
@@ -0,0 +1,649 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <netinet/in.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <sys/socket.h>
+#include <sys/uio.h>
+#include <unistd.h>
+
+#include "libknot/errcode.h"
+#include "contrib/macros.h"
+#include "contrib/net.h"
+#include "contrib/sockaddr.h"
+#include "contrib/time.h"
+
+/*
+ * OS X doesn't support MSG_NOSIGNAL. Use SO_NOSIGPIPE socket option instead.
+ */
+#if defined(__APPLE__) && !defined(MSG_NOSIGNAL)
+#  define MSG_NOSIGNAL 0
+#  define osx_block_sigpipe(sock) sockopt_enable(sock, SOL_SOCKET, SO_NOSIGPIPE)
+#else
+#  define osx_block_sigpipe(sock) KNOT_EOK
+#endif
+
+/*!
+ * \brief Enable socket option.
+ */
+static int sockopt_enable(int sock, int level, int optname)
+{
+	const int enable = 1;
+	if (setsockopt(sock, level, optname, &enable, sizeof(enable)) != 0) {
+		return knot_map_errno();
+	}
+
+	return KNOT_EOK;
+}
+
+/*!
+ * \brief Create a non-blocking socket.
+ *
+ * Prefer SOCK_NONBLOCK if available to save one fcntl() syscall.
+ *
+ */
+static int socket_create(int family, int type, int proto)
+{
+#ifdef SOCK_NONBLOCK
+	type |= SOCK_NONBLOCK;
+#endif
+	int sock = socket(family, type, proto);
+	if (sock < 0) {
+		return knot_map_errno();
+	}
+
+#ifndef SOCK_NONBLOCK
+	if (fcntl(sock, F_SETFL, O_NONBLOCK) != 0) {
+		int ret = knot_map_errno();
+		close(sock);
+		return ret;
+	}
+#endif
+
+	int ret = osx_block_sigpipe(sock);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	return sock;
+}
+
+int net_unbound_socket(int type, const struct sockaddr_storage *addr)
+{
+	if (addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Create socket. */
+	return socket_create(addr->ss_family, type, 0);
+}
+
+struct option {
+	int level;
+	int name;
+};
+
+/*!
+ * \brief Get setsock option for binding non-local address.
+ */
+static const struct option *nonlocal_option(int family)
+{
+	static const struct option ipv4 = {
+		#if defined(IP_FREEBIND)
+			IPPROTO_IP, IP_FREEBIND
+		#elif defined(IP_BINDANY)
+			IPPROTO_IP, IP_BINDANY
+		#else
+			0, 0
+		#endif
+	};
+
+	static const struct option ipv6 = {
+		#if defined(IP_FREEBIND)
+			IPPROTO_IP, IP_FREEBIND
+		#elif defined(IPV6_BINDANY)
+			IPPROTO_IPV6, IPV6_BINDANY
+		#else
+			0, 0
+		#endif
+
+	};
+
+	switch (family) {
+	case AF_INET:  return &ipv4;
+	case AF_INET6: return &ipv6;
+	default:
+		return NULL;
+	}
+}
+
+static int enable_nonlocal(int sock, int family)
+{
+	const struct option *opt = nonlocal_option(family);
+	if (opt == NULL || opt->name == 0) {
+		return KNOT_ENOTSUP;
+	}
+
+	return sockopt_enable(sock, opt->level, opt->name);
+}
+
+static int enable_reuseport(int sock)
+{
+#ifdef ENABLE_REUSEPORT
+#  if defined(__FreeBSD__)
+	return sockopt_enable(sock, SOL_SOCKET, SO_REUSEPORT_LB);
+#  else
+	return sockopt_enable(sock, SOL_SOCKET, SO_REUSEPORT);
+#  endif
+#else
+	return KNOT_ENOTSUP;
+#endif
+}
+
+static void unlink_unix_socket(const struct sockaddr_storage *addr)
+{
+	char path[SOCKADDR_STRLEN] = { 0 };
+	sockaddr_tostr(path, sizeof(path), addr);
+	unlink(path);
+}
+
+int net_bound_socket(int type, const struct sockaddr_storage *addr, enum net_flags flags)
+{
+	/* Create socket. */
+	int sock = net_unbound_socket(type, addr);
+	if (sock < 0) {
+		return sock;
+	}
+
+	/* Unlink UNIX sock if exists. */
+	if (addr->ss_family == AF_UNIX) {
+		unlink_unix_socket(addr);
+	}
+
+	/* Reuse old address if taken. */
+	int ret = sockopt_enable(sock, SOL_SOCKET, SO_REUSEADDR);
+	if (ret != KNOT_EOK) {
+		close(sock);
+		return ret;
+	}
+
+	/* Don't bind IPv4 for IPv6 any address. */
+	if (addr->ss_family == AF_INET6) {
+		ret = sockopt_enable(sock, IPPROTO_IPV6, IPV6_V6ONLY);
+		if (ret != KNOT_EOK) {
+			close(sock);
+			return ret;
+		}
+	}
+
+	/* Allow bind to non-local address. */
+	if (flags & NET_BIND_NONLOCAL) {
+		ret = enable_nonlocal(sock, addr->ss_family);
+		if (ret != KNOT_EOK) {
+			close(sock);
+			return ret;
+		}
+	}
+
+	/* Allow to bind the same address by multiple threads. */
+	if (flags & NET_BIND_MULTIPLE) {
+		ret = enable_reuseport(sock);
+		if (ret != KNOT_EOK) {
+			close(sock);
+			return ret;
+		}
+	}
+
+	/* Bind to specified address. */
+	ret = bind(sock, (const struct sockaddr *)addr, sockaddr_len(addr));
+	if (ret < 0) {
+		ret = knot_map_errno();
+		close(sock);
+		return ret;
+	}
+
+	return sock;
+}
+
+int net_connected_socket(int type, const struct sockaddr_storage *dst_addr,
+                         const struct sockaddr_storage *src_addr)
+{
+	if (dst_addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Check port. */
+	if (sockaddr_port(dst_addr) == 0) {
+		return KNOT_NET_EADDR;
+	}
+
+	/* Bind to specific source address - if set. */
+	int sock = -1;
+	if (src_addr && src_addr->ss_family != AF_UNSPEC) {
+		sock = net_bound_socket(type, src_addr, 0);
+	} else {
+		sock = net_unbound_socket(type, dst_addr);
+	}
+	if (sock < 0) {
+		return sock;
+	}
+
+	/* Connect to destination. */
+	int ret = connect(sock, (const struct sockaddr *)dst_addr, sockaddr_len(dst_addr));
+	if (ret != 0 && errno != EINPROGRESS) {
+		ret = knot_map_errno();
+		close(sock);
+		return ret;
+	}
+
+	return sock;
+}
+
+bool net_is_connected(int sock)
+{
+	struct sockaddr_storage addr;
+	socklen_t len = sizeof(addr);
+	return (getpeername(sock, (struct sockaddr *)&addr, &len) == 0);
+}
+
+int net_socktype(int sock)
+{
+	int type;
+	socklen_t size = sizeof(type);
+
+	if (getsockopt(sock, SOL_SOCKET, SO_TYPE, &type, &size) == 0) {
+		return type;
+	} else {
+		return AF_UNSPEC;
+	}
+}
+
+bool net_is_stream(int sock)
+{
+	return net_socktype(sock) == SOCK_STREAM;
+}
+
+int net_accept(int sock, struct sockaddr_storage *addr)
+{
+	socklen_t len = sizeof(*addr);
+	socklen_t *addr_len = (addr != NULL) ? &len : NULL;
+
+	int remote = -1;
+
+#if defined(HAVE_ACCEPT4) && defined(SOCK_NONBLOCK)
+	remote = accept4(sock, (struct sockaddr *)addr, addr_len, SOCK_NONBLOCK);
+	if (remote < 0) {
+		return knot_map_errno();
+	}
+#else
+	remote = accept(sock, (struct sockaddr *)addr, addr_len);
+	if (fcntl(remote, F_SETFL, O_NONBLOCK) != 0) {
+		int error = knot_map_errno();
+		close(remote);
+		return error;
+	}
+#endif
+
+	return remote;
+}
+
+/* -- I/O interface handling partial  -------------------------------------- */
+
+/*!
+ * \brief Perform \a poll() on one socket.
+ */
+static int poll_one(int fd, int events, int timeout_ms)
+{
+	struct pollfd pfd = {
+		.fd = fd,
+		.events = events
+	};
+
+	return poll(&pfd, 1, timeout_ms);
+}
+
+/*!
+ * \brief Check if we should wait for I/O readiness.
+ *
+ * \param error  \a errno set by the failed I/O operation.
+ */
+static bool io_should_wait(int error)
+{
+	if (error == EAGAIN || error == EWOULDBLOCK ||	/* Socket data not ready. */
+	    error == ENOMEM || error == ENOBUFS) {	/* Insufficient resources. */
+		return true;
+	}
+
+#ifndef __linux__
+	/* FreeBSD: connection in progress. */
+	if (error == ENOTCONN) {
+		return true;
+	}
+#endif
+
+	return false;
+}
+
+/*!
+ * \brief Check if we should wait again.
+ *
+ * \param error  \a errno set by the failed wait operation.
+ */
+static bool wait_should_retry(int error)
+{
+	if (error == EINTR ||				/* System call interrupted. */
+	    error == EAGAIN || error == ENOMEM) {	/* Insufficient resources. */
+		return true;
+	}
+	return false;
+}
+
+/*!
+ * \brief I/O operation callbacks.
+ */
+struct io {
+	ssize_t (*process)(int sockfd, struct msghdr *msg);
+	int (*wait)(int sockfd, int timeout_ms);
+};
+
+/*!
+ * \brief Get total size of I/O vector in a message.
+ */
+static size_t msg_iov_len(const struct msghdr *msg)
+{
+	size_t total = 0;
+
+	for (int i = 0; i < msg->msg_iovlen; i++) {
+		total += msg->msg_iov[i].iov_len;
+	}
+
+	return total;
+}
+
+/*!
+ * \brief Shift processed data out of message IO vectors.
+ */
+static void msg_iov_shift(struct msghdr *msg, size_t done)
+{
+	struct iovec *iov = msg->msg_iov;
+	int iovlen = msg->msg_iovlen;
+
+	for (int i = 0; i < iovlen && done > 0; i++) {
+		if (iov[i].iov_len > done) {
+			iov[i].iov_base += done;
+			iov[i].iov_len -= done;
+			done = 0;
+		} else {
+			done -= iov[i].iov_len;
+			msg->msg_iov += 1;
+			msg->msg_iovlen -= 1;
+		}
+	}
+
+	assert(done == 0);
+}
+
+#define TIMEOUT_CTX_INIT \
+	struct timespec begin, end; \
+	if (*timeout_ptr > 0) { \
+		clock_gettime(CLOCK_MONOTONIC, &begin); \
+	}
+
+#define TIMEOUT_CTX_UPDATE \
+	if (*timeout_ptr > 0) { \
+		clock_gettime(CLOCK_MONOTONIC, &end); \
+		int running_ms = time_diff_ms(&begin, &end); \
+		*timeout_ptr = MAX(*timeout_ptr - running_ms, 0); \
+	}
+
+/*!
+ * \brief Perform an I/O operation with a socket with waiting.
+ *
+ * \param oneshot  If set, doesn't wait until the buffer is fully processed.
+ */
+static ssize_t io_exec(const struct io *io, int fd, struct msghdr *msg,
+                       bool oneshot, int *timeout_ptr)
+{
+	size_t done = 0;
+	size_t total = msg_iov_len(msg);
+
+	for (;;) {
+		/* Perform I/O. */
+		ssize_t ret = io->process(fd, msg);
+		if (ret == -1 && errno == EINTR) {
+			continue;
+		}
+		if (ret > 0) {
+			done += ret;
+			if (oneshot || done == total) {
+				break;
+			}
+			msg_iov_shift(msg, ret);
+		}
+
+		/* Wait for data readiness. */
+		if (ret > 0 || (ret == -1 && io_should_wait(errno))) {
+			for (;;) {
+				TIMEOUT_CTX_INIT
+
+				ret = io->wait(fd, *timeout_ptr);
+
+				if (ret == 1) {
+					TIMEOUT_CTX_UPDATE
+					/* Ready, retry process. */
+					break;
+				} else if (ret == -1 && wait_should_retry(errno)) {
+					TIMEOUT_CTX_UPDATE
+					/* Interrupted or transient error, continue waiting. */
+					continue;
+				} else if (ret == 0) {
+					/* Timeouted, exit. */
+					return KNOT_ETIMEOUT;
+				} else {
+					/* In specific circumstances with Valgrind,
+					 * poll() returns wrong value.
+					 */
+					assert(ret <= 1);
+					assert(ret >= -1);
+					/* Other error, exit. */
+					return KNOT_ECONN;
+				}
+			}
+		} else {
+			/* Disconnect or error. */
+			return KNOT_ECONN;
+		}
+	}
+
+	return done;
+}
+
+static ssize_t recv_process(int fd, struct msghdr *msg)
+{
+	return recvmsg(fd, msg, MSG_DONTWAIT | MSG_NOSIGNAL);
+}
+
+static int recv_wait(int fd, int timeout_ms)
+{
+	return poll_one(fd, POLLIN, timeout_ms);
+}
+
+static ssize_t recv_data(int sock, struct msghdr *msg, bool oneshot, int *timeout_ptr)
+{
+	static const struct io RECV_IO = {
+		.process = recv_process,
+		.wait = recv_wait
+	};
+
+	return io_exec(&RECV_IO, sock, msg, oneshot, timeout_ptr);
+}
+
+static ssize_t send_process(int fd, struct msghdr *msg)
+{
+	return sendmsg(fd, msg, MSG_NOSIGNAL);
+}
+
+static int send_wait(int fd, int timeout_ms)
+{
+	return poll_one(fd, POLLOUT, timeout_ms);
+}
+
+static ssize_t send_data(int sock, struct msghdr *msg, int *timeout_ptr)
+{
+	static const struct io SEND_IO = {
+		.process = send_process,
+		.wait = send_wait
+	};
+
+	return io_exec(&SEND_IO, sock, msg, false, timeout_ptr);
+}
+
+/* -- generic stream and datagram I/O -------------------------------------- */
+
+ssize_t net_base_send(int sock, const uint8_t *buffer, size_t size,
+                      const struct sockaddr_storage *addr, int timeout_ms)
+{
+	if (sock < 0 || buffer == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct iovec iov = { 0 };
+	iov.iov_base = (void *)buffer;
+	iov.iov_len = size;
+
+	struct msghdr msg = { 0 };
+	msg.msg_name = (void *)addr;
+	msg.msg_namelen = sockaddr_len(addr);
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	int ret = send_data(sock, &msg, &timeout_ms);
+	if (ret < 0) {
+		return ret;
+	} else if (ret != size) {
+		return KNOT_ECONN;
+	}
+
+	return ret;
+}
+
+ssize_t net_base_recv(int sock, uint8_t *buffer, size_t size,
+                      struct sockaddr_storage *addr, int timeout_ms)
+{
+	if (sock < 0 || buffer == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct iovec iov = { 0 };
+	iov.iov_base = buffer;
+	iov.iov_len = size;
+
+	struct msghdr msg = { 0 };
+	msg.msg_name = (void *)addr;
+	msg.msg_namelen = addr ? sizeof(*addr) : 0;
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	return recv_data(sock, &msg, true, &timeout_ms);
+}
+
+ssize_t net_dgram_send(int sock, const uint8_t *buffer, size_t size,
+                       const struct sockaddr_storage *addr)
+{
+	return net_base_send(sock, buffer, size, addr, 0);
+}
+
+ssize_t net_dgram_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms)
+{
+	return net_base_recv(sock, buffer, size, NULL, timeout_ms);
+}
+
+ssize_t net_stream_send(int sock, const uint8_t *buffer, size_t size, int timeout_ms)
+{
+	return net_base_send(sock, buffer, size, NULL, timeout_ms);
+}
+
+ssize_t net_stream_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms)
+{
+	return net_base_recv(sock, buffer, size, NULL, timeout_ms);
+}
+
+/* -- DNS specific I/O ----------------------------------------------------- */
+
+ssize_t net_dns_tcp_send(int sock, const uint8_t *buffer, size_t size, int timeout_ms)
+{
+	if (sock < 0 || buffer == NULL || size > UINT16_MAX) {
+		return KNOT_EINVAL;
+	}
+
+	struct iovec iov[2];
+	uint16_t pktsize = htons(size);
+	iov[0].iov_base = &pktsize;
+	iov[0].iov_len = sizeof(uint16_t);
+	iov[1].iov_base = (void *)buffer;
+	iov[1].iov_len = size;
+
+	struct msghdr msg = { 0 };
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 2;
+
+	ssize_t ret = send_data(sock, &msg, &timeout_ms);
+	if (ret < 0) {
+		return ret;
+	}
+
+	return size; /* Do not count the size prefix. */
+}
+
+ssize_t net_dns_tcp_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms)
+{
+	if (sock < 0 || buffer == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct iovec iov = { 0 };
+	struct msghdr msg = { 0 };
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+
+	/* Receive size. */
+	uint16_t pktsize = 0;
+	iov.iov_base = &pktsize;
+	iov.iov_len = sizeof(pktsize);
+
+	int ret = recv_data(sock, &msg, false, &timeout_ms);
+	if (ret != sizeof(pktsize)) {
+		return ret;
+	}
+	pktsize = ntohs(pktsize);
+
+	/* Check packet size */
+	if (size < pktsize) {
+		return KNOT_ESPACE;
+	}
+
+	/* Receive payload. */
+	msg.msg_iov = &iov;
+	msg.msg_iovlen = 1;
+	iov.iov_base = buffer;
+	iov.iov_len = pktsize;
+
+	return recv_data(sock, &msg, false, &timeout_ms);
+}
diff --git a/src/contrib/net.h b/src/contrib/net.h
new file mode 100644
index 0000000..b233deb
--- /dev/null
+++ b/src/contrib/net.h
@@ -0,0 +1,185 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/socket.h>
+
+/*!
+ * \brief Network interface flags.
+ */
+enum net_flags {
+	NET_BIND_NONLOCAL = (1 << 0), //!< Allow to bind unavailable address.
+	NET_BIND_MULTIPLE = (1 << 1), //!< Allow to bind address multiple times.
+};
+
+/*!
+ * \brief Create unbound socket of given family and type.
+ *
+ * \note The socket is set to non-blocking mode.
+ *
+ * \param type  Socket transport type (SOCK_STREAM, SOCK_DGRAM).
+ * \param addr  Socket address.
+ *
+ * \return socket or error code
+ */
+int net_unbound_socket(int type, const struct sockaddr_storage *addr);
+
+/*!
+ * \brief Create socket bound to given address.
+ *
+ * The socket is set to non-blocking mode.
+ *
+ * \param type   Socket transport type (SOCK_STREAM, SOCK_DGRAM).
+ * \param addr   Socket address.
+ * \param flags  Socket binding options.
+ *
+ * \return socket or error code
+ */
+int net_bound_socket(int type, const struct sockaddr_storage *addr, enum net_flags flags);
+
+/*!
+ * \brief Create socket connected (asynchronously) to destination address.
+ *
+ * \note The socket is set to non-blocking mode.
+ *
+ * \param type      Socket transport type (SOCK_STREAM, SOCK_DGRAM).
+ * \param dst_addr  Destination address.
+ * \param src_addr  Source address (can be NULL).
+ *
+ * \return socket or error code
+ */
+int net_connected_socket(int type, const struct sockaddr_storage *dst_addr,
+                         const struct sockaddr_storage *src_addr);
+
+/*!
+ * \brief Return true if the socket is fully connected.
+ *
+ * \param sock  Socket.
+ *
+ * \return true if connected
+ */
+bool net_is_connected(int sock);
+
+/*!
+ * \brief Get socket type (e.g. \a SOCK_STREAM).
+ *
+ * \param sock  Socket.
+ */
+int net_socktype(int sock);
+
+/*!
+ * \brief Check if socket is a SOCK_STREAM socket.
+ */
+bool net_is_stream(int sock);
+
+/*!
+ * \brief Accept a connection on a listening socket.
+ *
+ * \brief The socket is set to non-blocking mode.
+ *
+ * \param sock  Socket
+ * \param addr  Remote address (can be NULL).
+ *
+ * \return socket or error code
+ */
+int net_accept(int sock, struct sockaddr_storage *addr);
+
+/*!
+ * \brief Send a message on a socket.
+ *
+ * The socket can be SOCK_STREAM or SOCK_DGRAM.
+ *
+ * The implementation handles partial-writes automatically.
+ *
+ * \param[in] sock        Socket.
+ * \param[in] buffer      Message buffer.
+ * \param[in] size        Size of the message.
+ * \param[in] addr        Remote address (ignored for SOCK_STREAM).
+ * \param[in] timeout_ms  Write timeout in miliseconds (-1 for infinity,
+ *                        not valid for SOCK_DGRAM).
+ *
+ * \return Number of bytes sent or negative error code.
+ */
+ssize_t net_base_send(int sock, const uint8_t *buffer, size_t size,
+                      const struct sockaddr_storage *addr, int timeout_ms);
+
+/*!
+ * \brief Receive a message from a socket.
+ *
+ * \param[in]  sock        Socket.
+ * \param[out] buffer      Receiving buffer.
+ * \param[in]  size        Capacity of the receiving buffer.
+ * \param[out] addr        Remote address (can be NULL).
+ * \param[in]  timeout_ms  Read timeout in miliseconds (-1 for infinity).
+ *
+ * \return Number of bytes read or negative error code.
+ */
+ssize_t net_base_recv(int sock, uint8_t *buffer, size_t size,
+                      struct sockaddr_storage *addr, int timeout_ms);
+
+/*!
+ * \brief Send a message on a SOCK_DGRAM socket.
+ *
+ * \see net_base_send
+ */
+ssize_t net_dgram_send(int sock, const uint8_t *buffer, size_t size,
+                       const struct sockaddr_storage *addr);
+
+/*!
+ * \brief Receive a message from a SOCK_DGRAM socket.
+ *
+ * \see net_base_recv
+ */
+ssize_t net_dgram_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms);
+
+/*!
+ * \brief Send a message on a SOCK_STREAM socket.
+ *
+ * \see net_base_send
+ */
+ssize_t net_stream_send(int sock, const uint8_t *buffer, size_t size, int timeout_ms);
+
+/*!
+ * \brief Receive a message from a SOCK_STREAM socket.
+ *
+ * \see net_base_recv
+ */
+ssize_t net_stream_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms);
+
+/*!
+ * \brief Send a DNS message on a TCP socket.
+ *
+ * The outgoing message is prefixed with a two-byte value carrying the DNS
+ * message size according to the specification. These two bytes are not
+ * reflected in the return value.
+ *
+ * \see net_base_send
+ */
+ssize_t net_dns_tcp_send(int sock, const uint8_t *buffer, size_t size, int timeout_ms);
+
+/*!
+ * \brief Receive a DNS message from a TCP socket.
+ *
+ * The first two bytes of the incoming message are interpreted as a DNS message
+ * size according to the specification. These two bytes are not included in
+ * the returned size. Only a complete DNS message is retrieved.
+ *
+ * \see net_base_recv
+ */
+ssize_t net_dns_tcp_recv(int sock, uint8_t *buffer, size_t size, int timeout_ms);
diff --git a/src/contrib/openbsd/LICENSE b/src/contrib/openbsd/LICENSE
new file mode 100644
index 0000000..e9a1aaa
--- /dev/null
+++ b/src/contrib/openbsd/LICENSE
@@ -0,0 +1,2 @@
+../licenses/0BSD
+../licenses/BSD-3-Clause
\ No newline at end of file
diff --git a/src/contrib/openbsd/siphash.c b/src/contrib/openbsd/siphash.c
new file mode 100644
index 0000000..26b8cfc
--- /dev/null
+++ b/src/contrib/openbsd/siphash.c
@@ -0,0 +1,176 @@
+/*	$OpenBSD: siphash.c,v 1.6 2017/04/12 17:41:49 deraadt Exp $ */
+
+/*-
+ * Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+/*
+ * SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d
+ * are the number of compression rounds and the number of finalization rounds.
+ * A compression round is identical to a finalization round and this round
+ * function is called SipRound.  Given a 128-bit key k and a (possibly empty)
+ * byte string m, SipHash-c-d returns a 64-bit value SipHash-c-d(k; m).
+ *
+ * Implemented from the paper "SipHash: a fast short-input PRF", 2012.09.18,
+ * by Jean-Philippe Aumasson and Daniel J. Bernstein,
+ * Permanent Document ID b9a943a805fbfc6fde808af9fc0ecdfa
+ * https://131002.net/siphash/siphash.pdf
+ * https://131002.net/siphash/
+ */
+
+#include <string.h>
+
+#include "libknot/endian.h"
+#include "contrib/string.h"
+#include "contrib/openbsd/siphash.h"
+
+static void	SipHash_CRounds(SIPHASH_CTX *, int);
+static void	SipHash_Rounds(SIPHASH_CTX *, int);
+
+void
+SipHash_Init(SIPHASH_CTX *ctx, const SIPHASH_KEY *key)
+{
+	uint64_t k0, k1;
+
+	k0 = le64toh(key->k0);
+	k1 = le64toh(key->k1);
+
+	ctx->v[0] = 0x736f6d6570736575ULL ^ k0;
+	ctx->v[1] = 0x646f72616e646f6dULL ^ k1;
+	ctx->v[2] = 0x6c7967656e657261ULL ^ k0;
+	ctx->v[3] = 0x7465646279746573ULL ^ k1;
+
+	memset(ctx->buf, 0, sizeof(ctx->buf));
+	ctx->bytes = 0;
+}
+
+void
+SipHash_Update(SIPHASH_CTX *ctx, int rc, int rf, const void *src, size_t len)
+{
+	const uint8_t *ptr = src;
+	size_t left, used;
+
+	if (len == 0)
+		return;
+
+	used = ctx->bytes % sizeof(ctx->buf);
+	ctx->bytes += len;
+
+	if (used > 0) {
+		left = sizeof(ctx->buf) - used;
+
+		if (len >= left) {
+			memcpy(&ctx->buf[used], ptr, left);
+			SipHash_CRounds(ctx, rc);
+			len -= left;
+			ptr += left;
+		} else {
+			memcpy(&ctx->buf[used], ptr, len);
+			return;
+		}
+	}
+
+	while (len >= sizeof(ctx->buf)) {
+		memcpy(ctx->buf, ptr, sizeof(ctx->buf));
+		SipHash_CRounds(ctx, rc);
+		len -= sizeof(ctx->buf);
+		ptr += sizeof(ctx->buf);
+	}
+
+	if (len > 0)
+		memcpy(&ctx->buf, ptr, len);
+}
+
+uint64_t
+SipHash_End(SIPHASH_CTX *ctx, int rc, int rf)
+{
+	uint64_t r;
+	size_t left, used;
+
+	used = ctx->bytes % sizeof(ctx->buf);
+	left = sizeof(ctx->buf) - used;
+	memset(&ctx->buf[used], 0, left - 1);
+	ctx->buf[7] = ctx->bytes;
+
+	SipHash_CRounds(ctx, rc);
+	ctx->v[2] ^= 0xff;
+	SipHash_Rounds(ctx, rf);
+
+	r = (ctx->v[0] ^ ctx->v[1]) ^ (ctx->v[2] ^ ctx->v[3]);
+	memzero(ctx, sizeof(*ctx));
+	return htole64(r);
+}
+
+uint64_t
+SipHash(const SIPHASH_KEY *key, int rc, int rf, const void *src, size_t len)
+{
+	SIPHASH_CTX ctx;
+
+	SipHash_Init(&ctx, key);
+	SipHash_Update(&ctx, rc, rf, src, len);
+	return (SipHash_End(&ctx, rc, rf));
+}
+
+#define SIP_ROTL(x, b) ((x) << (b)) | ( (x) >> (64 - (b)))
+
+static void
+SipHash_Rounds(SIPHASH_CTX *ctx, int rounds)
+{
+	while (rounds--) {
+		ctx->v[0] += ctx->v[1];
+		ctx->v[2] += ctx->v[3];
+		ctx->v[1] = SIP_ROTL(ctx->v[1], 13);
+		ctx->v[3] = SIP_ROTL(ctx->v[3], 16);
+
+		ctx->v[1] ^= ctx->v[0];
+		ctx->v[3] ^= ctx->v[2];
+		ctx->v[0] = SIP_ROTL(ctx->v[0], 32);
+
+		ctx->v[2] += ctx->v[1];
+		ctx->v[0] += ctx->v[3];
+		ctx->v[1] = SIP_ROTL(ctx->v[1], 17);
+		ctx->v[3] = SIP_ROTL(ctx->v[3], 21);
+
+		ctx->v[1] ^= ctx->v[2];
+		ctx->v[3] ^= ctx->v[0];
+		ctx->v[2] = SIP_ROTL(ctx->v[2], 32);
+	}
+}
+
+static void
+SipHash_CRounds(SIPHASH_CTX *ctx, int rounds)
+{
+	uint64_t tmp;
+
+	memcpy(&tmp, ctx->buf, sizeof(tmp));
+	uint64_t m = le64toh(tmp);
+
+	ctx->v[3] ^= m;
+	SipHash_Rounds(ctx, rounds);
+	ctx->v[0] ^= m;
+}
diff --git a/src/contrib/openbsd/siphash.h b/src/contrib/openbsd/siphash.h
new file mode 100644
index 0000000..d551fe8
--- /dev/null
+++ b/src/contrib/openbsd/siphash.h
@@ -0,0 +1,83 @@
+/*-
+ * Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $OpenBSD: siphash.h,v 1.3 2015/02/20 11:51:03 tedu Exp $
+ */
+
+/*
+ * SipHash is a family of pseudorandom functions (a.k.a. keyed hash functions)
+ * optimized for speed on short messages returning a 64bit hash/digest value.
+ *
+ * The number of rounds is defined during the initialization:
+ *  SipHash24_Init() for the fast and resonable strong version
+ *  SipHash48_Init() for the strong version (half as fast)
+ *
+ * struct SIPHASH_CTX ctx;
+ * SipHash24_Init(&ctx);
+ * SipHash_SetKey(&ctx, "16bytes long key");
+ * SipHash_Update(&ctx, pointer_to_string, length_of_string);
+ * SipHash_End(&ctx);
+ */
+
+#ifndef _SIPHASH_H_
+#define _SIPHASH_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define SIPHASH_BLOCK_LENGTH	 8
+#define SIPHASH_KEY_LENGTH	16
+#define SIPHASH_DIGEST_LENGTH	 8
+
+typedef struct _SIPHASH_CTX {
+	uint64_t	v[4];
+	uint8_t		buf[SIPHASH_BLOCK_LENGTH];
+	uint32_t	bytes;
+} SIPHASH_CTX;
+
+typedef struct {
+	uint64_t	k0;
+	uint64_t	k1;
+} SIPHASH_KEY;
+
+void		SipHash_Init(SIPHASH_CTX *, const SIPHASH_KEY *);
+void		SipHash_Update(SIPHASH_CTX *, int, int, const void *, size_t);
+uint64_t	SipHash_End(SIPHASH_CTX *, int, int);
+uint64_t	SipHash(const SIPHASH_KEY *, int, int, const void *, size_t);
+
+#define SipHash24_Init(_c, _k)		SipHash_Init((_c), (_k))
+#define SipHash24_Update(_c, _p, _l)	SipHash_Update((_c), 2, 4, (_p), (_l))
+#define SipHash24_End(_d)		SipHash_End((_d), 2, 4)
+#define SipHash24(_k, _p, _l)		SipHash((_k), 2, 4, (_p), (_l))
+
+#define SipHash48_Init(_c, _k)		SipHash_Init((_c), (_k))
+#define SipHash48_Update(_c, _p, _l)	SipHash_Update((_c), 4, 8, (_p), (_l))
+#define SipHash48_End(_d)		SipHash_End((_d), 4, 8)
+#define SipHash48(_k, _p, _l)		SipHash((_k), 4, 8, (_p), (_l))
+
+#endif /* _SIPHASH_H_ */
diff --git a/src/contrib/openbsd/strlcat.c b/src/contrib/openbsd/strlcat.c
new file mode 100644
index 0000000..1409062
--- /dev/null
+++ b/src/contrib/openbsd/strlcat.c
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <string.h>
+
+#include "contrib/openbsd/strlcat.h"
+
+size_t
+knot_strlcat(char *dst, const char *src, size_t siz)
+{
+	char *d = dst;
+	const char *s = src;
+	size_t n = siz;
+	size_t dlen;
+
+	/* Find the end of dst and adjust bytes left but don't go past end */
+	while (n-- != 0 && *d != '\0')
+		d++;
+	dlen = d - dst;
+	n = siz - dlen;
+
+	if (n == 0)
+		return(dlen + strlen(s));
+	while (*s != '\0') {
+		if (n != 1) {
+			*d++ = *s;
+			n--;
+		}
+		s++;
+	}
+	*d = '\0';
+
+	return(dlen + (s - src));	/* count does not include NUL */
+}
diff --git a/src/contrib/openbsd/strlcat.h b/src/contrib/openbsd/strlcat.h
new file mode 100644
index 0000000..7016069
--- /dev/null
+++ b/src/contrib/openbsd/strlcat.h
@@ -0,0 +1,31 @@
+/*
+ * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#pragma once
+
+#ifndef HAVE_STRLCAT
+#define strlcat(dst, src, size) knot_strlcat(dst, src, size)
+#endif
+
+/*
+ * Appends src to string dst of size siz (unlike strncat, siz is the
+ * full size of dst, not space left).  At most siz-1 characters
+ * will be copied.  Always NUL terminates (unless siz <= strlen(dst)).
+ * Returns strlen(src) + MIN(siz, strlen(initial dst)).
+ * If retval >= siz, truncation occurred.
+ */
+size_t
+knot_strlcat(char *dst, const char *src, size_t siz);
diff --git a/src/contrib/openbsd/strlcpy.c b/src/contrib/openbsd/strlcpy.c
new file mode 100644
index 0000000..eafc0e4
--- /dev/null
+++ b/src/contrib/openbsd/strlcpy.c
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+#include <string.h>
+
+#include "contrib/openbsd/strlcpy.h"
+
+size_t
+knot_strlcpy(char *dst, const char *src, size_t siz)
+{
+	char *d = dst;
+	const char *s = src;
+	size_t n = siz;
+
+	/* Copy as many bytes as will fit */
+	if (n != 0) {
+		while (--n != 0) {
+			if ((*d++ = *s++) == '\0')
+				break;
+		}
+	}
+
+	/* Not enough room in dst, add NUL and traverse rest of src */
+	if (n == 0) {
+		if (siz != 0)
+			*d = '\0';		/* NUL-terminate dst */
+		while (*s++)
+			;
+	}
+
+	return(s - src - 1);	/* count does not include NUL */
+}
diff --git a/src/contrib/openbsd/strlcpy.h b/src/contrib/openbsd/strlcpy.h
new file mode 100644
index 0000000..6421068
--- /dev/null
+++ b/src/contrib/openbsd/strlcpy.h
@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 1998 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#pragma once
+
+#ifndef HAVE_STRLCPY
+#define strlcpy(dst, src, size) knot_strlcpy(dst, src, size)
+#endif
+
+/*
+ * Copy src to string dst of size siz.  At most siz-1 characters
+ * will be copied.  Always NUL terminates (unless siz == 0).
+ * Returns strlen(src); if retval >= siz, truncation occurred.
+ */
+size_t
+knot_strlcpy(char *dst, const char *src, size_t siz);
diff --git a/src/contrib/qp-trie/trie.c b/src/contrib/qp-trie/trie.c
new file mode 100644
index 0000000..c5ee897
--- /dev/null
+++ b/src/contrib/qp-trie/trie.c
@@ -0,0 +1,1451 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+    Copyright (C) 2018 Tony Finch <dot@dotat.at>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+    The code originated from https://github.com/fanf2/qp/blob/master/qp.c
+    at revision 5f6d93753.
+ */
+
+#include <assert.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "contrib/qp-trie/trie.h"
+#include "contrib/macros.h"
+#include "contrib/mempattern.h"
+#include "libknot/errcode.h"
+
+typedef unsigned int uint;
+typedef uint64_t index_t; /*!< nibble index into a key */
+typedef uint64_t word; /*!< A type-punned word */
+typedef uint bitmap_t; /*!< Bit-maps, using the range of 1<<0 to 1<<16 (inclusive). */
+
+typedef char static_assert_pointer_fits_in_word
+	[sizeof(word) >= sizeof(uintptr_t) ? 1 : -1];
+
+#define KEYLENBITS 31
+
+/*! \brief trie keys have lengths
+ *
+ * 32 bits are enough for key lengths; probably even 16 bits would be.
+ * However, a 32 bit length means the alignment will be a multiple of
+ * 4, allowing us to stash the COW and BRANCH flags in the bottom bits
+ * of a pointer to a key.
+ *
+ * We need to steal a couple of bits from the length to keep the COW
+ * state of key allocations.
+ */
+typedef struct {
+	uint32_t cow:1, len:KEYLENBITS;
+	trie_key_t chars[];
+} tkey_t;
+
+/*! \brief A trie node is a pair of words.
+ *
+ * Each word is type-punned, depending on whether this is a branch
+ * node or a leaf node. We'll define some accessor functions to wrap
+ * this up into something reasonably safe.
+ *
+ * We aren't using a union to avoid problems with strict aliasing, and
+ * we aren't using bitfields because we want to control exactly which
+ * bits in the word are used by each field (in particular the flags).
+ *
+ * Branch nodes are never allocated individually: they are always part
+ * of either the root node or the twigs array of their parent branch.
+ *
+ * In a branch:
+ *
+ * `i` contains flags, bitmap, and index, explained in more detail below.
+ *
+ * `p` is a pointer to the "twigs", an array of child nodes.
+ *
+ * In a leaf:
+ *
+ * `i` is cast from a pointer to a tkey_t, with flags in the bottom bits.
+ *
+ * `p` is a trie_val_t.
+ */
+typedef struct node {
+	word i;
+	void *p;
+} node_t;
+
+struct trie {
+	node_t root; // undefined when weight == 0, see empty_root()
+	size_t weight;
+	knot_mm_t mm;
+};
+
+/*! \brief size (in bits) of nibble (half-byte) indexes into keys
+ *
+ * The bottom bit is clear for the upper nibble, and set for the lower
+ * nibble, big-endian style, since the tree has to be in lexicographic
+ * order. The index increases from one branch node to the next as you
+ * go deeper into the trie. All the keys below a branch are identical
+ * up to the nibble identified by the branch.
+ *
+ * (see also tkey_t.len above)
+ */
+#define TWIDTH_INDEX 33
+
+/*! \brief exclusive limit on indexes */
+#define TMAX_INDEX (BIG1 << TWIDTH_INDEX)
+
+/*! \brief size (in bits) of branch bitmap
+ *
+ * The bitmap indicates which subtries are present. The present child
+ * nodes are stored in the twigs array (with no holes between them).
+ *
+ * To simplify storing keys that are prefixes of each other, the
+ * end-of-string position is treated as an extra nibble value, ordered
+ * before all others. So there are 16 possible real nibble values,
+ * plus one value for nibbles past the end of the key.
+ */
+#define TWIDTH_BMP 17
+
+/*
+ * We're constructing the layout of the branch `i` field in a careful
+ * way to avoid mistakes, getting the compiler to calculate values
+ * rather than typing them in by hand.
+ */
+enum {
+	TSHIFT_BRANCH = 0,
+	TSHIFT_COW,
+	TSHIFT_BMP,
+	TOP_BMP = TSHIFT_BMP + TWIDTH_BMP,
+	TSHIFT_INDEX = TOP_BMP,
+	TOP_INDEX = TSHIFT_INDEX + TWIDTH_INDEX,
+};
+
+typedef char static_assert_fields_fit_in_word
+	[TOP_INDEX <= sizeof(word) * CHAR_BIT ? 1 : -1];
+
+typedef char static_assert_bmp_fits
+	[TOP_BMP <= sizeof(bitmap_t) * CHAR_BIT ? 1 : -1];
+
+#define BIG1 ((word)1)
+#define TMASK(width, shift) (((BIG1 << (width)) - BIG1) << (shift))
+
+/*! \brief is this node a branch or a leaf? */
+#define TFLAG_BRANCH (BIG1 << TSHIFT_BRANCH)
+
+/*! \brief copy-on-write flag, used in both leaves and branches */
+#define TFLAG_COW (BIG1 << TSHIFT_COW)
+
+/*! \brief for extracting pointer to key */
+#define TMASK_LEAF (~(word)(TFLAG_BRANCH | TFLAG_COW))
+
+/*! \brief mask for extracting nibble index */
+#define TMASK_INDEX TMASK(TWIDTH_INDEX,  TSHIFT_INDEX)
+
+/*! \brief mask for extracting bitmap */
+#define TMASK_BMP TMASK(TWIDTH_BMP,  TSHIFT_BMP)
+
+/*! \brief bitmap entry for NOBYTE */
+#define BMP_NOBYTE (BIG1 << TSHIFT_BMP)
+
+/*! \brief Initialize a new leaf, copying the key, and returning failure code. */
+static int mkleaf(node_t *leaf, const trie_key_t *key, uint32_t len, knot_mm_t *mm)
+{
+	if (unlikely((word)len > (BIG1 << KEYLENBITS)))
+		return KNOT_ENOMEM;
+	tkey_t *lkey = mm_alloc(mm, sizeof(tkey_t) + len);
+	if (unlikely(!lkey))
+		return KNOT_ENOMEM;
+	lkey->cow = 0;
+	lkey->len = len;
+	memcpy(lkey->chars, key, len);
+	word i = (uintptr_t)lkey;
+	assert((i & TFLAG_BRANCH) == 0);
+	*leaf = (node_t){ .i = i, .p = NULL };
+	return KNOT_EOK;
+}
+
+/*! \brief construct a branch node */
+static node_t mkbranch(index_t index, bitmap_t bmp, node_t *twigs)
+{
+	word i = TFLAG_BRANCH | bmp
+		| (index << TSHIFT_INDEX);
+	assert(index < TMAX_INDEX);
+	assert((bmp & ~TMASK_BMP) == 0);
+	return (node_t){ .i = i, .p = twigs };
+}
+
+/*! \brief Make an empty root node. */
+static node_t empty_root(void)
+{
+	return mkbranch(TMAX_INDEX-1, 0, NULL);
+}
+
+/*! \brief Propagate error codes. */
+#define ERR_RETURN(x) \
+	do { \
+		int err_code_ = x; \
+		if (unlikely(err_code_ != KNOT_EOK)) \
+			return err_code_; \
+	} while (false)
+
+
+/*! \brief Test flags to determine type of this node. */
+static bool isbranch(const node_t *t)
+{
+	return t->i & TFLAG_BRANCH;
+}
+
+static tkey_t *tkey(const node_t *t)
+{
+	assert(!isbranch(t));
+	return (tkey_t *)(uintptr_t)(t->i & TMASK_LEAF);
+}
+
+static trie_val_t *tvalp(node_t *t)
+{
+	assert(!isbranch(t));
+	return &t->p;
+}
+
+/*! \brief Given a branch node, return the index of the corresponding nibble in the key. */
+static index_t branch_index(const node_t *t)
+{
+	assert(isbranch(t));
+	return (t->i & TMASK_INDEX) >> TSHIFT_INDEX;
+}
+
+static bitmap_t branch_bmp(const node_t *t)
+{
+	assert(isbranch(t));
+	return (t->i & TMASK_BMP);
+}
+
+/*!
+ * \brief Count the number of set bits.
+ *
+ * \TODO This implementation may be relatively slow on some HW.
+ */
+static uint branch_weight(const node_t *t)
+{
+	assert(isbranch(t));
+	uint n = __builtin_popcount(t->i & TMASK_BMP);
+	assert(n > 1 && n <= TWIDTH_BMP);
+	return n;
+}
+
+/*! \brief Compute offset of an existing child in a branch node. */
+static uint twigoff(const node_t *t, bitmap_t bit)
+{
+	assert(isbranch(t));
+	assert(__builtin_popcount(bit) == 1);
+	return __builtin_popcount(t->i & TMASK_BMP & (bit - 1));
+}
+
+/*! \brief Extract a nibble from a key and turn it into a bitmask. */
+static bitmap_t keybit(index_t ni, const trie_key_t *key, uint32_t len)
+{
+	index_t bytei = ni >> 1;
+
+	if (bytei >= len)
+		return BMP_NOBYTE;
+
+	uint8_t ki = (uint8_t)key[bytei];
+	uint nibble = (ni & 1) ? (ki & 0xf) : (ki >> 4);
+
+	// skip one for NOBYTE nibbles after the end of the key
+	return BIG1 << (nibble + 1 + TSHIFT_BMP);
+}
+
+/*! \brief Extract a nibble from a key and turn it into a bitmask. */
+static bitmap_t twigbit(const node_t *t, const trie_key_t *key, uint32_t len)
+{
+	assert(isbranch(t));
+	return keybit(branch_index(t), key, len);
+}
+
+/*! \brief Test if a branch node has a child indicated by a bitmask. */
+static bool hastwig(const node_t *t, bitmap_t bit)
+{
+	assert(isbranch(t));
+	assert((bit & ~TMASK_BMP) == 0);
+	assert(__builtin_popcount(bit) == 1);
+	return t->i & bit;
+}
+
+/*! \brief Get pointer to packed array of child nodes. */
+static node_t* twigs(node_t *t)
+{
+	assert(isbranch(t));
+	return t->p;
+}
+
+/*! \brief Get pointer to a particular child of a branch node. */
+static node_t* twig(node_t *t, uint i)
+{
+	assert(i < branch_weight(t));
+	return twigs(t) + i;
+}
+
+/*! \brief Get twig number of a child node TODO: better description. */
+static uint twig_number(node_t *child, node_t *parent)
+{
+	// twig array index using pointer arithmetic
+	ptrdiff_t num = child - twigs(parent);
+	assert(num >= 0 && num < branch_weight(parent));
+	return (uint)num;
+}
+
+/*! \brief Simple string comparator. */
+static int key_cmp(const trie_key_t *k1, uint32_t k1_len,
+		   const trie_key_t *k2, uint32_t k2_len)
+{
+	int ret = memcmp(k1, k2, MIN(k1_len, k2_len));
+	if (ret != 0) {
+		return ret;
+	}
+
+	/* Key string is equal, compare lengths. */
+	if (k1_len == k2_len) {
+		return 0;
+	} else if (k1_len < k2_len) {
+		return -1;
+	} else {
+		return 1;
+	}
+}
+
+trie_t* trie_create(knot_mm_t *mm)
+{
+	trie_t *trie = mm_alloc(mm, sizeof(trie_t));
+	if (trie != NULL) {
+		trie->root = empty_root();
+		trie->weight = 0;
+		if (mm != NULL)
+			trie->mm = *mm;
+		else
+			mm_ctx_init(&trie->mm);
+	}
+	return trie;
+}
+
+/*! \brief Free anything under the trie node, except for the passed pointer itself. */
+static void clear_trie(node_t *trie, knot_mm_t *mm)
+{
+	if (!isbranch(trie)) {
+		mm_free(mm, tkey(trie));
+	} else {
+		uint n = branch_weight(trie);
+		for (uint i = 0; i < n; ++i)
+			clear_trie(twig(trie, i), mm);
+		mm_free(mm, twigs(trie));
+	}
+}
+
+void trie_free(trie_t *tbl)
+{
+	if (tbl == NULL)
+		return;
+	if (tbl->weight)
+		clear_trie(&tbl->root, &tbl->mm);
+	mm_free(&tbl->mm, tbl);
+}
+
+void trie_clear(trie_t *tbl)
+{
+	assert(tbl);
+	if (!tbl->weight)
+		return;
+	clear_trie(&tbl->root, &tbl->mm);
+	tbl->root = empty_root();
+	tbl->weight = 0;
+}
+
+static bool dup_trie(node_t *copy, const node_t *orig, trie_dup_cb dup_cb, knot_mm_t *mm)
+{
+	if (isbranch(orig)) {
+		uint n = branch_weight(orig);
+		node_t *cotw = mm_alloc(mm, n * sizeof(*cotw));
+		if (cotw == NULL) {
+			return NULL;
+		}
+		const node_t *ortw = twigs((node_t *)orig);
+		for (uint i = 0; i < n; ++i) {
+			if (!dup_trie(cotw + i, ortw + i, dup_cb, mm)) {
+				while (i-- > 0) {
+					clear_trie(cotw + i, mm);
+				}
+				mm_free(mm, cotw);
+				return false;
+			}
+		}
+		*copy = mkbranch(branch_index(orig), branch_bmp(orig), cotw);
+	} else {
+		tkey_t *key = tkey(orig);
+		if (mkleaf(copy, key->chars, key->len, mm) != KNOT_EOK) {
+			return false;
+		}
+		if ((copy->p = dup_cb(orig->p, mm)) == NULL) {
+			mm_free(mm, tkey(copy));
+			return false;
+		}
+	}
+	return true;
+}
+
+trie_t* trie_dup(const trie_t *orig, trie_dup_cb dup_cb, knot_mm_t *mm)
+{
+	if (orig == NULL) {
+		return NULL;
+	}
+	trie_t *copy = mm_alloc(mm, sizeof(*copy));
+	if (copy == NULL) {
+		return NULL;
+	}
+	copy->weight = orig->weight;
+	if (mm != NULL) {
+		copy->mm = *mm;
+	} else {
+		mm_ctx_init(&copy->mm);
+	}
+	if (copy->weight) {
+		if (!dup_trie(&copy->root, &orig->root, dup_cb, mm)) {
+			mm_free(mm, copy);
+			return NULL;
+		}
+	}
+	return copy;
+}
+
+size_t trie_weight(const trie_t *tbl)
+{
+	assert(tbl);
+	return tbl->weight;
+}
+
+trie_val_t* trie_get_try(trie_t *tbl, const trie_key_t *key, uint32_t len)
+{
+	assert(tbl);
+	if (!tbl->weight)
+		return NULL;
+	node_t *t = &tbl->root;
+	while (isbranch(t)) {
+		__builtin_prefetch(twigs(t));
+		bitmap_t b = twigbit(t, key, len);
+		if (!hastwig(t, b))
+			return NULL;
+		t = twig(t, twigoff(t, b));
+	}
+	tkey_t *lkey = tkey(t);
+	if (key_cmp(key, len, lkey->chars, lkey->len) != 0)
+		return NULL;
+	return tvalp(t);
+}
+
+/* Optimization: the approach isn't ideal, as e.g. walking through the prefix
+ * is duplicated and we explicitly construct the wildcard key.  Still, it's close
+ * to optimum which would be significantly more complicated and error-prone to write. */
+trie_val_t* trie_get_try_wildcard(trie_t *tbl, const trie_key_t *key, uint32_t len)
+{
+	assert(tbl);
+	if (!tbl->weight)
+		return NULL;
+	// Find leaf sharing the longest common prefix; see ns_find_branch() for explanation.
+	node_t *t = &tbl->root;
+	while (isbranch(t)) {
+		__builtin_prefetch(twigs(t));
+		bitmap_t b = twigbit(t, key, len);
+		uint i = hastwig(t, b) ? twigoff(t, b) : 0;
+		t = twig(t, i);
+	}
+	const tkey_t * const lcp_key = tkey(t);
+
+	// Find the last matching zero byte or -1 (source of synthesis)
+	int i_lmz = -1;
+	for (int i = 0; i < len && i < lcp_key->len && key[i] == lcp_key->chars[i]; ++i) {
+		if (key[i] == '\0' && i < len - 1) // do not count the terminating zero
+			i_lmz = i;
+		// Shortcut: we may have found an exact match.
+		if (i == len - 1 && len == lcp_key->len)
+			return tvalp(t);
+	}
+	if (len == 0) // The empty name needs separate handling.
+		return lcp_key->len == 0 ? tvalp(t) : NULL;
+
+	// Construct the key of the wildcard we need and look it up.
+	const int wild_len = i_lmz + 3;
+	uint8_t wild_key[wild_len];
+	memcpy(wild_key, key, wild_len - 2);
+	wild_key[wild_len - 2] = '*';
+	wild_key[wild_len - 1] = '\0'; // LF is always 0-terminated ATM
+	return trie_get_try(tbl, wild_key, wild_len);
+}
+
+/*! \brief Delete leaf t with parent p; b is the bit for t under p.
+ * Optionally return the deleted value via val.  The function can't fail. */
+static void del_found(trie_t *tbl, node_t *t, node_t *p, bitmap_t b, trie_val_t *val)
+{
+	assert(!tkey(t)->cow);
+	mm_free(&tbl->mm, tkey(t));
+	if (val != NULL)
+		*val = *tvalp(t); // we return trie_val_t directly when deleting
+	--tbl->weight;
+	if (unlikely(!p)) { // whole trie was a single leaf
+		assert(tbl->weight == 0);
+		tbl->root = empty_root();
+		return;
+	}
+	// remove leaf t as child of p
+	node_t *tp = twigs(p);
+	uint ci = twig_number(t, p);
+	uint cc = branch_weight(p); // child count
+
+	if (cc == 2) {
+		// collapse binary node p: move the other child to the parent
+		*p = tp[1 - ci];
+		mm_free(&tbl->mm, tp);
+		return;
+	}
+	memmove(tp + ci, tp + ci + 1, sizeof(node_t) * (cc - ci - 1));
+	p->i &= ~b;
+	node_t *newt = mm_realloc(&tbl->mm, tp, sizeof(node_t) * (cc - 1),
+				  sizeof(node_t) * cc);
+	if (likely(newt != NULL))
+		p->p = newt;
+	// We can ignore mm_realloc failure because an oversized twig
+	// array is OK - only beware that next time the prev_size
+	// passed to mm_realloc will not be correct; TODO?
+}
+
+int trie_del(trie_t *tbl, const trie_key_t *key, uint32_t len, trie_val_t *val)
+{
+	assert(tbl);
+	if (!tbl->weight)
+		return KNOT_ENOENT;
+	node_t *t = &tbl->root; // current and parent node
+	node_t *p = NULL;
+	bitmap_t b = 0;
+	while (isbranch(t)) {
+		__builtin_prefetch(twigs(t));
+		b = twigbit(t, key, len);
+		if (!hastwig(t, b))
+			return KNOT_ENOENT;
+		p = t;
+		t = twig(t, twigoff(t, b));
+	}
+	tkey_t *lkey = tkey(t);
+	if (key_cmp(key, len, lkey->chars, lkey->len) != 0)
+		return KNOT_ENOENT;
+	del_found(tbl, t, p, b, val);
+	return KNOT_EOK;
+}
+
+/*!
+ * \brief Stack of nodes, storing a path down a trie.
+ *
+ * The structure also serves directly as the public trie_it_t type,
+ * in which case it always points to the current leaf, unless we've finished
+ * (i.e. it->len == 0).
+ * stack[0] is always a valid pointer to the root -> ns_gettrie()
+ */
+typedef struct trie_it {
+	node_t* *stack; /*!< The stack; malloc is used directly instead of mm. */
+	uint32_t len;   /*!< Current length of the stack. */
+	uint32_t alen;  /*!< Allocated/available length of the stack. */
+	/*! \brief Initial storage for \a stack; it should fit in most use cases. */
+	node_t* stack_init[250];
+} nstack_t;
+
+/*! \brief Create a node stack containing just the root (or empty). */
+static void ns_init(nstack_t *ns, trie_t *tbl)
+{
+	assert(tbl);
+	ns->stack = ns->stack_init;
+	ns->alen = sizeof(ns->stack_init) / sizeof(ns->stack_init[0]);
+	ns->stack[0] = &tbl->root;
+	ns->len = (tbl->weight > 0);
+}
+
+static inline trie_t * ns_gettrie(nstack_t *ns)
+{
+	assert(ns && ns->stack && ns->stack[0]);
+	return (struct trie *)ns->stack[0];
+}
+
+/*! \brief Free inside of the stack, i.e. not the passed pointer itself. */
+static void ns_cleanup(nstack_t *ns)
+{
+	assert(ns && ns->stack);
+	if (likely(ns->stack == ns->stack_init))
+		return;
+	free(ns->stack);
+	#ifndef NDEBUG
+		ns->stack = NULL;
+		ns->alen = 0;
+	#endif
+}
+
+/*! \brief Allocate more space for the stack. */
+static int ns_longer_alloc(nstack_t *ns)
+{
+	ns->alen *= 2;
+	size_t new_size = ns->alen * sizeof(node_t *);
+	node_t **st;
+	if (ns->stack == ns->stack_init) {
+		st = malloc(new_size);
+		if (st != NULL)
+			memcpy(st, ns->stack, ns->len * sizeof(node_t *));
+	} else {
+		st = realloc(ns->stack, new_size);
+	}
+	if (st == NULL)
+		return KNOT_ENOMEM;
+	ns->stack = st;
+	return KNOT_EOK;
+}
+
+/*! \brief Ensure the node stack can be extended by one. */
+static inline int ns_longer(nstack_t *ns)
+{
+	// get a longer stack if needed
+	if (likely(ns->len < ns->alen))
+		return KNOT_EOK;
+	return ns_longer_alloc(ns); // hand-split the part suitable for inlining
+}
+
+/*!
+ * \brief Find the "branching point" as if searching for a key.
+ *
+ *  The whole path to the point is kept on the passed stack;
+ *  always at least the root will remain on the top of it.
+ *  Beware: the precise semantics of this function is rather tricky.
+ *  The top of the stack will contain: the corresponding leaf if exact
+ *  match is found; or the immediate node below a
+ *  branching-point-on-edge or the branching-point itself.
+ *
+ *  \param idiff  Set the index of first differing nibble, or TMAX_INDEX for an exact match
+ *  \param tbit  Set the bit of the closest leaf's nibble at index idiff
+ *  \param kbit  Set the bit of the key's nibble at index idiff
+ *
+ *  \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_find_branch(nstack_t *ns, const trie_key_t *key, uint32_t len,
+                          index_t *idiff, bitmap_t *tbit, bitmap_t *kbit)
+{
+	assert(ns && ns->len && idiff);
+	// First find some leaf with longest matching prefix.
+	while (isbranch(ns->stack[ns->len - 1])) {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		__builtin_prefetch(twigs(t));
+		bitmap_t b = twigbit(t, key, len);
+		// Even if our key is missing from this branch we need to
+		// keep iterating down to a leaf. It doesn't matter which
+		// twig we choose since the keys are all the same up to this
+		// index. Note that blindly using twigoff(t, b) can cause
+		// an out-of-bounds index if it equals twigmax(t).
+		uint i = hastwig(t, b) ? twigoff(t, b) : 0;
+		ns->stack[ns->len++] = twig(t, i);
+	}
+	tkey_t *lkey = tkey(ns->stack[ns->len-1]);
+	// Find index of the first char that differs.
+	size_t bytei = 0;
+	uint32_t klen = lkey->len;
+	for (bytei = 0; bytei < MIN(len,klen); bytei++) {
+		if (key[bytei] != lkey->chars[bytei])
+			break;
+	}
+	// Find which half-byte has matched.
+	index_t index = bytei << 1;
+	if (bytei == len && len == lkey->len) { // found equivalent key
+		index = TMAX_INDEX;
+		goto success;
+	}
+	if (likely(bytei < MIN(len,klen))) {
+		uint8_t k2 = (uint8_t)lkey->chars[bytei];
+		uint8_t k1 = (uint8_t)key[bytei];
+		if (((k1 ^ k2) & 0xf0) == 0)
+			index += 1;
+	}
+	// now go up the trie from the current leaf
+	node_t *t;
+	do {
+		if (unlikely(ns->len == 1))
+			goto success; // only the root stays on the stack
+		t = ns->stack[ns->len - 2];
+		if (branch_index(t) < index)
+			goto success;
+		--ns->len;
+	} while (true);
+success:
+	#ifndef NDEBUG // invariants on successful return
+		assert(ns->len);
+		if (isbranch(ns->stack[ns->len - 1])) {
+			t = ns->stack[ns->len - 1];
+			assert(branch_index(t) >= index);
+		}
+		if (ns->len > 1) {
+			t = ns->stack[ns->len - 2];
+			assert(branch_index(t) < index || index == TMAX_INDEX);
+		}
+	#endif
+	*idiff = index;
+	*tbit = keybit(index, lkey->chars, lkey->len);
+	*kbit = keybit(index, key, len);
+	return KNOT_EOK;
+}
+
+/*!
+ * \brief Advance the node stack to the last leaf in the subtree.
+ *
+ * \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_last_leaf(nstack_t *ns)
+{
+	assert(ns);
+	do {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		if (!isbranch(t))
+			return KNOT_EOK;
+		uint lasti = branch_weight(t) - 1;
+		ns->stack[ns->len++] = twig(t, lasti);
+	} while (true);
+}
+
+/*!
+ * \brief Advance the node stack to the first leaf in the subtree.
+ *
+ * \return KNOT_EOK or KNOT_ENOMEM.
+ */
+static int ns_first_leaf(nstack_t *ns)
+{
+	assert(ns && ns->len);
+	do {
+		ERR_RETURN(ns_longer(ns));
+		node_t *t = ns->stack[ns->len - 1];
+		if (!isbranch(t))
+			return KNOT_EOK;
+		ns->stack[ns->len++] = twig(t, 0);
+	} while (true);
+}
+
+/*!
+ * \brief Advance the node stack to the leaf that is previous to the current node.
+ *
+ * \note Prefix leaf under the current node DOES count (if present; perhaps questionable).
+ * \return KNOT_EOK on success, KNOT_ENOENT on not-found, or possibly KNOT_ENOMEM.
+ */
+static int ns_prev_leaf(nstack_t *ns)
+{
+	assert(ns && ns->len > 0);
+
+	node_t *t = ns->stack[ns->len - 1];
+	// Beware: BMP_NOBYTE child is ordered *before* its parent.
+	if (isbranch(t) && hastwig(t, BMP_NOBYTE)) {
+		ERR_RETURN(ns_longer(ns));
+		ns->stack[ns->len++] = twig(t, 0);
+		return KNOT_EOK;
+	}
+
+	for (; ns->len >= 2; --ns->len) {
+		t = ns->stack[ns->len - 1];
+		node_t *p = ns->stack[ns->len - 2];
+		uint ci = twig_number(t, p);
+		if (ci == 0) // we've got to go up again
+			continue;
+		// t isn't the first child -> go down the previous one
+		ns->stack[ns->len - 1] = twig(p, ci - 1);
+		return ns_last_leaf(ns);
+	}
+	return KNOT_ENOENT; // root without empty key has no previous leaf
+}
+
+/*!
+ * \brief Advance the node stack to the leaf that is successor to the current node.
+ *
+ * \param skip_prefixed skip any nodes whose key is a prefix of the current one.
+ *     If false, prefix leaf or anything else under the current node DOES count.
+ * \return KNOT_EOK on success, KNOT_ENOENT on not-found, or possibly KNOT_ENOMEM.
+ */
+static int ns_next_leaf(nstack_t *ns, const bool skip_pefixed)
+{
+	assert(ns && ns->len > 0);
+
+	node_t *t = ns->stack[ns->len - 1];
+	if (!skip_pefixed && isbranch(t))
+		return ns_first_leaf(ns);
+	for (; ns->len >= 2; --ns->len) {
+		t = ns->stack[ns->len - 1];
+		node_t *p = ns->stack[ns->len - 2];
+		uint ci = twig_number(t, p);
+		if (skip_pefixed && ci == 0 && hastwig(t, BMP_NOBYTE)) {
+			// Keys in the subtree of p are suffixes of the key of t,
+			// so we've got to go one level higher
+			// (this can't happen more than once)
+			continue;
+		}
+		uint cc = branch_weight(p);
+		assert(ci + 1 <= cc);
+		if (ci + 1 == cc) {
+			// t is the last child of p, so we need to keep climbing
+			continue;
+		}
+		// go down the next child of p
+		ns->stack[ns->len - 1] = twig(p, ci + 1);
+		return ns_first_leaf(ns);
+	}
+	return KNOT_ENOENT; // not found, as no more parent is available
+}
+
+/*! \brief Advance the node stack to leaf with longest prefix of the current key. */
+static int ns_prefix(nstack_t *ns)
+{
+	assert(ns && ns->len > 0);
+	const node_t *start = ns->stack[ns->len - 1];
+	// Walk up the trie until we find a BMP_NOBYTE child.
+	while (--ns->len > 0) {
+		node_t *p = ns->stack[ns->len - 1];
+		if (!hastwig(p, BMP_NOBYTE))
+			continue;
+		node_t *end = twig(p, 0);
+		// In case we started in a BMP_NOBYTE leaf, the first step up
+		// did NOT shorten the key and we would get back into the same
+		// node again.
+		if (end == start)
+			continue;
+		ns->stack[ns->len++] = end;
+		return KNOT_EOK;
+	}
+	return KNOT_ENOENT; // not found, as no more parent is available
+}
+
+/*! \brief less-or-equal search.
+ *
+ * \return KNOT_EOK for exact match, 1 for previous, KNOT_ENOENT for not-found,
+ *         or KNOT_E*.
+ */
+static int ns_get_leq(nstack_t *ns, const trie_key_t *key, uint32_t len)
+{
+	// First find the key with longest-matching prefix
+	index_t idiff;
+	bitmap_t tbit, kbit;
+	ERR_RETURN(ns_find_branch(ns, key, len, &idiff, &tbit, &kbit));
+	node_t *t = ns->stack[ns->len - 1];
+	if (idiff == TMAX_INDEX) // found exact match
+		return KNOT_EOK;
+	// Get t: the last node on matching path
+	bitmap_t b;
+	if (isbranch(t) && branch_index(t) == idiff) {
+		// t is OK
+		b = kbit;
+	} else {
+		// the top of the stack was the first unmatched node -> step up
+		if (ns->len == 1) {
+			// root was unmatched already
+			if (kbit < tbit)
+				return KNOT_ENOENT;
+			ERR_RETURN(ns_last_leaf(ns));
+			return 1;
+		}
+		--ns->len;
+		t = ns->stack[ns->len - 1];
+		b = twigbit(t, key, len);
+	}
+	// Now we re-do the first "non-matching" step in the trie
+	// but try the previous child if key was less (it may not exist)
+	int i = hastwig(t, b)
+		? (int)twigoff(t, b) - (kbit < tbit)
+		: (int)twigoff(t, b) - 1 /* twigoff returns successor when !hastwig */;
+	if (i >= 0) {
+		ERR_RETURN(ns_longer(ns));
+		ns->stack[ns->len++] = twig(t, i);
+		ERR_RETURN(ns_last_leaf(ns));
+	} else {
+		ERR_RETURN(ns_prev_leaf(ns));
+	}
+	return 1;
+}
+
+int trie_get_leq(trie_t *tbl, const trie_key_t *key, uint32_t len, trie_val_t **val)
+{
+	assert(tbl && val);
+	if (tbl->weight == 0) {
+		if (val) *val = NULL;
+		return KNOT_ENOENT;
+	}
+	// We try to do without malloc.
+	nstack_t ns_local;
+	ns_init(&ns_local, tbl);
+	nstack_t *ns = &ns_local;
+
+	int ret = ns_get_leq(ns, key, len);
+	if (ret == KNOT_EOK || ret == 1) {
+		assert(!isbranch(ns->stack[ns->len - 1]));
+		if (val) *val = tvalp(ns->stack[ns->len - 1]);
+	} else {
+		if (val) *val = NULL;
+	}
+	ns_cleanup(ns);
+	return ret;
+}
+
+int trie_it_get_leq(trie_it_t *it, const trie_key_t *key, uint32_t len)
+{
+	assert(it && it->stack[0] && it->alen);
+	const trie_t *tbl = ns_gettrie(it);
+	if (tbl->weight == 0) {
+		it->len = 0;
+		return KNOT_ENOENT;
+	}
+	it->len = 1;
+	int ret = ns_get_leq(it, key, len);
+	if (ret == KNOT_EOK || ret == 1) {
+		assert(trie_it_key(it, NULL));
+	} else {
+		it->len = 0;
+	}
+	return ret;
+}
+
+/* see below */
+static int cow_pushdown(trie_cow_t *cow, nstack_t *ns);
+
+/*! \brief implementation of trie_get_ins() and trie_get_cow() */
+static trie_val_t* cow_get_ins(trie_cow_t *cow, trie_t *tbl,
+			       const trie_key_t *key, uint32_t len)
+{
+	assert(tbl);
+	// First leaf in an empty tbl?
+	if (unlikely(!tbl->weight)) {
+		if (unlikely(mkleaf(&tbl->root, key, len, &tbl->mm)))
+			return NULL;
+		++tbl->weight;
+		return tvalp(&tbl->root);
+	}
+	{ // Intentionally un-indented; until end of function, to bound cleanup attr.
+	// Find the branching-point
+	__attribute__((cleanup(ns_cleanup)))
+		nstack_t ns_local;
+	ns_init(&ns_local, tbl);
+	nstack_t *ns = &ns_local;
+	index_t idiff;
+	bitmap_t tbit, kbit;
+	if (unlikely(ns_find_branch(ns, key, len, &idiff, &tbit, &kbit)))
+		return NULL;
+	if (unlikely(cow && cow_pushdown(cow, ns) != KNOT_EOK))
+		return NULL;
+	node_t *t = ns->stack[ns->len - 1];
+	if (idiff == TMAX_INDEX) // the same key was already present
+		return tvalp(t);
+	node_t leaf, *leafp;
+	if (unlikely(mkleaf(&leaf, key, len, &tbl->mm)))
+		return NULL;
+
+	if (isbranch(t) && branch_index(t) == idiff) {
+		// The node t needs a new leaf child.
+		assert(!hastwig(t, kbit));
+		// new child position and original child count
+		uint s = twigoff(t, kbit);
+		uint m = branch_weight(t);
+		node_t *nt = mm_realloc(&tbl->mm, twigs(t),
+				sizeof(node_t) * (m + 1), sizeof(node_t) * m);
+		if (unlikely(!nt))
+			goto err_leaf;
+		memmove(nt + s + 1, nt + s, sizeof(node_t) * (m - s));
+		leafp = nt + s;
+		*t = mkbranch(idiff, branch_bmp(t) | kbit, nt);
+	} else {
+		// We need to insert a new binary branch with leaf at *t.
+		// Note: it works the same for the case where we insert above root t.
+		#ifndef NDEBUG
+			if (ns->len > 1) {
+				node_t *pt = ns->stack[ns->len - 2];
+				assert(hastwig(pt, twigbit(pt, key, len)));
+			}
+		#endif
+		node_t *nt = mm_alloc(&tbl->mm, sizeof(node_t) * 2);
+		if (unlikely(!nt))
+			goto err_leaf;
+		node_t t2 = *t; // Save before overwriting t.
+		*t = mkbranch(idiff, tbit | kbit, nt);
+		*twig(t, twigoff(t, tbit)) = t2;
+		leafp = twig(t, twigoff(t, kbit));
+	};
+	*leafp = leaf;
+	++tbl->weight;
+	return tvalp(leafp);
+err_leaf:
+	mm_free(&tbl->mm, tkey(&leaf));
+	return NULL;
+	}
+}
+
+trie_val_t* trie_get_ins(trie_t *tbl, const trie_key_t *key, uint32_t len)
+{
+	return cow_get_ins(NULL, tbl, key, len);
+}
+
+/*! \brief Apply a function to every trie_val_t*, in order; a recursive solution. */
+static int apply_nodes(node_t *t, int (*f)(trie_val_t *, void *), void *d)
+{
+	assert(t);
+	if (!isbranch(t))
+		return f(tvalp(t), d);
+	uint n = branch_weight(t);
+	for (uint i = 0; i < n; ++i)
+		ERR_RETURN(apply_nodes(twig(t, i), f, d));
+	return KNOT_EOK;
+}
+
+int trie_apply(trie_t *tbl, int (*f)(trie_val_t *, void *), void *d)
+{
+	assert(tbl && f);
+	if (!tbl->weight)
+		return KNOT_EOK;
+	return apply_nodes(&tbl->root, f, d);
+}
+
+/* These are all thin wrappers around static Tns* functions. */
+trie_it_t* trie_it_begin(trie_t *tbl)
+{
+	assert(tbl);
+	trie_it_t *it = malloc(sizeof(nstack_t));
+	if (!it)
+		return NULL;
+	ns_init(it, tbl);
+	if (it->len == 0) // empty tbl
+		return it;
+	if (ns_first_leaf(it)) {
+		ns_cleanup(it);
+		free(it);
+		return NULL;
+	}
+	return it;
+}
+
+bool trie_it_finished(trie_it_t *it)
+{
+	assert(it);
+	return it->len == 0;
+}
+
+void trie_it_free(trie_it_t *it)
+{
+	if (!it)
+		return;
+	ns_cleanup(it);
+	free(it);
+}
+
+trie_it_t *trie_it_clone(const trie_it_t *it)
+{
+	if (!it) // TODO: or should that be an assertion?
+		return NULL;
+	trie_it_t *it2 = malloc(sizeof(nstack_t));
+	if (!it2)
+		return NULL;
+	it2->len = it->len;
+	it2->alen = it->alen; // we _might_ change it in the rare malloc case, but...
+	if (likely(it->stack == it->stack_init)) {
+		it2->stack = it2->stack_init;
+		assert(it->alen == sizeof(it->stack_init) / sizeof(it->stack_init[0]));
+	} else {
+		it2->stack = malloc(it2->alen * sizeof(it2->stack[0]));
+		if (!it2->stack) {
+			free(it2);
+			return NULL;
+		}
+	}
+	memcpy(it2->stack, it->stack, it->len * sizeof(it->stack[0]));
+	return it2;
+}
+
+const trie_key_t* trie_it_key(trie_it_t *it, size_t *len)
+{
+	assert(it && it->len);
+	node_t *t = it->stack[it->len - 1];
+	assert(!isbranch(t));
+	tkey_t *key = tkey(t);
+	if (len)
+		*len = key->len;
+	return key->chars;
+}
+
+trie_val_t* trie_it_val(trie_it_t *it)
+{
+	assert(it && it->len);
+	node_t *t = it->stack[it->len - 1];
+	assert(!isbranch(t));
+	return tvalp(t);
+}
+
+void trie_it_next(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (ns_next_leaf(it, false) != KNOT_EOK)
+		it->len = 0;
+}
+
+void trie_it_next_loop(trie_it_t *it)
+{
+	assert(it && it->len);
+	int ret = ns_next_leaf(it, false);
+	if (ret == KNOT_ENOENT) {
+		it->len = 1;
+		ret = ns_first_leaf(it);
+	}
+	if (ret)
+		it->len = 0;
+}
+
+void trie_it_next_nosuffix(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (ns_next_leaf(it, true) != KNOT_EOK)
+		it->len = 0;
+}
+
+void trie_it_prev(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (ns_prev_leaf(it) != KNOT_EOK)
+		it->len = 0;
+}
+
+void trie_it_prev_loop(trie_it_t *it)
+{
+	assert(it && it->len);
+	int ret = ns_prev_leaf(it);
+	if (ret == KNOT_ENOENT) {
+		it->len = 1;
+		ret = ns_last_leaf(it);
+	}
+	if (ret)
+		it->len = 0;
+}
+
+void trie_it_parent(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (ns_prefix(it))
+		it->len = 0;
+}
+
+void trie_it_del(trie_it_t *it)
+{
+	assert(it && it->len);
+	if (it->len == 0)
+		return;
+	node_t *t = it->stack[it->len - 1];
+	assert(!isbranch(t));
+	bitmap_t b; // del_found() needs to know which bit to zero in the bitmap
+	node_t *p;
+	if (it->len == 1) { // deleting the root
+		p = NULL;
+		b = 0; // unused
+	} else {
+		p = it->stack[it->len - 2];
+		assert(isbranch(p));
+		size_t len;
+		const trie_key_t *key = trie_it_key(it, &len);
+		b = twigbit(p, key, len);
+	}
+	// We could trie_it_{next,prev,...}(it) now, in case we wanted that semantics.
+	it->len = 0;
+	del_found(ns_gettrie(it), t, p, b, NULL);
+}
+
+
+/*!\file
+ *
+ * \section About copy-on-write
+ *
+ * In these notes I'll use the term "object" to refer to either the
+ * twig array of a branch, or the application's data that is referred
+ * to by a leaf's trie_val_t pointer. Note that for COW we don't care
+ * about trie node_t structs themselves, but the objects that they
+ * point to.
+ *
+ * \subsection COW states
+ *
+ * During a COW transaction an object can be in one of three states:
+ * shared, only in the old trie, or only in the new trie. When a
+ * transaction is rolled back, the only-new objects are freed; when a
+ * transaction is committed the new trie takes the place of the old
+ * one and only-old objects are freed.
+ *
+ * \subsection branch marks and regions
+ *
+ * A branch object can be marked by setting the COW flag in the first
+ * element of its twig array. Marked branches partition the trie into
+ * regions; an object's state depends on its region.
+ *
+ * The unmarked branch objects between a trie's root and the marked
+ * branches (excluding the marked branches themselves) is exclusively
+ * owned: either old-only (if you started from the old root) or
+ * new-only (if you started from the new root).
+ *
+ * Marked branch objects, and all objects reachable from marked branch
+ * objects, are in the shared region accessible from both old and new
+ * roots. All branch objects below a marked branch must be unmarked.
+ * (That is, there is at most one marked branch object on any path
+ * from the root of a trie.)
+ *
+ * Branch nodes in the new-only region can be modified in place, in
+ * the same way as an original qp trie. Branch nodes in the old-only
+ * or shared regions must not be modified.
+ *
+ * \subsection app object states
+ *
+ * The app objects reachable from the new-only and old-only regions
+ * explicitly record their state in a way determined by the
+ * application. (These app objects are reachable from the old and new
+ * roots by traversing only unmarked branch objects.)
+ *
+ * The app objects reachable from marked branch objects are implicitly
+ * shared, but their state field has an indeterminate value. If an app
+ * object was previously touched by a rolled-back transaction it may
+ * be marked shared or old-only; if it was previously touched by a
+ * committed transaction it may be marked shared or new-only.
+ *
+ * \subsection key states
+ *
+ * The memory allocated for tkey_t objects also needs to track its
+ * sharing state. They have a "cow" flag to mark when they are shared.
+ * Keys are relatively lazily copied (to make them exclusive) when
+ * their leaf node is touched by a COW mutation.
+ *
+ * [An alternative technique might be to copy them more eagerly, in
+ * cow_pushdown(), which would avoid the need for a flag bit at the
+ * cost of more allocator churn in a transaction.]
+ *
+ * \subsection outside COW
+ *
+ * When a COW transaction is not in progress, there are no marked
+ * branch objects, so everything is exclusively owned. When a COW
+ * transaction is finished (committed or rolled back), the branch
+ * marks are removed. Since they are in the shared region, this branch
+ * cleanup is visible to both old and new tries.
+ *
+ * However the state of app objects is not clean between COW
+ * transactions. When a COW transaction is committed, we traverse the
+ * old-only region to find old-only app objects that should be freed
+ * (and vice versa for rollback). In general, there will be app
+ * objects that are only reachable from the new-only region, and that
+ * have a mixture of shared and new states.
+ */
+
+/*! \brief Trie copy-on-write state */
+struct trie_cow {
+	trie_t *old;
+	trie_t *new;
+	trie_cb *mark_shared;
+	void *d;
+};
+
+/*! \brief is this a marked branch object */
+static bool cow_marked(node_t *t)
+{
+	return isbranch(t) && (twigs(t)->i & TFLAG_COW);
+}
+
+/*! \brief is this a leaf with a marked key */
+static bool cow_key(node_t *t)
+{
+	return !isbranch(t) && tkey(t)->cow;
+}
+
+/*! \brief remove mark from a branch object */
+static void clear_cow(node_t *t)
+{
+	assert(isbranch(t));
+	twigs(t)->i &= ~TFLAG_COW;
+}
+
+/*! \brief mark a node as shared
+ *
+ * For branches this marks the twig array (in COW terminology, the
+ * branch object); for leaves it uses the callback to mark the app
+ * object.
+ */
+static void mark_cow(trie_cow_t *cow, node_t *t)
+{
+	if (isbranch(t)) {
+		node_t *object = twigs(t);
+		object->i |= TFLAG_COW;
+	} else {
+		tkey_t *lkey = tkey(t);
+		lkey->cow = 1;
+		if (cow->mark_shared != NULL) {
+			trie_val_t *valp = tvalp(t);
+			cow->mark_shared(*valp, lkey->chars, lkey->len, cow->d);
+		}
+	}
+}
+
+/*! \brief push exclusive COW region down one node */
+static int cow_pushdown_one(trie_cow_t *cow, node_t *t)
+{
+	uint cc = branch_weight(t);
+	node_t *nt = mm_alloc(&cow->new->mm, sizeof(node_t) * cc);
+	if (nt == NULL)
+		return KNOT_ENOMEM;
+	/* mark all the children */
+	for (uint ci = 0; ci < cc; ++ci)
+		mark_cow(cow, twig(t, ci));
+	/* this node must be unmarked in both old and new versions */
+	clear_cow(t);
+	t->p = memcpy(nt, twigs(t), sizeof(node_t) * cc);
+	return KNOT_EOK;
+}
+
+/*! \brief push exclusive COW region to cover a whole node stack */
+static int cow_pushdown(trie_cow_t *cow, nstack_t *ns)
+{
+	node_t *new_twigs = NULL;
+	node_t *old_twigs = NULL;
+	for (uint i = 0; i < ns->len; i++) {
+		/* if we did a pushdown on the previous iteration, we
+		   need to update this stack entry so it points into
+		   the parent's new twigs instead of the old ones */
+		if (new_twigs != old_twigs)
+			ns->stack[i] = new_twigs + (ns->stack[i] - old_twigs);
+		if (cow_marked(ns->stack[i])) {
+			old_twigs = twigs(ns->stack[i]);
+			if (cow_pushdown_one(cow, ns->stack[i]))
+				return KNOT_ENOMEM;
+			new_twigs = twigs(ns->stack[i]);
+		} else {
+			new_twigs = NULL;
+			old_twigs = NULL;
+			/* ensure key is exclusively owned */
+			if (cow_key(ns->stack[i])) {
+				node_t oleaf = *ns->stack[i];
+				tkey_t *okey = tkey(&oleaf);
+				if(mkleaf(ns->stack[i], okey->chars, okey->len,
+					  &cow->new->mm))
+					return KNOT_ENOMEM;
+				ns->stack[i]->p = oleaf.p;
+				okey->cow = 0;
+			}
+		}
+	}
+	return KNOT_EOK;
+}
+
+trie_cow_t* trie_cow(trie_t *old, trie_cb *mark_shared, void *d)
+{
+	knot_mm_t *mm = &old->mm;
+	trie_t *new = mm_alloc(mm, sizeof(trie_t));
+	trie_cow_t *cow = mm_alloc(mm, sizeof(trie_cow_t));
+	if (new == NULL || cow == NULL) {
+		mm_free(mm, new);
+		mm_free(mm, cow);
+		return NULL;
+	}
+	new->mm = old->mm;
+	new->root = old->root;
+	new->weight = old->weight;
+	cow->old = old;
+	cow->new = new;
+	cow->mark_shared = mark_shared;
+	cow->d = d;
+	if (old->weight)
+		mark_cow(cow, &old->root);
+	return cow;
+}
+
+trie_t* trie_cow_new(trie_cow_t *cow)
+{
+	assert(cow != NULL);
+	return cow->new;
+}
+
+trie_val_t* trie_get_cow(trie_cow_t *cow, const trie_key_t *key, uint32_t len)
+{
+	return cow_get_ins(cow, cow->new, key, len);
+}
+
+int trie_del_cow(trie_cow_t *cow, const trie_key_t *key, uint32_t len, trie_val_t *val)
+{
+	trie_t *tbl = cow->new;
+	if (unlikely(!tbl->weight))
+		return KNOT_ENOENT;
+	{ // Intentionally un-indented; until end of function, to bound cleanup attr.
+	// Find the branching-point
+	__attribute__((cleanup(ns_cleanup)))
+		nstack_t ns_local;
+	ns_init(&ns_local, tbl);
+	nstack_t *ns = &ns_local;
+	index_t idiff;
+	bitmap_t tbit, kbit;
+	ERR_RETURN(ns_find_branch(ns, key, len, &idiff, &tbit, &kbit));
+	if (idiff != TMAX_INDEX)
+		return KNOT_ENOENT;
+	ERR_RETURN(cow_pushdown(cow, ns));
+	node_t *t = ns->stack[ns->len - 1];
+	node_t *p = ns->len >= 2 ? ns->stack[ns->len - 2] : NULL;
+	del_found(tbl, t, p, p ? twigbit(p, key, len) : 0, val);
+	}
+	return KNOT_EOK;
+}
+
+/*! \brief clean up after a COW transaction, recursively */
+static void cow_cleanup(trie_cow_t *cow, node_t *t, trie_cb *cb, void *d)
+{
+	if (cow_marked(t)) {
+		// we have hit the shared region, so just reset the mark
+		clear_cow(t);
+		return;
+	} else if (isbranch(t)) {
+		// traverse and free the exclusive region
+		uint cc = branch_weight(t);
+		for (uint ci = 0; ci < cc; ++ci)
+			cow_cleanup(cow, twig(t, ci), cb, d);
+		mm_free(&cow->new->mm, twigs(t));
+		return;
+	} else {
+		// application must decide how to clean up its values
+		tkey_t *lkey = tkey(t);
+		if (cb != NULL) {
+			trie_val_t *valp = tvalp(t);
+			cb(*valp, lkey->chars, lkey->len, d);
+		}
+		// clean up exclusively-owned keys
+		if (lkey->cow)
+			lkey->cow = 0;
+		else
+			mm_free(&cow->new->mm, lkey);
+		return;
+	}
+}
+
+trie_t* trie_cow_commit(trie_cow_t *cow, trie_cb *cb, void *d)
+{
+	trie_t *ret = cow->new;
+	if (cow->old->weight)
+		cow_cleanup(cow, &cow->old->root, cb, d);
+	mm_free(&ret->mm, cow->old);
+	mm_free(&ret->mm, cow);
+	return ret;
+}
+
+trie_t* trie_cow_rollback(trie_cow_t *cow, trie_cb *cb, void *d)
+{
+	trie_t *ret = cow->old;
+	if (cow->new->weight)
+		cow_cleanup(cow, &cow->new->root, cb, d);
+	mm_free(&ret->mm, cow->new);
+	mm_free(&ret->mm, cow);
+	return ret;
+}
diff --git a/src/contrib/qp-trie/trie.h b/src/contrib/qp-trie/trie.h
new file mode 100644
index 0000000..14fb1a2
--- /dev/null
+++ b/src/contrib/qp-trie/trie.h
@@ -0,0 +1,280 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+    Copyright (C) 2018 Tony Finch <dot@dotat.at>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "libknot/mm_ctx.h"
+
+/*!
+ * \brief Native API of QP-tries:
+ *
+ * - keys are uint8_t strings, not necessarily zero-terminated,
+ *   the structure copies the contents of the passed keys
+ * - values are void* pointers, typically you get an ephemeral pointer to it
+ * - key lengths are limited by 2^32-1 ATM
+ */
+
+/*! \brief Element value. */
+typedef void* trie_val_t;
+/*! \brief Key for indexing tries.  Sign could be flipped easily. */
+typedef uint8_t trie_key_t;
+
+/*! \brief Opaque structure holding a QP-trie. */
+typedef struct trie trie_t;
+
+/*! \brief Opaque type for holding a QP-trie iterator. */
+typedef struct trie_it trie_it_t;
+
+/*! \brief Callback for cloning trie values. */
+typedef trie_val_t (*trie_dup_cb)(const trie_val_t val, knot_mm_t *mm);
+
+/*! \brief Callback for performing actions on a trie leaf
+ *
+ * Used during copy-on-write transactions
+ *
+ * \param val	The value of the element to be altered
+ * \param key	The key of the element to be altered
+ * \param len	The length of key
+ * \param d	Additional user data
+ */
+typedef void trie_cb(trie_val_t val, const trie_key_t *key, size_t len, void *d);
+
+/*! \brief Opaque type for holding the copy-on-write state for a QP-trie. */
+typedef struct trie_cow trie_cow_t;
+
+/*! \brief Create a trie instance. */
+trie_t* trie_create(knot_mm_t *mm);
+
+/*! \brief Free a trie instance. */
+void trie_free(trie_t *tbl);
+
+/*! \brief Clear a trie instance (make it empty). */
+void trie_clear(trie_t *tbl);
+
+/*! \brief Create a clone of existing trie. */
+trie_t* trie_dup(const trie_t *orig, trie_dup_cb dup_cb, knot_mm_t *mm);
+
+/*! \brief Return the number of keys in the trie. */
+size_t trie_weight(const trie_t *tbl);
+
+/*! \brief Search the trie, returning NULL on failure. */
+trie_val_t* trie_get_try(trie_t *tbl, const trie_key_t *key, uint32_t len);
+
+/*! \brief Search the trie including DNS wildcard semantics, returning NULL on failure.
+ *
+ * \note We assume the key is in knot_dname_lf() format, i.e. labels are ordered
+ *   from root to leaf and separated by zero bytes (and no other zeros are allowed).
+ * \note Beware that DNS wildcard matching is not exactly what normal people would expect.
+ */
+trie_val_t* trie_get_try_wildcard(trie_t *tbl, const trie_key_t *key, uint32_t len);
+
+/*! \brief Search the trie, inserting NULL trie_val_t on failure. */
+trie_val_t* trie_get_ins(trie_t *tbl, const trie_key_t *key, uint32_t len);
+
+/*!
+ * \brief Search for less-or-equal element.
+ *
+ * \param tbl  Trie.
+ * \param key  Searched key.
+ * \param len  Key length.
+ * \param val  (optional) Value found; it will be set to NULL if not found or errored.
+ * \return KNOT_EOK for exact match, 1 for previous, KNOT_ENOENT for not-found,
+ *         or KNOT_E*.
+ */
+int trie_get_leq(trie_t *tbl, const trie_key_t *key, uint32_t len, trie_val_t **val);
+
+/*!
+ * \brief Apply a function to every trie_val_t, in order.
+ *
+ * \return KNOT_EOK if success or KNOT_E* if error.
+ */
+int trie_apply(trie_t *tbl, int (*f)(trie_val_t *, void *), void *d);
+
+/*!
+ * \brief Remove an item, returning KNOT_EOK if succeeded or KNOT_ENOENT if not found.
+ *
+ * If val!=NULL and deletion succeeded, the deleted value is set.
+ */
+int trie_del(trie_t *tbl, const trie_key_t *key, uint32_t len, trie_val_t *val);
+
+
+/*! \brief Create a new iterator pointing to the first element (if any).
+ *
+ * trie_it_* functions deal with these iterators capable of walking and jumping
+ * over the trie.  Note that any modification to key-set stored by the trie
+ * will in general invalidate all iterators and you will need to begin anew.
+ * (It won't be detected - you may end up reading freed memory, etc.)
+ */
+trie_it_t* trie_it_begin(trie_t *tbl);
+
+/*! \brief Test if the iterator has gone "past the end" (and points nowhere). */
+bool trie_it_finished(trie_it_t *it);
+
+/*! \brief Free any resources of the iterator. It's OK to call it on NULL. */
+void trie_it_free(trie_it_t *it);
+
+/*! \brief Copy the iterator.  See the warning in trie_it_begin(). */
+trie_it_t *trie_it_clone(const trie_it_t *it);
+
+/*!
+ * \brief Return pointer to the key of the current element.
+ *
+ * \note The len is uint32_t internally but size_t is better for our usage
+ *       as it is without an additional type conversion.
+ */
+const trie_key_t* trie_it_key(trie_it_t *it, size_t *len);
+
+/*! \brief Return pointer to the value of the current element (writable). */
+trie_val_t* trie_it_val(trie_it_t *it);
+
+/*!
+ * \brief Advance the iterator to the next element.
+ *
+ * Iteration is in ascending lexicographical order.
+ * In particular, the empty string would be considered as the very first.
+ *
+ * \TODO: in most iterator operations, ENOMEM is very unlikely
+ * but it leads to a _finished() iterator (silently).
+ * Perhaps the functions should simply return KNOT_E*
+ */
+void trie_it_next(trie_it_t *it);
+/*! \brief Advance the iterator to the previous element.  See trie_it_next(). */
+void trie_it_prev(trie_it_t *it);
+
+/*! \brief Advance iterator to the next element, looping to first after last. */
+void trie_it_next_loop(trie_it_t *it);
+/*! \brief Advance iterator to the previous element, looping to last after first. */
+void trie_it_prev_loop(trie_it_t *it);
+
+/*! \brief Advance iterator to the next element while ignoring the subtree.
+ *
+ * \note Another formulation: skip keys that are prefixed by the current key.
+ * \TODO: name, maybe _noprefixed?  The thing is that in the "subtree" meaning
+ * doesn't correspond to how the pointers go in the implementation,
+ * but we may not care much for implementation in the API...
+ */
+void trie_it_next_nosub(trie_it_t *it);
+
+/*! \brief Advance iterator to the longest prefix of the current key.
+ *
+ * \TODO: name, maybe _prefix?  Arguments similar to _nosub vs. _noprefixed.
+ */
+void trie_it_parent(trie_it_t *it);
+
+/*! \brief trie_get_leq() but with an iterator. */
+int trie_it_get_leq(trie_it_t *it, const trie_key_t *key, uint32_t len);
+
+/*! \brief Remove the current element.  The iterator will get trie_it_finished() */
+void trie_it_del(trie_it_t *it);
+
+
+/*! \brief Start a COW transaction
+ *
+ * A copy-on-write transaction starts by obtaining a write lock (in
+ * your application code) followed by a call to trie_cow(). This
+ * creates a shared clone of the trie and saves both old and new roots
+ * in the COW context.
+ *
+ * During the COW transaction, you call trie_cow_ins() or
+ * trie_cow_del() as necessary. These calls ensure that the relevant
+ * parts of the (new) trie are copied so that they can be modified
+ * freely.
+ *
+ * Your trie_val_t objects must be able to distinguish their
+ * reachability, either shared, or old-only, or new-only. Before a COW
+ * transaction the reachability of your objects is indeterminate.
+ * During a transaction, any trie_val_t objects that might be affected
+ * (because they are adjacent to a trie_get_cow() or trie_del_cow())
+ * are first marked as shared using the callback you pass to
+ * trie_cow().
+ *
+ * When the transaction is complete, to commit, call trie_cow_new() to
+ * get the new root, swap the old and new trie roots (e.g. with
+ * rcu_xchg_pointer()), wait for readers to finish with the old trie
+ * (e.g. using synchronize_rcu()), then call trie_cow_commit(). For a
+ * rollback, you can just call trie_cow_rollback() without waiting
+ * since that doesn't conflict with readers. After trie_cow_commit()
+ * or trie_cow_rollback() have finished, you can release your write
+ * lock.
+ *
+ * Concurrent reading of the old trie is allowed during a transaction
+ * provided that it is known when all readers have finished with the
+ * old version, e.g. using rcu_read_lock() and rcu_read_unlock().
+ * There must be only one write transaction at a time.
+ *
+ * \param old		the old trie
+ * \param mark_shared	callback to mark a leaf as shared (can be NULL)
+ * \param d		extra data for the callback
+ * \return		a pointer to a COW context,
+ *			or NULL if there was a failure
+ */
+trie_cow_t* trie_cow(trie_t *old, trie_cb *mark_shared, void *d);
+
+/*! \brief get the new trie from a COW context */
+trie_t* trie_cow_new(trie_cow_t *cow);
+
+/*! \brief variant of trie_get_ins() for use during COW transactions
+ *
+ * As necessary, this copies path from the root of the trie to the
+ * leaf, so that it is no longer shared. Any leaves adjacent to this
+ * path are marked as shared using the mark_shared callback passed to
+ * trie_cow().
+ *
+ * It is your responsibility to COW your trie_val_t objects. If you copy an
+ * object you must change the original's reachability from shared to old-only.
+ * New objects (including copies) must have new-only reachability.
+ */
+trie_val_t* trie_get_cow(trie_cow_t *cow, const trie_key_t *key, uint32_t len);
+
+/*!
+ * \brief variant of trie_del() for use during COW transactions
+ *
+ * The mark_shared callback is invoked as necessary, in the same way
+ * as trie_get_cow().
+ *
+ * Returns KNOT_EOK if the key was removed or KNOT_ENOENT if not found.
+ * If val!=NULL and deletion succeeded, the *val is set to the deleted
+ * value pointer.
+ */
+int trie_del_cow(trie_cow_t *cow, const trie_key_t *key, uint32_t len, trie_val_t *val);
+
+/*! \brief clean up the old trie after committing a COW transaction
+ *
+ * Your callback is invoked for any trie_val_t objects that might need
+ * cleaning up; you must free any objects you have marked as old-only
+ * and retain objects with shared reachability.
+ *
+ * \note The callback can be NULL.
+ *
+ * The cow object is free()d, and the new trie root is returned.
+ */
+trie_t* trie_cow_commit(trie_cow_t *cow, trie_cb *cb, void *d);
+
+/*! \brief clean up the new trie after rolling back a COW transaction
+ *
+ * Your callback is invoked for any trie_val_t objects that might need
+ * cleaning up; you must free any objects you have marked as new-only
+ * and retain objects with shared reachability.
+ *
+ * \note The callback can be NULL.
+ *
+ * The cow object is free()d, and the old trie root is returned.
+ */
+trie_t* trie_cow_rollback(trie_cow_t *cow, trie_cb *cb, void *d);
diff --git a/src/contrib/semaphore.c b/src/contrib/semaphore.c
new file mode 100644
index 0000000..ad50dcc
--- /dev/null
+++ b/src/contrib/semaphore.c
@@ -0,0 +1,80 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include "semaphore.h"
+
+#include <assert.h>
+#include <stdlib.h>
+
+#if defined(__APPLE__)
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+#endif
+
+void knot_sem_init(knot_sem_t *sem, unsigned int value)
+{
+	int ret = sem_init(&sem->semaphore, 1, value);
+	if (ret == 0) {
+		sem->status = -1;
+	} else {
+		sem->status = value;
+		sem->status_lock = malloc(sizeof(*sem->status_lock));
+		pthread_mutex_init(&sem->status_lock->mutex, NULL);
+		pthread_cond_init(&sem->status_lock->cond, NULL);
+	}
+}
+
+void knot_sem_wait(knot_sem_t *sem)
+{
+	if (sem->status < 0) {
+		int semret;
+		do {
+			semret = sem_wait(&sem->semaphore);
+		} while (semret != 0); // repeat wait as it might be interrupted by a signal
+	} else {
+		pthread_mutex_lock(&sem->status_lock->mutex);
+		while (sem->status == 0) {
+			pthread_cond_wait(&sem->status_lock->cond, &sem->status_lock->mutex);
+		}
+		sem->status--;
+		pthread_mutex_unlock(&sem->status_lock->mutex);
+	}
+}
+
+void knot_sem_post(knot_sem_t *sem)
+{
+	if (sem->status < 0) {
+		int semret = sem_post(&sem->semaphore);
+		(void)semret;
+		assert(semret == 0);
+	} else {
+		pthread_mutex_lock(&sem->status_lock->mutex);
+		sem->status++;
+		pthread_cond_signal(&sem->status_lock->cond);
+		pthread_mutex_unlock(&sem->status_lock->mutex);
+	}
+}
+
+void knot_sem_destroy(knot_sem_t *sem)
+{
+	knot_sem_wait(sem);
+	if (sem->status < 0) {
+		sem_destroy(&sem->semaphore);
+	} else {
+		pthread_cond_destroy(&sem->status_lock->cond);
+		pthread_mutex_destroy(&sem->status_lock->mutex);
+		free(sem->status_lock);
+	}
+}
diff --git a/src/contrib/semaphore.h b/src/contrib/semaphore.h
new file mode 100644
index 0000000..be49b7f
--- /dev/null
+++ b/src/contrib/semaphore.h
@@ -0,0 +1,41 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <pthread.h>
+#include <semaphore.h>
+
+#pragma once
+
+typedef struct {
+	pthread_mutex_t mutex;
+	pthread_cond_t cond;
+} knot_sem_mutex_t;
+
+typedef struct {
+	int status;
+	union {
+		sem_t semaphore;
+		knot_sem_mutex_t *status_lock;
+	};
+} knot_sem_t;
+
+void knot_sem_init(knot_sem_t *sem, unsigned int value);
+
+void knot_sem_wait(knot_sem_t *sem);
+
+void knot_sem_post(knot_sem_t *sem);
+
+void knot_sem_destroy(knot_sem_t *sem);
diff --git a/src/contrib/sockaddr.c b/src/contrib/sockaddr.c
new file mode 100644
index 0000000..229c0dd
--- /dev/null
+++ b/src/contrib/sockaddr.c
@@ -0,0 +1,356 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netdb.h>
+
+#include "libknot/errcode.h"
+#include "contrib/sockaddr.h"
+#include "contrib/openbsd/strlcpy.h"
+#include "contrib/macros.h"
+
+int sockaddr_len(const struct sockaddr_storage *ss)
+{
+	if (ss == NULL) {
+		return 0;
+	}
+
+	switch(ss->ss_family) {
+	case AF_INET:
+		return sizeof(struct sockaddr_in);
+	case AF_INET6:
+		return sizeof(struct sockaddr_in6);
+	case AF_UNIX:
+		return sizeof(struct sockaddr_un);
+	default:
+		return 0;
+	}
+}
+
+static int cmp_ipv4(const struct sockaddr_in *a, const struct sockaddr_in *b,
+                    bool ignore_port)
+{
+	if (a->sin_addr.s_addr < b->sin_addr.s_addr) {
+		return -1;
+	} else if (a->sin_addr.s_addr > b->sin_addr.s_addr) {
+		return 1;
+	} else {
+		return ignore_port ? 0 : a->sin_port - b->sin_port;
+	}
+}
+
+static int cmp_ipv6(const struct sockaddr_in6 *a, const struct sockaddr_in6 *b,
+                    bool ignore_port)
+{
+	int ret = memcmp(&a->sin6_addr, &b->sin6_addr, sizeof(struct in6_addr));
+	if (ret == 0) {
+		ret = ignore_port ? 0 : a->sin6_port - b->sin6_port;
+	}
+
+	return ret;
+}
+
+static int cmp_unix(const struct sockaddr_un *a, const struct sockaddr_un *b)
+{
+	int len_a = strnlen(a->sun_path, sizeof(a->sun_path));
+	int len_b = strnlen(b->sun_path, sizeof(b->sun_path));
+	int len_min = len_a <= len_b ? len_a : len_b;
+
+	int ret = strncmp(a->sun_path, b->sun_path, len_min);
+	if (ret == 0) {
+		ret = len_a - len_b;
+	}
+
+	return ret;
+}
+
+int sockaddr_cmp(const struct sockaddr_storage *a, const struct sockaddr_storage *b,
+                 bool ignore_port)
+{
+	if (a->ss_family != b->ss_family) {
+		return (int)a->ss_family - (int)b->ss_family;
+	}
+
+	switch (a->ss_family) {
+	case AF_UNSPEC:
+		return 0;
+	case AF_INET:
+		return cmp_ipv4((struct sockaddr_in *)a, (struct sockaddr_in *)b,
+		                ignore_port);
+	case AF_INET6:
+		return cmp_ipv6((struct sockaddr_in6 *)a, (struct sockaddr_in6 *)b,
+		                ignore_port);
+	case AF_UNIX:
+		return cmp_unix((struct sockaddr_un *)a, (struct sockaddr_un *)b);
+	default:
+		return 1;
+	}
+}
+
+int sockaddr_set(struct sockaddr_storage *ss, int family, const char *straddr, int port)
+{
+	if (ss == NULL || straddr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Set family and port. */
+	memset(ss, 0, sizeof(*ss));
+	ss->ss_family = family;
+	sockaddr_port_set(ss, port);
+
+	/* Initialize address depending on address family. */
+	if (family == AF_INET6) {
+		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)ss;
+		if (inet_pton(family, straddr, &ipv6->sin6_addr) < 1) {
+			return KNOT_ERROR;
+		}
+		return KNOT_EOK;
+	} else if (family == AF_INET) {
+		struct sockaddr_in *ipv4 = (struct sockaddr_in *)ss;
+		if (inet_pton(family, straddr, &ipv4->sin_addr) < 1) {
+			return KNOT_ERROR;
+		}
+		return KNOT_EOK;
+	} else if (family == AF_UNIX) {
+		struct sockaddr_un *un = (struct sockaddr_un *)ss;
+		size_t ret = strlcpy(un->sun_path, straddr, sizeof(un->sun_path));
+		if (ret >= sizeof(un->sun_path)) {
+			return KNOT_ESPACE;
+		}
+		return KNOT_EOK;
+	}
+
+	return KNOT_EINVAL;
+}
+
+void *sockaddr_raw(const struct sockaddr_storage *ss, size_t *addr_size)
+{
+	if (ss == NULL || addr_size == NULL) {
+		return NULL;
+	}
+
+	if (ss->ss_family == AF_INET) {
+		struct sockaddr_in *ipv4 = (struct sockaddr_in *)ss;
+		*addr_size = sizeof(ipv4->sin_addr);
+		return &ipv4->sin_addr;
+	} else if (ss->ss_family == AF_INET6) {
+		struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)ss;
+		*addr_size = sizeof(ipv6->sin6_addr);
+		return &ipv6->sin6_addr;
+	} else {
+		return NULL;
+	}
+}
+
+int sockaddr_set_raw(struct sockaddr_storage *ss, int family,
+                     const uint8_t *raw_addr, size_t raw_addr_size)
+{
+	if (ss == NULL || raw_addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	memset(ss, 0, sizeof(*ss));
+	ss->ss_family = family;
+
+	size_t ss_size = 0;
+	void *ss_data = sockaddr_raw(ss, &ss_size);
+	if (ss_data == NULL || ss_size != raw_addr_size) {
+		return KNOT_EINVAL;
+	}
+
+	memcpy(ss_data, raw_addr, ss_size);
+
+	return KNOT_EOK;
+}
+
+int sockaddr_tostr(char *buf, size_t maxlen, const struct sockaddr_storage *ss)
+{
+	if (ss == NULL || buf == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	const char *out = NULL;
+
+	/* Convert network address string. */
+	if (ss->ss_family == AF_INET6) {
+		const struct sockaddr_in6 *s = (const struct sockaddr_in6 *)ss;
+		out = inet_ntop(ss->ss_family, &s->sin6_addr, buf, maxlen);
+	} else if (ss->ss_family == AF_INET) {
+		const struct sockaddr_in *s = (const struct sockaddr_in *)ss;
+		out = inet_ntop(ss->ss_family, &s->sin_addr, buf, maxlen);
+	} else if (ss->ss_family == AF_UNIX) {
+		const struct sockaddr_un *s = (const struct sockaddr_un *)ss;
+		size_t ret = strlcpy(buf, s->sun_path, maxlen);
+		out = (ret < maxlen) ? buf : NULL;
+	} else {
+		return KNOT_EINVAL;
+	}
+
+	if (out == NULL) {
+		*buf = '\0';
+		return KNOT_ESPACE;
+	}
+
+	/* Write separator and port. */
+	int written = strlen(buf);
+	int port = sockaddr_port(ss);
+	if (port > 0) {
+		int ret = snprintf(&buf[written], maxlen - written, "@%d", port);
+		if (ret <= 0 || (size_t)ret >= maxlen - written) {
+			*buf = '\0';
+			return KNOT_ESPACE;
+		}
+
+		written += ret;
+	}
+
+	return written;
+}
+
+int sockaddr_port(const struct sockaddr_storage *ss)
+{
+	if (ss == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (ss->ss_family == AF_INET6) {
+		return ntohs(((struct sockaddr_in6 *)ss)->sin6_port);
+	} else if (ss->ss_family == AF_INET) {
+		return ntohs(((struct sockaddr_in *)ss)->sin_port);
+	} else {
+		return KNOT_EINVAL;
+	}
+}
+
+void sockaddr_port_set(struct sockaddr_storage *ss, uint16_t port)
+{
+	if (ss == NULL) {
+		return;
+	}
+
+	if (ss->ss_family == AF_INET6) {
+		((struct sockaddr_in6 *)ss)->sin6_port = htons(port);
+	} else if (ss->ss_family == AF_INET) {
+		((struct sockaddr_in *)ss)->sin_port = htons(port);
+	}
+}
+
+char *sockaddr_hostname(void)
+{
+	/* Fetch hostname. */
+	char host[256] = "";
+	if (gethostname(host, sizeof(host)) != 0) {
+		return NULL;
+	}
+	/* Just to be sure. */
+	host[sizeof(host) - 1] = '\0';
+
+	/* Fetch canonical name for this address/DNS. */
+	struct addrinfo hints, *info = NULL;
+	memset(&hints, 0, sizeof hints);
+	hints.ai_family = AF_UNSPEC;
+	hints.ai_socktype = SOCK_DGRAM;
+	hints.ai_flags = AI_CANONNAME;
+	if (getaddrinfo(host, "domain", &hints, &info) != 0) {
+		return NULL;
+	}
+
+	/* Fetch first valid hostname. */
+	char *hname = NULL;
+	struct addrinfo *p = NULL;
+	for (p = info; p != NULL; p = p->ai_next) {
+		if (p->ai_canonname) {
+			hname = strdup(p->ai_canonname);
+			break;
+		}
+	}
+
+	/* No valid hostname found, resort to gethostname() result */
+	if (hname == NULL) {
+		hname = strdup(host);
+	}
+
+	freeaddrinfo(info);
+	return hname;
+}
+
+bool sockaddr_is_any(const struct sockaddr_storage *ss)
+{
+	if (ss == NULL) {
+		return false;
+	}
+
+	if (ss->ss_family == AF_INET) {
+		const struct sockaddr_in *ipv4 = (struct sockaddr_in *)ss;
+		return ipv4->sin_addr.s_addr == INADDR_ANY;
+	}
+
+	if (ss->ss_family == AF_INET6) {
+		const struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)ss;
+		return memcmp(&ipv6->sin6_addr, &in6addr_any, sizeof(ipv6->sin6_addr)) == 0;
+	}
+
+	return false;
+}
+
+bool sockaddr_net_match(const struct sockaddr_storage *ss1,
+                        const struct sockaddr_storage *ss2,
+                        unsigned prefix)
+{
+	if (ss1 == NULL || ss2 == NULL) {
+		return false;
+	}
+
+	if (ss1->ss_family != ss2->ss_family) {
+		return false;
+	}
+
+	size_t raw_len = 0;
+	const uint8_t *raw_1 = sockaddr_raw(ss1, &raw_len);
+	const uint8_t *raw_2 = sockaddr_raw(ss2, &raw_len);
+
+	prefix = MIN(prefix, raw_len * 8);
+	unsigned bytes = prefix / 8;
+	unsigned bits = prefix % 8;
+
+	/* Compare full bytes. */
+	if (memcmp(raw_1, raw_2, bytes) != 0) {
+		return false;
+	}
+
+	/* Compare last partial byte. */
+	return bits == 0 ||
+	       (raw_1[bytes] >> (8 - bits) == raw_2[bytes] >> (8 - bits));
+}
+
+bool sockaddr_range_match(const struct sockaddr_storage *ss,
+                          const struct sockaddr_storage *ss_min,
+                          const struct sockaddr_storage *ss_max)
+{
+	if (ss == NULL || ss_min == NULL || ss_max == NULL) {
+		return false;
+	}
+
+	if (ss_min->ss_family != ss_max->ss_family ||
+	    ss_min->ss_family != ss->ss_family) {
+		return false;
+	}
+
+	return sockaddr_cmp(ss, ss_min, true) >= 0 &&
+	       sockaddr_cmp(ss, ss_max, true) <= 0;
+}
diff --git a/src/contrib/sockaddr.h b/src/contrib/sockaddr.h
new file mode 100644
index 0000000..f9228d7
--- /dev/null
+++ b/src/contrib/sockaddr.h
@@ -0,0 +1,160 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <stdint.h>
+#include <unistd.h>
+
+/* Subnet maximum prefix length. */
+#define IPV4_PREFIXLEN 32
+#define IPV6_PREFIXLEN 128
+
+/* Address string "address[@port]" maximum length. */
+#define SOCKADDR_STRLEN_EXT (1 + 6) /* '@', 5 digits number, \0 */
+#define SOCKADDR_STRLEN (sizeof(struct sockaddr_un) + SOCKADDR_STRLEN_EXT)
+
+/*!
+ * \brief Calculate current structure length based on address family.
+ *
+ * \param ss  Socket address.
+ *
+ * \return Number of bytes or error code.
+ */
+int sockaddr_len(const struct sockaddr_storage *ss);
+
+/*!
+ * \brief Compare addresses.
+ *
+ * \param a            First address.
+ * \param b            Second address.
+ * \param ignore_port  Ignore port indication.
+ *
+ * \return like memcmp(3)
+ */
+int sockaddr_cmp(const struct sockaddr_storage *a, const struct sockaddr_storage *b,
+                 bool ignore_port);
+
+/*!
+ * \brief Set address and port.
+ *
+ * \param ss       Socket address.
+ * \param family   Address family.
+ * \param straddr  IP address in string format.
+ * \param port     Port.
+ *
+ * \return KNOT_EOK on success or an error code.
+ */
+int sockaddr_set(struct sockaddr_storage *ss, int family, const char *straddr, int port);
+
+/*!
+ * \brief Return raw network address in network byte order.
+ *
+ * \param[in]  ss        Socket address.
+ * \param[out] addr_size Address length.
+ *
+ * \return Pointer to binary buffer of size addr_size.
+ */
+void *sockaddr_raw(const struct sockaddr_storage *ss, size_t *addr_size);
+
+/*!
+ * \brief Set raw address.
+ *
+ * \param ss             Socket address.
+ * \param family         Address family.
+ * \param raw_addr       IP address in binary format.
+ * \param raw_addr_size  Size of the binary address.
+ *
+ * \return KNOT_EOK on success or an error code.
+ */
+int sockaddr_set_raw(struct sockaddr_storage *ss, int family,
+                     const uint8_t *raw_addr, size_t raw_addr_size);
+
+/*!
+ * \brief Return string representation of socket address.
+ *
+ * \note String format: \<address>[@<port>], f.e. '127.0.0.1@53'
+ *
+ * \param buf     Destination for string representation.
+ * \param maxlen  Maximum number of written bytes.
+ * \param ss      Socket address.
+ *
+ * \return Number of bytes written on success, error code on failure.
+ */
+int sockaddr_tostr(char *buf, size_t maxlen, const struct sockaddr_storage *ss);
+
+/*!
+ * \brief Return port number from address.
+ *
+ * \param ss  Socket address.
+ *
+ * \return Port number or error code.
+ */
+int sockaddr_port(const struct sockaddr_storage *ss);
+
+/*!
+ * \brief Set port number.
+ *
+ * \param ss    Socket address.
+ * \param port  Port to set.
+ */
+void sockaddr_port_set(struct sockaddr_storage *ss, uint16_t port);
+
+/*!
+ * \brief Get host FQDN address.
+ *
+ * \return Hostname string or NULL.
+ */
+char *sockaddr_hostname(void);
+
+/*!
+ * \brief Check if address is ANY address.
+ *
+ * \param ss  Socket address.
+ */
+bool sockaddr_is_any(const struct sockaddr_storage *ss);
+
+/*!
+ * \brief Check if two addresses match the given network prefix.
+ *
+ * \param ss1     First address.
+ * \param ss2     Second address.
+ * \param prefix  Prefix length.
+ *
+ * \return True on match.
+ */
+bool sockaddr_net_match(const struct sockaddr_storage *ss1,
+                        const struct sockaddr_storage *ss2,
+                        unsigned prefix);
+
+/*!
+ * \brief Check if the address is within the given address range (inclusive).
+ *
+ * \param ss      Address to check.
+ * \param ss_min  Minimum address.
+ * \param ss_max  Maximum address.
+ *
+ * \return True on match.
+ */
+bool sockaddr_range_match(const struct sockaddr_storage *ss,
+                          const struct sockaddr_storage *ss_min,
+                          const struct sockaddr_storage *ss_max);
diff --git a/src/contrib/spinlock.h b/src/contrib/spinlock.h
new file mode 100644
index 0000000..52a6dd9
--- /dev/null
+++ b/src/contrib/spinlock.h
@@ -0,0 +1,130 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Multiplatform spinlock.
+ */
+
+#pragma once
+
+#if (__STDC_VERSION__ >= 201112L) && !defined(__STDC_NO_ATOMICS__)
+/* Not tested and activated yet. */
+/* #define HAVE_STDATOMIC */
+#endif
+
+#if defined(__APPLE__)
+#  if defined(MAC_OS_X_VERSION_10_12) || \
+      MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_12
+#    define APPLE_SPIN_NEW
+#  else
+#    define APPLE_SPIN_OLD
+#  endif	/* MAC_OS_X_VERSION_10_12 ... */
+#endif	/* __APPLE__ */
+
+#if defined(HAVE_STDATOMIC)
+#  include <stdatomic.h>
+#elif defined(APPLE_SPIN_NEW)
+#  include <os/lock.h>
+#elif defined(APPLE_SPIN_OLD)
+#  include <libkern/OSAtomic.h>
+#else	/* POSIX pthread spinlock. */
+#  include <pthread.h>
+#endif
+
+/*! \brief Spinlock lock variable type. */
+typedef
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC)
+	bool			/*!< Spinlock lock - a simple & fast atomic version. */
+#elif defined(HAVE_STDATOMIC)
+	atomic_bool		/*!< Spinlock lock - a simple & fast atomic version, C11 */
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock		/*!< Spinlock lock - a newer macOS version (macOS >= 10.12). */
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLock		/*!< Spinlock lock - an older macOS version (macOS < 10.12). */
+#else	/* POSIX */
+	pthread_spinlock_t	/*!< Spinlock lock - a POSIX pthread version. */
+#endif
+	knot_spin_t;
+
+/*! \brief Initialize the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_init(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC)
+	*lock = false;
+#elif defined(HAVE_STDATOMIC)
+	atomic_init(lock, false);
+#elif defined(APPLE_SPIN_NEW)
+	*lock = OS_UNFAIR_LOCK_INIT;
+#elif defined(APPLE_SPIN_OLD)
+	*lock = OS_SPINLOCK_INIT;
+#else	/* POSIX */
+	pthread_spin_init(lock, PTHREAD_PROCESS_PRIVATE);
+#endif
+}
+
+/*! \brief Destroy the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_destroy(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC) || defined(HAVE_ATOMIC) || defined(HAVE_STDATOMIC) || \
+    defined(APPLE_SPIN_NEW) || defined(APPLE_SPIN_OLD)
+	/* Nothing needed here. */
+#else	/* POSIX */
+	pthread_spin_destroy(lock);
+#endif
+}
+
+/*! \brief Lock the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_lock(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC)
+	while (__sync_lock_test_and_set(lock, 1)) {
+	}
+#elif defined(HAVE_ATOMIC)
+	int expected = 0;
+        while (!__atomic_compare_exchange_n(lock, &expected, 1, false, __ATOMIC_RELAXED, __ATOMIC_RELAXED)) {
+		expected = 0;
+	}
+#elif defined(HAVE_STDATOMIC)
+	int expected = 0;
+	while (!atomic_compare_exchange_strong(lock, &expected, false)) {
+		expected = 0;
+	}
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock_lock(lock);
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLockLock(lock);
+#else	/* POSIX */
+	pthread_spin_lock(lock);
+#endif
+}
+
+/*! \brief Unlock the spinlock pointed to by the parameter "lock". */
+static inline void knot_spin_unlock(knot_spin_t *lock)
+{
+#if defined(HAVE_SYNC_ATOMIC)
+	__sync_lock_release(lock);
+#elif defined(HAVE_ATOMIC)
+	__atomic_clear(lock, __ATOMIC_RELAXED);
+#elif defined(HAVE_STDATOMIC)
+	atomic_store(lock, false);
+#elif defined(APPLE_SPIN_NEW)
+	os_unfair_lock_unlock(lock);
+#elif defined(APPLE_SPIN_OLD)
+	OSSpinLockUnlock(lock);
+#else	/* POSIX */
+	pthread_spin_unlock(lock);
+#endif
+}
diff --git a/src/contrib/string.c b/src/contrib/string.c
new file mode 100644
index 0000000..4146c96
--- /dev/null
+++ b/src/contrib/string.c
@@ -0,0 +1,227 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#if defined(HAVE_EXPLICIT_BZERO)
+  #if defined(HAVE_BSD_STRING_H)
+    #include <bsd/string.h>
+  #endif
+  /* #include <string.h> is needed. */
+#elif defined(HAVE_EXPLICIT_MEMSET)
+  /* #include <string.h> is needed. */
+#elif defined(HAVE_GNUTLS_MEMSET)
+  #include <gnutls/gnutls.h>
+#else
+  #define USE_CUSTOM_MEMSET
+#endif
+
+#include "contrib/string.h"
+#include "contrib/ctype.h"
+#include "contrib/tolower.h"
+
+uint8_t *memdup(const uint8_t *data, size_t data_size)
+{
+	uint8_t *result = (uint8_t *)malloc(data_size);
+	if (!result) {
+		return NULL;
+	}
+
+	return memcpy(result, data, data_size);
+}
+
+char *sprintf_alloc(const char *fmt, ...)
+{
+	char *strp = NULL;
+	va_list ap;
+
+	va_start(ap, fmt);
+	int ret = vasprintf(&strp, fmt, ap);
+	va_end(ap);
+
+	if (ret < 0) {
+		return NULL;
+	}
+	return strp;
+}
+
+char *strcdup(const char *s1, const char *s2)
+{
+	if (!s1 || !s2) {
+		return NULL;
+	}
+
+	size_t s1len = strlen(s1);
+	size_t s2len = strlen(s2);
+	size_t nlen = s1len + s2len + 1;
+
+	char* dst = malloc(nlen);
+	if (dst == NULL) {
+		return NULL;
+	}
+
+	memcpy(dst, s1, s1len);
+	memcpy(dst + s1len, s2, s2len + 1);
+	return dst;
+}
+
+char *strstrip(const char *str)
+{
+	// leading white-spaces
+	const char *scan = str;
+	while (is_space(scan[0])) {
+		scan += 1;
+	}
+
+	// trailing white-spaces
+	size_t len = strlen(scan);
+	while (len > 0 && is_space(scan[len - 1])) {
+		len -= 1;
+	}
+
+	char *trimmed = malloc(len + 1);
+	if (!trimmed) {
+		return NULL;
+	}
+
+	memcpy(trimmed, scan, len);
+	trimmed[len] = '\0';
+
+	return trimmed;
+}
+
+void strtolower(char *str)
+{
+	if (str == NULL) {
+		return;
+	}
+
+	for (char *it = str; *it != '\0'; ++it) {
+		*it = knot_tolower(*it);
+	}
+}
+
+int const_time_memcmp(const void *s1, const void *s2, size_t n)
+{
+	volatile uint8_t equal = 0;
+
+	for (size_t i = 0; i < n; i++) {
+		equal |= ((uint8_t *)s1)[i] ^ ((uint8_t *)s2)[i];
+	}
+
+	return equal;
+}
+
+#if defined(USE_CUSTOM_MEMSET)
+typedef void *(*memset_t)(void *, int, size_t);
+static volatile memset_t volatile_memset = memset;
+#endif
+
+void *memzero(void *s, size_t n)
+{
+#if defined(HAVE_EXPLICIT_BZERO)	/* In OpenBSD since 5.5. */
+					/* In FreeBSD since 11.0. */
+					/* In glibc since 2.25. */
+					/* In DragonFly BSD since 5.5. */
+	explicit_bzero(s, n);
+	return s;
+#elif defined(HAVE_EXPLICIT_MEMSET)	/* In NetBSD since 7.0. */
+	return explicit_memset(s, 0, n);
+#elif defined(HAVE_GNUTLS_MEMSET)	/* In GnuTLS since 3.4.0. */
+	gnutls_memset(s, 0, n);
+	return s;
+#else					/* Knot custom solution as a fallback. */
+	/* Warning: the use of the return value is *probably* needed
+	 * so as to avoid the volatile_memset() to be optimized out.
+	 */
+	return volatile_memset(s, 0, n);
+#endif
+}
+
+static const char BIN_TO_HEX[] = {
+	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
+};
+
+char *bin_to_hex(const uint8_t *bin, size_t bin_len)
+{
+	if (bin == NULL) {
+		return NULL;
+	}
+
+	size_t hex_size = bin_len * 2;
+	char *hex = malloc(hex_size + 1);
+	if (hex == NULL) {
+		return NULL;
+	}
+
+	for (size_t i = 0; i < bin_len; i++) {
+		hex[2 * i]     = BIN_TO_HEX[bin[i] >> 4];
+		hex[2 * i + 1] = BIN_TO_HEX[bin[i] & 0x0f];
+	}
+	hex[hex_size] = '\0';
+
+	return hex;
+}
+
+/*!
+ * Convert HEX character to numeric value (assumes valid input).
+ */
+static uint8_t hex_to_number(const char hex)
+{
+	if (hex >= '0' && hex <= '9') {
+		return hex - '0';
+	} else if (hex >= 'a' && hex <= 'f') {
+		return hex - 'a' + 10;
+	} else {
+		assert(hex >= 'A' && hex <= 'F');
+		return hex - 'A' + 10;
+	}
+}
+
+uint8_t *hex_to_bin(const char *hex, size_t *out_len)
+{
+	if (hex == NULL || out_len == NULL) {
+		return NULL;
+	}
+
+	size_t hex_len = strlen(hex);
+	if (hex_len % 2 != 0) {
+		return NULL;
+	}
+
+	size_t bin_len = hex_len / 2;
+	uint8_t *bin = malloc(bin_len + 1);
+	if (bin == NULL) {
+		return NULL;
+	}
+
+	for (size_t i = 0; i < bin_len; i++) {
+		if (!is_xdigit(hex[2 * i]) || !is_xdigit(hex[2 * i + 1])) {
+			free(bin);
+			return NULL;
+		}
+		uint8_t high = hex_to_number(hex[2 * i]);
+		uint8_t low  = hex_to_number(hex[2 * i + 1]);
+		bin[i] = high << 4 | low;
+	}
+
+	*out_len = bin_len;
+
+	return bin;
+}
diff --git a/src/contrib/string.h b/src/contrib/string.h
new file mode 100644
index 0000000..65c2eb6
--- /dev/null
+++ b/src/contrib/string.h
@@ -0,0 +1,98 @@
+/*  Copyright (C) 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief String manipulations.
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+/*!
+ * \brief Create a copy of a binary buffer.
+ *
+ * Like \c strdup, but for binary data.
+ */
+uint8_t *memdup(const uint8_t *data, size_t data_size);
+
+/*!
+ * \brief Format string and take care of allocating memory.
+ *
+ * \note sprintf(3) manual page reference implementation.
+ *
+ * \param fmt Message format.
+ * \return formatted message or NULL.
+ */
+char *sprintf_alloc(const char *fmt, ...);
+
+/*!
+ * \brief Create new string from a concatenation of s1 and s2.
+ *
+ * \param s1 First string.
+ * \param s2 Second string.
+ *
+ * \retval Newly allocated string on success.
+ * \retval NULL on error.
+ */
+char *strcdup(const char *s1, const char *s2);
+
+/*!
+ * \brief Create a copy of a string skipping leading and trailing white spaces.
+ *
+ * \return Newly allocated string, NULL in case of error.
+ */
+char *strstrip(const char *str);
+
+/*!
+ * \brief Convert upper-case letters to lower-case in a string.
+ */
+void strtolower(char *str);
+
+/*!
+ * \brief Compare data in time based on string length.
+ *        This function just checks for (in)equality not for relation
+ *
+ * \param s1 The first address to compare.
+ * \param s2 The second address to compare.
+ * \param n The size of memory to compare.
+ *
+ * \return Non zero on difference and zero if the buffers are identical.
+ */
+int const_time_memcmp(const void *s1, const void *s2, size_t n);
+
+/*!
+ * \brief Fill memory with zeroes.
+ *
+ * Inspired by OPENSSL_cleanse. Such a memset shouldn't be optimized out.
+ *
+ * \param s The address to fill.
+ * \param n The size of memory to fill.
+ *
+ * \return Pointer to the memory.
+ */
+void *memzero(void *s, size_t n);
+
+/*!
+ * \brief Convert binary data to hexadecimal string.
+ */
+char *bin_to_hex(const uint8_t *bin, size_t bin_len);
+
+/*!
+ * \brief Convert hex encoded string to binary data.
+ */
+uint8_t *hex_to_bin(const char *hex, size_t *out_len);
diff --git a/src/contrib/strtonum.h b/src/contrib/strtonum.h
new file mode 100644
index 0000000..849f66f
--- /dev/null
+++ b/src/contrib/strtonum.h
@@ -0,0 +1,125 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <errno.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#include "libknot/errcode.h"
+#include "contrib/ctype.h"
+
+inline static int intmax_from_str(const char *src, intmax_t *dst,
+                                  intmax_t min, intmax_t max)
+{
+	if (!is_digit(*src) && *src != '-' && *src != '+') {
+		return KNOT_EINVAL;
+	}
+
+	errno = 0;
+	char *end = NULL;
+	intmax_t result = strtoimax(src, &end, 10);
+
+	if (errno == ERANGE) {
+		return KNOT_ERANGE;
+	}
+
+	if (src == end || *end != '\0') {
+		return KNOT_EINVAL;
+	}
+
+	if (result < min || result > max) {
+		return KNOT_ERANGE;
+	}
+
+	*dst = result;
+	return KNOT_EOK;
+}
+
+inline static int uintmax_from_str(const char *src, uintmax_t *dst,
+                                   uintmax_t min, uintmax_t max)
+{
+	if (!is_digit(*src) && *src != '+') {
+		return KNOT_EINVAL;
+	}
+
+	errno = 0;
+	char *end = NULL;
+	uintmax_t result = strtoumax(src, &end, 10);
+
+	if (errno == ERANGE) {
+		return KNOT_ERANGE;
+	}
+
+	if (src == end || *end != '\0') {
+		return KNOT_EINVAL;
+	}
+
+	if (result < min || result > max) {
+		return KNOT_ERANGE;
+	}
+
+	*dst = result;
+	return KNOT_EOK;
+}
+
+#define CONVERT(prefix, type, min, max, src, dst)                 \
+{                                                                 \
+	assert(src && dst);                                       \
+	prefix##max_t value;                                      \
+	int result = prefix##max_from_str(src, &value, min, max); \
+	if (result != KNOT_EOK) {                                 \
+		return result;                                    \
+	}                                                         \
+	*dst = (type)value;                                       \
+	return KNOT_EOK;                                          \
+}
+
+inline static int str_to_int(const char *src, int *dst, int min, int max)
+{
+	CONVERT(int, int, min, max, src, dst);
+}
+
+inline static int str_to_u8(const char *src, uint8_t *dst)
+{
+	CONVERT(uint, uint8_t, 0, UINT8_MAX, src, dst);
+}
+
+inline static int str_to_u16(const char *src, uint16_t *dst)
+{
+	CONVERT(uint, uint16_t, 0, UINT16_MAX, src, dst);
+}
+
+inline static int str_to_u32(const char *src, uint32_t *dst)
+{
+	CONVERT(uint, uint32_t, 0, UINT32_MAX, src, dst);
+}
+
+inline static int str_to_u64(const char *src, uint64_t *dst)
+{
+	CONVERT(uint, uint64_t, 0, UINT64_MAX, src, dst);
+}
+
+inline static int str_to_size(const char *src, size_t *dst, size_t min, size_t max)
+{
+	CONVERT(uint, size_t, min, max, src, dst);
+}
+
+#undef CONVERT
diff --git a/src/contrib/time.c b/src/contrib/time.c
new file mode 100644
index 0000000..8a4c467
--- /dev/null
+++ b/src/contrib/time.c
@@ -0,0 +1,405 @@
+/*  Copyright (C) 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "contrib/time.h"
+#include "contrib/ctype.h"
+#ifndef HAVE_CLOCK_GETTIME
+	#include <sys/time.h>
+#endif
+
+struct timespec time_now(void)
+{
+	struct timespec result = { 0 };
+
+#ifdef HAVE_CLOCK_GETTIME
+	clock_gettime(CLOCK_MONOTONIC, &result);
+#else // OS X < Sierra fallback.
+	struct timeval tmp = { 0 };
+	gettimeofday(&tmp, NULL);
+	result.tv_sec = tmp.tv_sec;
+	result.tv_nsec = 1000 * tmp.tv_usec;
+#endif
+
+	return result;
+}
+
+struct timespec time_diff(const struct timespec *begin, const struct timespec *end)
+{
+	struct timespec result = { 0 };
+
+	if (end->tv_nsec >= begin->tv_nsec) {
+		result.tv_sec  = end->tv_sec - begin->tv_sec;
+		result.tv_nsec = end->tv_nsec - begin->tv_nsec;
+	} else {
+		result.tv_sec  = end->tv_sec - begin->tv_sec - 1;
+		result.tv_nsec = 1000000000 - begin->tv_nsec + end->tv_nsec;
+	}
+
+	return result;
+}
+
+double time_diff_ms(const struct timespec *begin, const struct timespec *end)
+{
+	struct timespec result = time_diff(begin, end);
+
+	return (result.tv_sec * 1e3) + (result.tv_nsec / 1e6);
+}
+
+typedef struct {
+	const char *format;
+	const char *timespec;
+	const char *parsed;
+	knot_timediff_t offset;
+	char offset_sign;
+	char offset_unit;
+	struct tm calendar;
+	int error;
+} time_ctx_t;
+
+// After casting (struct tm) to (int []), we can use indexes...
+static int calendar_index(char ind)
+{
+	switch (ind) {
+	case 'Y': return 5;
+	case 'M': return 4;
+	case 'D': return 3;
+	case 'h': return 2;
+	case 'm': return 1;
+	case 's': return 0;
+	default: assert(0); return 6;
+	}
+}
+
+static size_t calendar_digits(int index)
+{
+	return index == 5 ? 4 : 2;
+}
+
+static size_t unit_value(char unit)
+{
+	size_t val = 1;
+	switch (unit) {
+	case 'M':
+		return 3600 * 24 * 30;
+	case 'Y':
+		val *= 365;
+		// FALLTHROUGH
+	case 'D':
+		val *= 24;
+		// FALLTHROUGH
+	case 'h':
+		val *= 60;
+		// FALLTHROUGH
+	case 'm':
+		val *= 60;
+		// FALLTHROUGH
+	case 's':
+	default:
+		return val;
+	}
+}
+
+static knot_time_t time_ctx_finalize(time_ctx_t *ctx)
+{
+	if (ctx->offset_sign) {
+		ctx->offset *= unit_value(ctx->offset_unit);
+		return knot_time_add(knot_time(), (ctx->offset_sign == '-' ? -1 : 1) * ctx->offset);
+	} else if (ctx->offset) {
+		return (knot_time_t)ctx->offset;
+	} else if (ctx->calendar.tm_year != 0) {
+		ctx->calendar.tm_isdst = -1;
+		ctx->calendar.tm_year -= 1900;
+		ctx->calendar.tm_mon -= 1;
+		// Set UTC timezone before using mktime
+		putenv("TZ=UTC");
+		tzset();
+		return (knot_time_t)mktime(&ctx->calendar);
+	} else {
+		return (knot_time_t)0;
+	}
+}
+
+static void time_ctx_reset(time_ctx_t *ctx)
+{
+	ctx->parsed = ctx->timespec;
+	ctx->offset = 0;
+	ctx->offset_sign = 0;
+	memset(&ctx->calendar, 0, sizeof(ctx->calendar));
+	ctx->error = 0;
+}
+
+static void parse_quote(time_ctx_t *ctx)
+{
+	while (*ctx->format != '|' && *ctx->format != '\0') {
+		if (*ctx->format == '\'') {
+			ctx->format++;
+			return;
+		}
+		if (*ctx->format++ != *ctx->parsed++) {
+			ctx->error = -1;
+			return;
+		}
+	}
+	ctx->error = -2;
+	return;
+}
+
+static void parse_offset(time_ctx_t *ctx)
+{
+	ctx->offset = 0;
+	ctx->error = -1;
+	while (is_digit(*ctx->parsed)) {
+		ctx->offset *= 10;
+		ctx->offset += *ctx->parsed++ - '0';
+		ctx->error = 0;
+	}
+}
+
+static void parse_calendar(time_ctx_t *ctx, int index)
+{
+	int *cal_arr = (int *)&ctx->calendar;
+	cal_arr[index] = 0;
+	for (size_t i = 0; i < calendar_digits(index); i++) {
+		if (!is_digit(*ctx->parsed)) {
+			ctx->error = -1;
+			return;
+		}
+		cal_arr[index] *= 10;
+		cal_arr[index] += *ctx->parsed++ - '0';
+	}
+}
+
+static void parse_sign(time_ctx_t *ctx)
+{
+	char sign1 = *(ctx->format - 1), sign2 = *ctx->format;
+
+	bool use_sign2 = (sign2 == '+' || sign2 == '-');
+
+	bool allow_plus = (sign1 == '+' || (sign1 == '-' && sign2 == '+'));
+	bool allow_minus = (sign1 == '-' || (sign1 == '+' && sign2 == '-'));
+	assert(sign1 == '+' || sign1 == '-');
+
+	if ((*ctx->parsed == '+' && allow_plus) || (*ctx->parsed == '-' && allow_minus)) {
+		ctx->offset_sign = *ctx->parsed++;
+		ctx->format += (use_sign2 ? 1 : 0);
+	} else {
+		ctx->error = -11;
+	}
+}
+
+static void parse_unit1(time_ctx_t *ctx)
+{
+	char u = *ctx->parsed++;
+	switch (u) {
+	case 'Y':
+	case 'M':
+	case 'D':
+	case 'h':
+	case 'm':
+	case 's':
+		ctx->offset_unit = u;
+		break;
+	default:
+		ctx->error = -1;
+	}
+}
+
+static void parse_unit2(time_ctx_t *ctx)
+{
+	char u = *ctx->parsed++;
+	switch (u) {
+	case 'y':
+	case 'd':
+		ctx->offset_unit = toupper((unsigned char)u);
+		break;
+	case 'h':
+	case 's':
+		ctx->offset_unit = u;
+		break;
+	case 'm':
+		switch (*ctx->parsed++) {
+		case 'o':
+			ctx->offset_unit = 'M';
+			break;
+		case 'i':
+			ctx->offset_unit = 'm';
+			break;
+		default:
+			ctx->error = -1;
+		}
+		break;
+	default:
+		ctx->error = -1;
+	}
+}
+
+int knot_time_parse(const char *format, const char *timespec, knot_time_t *time)
+{
+	if (format == NULL || timespec == NULL || time == NULL) {
+		return -1;
+	}
+
+	time_ctx_t ctx = {
+		.format = format,
+		.timespec = timespec,
+		.parsed = timespec,
+		.offset = 0,
+		.offset_sign = 0,
+		// we hope that .calendar is zeroed by default
+		.error = 0,
+	};
+
+	while (ctx.error == 0 && *ctx.format != '\0') {
+		switch (*ctx.format++) {
+		case '|':
+			if (*ctx.parsed == '\0') {
+				*time = time_ctx_finalize(&ctx);
+				return 0;
+			} else {
+				time_ctx_reset(&ctx);
+			}
+			break;
+		case '\'':
+			parse_quote(&ctx);
+			break;
+		case '#':
+			parse_offset(&ctx);
+			break;
+		case 'Y':
+		case 'M':
+		case 'D':
+		case 'h':
+		case 'm':
+		case 's':
+			parse_calendar(&ctx, calendar_index(*(ctx.format - 1)));
+			break;
+		case '+':
+		case '-':
+			parse_sign(&ctx);
+			break;
+		case 'U':
+			parse_unit1(&ctx);
+			break;
+		case 'u':
+			parse_unit2(&ctx);
+			break;
+		default:
+			return -1;
+		}
+
+		if (ctx.error < 0) {
+			while (*ctx.format != '|' && *ctx.format != '\0') {
+				ctx.format++;
+			}
+			time_ctx_reset(&ctx);
+			ctx.error = (*ctx.format == '\0' ? -1 : 0);
+		}
+	}
+
+	if (ctx.error == 0 && *ctx.parsed == '\0') {
+		*time = time_ctx_finalize(&ctx);
+		return 0;
+	}
+	return -1;
+}
+
+static char *unit_names_mixed[] = { "Y", "M", "D", "h", "m", "s" };
+static char *unit_names_lower[] = { "y", "mo", "d", "h", "mi", "s" };
+static size_t unit_sizes[] = { 3600*24*365, 3600*24*30, 3600*24, 3600, 60, 1 };
+static const size_t unit_count = 6;
+
+static int print_unit(char *dst, size_t dst_len, char *unit_names[unit_count],
+                      size_t max_units, knot_time_t time)
+{
+	int ret;
+	if (time == 0) {
+		ret = snprintf(dst, dst_len, "0");
+		return (ret < 0 || ret >= dst_len ? -1 : 0);
+	}
+	knot_timediff_t diff = knot_time_diff(time, knot_time());
+	if (dst_len-- < 1) {
+		return -1;
+	}
+	*dst++ = (diff < 0 ? '-' : '+');
+	if (diff < 0) {
+		diff = -diff;
+	} else if (diff == 0) {
+		ret = snprintf(dst, dst_len, "0%s", unit_names[unit_count - 1]);
+		return (ret < 0 || ret >= dst_len ? -1 : 0);
+	}
+	size_t curr_unit = 0, used_units = 0;
+	while (curr_unit < unit_count && used_units < max_units) {
+		if (diff >= unit_sizes[curr_unit]) {
+			ret = snprintf(dst, dst_len, "%"KNOT_TIMEDIFF_PRINTF"%s",
+			               diff / unit_sizes[curr_unit],
+			               unit_names[curr_unit]);
+			if (ret < 0 || ret >= dst_len) {
+				return -1;
+			}
+			dst += ret;
+			dst_len -= ret;
+			used_units++;
+			diff %= unit_sizes[curr_unit];
+		}
+		curr_unit++;
+	}
+	return 0;
+}
+
+int knot_time_print(knot_time_print_t format, knot_time_t time, char *dst, size_t dst_len)
+{
+	if (dst == NULL) {
+		return -1;
+	}
+
+	int ret;
+	switch (format) {
+	case TIME_PRINT_UNIX:
+		ret = snprintf(dst, dst_len, "%"KNOT_TIME_PRINTF, time);
+		return ((ret >= 0 && ret < dst_len) ? 0 : -1);
+	case TIME_PRINT_ISO8601:
+		if (time > LONG_MAX) {
+			return -1;
+		}
+
+		// Set timezone to UTC before using timezone dependent functions
+		putenv("TZ=UTC");
+		tzset();
+
+		struct tm lt;
+		time_t tt = (time_t)time;
+		ret = (localtime_r(&tt, &lt) == NULL ? -1 :
+		       strftime(dst, dst_len, "%Y-%m-%dT%H:%M:%SZ", &lt));
+		return (ret > 0 ? 0 : -1);
+	case TIME_PRINT_RELSEC:
+		ret = snprintf(dst, dst_len, "%+"KNOT_TIMEDIFF_PRINTF,
+		               knot_time_diff(time, knot_time()));
+		return ((ret >= 0 && ret < dst_len) ? 0 : -1);
+	case TIME_PRINT_HUMAN_MIXED:
+		return print_unit(dst, dst_len, unit_names_mixed, unit_count, time);
+	case TIME_PRINT_HUMAN_LOWER:
+		return print_unit(dst, dst_len, unit_names_lower, unit_count, time);
+	default:
+		return -1;
+	}
+}
diff --git a/src/contrib/time.h b/src/contrib/time.h
new file mode 100644
index 0000000..019b8c3
--- /dev/null
+++ b/src/contrib/time.h
@@ -0,0 +1,180 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <time.h>
+#include <inttypes.h>
+
+#ifdef __APPLE__
+ #define st_mtim st_mtimespec
+#endif
+
+/*!
+ * \brief Specify output format for knot_time_print().
+ */
+typedef enum {
+	TIME_PRINT_UNIX,	// numeric UNIX time
+	TIME_PRINT_ISO8601,	// 2016-12-31T23:59:00
+	TIME_PRINT_RELSEC,	// relative +6523
+	TIME_PRINT_HUMAN_MIXED,	// relative with mixed-case units
+	TIME_PRINT_HUMAN_LOWER,	// relative with lower-case units
+} knot_time_print_t;
+
+/*!
+ * \brief Get current time.
+ */
+struct timespec time_now(void);
+
+/*!
+ * \brief Get time elapsed between two events.
+ */
+struct timespec time_diff(const struct timespec *begin, const struct timespec *end);
+
+/*!
+ * \brief Get time elapsed between two events in miliseconds.
+ */
+double time_diff_ms(const struct timespec *begin, const struct timespec *end);
+
+/*!
+ * \brief Data type for keeping UNIX timestamps.
+ *
+ * This is because time_t can be 32-bit on some systems, which is bad.
+ * Zero value represents infinity.
+ */
+typedef uint64_t knot_time_t;
+
+/*!
+ * \brief Data type for keeping time differences.
+ */
+typedef int64_t knot_timediff_t;
+
+#define KNOT_TIMEDIFF_MIN INT64_MIN
+#define KNOT_TIMEDIFF_MAX INT64_MAX
+
+#define KNOT_TIME_PRINTF PRIu64
+#define KNOT_TIMEDIFF_PRINTF PRId64
+
+/*!
+ * \brief Returns current time sice epoch.
+ */
+inline static knot_time_t knot_time(void)
+{
+	return (knot_time_t)time(NULL);
+}
+
+/*!
+ * \brief Compare two timestamps.
+ *
+ * \return 0 if equal, -1 if the former is smaller (=earlier), 1 else.
+ */
+inline static int knot_time_cmp(knot_time_t a, knot_time_t b)
+{
+	return (a == b ? 0 : 1) * ((a && b) == 0 ? -1 : 1) * (a < b ? -1 : 1);
+}
+
+/*!
+ * \brief Return the smaller (=earlier) from given two timestamps.
+ */
+inline static knot_time_t knot_time_min(knot_time_t a, knot_time_t b)
+{
+	if ((a && b) == 0) {
+		return a + b;
+	} else {
+		return (a < b ? a : b);
+	}
+}
+
+/*!
+ * \brief Return the difference between two timestamps (to "minus" from).
+ *
+ * \note If both are zero (=infinity), KNOT_TIMEDIFF_MAX is returned.
+ */
+inline static knot_timediff_t knot_time_diff(knot_time_t to, knot_time_t from)
+{
+	if ((to && from) == 0) {
+		return (to > from ? KNOT_TIMEDIFF_MIN : KNOT_TIMEDIFF_MAX);
+	} else {
+		return (knot_timediff_t)to - (knot_timediff_t)from;
+	}
+}
+
+/*!
+ * \brief Add a time difference to timestamp.
+ */
+inline static knot_time_t knot_time_add(knot_time_t since, knot_timediff_t howlong)
+{
+	return (since != 0 ? since + howlong : since);
+}
+
+inline static knot_time_t knot_time_plus(knot_time_t a, knot_time_t b)
+{
+	return ((a && b) ? a + b : 0);
+}
+
+/*!
+ * \brief Convert uint32_t-encoded timestamp to knot_time_t.
+ *
+ * In RRSIG rdata, there are inception and expiration timestamps in uint32_t format.
+ * One shall use 'serial arithmetics' to decode them.
+ *
+ * \todo However it needs time(now) context which is slow to obtain, so we don't do it
+ *       for now. Please fix this in next 100 years.
+ */
+inline static knot_time_t knot_time_from_u32(uint32_t u32time)
+{
+	return (knot_time_t)u32time;
+}
+
+/*!
+ * \brief Parse a text-formatted timestamp to knot_time_t using format specification.
+ *
+ * \param format    The timestamp text format specification.
+ * \param timespec  Text-formatted timestamp.
+ * \param time      The parsed timestamp.
+ *
+ * The format specification basics:
+ * <format 1>|<format 2> - The pipe sign separates two time format specifications. Leftmost
+ *                         specification matching the timespec is used.
+ * '<a string>'          - Matches exactly <a string> (not containing apostrophes) in timespec.
+ * #                     - Hashtag matches for a number in timespec, stands for either a UNIX timestamp,
+ *                         or, within a context of an unit, as a number of such units.
+ * Y, M, D, h, m, s      - Matches a number, stands for a number of years, months, days, hours,
+ *                         minutes and seconds, respectively.
+ * +, -                  - The + and - signs declaring that following timespec is relative to "now".
+ *                         A single sign can be used to limit the timestamp being in future or in past,
+ *                         or both +- allow the timestamp to select any (just one) of them.
+ * U                     - Matches one of Y, M, D, h, m, s in the timespec standing for a time unit.
+ * u                     - Like U, but the unit in the timestamp is from: y, mo, d, h, mi, s.
+ *
+ * \retval -1  An error occurred, out_time has no sense.
+ * \return  0  OK, timestamp parsed successfully.
+ */
+int knot_time_parse(const char *format, const char *timespec, knot_time_t *time);
+
+/*!
+ * \brief Print the timestamp in specified format into a string buffer.
+ *
+ * \param format   The timestamp text format specification.
+ * \param time     The timestamp to be printed.
+ * \param dst      The destination buffer pointer with text-formatted timestamp.
+ * \param dst_len  The destination buffer length.
+ *
+ * \retval -1 An error occurred, the buffer may be filled with nonsense.
+ * \return  0 OK, timestamp printed successfully.
+ */
+int knot_time_print(knot_time_print_t format, knot_time_t time, char *dst, size_t dst_len);
diff --git a/src/contrib/tolower.h b/src/contrib/tolower.h
new file mode 100644
index 0000000..c8b4897
--- /dev/null
+++ b/src/contrib/tolower.h
@@ -0,0 +1,52 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Table for converting ASCII characters to lowercase.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*!
+ * \brief Converts binary character to lowercase.
+ *
+ * \param c  Character code.
+ *
+ * \return \a c converted to lowercase (or \a c if not applicable).
+ */
+static inline uint8_t knot_tolower(uint8_t c) {
+	const uint8_t *tolower_table = (uint8_t *)
+	"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F"
+	"\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F"
+	"\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2A\x2B\x2C\x2D\x2E\x2F"
+	"\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3A\x3B\x3C\x3D\x3E\x3F"
+	"\x40\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6A\x6B\x6C\x6D\x6E\x6F"
+	"\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7A\x5B\x5C\x5D\x5E\x5F"
+	"\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6A\x6B\x6C\x6D\x6E\x6F"
+	"\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7A\x7B\x7C\x7D\x7E\x7F"
+	"\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8A\x8B\x8C\x8D\x8E\x8F"
+	"\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9A\x9B\x9C\x9D\x9E\x9F"
+	"\xA0\xA1\xA2\xA3\xA4\xA5\xA6\xA7\xA8\xA9\xAA\xAB\xAC\xAD\xAE\xAF"
+	"\xB0\xB1\xB2\xB3\xB4\xB5\xB6\xB7\xB8\xB9\xBA\xBB\xBC\xBD\xBE\xBF"
+	"\xC0\xC1\xC2\xC3\xC4\xC5\xC6\xC7\xC8\xC9\xCA\xCB\xCC\xCD\xCE\xCF"
+	"\xD0\xD1\xD2\xD3\xD4\xD5\xD6\xD7\xD8\xD9\xDA\xDB\xDC\xDD\xDE\xDF"
+	"\xE0\xE1\xE2\xE3\xE4\xE5\xE6\xE7\xE8\xE9\xEA\xEB\xEC\xED\xEE\xEF"
+	"\xF0\xF1\xF2\xF3\xF4\xF5\xF6\xF7\xF8\xF9\xFA\xFB\xFC\xFD\xFE\xFF";
+
+	return tolower_table[c];
+}
diff --git a/src/contrib/trim.h b/src/contrib/trim.h
new file mode 100644
index 0000000..2b89249
--- /dev/null
+++ b/src/contrib/trim.h
@@ -0,0 +1,36 @@
+/*  Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/*!
+ * \brief Heap memory trimmer.
+ */
+
+#pragma once
+
+#ifdef HAVE_MALLOC_TRIM
+#include <malloc.h>
+#endif
+
+/*!
+ * \brief Trim excess heap memory.
+ */
+static inline void mem_trim(void)
+{
+#ifdef HAVE_MALLOC_TRIM
+	malloc_trim(0);
+#endif
+	return;
+}
diff --git a/src/contrib/ucw/LICENSE b/src/contrib/ucw/LICENSE
new file mode 100644
index 0000000..b463d57
--- /dev/null
+++ b/src/contrib/ucw/LICENSE
@@ -0,0 +1 @@
+../licenses/LGPL-2.0
\ No newline at end of file
diff --git a/src/contrib/ucw/array-sort.h b/src/contrib/ucw/array-sort.h
new file mode 100644
index 0000000..1ff1377
--- /dev/null
+++ b/src/contrib/ucw/array-sort.h
@@ -0,0 +1,195 @@
+/*
+ *	UCW Library -- Universal Simple Array Sorter
+ *
+ *	(c) 2003--2008 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#pragma once
+
+#include "contrib/macros.h"
+
+/*
+ *  This is not a normal header file, it's a generator of sorting
+ *  routines.  Each time you include it with parameters set in the
+ *  corresponding preprocessor macros, it generates an array sorter
+ *  with the parameters given.
+ *
+ *  You might wonder why the heck do we implement our own array sorter
+ *  instead of using qsort(). The primary reason is that qsort handles
+ *  only continuous arrays, but we need to sort array-like data structures
+ *  where the only way to access elements is by using an indexing macro.
+ *  Besides that, we are more than 2 times faster.
+ *
+ *  So much for advocacy, there are the parameters (those marked with [*]
+ *  are mandatory):
+ *
+ *  ASORT_PREFIX(x) [*]	add a name prefix (used on all global names
+ *			defined by the sorter)
+ *  ASORT_KEY_TYPE  [*]	data type of a single array entry key
+ *  ASORT_ELT(i)	returns the key of i-th element; if this macro is not
+ *			defined, the function gets a pointer to an array to be sorted
+ *  ASORT_LT(x,y)	x < y for ASORT_KEY_TYPE (default: "x<y")
+ *  ASORT_SWAP(i,j)	swap i-th and j-th element (default: assume _ELT
+ *			is an l-value and swap just the keys)
+ *  ASORT_THRESHOLD	threshold for switching between quicksort and insertsort
+ *  ASORT_EXTRA_ARGS	extra arguments for the sort function (they are always
+ *			visible in all the macros supplied above), starts with comma
+ *
+ *  After including this file, a function ASORT_PREFIX(sort)(unsigned array_size)
+ *  or ASORT_PREFIX(sort)(ASORT_KEY_TYPE *array, unsigned array_size) [if ASORT_ELT
+ *  is not defined] is declared and all parameter macros are automatically
+ *  undef'd.
+ */
+
+#ifndef ASORT_LT
+#define ASORT_LT(x,y) ((x) < (y))
+#endif
+
+#ifndef ASORT_SWAP
+#define ASORT_SWAP(i,j) do { ASORT_KEY_TYPE tmp = ASORT_ELT(i); ASORT_ELT(i)=ASORT_ELT(j); ASORT_ELT(j)=tmp; } while (0)
+#endif
+
+#ifndef ASORT_THRESHOLD
+#define ASORT_THRESHOLD 8		/* Guesswork and experimentation */
+#endif
+
+#ifndef ASORT_EXTRA_ARGS
+#define ASORT_EXTRA_ARGS
+#endif
+
+#ifndef ASORT_ELT
+#define ASORT_ARRAY_ARG ASORT_KEY_TYPE *array,
+#define ASORT_ELT(i) array[i]
+#else
+#define ASORT_ARRAY_ARG
+#endif
+
+/**
+ * The generated sorting function. If `ASORT_ELT` macro is not provided, the
+ * @ASORT_ARRAY_ARG is equal to `ASORT_KEY_TYPE *array` and is the array to be
+ * sorted. If the macro is provided, this parameter is omitted. In that case,
+ * you can sort global variables or pass your structure by @ASORT_EXTRA_ARGS.
+ **/
+static void ASORT_PREFIX(sort)(ASORT_ARRAY_ARG unsigned array_size ASORT_EXTRA_ARGS)
+{
+  struct stk { int l, r; } stack[8*sizeof(unsigned)];
+  int l, r, left, right, m;
+  unsigned sp = 0;
+  ASORT_KEY_TYPE pivot;
+
+  if (array_size <= 1)
+    return;
+
+  /* QuickSort with optimizations a'la Sedgewick, but stop at ASORT_THRESHOLD */
+
+  left = 0;
+  right = array_size - 1;
+  for(;;)
+    {
+      l = left;
+      r = right;
+      m = (l+r)/2;
+      if (ASORT_LT(ASORT_ELT(m), ASORT_ELT(l)))
+	ASORT_SWAP(l,m);
+      if (ASORT_LT(ASORT_ELT(r), ASORT_ELT(m)))
+	{
+	  ASORT_SWAP(m,r);
+	  if (ASORT_LT(ASORT_ELT(m), ASORT_ELT(l)))
+	    ASORT_SWAP(l,m);
+	}
+      pivot = ASORT_ELT(m);
+      do
+	{
+	  while (ASORT_LT(ASORT_ELT(l), pivot))
+	    l++;
+	  while (ASORT_LT(pivot, ASORT_ELT(r)))
+	    r--;
+	  if (l < r)
+	    {
+	      ASORT_SWAP(l,r);
+	      l++;
+	      r--;
+	    }
+	  else if (l == r)
+	    {
+	      l++;
+	      r--;
+	    }
+	}
+      while (l <= r);
+      if ((r - left) >= ASORT_THRESHOLD && (right - l) >= ASORT_THRESHOLD)
+	{
+	  /* Both partitions ok => push the larger one */
+	  if ((r - left) > (right - l))
+	    {
+	      stack[sp].l = left;
+	      stack[sp].r = r;
+	      left = l;
+	    }
+	  else
+	    {
+	      stack[sp].l = l;
+	      stack[sp].r = right;
+	      right = r;
+	    }
+	  sp++;
+	}
+      else if ((r - left) >= ASORT_THRESHOLD)
+	{
+	  /* Left partition OK, right undersize */
+	  right = r;
+	}
+      else if ((right - l) >= ASORT_THRESHOLD)
+	{
+	  /* Right partition OK, left undersize */
+	  left = l;
+	}
+      else
+	{
+	  /* Both partitions undersize => pop */
+	  if (!sp)
+	    break;
+	  sp--;
+	  left = stack[sp].l;
+	  right = stack[sp].r;
+	}
+    }
+
+  /*
+   * We have a partially sorted array, finish by insertsort. Inspired
+   * by qsort() in GNU libc.
+   */
+
+  /* Find minimal element which will serve as a barrier */
+  r = MIN(array_size, ASORT_THRESHOLD);
+  m = 0;
+  for (l=1; l<r; l++)
+    if (ASORT_LT(ASORT_ELT(l),ASORT_ELT(m)))
+      m = l;
+  ASORT_SWAP(0,m);
+
+  /* Insertion sort */
+  for (m=1; m<(int)array_size; m++)
+    {
+      l=m;
+      while (ASORT_LT(ASORT_ELT(m),ASORT_ELT(l-1)))
+	l--;
+      while (l < m)
+	{
+	  ASORT_SWAP(l,m);
+	  l++;
+	}
+    }
+}
+
+#undef ASORT_PREFIX
+#undef ASORT_KEY_TYPE
+#undef ASORT_ELT
+#undef ASORT_LT
+#undef ASORT_SWAP
+#undef ASORT_THRESHOLD
+#undef ASORT_EXTRA_ARGS
+#undef ASORT_ARRAY_ARG
diff --git a/src/contrib/ucw/binsearch.h b/src/contrib/ucw/binsearch.h
new file mode 100644
index 0000000..b791d39
--- /dev/null
+++ b/src/contrib/ucw/binsearch.h
@@ -0,0 +1,50 @@
+/*
+ *	UCW Library -- Generic Binary Search
+ *
+ *	(c) 2005 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#pragma once
+
+/***
+ * [[defs]]
+ * Definitions
+ * -----------
+ ***/
+
+/**
+ * Find the first element not lower than \p x in the sorted array \p ary of \p N elements (non-decreasing order).
+ * Returns the index of the found element or \p N if no exists. Uses `ary_lt_x(ary,i,x)` to compare the i'th element with \p x.
+ * The time complexity is `O(log(N))`.
+ **/
+#define BIN_SEARCH_FIRST_GE_CMP(ary, N, ary_lt_x, x, ...)  ({	\
+  unsigned l = 0, r = (N);						\
+  while (l < r)							\
+    {								\
+      unsigned m = (l+r)/2;						\
+      if (ary_lt_x(ary, m, x, __VA_ARGS__))			\
+        l = m+1;						\
+      else							\
+        r = m;							\
+    }								\
+  l;								\
+})
+
+/**
+ * The default comparison macro for \ref BIN_SEARCH_FIRST_GE_CMP().
+ **/
+#define ARY_LT_NUM(ary,i,x) (ary)[i] < (x)
+
+/**
+ * Same as \ref BIN_SEARCH_FIRST_GE_CMP(), but uses the default `<` operator for comparisons.
+ **/
+#define BIN_SEARCH_FIRST_GE(ary,N,x) BIN_SEARCH_FIRST_GE_CMP(ary,N,ARY_LT_NUM,x)
+
+/**
+ * Search the sorted array \p ary of \p N elements (non-decreasing) for the first occurrence of \p x.
+ * Returns the index or -1 if no such element exists. Uses the `<` operator for comparisons.
+ **/
+#define BIN_SEARCH_EQ(ary,N,x) ({ int i = BIN_SEARCH_FIRST_GE(ary,N,x); if (i >= (N) || (ary)[i] != (x)) i=-1; i; })
diff --git a/src/contrib/ucw/heap.c b/src/contrib/ucw/heap.c
new file mode 100644
index 0000000..d7ed18e
--- /dev/null
+++ b/src/contrib/ucw/heap.c
@@ -0,0 +1,166 @@
+/*
+ *	Binary heap
+ *
+ *	(c) 2012 Ondrej Filip <feela@network.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+/***
+ * Introduction
+ * ------------
+ *
+ * Binary heap is a simple data structure, which for example supports efficient insertions, deletions
+ * and access to the minimal inserted item. We define several macros for such operations.
+ * Note that because of simplicity of heaps, we have decided to define direct macros instead
+ * of a <<generic:,macro generator>> as for several other data structures in the Libucw.
+ *
+ * A heap is represented by a number of elements and by an array of values. Beware that we
+ * index this array from one, not from zero as do the standard C arrays.
+ *
+ * Most macros use these parameters:
+ *
+ * - @num - a variable (signed or unsigned integer) with the number of elements
+ * - @heap - a C array of type @type; the heap is stored in `heap[1] .. heap[num]`; `heap[0]` is unused
+ *
+ * A valid heap must follow these rules:
+ *
+ * - `num >= 0`
+ * - `heap[i] >= heap[i / 2]` for each `i` in `[2, num]`
+ *
+ * The first element `heap[1]` is always lower or equal to all other elements.
+ ***/
+
+#include <string.h>
+#include <stdlib.h>
+#include "contrib/ucw/heap.h"
+
+static inline void heap_swap(heap_val_t **e1, heap_val_t **e2)
+{
+	if (e1 == e2) return; /* Stack tmp should be faster than tmpelem. */
+	heap_val_t *tmp = *e1; /* Even faster than 2-XOR nowadays. */
+	*e1 = *e2;
+	*e2 = tmp;
+	int pos = (*e1)->pos;
+	(*e1)->pos = (*e2)->pos;
+	(*e2)->pos = pos;
+}
+
+int heap_init(struct heap *h, int (*cmp)(void *, void *), int init_size)
+{
+	int isize = init_size ? init_size : INITIAL_HEAP_SIZE;
+
+	h->num = 0;
+	h->max_size = isize;
+	h->cmp = cmp;
+	h->data = malloc((isize + 1) * sizeof(heap_val_t*)); /* Temp element unused. */
+
+	return h->data ? 1 : 0;
+}
+
+void heap_deinit(struct heap *h)
+{
+	free(h->data);
+	memset(h, 0, sizeof(*h));
+}
+
+static inline void _heap_bubble_down(struct heap *h, int e)
+{
+	int e1;
+	for (;;)
+	{
+		e1 = 2*e;
+		if(e1 > h->num) break;
+		if((h->cmp(*HELEMENT(h, e),*HELEMENT(h,e1)) < 0) && (e1 == h->num || (h->cmp(*HELEMENT(h, e),*HELEMENT(h,e1+1)) < 0))) break;
+		if((e1 != h->num) && (h->cmp(*HELEMENT(h, e1+1), *HELEMENT(h,e1)) < 0)) e1++;
+		heap_swap(HELEMENT(h,e),HELEMENT(h,e1));
+		e = e1;
+	}
+}
+
+static inline void _heap_bubble_up(struct heap *h, int e)
+{
+	int e1;
+	while (e > 1)
+	{
+		e1 = e/2;
+		if(h->cmp(*HELEMENT(h, e1),*HELEMENT(h,e)) < 0) break;
+		heap_swap(HELEMENT(h,e),HELEMENT(h,e1));
+		e = e1;
+	}
+
+}
+
+static void heap_increase(struct heap *h, int pos, heap_val_t *e)
+{
+	*HELEMENT(h, pos) = e;
+	e->pos = pos;
+	_heap_bubble_down(h, pos);
+}
+
+static void heap_decrease(struct heap *h, int pos, heap_val_t *e)
+{
+	*HELEMENT(h, pos) = e;
+	e->pos = pos;
+	_heap_bubble_up(h, pos);
+}
+
+void heap_replace(struct heap *h, int pos, heap_val_t *e)
+{
+	if (h->cmp(*HELEMENT(h, pos),e) < 0) {
+		heap_increase(h, pos, e);
+	} else {
+		heap_decrease(h, pos, e);
+	}
+}
+
+void heap_delmin(struct heap *h)
+{
+	if(h->num == 0) return;
+	if(h->num > 1)
+	{
+		heap_swap(HHEAD(h),HELEMENT(h,h->num));
+	}
+	(*HELEMENT(h, h->num))->pos = 0;
+	--h->num;
+	_heap_bubble_down(h, 1);
+}
+
+int heap_insert(struct heap *h, heap_val_t *e)
+{
+	if(h->num == h->max_size)
+	{
+		h->max_size = h->max_size * HEAP_INCREASE_STEP;
+		h->data = realloc(h->data, (h->max_size + 1) * sizeof(heap_val_t*));
+		if (!h->data) {
+			return 0;
+		}
+	}
+
+	h->num++;
+	*HELEMENT(h,h->num) = e;
+	e->pos = h->num;
+	_heap_bubble_up(h,h->num);
+	return 1;
+}
+
+int heap_find(struct heap *h, heap_val_t *elm)
+{
+	return ((struct heap_val *) elm)->pos;
+}
+
+void heap_delete(struct heap *h, int e)
+{
+	heap_swap(HELEMENT(h, e), HELEMENT(h, h->num));
+	(*HELEMENT(h, h->num))->pos = 0;
+	h->num--;
+	if(h->cmp(*HELEMENT(h, e), *HELEMENT(h, h->num + 1)) < 0) _heap_bubble_up(h, e);
+	else _heap_bubble_down(h, e);
+
+	if ((h->num > INITIAL_HEAP_SIZE) && (h->num < h->max_size / HEAP_DECREASE_THRESHOLD))
+	{
+		h->max_size = h->max_size / HEAP_INCREASE_STEP;
+		h->data = realloc(h->data, (h->max_size + 1) * sizeof(heap_val_t*));
+	}
+}
diff --git a/src/contrib/ucw/heap.h b/src/contrib/ucw/heap.h
new file mode 100644
index 0000000..58958b3
--- /dev/null
+++ b/src/contrib/ucw/heap.h
@@ -0,0 +1,46 @@
+/*  Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+  
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+  
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+struct heap_val {
+	int pos;
+};
+
+typedef struct heap_val heap_val_t;
+
+struct heap {
+   int num;		/* Number of elements */
+   int max_size;	/* Size of allocated memory */
+   int (*cmp)(void *, void *);
+   heap_val_t **data;
+};		/* Array follows */
+
+#define INITIAL_HEAP_SIZE	512 /* initial heap size */
+#define HEAP_INCREASE_STEP	2 /* multiplier for each inflation, keep conservative */
+#define HEAP_DECREASE_THRESHOLD	2 /* threshold for deflation, keep conservative */
+#define HELEMENT(h,num) 	((h)->data + (num))
+#define HHEAD(h) 		HELEMENT((h), 1)
+#define EMPTY_HEAP(h) 		((h)->num == 0) /* h->num == 0 */
+
+int heap_init(struct heap *, int (*cmp)(void *, void *), int);
+void heap_deinit(struct heap *);
+
+void heap_delmin(struct heap *);
+int heap_insert(struct heap *, heap_val_t *);
+int heap_find(struct heap *, heap_val_t *);
+void heap_delete(struct heap *, int);
+void heap_replace(struct heap *h, int pos, heap_val_t *);
diff --git a/src/contrib/ucw/lists.c b/src/contrib/ucw/lists.c
new file mode 100644
index 0000000..84c6eaa
--- /dev/null
+++ b/src/contrib/ucw/lists.c
@@ -0,0 +1,244 @@
+/*
+ *	BIRD Library -- Linked Lists
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *	(c) 2015, 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+/**
+ * DOC: Linked lists
+ *
+ * The BIRD library provides a set of functions for operating on linked
+ * lists. The lists are internally represented as standard doubly linked
+ * lists with synthetic head and tail which makes all the basic operations
+ * run in constant time and contain no extra end-of-list checks. Each list
+ * is described by a &list structure, nodes can have any format as long
+ * as they start with a &node structure. If you want your nodes to belong
+ * to multiple lists at once, you can embed multiple &node structures in them
+ * and use the SKIP_BACK() macro to calculate a pointer to the start of the
+ * structure from a &node pointer, but beware of obscurity.
+ *
+ * There also exist safe linked lists (&slist, &snode and all functions
+ * being prefixed with |s_|) which support asynchronous walking very
+ * similar to that used in the &fib structure.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include "contrib/ucw/lists.h"
+#include "contrib/mempattern.h"
+
+/**
+ * add_tail - append a node to a list
+ * \p l: linked list
+ * \p n: list node
+ *
+ * add_tail() takes a node \p n and appends it at the end of the list \p l.
+ */
+void
+add_tail(list_t *l, node_t *n)
+{
+  node_t *z = l->tail;
+
+  n->next = (node_t *) &l->null;
+  n->prev = z;
+  z->next = n;
+  l->tail = n;
+}
+
+/**
+ * add_head - prepend a node to a list
+ * \p l: linked list
+ * \p n: list node
+ *
+ * add_head() takes a node \p n and prepends it at the start of the list \p l.
+ */
+void
+add_head(list_t *l, node_t *n)
+{
+  node_t *z = l->head;
+
+  n->next = z;
+  n->prev = (node_t *) &l->head;
+  z->prev = n;
+  l->head = n;
+}
+
+/**
+ * insert_node - insert a node to a list
+ * \p n: a new list node
+ * \p after: a node of a list
+ *
+ * Inserts a node \p n to a linked list after an already inserted
+ * node \p after.
+ */
+void
+insert_node(node_t *n, node_t *after)
+{
+  node_t *z = after->next;
+
+  n->next = z;
+  n->prev = after;
+  after->next = n;
+  z->prev = n;
+}
+
+/**
+ * rem_node - remove a node from a list
+ * \p n: node to be removed
+ *
+ * Removes a node \p n from the list it's linked in.
+ */
+void
+rem_node(node_t *n)
+{
+  node_t *z = n->prev;
+  node_t *x = n->next;
+
+  z->next = x;
+  x->prev = z;
+  n->prev = 0;
+  n->next = 0;
+}
+
+/**
+ * init_list - create an empty list
+ * \p l: list
+ *
+ * init_list() takes a &list structure and initializes its
+ * fields, so that it represents an empty list.
+ */
+void
+init_list(list_t *l)
+{
+  l->head = (node_t *) &l->null;
+  l->null = NULL;
+  l->tail = (node_t *) &l->head;
+}
+
+/**
+ * add_tail_list - concatenate two lists
+ * \p to: destination list
+ * \p l: source list
+ *
+ * This function appends all elements of the list \p l to
+ * the list \p to in constant time.
+ */
+void
+add_tail_list(list_t *to, list_t *l)
+{
+  node_t *p = to->tail;
+  node_t *q = l->head;
+
+  p->next = q;
+  q->prev = p;
+  q = l->tail;
+  q->next = (node_t *) &to->null;
+  to->tail = q;
+}
+
+/**
+ * list_dup - duplicate list
+ * \p to: destination list
+ * \p l: source list
+ *
+ * This function duplicates all elements of the list \p l to
+ * the list \p to in linear time.
+ *
+ * This function only works with a homogenous item size.
+ */
+void list_dup(list_t *dst, list_t *src, size_t itemsz)
+{
+	node_t *n;
+	WALK_LIST(n, *src) {
+		node_t *i = malloc(itemsz);
+		memcpy(i, n, itemsz);
+		add_tail(dst, i);
+	}
+}
+
+/**
+ * list_size - gets number of nodes
+ * \p l: list
+ *
+ * This function counts nodes in list \p l and returns this number.
+ */
+size_t list_size(const list_t *l)
+{
+	size_t count = 0;
+
+	node_t *n;
+	WALK_LIST(n, *l) {
+		count++;
+	}
+
+	return count;
+}
+
+/**
+ * ptrlist_add - add pointer to pointer list
+ * \p to: destination list
+ * \p val: added pointer
+ * \p mm: memory context
+ */
+ptrnode_t *ptrlist_add(list_t *to, void *val, knot_mm_t *mm)
+{
+	ptrnode_t *node = mm_alloc(mm , sizeof(ptrnode_t));
+	if (node == NULL) {
+		return NULL;
+	} else {
+		node->d = val;
+	}
+	add_tail(to, &node->n);
+	return node;
+}
+
+/**
+ * ptrlist_free - free all nodes in pointer list
+ * \p list: list nodes
+ * \p mm: memory context
+ */
+void ptrlist_free(list_t *list, knot_mm_t *mm)
+{
+	node_t *n, *nxt;
+	WALK_LIST_DELSAFE(n, nxt, *list) {
+		mm_free(mm, n);
+	}
+	init_list(list);
+}
+
+/**
+ * ptrlist_rem - remove pointer node
+ * \p val: pointer to remove
+ * \p mm: memory context
+ */
+void ptrlist_rem(ptrnode_t *node, knot_mm_t *mm)
+{
+	rem_node(&node->n);
+	mm_free(mm, node);
+}
+
+/**
+ * ptrlist_deep_free - free all nodes incl referenced data
+ * \p list: list nodes
+ * \p mm: memory context
+ */
+void ptrlist_deep_free(list_t *l, knot_mm_t *mm)
+{
+	ptrnode_t *n;
+	WALK_LIST(n, *l) {
+		mm_free(mm, n->d);
+	}
+	ptrlist_free(l, mm);
+}
+
+void ptrlist_free_custom(list_t *l, knot_mm_t *mm, ptrlist_free_cb free_cb)
+{
+	ptrnode_t *n;
+	WALK_LIST(n, *l) {
+		free_cb(n->d);
+	}
+	ptrlist_free(l, mm);
+}
diff --git a/src/contrib/ucw/lists.h b/src/contrib/ucw/lists.h
new file mode 100644
index 0000000..305806a
--- /dev/null
+++ b/src/contrib/ucw/lists.h
@@ -0,0 +1,86 @@
+/*
+ *	BIRD Library -- Linked Lists
+ *
+ *	(c) 1998 Martin Mares <mj@ucw.cz>
+ *	(c) 2015, 2020 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *
+ *	Can be freely distributed and used under the terms of the GNU GPL.
+ */
+
+#pragma once
+
+/*
+ * I admit the list structure is very tricky and also somewhat awkward,
+ * but it's both efficient and easy to manipulate once one understands the
+ * basic trick: The list head always contains two synthetic nodes which are
+ * always present in the list: the head and the tail. But as the `next'
+ * entry of the tail and the `prev' entry of the head are both NULL, the
+ * nodes can overlap each other:
+ *
+ *     head    head_node.next
+ *     null    head_node.prev  tail_node.next
+ *     tail                    tail_node.prev
+ */
+
+#include <string.h>
+#include "libknot/mm_ctx.h"
+
+typedef struct node {
+  struct node *next, *prev;
+} node_t;
+
+typedef struct list {			/* In fact two overlayed nodes */
+  struct node *head, *null, *tail;
+} list_t;
+
+#define NODE (node_t *)
+#define HEAD(list) ((void *)((list).head))
+#define TAIL(list) ((void *)((list).tail))
+#define WALK_LIST(n,list) for(n=HEAD(list);(NODE (n))->next; \
+				n=(void *)((NODE (n))->next))
+#define WALK_LIST_DELSAFE(n,nxt,list) \
+     for(n=HEAD(list); (nxt=(void *)((NODE (n))->next)); n=(void *) nxt)
+/* WALK_LIST_FIRST supposes that called code removes each processed node */
+#define WALK_LIST_FIRST(n,list) \
+     while(n=HEAD(list), (NODE (n))->next)
+#define WALK_LIST_BACKWARDS(n,list) for(n=TAIL(list);(NODE (n))->prev; \
+				n=(void *)((NODE (n))->prev))
+#define WALK_LIST_BACKWARDS_DELSAFE(n,prv,list) \
+     for(n=TAIL(list); prv=(void *)((NODE (n))->prev); n=(void *) prv)
+
+#define EMPTY_LIST(list) (!(list).head->next)
+
+/*! \brief Free every node in the list. */
+#define WALK_LIST_FREE(list) \
+	do { \
+	node_t *n=0,*nxt=0;  \
+	WALK_LIST_DELSAFE(n,nxt,list) { \
+	    free(n); \
+	} \
+	init_list(&list); \
+	} while(0)
+
+void add_tail(list_t *, node_t *);
+void add_head(list_t *, node_t *);
+void rem_node(node_t *);
+void add_tail_list(list_t *, list_t *);
+void init_list(list_t *);
+void insert_node(node_t *, node_t *);
+void list_dup(list_t *dst, list_t *src, size_t itemsz);
+size_t list_size(const list_t *);
+
+/*!
+ * \brief Generic pointer list implementation.
+ */
+typedef struct ptrnode {
+	node_t n;
+	void *d;
+} ptrnode_t;
+
+ptrnode_t *ptrlist_add(list_t *, void *, knot_mm_t *);
+void ptrlist_free(list_t *, knot_mm_t *);
+void ptrlist_rem(ptrnode_t *node, knot_mm_t *mm);
+void ptrlist_deep_free(list_t *, knot_mm_t *);
+
+typedef void (*ptrlist_free_cb)(void *);
+void ptrlist_free_custom(list_t *l, knot_mm_t *mm, ptrlist_free_cb free_cb);
diff --git a/src/contrib/ucw/mempool.c b/src/contrib/ucw/mempool.c
new file mode 100644
index 0000000..8e835c1
--- /dev/null
+++ b/src/contrib/ucw/mempool.c
@@ -0,0 +1,323 @@
+/*
+ *	UCW Library -- Memory Pools (One-Time Allocation)
+ *
+ *	(c) 1997--2001 Martin Mares <mj@ucw.cz>
+ *	(c) 2007 Pavel Charvat <pchar@ucw.cz>
+ *	(c) 2015, 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#undef LOCAL_DEBUG
+
+#include <string.h>
+#include <strings.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <assert.h>
+#include "contrib/asan.h"
+#include "contrib/macros.h"
+#include "contrib/ucw/mempool.h"
+
+/** \todo This shouldn't be precalculated, but computed on load. */
+#define CPU_PAGE_SIZE 4096
+
+/** Align an integer \p s to the nearest higher multiple of \p a (which should be a power of two) **/
+#define ALIGN_TO(s, a) (((s)+a-1)&~(a-1))
+#define MP_CHUNK_TAIL ALIGN_TO(sizeof(struct mempool_chunk), CPU_STRUCT_ALIGN)
+#define MP_SIZE_MAX (~0U - MP_CHUNK_TAIL - CPU_PAGE_SIZE)
+#define DBG(s, ...)
+
+/** \note Imported MMAP backend from bigalloc.c */
+#define CONFIG_UCW_POOL_IS_MMAP
+#ifdef CONFIG_UCW_POOL_IS_MMAP
+#include <sys/mman.h>
+static void *
+page_alloc(uint64_t len)
+{
+	if (!len) {
+		return NULL;
+	}
+	if (len > SIZE_MAX) {
+		return NULL;
+	}
+	assert(!(len & (CPU_PAGE_SIZE-1)));
+	uint8_t *p = mmap(NULL, len, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0);
+	if (p == (uint8_t*) MAP_FAILED) {
+		return NULL;
+	}
+	return p;
+}
+
+static void
+page_free(void *start, uint64_t len)
+{
+	assert(!(len & (CPU_PAGE_SIZE-1)));
+	assert(!((uintptr_t) start & (CPU_PAGE_SIZE-1)));
+	munmap(start, len);
+}
+#endif
+
+struct mempool_chunk {
+	struct mempool_chunk *next;
+	unsigned size;
+};
+
+static unsigned
+mp_align_size(unsigned size)
+{
+#ifdef CONFIG_UCW_POOL_IS_MMAP
+	return ALIGN_TO(size + MP_CHUNK_TAIL, CPU_PAGE_SIZE) - MP_CHUNK_TAIL;
+#else
+	return ALIGN_TO(size, CPU_STRUCT_ALIGN);
+#endif
+}
+
+void
+mp_init(struct mempool *pool, unsigned chunk_size)
+{
+	chunk_size = mp_align_size(MAX(sizeof(struct mempool), chunk_size));
+	*pool = (struct mempool) {
+		.chunk_size = chunk_size,
+		.threshold = chunk_size >> 1,
+		.last_big = &pool->last_big
+	};
+}
+
+static void *
+mp_new_big_chunk(unsigned size)
+{
+	uint8_t *data = malloc(size + MP_CHUNK_TAIL);
+	if (!data) {
+		return NULL;
+	}
+	ASAN_POISON_MEMORY_REGION(data, size);
+	struct mempool_chunk *chunk = (struct mempool_chunk *)(data + size);
+	chunk->size = size;
+	return chunk;
+}
+
+static void
+mp_free_big_chunk(struct mempool_chunk *chunk)
+{
+	void *ptr = (uint8_t *)chunk - chunk->size;
+	ASAN_UNPOISON_MEMORY_REGION(ptr, chunk->size);
+	free(ptr);
+}
+
+static void *
+mp_new_chunk(unsigned size)
+{
+#ifdef CONFIG_UCW_POOL_IS_MMAP
+	uint8_t *data = page_alloc(size + MP_CHUNK_TAIL);
+	if (!data) {
+		return NULL;
+	}
+	ASAN_POISON_MEMORY_REGION(data, size);
+	struct mempool_chunk *chunk = (struct mempool_chunk *)(data + size);
+	chunk->size = size;
+	return chunk;
+#else
+	return mp_new_big_chunk(size);
+#endif
+}
+
+static void
+mp_free_chunk(struct mempool_chunk *chunk)
+{
+#ifdef CONFIG_UCW_POOL_IS_MMAP
+	uint8_t *data = (uint8_t *)chunk - chunk->size;
+	ASAN_UNPOISON_MEMORY_REGION(data, chunk->size);
+	page_free(data, chunk->size + MP_CHUNK_TAIL);
+#else
+	mp_free_big_chunk(chunk);
+#endif
+}
+
+struct mempool *
+mp_new(unsigned chunk_size)
+{
+	chunk_size = mp_align_size(MAX(sizeof(struct mempool), chunk_size));
+	struct mempool_chunk *chunk = mp_new_chunk(chunk_size);
+	struct mempool *pool = (void *)chunk - chunk_size;
+	ASAN_UNPOISON_MEMORY_REGION(pool, sizeof(*pool));
+	DBG("Creating mempool %p with %u bytes long chunks", pool, chunk_size);
+	chunk->next = NULL;
+	ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+	*pool = (struct mempool) {
+		.state = { .free = { chunk_size - sizeof(*pool) }, .last = { chunk } },
+		.chunk_size = chunk_size,
+		.threshold = chunk_size >> 1,
+		.last_big = &pool->last_big
+	};
+	return pool;
+}
+
+static void
+mp_free_chain(struct mempool_chunk *chunk)
+{
+	while (chunk) {
+		ASAN_UNPOISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		struct mempool_chunk *next = chunk->next;
+		mp_free_chunk(chunk);
+		chunk = next;
+	}
+}
+
+static void
+mp_free_big_chain(struct mempool_chunk *chunk)
+{
+	while (chunk) {
+		ASAN_UNPOISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		struct mempool_chunk *next = chunk->next;
+		mp_free_big_chunk(chunk);
+		chunk = next;
+	}
+}
+
+void
+mp_delete(struct mempool *pool)
+{
+	if (pool == NULL) {
+		return;
+	}
+	DBG("Deleting mempool %p", pool);
+	mp_free_big_chain(pool->state.last[1]);
+	mp_free_chain(pool->unused);
+	mp_free_chain(pool->state.last[0]); // can contain the mempool structure
+}
+
+void
+mp_flush(struct mempool *pool)
+{
+	mp_free_big_chain(pool->state.last[1]);
+	struct mempool_chunk *chunk = pool->state.last[0], *next;
+	while (chunk) {
+		ASAN_UNPOISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		if ((uint8_t *)chunk - chunk->size == (uint8_t *)pool) {
+			break;
+		}
+		next = chunk->next;
+		chunk->next = pool->unused;
+		ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		pool->unused = chunk;
+		chunk = next;
+	}
+	pool->state.last[0] = chunk;
+	if (chunk) {
+		pool->state.free[0] = chunk->size - sizeof(*pool);
+		ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+	} else {
+		pool->state.free[0] = 0;
+	}
+	pool->state.last[1] = NULL;
+	pool->state.free[1] = 0;
+	pool->last_big = &pool->last_big;
+}
+
+static void
+mp_stats_chain(struct mempool_chunk *chunk, struct mempool_stats *stats, unsigned idx)
+{
+	struct mempool_chunk *next;
+	while (chunk) {
+		ASAN_UNPOISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		stats->chain_size[idx] += chunk->size + sizeof(*chunk);
+		stats->chain_count[idx]++;
+		next = chunk->next;
+		ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		chunk = next;
+	}
+	stats->total_size += stats->chain_size[idx];
+}
+
+void
+mp_stats(struct mempool *pool, struct mempool_stats *stats)
+{
+	bzero(stats, sizeof(*stats));
+	mp_stats_chain(pool->state.last[0], stats, 0);
+	mp_stats_chain(pool->state.last[1], stats, 1);
+	mp_stats_chain(pool->unused, stats, 2);
+}
+
+uint64_t
+mp_total_size(struct mempool *pool)
+{
+	struct mempool_stats stats;
+	mp_stats(pool, &stats);
+	return stats.total_size;
+}
+
+static void *
+mp_alloc_internal(struct mempool *pool, unsigned size)
+{
+	struct mempool_chunk *chunk;
+	if (size <= pool->threshold) {
+		pool->idx = 0;
+		if (pool->unused) {
+			chunk = pool->unused;
+			ASAN_UNPOISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+			pool->unused = chunk->next;
+		} else {
+			chunk = mp_new_chunk(pool->chunk_size);
+		}
+		chunk->next = pool->state.last[0];
+		ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		pool->state.last[0] = chunk;
+		pool->state.free[0] = pool->chunk_size - size;
+		return (uint8_t *)chunk - pool->chunk_size;
+	} else if (size <= MP_SIZE_MAX) {
+		pool->idx = 1;
+		unsigned aligned = ALIGN_TO(size, CPU_STRUCT_ALIGN);
+		chunk = mp_new_big_chunk(aligned);
+		if (!chunk) {
+			return NULL;
+		}
+		chunk->next = pool->state.last[1];
+		ASAN_POISON_MEMORY_REGION(chunk, sizeof(struct mempool_chunk));
+		pool->state.last[1] = chunk;
+		pool->state.free[1] = aligned - size;
+		return pool->last_big = (uint8_t *)chunk - aligned;
+	} else {
+		fprintf(stderr, "Cannot allocate %u bytes from a mempool", size);
+		assert(0);
+		return NULL;
+	}
+}
+
+void *
+mp_alloc(struct mempool *pool, unsigned size)
+{
+	unsigned avail = pool->state.free[0] & ~(CPU_STRUCT_ALIGN - 1);
+	void *ptr = NULL;
+	if (size <= avail) {
+		pool->state.free[0] = avail - size;
+		ptr = (uint8_t*)pool->state.last[0] - avail;
+	} else {
+		ptr = mp_alloc_internal(pool, size);
+	}
+	ASAN_UNPOISON_MEMORY_REGION(ptr, size);
+	return ptr;
+}
+
+void *
+mp_alloc_noalign(struct mempool *pool, unsigned size)
+{
+	void *ptr = NULL;
+	if (size <= pool->state.free[0]) {
+		ptr = (uint8_t*)pool->state.last[0] - pool->state.free[0];
+		pool->state.free[0] -= size;
+	} else {
+		ptr = mp_alloc_internal(pool, size);
+	}
+	ASAN_UNPOISON_MEMORY_REGION(ptr, size);
+	return ptr;
+}
+
+void *
+mp_alloc_zero(struct mempool *pool, unsigned size)
+{
+	void *ptr = mp_alloc(pool, size);
+	bzero(ptr, size);
+	return ptr;
+}
diff --git a/src/contrib/ucw/mempool.h b/src/contrib/ucw/mempool.h
new file mode 100644
index 0000000..c5a4fa8
--- /dev/null
+++ b/src/contrib/ucw/mempool.h
@@ -0,0 +1,124 @@
+/*
+ *	UCW Library -- Memory Pools
+ *
+ *	(c) 1997--2005 Martin Mares <mj@ucw.cz>
+ *	(c) 2007 Pavel Charvat <pchar@ucw.cz>
+ *	(c) 2015, 2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
+ */
+
+#pragma once
+
+#include <string.h>
+#include <stdint.h>
+
+#define CPU_STRUCT_ALIGN (sizeof(void*))
+
+/***
+ * [[defs]]
+ * Definitions
+ * -----------
+ ***/
+
+/**
+ * Memory pool state (see mp_push(), ...).
+ * You should use this one as an opaque handle only, the insides are internal.
+ **/
+struct mempool_state {
+	unsigned free[2];
+	void *last[2];
+};
+
+/**
+ * Memory pool.
+ * You should use this one as an opaque handle only, the insides are internal.
+ **/
+struct mempool {
+	struct mempool_state state;
+	void *unused, *last_big;
+	unsigned chunk_size, threshold, idx;
+};
+
+struct mempool_stats {			/** Mempool statistics. See mp_stats(). **/
+	uint64_t total_size;		/** Real allocated size in bytes. */
+	unsigned chain_count[3];	/** Number of allocated chunks in small/big/unused chains. */
+	unsigned chain_size[3];		/** Size of allocated chunks in small/big/unused chains. */
+};
+
+/***
+ * [[basic]]
+ * Basic manipulation
+ * ------------------
+ ***/
+
+/**
+ * Initialize a given mempool structure.
+ * \p chunk_size must be in the interval `[1, UINT_MAX / 2]`.
+ * It will allocate memory by this large chunks and take
+ * memory to satisfy requests from them.
+ *
+ * Memory pools can be treated as <<trans:respools,resources>>, see <<trans:res_mempool()>>.
+ **/
+void mp_init(struct mempool *pool, unsigned chunk_size);
+
+/**
+ * Allocate and initialize a new memory pool.
+ * See \ref mp_init() for \p chunk_size limitations.
+ *
+ * The new mempool structure is allocated on the new mempool.
+ *
+ * Memory pools can be treated as <<trans:respools,resources>>, see <<trans:res_mempool()>>.
+ **/
+struct mempool *mp_new(unsigned chunk_size);
+
+/**
+ * Cleanup mempool initialized by mp_init or mp_new.
+ * Frees all the memory allocated by this mempool and,
+ * if created by \ref mp_new(), the \p pool itself.
+ **/
+void mp_delete(struct mempool *pool);
+
+/**
+ * Frees all data on a memory pool, but leaves it working.
+ * It can keep some of the chunks allocated to serve
+ * further allocation requests. Leaves the \p pool alive,
+ * even if it was created with \ref mp_new().
+ **/
+void mp_flush(struct mempool *pool);
+
+/**
+ * Compute some statistics for debug purposes.
+ * See the definition of the <<struct_mempool_stats,mempool_stats structure>>.
+ **/
+void mp_stats(struct mempool *pool, struct mempool_stats *stats);
+uint64_t mp_total_size(struct mempool *pool);	/** How many bytes were allocated by the pool. **/
+
+/***
+ * [[alloc]]
+ * Allocation routines
+ * -------------------
+ ***/
+
+/**
+ * The function allocates new \p size bytes on a given memory pool.
+ * If the \p size is zero, the resulting pointer is undefined,
+ * but it may be safely reallocated or used as the parameter
+ * to other functions below.
+ *
+ * The resulting pointer is always aligned to a multiple of
+ * `CPU_STRUCT_ALIGN` bytes and this condition remains true also
+ * after future reallocations.
+ **/
+void *mp_alloc(struct mempool *pool, unsigned size);
+
+/**
+ * The same as \ref mp_alloc(), but the result may be unaligned.
+ **/
+void *mp_alloc_noalign(struct mempool *pool, unsigned size);
+
+/**
+ * The same as \ref mp_alloc(), but fills the newly allocated memory with zeroes.
+ **/
+void *mp_alloc_zero(struct mempool *pool, unsigned size);
diff --git a/src/contrib/url-parser/LICENSE b/src/contrib/url-parser/LICENSE
new file mode 100644
index 0000000..0161703
--- /dev/null
+++ b/src/contrib/url-parser/LICENSE
@@ -0,0 +1 @@
+../licenses/MIT
\ No newline at end of file
diff --git a/src/contrib/url-parser/README.md b/src/contrib/url-parser/README.md
new file mode 100644
index 0000000..c3b1919
--- /dev/null
+++ b/src/contrib/url-parser/README.md
@@ -0,0 +1,14 @@
+url-parser
+==========
+
+This is Joyent's [URL parser][original-source] from their
+[http-parser][joyent-http-parser] library.
+
+## LICENSE
+
+This derivative is licensed under the same terms as NGINX and copyright Joyent,
+Inc. and other Node contributors as outlined in their [LICENSE][].
+
+[original-source]: https://github.com/joyent/http-parser/blob/e01811e7f4894d7f0f7f4bd8492cccec6f6b4038/http_parser.c#L2343
+[joyent-http-parser]: https://github.com/joyent/http-parser
+[LICENSE]: https://github.com/joyent/http-parser/blob/master/LICENSE-MIT
diff --git a/src/contrib/url-parser/url_parser.c b/src/contrib/url-parser/url_parser.c
new file mode 100644
index 0000000..56244b4
--- /dev/null
+++ b/src/contrib/url-parser/url_parser.c
@@ -0,0 +1,635 @@
+/* Based on src/http/ngx_http_parse.c from NGINX copyright Igor Sysoev
+ *
+ * Additional changes are licensed under the same terms as NGINX and
+ * copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * This is the http_parser_parse_url function extracted from joyent's
+ * http-parser library.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "url_parser.h"
+
+/* Macros for character classes; depends on strict-mode  */
+#define CR                  '\r'
+#define LF                  '\n'
+#define LOWER(c)            (unsigned char)(c | 0x20)
+#define IS_ALPHA(c)         (LOWER(c) >= 'a' && LOWER(c) <= 'z')
+#define IS_NUM(c)           ((c) >= '0' && (c) <= '9')
+#define IS_ALPHANUM(c)      (IS_ALPHA(c) || IS_NUM(c))
+#define IS_HEX(c)           (IS_NUM(c) || (LOWER(c) >= 'a' && LOWER(c) <= 'f'))
+#define IS_MARK(c)          ((c) == '-' || (c) == '_' || (c) == '.' || \
+  (c) == '!' || (c) == '~' || (c) == '*' || (c) == '\'' || (c) == '(' || \
+  (c) == ')')
+#define IS_USERINFO_CHAR(c) (IS_ALPHANUM(c) || IS_MARK(c) || (c) == '%' || \
+  (c) == ';' || (c) == ':' || (c) == '&' || (c) == '=' || (c) == '+' || \
+  (c) == '$' || (c) == ',')
+
+#define STRICT_TOKEN(c)     (tokens[(unsigned char)c])
+
+#ifndef BIT_AT
+# define BIT_AT(a, i)                                                \
+  (!!((unsigned int) (a)[(unsigned int) (i) >> 3] &                  \
+   (1 << ((unsigned int) (i) & 7))))
+#endif
+
+#if HTTP_PARSER_STRICT
+# define T(v) 0
+#else
+# define T(v) v
+#endif
+
+static const uint8_t normal_url_char[32] = {
+/*   0 nul    1 soh    2 stx    3 etx    4 eot    5 enq    6 ack    7 bel  */
+        0    |   0    |   0    |   0    |   0    |   0    |   0    |   0,
+/*   8 bs     9 ht    10 nl    11 vt    12 np    13 cr    14 so    15 si   */
+        0    | T(2)   |   0    |   0    | T(16)  |   0    |   0    |   0,
+/*  16 dle   17 dc1   18 dc2   19 dc3   20 dc4   21 nak   22 syn   23 etb */
+        0    |   0    |   0    |   0    |   0    |   0    |   0    |   0,
+/*  24 can   25 em    26 sub   27 esc   28 fs    29 gs    30 rs    31 us  */
+        0    |   0    |   0    |   0    |   0    |   0    |   0    |   0,
+/*  32 sp    33  !    34  "    35  #    36  $    37  %    38  &    39  '  */
+        0    |   2    |   4    |   0    |   16   |   32   |   64   |  128,
+/*  40  (    41  )    42  *    43  +    44  ,    45  -    46  .    47  /  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  48  0    49  1    50  2    51  3    52  4    53  5    54  6    55  7  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  56  8    57  9    58  :    59  ;    60  <    61  =    62  >    63  ?  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |   0,
+/*  64  @    65  A    66  B    67  C    68  D    69  E    70  F    71  G  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  72  H    73  I    74  J    75  K    76  L    77  M    78  N    79  O  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  80  P    81  Q    82  R    83  S    84  T    85  U    86  V    87  W  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  88  X    89  Y    90  Z    91  [    92  \    93  ]    94  ^    95  _  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/*  96  `    97  a    98  b    99  c   100  d   101  e   102  f   103  g  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 104  h   105  i   106  j   107  k   108  l   109  m   110  n   111  o  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 112  p   113  q   114  r   115  s   116  t   117  u   118  v   119  w  */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |  128,
+/* 120  x   121  y   122  z   123  {   124  |   125  }   126  ~   127 del */
+        1    |   2    |   4    |   8    |   16   |   32   |   64   |   0, };
+
+#if HTTP_PARSER_STRICT
+#define TOKEN(c)            (tokens[(unsigned char)c])
+#define IS_URL_CHAR(c)      (BIT_AT(normal_url_char, (unsigned char)c))
+#define IS_HOST_CHAR(c)     (IS_ALPHANUM(c) || (c) == '.' || (c) == '-')
+#else
+#define TOKEN(c)            ((c == ' ') ? ' ' : tokens[(unsigned char)c])
+#define IS_URL_CHAR(c)                                                         \
+  (BIT_AT(normal_url_char, (unsigned char)c) || ((c) & 0x80))
+#define IS_HOST_CHAR(c)                                                        \
+  (IS_ALPHANUM(c) || (c) == '.' || (c) == '-' || (c) == '_')
+#endif
+
+
+
+enum state
+  { s_dead = 1 /* important that this is > 0 */
+
+  , s_start_req_or_res
+  , s_res_or_resp_H
+  , s_start_res
+  , s_res_H
+  , s_res_HT
+  , s_res_HTT
+  , s_res_HTTP
+  , s_res_first_http_major
+  , s_res_http_major
+  , s_res_first_http_minor
+  , s_res_http_minor
+  , s_res_first_status_code
+  , s_res_status_code
+  , s_res_status_start
+  , s_res_status
+  , s_res_line_almost_done
+
+  , s_start_req
+
+  , s_req_method
+  , s_req_spaces_before_url
+  , s_req_schema
+  , s_req_schema_slash
+  , s_req_schema_slash_slash
+  , s_req_server_start
+  , s_req_server
+  , s_req_server_with_at
+  , s_req_path
+  , s_req_query_string_start
+  , s_req_query_string
+  , s_req_fragment_start
+  , s_req_fragment
+  , s_req_http_start
+  , s_req_http_H
+  , s_req_http_HT
+  , s_req_http_HTT
+  , s_req_http_HTTP
+  , s_req_first_http_major
+  , s_req_http_major
+  , s_req_first_http_minor
+  , s_req_http_minor
+  , s_req_line_almost_done
+
+  , s_header_field_start
+  , s_header_field
+  , s_header_value_discard_ws
+  , s_header_value_discard_ws_almost_done
+  , s_header_value_discard_lws
+  , s_header_value_start
+  , s_header_value
+  , s_header_value_lws
+
+  , s_header_almost_done
+
+  , s_chunk_size_start
+  , s_chunk_size
+  , s_chunk_parameters
+  , s_chunk_size_almost_done
+
+  , s_headers_almost_done
+  , s_headers_done
+
+  /* Important: 's_headers_done' must be the last 'header' state. All
+   * states beyond this must be 'body' states. It is used for overflow
+   * checking. See the PARSING_HEADER() macro.
+   */
+
+  , s_chunk_data
+  , s_chunk_data_almost_done
+  , s_chunk_data_done
+
+  , s_body_identity
+  , s_body_identity_eof
+
+  , s_message_done
+  };
+
+
+enum http_host_state
+  {
+    s_http_host_dead = 1
+  , s_http_userinfo_start
+  , s_http_userinfo
+  , s_http_host_start
+  , s_http_host_v6_start
+  , s_http_host
+  , s_http_host_v6
+  , s_http_host_v6_end
+  , s_http_host_v6_zone_start
+  , s_http_host_v6_zone
+  , s_http_host_port_start
+  , s_http_host_port
+};
+
+/* Our URL parser.
+ *
+ * This is designed to be shared by http_parser_execute() for URL validation,
+ * hence it has a state transition + byte-for-byte interface. In addition, it
+ * is meant to be embedded in http_parser_parse_url(), which does the dirty
+ * work of turning state transitions URL components for its API.
+ *
+ * This function should only be invoked with non-space characters. It is
+ * assumed that the caller cares about (and can detect) the transition between
+ * URL and non-URL states by looking for these.
+ */
+static enum state
+parse_url_char(enum state s, const char ch)
+{
+  if (ch == ' ' || ch == '\r' || ch == '\n') {
+    return s_dead;
+  }
+
+#if HTTP_PARSER_STRICT
+  if (ch == '\t' || ch == '\f') {
+    return s_dead;
+  }
+#endif
+
+  switch (s) {
+    case s_req_spaces_before_url:
+      /* Proxied requests are followed by scheme of an absolute URI (alpha).
+       * All methods except CONNECT are followed by '/' or '*'.
+       */
+
+      if (ch == '/' || ch == '*') {
+        return s_req_path;
+      }
+
+      if (IS_ALPHA(ch)) {
+        return s_req_schema;
+      }
+
+      break;
+
+    case s_req_schema:
+      if (IS_ALPHA(ch)) {
+        return s;
+      }
+
+      if (ch == ':') {
+        return s_req_schema_slash;
+      }
+
+      break;
+
+    case s_req_schema_slash:
+      if (ch == '/') {
+        return s_req_schema_slash_slash;
+      }
+
+      break;
+
+    case s_req_schema_slash_slash:
+      if (ch == '/') {
+        return s_req_server_start;
+      }
+
+      break;
+
+    case s_req_server_with_at:
+      if (ch == '@') {
+        return s_dead;
+      }
+
+    /* FALLTHROUGH */
+    case s_req_server_start:
+    case s_req_server:
+      if (ch == '/') {
+        return s_req_path;
+      }
+
+      if (ch == '?') {
+        return s_req_query_string_start;
+      }
+
+      if (ch == '@') {
+        return s_req_server_with_at;
+      }
+
+      if (IS_USERINFO_CHAR(ch) || ch == '[' || ch == ']') {
+        return s_req_server;
+      }
+
+      break;
+
+    case s_req_path:
+      if (IS_URL_CHAR(ch)) {
+        return s;
+      }
+
+      switch (ch) {
+        case '?':
+          return s_req_query_string_start;
+
+        case '#':
+          return s_req_fragment_start;
+      }
+
+      break;
+
+    case s_req_query_string_start:
+    case s_req_query_string:
+      if (IS_URL_CHAR(ch)) {
+        return s_req_query_string;
+      }
+
+      switch (ch) {
+        case '?':
+          /* allow extra '?' in query string */
+          return s_req_query_string;
+
+        case '#':
+          return s_req_fragment_start;
+      }
+
+      break;
+
+    case s_req_fragment_start:
+      if (IS_URL_CHAR(ch)) {
+        return s_req_fragment;
+      }
+
+      switch (ch) {
+        case '?':
+          return s_req_fragment;
+
+        case '#':
+          return s;
+      }
+
+      break;
+
+    case s_req_fragment:
+      if (IS_URL_CHAR(ch)) {
+        return s;
+      }
+
+      switch (ch) {
+        case '?':
+        case '#':
+          return s;
+      }
+
+      break;
+
+    default:
+      break;
+  }
+
+  /* We should never fall out of the switch above unless there's an error */
+  return s_dead;
+}
+
+static enum http_host_state
+http_parse_host_char(enum http_host_state s, const char ch) {
+  switch(s) {
+    case s_http_userinfo:
+    case s_http_userinfo_start:
+      if (ch == '@') {
+        return s_http_host_start;
+      }
+
+      if (IS_USERINFO_CHAR(ch)) {
+        return s_http_userinfo;
+      }
+      break;
+
+    case s_http_host_start:
+      if (ch == '[') {
+        return s_http_host_v6_start;
+      }
+
+      if (IS_HOST_CHAR(ch)) {
+        return s_http_host;
+      }
+
+      break;
+
+    case s_http_host:
+      if (IS_HOST_CHAR(ch)) {
+        return s_http_host;
+      }
+
+    /* FALLTHROUGH */
+    case s_http_host_v6_end:
+      if (ch == ':') {
+        return s_http_host_port_start;
+      }
+
+      break;
+
+    case s_http_host_v6:
+      if (ch == ']') {
+        return s_http_host_v6_end;
+      }
+
+    /* FALLTHROUGH */
+    case s_http_host_v6_start:
+      if (IS_HEX(ch) || ch == ':' || ch == '.') {
+        return s_http_host_v6;
+      }
+
+      if (s == s_http_host_v6 && ch == '%') {
+        return s_http_host_v6_zone_start;
+      }
+      break;
+
+    case s_http_host_v6_zone:
+      if (ch == ']') {
+        return s_http_host_v6_end;
+      }
+
+    /* FALLTHROUGH */
+    case s_http_host_v6_zone_start:
+      /* RFC 6874 Zone ID consists of 1*( unreserved / pct-encoded) */
+      if (IS_ALPHANUM(ch) || ch == '%' || ch == '.' || ch == '-' || ch == '_' ||
+          ch == '~') {
+        return s_http_host_v6_zone;
+      }
+      break;
+
+    case s_http_host_port:
+    case s_http_host_port_start:
+      if (IS_NUM(ch)) {
+        return s_http_host_port;
+      }
+
+      break;
+
+    default:
+      break;
+  }
+  return s_http_host_dead;
+}
+
+static int
+http_parse_host(const char * buf, struct http_parser_url *u, int found_at) {
+  assert(u->field_set & (1 << UF_HOST));
+  enum http_host_state s;
+
+  const char *p;
+  size_t buflen = u->field_data[UF_HOST].off + u->field_data[UF_HOST].len;
+
+  u->field_data[UF_HOST].len = 0;
+
+  s = found_at ? s_http_userinfo_start : s_http_host_start;
+
+  for (p = buf + u->field_data[UF_HOST].off; p < buf + buflen; p++) {
+    enum http_host_state new_s = http_parse_host_char(s, *p);
+
+    if (new_s == s_http_host_dead) {
+      return 1;
+    }
+
+    switch(new_s) {
+      case s_http_host:
+        if (s != s_http_host) {
+          u->field_data[UF_HOST].off = p - buf;
+        }
+        u->field_data[UF_HOST].len++;
+        break;
+
+      case s_http_host_v6:
+        if (s != s_http_host_v6) {
+          u->field_data[UF_HOST].off = p - buf;
+        }
+        u->field_data[UF_HOST].len++;
+        break;
+
+      case s_http_host_v6_zone_start:
+      case s_http_host_v6_zone:
+        u->field_data[UF_HOST].len++;
+        break;
+
+      case s_http_host_port:
+        if (s != s_http_host_port) {
+          u->field_data[UF_PORT].off = p - buf;
+          u->field_data[UF_PORT].len = 0;
+          u->field_set |= (1 << UF_PORT);
+        }
+        u->field_data[UF_PORT].len++;
+        break;
+
+      case s_http_userinfo:
+        if (s != s_http_userinfo) {
+          u->field_data[UF_USERINFO].off = p - buf ;
+          u->field_data[UF_USERINFO].len = 0;
+          u->field_set |= (1 << UF_USERINFO);
+        }
+        u->field_data[UF_USERINFO].len++;
+        break;
+
+      default:
+        break;
+    }
+    s = new_s;
+  }
+
+  /* Make sure we don't end somewhere unexpected */
+  switch (s) {
+    case s_http_host_start:
+    case s_http_host_v6_start:
+    case s_http_host_v6:
+    case s_http_host_v6_zone_start:
+    case s_http_host_v6_zone:
+    case s_http_host_port_start:
+    case s_http_userinfo:
+    case s_http_userinfo_start:
+      return 1;
+    default:
+      break;
+  }
+
+  return 0;
+}
+
+
+int
+http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
+                      struct http_parser_url *u)
+{
+  enum state s;
+  const char *p;
+  enum http_parser_url_fields uf, old_uf;
+  int found_at = 0;
+
+  u->port = u->field_set = 0;
+  s = is_connect ? s_req_server_start : s_req_spaces_before_url;
+  old_uf = UF_MAX;
+
+  for (p = buf; p < buf + buflen; p++) {
+    s = parse_url_char(s, *p);
+
+    /* Figure out the next field that we're operating on */
+    switch (s) {
+      case s_dead:
+        return 1;
+
+      /* Skip delimeters */
+      case s_req_schema_slash:
+      case s_req_schema_slash_slash:
+      case s_req_server_start:
+      case s_req_query_string_start:
+      case s_req_fragment_start:
+        continue;
+
+      case s_req_schema:
+        uf = UF_SCHEMA;
+        break;
+
+      case s_req_server_with_at:
+        found_at = 1;
+
+      /* FALLTROUGH */
+      case s_req_server:
+        uf = UF_HOST;
+        break;
+
+      case s_req_path:
+        uf = UF_PATH;
+        break;
+
+      case s_req_query_string:
+        uf = UF_QUERY;
+        break;
+
+      case s_req_fragment:
+        uf = UF_FRAGMENT;
+        break;
+
+      default:
+        assert(!"Unexpected state");
+        return 1;
+    }
+
+    /* Nothing's changed; soldier on */
+    if (uf == old_uf) {
+      u->field_data[uf].len++;
+      continue;
+    }
+
+    u->field_data[uf].off = p - buf;
+    u->field_data[uf].len = 1;
+
+    u->field_set |= (1 << uf);
+    old_uf = uf;
+  }
+
+  /* host must be present if there is a schema */
+  /* parsing http:///toto will fail */
+  if ((u->field_set & (1 << UF_SCHEMA)) &&
+      (u->field_set & (1 << UF_HOST)) == 0) {
+    return 1;
+  }
+
+  if (u->field_set & (1 << UF_HOST)) {
+    if (http_parse_host(buf, u, found_at) != 0) {
+      return 1;
+    }
+  }
+
+  /* CONNECT requests can only contain "hostname:port" */
+  if (is_connect && u->field_set != ((1 << UF_HOST)|(1 << UF_PORT))) {
+    return 1;
+  }
+
+  if (u->field_set & (1 << UF_PORT)) {
+    /* Don't bother with endp; we've already validated the string */
+    unsigned long v = strtoul(buf + u->field_data[UF_PORT].off, NULL, 10);
+
+    /* Ports have a max value of 2^16 */
+    if (v > 0xffff) {
+      return 1;
+    }
+
+    u->port = (uint16_t) v;
+  }
+
+  return 0;
+}
diff --git a/src/contrib/url-parser/url_parser.h b/src/contrib/url-parser/url_parser.h
new file mode 100644
index 0000000..0f916e0
--- /dev/null
+++ b/src/contrib/url-parser/url_parser.h
@@ -0,0 +1,64 @@
+/* Based on src/http/ngx_http_parse.c from NGINX copyright Igor Sysoev
+ *
+ * Additional changes are licensed under the same terms as NGINX and
+ * copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/**
+ * This is the http_parser_parse_url function extracted from joyent's
+ * http-parser library.
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+enum http_parser_url_fields
+  { UF_SCHEMA           = 0
+  , UF_HOST             = 1
+  , UF_PORT             = 2
+  , UF_PATH             = 3
+  , UF_QUERY            = 4
+  , UF_FRAGMENT         = 5
+  , UF_USERINFO         = 6
+  , UF_MAX              = 7
+  };
+
+/* Result structure for http_parser_parse_url().
+ *
+ * Callers should index into field_data[] with UF_* values iff field_set
+ * has the relevant (1 << UF_*) bit set. As a courtesy to clients (and
+ * because we probably have padding left over), we convert any port to
+ * a uint16_t.
+ */
+struct http_parser_url {
+  uint16_t field_set;           /* Bitmask of (1 << UF_*) values */
+  uint16_t port;                /* Converted UF_PORT string */
+
+  struct {
+    uint16_t off;               /* Offset into buffer in which field starts */
+    uint16_t len;               /* Length of run in buffer */
+  } field_data[UF_MAX];
+};
+
+int
+http_parser_parse_url(const char *buf, size_t buflen, int is_connect,
+                      struct http_parser_url *u);
diff --git a/src/contrib/vpool/vpool.c b/src/contrib/vpool/vpool.c
new file mode 100644
index 0000000..b7c0305
--- /dev/null
+++ b/src/contrib/vpool/vpool.c
@@ -0,0 +1,241 @@
+/*
+ * Copyright (c) 2006, 2008 Alexey Vatchenko <av@bsdua.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/types.h>
+
+#include <errno.h>
+#include <limits.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "contrib/vpool/vpool.h"
+
+static void	vpool_shift(struct vpool *pool);
+static int	vpool_new_size(struct vpool *pool, size_t datsize,
+		    size_t *size);
+static int	vpool_resize(struct vpool *pool, size_t datsize);
+
+static void
+vpool_shift(struct vpool *pool)
+{
+	if (pool->v_buf != pool->v_basebuf) {
+		memmove(pool->v_basebuf, pool->v_buf, pool->v_off);
+		pool->v_buf = pool->v_basebuf;
+	}
+}
+
+static int
+vpool_new_size(struct vpool *pool, size_t datsize, size_t *size)
+{
+	size_t need;
+	size_t rem;
+
+	if (datsize <= pool->v_size - pool->v_off) {
+		*size = pool->v_size;
+		return (0);
+	}
+
+	/* Check limit of new requested size */
+	if (pool->v_limit - pool->v_off < datsize) {
+		return (EFBIG);
+	}
+	need = pool->v_off + datsize;
+
+	/* Check limit of new size aligned to block size */
+	rem = need % pool->v_blksize;
+	if (rem != 0) {
+		if (pool->v_limit - pool->v_off >=
+		    datsize + (pool->v_blksize - rem)) {
+			need += pool->v_blksize - rem;
+		} else {
+			need = pool->v_limit;
+		}
+	}
+
+	*size = need;
+	return (0);
+}
+
+static int
+vpool_resize(struct vpool *pool, size_t datsize)
+{
+	void *ret;
+	size_t size;
+	int error;
+
+	error = vpool_new_size(pool, datsize, &size);
+	if (error != 0) {
+		return (error);
+	}
+
+	if (size > pool->v_size) {
+		ret = malloc(size);
+		if (ret == NULL) {
+			return (ENOMEM);
+		}
+
+		memcpy(ret, pool->v_buf, pool->v_off);
+		free(pool->v_basebuf);
+		pool->v_basebuf = pool->v_buf = ret;
+		pool->v_size = size;
+	} else if ((pool->v_size - pool->v_off) -
+		   (pool->v_buf - pool->v_basebuf) < datsize) {
+		vpool_shift(pool);
+	}
+
+	return (0);
+}
+
+void
+vpool_init(struct vpool *pool, size_t blksize, size_t limit)
+{
+
+	pool->v_basebuf = pool->v_buf = NULL;
+	pool->v_off = pool->v_size = 0;
+
+	pool->v_blksize = (blksize == 0) ? 4096 : blksize;	/* XXX */
+	pool->v_limit = (limit == 0) ? SIZE_MAX : limit;
+
+	pool->v_lasterr = 0;
+}
+
+void
+vpool_final(struct vpool *pool)
+{
+	free(pool->v_basebuf);
+}
+
+void
+vpool_reset(struct vpool *pool)
+{
+	free(pool->v_basebuf);
+	pool->v_basebuf = pool->v_buf = NULL;
+	pool->v_off = pool->v_size = 0;
+	pool->v_lasterr = 0;
+}
+
+void
+vpool_wipe(struct vpool *pool)
+{
+	pool->v_off = 0;
+	pool->v_lasterr = 0;
+}
+
+void *
+vpool_insert(struct vpool *pool, size_t where, void *data, size_t datsize)
+{
+	void *ret;
+	int error;
+
+	error = vpool_resize(pool, datsize);
+	if (error != 0) {
+		pool->v_lasterr = error;
+		return (NULL);
+	}
+
+	/*
+	 * If ``where'' is greater than or equal to offset then
+	 * we are appending data to the end of the buffer.
+	 */
+	if (where > pool->v_off) {
+		where = pool->v_off;
+	}
+
+	ret = (uint8_t *)pool->v_buf + where;
+	if (pool->v_off - where > 0) {
+		memmove(ret + datsize, ret, pool->v_off - where);
+	}
+	memcpy(ret, data, datsize);
+	pool->v_off += datsize;
+	pool->v_lasterr = 0;
+
+	return (ret);
+}
+
+void *
+vpool_expand(struct vpool *pool, size_t where, size_t size)
+{
+	void *ret;
+	int error;
+
+	error = vpool_resize(pool, size);
+	if (error != 0) {
+		pool->v_lasterr = error;
+		return (NULL);
+	}
+
+	/*
+	 * If ``where'' is greater than or equal to offset then
+	 * we are appending data to the end of the buffer.
+	 */
+	if (where > pool->v_off) {
+		where = pool->v_off;
+	}
+
+	ret = (uint8_t *)pool->v_buf + where;
+	if (pool->v_off - where > 0) {
+		memmove(ret + size, ret, pool->v_off - where);
+	}
+	pool->v_off += size;
+	pool->v_lasterr = 0;
+
+	return (ret);
+}
+
+int
+vpool_truncate(struct vpool *pool,
+    size_t where, size_t size, enum vpool_trunc how)
+{
+	/* Check if caller wants to remove more data than we have */
+	if (where >= pool->v_off ||
+	    size > pool->v_off || pool->v_off - size < where) {
+		pool->v_lasterr = ERANGE;
+		return (pool->v_lasterr);
+	}
+
+	if (how == VPOOL_EXCLUDE) {
+		if (where == 0) {
+			/*
+			 * Optimization.
+			 * Don't move data, just adjust pointer.
+			 */
+			pool->v_buf = (uint8_t *)pool->v_buf + size;
+		} else {
+			memmove((uint8_t *)pool->v_buf + where,
+				(uint8_t *)pool->v_buf + where + size,
+				pool->v_off - size - where);
+		}
+		pool->v_off -= size;
+	} else {
+		pool->v_buf = (uint8_t *)pool->v_buf + where;
+		pool->v_off = size;
+	}
+
+	pool->v_lasterr = 0;
+	return (0);
+}
+
+void
+vpool_export(struct vpool *pool, void **buf, size_t *size)
+{
+	vpool_shift(pool);
+	*buf = pool->v_buf;
+	*size = pool->v_off;
+	pool->v_basebuf = pool->v_buf = NULL;
+	pool->v_off = pool->v_size = 0;
+	pool->v_lasterr = 0;
+}
diff --git a/src/contrib/vpool/vpool.h b/src/contrib/vpool/vpool.h
new file mode 100644
index 0000000..82e3d66
--- /dev/null
+++ b/src/contrib/vpool/vpool.h
@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2006, 2008 Alexey Vatchenko <av@bsdua.org>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ * VPool: implementation of pool of data with a variable size.
+ */
+#ifndef _VPOOL_H_
+#define _VPOOL_H_
+
+#include <stddef.h>
+#include <limits.h>
+
+struct vpool {
+	void	*v_basebuf;	/* pointer returned by (re|m)alloc() */
+	void	*v_buf;		/* actual data starts here */
+	size_t	v_off;
+	size_t	v_size;
+
+	size_t	v_blksize;
+	size_t	v_limit;
+	int	v_lasterr;
+};
+
+enum vpool_trunc {VPOOL_EXCLUDE, VPOOL_INCLUDE};
+#define VPOOL_TAIL	UINT_MAX
+
+void	vpool_init(struct vpool *pool, size_t blksize, size_t limit);
+void	vpool_final(struct vpool *pool);
+
+void	vpool_reset(struct vpool *pool);
+void	vpool_wipe(struct vpool *pool);
+
+void *	vpool_insert(struct vpool *pool,
+	    size_t where, void *data, size_t datsize);
+void *	vpool_expand(struct vpool *pool, size_t where, size_t size);
+
+int	vpool_truncate(struct vpool *pool,
+	    size_t where, size_t size, enum vpool_trunc how);
+
+#define vpool_is_empty(pool)		((pool)->v_off == 0)
+#define vpool_get_buf(pool)		((pool)->v_buf)
+#define vpool_get_length(pool)		((pool)->v_off)
+#define vpool_get_error(pool)		((pool)->v_lasterr)
+
+void	vpool_export(struct vpool *pool, void **buf, size_t *size);
+
+#endif /* !_VPOOL_H_ */
diff --git a/src/contrib/wire_ctx.h b/src/contrib/wire_ctx.h
new file mode 100644
index 0000000..f4f1789
--- /dev/null
+++ b/src/contrib/wire_ctx.h
@@ -0,0 +1,355 @@
+/*  Copyright (C) 2019 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include "contrib/string.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+
+/*!
+ * \brief Struct to keep the wire context.
+ */
+typedef struct wire_ctx {
+	size_t size;
+	uint8_t *wire;
+	uint8_t *position;
+	int error;
+	bool readonly;
+} wire_ctx_t;
+
+/*!
+ * \brief Initialize wire context.
+ */
+static inline wire_ctx_t wire_ctx_init(uint8_t *data, size_t size)
+{
+	assert(data);
+
+	wire_ctx_t result = {
+		.size = size,
+		.wire = data,
+		.position = data,
+		.error = KNOT_EOK,
+		.readonly = false
+	};
+
+	return result;
+}
+
+/*!
+ * \brief Initialize read only wire context.
+ *
+ * \note No write is performed, and error is set to KNOT_EACCES.
+ *
+ */
+static inline wire_ctx_t wire_ctx_init_const(const uint8_t *data, size_t size)
+{
+	assert(data);
+
+	wire_ctx_t result = wire_ctx_init((uint8_t *)data, size);
+	result.readonly = true;
+
+	return result;
+}
+
+/*!
+ * \brief Gets actual position.
+ *
+ * \return position from the begin.
+ */
+static inline size_t wire_ctx_offset(wire_ctx_t *ctx)
+{
+	assert(ctx);
+
+	return ctx->position - ctx->wire;
+}
+
+/*!
+ * \brief Set position offset from the begin.
+ *
+ * \param offset Wire offset (starts from 0).
+ *
+ * \note Noop if previous error.
+ */
+static inline void wire_ctx_set_offset(wire_ctx_t *ctx, size_t offset)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return;
+	}
+
+	if (offset > ctx->size) {
+		ctx->error = KNOT_ERANGE;
+		return;
+	}
+
+	ctx->position = ctx->wire + offset;
+}
+
+/*!
+ * \brief Gets available bytes.
+ *
+ * \return Number of bytes to end.
+ */
+static inline size_t wire_ctx_available(wire_ctx_t *ctx)
+{
+	assert(ctx);
+
+	return ctx->size - wire_ctx_offset(ctx);
+}
+
+/*!
+ * \brief Add offset to the current position.
+ *
+ * \note Noop if previous error.
+ */
+static inline void wire_ctx_skip(wire_ctx_t *ctx, ssize_t offset)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return;
+	}
+
+	// Check for out of scope skip.
+	if (offset >= 0) {
+		if (offset > wire_ctx_available(ctx)) {
+			ctx->error = KNOT_ERANGE;
+			return;
+		}
+	} else {
+		if (-offset > wire_ctx_offset(ctx)) {
+			ctx->error = KNOT_ERANGE;
+			return;
+		}
+	}
+
+	ctx->position += offset;
+}
+
+/*!
+ * \brief Check the context if reading is possible.
+ */
+static inline int wire_ctx_can_read(wire_ctx_t *ctx, size_t size)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return ctx->error;
+	}
+
+	if (wire_ctx_available(ctx) < size) {
+		return KNOT_EFEWDATA;
+	}
+
+	return KNOT_EOK;
+}
+
+/*!
+ * \brief Check the context if writing is possible.
+ */
+static inline int wire_ctx_can_write(wire_ctx_t *ctx, size_t size)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return ctx->error;
+	}
+
+	if (ctx->readonly) {
+		return KNOT_EACCES;
+	}
+
+	if (wire_ctx_available(ctx) < size) {
+		return KNOT_ESPACE;
+	}
+
+	return KNOT_EOK;
+}
+
+
+static inline void wire_ctx_read(wire_ctx_t *ctx, void *data, size_t size)
+{
+	assert(ctx);
+	assert(data);
+
+	if (ctx->error != KNOT_EOK) {
+		/* Avoid leaving data uninitialized. */
+		memzero(data, size);
+		return;
+	}
+
+	int ret = wire_ctx_can_read(ctx, size);
+	if (ret != KNOT_EOK) {
+		ctx->error = ret;
+		memzero(data, size);
+		return;
+	}
+
+	memcpy(data, ctx->position, size);
+	ctx->position += size;
+}
+
+static inline uint8_t wire_ctx_read_u8(wire_ctx_t *ctx)
+{
+	uint8_t result;
+	wire_ctx_read(ctx, &result, sizeof(result));
+
+	return result;
+}
+
+static inline uint16_t wire_ctx_read_u16(wire_ctx_t *ctx)
+{
+	uint16_t result;
+	wire_ctx_read(ctx, &result, sizeof(result));
+
+	return be16toh(result);
+}
+
+static inline uint32_t wire_ctx_read_u32(wire_ctx_t *ctx)
+{
+	uint32_t result;
+	wire_ctx_read(ctx, &result, sizeof(result));
+
+	return be32toh(result);
+}
+
+static inline uint64_t wire_ctx_read_u48(wire_ctx_t *ctx)
+{
+	/* This case is slightly tricky. */
+	uint64_t result = 0;
+	wire_ctx_read(ctx, (uint8_t *)&result + 1, 6);
+
+	return be64toh(result) >> 8;
+}
+
+static inline uint64_t wire_ctx_read_u64(wire_ctx_t *ctx)
+{
+	uint64_t result;
+	wire_ctx_read(ctx, &result, sizeof(result));
+
+	return be64toh(result);
+}
+
+
+static inline void wire_ctx_write(wire_ctx_t *ctx, const void *data, size_t size)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return;
+	}
+
+	if (size == 0) {
+		return;
+	}
+
+	assert(data);
+
+	int ret = wire_ctx_can_write(ctx, size);
+	if (ret != KNOT_EOK) {
+		ctx->error = ret;
+		return;
+	}
+
+	memcpy(ctx->position, data, size);
+	ctx->position += size;
+}
+
+static inline void wire_ctx_write_u8(wire_ctx_t *ctx, uint8_t value)
+{
+	wire_ctx_write(ctx, &value, sizeof(value));
+}
+
+static inline void wire_ctx_write_u16(wire_ctx_t *ctx, uint16_t value)
+{
+	uint16_t beval = htobe16(value);
+	wire_ctx_write(ctx, &beval, sizeof(beval));
+}
+
+static inline void wire_ctx_write_u32(wire_ctx_t *ctx, uint32_t value)
+{
+	uint32_t beval = htobe32(value);
+	wire_ctx_write(ctx, &beval, sizeof(beval));
+}
+
+static inline void wire_ctx_write_u48(wire_ctx_t *ctx, uint64_t value)
+{
+	/* This case is slightly tricky. */
+	uint64_t swapped = htobe64(value << 8);
+	wire_ctx_write(ctx, (uint8_t *)&swapped + 1, 6);
+}
+
+static inline void wire_ctx_write_u64(wire_ctx_t *ctx, uint64_t value)
+{
+	uint64_t beval = htobe64(value);
+	wire_ctx_write(ctx, &beval, sizeof(beval));
+}
+
+static inline void wire_ctx_clear(wire_ctx_t *ctx, size_t size)
+{
+	assert(ctx);
+
+	if (ctx->error != KNOT_EOK) {
+		return;
+	}
+
+	if (size == 0) {
+		return;
+	}
+
+	int ret = wire_ctx_can_write(ctx, size);
+	if (ret != KNOT_EOK) {
+		ctx->error = ret;
+		return;
+	}
+
+	memzero(ctx->position, size);
+	ctx->position += size;
+}
+
+static inline void wire_ctx_copy(wire_ctx_t *dst, wire_ctx_t *src, size_t size)
+{
+	assert(dst);
+	assert(src);
+
+	if (size == 0 || dst->error != KNOT_EOK) {
+		return;
+	}
+
+	if (wire_ctx_can_read(src, size) != KNOT_EOK) {
+		dst->error = KNOT_EFEWDATA;
+		return;
+	}
+
+	int ret = wire_ctx_can_write(dst, size);
+	if (ret != KNOT_EOK) {
+		dst->error = ret;
+		return;
+	}
+
+	memcpy(dst->position, src->position, size);
+	dst->position += size;
+	src->position += size;
+}