Adding upstream version 3.2.6.upstream/3.2.6upstream

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

99 files changed, 27503 insertions, 0 deletions

diff --git a/src/libknot/Makefile.inc b/src/libknot/Makefile.inc
new file mode 100755
index 0000000..73a4d6e
--- /dev/null
+++ b/src/libknot/Makefile.inc
@@ -0,0 +1,136 @@
+lib_LTLIBRARIES += libknot.la
+pkgconfig_DATA  += libknot.pc
+
+libknot_la_CPPFLAGS = $(AM_CPPFLAGS) $(CFLAG_VISIBILITY) $(lmdb_CFLAGS) \
+                      ${fuzzer_CFLAGS}
+libknot_la_LDFLAGS  = $(AM_LDFLAGS) $(libknot_VERSION_INFO) $(LDFLAG_EXCLUDE_LIBS) \
+                      ${fuzzer_LDFLAGS}
+libknot_la_LIBADD   = libdnssec.la $(libcontrib_LIBS) $(lmdb_LIBS) $(math_LIBS)
+
+if EMBEDDED_LIBNGTCP2
+libknot_la_LIBADD += $(libembngtcp2_LIBS)
+endif EMBEDDED_LIBNGTCP2
+
+include_libknotdir = $(includedir)
+nobase_include_libknot_HEADERS = \
+	libknot/attribute.h			\
+	libknot/codes.h				\
+	libknot/consts.h			\
+	libknot/control/control.h		\
+	libknot/cookies.h			\
+	libknot/descriptor.h			\
+	libknot/dname.h				\
+	libknot/dynarray.h			\
+	libknot/endian.h			\
+	libknot/errcode.h			\
+	libknot/error.h				\
+	libknot/libknot.h			\
+	libknot/lookup.h			\
+	libknot/mm_ctx.h			\
+	libknot/db/db.h				\
+	libknot/db/db_lmdb.h			\
+	libknot/db/db_trie.h			\
+	libknot/packet/compr.h			\
+	libknot/packet/pkt.h			\
+	libknot/packet/rrset-wire.h		\
+	libknot/packet/wire.h			\
+	libknot/probe/data.h			\
+	libknot/probe/probe.h			\
+	libknot/rdata.h				\
+	libknot/rdataset.h			\
+	libknot/rrset-dump.h			\
+	libknot/rrset.h				\
+	libknot/rrtype/dnskey.h			\
+	libknot/rrtype/ds.h			\
+	libknot/rrtype/naptr.h			\
+	libknot/rrtype/nsec.h			\
+	libknot/rrtype/nsec3.h			\
+	libknot/rrtype/nsec3param.h		\
+	libknot/rrtype/opt.h			\
+	libknot/rrtype/rdname.h			\
+	libknot/rrtype/rrsig.h			\
+	libknot/rrtype/soa.h			\
+	libknot/rrtype/svcb.h			\
+	libknot/rrtype/tsig.h			\
+	libknot/rrtype/zonemd.h			\
+	libknot/tsig-op.h			\
+	libknot/tsig.h				\
+	libknot/wire.h				\
+	libknot/yparser/yparser.h		\
+	libknot/yparser/ypformat.h		\
+	libknot/yparser/ypschema.h		\
+	libknot/yparser/yptrafo.h		\
+	libknot/version.h			\
+	libknot/xdp/tcp_iobuf.h			\
+	libknot/xdp.h
+
+libknot_la_SOURCES = \
+	libknot/codes.c				\
+	libknot/control/control.c		\
+	libknot/cookies.c			\
+	libknot/descriptor.c			\
+	libknot/dname.c				\
+	libknot/error.c				\
+	libknot/db/db_lmdb.c			\
+	libknot/db/db_trie.c			\
+	libknot/packet/pkt.c			\
+	libknot/packet/rrset-wire.c		\
+	libknot/probe/data.c			\
+	libknot/probe/probe.c			\
+	libknot/rdataset.c			\
+	libknot/rrset-dump.c			\
+	libknot/rrset.c				\
+	libknot/rrtype/naptr.c			\
+	libknot/rrtype/opt.c			\
+	libknot/rrtype/tsig.c			\
+	libknot/tsig-op.c			\
+	libknot/tsig.c				\
+	libknot/yparser/yparser.c		\
+	libknot/yparser/ypbody.c		\
+	libknot/yparser/ypformat.c		\
+	libknot/yparser/ypschema.c		\
+	libknot/yparser/yptrafo.c		\
+	libknot/xdp/tcp_iobuf.c
+
+if EMBEDDED_LIBBPF
+libknot_la_LIBADD   += $(libembbpf_LIBS)
+endif EMBEDDED_LIBBPF
+if ENABLE_XDP
+libknot_la_CPPFLAGS += $(libbpf_CFLAGS)
+libknot_la_LIBADD   += $(libbpf_LIBS)
+
+nobase_include_libknot_HEADERS += \
+	libknot/xdp/bpf-consts.h		\
+	libknot/xdp/eth.h			\
+	libknot/xdp/msg.h			\
+	libknot/xdp/tcp.h			\
+	libknot/xdp/xdp.h
+
+libknot_la_SOURCES  += \
+	libknot/xdp/bpf-kernel-obj.c		\
+	libknot/xdp/bpf-kernel-obj.h		\
+	libknot/xdp/bpf-user.c			\
+	libknot/xdp/bpf-user.h			\
+	libknot/xdp/eth.c			\
+	libknot/xdp/msg_init.h			\
+	libknot/xdp/protocols.h			\
+	libknot/xdp/tcp.c			\
+	libknot/xdp/xdp.c
+
+if ENABLE_QUIC
+
+libknot_la_CPPFLAGS += $(libngtcp2_CFLAGS) $(gnutls_CFLAGS)
+libknot_la_LIBADD   += $(libngtcp2_LIBS) $(gnutls_LIBS)
+
+nobase_include_libknot_HEADERS += \
+        libknot/xdp/quic.h                      \
+        libknot/xdp/quic_conn.h
+
+libknot_la_SOURCES  += \
+	libknot/xdp/quic.c                      \
+        libknot/xdp/quic_conn.c
+
+endif ENABLE_QUIC
+endif ENABLE_XDP
+
+DIST_SUBDIRS = libknot/xdp
diff --git a/src/libknot/attribute.h b/src/libknot/attribute.h
new file mode 100644
index 0000000..525aef3
--- /dev/null
+++ b/src/libknot/attribute.h
@@ -0,0 +1,51 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Function and variable attributes.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+/*! \brief Library visibility macros. */
+#define _public_ __attribute__((visibility("default")))
+#define _hidden_ __attribute__((visibility("hidden")))
+
+#define _unused_ __attribute__((unused))
+
+#define _cleanup_(var) __attribute__((cleanup(var)))
+
+/*! \brief GNU C function attributes. */
+#if __GNUC__ >= 3
+#define _pure_      __attribute__ ((pure))
+#define _const_     __attribute__ ((const))
+#define _noreturn_  __attribute__ ((noreturn))
+#define _malloc_    __attribute__ ((malloc))
+#define _mustcheck_ __attribute__ ((warn_unused_result))
+#else
+#define _pure_
+#define _const_
+#define _noreturn_
+#define _malloc_
+#define _mustcheck_
+#endif
+
+/*! @} */
diff --git a/src/libknot/codes.c b/src/libknot/codes.c
new file mode 100644
index 0000000..e6b38cf
--- /dev/null
+++ b/src/libknot/codes.c
@@ -0,0 +1,129 @@
+/*  Copyright (C) 2023 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 "libknot/attribute.h"
+#include "libknot/codes.h"
+#include "libknot/consts.h"
+#include "libdnssec/key.h"
+
+_public_
+const knot_lookup_t knot_opcode_names[] = {
+	{ KNOT_OPCODE_QUERY,  "QUERY" },
+	{ KNOT_OPCODE_IQUERY, "IQUERY" },
+	{ KNOT_OPCODE_STATUS, "STATUS" },
+	{ KNOT_OPCODE_NOTIFY, "NOTIFY" },
+	{ KNOT_OPCODE_UPDATE, "UPDATE" },
+	{ 0, NULL }
+};
+
+_public_
+const knot_lookup_t knot_rcode_names[] = {
+	{ KNOT_RCODE_NOERROR,   "NOERROR" },
+	{ KNOT_RCODE_FORMERR,   "FORMERR" },
+	{ KNOT_RCODE_SERVFAIL,  "SERVFAIL" },
+	{ KNOT_RCODE_NXDOMAIN,  "NXDOMAIN" },
+	{ KNOT_RCODE_NOTIMPL,   "NOTIMPL" },
+	{ KNOT_RCODE_REFUSED,   "REFUSED" },
+	{ KNOT_RCODE_YXDOMAIN,  "YXDOMAIN" },
+	{ KNOT_RCODE_YXRRSET,   "YXRRSET" },
+	{ KNOT_RCODE_NXRRSET,   "NXRRSET" },
+	{ KNOT_RCODE_NOTAUTH,   "NOTAUTH" },
+	{ KNOT_RCODE_NOTZONE,   "NOTZONE" },
+	{ KNOT_RCODE_BADVERS,   "BADVERS" },
+	{ KNOT_RCODE_BADKEY,    "BADKEY" },
+	{ KNOT_RCODE_BADTIME,   "BADTIME" },
+	{ KNOT_RCODE_BADMODE,   "BADMODE" },
+	{ KNOT_RCODE_BADNAME,   "BADNAME" },
+	{ KNOT_RCODE_BADALG,    "BADALG" },
+	{ KNOT_RCODE_BADTRUNC,  "BADTRUNC" },
+	{ KNOT_RCODE_BADCOOKIE, "BADCOOKIE" },
+	{ 0, NULL }
+};
+
+_public_
+const knot_lookup_t knot_tsig_rcode_names[] = {
+	{ KNOT_RCODE_BADSIG, "BADSIG" },
+	{ 0, NULL }
+};
+
+_public_
+const knot_lookup_t knot_edns_ede_names[] = {
+	{ KNOT_EDNS_EDE_OTHER,            "Other" },
+	{ KNOT_EDNS_EDE_DNSKEY_ALG,       "Unsupported DNSKEY Algorithm" },
+	{ KNOT_EDNS_EDE_DS_DIGEST,        "Unsupported DS Digest Type" },
+	{ KNOT_EDNS_EDE_STALE,            "Stale Answer" },
+	{ KNOT_EDNS_EDE_FORGED,           "Forged Answer" },
+	{ KNOT_EDNS_EDE_INDETERMINATE,    "DNSSEC Indeterminate" },
+	{ KNOT_EDNS_EDE_BOGUS,            "DNSSEC Bogus" },
+	{ KNOT_EDNS_EDE_SIG_EXPIRED,      "Signature Expired" },
+	{ KNOT_EDNS_EDE_SIG_NOTYET,       "Signature Not Yet Valid" },
+	{ KNOT_EDNS_EDE_DNSKEY_MISS,      "DNSKEY Missing" },
+	{ KNOT_EDNS_EDE_RRSIG_MISS,       "RRSIGs Missing" },
+	{ KNOT_EDNS_EDE_DNSKEY_BIT,       "No Zone Key Bit Set" },
+	{ KNOT_EDNS_EDE_NSEC_MISS,        "NSEC Missing" },
+	{ KNOT_EDNS_EDE_CACHED_ERR,       "Cached Error" },
+	{ KNOT_EDNS_EDE_NOT_READY,        "Not Ready" },
+	{ KNOT_EDNS_EDE_BLOCKED,          "Blocked" },
+	{ KNOT_EDNS_EDE_CENSORED,         "Censored" },
+	{ KNOT_EDNS_EDE_FILTERED,         "Filtered" },
+	{ KNOT_EDNS_EDE_PROHIBITED,       "Prohibited" },
+	{ KNOT_EDNS_EDE_STALE_NXD,        "Stale NXDOMAIN Answer" },
+	{ KNOT_EDNS_EDE_NOTAUTH,          "Not Authoritative" },
+	{ KNOT_EDNS_EDE_NOTSUP,           "Not Supported" },
+	{ KNOT_EDNS_EDE_NREACH_AUTH,      "No Reachable Authority" },
+	{ KNOT_EDNS_EDE_NETWORK,          "Network Error" },
+	{ KNOT_EDNS_EDE_INV_DATA,         "Invalid Data" },
+	{ KNOT_EDNS_EDE_EXPIRED_INV,      "Signature Expired before Valid" },
+	{ KNOT_EDNS_EDE_TOO_EARLY,        "Too Early" },
+	{ KNOT_EDNS_EDE_NSEC3_ITERS,      "Unsupported NSEC3 Iterations Value" },
+	{ KNOT_EDNS_EDE_NONCONF_POLICY,   "Unable to conform to policy" },
+	{ KNOT_EDNS_EDE_SYNTHESIZED,      "Synthesized" },
+	{ 0, NULL }
+};
+
+_public_
+const knot_lookup_t knot_dnssec_alg_names[] = {
+	{ DNSSEC_KEY_ALGORITHM_DELETE,            "DELETE" },
+	{ DNSSEC_KEY_ALGORITHM_RSA_MD5,           "RSAMD5" },
+	{ DNSSEC_KEY_ALGORITHM_DH,                "DH" },
+	{ DNSSEC_KEY_ALGORITHM_DSA,               "DSA" },
+	{ DNSSEC_KEY_ALGORITHM_RSA_SHA1,          "RSASHA1" },
+	{ DNSSEC_KEY_ALGORITHM_DSA_NSEC3_SHA1,    "DSA_NSEC3_SHA1" },
+	{ DNSSEC_KEY_ALGORITHM_RSA_SHA1_NSEC3,    "RSASHA1_NSEC3_SHA1" },
+	{ DNSSEC_KEY_ALGORITHM_RSA_SHA256,        "RSASHA256" },
+	{ DNSSEC_KEY_ALGORITHM_RSA_SHA512,        "RSASHA512" },
+	{ DNSSEC_KEY_ALGORITHM_ECC_GOST,          "ECC_GOST" },
+	{ DNSSEC_KEY_ALGORITHM_ECDSA_P256_SHA256, "ECDSAP256SHA256" },
+	{ DNSSEC_KEY_ALGORITHM_ECDSA_P384_SHA384, "ECDSAP384SHA384" },
+	{ DNSSEC_KEY_ALGORITHM_ED25519,           "ED25519" },
+	{ DNSSEC_KEY_ALGORITHM_ED448,             "ED448" },
+	{ DNSSEC_KEY_ALGORITHM_INDIRECT,          "INDIRECT" },
+	{ DNSSEC_KEY_ALGORITHM_PRIVATEDNS,        "PRIVATEDNS" },
+	{ DNSSEC_KEY_ALGORITHM_PRIVATEOID,        "PRIVATEOID" },
+	{ 0, NULL }
+};
+
+_public_
+const knot_lookup_t knot_svcb_param_names[] = {
+	{ KNOT_SVCB_PARAM_MANDATORY, "mandatory" },
+	{ KNOT_SVCB_PARAM_ALPN,      "alpn" },
+	{ KNOT_SVCB_PARAM_NDALPN,    "no-default-alpn" },
+	{ KNOT_SVCB_PARAM_PORT,      "port" },
+	{ KNOT_SVCB_PARAM_IPV4HINT,  "ipv4hint" },
+	{ KNOT_SVCB_PARAM_ECH,       "ech" },
+	{ KNOT_SVCB_PARAM_IPV6HINT,  "ipv6hint" },
+	{ 0, NULL }
+};
diff --git a/src/libknot/codes.h b/src/libknot/codes.h
new file mode 100644
index 0000000..2d3a548
--- /dev/null
+++ b/src/libknot/codes.h
@@ -0,0 +1,60 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Some DNS-related code names.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/lookup.h"
+
+/*!
+ * \brief DNS operation code names.
+ */
+extern const knot_lookup_t knot_opcode_names[];
+
+/*!
+ * \brief DNS reply code names.
+ */
+extern const knot_lookup_t knot_rcode_names[];
+
+/*!
+ * \brief TSIG exceptions to reply code names.
+ */
+extern const knot_lookup_t knot_tsig_rcode_names[];
+
+/*!
+ * \brief EDNS EDE names.
+ */
+extern const knot_lookup_t knot_edns_ede_names[];
+
+/*!
+ * \brief DNSSEC algorithm names.
+ */
+extern const knot_lookup_t knot_dnssec_alg_names[];
+
+/*!
+ * \brief Service binding (SVCB) param types.
+ */
+extern const knot_lookup_t knot_svcb_param_names[];
+
+/*! @} */
diff --git a/src/libknot/consts.h b/src/libknot/consts.h
new file mode 100644
index 0000000..e6041b7
--- /dev/null
+++ b/src/libknot/consts.h
@@ -0,0 +1,163 @@
+/*  Copyright (C) 2023 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Some DNS-related constants.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+/*!
+ * \brief Basic limits for domain names (RFC 1035).
+ */
+#define KNOT_DNAME_MAXLEN      255 /*!< 1-byte maximum. */
+#define KNOT_DNAME_MAXLABELS   127 /*!< 1-char labels. */
+#define KNOT_DNAME_MAXLABELLEN  63 /*!< 2^6 - 1 */
+
+/*!
+ * \brief The longest textual dname representation.
+ *
+ * Binary:  3 x (0x3F + maximum_label) + (0x3D + rest_label) + (0x00)
+ * Textual: 3 x (maximum_label + '.') + (rest_label + '.')
+ *
+ * Each dname label byte takes 4 characters (\\DDD).
+ *
+ * KNOT_DNAME_TXT_MAXLEN = 3 x (63 x 4 + 1) + (61 x 4 + 1)
+ */
+#define KNOT_DNAME_TXT_MAXLEN 1004
+
+/*!
+ * \brief Address family numbers.
+ *
+ * https://www.iana.org/assignments/address-family-numbers/address-family-numbers.xml
+ */
+typedef enum {
+	KNOT_ADDR_FAMILY_IPV4 = 1, /*!< IP version 4. */
+	KNOT_ADDR_FAMILY_IPV6 = 2  /*!< IP version 6. */
+} knot_addr_family_t;
+
+/*!
+ * \brief DNS operation codes (OPCODEs).
+ *
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml
+ */
+typedef enum {
+	KNOT_OPCODE_QUERY  = 0, /*!< Standard query. */
+	KNOT_OPCODE_IQUERY = 1, /*!< Inverse query. */
+	KNOT_OPCODE_STATUS = 2, /*!< Server status request. */
+	KNOT_OPCODE_NOTIFY = 4, /*!< Notify message. */
+	KNOT_OPCODE_UPDATE = 5  /*!< Dynamic update. */
+} knot_opcode_t;
+
+/*!
+ * \brief DNS reply codes (RCODEs).
+ *
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml
+ */
+typedef enum {
+	KNOT_RCODE_NOERROR   =  0, /*!< No error. */
+	KNOT_RCODE_FORMERR   =  1, /*!< Format error. */
+	KNOT_RCODE_SERVFAIL  =  2, /*!< Server failure. */
+	KNOT_RCODE_NXDOMAIN  =  3, /*!< Non-existent domain. */
+	KNOT_RCODE_NOTIMPL   =  4, /*!< Not implemented. */
+	KNOT_RCODE_REFUSED   =  5, /*!< Refused. */
+	KNOT_RCODE_YXDOMAIN  =  6, /*!< Name should not exist. */
+	KNOT_RCODE_YXRRSET   =  7, /*!< RR set should not exist. */
+	KNOT_RCODE_NXRRSET   =  8, /*!< RR set does not exist. */
+	KNOT_RCODE_NOTAUTH   =  9, /*!< Server not authoritative. / Query not authorized. */
+	KNOT_RCODE_NOTZONE   = 10, /*!< Name is not inside zone. */
+	KNOT_RCODE_BADVERS   = 16, /*!< Bad OPT Version. */
+	KNOT_RCODE_BADSIG    = 16, /*!< (TSIG) Signature failure. */
+	KNOT_RCODE_BADKEY    = 17, /*!< (TSIG) Key is not supported. */
+	KNOT_RCODE_BADTIME   = 18, /*!< (TSIG) Signature out of time window. */
+	KNOT_RCODE_BADMODE   = 19, /*!< (TKEY) Bad mode. */
+	KNOT_RCODE_BADNAME   = 20, /*!< (TKEY) Duplicate key name. */
+	KNOT_RCODE_BADALG    = 21, /*!< (TKEY) Algorithm not supported. */
+	KNOT_RCODE_BADTRUNC  = 22, /*!< (TSIG) Bad truncation. */
+	KNOT_RCODE_BADCOOKIE = 23  /*!< Bad/missing server cookie. */
+} knot_rcode_t;
+
+/*!
+ * \brief Extended error codes as in EDNS option #15.
+ *
+ * \note The default -1 value must be filtered out before storing to uint16_t!
+ *
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml#extended-dns-error-codes
+ */
+typedef enum {
+	KNOT_EDNS_EDE_NONE             = -1,
+	KNOT_EDNS_EDE_OTHER            = 0,
+	KNOT_EDNS_EDE_DNSKEY_ALG       = 1,
+	KNOT_EDNS_EDE_DS_DIGEST        = 2,
+	KNOT_EDNS_EDE_STALE            = 3,
+	KNOT_EDNS_EDE_FORGED           = 4,
+	KNOT_EDNS_EDE_INDETERMINATE    = 5,
+	KNOT_EDNS_EDE_BOGUS            = 6,
+	KNOT_EDNS_EDE_SIG_EXPIRED      = 7,
+	KNOT_EDNS_EDE_SIG_NOTYET       = 8,
+	KNOT_EDNS_EDE_DNSKEY_MISS      = 9,
+	KNOT_EDNS_EDE_RRSIG_MISS       = 10,
+	KNOT_EDNS_EDE_DNSKEY_BIT       = 11,
+	KNOT_EDNS_EDE_NSEC_MISS        = 12,
+	KNOT_EDNS_EDE_CACHED_ERR       = 13,
+	KNOT_EDNS_EDE_NOT_READY        = 14,
+	KNOT_EDNS_EDE_BLOCKED          = 15,
+	KNOT_EDNS_EDE_CENSORED         = 16,
+	KNOT_EDNS_EDE_FILTERED         = 17,
+	KNOT_EDNS_EDE_PROHIBITED       = 18,
+	KNOT_EDNS_EDE_STALE_NXD        = 19,
+	KNOT_EDNS_EDE_NOTAUTH          = 20,
+	KNOT_EDNS_EDE_NOTSUP           = 21,
+	KNOT_EDNS_EDE_NREACH_AUTH      = 22,
+	KNOT_EDNS_EDE_NETWORK          = 23,
+	KNOT_EDNS_EDE_INV_DATA         = 24,
+	KNOT_EDNS_EDE_EXPIRED_INV      = 25,
+	KNOT_EDNS_EDE_TOO_EARLY        = 26,
+	KNOT_EDNS_EDE_NSEC3_ITERS      = 27,
+	KNOT_EDNS_EDE_NONCONF_POLICY   = 28,
+	KNOT_EDNS_EDE_SYNTHESIZED      = 29,
+} knot_edns_ede_t;
+
+/*!
+ * \brief DNS packet section identifiers.
+ */
+typedef enum {
+	KNOT_ANSWER       = 0,
+	KNOT_AUTHORITY    = 1,
+	KNOT_ADDITIONAL   = 2
+} knot_section_t;
+
+/*!
+ * \brief Service Binding (SVCB) Parameter Registry
+ *
+ * https://tools.ietf.org/html/draft-ietf-dnsop-svcb-https-05 // FIXME
+ */
+typedef enum {
+	KNOT_SVCB_PARAM_MANDATORY = 0,
+	KNOT_SVCB_PARAM_ALPN      = 1,
+	KNOT_SVCB_PARAM_NDALPN    = 2,
+	KNOT_SVCB_PARAM_PORT      = 3,
+	KNOT_SVCB_PARAM_IPV4HINT  = 4,
+	KNOT_SVCB_PARAM_ECH       = 5,
+	KNOT_SVCB_PARAM_IPV6HINT  = 6,
+} knot_svcb_param_t;
+
+/*! @} */
diff --git a/src/libknot/control/control.c b/src/libknot/control/control.c
new file mode 100644
index 0000000..8656057
--- /dev/null
+++ b/src/libknot/control/control.c
@@ -0,0 +1,568 @@
+/*  Copyright (C) 2023 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 <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libknot/control/control.h"
+#include "libknot/attribute.h"
+#include "libknot/error.h"
+#include "contrib/mempattern.h"
+#include "contrib/net.h"
+#include "contrib/sockaddr.h"
+#include "contrib/string.h"
+#include "contrib/ucw/mempool.h"
+#include "contrib/wire_ctx.h"
+
+/*! Size of the input and output buffers. */
+#ifndef CTL_BUFF_SIZE
+#define CTL_BUFF_SIZE		(256 * 1024)
+#endif
+
+/*! Listen backlog size. */
+#define LISTEN_BACKLOG		5
+
+/*! Default socket operations timeout in milliseconds. */
+#define DEFAULT_TIMEOUT		(30 * 1000)
+
+/*! Accept poll timeout in milliseconds. */
+#define ACCEPT_TIMEOUT		(5 * 1000)
+
+/*! The first data item code. */
+#define DATA_CODE_OFFSET	16
+
+/*! Control context structure. */
+struct knot_ctl {
+	/*! Memory pool context. */
+	knot_mm_t mm;
+	/*! Network operations timeout. */
+	int timeout;
+	/*! Server listening socket. */
+	int listen_sock;
+	/*! Remote server/client socket. */
+	int sock;
+
+	/*! The latter read data. */
+	knot_ctl_data_t data;
+
+	/*! Write wire context. */
+	wire_ctx_t wire_out;
+	/*! Read wire context. */
+	wire_ctx_t wire_in;
+
+	/*! Write buffer. */
+	uint8_t buff_out[CTL_BUFF_SIZE];
+	/*! Read buffer. */
+	uint8_t buff_in[CTL_BUFF_SIZE];
+};
+
+static int type_to_code(knot_ctl_type_t type)
+{
+	switch (type) {
+	case KNOT_CTL_TYPE_END:   return  0;
+	case KNOT_CTL_TYPE_DATA:  return  1;
+	case KNOT_CTL_TYPE_EXTRA: return  2;
+	case KNOT_CTL_TYPE_BLOCK: return  3;
+	default:                  return -1;
+	}
+}
+
+static int code_to_type(uint8_t code)
+{
+	switch (code) {
+	case 0:  return KNOT_CTL_TYPE_END;
+	case 1:  return KNOT_CTL_TYPE_DATA;
+	case 2:  return KNOT_CTL_TYPE_EXTRA;
+	case 3:  return KNOT_CTL_TYPE_BLOCK;
+	default: return -1;
+	}
+}
+
+static bool is_data_type(knot_ctl_type_t type)
+{
+	switch (type) {
+	case KNOT_CTL_TYPE_DATA:
+	case KNOT_CTL_TYPE_EXTRA:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static int idx_to_code(knot_ctl_idx_t idx)
+{
+	if (idx >= KNOT_CTL_IDX__COUNT) {
+		return -1;
+	}
+
+	return DATA_CODE_OFFSET + idx;
+}
+
+static int code_to_idx(uint8_t code)
+{
+	if (code <  DATA_CODE_OFFSET ||
+	    code >= DATA_CODE_OFFSET + KNOT_CTL_IDX__COUNT) {
+		return -1;
+	}
+
+	return code - DATA_CODE_OFFSET;
+}
+
+static void reset_buffers(knot_ctl_t *ctx)
+{
+	ctx->wire_out = wire_ctx_init(ctx->buff_out, CTL_BUFF_SIZE);
+	ctx->wire_in = wire_ctx_init(ctx->buff_in, 0);
+}
+
+static void clean_data(knot_ctl_t *ctx)
+{
+	mp_flush(ctx->mm.ctx);
+	memzero(ctx->data, sizeof(ctx->data));
+}
+
+static void close_sock(int *sock)
+{
+	if (*sock < 0) {
+		return;
+	}
+
+	close(*sock);
+	*sock = -1;
+}
+
+_public_
+knot_ctl_t* knot_ctl_alloc(void)
+{
+	knot_ctl_t *ctx = calloc(1, sizeof(*ctx));
+	if (ctx == NULL) {
+		return NULL;
+	}
+
+	mm_ctx_mempool(&ctx->mm, MM_DEFAULT_BLKSIZE);
+	ctx->timeout = DEFAULT_TIMEOUT;
+	ctx->listen_sock = -1;
+	ctx->sock = -1;
+
+	reset_buffers(ctx);
+
+	return ctx;
+}
+
+_public_
+void knot_ctl_free(knot_ctl_t *ctx)
+{
+	if (ctx == NULL) {
+		return;
+	}
+
+	close_sock(&ctx->listen_sock);
+	close_sock(&ctx->sock);
+
+	clean_data(ctx);
+
+	mp_delete(ctx->mm.ctx);
+
+	memzero(ctx, sizeof(*ctx));
+	free(ctx);
+}
+
+_public_
+void knot_ctl_set_timeout(knot_ctl_t *ctx, int timeout_ms)
+{
+	if (ctx == NULL) {
+		return;
+	}
+
+	ctx->timeout = (timeout_ms > 0) ? timeout_ms : -1;
+}
+
+_public_
+int knot_ctl_bind(knot_ctl_t *ctx, const char *path)
+{
+	if (ctx == NULL || path == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Prepare socket address.
+	struct sockaddr_storage addr;
+	int ret = sockaddr_set(&addr, AF_UNIX, path, 0);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Bind the socket.
+	mode_t mode = S_IWUSR | S_IWGRP;
+	ctx->listen_sock = net_bound_socket(SOCK_STREAM, &addr, 0, mode);
+	if (ctx->listen_sock < 0) {
+		return ctx->listen_sock;
+	}
+
+	// Start listening.
+	if (listen(ctx->listen_sock, LISTEN_BACKLOG) != 0) {
+		close_sock(&ctx->listen_sock);
+		return knot_map_errno();
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_ctl_unbind(knot_ctl_t *ctx)
+{
+	if (ctx == NULL || ctx->listen_sock < 0) {
+		return;
+	}
+
+	// Remove the control socket file.
+	struct sockaddr_storage addr;
+	socklen_t addr_len = sizeof(addr);
+	if (getsockname(ctx->listen_sock, (struct sockaddr *)&addr, &addr_len) == 0) {
+		char addr_str[SOCKADDR_STRLEN] = { 0 };
+		if (sockaddr_tostr(addr_str, sizeof(addr_str), &addr) > 0) {
+			(void)unlink(addr_str);
+		}
+	}
+
+	// Close the listening socket.
+	close_sock(&ctx->listen_sock);
+}
+
+_public_
+int knot_ctl_accept(knot_ctl_t *ctx)
+{
+	if (ctx == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_ctl_close(ctx);
+
+	// Control interface.
+	struct pollfd pfd = { .fd = ctx->listen_sock, .events = POLLIN };
+	int ret = poll(&pfd, 1, ACCEPT_TIMEOUT);
+	if (ret <= 0) {
+		return (ret == 0) ? KNOT_ETIMEOUT : knot_map_errno();
+	}
+
+	int client = net_accept(ctx->listen_sock, NULL);
+	if (client < 0) {
+		return client;
+	}
+
+	ctx->sock = client;
+
+	reset_buffers(ctx);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_ctl_connect(knot_ctl_t *ctx, const char *path)
+{
+	if (ctx == NULL || path == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Prepare socket address.
+	struct sockaddr_storage addr;
+	int ret = sockaddr_set(&addr, AF_UNIX, path, 0);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Connect to socket.
+	ctx->sock = net_connected_socket(SOCK_STREAM, &addr, NULL, false);
+	if (ctx->sock < 0) {
+		return ctx->sock;
+	}
+
+	reset_buffers(ctx);
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_ctl_close(knot_ctl_t *ctx)
+{
+	if (ctx == NULL) {
+		return;
+	}
+
+	close_sock(&ctx->sock);
+}
+
+static int ensure_output(knot_ctl_t *ctx, uint16_t len)
+{
+	wire_ctx_t *w = &ctx->wire_out;
+
+	// Check for enough available room in the output buffer.
+	size_t available = wire_ctx_available(w);
+	if (available >= len) {
+		return KNOT_EOK;
+	}
+
+	// Flush the buffer.
+	int ret = net_stream_send(ctx->sock, w->wire, wire_ctx_offset(w),
+	                          ctx->timeout);
+	if (ret < 0) {
+		return ret;
+	}
+
+	*w = wire_ctx_init(w->wire, CTL_BUFF_SIZE);
+
+	return KNOT_EOK;
+}
+
+static int send_item(knot_ctl_t *ctx, uint8_t code, const char *data, bool flush)
+{
+	wire_ctx_t *w = &ctx->wire_out;
+
+	// Write the control block code.
+	int ret = ensure_output(ctx, sizeof(uint8_t));
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	wire_ctx_write_u8(w, code);
+	if (w->error != KNOT_EOK) {
+		return w->error;
+	}
+
+	// Control block data is optional.
+	if (data != NULL) {
+		// Get the data length.
+		size_t data_len = strlen(data);
+		if (data_len > UINT16_MAX) {
+			return KNOT_ERANGE;
+		}
+
+		// Write the data length.
+		ret = ensure_output(ctx, sizeof(uint16_t));
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		wire_ctx_write_u16(w, data_len);
+		if (w->error != KNOT_EOK) {
+			return w->error;
+		}
+
+		// Write the data.
+		ret = ensure_output(ctx, data_len);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		wire_ctx_write(w, (uint8_t *)data, data_len);
+		if (w->error != KNOT_EOK) {
+			return w->error;
+		}
+	}
+
+	// Send finalized buffer.
+	if (flush && wire_ctx_offset(w) > 0) {
+		ret = net_stream_send(ctx->sock, w->wire, wire_ctx_offset(w),
+		                      ctx->timeout);
+		if (ret < 0) {
+			return ret;
+		}
+
+		*w = wire_ctx_init(w->wire, CTL_BUFF_SIZE);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_ctl_send(knot_ctl_t *ctx, knot_ctl_type_t type, knot_ctl_data_t *data)
+{
+	if (ctx == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Get the type code.
+	int code = type_to_code(type);
+	if (code == -1) {
+		return KNOT_EINVAL;
+	}
+
+	// Send unit type.
+	int ret = send_item(ctx, code, NULL, !is_data_type(type));
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Send unit data.
+	if (is_data_type(type) && data != NULL) {
+		// Send all non-empty data items.
+		for (knot_ctl_idx_t i = 0; i < KNOT_CTL_IDX__COUNT; i++) {
+			const char *value = (*data)[i];
+			if (value == NULL) {
+				continue;
+			}
+
+			ret = send_item(ctx, idx_to_code(i), value, false);
+			if (ret != KNOT_EOK) {
+				return ret;
+			}
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+static int ensure_input(knot_ctl_t *ctx, uint16_t len)
+{
+	wire_ctx_t *w = &ctx->wire_in;
+
+	// Check for enough available room in the input buffer.
+	size_t available = wire_ctx_available(w);
+	if (available >= len) {
+		return KNOT_EOK;
+	}
+
+	// Move unprocessed data to the beginning of the buffer.
+	memmove(w->wire, w->wire + wire_ctx_offset(w), available);
+
+	// Receive enough data.
+	while (available < len) {
+		int ret = net_stream_recv(ctx->sock, w->wire + available,
+		                          CTL_BUFF_SIZE - available,
+		                          ctx->timeout);
+		if (ret < 0) {
+			return ret;
+		}
+		assert(ret > 0);
+		available += ret;
+	}
+
+	ctx->wire_in = wire_ctx_init(w->wire, available);
+
+	return KNOT_EOK;
+}
+
+static int receive_item_code(knot_ctl_t *ctx, uint8_t *code)
+{
+	wire_ctx_t *w = &ctx->wire_in;
+
+	// Read the type.
+	int ret = ensure_input(ctx, sizeof(uint8_t));
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	*code = wire_ctx_read_u8(w);
+	if (w->error != KNOT_EOK) {
+		return w->error;
+	}
+
+	return KNOT_EOK;
+}
+
+static int receive_item_value(knot_ctl_t *ctx, char **value)
+{
+	wire_ctx_t *w = &ctx->wire_in;
+
+	// Read value length.
+	int ret = ensure_input(ctx, sizeof(uint16_t));
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	uint16_t data_len = wire_ctx_read_u16(w);
+	if (w->error != KNOT_EOK) {
+		return w->error;
+	}
+
+	// Read the value.
+	ret = ensure_input(ctx, data_len);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	*value = mm_alloc(&ctx->mm, data_len + 1);
+	if (*value == NULL) {
+		return KNOT_ENOMEM;
+	}
+	wire_ctx_read(w, *value, data_len);
+	if (w->error != KNOT_EOK) {
+		return w->error;
+	}
+	(*value)[data_len] = '\0';
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_ctl_receive(knot_ctl_t *ctx, knot_ctl_type_t *type, knot_ctl_data_t *data)
+{
+	if (ctx == NULL || type == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t *w = &ctx->wire_in;
+
+	// Reset output variables.
+	*type = KNOT_CTL_TYPE_END;
+	clean_data(ctx);
+
+	// Read data units until end of message.
+	bool have_type = false;
+	while (true) {
+		uint8_t code;
+		int ret = receive_item_code(ctx, &code);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+
+		// Process unit type.
+		int current_type = code_to_type(code);
+		if (current_type != -1) {
+			if (have_type) {
+				// Revert parsed type.
+				wire_ctx_skip(w, -sizeof(uint8_t));
+				assert(w->error == KNOT_EOK);
+				break;
+			}
+
+			// Set the unit type.
+			*type = current_type;
+
+			if (is_data_type(current_type)) {
+				have_type = true;
+				continue;
+			} else {
+				break;
+			}
+		}
+
+		// Check for data item code.
+		int idx = code_to_idx(code);
+		if (idx == -1) {
+			return KNOT_EINVAL;
+		}
+
+		// Store the item data value.
+		ret = receive_item_value(ctx, (char **)&ctx->data[idx]);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	// Set the output data.
+	if (data != NULL) {
+		memcpy(*data, ctx->data, sizeof(*data));
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/control/control.h b/src/libknot/control/control.h
new file mode 100644
index 0000000..1d3dcd1
--- /dev/null
+++ b/src/libknot/control/control.h
@@ -0,0 +1,161 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief A server control interface.
+ *
+ * \addtogroup ctl
+ * @{
+ */
+
+#pragma once
+
+/*! Control data item indexes. */
+typedef enum {
+	KNOT_CTL_IDX_CMD = 0, /*!< Control command name. */
+	KNOT_CTL_IDX_FLAGS,   /*!< Control command flags. */
+	KNOT_CTL_IDX_ERROR,   /*!< Error message. */
+	KNOT_CTL_IDX_SECTION, /*!< Configuration section name. */
+	KNOT_CTL_IDX_ITEM,    /*!< Configuration item name. */
+	KNOT_CTL_IDX_ID,      /*!< Configuration item identifier. */
+	KNOT_CTL_IDX_ZONE,    /*!< Zone name. */
+	KNOT_CTL_IDX_OWNER,   /*!< Zone record owner */
+	KNOT_CTL_IDX_TTL,     /*!< Zone record TTL. */
+	KNOT_CTL_IDX_TYPE,    /*!< Zone record type name. */
+	KNOT_CTL_IDX_DATA,    /*!< Configuration item/zone record data. */
+	KNOT_CTL_IDX_FILTER,  /*!< An option or a filter for output data processing. */
+	KNOT_CTL_IDX__COUNT,  /*!< The number of data items. */
+} knot_ctl_idx_t;
+
+/*! Control unit types. */
+typedef enum {
+	KNOT_CTL_TYPE_END,   /*!< End of message, cache flushed. */
+	KNOT_CTL_TYPE_DATA,  /*!< Data unit, cached. */
+	KNOT_CTL_TYPE_EXTRA, /*!< Extra value data unit, cached. */
+	KNOT_CTL_TYPE_BLOCK, /*!< End of data block, cache flushed. */
+} knot_ctl_type_t;
+
+/*! Control input/output string data. */
+typedef const char* knot_ctl_data_t[KNOT_CTL_IDX__COUNT];
+
+/*! A control context. */
+struct knot_ctl;
+typedef struct knot_ctl knot_ctl_t;
+
+/*!
+ * Allocates a control context.
+ *
+ * \return Control context.
+ */
+knot_ctl_t* knot_ctl_alloc(void);
+
+/*!
+ * Deallocates a control context.
+ *
+ * \param[in] ctx  Control context.
+ */
+void knot_ctl_free(knot_ctl_t *ctx);
+
+/*!
+ * Sets the timeout for socket operations.
+ *
+ * Default value is 30 seconds.
+ *
+ * \param[in] ctx         Control context.
+ * \param[in] timeout_ms  Timeout in milliseconds (0 for infinity).
+ */
+void knot_ctl_set_timeout(knot_ctl_t *ctx, int timeout_ms);
+
+/*!
+ * Binds a specified UNIX socket path.
+ *
+ * \note Server operation.
+ *
+ * \param[in] ctx   Control context.
+ * \param[in] path  Control UNIX socket path.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_ctl_bind(knot_ctl_t *ctx, const char *path);
+
+/*!
+ * Unbinds a control socket.
+ *
+ * \note Server operation.
+ *
+ * \param[in] ctx  Control context.
+ */
+void knot_ctl_unbind(knot_ctl_t *ctx);
+
+/*!
+ * Connects to a specified UNIX socket path.
+ *
+ * \note Client operation.
+ *
+ * \param[in] ctx   Control context.
+ * \param[in] path  Control UNIX socket path.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_ctl_connect(knot_ctl_t *ctx, const char *path);
+
+/*!
+ * Waits for an incoming connection.
+ *
+ * \note Server operation.
+ *
+ * \param[in] ctx  Control context.
+ *
+ * \retval KNOT_EOK       if successful.
+ * \retval KNOT_ETIMEOUT  if no connection accepted during ACCEPT_TIMEOUT interval.
+ * \retval KNOT_E*        if error.
+ */
+int knot_ctl_accept(knot_ctl_t *ctx);
+
+/*!
+ * Closes the remote connections.
+ *
+ * \note Applies to both server and client.
+ *
+ * \param[in] ctx  Control context.
+ */
+void knot_ctl_close(knot_ctl_t *ctx);
+
+/*!
+ * Sends one control unit.
+ *
+ * \param[in] ctx   Control context.
+ * \param[in] type  Unit type to send.
+ * \param[in] data  Data unit to send (optional, ignored if non-data type).
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_ctl_send(knot_ctl_t *ctx, knot_ctl_type_t type, knot_ctl_data_t *data);
+
+/*!
+ * Receives one control unit.
+ *
+ * \param[in] ctx    Control context.
+ * \param[out] type  Received unit type.
+ * \param[out] data  Received data unit (optional).
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_ctl_receive(knot_ctl_t *ctx, knot_ctl_type_t *type, knot_ctl_data_t *data);
+
+/*! @} */
diff --git a/src/libknot/cookies.c b/src/libknot/cookies.c
new file mode 100644
index 0000000..e7b3354
--- /dev/null
+++ b/src/libknot/cookies.c
@@ -0,0 +1,170 @@
+/*  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 <stdbool.h>
+
+#include "libknot/attribute.h"
+#include "libknot/cookies.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "contrib/string.h"
+#include "contrib/sockaddr.h"
+#include "contrib/openbsd/siphash.h"
+
+_public_
+int knot_edns_cookie_client_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_params_t *params)
+{
+	if (out == NULL || params == NULL || params->server_addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	SIPHASH_CTX ctx;
+	assert(sizeof(params->secret) == sizeof(SIPHASH_KEY));
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret);
+
+	size_t addr_len = 0;
+	void *addr = sockaddr_raw(params->server_addr, &addr_len);
+	assert(addr);
+	SipHash24_Update(&ctx, addr, addr_len);
+
+	uint64_t hash = SipHash24_End(&ctx);
+	memcpy(out->data, &hash, sizeof(hash));
+	out->len = sizeof(hash);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_cookie_client_check(const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params)
+{
+	if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE) {
+		return KNOT_EINVAL;
+	}
+
+	knot_edns_cookie_t ref;
+	int ret = knot_edns_cookie_client_generate(&ref, params);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	assert(ref.len == KNOT_EDNS_COOKIE_CLNT_SIZE);
+
+	ret = const_time_memcmp(cc->data, ref.data, KNOT_EDNS_COOKIE_CLNT_SIZE);
+	if (ret != 0) {
+		return KNOT_EINVAL;
+	}
+
+	return KNOT_EOK;
+}
+
+static int cookie_server_generate(knot_edns_cookie_t *out,
+                                  const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params)
+{
+	assert(out && params);
+
+	if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE ||
+	    params->client_addr == NULL) {
+		return KNOT_EINVAL;
+	} else if (out->data[0] != KNOT_EDNS_COOKIE_VERSION) {
+		return KNOT_ENOTSUP;
+	}
+
+	SIPHASH_CTX ctx;
+	assert(sizeof(params->secret) == sizeof(SIPHASH_KEY));
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)params->secret);
+
+	SipHash24_Update(&ctx, cc->data, cc->len);
+	SipHash24_Update(&ctx, out->data, out->len);
+
+	size_t addr_len = 0;
+	void *addr = sockaddr_raw(params->client_addr, &addr_len);
+	assert(addr);
+	SipHash24_Update(&ctx, addr, addr_len);
+
+	uint64_t hash = SipHash24_End(&ctx);
+	memcpy(out->data + out->len, &hash, sizeof(hash));
+	out->len += sizeof(hash);
+
+	return KNOT_EOK;
+
+}
+
+_public_
+int knot_edns_cookie_server_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_t *cc,
+                                     const knot_edns_cookie_params_t *params)
+{
+	if (out == NULL || params == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	out->data[0] = params->version;
+	out->data[1] = 0; /* reserved */
+	out->data[2] = 0; /* reserved */
+	out->data[3] = 0; /* reserved */
+	out->len = 4;
+
+	uint32_t now = htobe32(params->timestamp);
+	memcpy(&out->data[out->len], &now, sizeof(now));
+	out->len += sizeof(now);
+
+	return cookie_server_generate(out, cc, params);
+}
+
+_public_
+int knot_edns_cookie_server_check(const knot_edns_cookie_t *sc,
+                                  const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params)
+{
+	if (sc == NULL || sc->len < KNOT_EDNS_COOKIE_SRVR_MIN_SIZE || params == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	uint32_t cookie_time;
+	memcpy(&cookie_time, &sc->data[4], sizeof(cookie_time));
+	cookie_time = be32toh(cookie_time);
+
+	uint32_t min_time = params->timestamp - params->lifetime_before;
+	uint32_t max_time = params->timestamp + params->lifetime_after;
+	if (cookie_time < min_time || cookie_time > max_time) {
+		return KNOT_ERANGE;
+	}
+
+	const int fixed_len = 8;
+	knot_edns_cookie_t ref;
+	memcpy(ref.data, sc->data, fixed_len);
+	ref.len = fixed_len;
+
+	int ret = cookie_server_generate(&ref, cc, params);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	if (sc->len != ref.len) {
+		return KNOT_EINVAL;
+	}
+
+	ret = const_time_memcmp(sc->data + fixed_len, ref.data + fixed_len,
+	                        sc->len - fixed_len);
+	if (ret != 0) {
+		return KNOT_EINVAL;
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/cookies.h b/src/libknot/cookies.h
new file mode 100644
index 0000000..b39ca93
--- /dev/null
+++ b/src/libknot/cookies.h
@@ -0,0 +1,103 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief DNS cookies processing.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <sys/socket.h>
+
+#include "libknot/rrtype/opt.h"
+
+#define KNOT_EDNS_COOKIE_SECRET_SIZE 16
+
+/*!
+ * \brief DNS Cookie parameters needed to generate/check the cookie value.
+ *
+ * \note Client address is not used for the client cookie generation/check.
+ * \note Server address is not used for the server cookie generation/check.
+ */
+typedef struct {
+	uint8_t version;          /*!< Server cookie version to generate. */
+	uint32_t timestamp;       /*!< [s] Server cookie generate or check time. */
+	uint32_t lifetime_before; /*!< [s] Server cookie lifetime in the past. */
+	uint32_t lifetime_after;  /*!< [s] Server cookie lifetime in the future. */
+	const struct sockaddr_storage *client_addr;   /*!< Client socket address. */
+	const struct sockaddr_storage *server_addr;   /*!< Server socket address. */
+	uint8_t secret[KNOT_EDNS_COOKIE_SECRET_SIZE]; /*!< Cookie secret data. */
+} knot_edns_cookie_params_t;
+
+/*!
+ * \brief Generate a client cookie using given parameters.
+ *
+ * \param out     Generated client cookie.
+ * \param params  Client cookie parameters.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ */
+int knot_edns_cookie_client_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_params_t *params);
+
+/*!
+ * \brief Check whether client cookie was generated using given parameters.
+ *
+ * \param cc      Client cookie that should be checked.
+ * \param params  Client cookie parameters.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ */
+int knot_edns_cookie_client_check(const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params);
+
+/*!
+ * \brief Generate a server cookie using given parameters.
+ *
+ * \param out     Generated server cookie.
+ * \param cc      Client cookie parameter.
+ * \param params  Server cookie parameters.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ */
+int knot_edns_cookie_server_generate(knot_edns_cookie_t *out,
+                                     const knot_edns_cookie_t *cc,
+                                     const knot_edns_cookie_params_t *params);
+
+/*!
+ * \brief Check whether server cookie was generated using given parameters.
+ *
+ * \param sc      Server cookie that should be checked.
+ * \param cc      Client cookie parameter.
+ * \param params  Server cookie parameters.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_EINVAL
+ */
+int knot_edns_cookie_server_check(const knot_edns_cookie_t *sc,
+                                  const knot_edns_cookie_t *cc,
+                                  const knot_edns_cookie_params_t *params);
+
+/*! @} */
diff --git a/src/libknot/db/db.h b/src/libknot/db/db.h
new file mode 100644
index 0000000..044a2b9
--- /dev/null
+++ b/src/libknot/db/db.h
@@ -0,0 +1,92 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Structures for binary data handling.
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/mm_ctx.h"
+
+enum {
+	/* Database flags */
+
+	KNOT_DB_RDONLY = 1 << 0, /*!< Read only. */
+	KNOT_DB_SORTED = 1 << 1, /*!< Sorted output. */
+
+	/* Operations */
+
+	KNOT_DB_NOOP   = 1 << 2, /*!< No operation. */
+	KNOT_DB_FIRST  = 1 << 3, /*!< First entry. */
+	KNOT_DB_LAST   = 1 << 4, /*!< Last entry. */
+	KNOT_DB_NEXT   = 1 << 5, /*!< Next entry. */
+	KNOT_DB_PREV   = 1 << 6, /*!< Previous entry. */
+	KNOT_DB_LEQ    = 1 << 7, /*!< Lesser or equal. */
+	KNOT_DB_GEQ    = 1 << 8  /*!< Greater or equal. */
+};
+
+typedef void knot_db_t;
+typedef void knot_db_iter_t;
+
+typedef struct knot_db_val {
+	void *data;
+	size_t len;
+} knot_db_val_t;
+
+typedef struct knot_db_txn {
+	knot_db_t *db;
+	void *txn;
+} knot_db_txn_t;
+
+typedef struct knot_db_api {
+	const char *name;
+
+	/* Context operations */
+
+	int (*init)(knot_db_t **db, knot_mm_t *mm, void *opts);
+	void (*deinit)(knot_db_t *db);
+
+	/* Transactions */
+
+	int (*txn_begin)(knot_db_t *db, knot_db_txn_t *txn, unsigned flags);
+	int (*txn_commit)(knot_db_txn_t *txn);
+	void (*txn_abort)(knot_db_txn_t *txn);
+
+	/* Data access */
+
+	int (*count)(knot_db_txn_t *txn);
+	int (*clear)(knot_db_txn_t *txn);
+	int (*find)(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags);
+	int (*insert)(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags);
+	int (*del)(knot_db_txn_t *txn, knot_db_val_t *key);
+
+	/* Iteration */
+
+	knot_db_iter_t *(*iter_begin)(knot_db_txn_t *txn, unsigned flags);
+	knot_db_iter_t *(*iter_seek)(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags);
+	knot_db_iter_t *(*iter_next)(knot_db_iter_t *iter);
+	int (*iter_key)(knot_db_iter_t *iter, knot_db_val_t *key);
+	int (*iter_val)(knot_db_iter_t *iter, knot_db_val_t *val);
+	void (*iter_finish)(knot_db_iter_t *iter);
+} knot_db_api_t;
+
+/*! @} */
diff --git a/src/libknot/db/db_lmdb.c b/src/libknot/db/db_lmdb.c
new file mode 100644
index 0000000..b5eae09
--- /dev/null
+++ b/src/libknot/db/db_lmdb.c
@@ -0,0 +1,578 @@
+/*  Copyright (C) 2022 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 <stdbool.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/db/db_lmdb.h"
+#include "contrib/files.h"
+#include "contrib/mempattern.h"
+
+#include <lmdb.h>
+
+/* Defines */
+#define LMDB_DIR_MODE   0770
+#define LMDB_FILE_MODE  0660
+
+_public_ const unsigned KNOT_DB_LMDB_NOTLS = MDB_NOTLS;
+_public_ const unsigned KNOT_DB_LMDB_RDONLY = MDB_RDONLY;
+_public_ const unsigned KNOT_DB_LMDB_INTEGERKEY = MDB_INTEGERKEY;
+_public_ const unsigned KNOT_DB_LMDB_NOSYNC = MDB_NOSYNC;
+_public_ const unsigned KNOT_DB_LMDB_WRITEMAP = MDB_WRITEMAP;
+_public_ const unsigned KNOT_DB_LMDB_MAPASYNC = MDB_MAPASYNC;
+_public_ const unsigned KNOT_DB_LMDB_DUPSORT = MDB_DUPSORT;
+
+struct lmdb_env
+{
+	bool shared;
+	MDB_dbi dbi;
+	MDB_env *env;
+	knot_mm_t *pool;
+};
+
+/*!
+ * \brief Convert error code returned by LMDB to Knot DNS error code.
+ *
+ * LMDB defines own error codes but uses additional ones from libc:
+ * - LMDB errors do not conflict with Knot DNS ones.
+ * - Significant LMDB errors are mapped to Knot DNS ones.
+ * - Standard errors are converted to negative value to match Knot DNS mapping.
+ */
+static int lmdb_error_to_knot(int error)
+{
+	if (error == MDB_SUCCESS) {
+		return KNOT_EOK;
+	}
+
+	if (error == MDB_NOTFOUND) {
+		return KNOT_ENOENT;
+	}
+
+	if (error == MDB_TXN_FULL) {
+		return KNOT_ELIMIT;
+	}
+
+	if (error == MDB_MAP_FULL || error == ENOSPC) {
+		return KNOT_ESPACE;
+	}
+
+	return -abs(error);
+}
+
+/*! \brief Set the environment map size.
+ * \note This also sets the maximum database size, see mdb_env_set_mapsize
+ */
+static int set_mapsize(MDB_env *env, size_t map_size)
+{
+	long page_size = sysconf(_SC_PAGESIZE);
+	if (page_size <= 0) {
+		return KNOT_ERROR;
+	}
+
+	/* Round to page size. */
+	map_size = (map_size / page_size) * page_size;
+	int ret = mdb_env_set_mapsize(env, map_size);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+/*! \brief Close the database. */
+static void dbase_close(struct lmdb_env *env)
+{
+	mdb_dbi_close(env->env, env->dbi);
+	if (!env->shared) {
+		mdb_env_close(env->env);
+	}
+}
+
+/*! \brief Open database environment. */
+static int dbase_open_env(struct lmdb_env *env, struct knot_db_lmdb_opts *opts)
+{
+	MDB_env *mdb_env = NULL;
+	int ret = mdb_env_create(&mdb_env);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = make_dir(opts->path, LMDB_DIR_MODE, true);
+	if (ret != KNOT_EOK) {
+		mdb_env_close(mdb_env);
+		return ret;
+	}
+
+	ret = set_mapsize(mdb_env, opts->mapsize);
+	if (ret != KNOT_EOK) {
+		mdb_env_close(mdb_env);
+		return ret;
+	}
+
+	ret = mdb_env_set_maxdbs(mdb_env, opts->maxdbs);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_env_set_maxreaders(mdb_env, opts->maxreaders);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+#ifdef __OpenBSD__
+	/*
+	 * Enforce that MDB_WRITEMAP is set.
+	 *
+	 * MDB assumes a unified buffer cache.
+	 *
+	 * See https://www.openldap.org/pub/hyc/mdm-paper.pdf section 3.1,
+	 * references 17, 18, and 19.
+	 *
+	 * From Howard Chu: "This requirement can be relaxed in the
+	 * current version of the library. If you create the environment
+	 * with the MDB_WRITEMAP option then all reads and writes are
+	 * performed using mmap, so the file buffer cache is irrelevant.
+	 * Of course then you lose the protection that the read-only
+	 * map offers."
+	 */
+	opts->flags.env |= MDB_WRITEMAP;
+#endif
+
+	ret = mdb_env_open(mdb_env, opts->path, opts->flags.env, LMDB_FILE_MODE);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(mdb_env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	/* Keep the environment pointer. */
+	env->env = mdb_env;
+
+	return KNOT_EOK;
+}
+
+static int dbase_open(struct lmdb_env *env, struct knot_db_lmdb_opts *opts)
+{
+	unsigned flags = 0;
+	if (opts->flags.env & KNOT_DB_LMDB_RDONLY) {
+		flags = MDB_RDONLY;
+	}
+
+	/* Open the database. */
+	MDB_txn *txn = NULL;
+	int ret = mdb_txn_begin(env->env, NULL, flags, &txn);
+	if (ret == MDB_READERS_FULL) {
+		int cleared = 0;
+		ret = mdb_reader_check(env->env, &cleared);
+		if (ret == MDB_SUCCESS) {
+			ret = mdb_txn_begin(env->env, NULL, flags, &txn);
+		}
+	}
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_dbi_open(txn, opts->dbname, opts->flags.db | MDB_CREATE, &env->dbi);
+	if (ret != MDB_SUCCESS) {
+		mdb_txn_abort(txn);
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	ret = mdb_txn_commit(txn);
+	if (ret != MDB_SUCCESS) {
+		mdb_env_close(env->env);
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int init(knot_db_t **db_ptr, knot_mm_t *mm, void *arg)
+{
+	if (db_ptr == NULL || arg == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct lmdb_env *env = mm_alloc(mm, sizeof(struct lmdb_env));
+	if (env == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	memset(env, 0, sizeof(struct lmdb_env));
+	env->pool = mm;
+
+	/* Open new environment. */
+	struct lmdb_env *old_env = *db_ptr;
+	if (old_env == NULL) {
+		int ret = dbase_open_env(env, (struct knot_db_lmdb_opts *)arg);
+		if (ret != KNOT_EOK) {
+			mm_free(mm, env);
+			return ret;
+		}
+	} else {
+		/* Shared environment, this instance just owns the DBI. */
+		env->env = old_env->env;
+		env->shared = true;
+	}
+
+	/* Open the database. */
+	int ret = dbase_open(env, (struct knot_db_lmdb_opts *)arg);
+	if (ret != KNOT_EOK) {
+		mm_free(mm, env);
+		return ret;
+	}
+
+	/* Store the new environment. */
+	*db_ptr = env;
+
+	return KNOT_EOK;
+}
+
+static void deinit(knot_db_t *db)
+{
+	if (db) {
+		struct lmdb_env *env = db;
+
+		dbase_close(env);
+		mm_free(env->pool, env);
+	}
+}
+
+_public_
+int knot_db_lmdb_txn_begin(knot_db_t *db, knot_db_txn_t *txn, knot_db_txn_t *parent,
+                           unsigned flags)
+{
+	txn->db = db;
+	txn->txn = NULL;
+
+	unsigned txn_flags = 0;
+	if (flags & KNOT_DB_RDONLY) {
+		txn_flags |= MDB_RDONLY;
+	}
+
+	MDB_txn *parent_txn = (parent != NULL) ? (MDB_txn *)parent->txn : NULL;
+
+	struct lmdb_env *env = db;
+	int ret = mdb_txn_begin(env->env, parent_txn, txn_flags, (MDB_txn **)&txn->txn);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int txn_begin(knot_db_t *db, knot_db_txn_t *txn, unsigned flags)
+{
+	return knot_db_lmdb_txn_begin(db, txn, NULL, flags);
+}
+
+static int txn_commit(knot_db_txn_t *txn)
+{
+	int ret = mdb_txn_commit((MDB_txn *)txn->txn);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static void txn_abort(knot_db_txn_t *txn)
+{
+	mdb_txn_abort((MDB_txn *)txn->txn);
+}
+
+static int count(knot_db_txn_t *txn)
+{
+	struct lmdb_env *env = txn->db;
+
+	MDB_stat stat;
+	int ret = mdb_stat(txn->txn, env->dbi, &stat);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return stat.ms_entries;
+}
+
+static int clear(knot_db_txn_t *txn)
+{
+	struct lmdb_env *env = txn->db;
+
+	int ret = mdb_drop(txn->txn, env->dbi, 0);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static knot_db_iter_t *iter_set(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_cursor_op op = MDB_SET;
+	switch(flags) {
+	case KNOT_DB_NOOP:  return cursor;
+	case KNOT_DB_FIRST: op = MDB_FIRST; break;
+	case KNOT_DB_LAST:  op = MDB_LAST;  break;
+	case KNOT_DB_NEXT:  op = MDB_NEXT; break;
+	case KNOT_DB_PREV:  op = MDB_PREV; break;
+	case KNOT_DB_LEQ:
+	case KNOT_DB_GEQ:   op = MDB_SET_RANGE; break;
+	default: break;
+	}
+
+	MDB_val db_key = { 0, NULL };
+	if (key) {
+		db_key.mv_data = key->data;
+		db_key.mv_size = key->len;
+	}
+	MDB_val unused_key = { 0, NULL }, unused_val = { 0, NULL };
+
+	int ret = mdb_cursor_get(cursor, key ? &db_key : &unused_key, &unused_val, op);
+
+	/* LEQ is not supported in LMDB, workaround using GEQ. */
+	if (flags == KNOT_DB_LEQ && key) {
+		/* Searched key is after the last key. */
+		if (ret != MDB_SUCCESS) {
+			return iter_set(iter, NULL, KNOT_DB_LAST);
+		}
+		/* If the searched key != matched, get previous. */
+		if ((key->len != db_key.mv_size) ||
+		    (memcmp(key->data, db_key.mv_data, key->len) != 0)) {
+			return iter_set(iter, NULL, KNOT_DB_PREV);
+		}
+	}
+
+	if (ret != MDB_SUCCESS) {
+		mdb_cursor_close(cursor);
+		return NULL;
+	}
+
+	return cursor;
+}
+
+static knot_db_iter_t *iter_begin(knot_db_txn_t *txn, unsigned flags)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_cursor *cursor = NULL;
+
+	int ret = mdb_cursor_open(txn->txn, env->dbi, &cursor);
+	if (ret != MDB_SUCCESS) {
+		return NULL;
+	}
+
+	/* Clear sorted flag, as it's always sorted. */
+	flags &= ~KNOT_DB_SORTED;
+
+	return iter_set(cursor, NULL, (flags == 0) ? KNOT_DB_FIRST : flags);
+}
+
+static knot_db_iter_t *iter_next(knot_db_iter_t *iter)
+{
+	return iter_set(iter, NULL, KNOT_DB_NEXT);
+}
+
+_public_
+int knot_db_lmdb_iter_del(knot_db_iter_t *iter)
+{
+	MDB_cursor *cursor = iter;
+
+	int ret = mdb_cursor_del(cursor, 0);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+static int iter_key(knot_db_iter_t *iter, knot_db_val_t *key)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_val mdb_key, mdb_val;
+	int ret = mdb_cursor_get(cursor, &mdb_key, &mdb_val, MDB_GET_CURRENT);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	key->data = mdb_key.mv_data;
+	key->len  = mdb_key.mv_size;
+	return KNOT_EOK;
+}
+
+static int iter_val(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	MDB_cursor *cursor = iter;
+
+	MDB_val mdb_key, mdb_val;
+	int ret = mdb_cursor_get(cursor, &mdb_key, &mdb_val, MDB_GET_CURRENT);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	val->data = mdb_val.mv_data;
+	val->len  = mdb_val.mv_size;
+	return KNOT_EOK;
+}
+
+static void iter_finish(knot_db_iter_t *iter)
+{
+	if (iter == NULL) {
+		return;
+	}
+
+	MDB_cursor *cursor = iter;
+	mdb_cursor_close(cursor);
+}
+
+static int find(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	knot_db_iter_t *iter = iter_begin(txn, KNOT_DB_NOOP);
+	if (iter == NULL) {
+		return KNOT_ERROR;
+	}
+
+	int ret = KNOT_EOK;
+	if (iter_set(iter, key, flags) == NULL) {
+		return KNOT_ENOENT;
+	} else {
+		ret = iter_val(iter, val);
+	}
+
+	iter_finish(iter);
+	return ret;
+}
+
+static int insert(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	struct lmdb_env *env = txn->db;
+
+	MDB_val db_key = { key->len, key->data };
+	MDB_val data = { val->len, val->data };
+
+	/* Reserve if only size is declared. */
+	unsigned mdb_flags = 0;
+	if (val->len > 0 && val->data == NULL) {
+		mdb_flags |= MDB_RESERVE;
+	}
+
+	int ret = mdb_put(txn->txn, env->dbi, &db_key, &data, mdb_flags);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	/* Update the result. */
+	val->data = data.mv_data;
+	val->len = data.mv_size;
+
+	return KNOT_EOK;
+}
+
+static int del(knot_db_txn_t *txn, knot_db_val_t *key)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_val db_key = { key->len, key->data };
+
+	int ret = mdb_del(txn->txn, env->dbi, &db_key, NULL);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_db_lmdb_del_exact(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val)
+{
+	struct lmdb_env *env = txn->db;
+	MDB_val db_key = { key->len, key->data };
+	MDB_val data = { val->len, val->data };
+
+	int ret = mdb_del(txn->txn, env->dbi, &db_key, &data);
+	if (ret != MDB_SUCCESS) {
+		return lmdb_error_to_knot(ret);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+size_t knot_db_lmdb_get_mapsize(knot_db_t *db)
+{
+	struct lmdb_env *env = db;
+	MDB_envinfo info;
+	if (mdb_env_info(env->env, &info) != MDB_SUCCESS) {
+		return 0;
+	}
+
+	return info.me_mapsize;
+}
+
+// you should SUM all the usages of DBs sharing one mapsize
+_public_
+size_t knot_db_lmdb_get_usage(knot_db_t *db)
+{
+	struct lmdb_env *env = db;
+	knot_db_txn_t txn;
+	knot_db_lmdb_txn_begin(db, &txn, NULL, KNOT_DB_RDONLY);
+	MDB_stat st;
+	if (mdb_stat(txn.txn, env->dbi, &st) != MDB_SUCCESS) {
+		txn_abort(&txn);
+		return 0;
+	}
+	txn_abort(&txn);
+
+	size_t pgs_used = st.ms_branch_pages + st.ms_leaf_pages + st.ms_overflow_pages;
+
+	return (pgs_used * st.ms_psize);
+}
+
+_public_
+const char *knot_db_lmdb_get_path(knot_db_t *db)
+{
+	struct lmdb_env *env = db;
+
+	static const char *path;
+	if (mdb_env_get_path(env->env, &path) == 0) {
+		return path;
+	} else {
+		return "";
+	}
+}
+
+_public_
+const knot_db_api_t *knot_db_lmdb_api(void)
+{
+	static const knot_db_api_t api = {
+		"lmdb",
+		init, deinit,
+		txn_begin, txn_commit, txn_abort,
+		count, clear, find, insert, del,
+		iter_begin, iter_set, iter_next, iter_key, iter_val, iter_finish
+	};
+
+	return &api;
+}
diff --git a/src/libknot/db/db_lmdb.h b/src/libknot/db/db_lmdb.h
new file mode 100644
index 0000000..ef8e664
--- /dev/null
+++ b/src/libknot/db/db_lmdb.h
@@ -0,0 +1,73 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/db/db.h"
+
+/* Defines. */
+#define KNOT_DB_LMDB_MAPSIZE    (100 * 1024 * 1024)
+
+/* LMDB specific flags. */
+extern const unsigned KNOT_DB_LMDB_NOTLS;
+extern const unsigned KNOT_DB_LMDB_RDONLY;
+extern const unsigned KNOT_DB_LMDB_INTEGERKEY;
+extern const unsigned KNOT_DB_LMDB_NOSYNC;
+extern const unsigned KNOT_DB_LMDB_WRITEMAP;
+extern const unsigned KNOT_DB_LMDB_MAPASYNC;
+extern const unsigned KNOT_DB_LMDB_DUPSORT;
+
+/* Native options. */
+struct knot_db_lmdb_opts {
+	const char *path;     /*!< Database environment path. */
+	const char *dbname;   /*!< Database name (or NULL). */
+	size_t mapsize;       /*!< Environment map size. */
+	unsigned maxdbs;      /*!< Maximum number of databases in the env. */
+	unsigned maxreaders;  /*!< Maximum number of concurrent readers */
+	struct {
+		unsigned env; /*!< Environment flags. */
+		unsigned db;  /*!< Database flags. */
+	} flags;
+};
+
+/* Default options. */
+#define KNOT_DB_LMDB_OPTS_INITIALIZER { \
+	NULL, NULL, \
+	KNOT_DB_LMDB_MAPSIZE, \
+	0, \
+	126, /* = contrib/lmdb/mdb.c DEFAULT_READERS */ \
+	{ 0, 0 } \
+}
+
+const knot_db_api_t *knot_db_lmdb_api(void);
+
+/* LMDB specific operations. */
+int knot_db_lmdb_del_exact(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val);
+int knot_db_lmdb_txn_begin(knot_db_t *db, knot_db_txn_t *txn, knot_db_txn_t *parent,
+                           unsigned flags);
+int knot_db_lmdb_iter_del(knot_db_iter_t *iter);
+size_t knot_db_lmdb_get_mapsize(knot_db_t *db);
+size_t knot_db_lmdb_get_usage(knot_db_t *db);
+const char *knot_db_lmdb_get_path(knot_db_t *db);
+
+/*! @} */
diff --git a/src/libknot/db/db_trie.c b/src/libknot/db/db_trie.c
new file mode 100644
index 0000000..1bdba8b
--- /dev/null
+++ b/src/libknot/db/db_trie.c
@@ -0,0 +1,176 @@
+/*  Copyright (C) 2021 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 "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/db/db_trie.h"
+#include "contrib/qp-trie/trie.h"
+#include "contrib/mempattern.h"
+
+static int init(knot_db_t **db, knot_mm_t *mm, void *arg)
+{
+	if (db == NULL || arg == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	_unused_ struct knot_db_trie_opts *opts = arg;
+	trie_t *trie = trie_create(mm);
+	if (!trie) {
+		return KNOT_ENOMEM;
+	}
+
+	*db = trie;
+
+	return KNOT_EOK;
+}
+
+static void deinit(knot_db_t *db)
+{
+	trie_free((trie_t *)db);
+}
+
+static int txn_begin(knot_db_t *db, knot_db_txn_t *txn, unsigned flags)
+{
+	txn->txn = (void *)(size_t)flags;
+	txn->db  = db;
+	return KNOT_EOK; /* N/A */
+}
+
+static int txn_commit(knot_db_txn_t *txn)
+{
+	return KNOT_EOK;
+}
+
+static void txn_abort(knot_db_txn_t *txn)
+{
+}
+
+static int count(knot_db_txn_t *txn)
+{
+	return trie_weight((trie_t *)txn->db);
+}
+
+static int clear(knot_db_txn_t *txn)
+{
+	trie_clear((trie_t *)txn->db);
+
+	return KNOT_EOK;
+}
+
+static int find(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	trie_val_t *ret = trie_get_try((trie_t *)txn->db, key->data, key->len);
+	if (ret == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	val->data = *ret;
+	val->len  = sizeof(trie_val_t); /* Trie doesn't support storing length. */
+	return KNOT_EOK;
+}
+
+static int insert(knot_db_txn_t *txn, knot_db_val_t *key, knot_db_val_t *val, unsigned flags)
+{
+	/* No flags supported. */
+	if (flags != 0) {
+		return KNOT_ENOTSUP;
+	}
+
+	trie_val_t *ret = trie_get_ins((trie_t *)txn->db, key->data, key->len);
+	if (ret == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	*ret = val->data;
+	return KNOT_EOK;
+}
+
+static int del(knot_db_txn_t *txn, knot_db_val_t *key)
+{
+	return trie_del((trie_t *)txn->db, key->data, key->len, NULL);
+}
+
+static knot_db_iter_t *iter_begin(knot_db_txn_t *txn, unsigned flags)
+{
+	flags &= ~KNOT_DB_SORTED;
+
+	/* No operations other than begin are supported right now. */
+	if (flags != 0) {
+		return NULL;
+	}
+
+	return trie_it_begin((trie_t *)txn->db);
+}
+
+static knot_db_iter_t *iter_seek(knot_db_iter_t *iter, knot_db_val_t *key, unsigned flags)
+{
+	assert(0);
+	return NULL; /* ENOTSUP */
+}
+
+static knot_db_iter_t *iter_next(knot_db_iter_t *iter)
+{
+	trie_it_next((trie_it_t *)iter);
+	if (trie_it_finished((trie_it_t *)iter)) {
+		trie_it_free((trie_it_t *)iter);
+		return NULL;
+	}
+
+	return iter;
+}
+
+static int iter_key(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	val->data = (void *)trie_it_key((trie_it_t *)iter, &val->len);
+	if (val->data == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	return KNOT_EOK;
+}
+
+static int iter_val(knot_db_iter_t *iter, knot_db_val_t *val)
+{
+	trie_val_t *ret = trie_it_val((trie_it_t *)iter);
+	if (ret == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	val->data = *ret;
+	val->len  = sizeof(trie_val_t);
+	return KNOT_EOK;
+}
+
+static void iter_finish(knot_db_iter_t *iter)
+{
+	trie_it_free((trie_it_t *)iter);
+}
+
+_public_
+const knot_db_api_t *knot_db_trie_api(void)
+{
+	static const knot_db_api_t api = {
+		"trie",
+		init, deinit,
+		txn_begin, txn_commit, txn_abort,
+		count, clear, find, insert, del,
+		iter_begin, iter_seek, iter_next, iter_key, iter_val, iter_finish
+	};
+
+	return &api;
+}
diff --git a/src/libknot/db/db_trie.h b/src/libknot/db/db_trie.h
new file mode 100644
index 0000000..fee4722
--- /dev/null
+++ b/src/libknot/db/db_trie.h
@@ -0,0 +1,40 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup db
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/db/db.h"
+
+/* Native options. */
+struct knot_db_trie_opts {
+	unsigned unused;
+};
+
+/* Default options. */
+#define KNOT_DB_TRIE_OPTS_INITIALIZER { \
+	0 \
+}
+
+const knot_db_api_t *knot_db_trie_api(void);
+
+/*! @} */
diff --git a/src/libknot/descriptor.c b/src/libknot/descriptor.c
new file mode 100644
index 0000000..5ff2714
--- /dev/null
+++ b/src/libknot/descriptor.c
@@ -0,0 +1,425 @@
+/*  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 <stdio.h>
+#include <stdlib.h>
+#include <strings.h>
+
+#include "libknot/attribute.h"
+#include "libknot/descriptor.h"
+
+/*!
+ * \brief Table with DNS classes.
+ */
+static const char* dns_classes[] = {
+	[KNOT_CLASS_IN]   = "IN",
+	[KNOT_CLASS_CH]   = "CH",
+	[KNOT_CLASS_NONE] = "NONE",
+	[KNOT_CLASS_ANY]  = "ANY"
+};
+
+/*!
+ * \brief RR type descriptors.
+ */
+static const knot_rdata_descriptor_t rdata_descriptors[] = {
+	[0]                      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, NULL },
+	[KNOT_RRTYPE_A]          = { { 4, KNOT_RDATA_WF_END }, "A" },
+	[KNOT_RRTYPE_NS]         = { { KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "NS" },
+	[KNOT_RRTYPE_CNAME]      = { { KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "CNAME" },
+	[KNOT_RRTYPE_SOA]        = { { KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               20, KNOT_RDATA_WF_END }, "SOA" },
+	[KNOT_RRTYPE_NULL]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "NULL" },
+	[KNOT_RRTYPE_PTR]        = { { KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "PTR" },
+	[KNOT_RRTYPE_HINFO]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "HINFO" },
+	[KNOT_RRTYPE_MINFO]      = { { KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MINFO" },
+	[KNOT_RRTYPE_MX]         = { { 2, KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MX" },
+	[KNOT_RRTYPE_TXT]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "TXT" },
+	[KNOT_RRTYPE_RP]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "RP" },
+	[KNOT_RRTYPE_AFSDB]      = { { 2, KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "AFSDB" },
+	[KNOT_RRTYPE_RT]         = { { 2, KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "RT" },
+	[KNOT_RRTYPE_SIG]        = { { 18, KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "SIG" },
+	[KNOT_RRTYPE_KEY]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "KEY" },
+	[KNOT_RRTYPE_AAAA]       = { { 16, KNOT_RDATA_WF_END }, "AAAA" },
+	[KNOT_RRTYPE_LOC]        = { { 16, KNOT_RDATA_WF_END }, "LOC" },
+	[KNOT_RRTYPE_SRV]        = { { 6, KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "SRV" },
+	[KNOT_RRTYPE_NAPTR]      = { { KNOT_RDATA_WF_NAPTR_HEADER,
+	                               KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "NAPTR" },
+	[KNOT_RRTYPE_KX]         = { { 2, KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_END }, "KX" },
+	[KNOT_RRTYPE_CERT]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "CERT" },
+	[KNOT_RRTYPE_DNAME]      = { { KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_END }, "DNAME" },
+	[KNOT_RRTYPE_OPT]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "OPT" },
+	[KNOT_RRTYPE_APL]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "APL" },
+	[KNOT_RRTYPE_DS]         = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "DS" },
+	[KNOT_RRTYPE_SSHFP]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "SSHFP" },
+	[KNOT_RRTYPE_IPSECKEY]   = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "IPSECKEY" },
+	[KNOT_RRTYPE_RRSIG]      = { { 18, KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "RRSIG" },
+	[KNOT_RRTYPE_NSEC]       = { { KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "NSEC" },
+	[KNOT_RRTYPE_DNSKEY]     = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "DNSKEY" },
+	[KNOT_RRTYPE_DHCID]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "DHCID" },
+	[KNOT_RRTYPE_NSEC3]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "NSEC3" },
+	[KNOT_RRTYPE_NSEC3PARAM] = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "NSEC3PARAM" },
+	[KNOT_RRTYPE_TLSA]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "TLSA" },
+	[KNOT_RRTYPE_SMIMEA]     = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "SMIMEA" },
+	[KNOT_RRTYPE_CDS]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "CDS" },
+	[KNOT_RRTYPE_CDNSKEY]    = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "CDNSKEY" },
+	[KNOT_RRTYPE_OPENPGPKEY] = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "OPENPGPKEY" },
+	[KNOT_RRTYPE_CSYNC]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "CSYNC" },
+	[KNOT_RRTYPE_ZONEMD]     = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "ZONEMD" },
+	[KNOT_RRTYPE_SVCB]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "SVCB" },
+	[KNOT_RRTYPE_HTTPS]      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "HTTPS" },
+	[KNOT_RRTYPE_SPF]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "SPF" },
+	[KNOT_RRTYPE_NID]        = { { 10, KNOT_RDATA_WF_END }, "NID" },
+	[KNOT_RRTYPE_L32]        = { { 6, KNOT_RDATA_WF_END }, "L32" },
+	[KNOT_RRTYPE_L64]        = { { 10, KNOT_RDATA_WF_END }, "L64" },
+	[KNOT_RRTYPE_LP]         = { { 2, KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_END }, "LP" },
+	[KNOT_RRTYPE_EUI48]      = { { 6, KNOT_RDATA_WF_END }, "EUI48" },
+	[KNOT_RRTYPE_EUI64]      = { { 8, KNOT_RDATA_WF_END }, "EUI64" },
+	[KNOT_RRTYPE_TKEY]       = { { KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "TKEY" },
+	[KNOT_RRTYPE_TSIG]       = { { KNOT_RDATA_WF_FIXED_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "TSIG" },
+	[KNOT_RRTYPE_IXFR]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "IXFR" },
+	[KNOT_RRTYPE_AXFR]       = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "AXFR" },
+	[KNOT_RRTYPE_ANY]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "ANY" },
+	[KNOT_RRTYPE_URI]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "URI" },
+	[KNOT_RRTYPE_CAA]        = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "CAA" },
+};
+
+#define MAX_RRTYPE sizeof(rdata_descriptors) / sizeof(knot_rdata_descriptor_t) - 1
+
+/*!
+ * \brief Some (OBSOLETE) RR type descriptors.
+ */
+static const knot_rdata_descriptor_t obsolete_rdata_descriptors[] = {
+	[0]                      = { { KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, NULL },
+	[KNOT_RRTYPE_MD]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MD" },
+	[KNOT_RRTYPE_MF]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MF" },
+	[KNOT_RRTYPE_MB]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MB" },
+	[KNOT_RRTYPE_MG]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MG" },
+	[KNOT_RRTYPE_MR]         = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "MR" },
+	[KNOT_RRTYPE_PX]         = { { 2, KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_END }, "PX" },
+	[KNOT_RRTYPE_NXT]        = { { KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	                               KNOT_RDATA_WF_REMAINDER,
+	                               KNOT_RDATA_WF_END }, "NXT" },
+};
+
+_public_
+const knot_rdata_descriptor_t *knot_get_rdata_descriptor(const uint16_t type)
+{
+	if (type <= MAX_RRTYPE && rdata_descriptors[type].type_name != NULL) {
+		return &rdata_descriptors[type];
+	} else {
+		return &rdata_descriptors[0];
+	}
+}
+
+_public_
+const knot_rdata_descriptor_t *knot_get_obsolete_rdata_descriptor(const uint16_t type)
+{
+	if (type <= KNOT_RRTYPE_NXT &&
+	    obsolete_rdata_descriptors[type].type_name != NULL) {
+		return &obsolete_rdata_descriptors[type];
+	} else {
+		return &obsolete_rdata_descriptors[0];
+	}
+}
+
+_public_
+int knot_rrtype_to_string(const uint16_t rrtype,
+                          char           *out,
+                          const size_t   out_len)
+{
+	if (out == NULL) {
+		return -1;
+	}
+
+	int ret;
+
+	const knot_rdata_descriptor_t *descr = knot_get_rdata_descriptor(rrtype);
+
+	if (descr->type_name != NULL) {
+		ret = snprintf(out, out_len, "%s", descr->type_name);
+	} else {
+		ret = snprintf(out, out_len, "TYPE%u", rrtype);
+	}
+
+	if (ret <= 0 || (size_t)ret >= out_len) {
+		return -1;
+	} else {
+		return ret;
+	}
+}
+
+_public_
+int knot_rrtype_from_string(const char *name, uint16_t *num)
+{
+	if (name == NULL || num == NULL) {
+		return -1;
+	}
+
+	int i;
+	char *end;
+	unsigned long n;
+
+	// Try to find name in descriptors table.
+	for (i = 0; i <= MAX_RRTYPE; i++) {
+		if (rdata_descriptors[i].type_name != NULL &&
+		    strcasecmp(rdata_descriptors[i].type_name, name) == 0) {
+			*num = i;
+			return 0;
+		}
+	}
+
+	// Type name must begin with TYPE.
+	if (strncasecmp(name, "TYPE", 4) != 0) {
+		return -1;
+	} else {
+		name += 4;
+	}
+
+	// The rest must be a number.
+	n = strtoul(name, &end, 10);
+	if (end == name || *end != '\0' || n > UINT16_MAX) {
+		return -1;
+	}
+
+	*num = n;
+	return 0;
+}
+
+_public_
+int knot_rrclass_to_string(const uint16_t rrclass,
+                           char           *out,
+                           const size_t   out_len)
+{
+	if (out == NULL) {
+		return -1;
+	}
+
+	int ret;
+
+	if (rrclass <= KNOT_CLASS_ANY && dns_classes[rrclass] != NULL) {
+		ret = snprintf(out, out_len, "%s", dns_classes[rrclass]);
+	} else {
+		ret = snprintf(out, out_len, "CLASS%u", rrclass);
+	}
+
+	if (ret <= 0 || (size_t)ret >= out_len) {
+		return -1;
+	} else {
+		return ret;
+	}
+}
+
+_public_
+int knot_rrclass_from_string(const char *name, uint16_t *num)
+{
+	if (name == NULL || num == NULL) {
+		return -1;
+	}
+
+	int i;
+	char *end;
+	unsigned long n;
+
+	// Try to find the name in classes table.
+	for (i = 0; i <= KNOT_CLASS_ANY; i++) {
+		if (dns_classes[i] != NULL &&
+		    strcasecmp(dns_classes[i], name) == 0) {
+			*num = i;
+			return 0;
+		}
+	}
+
+	// Class name must begin with CLASS.
+	if (strncasecmp(name, "CLASS", 5) != 0) {
+		return -1;
+	} else {
+		name += 5;
+	}
+
+	// The rest must be a number.
+	n = strtoul(name, &end, 10);
+	if (end == name || *end != '\0' || n > UINT16_MAX) {
+		return -1;
+	}
+
+	*num = n;
+	return 0;
+}
+
+_public_
+int knot_rrtype_is_metatype(const uint16_t type)
+{
+	return type == KNOT_RRTYPE_SIG  ||
+	       type == KNOT_RRTYPE_OPT  ||
+	       type == KNOT_RRTYPE_TKEY ||
+	       type == KNOT_RRTYPE_TSIG ||
+	       type == KNOT_RRTYPE_IXFR ||
+	       type == KNOT_RRTYPE_AXFR ||
+	       type == KNOT_RRTYPE_ANY;
+}
+
+_public_
+int knot_rrtype_is_dnssec(const uint16_t type)
+{
+	return type == KNOT_RRTYPE_DNSKEY     ||
+	       type == KNOT_RRTYPE_RRSIG      ||
+	       type == KNOT_RRTYPE_NSEC       ||
+	       type == KNOT_RRTYPE_NSEC3      ||
+	       type == KNOT_RRTYPE_NSEC3PARAM ||
+	       type == KNOT_RRTYPE_CDNSKEY    ||
+	       type == KNOT_RRTYPE_CDS;
+}
+
+_public_
+int knot_rrtype_additional_needed(const uint16_t type)
+{
+	return type == KNOT_RRTYPE_NS ||
+	       type == KNOT_RRTYPE_MX ||
+	       type == KNOT_RRTYPE_SRV ||
+	       type == KNOT_RRTYPE_SVCB ||
+	       type == KNOT_RRTYPE_HTTPS;
+}
+
+_public_
+bool knot_rrtype_should_be_lowercased(const uint16_t type)
+{
+	return type == KNOT_RRTYPE_NS    ||
+	       type == KNOT_RRTYPE_MD    ||
+	       type == KNOT_RRTYPE_MF    ||
+	       type == KNOT_RRTYPE_CNAME ||
+	       type == KNOT_RRTYPE_SOA   ||
+	       type == KNOT_RRTYPE_MB    ||
+	       type == KNOT_RRTYPE_MG    ||
+	       type == KNOT_RRTYPE_MR    ||
+	       type == KNOT_RRTYPE_PTR   ||
+	       type == KNOT_RRTYPE_MINFO ||
+	       type == KNOT_RRTYPE_MX    ||
+	       type == KNOT_RRTYPE_RP    ||
+	       type == KNOT_RRTYPE_AFSDB ||
+	       type == KNOT_RRTYPE_RT    ||
+	       type == KNOT_RRTYPE_SIG   ||
+	       type == KNOT_RRTYPE_PX    ||
+	       type == KNOT_RRTYPE_NXT   ||
+	       type == KNOT_RRTYPE_NAPTR ||
+	       type == KNOT_RRTYPE_KX    ||
+	       type == KNOT_RRTYPE_SRV   ||
+	       type == KNOT_RRTYPE_DNAME ||
+	       type == KNOT_RRTYPE_RRSIG;
+}
+
+_public_
+int knot_opt_code_to_string(const uint16_t code, char *out, const size_t out_len)
+{
+	if (out == NULL) {
+		return -1;
+	}
+
+	const char *name = NULL;
+
+	switch (code) {
+	case 1:  name = "LLQ"; break;
+	case 2:  name = "UL"; break;
+	case 3:  name = "NSID"; break;
+	case 5:  name = "DAU"; break;
+	case 6:  name = "DHU"; break;
+	case 7:  name = "N3U"; break;
+	case 8:  name = "EDNS-CLIENT-SUBNET"; break;
+	case 9:  name = "EDNS-EXPIRE"; break;
+	case 10: name = "COOKIE"; break;
+	case 11: name = "EDNS-TCP-KEEPALIVE"; break;
+	case 12: name = "PADDING"; break;
+	case 13: name = "CHAIN"; break;
+	case 14: name = "EDNS-KEY-TAG"; break;
+	}
+
+	int ret;
+
+	if (name != NULL) {
+		ret = snprintf(out, out_len, "%s", name);
+	} else {
+		ret = snprintf(out, out_len, "CODE%u", code);
+	}
+
+	if (ret <= 0 || (size_t)ret >= out_len) {
+		return -1;
+	} else {
+		return ret;
+	}
+}
diff --git a/src/libknot/descriptor.h b/src/libknot/descriptor.h
new file mode 100644
index 0000000..14cd3b3
--- /dev/null
+++ b/src/libknot/descriptor.h
@@ -0,0 +1,307 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief DNS resource record descriptions.
+ *
+ * \addtogroup rr
+ * @{
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+
+#define KNOT_MAX_RDATA_BLOCKS	8
+#define KNOT_MAX_RDATA_DNAMES	2	// Update this when defining new RR types!
+
+/*!
+ * \brief Resource record class codes.
+ *
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml
+ */
+enum knot_rr_class {
+	KNOT_CLASS_IN   =   1,
+	KNOT_CLASS_CH   =   3,
+	KNOT_CLASS_NONE = 254,
+	KNOT_CLASS_ANY  = 255
+};
+
+/*!
+ * \brief Resource record type constants.
+ *
+ * References:
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml
+ * RFC 3597#4
+ *
+ * METATYPE: Contains DNS data that can't be in a zone file.
+ * QTYPE: Specifies DNS query type; can't be in a zone file.
+ */
+enum knot_rr_type {
+	KNOT_RRTYPE_A          =   1, /*!< An IPv4 host address. */
+	KNOT_RRTYPE_NS         =   2, /*!< An authoritative name server. */
+
+	KNOT_RRTYPE_CNAME      =   5, /*!< The canonical name for an alias. */
+	KNOT_RRTYPE_SOA        =   6, /*!< The start of a zone of authority. */
+
+	KNOT_RRTYPE_NULL       =  10, /*!< METATYPE. Used in RFC 8145. */
+
+	KNOT_RRTYPE_PTR        =  12, /*!< A domain name pointer. */
+	KNOT_RRTYPE_HINFO      =  13, /*!< A host information. */
+	KNOT_RRTYPE_MINFO      =  14, /*!< A mailbox information. */
+	KNOT_RRTYPE_MX         =  15, /*!< Mail exchange. */
+	KNOT_RRTYPE_TXT        =  16, /*!< Text strings. */
+	KNOT_RRTYPE_RP         =  17, /*!< For responsible person. */
+	KNOT_RRTYPE_AFSDB      =  18, /*!< For AFS Data Base location. */
+
+	KNOT_RRTYPE_RT         =  21, /*!< For route through. */
+
+	KNOT_RRTYPE_SIG        =  24, /*!< METATYPE. Transaction signature. */
+	KNOT_RRTYPE_KEY        =  25, /*!< For security key. */
+
+	KNOT_RRTYPE_AAAA       =  28, /*!< IPv6 address. */
+	KNOT_RRTYPE_LOC        =  29, /*!< Location information. */
+
+	KNOT_RRTYPE_SRV        =  33, /*!< Server selection. */
+
+	KNOT_RRTYPE_NAPTR      =  35, /*!< Naming authority pointer . */
+	KNOT_RRTYPE_KX         =  36, /*!< Key exchanger. */
+	KNOT_RRTYPE_CERT       =  37, /*!< Certificate record. */
+
+	KNOT_RRTYPE_DNAME      =  39, /*!< Delegation name. */
+
+	KNOT_RRTYPE_OPT        =  41, /*!< METATYPE. Option for EDNS. */
+	KNOT_RRTYPE_APL        =  42, /*!< Address prefix list. */
+	KNOT_RRTYPE_DS         =  43, /*!< Delegation signer. */
+	KNOT_RRTYPE_SSHFP      =  44, /*!< SSH public key fingerprint. */
+	KNOT_RRTYPE_IPSECKEY   =  45, /*!< IPSEC key. */
+	KNOT_RRTYPE_RRSIG      =  46, /*!< DNSSEC signature. */
+	KNOT_RRTYPE_NSEC       =  47, /*!< Next-secure record. */
+	KNOT_RRTYPE_DNSKEY     =  48, /*!< DNS key. */
+	KNOT_RRTYPE_DHCID      =  49, /*!< DHCP identifier. */
+	KNOT_RRTYPE_NSEC3      =  50, /*!< NSEC version 3. */
+	KNOT_RRTYPE_NSEC3PARAM =  51, /*!< NSEC3 parameters. */
+	KNOT_RRTYPE_TLSA       =  52, /*!< DANE record. */
+	KNOT_RRTYPE_SMIMEA     =  53, /*!< S/MIME cert association. */
+
+	KNOT_RRTYPE_CDS        =  59, /*!< Child delegation signer. */
+	KNOT_RRTYPE_CDNSKEY    =  60, /*!< Child DNS key. */
+	KNOT_RRTYPE_OPENPGPKEY =  61, /*!< OpenPGP Key. */
+	KNOT_RRTYPE_CSYNC      =  62, /*!< Child-To-Parent synchronization. */
+	KNOT_RRTYPE_ZONEMD     =  63, /*!< Message digest for DNS zone. */
+	KNOT_RRTYPE_SVCB       =  64, /*!< Service Binding. */
+	KNOT_RRTYPE_HTTPS      =  65, /*!< HTTPS Binding. */
+
+	KNOT_RRTYPE_SPF        =  99, /*!< Sender policy framework. */
+
+	KNOT_RRTYPE_NID        = 104, /*!< Node identifier. */
+	KNOT_RRTYPE_L32        = 105, /*!< 32-bit network locator. */
+	KNOT_RRTYPE_L64        = 106, /*!< 64-bit network locator. */
+	KNOT_RRTYPE_LP         = 107, /*!< Subnetwork name. */
+	KNOT_RRTYPE_EUI48      = 108, /*!< 48-bit extended unique identifier. */
+	KNOT_RRTYPE_EUI64      = 109, /*!< 64-bit extended unique identifier. */
+
+	KNOT_RRTYPE_TKEY       = 249, /*!< METATYPE. Transaction key. */
+	KNOT_RRTYPE_TSIG       = 250, /*!< METATYPE. Transaction signature. */
+	KNOT_RRTYPE_IXFR       = 251, /*!< QTYPE. Incremental zone transfer. */
+	KNOT_RRTYPE_AXFR       = 252, /*!< QTYPE. Authoritative zone transfer. */
+
+	KNOT_RRTYPE_ANY        = 255, /*!< QTYPE. Any record. */
+	KNOT_RRTYPE_URI        = 256, /*!< Uniform resource identifier. */
+	KNOT_RRTYPE_CAA        = 257, /*!< Certification authority restriction. */
+};
+
+/*!
+ * \brief Some (OBSOLETE) resource record type constants.
+ *
+ * References:
+ * https://www.iana.org/assignments/dns-parameters/dns-parameters.xml
+ * RFC 3597#4
+ *
+ * \note These records can contain compressed domain name in rdata so
+ *       it is important to know the position of them during transfers.
+ */
+enum knot_obsolete_rr_type {
+	KNOT_RRTYPE_MD         =   3,
+	KNOT_RRTYPE_MF         =   4,
+	KNOT_RRTYPE_MB         =   7,
+	KNOT_RRTYPE_MG         =   8,
+	KNOT_RRTYPE_MR         =   9,
+	KNOT_RRTYPE_PX         =  26,
+	KNOT_RRTYPE_NXT        =  30
+};
+
+/*!
+ * \brief Constants characterising the wire format of RDATA items.
+ */
+enum knot_rdata_wireformat {
+	/*!< Dname must not be compressed. */
+	KNOT_RDATA_WF_FIXED_DNAME          = -10,
+	/*!< Dname can be both compressed and decompressed. */
+	KNOT_RDATA_WF_COMPRESSIBLE_DNAME,
+	/*!< Dname can be decompressed. */
+	KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME,
+	/*!< Initial part of NAPTR record before dname. */
+	KNOT_RDATA_WF_NAPTR_HEADER,
+	/*!< Final part of a record. */
+	KNOT_RDATA_WF_REMAINDER,
+	/*!< The last descriptor in array. */
+	KNOT_RDATA_WF_END                  =   0
+};
+
+/*!
+ * \brief Structure describing rdata.
+ */
+typedef struct {
+	/*!< Item types describing rdata. */
+	const int  block_types[KNOT_MAX_RDATA_BLOCKS];
+	/*!< RR type name. */
+	const char *type_name;
+} knot_rdata_descriptor_t;
+
+/*!
+ * \brief Gets rdata descriptor for given RR name.
+ *
+ * \param type Mnemonic of RR type whose descriptor should be returned.
+ *
+ * \retval RR descriptor for given name, NULL descriptor if
+ *         unknown type.
+ */
+const knot_rdata_descriptor_t *knot_get_rdata_descriptor(const uint16_t type);
+
+/*!
+ * \brief Gets rdata descriptor for given RR name (obsolete version).
+ *
+ * \param type Mnemonic of RR type whose descriptor should be returned.
+ *
+ * \retval RR descriptor for given name, NULL descriptor if
+ *         unknown type.
+ */
+const knot_rdata_descriptor_t *knot_get_obsolete_rdata_descriptor(const uint16_t type);
+
+/*!
+ * \brief Converts numeric type representation to mnemonic string.
+ *
+ * \param rrtype  Type RR type code to be converted.
+ * \param out     Output buffer.
+ * \param out_len Length of the output buffer.
+ *
+ * \retval Length of output string.
+ * \retval -1 if error.
+ */
+int knot_rrtype_to_string(const uint16_t rrtype,
+                          char           *out,
+                          const size_t   out_len);
+
+/*!
+ * \brief Converts mnemonic string representation of a type to numeric one.
+ *
+ * \param name Mnemonic string to be converted.
+ * \param num  Output variable.
+ *
+ * \retval  0 if OK.
+ * \retval -1 if error.
+ */
+int knot_rrtype_from_string(const char *name, uint16_t *num);
+
+/*!
+ * \brief Converts numeric class representation to the string one.
+ *
+ * \param rrclass Class code to be converted.
+ * \param out     Output buffer.
+ * \param out_len Length of the output buffer.
+ *
+ * \retval Length of output string.
+ * \retval -1 if error.
+ */
+int knot_rrclass_to_string(const uint16_t rrclass,
+                           char           *out,
+                           const size_t   out_len);
+
+/*!
+ * \brief Converts string representation of a class to numeric one.
+ *
+ * \param name Mnemonic string to be converted.
+ * \param num  Output variable.
+ *
+ * \retval  0 if OK.
+ * \retval -1 if error.
+ */
+int knot_rrclass_from_string(const char *name, uint16_t *num);
+
+/*!
+ * \brief Checks if given item is one of metatypes or qtypes.
+ *
+ * \param type Item value.
+ *
+ * \retval > 0 if YES.
+ * \retval 0 if NO.
+ */
+int knot_rrtype_is_metatype(const uint16_t type);
+
+/*!
+ * \brief Checks if given item is one of the DNSSEC types.
+ *
+ * \param type Item value.
+ *
+ * \retval > 0 if YES.
+ * \retval 0 if NO.
+ */
+int knot_rrtype_is_dnssec(const uint16_t type);
+
+/*!
+ * \brief Checks whether the given type requires additional processing.
+ *
+ * Only MX, NS and SRV types require additional processing.
+ *
+ * \param type Type to check.
+ *
+ * \retval <> 0 if additional processing is needed for \a qtype.
+ * \retval 0 otherwise.
+ */
+int knot_rrtype_additional_needed(const uint16_t type);
+
+/*!
+ * \brief Checks whether the RDATA domain names should be lowercased in
+ *        canonical format of RRSet of the given type.
+ *
+ * Types that should be lowercased are according to RFC 4034, Section 6.2,
+ * except for NSEC (updated by RFC 6840, Section 5.1) and A6 (not supported).
+ *
+ * \param type RRSet type to check.
+ *
+ * \retval true If RDATA dnames for type should be lowercased in canonical format.
+ * \retval false Otherwise.
+ */
+bool knot_rrtype_should_be_lowercased(const uint16_t type);
+
+/*!
+ * \brief Translates option code to string.
+ *
+ * \param code     Code of the option to translate.
+ * \param out      Buffer for the output string.
+ * \param out_len  The available size of the buffer.
+ *
+ * \retval Length of output string.
+ * \retval -1 if error.
+ */
+int knot_opt_code_to_string(const uint16_t code, char *out, const size_t out_len);
+
+/*! @} */
diff --git a/src/libknot/dname.c b/src/libknot/dname.c
new file mode 100644
index 0000000..31b8a5f
--- /dev/null
+++ b/src/libknot/dname.c
@@ -0,0 +1,801 @@
+/*  Copyright (C) 2022 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "libknot/attribute.h"
+#include "libknot/consts.h"
+#include "libknot/dname.h"
+#include "libknot/errcode.h"
+#include "libknot/packet/wire.h"
+#include "contrib/ctype.h"
+#include "contrib/mempattern.h"
+#include "contrib/tolower.h"
+
+static bool label_is_equal(const uint8_t *lb1, const uint8_t *lb2, bool no_case)
+{
+	if (*lb1 != *lb2) {
+		return false;
+	}
+
+	if (no_case) {
+		uint8_t len = *lb1;
+		for (uint8_t i = 1; i <= len; i++) {
+			if (knot_tolower(lb1[i]) != knot_tolower(lb2[i])) {
+				return false;
+			}
+		}
+
+		return true;
+	} else {
+		return memcmp(lb1 + 1, lb2 + 1, *lb1) == 0;
+	}
+}
+
+/*!
+ * \brief Align name end-to-end and return number of common suffix labels.
+ *
+ * \param d1         Domain name1.
+ * \param d1_labels  Number of labels in d1.
+ * \param d2         Domain name2.
+ * \param d2_labels  Number of labels in d2.
+ */
+static int dname_align(const uint8_t **d1, uint8_t d1_labels,
+                       const uint8_t **d2, uint8_t d2_labels)
+{
+	assert(d1 && d2);
+
+	for (unsigned j = d1_labels; j < d2_labels; ++j) {
+		*d2 = knot_wire_next_label(*d2, NULL);
+	}
+
+	for (unsigned j = d2_labels; j < d1_labels; ++j) {
+		*d1 = knot_wire_next_label(*d1, NULL);
+	}
+
+	return (d1_labels < d2_labels) ? d1_labels : d2_labels;
+}
+
+_public_
+int knot_dname_wire_check(const uint8_t *name, const uint8_t *endp,
+                          const uint8_t *pkt)
+{
+	if (name == NULL || name == endp) {
+		return KNOT_EINVAL;
+	}
+
+	int wire_len = 0;
+	int name_len = 1; /* Keep \x00 terminal label in advance. */
+	bool is_compressed = false;
+
+	while (*name != '\0') {
+		/* Check bounds (must have at least 2 octets remaining). */
+		if (name + 2 > endp) {
+			return KNOT_EMALF;
+		}
+
+		if (knot_wire_is_pointer(name)) {
+			/* Check that the pointer points backwards
+			 * otherwise it could result in infinite loop
+			 */
+			if (pkt == NULL) {
+				return KNOT_EINVAL;
+			}
+			uint16_t ptr = knot_wire_get_pointer(name);
+			if (ptr >= (name - pkt)) {
+				return KNOT_EMALF;
+			}
+
+			name = pkt + ptr; /* Hop to compressed label */
+			if (!is_compressed) { /* Measure compressed size only */
+				wire_len += sizeof(uint16_t);
+				is_compressed = true;
+			}
+		} else {
+			/* Check label length. */
+			if (*name > KNOT_DNAME_MAXLABELLEN) {
+				return KNOT_EMALF;
+			}
+			/* Check if there's enough space. */
+			int lblen = *name + 1;
+			if (name_len + lblen > KNOT_DNAME_MAXLEN) {
+				return KNOT_EMALF;
+			}
+			/* Update wire size only for uncompressed part. */
+			name_len += lblen;
+			if (!is_compressed) {
+				wire_len += lblen;
+			}
+			/* Hop to next label. */
+			name += lblen;
+		}
+
+		/* Check bounds (must have at least 1 octet). */
+		if (name + 1 > endp) {
+			return KNOT_EMALF;
+		}
+	}
+
+	if (!is_compressed) { /* Terminal label. */
+		wire_len += 1;
+	}
+
+	return wire_len;
+}
+
+_public_
+size_t knot_dname_store(knot_dname_storage_t dst, const knot_dname_t *name)
+{
+	if (dst == NULL || name == NULL) {
+		return 0;
+	}
+
+	size_t len = knot_dname_size(name);
+	assert(len <= KNOT_DNAME_MAXLEN);
+	memcpy(dst, name, len);
+
+	return len;
+}
+
+_public_
+knot_dname_t *knot_dname_copy(const knot_dname_t *name, knot_mm_t *mm)
+{
+	if (name == NULL) {
+		return NULL;
+	}
+
+	size_t len = knot_dname_size(name);
+	knot_dname_t *dst = mm_alloc(mm, len);
+	if (dst == NULL) {
+		return NULL;
+	}
+	memcpy(dst, name, len);
+
+	return dst;
+}
+
+_public_
+int knot_dname_to_wire(uint8_t *dst, const knot_dname_t *src, size_t maxlen)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t len = knot_dname_size(src);
+	if (len > maxlen) {
+		return KNOT_ESPACE;
+	}
+	memcpy(dst, src, len);
+
+	return len;
+}
+
+_public_
+int knot_dname_unpack(uint8_t *dst, const knot_dname_t *src,
+                      size_t maxlen, const uint8_t *pkt)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Seek first real label occurrence. */
+	src = knot_wire_seek_label(src, pkt);
+
+	/* Unpack rest of the labels. */
+	int len = 0;
+	while (*src != '\0') {
+		uint8_t lblen = *src + 1;
+		if (len + lblen > maxlen) {
+			return KNOT_ESPACE;
+		}
+		memcpy(dst + len, src, lblen);
+		len += lblen;
+		src = knot_wire_next_label(src, pkt);
+	}
+
+	/* Terminal label */
+	if (len + 1 > maxlen) {
+		return KNOT_EINVAL;
+	}
+
+	*(dst + len) = '\0';
+	return len + 1;
+}
+
+_public_
+char *knot_dname_to_str(char *dst, const knot_dname_t *name, size_t maxlen)
+{
+	if (name == NULL) {
+		return NULL;
+	}
+
+	size_t dname_size = knot_dname_size(name);
+
+	/* Check the size for len(dname) + 1 char termination. */
+	size_t alloc_size = (dst == NULL) ? dname_size + 1 : maxlen;
+	if (alloc_size < dname_size + 1) {
+		return NULL;
+	}
+
+	char *res = (dst == NULL) ? malloc(alloc_size) : dst;
+	if (res == NULL) {
+		return NULL;
+	}
+
+	uint8_t label_len = 0;
+	size_t  str_len = 0;
+
+	for (unsigned i = 0; i < dname_size; i++) {
+		uint8_t c = name[i];
+
+		/* Read next label size. */
+		if (label_len == 0) {
+			label_len = c;
+
+			/* Write label separation. */
+			if (str_len > 0 || dname_size == 1) {
+				if (alloc_size <= str_len + 1) {
+					goto dname_to_str_failed;
+				}
+				res[str_len++] = '.';
+			}
+
+			continue;
+		}
+
+		if (is_alnum(c) || c == '-' || c == '_' || c == '*' ||
+		    c == '/') {
+			if (alloc_size <= str_len + 1) {
+				goto dname_to_str_failed;
+			}
+			res[str_len++] = c;
+		} else if (is_punct(c) && c != '#') {
+			/* Exclusion of '#' character is to avoid possible
+			 * collision with rdata hex notation '\#'. So it is
+			 * encoded in \ddd notation.
+			 */
+
+			if (dst != NULL) {
+				if (maxlen <= str_len + 2) {
+					goto dname_to_str_failed;
+				}
+			} else {
+				/* Extend output buffer for \x format. */
+				alloc_size += 1;
+				char *extended = realloc(res, alloc_size);
+				if (extended == NULL) {
+					goto dname_to_str_failed;
+				}
+				res = extended;
+			}
+
+			/* Write encoded character. */
+			res[str_len++] = '\\';
+			res[str_len++] = c;
+		} else {
+			if (dst != NULL) {
+				if (maxlen <= str_len + 4) {
+					goto dname_to_str_failed;
+				}
+			} else {
+				/* Extend output buffer for \DDD format. */
+				alloc_size += 3;
+				char *extended = realloc(res, alloc_size);
+				if (extended == NULL) {
+					goto dname_to_str_failed;
+				}
+				res = extended;
+			}
+
+			/* Write encoded character. */
+			int ret = snprintf(res + str_len, alloc_size - str_len,
+			                   "\\%03u", c);
+			if (ret <= 0 || ret >= alloc_size - str_len) {
+				goto dname_to_str_failed;
+			}
+
+			str_len += ret;
+		}
+
+		label_len--;
+	}
+
+	/* String_termination. */
+	assert(str_len < alloc_size);
+	res[str_len] = 0;
+
+	return res;
+
+dname_to_str_failed:
+
+	if (dst == NULL) {
+		free(res);
+	}
+
+	return NULL;
+}
+
+_public_
+knot_dname_t *knot_dname_from_str(uint8_t *dst, const char *name, size_t maxlen)
+{
+	if (name == NULL) {
+		return NULL;
+	}
+
+	size_t name_len = strlen(name);
+	if (name_len == 0) {
+		return NULL;
+	}
+
+	/* Wire size estimation. */
+	size_t alloc_size = maxlen;
+	if (dst == NULL) {
+		/* Check for the root label. */
+		if (name[0] == '.') {
+			/* Just the root dname can begin with a dot. */
+			if (name_len > 1) {
+				return NULL;
+			}
+			name_len = 0; /* Skip the following parsing. */
+			alloc_size = 1;
+		} else if (name[name_len - 1] != '.') { /* Check for non-FQDN. */
+			alloc_size = 1 + name_len + 1;
+		} else {
+			alloc_size = 1 + name_len ; /* + 1 ~ first label length. */
+		}
+	}
+
+	/* The minimal (root) dname takes 1 byte. */
+	if (alloc_size == 0) {
+		return NULL;
+	}
+
+	/* Check the maximal wire size. */
+	if (alloc_size > KNOT_DNAME_MAXLEN) {
+		alloc_size = KNOT_DNAME_MAXLEN;
+	}
+
+	/* Prepare output buffer. */
+	uint8_t *wire = (dst == NULL) ? malloc(alloc_size) : dst;
+	if (wire == NULL) {
+		return NULL;
+	}
+
+	uint8_t *label = wire;
+	uint8_t *wire_pos = wire + 1;
+	uint8_t *wire_end = wire + alloc_size;
+
+	/* Initialize the first label (root label). */
+	*label = 0;
+
+	const uint8_t *ch = (const uint8_t *)name;
+	const uint8_t *end = ch + name_len;
+
+	while (ch < end) {
+		/* Check the output buffer for enough space. */
+		if (wire_pos >= wire_end) {
+			goto dname_from_str_failed;
+		}
+
+		switch (*ch) {
+		case '.':
+			/* Check for invalid zero-length label. */
+			if (*label == 0 && name_len > 1) {
+				goto dname_from_str_failed;
+			}
+			label = wire_pos++;
+			*label = 0;
+			break;
+		case '\\':
+			ch++;
+
+			/* At least one more character is required OR
+			 * check for maximal label length.
+			 */
+			if (ch == end || ++(*label) > KNOT_DNAME_MAXLABELLEN) {
+				goto dname_from_str_failed;
+			}
+
+			/* Check for \DDD notation. */
+			if (is_digit(*ch)) {
+				/* Check for next two digits. */
+				if (ch + 2 >= end ||
+				    !is_digit(*(ch + 1)) ||
+				    !is_digit(*(ch + 2))) {
+					goto dname_from_str_failed;
+				}
+
+				uint32_t num = (*(ch + 0) - '0') * 100 +
+				               (*(ch + 1) - '0') * 10 +
+				               (*(ch + 2) - '0') * 1;
+				if (num > UINT8_MAX) {
+					goto dname_from_str_failed;
+				}
+				*(wire_pos++) = num;
+				ch +=2;
+			} else {
+				*(wire_pos++) = *ch;
+			}
+			break;
+		default:
+			/* Check for maximal label length. */
+			if (++(*label) > KNOT_DNAME_MAXLABELLEN) {
+				goto dname_from_str_failed;
+			}
+			*(wire_pos++) = *ch;
+		}
+		ch++;
+	}
+
+	/* Check for non-FQDN name. */
+	if (*label > 0) {
+		if (wire_pos >= wire_end) {
+			goto dname_from_str_failed;
+		}
+		*(wire_pos++) = 0;
+	}
+
+	/* Reduce output buffer if the size is overestimated. */
+	if (wire_pos < wire_end && dst == NULL) {
+		uint8_t *reduced = realloc(wire, wire_pos - wire);
+		if (reduced == NULL) {
+			goto dname_from_str_failed;
+		}
+		wire = reduced;
+	}
+
+	return wire;
+
+dname_from_str_failed:
+
+	if (dst == NULL) {
+		free(wire);
+	}
+
+	return NULL;
+}
+
+_public_
+void knot_dname_to_lower(knot_dname_t *name)
+{
+	if (name == NULL) {
+		return;
+	}
+
+	while (*name != '\0') {
+		uint8_t len = *name;
+		for (uint8_t i = 1; i <= len; ++i) {
+			name[i] = knot_tolower(name[i]);
+		}
+		name += 1 + len;
+	}
+}
+
+_public_
+void knot_dname_copy_lower(knot_dname_t *dst, const knot_dname_t *name)
+{
+	if (dst == NULL || name == NULL) {
+		return;
+	}
+
+	while (*name != '\0') {
+		uint8_t len = *name;
+		*dst = len;
+		for (uint8_t i = 1; i <= len; ++i) {
+			dst[i] = knot_tolower(name[i]);
+		}
+		dst += 1 + len;
+		name += 1 + len;
+	}
+	*dst = '\0';
+}
+
+_public_
+size_t knot_dname_size(const knot_dname_t *name)
+{
+	if (name == NULL) {
+		return 0;
+	}
+
+	/* Count name size without terminal label. */
+	size_t len = 0;
+	while (*name != '\0' && !knot_wire_is_pointer(name)) {
+		uint8_t lblen = *name + 1;
+		len += lblen;
+		name += lblen;
+	}
+
+	if (knot_wire_is_pointer(name)) {
+		/* Add 2-octet compression pointer. */
+		return len + 2;
+	} else {
+		/* Add 1-octet terminal label. */
+		return len + 1;
+	}
+}
+
+_public_
+size_t knot_dname_realsize(const knot_dname_t *name, const uint8_t *pkt)
+{
+	if (name == NULL) {
+		return 0;
+	}
+
+	/* Seek first real label occurrence. */
+	name = knot_wire_seek_label(name, pkt);
+
+	size_t len = 0;
+	while (*name != '\0') {
+		len += *name + 1;
+		name = knot_wire_next_label(name, pkt);
+	}
+
+	/* Add 1-octet terminal label. */
+	return len + 1;
+}
+
+_public_
+size_t knot_dname_matched_labels(const knot_dname_t *d1, const knot_dname_t *d2)
+{
+	/* Count labels. */
+	size_t l1 = knot_dname_labels(d1, NULL);
+	size_t l2 = knot_dname_labels(d2, NULL);
+	if (l1 == 0 || l2 == 0) {
+		return 0;
+	}
+
+	/* Align end-to-end to common suffix. */
+	int common = dname_align(&d1, l1, &d2, l2);
+
+	/* Count longest chain leading to root label. */
+	size_t matched = 0;
+	while (common > 0) {
+		if (label_is_equal(d1, d2, false)) {
+			++matched;
+		} else {
+			matched = 0; /* Broken chain. */
+		}
+
+		/* Next label. */
+		d1 = knot_wire_next_label(d1, NULL);
+		d2 = knot_wire_next_label(d2, NULL);
+		--common;
+	}
+
+	return matched;
+}
+
+_public_
+knot_dname_t *knot_dname_replace_suffix(const knot_dname_t *name, unsigned labels,
+                                        const knot_dname_t *suffix, knot_mm_t *mm)
+{
+	if (name == NULL) {
+		return NULL;
+	}
+
+	/* Calculate prefix and suffix lengths. */
+	size_t dname_lbs = knot_dname_labels(name, NULL);
+	if (dname_lbs < labels) {
+		return NULL;
+	}
+	size_t prefix_lbs = dname_lbs - labels;
+
+	size_t prefix_len = knot_dname_prefixlen(name, prefix_lbs, NULL);
+	size_t suffix_len = knot_dname_size(suffix);
+	if (prefix_len == 0 || suffix_len == 0) {
+		return NULL;
+	}
+
+	/* Create target name. */
+	size_t new_len = prefix_len + suffix_len;
+	knot_dname_t *out = mm_alloc(mm, new_len);
+	if (out == NULL) {
+		return NULL;
+	}
+
+	/* Copy prefix. */
+	uint8_t *dst = out;
+	while (prefix_lbs > 0) {
+		memcpy(dst, name, *name + 1);
+		dst += *name + 1;
+		name = knot_wire_next_label(name, NULL);
+		--prefix_lbs;
+	}
+
+	/* Copy suffix. */
+	while (*suffix != '\0') {
+		memcpy(dst, suffix, *suffix + 1);
+		dst += *suffix + 1;
+		suffix = knot_wire_next_label(suffix, NULL);
+	}
+
+	*dst = '\0';
+	return out;
+}
+
+_public_
+void knot_dname_free(knot_dname_t *name, knot_mm_t *mm)
+{
+	if (name == NULL) {
+		return;
+	}
+
+	mm_free(mm, name);
+}
+
+_public_
+int knot_dname_cmp(const knot_dname_t *d1, const knot_dname_t *d2)
+{
+	if (d1 == NULL) {
+		return -1;
+	} else if (d2 == NULL) {
+		return 1;
+	}
+
+	/* Convert to lookup format. */
+	knot_dname_storage_t lf1_storage;
+	knot_dname_storage_t lf2_storage;
+
+	uint8_t *lf1 = knot_dname_lf(d1, lf1_storage);
+	uint8_t *lf2 = knot_dname_lf(d2, lf2_storage);
+	assert(lf1 && lf2);
+
+	/* Compare common part. */
+	uint8_t common = lf1[0];
+	if (common > lf2[0]) {
+		common = lf2[0];
+	}
+	int ret = memcmp(lf1 + 1, lf2 + 1, common);
+	if (ret != 0) {
+		return ret;
+	}
+
+	/* If they match, compare lengths. */
+	if (lf1[0] < lf2[0]) {
+		return -1;
+	} else if (lf1[0] > lf2[0]) {
+		return 1;
+	} else {
+		return 0;
+	}
+}
+
+inline static bool dname_is_equal(const knot_dname_t *d1, const knot_dname_t *d2, bool no_case)
+{
+	if (d1 == NULL || d2 == NULL) {
+		return false;
+	}
+
+	while (*d1 != '\0' || *d2 != '\0') {
+		if (label_is_equal(d1, d2, no_case)) {
+			d1 = knot_wire_next_label(d1, NULL);
+			d2 = knot_wire_next_label(d2, NULL);
+		} else {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+_public_
+bool knot_dname_is_equal(const knot_dname_t *d1, const knot_dname_t *d2)
+{
+	return dname_is_equal(d1, d2, false);
+}
+
+_public_
+bool knot_dname_is_case_equal(const knot_dname_t *d1, const knot_dname_t *d2)
+{
+	return dname_is_equal(d1, d2, true);
+}
+
+_public_
+size_t knot_dname_prefixlen(const uint8_t *name, unsigned nlabels, const uint8_t *pkt)
+{
+	if (name == NULL) {
+		return 0;
+	}
+
+	/* Zero labels means no prefix. */
+	if (nlabels == 0) {
+		return 0;
+	}
+
+	/* Seek first real label occurrence. */
+	name = knot_wire_seek_label(name, pkt);
+
+	size_t len = 0;
+	while (*name != '\0') {
+		len += *name + 1;
+		name = knot_wire_next_label(name, pkt);
+		if (--nlabels == 0) { /* Count N first labels only. */
+			break;
+		}
+	}
+
+	return len;
+}
+
+_public_
+size_t knot_dname_labels(const uint8_t *name, const uint8_t *pkt)
+{
+	if (name == NULL) {
+		return 0;
+	}
+
+	size_t count = 0;
+	while (*name != '\0') {
+		++count;
+		name = knot_wire_next_label(name, pkt);
+		if (name == NULL) {
+			return 0;
+		}
+	}
+
+	return count;
+}
+
+_public_
+uint8_t *knot_dname_lf(const knot_dname_t *src, knot_dname_storage_t storage)
+{
+	if (src == NULL || storage == NULL) {
+		return NULL;
+	}
+
+	uint8_t *dst = storage + KNOT_DNAME_MAXLEN - 1;
+
+	while (*src != 0) {
+		uint8_t len = *src++;
+		*dst = '\0';
+		dst -= len;
+		assert(dst >= storage);
+
+		if (len == 1) {
+			*dst-- = *src++;
+		} else {
+			memcpy(dst--, src, len);
+			src += len;
+		}
+	}
+
+	*dst = storage + KNOT_DNAME_MAXLEN - 1 - dst;
+	assert(dst >= storage);
+
+	return dst;
+}
+
+_public_
+int knot_dname_in_bailiwick(const knot_dname_t *name, const knot_dname_t *bailiwick)
+{
+	if (name == NULL || bailiwick == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int label_diff = knot_dname_labels(name, NULL) - knot_dname_labels(bailiwick, NULL);
+	if (label_diff < 0) {
+		return KNOT_EOUTOFZONE;
+	}
+
+	for (int i = 0; i < label_diff; ++i) {
+		name = knot_wire_next_label(name, NULL);
+	}
+
+	return knot_dname_is_equal(name, bailiwick) ? label_diff : KNOT_EOUTOFZONE;
+}
diff --git a/src/libknot/dname.h b/src/libknot/dname.h
new file mode 100644
index 0000000..5733de9
--- /dev/null
+++ b/src/libknot/dname.h
@@ -0,0 +1,354 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Domain name structure and API for manipulating it.
+ *
+ * \addtogroup dname
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "libknot/attribute.h"
+#include "libknot/consts.h"
+#include "libknot/mm_ctx.h"
+
+/*! \brief Type representing a domain name in wire format. */
+typedef uint8_t knot_dname_t;
+
+/*! \brief Local domain name storage. */
+typedef uint8_t knot_dname_storage_t[KNOT_DNAME_MAXLEN];
+
+/*! \brief Local textual domain name storage. */
+typedef char knot_dname_txt_storage_t[KNOT_DNAME_TXT_MAXLEN + 1];
+
+/*!
+ * \brief Check dname on the wire for constraints.
+ *
+ * If the name passes such checks, it is safe to be used in rest of the functions.
+ *
+ * \param name  Name on the wire.
+ * \param endp  Name boundary.
+ * \param pkt   Wire.
+ *
+ * \retval (compressed) size of the domain name.
+ * \retval KNOT_EINVAL
+ * \retval KNOT_EMALF
+ */
+_pure_ _mustcheck_
+int knot_dname_wire_check(const uint8_t *name, const uint8_t *endp,
+                          const uint8_t *pkt);
+
+/*!
+ * \brief Duplicates the given domain name to a local storage.
+ *
+ * \param dst   Destination storage.
+ * \param name  Domain name to be copied.
+ *
+ * \retval size of the domain name.
+ * \retval 0 if invalid argument.
+ */
+_mustcheck_
+size_t knot_dname_store(knot_dname_storage_t dst, const knot_dname_t *name);
+
+/*!
+ * \brief Duplicates the given domain name.
+ *
+ * \param name  Domain name to be copied.
+ * \param mm    Memory context.
+ *
+ * \return New domain name which is an exact copy of \a name.
+ */
+_mustcheck_
+knot_dname_t *knot_dname_copy(const knot_dname_t *name, knot_mm_t *mm);
+
+/*!
+ * \brief Copy name to wire as is, no compression pointer expansion will be done.
+ *
+ * \param dst     Destination wire.
+ * \param src     Source name.
+ * \param maxlen  Maximum wire length.
+ *
+ * \return the number of bytes written or negative error code
+ */
+int knot_dname_to_wire(uint8_t *dst, const knot_dname_t *src, size_t maxlen);
+
+/*!
+ * \brief Write unpacked name (i.e. compression pointers expanded)
+ *
+ * \note The function is very similar to the knot_dname_to_wire(), except
+ *       it expands compression pointers. E.g. you want to use knot_dname_unpack()
+ *       if you copy a dname from incoming packet to some persistent storage.
+ *       And you want to use knot_dname_to_wire() if you know the name is not
+ *       compressed or you want to copy it 1:1.
+ *
+ * \param dst     Destination wire.
+ * \param src     Source name.
+ * \param maxlen  Maximum destination wire size.
+ * \param pkt     Name packet wire (for compression pointers).
+ *
+ * \return number of bytes written
+ */
+int knot_dname_unpack(uint8_t *dst, const knot_dname_t *src,
+                      size_t maxlen, const uint8_t *pkt);
+
+/*!
+ * \brief Converts the given domain name to its string representation.
+ *
+ * \note Output buffer is allocated automatically if dst is NULL.
+ *
+ * \param dst     Output buffer.
+ * \param name    Domain name to be converted.
+ * \param maxlen  Output buffer length.
+ *
+ * \return 0-terminated string if successful, NULL if error.
+ */
+char *knot_dname_to_str(char *dst, const knot_dname_t *name, size_t maxlen);
+
+/*!
+ * \brief This function is a shortcut for \ref knot_dname_to_str with
+ *        no output buffer parameters.
+ */
+_mustcheck_
+static inline char *knot_dname_to_str_alloc(const knot_dname_t *name)
+{
+	return knot_dname_to_str(NULL, name, 0);
+}
+
+/*!
+ * \brief Creates a dname structure from domain name given in presentation
+ *        format.
+ *
+ * \note The resulting FQDN is stored in the wire format.
+ * \note Output buffer is allocated automatically if dst is NULL.
+ *
+ * \param dst    Output buffer.
+ * \param name   Domain name in presentation format (labels separated by dots,
+ *               '\0' terminated).
+ * \param maxlen Output buffer length.
+ *
+ * \return New dname if successful, NULL if error.
+ */
+knot_dname_t *knot_dname_from_str(uint8_t *dst, const char *name, size_t maxlen);
+
+/*!
+ * \brief This function is a shortcut for \ref knot_dname_from_str with
+ *        no output buffer parameters.
+ */
+_mustcheck_
+static inline knot_dname_t *knot_dname_from_str_alloc(const char *name)
+{
+	return knot_dname_from_str(NULL, name, 0);
+}
+
+/*!
+ * \brief Convert domain name to lowercase.
+ *
+ * \param name  Domain name to be converted.
+ */
+void knot_dname_to_lower(knot_dname_t *name);
+
+/*!
+ * \brief Copy lowercased domain name.
+ *
+ * \note The output buffer isn't checked if it's big enough!
+ *
+ * \param dst   Destination buffer.
+ * \param name  Source domain name to be converted.
+ */
+void knot_dname_copy_lower(knot_dname_t *dst, const knot_dname_t *name);
+
+/*!
+ * \brief Returns size of the given domain name.
+ *
+ * \note If the domain name is compressed, the length of not compressed part
+ *       is returned.
+ *
+ * \param name  Domain name to get the size of.
+ *
+ * \retval size of the domain name.
+ * \retval 0 if invalid argument.
+ */
+_pure_
+size_t knot_dname_size(const knot_dname_t *name);
+
+/*!
+ * \brief Returns full size of the given domain name (expanded compression ptrs).
+ *
+ * \param name  Domain name to get the size of.
+ * \param pkt   Related packet (or NULL if unpacked)
+ *
+ * \retval size of the domain name.
+ * \retval 0 if invalid argument.
+ */
+_pure_
+size_t knot_dname_realsize(const knot_dname_t *name, const uint8_t *pkt);
+
+/*!
+ * \brief Checks if the domain name is a wildcard.
+ *
+ * \param name  Domain name to check.
+ *
+ * \retval true if \a dname is a wildcard domain name.
+ * \retval false otherwise.
+ */
+static inline
+bool knot_dname_is_wildcard(const knot_dname_t *name)
+{
+	return name != NULL && name[0] == 1 && name[1] == '*';
+}
+
+/*!
+ * \brief Returns the number of labels common for the two domain names (counted
+ *        from the rightmost label.
+ *
+ * \param d1  First domain name.
+ * \param d2  Second domain name.
+ *
+ * \return Number of labels common for the two domain names.
+ */
+_pure_
+size_t knot_dname_matched_labels(const knot_dname_t *d1, const knot_dname_t *d2);
+
+/*!
+ * \brief Replaces the suffix of given size in one domain name with other domain
+ *        name.
+ *
+ * \param name    Domain name where to replace the suffix.
+ * \param labels  Size of the suffix to be replaced.
+ * \param suffix  New suffix to be used as a replacement.
+ * \param mm      Memory context.
+ *
+ * \return New domain name created by replacing suffix of \a dname of size
+ *         \a size with \a suffix.
+ */
+_mustcheck_
+knot_dname_t *knot_dname_replace_suffix(const knot_dname_t *name, unsigned labels,
+                                        const knot_dname_t *suffix, knot_mm_t *mm);
+
+/*!
+ * \brief Destroys the given domain name.
+ *
+ * \param name  Domain name to be destroyed.
+ * \param mm    Memory context.
+ */
+void knot_dname_free(knot_dname_t *name, knot_mm_t *mm);
+
+/*!
+ * \brief Compares two domain names by labels (case sensitive).
+ *
+ * \param d1  First domain name.
+ * \param d2  Second domain name.
+ *
+ * \retval < 0 if \a d1 goes before \a d2 in canonical order.
+ * \retval > 0 if \a d1 goes after \a d2 in canonical order.
+ * \retval 0 if the domain names are identical.
+ */
+_pure_
+int knot_dname_cmp(const knot_dname_t *d1, const knot_dname_t *d2);
+
+/*!
+ * \brief Compares two domain names (case sensitive).
+ *
+ * \param d1  First domain name.
+ * \param d2  Second domain name.
+ *
+ * \retval true if the domain names are identical
+ * \retval false if the domain names are NOT identical
+ */
+_pure_
+bool knot_dname_is_equal(const knot_dname_t *d1, const knot_dname_t *d2);
+
+/*!
+ * \brief Compares two domain names (case insensitive).
+ *
+ * \param d1  First domain name.
+ * \param d2  Second domain name.
+ *
+ * \retval true if the domain names are equal
+ * \retval false if the domain names are NOT equal
+ */
+_pure_
+bool knot_dname_is_case_equal(const knot_dname_t *d1, const knot_dname_t *d2);
+
+/*!
+ * \brief Count length of the N first labels.
+ *
+ * \param name     Domain name.
+ * \param nlabels  First N labels.
+ * \param pkt      Related packet (or NULL if not compressed).
+ *
+ * \return Length of the prefix.
+ */
+_pure_
+size_t knot_dname_prefixlen(const uint8_t *name, unsigned nlabels, const uint8_t *pkt);
+
+/*!
+ * \brief Return number of labels in the domain name.
+ *
+ * Terminal nullbyte is not counted.
+ *
+ * \param name  Domain name.
+ * \param pkt   Related packet (or NULL if not compressed).
+ *
+ * \return Number of labels.
+ */
+_pure_
+size_t knot_dname_labels(const uint8_t *name, const uint8_t *pkt);
+
+/*!
+ * \brief Convert domain name from wire to the lookup format.
+ *
+ * Formats names from rightmost label to the leftmost, separated by the lowest
+ * possible character (\\x00). Sorting such formatted names also gives
+ * correct canonical order (for NSEC/NSEC3). The first byte of the output
+ * contains length of the remaining output.
+ *
+ * Examples:
+ * Name:   lake.example.com.
+ * Wire:   \\x04lake\\x07example\\x03com\\x00
+ * Lookup: \\x11com\\x00example\\x00lake\\x00
+ *
+ * Name:   .
+ * Wire:   \\x00
+ * Lookup: \\x00
+ *
+ * \param src      Source domain name.
+ * \param storage  Memory to store converted name into. Don't use directly!
+ *
+ * \retval Lookup format if successful (pointer into the storage).
+ * \retval NULL on invalid parameters.
+ */
+uint8_t *knot_dname_lf(const knot_dname_t *src, knot_dname_storage_t storage);
+
+/*!
+ * \brief Check whether a domain name is under another one and how deep.
+ *
+ * \param name       The longer name to check.
+ * \param bailiwick  The shorter name to check.
+ *
+ * \retval >=0 a subdomain nested this many labels.
+ * \retval <0 not a subdomain (KNOT_EOUTOFZONE) or another error (KNOT_EINVAL).
+ */
+int knot_dname_in_bailiwick(const knot_dname_t *name, const knot_dname_t *bailiwick);
+
+/*! @} */
diff --git a/src/libknot/dynarray.h b/src/libknot/dynarray.h
new file mode 100644
index 0000000..7ea66f9
--- /dev/null
+++ b/src/libknot/dynarray.h
@@ -0,0 +1,188 @@
+/*  Copyright (C) 2022 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>
+
+#include "libknot/attribute.h"
+
+#pragma once
+
+#define DYNARRAY_VISIBILITY_NORMAL
+#define DYNARRAY_VISIBILITY_STATIC static
+#define DYNARRAY_VISIBILITY_PUBLIC _public_
+
+#define knot_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 ntype *prefix ## _dynarray_add(prefix ## _dynarray_t *dynarray, \
+	                                        ntype const *to_add); \
+	visibility void prefix ## _dynarray_remove(prefix ## _dynarray_t *dynarray, \
+	                                        ntype const *to_remove); \
+	visibility void prefix ## _dynarray_sort(prefix ## _dynarray_t *dynarray); \
+	visibility ntype *prefix ## _dynarray_bsearch(prefix ## _dynarray_t *dynarray, \
+	                                        const ntype *bskey); \
+	visibility void prefix ## _dynarray_sort_dedup(prefix ## _dynarray_t *dynarray); \
+	visibility void prefix ## _dynarray_free(prefix ## _dynarray_t *dynarray);
+
+#define knot_dynarray_foreach(prefix, ntype, ptr, array) \
+	for (ntype *ptr = prefix ## _dynarray_arr(&(array)); \
+	     ptr < prefix ## _dynarray_arr(&(array)) + (array).size; ptr++)
+
+#define knot_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); \
+		} \
+	} \
+	\
+	_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; \
+	} \
+	\
+	_unused_ \
+	visibility ntype *prefix ## _dynarray_add(struct prefix ## _dynarray *dynarray, \
+	                                          ntype const *to_add) \
+	{ \
+		if (dynarray->capacity < 0) { \
+			return NULL; \
+		} \
+		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 NULL; \
+			} \
+			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__; \
+		} \
+		ntype *add_to = &prefix ## _dynarray_arr(dynarray)[dynarray->size++]; \
+		*add_to = *to_add; \
+		return add_to; \
+	} \
+	\
+	_unused_ \
+	visibility void prefix ## _dynarray_remove(struct prefix ## _dynarray *dynarray, \
+	                                           ntype const *to_remove) \
+	{ \
+		ntype *orig_arr = prefix ## _dynarray_arr(dynarray); \
+		knot_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! */ \
+	} \
+	\
+	static int prefix ## _dynarray_memb_cmp(const void *a, const void *b) \
+	{ \
+		return memcmp(a, b, sizeof(ntype)); \
+	} \
+	\
+	_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); \
+	} \
+	\
+	_unused_ \
+	visibility ntype *prefix ## _dynarray_bsearch(struct prefix ## _dynarray *dynarray, const ntype *bskey) \
+	{ \
+		ntype *arr = prefix ## _dynarray_arr(dynarray); \
+		return bsearch(bskey, arr, dynarray->size, sizeof(*arr), prefix ## _dynarray_memb_cmp); \
+	} \
+	\
+	_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; \
+		} \
+	} \
+	_unused_ \
+	visibility void prefix ## _dynarray_free(struct prefix ## _dynarray *dynarray) \
+	{ \
+		prefix ## _dynarray_free__(dynarray); \
+		memset(dynarray, 0, sizeof(*dynarray)); \
+	}
diff --git a/src/libknot/endian.h b/src/libknot/endian.h
new file mode 100644
index 0000000..037ed68
--- /dev/null
+++ b/src/libknot/endian.h
@@ -0,0 +1,51 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Endian dependent integer operations.
+ *
+ * \addtogroup wire
+ * @{
+ */
+
+#pragma once
+
+#if defined(__linux__) || defined(__gnu_hurd__) || \
+    (defined(__FreeBSD_kernel__) && defined(__GLIBC__))
+#       include <endian.h>
+#elif defined(__FreeBSD__) || defined(__NetBSD__)
+#       include <sys/endian.h>
+#elif defined(__OpenBSD__) || defined(__sun) || defined(__CYGWIN__)
+#       include <endian.h>
+#elif defined(__APPLE__)
+#       include <libkern/OSByteOrder.h>
+#       define be16toh(x) OSSwapBigToHostInt16(x)
+#       define be32toh(x) OSSwapBigToHostInt32(x)
+#       define be64toh(x) OSSwapBigToHostInt64(x)
+#       define htobe16(x) OSSwapHostToBigInt16(x)
+#       define htobe32(x) OSSwapHostToBigInt32(x)
+#       define htobe64(x) OSSwapHostToBigInt64(x)
+#       define le16toh(x) OSSwapLittleToHostInt16(x)
+#       define le32toh(x) OSSwapLittleToHostInt32(x)
+#       define le64toh(x) OSSwapLittleToHostInt64(x)
+#       define htole16(x) OSSwapHostToLittleInt16(x)
+#       define htole32(x) OSSwapHostToLittleInt32(x)
+#       define htole64(x) OSSwapHostToLittleInt64(x)
+#endif
+
+/*! @} */
diff --git a/src/libknot/errcode.h b/src/libknot/errcode.h
new file mode 100644
index 0000000..648ca66
--- /dev/null
+++ b/src/libknot/errcode.h
@@ -0,0 +1,272 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Knot error codes.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include <errno.h>
+
+/*! \brief Error codes used in the library. */
+enum knot_error {
+	KNOT_EOK = 0,
+
+	/* Directly mapped error codes. */
+	KNOT_ENOMEM        = -ENOMEM,
+	KNOT_EINVAL        = -EINVAL,
+	KNOT_ENOTSUP       = -ENOTSUP,
+	KNOT_EBUSY         = -EBUSY,
+	KNOT_EAGAIN        = -EAGAIN,
+	KNOT_ENOBUFS       = -ENOBUFS,
+	KNOT_EMFILE        = -EMFILE,
+	KNOT_ENFILE        = -ENFILE,
+	KNOT_EACCES        = -EACCES,
+	KNOT_EISCONN       = -EISCONN,
+	KNOT_ECONNREFUSED  = -ECONNREFUSED,
+	KNOT_EALREADY      = -EALREADY,
+	KNOT_ECONNRESET    = -ECONNRESET,
+	KNOT_ECONNABORTED  = -ECONNABORTED,
+	KNOT_ENETRESET     = -ENETRESET,
+	KNOT_EHOSTUNREACH  = -EHOSTUNREACH,
+	KNOT_ENETUNREACH   = -ENETUNREACH,
+	KNOT_EHOSTDOWN     = -EHOSTDOWN,
+	KNOT_ENETDOWN      = -ENETDOWN,
+	KNOT_EADDRINUSE    = -EADDRINUSE,
+	KNOT_ENOENT        = -ENOENT,
+	KNOT_EEXIST        = -EEXIST,
+	KNOT_ERANGE        = -ERANGE,
+	KNOT_EADDRNOTAVAIL = -EADDRNOTAVAIL,
+	KNOT_ENOTDIR       = -ENOTDIR,
+
+	KNOT_ERRNO_ERROR   = -500,
+
+	KNOT_ERROR_MIN = -1000,
+
+	/* General errors. */
+	KNOT_ERROR = KNOT_ERROR_MIN,
+	KNOT_EPARSEFAIL,
+	KNOT_ESEMCHECK,
+	KNOT_EUPTODATE,
+	KNOT_EFEWDATA,
+	KNOT_ESPACE,
+	KNOT_EMALF,
+	KNOT_ENSEC3PAR,
+	KNOT_ENSEC3CHAIN,
+	KNOT_EOUTOFZONE,
+	KNOT_EZONEINVAL,
+	KNOT_ENOZONE,
+	KNOT_ENONODE,
+	KNOT_ENORECORD,
+	KNOT_EISRECORD,
+	KNOT_ENOMASTER,
+	KNOT_EPREREQ,
+	KNOT_ETTL,
+	KNOT_ENOTTL,
+	KNOT_ENOXFR,
+	KNOT_EDENIED,
+	KNOT_ECONN,
+	KNOT_ETIMEOUT,
+	KNOT_ENODIFF,
+	KNOT_ENOTSIG,
+	KNOT_ELIMIT,
+	KNOT_EZONESIZE,
+	KNOT_EOF,
+	KNOT_ESYSTEM,
+	KNOT_EFILE,
+	KNOT_ESOAINVAL,
+	KNOT_ETRAIL,
+	KNOT_EPROCESSING,
+	KNOT_EPROGRESS,
+	KNOT_ELOOP,
+	KNOT_EPROGRAM,
+	KNOT_EFD,
+	KNOT_ENOPARAM,
+	KNOT_EXPARAM,
+	KNOT_EEMPTYZONE,
+	KNOT_ENODB,
+	KNOT_EUNREACH,
+
+	KNOT_GENERAL_ERROR = -900,
+
+	/* Control states. */
+	KNOT_CTL_ESTOP,
+	KNOT_CTL_EZONE,
+
+	/* Network errors. */
+	KNOT_NET_EADDR,
+	KNOT_NET_ESOCKET,
+	KNOT_NET_ECONNECT,
+	KNOT_NET_ESEND,
+	KNOT_NET_ERECV,
+	KNOT_NET_ETIMEOUT,
+
+	/* Encoding errors. */
+	KNOT_BASE64_ESIZE,
+	KNOT_BASE64_ECHAR,
+	KNOT_BASE32HEX_ESIZE,
+	KNOT_BASE32HEX_ECHAR,
+
+	/* TSIG errors. */
+	KNOT_TSIG_EBADSIG,
+	KNOT_TSIG_EBADKEY,
+	KNOT_TSIG_EBADTIME,
+	KNOT_TSIG_EBADTRUNC,
+
+	/* DNSSEC errors. */
+	KNOT_DNSSEC_EMISSINGKEYTYPE,
+	KNOT_DNSSEC_ENOKEY,
+	KNOT_DNSSEC_ENOSIG,
+	KNOT_DNSSEC_ENONSEC,
+	KNOT_DNSSEC_ENSEC_BITMAP,
+	KNOT_DNSSEC_ENSEC_CHAIN,
+	KNOT_DNSSEC_ENSEC3_OPTOUT,
+
+	/* Yparser errors. */
+	KNOT_YP_ECHAR_TAB,
+	KNOT_YP_EINVAL_ITEM,
+	KNOT_YP_EINVAL_ID,
+	KNOT_YP_EINVAL_DATA,
+	KNOT_YP_EINVAL_INDENT,
+	KNOT_YP_ENOTSUP_DATA,
+	KNOT_YP_ENOTSUP_ID,
+	KNOT_YP_ENODATA,
+	KNOT_YP_ENOID,
+
+	/* Configuration errors. */
+	KNOT_CONF_ENOTINIT,
+	KNOT_CONF_EVERSION,
+	KNOT_CONF_EREDEFINE,
+
+	/* Transaction errors. */
+	KNOT_TXN_EEXISTS,
+	KNOT_TXN_ENOTEXISTS,
+
+	/* DNSSEC errors. */
+	KNOT_INVALID_PUBLIC_KEY,
+	KNOT_INVALID_PRIVATE_KEY,
+	KNOT_INVALID_KEY_ALGORITHM,
+	KNOT_INVALID_KEY_SIZE,
+	KNOT_INVALID_KEY_ID,
+	KNOT_INVALID_KEY_NAME,
+	KNOT_NO_PUBLIC_KEY,
+	KNOT_NO_PRIVATE_KEY,
+	KNOT_NO_READY_KEY,
+
+	KNOT_ERROR_MAX = -501
+};
+
+/*!
+ * \brief Map POSIX errno code to Knot error code.
+ *
+ * \param code       Errno code to transform (set -1 to use the current errno).
+ * \param dflt_error Default return value, if code is unknown.
+ *
+ * \return Mapped errno or the value of dflt_error if unknown.
+ */
+inline static int knot_map_errno_code_def(int code, int dflt_error)
+{
+	if (code < 0) {
+		code = errno;
+	}
+
+	typedef struct {
+		int errno_code;
+		int libknot_code;
+	} err_table_t;
+
+	#define ERR_ITEM(name) { name, KNOT_##name }
+	static const err_table_t errno_to_errcode[] = {
+		ERR_ITEM(ENOMEM),
+		ERR_ITEM(EINVAL),
+		ERR_ITEM(ENOTSUP),
+		ERR_ITEM(EBUSY),
+		ERR_ITEM(EAGAIN),
+		ERR_ITEM(ENOBUFS),
+		ERR_ITEM(EMFILE),
+		ERR_ITEM(ENFILE),
+		ERR_ITEM(EACCES),
+		ERR_ITEM(EISCONN),
+		ERR_ITEM(ECONNREFUSED),
+		ERR_ITEM(EALREADY),
+		ERR_ITEM(ECONNRESET),
+		ERR_ITEM(ECONNABORTED),
+		ERR_ITEM(ENETRESET),
+		ERR_ITEM(EHOSTUNREACH),
+		ERR_ITEM(ENETUNREACH),
+		ERR_ITEM(EHOSTDOWN),
+		ERR_ITEM(ENETDOWN),
+		ERR_ITEM(EADDRINUSE),
+		ERR_ITEM(ENOENT),
+		ERR_ITEM(EEXIST),
+		ERR_ITEM(ERANGE),
+		ERR_ITEM(EADDRNOTAVAIL),
+
+		/* Terminator - the value isn't used. */
+		{ 0, KNOT_ERRNO_ERROR }
+	};
+	#undef ERR_ITEM
+
+	const err_table_t *err = errno_to_errcode;
+
+	while (err->errno_code != 0 && err->errno_code != code) {
+		err++;
+	}
+
+	return err->errno_code != 0 ? err->libknot_code : dflt_error;
+}
+
+/*!
+ * \brief Map POSIX errno code to Knot error code.
+ *
+ * \param code Errno code to transform (set -1 to use the current errno).
+ *
+ * \return Mapped errno or KNOT_ERRNO_ERROR if unknown.
+ */
+inline static int knot_map_errno_code(int code)
+{
+	return knot_map_errno_code_def(code, KNOT_ERRNO_ERROR);
+}
+
+/*!
+ * \brief Get a POSIX errno mapped to Knot error code.
+ *
+ * \param dflt_error Default return value, if code is unknown.
+ *
+ * \return Mapped errno.
+ */
+inline static int knot_map_errno_def(int dflt_error)
+{
+	return knot_map_errno_code_def(-1, dflt_error);
+}
+
+/*!
+ * \brief Get a POSIX errno mapped to Knot error code.
+ *
+ * \return Mapped errno or KNOT_ERRNO_ERROR if unknown.
+ */
+inline static int knot_map_errno(void)
+{
+	return knot_map_errno_code_def(-1, KNOT_ERRNO_ERROR);
+}
+
+/*! @} */
diff --git a/src/libknot/error.c b/src/libknot/error.c
new file mode 100644
index 0000000..352acd3
--- /dev/null
+++ b/src/libknot/error.c
@@ -0,0 +1,239 @@
+/*  Copyright (C) 2022 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 <limits.h>
+#include <lmdb.h>
+
+#include "libknot/attribute.h"
+#include "libknot/error.h"
+#include "libdnssec/error.h"
+
+struct error {
+	int code;
+	const char *message;
+};
+
+static const struct error errors[] = {
+	{ KNOT_EOK, "OK" },
+
+	/* Directly mapped error codes. */
+	{ KNOT_ENOMEM,        "not enough memory" },
+	{ KNOT_EINVAL,        "invalid parameter" },
+	{ KNOT_ENOTSUP,       "operation not supported" },
+	{ KNOT_EBUSY,         "requested resource is busy" },
+	{ KNOT_EAGAIN,        "OS lacked necessary resources" },
+	{ KNOT_ENOBUFS,       "no buffers" },
+	{ KNOT_EMFILE,        "too many open files" },
+	{ KNOT_ENFILE,        "too many open files in system" },
+	{ KNOT_EACCES,        "operation not permitted" },
+	{ KNOT_EISCONN,       "already connected" },
+	{ KNOT_ECONNREFUSED,  "connection refused" },
+	{ KNOT_EALREADY,      "operation already in progress" },
+	{ KNOT_ECONNRESET,    "connection reset by peer" },
+	{ KNOT_ECONNABORTED,  "connection aborted" },
+	{ KNOT_ENETRESET,     "connection aborted by network" },
+	{ KNOT_EHOSTUNREACH,  "host is unreachable" },
+	{ KNOT_ENETUNREACH,   "network is unreachable" },
+	{ KNOT_EHOSTDOWN,     "host is down" },
+	{ KNOT_ENETDOWN,      "network is down" },
+	{ KNOT_EADDRINUSE,    "address already in use" },
+	{ KNOT_ENOENT,        "not exists" },
+	{ KNOT_EEXIST,        "already exists" },
+	{ KNOT_ERANGE,        "value is out of range" },
+	{ KNOT_EADDRNOTAVAIL, "address is not available" },
+	{ KNOT_ENOTDIR,       "not a directory" },
+
+	{ KNOT_ERRNO_ERROR,   "unknown system error" },
+
+	/* General errors. */
+	{ KNOT_ERROR,        "failed" },
+	{ KNOT_EPARSEFAIL,   "parser failed" },
+	{ KNOT_ESEMCHECK,    "semantic check" },
+	{ KNOT_EUPTODATE,    "zone is up-to-date" },
+	{ KNOT_EFEWDATA,     "not enough data to parse" },
+	{ KNOT_ESPACE,       "not enough space provided" },
+	{ KNOT_EMALF,        "malformed data" },
+	{ KNOT_ENSEC3PAR,    "missing or wrong NSEC3PARAM record" },
+	{ KNOT_ENSEC3CHAIN,  "missing or wrong NSEC3 chain in the zone" },
+	{ KNOT_EOUTOFZONE,   "name does not belong to the zone" },
+	{ KNOT_EZONEINVAL,   "invalid zone file" },
+	{ KNOT_ENOZONE,      "no such zone found" },
+	{ KNOT_ENONODE,      "no such node in zone found" },
+	{ KNOT_ENORECORD,    "no such record in zone found" },
+	{ KNOT_EISRECORD,    "such record already exists in zone" },
+	{ KNOT_ENOMASTER,    "no usable master" },
+	{ KNOT_EPREREQ,      "UPDATE prerequisite not met" },
+	{ KNOT_ETTL,         "TTL mismatch" },
+	{ KNOT_ENOTTL,       "no TTL specified" },
+	{ KNOT_ENOXFR,       "transfer was not sent" },
+	{ KNOT_EDENIED,      "not allowed" },
+	{ KNOT_ECONN,        "connection reset" },
+	{ KNOT_ETIMEOUT,     "connection timeout" },
+	{ KNOT_ENODIFF,      "cannot create zone diff" },
+	{ KNOT_ENOTSIG,      "expected a TSIG or SIG(0)" },
+	{ KNOT_ELIMIT,       "exceeded limit" },
+	{ KNOT_EZONESIZE,    "zone size exceeded" },
+	{ KNOT_EOF,          "end of file" },
+	{ KNOT_ESYSTEM,      "system error" },
+	{ KNOT_EFILE,        "file error" },
+	{ KNOT_ESOAINVAL,    "SOA mismatch" },
+	{ KNOT_ETRAIL,       "trailing data" },
+	{ KNOT_EPROCESSING,  "processing error" },
+	{ KNOT_EPROGRESS,    "in progress" },
+	{ KNOT_ELOOP,        "loop detected" },
+	{ KNOT_EPROGRAM,     "program not loaded" },
+	{ KNOT_EFD,          "file descriptor error" },
+	{ KNOT_ENOPARAM,     "missing parameter" },
+	{ KNOT_EXPARAM,      "parameter conflict" },
+	{ KNOT_EEMPTYZONE,   "zone is empty" },
+	{ KNOT_ENODB,        "database does not exist" },
+	{ KNOT_EUNREACH,     "remote known to be unreachable" },
+
+	{ KNOT_GENERAL_ERROR, "unknown general error" },
+
+	/* Control states. */
+	{ KNOT_CTL_ESTOP,     "stopping server" },
+	{ KNOT_CTL_EZONE,     "operation failed for some zones" },
+
+	/* Network errors. */
+	{ KNOT_NET_EADDR,    "bad address or host name" },
+	{ KNOT_NET_ESOCKET,  "can't create socket" },
+	{ KNOT_NET_ECONNECT, "can't connect" },
+	{ KNOT_NET_ESEND,    "can't send data" },
+	{ KNOT_NET_ERECV,    "can't receive data" },
+	{ KNOT_NET_ETIMEOUT, "network timeout" },
+
+	/* Encoding errors. */
+	{ KNOT_BASE64_ESIZE,    "invalid base64 string length" },
+	{ KNOT_BASE64_ECHAR,    "invalid base64 character" },
+	{ KNOT_BASE32HEX_ESIZE, "invalid base32hex string length" },
+	{ KNOT_BASE32HEX_ECHAR, "invalid base32hex character" },
+
+	/* TSIG errors. */
+	{ KNOT_TSIG_EBADSIG,   "failed to verify TSIG" },
+	{ KNOT_TSIG_EBADKEY,   "TSIG key not recognized or invalid" },
+	{ KNOT_TSIG_EBADTIME,  "TSIG out of time window" },
+	{ KNOT_TSIG_EBADTRUNC, "TSIG bad truncation" },
+
+	/* DNSSEC errors. */
+	{ KNOT_DNSSEC_ENOKEY,          "no keys for signing" },
+	{ KNOT_DNSSEC_EMISSINGKEYTYPE, "missing active KSK or ZSK" },
+	{ KNOT_DNSSEC_ENOSIG,          "no valid signature for a record" },
+	{ KNOT_DNSSEC_ENONSEC,         "missing NSEC(3) record" },
+	{ KNOT_DNSSEC_ENSEC_BITMAP,    "wrong NSEC(3) bitmap" },
+	{ KNOT_DNSSEC_ENSEC_CHAIN,     "inconsistent NSEC(3) chain" },
+	{ KNOT_DNSSEC_ENSEC3_OPTOUT,   "wrong NSEC3 opt-out" },
+
+	/* Yparser errors. */
+	{ KNOT_YP_ECHAR_TAB,     "tabulator character is not allowed" },
+	{ KNOT_YP_EINVAL_ITEM,   "invalid item" },
+	{ KNOT_YP_EINVAL_ID,     "invalid identifier" },
+	{ KNOT_YP_EINVAL_DATA,   "invalid value" },
+	{ KNOT_YP_EINVAL_INDENT, "invalid indentation" },
+	{ KNOT_YP_ENOTSUP_DATA,  "value not supported" },
+	{ KNOT_YP_ENOTSUP_ID,    "identifier not supported" },
+	{ KNOT_YP_ENODATA,       "missing value" },
+	{ KNOT_YP_ENOID,         "missing identifier" },
+
+	/* Configuration errors. */
+	{ KNOT_CONF_ENOTINIT,  "config DB not initialized" },
+	{ KNOT_CONF_EVERSION,  "invalid config DB version" },
+	{ KNOT_CONF_EREDEFINE, "duplicate identifier" },
+
+	/* Transaction errors. */
+	{ KNOT_TXN_EEXISTS,    "too many transactions" },
+	{ KNOT_TXN_ENOTEXISTS, "no active transaction" },
+
+	/* DNSSEC errors. */
+	{ KNOT_INVALID_PUBLIC_KEY,    "invalid public key" },
+	{ KNOT_INVALID_PRIVATE_KEY,   "invalid private key" },
+	{ KNOT_INVALID_KEY_ALGORITHM, "invalid key algorithm" },
+	{ KNOT_INVALID_KEY_SIZE,      "invalid key size" },
+	{ KNOT_INVALID_KEY_ID,        "invalid key ID" },
+	{ KNOT_INVALID_KEY_NAME,      "invalid key name" },
+	{ KNOT_NO_PUBLIC_KEY,         "no public key" },
+	{ KNOT_NO_PRIVATE_KEY,        "no private key" },
+	{ KNOT_NO_READY_KEY,          "no key ready for submission" },
+
+	/* Terminator */
+	{ KNOT_ERROR, NULL }
+};
+
+/*!
+ * \brief Lookup error message by error code.
+ */
+static const char *lookup_message(int code)
+{
+	for (const struct error *e = errors; e->message; e++) {
+		if (e->code == code) {
+			return e->message;
+		}
+	}
+
+	return NULL;
+}
+
+_public_
+int knot_error_from_libdnssec(int libdnssec_errcode)
+{
+	switch (libdnssec_errcode) {
+	case DNSSEC_ERROR:
+		return KNOT_ERROR;
+	case DNSSEC_MALFORMED_DATA:
+		return KNOT_EMALF;
+	case DNSSEC_NOT_FOUND:
+		return KNOT_ENOENT;
+	case DNSSEC_NO_PUBLIC_KEY:
+	case DNSSEC_NO_PRIVATE_KEY:
+		return KNOT_DNSSEC_ENOKEY;
+	// EOK, EINVAL, ENOMEM and ENOENT are identical, no need to translate
+	case DNSSEC_INVALID_PUBLIC_KEY ... DNSSEC_INVALID_KEY_NAME:
+		return libdnssec_errcode
+		       - DNSSEC_INVALID_PUBLIC_KEY + KNOT_INVALID_PUBLIC_KEY;
+	default:
+		return libdnssec_errcode;
+	}
+}
+
+_public_
+const char *knot_strerror(int code)
+{
+	const char *msg;
+
+	switch (code) {
+	case INT_MIN: // Cannot convert to a positive value.
+		code = KNOT_ERROR;
+		// FALLTHROUGH
+	case KNOT_ERROR_MIN ... KNOT_EOK:
+		msg = lookup_message(code); break;
+	case DNSSEC_ERROR_MIN ... DNSSEC_ERROR_MAX:
+		msg = dnssec_strerror(code); break;
+	case MDB_KEYEXIST ... MDB_LAST_ERRCODE:
+		msg = mdb_strerror(code); break;
+	default:
+		msg = NULL;
+	}
+
+	if (msg != NULL) {
+		return msg;
+	} else {
+		// strerror_r would be better but it requires thread local storage.
+		return strerror(abs(code));
+	}
+}
diff --git a/src/libknot/error.h b/src/libknot/error.h
new file mode 100644
index 0000000..4403497
--- /dev/null
+++ b/src/libknot/error.h
@@ -0,0 +1,50 @@
+/*  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/>.
+ */
+
+/*!
+* \file
+*
+* \brief Error codes and function for getting error message.
+*
+* \addtogroup libknot
+* @{
+*/
+
+#pragma once
+
+#include "libknot/errcode.h"
+
+/*!
+ * \brief Returns error message for the given error code.
+ *
+ * \param code Error code.
+ *
+ * \return String containing the error message.
+ */
+const char *knot_strerror(int code);
+
+/*!
+ * \brief Translates error code from libdnssec into libknot.
+ *
+ * This is just temporary until everything from libdnssec moved to libknot.
+ *
+ * \param libdnssec_errcode Error code from libdnssec
+ *
+ * \return Error code.
+ */
+int knot_error_from_libdnssec(int libdnssec_errcode);
+
+/*! @} */
diff --git a/src/libknot/libknot.h b/src/libknot/libknot.h
new file mode 100644
index 0000000..f62c2c7
--- /dev/null
+++ b/src/libknot/libknot.h
@@ -0,0 +1,72 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Convenience header for including whole library.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/version.h"
+#include "libknot/attribute.h"
+#include "libknot/cookies.h"
+#include "libknot/codes.h"
+#include "libknot/consts.h"
+#include "libknot/descriptor.h"
+#include "libknot/dname.h"
+#include "libknot/dynarray.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "libknot/error.h"
+#include "libknot/lookup.h"
+#include "libknot/mm_ctx.h"
+#include "libknot/rdata.h"
+#include "libknot/rdataset.h"
+#include "libknot/rrset-dump.h"
+#include "libknot/rrset.h"
+#include "libknot/tsig-op.h"
+#include "libknot/tsig.h"
+#include "libknot/control/control.h"
+#include "libknot/db/db.h"
+#include "libknot/db/db_lmdb.h"
+#include "libknot/db/db_trie.h"
+#include "libknot/packet/compr.h"
+#include "libknot/packet/pkt.h"
+#include "libknot/packet/rrset-wire.h"
+#include "libknot/packet/wire.h"
+#include "libknot/probe/data.h"
+#include "libknot/probe/probe.h"
+#include "libknot/rrtype/dnskey.h"
+#include "libknot/rrtype/ds.h"
+#include "libknot/rrtype/naptr.h"
+#include "libknot/rrtype/nsec.h"
+#include "libknot/rrtype/nsec3.h"
+#include "libknot/rrtype/nsec3param.h"
+#include "libknot/rrtype/opt.h"
+#include "libknot/rrtype/rdname.h"
+#include "libknot/rrtype/rrsig.h"
+#include "libknot/rrtype/soa.h"
+#include "libknot/rrtype/svcb.h"
+#include "libknot/rrtype/tsig.h"
+#include "libknot/rrtype/zonemd.h"
+#include "libknot/wire.h"
+
+/*! @} */
diff --git a/src/libknot/lookup.h b/src/libknot/lookup.h
new file mode 100644
index 0000000..8599aa3
--- /dev/null
+++ b/src/libknot/lookup.h
@@ -0,0 +1,89 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief A general purpose lookup table.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include <string.h>
+#include <strings.h>
+
+/*!
+ * \brief A general purpose lookup table.
+ */
+typedef struct knot_lookup {
+	int id;
+	const char *name;
+} knot_lookup_t;
+
+/*!
+ * \brief Looks up the given name in the lookup table.
+ *
+ * \param table Lookup table.
+ * \param name Name to look up.
+ *
+ * \return Item in the lookup table with the given name or NULL if no such is
+ *         present.
+ */
+inline static const knot_lookup_t *knot_lookup_by_name(const knot_lookup_t *table, const char *name)
+{
+	if (table == NULL || name == NULL) {
+		return NULL;
+	}
+
+	while (table->name != NULL) {
+		if (strcasecmp(name, table->name) == 0) {
+			return table;
+		}
+		table++;
+	}
+
+	return NULL;
+}
+
+/*!
+ * \brief Looks up the given id in the lookup table.
+ *
+ * \param table Lookup table.
+ * \param id ID to look up.
+ *
+ * \return Item in the lookup table with the given id or NULL if no such is
+ *         present.
+ */
+inline static const knot_lookup_t *knot_lookup_by_id(const knot_lookup_t *table, int id)
+{
+	if (table == NULL) {
+		return NULL;
+	}
+
+	while (table->name != NULL) {
+		if (table->id == id) {
+			return table;
+		}
+		table++;
+	}
+
+	return NULL;
+}
+
+/*! @} */
diff --git a/src/libknot/mm_ctx.h b/src/libknot/mm_ctx.h
new file mode 100644
index 0000000..8f0544c
--- /dev/null
+++ b/src/libknot/mm_ctx.h
@@ -0,0 +1,41 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Memory allocation context.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+
+/* Memory allocation function prototypes. */
+typedef void* (*knot_mm_alloc_t)(void *ctx, size_t len);
+typedef void (*knot_mm_free_t)(void *p);
+
+/*! \brief Memory allocation context. */
+typedef struct knot_mm {
+	void *ctx; /* \note Must be first */
+	knot_mm_alloc_t alloc;
+	knot_mm_free_t free;
+} knot_mm_t;
+
+/*! @} */
diff --git a/src/libknot/packet/compr.h b/src/libknot/packet/compr.h
new file mode 100644
index 0000000..ea14d64
--- /dev/null
+++ b/src/libknot/packet/compr.h
@@ -0,0 +1,101 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Name compression API.
+ *
+ * \addtogroup pkt
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "libknot/packet/wire.h"
+
+/*! \brief Compression hint type. */
+enum knot_compr_hint {
+	KNOT_COMPR_HINT_NONE    = 0, /* No hint. */
+	KNOT_COMPR_HINT_NOCOMP  = 1, /* Don't compress. */
+	KNOT_COMPR_HINT_QNAME   = KNOT_WIRE_HEADER_SIZE /* Name is QNAME. */
+};
+
+/*! \brief Compression hint array offsets. */
+enum knot_compr_offset {
+	KNOT_COMPR_HINT_OWNER = 0,  /* First element in the array is RR owner. */
+	KNOT_COMPR_HINT_RDATA = 1,  /* First name in RDATA is at offset 1. */
+	KNOT_COMPR_HINT_COUNT = 16  /* Maximum number of stored hints per-RR. */
+};
+
+/*
+ * \note A little bit about how compression hints work.
+ *
+ * We're storing a RRSet say 'abcd. CNAME [0]net. [1]com.' (owner=abcd. 2 RRs).
+ * The owner 'abcd.' is same for both RRs, we put it at the offset 0 in rrinfo.compress_ptr
+ * The names 'net.' and 'com.' are in the RDATA, therefore go to offsets 1 and 2.
+ * Now this is useful when solving additionals for example, because we can scan
+ * rrinfo for this RRSet and we know that 'net.' name is at the hint 1 and that leads
+ * to packet position N. With that, we just put the pointer in without any calculation.
+ * This is also useful for positive answers, where we know the RRSet owner is always QNAME.
+ * All in all, we just remember the positions of written domain names.
+ */
+
+/*! \brief Additional information about RRSet position and compression hints. */
+typedef struct {
+	uint16_t pos;   /* RRSet position in the packet. */
+	uint16_t flags; /* RRSet flags. */
+	uint16_t compress_ptr[KNOT_COMPR_HINT_COUNT]; /* Array of compr. ptr hints. */
+} knot_rrinfo_t;
+
+/*!
+ * \brief Name compression context.
+ */
+typedef struct knot_compr {
+	uint8_t *wire;          /* Packet wireformat. */
+	knot_rrinfo_t *rrinfo;  /* Hints for current RRSet. */
+	struct {
+		uint16_t pos;   /* Position of current suffix. */
+		uint8_t labels; /* Label count of the suffix. */
+	} suffix;
+} knot_compr_t;
+
+/*!
+ * \brief Retrieve compression hint from given offset.
+ */
+static inline uint16_t knot_compr_hint(const knot_rrinfo_t *info, uint16_t hint_id)
+{
+	if (hint_id < KNOT_COMPR_HINT_COUNT) {
+		return info->compress_ptr[hint_id];
+	} else {
+		return KNOT_COMPR_HINT_NONE;
+	}
+}
+
+/*!
+ * \brief Store compression hint for given offset.
+ */
+static inline void knot_compr_hint_set(knot_rrinfo_t *info, uint16_t hint_id,
+                                       uint16_t val, uint16_t len)
+{
+	if ((hint_id < KNOT_COMPR_HINT_COUNT) && (val + len < KNOT_WIRE_PTR_MAX)) {
+		info->compress_ptr[hint_id] = val;
+	}
+}
+
+/*! @} */
diff --git a/src/libknot/packet/pkt.c b/src/libknot/packet/pkt.c
new file mode 100644
index 0000000..728bb3e
--- /dev/null
+++ b/src/libknot/packet/pkt.c
@@ -0,0 +1,837 @@
+/*  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/>.
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdbool.h>
+
+#include "libknot/attribute.h"
+#include "libknot/packet/pkt.h"
+#include "libknot/codes.h"
+#include "libknot/descriptor.h"
+#include "libknot/errcode.h"
+#include "libknot/rrtype/tsig.h"
+#include "libknot/tsig-op.h"
+#include "libknot/packet/wire.h"
+#include "libknot/packet/rrset-wire.h"
+#include "libknot/wire.h"
+#include "contrib/mempattern.h"
+#include "contrib/wire_ctx.h"
+
+/*! \brief Packet RR array growth step. */
+#define NEXT_RR_ALIGN 16
+#define NEXT_RR_COUNT(count) (((count) / NEXT_RR_ALIGN + 1) * NEXT_RR_ALIGN)
+
+/*! \brief Scan packet for RRSet existence. */
+static bool pkt_contains(const knot_pkt_t *packet, const knot_rrset_t *rrset)
+{
+	assert(packet);
+	assert(rrset);
+
+	for (int i = 0; i < packet->rrset_count; ++i) {
+		const uint16_t type = packet->rr[i].type;
+		const knot_rdata_t *data = packet->rr[i].rrs.rdata;
+		if (type == rrset->type && data == rrset->rrs.rdata) {
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/*! \brief Free all RRSets and reset RRSet count. */
+static void pkt_free_data(knot_pkt_t *pkt)
+{
+	assert(pkt);
+
+	/* Free RRSets if applicable. */
+	for (uint16_t i = 0; i < pkt->rrset_count; ++i) {
+		if (pkt->rr_info[i].flags & KNOT_PF_FREE) {
+			knot_rrset_clear(&pkt->rr[i], &pkt->mm);
+		}
+	}
+	pkt->rrset_count = 0;
+
+	/* Free EDNS option positions. */
+	mm_free(&pkt->mm, pkt->edns_opts);
+	pkt->edns_opts = 0;
+}
+
+/*! \brief Allocate new wireformat of given length, assuming *pkt is zeroed. */
+static int pkt_wire_alloc(knot_pkt_t *pkt, uint16_t len)
+{
+	assert(pkt);
+
+	if (len < KNOT_WIRE_HEADER_SIZE) {
+		return KNOT_ERANGE;
+	}
+
+	pkt->wire = mm_alloc(&pkt->mm, len);
+	if (pkt->wire == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	pkt->flags |= KNOT_PF_FREE;
+	pkt->max_size = len;
+
+	/* Reset to header size. */
+	pkt->size = KNOT_WIRE_HEADER_SIZE;
+	memset(pkt->wire, 0, pkt->size);
+
+	return KNOT_EOK;
+}
+
+/*! \brief Set packet wireformat to an existing memory. */
+static void pkt_wire_set(knot_pkt_t *pkt, void *wire, uint16_t len)
+{
+	assert(pkt);
+
+	pkt->wire = wire;
+	pkt->size = pkt->max_size = len;
+	pkt->parsed = 0;
+}
+
+/*! \brief Calculate remaining size in the packet. */
+static uint16_t pkt_remaining(knot_pkt_t *pkt)
+{
+	assert(pkt);
+
+	return pkt->max_size - pkt->size - pkt->reserved;
+}
+
+/*! \brief Return RR count for given section (from wire xxCOUNT in header). */
+static uint16_t pkt_rr_wirecount(knot_pkt_t *pkt, knot_section_t section_id)
+{
+	assert(pkt);
+	switch (section_id) {
+	case KNOT_ANSWER:     return knot_wire_get_ancount(pkt->wire);
+	case KNOT_AUTHORITY:  return knot_wire_get_nscount(pkt->wire);
+	case KNOT_ADDITIONAL: return knot_wire_get_arcount(pkt->wire);
+	default: assert(0);   return 0;
+	}
+}
+
+/*! \brief Update RR count for given section (wire xxCOUNT in header). */
+static void pkt_rr_wirecount_add(knot_pkt_t *pkt, knot_section_t section_id,
+                                 int16_t val)
+{
+	assert(pkt);
+	switch (section_id) {
+	case KNOT_ANSWER:     knot_wire_add_ancount(pkt->wire, val); break;
+	case KNOT_AUTHORITY:  knot_wire_add_nscount(pkt->wire, val); break;
+	case KNOT_ADDITIONAL: knot_wire_add_arcount(pkt->wire, val); break;
+	}
+}
+
+/*! \brief Reserve enough space in the RR arrays. */
+static int pkt_rr_array_alloc(knot_pkt_t *pkt, uint16_t count)
+{
+	/* Enough space. */
+	if (pkt->rrset_allocd >= count) {
+		return KNOT_EOK;
+	}
+
+	/* Allocate rr_info and rr fields to next size. */
+	size_t next_size = NEXT_RR_COUNT(count);
+	knot_rrinfo_t *rr_info = mm_alloc(&pkt->mm, sizeof(knot_rrinfo_t) * next_size);
+	if (rr_info == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	knot_rrset_t *rr = mm_alloc(&pkt->mm, sizeof(knot_rrset_t) * next_size);
+	if (rr == NULL) {
+		mm_free(&pkt->mm, rr_info);
+		return KNOT_ENOMEM;
+	}
+
+	/* Copy and free the old data, if any. */
+	if (pkt->rrset_allocd > 0) {
+		memcpy(rr_info, pkt->rr_info, pkt->rrset_allocd * sizeof(knot_rrinfo_t));
+		memcpy(rr, pkt->rr, pkt->rrset_allocd * sizeof(knot_rrset_t));
+		mm_free(&pkt->mm, pkt->rr);
+		mm_free(&pkt->mm, pkt->rr_info);
+	}
+	pkt->rr = rr;
+	pkt->rr_info = rr_info;
+	pkt->rrset_allocd = next_size;
+
+	return KNOT_EOK;
+}
+
+static void compr_clear(knot_compr_t *compr)
+{
+	compr->rrinfo = NULL;
+	compr->suffix.pos = 0;
+	compr->suffix.labels = 0;
+}
+
+/*! \brief Clear the packet and switch wireformat pointers (possibly allocate new). */
+static int pkt_init(knot_pkt_t *pkt, void *wire, uint16_t len, knot_mm_t *mm)
+{
+	assert(pkt);
+
+	memset(pkt, 0, offsetof(knot_pkt_t, lower_qname));
+	pkt->lower_qname[0] = '\0';
+
+	/* No data to free, set memory context. */
+	memcpy(&pkt->mm, mm, sizeof(knot_mm_t));
+
+	/* Initialize wire. */
+	int ret = KNOT_EOK;
+	if (wire == NULL) {
+		ret = pkt_wire_alloc(pkt, len);
+	} else {
+		pkt_wire_set(pkt, wire, len);
+	}
+
+	/* Initialize compression context (zeroed above). */
+	pkt->compr.wire = pkt->wire;
+
+	return ret;
+}
+
+/*! \brief Reset packet parse state. */
+static void sections_reset(knot_pkt_t *pkt)
+{
+	pkt->current = KNOT_ANSWER;
+	memset(pkt->sections, 0, sizeof(pkt->sections));
+	(void)knot_pkt_begin(pkt, KNOT_ANSWER);
+}
+
+/*! \brief Allocate new packet using memory context. */
+static knot_pkt_t *pkt_new_mm(void *wire, uint16_t len, knot_mm_t *mm)
+{
+	assert(mm);
+
+	knot_pkt_t *pkt = mm_alloc(mm, sizeof(knot_pkt_t));
+	if (pkt == NULL) {
+		return NULL;
+	}
+
+	if (pkt_init(pkt, wire, len, mm) != KNOT_EOK) {
+		mm_free(mm, pkt);
+		return NULL;
+	}
+
+	return pkt;
+}
+
+_public_
+knot_pkt_t *knot_pkt_new(void *wire, uint16_t len, knot_mm_t *mm)
+{
+	/* Default memory allocator if NULL. */
+	knot_mm_t _mm;
+	if (mm == NULL) {
+		mm_ctx_init(&_mm);
+		mm = &_mm;
+	}
+
+	return pkt_new_mm(wire, len, mm);
+}
+
+static int append_tsig(knot_pkt_t *dst, const knot_pkt_t *src)
+{
+	/* Check if a wire TSIG is available. */
+	if (src->tsig_wire.pos != NULL) {
+		if (dst->max_size < src->size + src->tsig_wire.len) {
+			return KNOT_ESPACE;
+		}
+		memcpy(dst->wire + dst->size, src->tsig_wire.pos,
+		       src->tsig_wire.len);
+		dst->size += src->tsig_wire.len;
+
+		/* Increment arcount. */
+		knot_wire_set_arcount(dst->wire,
+		                      knot_wire_get_arcount(dst->wire) + 1);
+	} else {
+		return knot_tsig_append(dst->wire, &dst->size, dst->max_size,
+		                        src->tsig_rr);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_pkt_copy(knot_pkt_t *dst, const knot_pkt_t *src)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (dst->max_size < src->size) {
+		return KNOT_ESPACE;
+	}
+	memcpy(dst->wire, src->wire, src->size);
+	dst->size = src->size;
+
+	/* Append TSIG record. */
+	if (src->tsig_rr) {
+		int ret = append_tsig(dst, src);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	/* Invalidate arrays. */
+	dst->rr = NULL;
+	dst->rr_info = NULL;
+	dst->rrset_count = 0;
+	dst->rrset_allocd = 0;
+
+	/* @note This could be done more effectively if needed. */
+	return knot_pkt_parse(dst, 0);
+}
+
+static void payload_clear(knot_pkt_t *pkt)
+{
+	assert(pkt);
+
+	/* Keep question. */
+	pkt->parsed = 0;
+	pkt->reserved = 0;
+
+	/* Free RRSets if applicable. */
+	pkt_free_data(pkt);
+
+	/* Reset sections. */
+	sections_reset(pkt);
+
+	/* Reset special types. */
+	pkt->opt_rr = NULL;
+	pkt->tsig_rr = NULL;
+
+	/* Reset TSIG wire reference. */
+	pkt->tsig_wire.pos = NULL;
+	pkt->tsig_wire.len = 0;
+}
+
+_public_
+int knot_pkt_init_response(knot_pkt_t *pkt, const knot_pkt_t *query)
+{
+	if (pkt == NULL || query == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Header + question size. */
+	size_t base_size = KNOT_WIRE_HEADER_SIZE + knot_pkt_question_size(query);
+	if (base_size > pkt->max_size) {
+		return KNOT_ESPACE;
+	}
+
+	pkt->size = base_size;
+	memcpy(pkt->wire, query->wire, base_size);
+
+	/* Copy lowercased QNAME. */
+	pkt->qname_size = query->qname_size;
+	if (query->qname_size == 0) {
+		/* Reset question count if malformed. */
+		knot_wire_set_qdcount(pkt->wire, 0);
+	}
+	memcpy(pkt->lower_qname, query->lower_qname, pkt->qname_size);
+
+	/* Update flags and section counters. */
+	knot_wire_set_ancount(pkt->wire, 0);
+	knot_wire_set_nscount(pkt->wire, 0);
+	knot_wire_set_arcount(pkt->wire, 0);
+
+	knot_wire_set_qr(pkt->wire);
+	knot_wire_clear_tc(pkt->wire);
+	knot_wire_clear_ad(pkt->wire);
+	knot_wire_clear_ra(pkt->wire);
+	knot_wire_clear_aa(pkt->wire);
+	knot_wire_clear_z(pkt->wire);
+
+	/* Clear payload. */
+	payload_clear(pkt);
+
+	/* Clear compression context. */
+	compr_clear(&pkt->compr);
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_pkt_clear(knot_pkt_t *pkt)
+{
+	if (pkt == NULL) {
+		return;
+	}
+
+	/* Reset to header size. */
+	pkt->size = KNOT_WIRE_HEADER_SIZE;
+	memset(pkt->wire, 0, pkt->size);
+
+	/* Clear payload. */
+	payload_clear(pkt);
+
+	/* Clear compression context. */
+	compr_clear(&pkt->compr);
+
+	/* Initialize lowercased QNAME. */
+	pkt->lower_qname[0] = '\0';
+}
+
+_public_
+void knot_pkt_free(knot_pkt_t *pkt)
+{
+	if (pkt == NULL) {
+		return;
+	}
+
+	/* Free temporary RRSets. */
+	pkt_free_data(pkt);
+
+	/* Free RR/RR info arrays. */
+	mm_free(&pkt->mm, pkt->rr);
+	mm_free(&pkt->mm, pkt->rr_info);
+
+	/* Free the space for wireformat. */
+	if (pkt->flags & KNOT_PF_FREE) {
+		mm_free(&pkt->mm, pkt->wire);
+	}
+
+	mm_free(&pkt->mm, pkt);
+}
+
+_public_
+int knot_pkt_reserve(knot_pkt_t *pkt, uint16_t size)
+{
+	if (pkt == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Reserve extra space (if possible). */
+	if (pkt_remaining(pkt) >= size) {
+		pkt->reserved += size;
+		return KNOT_EOK;
+	} else {
+		return KNOT_ERANGE;
+	}
+}
+
+_public_
+int knot_pkt_reclaim(knot_pkt_t *pkt, uint16_t size)
+{
+	if (pkt == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (pkt->reserved >= size) {
+		pkt->reserved -= size;
+		return KNOT_EOK;
+	} else {
+		return KNOT_ERANGE;
+	}
+}
+
+_public_
+int knot_pkt_begin(knot_pkt_t *pkt, knot_section_t section_id)
+{
+	if (pkt == NULL || section_id < pkt->current) {
+		return KNOT_EINVAL;
+	}
+
+	/* Remember watermark but not on repeated calls. */
+	pkt->sections[section_id].pkt = pkt;
+	if (section_id > pkt->current) {
+		pkt->sections[section_id].pos = pkt->rrset_count;
+	}
+
+	pkt->current = section_id;
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_pkt_put_question(knot_pkt_t *pkt, const knot_dname_t *qname, uint16_t qclass, uint16_t qtype)
+{
+	if (pkt == NULL || qname == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	assert(pkt->size == KNOT_WIRE_HEADER_SIZE);
+	assert(pkt->rrset_count == 0);
+
+	/* Copy name into wire format buffer. */
+	wire_ctx_t wire = wire_ctx_init(pkt->wire, pkt->max_size);
+	wire_ctx_set_offset(&wire, KNOT_WIRE_HEADER_SIZE);
+
+	int qname_len = knot_dname_to_wire(wire.position,
+	                                   qname, wire_ctx_available(&wire));
+	if (qname_len < 0) {
+		return qname_len;
+	}
+	wire_ctx_skip(&wire, qname_len);
+
+	/* Copy QNAME and canonicalize to lowercase. */
+	knot_dname_copy_lower(pkt->lower_qname, qname);
+
+	/* Copy QTYPE & QCLASS */
+	wire_ctx_write_u16(&wire, qtype);
+	wire_ctx_write_u16(&wire, qclass);
+
+	/* Check errors. */
+	if (wire.error != KNOT_EOK) {
+		return wire.error;
+	}
+
+	/* Update question count and sizes. */
+	knot_wire_set_qdcount(pkt->wire, 1);
+	pkt->size = wire_ctx_offset(&wire);
+	pkt->qname_size = qname_len;
+
+	/* Start writing ANSWER. */
+	return knot_pkt_begin(pkt, KNOT_ANSWER);
+}
+
+_public_
+int knot_pkt_put_rotate(knot_pkt_t *pkt, uint16_t compr_hint, const knot_rrset_t *rr,
+                        uint16_t rotate, uint16_t flags)
+{
+	if (pkt == NULL || rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Reserve memory for RR descriptors. */
+	int ret = pkt_rr_array_alloc(pkt, pkt->rrset_count + 1);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Check for double insertion. */
+	if ((flags & KNOT_PF_CHECKDUP) && pkt_contains(pkt, rr)) {
+		return KNOT_EOK;
+	}
+
+	knot_rrinfo_t *rrinfo = &pkt->rr_info[pkt->rrset_count];
+	memset(rrinfo, 0, sizeof(knot_rrinfo_t));
+	rrinfo->pos = pkt->size;
+	rrinfo->flags = flags;
+	rrinfo->compress_ptr[0] = compr_hint;
+	memcpy(pkt->rr + pkt->rrset_count, rr, sizeof(knot_rrset_t));
+
+	/* Disable compression if no QNAME is available. */
+	knot_compr_t *compr = NULL;
+	if (knot_pkt_qname(pkt) != NULL) {
+		/* Initialize compression context if it did not happen yet. */
+		pkt->compr.rrinfo = rrinfo;
+		if (pkt->compr.suffix.pos == 0) {
+			pkt->compr.suffix.pos = KNOT_WIRE_HEADER_SIZE;
+			pkt->compr.suffix.labels =
+				knot_dname_labels(pkt->compr.wire + pkt->compr.suffix.pos,
+				                  pkt->compr.wire);
+		}
+
+		compr = &pkt->compr;
+	}
+
+	uint8_t *pos = pkt->wire + pkt->size;
+	size_t maxlen = pkt_remaining(pkt);
+
+	/* Write RRSet to wireformat. */
+	ret = knot_rrset_to_wire_extra(rr, pos, maxlen, rotate, compr, flags);
+	if (ret < 0) {
+		/* Truncate packet if required. */
+		if (ret == KNOT_ESPACE && !(flags & KNOT_PF_NOTRUNC)) {
+			knot_wire_set_tc(pkt->wire);
+		}
+		return ret;
+	}
+
+	size_t len = ret;
+	uint16_t rr_added = rr->rrs.count;
+
+	/* Keep reference to special types. */
+	if (rr->type == KNOT_RRTYPE_OPT) {
+		pkt->opt_rr = &pkt->rr[pkt->rrset_count];
+	}
+
+	if (rr_added > 0) {
+		pkt->rrset_count += 1;
+		pkt->sections[pkt->current].count += 1;
+		pkt->size += len;
+		pkt_rr_wirecount_add(pkt, pkt->current, rr_added);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_pkt_parse_question(knot_pkt_t *pkt)
+{
+	if (pkt == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Check at least header size. */
+	if (pkt->size < KNOT_WIRE_HEADER_SIZE) {
+		return KNOT_EMALF;
+	}
+
+	/* We have at least some DNS header. */
+	pkt->parsed = KNOT_WIRE_HEADER_SIZE;
+
+	/* Check QD count. */
+	uint16_t qd = knot_wire_get_qdcount(pkt->wire);
+	if (qd > 1) {
+		return KNOT_EMALF;
+	}
+
+	/* No question. */
+	if (qd == 0) {
+		pkt->qname_size = 0;
+		return KNOT_EOK;
+	}
+
+	/* Process question. */
+	int len = knot_dname_wire_check(pkt->wire + pkt->parsed,
+	                                pkt->wire + pkt->size,
+	                                NULL /* No compression in QNAME. */);
+	if (len <= 0) {
+		return KNOT_EMALF;
+	}
+
+	/* Check QCLASS/QTYPE size. */
+	uint16_t question_size = len + 2 * sizeof(uint16_t); /* QCLASS + QTYPE */
+	if (pkt->parsed + question_size > pkt->size) {
+		return KNOT_EMALF;
+	}
+
+	pkt->parsed += question_size;
+	pkt->qname_size = len;
+
+	/* Copy QNAME and canonicalize to lowercase. */
+	knot_dname_copy_lower(pkt->lower_qname, pkt->wire + KNOT_WIRE_HEADER_SIZE);
+
+	return KNOT_EOK;
+}
+
+/*! \brief Check constraints (position, uniqueness, validity) for special types
+ *         (TSIG, OPT).
+ */
+static int check_rr_constraints(knot_pkt_t *pkt, knot_rrset_t *rr, size_t rr_size,
+                                unsigned flags)
+{
+	switch (rr->type) {
+	case KNOT_RRTYPE_TSIG:
+		if (pkt->current != KNOT_ADDITIONAL || pkt->tsig_rr != NULL ||
+		    !knot_tsig_rdata_is_ok(rr)) {
+			return KNOT_EMALF;
+		}
+
+		/* Strip TSIG RR from wireformat and decrease ARCOUNT. */
+		if (!(flags & KNOT_PF_KEEPWIRE)) {
+			pkt->parsed -= rr_size;
+			pkt->size -= rr_size;
+			pkt->tsig_wire.pos = pkt->wire + pkt->parsed;
+			pkt->tsig_wire.len = rr_size;
+			knot_wire_set_arcount(pkt->wire, knot_wire_get_arcount(pkt->wire) - 1);
+		}
+
+		pkt->tsig_rr = rr;
+		break;
+	case KNOT_RRTYPE_OPT:
+		if (pkt->current != KNOT_ADDITIONAL || pkt->opt_rr != NULL ||
+		    knot_edns_get_options(rr, &pkt->edns_opts, &pkt->mm) != KNOT_EOK) {
+			return KNOT_EMALF;
+		}
+
+		pkt->opt_rr = rr;
+		break;
+	default:
+		break;
+	}
+
+	return KNOT_EOK;
+}
+
+static int parse_rr(knot_pkt_t *pkt, unsigned flags)
+{
+	assert(pkt);
+
+	if (pkt->parsed >= pkt->size) {
+		return KNOT_EFEWDATA;
+	}
+
+	/* Reserve memory for RR descriptors. */
+	int ret = pkt_rr_array_alloc(pkt, pkt->rrset_count + 1);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Initialize RR info. */
+	memset(&pkt->rr_info[pkt->rrset_count], 0, sizeof(knot_rrinfo_t));
+	pkt->rr_info[pkt->rrset_count].pos = pkt->parsed;
+	pkt->rr_info[pkt->rrset_count].flags = KNOT_PF_FREE;
+
+	/* Parse wire format. */
+	size_t rr_size = pkt->parsed;
+	knot_rrset_t *rr = &pkt->rr[pkt->rrset_count];
+	ret = knot_rrset_rr_from_wire(pkt->wire, &pkt->parsed, pkt->size,
+	                              rr, &pkt->mm, !(flags & KNOT_PF_NOCANON));
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Calculate parsed RR size from before/after parsing. */
+	rr_size = (pkt->parsed - rr_size);
+
+	/* Update packet RRSet count. */
+	++pkt->rrset_count;
+	++pkt->sections[pkt->current].count;
+
+	/* Check special RRs (OPT and TSIG). */
+	return check_rr_constraints(pkt, rr, rr_size, flags);
+}
+
+static int parse_section(knot_pkt_t *pkt, unsigned flags)
+{
+	assert(pkt);
+
+	uint16_t rr_parsed = 0;
+	uint16_t rr_count = pkt_rr_wirecount(pkt, pkt->current);
+
+	/* Parse all RRs belonging to the section. */
+	for (rr_parsed = 0; rr_parsed < rr_count; ++rr_parsed) {
+		int ret = parse_rr(pkt, flags);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+static int parse_payload(knot_pkt_t *pkt, unsigned flags)
+{
+	assert(pkt);
+	assert(pkt->wire);
+	assert(pkt->size > 0);
+
+	/* Reserve memory in advance to avoid resizing. */
+	size_t rr_count = knot_wire_get_ancount(pkt->wire) +
+	                  knot_wire_get_nscount(pkt->wire) +
+	                  knot_wire_get_arcount(pkt->wire);
+
+	if (rr_count > pkt->size / KNOT_WIRE_RR_MIN_SIZE) {
+		return KNOT_EMALF;
+	}
+
+	int ret = pkt_rr_array_alloc(pkt, rr_count);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	for (knot_section_t i = KNOT_ANSWER; i <= KNOT_ADDITIONAL; ++i) {
+		ret = knot_pkt_begin(pkt, i);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		ret = parse_section(pkt, flags);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	/* TSIG must be last record of AR if present. */
+	const knot_pktsection_t *ar = knot_pkt_section(pkt, KNOT_ADDITIONAL);
+	if (pkt->tsig_rr != NULL) {
+		const knot_rrset_t *last_rr = knot_pkt_rr(ar, ar->count - 1);
+		if (ar->count > 0 && pkt->tsig_rr->rrs.rdata != last_rr->rrs.rdata) {
+			return KNOT_EMALF;
+		}
+	}
+
+	/* Check for trailing garbage. */
+	if (pkt->parsed < pkt->size) {
+		return KNOT_ETRAIL;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_pkt_parse(knot_pkt_t *pkt, unsigned flags)
+{
+	if (pkt == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Reset parse state. */
+	sections_reset(pkt);
+
+	int ret = knot_pkt_parse_question(pkt);
+	if (ret == KNOT_EOK) {
+		ret = parse_payload(pkt, flags);
+	}
+
+	return ret;
+}
+
+_public_
+uint16_t knot_pkt_ext_rcode(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL) {
+		return 0;
+	}
+
+	/* Get header RCODE. */
+	uint16_t rcode = knot_wire_get_rcode(pkt->wire);
+
+	/* Update to extended RCODE if EDNS is available. */
+	if (pkt->opt_rr != NULL) {
+		uint8_t opt_rcode = knot_edns_get_ext_rcode(pkt->opt_rr);
+		rcode = knot_edns_whole_rcode(opt_rcode, rcode);
+	}
+
+	/* Return if not NOTAUTH. */
+	if (rcode != KNOT_RCODE_NOTAUTH) {
+		return rcode;
+	}
+
+	/* Get TSIG RCODE. */
+	uint16_t tsig_rcode = KNOT_RCODE_NOERROR;
+	if (pkt->tsig_rr != NULL) {
+		tsig_rcode = knot_tsig_rdata_error(pkt->tsig_rr);
+	}
+
+	/* Return proper RCODE. */
+	if (tsig_rcode != KNOT_RCODE_NOERROR) {
+		return tsig_rcode;
+	} else {
+		return rcode;
+	}
+}
+
+_public_
+const char *knot_pkt_ext_rcode_name(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL) {
+		return "";
+	}
+
+	uint16_t rcode = knot_pkt_ext_rcode(pkt);
+
+	const knot_lookup_t *item = NULL;
+	if (pkt->tsig_rr != NULL) {
+		item = knot_lookup_by_id(knot_tsig_rcode_names, rcode);
+	}
+	if (item == NULL) {
+		item = knot_lookup_by_id(knot_rcode_names, rcode);
+	}
+
+	return (item != NULL) ? item->name : "";
+}
diff --git a/src/libknot/packet/pkt.h b/src/libknot/packet/pkt.h
new file mode 100644
index 0000000..f5e218f
--- /dev/null
+++ b/src/libknot/packet/pkt.h
@@ -0,0 +1,416 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Structure for holding DNS packet data and metadata.
+ *
+ * \addtogroup pkt
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stdint.h>
+
+#include "libknot/consts.h"
+#include "libknot/dname.h"
+#include "libknot/mm_ctx.h"
+#include "libknot/rrset.h"
+#include "libknot/rrtype/opt.h"
+#include "libknot/packet/wire.h"
+#include "libknot/packet/compr.h"
+#include "libknot/wire.h"
+
+/* Number of packet sections (ANSWER, AUTHORITY, ADDITIONAL). */
+#define KNOT_PKT_SECTIONS 3
+
+/*!
+ * \brief Packet flags.
+ */
+enum {
+	KNOT_PF_NULL      = 0 << 0, /*!< No flags. */
+	KNOT_PF_FREE      = 1 << 1, /*!< Free with packet. */
+	KNOT_PF_NOTRUNC   = 1 << 2, /*!< Don't truncate. */
+	KNOT_PF_CHECKDUP  = 1 << 3, /*!< Check for duplicates. */
+	KNOT_PF_KEEPWIRE  = 1 << 4, /*!< Keep wireformat untouched when parsing. */
+	KNOT_PF_NOCANON   = 1 << 5, /*!< Don't canonicalize rrsets during parsing. */
+	KNOT_PF_ORIGTTL   = 1 << 6, /*!< Write RRSIGs with their original TTL. */
+	KNOT_PF_SOAMINTTL = 1 << 7, /*!< Write SOA with its minimum-ttl as TTL. */
+};
+
+typedef struct knot_pkt knot_pkt_t;
+
+/*!
+ * \brief Packet section.
+ * Points to RRSet and RRSet info arrays in the packet.
+ * This structure is required for random access to packet sections.
+ */
+typedef struct {
+	knot_pkt_t *pkt; /*!< Owner. */
+	uint16_t pos;    /*!< Position in the rr/rrinfo fields in packet. */
+	uint16_t count;  /*!< Number of RRSets in this section. */
+} knot_pktsection_t;
+
+/*!
+ * \brief Structure representing a DNS packet.
+ */
+struct knot_pkt {
+	uint8_t *wire;         /*!< Wire format of the packet. */
+	size_t size;           /*!< Current wire size of the packet. */
+	size_t max_size;       /*!< Maximum allowed size of the packet. */
+	size_t parsed;         /*!< Parsed size. */
+	uint16_t reserved;     /*!< Reserved space. */
+	uint16_t qname_size;   /*!< QNAME size. */
+	uint16_t rrset_count;  /*!< Packet RRSet count. */
+	uint16_t flags;        /*!< Packet flags. */
+
+	knot_rrset_t *opt_rr;   /*!< OPT RR included in the packet. */
+	knot_rrset_t *tsig_rr;  /*!< TSIG RR stored in the packet. */
+
+	/*! EDNS option positions in the wire (if parsed from wire). */
+	knot_edns_options_t *edns_opts;
+
+	/*! TSIG RR position in the wire (if parsed from wire). */
+	struct {
+		uint8_t *pos;
+		size_t len;
+	} tsig_wire;
+
+	/* Packet sections. */
+	knot_section_t current;
+	knot_pktsection_t sections[KNOT_PKT_SECTIONS];
+
+	/* Packet RRSet (meta)data. */
+	size_t rrset_allocd;
+	knot_rrinfo_t *rr_info;
+	knot_rrset_t *rr;
+
+	knot_mm_t mm; /*!< Memory allocation context. */
+
+	knot_compr_t compr; /*!< Compression context. */
+
+	/*! Lowercased QNAME. MUST BE LAST ITEM! */
+	knot_dname_storage_t lower_qname;
+};
+
+/*!
+ * \brief Create new packet over existing memory, or allocate new from memory context.
+ *
+ * \note Packet is allocated from given memory context.
+ *
+ * \param wire If NULL, memory of 'len' size shall be allocated.
+ *        Otherwise pointer is used for the wire format of the packet.
+ * \param len Wire format length.
+ * \param mm Memory context (NULL for default).
+ * \return New packet or NULL.
+ */
+knot_pkt_t *knot_pkt_new(void *wire, uint16_t len, knot_mm_t *mm);
+
+/*!
+ * \brief Copy packet.
+ *
+ * \note Current implementation is not very efficient, as it re-parses the wire.
+ *
+ * \param dst Target packet.
+ * \param src Source packet.
+ *
+ * \return new packet or NULL
+ */
+int knot_pkt_copy(knot_pkt_t *dst, const knot_pkt_t *src);
+
+/*!
+ * \brief Initialized response from query packet.
+ *
+ * \note Question is not checked, it is expected to be checked already.
+ *
+ * \param pkt Given packet.
+ * \param query Query.
+ * \return KNOT_EOK, KNOT_EINVAL, KNOT_ESPACE
+ */
+int knot_pkt_init_response(knot_pkt_t *pkt, const knot_pkt_t *query);
+
+/*! \brief Reinitialize packet for another use. */
+void knot_pkt_clear(knot_pkt_t *pkt);
+
+/*! \brief Begone you foul creature of the underworld. */
+void knot_pkt_free(knot_pkt_t *pkt);
+
+/*!
+ * \brief Reserve an arbitrary amount of space in the packet.
+ *
+ * \return KNOT_EOK
+ * \return KNOT_ERANGE if size can't be reserved
+ */
+int knot_pkt_reserve(knot_pkt_t *pkt, uint16_t size);
+
+/*!
+ * \brief Reclaim reserved size.
+ *
+ * \return KNOT_EOK
+ * \return KNOT_ERANGE if size can't be reclaimed
+ */
+int knot_pkt_reclaim(knot_pkt_t *pkt, uint16_t size);
+
+/*
+ * Packet QUESTION accessors.
+ */
+static inline uint16_t knot_pkt_question_size(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL || pkt->qname_size == 0) {
+		return 0;
+	}
+
+	return pkt->qname_size + 2 * sizeof(uint16_t);
+}
+
+static inline const knot_dname_t *knot_pkt_qname(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL || pkt->qname_size == 0) {
+		return NULL;
+	}
+
+	return pkt->lower_qname;
+}
+
+static inline const knot_dname_t *knot_pkt_wire_qname(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL || pkt->qname_size == 0) {
+		return NULL;
+	}
+
+	return pkt->wire + KNOT_WIRE_HEADER_SIZE;
+}
+
+static inline uint16_t knot_pkt_qtype(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL || pkt->qname_size == 0) {
+		return 0;
+	}
+
+	unsigned off = KNOT_WIRE_HEADER_SIZE + pkt->qname_size;
+	return knot_wire_read_u16(pkt->wire + off);
+}
+
+static inline uint16_t knot_pkt_qclass(const knot_pkt_t *pkt)
+{
+	if (pkt == NULL || pkt->qname_size == 0) {
+		return 0;
+	}
+
+	unsigned off = KNOT_WIRE_HEADER_SIZE + pkt->qname_size + sizeof(uint16_t);
+	return knot_wire_read_u16(pkt->wire + off);
+}
+
+/*
+ * Packet writing API.
+ */
+
+/*!
+ * \brief Begin reading/writing packet section.
+ *
+ * \note You must proceed in the natural order (ANSWER, AUTHORITY, ADDITIONAL).
+ *
+ * \param pkt
+ * \param section_id
+ * \return KNOT_EOK or KNOT_EINVAL
+ */
+int knot_pkt_begin(knot_pkt_t *pkt, knot_section_t section_id);
+
+/*!
+ * \brief Put QUESTION in the packet.
+ *
+ * \note Since we support QD=1 only, QUESTION is a special type of packet section.
+ * \note Must not be used after putting RRsets into the packet.
+ *
+ * \param pkt
+ * \param qname
+ * \param qclass
+ * \param qtype
+ * \return KNOT_EOK or various errors
+ */
+int knot_pkt_put_question(knot_pkt_t *pkt, const knot_dname_t *qname,
+                          uint16_t qclass, uint16_t qtype);
+
+/*!
+ * \brief Put RRSet into packet.
+ *
+ * \note See compr.h for description on how compression hints work.
+ * \note Available flags: PF_FREE, KNOT_PF_CHECKDUP, KNOT_PF_NOTRUNC
+ *
+ * \param pkt
+ * \param compr_hint  Compression hint, see enum knot_compr_hint or absolute
+ *                    position.
+ * \param rr          Given RRSet.
+ * \param rotate      Rotate the RRSet order by this count.
+ * \param flags       RRSet flags (set PF_FREE if you want RRSet to be freed
+ *                    with the packet).
+ *
+ * \return KNOT_EOK, KNOT_ESPACE, various errors
+ */
+int knot_pkt_put_rotate(knot_pkt_t *pkt, uint16_t compr_hint, const knot_rrset_t *rr,
+                        uint16_t rotate, uint16_t flags);
+
+/*! \brief Same as knot_pkt_put_rotate but without rrset rotation. */
+static inline int knot_pkt_put(knot_pkt_t *pkt, uint16_t compr_hint,
+                               const knot_rrset_t *rr, uint16_t flags)
+{
+	return knot_pkt_put_rotate(pkt, compr_hint, rr, 0, flags);
+}
+
+/*! \brief Get description of the given packet section. */
+static inline const knot_pktsection_t *knot_pkt_section(const knot_pkt_t *pkt,
+                                                        knot_section_t section_id)
+{
+	assert(pkt);
+	return &pkt->sections[section_id];
+}
+
+/*! \brief Get RRSet from the packet section. */
+static inline const knot_rrset_t *knot_pkt_rr(const knot_pktsection_t *section,
+                                              uint16_t i)
+{
+	assert(section);
+	return section->pkt->rr + section->pos + i;
+}
+
+/*! \brief Get RRSet offset in the packet wire. */
+static inline uint16_t knot_pkt_rr_offset(const knot_pktsection_t *section,
+                                          uint16_t i)
+{
+	assert(section);
+	return section->pkt->rr_info[section->pos + i].pos;
+}
+
+/*
+ * Packet parsing API.
+ */
+
+/*!
+ * \brief Parse both packet question and payload.
+ *
+ * Parses both QUESTION and all packet sections,
+ * includes semantic checks over specific RRs (TSIG, OPT).
+ *
+ * \note If KNOT_PF_KEEPWIRE is set, TSIG RR is not stripped from the wire
+ *       and is processed as any other RR.
+ *
+ * \param  pkt Given packet.
+ * \param  flags Parsing flags (allowed KNOT_PF_KEEPWIRE)
+ *
+ * \retval KNOT_EOK if success.
+ * \retval KNOT_ETRAIL if success but with some trailing data.
+ * \retval KNOT_EMALF and other errors.
+ */
+int knot_pkt_parse(knot_pkt_t *pkt, unsigned flags);
+
+/*!
+ * \brief Parse packet header and a QUESTION section.
+ */
+int knot_pkt_parse_question(knot_pkt_t *pkt);
+
+/*!
+ * \brief Get packet extended RCODE.
+ *
+ * Extended RCODE is created by considering TSIG RCODE, EDNS RCODE and
+ * DNS Header RCODE. (See RFC 6895, Section 2.3).
+ *
+ * \param pkt Packet to get the response code from.
+ *
+ * \return Whole extended RCODE (0 if pkt == NULL).
+ */
+uint16_t knot_pkt_ext_rcode(const knot_pkt_t *pkt);
+
+/*!
+ * \brief Get packet extended RCODE name.
+ *
+ * The packet parameter is important as the name depends on TSIG.
+ *
+ * \param pkt Packet to get the response code from.
+ *
+ * \return RCODE name (or empty string if not known).
+ */
+const char *knot_pkt_ext_rcode_name(const knot_pkt_t *pkt);
+
+/*!
+ * \brief Checks if there is an OPT RR in the packet.
+ */
+static inline bool knot_pkt_has_edns(const knot_pkt_t *pkt)
+{
+	assert(pkt);
+	return pkt->opt_rr != NULL;
+}
+
+/*!
+ * \brief Checks if TSIG is present.
+ */
+static inline bool knot_pkt_has_tsig(const knot_pkt_t *pkt)
+{
+	assert(pkt);
+	return pkt->tsig_rr != NULL;
+}
+
+/*!
+ * \brief Checks if DO bit is set in the packet's OPT RR.
+ */
+static inline bool knot_pkt_has_dnssec(const knot_pkt_t *pkt)
+{
+	assert(pkt);
+	return knot_pkt_has_edns(pkt) && knot_edns_do(pkt->opt_rr);
+}
+
+/*!
+ * \brief Get specific EDNS option from a parsed packet.
+ */
+static inline uint8_t *knot_pkt_edns_option(const knot_pkt_t *pkt, uint16_t code)
+{
+	assert(pkt);
+	if (pkt->edns_opts != NULL && code <= KNOT_EDNS_MAX_OPTION_CODE) {
+		return pkt->edns_opts->ptr[code];
+	} else {
+		return NULL;
+	}
+}
+
+/*!
+ * \brief Computes a reasonable Padding data length for a given packet and opt RR.
+ *
+ * \param pkt     DNS Packet prepared and otherwise ready to go, no OPT yet added.
+ * \param opt_rr  OPT RR, not yet including padding.
+ *
+ * \return Required padding length or -1 if padding not required.
+ */
+static inline int knot_pkt_default_padding_size(const knot_pkt_t *pkt,
+                                                const knot_rrset_t *opt_rr)
+{
+	if (knot_wire_get_qr(pkt->wire)) {
+		return knot_edns_alignment_size(pkt->size, knot_rrset_size(opt_rr),
+		                                KNOT_EDNS_ALIGNMENT_RESPONSE_DEFAULT);
+	} else {
+		return knot_edns_alignment_size(pkt->size, knot_rrset_size(opt_rr),
+		                                KNOT_EDNS_ALIGNMENT_QUERY_DEFAULT);
+	}
+}
+
+static inline size_t knot_pkt_size(const knot_pkt_t *pkt)
+{
+	assert(pkt);
+	return pkt->size + (knot_pkt_has_tsig(pkt) ? pkt->tsig_wire.len : 0);
+}
+
+/*! @} */
diff --git a/src/libknot/packet/rrset-wire.c b/src/libknot/packet/rrset-wire.c
new file mode 100644
index 0000000..2b02969
--- /dev/null
+++ b/src/libknot/packet/rrset-wire.c
@@ -0,0 +1,727 @@
+/*  Copyright (C) 2021 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 "libknot/attribute.h"
+#include "libknot/consts.h"
+#include "libknot/descriptor.h"
+#include "libknot/packet/pkt.h"
+#include "libknot/packet/rrset-wire.h"
+#include "libknot/rrtype/naptr.h"
+#include "libknot/rrtype/rrsig.h"
+#include "libknot/rrtype/soa.h"
+#include "contrib/macros.h"
+#include "contrib/mempattern.h"
+#include "contrib/tolower.h"
+#include "contrib/wire_ctx.h"
+
+/*!
+ * \brief Get maximal size of a domain name in a wire with given capacity.
+ */
+static uint16_t dname_max(size_t wire_avail)
+{
+	return MIN(wire_avail, KNOT_DNAME_MAXLEN);
+}
+
+/*!
+ * \brief Compares two domain name labels.
+ *
+ * \param label1  First label.
+ * \param label2  Second label (may be in upper-case).
+ *
+ * \retval true if the labels are identical
+ * \retval false if the labels are NOT identical
+ */
+static bool label_is_equal(const uint8_t *label1, const uint8_t *label2)
+{
+	assert(label1 && label2);
+
+	if (*label1 != *label2) {
+		return false;
+	}
+
+	uint8_t len = *label1;
+	for (uint8_t i = 1; i <= len; i++) {
+		if (label1[i] != knot_tolower(label2[i])) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+/*!
+ * Case insensitive comparison of two dnames in wire format.
+ * The second name may be compressed in a supplied wire.
+ */
+static bool dname_equal_wire(const knot_dname_t *d1, const knot_dname_t *d2,
+                             const uint8_t *wire)
+{
+	assert(d1);
+	assert(d2);
+
+	d2 = knot_wire_seek_label(d2, wire);
+
+	while (*d1 != '\0' || *d2 != '\0') {
+		if (!label_is_equal(d1, d2)) {
+			return false;
+		}
+		d1 = knot_wire_next_label(d1, NULL);
+		d2 = knot_wire_next_label(d2, wire);
+	}
+
+	return true;
+}
+
+static uint16_t compr_get_ptr(knot_compr_t *compr, uint16_t hint)
+{
+	if (compr == NULL) {
+		return 0;
+	}
+
+	return knot_compr_hint(compr->rrinfo, hint);
+}
+
+static void compr_set_ptr(knot_compr_t *compr, uint16_t hint,
+                          const uint8_t *written_at, uint16_t written_size)
+{
+	if (compr == NULL) {
+		return;
+	}
+
+	assert(written_at >= compr->wire);
+
+	uint16_t offset = written_at - compr->wire;
+
+	if (knot_wire_is_pointer(written_at)) {
+		offset = knot_wire_get_pointer(written_at);
+	}
+
+	knot_compr_hint_set(compr->rrinfo, hint, offset, written_size);
+}
+
+static int write_rdata_fixed(const uint8_t **src, size_t *src_avail,
+                             uint8_t **dst, size_t *dst_avail, size_t size)
+{
+	assert(src && *src);
+	assert(src_avail);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	// Check input/output buffer boundaries.
+	if (size > *src_avail) {
+		return KNOT_EMALF;
+	}
+
+	if (size > *dst_avail) {
+		return KNOT_ESPACE;
+	}
+
+	// Data binary copy.
+	memcpy(*dst, *src, size);
+
+	// Update buffers.
+	*src += size;
+	*src_avail -= size;
+
+	*dst += size;
+	*dst_avail -= size;
+
+	return KNOT_EOK;
+}
+
+static int write_rdata_naptr_header(const uint8_t **src, size_t *src_avail,
+                                    uint8_t **dst, size_t *dst_avail)
+{
+	assert(src && *src);
+	assert(src_avail);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	int ret = knot_naptr_header_size(*src, *src + *src_avail);
+	if (ret < 0) {
+		return ret;
+	}
+
+	// Copy the data.
+	return write_rdata_fixed(src, src_avail, dst, dst_avail, ret);
+}
+
+/*! \brief Helper for \ref compr_put_dname, writes label(s) with size checks. */
+#define WRITE_LABEL(dst, written, label, max, len) \
+	if ((written) + (len) > (max)) { \
+		return KNOT_ESPACE; \
+	} else { \
+		memcpy((dst) + (written), (label), (len)); \
+		written += (len); \
+	}
+
+/*!
+ * \brief Write compressed domain name to the destination wire.
+ *
+ * \param dname  Name to be written.
+ * \param dst    Destination wire.
+ * \param max    Maximum number of bytes available.
+ * \param compr  Compression context (NULL for no compression)
+ * \return Number of written bytes or an error.
+ */
+static int compr_put_dname(const knot_dname_t *dname, uint8_t *dst, uint16_t max,
+                           knot_compr_t *compr)
+{
+	assert(dname && dst);
+
+	// Write uncompressible names directly (zero label dname).
+	if (compr == NULL || *dname == '\0') {
+		return knot_dname_to_wire(dst, dname, max);
+	}
+
+	// Get number of labels (should not be a zero label dname).
+	size_t name_labels = knot_dname_labels(dname, NULL);
+	assert(name_labels > 0);
+
+	// Suffix must not be longer than whole name.
+	const knot_dname_t *suffix = compr->wire + compr->suffix.pos;
+	int suffix_labels = compr->suffix.labels;
+	while (suffix_labels > name_labels) {
+		suffix = knot_wire_next_label(suffix, compr->wire);
+		--suffix_labels;
+	}
+
+	// Suffix is shorter than name, write labels until aligned.
+	uint8_t orig_labels = name_labels;
+	uint16_t written = 0;
+	while (name_labels > suffix_labels) {
+		WRITE_LABEL(dst, written, dname, max, (*dname + 1));
+		dname = knot_wire_next_label(dname, NULL);
+		--name_labels;
+	}
+
+	// Label count is now equal.
+	assert(name_labels == suffix_labels);
+	const knot_dname_t *match_begin = dname;
+	const knot_dname_t *compr_ptr = suffix;
+	while (dname[0] != '\0') {
+		// Next labels.
+		const knot_dname_t *next_dname = knot_wire_next_label(dname, NULL);
+		const knot_dname_t *next_suffix = knot_wire_next_label(suffix, compr->wire);
+
+		// Two labels match, extend suffix length.
+		if (!label_is_equal(dname, suffix)) {
+			// If they don't match, write unmatched labels.
+			uint16_t mismatch_len = (dname - match_begin) + (*dname + 1);
+			WRITE_LABEL(dst, written, match_begin, max, mismatch_len);
+			// Start new potential match.
+			match_begin = next_dname;
+			compr_ptr = next_suffix;
+		}
+
+		// Jump to next labels.
+		dname = next_dname;
+		suffix = next_suffix;
+	}
+
+	// If match begins at the end of the name, write '\0' label.
+	if (match_begin == dname) {
+		WRITE_LABEL(dst, written, dname, max, 1);
+	} else {
+		// Match covers >0 labels, write out compression pointer.
+		if (written + sizeof(uint16_t) > max) {
+			return KNOT_ESPACE;
+		}
+		knot_wire_put_pointer(dst + written, compr_ptr - compr->wire);
+		written += sizeof(uint16_t);
+	}
+
+	assert(dst >= compr->wire);
+	size_t wire_pos = dst - compr->wire;
+	assert(wire_pos < KNOT_WIRE_MAX_PKTSIZE);
+
+	// Heuristics - expect similar names are grouped together.
+	if (written > sizeof(uint16_t) && wire_pos + written < KNOT_WIRE_PTR_MAX) {
+		compr->suffix.pos = wire_pos;
+		compr->suffix.labels = orig_labels;
+	}
+
+	return written;
+}
+
+#define WRITE_OWNER_CHECK(size, dst_avail) \
+	if ((size) > *(dst_avail)) { \
+		return KNOT_ESPACE; \
+	}
+
+#define WRITE_OWNER_INCR(dst, dst_avail, size) \
+	*(dst) += (size); \
+	*(dst_avail) -= (size);
+
+static int write_owner(const knot_rrset_t *rrset, uint8_t **dst, size_t *dst_avail,
+                       knot_compr_t *compr)
+{
+	assert(rrset);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	// Check for zero label owner (don't compress).
+	uint16_t owner_pointer = 0;
+	if (*rrset->owner != '\0') {
+		owner_pointer = compr_get_ptr(compr, KNOT_COMPR_HINT_OWNER);
+	}
+
+	// Write result.
+	if (owner_pointer > 0) {
+		WRITE_OWNER_CHECK(sizeof(uint16_t), dst_avail);
+		knot_wire_put_pointer(*dst, owner_pointer);
+		WRITE_OWNER_INCR(dst, dst_avail, sizeof(uint16_t));
+	// Check for coincidence with previous RR set.
+	} else if (compr != NULL && compr->suffix.pos != 0 && *rrset->owner != '\0' &&
+	           dname_equal_wire(rrset->owner, compr->wire + compr->suffix.pos,
+	                            compr->wire)) {
+		WRITE_OWNER_CHECK(sizeof(uint16_t), dst_avail);
+		knot_wire_put_pointer(*dst, compr->suffix.pos);
+		compr_set_ptr(compr, KNOT_COMPR_HINT_OWNER,
+		              compr->wire + compr->suffix.pos,
+		              knot_dname_size(rrset->owner));
+		WRITE_OWNER_INCR(dst, dst_avail, sizeof(uint16_t));
+	} else {
+		if (compr != NULL) {
+			compr->suffix.pos = KNOT_WIRE_HEADER_SIZE;
+			compr->suffix.labels =
+				knot_dname_labels(compr->wire + compr->suffix.pos,
+				                  compr->wire);
+		}
+		// WRITE_OWNER_CHECK not needed, compr_put_dname has a check.
+		int written = compr_put_dname(rrset->owner, *dst,
+		                              dname_max(*dst_avail), compr);
+		if (written < 0) {
+			return written;
+		}
+
+		compr_set_ptr(compr, KNOT_COMPR_HINT_OWNER, *dst, written);
+		WRITE_OWNER_INCR(dst, dst_avail, written);
+	}
+
+	return KNOT_EOK;
+}
+
+static int write_fixed_header(const knot_rrset_t *rrset, uint16_t rrset_index,
+                              uint8_t **dst, size_t *dst_avail, uint16_t flags)
+{
+	assert(rrset);
+	assert(rrset_index < rrset->rrs.count);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	// Write header.
+	wire_ctx_t write = wire_ctx_init(*dst, *dst_avail);
+
+	wire_ctx_write_u16(&write, rrset->type);
+	wire_ctx_write_u16(&write, rrset->rclass);
+
+	if ((flags & KNOT_PF_ORIGTTL) && rrset->type == KNOT_RRTYPE_RRSIG) {
+		const knot_rdata_t *rdata = knot_rdataset_at(&rrset->rrs, rrset_index);
+		wire_ctx_write_u32(&write, knot_rrsig_original_ttl(rdata));
+	} else if ((flags & KNOT_PF_SOAMINTTL) && rrset->type == KNOT_RRTYPE_SOA) {
+		const knot_rdata_t *rdata = knot_rdataset_at(&rrset->rrs, rrset_index);
+		wire_ctx_write_u32(&write, MIN(knot_soa_minimum(rdata), rrset->ttl));
+	} else {
+		wire_ctx_write_u32(&write, rrset->ttl);
+	}
+
+	// Check write.
+	if (write.error != KNOT_EOK) {
+		return write.error;
+	}
+
+	// Update buffer.
+	*dst = write.position;
+	*dst_avail = wire_ctx_available(&write);
+
+	return KNOT_EOK;
+}
+
+static int compress_rdata_dname(const uint8_t **src, size_t *src_avail,
+                                uint8_t **dst, size_t *dst_avail,
+                                knot_compr_t *put_compr, knot_compr_t *compr,
+                                uint16_t hint)
+{
+	assert(src && *src);
+	assert(src_avail);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	// Source domain name.
+	const knot_dname_t *dname = *src;
+	size_t dname_size = knot_dname_size(dname);
+
+	// Output domain name.
+	int written = compr_put_dname(dname, *dst, dname_max(*dst_avail), put_compr);
+	if (written < 0) {
+		return written;
+	}
+
+	// Update compression hints.
+	if (compr_get_ptr(compr, hint) == 0) {
+		compr_set_ptr(compr, hint, *dst, written);
+	}
+
+	// Update buffers.
+	*dst += written;
+	*dst_avail -= written;
+
+	*src += dname_size;
+	*src_avail -= dname_size;
+
+	return KNOT_EOK;
+}
+
+static int rdata_traverse_write(const uint8_t **src, size_t *src_avail,
+                                uint8_t **dst, size_t *dst_avail,
+                                const knot_rdata_descriptor_t *desc,
+                                knot_compr_t *compr, uint16_t hint)
+{
+	for (const int *type = desc->block_types; *type != KNOT_RDATA_WF_END; type++) {
+		int ret;
+		knot_compr_t *put_compr = NULL;
+		switch (*type) {
+		case KNOT_RDATA_WF_COMPRESSIBLE_DNAME:
+			put_compr = compr;
+			// FALLTHROUGH
+		case KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME:
+		case KNOT_RDATA_WF_FIXED_DNAME:
+			ret = compress_rdata_dname(src, src_avail, dst, dst_avail,
+			                           put_compr, compr, hint);
+			break;
+		case KNOT_RDATA_WF_NAPTR_HEADER:
+			ret = write_rdata_naptr_header(src, src_avail, dst, dst_avail);
+			break;
+		case KNOT_RDATA_WF_REMAINDER:
+			ret = write_rdata_fixed(src, src_avail, dst, dst_avail, *src_avail);
+			break;
+		default:
+			// Fixed size block.
+			assert(*type > 0);
+			ret = write_rdata_fixed(src, src_avail, dst, dst_avail, *type);
+			break;
+		}
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+static int write_rdata(const knot_rrset_t *rrset, uint16_t rrset_index,
+                       uint8_t **dst, size_t *dst_avail, knot_compr_t *compr)
+{
+	assert(rrset);
+	assert(rrset_index < rrset->rrs.count);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	const knot_rdata_t *rdata = knot_rdataset_at(&rrset->rrs, rrset_index);
+
+	// Reserve space for RDLENGTH.
+	if (sizeof(uint16_t) > *dst_avail) {
+		return KNOT_ESPACE;
+	}
+
+	uint8_t *wire_rdlength = *dst;
+	*dst += sizeof(uint16_t);
+	*dst_avail -= sizeof(uint16_t);
+	uint8_t *wire_rdata_begin = *dst;
+
+	// Write RDATA.
+	const uint8_t *src = rdata->data;
+	size_t src_avail = rdata->len;
+	if (src_avail > 0) {
+		// Only write non-empty data.
+		const knot_rdata_descriptor_t *desc =
+			knot_get_rdata_descriptor(rrset->type);
+		int ret = rdata_traverse_write(&src, &src_avail, dst, dst_avail,
+		                         desc, compr, KNOT_COMPR_HINT_RDATA + rrset_index);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	// Check for trailing data in the message.
+	if (src_avail > 0) {
+		return KNOT_EMALF;
+	}
+
+	// Write final RDLENGTH.
+	size_t rdlength = *dst - wire_rdata_begin;
+	knot_wire_write_u16(wire_rdlength, rdlength);
+
+	return KNOT_EOK;
+}
+
+static int write_rr(const knot_rrset_t *rrset, uint16_t rrset_index, uint8_t **dst,
+                    size_t *dst_avail, knot_compr_t *compr, uint16_t flags)
+{
+	int ret = write_owner(rrset, dst, dst_avail, compr);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	ret = write_fixed_header(rrset, rrset_index, dst, dst_avail, flags);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	return write_rdata(rrset, rrset_index, dst, dst_avail, compr);
+}
+
+_public_
+int knot_rrset_to_wire_extra(const knot_rrset_t *rrset, uint8_t *wire,
+                             uint16_t max_size, uint16_t rotate,
+                             knot_compr_t *compr, uint16_t flags)
+{
+	if (rrset == NULL || wire == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (rrset->rrs.count == 0) {
+		return 0;
+	}
+	if (rotate != 0) {
+		rotate %= rrset->rrs.count;
+	}
+
+	uint8_t *write = wire;
+	size_t capacity = max_size;
+
+	uint16_t count = rrset->rrs.count;
+	for (int i = rotate; i < count + rotate; i++) {
+		uint16_t pos = (i < count) ? i : (i - count);
+		int ret = write_rr(rrset, pos, &write, &capacity, compr, flags);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return write - wire;
+}
+
+static int parse_header(const uint8_t *wire, size_t *pos, size_t pkt_size,
+                        knot_mm_t *mm, knot_rrset_t *rrset, uint16_t *rdlen)
+{
+	assert(wire);
+	assert(pos);
+	assert(rrset);
+	assert(rdlen);
+
+	wire_ctx_t src = wire_ctx_init_const(wire, pkt_size);
+	wire_ctx_set_offset(&src, *pos);
+
+	int compr_size = knot_dname_wire_check(src.position, wire + pkt_size, wire);
+	if (compr_size <= 0) {
+		return KNOT_EMALF;
+	}
+
+	knot_dname_storage_t buff;
+	int decompr_size = knot_dname_unpack(buff, src.position, sizeof(buff), wire);
+	if (decompr_size <= 0) {
+		return KNOT_EMALF;
+	}
+
+	knot_dname_t *owner = mm_alloc(mm, decompr_size);
+	if (owner == NULL) {
+		return KNOT_ENOMEM;
+	}
+	memcpy(owner, buff, decompr_size);
+	wire_ctx_skip(&src, compr_size);
+
+	uint16_t type = wire_ctx_read_u16(&src);
+	uint16_t rclass = wire_ctx_read_u16(&src);
+	uint32_t ttl = wire_ctx_read_u32(&src);
+	*rdlen = wire_ctx_read_u16(&src);
+
+	if (src.error != KNOT_EOK) {
+		knot_dname_free(owner, mm);
+		return KNOT_EMALF;
+	}
+
+	if (wire_ctx_available(&src) < *rdlen) {
+		knot_dname_free(owner, mm);
+		return KNOT_EMALF;
+	}
+
+	*pos = wire_ctx_offset(&src);
+
+	knot_rrset_init(rrset, owner, type, rclass, ttl);
+
+	return KNOT_EOK;
+}
+
+static int decompress_rdata_dname(const uint8_t **src, size_t *src_avail,
+                                  uint8_t **dst, size_t *dst_avail,
+                                  const uint8_t *pkt_wire)
+{
+	assert(src && *src);
+	assert(src_avail);
+	assert(dst && *dst);
+	assert(dst_avail);
+
+	int compr_size = knot_dname_wire_check(*src, *src + *src_avail, pkt_wire);
+	if (compr_size <= 0) {
+		return compr_size;
+	}
+
+	int decompr_size = knot_dname_unpack(*dst, *src, *dst_avail, pkt_wire);
+	if (decompr_size <= 0) {
+		return decompr_size;
+	}
+
+	// Update buffers.
+	*dst += decompr_size;
+	*dst_avail -= decompr_size;
+
+	*src += compr_size;
+	*src_avail -= compr_size;
+
+	return KNOT_EOK;
+}
+
+static int rdata_traverse_parse(const uint8_t **src, size_t *src_avail,
+                                uint8_t **dst, size_t *dst_avail,
+                                const knot_rdata_descriptor_t *desc,
+                                const uint8_t *pkt_wire)
+{
+	for (const int *type = desc->block_types; *type != KNOT_RDATA_WF_END; type++) {
+		int ret;
+		switch (*type) {
+		case KNOT_RDATA_WF_COMPRESSIBLE_DNAME:
+		case KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME:
+		case KNOT_RDATA_WF_FIXED_DNAME:
+			ret = decompress_rdata_dname(src, src_avail, dst, dst_avail,
+			                             pkt_wire);
+			break;
+		case KNOT_RDATA_WF_NAPTR_HEADER:
+			ret = write_rdata_naptr_header(src, src_avail, dst, dst_avail);
+			break;
+		case KNOT_RDATA_WF_REMAINDER:
+			ret = write_rdata_fixed(src, src_avail, dst, dst_avail, *src_avail);
+			break;
+		default:
+			/* Fixed size block */
+			assert(*type > 0);
+			ret = write_rdata_fixed(src, src_avail, dst, dst_avail, *type);
+			break;
+		}
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+static bool allow_zero_rdata(const knot_rrset_t *rr,
+                             const knot_rdata_descriptor_t *desc)
+{
+	return rr->rclass != KNOT_CLASS_IN ||  // NONE and ANY for DDNS
+	       rr->type == KNOT_RRTYPE_APL ||  // APL RR type
+	       desc->type_name == NULL;        // Unknown RR type
+}
+
+static int parse_rdata(const uint8_t *pkt_wire, size_t *pos, size_t pkt_size,
+                       knot_mm_t *mm, uint16_t rdlength, knot_rrset_t *rrset)
+{
+	assert(pkt_wire);
+	assert(pos);
+	assert(rrset);
+
+	const knot_rdata_descriptor_t *desc = knot_get_rdata_descriptor(rrset->type);
+	if (desc->type_name == NULL) {
+		desc = knot_get_obsolete_rdata_descriptor(rrset->type);
+	}
+
+	if (rdlength == 0) {
+		if (allow_zero_rdata(rrset, desc)) {
+			return knot_rrset_add_rdata(rrset, NULL, 0, mm);
+		} else {
+			return KNOT_EMALF;
+		}
+	} else if (pkt_size - *pos < rdlength) {
+		return KNOT_EMALF;
+	}
+
+	// Buffer for parsed rdata (decompression extends rdata length).
+	const size_t max_rdata_len = UINT16_MAX;
+	uint8_t buf[knot_rdata_size(max_rdata_len)];
+	knot_rdata_t *rdata = (knot_rdata_t *)buf;
+
+	const uint8_t *src = pkt_wire + *pos;
+	size_t src_avail = rdlength;
+	uint8_t *dst = rdata->data;
+	size_t dst_avail = max_rdata_len;
+
+	// Parse RDATA.
+	int ret = rdata_traverse_parse(&src, &src_avail, &dst, &dst_avail, desc, pkt_wire);
+	if (ret != KNOT_EOK) {
+		return KNOT_EMALF;
+	}
+
+	// Check for trailing data.
+	size_t real_len = max_rdata_len - dst_avail;
+	if (real_len < rdlength) {
+		return KNOT_EMALF;
+	}
+	rdata->len = real_len;
+
+	ret = knot_rdataset_add(&rrset->rrs, rdata, mm);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Update position pointer.
+	*pos += rdlength;
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_rrset_rr_from_wire(const uint8_t *wire, size_t *pos, size_t max_size,
+                            knot_rrset_t *rrset, knot_mm_t *mm, bool canonical)
+{
+	if (wire == NULL || pos == NULL || *pos > max_size || rrset == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	uint16_t rdlen = 0;
+	int ret = parse_header(wire, pos, max_size, mm, rrset, &rdlen);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	ret = parse_rdata(wire, pos, max_size, mm, rdlen, rrset);
+	if (ret != KNOT_EOK) {
+		knot_rrset_clear(rrset, mm);
+		return ret;
+	}
+
+	// Convert RR to the canonical format.
+	if (canonical) {
+		ret = knot_rrset_rr_to_canonical(rrset);
+		if (ret != KNOT_EOK) {
+			knot_rrset_clear(rrset, mm);
+		}
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/packet/rrset-wire.h b/src/libknot/packet/rrset-wire.h
new file mode 100644
index 0000000..3be0cba
--- /dev/null
+++ b/src/libknot/packet/rrset-wire.h
@@ -0,0 +1,69 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief RRSet from/to wire conversion functions.
+ *
+ * \addtogroup wire
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rrset.h"
+#include "libknot/packet/compr.h"
+
+/*!
+ * \brief Write RR Set content to a wire.
+ *
+ * \param rrset     RRSet to be converted.
+ * \param wire      Output wire buffer.
+ * \param max_size  Capacity of wire buffer.
+ * \param rotate    Rotate the RR order by this count.
+ * \param compr     Compression context.
+ * \param flags     Flags; currently only KNOT_PF_TTL_ORIG is accepted.
+ *
+ * \return Output size, negative number on error (KNOT_E*).
+ */
+int knot_rrset_to_wire_extra(const knot_rrset_t *rrset, uint8_t *wire,
+                             uint16_t max_size, uint16_t rotate,
+                             knot_compr_t *compr, uint16_t flags);
+
+/*! \brief Same as knot_rrset_to_wire_extra but without rrset rotation and flags. */
+static inline int knot_rrset_to_wire(const knot_rrset_t *rrset, uint8_t *wire,
+                                     uint16_t max_size, knot_compr_t *compr)
+{
+	return knot_rrset_to_wire_extra(rrset, wire, max_size, 0, compr, 0);
+}
+
+/*!
+* \brief Creates one RR from wire, stores it into \a rrset.
+*
+* \param wire       Source wire (the whole packet).
+* \param pos        Position in \a wire where to start parsing.
+* \param max_size   Total size of data in \a wire (size of the packet).
+* \param rrset      Destination RRSet.
+* \param mm         Memory context.
+* \param canonical  Convert rrset to canonical format indication.
+*
+* \return KNOT_E*
+*/
+int knot_rrset_rr_from_wire(const uint8_t *wire, size_t *pos, size_t max_size,
+                            knot_rrset_t *rrset, knot_mm_t *mm, bool canonical);
+
+/*! @} */
diff --git a/src/libknot/packet/wire.h b/src/libknot/packet/wire.h
new file mode 100644
index 0000000..698ac3d
--- /dev/null
+++ b/src/libknot/packet/wire.h
@@ -0,0 +1,1045 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Functions for manipulating and parsing raw data in DNS packets.
+ *
+ * \addtogroup wire
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stdint.h>
+
+#include "libknot/attribute.h"
+#include "libknot/wire.h"
+
+/*! \brief Offset of DNS header fields in wireformat. */
+enum knot_wire_offsets {
+	KNOT_WIRE_OFFSET_ID = 0,
+	KNOT_WIRE_OFFSET_FLAGS1 = 2,
+	KNOT_WIRE_OFFSET_FLAGS2 = 3,
+	KNOT_WIRE_OFFSET_QDCOUNT = 4,
+	KNOT_WIRE_OFFSET_ANCOUNT = 6,
+	KNOT_WIRE_OFFSET_NSCOUNT = 8,
+	KNOT_WIRE_OFFSET_ARCOUNT = 10
+};
+
+/*! \brief Minimum size for some parts of the DNS packet. */
+enum knot_wire_sizes {
+	KNOT_WIRE_HEADER_SIZE = 12,
+	KNOT_WIRE_QUESTION_MIN_SIZE = 5,
+	KNOT_WIRE_RR_MIN_SIZE = 11,
+	KNOT_WIRE_MIN_PKTSIZE = 512,
+	KNOT_WIRE_MAX_PKTSIZE = 65535,
+	KNOT_WIRE_MAX_PAYLOAD = KNOT_WIRE_MAX_PKTSIZE
+	                        - KNOT_WIRE_HEADER_SIZE
+	                        - KNOT_WIRE_QUESTION_MIN_SIZE
+};
+
+/*
+ * Packet header manipulation functions.
+ */
+
+/*!
+ * \brief Returns the ID from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return DNS packet ID.
+ */
+static inline uint16_t knot_wire_get_id(const uint8_t *packet)
+{
+	assert(packet);
+	return knot_wire_read_u16(packet + KNOT_WIRE_OFFSET_ID);
+}
+
+/*!
+ * \brief Sets the ID to the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param id DNS packet ID.
+ */
+static inline void knot_wire_set_id(uint8_t *packet, uint16_t id)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_ID, id);
+}
+
+/*!
+ * \brief Returns the first byte of flags from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return First byte of DNS flags.
+ */
+static inline uint8_t knot_wire_get_flags1(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1);
+}
+
+/*!
+ * \brief Sets the first byte of flags to the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param flags1 First byte of the DNS flags.
+ */
+static inline uint8_t knot_wire_set_flags1(uint8_t *packet, uint8_t flags1)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1) = flags1;
+}
+
+/*!
+ * \brief Returns the second byte of flags from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Second byte of DNS flags.
+ */
+static inline uint8_t knot_wire_get_flags2(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2);
+}
+
+/*!
+ * \brief Sets the second byte of flags to the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param flags2 Second byte of the DNS flags.
+ */
+static inline uint8_t knot_wire_set_flags2(uint8_t *packet, uint8_t flags2)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2) = flags2;
+}
+
+/*!
+ * \brief Returns the QDCOUNT (count of Question entries) from wire format of
+ *        the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return QDCOUNT (count of Question entries in the packet).
+ */
+static inline uint16_t knot_wire_get_qdcount(const uint8_t *packet)
+{
+	assert(packet);
+	return knot_wire_read_u16(packet + KNOT_WIRE_OFFSET_QDCOUNT);
+}
+
+/*!
+ * \brief Sets the QDCOUNT (count of Question entries) to wire format of the
+ *        packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param qdcount QDCOUNT (count of Question entries in the packet).
+ */
+static inline void knot_wire_set_qdcount(uint8_t *packet, uint16_t qdcount)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_QDCOUNT, qdcount);
+}
+
+/*!
+ * \brief Adds to QDCOUNT.
+ */
+static inline void knot_wire_add_qdcount(uint8_t *packet, int16_t n)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_QDCOUNT,
+	                    knot_wire_get_qdcount(packet) + n);
+}
+
+/*!
+ * \brief Returns the ANCOUNT (count of Answer entries) from wire format of
+ *        the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return ANCOUNT (count of Answer entries in the packet).
+ */
+static inline uint16_t knot_wire_get_ancount(const uint8_t *packet)
+{
+	assert(packet);
+	return knot_wire_read_u16(packet + KNOT_WIRE_OFFSET_ANCOUNT);
+}
+
+/*!
+ * \brief Sets the ANCOUNT (count of Answer entries) to wire format of the
+ *        packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param ancount ANCOUNT (count of Answer entries in the packet).
+ */
+static inline void knot_wire_set_ancount(uint8_t *packet, uint16_t ancount)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_ANCOUNT, ancount);
+}
+
+/*!
+ * \brief Adds to ANCOUNT.
+ */
+static inline void knot_wire_add_ancount(uint8_t *packet, int16_t n)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_ANCOUNT,
+	                    knot_wire_get_ancount(packet) + n);
+}
+
+/*!
+ * \brief Returns the NSCOUNT (count of Authority entries) from wire format of
+ *        the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return NSCOUNT (count of Authority entries in the packet).
+ */
+static inline uint16_t knot_wire_get_nscount(const uint8_t *packet)
+{
+	assert(packet);
+	return knot_wire_read_u16(packet + KNOT_WIRE_OFFSET_NSCOUNT);
+}
+
+/*!
+ * \brief Sets the NSCOUNT (count of Authority entries) to wire format of the
+ *        packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param nscount NSCOUNT (count of Authority entries in the packet).
+ */
+static inline void knot_wire_set_nscount(uint8_t *packet, uint16_t nscount)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_NSCOUNT, nscount);
+}
+
+/*!
+ * \brief Adds to NSCOUNT.
+ */
+static inline void knot_wire_add_nscount(uint8_t *packet, int16_t n)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_NSCOUNT,
+	                    knot_wire_get_nscount(packet) + n);
+}
+
+/*!
+ * \brief Returns the ARCOUNT (count of Additional entries) from wire format of
+ *        the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return ARCOUNT (count of Additional entries in the packet).
+ */
+static inline uint16_t knot_wire_get_arcount(const uint8_t *packet)
+{
+	assert(packet);
+	return knot_wire_read_u16(packet + KNOT_WIRE_OFFSET_ARCOUNT);
+}
+
+/*!
+ * \brief Sets the ARCOUNT (count of Additional entries) to wire format of the
+ *        packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param arcount ARCOUNT (count of Additional entries in the packet).
+ */
+static inline void knot_wire_set_arcount(uint8_t *packet, uint16_t arcount)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_ARCOUNT, arcount);
+}
+
+/*!
+ * \brief Adds to ARCOUNT.
+ */
+static inline void knot_wire_add_arcount(uint8_t *packet, int16_t n)
+{
+	assert(packet);
+	knot_wire_write_u16(packet + KNOT_WIRE_OFFSET_ARCOUNT,
+	                    knot_wire_get_arcount(packet) + n);
+}
+
+/*
+ * Packet header flags manipulation functions.
+ */
+/*! \brief Constants for DNS header flags in the first flags byte. */
+enum knot_wire_flags1_consts {
+	KNOT_WIRE_RD_MASK = (uint8_t)0x01U,      /*!< RD bit mask. */
+	KNOT_WIRE_RD_SHIFT = 0,                  /*!< RD bit shift. */
+	KNOT_WIRE_TC_MASK = (uint8_t)0x02U,      /*!< TC bit mask. */
+	KNOT_WIRE_TC_SHIFT = 1,                  /*!< TC bit shift. */
+	KNOT_WIRE_AA_MASK = (uint8_t)0x04U,      /*!< AA bit mask. */
+	KNOT_WIRE_AA_SHIFT = 2,                  /*!< AA bit shift. */
+	KNOT_WIRE_OPCODE_MASK = (uint8_t)0x78U,  /*!< OPCODE mask. */
+	KNOT_WIRE_OPCODE_SHIFT = 3,              /*!< OPCODE shift. */
+	KNOT_WIRE_QR_MASK = (uint8_t)0x80U,      /*!< QR bit mask. */
+	KNOT_WIRE_QR_SHIFT = 7                   /*!< QR bit shift. */
+};
+
+/*! \brief Constants for DNS header flags in the second flags byte. */
+enum knot_wire_flags2_consts {
+	KNOT_WIRE_RCODE_MASK = (uint8_t)0x0fU,  /*!< RCODE mask. */
+	KNOT_WIRE_RCODE_SHIFT = 0,              /*!< RCODE shift. */
+	KNOT_WIRE_CD_MASK = (uint8_t)0x10U,     /*!< CD bit mask. */
+	KNOT_WIRE_CD_SHIFT = 4,                 /*!< CD bit shift. */
+	KNOT_WIRE_AD_MASK = (uint8_t)0x20U,     /*!< AD bit mask. */
+	KNOT_WIRE_AD_SHIFT = 5,                 /*!< AD bit shift. */
+	KNOT_WIRE_Z_MASK = (uint8_t)0x40U,      /*!< Zero bit mask. */
+	KNOT_WIRE_Z_SHIFT = 6,                  /*!< Zero bit shift. */
+	KNOT_WIRE_RA_MASK = (uint8_t)0x80U,     /*!< RA bit mask. */
+	KNOT_WIRE_RA_SHIFT = 7                  /*!< RA bit shift. */
+};
+
+/*
+ * Functions for getting / setting / clearing flags and codes directly in packet
+ */
+
+/*!
+ * \brief Returns the RD bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the RD bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_rd(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1) & KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Sets the RD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_rd(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) |= KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Clears the RD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_rd(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) &= ~KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Returns the TC bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the TC bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_tc(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1) & KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Sets the TC bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_tc(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) |= KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Clears the TC bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_tc(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) &= ~KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Returns the AA bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the AA bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_aa(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1) & KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Sets the AA bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_aa(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) |= KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Clears the AA bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_aa(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) &= ~KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Returns the OPCODE from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return OPCODE of the packet.
+ */
+static inline uint8_t knot_wire_get_opcode(const uint8_t *packet)
+{
+	assert(packet);
+	return (*(packet + KNOT_WIRE_OFFSET_FLAGS1)
+	        & KNOT_WIRE_OPCODE_MASK) >> KNOT_WIRE_OPCODE_SHIFT;
+}
+
+/*!
+ * \brief Sets the OPCODE in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param opcode OPCODE to set.
+ */
+static inline void knot_wire_set_opcode(uint8_t *packet, short opcode)
+{
+	assert(packet);
+	uint8_t *flags1 = packet + KNOT_WIRE_OFFSET_FLAGS1;
+	*flags1 = (*flags1 & ~KNOT_WIRE_OPCODE_MASK)
+	          | ((opcode) << KNOT_WIRE_OPCODE_SHIFT);
+}
+
+/*!
+ * \brief Returns the QR bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Nonzero for responses and zero for queries.
+ */
+static inline uint8_t knot_wire_get_qr(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS1) & KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Sets the QR bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_qr(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) |= KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Clears the QR bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_qr(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS1) &= ~KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Returns the RCODE from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return RCODE of the packet.
+ */
+static inline uint8_t knot_wire_get_rcode(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2)
+	       & KNOT_WIRE_RCODE_MASK;
+}
+
+/*!
+ * \brief Sets the RCODE in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ * \param rcode RCODE to set.
+ */
+static inline void knot_wire_set_rcode(uint8_t *packet, short rcode)
+{
+	assert(packet);
+	uint8_t *flags2 = packet + KNOT_WIRE_OFFSET_FLAGS2;
+	*flags2 = (*flags2 & ~KNOT_WIRE_RCODE_MASK) | (rcode);
+}
+
+/*!
+ * \brief Returns the CD bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the CD bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_cd(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2) & KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Sets the CD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_cd(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) |= KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Clears the CD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_cd(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) &= ~KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Returns the AD bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the AD bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_ad(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2) & KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Sets the AD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_ad(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) |= KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Clears the AD bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_ad(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) &= ~KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Returns the Zero bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the Zero bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_z(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2) & KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Sets the Zero bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_z(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) |= KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Clears the Zero bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_z(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) &= ~KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Returns the RA bit from wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ *
+ * \return Flags with only the RA bit according to its setting in the packet.
+ */
+static inline uint8_t knot_wire_get_ra(const uint8_t *packet)
+{
+	assert(packet);
+	return *(packet + KNOT_WIRE_OFFSET_FLAGS2) & KNOT_WIRE_RA_MASK;
+}
+
+/*!
+ * \brief Sets the RA bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_set_ra(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) |= KNOT_WIRE_RA_MASK;
+}
+
+/*!
+ * \brief Clears the RA bit in the wire format of the packet.
+ *
+ * \param packet Wire format of the packet.
+ */
+static inline void knot_wire_clear_ra(uint8_t *packet)
+{
+	assert(packet);
+	*(packet + KNOT_WIRE_OFFSET_FLAGS2) &= ~KNOT_WIRE_RA_MASK;
+}
+
+/*
+ * Functions for getting / setting / clearing flags in flags variable
+ */
+
+/*!
+ * \brief Returns the RD bit from the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ *
+ * \return Flags byte with only the RD bit according to its setting in
+ *         \a flags1.
+ */
+static inline uint8_t knot_wire_flags_get_rd(uint8_t flags1)
+{
+	return flags1 & KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Sets the RD bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_rd(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 |= KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Clears the RD bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_rd(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 &= ~KNOT_WIRE_RD_MASK;
+}
+
+/*!
+ * \brief Returns the TC bit from the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ *
+ * \return Flags byte with only the TC bit according to its setting in
+ *         \a flags1.
+ */
+static inline uint8_t knot_wire_flags_get_tc(uint8_t flags1)
+{
+	return flags1 & KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Sets the TC bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_tc(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 |= KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Clears the TC bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_tc(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 &= ~KNOT_WIRE_TC_MASK;
+}
+
+/*!
+ * \brief Returns the AA bit from the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ *
+ * \return Flags byte with only the AA bit according to its setting in
+ *         \a flags1.
+ */
+static inline uint8_t knot_wire_flags_get_aa(uint8_t flags1)
+{
+	return flags1 & KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Sets the AA bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_aa(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 |= KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Clears the AA bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_aa(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 &= ~KNOT_WIRE_AA_MASK;
+}
+
+/*!
+ * \brief Returns the OPCODE from the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ *
+ * \return OPCODE
+ */
+static inline uint8_t knot_wire_flags_get_opcode(uint8_t flags1)
+{
+	return (flags1 & KNOT_WIRE_OPCODE_MASK)
+	        >> KNOT_WIRE_OPCODE_SHIFT;
+}
+
+/*!
+ * \brief Sets the OPCODE in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ * \param opcode OPCODE to set.
+ */
+static inline void knot_wire_flags_set_opcode(uint8_t *flags1, short opcode)
+{
+	assert(flags1);
+	*flags1 = (*flags1 & ~KNOT_WIRE_OPCODE_MASK)
+	          | ((opcode) << KNOT_WIRE_OPCODE_SHIFT);
+}
+
+/*!
+ * \brief Returns the QR bit from the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ *
+ * \return Flags byte with only the QR bit according to its setting in
+ *         \a flags1.
+ */
+static inline uint8_t knot_wire_flags_get_qr(uint8_t flags1)
+{
+	return flags1 & KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Sets the QR bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_qr(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 |= KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Clears the QR bit in the first byte of flags.
+ *
+ * \param flags1 First byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_qr(uint8_t *flags1)
+{
+	assert(flags1);
+	*flags1 &= ~KNOT_WIRE_QR_MASK;
+}
+
+/*!
+ * \brief Returns the RCODE from the second byte of flags.
+ *
+ * \param flags2 First byte of DNS header flags.
+ *
+ * \return RCODE
+ */
+static inline uint8_t knot_wire_flags_get_rcode(uint8_t flags2)
+{
+	return flags2 & KNOT_WIRE_RCODE_MASK;
+}
+
+/*!
+ * \brief Sets the RCODE in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ * \param rcode RCODE to set.
+ */
+static inline void knot_wire_flags_set_rcode(uint8_t *flags2, short rcode)
+{
+	assert(flags2);
+	*flags2 = (*flags2 & ~KNOT_WIRE_RCODE_MASK) | (rcode);
+}
+
+/*!
+ * \brief Returns the CD bit from the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ *
+ * \return Flags byte with only the CD bit according to its setting in
+ *         \a flags2.
+ */
+static inline uint8_t knot_wire_flags_get_cd(uint8_t flags2)
+{
+	return flags2 & KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Sets the CD bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_cd(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 |= KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Clears the CD bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_cd(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 &= ~KNOT_WIRE_CD_MASK;
+}
+
+/*!
+ * \brief Returns the AD bit from the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ *
+ * \return Flags byte with only the AD bit according to its setting in
+ *         \a flags2.
+ */
+static inline uint8_t knot_wire_flags_get_ad(uint8_t flags2)
+{
+	return flags2 & KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Sets the AD bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_ad(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 |= KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Clears the AD bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_ad(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 &= ~KNOT_WIRE_AD_MASK;
+}
+
+/*!
+ * \brief Returns the Zero bit from the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ *
+ * \return Flags byte with only the Zero bit according to its setting in
+ *         \a flags2.
+ */
+static inline uint8_t knot_wire_flags_get_z(uint8_t flags2)
+{
+	return flags2 & KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Sets the Zero bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_z(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 |= KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Clears the Zero bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_z(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 &= ~KNOT_WIRE_Z_MASK;
+}
+
+/*!
+ * \brief Returns the RA bit from the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ *
+ * \return Flags byte with only the RA bit according to its setting in
+ *         \a flags2.
+ */
+static inline uint8_t knot_wire_flags_get_ra(uint8_t flags2)
+{
+	return flags2 & KNOT_WIRE_RA_MASK;
+}
+
+/*!
+ * \brief Sets the RA bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_set_ra(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 |= KNOT_WIRE_RA_MASK;
+}
+
+/*!
+ * \brief Clears the RA bit in the second byte of flags.
+ *
+ * \param flags2 Second byte of DNS header flags.
+ */
+static inline void knot_wire_flags_clear_ra(uint8_t *flags2)
+{
+	assert(flags2);
+	*flags2 &= ~KNOT_WIRE_RA_MASK;
+}
+
+/*
+ * Pointer manipulation
+ */
+
+enum knot_wire_pointer_consts {
+	/*! \brief DNS packet pointer designation (first two bits set to 1). */
+	KNOT_WIRE_PTR = (uint8_t)0xC0,
+	/*! \brief DNS packet minimal pointer (KNOT_WIRE_PTR + 1 zero byte). */
+	KNOT_WIRE_PTR_BASE = (uint16_t)0xC000,
+	/*! \brief DNS packet maximal offset (KNOT_WIRE_BASE complement). */
+	KNOT_WIRE_PTR_MAX = (uint16_t)0x3FFF
+};
+
+static inline int knot_wire_is_pointer(const uint8_t *pos)
+{
+	return pos && ((pos[0] & KNOT_WIRE_PTR) == KNOT_WIRE_PTR);
+}
+
+/*!
+ * \brief Creates a DNS packet pointer and stores it in wire format.
+ *
+ * \param pos Position where tu put the pointer.
+ * \param ptr Relative position of the item to which the pointer should point in
+ *            the wire format of the packet.
+ */
+static inline void knot_wire_put_pointer(uint8_t *pos, uint16_t ptr)
+{
+	knot_wire_write_u16(pos, ptr);		// Write pointer offset.
+	assert((pos[0] & KNOT_WIRE_PTR) == 0);	// Check for maximal offset.
+	pos[0] |= KNOT_WIRE_PTR;		// Add pointer mark.
+}
+
+static inline uint16_t knot_wire_get_pointer(const uint8_t *pos)
+{
+	assert(knot_wire_is_pointer(pos));			// Check pointer.
+	return (knot_wire_read_u16(pos) - KNOT_WIRE_PTR_BASE);	// Return offset.
+}
+
+_pure_ _mustcheck_
+static inline const uint8_t *knot_wire_seek_label(const uint8_t *lp, const uint8_t *wire)
+{
+	while (knot_wire_is_pointer(lp)) {
+		if (!wire)
+			return NULL;
+		lp = wire + knot_wire_get_pointer(lp);
+	}
+	return lp;
+}
+
+_pure_ _mustcheck_
+static inline const uint8_t *knot_wire_next_label(const uint8_t *lp, const uint8_t *wire)
+{
+	if (!lp || !lp[0]) /* No label after final label. */
+		return NULL;
+	return knot_wire_seek_label(lp + (lp[0] + sizeof(uint8_t)), wire);
+}
+
+/*! @} */
diff --git a/src/libknot/probe/data.c b/src/libknot/probe/data.c
new file mode 100644
index 0000000..5d831b2
--- /dev/null
+++ b/src/libknot/probe/data.c
@@ -0,0 +1,135 @@
+/*  Copyright (C) 2023 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/types.h>
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/tcp.h>
+
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "libknot/probe/probe.h"
+#include "contrib/macros.h"
+
+_public_
+int knot_probe_data_set(knot_probe_data_t *data, knot_probe_proto_t proto,
+                        const struct sockaddr_storage *local_addr,
+                        const struct sockaddr_storage *remote_addr,
+                        const knot_pkt_t *query, const knot_pkt_t *reply,
+                        uint16_t rcode)
+{
+	if (data == NULL || remote_addr == NULL || query == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	data->proto = proto;
+
+	if (remote_addr->ss_family == AF_INET) {
+		const struct sockaddr_in *sa = (struct sockaddr_in *)remote_addr;
+		const struct sockaddr_in *da = (struct sockaddr_in *)local_addr;
+
+		memcpy(data->remote.addr, &sa->sin_addr, sizeof(sa->sin_addr));
+		memset(data->remote.addr + sizeof(sa->sin_addr), 0,
+		       sizeof(data->remote.addr) - sizeof(sa->sin_addr));
+		data->remote.port = be16toh(sa->sin_port);
+
+		if (da != NULL) {
+			memcpy(data->local.addr, &da->sin_addr, sizeof(da->sin_addr));
+			memset(data->local.addr + sizeof(da->sin_addr), 0,
+			       sizeof(data->local.addr) - sizeof(da->sin_addr));
+			data->local.port = be16toh(da->sin_port);
+		} else {
+			memset(&data->local, 0, sizeof(data->local));
+		}
+
+		data->ip = 4;
+	} else if (remote_addr->ss_family == AF_INET6) {
+		const struct sockaddr_in6 *sa = (struct sockaddr_in6 *)remote_addr;
+		const struct sockaddr_in6 *da = (struct sockaddr_in6 *)local_addr;
+
+		memcpy(data->remote.addr, &sa->sin6_addr, sizeof(sa->sin6_addr));
+		data->remote.port = be16toh(sa->sin6_port);
+
+		if (da != NULL) {
+			memcpy(data->local.addr, &da->sin6_addr, sizeof(da->sin6_addr));
+			data->local.port = be16toh(da->sin6_port);
+		} else {
+			memset(&data->local, 0, sizeof(data->local));
+		}
+
+		data->ip = 6;
+	} else {
+		memset(&data->remote, 0, sizeof(data->remote));
+		memset(&data->local, 0, sizeof(data->local));
+
+		data->ip = 0;
+	}
+
+	if (reply != NULL) {
+		memcpy(&data->reply.hdr, reply->wire, sizeof(data->reply.hdr));
+		data->reply.size = knot_pkt_size(reply);
+		data->reply.rcode = rcode;
+	} else {
+		memset(&data->reply, 0, sizeof(data->reply));
+	}
+	data->reply.ede = KNOT_PROBE_DATA_EDE_NONE;
+
+	data->tcp_rtt = 0;
+
+	if (query->opt_rr != NULL) {
+		data->query_edns.options = 0;
+		data->query_edns.payload = knot_edns_get_payload(query->opt_rr);
+		data->query_edns.version = knot_edns_get_version(query->opt_rr);
+		data->query_edns.present = 1;
+		data->query_edns.flag_do = knot_edns_do(query->opt_rr);
+		if (query->edns_opts != NULL) {
+			for (int i = 0; i <= KNOT_EDNS_MAX_OPTION_CODE; i++) {
+				if (query->edns_opts->ptr[i] != NULL) {
+					data->query_edns.options |= (1 << i);
+				}
+			}
+		}
+		data->query_edns.reserved = 0;
+	} else {
+		memset(&data->query_edns, 0, sizeof(data->query_edns));
+	}
+
+	memcpy(&data->query.hdr, query->wire, sizeof(data->query.hdr));
+	data->query.size = knot_pkt_size(query);
+	data->query.qclass = knot_pkt_qclass(query);
+	data->query.qtype = knot_pkt_qtype(query);
+	data->query.qname_len = knot_dname_size(knot_pkt_qname(query));
+	memcpy(data->query.qname, knot_pkt_qname(query), data->query.qname_len);
+	memset(data->query.qname + data->query.qname_len, 0,
+	       MIN(8, sizeof(data->query.qname) - data->query.qname_len));
+
+	return KNOT_EOK;
+}
+
+_public_
+uint32_t knot_probe_tcp_rtt(int sockfd)
+{
+#if defined(__linux__)
+	struct tcp_info info = { 0 };
+	socklen_t info_length = sizeof(info);
+	if (getsockopt(sockfd, SOL_TCP, TCP_INFO, &info, &info_length) == 0) {
+		return info.tcpi_rtt;
+	}
+#endif
+
+	return 0;
+}
diff --git a/src/libknot/probe/data.h b/src/libknot/probe/data.h
new file mode 100644
index 0000000..efd5135
--- /dev/null
+++ b/src/libknot/probe/data.h
@@ -0,0 +1,132 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief A DNS traffic probe data structure.
+ *
+ * \addtogroup probe
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "libknot/consts.h"
+#include "libknot/packet/pkt.h"
+
+/*! EDE absence indication. */
+#define KNOT_PROBE_DATA_EDE_NONE	0xFFFF
+
+/*! Data transport protocol types. */
+typedef enum {
+	KNOT_PROBE_PROTO_UDP = 0,
+	KNOT_PROBE_PROTO_TCP,
+	KNOT_PROBE_PROTO_QUIC,
+	KNOT_PROBE_PROTO_TLS,
+	KNOT_PROBE_PROTO_HTTPS,
+} knot_probe_proto_t;
+
+/*! DNS message header in wire format (network byte order!). */
+typedef struct {
+	uint16_t id;
+	uint8_t byte3; /*!< QR, OPCODE, AA, TC, RD. */
+	uint8_t byte4; /*!< RA, Z, AD, CD, RCODE. */
+	uint16_t questions;
+	uint16_t answers;
+	uint16_t authorities;
+	uint16_t additionals;
+} knot_probe_data_wire_hdr_t;
+
+/*! Probe data unit. */
+typedef struct {
+	uint8_t ip;    /*!< IP protocol: 4 or 6. */
+	uint8_t proto; /*!< Transport protocol \ref knot_probe_proto_t. */
+
+	struct {
+		uint8_t addr[16]; /*!< Query destination address. */
+		uint16_t port;    /*!< Query destination port. */
+	} local;
+
+	struct {
+		uint8_t addr[16]; /*!< Query source address. */
+		uint16_t port;    /*!< Query source port. */
+	} remote;
+
+	struct {
+		knot_probe_data_wire_hdr_t hdr; /*!< DNS reply header. */
+		uint16_t size;  /*!< DNS reply size (0 if no reply). */
+		uint16_t rcode; /*!< Final RCODE (header + EDNS + TSIG). */
+		uint16_t ede;   /*!< EDE code if present. */
+	} reply;
+
+	uint32_t tcp_rtt; /*!< Average TCP RTT in microseconds. */
+
+	struct {
+		uint32_t options; /*!< EDNS options bit map (e.g. NSID ~ 1 << 3). */
+		uint16_t payload; /*!< EDNS payload size. */
+		uint8_t version;  /*!< EDNS version. */
+		uint8_t present  : 1; /*!< EDNS presence indication. */
+		uint8_t flag_do  : 1; /*!< DO flag indication. */
+		uint8_t reserved : 6; /*!< Unused. */
+	} query_edns;
+
+	struct {
+		knot_probe_data_wire_hdr_t hdr; /*!< DNS query header. */
+		uint16_t size;     /*!< DNS query size. */
+		uint16_t qclass;   /*!< QCLASS. */
+		uint16_t qtype;    /*!< QTYPE. */
+		uint8_t qname_len; /*!< QNAME length. */
+		uint8_t qname[KNOT_DNAME_MAXLEN]; /*!< QNAME. */
+	} query;
+} knot_probe_data_t;
+
+/*!
+ * \brief Initializes a probe data unit.
+ *
+ * \note 'reply.ede' and 'tcp.rtt' are zeroed only and require further setting.
+ *
+ * \param data         Output probe data unit.
+ * \param proto        Transport protocol \ref knot_probe_proto_t.
+ * \param local_addr   Query destination address (optional).
+ * \param remote_addr  Query source address.
+ * \param query        Query packet.
+ * \param reply        Reply packet (optional).
+ * \param rcode        Extended rcode (combination of RCODE, EDNS, TSIG).
+ *
+ * \retval KNOT_EOK  Success.
+ * \return KNOT_E*   If error.
+ */
+int knot_probe_data_set(knot_probe_data_t *data, knot_probe_proto_t proto,
+                        const struct sockaddr_storage *local_addr,
+                        const struct sockaddr_storage *remote_addr,
+                        const knot_pkt_t *query, const knot_pkt_t *reply,
+                        uint16_t rcode);
+
+/*!
+ * \brief Gets averate TCP RRT for a given socket descriptor.
+ *
+ * \note Implemented on Linux only!
+ *
+ * \param sockfd  Socket descriptor of a TCP connection.
+ *
+ * \return Average TCP RTT in microseconds.
+ */
+uint32_t knot_probe_tcp_rtt(int sockfd);
+
+/*! @} */
diff --git a/src/libknot/probe/probe.c b/src/libknot/probe/probe.c
new file mode 100644
index 0000000..341c48b
--- /dev/null
+++ b/src/libknot/probe/probe.c
@@ -0,0 +1,228 @@
+/*  Copyright (C) 2023 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 <fcntl.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/probe/probe.h"
+#include "contrib/time.h"
+
+struct knot_probe {
+	struct sockaddr_un path;
+	uint32_t last_unconn_time;
+	bool consumer;
+	int fd;
+};
+
+_public_
+knot_probe_t *knot_probe_alloc(void)
+{
+	knot_probe_t *probe = calloc(1, sizeof(*probe));
+	if (probe == NULL) {
+		return NULL;
+	}
+
+	probe->fd = -1;
+
+	return probe;
+}
+
+_public_
+void knot_probe_free(knot_probe_t *probe)
+{
+	if (probe == NULL) {
+		return;
+	}
+
+	close(probe->fd);
+	if (probe->consumer) {
+		(void)unlink(probe->path.sun_path);
+	}
+	free(probe);
+}
+
+static int probe_connect(knot_probe_t *probe)
+{
+	return connect(probe->fd, (const struct sockaddr *)(&probe->path),
+	               sizeof(probe->path));
+}
+
+static int probe_init(knot_probe_t *probe, const char *dir, uint16_t idx)
+{
+	if (probe == NULL || dir == NULL || idx == 0) {
+		return KNOT_EINVAL;
+	}
+
+	probe->path.sun_family = AF_UNIX;
+	int ret = snprintf(probe->path.sun_path, sizeof(probe->path.sun_path),
+	                   "%s/probe%02u.sock", dir, idx);
+	if (ret < 0 || ret >= sizeof(probe->path.sun_path)) {
+		return KNOT_ERANGE;
+	}
+
+	probe->fd = socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (probe->fd < 0) {
+		return knot_map_errno();
+	}
+
+	if (fcntl(probe->fd, F_SETFL, O_NONBLOCK) == -1) {
+		close(probe->fd);
+		probe->fd = -1;
+		return knot_map_errno();
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_probe_set_producer(knot_probe_t *probe, const char *dir, uint16_t idx)
+{
+	int ret = probe_init(probe, dir, idx);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	ret = probe_connect(probe);
+	if (ret != 0) {
+		return KNOT_ECONN;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_probe_set_consumer(knot_probe_t *probe, const char *dir, uint16_t idx)
+{
+	int ret = probe_init(probe, dir, idx);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	probe->consumer = true;
+
+	(void)unlink(probe->path.sun_path);
+
+	ret = bind(probe->fd, (const struct sockaddr *)(&probe->path),
+	           sizeof(probe->path));
+	if (ret != 0) {
+		return knot_map_errno();
+	}
+
+	if (chmod(probe->path.sun_path, S_IWUSR | S_IWGRP | S_IWOTH) != 0) {
+		close(probe->fd);
+		return knot_map_errno();
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_probe_fd(knot_probe_t *probe)
+{
+	if (probe == NULL) {
+		return -1;
+	}
+
+	return probe->fd;
+}
+
+_public_
+int knot_probe_produce(knot_probe_t *probe, const knot_probe_data_t *data, uint8_t count)
+{
+	if (probe == NULL || data == NULL || count != 1) {
+		return KNOT_EINVAL;
+	}
+
+	size_t used_len = sizeof(*data) - KNOT_DNAME_MAXLEN + data->query.qname_len;
+	if (send(probe->fd, data, used_len, 0) == -1) {
+		struct timespec now = time_now();
+		if (now.tv_sec - probe->last_unconn_time > 2) {
+			probe->last_unconn_time = now.tv_sec;
+			if ((errno == ENOTCONN || errno == ECONNREFUSED) &&
+			    probe_connect(probe) == 0 &&
+			    send(probe->fd, data, used_len, 0) > 0) {
+				return KNOT_EOK;
+			}
+		}
+		return knot_map_errno();
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_probe_consume(knot_probe_t *probe, knot_probe_data_t *data, uint8_t count,
+                       int timeout_ms)
+{
+	if (probe == NULL || data == NULL || count == 0) {
+		return KNOT_EINVAL;
+	}
+
+#ifdef ENABLE_RECVMMSG
+	struct mmsghdr msgs[count];
+	struct iovec iovecs[count];
+
+	memset(msgs, 0, sizeof(msgs));
+	for (int i = 0; i < count; i++) {
+		iovecs[i].iov_base         = &(data[i]);
+		iovecs[i].iov_len          = sizeof(*data);
+		msgs[i].msg_hdr.msg_iov    = &iovecs[i];
+		msgs[i].msg_hdr.msg_iovlen = 1;
+	}
+#else
+	struct iovec iov = {
+		.iov_base = data,
+		.iov_len  = sizeof(*data)
+	};
+	struct msghdr msg = {
+		.msg_iov    = &iov,
+		.msg_iovlen = 1
+	};
+#endif
+
+	struct pollfd pfd = { .fd = probe->fd, .events = POLLIN };
+	int ret = poll(&pfd, 1, timeout_ms);
+	if (ret == -1) {
+		return knot_map_errno();
+	} else if ((pfd.revents & POLLIN) == 0) {
+		return 0;
+	}
+
+#ifdef ENABLE_RECVMMSG
+	ret = recvmmsg(probe->fd, msgs, count, 0, NULL);
+#else
+	ret = recvmsg(probe->fd, &msg, 0);
+#endif
+	if (ret == -1) {
+		return knot_map_errno();
+	}
+
+#ifdef ENABLE_RECVMMSG
+	return ret;
+#else
+	return (ret > 0 ? 1 : 0);
+#endif
+}
diff --git a/src/libknot/probe/probe.h b/src/libknot/probe/probe.h
new file mode 100644
index 0000000..24c8067
--- /dev/null
+++ b/src/libknot/probe/probe.h
@@ -0,0 +1,116 @@
+/*  Copyright (C) 2023 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief A DNS traffic probe interface.
+ *
+ * \addtogroup probe
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/probe/data.h"
+
+/*! A probe context. */
+struct knot_probe;
+typedef struct knot_probe knot_probe_t;
+
+/*!
+ * Allocates a probe context.
+ *
+ * \return Probe context.
+ */
+knot_probe_t *knot_probe_alloc(void);
+
+/*!
+ * \brief Deallocates a probe.
+ *
+ * \param probe  Probe context.
+ */
+void knot_probe_free(knot_probe_t *probe);
+
+/*!
+ * \brief Initializes one probe producer.
+ *
+ * \param probe  Probe context.
+ * \param dir    Unix socket directory.
+ * \param idx    Probe ID (counted from 1).
+ *
+ * \retval KNOT_EOK    Success.
+ * \retval KNOT_ECONN  Initial connection failed.
+ * \return KNOT_E*     If error.
+ */
+int knot_probe_set_producer(knot_probe_t *probe, const char *dir, uint16_t idx);
+
+/*!
+ * \brief Initializes one probe consumer.
+ *
+ * \note The socket permissions are set to 0222!
+ *
+ * \param probe  Probe context.
+ * \param dir    Unix socket directory.
+ * \param idx    Probe ID (counted from 1).
+ *
+ * \retval KNOT_EOK  Success.
+ * \return KNOT_E*   If error.
+ */
+int knot_probe_set_consumer(knot_probe_t *probe, const char *dir, uint16_t idx);
+
+/*!
+ * \brief Returns file descriptor of the probe.
+ *
+ * \param probe  Probe context.
+ */
+int knot_probe_fd(knot_probe_t *probe);
+
+/*!
+ * \brief Sends data units to a probe.
+ *
+ * \note Data arrays of length > 1 are not supported yet.
+ *
+ * If send fails due to unconnected socket anf if not connected for at least
+ * 2 seconds, reconnection is attempted and if successful, the send operation
+ * is repeated.
+ *
+ * \param probe  Probe context.
+ * \param data   Array of data units.
+ * \param count  Length of data unit array.
+ *
+ * \retval KNOT_EOK  Success.
+ * \return KNOT_E*   If error.
+ */
+int knot_probe_produce(knot_probe_t *probe, const knot_probe_data_t *data, uint8_t count);
+
+/*!
+ * \brief Receives data units from a probe.
+ *
+ * This function blocks on poll until a data unit is received or timeout is hit.
+ *
+ * \param probe       Probe context.
+ * \param data        Array of data units.
+ * \param count       Length of data unit array.
+ * \param timeout_ms  Poll timeout in milliseconds (-1 means infinity).
+ *
+ * \retval >= 0    Number of data units received.
+ * \return KNOT_E* If error.
+ */
+int knot_probe_consume(knot_probe_t *probe, knot_probe_data_t *data, uint8_t count,
+                       int timeout_ms);
+
+/*! @} */
diff --git a/src/libknot/rdata.h b/src/libknot/rdata.h
new file mode 100644
index 0000000..1891f91
--- /dev/null
+++ b/src/libknot/rdata.h
@@ -0,0 +1,101 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief API for manipulating rdata.
+ *
+ * \addtogroup rr
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+/*!< \brief Maximum rdata length. */
+#define KNOT_RDATA_MAXLEN 65535
+
+/*!
+ * \brief Structure holding single rdata payload.
+ */
+typedef struct {
+	uint16_t len;
+	uint8_t data[];
+} knot_rdata_t;
+
+/*!
+ * \brief Inits rdata structure.
+ *
+ * \param rdata  Rdata structure to be initialized. At least knot_rdata_size bytes
+ *               must fit into it!
+ * \param len    Rdata length.
+ * \param data   Rdata itself.
+ */
+inline static void knot_rdata_init(knot_rdata_t *rdata, uint16_t len, const uint8_t *data)
+{
+	assert(rdata);
+	rdata->len = len;
+	if (rdata->len > 0) {
+		assert(data);
+		memcpy(rdata->data, data, len);
+		if (len & 1) { // Initialize possible padding to mute analytical tools.
+			rdata->data[len] = 0;
+		}
+	}
+}
+
+/*!
+ * \brief Returns actual size of the rdata structure for given rdata length.
+ *
+ * \param len  Rdata length.
+ *
+ * \return Actual structure size.
+ */
+inline static size_t knot_rdata_size(uint16_t len)
+{
+	return sizeof(uint16_t) + len + (len & 1);
+}
+
+/*!
+ * \brief Canonical comparison of two rdata structures.
+ *
+ * \param rdata1  First rdata to compare.
+ * \param rdata2  Second rdata to compare.
+ *
+ * \retval = 0 if rdata1 == rdata2.
+ * \retval < 0 if rdata1 <  rdata2.
+ * \retval > 0 if rdata1 >  rdata2.
+ */
+inline static int knot_rdata_cmp(const knot_rdata_t *rdata1, const knot_rdata_t *rdata2)
+{
+	assert(rdata1);
+	assert(rdata2);
+
+	size_t common_len = (rdata1->len <= rdata2->len) ? rdata1->len : rdata2->len;
+
+	int cmp = memcmp(rdata1->data, rdata2->data, common_len);
+	if (cmp == 0 && rdata1->len != rdata2->len) {
+		cmp = rdata1->len < rdata2->len ? -1 : 1;
+	}
+	return cmp;
+}
+
+/*! @} */
diff --git a/src/libknot/rdataset.c b/src/libknot/rdataset.c
new file mode 100644
index 0000000..03e0784
--- /dev/null
+++ b/src/libknot/rdataset.c
@@ -0,0 +1,371 @@
+/*  Copyright (C) 2022 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 <string.h>
+#include <stdlib.h>
+
+#include "libknot/attribute.h"
+#include "libknot/rdataset.h"
+#include "contrib/mempattern.h"
+
+static knot_rdata_t *rr_seek(const knot_rdataset_t *rrs, uint16_t pos)
+{
+	assert(rrs);
+	assert(0 < rrs->count);
+	assert(pos < rrs->count);
+
+	uint8_t *raw = (uint8_t *)(rrs->rdata);
+	for (uint16_t i = 0; i < pos; ++i) {
+		raw += knot_rdata_size(((knot_rdata_t *)raw)->len);
+	}
+
+	return (knot_rdata_t *)raw;
+}
+
+static int find_rr_pos(const knot_rdataset_t *rrs, const knot_rdata_t *rr)
+{
+	knot_rdata_t *search_rr = rrs->rdata;
+	for (uint16_t i = 0; i < rrs->count; ++i) {
+		if (knot_rdata_cmp(rr, search_rr) == 0) {
+			return i;
+		}
+		search_rr = knot_rdataset_next(search_rr);
+	}
+
+	return KNOT_ENOENT;
+}
+
+static int add_rr_at(knot_rdataset_t *rrs, const knot_rdata_t *rr, knot_rdata_t *ins_pos,
+                     knot_mm_t *mm)
+{
+	assert(rrs);
+	assert(rr);
+	const size_t ins_offset = (uint8_t *)ins_pos - (uint8_t *)rrs->rdata;
+	assert(ins_offset <= rrs->size);
+
+	if (rrs->count == UINT16_MAX) {
+		return KNOT_ESPACE;
+	} else if (rrs->size > UINT32_MAX - knot_rdata_size(UINT16_MAX)) {
+		return KNOT_ESPACE;
+	}
+
+	const size_t rr_size = knot_rdata_size(rr->len);
+
+	// Realloc RDATA.
+	knot_rdata_t *tmp = mm_realloc(mm, rrs->rdata, rrs->size + rr_size,
+	                               rrs->size);
+	if (tmp == NULL) {
+		return KNOT_ENOMEM;
+	} else {
+		rrs->rdata = tmp;
+	}
+
+	uint8_t *ins_pos_raw = (uint8_t *)rrs->rdata + ins_offset;
+	// RDATA may have to be rearanged.  Moving zero-length region is OK.
+	memmove(ins_pos_raw + rr_size, ins_pos_raw, rrs->size - ins_offset);
+
+	// Set new RDATA.
+	knot_rdata_init((knot_rdata_t *)ins_pos_raw, rr->len, rr->data);
+	rrs->count++;
+	rrs->size += rr_size;
+
+	return KNOT_EOK;
+}
+
+static int remove_rr_at(knot_rdataset_t *rrs, uint16_t pos, knot_mm_t *mm)
+{
+	assert(rrs);
+	assert(0 < rrs->count);
+	assert(pos < rrs->count);
+
+	knot_rdata_t *old_rr = rr_seek(rrs, pos);
+	knot_rdata_t *last_rr = rr_seek(rrs, rrs->count - 1);
+
+	size_t old_size = knot_rdata_size(old_rr->len);
+
+	// Move RDATA.
+	uint8_t *old_threshold = (uint8_t *)old_rr + old_size;
+	uint8_t *last_threshold = (uint8_t *)last_rr + knot_rdata_size(last_rr->len);
+	assert(old_threshold <= last_threshold);
+	memmove(old_rr, old_threshold, last_threshold - old_threshold);
+
+	if (rrs->count > 1) {
+		// Realloc RDATA.
+		knot_rdata_t *tmp = mm_realloc(mm, rrs->rdata, rrs->size - old_size,
+		                               rrs->size);
+		if (tmp == NULL) {
+			return KNOT_ENOMEM;
+		} else {
+			rrs->rdata = tmp;
+		}
+	} else {
+		// Free RDATA.
+		mm_free(mm, rrs->rdata);
+		rrs->rdata = NULL;
+	}
+	rrs->count--;
+	rrs->size -= old_size;
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_rdataset_clear(knot_rdataset_t *rrs, knot_mm_t *mm)
+{
+	if (rrs == NULL) {
+		return;
+	}
+
+	mm_free(mm, rrs->rdata);
+	knot_rdataset_init(rrs);
+}
+
+_public_
+int knot_rdataset_copy(knot_rdataset_t *dst, const knot_rdataset_t *src, knot_mm_t *mm)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	dst->count = src->count;
+	dst->size = src->size;
+
+	if (src->count > 0) {
+		assert(src->rdata != NULL);
+		dst->rdata = mm_alloc(mm, src->size);
+		if (dst->rdata == NULL) {
+			return KNOT_ENOMEM;
+		}
+		memcpy(dst->rdata, src->rdata, src->size);
+	} else {
+		assert(src->size == 0);
+		dst->rdata = NULL;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+knot_rdata_t *knot_rdataset_at(const knot_rdataset_t *rrs, uint16_t pos)
+{
+	if (rrs == NULL || rrs->count == 0 || pos >= rrs->count) {
+		return NULL;
+	}
+
+	return rr_seek(rrs, pos);
+}
+
+_public_
+int knot_rdataset_add(knot_rdataset_t *rrs, const knot_rdata_t *rr, knot_mm_t *mm)
+{
+	if (rrs == NULL || rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Optimize a little for insertion at the end, for larger RRsets.
+	if (rrs->count > 4) {
+		knot_rdata_t *last = rr_seek(rrs, rrs->count - 1);
+		if (knot_rdata_cmp(last, rr) < 0) {
+			return add_rr_at(rrs, rr, knot_rdataset_next(last), mm);
+		}
+	}
+
+	// Look for the right place to insert.
+	knot_rdata_t *ins_pos = rrs->rdata;
+	for (int i = 0; i < rrs->count; ++i, ins_pos = knot_rdataset_next(ins_pos)) {
+		int cmp = knot_rdata_cmp(ins_pos, rr);
+		if (cmp == 0) {
+			// Duplicate - no need to add this RR.
+			return KNOT_EOK;
+		} else if (cmp > 0) {
+			// Found position to insert.
+			return add_rr_at(rrs, rr, ins_pos, mm);
+		}
+	}
+
+	assert(rrs->rdata == NULL || (uint8_t *)rrs->rdata + rrs->size == (uint8_t *)ins_pos);
+
+	// If flow gets here, it means that we should insert at the current position (append).
+	return add_rr_at(rrs, rr, ins_pos, mm);
+}
+
+_public_
+bool knot_rdataset_eq(const knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2)
+{
+	if (rrs1 == NULL || rrs2 == NULL || rrs1->count != rrs2->count) {
+		return false;
+	}
+
+	knot_rdata_t *rr1 = rrs1->rdata;
+	knot_rdata_t *rr2 = rrs2->rdata;
+	for (uint16_t i = 0; i < rrs1->count; ++i) {
+		if (knot_rdata_cmp(rr1, rr2) != 0) {
+			return false;
+		}
+		rr1 = knot_rdataset_next(rr1);
+		rr2 = knot_rdataset_next(rr2);
+	}
+
+	return true;
+}
+
+_public_
+bool knot_rdataset_member(const knot_rdataset_t *rrs, const knot_rdata_t *rr)
+{
+	if (rrs == NULL) {
+		return false;
+	}
+
+	knot_rdata_t *cmp_rr = rrs->rdata;
+	for (uint16_t i = 0; i < rrs->count; ++i) {
+		int cmp = knot_rdata_cmp(cmp_rr, rr);
+		if (cmp == 0) {
+			// Match.
+			return true;
+		} else if (cmp > 0) {
+			// 'Greater' RR present, no need to continue.
+			return false;
+		}
+		cmp_rr = knot_rdataset_next(cmp_rr);
+	}
+
+	return false;
+}
+
+_public_
+bool knot_rdataset_subset(const knot_rdataset_t *subset, const knot_rdataset_t *of)
+{
+	if (subset == NULL || (of != NULL && subset->rdata == of->rdata)) {
+		return true;
+	}
+
+	knot_rdata_t *rd = subset->rdata;
+	for (uint16_t i = 0; i < subset->count; ++i) {
+		if (!knot_rdataset_member(of, rd)) {
+			return false;
+		}
+		rd = knot_rdataset_next(rd);
+	}
+
+	return true;
+}
+
+_public_
+int knot_rdataset_merge(knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2,
+                        knot_mm_t *mm)
+{
+	if (rrs1 == NULL || rrs2 == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdata_t *rr2 = rrs2->rdata;
+	for (uint16_t i = 0; i < rrs2->count; ++i) {
+		int ret = knot_rdataset_add(rrs1, rr2, mm);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		rr2 = knot_rdataset_next(rr2);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_rdataset_intersect(const knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2,
+                            knot_rdataset_t *out, knot_mm_t *mm)
+{
+	if (rrs1 == NULL || rrs2 == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdataset_init(out);
+	knot_rdata_t *rr1 = rrs1->rdata;
+	for (uint16_t i = 0; i < rrs1->count; ++i) {
+		if (knot_rdataset_member(rrs2, rr1)) {
+			// Add RR into output intersection RRSet.
+			int ret = knot_rdataset_add(out, rr1, mm);
+			if (ret != KNOT_EOK) {
+				knot_rdataset_clear(out, mm);
+				return ret;
+			}
+		}
+		rr1 = knot_rdataset_next(rr1);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_rdataset_intersect2(knot_rdataset_t *from, const knot_rdataset_t *what,
+                             knot_mm_t *mm)
+{
+	if (from == NULL || what == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (from->rdata == what->rdata) {
+		return KNOT_EOK;
+	}
+
+	knot_rdata_t *rr1 = from->rdata;
+	for (uint16_t i = 0; i < from->count; ) {
+		if (!knot_rdataset_member(what, rr1)) {
+			int ret = remove_rr_at(from, i, mm);
+			if (ret != KNOT_EOK) {
+				return ret;
+			}
+			if (i < from->count) {
+				// Just to make sure rr1 remains valid if re-allocated.
+				rr1 = rr_seek(from, i);
+			}
+		} else {
+			i++;
+			rr1 = knot_rdataset_next(rr1);
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_rdataset_subtract(knot_rdataset_t *from, const knot_rdataset_t *what,
+                           knot_mm_t *mm)
+{
+	if (from == NULL || what == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (from->rdata == what->rdata) {
+		knot_rdataset_clear(from, mm);
+		knot_rdataset_init((knot_rdataset_t *) what);
+		return KNOT_EOK;
+	}
+
+	knot_rdata_t *to_remove = what->rdata;
+	for (uint16_t i = 0; i < what->count; ++i) {
+		int pos_to_remove = find_rr_pos(from, to_remove);
+		if (pos_to_remove >= 0) {
+			int ret = remove_rr_at(from, pos_to_remove, mm);
+			if (ret != KNOT_EOK) {
+				return ret;
+			}
+		}
+		to_remove = knot_rdataset_next(to_remove);
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/rdataset.h b/src/libknot/rdataset.h
new file mode 100644
index 0000000..6d98086
--- /dev/null
+++ b/src/libknot/rdataset.h
@@ -0,0 +1,218 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief API for manipulating RR arrays.
+ *
+ * \addtogroup rr
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "libknot/errcode.h"
+#include "libknot/mm_ctx.h"
+#include "libknot/rdata.h"
+
+/*!< \brief Set of RRs. */
+typedef struct {
+	uint16_t count;      /*!< \brief Count of RRs stored in the structure. */
+	uint32_t size;       /*!< \brief Size of the rdata array. */
+	knot_rdata_t *rdata; /*!< \brief Serialized rdata, canonically sorted. */
+} knot_rdataset_t;
+
+/*!
+ * \brief Initializes RRS structure.
+ *
+ * \param rrs  Structure to be initialized.
+ */
+inline static void knot_rdataset_init(knot_rdataset_t *rrs)
+{
+	if (rrs != NULL) {
+		rrs->count = 0;
+		rrs->size = 0;
+		rrs->rdata = NULL;
+	}
+}
+
+/*!
+ * \brief Advance to the next rdata in a rdataset.
+ *
+ * Useful for iteration.
+ *
+ * \note Ensure that this operation makes sense!
+ *
+ * \param rr  Current RR.
+ *
+ * \return Next RR.
+ */
+static inline knot_rdata_t *knot_rdataset_next(knot_rdata_t *rr)
+{
+	assert(rr);
+	return (knot_rdata_t *)((uint8_t *)rr + knot_rdata_size(rr->len));
+}
+
+/*!
+ * \brief Frees data initialized by RRS structure, but not the structure itself.
+ *
+ * \param rrs  Structure to be cleared.
+ * \param mm   Memory context used to create allocations.
+ */
+void knot_rdataset_clear(knot_rdataset_t *rrs, knot_mm_t *mm);
+
+/*!
+ * \brief Deep copies RRS structure. All data are duplicated.
+ *
+ * \param dst  Copy destination.
+ * \param src  Copy source.
+ * \param mm   Memory context.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_copy(knot_rdataset_t *dst, const knot_rdataset_t *src, knot_mm_t *mm);
+
+/*!
+ * \brief Gets RR from RRS structure, using given position.
+ *
+ * \param rrs  RRS structure to get RR from.
+ * \param pos  Position to use (counted from 0).
+ *
+ * \return Pointer to RR at \a pos position.
+ */
+knot_rdata_t *knot_rdataset_at(const knot_rdataset_t *rrs, uint16_t pos);
+
+/*!
+ * \brief Adds single RR into RRS structure. All data are copied.
+ *
+ * \param rrs  RRS structure to add RR into.
+ * \param rr   RR to add.
+ * \param mm   Memory context.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_add(knot_rdataset_t *rrs, const knot_rdata_t *rr, knot_mm_t *mm);
+
+/*!
+ * \brief RRS equality check.
+ *
+ * \param rrs1  First RRS to be compared.
+ * \param rrs2  Second RRS to be compared.
+ *
+ * \retval true if rrs1 == rrs2.
+ * \retval false if rrs1 != rrs2.
+ */
+bool knot_rdataset_eq(const knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2);
+
+/*!
+ * \brief Returns true if \a rr is present in \a rrs, false otherwise.
+ *
+ * \param rrs  RRS to search in.
+ * \param rr   RR to compare with.
+ *
+ * \retval true if \a rr is present in \a rrs.
+ * \retval false if \a rr is not present in \a rrs.
+ */
+bool knot_rdataset_member(const knot_rdataset_t *rrs, const knot_rdata_t *rr);
+
+/*!
+ * \brief Returns true if \a subset is a sub-set of \a of, false otherwise.
+ *
+ * \param subset  RRS to check.
+ * \param of      RRS to search in.
+ *
+ * \retval true if \a subset is a sub-set of \a of.
+ * \retval false if \a subset is not a sub-set of \a of.
+ */
+bool knot_rdataset_subset(const knot_rdataset_t *subset, const knot_rdataset_t *of);
+
+/*!
+ * \brief Merges two RRS into the first one. Second RRS is left intact.
+ *        Canonical order is preserved.
+ *
+ * \param rrs1  Destination RRS (merge here).
+ * \param rrs2  RRS to be merged (merge from).
+ * \param mm    Memory context.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_merge(knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2,
+                        knot_mm_t *mm);
+
+/*!
+ * \brief RRS set-like intersection. Full compare is done.
+ *
+ * \param rrs1  First RRS to intersect.
+ * \param rrs2  Second RRS to intersect.
+ * \param out   Output RRS with intersection, RDATA are created anew.
+ * \param mm    Memory context. Will be used to create new RDATA.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_intersect(const knot_rdataset_t *rrs1, const knot_rdataset_t *rrs2,
+                            knot_rdataset_t *out, knot_mm_t *mm);
+
+/*!
+ * \brief Does set-like RRS intersection. \a from RRS is changed.
+ *
+ * \param from  RRS to be modified by intersection.
+ * \param what  RRS to intersect.
+ * \param mm    Memory context use to reallocated \a from data.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_intersect2(knot_rdataset_t *from, const knot_rdataset_t *what,
+                             knot_mm_t *mm);
+
+/*!
+ * \brief Does set-like RRS subtraction. \a from RRS is changed.
+ *
+ * \param from  RRS to subtract from.
+ * \param what  RRS to subtract.
+ * \param mm    Memory context use to reallocated \a from data.
+ *
+ * \return KNOT_E*
+ */
+int knot_rdataset_subtract(knot_rdataset_t *from, const knot_rdataset_t *what,
+                           knot_mm_t *mm);
+
+/*!
+ * \brief Removes single RR from RRS structure.
+ *
+ * \param rrs  RRS structure to remove RR from.
+ * \param rr   RR to remove.
+ * \param mm   Memory context.
+ *
+ * \return KNOT_E*
+ */
+inline static int knot_rdataset_remove(knot_rdataset_t *rrs, const knot_rdata_t *rr,
+                                       knot_mm_t *mm)
+{
+	if (rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdataset_t rrs_rm = { 1, knot_rdata_size(rr->len), (knot_rdata_t *)rr };
+	return knot_rdataset_subtract(rrs, &rrs_rm, mm);
+}
+
+/*! @} */
diff --git a/src/libknot/rrset-dump.c b/src/libknot/rrset-dump.c
new file mode 100644
index 0000000..dd814de
--- /dev/null
+++ b/src/libknot/rrset-dump.c
@@ -0,0 +1,2292 @@
+/*  Copyright (C) 2023 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 <arpa/inet.h>
+#include <inttypes.h>
+#include <math.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "libdnssec/binary.h"
+#include "libdnssec/key.h"
+#include "libdnssec/keytag.h"
+#include "libknot/attribute.h"
+#include "libknot/rrset-dump.h"
+#include "libknot/codes.h"
+#include "libknot/consts.h"
+#include "libknot/descriptor.h"
+#include "libknot/errcode.h"
+#include "libknot/lookup.h"
+#include "libknot/rrtype/rrsig.h"
+#include "libknot/wire.h"
+#include "contrib/base32hex.h"
+#include "contrib/base64.h"
+#include "contrib/color.h"
+#include "contrib/ctype.h"
+#include "contrib/musl/inet_ntop.h"
+#include "contrib/time.h"
+#include "contrib/wire_ctx.h"
+
+#define RRSET_DUMP_LIMIT (2 * 1024 * 1024)
+
+#define TAB_WIDTH		8
+#define BLOCK_WIDTH		40
+#define BLOCK_INDENT		"\n\t\t\t\t"
+
+#define LOC_ZERO		2147483648	// 2^31
+
+/*! \brief macros with repetitive (mostly error-checking) code of methods from first section of this file */
+#define CHECK_PRET if (p->ret < 0) return;
+#define CHECK_INMAX(mininmax) if (p->in_max < (mininmax)) { p->ret = -1; return; }
+#define CHECK_RET_OUTMAX_SNPRINTF if (ret <= 0 || (size_t)ret >= p->out_max) { p->ret = -1; return; }
+#define STRING_TERMINATION if (p->out_max > 0) { *p->out = '\0'; } else { p->ret = -1; return; }
+#define FILL_IN_INPUT(pdata) if (memcpy(&(pdata), p->in, in_len) == NULL) { p->ret = -1; return; }
+#define CHECK_RET_POSITIVE if (ret <= 0) { p->ret = -1; return; }
+
+#define SNPRINTF_CHECK(ret, max_len)			\
+	if ((ret) < 0 || (size_t)(ret) >= (max_len)) {	\
+		return KNOT_ESPACE;			\
+	}
+
+typedef struct {
+	const knot_dump_style_t *style;
+	const uint8_t *in;
+	size_t        in_max;
+	char          *out;
+	size_t        out_max;
+	size_t        total;
+	int           ret;
+} rrset_dump_params_t;
+
+_public_
+const knot_dump_style_t KNOT_DUMP_STYLE_DEFAULT = {
+	.wrap = false,
+	.show_class = false,
+	.show_ttl = true,
+	.verbose = false,
+	.original_ttl = true,
+	.empty_ttl = false,
+	.human_ttl = false,
+	.human_timestamp = true,
+	.hide_crypto = false,
+	.ascii_to_idn = NULL,
+	.color = NULL,
+	.now = 0,
+};
+
+static void dump_string(rrset_dump_params_t *p, const char *str)
+{
+	CHECK_PRET
+
+	size_t in_len = strlen(str);
+
+	// Check input size (+ 1 termination).
+	if (in_len >= p->out_max) {
+		p->ret = -1;
+		return;
+	}
+
+	// Copy string including termination '\0'!
+	if (memcpy(p->out, str, in_len + 1) == NULL) {
+		p->ret = -1;
+		return;
+	}
+
+	// Fill in output.
+	p->out += in_len;
+	p->out_max -= in_len;
+	p->total += in_len;
+}
+
+static void wire_num8_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint8_t data = *(p->in);
+	size_t  in_len = sizeof(data);
+	size_t  out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	// Write number.
+	int ret = snprintf(p->out, p->out_max, "%u", data);
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_num16_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint16_t data;
+	size_t   in_len = sizeof(data);
+	size_t   out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	// Fill in input data.
+	data = knot_wire_read_u16(p->in);
+
+	// Write number.
+	int ret = snprintf(p->out, p->out_max, "%u", data);
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_num32_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint32_t data;
+	size_t   in_len = sizeof(data);
+	size_t   out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	// Fill in input data.
+	data = knot_wire_read_u32(p->in);
+
+	// Write number.
+	int ret = snprintf(p->out, p->out_max, "%u", data);
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_num48_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint64_t data;
+	size_t   in_len = 6;
+	size_t   out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	// Fill in input data.
+	data = knot_wire_read_u48(p->in);
+
+	// Write number.
+	int ret = snprintf(p->out, p->out_max, "%"PRIu64"", data);
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_ipv4_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	struct in_addr addr4;
+	size_t in_len = sizeof(addr4.s_addr);
+	size_t out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	FILL_IN_INPUT(addr4.s_addr)
+
+	// Write address.
+	if (knot_inet_ntop(AF_INET, &addr4, p->out, p->out_max) == NULL) {
+		p->ret = -1;
+		return;
+	}
+	out_len = strlen(p->out);
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_ipv6_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	struct in6_addr addr6;
+	size_t in_len = sizeof(addr6.s6_addr);
+	size_t out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	FILL_IN_INPUT(addr6.s6_addr)
+
+	// Write address.
+	if (knot_inet_ntop(AF_INET6, &addr6, p->out, p->out_max) == NULL) {
+		p->ret = -1;
+		return;
+	}
+	out_len = strlen(p->out);
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_type_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	char     type[32];
+	uint16_t data;
+	size_t   in_len = sizeof(data);
+	size_t   out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	FILL_IN_INPUT(data)
+
+	// Get record type name string.
+	int ret = knot_rrtype_to_string(ntohs(data), type, sizeof(type));
+	CHECK_RET_POSITIVE
+
+	// Write string.
+	ret = snprintf(p->out, p->out_max, "%s", type);
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static int hex_encode(const uint8_t  *in,
+                      const uint32_t in_len,
+                      uint8_t        *out,
+                      const uint32_t out_len)
+{
+	static const char hex[] = "0123456789ABCDEF";
+
+	if (out_len < 2 * in_len) {
+		return -1;
+	}
+
+	for (uint32_t i = 0; i < in_len; i++) {
+		out[2 * i]     = hex[in[i] / 16];
+		out[2 * i + 1] = hex[in[i] % 16];
+	}
+
+	return 2 * in_len;
+}
+
+static int hex_encode_alloc(const uint8_t  *in,
+                            const uint32_t in_len,
+                            uint8_t        **out)
+{
+	uint32_t out_len = 2 * in_len;
+
+	// Allocating output buffer.
+	*out = malloc(out_len);
+
+	if (*out == NULL) {
+		return -1;
+	}
+
+	// Encoding data.
+	return hex_encode(in, in_len, *out, out_len);
+}
+
+static int num48_encode(const uint8_t  *in,
+                        const uint32_t in_len,
+                        uint8_t        *out,
+                        const uint32_t out_len)
+{
+	if (in_len != 6) {
+		return -1;
+	}
+
+	uint64_t data = knot_wire_read_u48(in);
+
+	int ret = snprintf((char *)out, out_len, "%"PRIu64"", data);
+	if (ret <= 0 || (size_t)ret >= out_len) {
+		return -1;
+	}
+
+	return ret;
+}
+
+typedef int (*encode_t)(const uint8_t *in, const uint32_t in_len,
+                        uint8_t *out, const uint32_t out_len);
+
+typedef int (*encode_alloc_t)(const uint8_t *in, const uint32_t in_len,
+                              uint8_t **out);
+
+static void wire_data_encode_to_str(rrset_dump_params_t *p,
+                                    encode_t enc, encode_alloc_t enc_alloc)
+{
+	CHECK_PRET
+
+	int    ret;
+	size_t in_len = p->in_max;
+
+	// One-line vs multi-line mode.
+	if (p->style->wrap == false) {
+		// Encode data directly to the output.
+		ret = enc(p->in, in_len, (uint8_t *)(p->out), p->out_max);
+		CHECK_RET_POSITIVE
+		size_t out_len = ret;
+
+		p->out += out_len;
+		p->out_max -= out_len;
+		p->total += out_len;
+	} else {
+		int     src_begin;
+		uint8_t *buf;
+
+		// Encode data to the temporary buffer.
+		ret = enc_alloc(p->in, in_len, &buf);
+		CHECK_RET_POSITIVE
+
+		// Loop which wraps base64 block in more lines.
+		for (src_begin = 0; src_begin < ret; src_begin += BLOCK_WIDTH) {
+			if (src_begin > 0) {
+				// Write indent block.
+				dump_string(p, BLOCK_INDENT);
+				if (p->ret < 0) {
+					free(buf);
+					return;
+				}
+			}
+
+			// Compute block length (the last one can be shorter).
+			int src_len = (ret - src_begin) < BLOCK_WIDTH ?
+			              (ret - src_begin) : BLOCK_WIDTH;
+
+			if ((size_t)src_len > p->out_max) {
+				free(buf);
+				p->ret = -1;
+				return;
+			}
+
+			// Write data block.
+			memcpy(p->out, buf + src_begin, src_len);
+
+			p->out += src_len;
+			p->out_max -= src_len;
+			p->total += src_len;
+		}
+
+		// Destroy temporary buffer.
+		free(buf);
+	}
+
+	STRING_TERMINATION
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+}
+
+static void wire_len_data_encode_to_str(rrset_dump_params_t *p,
+                                        encode_t            enc,
+                                        const size_t        len_len,
+                                        const bool          print_len,
+                                        const char          *empty_str)
+{
+	CHECK_PRET
+
+	size_t in_len;
+
+	// First len_len bytes are data length.
+	CHECK_INMAX(len_len)
+
+	// Read data length.
+	switch (len_len) {
+	case 1:
+		in_len = *(p->in);
+		break;
+	case 2:
+		in_len = knot_wire_read_u16(p->in);
+		break;
+	case 4:
+		in_len = knot_wire_read_u32(p->in);
+		break;
+	default:
+		p->ret = -1;
+		return;
+	}
+
+	// If required print data length.
+	if (print_len == true) {
+		switch (len_len) {
+		case 1:
+			wire_num8_to_str(p);
+			break;
+		case 2:
+			wire_num16_to_str(p);
+			break;
+		case 4:
+			wire_num32_to_str(p);
+			break;
+		}
+
+		CHECK_PRET
+
+		// If something follows, print one space character.
+		if (in_len > 0 || *empty_str != '\0') {
+			dump_string(p, " ");
+			CHECK_PRET
+		}
+	} else {
+		p->in += len_len;
+		p->in_max -= len_len;
+	}
+
+	if (in_len > 0) {
+		// Encode data directly to the output.
+		int ret = enc(p->in, in_len, (uint8_t *)(p->out), p->out_max);
+		CHECK_RET_POSITIVE
+		p->out += ret;
+		p->out_max -= ret;
+		p->total += ret;
+
+		STRING_TERMINATION
+
+		// Fill in output.
+		p->in += in_len;
+		p->in_max -= in_len;
+	} else if (*empty_str != '\0') {
+		dump_string(p, empty_str);
+		CHECK_PRET
+	}
+}
+
+static void wire_data_omit(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	const char *omit_message = "[omitted]";
+	const size_t omlen = strlen(omit_message);
+
+	if (p->out_max < omlen) {
+		p->ret = -1;
+		return;
+	}
+
+	memcpy(p->out, omit_message, omlen);
+	p->out += omlen;
+	p->out_max -= omlen;
+	p->total += omlen;
+
+	STRING_TERMINATION
+
+	p->in += p->in_max;
+	p->in_max = 0;
+}
+
+static void wire_dnskey_to_tag(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	int key_pos = -4; // we expect that key flags, 3 and algorithm
+	                  // have been already dumped
+
+	uint16_t key_tag = 0;
+	const dnssec_binary_t rdata_bin = {
+		.data = (uint8_t *)(p->in + key_pos),
+		.size = p->in_max - key_pos
+	};
+	dnssec_keytag(&rdata_bin, &key_tag);
+
+	int ret = snprintf(p->out, p->out_max, "[id = %hu]", key_tag);
+	CHECK_RET_OUTMAX_SNPRINTF
+
+	p->in += p->in_max;
+	p->in_max = 0;
+	p->out += ret;
+	p->out_max -= ret;
+	p->total += ret;
+}
+
+static void wire_unknown_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	int    ret;
+	size_t in_len = p->in_max;
+	size_t out_len = 0;
+
+	// Write unknown length header.
+	if (in_len > 0) {
+		ret = snprintf(p->out, p->out_max, "\\# %zu ", in_len);
+	} else {
+		ret = snprintf(p->out, p->out_max, "\\# 0");
+	}
+	CHECK_RET_OUTMAX_SNPRINTF
+	out_len = ret;
+
+	// Fill in output.
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+
+	// Write hex data if any.
+	if (in_len > 0) {
+		// If wrap mode wrap line.
+		if (p->style->wrap) {
+			dump_string(p, BLOCK_INDENT);
+			CHECK_PRET
+		}
+
+		wire_data_encode_to_str(p, &hex_encode, &hex_encode_alloc);
+		CHECK_PRET
+	}
+}
+
+static void wire_text_to_str(rrset_dump_params_t *p, bool quote,
+                             unsigned with_header_len, bool alpn_mode)
+{
+	CHECK_PRET
+
+	size_t in_len = 0;
+
+	CHECK_INMAX(with_header_len)
+	switch (with_header_len) {
+	case 0:
+		in_len = p->in_max;
+		break;
+	case 1:
+		in_len = *(p->in);
+		break;
+	case 2:
+		in_len = knot_wire_read_u16(p->in);
+		break;
+	default:
+		assert(0);
+	}
+	p->in += with_header_len;
+	p->in_max -= with_header_len;
+	CHECK_INMAX(in_len)
+
+	// Check if quotation can ever be disabled (parser protection fallback).
+	if (!quote) {
+		for (size_t i = 0; i < in_len; i++) {
+			if (p->in[i] == ' ') { // Other WS characters are encoded.
+				quote = true;
+				break;
+			}
+		}
+	}
+
+	// Opening quotation.
+	if (quote) {
+		dump_string(p, "\"");
+		CHECK_PRET
+	}
+
+	// Loop over all characters.
+	for (size_t i = 0; i < in_len; i++) {
+		uint8_t ch = p->in[i];
+
+		if (is_print(ch)) {
+			// For special character print leading slash.
+			if (ch == '\\' || ch == '"') {
+				dump_string(p, "\\");
+				CHECK_PRET
+			}
+			if (alpn_mode && (ch == ',' || ch == '\\')) {
+				dump_string(p, "\\\\");
+				CHECK_PRET
+			}
+
+			// Print text character.
+			if (p->out_max == 0) {
+				p->ret = -1;
+				return;
+			}
+
+			*p->out = ch;
+			p->out++;
+			p->out_max--;
+			p->total++;
+		} else {
+			// Unprintable character encode via \ddd notation.
+			int ret = snprintf(p->out, p->out_max,"\\%03u", ch);
+			CHECK_RET_OUTMAX_SNPRINTF
+
+			p->out += ret;
+			p->out_max -= ret;
+			p->total += ret;
+		}
+	}
+
+	// Closing quotation.
+	if (quote) {
+		dump_string(p, "\"");
+		CHECK_PRET
+	}
+
+	STRING_TERMINATION
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+}
+
+static void wire_timestamp_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint32_t data;
+	size_t   in_len = sizeof(data);
+	size_t   out_len = 0;
+	int      ret;
+
+	CHECK_INMAX(in_len)
+
+	FILL_IN_INPUT(data)
+
+	time_t timestamp = ntohl(data);
+	if (sizeof(time_t) > 4) {
+		timestamp = knot_time_from_u32(timestamp, p->style->now);
+	}
+
+	if (p->style->human_timestamp) {
+		struct tm result;
+		// Write timestamp in YYYYMMDDhhmmss format.
+		ret = strftime(p->out, p->out_max, "%Y%m%d%H%M%S",
+		               gmtime_r(&timestamp, &result));
+		CHECK_RET_POSITIVE
+	} else {
+		// Write timestamp only.
+		ret = snprintf(p->out, p->out_max, "%u", ntohl(data));
+		CHECK_RET_OUTMAX_SNPRINTF
+	}
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static uint32_t wire_time_to_val(rrset_dump_params_t *p)
+{
+	uint32_t data;
+	size_t   in_len = sizeof(data);
+
+	if (p->ret < 0 || p->in_max < in_len ||
+	    memcpy(&data, p->in, in_len) == NULL) {
+		p->ret = -1;
+		return 0;
+	}
+
+	return ntohl(data);
+}
+
+static void wire_ttl_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint32_t data;
+	size_t   in_len = sizeof(data);
+	size_t   out_len = 0;
+	int      ret;
+
+	CHECK_INMAX(in_len)
+
+	FILL_IN_INPUT(data)
+
+	if (p->style->human_ttl) {
+		// Write time in human readable format.
+		ret = knot_time_print_human(ntohl(data), p->out, p->out_max, true);
+		CHECK_RET_POSITIVE
+	} else {
+		// Write timestamp only.
+		ret = snprintf(p->out, p->out_max, "%u", ntohl(data));
+		CHECK_RET_OUTMAX_SNPRINTF
+	}
+	out_len = ret;
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_bitmap_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	int    ret;
+	char   type[32];
+	size_t i = 0;
+	size_t in_len = p->in_max;
+	size_t out_len = 0;
+
+	// Loop over bitmap window array (can be empty).
+	while (i < in_len) {
+		// First byte is window number.
+		uint8_t win = p->in[i++];
+
+		// Check window length (length must follow).
+		if (i >= in_len) {
+			p->ret = -1;
+			return;
+		}
+
+		// Second byte is window length.
+		uint8_t bitmap_len = p->in[i++];
+
+		// Check window length (len bytes must follow).
+		if (i + bitmap_len > in_len) {
+			p->ret = -1;
+			return;
+		}
+
+		// Bitmap processing.
+		for (size_t j = 0; j < (bitmap_len * 8); j++) {
+			if ((p->in[i + j / 8] & (128 >> (j % 8))) != 0) {
+				uint16_t type_num = win * 256 + j;
+
+				ret = knot_rrtype_to_string(type_num, type, sizeof(type));
+				CHECK_RET_POSITIVE
+
+				// Print type name to type list.
+				if (out_len > 0) {
+					ret = snprintf(p->out, p->out_max,
+					               " %s", type);
+				} else {
+					ret = snprintf(p->out, p->out_max,
+					               "%s", type);
+				}
+				CHECK_RET_OUTMAX_SNPRINTF
+				out_len += ret;
+				p->out += ret;
+				p->out_max -= ret;
+			}
+		}
+
+		i += bitmap_len;
+	}
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->total += out_len;
+}
+
+static void wire_dname_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	size_t in_len = knot_dname_size(p->in);
+	size_t out_len = 0;
+
+	CHECK_INMAX(in_len)
+
+	// Write dname string.
+	if (p->style->ascii_to_idn == NULL) {
+		char *dname_str = knot_dname_to_str(p->out, p->in, p->out_max);
+		if (dname_str == NULL) {
+			p->ret = -1;
+			return;
+		}
+		out_len = strlen(dname_str);
+	} else {
+		char *dname_str = knot_dname_to_str_alloc(p->in);
+		p->style->ascii_to_idn(&dname_str);
+
+		int ret = snprintf(p->out, p->out_max, "%s", dname_str);
+		free(dname_str);
+		CHECK_RET_OUTMAX_SNPRINTF
+		out_len = ret;
+	}
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+}
+
+static void wire_apl_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	struct in_addr addr4;
+	struct in6_addr addr6;
+	int    ret;
+	size_t out_len = 0;
+
+	// Input check: family(2B) + prefix(1B) + afdlen(1B).
+	CHECK_INMAX(4)
+
+	// Read fixed size values.
+	uint16_t family   = knot_wire_read_u16(p->in);
+	uint8_t  prefix   = *(p->in + 2);
+	uint8_t  negation = *(p->in + 3) >> 7;
+	uint8_t  afdlen   = *(p->in + 3) & 0x7F;
+	p->in += 4;
+	p->in_max -= 4;
+
+	// Write negation mark.
+	if (negation != 0) {
+		dump_string(p, "!");
+		CHECK_PRET
+	}
+
+	// Write address family with colon.
+	ret = snprintf(p->out, p->out_max, "%u:", family);
+	CHECK_RET_OUTMAX_SNPRINTF
+	p->out += ret;
+	p->out_max -= ret;
+	p->total += ret;
+
+	// Write address.
+	switch (family) {
+	case 1:
+		memset(&addr4, 0, sizeof(addr4));
+
+		if (afdlen > sizeof(addr4.s_addr) || afdlen > p->in_max) {
+			p->ret = -1;
+			return;
+		}
+
+		if (memcpy(&(addr4.s_addr), p->in, afdlen) == NULL) {
+			p->ret = -1;
+			return;
+		}
+
+		// Write address.
+		if (knot_inet_ntop(AF_INET, &addr4, p->out, p->out_max) == NULL) {
+			p->ret = -1;
+			return;
+		}
+		out_len = strlen(p->out);
+
+		break;
+	case 2:
+		memset(&addr6, 0, sizeof(addr6));
+
+		if (afdlen > sizeof(addr6.s6_addr) || afdlen > p->in_max) {
+			p->ret = -1;
+			return;
+		}
+
+		if (memcpy(&(addr6.s6_addr), p->in, afdlen) == NULL) {
+			p->ret = -1;
+			return;
+		}
+
+		// Write address.
+		if (knot_inet_ntop(AF_INET6, &addr6, p->out, p->out_max) == NULL) {
+			p->ret = -1;
+			return;
+		}
+		out_len = strlen(p->out);
+
+		break;
+	default:
+		p->ret = -1;
+		return;
+	}
+	p->in += afdlen;
+	p->in_max -= afdlen;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+
+	// Write prefix length with forward slash.
+	ret = snprintf(p->out, p->out_max, "/%u", prefix);
+	CHECK_RET_OUTMAX_SNPRINTF
+	p->out += ret;
+	p->out_max -= ret;
+	p->total += ret;
+}
+
+static void wire_loc_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	// Read values.
+	wire_ctx_t wire = wire_ctx_init_const(p->in, p->in_max);
+	uint8_t version = wire_ctx_read_u8(&wire);
+
+	// Version check.
+	if (version != 0) {
+		wire_unknown_to_str(p);
+		p->ret = -1;
+		return;
+	}
+
+	// Continue to read values.
+	uint8_t size_w = wire_ctx_read_u8(&wire);
+	uint8_t hpre_w = wire_ctx_read_u8(&wire);
+	uint8_t vpre_w = wire_ctx_read_u8(&wire);
+	uint32_t lat_w = wire_ctx_read_u32(&wire);
+	uint32_t lon_w = wire_ctx_read_u32(&wire);
+	uint32_t alt_w = wire_ctx_read_u32(&wire);
+
+	// Check if all reads are correct.
+	if (wire.error != KNOT_EOK) {
+		p->ret = -1;
+		return;
+	}
+
+	p->in += wire_ctx_offset(&wire);
+	p->in_max = wire_ctx_available(&wire);
+
+	// Latitude calculation.
+	char lat_mark;
+	uint32_t lat;
+	if (lat_w >= LOC_ZERO) {
+		lat_mark = 'N';
+		lat = lat_w - LOC_ZERO;
+	} else {
+		lat_mark = 'S';
+		lat = LOC_ZERO - lat_w;
+	}
+
+	uint32_t d1 = lat / 3600000;
+	uint32_t m1 = (lat - 3600000 * d1) / 60000;
+	double s1 = 0.001 * (lat - 3600000 * d1 - 60000 * m1);
+
+	// Longitude calculation.
+	char lon_mark;
+	uint32_t lon;
+	if (lon_w >= LOC_ZERO) {
+		lon_mark = 'E';
+		lon = lon_w - LOC_ZERO;
+	} else {
+		lon_mark = 'W';
+		lon = LOC_ZERO - lon_w;
+	}
+
+	uint32_t d2 = lon / 3600000;
+	uint32_t m2 = (lon - 3600000 * d2) / 60000;
+	double s2 = 0.001 * (lon - 3600000 * d2 - 60000 * m2);
+
+	// Write latitude and longitude.
+	int ret = snprintf(p->out, p->out_max, "%u %u %.*f %c  %u %u %.*f %c",
+	                   d1, m1, (uint32_t)s1 != s1 ? 3 : 0, s1, lat_mark,
+	                   d2, m2, (uint32_t)s2 != s2 ? 3 : 0, s2, lon_mark);
+	CHECK_RET_OUTMAX_SNPRINTF
+	p->out += ret;
+	p->out_max -= ret;
+	p->total += ret;
+
+	// Altitude calculation.
+	double alt = 0.01 * alt_w - 100000.0;
+
+	// Compute mantissa and exponent for each size.
+	uint8_t size_m = size_w >> 4;
+	uint8_t size_e = size_w & 0xF;
+	uint8_t hpre_m = hpre_w >> 4;
+	uint8_t hpre_e = hpre_w & 0xF;
+	uint8_t vpre_m = vpre_w >> 4;
+	uint8_t vpre_e = vpre_w & 0xF;
+
+	// Sizes check.
+	if (size_m > 9 || size_e > 9 || hpre_m > 9 || hpre_e > 9 ||
+	    vpre_m > 9 || vpre_e > 9) {
+		p->ret = -1;
+		return;
+	}
+
+	// Size and precisions calculation.
+	double size = 0.01 * size_m * pow(10, size_e);
+	double hpre = 0.01 * hpre_m * pow(10, hpre_e);
+	double vpre = 0.01 * vpre_m * pow(10, vpre_e);
+
+	// Write altitude and precisions.
+	ret = snprintf(p->out, p->out_max, "  %.*fm  %.*fm %.*fm %.*fm",
+	               (int32_t)alt != alt ? 2 : 0, alt,
+	               (uint32_t)size != size ? 2 : 0, size,
+	               (uint32_t)hpre != hpre ? 2 : 0, hpre,
+	               (uint32_t)vpre != vpre ? 2 : 0, vpre);
+	CHECK_RET_OUTMAX_SNPRINTF
+	p->out += ret;
+	p->out_max -= ret;
+	p->total += ret;
+}
+
+static void wire_gateway_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	// Input check: type(1B) + algo(1B).
+	CHECK_INMAX(2)
+
+	uint8_t type = *p->in;
+	uint8_t alg = *(p->in + 1);
+
+	// Write gateway type.
+	wire_num8_to_str(p);
+	CHECK_PRET
+
+	// Write space.
+	dump_string(p, " ");
+	CHECK_PRET
+
+	// Write algorithm number.
+	wire_num8_to_str(p);
+	CHECK_PRET
+
+	// Write space.
+	dump_string(p, " ");
+	CHECK_PRET
+
+	// Write appropriate gateway.
+	switch (type) {
+	case 0:
+		dump_string(p, ".");
+		break;
+	case 1:
+		wire_ipv4_to_str(p);
+		break;
+	case 2:
+		wire_ipv6_to_str(p);
+		break;
+	case 3:
+		wire_dname_to_str(p);
+		break;
+	default:
+		p->ret = -1;
+	}
+	CHECK_PRET
+
+	if (alg > 0) {
+		// If wrap mode wrap line.
+		if (p->style->wrap) {
+			dump_string(p, BLOCK_INDENT);
+		} else {
+			dump_string(p, " ");
+		}
+		CHECK_PRET
+
+		// Write ipsec key.
+		wire_data_encode_to_str(p, &knot_base64_encode, &knot_base64_encode_alloc);
+		CHECK_PRET
+	}
+}
+
+static void wire_l64_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	// Check input size (64-bit identifier).
+	if (p->in_max != 8) {
+		p->ret = -1;
+		return;
+	}
+
+	// Write identifier (2-byte) labels separated with a colon.
+	while (p->in_max > 0) {
+		int ret = hex_encode(p->in, 2, (uint8_t *)(p->out), p->out_max);
+		CHECK_RET_POSITIVE
+		p->in += 2;
+		p->in_max -= 2;
+		p->out += ret;
+		p->out_max -= ret;
+		p->total += ret;
+
+		// Write separation character.
+		if (p->in_max > 0) {
+			dump_string(p, ":");
+			CHECK_PRET
+		}
+	}
+}
+
+static void wire_eui_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	CHECK_INMAX(2)
+
+	// Write EUI hexadecimal pairs.
+	while (p->in_max > 0) {
+		int ret = hex_encode(p->in, 1, (uint8_t *)(p->out), p->out_max);
+		CHECK_RET_POSITIVE
+		p->in++;
+		p->in_max--;
+		p->out += ret;
+		p->out_max -= ret;
+		p->total += ret;
+
+		// Write separation character.
+		if (p->in_max > 0) {
+			dump_string(p, "-");
+			CHECK_PRET
+		}
+	}
+}
+
+static void wire_tsig_rcode_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	uint16_t data;
+	size_t   in_len = sizeof(data);
+	const char *rcode_str = "Unknown";
+
+	CHECK_INMAX(in_len)
+
+	// Fill in input data.
+	data = knot_wire_read_u16(p->in);
+
+	// Find RCODE name.
+	const knot_lookup_t *rcode = NULL;
+	rcode = knot_lookup_by_id(knot_tsig_rcode_names, data);
+	if (rcode == NULL) {
+		rcode = knot_lookup_by_id(knot_rcode_names, data);
+	}
+	if (rcode != NULL) {
+		rcode_str = rcode->name;
+	}
+
+	// Dump RCODE name.
+	dump_string(p, rcode_str);
+	CHECK_PRET
+
+	// Fill in output.
+	p->in += in_len;
+	p->in_max -= in_len;
+}
+
+static void wire_svcb_paramkey_to_str(rrset_dump_params_t *p)
+{
+	uint16_t param_key = knot_wire_read_u16(p->in);
+	const knot_lookup_t *type = knot_lookup_by_id(knot_svcb_param_names, param_key);
+
+	if (type != NULL) {
+		dump_string(p, type->name);
+		CHECK_PRET
+		p->in += sizeof(param_key);
+		p->in_max -= sizeof(param_key);
+	} else {
+		dump_string(p, "key");
+		CHECK_PRET
+		wire_num16_to_str(p);
+		CHECK_PRET
+	}
+}
+
+static void wire_value_list_to_str(rrset_dump_params_t *p,
+                                   void (*list_item_dump_fcn)(rrset_dump_params_t *p),
+                                   const uint8_t *expect_end)
+{
+	bool first = true;
+
+	while (expect_end > p->in) {
+		if (first) {
+			first = false;
+		} else {
+			dump_string(p, ",");
+			CHECK_PRET
+		}
+
+		list_item_dump_fcn(p);
+		CHECK_PRET
+	}
+	if (expect_end != p->in) {
+		p->ret = -1;
+	}
+}
+
+static void wire_text_to_str1(rrset_dump_params_t *p)
+{
+	wire_text_to_str(p, false, 1, true);
+}
+
+static void wire_ech_to_base64(rrset_dump_params_t *p, unsigned ech_len)
+{
+	CHECK_INMAX(ech_len)
+
+	int ret = knot_base64_encode(p->in, ech_len, (uint8_t *)(p->out), p->out_max);
+	CHECK_RET_POSITIVE
+	size_t out_len = ret;
+
+	p->in += ech_len;
+	p->in_max -= ech_len;
+	p->out += out_len;
+	p->out_max -= out_len;
+	p->total += out_len;
+
+	STRING_TERMINATION
+}
+
+static void wire_svcparam_to_str(rrset_dump_params_t *p)
+{
+	CHECK_PRET
+
+	CHECK_INMAX(4)
+
+	// Pre-fetch key and length for later use.
+	uint16_t key_type = knot_wire_read_u16(p->in);
+	uint16_t val_len = knot_wire_read_u16(p->in + sizeof(key_type));
+
+	wire_svcb_paramkey_to_str(p);
+
+	p->in += sizeof(val_len);
+	p->in_max -= sizeof(val_len);
+	CHECK_INMAX(val_len)
+
+	if (val_len > 0) {
+		dump_string(p, "=");
+		CHECK_PRET
+
+		switch (key_type) {
+		case KNOT_SVCB_PARAM_MANDATORY:
+			wire_value_list_to_str(p, wire_svcb_paramkey_to_str, p->in + val_len);
+			break;
+		case KNOT_SVCB_PARAM_ALPN:
+			wire_value_list_to_str(p, wire_text_to_str1, p->in + val_len);
+			break;
+		case KNOT_SVCB_PARAM_NDALPN:
+			p->ret = -1; // must not have value
+			break;
+		case KNOT_SVCB_PARAM_PORT:
+			if (val_len != sizeof(uint16_t)) {
+				p->ret = -1;
+			} else {
+				wire_num16_to_str(p);
+			}
+			break;
+		case KNOT_SVCB_PARAM_IPV4HINT:
+			wire_value_list_to_str(p, wire_ipv4_to_str, p->in + val_len);
+			break;
+		case KNOT_SVCB_PARAM_ECH:
+			wire_ech_to_base64(p, val_len);
+			break;
+		case KNOT_SVCB_PARAM_IPV6HINT:
+			wire_value_list_to_str(p, wire_ipv6_to_str, p->in + val_len);
+			break;
+		default:
+			p->in -= sizeof(val_len); // Rollback to where the string length resides.
+			p->in_max += sizeof(val_len);
+			wire_text_to_str(p, true, sizeof(val_len), false);
+		}
+	}
+}
+
+static size_t dnskey_len(const uint8_t *rdata,
+                         const size_t  rdata_len)
+{
+	// Check for empty rdata and empty key.
+	if (rdata_len <= 4) {
+		return 0;
+	}
+
+	const uint8_t *key = rdata + 4;
+	const size_t  len = rdata_len - 4;
+
+	switch (rdata[3]) {
+	case DNSSEC_KEY_ALGORITHM_DSA:
+	case DNSSEC_KEY_ALGORITHM_DSA_NSEC3_SHA1:
+		// RFC 2536, key size ~ bit-length of 'modulus' P.
+		return (64 + 8 * key[0]) * 8;
+	case DNSSEC_KEY_ALGORITHM_RSA_MD5:
+	case DNSSEC_KEY_ALGORITHM_RSA_SHA1:
+	case DNSSEC_KEY_ALGORITHM_RSA_SHA1_NSEC3:
+	case DNSSEC_KEY_ALGORITHM_RSA_SHA256:
+	case DNSSEC_KEY_ALGORITHM_RSA_SHA512:
+		// RFC 3110, key size ~ bit-length of 'modulus'.
+		if (key[0] == 0) {
+			if (len < 3) {
+				return 0;
+			}
+			uint16_t exp;
+			memcpy(&exp, key + 1, sizeof(uint16_t));
+			return (len - 3 - ntohs(exp)) * 8;
+		} else {
+			return (len - 1 - key[0]) * 8;
+		}
+	case DNSSEC_KEY_ALGORITHM_ECC_GOST:
+		// RFC 5933, key size of GOST public keys MUST be 512 bits.
+		return 512;
+	case DNSSEC_KEY_ALGORITHM_ECDSA_P256_SHA256:
+		// RFC 6605.
+		return 256;
+	case DNSSEC_KEY_ALGORITHM_ECDSA_P384_SHA384:
+		// RFC 6605.
+		return 384;
+	case DNSSEC_KEY_ALGORITHM_ED25519:
+		// RFC 8080.
+		return 256;
+	case DNSSEC_KEY_ALGORITHM_ED448:
+		// RFC 8080.
+		return 456;
+	default:
+		return 0;
+	}
+}
+
+static int ber_to_oid(char *dst,
+                      size_t dst_len,
+                      const uint8_t *src,
+                      const size_t src_len)
+{
+	assert(dst);
+	assert(src);
+
+	static const uint8_t longer_mask = (1 << 7);
+
+	size_t len = src[0];
+	if (len == 0 || len >= src_len || dst_len == 0) {
+		return KNOT_EINVAL;
+	}
+
+	uint64_t node = 0UL;
+	for (int i = 1; i <= len; ++i) {
+		uint8_t longer_node = (src[i] & longer_mask);
+		node <<= 7;
+		node += (longer_node ^ src[i]);
+		if (!longer_node) {
+			int ret = snprintf(dst, dst_len, "%"PRIu64".", node);
+			SNPRINTF_CHECK(ret, dst_len);
+			dst += ret;
+			dst_len -= ret;
+			node = 0UL;
+		}
+	}
+	*(dst - 1) = '\0';
+
+	return KNOT_EOK;
+}
+
+static void dnskey_info(const uint8_t *rdata,
+                        const size_t  rdata_len,
+                        char          *out,
+                        const size_t  out_len)
+{
+	if (rdata_len < 5) {
+		return;
+	}
+
+	const uint8_t sep = *(rdata + 1) & 0x01;
+	uint16_t      key_tag = 0;
+	const size_t  key_len = dnskey_len(rdata, rdata_len);
+	const uint8_t alg_id = rdata[3];
+	char          alg_info[512] = "";
+
+	const dnssec_binary_t rdata_bin = { .data = (uint8_t *)rdata,
+	                                    .size = rdata_len };
+	dnssec_keytag(&rdata_bin, &key_tag);
+
+	const knot_lookup_t *alg = knot_lookup_by_id(knot_dnssec_alg_names, alg_id);
+
+	switch (alg_id) {
+	case DNSSEC_KEY_ALGORITHM_DELETE:
+	case DNSSEC_KEY_ALGORITHM_INDIRECT:
+		break;
+	case DNSSEC_KEY_ALGORITHM_PRIVATEOID:
+		; char oid_str[sizeof(alg_info) - 3];
+		if (ber_to_oid(oid_str, sizeof(oid_str), rdata + 4, rdata_len - 4) != KNOT_EOK ||
+		    snprintf(alg_info, sizeof(alg_info), " (%s)", oid_str) <= 0) {
+			alg_info[0] = '\0';
+		}
+		break;
+	case DNSSEC_KEY_ALGORITHM_PRIVATEDNS:
+		; knot_dname_txt_storage_t alg_str;
+		if (knot_dname_wire_check(rdata + 4, rdata + rdata_len, NULL) <= 0 ||
+		    knot_dname_to_str(alg_str, rdata + 4, sizeof(alg_str)) == NULL ||
+		    snprintf(alg_info, sizeof(alg_info), " (%s)", alg_str) <= 0) {
+			alg_info[0] = '\0';
+		}
+		break;
+	default:
+		if (snprintf(alg_info, sizeof(alg_info), " (%zub)", key_len) <= 0) {
+			alg_info[0] = '\0';
+		}
+		break;
+	}
+
+	int ret = snprintf(out, out_len, "%s, %s%s, id = %u",
+	                   sep ? "KSK" : "ZSK",
+	                   alg ? alg->name : "UNKNOWN",
+	                   alg_info,
+	                   key_tag);
+	if (ret <= 0) {	// Truncated return is acceptable. Just check for errors.
+		out[0] = '\0';
+	}
+}
+
+#define DUMP_PARAMS	rrset_dump_params_t *const p
+#define	DUMP_END	return (p->in_max == 0 ? (int)p->total : KNOT_EPARSEFAIL);
+
+#define CHECK_RET(p)	if (p->ret < 0) return p->ret;
+
+#define WRAP_INIT	dump_string(p, "(" BLOCK_INDENT); CHECK_RET(p);
+#define WRAP_END	dump_string(p, BLOCK_INDENT ")"); CHECK_RET(p);
+#define WRAP_LINE	dump_string(p, BLOCK_INDENT); CHECK_RET(p);
+
+#define COMMENT(s)	if (p->style->verbose) { \
+			    dump_string(p, " ; "); CHECK_RET(p); \
+			    dump_string(p, s); CHECK_RET(p); \
+			}
+
+#define STORE_TIME	if (p->style->verbose) { \
+				time = wire_time_to_val(p); CHECK_RET(p); \
+			}
+#define COMMENT_TIME(s)	if (p->style->verbose) { \
+			    char buf[80]; \
+			    dump_string(p, " ; "); CHECK_RET(p); \
+			    dump_string(p, s); CHECK_RET(p); \
+			    if (knot_time_print_human(time, buf, sizeof(buf), false) > 0) { \
+			        dump_string(p, " ("); CHECK_RET(p); \
+			        dump_string(p, buf); CHECK_RET(p); \
+			        dump_string(p, ")"); CHECK_RET(p); \
+			    } \
+			}
+
+#define DUMP_SPACE	dump_string(p, " "); CHECK_RET(p);
+#define DUMP_NUM8	wire_num8_to_str(p); CHECK_RET(p);
+#define DUMP_NUM16	wire_num16_to_str(p); CHECK_RET(p);
+#define DUMP_NUM32	wire_num32_to_str(p); CHECK_RET(p);
+#define DUMP_NUM48	wire_num48_to_str(p); CHECK_RET(p);
+#define DUMP_DNAME	wire_dname_to_str(p); CHECK_RET(p);
+#define DUMP_TIME	wire_ttl_to_str(p); CHECK_RET(p);
+#define DUMP_TIMESTAMP	wire_timestamp_to_str(p); CHECK_RET(p);
+#define DUMP_IPV4	wire_ipv4_to_str(p); CHECK_RET(p);
+#define DUMP_IPV6	wire_ipv6_to_str(p); CHECK_RET(p);
+#define DUMP_TYPE	wire_type_to_str(p); CHECK_RET(p);
+#define DUMP_HEX	wire_data_encode_to_str(p, &hex_encode, \
+				&hex_encode_alloc); CHECK_RET(p);
+#define DUMP_BASE64	wire_data_encode_to_str(p, &knot_base64_encode, \
+				&knot_base64_encode_alloc); CHECK_RET(p);
+#define DUMP_HASH	wire_len_data_encode_to_str(p, &knot_base32hex_encode, \
+				1, false, ""); CHECK_RET(p);
+#define DUMP_SALT	wire_len_data_encode_to_str(p, &hex_encode, \
+				1, false, "-"); CHECK_RET(p);
+#define DUMP_TSIG_DGST	wire_len_data_encode_to_str(p, &knot_base64_encode, \
+				2, true, ""); CHECK_RET(p);
+#define DUMP_TSIG_DATA	wire_len_data_encode_to_str(p, &num48_encode, \
+				2, true, ""); CHECK_RET(p);
+#define DUMP_OMIT	wire_data_omit(p); CHECK_RET(p);
+#define DUMP_KEY_OMIT	wire_dnskey_to_tag(p); CHECK_RET(p);
+#define DUMP_TEXT	wire_text_to_str(p, true,  1, false); CHECK_RET(p);
+#define DUMP_LONG_TEXT	wire_text_to_str(p, true,  0, false); CHECK_RET(p);
+#define DUMP_UNQUOTED	wire_text_to_str(p, false, 1, false); CHECK_RET(p);
+#define DUMP_BITMAP	wire_bitmap_to_str(p); CHECK_RET(p);
+#define DUMP_APL	wire_apl_to_str(p); CHECK_RET(p);
+#define DUMP_LOC	wire_loc_to_str(p); CHECK_RET(p);
+#define DUMP_GATEWAY	wire_gateway_to_str(p); CHECK_RET(p);
+#define DUMP_L64	wire_l64_to_str(p); CHECK_RET(p);
+#define DUMP_EUI	wire_eui_to_str(p); CHECK_RET(p);
+#define DUMP_TSIG_RCODE	wire_tsig_rcode_to_str(p); CHECK_RET(p);
+#define DUMP_SVCPARAM	wire_svcparam_to_str(p); CHECK_RET(p);
+#define DUMP_UNKNOWN	wire_unknown_to_str(p); CHECK_RET(p);
+
+static int dump_a(DUMP_PARAMS)
+{
+	DUMP_IPV4;
+
+	DUMP_END;
+}
+
+static int dump_ns(DUMP_PARAMS)
+{
+	DUMP_DNAME;
+
+	DUMP_END;
+}
+
+static int dump_soa(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		uint32_t time = 0;
+		DUMP_DNAME; DUMP_SPACE;
+		DUMP_DNAME; DUMP_SPACE; WRAP_INIT;
+		DUMP_NUM32; COMMENT("serial"); WRAP_LINE;
+		STORE_TIME; DUMP_TIME; COMMENT_TIME("refresh"); WRAP_LINE;
+		STORE_TIME; DUMP_TIME; COMMENT_TIME("retry"); WRAP_LINE;
+		STORE_TIME; DUMP_TIME; COMMENT_TIME("expire"); WRAP_LINE;
+		STORE_TIME; DUMP_TIME; COMMENT_TIME("minimum"); WRAP_END;
+	} else {
+		DUMP_DNAME; DUMP_SPACE;
+		DUMP_DNAME; DUMP_SPACE;
+		DUMP_NUM32; DUMP_SPACE;
+		DUMP_TIME;  DUMP_SPACE;
+		DUMP_TIME;  DUMP_SPACE;
+		DUMP_TIME;  DUMP_SPACE;
+		DUMP_TIME;
+	}
+
+	DUMP_END;
+}
+
+static int dump_hinfo(DUMP_PARAMS)
+{
+	DUMP_TEXT; DUMP_SPACE;
+	DUMP_TEXT;
+
+	DUMP_END;
+}
+
+static int dump_minfo(DUMP_PARAMS)
+{
+	DUMP_DNAME; DUMP_SPACE;
+	DUMP_DNAME;
+
+	DUMP_END;
+}
+
+static int dump_mx(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_DNAME;
+
+	DUMP_END;
+}
+
+static int dump_txt(DUMP_PARAMS)
+{
+	// First text string.
+	DUMP_TEXT;
+
+	// Other text strings if any.
+	while (p->in_max > 0) {
+		DUMP_SPACE; DUMP_TEXT;
+	}
+
+	DUMP_END;
+}
+
+static int dump_dnskey(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		char info[512] = "";
+		dnskey_info(p->in, p->in_max, info, sizeof(info));
+
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		if (p->style->hide_crypto) {
+			DUMP_OMIT;
+			WRAP_LINE;
+		} else {
+			WRAP_INIT;
+			DUMP_BASE64;
+			WRAP_END;
+		}
+		COMMENT(info);
+	} else {
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		if (p->style->hide_crypto) {
+			DUMP_KEY_OMIT;
+		} else {
+			DUMP_BASE64;
+		}
+	}
+
+	DUMP_END;
+}
+
+static int dump_aaaa(DUMP_PARAMS)
+{
+	DUMP_IPV6;
+
+	DUMP_END;
+}
+
+static int dump_loc(DUMP_PARAMS)
+{
+	DUMP_LOC;
+
+	DUMP_END;
+}
+
+static int dump_srv(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_DNAME;
+
+	DUMP_END;
+}
+
+static int dump_naptr(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_TEXT;  DUMP_SPACE;
+	DUMP_TEXT;  DUMP_SPACE;
+	DUMP_TEXT;  DUMP_SPACE;
+	DUMP_DNAME;
+
+	DUMP_END;
+}
+
+static int dump_cert(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM16;  DUMP_SPACE;
+		DUMP_NUM16;  DUMP_SPACE;
+		DUMP_NUM8;   DUMP_SPACE; WRAP_INIT;
+		DUMP_BASE64;
+		WRAP_END;
+	} else {
+		DUMP_NUM16;  DUMP_SPACE;
+		DUMP_NUM16;  DUMP_SPACE;
+		DUMP_NUM8;   DUMP_SPACE;
+		DUMP_BASE64;
+	}
+
+	DUMP_END;
+}
+
+static int dump_apl(DUMP_PARAMS)
+{
+	// Print list of APLs (empty list is allowed).
+	while (p->in_max > 0) {
+		if (p->total > 0) {
+			DUMP_SPACE;
+		}
+		DUMP_APL;
+	}
+
+	DUMP_END;
+}
+
+static int dump_ds(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE; WRAP_INIT;
+		DUMP_HEX;
+		WRAP_END;
+	} else {
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_HEX;
+	}
+
+	DUMP_END;
+}
+
+static int dump_sshfp(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE; WRAP_INIT;
+		DUMP_HEX;
+		WRAP_END;
+	} else {
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_HEX;
+	}
+
+	DUMP_END;
+}
+
+static int dump_ipseckey(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM8; DUMP_SPACE; WRAP_INIT;
+		DUMP_GATEWAY;
+		WRAP_END;
+	} else {
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_GATEWAY;
+	}
+
+	DUMP_END;
+}
+
+static int dump_rrsig(DUMP_PARAMS)
+{
+	DUMP_TYPE;   DUMP_SPACE;
+	DUMP_NUM8;   DUMP_SPACE;
+	DUMP_NUM8;   DUMP_SPACE;
+	DUMP_NUM32;  DUMP_SPACE;
+	DUMP_TIMESTAMP; DUMP_SPACE;
+	if (p->style->wrap) {
+		WRAP_INIT;
+	}
+	DUMP_TIMESTAMP; DUMP_SPACE;
+	DUMP_NUM16;  DUMP_SPACE;
+	DUMP_DNAME;
+	if (p->style->wrap) {
+		WRAP_LINE;
+	} else {
+		DUMP_SPACE;
+	}
+	if (p->style->hide_crypto) {
+		DUMP_OMIT;
+	} else {
+		DUMP_BASE64;
+	}
+	if (p->style->wrap) {
+		WRAP_END;
+	}
+	DUMP_END;
+}
+
+static int dump_nsec(DUMP_PARAMS)
+{
+	DUMP_DNAME; DUMP_SPACE;
+	DUMP_BITMAP;
+
+	DUMP_END;
+}
+
+static int dump_dhcid(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		WRAP_INIT;
+		DUMP_BASE64;
+		WRAP_END;
+	} else {
+		DUMP_BASE64;
+	}
+
+	DUMP_END;
+}
+
+static int dump_nsec3(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM8;   DUMP_SPACE;
+		DUMP_NUM8;   DUMP_SPACE;
+		DUMP_NUM16;  DUMP_SPACE;
+		DUMP_SALT;   DUMP_SPACE; WRAP_INIT;
+		DUMP_HASH;   WRAP_LINE;
+		DUMP_BITMAP;
+		WRAP_END;
+	} else {
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_SALT;  DUMP_SPACE;
+		DUMP_HASH;  DUMP_SPACE;
+		DUMP_BITMAP;
+	}
+
+	DUMP_END;
+}
+
+static int dump_nsec3param(DUMP_PARAMS)
+{
+	DUMP_NUM8;  DUMP_SPACE;
+	DUMP_NUM8;  DUMP_SPACE;
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_SALT;
+
+	DUMP_END;
+}
+
+static int dump_tlsa(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE; WRAP_INIT;
+		DUMP_HEX;
+		WRAP_END;
+	} else {
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_NUM8; DUMP_SPACE;
+		DUMP_HEX;
+	}
+
+	DUMP_END;
+}
+
+static int dump_csync(DUMP_PARAMS)
+{
+	DUMP_NUM32; DUMP_SPACE;
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_BITMAP;
+
+	DUMP_END;
+}
+
+static int dump_zonemd(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_NUM32; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE; WRAP_INIT;
+		DUMP_HEX;
+		WRAP_END;
+	} else {
+		DUMP_NUM32; DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_NUM8;  DUMP_SPACE;
+		DUMP_HEX;
+	}
+
+	DUMP_END;
+}
+
+static int dump_l64(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_L64;
+
+	DUMP_END;
+}
+
+static int dump_l32(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_IPV4;
+
+	DUMP_END;
+}
+
+static int dump_eui(DUMP_PARAMS)
+{
+	DUMP_EUI;
+
+	DUMP_END;
+}
+
+static int dump_tsig(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		DUMP_DNAME; DUMP_SPACE;
+		DUMP_NUM48; DUMP_SPACE;
+		DUMP_NUM16; DUMP_SPACE; WRAP_INIT;
+		DUMP_TSIG_DGST; WRAP_LINE;
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_TSIG_RCODE; DUMP_SPACE;
+		DUMP_TSIG_DATA;
+		WRAP_END;
+	} else {
+		DUMP_DNAME; DUMP_SPACE;
+		DUMP_NUM48; DUMP_SPACE;
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_TSIG_DGST; DUMP_SPACE;
+		DUMP_NUM16; DUMP_SPACE;
+		DUMP_TSIG_RCODE; DUMP_SPACE;
+		DUMP_TSIG_DATA;
+	}
+
+	DUMP_END;
+}
+
+static int dump_uri(DUMP_PARAMS)
+{
+	DUMP_NUM16;     DUMP_SPACE;
+	DUMP_NUM16;     DUMP_SPACE;
+	DUMP_LONG_TEXT; DUMP_SPACE;
+
+	DUMP_END;
+}
+
+static int dump_caa(DUMP_PARAMS)
+{
+	DUMP_NUM8;      DUMP_SPACE;
+	DUMP_UNQUOTED;  DUMP_SPACE;
+	DUMP_LONG_TEXT; DUMP_SPACE;
+
+	DUMP_END;
+}
+
+static int dump_svcb(DUMP_PARAMS)
+{
+	DUMP_NUM16; DUMP_SPACE;
+	DUMP_DNAME;
+	if (p->style->wrap) {
+		if (p->in_max > 0) {
+			DUMP_SPACE;
+			WRAP_INIT;
+			DUMP_SVCPARAM;
+			while (p->in_max > 0) {
+				WRAP_LINE; DUMP_SVCPARAM;
+			}
+			WRAP_END;
+		}
+	} else {
+		while (p->in_max > 0) {
+			DUMP_SPACE;
+			DUMP_SVCPARAM;
+		}
+	}
+
+	DUMP_END;
+}
+
+static int dump_unknown(DUMP_PARAMS)
+{
+	if (p->style->wrap) {
+		WRAP_INIT;
+		DUMP_UNKNOWN;
+		WRAP_END;
+	} else {
+		DUMP_UNKNOWN;
+	}
+
+	DUMP_END;
+}
+
+static int txt_dump_data(rrset_dump_params_t *p, uint16_t type)
+{
+	switch (type) {
+		case KNOT_RRTYPE_A:
+			return dump_a(p);
+		case KNOT_RRTYPE_NS:
+		case KNOT_RRTYPE_CNAME:
+		case KNOT_RRTYPE_PTR:
+		case KNOT_RRTYPE_DNAME:
+			return dump_ns(p);
+		case KNOT_RRTYPE_SOA:
+			return dump_soa(p);
+		case KNOT_RRTYPE_HINFO:
+			return dump_hinfo(p);
+		case KNOT_RRTYPE_MINFO:
+		case KNOT_RRTYPE_RP:
+			return dump_minfo(p);
+		case KNOT_RRTYPE_MX:
+		case KNOT_RRTYPE_AFSDB:
+		case KNOT_RRTYPE_RT:
+		case KNOT_RRTYPE_KX:
+		case KNOT_RRTYPE_LP:
+			return dump_mx(p);
+		case KNOT_RRTYPE_TXT:
+		case KNOT_RRTYPE_SPF:
+			return dump_txt(p);
+		case KNOT_RRTYPE_KEY:
+		case KNOT_RRTYPE_DNSKEY:
+		case KNOT_RRTYPE_CDNSKEY:
+			return dump_dnskey(p);
+		case KNOT_RRTYPE_AAAA:
+			return dump_aaaa(p);
+		case KNOT_RRTYPE_LOC:
+			return dump_loc(p);
+		case KNOT_RRTYPE_SRV:
+			return dump_srv(p);
+		case KNOT_RRTYPE_NAPTR:
+			return dump_naptr(p);
+		case KNOT_RRTYPE_CERT:
+			return dump_cert(p);
+		case KNOT_RRTYPE_APL:
+			return dump_apl(p);
+		case KNOT_RRTYPE_DS:
+		case KNOT_RRTYPE_CDS:
+			return dump_ds(p);
+		case KNOT_RRTYPE_SSHFP:
+			return dump_sshfp(p);
+		case KNOT_RRTYPE_IPSECKEY:
+			return dump_ipseckey(p);
+		case KNOT_RRTYPE_RRSIG:
+			return dump_rrsig(p);
+		case KNOT_RRTYPE_NSEC:
+			return dump_nsec(p);
+		case KNOT_RRTYPE_DHCID:
+		case KNOT_RRTYPE_OPENPGPKEY:
+			return dump_dhcid(p);
+		case KNOT_RRTYPE_NSEC3:
+			return dump_nsec3(p);
+		case KNOT_RRTYPE_NSEC3PARAM:
+			return dump_nsec3param(p);
+		case KNOT_RRTYPE_TLSA:
+		case KNOT_RRTYPE_SMIMEA:
+			return dump_tlsa(p);
+		case KNOT_RRTYPE_CSYNC:
+			return dump_csync(p);
+		case KNOT_RRTYPE_ZONEMD:
+			return dump_zonemd(p);
+		case KNOT_RRTYPE_NID:
+		case KNOT_RRTYPE_L64:
+			return dump_l64(p);
+		case KNOT_RRTYPE_L32:
+			return dump_l32(p);
+		case KNOT_RRTYPE_EUI48:
+		case KNOT_RRTYPE_EUI64:
+			return dump_eui(p);
+		case KNOT_RRTYPE_TSIG:
+			return dump_tsig(p);
+		case KNOT_RRTYPE_URI:
+			return dump_uri(p);
+		case KNOT_RRTYPE_CAA:
+			return dump_caa(p);
+		case KNOT_RRTYPE_SVCB:
+		case KNOT_RRTYPE_HTTPS:
+			return dump_svcb(p);
+		default:
+			return dump_unknown(p);
+	}
+}
+
+_public_
+int knot_rrset_txt_dump_data(const knot_rrset_t      *rrset,
+                             const size_t            pos,
+                             char                    *dst,
+                             const size_t            maxlen,
+                             const knot_dump_style_t *style)
+{
+	if (rrset == NULL || dst == NULL || style == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdata_t *rr_data = knot_rdataset_at(&rrset->rrs, pos);
+	if (rr_data == NULL) {
+		return KNOT_EINVAL; /* bad pos or rrset->rrs */
+	}
+
+	uint8_t *data = rr_data->data;
+	uint16_t data_len = rr_data->len;
+
+	rrset_dump_params_t p = {
+		.style = style,
+		.in = data,
+		.in_max = data_len,
+		.out = dst,
+		.out_max = maxlen,
+		.total = 0,
+		.ret = 0
+	};
+
+	int ret;
+
+	// Allow empty rdata with the CH class (knsupdate).
+	if (data_len == 0 && rrset->rclass != KNOT_CLASS_IN) {
+		ret = 0;
+	} else if (style->generic) {
+		ret = dump_unknown(&p);
+	} else {
+		ret = txt_dump_data(&p, rrset->type);
+	}
+
+	// Terminate the string just in case.
+	if (ret < 0 || ret >= maxlen) {
+		return KNOT_ESPACE;
+	}
+	dst[ret] = '\0';
+
+	return ret;
+}
+
+_public_
+int knot_rrset_txt_dump_header(const knot_rrset_t      *rrset,
+                               const uint32_t          ttl,
+                               char                    *dst,
+                               const size_t            maxlen,
+                               const knot_dump_style_t *style)
+{
+	if (rrset == NULL || dst == NULL || style == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t len = 0;
+	char   buf[32];
+	int    ret;
+
+	// Dump rrset owner.
+	char *name = knot_dname_to_str_alloc(rrset->owner);
+	if (style->ascii_to_idn != NULL) {
+		style->ascii_to_idn(&name);
+	}
+	char sep = strlen(name) < 4 * TAB_WIDTH ? '\t' : ' ';
+	ret = snprintf(dst + len, maxlen - len, "%-20s%c", name, sep);
+	free(name);
+	SNPRINTF_CHECK(ret, maxlen - len);
+	len += ret;
+
+	// Set white space separation character.
+	sep = style->wrap ? ' ' : '\t';
+
+	// Dump rrset ttl.
+	if (style->show_ttl) {
+		if (style->empty_ttl) {
+			ret = snprintf(dst + len, maxlen - len, "%c", sep);
+		} else if (style->human_ttl) {
+			// Create human readable ttl string.
+			if (knot_time_print_human(ttl, buf, sizeof(buf), true) < 0) {
+				return KNOT_ESPACE;
+			}
+			ret = snprintf(dst + len, maxlen - len, "%s%c",
+			               buf, sep);
+		} else {
+			ret = snprintf(dst + len, maxlen - len, "%u%c", ttl, sep);
+		}
+		SNPRINTF_CHECK(ret, maxlen - len);
+		len += ret;
+	}
+
+	// Dump rrset class.
+	if (style->show_class) {
+		if (knot_rrclass_to_string(rrset->rclass, buf, sizeof(buf)) < 0) {
+			return KNOT_ESPACE;
+		}
+		ret = snprintf(dst + len, maxlen - len, "%-2s%c", buf, sep);
+		SNPRINTF_CHECK(ret, maxlen - len);
+		len += ret;
+	}
+
+	// Dump rrset type.
+	if (style->generic) {
+		if (snprintf(buf, sizeof(buf), "TYPE%u", rrset->type) < 0) {
+			return KNOT_ESPACE;
+		}
+	} else if (knot_rrtype_to_string(rrset->type, buf, sizeof(buf)) < 0) {
+		return KNOT_ESPACE;
+	}
+	if (rrset->rrs.count > 0) {
+		ret = snprintf(dst + len, maxlen - len, "%s%c", buf, sep);
+	} else {
+		ret = snprintf(dst + len, maxlen - len, "%s", buf);
+	}
+	SNPRINTF_CHECK(ret, maxlen - len);
+	len += ret;
+
+	return len;
+}
+
+static int rrset_txt_dump(const knot_rrset_t      *rrset,
+                          char                    *dst,
+                          const size_t            maxlen,
+                          const knot_dump_style_t *style)
+{
+	if (rrset == NULL || dst == NULL || style == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t len = 0;
+	size_t color_len = (style->color != NULL ? strlen(style->color) : 0);
+	size_t reset_len = (color_len > 0 ? strlen(COL_RST(true)) : 0);
+
+	dst[0] = '\0';
+
+	// Loop over rdata in rrset.
+	uint16_t rr_count = rrset->rrs.count;
+	knot_rdata_t *rr = rrset->rrs.rdata;
+	for (uint16_t i = 0; i < rr_count; i++) {
+		// Put color prefix before every record.
+		if (color_len > 0) {
+			if (len >= maxlen - color_len) {
+				return KNOT_ESPACE;
+			}
+			memcpy(dst + len, style->color, color_len);
+			len += color_len;
+		}
+
+		// Dump rdata owner, class, ttl and type.
+		uint32_t ttl = ((style->original_ttl && rrset->type == KNOT_RRTYPE_RRSIG) ?
+		                knot_rrsig_original_ttl(rr) : rrset->ttl);
+
+		int ret = knot_rrset_txt_dump_header(rrset, ttl, dst + len,
+		                                     maxlen - len, style);
+		if (ret < 0) {
+			return KNOT_ESPACE;
+		}
+		len += ret;
+
+		// Dump rdata as such.
+		ret = knot_rrset_txt_dump_data(rrset, i, dst + len,
+		                               maxlen - len, style);
+		if (ret < 0) {
+			return KNOT_ESPACE;
+		}
+		len += ret;
+
+		// Reset the color.
+		if (reset_len > 0) {
+			if (len >= maxlen - reset_len) {
+				return KNOT_ESPACE;
+			}
+			memcpy(dst + len, COL_RST(true), reset_len);
+			len += reset_len;
+		}
+
+		// Terminate line.
+		if (len >= maxlen - 1) {
+			return KNOT_ESPACE;
+		}
+		dst[len++] = '\n';
+		dst[len] = '\0';
+
+		rr = knot_rdataset_next(rr);
+	}
+
+	return len;
+}
+
+_public_
+int knot_rrset_txt_dump(const knot_rrset_t      *rrset,
+                        char                    **dst,
+                        size_t                  *dst_size,
+                        const knot_dump_style_t *style)
+{
+	if (dst == NULL || dst_size == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	while (1) {
+		int ret = rrset_txt_dump(rrset, *dst, *dst_size, style);
+		if (ret != KNOT_ESPACE) {
+			return ret;
+		}
+
+		size_t new_dst_size = 2 * (*dst_size);
+		if (new_dst_size > RRSET_DUMP_LIMIT) {
+			return KNOT_ESPACE;
+		}
+
+		char * new_dst = malloc(new_dst_size);
+		if (new_dst == NULL) {
+			return KNOT_ENOMEM;
+		}
+
+		free(*dst);
+		*dst = new_dst;
+		*dst_size = new_dst_size;
+	}
+}
diff --git a/src/libknot/rrset-dump.h b/src/libknot/rrset-dump.h
new file mode 100644
index 0000000..4631531
--- /dev/null
+++ b/src/libknot/rrset-dump.h
@@ -0,0 +1,118 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief RRset text dump facility.
+ *
+ * \addtogroup rr
+ * @{
+ */
+
+#pragma once
+
+#include <stdbool.h>
+
+#include "libknot/rrset.h"
+
+/*! \brief Text output settings. */
+typedef struct {
+	/*!< Wrap long records. */
+	bool	wrap;
+	/*!< Show class. */
+	bool	show_class;
+	/*!< Show TTL. */
+	bool	show_ttl;
+	/*!< Print extra information. */
+	bool	verbose;
+	/*!< Print RRSIG original TTL instead of rrset TTL. */
+	bool	original_ttl;
+	/*!< Show empty TTL value (keep indentation). */
+	bool	empty_ttl;
+	/*!< Format TTL as DHMS. */
+	bool	human_ttl;
+	/*!< Format timestamp as YYYYMMDDHHmmSS. */
+	bool	human_timestamp;
+	/*!< Force generic data representation. */
+	bool	generic;
+	/*!< Hide binary parts of RRSIGs and DNSKEYs. */
+	bool	hide_crypto;
+	/*!< ASCII string to IDN string transformation callback. */
+	void (*ascii_to_idn)(char **name);
+	/*!< Optional color control sequence which is put before every output line.
+	 *   Not compatible with wrap. */
+	const char *color;
+	/*!< Time context for correct > 32 bit timestamp conversion. */
+	uint64_t now;
+} knot_dump_style_t;
+
+/*! \brief Default dump style. */
+extern const knot_dump_style_t KNOT_DUMP_STYLE_DEFAULT;
+
+/*!
+ * \brief Dumps rrset header.
+ *
+ * \param rrset		RRset to dump.
+ * \param ttl		TTL to dump.
+ * \param dst		Output buffer.
+ * \param maxlen	Output buffer size.
+ * \param style		Output style.
+ *
+ * \retval output length	if success.
+ * \retval < 0			if error.
+ */
+int knot_rrset_txt_dump_header(const knot_rrset_t      *rrset,
+                               const uint32_t          ttl,
+                               char                    *dst,
+                               const size_t            maxlen,
+                               const knot_dump_style_t *style);
+
+/*!
+ * \brief Dumps rrset data.
+ *
+ * \param rrset		RRset to dump.
+ * \param pos		Position of the record to dump.
+ * \param dst		Output buffer.
+ * \param maxlen	Output buffer size.
+ * \param style		Output style.
+ *
+ * \retval output length	if success.
+ * \retval < 0			if error.
+ */
+int knot_rrset_txt_dump_data(const knot_rrset_t      *rrset,
+                             const size_t            pos,
+                             char                    *dst,
+                             const size_t            maxlen,
+                             const knot_dump_style_t *style);
+
+/*!
+ * \brief Dumps rrset, re-allocates dst to double (4x, 8x, ...) if too small.
+ *
+ * \param rrset		RRset to dump.
+ * \param dst		Output buffer.
+ * \param dst_size	Output buffer size (changed if *dst re-allocated).
+ * \param style		Output style.
+ *
+ * \retval output length	if success.
+ * \retval < 0			if error.
+ */
+int knot_rrset_txt_dump(const knot_rrset_t      *rrset,
+                        char                    **dst,
+                        size_t                  *dst_size,
+                        const knot_dump_style_t *style);
+
+/*! @} */
diff --git a/src/libknot/rrset.c b/src/libknot/rrset.c
new file mode 100644
index 0000000..110422f
--- /dev/null
+++ b/src/libknot/rrset.c
@@ -0,0 +1,217 @@
+/*  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 <stdbool.h>
+#include <stdint.h>
+
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/rrset.h"
+#include "libknot/rrtype/naptr.h"
+#include "libknot/rrtype/rrsig.h"
+#include "contrib/mempattern.h"
+
+_public_
+knot_rrset_t *knot_rrset_new(const knot_dname_t *owner, uint16_t type,
+                             uint16_t rclass, uint32_t ttl, knot_mm_t *mm)
+{
+	knot_dname_t *owner_cpy = knot_dname_copy(owner, mm);
+	if (owner_cpy == NULL) {
+		return NULL;
+	}
+
+	knot_rrset_t *ret = mm_alloc(mm, sizeof(knot_rrset_t));
+	if (ret == NULL) {
+		knot_dname_free(owner_cpy, mm);
+		return NULL;
+	}
+
+	knot_rrset_init(ret, owner_cpy, type, rclass, ttl);
+
+	return ret;
+}
+
+_public_
+knot_rrset_t *knot_rrset_copy(const knot_rrset_t *src, knot_mm_t *mm)
+{
+	if (src == NULL) {
+		return NULL;
+	}
+
+	knot_rrset_t *rrset = knot_rrset_new(src->owner, src->type,
+	                                     src->rclass, src->ttl, mm);
+	if (rrset == NULL) {
+		return NULL;
+	}
+
+	int ret = knot_rdataset_copy(&rrset->rrs, &src->rrs, mm);
+	if (ret != KNOT_EOK) {
+		knot_rrset_free(rrset, mm);
+		return NULL;
+	}
+
+	return rrset;
+}
+
+_public_
+void knot_rrset_free(knot_rrset_t *rrset, knot_mm_t *mm)
+{
+	if (rrset == NULL) {
+		return;
+	}
+
+	knot_rrset_clear(rrset, mm);
+	mm_free(mm, rrset);
+}
+
+_public_
+void knot_rrset_clear(knot_rrset_t *rrset, knot_mm_t *mm)
+{
+	if (rrset == NULL) {
+		return;
+	}
+
+	knot_rdataset_clear(&rrset->rrs, mm);
+	knot_dname_free(rrset->owner, mm);
+	rrset->owner = NULL;
+}
+
+_public_
+int knot_rrset_add_rdata(knot_rrset_t *rrset, const uint8_t *data, uint16_t len,
+                         knot_mm_t *mm)
+{
+	if (rrset == NULL || (data == NULL && len > 0)) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t buf[knot_rdata_size(len)];
+	knot_rdata_t *rdata = (knot_rdata_t *)buf;
+	knot_rdata_init(rdata, len, data);
+
+	return knot_rdataset_add(&rrset->rrs, rdata, mm);
+}
+
+_public_
+bool knot_rrset_equal(const knot_rrset_t *r1,
+                      const knot_rrset_t *r2,
+                      bool incl_ttl)
+{
+	if (r1->type != r2->type ||
+	    (incl_ttl && r1->ttl != r2->ttl)) {
+		return false;
+	}
+
+	if ((r1->owner != NULL || r2->owner != NULL) &&
+	    !knot_dname_is_equal(r1->owner, r2->owner)) {
+		return false;
+	}
+
+	return knot_rdataset_eq(&r1->rrs, &r2->rrs);
+}
+
+_public_
+bool knot_rrset_is_nsec3rel(const knot_rrset_t *rr)
+{
+	if (rr == NULL) {
+		return false;
+	}
+
+	/* Is NSEC3 or non-empty RRSIG covering NSEC3. */
+	return ((rr->type == KNOT_RRTYPE_NSEC3) ||
+	        (rr->type == KNOT_RRTYPE_RRSIG
+	         && knot_rrsig_type_covered(rr->rrs.rdata) == KNOT_RRTYPE_NSEC3));
+}
+
+_public_
+int knot_rrset_rr_to_canonical(knot_rrset_t *rrset)
+{
+	if (rrset == NULL || rrset->rrs.count != 1) {
+		return KNOT_EINVAL;
+	}
+
+	/* Convert owner for all RRSets. */
+	knot_dname_to_lower(rrset->owner);
+
+	/* Convert DNAMEs in RDATA only for RFC4034 types. */
+	if (!knot_rrtype_should_be_lowercased(rrset->type)) {
+		return KNOT_EOK;
+	}
+
+	const knot_rdata_descriptor_t *desc = knot_get_rdata_descriptor(rrset->type);
+	if (desc->type_name == NULL) {
+		desc = knot_get_obsolete_rdata_descriptor(rrset->type);
+	}
+
+	uint16_t rdlen = rrset->rrs.rdata->len;
+	uint8_t *pos = rrset->rrs.rdata->data;
+	uint8_t *endpos = pos + rdlen;
+
+	/* No RDATA */
+	if (rdlen == 0) {
+		return KNOT_EOK;
+	}
+
+	/* Otherwise, whole and not malformed RDATA are expected. */
+	for (int i = 0; desc->block_types[i] != KNOT_RDATA_WF_END; ++i) {
+		int type = desc->block_types[i];
+		switch (type) {
+		case KNOT_RDATA_WF_COMPRESSIBLE_DNAME:
+		case KNOT_RDATA_WF_DECOMPRESSIBLE_DNAME:
+		case KNOT_RDATA_WF_FIXED_DNAME:
+			knot_dname_to_lower(pos);
+			pos += knot_dname_size(pos);
+			break;
+		case KNOT_RDATA_WF_NAPTR_HEADER:
+			; int ret = knot_naptr_header_size(pos, endpos);
+			if (ret < 0) {
+				return ret;
+			}
+
+			pos += ret;
+			break;
+		case KNOT_RDATA_WF_REMAINDER:
+			break;
+		default:
+			/* Fixed size block */
+			assert(type > 0);
+			pos += type;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+size_t knot_rrset_size(const knot_rrset_t *rrset)
+{
+	if (rrset == NULL) {
+		return 0;
+	}
+
+	uint16_t rr_count = rrset->rrs.count;
+
+	size_t total_size = knot_dname_size(rrset->owner) * rr_count;
+
+	knot_rdata_t *rr = rrset->rrs.rdata;
+	for (size_t i = 0; i < rr_count; ++i) {
+		/* 10B = TYPE + CLASS + TTL + RDLENGTH */
+		total_size += rr->len + 10;
+		rr = knot_rdataset_next(rr);
+	}
+
+	return total_size;
+}
diff --git a/src/libknot/rrset.h b/src/libknot/rrset.h
new file mode 100644
index 0000000..fdc5719
--- /dev/null
+++ b/src/libknot/rrset.h
@@ -0,0 +1,194 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief RRSet structure and API for manipulating it.
+ *
+ * \addtogroup rr
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "libknot/dname.h"
+#include "libknot/descriptor.h"
+#include "libknot/mm_ctx.h"
+#include "libknot/rdataset.h"
+
+/*!
+ * \brief Structure for representing RRSet.
+ *
+ * For RRSet definition see RFC2181, Section 5.
+ */
+typedef struct {
+	knot_dname_t *owner;  /*!< Domain name being the owner of the RRSet. */
+	uint32_t ttl;         /*!< TTL of the RRset. */
+	uint16_t type;        /*!< TYPE of the RRset. */
+	uint16_t rclass;      /*!< CLASS of the RRSet. */
+	knot_rdataset_t rrs;  /*!< RRSet's RRs */
+	/* Optional fields. */
+	void *additional;     /*!< Additional records. */
+} knot_rrset_t;
+
+/*!
+ * \brief Creates a new RRSet with the given properties.
+ *
+ * The created RRSet contains no RDATAs (i.e. is actually empty).
+ *
+ * \param owner   OWNER of the RRSet.
+ * \param type    TYPE of the RRSet.
+ * \param rclass  CLASS of the RRSet.
+ * \param ttl     TTL of the RRSet.
+ * \param mm      Memory context.
+ *
+ * \return New RRSet structure or NULL if an error occurred.
+ */
+knot_rrset_t *knot_rrset_new(const knot_dname_t *owner, uint16_t type,
+                             uint16_t rclass, uint32_t ttl, knot_mm_t *mm);
+
+/*!
+ * \brief Initializes RRSet structure with given data.
+ *
+ * \param rrset   RRSet to init.
+ * \param owner   RRSet owner to use.
+ * \param type    RR type to use.
+ * \param rclass  Class to use.
+ * \param ttl     TTL to use.
+ */
+inline static void knot_rrset_init(knot_rrset_t *rrset, knot_dname_t *owner,
+                                   uint16_t type, uint16_t rclass, uint32_t ttl)
+{
+	if (rrset != NULL) {
+		rrset->owner = owner;
+		rrset->type = type;
+		rrset->rclass = rclass;
+		rrset->ttl = ttl;
+		knot_rdataset_init(&rrset->rrs);
+		rrset->additional = NULL;
+	}
+}
+
+/*!
+ * \brief Initializes given RRSet structure.
+ *
+ * \param rrset  RRSet to init.
+ */
+inline static void knot_rrset_init_empty(knot_rrset_t *rrset)
+{
+	knot_rrset_init(rrset, NULL, 0, KNOT_CLASS_IN, 0);
+}
+
+/*!
+ * \brief Creates new RRSet from \a src RRSet.
+ *
+ * \param src  Source RRSet.
+ * \param mm   Memory context.
+ *
+ * \retval Pointer to new RRSet if all went OK.
+ * \retval NULL on error.
+ */
+knot_rrset_t *knot_rrset_copy(const knot_rrset_t *src, knot_mm_t *mm);
+
+/*!
+ * \brief Destroys the RRSet structure and all its substructures.
+ *
+ * \param rrset  RRset to be destroyed.
+ * \param mm     Memory context.
+ */
+void knot_rrset_free(knot_rrset_t *rrset, knot_mm_t *mm);
+
+/*!
+ * \brief Frees structures inside RRSet, but not the RRSet itself.
+ *
+ * \param rrset  RRSet to be cleared.
+ * \param mm     Memory context used for allocations.
+ */
+void knot_rrset_clear(knot_rrset_t *rrset, knot_mm_t *mm);
+
+/*!
+ * \brief Adds the given RDATA to the RRSet.
+ *
+ * \param rrset  RRSet to add the RDATA to.
+ * \param data   RDATA to add to the RRSet.
+ * \param len    Length of RDATA.
+ * \param mm     Memory context.
+ *
+ * \return KNOT_E*
+ */
+int knot_rrset_add_rdata(knot_rrset_t *rrset, const uint8_t *data, uint16_t len,
+                         knot_mm_t *mm);
+
+/*!
+ * \brief Compares two RRSets for equality.
+ *
+ * \param r1   First RRSet.
+ * \param r2   Second RRSet.
+ * \param incl_ttl  Compare also TTLs for equality.
+ *
+ * \retval True   if RRSets are equal.
+ * \retval False  if RRSets are not equal.
+ */
+bool knot_rrset_equal(const knot_rrset_t *r1, const knot_rrset_t *r2,
+                      bool incl_ttl);
+
+/*!
+ * \brief Checks whether RRSet is empty.
+ *
+ * \param rrset  RRSet to check.
+ *
+ * \retval True if RRSet is empty.
+ * \retval False if RRSet is not empty.
+ */
+inline static bool knot_rrset_empty(const knot_rrset_t *rrset)
+{
+	return rrset == NULL || rrset->rrs.count == 0;
+}
+
+/*!
+ * \brief Return whether the RR type is NSEC3 related (NSEC3 or RRSIG).
+ */
+bool knot_rrset_is_nsec3rel(const knot_rrset_t *rr);
+
+/*!
+ * \brief Convert one RR into canonical format.
+ *
+ * Owner is always converted to lowercase. RDATA domain names are converted only
+ * for types listed in RFC 4034, Section 6.2, except for NSEC (updated by
+ * RFC 6840, Section 5.1) and A6 (not supported).
+ *
+ * \note If RRSet with more RRs is given to this function, only the first RR
+ *       will be converted.
+ * \warning This function expects either empty RDATA or full, not malformed
+ *          RDATA. If malformed RRSet is passed to this function, memory errors
+ *          may occur.
+ *
+ * \param rrset  RR to convert.
+ */
+int knot_rrset_rr_to_canonical(knot_rrset_t *rrset);
+
+/*!
+ * \brief Size of rrset in wire format.
+ *
+ * \retval size in bytes
+ */
+size_t knot_rrset_size(const knot_rrset_t *rrset);
+
+/*! @} */
diff --git a/src/libknot/rrtype/dnskey.h b/src/libknot/rrtype/dnskey.h
new file mode 100644
index 0000000..229b353
--- /dev/null
+++ b/src/libknot/rrtype/dnskey.h
@@ -0,0 +1,72 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+/*! See https://www.iana.org/assignments/dnskey-flags */
+/*! /brief "Secure entry point" marks KSK and CSK in practice. */
+#define KNOT_DNSKEY_FLAG_SEP	1
+/*! /brief The key is ALLOWED to be used for zone contents signing. */
+#define KNOT_DNSKEY_FLAG_ZONE	256
+/*! /brief The key MUST NOT be used for validation. */
+#define KNOT_DNSKEY_FLAG_REVOKE	128
+
+static inline
+uint16_t knot_dnskey_flags(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data);
+}
+
+static inline
+uint8_t knot_dnskey_proto(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 2);
+}
+
+static inline
+uint8_t knot_dnskey_alg(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 3);
+}
+
+static inline
+uint16_t knot_dnskey_key_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->len - 4;
+}
+
+static inline
+const uint8_t *knot_dnskey_key(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 4;
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/ds.h b/src/libknot/rrtype/ds.h
new file mode 100644
index 0000000..cb82e08
--- /dev/null
+++ b/src/libknot/rrtype/ds.h
@@ -0,0 +1,64 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+static inline
+uint16_t knot_ds_key_tag(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data);
+}
+
+static inline
+uint8_t knot_ds_alg(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 2);
+}
+
+static inline
+uint8_t knot_ds_digest_type(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 3);
+}
+
+static inline
+uint16_t knot_ds_digest_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->len - 4;
+}
+
+static inline
+const uint8_t *knot_ds_digest(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 4;
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/naptr.c b/src/libknot/rrtype/naptr.c
new file mode 100644
index 0000000..9307816
--- /dev/null
+++ b/src/libknot/rrtype/naptr.c
@@ -0,0 +1,47 @@
+/*  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/>.
+ */
+
+#include <assert.h>
+#include <stdint.h>
+
+#include "libknot/attribute.h"
+#include "libknot/rrtype/naptr.h"
+#include "contrib/wire_ctx.h"
+
+_public_
+int knot_naptr_header_size(const uint8_t *naptr, const uint8_t *maxp)
+{
+	if (!naptr || !maxp || naptr >= maxp) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init_const(naptr, maxp - naptr);
+
+	/* Fixed fields size (order, preference) */
+	wire_ctx_skip(&wire, 2 * sizeof(uint16_t));
+
+	/* Variable fields size (flags, services, regexp) */
+	for (int i = 0; i < 3; i++) {
+		uint8_t size = wire_ctx_read_u8(&wire);
+		wire_ctx_skip(&wire, size);
+	}
+
+	if (wire.error != KNOT_EOK) {
+		return KNOT_EMALF;
+	}
+
+	return wire_ctx_offset(&wire);
+}
diff --git a/src/libknot/rrtype/naptr.h b/src/libknot/rrtype/naptr.h
new file mode 100644
index 0000000..ab14a9f
--- /dev/null
+++ b/src/libknot/rrtype/naptr.h
@@ -0,0 +1,41 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+/*!
+ * \brief Counts the size of the NAPTR RDATA before the Replacement domain name.
+ *
+ * See RFC 2915.
+ *
+ * \param naptr  Wire format of NAPTR record.
+ * \param maxp   Limit of the wire format.
+ *
+ * \retval KNOT_EMALF if the record is malformed.
+ * \retval Size of the RDATA before the Replacement domain name.
+ */
+int knot_naptr_header_size(const uint8_t *naptr, const uint8_t *maxp);
+
+/*! @} */
diff --git a/src/libknot/rrtype/nsec.h b/src/libknot/rrtype/nsec.h
new file mode 100644
index 0000000..be1ce31
--- /dev/null
+++ b/src/libknot/rrtype/nsec.h
@@ -0,0 +1,50 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/dname.h"
+#include "libknot/rdata.h"
+
+static inline
+const knot_dname_t *knot_nsec_next(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+uint16_t knot_nsec_bitmap_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->len - knot_dname_size(knot_nsec_next(rdata));
+}
+
+static inline
+const uint8_t *knot_nsec_bitmap(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + knot_dname_size(knot_nsec_next(rdata));
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/nsec3.h b/src/libknot/rrtype/nsec3.h
new file mode 100644
index 0000000..5bb94bd
--- /dev/null
+++ b/src/libknot/rrtype/nsec3.h
@@ -0,0 +1,98 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+/*!
+ * \brief NSEC3 rdata constants.
+ */
+#define KNOT_NSEC3_ALGORITHM_SHA1	1
+#define KNOT_NSEC3_FLAG_OPT_OUT		1
+
+static inline
+uint8_t knot_nsec3_alg(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data);
+}
+
+static inline
+uint8_t knot_nsec3_flags(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 1);
+}
+
+static inline
+uint16_t knot_nsec3_iters(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data + 2);
+}
+
+static inline
+uint8_t knot_nsec3_salt_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 4);
+}
+
+static inline
+const uint8_t *knot_nsec3_salt(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 5;
+}
+
+static inline
+uint8_t knot_nsec3_next_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 5 + knot_nsec3_salt_len(rdata));
+}
+
+static inline
+const uint8_t *knot_nsec3_next(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 6 + knot_nsec3_salt_len(rdata);
+}
+
+static inline
+uint16_t knot_nsec3_bitmap_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->len - 6 - knot_nsec3_salt_len(rdata) - knot_nsec3_next_len(rdata);
+}
+
+static inline
+const uint8_t *knot_nsec3_bitmap(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 6 + knot_nsec3_salt_len(rdata) + knot_nsec3_next_len(rdata);
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/nsec3param.h b/src/libknot/rrtype/nsec3param.h
new file mode 100644
index 0000000..43bce18
--- /dev/null
+++ b/src/libknot/rrtype/nsec3param.h
@@ -0,0 +1,64 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+static inline
+uint8_t knot_nsec3param_alg(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data);
+}
+
+static inline
+uint8_t knot_nsec3param_flags(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 1);
+}
+
+static inline
+uint16_t knot_nsec3param_iters(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data + 2);
+}
+
+static inline
+uint8_t knot_nsec3param_salt_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 4);
+}
+
+static inline
+const uint8_t *knot_nsec3param_salt(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 5;
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/opt.c b/src/libknot/rrtype/opt.c
new file mode 100644
index 0000000..294689c
--- /dev/null
+++ b/src/libknot/rrtype/opt.c
@@ -0,0 +1,687 @@
+/*  Copyright (C) 2022 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 <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+
+#include "libknot/attribute.h"
+#include "libknot/consts.h"
+#include "libknot/descriptor.h"
+#include "libknot/lookup.h"
+#include "libknot/packet/pkt.h"
+#include "libknot/rrtype/opt.h"
+#include "contrib/mempattern.h"
+#include "contrib/wire_ctx.h"
+
+/*! \brief Some implementation-related constants. */
+enum {
+	/*! \brief Byte offset of the extended RCODE field in TTL. */
+	EDNS_OFFSET_RCODE   = 0,
+	/*! \brief Byte offset of the version field in TTL. */
+	EDNS_OFFSET_VERSION = 1,
+
+	/*! \brief Byte offset of the family field in option data. */
+	EDNS_OFFSET_CLIENT_SUBNET_FAMILY   = 0,
+	/*! \brief Byte offset of the source mask field in option data. */
+	EDNS_OFFSET_CLIENT_SUBNET_SRC_MASK = 2,
+	/*! \brief Byte offset of the destination mask field in option data. */
+	EDNS_OFFSET_CLIENT_SUBNET_DST_MASK = 3,
+	/*! \brief Byte offset of the address field in option data. */
+	EDNS_OFFSET_CLIENT_SUBNET_ADDR     = 4,
+};
+
+_public_
+int knot_edns_init(knot_rrset_t *opt_rr, uint16_t max_pld,
+                   uint8_t ext_rcode, uint8_t ver, knot_mm_t *mm)
+{
+	if (opt_rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Initialize RRSet. */
+	knot_dname_t *owner = knot_dname_copy((const uint8_t *)"", mm);
+	if (owner == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	knot_rrset_init(opt_rr, owner, KNOT_RRTYPE_OPT, max_pld, 0);
+
+	/* Create empty RDATA */
+	int ret = knot_rrset_add_rdata(opt_rr, NULL, 0, mm);
+	if (ret == KNOT_EOK) {
+		knot_edns_set_ext_rcode(opt_rr, ext_rcode);
+		knot_edns_set_version(opt_rr, ver);
+	}
+
+	return ret;
+}
+
+_public_
+uint8_t knot_edns_get_ext_rcode(const knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	uint32_t ttl = 0;
+	wire_ctx_t w = wire_ctx_init((uint8_t *)&ttl, sizeof(ttl));
+	// TTL is stored in machine byte order. Convert it to wire order first.
+	wire_ctx_write_u32(&w, opt_rr->ttl);
+	wire_ctx_set_offset(&w, EDNS_OFFSET_RCODE);
+	return wire_ctx_read_u8(&w);
+}
+
+static void set_value_to_ttl(knot_rrset_t *opt_rr, size_t offset, uint8_t value)
+{
+	uint32_t ttl = 0;
+	wire_ctx_t w = wire_ctx_init((uint8_t *)&ttl, sizeof(ttl));
+	// TTL is stored in machine byte order. Convert it to wire order first.
+	wire_ctx_write_u32(&w, opt_rr->ttl);
+	// Set the Extended RCODE in the converted TTL
+	wire_ctx_set_offset(&w, offset);
+	wire_ctx_write_u8(&w, value);
+	// Convert it back to machine byte order
+	wire_ctx_set_offset(&w, 0);
+	uint32_t ttl_local = wire_ctx_read_u32(&w);
+	// Store the TTL to the RDATA
+	opt_rr->ttl = ttl_local;
+}
+
+_public_
+void knot_edns_set_ext_rcode(knot_rrset_t *opt_rr, uint8_t ext_rcode)
+{
+	assert(opt_rr != NULL);
+	set_value_to_ttl(opt_rr, EDNS_OFFSET_RCODE, ext_rcode);
+}
+
+_public_
+uint8_t knot_edns_get_version(const knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	uint32_t ttl = 0;
+	wire_ctx_t w = wire_ctx_init((uint8_t *)&ttl, sizeof(ttl));
+	// TTL is stored in machine byte order. Convert it to wire order first.
+	wire_ctx_write_u32(&w, opt_rr->ttl);
+	wire_ctx_set_offset(&w, EDNS_OFFSET_VERSION);
+	return wire_ctx_read_u8(&w);
+}
+
+_public_
+void knot_edns_set_version(knot_rrset_t *opt_rr, uint8_t version)
+{
+	assert(opt_rr != NULL);
+	set_value_to_ttl(opt_rr, EDNS_OFFSET_VERSION, version);
+}
+
+/*!
+ * \brief Add new EDNS option by replacing RDATA of OPT RR.
+ *
+ * \param opt   OPT RR structure to add the Option to.
+ * \param code  Option code.
+ * \param size  Option data length in bytes.
+ * \param mm    Memory context.
+ *
+ * \return Pointer to uninitialized option data.
+ */
+static uint8_t *edns_add(knot_rrset_t *opt, uint16_t code, uint16_t size,
+                         knot_mm_t *mm)
+{
+	assert(opt->rrs.count == 1);
+
+	// extract old RDATA
+
+	uint8_t *old_data = opt->rrs.rdata->data;
+	uint16_t old_data_len = opt->rrs.rdata->len;
+
+	// construct new RDATA
+
+	uint16_t new_data_len = old_data_len + KNOT_EDNS_OPTION_HDRLEN + size;
+	uint8_t new_data[new_data_len];
+
+	wire_ctx_t wire = wire_ctx_init(new_data, new_data_len);
+	wire_ctx_write(&wire, old_data, old_data_len);
+	wire_ctx_write_u16(&wire, code);
+	wire_ctx_write_u16(&wire, size);
+
+	// prepare EDNS option data
+
+	size_t offset = wire_ctx_offset(&wire);
+	wire_ctx_clear(&wire, size);
+
+	assert(wire_ctx_available(&wire) == 0);
+	assert(wire.error == KNOT_EOK);
+
+	// replace RDATA
+
+	knot_rdataset_clear(&opt->rrs, mm);
+	if (knot_rrset_add_rdata(opt, new_data, new_data_len, mm) != KNOT_EOK) {
+		return NULL;
+	}
+
+	return opt->rrs.rdata->data + offset;
+}
+
+_public_
+int knot_edns_reserve_option(knot_rrset_t *opt_rr, uint16_t code,
+                             uint16_t size, uint8_t **wire_ptr, knot_mm_t *mm)
+{
+	if (!opt_rr) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t *wire = edns_add(opt_rr, code, size, mm);
+	if (!wire) {
+		return KNOT_ENOMEM;
+	}
+
+	if (wire_ptr) {
+		*wire_ptr = wire;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_add_option(knot_rrset_t *opt_rr, uint16_t code,
+                         uint16_t size, const uint8_t *data, knot_mm_t *mm)
+{
+	if (!opt_rr || (size > 0 && !data)) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t *wire = edns_add(opt_rr, code, size, mm);
+	if (!wire) {
+		return KNOT_ENOMEM;
+	}
+
+	if (size > 0) {
+		memcpy(wire, data, size);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+uint8_t *knot_edns_get_option(const knot_rrset_t *opt_rr, uint16_t code,
+                              const uint8_t *previous)
+{
+	if (opt_rr == NULL) {
+		return NULL;
+	}
+
+	knot_rdata_t *rdata = opt_rr->rrs.rdata;
+	if (rdata == NULL || rdata->len == 0) {
+		return NULL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init_const(rdata->data, rdata->len);
+	if (previous != NULL) {
+		if (previous < wire.wire) {
+			return NULL;
+		}
+		wire_ctx_set_offset(&wire, previous - wire.wire + 2);
+		uint16_t opt_len = wire_ctx_read_u16(&wire);
+		wire_ctx_skip(&wire, opt_len);
+	}
+
+	while (wire_ctx_available(&wire) > 0 && wire.error == KNOT_EOK) {
+		uint8_t *pos = wire.position;
+		uint16_t opt_code = wire_ctx_read_u16(&wire);
+		uint16_t opt_len = wire_ctx_read_u16(&wire);
+		wire_ctx_skip(&wire, opt_len);
+		if (wire.error == KNOT_EOK && opt_code == code) {
+			return pos;
+		}
+	}
+
+	return NULL;
+}
+
+_public_
+int knot_edns_get_options(knot_rrset_t *opt_rr, knot_edns_options_t **out,
+                          knot_mm_t *mm)
+{
+	if (opt_rr == NULL || opt_rr->rrs.count > 1 || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rdata_t *rdata = opt_rr->rrs.rdata;
+	if (rdata == NULL || rdata->len == 0) {
+		return KNOT_EOK;
+	}
+
+	knot_edns_options_t *options = mm_calloc(mm, 1, sizeof(*options));
+
+	wire_ctx_t wire = wire_ctx_init_const(rdata->data, rdata->len);
+
+	while (wire_ctx_available(&wire) > 0 && wire.error == KNOT_EOK) {
+		uint8_t *pos = wire.position;
+		uint16_t opt_code = wire_ctx_read_u16(&wire);
+		uint16_t opt_len = wire_ctx_read_u16(&wire);
+		wire_ctx_skip(&wire, opt_len);
+		if (wire.error == KNOT_EOK && opt_code <= KNOT_EDNS_MAX_OPTION_CODE) {
+			options->ptr[opt_code] = pos;
+		}
+	}
+
+	if (wire.error != KNOT_EOK) {
+		mm_free(mm, options);
+		return wire.error;
+	}
+
+	*out = options;
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_alignment_size(size_t current_pkt_size,
+                             size_t current_opt_size,
+                             size_t block_size)
+{
+	if (current_opt_size == 0 || block_size == 0) {
+		return -1;
+	}
+
+	size_t current_size = current_pkt_size + current_opt_size;
+	if (current_size % block_size == 0) {
+		return -1;
+	}
+
+	size_t modulo = (current_size + KNOT_EDNS_OPTION_HDRLEN) % block_size;
+
+	return (modulo == 0) ? 0 : block_size - modulo;
+}
+
+/*!
+ * \brief EDNS Client Subnet family data.
+ */
+typedef struct {
+	int platform;   //!< Platform family identifier.
+	uint16_t iana;  //!< IANA family identifier.
+	size_t offset;  //!< Socket address offset.
+	size_t size;    //!< Socket address size.
+} ecs_family_t;
+
+#define ECS_INIT(platform, iana, type, member) \
+	{ platform, iana, offsetof(type, member), sizeof(((type *)0)->member) }
+
+/*!
+ * \brief Supported EDNS Client Subnet families.
+ *
+ * https://www.iana.org/assignments/address-family-numbers/address-family-numbers.xml
+ */
+static const ecs_family_t ECS_FAMILIES[] = {
+	ECS_INIT(AF_INET,  KNOT_ADDR_FAMILY_IPV4, struct sockaddr_in,  sin_addr),
+	ECS_INIT(AF_INET6, KNOT_ADDR_FAMILY_IPV6, struct sockaddr_in6, sin6_addr),
+	{ 0 }
+};
+
+/*!
+ * \brief Lookup ECS family by platform identifier.
+ */
+static const ecs_family_t *ecs_family_by_platform(int family)
+{
+	for (const ecs_family_t *f = ECS_FAMILIES; f->size > 0; f++) {
+		if (f->platform == family) {
+			return f;
+		}
+	}
+
+	return NULL;
+}
+
+/*!
+ * \brief Lookup ECS family by IANA identifier.
+ */
+static const ecs_family_t *ecs_family_by_iana(uint16_t family)
+{
+	for (const ecs_family_t *f = ECS_FAMILIES; f->size > 0; f++) {
+		if (f->iana == family) {
+			return f;
+		}
+	}
+
+	return NULL;
+}
+
+/*!
+ * \brief Get ECS address prefix size in bytes.
+ */
+static uint16_t ecs_prefix_size(uint8_t prefix)
+{
+	return (prefix + 7) / 8;
+}
+
+static uint8_t ecs_prefix_lsb_mask(uint8_t prefix)
+{
+	int modulo = prefix % 8;
+	if (modulo == 0) {
+		return 0xff;
+	} else {
+		return 0xff << (8 - modulo);
+	}
+}
+
+/*!
+ * \brief Write raw network address prefix and clear the rest of the buffer.
+ */
+static void ecs_write_address(wire_ctx_t *dst, wire_ctx_t *src, int8_t prefix)
+{
+	size_t count = ecs_prefix_size(prefix);
+	uint8_t lsb_mask = ecs_prefix_lsb_mask(prefix);
+
+	if (count > 0) {
+		wire_ctx_copy(dst, src, count);
+		if (dst->error != KNOT_EOK) {
+			return;
+		}
+		dst->position[-1] &= lsb_mask;
+	}
+
+	size_t blank = wire_ctx_available(dst);
+	wire_ctx_clear(dst, blank);
+}
+
+/*!
+ * \brief Check if ECS parameters are valid.
+ */
+static bool ecs_is_valid(const knot_edns_client_subnet_t *ecs)
+{
+	if (ecs == NULL) {
+		return false;
+	}
+
+	const ecs_family_t *f = ecs_family_by_iana(ecs->family);
+
+	return f != NULL &&                        // known family check
+	       (ecs->source_len <= f->size * 8) && // family address maximum check
+	       (ecs->scope_len  <= f->size * 8);   // family address maximum check
+}
+
+_public_
+uint16_t knot_edns_client_subnet_size(const knot_edns_client_subnet_t *ecs)
+{
+	if (!ecs_is_valid(ecs)) {
+		return 0;
+	}
+
+	return sizeof(ecs->family) +
+	       sizeof(ecs->source_len) +
+	       sizeof(ecs->scope_len) +
+	       ecs_prefix_size(ecs->source_len);
+}
+
+_public_
+int knot_edns_client_subnet_write(uint8_t *option, uint16_t option_len,
+                                  const knot_edns_client_subnet_t *ecs)
+{
+	if (option == NULL || ecs == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (!ecs_is_valid(ecs)) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init(option, option_len);
+	wire_ctx_t addr = wire_ctx_init_const(ecs->address, sizeof(ecs->address));
+
+	wire_ctx_write_u16(&wire, ecs->family);
+	wire_ctx_write_u8(&wire, ecs->source_len);
+	wire_ctx_write_u8(&wire, ecs->scope_len);
+	ecs_write_address(&wire, &addr, ecs->source_len);
+
+	if (wire.error != KNOT_EOK) {
+		return wire.error;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_client_subnet_parse(knot_edns_client_subnet_t *ecs,
+                                  const uint8_t *option, uint16_t option_len)
+{
+	if (ecs == NULL || option == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_edns_client_subnet_t result = { 0 };
+
+	wire_ctx_t wire = wire_ctx_init_const(option, option_len);
+	wire_ctx_t addr = wire_ctx_init(result.address, sizeof(result.address));
+
+	result.family     = wire_ctx_read_u16(&wire);
+	result.source_len = wire_ctx_read_u8(&wire);
+	result.scope_len  = wire_ctx_read_u8(&wire);
+	ecs_write_address(&addr, &wire, result.source_len);
+
+	if (addr.error != KNOT_EOK || wire.error != KNOT_EOK) {
+		return KNOT_EMALF;
+	}
+
+	if (!ecs_is_valid(&result)) {
+		return KNOT_EMALF;
+	}
+
+	*ecs = result;
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_client_subnet_set_addr(knot_edns_client_subnet_t *ecs,
+                                     const struct sockaddr_storage *addr)
+{
+	if (ecs == NULL || addr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	const ecs_family_t *f = ecs_family_by_platform(addr->ss_family);
+	if (f == NULL) {
+		return KNOT_ENOTSUP;
+	}
+
+	ecs->family = f->iana;
+	ecs->source_len = f->size * 8;
+	ecs->scope_len = 0;
+
+	wire_ctx_t dst = wire_ctx_init(ecs->address, sizeof(ecs->address));
+	wire_ctx_t src = wire_ctx_init_const((uint8_t *)addr + f->offset, f->size);
+	ecs_write_address(&dst, &src, ecs->source_len);
+
+	assert(dst.error == KNOT_EOK);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_edns_client_subnet_get_addr(struct sockaddr_storage *addr,
+                                     const knot_edns_client_subnet_t *ecs)
+{
+	if (addr == NULL || ecs == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	const ecs_family_t *f = ecs_family_by_iana(ecs->family);
+	if (f == NULL) {
+		return KNOT_ENOTSUP;
+	}
+
+	addr->ss_family = f->platform;
+
+	wire_ctx_t dst = wire_ctx_init((uint8_t *)addr + f->offset, f->size);
+	wire_ctx_t src = wire_ctx_init_const(ecs->address, sizeof(ecs->address));
+	ecs_write_address(&dst, &src, ecs->source_len);
+
+	assert(dst.error == KNOT_EOK);
+
+	return KNOT_EOK;
+}
+
+_public_
+uint16_t knot_edns_keepalive_size(uint16_t timeout)
+{
+	return (timeout > 0) ? sizeof(uint16_t) : 0;
+}
+
+_public_
+int knot_edns_keepalive_write(uint8_t *option, uint16_t option_len, uint16_t timeout)
+{
+	if (option == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (timeout == 0) {
+		return KNOT_EOK;
+	}
+
+	wire_ctx_t wire = wire_ctx_init(option, option_len);
+	wire_ctx_write_u16(&wire, timeout);
+
+	return wire.error;
+}
+
+_public_
+int knot_edns_keepalive_parse(uint16_t *timeout, const uint8_t *option,
+                              uint16_t option_len)
+{
+	if (timeout == NULL || option == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	*timeout = 0;
+
+	if (option_len > 0) {
+		wire_ctx_t wire = wire_ctx_init_const(option, option_len);
+		*timeout = wire_ctx_read_u16(&wire);
+
+		if (wire.error != KNOT_EOK) {
+			return KNOT_EMALF;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+uint16_t knot_edns_chain_size(const knot_dname_t *point)
+{
+	return knot_dname_size(point);
+}
+
+_public_
+int knot_edns_chain_write(uint8_t *option, uint16_t option_len,
+                          const knot_dname_t *point)
+{
+	if (option == NULL || point == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init(option, option_len);
+	wire_ctx_write(&wire, point, knot_dname_size(point));
+
+	return wire.error;
+}
+
+_public_
+int knot_edns_chain_parse(knot_dname_t **point, const uint8_t *option,
+                          uint16_t option_len, knot_mm_t *mm)
+{
+	if (point == NULL || option == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = knot_dname_wire_check(option, option + option_len, NULL);
+	if (ret <= 0) {
+		return KNOT_EMALF;
+	}
+
+	*point = knot_dname_copy(option, mm);
+	if (*point == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+uint16_t knot_edns_cookie_size(const knot_edns_cookie_t *cc,
+                               const knot_edns_cookie_t *sc)
+{
+	if (cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE) {
+		return 0;
+	} else if (sc == NULL || sc->len == 0) {
+		return KNOT_EDNS_COOKIE_CLNT_SIZE;
+	} else if (sc->len < KNOT_EDNS_COOKIE_SRVR_MIN_SIZE ||
+	           sc->len > KNOT_EDNS_COOKIE_SRVR_MAX_SIZE) {
+		return 0;
+	} else {
+		return cc->len + sc->len;
+	}
+}
+
+_public_
+int knot_edns_cookie_write(uint8_t *option, uint16_t option_len,
+                           const knot_edns_cookie_t *cc,
+                           const knot_edns_cookie_t *sc)
+{
+	if (option == NULL || cc == NULL || cc->len != KNOT_EDNS_COOKIE_CLNT_SIZE) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init(option, option_len);
+	wire_ctx_write(&wire, cc->data, cc->len);
+
+	if (sc != NULL && sc->len > 0) {
+		if (sc->len < KNOT_EDNS_COOKIE_SRVR_MIN_SIZE ||
+		    sc->len > KNOT_EDNS_COOKIE_SRVR_MAX_SIZE) {
+			return KNOT_EINVAL;
+		}
+		wire_ctx_write(&wire, sc->data, sc->len);
+	}
+
+	return wire.error;
+}
+
+_public_
+int knot_edns_cookie_parse(knot_edns_cookie_t *cc, knot_edns_cookie_t *sc,
+                           const uint8_t *option, uint16_t option_len)
+{
+	if (cc == NULL || sc == NULL || option == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	if (option_len != KNOT_EDNS_COOKIE_CLNT_SIZE &&
+	    (option_len < KNOT_EDNS_COOKIE_CLNT_SIZE + KNOT_EDNS_COOKIE_SRVR_MIN_SIZE ||
+	     option_len > KNOT_EDNS_COOKIE_CLNT_SIZE + KNOT_EDNS_COOKIE_SRVR_MAX_SIZE)) {
+		return KNOT_EMALF;
+	}
+	assert(option_len >= KNOT_EDNS_COOKIE_CLNT_SIZE);
+
+	memcpy(cc->data, option, KNOT_EDNS_COOKIE_CLNT_SIZE);
+	cc->len = KNOT_EDNS_COOKIE_CLNT_SIZE;
+
+	size_t sc_len = option_len - KNOT_EDNS_COOKIE_CLNT_SIZE;
+	if (sc_len == 0) {
+		sc->len = 0;
+	} else {
+		memcpy(sc->data, option + KNOT_EDNS_COOKIE_CLNT_SIZE, sc_len);
+		sc->len = sc_len;
+	}
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/rrtype/opt.h b/src/libknot/rrtype/opt.h
new file mode 100644
index 0000000..bce87c2
--- /dev/null
+++ b/src/libknot/rrtype/opt.h
@@ -0,0 +1,587 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Functions for manipulating the EDNS OPT pseudo-RR.
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <sys/socket.h>
+
+#include "libknot/consts.h"
+#include "libknot/rrset.h"
+#include "libknot/wire.h"
+
+/*! \brief Constants related to EDNS. */
+enum {
+	/*! \brief Supported EDNS version. */
+	KNOT_EDNS_VERSION = 0,
+
+	/*! \brief Bit mask for DO bit. */
+	KNOT_EDNS_DO_MASK = (uint32_t)(1 << 15),
+
+	/*! \brief Minimal UDP payload with EDNS enabled. */
+	KNOT_EDNS_MIN_UDP_PAYLOAD    = 512,
+	/*! \brief Minimal payload when using DNSSEC (RFC4035/sec.3). */
+	KNOT_EDNS_MIN_DNSSEC_PAYLOAD = 1220,
+	/*! \brief Maximal UDP payload with EDNS enabled. */
+	KNOT_EDNS_MAX_UDP_PAYLOAD    = 4096,
+
+	/*! \brief Minimum size of EDNS OPT RR in wire format. */
+	KNOT_EDNS_MIN_SIZE                 = 11,
+	/*! \brief Position of the Ext RCODE field in wire format of OPT RR. */
+	KNOT_EDNS_EXT_RCODE_POS            = 5,
+	/*! \brief EDNS OPTION header size. */
+	KNOT_EDNS_OPTION_HDRLEN            = 4,
+
+	/*! \brief Maximal size of EDNS client subnet address in bytes (IPv6). */
+	KNOT_EDNS_CLIENT_SUBNET_ADDRESS_MAXLEN = 16,
+
+	/*! \brief Default EDNS alignment size for a query. */
+	KNOT_EDNS_ALIGNMENT_QUERY_DEFAULT    = 128,
+	/*! \brief Default EDNS alignment size for a response. */
+	KNOT_EDNS_ALIGNMENT_RESPONSE_DEFAULT = 468,
+
+	/*! \brief Current EDNS cookie version. */
+	KNOT_EDNS_COOKIE_VERSION       = 1,
+	/*! \brief EDNS client cookie size. */
+	KNOT_EDNS_COOKIE_CLNT_SIZE     = 8,
+	/*! \brief EDNS minimum server cookie size. */
+	KNOT_EDNS_COOKIE_SRVR_MIN_SIZE = 8,
+	/*! \brief EDNS maximum server cookie size. */
+	KNOT_EDNS_COOKIE_SRVR_MAX_SIZE = 32,
+
+	/*! \brief NSID option code. */
+	KNOT_EDNS_OPTION_NSID          = 3,
+	/*! \brief EDNS Client subnet option code. */
+	KNOT_EDNS_OPTION_CLIENT_SUBNET = 8,
+	/*! \brief EDNS Expire option code. */
+	KNOT_EDNS_OPTION_EXPIRE        = 9,
+	/*! \brief EDNS DNS Cookie option code. */
+	KNOT_EDNS_OPTION_COOKIE        = 10,
+	/*! \brief EDNS TCP Keepalive option code. */
+	KNOT_EDNS_OPTION_TCP_KEEPALIVE = 11,
+	/*! \brief EDNS Padding option code. */
+	KNOT_EDNS_OPTION_PADDING       = 12,
+	/*! \brief EDNS Chain query option code. */
+	KNOT_EDNS_OPTION_CHAIN         = 13,
+
+	/*! \brief EDNS Extended error code. */
+	KNOT_EDNS_OPTION_EDE           = 15,
+	/*! \brief The minimal length for EDE option including option header. */
+	KNOT_EDNS_EDE_MIN_LENGTH       = 6,
+
+	/*! \brief Maximal currently known option code. */
+	KNOT_EDNS_MAX_OPTION_CODE      = 17,
+};
+
+/* Helpers for splitting extended RCODE. */
+#define KNOT_EDNS_RCODE_HI(rc) ((rc >> 4) & 0x00ff)
+#define KNOT_EDNS_RCODE_LO(rc) (rc & 0x000f)
+
+/*!
+ * \brief Initialize OPT RR.
+ *
+ * \param opt_rr     OPT RR to initialize.
+ * \param max_pld    Max UDP payload.
+ * \param ext_rcode  Extended RCODE.
+ * \param ver        Version.
+ * \param mm         Memory context.
+ *
+ * \return KNOT_EOK or an error
+ */
+int knot_edns_init(knot_rrset_t *opt_rr, uint16_t max_pld,
+                   uint8_t ext_rcode, uint8_t ver, knot_mm_t *mm);
+
+/*!
+ * \brief Returns size of the OPT RR in wire format.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ *
+ * \param opt_rr  OPT RR to count the wire size of.
+ *
+ * \return Size of the OPT RR in bytes.
+ */
+static inline
+size_t knot_edns_wire_size(knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	return KNOT_EDNS_MIN_SIZE + opt_rr->rrs.rdata->len;
+}
+
+/*!
+ * \brief Returns the Max UDP payload value stored in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ *
+ * \param opt_rr  OPT RR to get the value from.
+ *
+ * \return Max UDP payload in bytes.
+ */
+static inline
+uint16_t knot_edns_get_payload(const knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	return opt_rr->rclass;
+}
+
+/*!
+ * \brief Sets the Max UDP payload field in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ *
+ * \param opt_rr   OPT RR to set the value to.
+ * \param payload  UDP payload in bytes.
+ */
+static inline
+void knot_edns_set_payload(knot_rrset_t *opt_rr, uint16_t payload)
+{
+	assert(opt_rr != NULL);
+	opt_rr->rclass = payload;
+}
+
+/*!
+ * \brief Returns the Extended RCODE stored in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ * \note There is an assert() for debug checking of the parameter.
+ *
+ * \param opt_rr  OPT RR to get the Extended RCODE from.
+ *
+ * \return Extended RCODE.
+ */
+uint8_t knot_edns_get_ext_rcode(const knot_rrset_t *opt_rr);
+
+/*!
+ * \brief Concatenates OPT RR Extended RCODE field and normal RCODE to get the
+ *        whole Extended RCODE.
+ *
+ * Extended RCODE is created by using the Extended RCODE field from OPT RR as
+ * higher 8 bits and the RCODE from DNS Header as the lower 4 bits, resulting
+ * in a 12-bit unsigned integer. (See RFC 6891, Section 6.1.3).
+ *
+ * \param ext_rcode  Extended RCODE field from OPT RR.
+ * \param rcode      RCODE from DNS Header.
+ *
+ * \return 12-bit Extended RCODE.
+ */
+static inline
+uint16_t knot_edns_whole_rcode(uint8_t ext_rcode, uint8_t rcode)
+{
+	uint16_t high = ext_rcode;
+	return (high << 4) | rcode;
+}
+
+/*!
+ * \brief Sets the Extended RCODE field in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ * \note There is an assert() for debug checking of the parameter.
+ *
+ * \param opt_rr     OPT RR to set the Extended RCODE to.
+ * \param ext_rcode  Extended RCODE to set.
+ */
+void knot_edns_set_ext_rcode(knot_rrset_t *opt_rr, uint8_t ext_rcode);
+
+/*!
+ * \brief Sets the Extended RCODE field in OPT RR wire.
+ *
+ * \param opt_rr     Position of the OPT RR in packet.
+ * \param ext_rcode  Higher 8 bits of Extended RCODE.
+ */
+static inline
+void knot_edns_set_ext_rcode_wire(uint8_t *opt_rr, uint8_t ext_rcode)
+{
+	assert(opt_rr != NULL);
+	*(opt_rr + KNOT_EDNS_EXT_RCODE_POS) = ext_rcode;
+}
+
+/*!
+ * \brief Returns the EDNS version stored in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ * \note There is an assert() for debug checking of the parameter.
+ *
+ * \param opt_rr  OPT RR to get the EDNS version from.
+ *
+ * \return EDNS version.
+ */
+uint8_t knot_edns_get_version(const knot_rrset_t *opt_rr);
+
+/*!
+ * \brief Sets the EDNS version field in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ * \note There is an assert() for debug checking of the parameter.
+ *
+ * \param opt_rr   OPT RR to set the EDNS version to.
+ * \param version  EDNS version to set.
+ */
+void knot_edns_set_version(knot_rrset_t *opt_rr, uint8_t version);
+
+/*!
+ * \brief Returns the state of the DO bit in the OPT RR flags.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ *
+ * \param opt_rr  OPT RR to get the DO bit from.
+ *
+ * \return true if the DO bit is set.
+ * \return false if the DO bit is not set.
+ */
+static inline
+bool knot_edns_do(const knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	return opt_rr->ttl & KNOT_EDNS_DO_MASK;
+}
+
+/*!
+ * \brief Sets the DO bit in the OPT RR.
+ *
+ * \warning This function does not check the parameter, so ensure to check it
+ *          before calling the function. It must not be NULL.
+ *
+ * \param opt_rr  OPT RR to set the DO bit in.
+ */
+static inline
+void knot_edns_set_do(knot_rrset_t *opt_rr)
+{
+	assert(opt_rr != NULL);
+	opt_rr->ttl |= KNOT_EDNS_DO_MASK;
+}
+
+/*!
+ * \brief Add EDNS option into the package with empty (zeroed) content.
+ *
+ * \param[in]  opt_rr    OPT RR structure to reserve the option in.
+ * \param[in]  code      Option code.
+ * \param[in]  size      Desired option size.
+ * \param[out] wire_ptr  Pointer to reserved option data (can be NULL).
+ * \param[in]  mm        Memory context.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_reserve_option(knot_rrset_t *opt_rr, uint16_t code,
+                             uint16_t size, uint8_t **wire_ptr, knot_mm_t *mm);
+
+/*!
+ * \brief Adds EDNS Option to the OPT RR.
+ *
+ * \note The function now supports adding empty OPTION (just having its code).
+ *
+ * \param opt_rr  OPT RR structure to add the Option to.
+ * \param code    Option code.
+ * \param size    Option data length in bytes.
+ * \param data    Option data.
+ * \param mm      Memory context.
+ *
+ * \retval KNOT_EOK
+ * \retval KNOT_ENOMEM
+ */
+int knot_edns_add_option(knot_rrset_t *opt_rr, uint16_t code,
+                         uint16_t size, const uint8_t *data, knot_mm_t *mm);
+
+/*!
+ * \brief Searches the OPT RR for option with the specified code.
+ *
+ * \param opt_rr    OPT RR structure to search in.
+ * \param code      Option code to search for.
+ * \param previous  (Optional) Previously returned option to start searching from,
+ *                  to be able to return another option with the same code.
+ *
+ * \retval pointer to option if found
+ * \retval NULL otherwise.
+ */
+uint8_t *knot_edns_get_option(const knot_rrset_t *opt_rr, uint16_t code,
+                              const uint8_t *previous);
+
+/*!
+ * \brief Pointers to every option in the OPT RR wire.
+ */
+typedef struct {
+	uint8_t *ptr[KNOT_EDNS_MAX_OPTION_CODE + 1];
+} knot_edns_options_t;
+
+/*!
+ * \brief Initializes pointers to options in a given OPT RR.
+ *
+ * \note If the OPT RR has no options, the output is NULL.
+ *
+ * \param opt_rr  OPT RR structure to be used.
+ * \param out     Structure to be initialized.
+ * \param mm      Memory context.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_get_options(knot_rrset_t *opt_rr, knot_edns_options_t **out,
+                          knot_mm_t *mm);
+
+/*!
+ * \brief Returns the option code.
+ *
+ * \param opt  EDNS option (including code, length and data portion).
+ *
+ * \return EDNS option code
+ */
+static inline uint16_t knot_edns_opt_get_code(const uint8_t *opt)
+{
+	assert(opt != NULL);
+	return knot_wire_read_u16(opt);
+}
+
+/*!
+ * \brief Returns the option data length.
+ *
+ * \param opt  EDNS option (including code, length and data portion).
+ *
+ * \return EDNS option length
+ */
+static inline uint16_t knot_edns_opt_get_length(const uint8_t *opt)
+{
+	assert(opt != NULL);
+	return knot_wire_read_u16(opt + sizeof(uint16_t));
+}
+
+/*!
+ * \brief Returns pointer to option data.
+ *
+ * \warning No safety checks are performed on the supplied data.
+ *
+ * \param opt  EDNS option (including code, length and data portion).
+ *
+ * \retval pointer to place where ENDS option data would reside
+ */
+static inline uint8_t *knot_edns_opt_get_data(uint8_t *opt)
+{
+	return opt + KNOT_EDNS_OPTION_HDRLEN;
+}
+
+/*!
+ * \brief Computes additional Padding data length for required packet alignment.
+ *
+ * \param current_pkt_size  Current packet size.
+ * \param current_opt_size  Current OPT rrset size (OPT must be used).
+ * \param block_size        Required packet block length (must be non-zero).
+ *
+ * \return Required padding length or -1 if padding not required.
+ */
+int knot_edns_alignment_size(size_t current_pkt_size,
+                             size_t current_opt_size,
+                             size_t block_size);
+
+/*!
+ * \brief EDNS Client Subnet content.
+ *
+ * \see draft-ietf-dnsop-edns-client-subnet
+ */
+typedef struct {
+	/*! \brief FAMILY */
+	uint16_t family;
+	/*! \brief SOURCE PREFIX-LENGTH */
+	uint8_t source_len;
+	/*! \brief SCOPE PREFIX-LENGTH */
+	uint8_t scope_len;
+	/*! \brief ADDRESS */
+	uint8_t address[KNOT_EDNS_CLIENT_SUBNET_ADDRESS_MAXLEN];
+} knot_edns_client_subnet_t;
+
+/*!
+ * \brief Get the wire size of the EDNS Client Subnet option.
+ *
+ * \param ecs  EDNS Client Subnet data.
+ *
+ * \return Size of the EDNS option data.
+ */
+uint16_t knot_edns_client_subnet_size(const knot_edns_client_subnet_t *ecs);
+
+/*!
+ * \brief Write EDNS Client Subnet data from the ECS structure to wire.
+ *
+ * \param option      EDNS option data buffer.
+ * \param option_len  EDNS option data buffer size.
+ * \param ecs         EDNS Client Subnet data.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_client_subnet_write(uint8_t *option, uint16_t option_len,
+                                  const knot_edns_client_subnet_t *ecs);
+
+/*!
+ * \brief Parse EDNS Client Subnet data from wire to the ECS structure.
+ *
+ * \param[out] ecs         EDNS Client Subnet data.
+ * \param[in]  option      EDNS option data.
+ * \param[in]  option_len  EDNS option size.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_client_subnet_parse(knot_edns_client_subnet_t *ecs,
+                                  const uint8_t *option, uint16_t option_len);
+
+/*!
+ * \brief Set address to the ECS structure.
+ *
+ * \note It also resets the lengths.
+ *
+ * \param ecs   ECS structure to set address into.
+ * \param addr  Address to be set.
+ *
+ * \return Error code. KNOT_EOK if successful.
+ */
+int knot_edns_client_subnet_set_addr(knot_edns_client_subnet_t *ecs,
+                                     const struct sockaddr_storage *addr);
+
+/*!
+ * \brief Get address from the ECS structure.
+ *
+ * Only the family and raw address is set in the structure. The bits not
+ * covered by the prefix length are cleared.
+ *
+ * \param addr  Address to be set.
+ * \param ecs   ECS structure to retrieve address from.
+ */
+int knot_edns_client_subnet_get_addr(struct sockaddr_storage *addr,
+                                     const knot_edns_client_subnet_t *ecs);
+
+/*!
+ * \brief Get size of the EDNS Keepalive option wire size.
+ *
+ * \param[in] timeout  EDNS TCP Keepalive timeout.
+ *
+ * \return Size of the EDNS option data.
+ */
+uint16_t knot_edns_keepalive_size(uint16_t timeout);
+
+/*!
+ * \brief Writes EDNS TCP Keepalive wire data.
+ *
+ * \param[out] option      EDNS option data buffer.
+ * \param[in]  option_len  EDNS option data buffer size.
+ * \param[in]  timeout     EDNS TCP Keepalive timeout.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_keepalive_write(uint8_t *option, uint16_t option_len, uint16_t timeout);
+
+/*!
+ * \brief Parses EDNS TCP Keepalive wire data.
+ *
+ * \param[out] timeout     EDNS TCP Keepalive timeout.
+ * \param[in]  option      EDNS option data.
+ * \param[in]  option_len  EDNS option size.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_keepalive_parse(uint16_t *timeout, const uint8_t *option,
+                              uint16_t option_len);
+
+/*!
+ * \brief Get size of the EDNS Chain option wire size.
+ *
+ * \param[in] point  EDNS Chain closest trusted point.
+ *
+ * \return Size of the EDNS option data or 0 if invalid input.
+ */
+uint16_t knot_edns_chain_size(const knot_dname_t *point);
+
+/*!
+ * \brief Writes EDNS Chain wire data.
+ *
+ * \param[out] option      EDNS option data buffer.
+ * \param[in]  option_len  EDNS option data buffer size.
+ * \param[in]  point       EDNS Chain closest trusted point.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_chain_write(uint8_t *option, uint16_t option_len,
+                          const knot_dname_t *point);
+
+/*!
+ * \brief Parses EDNS Chain wire data.
+ *
+ * \param[out] point       EDNS Chain closest trusted point.
+ * \param[in]  option      EDNS option data.
+ * \param[in]  option_len  EDNS option size.
+ * \param[in]  mm          Memory context.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_chain_parse(knot_dname_t **point, const uint8_t *option,
+                          uint16_t option_len, knot_mm_t *mm);
+
+/*!
+ * \brief DNS Cookie content.
+ */
+typedef struct {
+	uint8_t data[KNOT_EDNS_COOKIE_SRVR_MAX_SIZE]; /*!< Cookie data. */
+	uint16_t len; /*!< Cookie length. */
+} knot_edns_cookie_t;
+
+/*!
+ * \brief Get size of the EDNS Cookie option wire size.
+ *
+ * \param[in] cc  Client cookie.
+ * \param[in] sc  Server cookie (can be NULL).
+ *
+ * \return Size of the EDNS option data or 0 if invalid input.
+ */
+uint16_t knot_edns_cookie_size(const knot_edns_cookie_t *cc,
+                               const knot_edns_cookie_t *sc);
+
+/*!
+ * \brief Writes EDNS cookie wire data.
+ *
+ * \param[out] option      EDNS option data buffer.
+ * \param[in]  option_len  EDNS option data buffer size.
+ * \param[in]  cc          EDNS client cookie.
+ * \param[in]  sc          EDNS server cookie (can be NULL).
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_cookie_write(uint8_t *option, uint16_t option_len,
+                           const knot_edns_cookie_t *cc,
+                           const knot_edns_cookie_t *sc);
+
+/*!
+ * \brief Parses EDNS Cookie wire data.
+ *
+ * \param[out] cc          EDNS client cookie.
+ * \param[out] sc          EDNS server cookie.
+ * \param[in]  option      EDNS option data.
+ * \param[in]  option_len  EDNS option size.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_edns_cookie_parse(knot_edns_cookie_t *cc, knot_edns_cookie_t *sc,
+                           const uint8_t *option, uint16_t option_len);
+
+/*! @} */
diff --git a/src/libknot/rrtype/rdname.h b/src/libknot/rrtype/rdname.h
new file mode 100644
index 0000000..d2be870
--- /dev/null
+++ b/src/libknot/rrtype/rdname.h
@@ -0,0 +1,98 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/descriptor.h"
+#include "libknot/dname.h"
+#include "libknot/rdata.h"
+#include "libknot/rrtype/svcb.h"
+
+static inline
+const knot_dname_t *knot_cname_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+const knot_dname_t *knot_dname_target(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+const knot_dname_t *knot_ns_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+const knot_dname_t *knot_ptr_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+const knot_dname_t *knot_mx_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 2;
+}
+
+static inline
+const knot_dname_t *knot_srv_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 6;
+}
+
+static inline
+const knot_dname_t *knot_rdata_name(const knot_rdata_t *rdata, uint16_t type)
+{
+	assert(rdata);
+	switch (type) {
+		case KNOT_RRTYPE_NS:
+			return knot_ns_name(rdata);
+		case KNOT_RRTYPE_PTR:
+			return knot_ptr_name(rdata);
+		case KNOT_RRTYPE_MX:
+			return knot_mx_name(rdata);
+		case KNOT_RRTYPE_SRV:
+			return knot_srv_name(rdata);
+		case KNOT_RRTYPE_CNAME:
+			return knot_cname_name(rdata);
+		case KNOT_RRTYPE_DNAME:
+			return knot_dname_target(rdata);
+		case KNOT_RRTYPE_SVCB:
+		case KNOT_RRTYPE_HTTPS:
+			return knot_svcb_target(rdata);
+	}
+
+	return NULL;
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/rrsig.h b/src/libknot/rrtype/rrsig.h
new file mode 100644
index 0000000..5a3643d
--- /dev/null
+++ b/src/libknot/rrtype/rrsig.h
@@ -0,0 +1,100 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/dname.h"
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+static inline
+uint16_t knot_rrsig_type_covered(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data);
+}
+
+static inline
+uint8_t knot_rrsig_alg(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 2);
+}
+
+static inline
+uint8_t knot_rrsig_labels(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 3);
+}
+
+static inline
+uint32_t knot_rrsig_original_ttl(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + 4);
+}
+
+static inline
+uint32_t knot_rrsig_sig_expiration(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + 8);
+}
+
+static inline
+uint32_t knot_rrsig_sig_inception(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + 12);
+}
+
+static inline
+uint16_t knot_rrsig_key_tag(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data + 16);
+}
+
+static inline
+const knot_dname_t *knot_rrsig_signer_name(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 18;
+}
+
+static inline
+uint16_t knot_rrsig_signature_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->len - 18 - knot_dname_size(knot_rrsig_signer_name(rdata));
+}
+
+static inline
+const uint8_t *knot_rrsig_signature(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 18 + knot_dname_size(knot_rrsig_signer_name(rdata));
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/soa.h b/src/libknot/rrtype/soa.h
new file mode 100644
index 0000000..9449f00
--- /dev/null
+++ b/src/libknot/rrtype/soa.h
@@ -0,0 +1,94 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/dname.h"
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+static inline
+const knot_dname_t *knot_soa_primary(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data;
+}
+
+static inline
+const knot_dname_t *knot_soa_mailbox(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + knot_dname_size(knot_soa_primary(rdata));
+}
+
+static inline
+size_t knot_soa_names_len(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_dname_size(knot_soa_primary(rdata)) +
+	       knot_dname_size(knot_soa_mailbox(rdata));
+}
+
+static inline
+uint32_t knot_soa_serial(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + knot_soa_names_len(rdata));
+}
+
+static inline
+void knot_soa_serial_set(knot_rdata_t *rdata, uint32_t serial)
+{
+	assert(rdata);
+	knot_wire_write_u32(rdata->data + knot_soa_names_len(rdata), serial);
+}
+
+static inline
+uint32_t knot_soa_refresh(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + knot_soa_names_len(rdata) + 4);
+}
+
+static inline
+uint32_t knot_soa_retry(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + knot_soa_names_len(rdata) + 8);
+}
+
+static inline
+uint32_t knot_soa_expire(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + knot_soa_names_len(rdata) + 12);
+}
+
+static inline
+uint32_t knot_soa_minimum(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data + knot_soa_names_len(rdata) + 16);
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/svcb.h b/src/libknot/rrtype/svcb.h
new file mode 100644
index 0000000..abee597
--- /dev/null
+++ b/src/libknot/rrtype/svcb.h
@@ -0,0 +1,44 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/dname.h"
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+static inline
+uint32_t knot_svcb_priority(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u16(rdata->data);
+}
+
+static inline
+const knot_dname_t *knot_svcb_target(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 2;
+}
+
+/*! @} */
diff --git a/src/libknot/rrtype/tsig.c b/src/libknot/rrtype/tsig.c
new file mode 100644
index 0000000..83f8436
--- /dev/null
+++ b/src/libknot/rrtype/tsig.c
@@ -0,0 +1,409 @@
+/*  Copyright (C) 2021 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 <inttypes.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <time.h>
+
+#include "libdnssec/tsig.h"
+#include "libknot/attribute.h"
+#include "libknot/rrtype/tsig.h"
+#include "libknot/consts.h"
+#include "libknot/dname.h"
+#include "libknot/errcode.h"
+#include "libknot/rrset.h"
+#include "libknot/wire.h"
+#include "contrib/wire_ctx.h"
+
+/*! \brief TSIG field offsets. */
+typedef enum tsig_off_t {
+	TSIG_ALGNAME_O = 0,
+	TSIG_TSIGNED_O,
+	TSIG_FUDGE_O,
+	TSIG_MACLEN_O,
+	TSIG_MAC_O,
+	TSIG_ORIGID_O,
+	TSIG_ERROR_O,
+	TSIG_OLEN_O,
+	TSIG_OTHER_O
+} tsig_off_t;
+
+/* Helpers for RDATA offset calculation. */
+#define TSIG_OFF_MACLEN (4 * sizeof(uint16_t))
+#define TSIG_FIXED_RDLEN (8 * sizeof(uint16_t))
+#define TSIG_OTHER_MAXLEN (3 * sizeof(uint16_t))
+
+/*!
+ * \brief Seek offset of a TSIG RR field.
+ *
+ * \param rr TSIG RR.
+ * \param id Field index.
+ * \param nb Required number of bytes after the offset (for boundaries check).
+ * \return pointer to field on wire or NULL.
+ */
+static uint8_t* rdata_seek(const knot_rrset_t *rr, tsig_off_t id, size_t nb)
+{
+	const knot_rdata_t *rr_data = knot_rdataset_at(&rr->rrs, 0);
+	if (!rr_data || rr_data->len == 0) {
+		return NULL;
+	}
+
+	wire_ctx_t wire = wire_ctx_init_const(rr_data->data, rr_data->len);
+
+	/* TSIG RR names should be already sanitized on parse. */
+	size_t alg_len = knot_dname_size(wire.wire);
+
+	/* Not pretty, but fast. */
+	switch (id) {
+	case TSIG_ALGNAME_O: break;
+	case TSIG_TSIGNED_O:
+		wire_ctx_skip(&wire, alg_len); break;
+	case TSIG_FUDGE_O:
+		wire_ctx_skip(&wire, alg_len + 3 * sizeof(uint16_t));
+		break;
+	case TSIG_MACLEN_O:
+		wire_ctx_skip(&wire, alg_len + 4 * sizeof(uint16_t));
+		break;
+	case TSIG_MAC_O:
+		wire_ctx_skip(&wire, alg_len + 5 * sizeof(uint16_t));
+		break;
+	case TSIG_ORIGID_O:
+		wire_ctx_skip(&wire, alg_len + 4 * sizeof(uint16_t));
+		wire_ctx_skip(&wire, wire_ctx_read_u16(&wire));
+		break;
+	case TSIG_ERROR_O:
+		wire_ctx_skip(&wire, alg_len + 4 * sizeof(uint16_t));
+		wire_ctx_skip(&wire, wire_ctx_read_u16(&wire));
+		wire_ctx_skip(&wire, sizeof(uint16_t));
+		break;
+	case TSIG_OLEN_O:
+		wire_ctx_skip(&wire, alg_len + 4 * sizeof(uint16_t));
+		wire_ctx_skip(&wire, wire_ctx_read_u16(&wire));
+		wire_ctx_skip(&wire, 2 * sizeof(uint16_t));
+		break;
+	case TSIG_OTHER_O:
+		wire_ctx_skip(&wire, alg_len + 4 * sizeof(uint16_t));
+		wire_ctx_skip(&wire, wire_ctx_read_u16(&wire));
+		wire_ctx_skip(&wire, 2 * sizeof(uint16_t));
+		assert(nb == 0);
+		nb = wire_ctx_read_u16(&wire);
+		if (wire_ctx_available(&wire) != nb) {
+			return NULL;
+		}
+		break;
+	}
+
+	if (wire.error != KNOT_EOK) {
+		return NULL;
+	}
+
+	/* Check remaining bytes. */
+
+	if (wire_ctx_available(&wire) < nb){
+		return NULL;
+	}
+
+	return wire.position;
+}
+
+static int rdata_set_tsig_error(knot_rrset_t *tsig, uint16_t tsig_error)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_ERROR_O, sizeof(uint16_t));
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	knot_wire_write_u16(rd, tsig_error);
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_create_rdata(knot_rrset_t *rr, const knot_dname_t *alg,
+                           uint16_t maclen, uint16_t tsig_err)
+{
+	if (rr == NULL || alg == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t alg_len = knot_dname_size(alg);
+	size_t rdlen = alg_len + TSIG_FIXED_RDLEN + maclen;
+	if (tsig_err == KNOT_RCODE_BADTIME) {
+		rdlen += TSIG_OTHER_MAXLEN;
+	}
+	uint8_t rd[rdlen];
+	memset(rd, 0, rdlen);
+
+	/* Copy alg name. */
+	knot_dname_to_wire(rd, alg, rdlen);
+
+	/* Set MAC variable length in advance. */
+	size_t offset = alg_len + TSIG_OFF_MACLEN;
+	knot_wire_write_u16(rd + offset, maclen);
+
+	int ret = knot_rrset_add_rdata(rr, rd, rdlen, NULL);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Set error. */
+	rdata_set_tsig_error(rr, tsig_err);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_rdata_set_time_signed(knot_rrset_t *tsig, uint64_t time)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_TSIGNED_O, 3*sizeof(uint16_t));
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	knot_wire_write_u48(rd, time);
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_rdata_set_fudge(knot_rrset_t *tsig, uint16_t fudge)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_FUDGE_O, sizeof(uint16_t));
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	knot_wire_write_u16(rd, fudge);
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_rdata_set_mac(knot_rrset_t *tsig, uint16_t length, const uint8_t *mac)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_MAC_O, length);
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	/*! \note Cannot change length, as rdata is already preallocd. */
+
+	/* Copy the actual MAC. */
+	memcpy(rd, mac, length);
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_rdata_set_orig_id(knot_rrset_t *tsig, uint16_t id)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_ORIGID_O, sizeof(uint16_t));
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	/* Write the length - 2. */
+	knot_wire_write_u16(rd, id);
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_rdata_set_other_data(knot_rrset_t *tsig, uint16_t len,
+                                   const uint8_t *other_data)
+{
+	if (len > TSIG_OTHER_MAXLEN) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t *rd = rdata_seek(tsig, TSIG_OLEN_O, len + sizeof(uint16_t));
+	if (!rd) {
+		return KNOT_ERROR;
+	}
+
+	/* Write the length. */
+	knot_wire_write_u16(rd, len);
+
+	/* Copy the actual data. */
+	if (len > 0) {
+		memcpy(rd + sizeof(uint16_t), other_data, len);
+	}
+	return KNOT_EOK;
+}
+
+_public_
+const knot_dname_t *knot_tsig_rdata_alg_name(const knot_rrset_t *tsig)
+{
+	return knot_rdataset_at(&tsig->rrs, 0)->data;
+}
+
+_public_
+dnssec_tsig_algorithm_t knot_tsig_rdata_alg(const knot_rrset_t *tsig)
+{
+	/* Get the algorithm name. */
+	const knot_dname_t *alg_name = knot_tsig_rdata_alg_name(tsig);
+	if (!alg_name) {
+		return DNSSEC_TSIG_UNKNOWN;
+	}
+
+	return dnssec_tsig_algorithm_from_dname(alg_name);
+}
+
+_public_
+uint64_t knot_tsig_rdata_time_signed(const knot_rrset_t *tsig)
+{
+	/*! \todo How to return invalid value? */
+	uint8_t *rd = rdata_seek(tsig, TSIG_TSIGNED_O, 3*sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u48(rd);
+}
+
+_public_
+uint16_t knot_tsig_rdata_fudge(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_FUDGE_O, sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u16(rd);
+}
+
+_public_
+const uint8_t *knot_tsig_rdata_mac(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_MAC_O, 0);
+	if (!rd) {
+		return NULL;
+	}
+	return rd;
+}
+
+_public_
+size_t knot_tsig_rdata_mac_length(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_MACLEN_O, sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u16(rd);
+}
+
+_public_
+uint16_t knot_tsig_rdata_orig_id(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_ORIGID_O, sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u16(rd);
+}
+
+_public_
+uint16_t knot_tsig_rdata_error(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_ERROR_O, sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u16(rd);
+}
+
+_public_
+const uint8_t *knot_tsig_rdata_other_data(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_OTHER_O, 0);
+	if (!rd) {
+		return NULL;
+	}
+	return rd;
+}
+
+_public_
+uint16_t knot_tsig_rdata_other_data_length(const knot_rrset_t *tsig)
+{
+	uint8_t *rd = rdata_seek(tsig, TSIG_OLEN_O, sizeof(uint16_t));
+	if (!rd) {
+		return 0;
+	}
+	return knot_wire_read_u16(rd);
+}
+
+_public_
+size_t knot_tsig_rdata_tsig_variables_length(const knot_rrset_t *tsig)
+{
+	if (tsig == NULL) {
+		return 0;
+	}
+	/* Key name, Algorithm name and Other data have variable lengths. */
+	const knot_dname_t *key_name = tsig->owner;
+	if (!key_name) {
+		return 0;
+	}
+
+	const knot_dname_t *alg_name = knot_tsig_rdata_alg_name(tsig);
+	if (!alg_name) {
+		return 0;
+	}
+
+	uint16_t other_data_length = knot_tsig_rdata_other_data_length(tsig);
+
+	return knot_dname_size(key_name) + knot_dname_size(alg_name) +
+	       other_data_length + KNOT_TSIG_VARIABLES_LENGTH;
+}
+
+_public_
+size_t knot_tsig_rdata_tsig_timers_length(void)
+{
+	/*! \todo Cleanup */
+	return KNOT_TSIG_TIMERS_LENGTH;
+}
+
+_public_
+size_t knot_tsig_wire_size(const knot_tsig_key_t *key)
+{
+	if (key == NULL || key->name == NULL) {
+		return 0;
+	}
+
+	return knot_dname_size(key->name) + TSIG_FIXED_RDLEN +
+	       sizeof(uint16_t) + /* TYPE */
+	       sizeof(uint16_t) + /* CLASS */
+	       sizeof(uint32_t) + /* TTL */
+	       sizeof(uint16_t) + /* RDATA length. */
+	       knot_dname_size(dnssec_tsig_algorithm_to_dname(key->algorithm)) +
+	       dnssec_tsig_algorithm_size(key->algorithm); /* MAC length. */
+}
+
+_public_
+size_t knot_tsig_wire_maxsize(const knot_tsig_key_t *key)
+{
+	size_t size = knot_tsig_wire_size(key);
+	if (size == 0) {
+		return 0;
+	}
+
+	/* In case of BADTIME other data. */
+	return size + TSIG_OTHER_MAXLEN;
+}
+
+_public_
+bool knot_tsig_rdata_is_ok(const knot_rrset_t *tsig)
+{
+	return (tsig != NULL
+	        && knot_rdataset_at(&tsig->rrs, 0) != NULL
+	        && rdata_seek(tsig, TSIG_OTHER_O, 0) != NULL
+	        && knot_tsig_rdata_alg_name(tsig) != NULL);
+}
diff --git a/src/libknot/rrtype/tsig.h b/src/libknot/rrtype/tsig.h
new file mode 100644
index 0000000..083a063
--- /dev/null
+++ b/src/libknot/rrtype/tsig.h
@@ -0,0 +1,122 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief TSIG manipulation.
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "libdnssec/binary.h"
+#include "libdnssec/tsig.h"
+#include "libknot/consts.h"
+#include "libknot/rrset.h"
+#include "libknot/tsig.h"
+
+enum tsig_consts {
+	KNOT_TSIG_ITEM_COUNT = 7,
+	KNOT_TSIG_VARIABLES_LENGTH = sizeof(uint16_t)	// class
+	                             + sizeof(uint32_t)	// ttl
+	                             + 6		// time signed
+	                             + sizeof(uint16_t)	// fudge
+	                             + sizeof(uint16_t)	// error
+	                             + sizeof(uint16_t),// other data length
+	KNOT_TSIG_TIMERS_LENGTH = sizeof(uint16_t)	//fudge
+	                          + 6			// time signed
+};
+
+/*!
+ * \brief Create TSIG RDATA.
+ *
+ * \param rr TSIG RR to contain created data.
+ * \param alg Algorithm name.
+ * \param maclen Algorithm MAC len (may be set to 0 for empty MAC).
+ * \param tsig_err TSIG error code.
+ *
+ * \retval KNOT_EINVAL
+ * \retval KNOT_EOK
+ */
+int knot_tsig_create_rdata(knot_rrset_t *rr, const knot_dname_t *alg,
+                      uint16_t maclen, uint16_t tsig_err);
+
+int knot_tsig_rdata_set_time_signed(knot_rrset_t *tsig, uint64_t time);
+
+int knot_tsig_rdata_store_current_time(knot_rrset_t *tsig);
+
+int knot_tsig_rdata_set_fudge(knot_rrset_t *tsig, uint16_t fudge);
+
+int knot_tsig_rdata_set_mac(knot_rrset_t *tsig, uint16_t length, const uint8_t *mac);
+
+int knot_tsig_rdata_set_orig_id(knot_rrset_t *tsig, uint16_t id);
+
+int knot_tsig_rdata_set_other_data(knot_rrset_t *tsig, uint16_t length,
+                              const uint8_t *other_data);
+
+const knot_dname_t *knot_tsig_rdata_alg_name(const knot_rrset_t *tsig);
+
+dnssec_tsig_algorithm_t knot_tsig_rdata_alg(const knot_rrset_t *tsig);
+
+uint64_t knot_tsig_rdata_time_signed(const knot_rrset_t *tsig);
+
+uint16_t knot_tsig_rdata_fudge(const knot_rrset_t *tsig);
+
+const uint8_t *knot_tsig_rdata_mac(const knot_rrset_t *tsig);
+
+size_t knot_tsig_rdata_mac_length(const knot_rrset_t *tsig);
+
+uint16_t knot_tsig_rdata_orig_id(const knot_rrset_t *tsig);
+
+uint16_t knot_tsig_rdata_error(const knot_rrset_t *tsig);
+
+const uint8_t *knot_tsig_rdata_other_data(const knot_rrset_t *tsig);
+
+uint16_t knot_tsig_rdata_other_data_length(const knot_rrset_t *tsig);
+
+size_t knot_tsig_rdata_tsig_variables_length(const knot_rrset_t *tsig);
+
+size_t knot_tsig_rdata_tsig_timers_length(void);
+
+/*!
+ * \brief Return standard TSIG RRSET wire size for given algorithm.
+ *
+ * \param key Signing key descriptor.
+ *
+ * \return RRSET wire size.
+ */
+size_t knot_tsig_wire_size(const knot_tsig_key_t *key);
+
+/*!
+ * \brief Return TSIG RRSET maximum wire size for given algorithm.
+ *
+ * This size is reached if error reply with BADTIME.
+ *
+ * \param key Signing key descriptor.
+ *
+ * \return RRSET wire size.
+ */
+size_t knot_tsig_wire_maxsize(const knot_tsig_key_t *key);
+
+/*! \todo Documentation. */
+bool knot_tsig_rdata_is_ok(const knot_rrset_t *tsig);
+
+/*! @} */
diff --git a/src/libknot/rrtype/zonemd.h b/src/libknot/rrtype/zonemd.h
new file mode 100644
index 0000000..a4d734b
--- /dev/null
+++ b/src/libknot/rrtype/zonemd.h
@@ -0,0 +1,71 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \addtogroup rrtype
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/rdata.h"
+#include "libknot/wire.h"
+
+#define KNOT_ZONEMD_SCHEME_SIMPLE	1
+#define KNOT_ZONEMD_ALGORITHM_SHA384	1
+#define KNOT_ZONEMD_ALGORITHM_SHA512	2
+
+static inline
+uint32_t knot_zonemd_soa_serial(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return knot_wire_read_u32(rdata->data);
+}
+
+static inline
+uint8_t knot_zonemd_scheme(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 4);
+}
+
+static inline
+uint8_t knot_zonemd_algorithm(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return *(rdata->data + 5);
+}
+
+static inline
+size_t knot_zonemd_digest_size(const knot_rdata_t *rdata)
+{
+	switch (knot_zonemd_algorithm(rdata)) {
+	case KNOT_ZONEMD_ALGORITHM_SHA384: return 48;
+	case KNOT_ZONEMD_ALGORITHM_SHA512: return 64;
+	default: return 0;
+	}
+}
+
+static inline
+const uint8_t *knot_zonemd_digest(const knot_rdata_t *rdata)
+{
+	assert(rdata);
+	return rdata->data + 6;
+}
+
+/*! @} */
diff --git a/src/libknot/tsig-op.c b/src/libknot/tsig-op.c
new file mode 100644
index 0000000..7913859
--- /dev/null
+++ b/src/libknot/tsig-op.c
@@ -0,0 +1,683 @@
+/*  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/>.
+ */
+
+#include <assert.h>
+#include <inttypes.h>
+#include <time.h>
+#include <stdint.h>
+
+#include "libdnssec/error.h"
+#include "libdnssec/tsig.h"
+#include "libknot/attribute.h"
+#include "libknot/tsig-op.h"
+#include "libknot/errcode.h"
+#include "libknot/descriptor.h"
+#include "libknot/rrtype/tsig.h"
+#include "libknot/packet/wire.h"
+#include "libknot/consts.h"
+#include "libknot/packet/rrset-wire.h"
+#include "libknot/wire.h"
+#include "contrib/string.h"
+
+const int KNOT_TSIG_MAX_DIGEST_SIZE = 64;    // size of HMAC-SHA512 digest
+const uint16_t KNOT_TSIG_FUDGE_DEFAULT = 300;  // default Fudge value
+
+static int check_algorithm(const knot_rrset_t *tsig_rr)
+{
+	if (tsig_rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	const knot_dname_t *alg_name = knot_tsig_rdata_alg_name(tsig_rr);
+	if (!alg_name) {
+		return KNOT_EMALF;
+	}
+
+	dnssec_tsig_algorithm_t alg = dnssec_tsig_algorithm_from_dname(alg_name);
+	if (alg == DNSSEC_TSIG_UNKNOWN) {
+		return KNOT_TSIG_EBADKEY;
+	}
+
+	return KNOT_EOK;
+}
+
+static int check_key(const knot_rrset_t *tsig_rr, const knot_tsig_key_t *tsig_key)
+{
+	if (tsig_rr == NULL || tsig_key == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	const knot_dname_t *tsig_name = tsig_rr->owner;
+	if (!tsig_name) {
+		return KNOT_EMALF;
+	}
+
+	if (!knot_dname_is_equal(tsig_name, tsig_key->name)) {
+		return KNOT_TSIG_EBADKEY;
+	}
+
+	return KNOT_EOK;
+}
+
+static int compute_digest(const uint8_t *wire, size_t wire_len,
+                          uint8_t *digest, size_t *digest_len,
+                          const knot_tsig_key_t *key)
+{
+	if (!wire || !digest || !digest_len || !key) {
+		return KNOT_EINVAL;
+	}
+
+	if (!key->name) {
+		return KNOT_EMALF;
+	}
+
+	dnssec_tsig_ctx_t *ctx = NULL;
+	int result = dnssec_tsig_new(&ctx, key->algorithm, &key->secret);
+	if (result != DNSSEC_EOK) {
+		return KNOT_TSIG_EBADSIG;
+	}
+
+	dnssec_binary_t cover = { .data = (uint8_t *)wire, .size = wire_len };
+	dnssec_tsig_add(ctx, &cover);
+
+	*digest_len = dnssec_tsig_size(ctx);
+	dnssec_tsig_write(ctx, digest);
+	dnssec_tsig_free(ctx);
+
+	return KNOT_EOK;
+}
+
+static int check_time_signed(const knot_rrset_t *tsig_rr, uint64_t prev_time_signed)
+{
+	if (!tsig_rr) {
+		return KNOT_EINVAL;
+	}
+
+	/* Get the time signed and fudge values. */
+	uint64_t time_signed = knot_tsig_rdata_time_signed(tsig_rr);
+	if (time_signed == 0) {
+		return KNOT_TSIG_EBADTIME;
+	}
+	uint16_t fudge = knot_tsig_rdata_fudge(tsig_rr);
+	if (fudge == 0) {
+		return KNOT_TSIG_EBADTIME;
+	}
+
+	/* Get the current time. */
+	time_t curr_time = time(NULL);
+
+	/*!< \todo bleeding eyes. */
+	double diff = difftime(curr_time, (time_t)time_signed);
+
+	if (diff > fudge || diff < -fudge) {
+		return KNOT_TSIG_EBADTIME;
+	}
+
+	diff = difftime((time_t)time_signed, prev_time_signed);
+
+	if (diff < 0) {
+		return KNOT_TSIG_EBADTIME;
+	}
+
+	return KNOT_EOK;
+}
+
+static int write_tsig_variables(uint8_t *wire, const knot_rrset_t *tsig_rr)
+{
+	if (wire == NULL || tsig_rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Copy TSIG variables - starting with key name. */
+	const knot_dname_t *tsig_owner = tsig_rr->owner;
+	if (!tsig_owner) {
+		return KNOT_EINVAL;
+	}
+
+	int offset = 0;
+
+	offset += knot_dname_to_wire(wire + offset, tsig_owner, KNOT_DNAME_MAXLEN);
+
+	/*!< \todo which order? */
+
+	/* Copy class. */
+	knot_wire_write_u16(wire + offset, tsig_rr->rclass);
+	offset += sizeof(uint16_t);
+
+	/* Copy TTL - always 0. */
+	knot_wire_write_u32(wire + offset, tsig_rr->ttl);
+	offset += sizeof(uint32_t);
+
+	/* Copy alg name. */
+	const knot_dname_t *alg_name = knot_tsig_rdata_alg_name(tsig_rr);
+	if (!alg_name) {
+		return KNOT_EINVAL;
+	}
+
+	/* Te algorithm name must be in canonical form, i.e. in lowercase. */
+	uint8_t *alg_name_wire = wire + offset;
+	offset += knot_dname_to_wire(alg_name_wire, alg_name, KNOT_DNAME_MAXLEN);
+	knot_dname_to_lower(alg_name_wire);
+
+	/* Following data are written in network order. */
+	/* Time signed. */
+	knot_wire_write_u48(wire + offset, knot_tsig_rdata_time_signed(tsig_rr));
+	offset += 6;
+	/* Fudge. */
+	knot_wire_write_u16(wire + offset, knot_tsig_rdata_fudge(tsig_rr));
+	offset += sizeof(uint16_t);
+	/* TSIG error. */
+	knot_wire_write_u16(wire + offset, knot_tsig_rdata_error(tsig_rr));
+	offset += sizeof(uint16_t);
+	/* Get other data length. */
+	uint16_t other_data_length = knot_tsig_rdata_other_data_length(tsig_rr);
+	/* Get other data. */
+	const uint8_t *other_data = knot_tsig_rdata_other_data(tsig_rr);
+	if (!other_data) {
+		return KNOT_EINVAL;
+	}
+
+	/*
+	 * We cannot write the whole other_data, as it contains its length in
+	 * machine order.
+	 */
+	knot_wire_write_u16(wire + offset, other_data_length);
+	offset += sizeof(uint16_t);
+
+	/* Skip the length. */
+	memcpy(wire + offset, other_data, other_data_length);
+
+	return KNOT_EOK;
+}
+
+static int wire_write_timers(uint8_t *wire, const knot_rrset_t *tsig_rr)
+{
+	if (wire == NULL || tsig_rr == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	//write time signed
+	knot_wire_write_u48(wire, knot_tsig_rdata_time_signed(tsig_rr));
+	//write fudge
+	knot_wire_write_u16(wire + 6, knot_tsig_rdata_fudge(tsig_rr));
+
+	return KNOT_EOK;
+}
+
+static int create_sign_wire(const uint8_t *msg, size_t msg_len,
+                            const uint8_t *request_mac, size_t request_mac_len,
+                            uint8_t *digest, size_t *digest_len,
+                            const knot_rrset_t *tmp_tsig,
+                            const knot_tsig_key_t *key)
+{
+	if (!msg || !key || digest_len == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Create tmp TSIG. */
+	int ret = KNOT_EOK;
+
+	/*
+	 * Create tmp wire, it should contain message
+	 * plus request mac plus tsig variables.
+	 */
+	size_t wire_len = msg_len + request_mac_len + (request_mac_len > 0 ? 2 : 0) +
+	                  knot_tsig_rdata_tsig_variables_length(tmp_tsig);
+	uint8_t *wire = malloc(wire_len);
+	if (!wire) {
+		return KNOT_ENOMEM;
+	}
+
+	memset(wire, 0, wire_len);
+
+	uint8_t *pos = wire;
+
+	/* Copy the request MAC - should work even if NULL. */
+	if (request_mac_len > 0) {
+		knot_wire_write_u16(pos, request_mac_len);
+		pos += 2;
+		memcpy(pos, request_mac, request_mac_len);
+	}
+	pos += request_mac_len;
+	/* Copy the original message. */
+	memcpy(pos, msg, msg_len);
+	pos += msg_len;
+	/* Copy TSIG variables. */
+	ret = write_tsig_variables(pos, tmp_tsig);
+	if (ret != KNOT_EOK) {
+		free(wire);
+		return ret;
+	}
+
+	/* Compute digest. */
+	ret = compute_digest(wire, wire_len, digest, digest_len, key);
+	if (ret != KNOT_EOK) {
+		*digest_len = 0;
+		free(wire);
+		return ret;
+	}
+
+	free(wire);
+
+	return KNOT_EOK;
+}
+
+static int create_sign_wire_next(const uint8_t *msg, size_t msg_len,
+                                 const uint8_t *prev_mac, size_t prev_mac_len,
+                                 uint8_t *digest, size_t *digest_len,
+                                 const knot_rrset_t *tmp_tsig,
+                                 const knot_tsig_key_t *key)
+{
+	if (!msg || !key || digest_len == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Create tmp TSIG. */
+	int ret = KNOT_EOK;
+
+	/*
+	 * Create tmp wire, it should contain message
+	 * plus request mac plus tsig variables.
+	 */
+	size_t wire_len = msg_len + prev_mac_len + knot_tsig_rdata_tsig_timers_length() + 2;
+	uint8_t *wire = malloc(wire_len);
+	if (!wire) {
+		return KNOT_ENOMEM;
+	}
+
+	memset(wire, 0, wire_len);
+
+	/* Copy the request MAC - should work even if NULL. */
+	knot_wire_write_u16(wire, prev_mac_len);
+	memcpy(wire + 2, prev_mac, prev_mac_len);
+	/* Copy the original message. */
+	memcpy(wire + prev_mac_len + 2, msg, msg_len);
+	/* Copy TSIG variables. */
+
+	ret = wire_write_timers(wire + prev_mac_len + msg_len + 2, tmp_tsig);
+	if (ret != KNOT_EOK) {
+		free(wire);
+		return ret;
+	}
+
+	/* Compute digest. */
+	ret = compute_digest(wire, wire_len, digest, digest_len, key);
+	if (ret != KNOT_EOK) {
+		*digest_len = 0;
+		free(wire);
+		return ret;
+	}
+
+	free(wire);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_sign(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                   const uint8_t *request_mac, size_t request_mac_len,
+                   uint8_t *digest, size_t *digest_len,
+                   const knot_tsig_key_t *key, uint16_t tsig_rcode,
+                   uint64_t request_time_signed)
+{
+	if (!msg || !msg_len || !key || digest == NULL || digest_len == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_rrset_t *tmp_tsig = knot_rrset_new(key->name, KNOT_RRTYPE_TSIG,
+	                                        KNOT_CLASS_ANY, 0, NULL);
+	if (!tmp_tsig) {
+		return KNOT_ENOMEM;
+	}
+
+	/* Create rdata for TSIG RR. */
+	uint16_t rdata_rcode = KNOT_RCODE_NOERROR;
+	if (tsig_rcode == KNOT_RCODE_BADTIME) {
+		rdata_rcode = tsig_rcode;
+	}
+
+	const uint8_t *alg_name = dnssec_tsig_algorithm_to_dname(key->algorithm);
+	size_t alg_size = dnssec_tsig_algorithm_size(key->algorithm);
+	knot_tsig_create_rdata(tmp_tsig, alg_name, alg_size, rdata_rcode);
+
+	/* Distinguish BADTIME response. */
+	if (tsig_rcode == KNOT_RCODE_BADTIME) {
+		/* Set client's time signed into the time signed field. */
+		knot_tsig_rdata_set_time_signed(tmp_tsig, request_time_signed);
+
+		/* Store current time into Other data. */
+		uint8_t time_signed[6];
+		time_t now = time(NULL);
+		knot_wire_write_u48(time_signed, now);
+
+		knot_tsig_rdata_set_other_data(tmp_tsig, 6, time_signed);
+	} else {
+		knot_tsig_rdata_set_time_signed(tmp_tsig, time(NULL));
+
+		/* Set other len. */
+		knot_tsig_rdata_set_other_data(tmp_tsig, 0, 0);
+	}
+
+	knot_tsig_rdata_set_fudge(tmp_tsig, KNOT_TSIG_FUDGE_DEFAULT);
+
+	/* Set original ID */
+	knot_tsig_rdata_set_orig_id(tmp_tsig, knot_wire_get_id(msg));
+
+	uint8_t digest_tmp[KNOT_TSIG_MAX_DIGEST_SIZE];
+	size_t digest_tmp_len = 0;
+
+	int ret = create_sign_wire(msg, *msg_len, /*msg_max_len,*/
+	                           request_mac, request_mac_len,
+	                           digest_tmp, &digest_tmp_len, tmp_tsig, key);
+	if (ret != KNOT_EOK) {
+		knot_rrset_free(tmp_tsig, NULL);
+		return ret;
+	}
+
+	/* Set the digest. */
+	knot_tsig_rdata_set_mac(tmp_tsig, digest_tmp_len, digest_tmp);
+
+	/* Write RRSet to wire */
+	ret = knot_rrset_to_wire(tmp_tsig, msg + *msg_len,
+	                         msg_max_len - *msg_len, NULL);
+	if (ret < 0) {
+		*digest_len = 0;
+		knot_rrset_free(tmp_tsig, NULL);
+		return ret;
+	}
+
+	size_t tsig_wire_len = ret;
+
+	knot_rrset_free(tmp_tsig, NULL);
+
+	*msg_len += tsig_wire_len;
+
+	uint16_t arcount = knot_wire_get_arcount(msg);
+	knot_wire_set_arcount(msg, ++arcount);
+
+	/* everything went ok, save the digest to the output parameter */
+	memcpy(digest, digest_tmp, digest_tmp_len);
+	*digest_len = digest_tmp_len;
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_sign_next(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                        const uint8_t *prev_digest, size_t prev_digest_len,
+                        uint8_t *digest, size_t *digest_len,
+                        const knot_tsig_key_t *key, uint8_t *to_sign,
+                        size_t to_sign_len)
+{
+	if (!msg || !msg_len || !key || !digest || !digest_len) {
+		return KNOT_EINVAL;
+	}
+
+	uint8_t digest_tmp[KNOT_TSIG_MAX_DIGEST_SIZE];
+	size_t digest_tmp_len = 0;
+	knot_rrset_t *tmp_tsig = knot_rrset_new(key->name, KNOT_RRTYPE_TSIG,
+	                                        KNOT_CLASS_ANY, 0, NULL);
+	if (!tmp_tsig) {
+		return KNOT_ENOMEM;
+	}
+
+	/* Create rdata for TSIG RR. */
+	const uint8_t *alg_name = dnssec_tsig_algorithm_to_dname(key->algorithm);
+	size_t alg_size = dnssec_tsig_algorithm_size(key->algorithm);
+	knot_tsig_create_rdata(tmp_tsig, alg_name, alg_size, 0);
+	knot_tsig_rdata_set_time_signed(tmp_tsig, time(NULL));
+	knot_tsig_rdata_set_fudge(tmp_tsig, KNOT_TSIG_FUDGE_DEFAULT);
+
+	/* Create wire to be signed. */
+	size_t wire_len = prev_digest_len + to_sign_len + KNOT_TSIG_TIMERS_LENGTH + 2;
+	uint8_t *wire = malloc(wire_len);
+	if (!wire) {
+		knot_rrset_free(tmp_tsig, NULL);
+		return KNOT_ENOMEM;
+	}
+	memset(wire, 0, wire_len);
+
+	/* Write previous digest length. */
+	knot_wire_write_u16(wire, prev_digest_len);
+	/* Write previous digest. */
+	memcpy(wire + 2, prev_digest, prev_digest_len);
+	/* Write original message. */
+	memcpy(wire + prev_digest_len + 2, to_sign, to_sign_len);
+	/* Write timers. */
+	wire_write_timers(wire + prev_digest_len + to_sign_len + 2, tmp_tsig);
+
+	int ret = compute_digest(wire, wire_len, digest_tmp, &digest_tmp_len, key);
+	free(wire);
+	if (ret != KNOT_EOK) {
+		knot_rrset_free(tmp_tsig, NULL);
+		*digest_len = 0;
+		return ret;
+	}
+
+	if (digest_tmp_len > *digest_len) {
+		knot_rrset_free(tmp_tsig, NULL);
+		*digest_len = 0;
+		return KNOT_ESPACE;
+	}
+
+	/* Set the MAC. */
+	knot_tsig_rdata_set_mac(tmp_tsig, digest_tmp_len, digest_tmp);
+
+	/* Set original id. */
+	knot_tsig_rdata_set_orig_id(tmp_tsig, knot_wire_get_id(msg));
+
+	/* Set other data. */
+	knot_tsig_rdata_set_other_data(tmp_tsig, 0, NULL);
+
+	ret = knot_rrset_to_wire(tmp_tsig, msg + *msg_len,
+	                         msg_max_len - *msg_len, NULL);
+	if (ret < 0) {
+		knot_rrset_free(tmp_tsig, NULL);
+		*digest_len = 0;
+		return ret;
+	}
+
+	size_t tsig_wire_size = ret;
+
+	knot_rrset_free(tmp_tsig, NULL);
+
+	*msg_len += tsig_wire_size;
+	uint16_t arcount = knot_wire_get_arcount(msg);
+	knot_wire_set_arcount(msg, ++arcount);
+
+	memcpy(digest, digest_tmp, digest_tmp_len);
+	*digest_len = digest_tmp_len;
+
+	return KNOT_EOK;
+}
+
+static int check_digest(const knot_rrset_t *tsig_rr,
+                        const uint8_t *wire, size_t size,
+                        const uint8_t *request_mac, size_t request_mac_len,
+                        const knot_tsig_key_t *tsig_key,
+                        uint64_t prev_time_signed, int use_times)
+{
+	if (!wire || !tsig_key) {
+		return KNOT_EINVAL;
+	}
+
+	/* No TSIG record means verification failure. */
+	if (tsig_rr == NULL) {
+		return KNOT_TSIG_EBADKEY;
+	}
+
+	/* Check that libknot knows the algorithm. */
+	int ret = check_algorithm(tsig_rr);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Check that key is valid, ie. the same as given in args. */
+	ret = check_key(tsig_rr, tsig_key);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	uint8_t *wire_to_sign = malloc(size);
+	if (!wire_to_sign) {
+		return KNOT_ENOMEM;
+	}
+
+	memcpy(wire_to_sign, wire, size);
+
+	// restore message ID to which the signature had been created with
+	knot_wire_set_id(wire_to_sign, knot_tsig_rdata_orig_id(tsig_rr));
+
+	uint8_t digest_tmp[KNOT_TSIG_MAX_DIGEST_SIZE];
+	size_t digest_tmp_len = 0;
+	assert(tsig_rr->rrs.count > 0);
+
+	if (use_times) {
+		/* Wire is not a single packet, TSIG RRs must be stripped already. */
+		ret = create_sign_wire_next(wire_to_sign, size,
+		                            request_mac, request_mac_len,
+		                            digest_tmp, &digest_tmp_len,
+		                            tsig_rr, tsig_key);
+	} else {
+		ret = create_sign_wire(wire_to_sign, size,
+		                       request_mac, request_mac_len,
+		                       digest_tmp, &digest_tmp_len,
+		                       tsig_rr, tsig_key);
+	}
+
+	assert(tsig_rr->rrs.count > 0);
+	free(wire_to_sign);
+
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Compare MAC from TSIG RR RDATA with just computed digest. */
+
+	/*!< \todo move to function. */
+	const knot_dname_t *alg_name = knot_tsig_rdata_alg_name(tsig_rr);
+	dnssec_tsig_algorithm_t alg = dnssec_tsig_algorithm_from_dname(alg_name);
+
+	/*! \todo [TSIG] TRUNCATION */
+	uint16_t mac_length = knot_tsig_rdata_mac_length(tsig_rr);
+	const uint8_t *tsig_mac = knot_tsig_rdata_mac(tsig_rr);
+
+	if (mac_length != dnssec_tsig_algorithm_size(alg)) {
+		return KNOT_TSIG_EBADSIG;
+	}
+
+	if (const_time_memcmp(tsig_mac, digest_tmp, mac_length) != 0) {
+		return KNOT_TSIG_EBADSIG;
+	}
+
+	/* Check TSIG validity period, must be after the signature check! */
+	ret = check_time_signed(tsig_rr, prev_time_signed);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_server_check(const knot_rrset_t *tsig_rr,
+                           const uint8_t *wire, size_t size,
+                           const knot_tsig_key_t *tsig_key)
+{
+	return check_digest(tsig_rr, wire, size, NULL, 0, tsig_key, 0, 0);
+}
+
+_public_
+int knot_tsig_client_check(const knot_rrset_t *tsig_rr,
+                           const uint8_t *wire, size_t size,
+                           const uint8_t *request_mac, size_t request_mac_len,
+                           const knot_tsig_key_t *tsig_key,
+                           uint64_t prev_time_signed)
+{
+	return check_digest(tsig_rr, wire, size, request_mac, request_mac_len,
+	                    tsig_key, prev_time_signed, 0);
+}
+
+_public_
+int knot_tsig_client_check_next(const knot_rrset_t *tsig_rr,
+                                const uint8_t *wire, size_t size,
+                                const uint8_t *prev_digest,
+                                size_t prev_digest_len,
+                                const knot_tsig_key_t *tsig_key,
+                                uint64_t prev_time_signed)
+{
+	return check_digest(tsig_rr, wire, size, prev_digest,
+	                    prev_digest_len, tsig_key, prev_time_signed, 1);
+}
+
+_public_
+int knot_tsig_add(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                  uint16_t tsig_rcode, const knot_rrset_t *tsig_rr)
+{
+	/*! \todo Revise!! */
+
+	if (!msg || !msg_len || !tsig_rr) {
+		return KNOT_EINVAL;
+	}
+
+	/*! \todo What key to use, when we do not sign? Does this even work? */
+	knot_rrset_t *tmp_tsig = knot_rrset_new(tsig_rr->owner, KNOT_RRTYPE_TSIG,
+		                                KNOT_CLASS_ANY, 0, NULL);
+	if (!tmp_tsig) {
+		return KNOT_ENOMEM;
+	}
+
+	assert(tsig_rcode != KNOT_RCODE_BADTIME);
+	knot_tsig_create_rdata(tmp_tsig, knot_tsig_rdata_alg_name(tsig_rr), 0, tsig_rcode);
+	knot_tsig_rdata_set_time_signed(tmp_tsig, knot_tsig_rdata_time_signed(tsig_rr));
+
+	/* Comparing to BIND it was found out that the Fudge should always be
+	 * set to the server's value.
+	 */
+	knot_tsig_rdata_set_fudge(tmp_tsig, KNOT_TSIG_FUDGE_DEFAULT);
+
+	/* Set original ID */
+	knot_tsig_rdata_set_orig_id(tmp_tsig, knot_wire_get_id(msg));
+
+	/* Set other len. */
+	knot_tsig_rdata_set_other_data(tmp_tsig, 0, 0);
+
+	/* Append TSIG RR. */
+	int ret = knot_tsig_append(msg, msg_len, msg_max_len, tmp_tsig);
+
+	/* key_name already referenced in RRSet, no need to free separately. */
+	knot_rrset_free(tmp_tsig, NULL);
+
+	return ret;
+}
+
+_public_
+int knot_tsig_append(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                     const knot_rrset_t *tsig_rr)
+{
+	/* Write RRSet to wire */
+	int ret = knot_rrset_to_wire(tsig_rr, msg + *msg_len,
+	                             msg_max_len - *msg_len, NULL);
+	if (ret < 0) {
+		return ret;
+	}
+
+	*msg_len += ret;
+
+	knot_wire_set_arcount(msg, knot_wire_get_arcount(msg) + 1);
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/tsig-op.h b/src/libknot/tsig-op.h
new file mode 100644
index 0000000..03e744d
--- /dev/null
+++ b/src/libknot/tsig-op.h
@@ -0,0 +1,187 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief TSIG signing and validating.
+ *
+ * \addtogroup knot-tsig
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+
+#include "libknot/rrtype/tsig.h"
+#include "libknot/rrset.h"
+
+/*!
+ * \brief Generate TSIG signature of a message.
+ *
+ * This function generates TSIG digest of the given message prepended with the
+ * given Request MAC (if any) and appended with TSIG Variables. It also appends
+ * the resulting TSIG RR to the message wire format and accordingly adjusts
+ * the message size.
+ *
+ * \note This function does not save the new digest to the 'digest' parameter
+ *       unless everything went OK. This allows sending the same buffer to
+ *       the 'request_mac' and 'digest' parameters.
+ *
+ * \param msg Message to be signed.
+ * \param msg_len Size of the message in bytes.
+ * \param msg_max_len Maximum size of the message in bytes.
+ * \param request_mac Request MAC. (may be NULL).
+ * \param request_mac_len Size of the request MAC in bytes.
+ * \param digest Buffer to save the digest in.
+ * \param digest_len In: size of the buffer. Out: real size of the digest saved.
+ * \param key TSIG used for signing.
+ * \param tsig_rcode RCODE of the TSIG.
+ * \param request_time_signed Clients time signed.
+ *
+ * \retval KNOT_EOK if everything went OK.
+ * \retval TODO
+ *
+ * \todo This function should return TSIG errors by their codes which are
+ *       positive values - this will be recognized by the caller.
+ */
+int knot_tsig_sign(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                   const uint8_t *request_mac, size_t request_mac_len,
+                   uint8_t *digest, size_t *digest_len,
+                   const knot_tsig_key_t *key, uint16_t tsig_rcode,
+                   uint64_t request_time_signed);
+
+/*!
+ * \brief Generate TSIG signature of a 2nd or later message in a TCP session.
+ *
+ * This function generates TSIG digest of the given message prepended with the
+ * given Request MAC (if any) and appended with TSIG Variables. It also appends
+ * the resulting TSIG RR to the message wire format and accordingly adjusts
+ * the message size.
+ *
+ * \note This function does not save the new digest to the 'digest' parameter
+ *       unless everything went OK. This allows sending the same buffer to
+ *       the 'request_mac' and 'digest' parameters.
+ *
+ * \param msg Message to be signed.
+ * \param msg_len Size of the message in bytes.
+ * \param msg_max_len Maximum size of the message in bytes.
+ * \param prev_digest Previous digest sent by the server in the session.
+ * \param prev_digest_len Size of the previous digest in bytes.
+ * \param digest Buffer to save the digest in.
+ * \param digest_len In: size of the buffer. Out: real size of the digest saved.
+ * \param key TSIG key for signing.
+ * \param to_sign Data being signed.
+ * \param to_sign_len Size of the data being signed.
+ *
+ * \retval KNOT_EOK if successful.
+ * \retval TODO
+ *
+ * \todo This function should return TSIG errors by their codes which are
+ *       positive values - this will be recognized by the caller.
+ */
+int knot_tsig_sign_next(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                        const uint8_t *prev_digest, size_t prev_digest_len,
+                        uint8_t *digest, size_t *digest_len,
+                        const knot_tsig_key_t *key, uint8_t *to_sign,
+                        size_t to_sign_len);
+
+/*!
+ * \brief Checks incoming request.
+ *
+ * \param tsig_rr TSIG extracted from the packet.
+ * \param wire Wire format of the packet (including the TSIG RR).
+ * \param size Size of the wire format of packet in bytes.
+ * \param tsig_key TSIG key.
+ *
+ * \retval KNOT_EOK If the signature is valid.
+ * \retval TODO
+ *
+ * \todo This function should return TSIG errors by their codes which are
+ *       positive values - this will be recognized by the caller.
+ */
+int knot_tsig_server_check(const knot_rrset_t *tsig_rr,
+                           const uint8_t *wire, size_t size,
+                           const knot_tsig_key_t *tsig_key);
+
+/*!
+ * \brief Checks incoming response.
+ *
+ * \param tsig_rr TSIG extracted from the packet.
+ * \param wire Wire format of the packet (including the TSIG RR).
+ * \param size Size of the wire format of packet in bytes.
+ * \param request_mac Request MAC. (may be NULL).
+ * \param request_mac_len Size of the request MAC in bytes.
+ * \param key TSIG key.
+ * \param prev_time_signed Time for TSIG period validity.
+ *
+ * \retval KNOT_EOK If the signature is valid.
+ * \retval TODO
+ *
+ * \todo This function should return TSIG errors by their codes which are
+ *       positive values - this will be recognized by the caller.
+ */
+int knot_tsig_client_check(const knot_rrset_t *tsig_rr,
+                           const uint8_t *wire, size_t size,
+                           const uint8_t *request_mac, size_t request_mac_len,
+                           const knot_tsig_key_t *key,
+                           uint64_t prev_time_signed);
+
+/*!
+ * \brief Checks signature of 2nd or next packet in a TCP session.
+ *
+ * \param tsig_rr TSIG extracted from the packet.
+ * \param wire Wire format of the packet (including the TSIG RR).
+ * \param size Size of the wire format of packet in bytes.
+ * \param prev_digest Previous digest sent by the server in the session.
+ * \param prev_digest_len Size of the previous digest in bytes.
+ * \param key TSIG key.
+ * \param prev_time_signed Time for TSIG period validity.
+ *
+ * \retval KNOT_EOK If the signature is valid.
+ * \retval TODO
+ *
+ * \todo This function should return TSIG errors by their codes which are
+ *       positive values - this will be recognized by the caller.
+ */
+int knot_tsig_client_check_next(const knot_rrset_t *tsig_rr,
+                                const uint8_t *wire, size_t size,
+                                const uint8_t *prev_digest,
+                                size_t prev_digest_len,
+                                const knot_tsig_key_t *key,
+                                uint64_t prev_time_signed);
+
+/*!
+ * \todo Documentation!
+ */
+int knot_tsig_add(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                  uint16_t tsig_rcode, const knot_rrset_t *tsig_rr);
+
+/*! \brief Append TSIG RR to message.
+ *  \todo Proper documentation.
+ */
+int knot_tsig_append(uint8_t *msg, size_t *msg_len, size_t msg_max_len,
+                     const knot_rrset_t *tsig_rr);
+
+/*! \brief Return true if the TSIG RCODE allows signing the packet.
+ *  \todo Proper documentation.
+ */
+static inline bool knot_tsig_can_sign(uint16_t tsig_rcode) {
+	return tsig_rcode == KNOT_RCODE_NOERROR || tsig_rcode == KNOT_RCODE_BADTIME;
+}
+
+/*! @} */
diff --git a/src/libknot/tsig.c b/src/libknot/tsig.c
new file mode 100644
index 0000000..35311a2
--- /dev/null
+++ b/src/libknot/tsig.c
@@ -0,0 +1,188 @@
+/*  Copyright (C) 2021 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 <string.h>
+
+#include "contrib/getline.h"
+#include "contrib/string.h"
+#include "libdnssec/error.h"
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+#include "libknot/tsig.h"
+
+_public_
+void knot_tsig_key_deinit(knot_tsig_key_t *key)
+{
+	if (!key) {
+		return;
+	}
+
+	knot_dname_free(key->name, NULL);
+
+	if (key->secret.data) {
+		memzero(key->secret.data, key->secret.size);
+	}
+	dnssec_binary_free(&key->secret);
+
+	memzero(key, sizeof(*key));
+}
+
+_public_
+int knot_tsig_key_init(knot_tsig_key_t *key, const char *algorithm_name,
+                       const char *name, const char *secret_b64)
+{
+	if (!name || !secret_b64 || !key) {
+		return KNOT_EINVAL;
+	}
+
+	dnssec_tsig_algorithm_t algorithm = DNSSEC_TSIG_HMAC_SHA256;
+	if (algorithm_name != NULL) {
+		algorithm = dnssec_tsig_algorithm_from_name(algorithm_name);
+		if (algorithm == DNSSEC_TSIG_UNKNOWN) {
+			return KNOT_EMALF;
+		}
+	}
+
+	knot_dname_t *dname = knot_dname_from_str_alloc(name);
+	if (!dname) {
+		return KNOT_ENOMEM;
+	}
+	knot_dname_to_lower(dname);
+
+	dnssec_binary_t b64secret = { 0 };
+	b64secret.data = (uint8_t *)secret_b64;
+	b64secret.size = strlen(secret_b64);
+
+	dnssec_binary_t secret = { 0 };
+	int result = dnssec_binary_from_base64(&b64secret, &secret);
+	if (result != KNOT_EOK) {
+		knot_dname_free(dname, NULL);
+		return result;
+	}
+
+	key->name = dname;
+	key->algorithm = algorithm;
+	key->secret = secret;
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tsig_key_init_str(knot_tsig_key_t *key, const char *params)
+{
+	if (!params) {
+		return KNOT_EINVAL;
+	}
+
+	char *copy = strstrip(params);
+	if (!copy) {
+		return KNOT_ENOMEM;
+	}
+
+	size_t copy_size = strlen(copy) + 1;
+
+	// format [algorithm:]name:secret
+
+	char *algorithm = NULL;
+	char *name = NULL;
+	char *secret = NULL;
+
+	// find secret
+
+	char *pos = strrchr(copy, ':');
+	if (pos) {
+		*pos = '\0';
+		secret = pos + 1;
+	} else {
+		memzero(copy, copy_size);
+		free(copy);
+		return KNOT_EMALF;
+	}
+
+	// find name and optionally algorithm
+
+	pos = strchr(copy, ':');
+	if (pos) {
+		*pos = '\0';
+		algorithm = copy;
+		name = pos + 1;
+	} else {
+		name = copy;
+	}
+
+	int result = knot_tsig_key_init(key, algorithm, name, secret);
+
+	memzero(copy, copy_size);
+	free(copy);
+
+	return result;
+}
+
+_public_
+int knot_tsig_key_init_file(knot_tsig_key_t *key, const char *filename)
+{
+	if (!filename) {
+		return KNOT_EINVAL;
+	}
+
+	FILE *file = fopen(filename, "r");
+	if (!file) {
+		return KNOT_EACCES;
+	}
+
+	char *line = NULL;
+	size_t line_size = 0;
+	ssize_t read = knot_getline(&line, &line_size, file);
+
+	fclose(file);
+
+	if (read == -1) {
+		return KNOT_EMALF;
+	}
+
+	int result = knot_tsig_key_init_str(key, line);
+
+	memzero(line, line_size);
+	free(line);
+
+	return result;
+}
+
+_public_
+int knot_tsig_key_copy(knot_tsig_key_t *dst, const knot_tsig_key_t *src)
+{
+	if (!src || !dst) {
+		return KNOT_EINVAL;
+	}
+
+	knot_tsig_key_t copy = { 0 };
+	copy.algorithm = src->algorithm;
+
+	copy.name = knot_dname_copy(src->name, NULL);
+	if (!copy.name) {
+		return KNOT_ENOMEM;
+	}
+
+	if (dnssec_binary_dup(&src->secret, &copy.secret) != DNSSEC_EOK) {
+		knot_tsig_key_deinit(&copy);
+		return KNOT_ENOMEM;
+	}
+
+	*dst = copy;
+
+	return KNOT_EOK;
+}
diff --git a/src/libknot/tsig.h b/src/libknot/tsig.h
new file mode 100644
index 0000000..abbdde2
--- /dev/null
+++ b/src/libknot/tsig.h
@@ -0,0 +1,89 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief TSIG operations
+ *
+ * \addtogroup knot-tsig
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/dname.h"
+#include "libdnssec/tsig.h"
+
+/*!
+ * \brief TSIG key.
+ */
+typedef struct {
+	dnssec_tsig_algorithm_t algorithm;
+	knot_dname_t *name;
+	dnssec_binary_t secret;
+} knot_tsig_key_t;
+
+/*!
+ * \brief Packet signing context.
+ */
+typedef struct {
+	knot_tsig_key_t tsig_key;
+	uint8_t *tsig_digest;
+	size_t tsig_digestlen;
+	uint64_t tsig_time_signed;
+	size_t pkt_count;
+} knot_sign_context_t;
+
+/*!
+ * \brief Initialize a new TSIG key from individual key parameters.
+ *
+ * \param[out] key         Key to be initialized.
+ * \param[in]  algorithm   Algorithm name. NULL for default (hmac-md5).
+ * \param[in]  name        Key name (domain name in presentation format).
+ * \param[in]  secret_b64  Secret encoded using Base 64.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int knot_tsig_key_init(knot_tsig_key_t *key, const char *algorithm,
+                       const char *name, const char *secret_b64);
+
+/*!
+ * \brief Create a new TSIG key from a string encoding all parameters.
+ *
+ * \param[out] key     Key to be initialized.
+ * \param[in]  params  Parameters in a form \a [algorithm:]name:base64_secret
+ */
+int knot_tsig_key_init_str(knot_tsig_key_t *key, const char *params);
+
+/*!
+ * \brief Create a new TSIG key by reading the parameters from a file.
+ *
+ * The file content is parsed by \a tsig_key_create_str.
+ */
+int knot_tsig_key_init_file(knot_tsig_key_t *key, const char *filename);
+
+/*!
+ * \brief Deinitialize TSIG key.
+ */
+void knot_tsig_key_deinit(knot_tsig_key_t *key);
+
+/*!
+ * \brief Duplicate a TSIG key.
+ */
+int knot_tsig_key_copy(knot_tsig_key_t *dst, const knot_tsig_key_t *src);
+
+/*! @} */
diff --git a/src/libknot/version.h b/src/libknot/version.h
new file mode 100644
index 0000000..49aee67
--- /dev/null
+++ b/src/libknot/version.h
@@ -0,0 +1,25 @@
+/*  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
+
+#define KNOT_VERSION_MAJOR 3
+#define KNOT_VERSION_MINOR 2
+#define KNOT_VERSION_PATCH 0x06
+
+#define KNOT_VERSION_HEX ((KNOT_VERSION_MAJOR << 16) | \
+                          (KNOT_VERSION_MINOR <<  8) | \
+                          (KNOT_VERSION_PATCH))
diff --git a/src/libknot/version.h.in b/src/libknot/version.h.in
new file mode 100644
index 0000000..37c02c6
--- /dev/null
+++ b/src/libknot/version.h.in
@@ -0,0 +1,25 @@
+/*  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
+
+#define KNOT_VERSION_MAJOR @KNOT_VERSION_MAJOR@
+#define KNOT_VERSION_MINOR @KNOT_VERSION_MINOR@
+#define KNOT_VERSION_PATCH 0x0@KNOT_VERSION_PATCH@
+
+#define KNOT_VERSION_HEX ((KNOT_VERSION_MAJOR << 16) | \
+                          (KNOT_VERSION_MINOR <<  8) | \
+                          (KNOT_VERSION_PATCH))
diff --git a/src/libknot/wire.h b/src/libknot/wire.h
new file mode 100644
index 0000000..2f264c7
--- /dev/null
+++ b/src/libknot/wire.h
@@ -0,0 +1,154 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Wire integer operations.
+ *
+ * \addtogroup wire
+ * @{
+ */
+
+#pragma once
+
+#include <assert.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "libknot/endian.h"
+
+/*!
+ * \brief Reads 2 bytes from the wireformat data.
+ *
+ * \param pos Data to read the 2 bytes from.
+ *
+ * \return The 2 bytes read, in host byte order.
+ */
+inline static uint16_t knot_wire_read_u16(const uint8_t *pos)
+{
+	assert(pos);
+	uint16_t result;
+	memcpy(&result, pos, sizeof(result));
+	return be16toh(result);
+}
+
+/*!
+ * \brief Reads 4 bytes from the wireformat data.
+ *
+ * \param pos Data to read the 4 bytes from.
+ *
+ * \return The 4 bytes read, in host byte order.
+ */
+inline static uint32_t knot_wire_read_u32(const uint8_t *pos)
+{
+	assert(pos);
+	uint32_t result;
+	memcpy(&result, pos, sizeof(result));
+	return be32toh(result);
+}
+
+/*!
+ * \brief Reads 6 bytes from the wireformat data.
+ *
+ * \param pos Data to read the 6 bytes from.
+ *
+ * \return The 6 bytes read, in host byte order.
+ */
+inline static uint64_t knot_wire_read_u48(const uint8_t *pos)
+{
+	assert(pos);
+	uint64_t input = 0;
+	memcpy((uint8_t *)&input + 1, pos, 6);
+	return be64toh(input) >> 8;
+}
+
+/*!
+ * \brief Read 8 bytes from the wireformat data.
+ *
+ * \param pos Data to read the 8 bytes from.
+ *
+ * \return The 8 bytes read, in host byte order.
+ */
+inline static uint64_t knot_wire_read_u64(const uint8_t *pos)
+{
+	assert(pos);
+	uint64_t result;
+	memcpy(&result, pos, sizeof(result));
+	return be64toh(result);
+}
+
+/*!
+ * \brief Writes 2 bytes in wireformat.
+ *
+ * The data are stored in network byte order (big endian).
+ *
+ * \param pos Position where to put the 2 bytes.
+ * \param data Data to put.
+ */
+inline static void knot_wire_write_u16(uint8_t *pos, uint16_t data)
+{
+	assert(pos);
+	uint16_t beval = htobe16(data);
+	memcpy(pos, &beval, sizeof(beval));
+}
+
+/*!
+ * \brief Writes 4 bytes in wireformat.
+ *
+ * The data are stored in network byte order (big endian).
+ *
+ * \param pos Position where to put the 4 bytes.
+ * \param data Data to put.
+ */
+inline static void knot_wire_write_u32(uint8_t *pos, uint32_t data)
+{
+	assert(pos);
+	uint32_t beval = htobe32(data);
+	memcpy(pos, &beval, sizeof(beval));
+}
+
+/*!
+ * \brief Writes 6 bytes in wireformat.
+ *
+ * The data are stored in network byte order (big endian).
+ *
+ * \param pos Position where to put the 4 bytes.
+ * \param data Data to put.
+ */
+inline static void knot_wire_write_u48(uint8_t *pos, uint64_t data)
+{
+	assert(pos);
+	uint64_t swapped = htobe64(data << 8);
+	memcpy(pos, (uint8_t *)&swapped + 1, 6);
+}
+
+/*!
+ * \brief Writes 8 bytes in wireformat.
+ *
+ * The data are stored in network byte order (big endian).
+ *
+ * \param pos Position where to put the 8 bytes.
+ * \param data Data to put.
+ */
+inline static void knot_wire_write_u64(uint8_t *pos, uint64_t data)
+{
+	assert(pos);
+	uint64_t beval = htobe64(data);
+	memcpy(pos, &beval, sizeof(beval));
+}
+
+/*! @} */
diff --git a/src/libknot/xdp.h b/src/libknot/xdp.h
new file mode 100644
index 0000000..db4460c
--- /dev/null
+++ b/src/libknot/xdp.h
@@ -0,0 +1,35 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Convenience header for including XDP-related stuff.
+ *
+ * \addtogroup libknot
+ * @{
+ */
+
+#pragma once
+
+#if ENABLE_XDP
+#include "libknot/xdp/xdp.h"
+#include "libknot/xdp/bpf-consts.h"
+#include "libknot/xdp/eth.h"
+#include "libknot/xdp/tcp.h"
+#endif
+
+/*! @} */
diff --git a/src/libknot/xdp/Makefile.am b/src/libknot/xdp/Makefile.am
new file mode 100644
index 0000000..cb58438
--- /dev/null
+++ b/src/libknot/xdp/Makefile.am
@@ -0,0 +1,20 @@
+# Useful commands:
+#   make filter
+#   ip link show $eth
+#   sudo ip link set dev $eth xdp off
+#   sudo ip link set dev $eth xdp obj ./bpf-kernel.o
+#
+# Built using LLVM/CLANG 14.
+#
+# When updating check using `llvm-objdump -h bpf-kernel.o` if .BTF and .BTF.ext
+# sections are present.
+
+EXTRA_DIST = bpf-kernel-obj.c bpf-kernel.c
+
+.PHONY: filter
+
+filter:
+	rm -f bpf-kernel.o bpf-kernel-obj.c
+	clang -target bpf -Wall -O2 -g -DNDEBUG -c -o bpf-kernel.o -I/usr/include/x86_64-linux-gnu -include ../../config.h bpf-kernel.c
+	llvm-strip -S bpf-kernel.o
+	xxd -i bpf-kernel.o > bpf-kernel-obj.c
diff --git a/src/libknot/xdp/Makefile.in b/src/libknot/xdp/Makefile.in
new file mode 100644
index 0000000..b56c39d
--- /dev/null
+++ b/src/libknot/xdp/Makefile.in
@@ -0,0 +1,545 @@
+# Makefile.in generated by automake 1.16.3 from Makefile.am.
+# @configure_input@
+
+# Copyright (C) 1994-2020 Free Software Foundation, Inc.
+
+# This Makefile.in is free software; the Free Software Foundation
+# gives unlimited permission to copy and/or distribute it,
+# with or without modifications, as long as this notice is preserved.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
+# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+# PARTICULAR PURPOSE.
+
+@SET_MAKE@
+
+# Useful commands:
+#   make filter
+#   ip link show $eth
+#   sudo ip link set dev $eth xdp off
+#   sudo ip link set dev $eth xdp obj ./bpf-kernel.o
+#
+# Built using LLVM/CLANG 14.
+#
+# When updating check using `llvm-objdump -h bpf-kernel.o` if .BTF and .BTF.ext
+# sections are present.
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diff --git a/src/libknot/xdp/bpf-consts.h b/src/libknot/xdp/bpf-consts.h
new file mode 100644
index 0000000..3b92cbb
--- /dev/null
+++ b/src/libknot/xdp/bpf-consts.h
@@ -0,0 +1,57 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief XDP filter configuration constants.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <linux/types.h>
+
+#define KNOT_XDP_PKT_ALIGNMENT	2 /*!< Fix for misaligned access to packet structures. */
+
+/*! \brief XDP filter configuration flags. */
+typedef enum {
+	KNOT_XDP_FILTER_ON    = 1 << 0,  /*!< Filter enabled. */
+	KNOT_XDP_FILTER_UDP   = 1 << 1,  /*!< Apply filter to UDP. */
+	KNOT_XDP_FILTER_TCP   = 1 << 2,  /*!< Apply filter to TCP. */
+	KNOT_XDP_FILTER_QUIC  = 1 << 3,  /*!< Apply filter to QUIC/UDP. */
+	KNOT_XDP_FILTER_PASS  = 1 << 4,  /*!< Pass incoming messages to ports >= port value. */
+	KNOT_XDP_FILTER_DROP  = 1 << 5,  /*!< Drop incoming messages to ports >= port value. */
+	KNOT_XDP_FILTER_ROUTE = 1 << 6,  /*!< Consider routing information from kernel. */
+} knot_xdp_filter_flag_t;
+
+/*! \brief XDP map item for the filter configuration. */
+typedef struct knot_xdp_opts knot_xdp_opts_t;
+struct knot_xdp_opts {
+	__u16 flags;     /*!< XDP filter flags \a knot_xdp_filter_flag_t. */
+	__u16 udp_port;  /*!< UDP/TCP port to listen on. */
+	__u16 quic_port; /*!< QUIC/UDP port to listen on. */
+} __attribute__((packed));
+
+/*! \brief Additional information from the filter. */
+typedef struct knot_xdp_info knot_xdp_info_t;
+struct knot_xdp_info {
+	__u16 out_if_index; /*!< Index of the output interface (if routing enabled). */
+};
+
+/*! @} */
diff --git a/src/libknot/xdp/bpf-kernel-obj.c b/src/libknot/xdp/bpf-kernel-obj.c
new file mode 100644
index 0000000..9f1ee71
--- /dev/null
+++ b/src/libknot/xdp/bpf-kernel-obj.c
@@ -0,0 +1,941 @@
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+  0x01, 0x00, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x10, 0x05, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x20, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x30, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x40, 0x05, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x50, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x60, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x70, 0x05, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x80, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x90, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xa0, 0x05, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0xb0, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0xc0, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xd0, 0x05, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0xe0, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0xf0, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x10, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x20, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x30, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x40, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x50, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x60, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x70, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x80, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x90, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0xa0, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0xb0, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xc0, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0xd0, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0xe0, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0xf0, 0x06, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x00, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x10, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x20, 0x07, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x30, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x40, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x50, 0x07, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x1a, 0x1b, 0x1c, 0x1d, 0x00, 0x2e, 0x74, 0x65, 0x78, 0x74, 0x00, 0x2e,
+  0x72, 0x65, 0x6c, 0x2e, 0x42, 0x54, 0x46, 0x2e, 0x65, 0x78, 0x74, 0x00,
+  0x2e, 0x6d, 0x61, 0x70, 0x73, 0x00, 0x2e, 0x72, 0x65, 0x6c, 0x78, 0x64,
+  0x70, 0x00, 0x6f, 0x70, 0x74, 0x73, 0x5f, 0x6d, 0x61, 0x70, 0x00, 0x78,
+  0x73, 0x6b, 0x73, 0x5f, 0x6d, 0x61, 0x70, 0x00, 0x2e, 0x6c, 0x6c, 0x76,
+  0x6d, 0x5f, 0x61, 0x64, 0x64, 0x72, 0x73, 0x69, 0x67, 0x00, 0x5f, 0x6c,
+  0x69, 0x63, 0x65, 0x6e, 0x73, 0x65, 0x00, 0x78, 0x64, 0x70, 0x5f, 0x72,
+  0x65, 0x64, 0x69, 0x72, 0x65, 0x63, 0x74, 0x5f, 0x64, 0x6e, 0x73, 0x5f,
+  0x66, 0x75, 0x6e, 0x63, 0x00, 0x2e, 0x73, 0x74, 0x72, 0x74, 0x61, 0x62,
+  0x00, 0x2e, 0x73, 0x79, 0x6d, 0x74, 0x61, 0x62, 0x00, 0x2e, 0x72, 0x65,
+  0x6c, 0x2e, 0x42, 0x54, 0x46, 0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x39,
+  0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x35, 0x38, 0x00, 0x4c, 0x42, 0x42,
+  0x30, 0x5f, 0x35, 0x37, 0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x31, 0x37,
+  0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x35, 0x36, 0x00, 0x4c, 0x42, 0x42,
+  0x30, 0x5f, 0x34, 0x36, 0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x33, 0x36,
+  0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x31, 0x36, 0x00, 0x4c, 0x42, 0x42,
+  0x30, 0x5f, 0x35, 0x35, 0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x34, 0x35,
+  0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x34, 0x00, 0x4c, 0x42, 0x42, 0x30,
+  0x5f, 0x35, 0x34, 0x00, 0x4c, 0x42, 0x42, 0x30, 0x5f, 0x32, 0x33, 0x00,
+  0x4c, 0x42, 0x42, 0x30, 0x5f, 0x34, 0x30, 0x00, 0x4c, 0x42, 0x42, 0x30,
+  0x5f, 0x33, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x61, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0xc4, 0x27, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x1e, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x06, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x1a, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x40, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00,
+  0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x14, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x40, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x43, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x03, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x80, 0x09, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x75, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x84, 0x09, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x62, 0x0d, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x71, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00,
+  0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x60, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00,
+  0x07, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0b, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xe8, 0x16, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x60, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x04, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x07, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x90, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x30, 0x07, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x00, 0x09, 0x00, 0x00, 0x00,
+  0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x34, 0x00, 0x00, 0x00, 0x03, 0x4c, 0xff, 0x6f,
+  0x00, 0x00, 0x00, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0xc0, 0x27, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x04, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x69, 0x00, 0x00, 0x00,
+  0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x48, 0x1e, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0xf8, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x01, 0x00, 0x00, 0x00, 0x11, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00, 0x00, 0x18, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+};
+unsigned int bpf_kernel_o_len = 11256;
diff --git a/src/libknot/xdp/bpf-kernel-obj.h b/src/libknot/xdp/bpf-kernel-obj.h
new file mode 100644
index 0000000..7c3d759
--- /dev/null
+++ b/src/libknot/xdp/bpf-kernel-obj.h
@@ -0,0 +1,2 @@
+extern unsigned char bpf_kernel_o[];
+extern unsigned int bpf_kernel_o_len;
diff --git a/src/libknot/xdp/bpf-kernel.c b/src/libknot/xdp/bpf-kernel.c
new file mode 100644
index 0000000..8bffd7f
--- /dev/null
+++ b/src/libknot/xdp/bpf-kernel.c
@@ -0,0 +1,293 @@
+/*  Copyright (C) 2022 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 <linux/if_ether.h>
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+
+#include "bpf-consts.h"
+#include "../../contrib/libbpf/include/uapi/linux/bpf.h"
+#include "../../contrib/libbpf/bpf/bpf_endian.h"
+#include "../../contrib/libbpf/bpf/bpf_helpers.h"
+
+/* Don't fragment flag. */
+#define	IP_DF		0x4000
+
+#define AF_INET		2
+#define AF_INET6	10
+
+/* Define maximum reasonable number of NIC queues supported. */
+#define QUEUE_MAX	256
+
+/* A map of configuration options. */
+struct {
+	__uint(type, BPF_MAP_TYPE_ARRAY);
+	__uint(max_entries, QUEUE_MAX);
+	__uint(key_size, sizeof(__u32)); /* Must be 4 bytes. */
+	__uint(value_size, sizeof(knot_xdp_opts_t));
+} opts_map SEC(".maps");
+
+/* A map of AF_XDP sockets. */
+struct {
+	__uint(type, BPF_MAP_TYPE_XSKMAP);
+	__uint(max_entries, QUEUE_MAX);
+	__uint(key_size, sizeof(__u32)); /* Must be 4 bytes. */
+	__uint(value_size, sizeof(int));
+} xsks_map SEC(".maps");
+
+struct ipv6_frag_hdr {
+	unsigned char nexthdr;
+	unsigned char whatever[7];
+} __attribute__((packed));
+
+SEC("xdp")
+int xdp_redirect_dns_func(struct xdp_md *ctx)
+{
+	/* Get the queue options. */
+	__u32 index = ctx->rx_queue_index;
+	struct knot_xdp_opts *opts_ptr = bpf_map_lookup_elem(&opts_map, &index);
+	if (!opts_ptr) {
+		return XDP_ABORTED;
+	}
+	knot_xdp_opts_t opts = *opts_ptr;
+
+	/* Check if the filter is disabled. */
+	if (!(opts.flags & KNOT_XDP_FILTER_ON)) {
+		return XDP_PASS;
+	}
+
+	/* Try to reserve space in front of the packet for additional (VLAN) data. */
+	(void)bpf_xdp_adjust_meta(ctx, - (int)sizeof(struct knot_xdp_info)
+	                               - KNOT_XDP_PKT_ALIGNMENT);
+
+	void *data = (void *)(long)ctx->data;
+	const void *data_end = (void *)(long)ctx->data_end;
+	struct knot_xdp_info *meta = (void *)(long)ctx->data_meta;
+
+	/* Check if the meta data pointer is usable (e.g. not `tap` interface). */
+	if ((void *)meta + sizeof(*meta) > data) {
+		meta = 0;
+	}
+
+	struct ethhdr *eth_hdr = data;
+	const void *ip_hdr;
+	const struct iphdr *ip4;
+	const struct ipv6hdr *ip6;
+	const void *l4_hdr;
+	__u8 ipv4;
+	__u8 ip_proto;
+	__u8 fragmented = 0;
+	__u16 eth_type; /* In big endian. */
+
+	/* Parse Ethernet header. */
+	if ((void *)eth_hdr + sizeof(*eth_hdr) > data_end) {
+		return XDP_DROP;
+	}
+	data += sizeof(*eth_hdr);
+
+	/* Parse possible VLAN (802.1Q) header. */
+	if (eth_hdr->h_proto == __constant_htons(ETH_P_8021Q)) {
+		if (data + sizeof(__u16) + sizeof(eth_type) > data_end) {
+			return XDP_DROP;
+		} else if (meta == 0) { /* VLAN not supported. */
+			return XDP_PASS;
+		}
+		__builtin_memcpy(&eth_type, data + sizeof(__u16), sizeof(eth_type));
+		data += sizeof(__u16) + sizeof(eth_type);
+	} else {
+		eth_type = eth_hdr->h_proto;
+	}
+
+	ip_hdr = data;
+
+	/* Parse IPv4 or IPv6 header. */
+	switch (eth_type) {
+	case __constant_htons(ETH_P_IP):
+		ip4 = ip_hdr;
+		if ((void *)ip4 + sizeof(*ip4) > data_end) {
+			return XDP_DROP;
+		}
+		if (ip4->version != 4) {
+			return XDP_DROP;
+		}
+
+		/* Check the IP length. Cannot use strict equality due to
+		 * Ethernet padding applied to frames shorter than 64 octects. */
+		if (data_end - data < __bpf_ntohs(ip4->tot_len)) {
+			return XDP_DROP;
+		}
+
+		if (ip4->frag_off != 0 &&
+		    ip4->frag_off != __constant_htons(IP_DF)) {
+			fragmented = 1;
+		}
+		ip_proto = ip4->protocol;
+		l4_hdr = data + ip4->ihl * 4;
+		ipv4 = 1;
+		break;
+	case __constant_htons(ETH_P_IPV6):
+		ip6 = ip_hdr;
+		if ((void *)ip6 + sizeof(*ip6) > data_end) {
+			return XDP_DROP;
+		}
+		if (ip6->version != 6) {
+			return XDP_DROP;
+		}
+
+		/* Check the IP length. Cannot use strict equality due to
+		 * Ethernet padding applied to frames shorter than 64 octects. */
+		if (data_end - data < __bpf_ntohs(ip6->payload_len) + sizeof(*ip6)) {
+			return XDP_DROP;
+		}
+
+		ip_proto = ip6->nexthdr;
+		data += sizeof(*ip6);
+		if (ip_proto == IPPROTO_FRAGMENT) {
+			fragmented = 1;
+			const struct ipv6_frag_hdr *frag = data;
+			if ((void *)frag + sizeof(*frag) > data_end) {
+				return XDP_DROP;
+			}
+			ip_proto = frag->nexthdr;
+			data += sizeof(*frag);
+		}
+		l4_hdr = data;
+		ipv4 = 0;
+		break;
+	default:
+		/* Pass packets of possible other protocols. */
+		return XDP_PASS;
+	}
+
+	const struct tcphdr *tcp;
+	const struct udphdr *udp;
+	__u16 port_dest;
+	__u8 match = 0;
+
+	/* Check the transport protocol. */
+	switch (ip_proto) {
+	case IPPROTO_TCP:
+		/* Parse TCP header. */
+		tcp = l4_hdr;
+		if (l4_hdr + sizeof(*tcp) > data_end) {
+			return XDP_DROP;
+		}
+
+		port_dest = __bpf_ntohs(tcp->dest);
+
+		if ((opts.flags & KNOT_XDP_FILTER_TCP) &&
+		    (port_dest == opts.udp_port ||
+		     ((opts.flags & (KNOT_XDP_FILTER_PASS | KNOT_XDP_FILTER_DROP)) &&
+		      port_dest >= opts.udp_port))) {
+			match = 1;
+		}
+		break;
+	case IPPROTO_UDP:
+		/* Parse UDP header. */
+		udp = l4_hdr;
+		if (l4_hdr + sizeof(*udp) > data_end) {
+			return XDP_DROP;
+		}
+
+		/* Check the UDP length. */
+		if (data_end - (void *)udp < __bpf_ntohs(udp->len)) {
+			return XDP_DROP;
+		}
+
+		port_dest = __bpf_ntohs(udp->dest);
+
+		if ((opts.flags & KNOT_XDP_FILTER_UDP) &&
+		    (port_dest == opts.udp_port ||
+		     ((opts.flags & (KNOT_XDP_FILTER_PASS | KNOT_XDP_FILTER_DROP)) &&
+		      port_dest >= opts.udp_port))) {
+			match = 1;
+		} else if ((opts.flags & KNOT_XDP_FILTER_QUIC) &&
+		    (port_dest == opts.quic_port ||
+		     ((opts.flags & (KNOT_XDP_FILTER_PASS | KNOT_XDP_FILTER_DROP)) &&
+		      port_dest >= opts.quic_port))) {
+			match = 1;
+		}
+		break;
+	default:
+		/* Pass packets of possible other protocols. */
+		return XDP_PASS;
+	}
+
+	if (!match) {
+		/* Pass non-matching packet. */
+		return XDP_PASS;
+	} else if (opts.flags & KNOT_XDP_FILTER_DROP) {
+		/* Drop matching packet if requested. */
+		return XDP_DROP;
+	} else if (fragmented) {
+		/* Drop fragmented packet. */
+		return XDP_DROP;
+	}
+
+	/* Take into account routing information. */
+	if (opts.flags & KNOT_XDP_FILTER_ROUTE) {
+		struct bpf_fib_lookup fib = {
+			.ifindex = 1 /* Loopback. */
+		};
+		if (ipv4) {
+			fib.family   = AF_INET;
+			fib.ipv4_src = ip4->daddr;
+			fib.ipv4_dst = ip4->saddr;
+		} else {
+			struct in6_addr *ipv6_src = (struct in6_addr *)fib.ipv6_src;
+			struct in6_addr *ipv6_dst = (struct in6_addr *)fib.ipv6_dst;
+			fib.family = AF_INET6;
+			*ipv6_src  = ip6->daddr;
+			*ipv6_dst  = ip6->saddr;
+		}
+
+		const __u16 *mac_in = (const __u16 *)eth_hdr->h_dest;
+		const __u16 *mac_out = (const __u16 *)fib.smac;
+		int ret = bpf_fib_lookup(ctx, &fib, sizeof(fib), BPF_FIB_LOOKUP_DIRECT);
+		switch (ret) {
+		case BPF_FIB_LKUP_RET_SUCCESS:
+			/* Cross-interface answers are handled through normal stack. */
+			if (mac_in[0] != mac_out[0] ||
+			    mac_in[1] != mac_out[1] ||
+			    mac_in[2] != mac_out[2]) {
+				return XDP_PASS;
+			}
+
+			/* Store output interface index for later use with VLAN in user space. */
+			if (meta != 0) {
+				meta->out_if_index = fib.ifindex;
+			}
+
+			/* Update destination MAC for responding. */
+			__builtin_memcpy(eth_hdr->h_source, fib.dmac, ETH_ALEN);
+			break;
+		case BPF_FIB_LKUP_RET_FWD_DISABLED: /* Disabled forwarding on loopback. */
+			return XDP_ABORTED;
+		case BPF_FIB_LKUP_RET_NO_NEIGH: /* Use normal stack to obtain MAC. */
+			return XDP_PASS;
+		default:
+			return XDP_DROP;
+		}
+	}
+
+	/* Forward the packet to user space. */
+	return bpf_redirect_map(&xsks_map, ctx->rx_queue_index, 0);
+}
+
+char _license[] SEC("license") = "GPL";
diff --git a/src/libknot/xdp/bpf-user.c b/src/libknot/xdp/bpf-user.c
new file mode 100644
index 0000000..a0c8bae
--- /dev/null
+++ b/src/libknot/xdp/bpf-user.c
@@ -0,0 +1,313 @@
+/*  Copyright (C) 2022 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 <bpf/bpf.h>
+#include <linux/if_link.h>
+#include <net/if.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "libknot/endian.h"
+#include "libknot/error.h"
+#include "libknot/xdp/bpf-kernel-obj.h"
+#include "libknot/xdp/bpf-user.h"
+#include "libknot/xdp/eth.h"
+#include "contrib/openbsd/strlcpy.h"
+
+#define NO_BPF_MAPS	2
+
+static inline bool IS_ERR_OR_NULL(const void *ptr)
+{
+	return (ptr == NULL) || (unsigned long)ptr >= (unsigned long)-4095;
+}
+
+static int prog_load(struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_program *prog, *first_prog = NULL;
+	struct bpf_object *obj;
+
+	obj = bpf_object__open_mem(bpf_kernel_o, bpf_kernel_o_len, NULL);
+	if (IS_ERR_OR_NULL(obj)) {
+		return KNOT_ENOENT;
+	}
+
+	bpf_object__for_each_program(prog, obj) {
+		bpf_program__set_type(prog, BPF_PROG_TYPE_XDP);
+		if (first_prog == NULL) {
+			first_prog = prog;
+		}
+	}
+
+	if (first_prog == NULL) {
+		bpf_object__close(obj);
+		return KNOT_ENOENT;
+	}
+
+	int ret = bpf_object__load(obj);
+	if (ret != 0) {
+		bpf_object__close(obj);
+		return KNOT_EINVAL;
+	}
+
+	*pobj = obj;
+	*prog_fd = bpf_program__fd(first_prog);
+
+	return KNOT_EOK;
+}
+
+static int ensure_prog(struct kxsk_iface *iface, bool overwrite)
+{
+	if (bpf_kernel_o_len < 2) {
+		return KNOT_ENOTSUP;
+	}
+
+	/* Use libbpf for extracting BPF byte-code from BPF-ELF object, and
+	 * loading this into the kernel via bpf-syscall. */
+	int prog_fd;
+	int ret = prog_load(&iface->prog_obj, &prog_fd);
+	if (ret != KNOT_EOK) {
+		return KNOT_EPROGRAM;
+	}
+
+#if USE_LIBXDP
+	ret = bpf_xdp_attach(iface->if_index, prog_fd,
+	                     overwrite ? 0 : XDP_FLAGS_UPDATE_IF_NOEXIST, NULL);
+#else
+	ret = bpf_set_link_xdp_fd(iface->if_index, prog_fd,
+	                          overwrite ? 0 : XDP_FLAGS_UPDATE_IF_NOEXIST);
+#endif
+	if (ret != 0) {
+		close(prog_fd);
+	}
+	if (ret == -EBUSY && !overwrite) { // We try accepting the present program.
+		uint32_t prog_id = 0;
+#if USE_LIBXDP
+		ret = bpf_xdp_query_id(iface->if_index, 0, &prog_id);
+#else
+		ret = bpf_get_link_xdp_id(iface->if_index, &prog_id, 0);
+#endif
+		if (ret == 0 && prog_id != 0) {
+			ret = prog_fd = bpf_prog_get_fd_by_id(prog_id);
+		}
+	}
+	if (ret < 0) {
+		return KNOT_EFD;
+	} else {
+		return prog_fd;
+	}
+}
+
+static void unget_bpf_maps(struct kxsk_iface *iface)
+{
+	if (iface->opts_map_fd >= 0) {
+		close(iface->opts_map_fd);
+	}
+	if (iface->xsks_map_fd >= 0) {
+		close(iface->xsks_map_fd);
+	}
+	iface->opts_map_fd = iface->xsks_map_fd = -1;
+}
+
+/*!
+ * /brief Get FDs for the two maps and assign them into xsk_info-> fields.
+ *
+ * Inspired by xsk_lookup_bpf_maps() from libbpf before qidconf_map elimination.
+ */
+static int get_bpf_maps(int prog_fd, struct kxsk_iface *iface)
+{
+	uint32_t *map_ids = calloc(NO_BPF_MAPS, sizeof(*map_ids));
+	if (map_ids == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	struct bpf_prog_info prog_info = {
+		.nr_map_ids = NO_BPF_MAPS,
+		.map_ids = (__u64)(unsigned long)map_ids,
+	};
+
+	uint32_t prog_len = sizeof(struct bpf_prog_info);
+	int ret = bpf_obj_get_info_by_fd(prog_fd, &prog_info, &prog_len);
+	if (ret != 0) {
+		free(map_ids);
+		return ret;
+	}
+
+	for (int i = 0; i < NO_BPF_MAPS; ++i) {
+		int fd = bpf_map_get_fd_by_id(map_ids[i]);
+		if (fd < 0) {
+			continue;
+		}
+
+		struct bpf_map_info map_info = { 0 };
+		uint32_t map_len = sizeof(struct bpf_map_info);
+		ret = bpf_obj_get_info_by_fd(fd, &map_info, &map_len);
+		if (ret != 0) {
+			close(fd);
+			continue;
+		}
+
+		if (strcmp(map_info.name, "opts_map") == 0) {
+			iface->opts_map_fd = fd;
+			continue;
+		}
+
+		if (strcmp(map_info.name, "xsks_map") == 0) {
+			iface->xsks_map_fd = fd;
+			continue;
+		}
+
+		close(fd);
+	}
+
+	if (iface->opts_map_fd < 0 || iface->xsks_map_fd < 0) {
+		unget_bpf_maps(iface);
+		free(map_ids);
+		return KNOT_ENOENT;
+	}
+
+	free(map_ids);
+	return KNOT_EOK;
+}
+
+int kxsk_socket_start(const struct kxsk_iface *iface, knot_xdp_filter_flag_t flags,
+                      uint16_t udp_port, uint16_t quic_port, struct xsk_socket *xsk)
+{
+	if (iface == NULL || xsk == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int fd = xsk_socket__fd(xsk);
+	int ret = bpf_map_update_elem(iface->xsks_map_fd, &iface->if_queue, &fd, 0);
+	if (ret != 0) {
+		return ret;
+	}
+
+	knot_xdp_opts_t opts = {
+		.flags = flags | KNOT_XDP_FILTER_ON,
+		.udp_port = udp_port,
+		.quic_port = quic_port,
+	};
+
+	ret = bpf_map_update_elem(iface->opts_map_fd, &iface->if_queue, &opts, 0);
+	if (ret != 0) {
+		(void)bpf_map_delete_elem(iface->xsks_map_fd, &iface->if_queue);
+	}
+
+	return ret;
+}
+
+void kxsk_socket_stop(const struct kxsk_iface *iface)
+{
+	if (iface == NULL) {
+		return;
+	}
+
+	knot_xdp_opts_t opts = { 0 };
+
+	(void)bpf_map_update_elem(iface->opts_map_fd, &iface->if_queue, &opts, 0);
+	(void)bpf_map_delete_elem(iface->xsks_map_fd, &iface->if_queue);
+}
+
+int kxsk_iface_new(const char *if_name, unsigned if_queue, knot_xdp_load_bpf_t load_bpf,
+                   struct kxsk_iface **out_iface)
+{
+	if (if_name == NULL || out_iface == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct kxsk_iface *iface = calloc(1, sizeof(*iface) + IFNAMSIZ);
+	if (iface == NULL) {
+		return KNOT_ENOMEM;
+	}
+	iface->if_name = (char *)(iface + 1);
+	strlcpy((char *)iface->if_name, if_name, IFNAMSIZ);
+	iface->if_index = if_nametoindex(if_name);
+	if (iface->if_index == 0) {
+		free(iface);
+		return KNOT_EINVAL;
+	}
+	iface->if_queue = if_queue;
+	iface->opts_map_fd = iface->xsks_map_fd = -1;
+
+	int ret;
+	switch (load_bpf) {
+	case KNOT_XDP_LOAD_BPF_NEVER:
+		(void)0;
+		uint32_t prog_id = 0;
+#if USE_LIBXDP
+		ret = bpf_xdp_query_id(iface->if_index, 0, &prog_id);
+#else
+		ret = bpf_get_link_xdp_id(iface->if_index, &prog_id, 0);
+#endif
+		if (ret == 0) {
+			if (prog_id == 0) {
+				ret = KNOT_EPROGRAM;
+			} else {
+				ret = bpf_prog_get_fd_by_id(prog_id);
+			}
+		}
+		break;
+	case KNOT_XDP_LOAD_BPF_ALWAYS_UNLOAD:
+#if USE_LIBXDP
+		(void)bpf_xdp_detach(iface->if_index, 0, NULL);
+#else
+		(void)bpf_set_link_xdp_fd(iface->if_index, -1, 0);
+#endif
+		sleep(1);
+		// FALLTHROUGH
+	case KNOT_XDP_LOAD_BPF_ALWAYS:
+		ret = ensure_prog(iface, true);
+		break;
+	case KNOT_XDP_LOAD_BPF_MAYBE:
+		ret = ensure_prog(iface, false);
+		break;
+	default:
+		return KNOT_EINVAL;
+	}
+
+	if (ret >= 0) {
+		ret = get_bpf_maps(ret, iface);
+	}
+	if (ret < 0) {
+		free(iface);
+		return ret;
+	}
+
+	knot_xdp_mode_t mode = knot_eth_xdp_mode(iface->if_index);
+	if (mode == KNOT_XDP_MODE_NONE) {
+		free(iface);
+		return KNOT_ENOTSUP;
+	}
+
+	*out_iface = iface;
+	return KNOT_EOK;
+}
+
+void kxsk_iface_free(struct kxsk_iface *iface)
+{
+	if (iface == NULL) {
+		return;
+	}
+
+	unget_bpf_maps(iface);
+
+	if (iface->prog_obj != NULL) {
+		bpf_object__close(iface->prog_obj);
+	}
+
+	free(iface);
+}
diff --git a/src/libknot/xdp/bpf-user.h b/src/libknot/xdp/bpf-user.h
new file mode 100644
index 0000000..14c54c5
--- /dev/null
+++ b/src/libknot/xdp/bpf-user.h
@@ -0,0 +1,139 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief XDP socket interface.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#if USE_LIBXDP
+ #include <xdp/xsk.h>
+#else
+ #include <bpf/xsk.h>
+#endif
+
+#include "libknot/xdp/xdp.h"
+
+struct kxsk_iface {
+	/*! Interface name. */
+	const char *if_name;
+	/*! Interface name index (derived from ifname). */
+	int if_index;
+	/*! Network card queue id. */
+	unsigned if_queue;
+
+	/*! Configuration BPF map file descriptor. */
+	int opts_map_fd;
+	/*! XSK BPF map file descriptor. */
+	int xsks_map_fd;
+
+	/*! BPF program object. */
+	struct bpf_object *prog_obj;
+};
+
+struct kxsk_umem {
+	/*! Fill queue: passing memory frames to kernel - ready to receive. */
+	struct xsk_ring_prod fq;
+	/*! Completion queue: passing memory frames from kernel - after send finishes. */
+	struct xsk_ring_cons cq;
+	/*! Handle internal to libbpf. */
+	struct xsk_umem *umem;
+
+	/*! The memory frames. */
+	struct umem_frame *frames;
+	/*! The number of free frames (for TX). */
+	uint32_t tx_free_count;
+	/*! Stack of indices of the free frames (for TX). */
+	uint16_t tx_free_indices[];
+};
+
+struct knot_xdp_socket {
+	/*! Receive queue: passing arrived packets from kernel. */
+	struct xsk_ring_cons rx;
+	/*! Transmit queue: passing packets to kernel for sending. */
+	struct xsk_ring_prod tx;
+	/*! Information about memory frames for all the passed packets. */
+	struct kxsk_umem *umem;
+	/*! Handle internal to libbpf. */
+	struct xsk_socket *xsk;
+
+	/*! Interface context. */
+	const struct kxsk_iface *iface;
+
+	/*! If non-NULL, it's a mocked socket with this send function. */
+	int (*send_mock)(struct knot_xdp_socket *, const knot_xdp_msg_t[], uint32_t, uint32_t *);
+
+	/*! The kernel has to be woken up by a syscall indication. */
+	bool kernel_needs_wakeup;
+
+	/*! The limit of frame size. */
+	unsigned frame_limit;
+
+	/*! Mapping of interface indices to VLAN tags. */
+	uint16_t *vlan_map;
+	uint16_t vlan_map_max;
+};
+
+/*!
+ * \brief Set up BPF program and map for one XDP socket.
+ *
+ * \param if_name    Name of the net iface (e.g. eth0).
+ * \param if_queue   Network card queue id.
+ * \param load_bpf   Insert BPF program into packet processing.
+ * \param out_iface  Output: created interface context.
+ *
+ * \return KNOT_E* or -errno
+ */
+int kxsk_iface_new(const char *if_name, unsigned if_queue, knot_xdp_load_bpf_t load_bpf,
+                   struct kxsk_iface **out_iface);
+
+/*!
+ * \brief Unload BPF maps for a socket.
+ *
+ * \note This keeps the loaded BPF program. We don't care.
+ *
+ * \param iface  Interface context to be freed.
+ */
+void kxsk_iface_free(struct kxsk_iface *iface);
+
+/*!
+ * \brief Activate this AF_XDP socket through the BPF maps.
+ *
+ * \param iface        Interface context.
+ * \param flags        XDP filter configuration flags.
+ * \param udp_port     UDP and/or TCP port to listen on if enabled via \a opts.
+ * \param quic_port    QUIC/UDP port to listen on if enabled via \a opts.
+ * \param xsk          Socket ctx.
+ *
+ * \return KNOT_E* or -errno
+ */
+int kxsk_socket_start(const struct kxsk_iface *iface, knot_xdp_filter_flag_t flags,
+                      uint16_t udp_port, uint16_t quic_port, struct xsk_socket *xsk);
+
+/*!
+ * \brief Deactivate this AF_XDP socket through the BPF maps.
+ *
+ * \param iface  Interface context.
+ */
+void kxsk_socket_stop(const struct kxsk_iface *iface);
+
+/*! @} */
diff --git a/src/libknot/xdp/eth.c b/src/libknot/xdp/eth.c
new file mode 100644
index 0000000..608eb20
--- /dev/null
+++ b/src/libknot/xdp/eth.c
@@ -0,0 +1,312 @@
+/*  Copyright (C) 2023 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 <bpf/libbpf.h>
+#include <errno.h>
+#include <ifaddrs.h>
+#include <linux/ethtool.h>
+#include <linux/if_link.h>
+#include <linux/if_vlan.h>
+#include <linux/sockios.h>
+#include <net/if.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+
+#include "contrib/openbsd/strlcpy.h"
+#include "contrib/sockaddr.h"
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "libknot/xdp/eth.h"
+
+_public_
+int knot_eth_queues(const char *devname)
+{
+	if (devname == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		return knot_map_errno();
+	}
+
+	struct ethtool_channels ch = {
+		.cmd = ETHTOOL_GCHANNELS
+	};
+	struct ifreq ifr = {
+		.ifr_data = (char *)&ch
+	};
+	strlcpy(ifr.ifr_name, devname, IFNAMSIZ);
+
+	int ret = ioctl(fd, SIOCETHTOOL, &ifr);
+	if (ret != 0) {
+		if (errno == EOPNOTSUPP) {
+			ret = 1;
+		} else {
+			ret = knot_map_errno();
+		}
+	} else {
+		if (ch.combined_count == 0) {
+			ret = 1;
+		} else {
+			ret = ch.combined_count;
+		}
+	}
+
+	close(fd);
+	return ret;
+}
+
+_public_
+int knot_eth_rss(const char *devname, knot_eth_rss_conf_t **rss_conf)
+{
+	if (devname == NULL || rss_conf == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct ethtool_rxfh *ctx = NULL;
+	knot_eth_rss_conf_t *out = NULL;
+	int ret = KNOT_ERROR;
+
+	int fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		return knot_map_errno();
+	}
+
+	struct ethtool_rxfh sizes = {
+		.cmd = ETHTOOL_GRSSH
+	};
+	struct ifreq ifr = {
+		.ifr_data = (char *)&sizes
+	};
+	strlcpy(ifr.ifr_name, devname, IFNAMSIZ);
+
+	ret = ioctl(fd, SIOCETHTOOL, &ifr);
+	if (ret != 0) {
+		ret = knot_map_errno();
+		goto finish;
+	}
+
+	const unsigned data_size = sizes.indir_size * sizeof(sizes.rss_config[0]) +
+	                           sizes.key_size;
+
+	ctx = calloc(1, sizeof(*ctx) + data_size);
+	if (ctx == NULL) {
+		ret = KNOT_ENOMEM;
+		goto finish;
+	}
+	ctx->cmd = ETHTOOL_GRSSH;
+	ctx->indir_size = sizes.indir_size;
+	ctx->key_size = sizes.key_size;
+	ifr.ifr_data = (char *)ctx;
+
+	ret = ioctl(fd, SIOCETHTOOL, &ifr);
+	if (ret != 0) {
+		ret = knot_map_errno();
+		goto finish;
+	}
+
+	out = calloc(1, sizeof(*out) + data_size);
+	if (out == NULL) {
+		ret = KNOT_ENOMEM;
+		goto finish;
+	}
+
+	out->table_size = sizes.indir_size;
+	out->key_size = sizes.key_size;
+	memcpy(out->data, ctx->rss_config, data_size);
+	out->mask = out->table_size - 1;
+finish:
+	*rss_conf = out;
+
+	free(ctx);
+	close(fd);
+	return ret;
+}
+
+_public_
+int knot_eth_mtu(const char *devname)
+{
+	if (devname == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		return knot_map_errno();
+	}
+
+	struct ifreq ifr = { 0 };
+	strlcpy(ifr.ifr_name, devname, IFNAMSIZ);
+
+	int ret = ioctl(fd, SIOCGIFMTU, &ifr);
+	if (ret != 0) {
+		if (errno == EOPNOTSUPP) {
+			ret = KNOT_ENOTSUP;
+		} else {
+			ret = knot_map_errno();
+		}
+	} else {
+		ret = ifr.ifr_mtu;
+	}
+
+	close(fd);
+	return ret;
+}
+
+_public_
+int knot_eth_name_from_addr(const struct sockaddr_storage *addr, char *out,
+                            size_t out_len)
+{
+	if (addr == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct ifaddrs *ifaces = NULL;
+	if (getifaddrs(&ifaces) != 0) {
+		return -errno;
+	}
+
+	size_t matches = 0;
+	char *match_name = NULL;
+
+	for (struct ifaddrs *ifa = ifaces; ifa != NULL; ifa = ifa->ifa_next) {
+		const struct sockaddr_storage *ifss = (struct sockaddr_storage *)ifa->ifa_addr;
+		if (ifss == NULL) { // Observed on interfaces without any address.
+			continue;
+		}
+
+		if ((ifss->ss_family == addr->ss_family && sockaddr_is_any(addr)) ||
+		    sockaddr_cmp(ifss, addr, true) == 0) {
+			matches++;
+			match_name = ifa->ifa_name;
+		}
+	}
+
+	if (matches == 1) {
+		size_t len = strlcpy(out, match_name, out_len);
+		freeifaddrs(ifaces);
+		return (len >= out_len) ? KNOT_ESPACE : KNOT_EOK;
+	}
+
+	freeifaddrs(ifaces);
+	return matches == 0 ? KNOT_EADDRNOTAVAIL : KNOT_ELIMIT;
+}
+
+_public_
+int knot_eth_vlans(uint16_t *vlan_map[], uint16_t *vlan_map_max)
+{
+	if (vlan_map == NULL || vlan_map_max == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct ifaddrs *ifaces = NULL;
+	if (getifaddrs(&ifaces) != 0) {
+		return knot_map_errno();
+	}
+
+	unsigned map_size = 0;
+	for (struct ifaddrs *ifa = ifaces; ifa != NULL; ifa = ifa->ifa_next) {
+		if (ifa->ifa_addr->sa_family != AF_PACKET) {
+			continue;
+		}
+		map_size++;
+	}
+
+	uint16_t *map = calloc(sizeof(uint16_t), 1 + map_size); // Indexed from 1.
+	if (map == NULL) {
+		freeifaddrs(ifaces);
+		return KNOT_ENOMEM;
+	}
+
+	int fd = socket(AF_INET, SOCK_DGRAM, 0);
+	if (fd < 0) {
+		free(map);
+		freeifaddrs(ifaces);
+		return knot_map_errno();
+	}
+
+	for (struct ifaddrs *ifa = ifaces; ifa != NULL; ifa = ifa->ifa_next) {
+		if (ifa->ifa_addr == NULL || ifa->ifa_addr->sa_family != AF_PACKET) {
+			continue;
+		}
+
+		unsigned if_index = if_nametoindex(ifa->ifa_name);
+		if (if_index == 0) {
+			close(fd);
+			free(map);
+			freeifaddrs(ifaces);
+			return knot_map_errno();
+		}
+
+		struct vlan_ioctl_args ifv = {
+			.cmd = GET_VLAN_REALDEV_NAME_CMD
+		};
+		strlcpy(ifv.device1, ifa->ifa_name, sizeof(ifv.device1));
+
+		if (ioctl(fd, SIOCGIFVLAN, &ifv) >= 0) {
+			memset(&ifv, 0, sizeof(ifv));
+			ifv.cmd = GET_VLAN_VID_CMD;
+			strlcpy(ifv.device1, ifa->ifa_name, sizeof(ifv.device1));
+
+			if (ioctl(fd, SIOCGIFVLAN, &ifv) < 0) {
+				close(fd);
+				free(map);
+				freeifaddrs(ifaces);
+				return knot_map_errno();
+			}
+
+			map[if_index] = htobe16(ifv.u.VID);
+		}
+	}
+
+	close(fd);
+	freeifaddrs(ifaces);
+
+	*vlan_map = map;
+	*vlan_map_max = map_size;
+
+	return KNOT_EOK;
+}
+
+_public_
+knot_xdp_mode_t knot_eth_xdp_mode(int if_index)
+{
+#if USE_LIBXDP
+	struct bpf_xdp_query_opts info = { .sz = sizeof(info) };
+	int ret = bpf_xdp_query(if_index, 0, &info);
+#else
+	struct xdp_link_info info;
+	int ret = bpf_get_link_xdp_info(if_index, &info, sizeof(info), 0);
+#endif
+	if (ret != 0) {
+		return KNOT_XDP_MODE_NONE;
+	}
+
+	switch (info.attach_mode) {
+	case XDP_ATTACHED_DRV:
+	case XDP_ATTACHED_HW:
+		return KNOT_XDP_MODE_FULL;
+	case XDP_ATTACHED_SKB:
+		return KNOT_XDP_MODE_EMUL;
+	default:
+		return KNOT_XDP_MODE_NONE;
+	}
+}
diff --git a/src/libknot/xdp/eth.h b/src/libknot/xdp/eth.h
new file mode 100644
index 0000000..8c5b901
--- /dev/null
+++ b/src/libknot/xdp/eth.h
@@ -0,0 +1,111 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Ethernet device info interface.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <stddef.h>
+#include <stdint.h>
+
+#define KNOT_XDP_MAX_MTU 1790
+
+/*!
+ * \brief Get number of combined queues of a network interface.
+ *
+ * \param devname  Name of the ethdev (e.g. eth1).
+ *
+ * \retval < 0   KNOT_E* if error.
+ * \retval 1     Default no of queues if the dev does not support.
+ * \return > 0   Number of queues.
+ */
+int knot_eth_queues(const char *devname);
+
+/*!
+ * \brief Network card RSS configuration.
+ */
+typedef struct {
+	size_t table_size; /*!< Size of indirection table in four-bytes. */
+	size_t key_size;   /*!< Size of the RSS key in bytes. */
+	uint32_t mask;     /*!< Input mask for accessing the table. */
+	uint32_t data[];   /*!< Serialized key and table. */
+} knot_eth_rss_conf_t;
+
+/*!
+ * \brief Get RSS configuration of a network interface.
+ *
+ * \param devname   Name of the ethdev (e.g. eth1).
+ * \param rss_conf  Output RSS configuration. Must be freed explicitly.
+ *
+ * \return KNOT_E*
+ */
+int knot_eth_rss(const char *devname, knot_eth_rss_conf_t **rss_conf);
+
+/*!
+ * \brief Get value of MTU setup on a network interface.
+ *
+ * \param devname  Name of the ethdev (e.g. eth1).
+ *
+ * \retval < 0    KNOT_E* if error.
+ * \return >= 0   Interface MTU.
+ */
+int knot_eth_mtu(const char *devname);
+
+/*!
+ * \brief Get the corresponding network interface name for the address.
+ *
+ * \param addr     Address of the interface.
+ * \param out      Output buffer for the interface name.
+ * \param out_len  Size of the output buffer.
+ *
+ * \return KNOT_E*
+ */
+int knot_eth_name_from_addr(const struct sockaddr_storage *addr, char *out,
+                            size_t out_len);
+
+/*!
+ * \brief Get the mapping of interface index to VLAN tags.
+ *
+ * \param vlan_map       Output array of the mappings.
+ * \param vlan_map_max   Maximum interface index allowed.
+ *
+ * \return KNOT_E*
+ */
+int knot_eth_vlans(uint16_t *vlan_map[], uint16_t *vlan_map_max);
+
+typedef enum {
+	KNOT_XDP_MODE_NONE, /*!< XDP not available, BPF not loaded, or error. */
+	KNOT_XDP_MODE_FULL, /*!< Full XDP support in driver or HW. */
+	KNOT_XDP_MODE_EMUL, /*!< Emulated XDP support. */
+} knot_xdp_mode_t;
+
+/*!
+ * \brief Return the current XDP mode of a network interface.
+ *
+ * \param if_index  Index of the interface, output from if_nametoindex().
+ *
+ * \return Current XDP mode.
+ */
+knot_xdp_mode_t knot_eth_xdp_mode(int if_index);
+
+/*! @} */
diff --git a/src/libknot/xdp/msg.h b/src/libknot/xdp/msg.h
new file mode 100644
index 0000000..f567921
--- /dev/null
+++ b/src/libknot/xdp/msg.h
@@ -0,0 +1,62 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief XDP message description.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <linux/if_ether.h>
+#include <netinet/in.h>
+#include <sys/uio.h>
+
+/*! \brief Message flags. */
+typedef enum {
+	KNOT_XDP_MSG_IPV6  = (1 << 0), /*!< This packet is a IPv6 (IPv4 otherwise). */
+	KNOT_XDP_MSG_TCP   = (1 << 1), /*!< This packet is a TCP (UDP otherwise). */
+	KNOT_XDP_MSG_SYN   = (1 << 2), /*!< SYN flag set (TCP only). */
+	KNOT_XDP_MSG_ACK   = (1 << 3), /*!< ACK flag set (TCP only). */
+	KNOT_XDP_MSG_FIN   = (1 << 4), /*!< FIN flag set (TCP only). */
+	KNOT_XDP_MSG_RST   = (1 << 5), /*!< RST flag set (TCP only). */
+	KNOT_XDP_MSG_MSS   = (1 << 6), /*!< MSS option in TCP header (TCP only). */
+	KNOT_XDP_MSG_WSC   = (1 << 7), /*!< Window Scale option in TCP header. */
+	KNOT_XDP_MSG_VLAN  = (1 << 8), /*!< This packet will contain VLAN header. */
+} knot_xdp_msg_flag_t;
+
+/*! \brief Packet description with src & dst MAC & IP addrs + DNS payload. */
+typedef struct knot_xdp_msg {
+	struct sockaddr_in6 ip_from;
+	struct sockaddr_in6 ip_to;
+	uint8_t eth_from[ETH_ALEN];
+	uint8_t eth_to[ETH_ALEN];
+	knot_xdp_msg_flag_t flags;
+	struct iovec payload;
+	uint32_t seqno;
+	uint32_t ackno;
+	uint16_t mss;
+	uint16_t win;
+	uint8_t win_scale;
+	uint16_t vlan_tci;
+} knot_xdp_msg_t;
+
+/*! @} */
diff --git a/src/libknot/xdp/msg_init.h b/src/libknot/xdp/msg_init.h
new file mode 100644
index 0000000..8b96129
--- /dev/null
+++ b/src/libknot/xdp/msg_init.h
@@ -0,0 +1,74 @@
+/*  Copyright (C) 2022 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 <string.h>
+
+#include "libknot/xdp/msg.h"
+#include "libknot/xdp/tcp.h"
+#include "libdnssec/random.h"
+
+inline static bool empty_msg(const knot_xdp_msg_t *msg)
+{
+	const unsigned tcp_flags = KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_ACK |
+	                           KNOT_XDP_MSG_FIN | KNOT_XDP_MSG_RST;
+
+	return (msg->payload.iov_len == 0 && !(msg->flags & tcp_flags));
+}
+
+inline static void msg_init_base(knot_xdp_msg_t *msg, knot_xdp_msg_flag_t flags)
+{
+	memset(msg, 0, sizeof(*msg));
+
+	msg->flags = flags;
+}
+
+inline static void msg_init(knot_xdp_msg_t *msg, knot_xdp_msg_flag_t flags)
+{
+	msg_init_base(msg, flags);
+
+	if (flags & KNOT_XDP_MSG_TCP) {
+		msg->ackno = 0;
+		msg->seqno = dnssec_random_uint32_t();
+		if (flags & KNOT_XDP_MSG_SYN) {
+			msg->flags |= KNOT_XDP_MSG_MSS | KNOT_XDP_MSG_WSC;
+		}
+	}
+}
+
+inline static void msg_init_reply(knot_xdp_msg_t *msg, const knot_xdp_msg_t *query)
+{
+	msg_init_base(msg, query->flags & (KNOT_XDP_MSG_IPV6 | KNOT_XDP_MSG_TCP |
+	                                   KNOT_XDP_MSG_MSS | KNOT_XDP_MSG_WSC));
+
+	memcpy(msg->eth_from, query->eth_to,   ETH_ALEN);
+	memcpy(msg->eth_to,   query->eth_from, ETH_ALEN);
+
+	memcpy(&msg->ip_from, &query->ip_to,   sizeof(msg->ip_from));
+	memcpy(&msg->ip_to,   &query->ip_from, sizeof(msg->ip_to));
+
+	msg->vlan_tci = query->vlan_tci;
+
+	if (msg->flags & KNOT_XDP_MSG_TCP) {
+		msg->ackno = knot_tcp_next_seqno(query);
+		msg->seqno = query->ackno;
+		if (msg->seqno == 0) {
+			msg->seqno = dnssec_random_uint32_t();
+		}
+	}
+}
diff --git a/src/libknot/xdp/protocols.h b/src/libknot/xdp/protocols.h
new file mode 100644
index 0000000..ab1cff4
--- /dev/null
+++ b/src/libknot/xdp/protocols.h
@@ -0,0 +1,446 @@
+/*  Copyright (C) 2022 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 <linux/ip.h>
+#include <linux/ipv6.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <string.h>
+
+#include "libknot/endian.h"
+#include "libknot/xdp/bpf-consts.h"
+#include "libknot/xdp/msg.h"
+
+/* Don't fragment flag. */
+#define	IP_DF 0x4000
+
+#define HDR_8021Q_LEN 4;
+
+/*
+ * Following prot_read_*() functions do not check sanity of parsed packet.
+ * Broken packets have to be dropped by BPF filter prior getting here.
+ */
+
+inline static void *prot_read_udp(void *data, uint16_t *src_port, uint16_t *dst_port)
+{
+	const struct udphdr *udp = data;
+
+	*src_port = udp->source;
+	*dst_port = udp->dest;
+
+	return data + sizeof(*udp);
+}
+
+enum {
+	PROT_TCP_OPT_ENDOP = 0,
+	PROT_TCP_OPT_NOOP  = 1,
+	PROT_TCP_OPT_MSS   = 2,
+	PROT_TCP_OPT_WSC   = 3, // window scale
+
+	PROT_TCP_OPT_LEN_MSS = 4,
+	PROT_TCP_OPT_LEN_WSC = 3,
+};
+
+inline static void *prot_read_tcp(void *data, knot_xdp_msg_t *msg, uint16_t *src_port, uint16_t *dst_port)
+{
+	const struct tcphdr *tcp = data;
+
+	msg->flags |= KNOT_XDP_MSG_TCP;
+
+	if (tcp->syn) {
+		msg->flags |= KNOT_XDP_MSG_SYN;
+	}
+	if (tcp->ack) {
+		msg->flags |= KNOT_XDP_MSG_ACK;
+	}
+	if (tcp->fin) {
+		msg->flags |= KNOT_XDP_MSG_FIN;
+	}
+	if (tcp->rst) {
+		msg->flags |= KNOT_XDP_MSG_RST;
+	}
+
+	msg->seqno = be32toh(tcp->seq);
+	msg->ackno = be32toh(tcp->ack_seq);
+	msg->win = be16toh(tcp->window);
+
+	*src_port = tcp->source;
+	*dst_port = tcp->dest;
+
+	uint8_t *opts = data + sizeof(*tcp), *hdr_end = data + tcp->doff * 4;
+	while (opts < hdr_end) {
+		if (opts[0] == PROT_TCP_OPT_ENDOP || opts[0] == PROT_TCP_OPT_NOOP) {
+			opts++;
+			continue;
+		}
+
+		if (opts + 1 > hdr_end || opts + opts[1] > hdr_end) {
+			// Malformed option.
+			break;
+		}
+
+		if (opts[0] == PROT_TCP_OPT_MSS && opts[1] == PROT_TCP_OPT_LEN_MSS) {
+			msg->flags |= KNOT_XDP_MSG_MSS;
+			memcpy(&msg->mss, &opts[2], sizeof(msg->mss));
+			msg->mss = be16toh(msg->mss);
+		}
+
+		if (opts[0] == PROT_TCP_OPT_WSC && opts[1] == PROT_TCP_OPT_LEN_WSC) {
+			msg->flags |= KNOT_XDP_MSG_WSC;
+			msg->win_scale = opts[2];
+		}
+
+		opts += opts[1];
+	}
+
+	return hdr_end;
+}
+
+inline static void *prot_read_ipv4(void *data, knot_xdp_msg_t *msg, void **data_end)
+{
+	const struct iphdr *ip4 = data;
+
+	// Conditions ensured by the BPF filter.
+	assert(ip4->version == 4);
+	assert(ip4->frag_off == 0 || ip4->frag_off == __constant_htons(IP_DF));
+	// IPv4 header checksum is not verified!
+
+	struct sockaddr_in *src = (struct sockaddr_in *)&msg->ip_from;
+	struct sockaddr_in *dst = (struct sockaddr_in *)&msg->ip_to;
+	memcpy(&src->sin_addr, &ip4->saddr, sizeof(src->sin_addr));
+	memcpy(&dst->sin_addr, &ip4->daddr, sizeof(dst->sin_addr));
+	src->sin_family = AF_INET;
+	dst->sin_family = AF_INET;
+
+	*data_end = data + be16toh(ip4->tot_len);
+	data += ip4->ihl * 4;
+
+	if (ip4->protocol == IPPROTO_TCP) {
+		return prot_read_tcp(data, msg, &src->sin_port, &dst->sin_port);
+	} else {
+		assert(ip4->protocol == IPPROTO_UDP);
+		return prot_read_udp(data, &src->sin_port, &dst->sin_port);
+	}
+}
+
+inline static void *prot_read_ipv6(void *data, knot_xdp_msg_t *msg, void **data_end)
+{
+	const struct ipv6hdr *ip6 = data;
+
+	msg->flags |= KNOT_XDP_MSG_IPV6;
+
+	// Conditions ensured by the BPF filter.
+	assert(ip6->version == 6);
+
+	struct sockaddr_in6 *src = (struct sockaddr_in6 *)&msg->ip_from;
+	struct sockaddr_in6 *dst = (struct sockaddr_in6 *)&msg->ip_to;
+	memcpy(&src->sin6_addr, &ip6->saddr, sizeof(src->sin6_addr));
+	memcpy(&dst->sin6_addr, &ip6->daddr, sizeof(dst->sin6_addr));
+	src->sin6_family = AF_INET6;
+	dst->sin6_family = AF_INET6;
+	src->sin6_flowinfo = 0;
+	dst->sin6_flowinfo = 0;
+	// Scope ID is ignored.
+
+	data += sizeof(*ip6);
+	*data_end = data + be16toh(ip6->payload_len);
+
+	if (ip6->nexthdr == IPPROTO_TCP) {
+		return prot_read_tcp(data, msg, &src->sin6_port, &dst->sin6_port);
+	} else {
+		assert(ip6->nexthdr == IPPROTO_UDP);
+		return prot_read_udp(data, &src->sin6_port, &dst->sin6_port);
+	}
+}
+
+inline static void *prot_read_eth(void *data, knot_xdp_msg_t *msg, void **data_end,
+                                  const uint16_t *vlan_map, unsigned vlan_map_max)
+{
+	const struct ethhdr *eth = data;
+	knot_xdp_info_t *info = data - KNOT_XDP_PKT_ALIGNMENT - sizeof(*info);
+
+	memcpy(msg->eth_from, eth->h_source, ETH_ALEN);
+	memcpy(msg->eth_to,   eth->h_dest,   ETH_ALEN);
+	msg->flags = 0;
+
+	if (eth->h_proto == __constant_htons(ETH_P_8021Q)) {
+		if (info->out_if_index > 0 && info->out_if_index <= vlan_map_max) {
+			assert(vlan_map);
+			msg->vlan_tci = vlan_map[info->out_if_index];
+		} else {
+			memcpy(&msg->vlan_tci, data + sizeof(*eth), sizeof(msg->vlan_tci));
+		}
+		data += HDR_8021Q_LEN;
+		eth = data;
+	}
+
+	data += sizeof(*eth);
+
+	if (eth->h_proto == __constant_htons(ETH_P_IPV6)) {
+		return prot_read_ipv6(data, msg, data_end);
+	} else {
+		assert(eth->h_proto == __constant_htons(ETH_P_IP));
+		return prot_read_ipv4(data, msg, data_end);
+	}
+}
+
+inline static size_t prot_write_hdrs_len(const knot_xdp_msg_t *msg)
+{
+	size_t res = sizeof(struct ethhdr) + sizeof(struct iphdr) + sizeof(struct udphdr);
+
+	if (msg->vlan_tci != 0 || msg->flags & KNOT_XDP_MSG_VLAN) {
+		res += HDR_8021Q_LEN;
+	}
+
+	if (msg->flags & KNOT_XDP_MSG_IPV6) {
+		res += sizeof(struct ipv6hdr) - sizeof(struct iphdr);
+	}
+
+	if (msg->flags & KNOT_XDP_MSG_TCP) {
+		res += sizeof(struct tcphdr) - sizeof(struct udphdr);
+
+		if (msg->flags & KNOT_XDP_MSG_MSS) {
+			res += PROT_TCP_OPT_LEN_MSS;
+		}
+		if (msg->flags & KNOT_XDP_MSG_WSC) {
+			res += PROT_TCP_OPT_LEN_WSC + 1; // 1 == align
+		}
+	}
+
+	return res;
+}
+
+/* Checksum endianness implementation notes for ipv4_checksum() and checksum().
+ *
+ * The basis for checksum is addition on big-endian 16-bit words, with bit 16 carrying
+ * over to bit 0.  That can be viewed as first byte carrying to the second and the
+ * second one carrying back to the first one, i.e. a symmetrical situation.
+ * Therefore the result is the same even when arithmetics is done on little-endian (!)
+ */
+
+inline static void checksum(uint32_t *result, const void *_data, uint32_t _data_len)
+{
+	assert(!(_data_len & 1));
+	const uint16_t *data = _data;
+	uint32_t len = _data_len / 2;
+	while (len-- > 0) {
+		*result += *data++;
+	}
+}
+
+inline static void checksum_uint16(uint32_t *result, uint16_t x)
+{
+	checksum(result, &x, sizeof(x));
+}
+
+inline static void checksum_payload(uint32_t *result, void *payload, size_t pay_len)
+{
+	if (pay_len & 1) {
+		((uint8_t *)payload)[pay_len++] = 0;
+	}
+	checksum(result, payload, pay_len);
+}
+
+inline static uint16_t checksum_finish(uint32_t result, bool nonzero)
+{
+	while (result > 0xffff) {
+		result = (result & 0xffff) + (result >> 16);
+	}
+	if (!nonzero || result != 0xffff) {
+		result = ~result;
+	}
+	return result;
+}
+
+inline static void prot_write_udp(void *data, const knot_xdp_msg_t *msg, void *data_end,
+                                  uint16_t src_port, uint16_t dst_port, uint32_t chksum)
+{
+	struct udphdr *udp = data;
+
+	udp->len    = htobe16(data_end - data);
+	udp->source = src_port;
+	udp->dest   = dst_port;
+
+	if (msg->flags & KNOT_XDP_MSG_IPV6) {
+		udp->check = 0;
+		checksum(&chksum, &udp->len, sizeof(udp->len));
+		checksum_uint16(&chksum, htobe16(IPPROTO_UDP));
+		checksum_payload(&chksum, data, data_end - data);
+		udp->check = checksum_finish(chksum, true);
+	} else {
+		udp->check = 0; // UDP over IPv4 doesn't require checksum.
+	}
+
+	assert(data + sizeof(*udp) == msg->payload.iov_base);
+}
+
+inline static void prot_write_tcp(void *data, const knot_xdp_msg_t *msg, void *data_end,
+                                  uint16_t src_port, uint16_t dst_port, uint32_t chksum,
+                                  uint16_t mss)
+{
+	struct tcphdr *tcp = data;
+
+	tcp->source  = src_port;
+	tcp->dest    = dst_port;
+	tcp->seq     = htobe32(msg->seqno);
+	tcp->ack_seq = htobe32(msg->ackno);
+	tcp->window  = htobe16(msg->win);
+	tcp->check   = 0; // Temporarily initialize before checksum calculation.
+
+	tcp->syn = ((msg->flags & KNOT_XDP_MSG_SYN) ? 1 : 0);
+	tcp->ack = ((msg->flags & KNOT_XDP_MSG_ACK) ? 1 : 0);
+	tcp->fin = ((msg->flags & KNOT_XDP_MSG_FIN) ? 1 : 0);
+	tcp->rst = ((msg->flags & KNOT_XDP_MSG_RST) ? 1 : 0);
+
+	uint8_t *hdr_end = data + sizeof(*tcp);
+	if (msg->flags & KNOT_XDP_MSG_WSC) {
+		hdr_end[0] = PROT_TCP_OPT_WSC;
+		hdr_end[1] = PROT_TCP_OPT_LEN_WSC;
+		hdr_end[2] = msg->win_scale;
+		hdr_end += PROT_TCP_OPT_LEN_WSC;
+		*hdr_end++ = PROT_TCP_OPT_NOOP; // align
+	}
+	if (msg->flags & KNOT_XDP_MSG_MSS) {
+		mss = htobe16(mss);
+		hdr_end[0] = PROT_TCP_OPT_MSS;
+		hdr_end[1] = PROT_TCP_OPT_LEN_MSS;
+		memcpy(&hdr_end[2], &mss, sizeof(mss));
+		hdr_end += PROT_TCP_OPT_LEN_MSS;
+	}
+
+	tcp->psh = ((data_end - (void *)hdr_end > 0) ? 1 : 0);
+	tcp->doff = (hdr_end - (uint8_t *)tcp) / 4;
+	assert((hdr_end - (uint8_t *)tcp) % 4 == 0);
+
+	checksum_uint16(&chksum, htobe16(IPPROTO_TCP));
+	checksum_uint16(&chksum, htobe16(data_end - data));
+	checksum_payload(&chksum, data, data_end - data);
+	tcp->check = checksum_finish(chksum, false);
+
+	assert(hdr_end == msg->payload.iov_base);
+}
+
+inline static uint16_t from32to16(uint32_t sum)
+{
+	sum = (sum & 0xffff) + (sum >> 16);
+	sum = (sum & 0xffff) + (sum >> 16);
+	return sum;
+}
+
+inline static uint16_t ipv4_checksum(const uint16_t *ipv4_hdr)
+{
+	uint32_t sum32 = 0;
+	for (int i = 0; i < 10; ++i) {
+		if (i != 5) {
+			sum32 += ipv4_hdr[i];
+		}
+	}
+	return ~from32to16(sum32);
+}
+
+inline static void prot_write_ipv4(void *data, const knot_xdp_msg_t *msg,
+                                   void *data_end, uint16_t tcp_mss)
+{
+	struct iphdr *ip4 = data;
+
+	ip4->version  = 4;
+	ip4->ihl      = sizeof(*ip4) / 4;
+	ip4->tos      = 0;
+	ip4->tot_len  = htobe16(data_end - data);
+	ip4->id       = 0;
+	ip4->frag_off = 0;
+	ip4->ttl      = IPDEFTTL;
+	ip4->protocol = ((msg->flags & KNOT_XDP_MSG_TCP) ? IPPROTO_TCP : IPPROTO_UDP);
+
+	const struct sockaddr_in *src = (const struct sockaddr_in *)&msg->ip_from;
+	const struct sockaddr_in *dst = (const struct sockaddr_in *)&msg->ip_to;
+	memcpy(&ip4->saddr, &src->sin_addr, sizeof(src->sin_addr));
+	memcpy(&ip4->daddr, &dst->sin_addr, sizeof(dst->sin_addr));
+
+	ip4->check = ipv4_checksum(data);
+
+	data += sizeof(*ip4);
+
+	if (msg->flags & KNOT_XDP_MSG_TCP) {
+		uint32_t chk = 0;
+		checksum(&chk, &src->sin_addr, sizeof(src->sin_addr));
+		checksum(&chk, &dst->sin_addr, sizeof(dst->sin_addr));
+
+		prot_write_tcp(data, msg, data_end, src->sin_port, dst->sin_port, chk, tcp_mss);
+	} else {
+		prot_write_udp(data, msg, data_end, src->sin_port, dst->sin_port, 0); // IPv4/UDP requires no checksum
+	}
+}
+
+inline static void prot_write_ipv6(void *data, const knot_xdp_msg_t *msg,
+                                   void *data_end, uint16_t tcp_mss)
+{
+	struct ipv6hdr *ip6 = data;
+
+	ip6->version     = 6;
+	ip6->priority    = 0;
+	ip6->payload_len = htobe16(data_end - data - sizeof(*ip6));
+	ip6->nexthdr     = ((msg->flags & KNOT_XDP_MSG_TCP) ? IPPROTO_TCP : IPPROTO_UDP);
+	ip6->hop_limit   = IPDEFTTL;
+
+	memset(ip6->flow_lbl, 0, sizeof(ip6->flow_lbl));
+
+	const struct sockaddr_in6 *src = (const struct sockaddr_in6 *)&msg->ip_from;
+	const struct sockaddr_in6 *dst = (const struct sockaddr_in6 *)&msg->ip_to;
+	memcpy(&ip6->saddr, &src->sin6_addr, sizeof(src->sin6_addr));
+	memcpy(&ip6->daddr, &dst->sin6_addr, sizeof(dst->sin6_addr));
+
+	data += sizeof(*ip6);
+
+	uint32_t chk = 0;
+	checksum(&chk, &src->sin6_addr, sizeof(src->sin6_addr));
+	checksum(&chk, &dst->sin6_addr, sizeof(dst->sin6_addr));
+
+	if (msg->flags & KNOT_XDP_MSG_TCP) {
+		prot_write_tcp(data, msg, data_end, src->sin6_port, dst->sin6_port, chk, tcp_mss);
+	} else {
+		prot_write_udp(data, msg, data_end, src->sin6_port, dst->sin6_port, chk);
+	}
+}
+
+inline static void prot_write_eth(void *data, const knot_xdp_msg_t *msg,
+                                  void *data_end, uint16_t tcp_mss)
+{
+	struct ethhdr *eth = data;
+
+	memcpy(eth->h_source, msg->eth_from, ETH_ALEN);
+	memcpy(eth->h_dest,   msg->eth_to,   ETH_ALEN);
+
+	if (msg->vlan_tci != 0) {
+		eth->h_proto = __constant_htons(ETH_P_8021Q);
+		memcpy(data + sizeof(*eth), &msg->vlan_tci, sizeof(msg->vlan_tci));
+		data += HDR_8021Q_LEN;
+		eth = data;
+	}
+
+	data += sizeof(*eth);
+
+	if (msg->flags & KNOT_XDP_MSG_IPV6) {
+		eth->h_proto = __constant_htons(ETH_P_IPV6);
+		prot_write_ipv6(data, msg, data_end, tcp_mss);
+	} else {
+		eth->h_proto = __constant_htons(ETH_P_IP);
+		prot_write_ipv4(data, msg, data_end, tcp_mss);
+	}
+}
diff --git a/src/libknot/xdp/quic.c b/src/libknot/xdp/quic.c
new file mode 100644
index 0000000..f12a47c
--- /dev/null
+++ b/src/libknot/xdp/quic.c
@@ -0,0 +1,1028 @@
+/*  Copyright (C) 2023 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 <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+#include <gnutls/x509.h>
+#include <ngtcp2/ngtcp2.h>
+#include <ngtcp2/ngtcp2_crypto.h>
+#include <ngtcp2/ngtcp2_crypto_gnutls.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+
+#include "libknot/xdp/quic.h"
+
+#include "contrib/macros.h"
+#include "contrib/sockaddr.h"
+#include "contrib/ucw/lists.h"
+#include "libknot/endian.h"
+#include "libdnssec/error.h"
+#include "libdnssec/random.h"
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/error.h"
+#include "libknot/wire.h"
+
+#define SERVER_DEFAULT_SCIDLEN 18
+
+#define QUIC_DEFAULT_VERSION "-VERS-ALL:+VERS-TLS1.3"
+#define QUIC_DEFAULT_CIPHERS "-CIPHER-ALL:+AES-128-GCM:+AES-256-GCM:+CHACHA20-POLY1305:+AES-128-CCM"
+#define QUIC_DEFAULT_GROUPS  "-GROUP-ALL:+GROUP-SECP256R1:+GROUP-X25519:+GROUP-SECP384R1:+GROUP-SECP521R1"
+#define QUIC_PRIORITIES      "%DISABLE_TLS13_COMPAT_MODE:NORMAL:"QUIC_DEFAULT_VERSION":"QUIC_DEFAULT_CIPHERS":"QUIC_DEFAULT_GROUPS
+
+#define XQUIC_SEND_VERSION_NEGOTIATION    NGTCP2_ERR_VERSION_NEGOTIATION
+#define XQUIC_SEND_RETRY                  NGTCP2_ERR_RETRY
+#define XQUIC_SEND_STATELESS_RESET        (-NGTCP2_STATELESS_RESET_TOKENLEN)
+
+#define TLS_CALLBACK_ERR     (-1)
+
+typedef struct knot_quic_creds {
+	gnutls_certificate_credentials_t tls_cert;
+	gnutls_anti_replay_t tls_anti_replay;
+	gnutls_datum_t tls_ticket_key;
+	bool is_clone;
+} knot_xquic_creds_t;
+
+typedef struct knot_quic_session {
+	node_t n;
+	gnutls_datum_t tls_session;
+	ngtcp2_transport_params quic_params;
+} knot_xquic_session_t;
+
+static unsigned addr_len(const struct sockaddr_in6 *ss)
+{
+	return (ss->sin6_family ==  AF_INET6 ?
+	        sizeof(struct sockaddr_in6) : sizeof(struct sockaddr));
+}
+
+_public_
+struct knot_quic_session *knot_xquic_session_save(knot_xquic_conn_t *conn)
+{
+	const ngtcp2_transport_params *tmp = ngtcp2_conn_get_remote_transport_params(conn->conn);
+	if (tmp == NULL) {
+		return NULL;
+	}
+
+	knot_xquic_session_t *session = calloc(1, sizeof(*session));
+	if (session == NULL) {
+		return NULL;
+	}
+
+	int ret = gnutls_session_get_data2(conn->tls_session, &session->tls_session);
+	if (ret != GNUTLS_E_SUCCESS) {
+		free(session);
+		return NULL;
+	}
+
+	memcpy(&session->quic_params, tmp, sizeof(session->quic_params));
+
+	return session;
+}
+
+_public_
+int knot_xquic_session_load(knot_xquic_conn_t *conn, struct knot_quic_session *session)
+{
+	if (session == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = KNOT_EOK;
+	if (conn == NULL) {
+		goto session_free;
+	}
+
+	ret = gnutls_session_set_data(conn->tls_session, session->tls_session.data, session->tls_session.size);
+	if (ret != KNOT_EOK) {
+		goto session_free;
+	}
+
+	ngtcp2_conn_set_early_remote_transport_params(conn->conn, &session->quic_params);
+
+session_free:
+	gnutls_free(session->tls_session.data);
+	free(session);
+	return ret;
+}
+
+static int tls_anti_replay_db_add_func(void *dbf, time_t exp_time,
+                                       const gnutls_datum_t *key,
+                                       const gnutls_datum_t *data)
+{
+	return 0;
+}
+
+static void tls_session_ticket_key_free(gnutls_datum_t *ticket)
+{
+	gnutls_memset(ticket->data, 0, ticket->size);
+	gnutls_free(ticket->data);
+}
+
+static int self_signed_cert(gnutls_certificate_credentials_t tls_cert)
+{
+	gnutls_x509_privkey_t privkey = NULL;
+	gnutls_x509_crt_t cert = NULL;
+	char *hostname = sockaddr_hostname();
+	if (hostname == NULL) {
+		return -ENOMEM;
+	}
+
+	int ret = gnutls_x509_privkey_init(&privkey);
+	if (ret < 0) {
+		free(hostname);
+		return ret;
+	}
+
+	uint8_t serial[16];
+	gnutls_rnd(GNUTLS_RND_NONCE, serial, sizeof(serial));
+	/* clear the left-most bit to avoid signedness confusion: */
+	serial[0] &= 0x8f;
+
+#define CHK(cmd) \
+	ret = (cmd); \
+	if (ret < 0) { goto finish; }
+
+#define now_years(years) (time(NULL) + 365 * 24 * 3600 * (years))
+
+	CHK(gnutls_x509_privkey_generate(privkey, GNUTLS_PK_ECDSA, GNUTLS_CURVE_TO_BITS(GNUTLS_ECC_CURVE_SECP256R1), 0));
+
+	CHK(gnutls_x509_crt_init(&cert));
+	//CHK(gnutls_x509_crt_set_ca_status(cert, 0)); // TODO needed ?
+	CHK(gnutls_x509_crt_set_activation_time(cert, now_years(-1)));
+	CHK(gnutls_x509_crt_set_expiration_time(cert, now_years(20)));
+	CHK(gnutls_x509_crt_set_dn(cert, "CN=DoQ Self-Signed Server Certificate", NULL));
+	CHK(gnutls_x509_crt_set_key(cert, privkey));
+
+	CHK(gnutls_x509_crt_set_serial(cert, serial, sizeof(serial)));
+	CHK(gnutls_x509_crt_set_subject_alt_name(cert, GNUTLS_SAN_DNSNAME, hostname, strlen(hostname), GNUTLS_FSAN_SET));
+	CHK(gnutls_x509_crt_set_version(cert, 3));
+	CHK(gnutls_x509_crt_sign2(cert, cert, privkey, GNUTLS_DIG_SHA256, 0));
+
+	ret = gnutls_certificate_set_x509_key(tls_cert, &cert, 1, privkey);
+
+finish:
+	free(hostname);
+	gnutls_x509_privkey_deinit(privkey);
+	gnutls_x509_crt_deinit(cert);
+
+	return ret;
+}
+
+_public_
+struct knot_quic_creds *knot_xquic_init_creds(bool server, const char *tls_cert,
+                                              const char *tls_key)
+{
+	knot_xquic_creds_t *creds = calloc(1, sizeof(*creds));
+	if (creds == NULL) {
+		return NULL;
+	}
+
+	int ret = gnutls_anti_replay_init(&creds->tls_anti_replay);
+	if (ret != GNUTLS_E_SUCCESS) {
+		goto fail;
+	}
+	gnutls_anti_replay_set_add_function(creds->tls_anti_replay, tls_anti_replay_db_add_func);
+	gnutls_anti_replay_set_ptr(creds->tls_anti_replay, NULL);
+
+	ret = gnutls_certificate_allocate_credentials(&creds->tls_cert);
+	if (ret != GNUTLS_E_SUCCESS) {
+		gnutls_anti_replay_deinit(creds->tls_anti_replay);
+		goto fail;
+	}
+
+	ret = gnutls_certificate_set_x509_system_trust(creds->tls_cert);
+	if (ret < 0) {
+		goto fail2;
+	}
+
+	if ((bool)(tls_cert == NULL) != (bool)(tls_key == NULL) ||
+	    (tls_cert != NULL && !server)) {
+		goto fail2;
+	}
+	if (tls_cert != NULL) {
+		ret = gnutls_certificate_set_x509_key_file(creds->tls_cert, tls_cert, tls_key, GNUTLS_X509_FMT_PEM);
+	} else if (server) {
+		ret = self_signed_cert(creds->tls_cert);
+	}
+	if (ret < 0) {
+		goto fail2;
+	}
+
+	ret = gnutls_session_ticket_key_generate(&creds->tls_ticket_key);
+	if (ret != GNUTLS_E_SUCCESS) {
+		goto fail2;
+	}
+
+	return creds;
+
+fail:
+	free(creds);
+	return NULL;
+fail2:
+	knot_xquic_free_creds(creds);
+	return NULL;
+}
+
+_public_
+void knot_xquic_free_creds(struct knot_quic_creds *creds)
+{
+	if (creds == NULL) {
+		return;
+	}
+
+	if (!creds->is_clone) {
+		gnutls_certificate_free_credentials(creds->tls_cert);
+		if (creds->tls_ticket_key.data != NULL) {
+			tls_session_ticket_key_free(&creds->tls_ticket_key);
+		}
+	}
+	gnutls_anti_replay_deinit(creds->tls_anti_replay);
+	free(creds);
+}
+
+#define ALPN "\03""doq"
+#define ALPN_TMP1 "\07""doq-i11"
+#define ALPN_TMP2 "\07""doq-i03"
+
+static int tls_client_hello_cb(gnutls_session_t session, unsigned int htype,
+                               unsigned when, unsigned int incoming,
+                               const gnutls_datum_t *msg)
+{
+	assert(htype == GNUTLS_HANDSHAKE_CLIENT_HELLO);
+	assert(when == GNUTLS_HOOK_POST);
+
+	if (!incoming) {
+		return 0;
+	}
+
+	gnutls_datum_t alpn;
+	int ret = gnutls_alpn_get_selected_protocol(session, &alpn);
+	if (ret != 0) {
+		return ret;
+	}
+
+	const char *dq = (const char *)&ALPN[1];
+	if (((unsigned int)ALPN[0] != alpn.size ||
+	     memcmp(dq, alpn.data, alpn.size) != 0) &&
+	   ((unsigned int)ALPN_TMP1[0] != alpn.size ||
+	     memcmp((const char *)&ALPN_TMP1[1], alpn.data, alpn.size) != 0) &&
+	   ((unsigned int)ALPN_TMP1[0] != alpn.size ||
+	     memcmp((const char *)&ALPN_TMP2[1], alpn.data, alpn.size) != 0)) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	return 0;
+}
+
+static ngtcp2_conn *get_conn(ngtcp2_crypto_conn_ref *conn_ref)
+{
+	return ((knot_xquic_conn_t *)conn_ref->user_data)->conn;
+}
+
+static int tls_init_conn_session(knot_xquic_conn_t *conn, bool server)
+{
+	if (gnutls_init(&conn->tls_session, (server ? GNUTLS_SERVER : GNUTLS_CLIENT) |
+	                GNUTLS_ENABLE_EARLY_DATA | GNUTLS_NO_AUTO_SEND_TICKET |
+	                GNUTLS_NO_END_OF_EARLY_DATA) != GNUTLS_E_SUCCESS) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	if (gnutls_priority_set_direct(conn->tls_session, QUIC_PRIORITIES,
+	                               NULL) != GNUTLS_E_SUCCESS) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	if (server && gnutls_session_ticket_enable_server(conn->tls_session,
+	                &conn->xquic_table->creds->tls_ticket_key) != GNUTLS_E_SUCCESS) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	gnutls_handshake_set_hook_function(conn->tls_session,
+					   GNUTLS_HANDSHAKE_CLIENT_HELLO,
+	                                   GNUTLS_HOOK_POST, tls_client_hello_cb);
+	int ret = ngtcp2_crypto_gnutls_configure_server_session(conn->tls_session);
+	if (ret != 0) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	gnutls_record_set_max_early_data_size(conn->tls_session, 0xffffffffu);
+
+	conn->conn_ref = (nc_conn_ref_placeholder_t) {
+		.get_conn = get_conn,
+		.user_data = conn
+	};
+
+	_Static_assert(sizeof(nc_conn_ref_placeholder_t) == sizeof(ngtcp2_crypto_conn_ref), "invalid placeholder for conn_ref");
+	gnutls_session_set_ptr(conn->tls_session, &conn->conn_ref);
+
+	if (server) {
+		gnutls_anti_replay_enable(conn->tls_session, conn->xquic_table->creds->tls_anti_replay);
+
+	}
+	if (gnutls_credentials_set(conn->tls_session, GNUTLS_CRD_CERTIFICATE,
+	                           conn->xquic_table->creds->tls_cert) != GNUTLS_E_SUCCESS) {
+		return TLS_CALLBACK_ERR;
+	}
+
+
+	gnutls_datum_t alpn[3] = {
+		{
+			.data = (uint8_t *)(&ALPN[1]),
+			.size = ALPN[0],
+		},
+		{
+			.data = (uint8_t *)(&ALPN_TMP1[1]),
+			.size = ALPN_TMP1[0],
+		},
+		{
+			.data = (uint8_t *)(&ALPN_TMP2[1]),
+			.size = ALPN_TMP2[0],
+		}
+	};
+	gnutls_alpn_set_protocols(conn->tls_session, alpn, 3, 0);
+
+	ngtcp2_conn_set_tls_native_handle(conn->conn, conn->tls_session);
+
+	return KNOT_EOK;
+}
+
+static uint64_t get_timestamp(void)
+{
+	struct timespec ts;
+	if (clock_gettime(CLOCK_MONOTONIC, &ts) != 0) {
+		assert(0);
+	}
+
+	return (uint64_t)ts.tv_sec * NGTCP2_SECONDS + (uint64_t)ts.tv_nsec;
+}
+
+uint64_t xquic_conn_get_timeout(knot_xquic_conn_t *conn)
+{
+	// This effectively obtains the locally configured conn timeout.
+	// It would be possible to obey negotitated idle timeout by employing remote params,
+	// but this would differ per-connection and the whole idea of maintaining
+	// to-be-timeouted connections in simple linear list requires that
+	// the idle timeout is homogeneous among conns.
+	// Anyway, we also violate RFC9000/10.1 (Probe Timeout) for the same reason.
+	// TODO for the future: refactor conn table to use some tree/heap
+	// for to-be-timeouted conns, and use ngtcp2_conn_get_expiry() and
+	// ngtcp2_conn_handle_expiry() appropriately.
+	const ngtcp2_transport_params *params = ngtcp2_conn_get_local_transport_params(conn->conn);
+
+	return conn->last_ts + params->max_idle_timeout;
+}
+
+bool xquic_conn_timeout(knot_xquic_conn_t *conn, uint64_t *now)
+{
+	if (*now == 0) {
+		*now = get_timestamp();
+	}
+	return *now > xquic_conn_get_timeout(conn);
+}
+
+_public_
+uint32_t knot_xquic_conn_rtt(knot_xquic_conn_t *conn)
+{
+	ngtcp2_conn_stat stat = { 0 };
+	ngtcp2_conn_get_conn_stat(conn->conn, &stat);
+	return stat.smoothed_rtt / 1000; // nanosec --> usec
+}
+
+static void knot_quic_rand_cb(uint8_t *dest, size_t destlen, const ngtcp2_rand_ctx *rand_ctx)
+{
+	(void)rand_ctx;
+	dnssec_random_buffer(dest, destlen);
+}
+
+static void init_random_cid(ngtcp2_cid *cid, size_t len)
+{
+	if (len == 0) {
+		len = SERVER_DEFAULT_SCIDLEN;
+	}
+
+	if (dnssec_random_buffer(cid->data, len) != DNSSEC_EOK) {
+		cid->datalen = 0;
+	} else {
+		cid->datalen = len;
+	}
+}
+
+static bool init_unique_cid(ngtcp2_cid *cid, size_t len, knot_xquic_table_t *table)
+{
+	do {
+		if (init_random_cid(cid, len), cid->datalen == 0) {
+			return false;
+		}
+	} while (xquic_table_lookup(cid, table) != NULL);
+	return true;
+}
+
+static int get_new_connection_id(ngtcp2_conn *conn, ngtcp2_cid *cid,
+                                 uint8_t *token, size_t cidlen,
+                                 void *user_data)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	if (!init_unique_cid(cid, cidlen, ctx->xquic_table)) {
+		return NGTCP2_ERR_CALLBACK_FAILURE;
+	}
+
+	knot_xquic_cid_t **addto = xquic_table_insert(ctx, cid, ctx->xquic_table);
+	(void)addto;
+
+	if (token != NULL &&
+	    ngtcp2_crypto_generate_stateless_reset_token(
+	            token, (uint8_t *)ctx->xquic_table->hash_secret,
+	            sizeof(ctx->xquic_table->hash_secret), cid) != 0) {
+		return NGTCP2_ERR_CALLBACK_FAILURE;
+	}
+
+	return 0;
+}
+
+static int remove_connection_id(ngtcp2_conn *conn, const ngtcp2_cid *cid,
+                                void *user_data)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	knot_xquic_cid_t **torem = xquic_table_lookup2(cid, ctx->xquic_table);
+	if (torem != NULL) {
+		assert((*torem)->conn == ctx);
+		xquic_table_rem2(torem, ctx->xquic_table);
+	}
+
+	return 0;
+}
+
+static int handshake_completed_cb(ngtcp2_conn *conn, void *user_data)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	assert(!ctx->handshake_done);
+	ctx->handshake_done = true;
+
+	if (!ngtcp2_conn_is_server(conn)) {
+		return 0;
+	}
+
+	gnutls_datum_t alpn;
+	if (gnutls_alpn_get_selected_protocol(ctx->tls_session, &alpn) != 0) {
+		return NGTCP2_ERR_CALLBACK_FAILURE;
+	}
+	char alpn_str[alpn.size + 1];
+	alpn_str[alpn.size] = '\0';
+	memcpy(alpn_str, alpn.data, alpn.size);
+
+	if (gnutls_session_ticket_send(ctx->tls_session, 1, 0) != GNUTLS_E_SUCCESS) {
+		return TLS_CALLBACK_ERR;
+	}
+
+	uint8_t token[NGTCP2_CRYPTO_MAX_REGULAR_TOKENLEN];
+	ngtcp2_path path = *ngtcp2_conn_get_path(ctx->conn);
+	uint64_t ts = get_timestamp();
+	ngtcp2_ssize tokenlen = ngtcp2_crypto_generate_regular_token(token,
+			(uint8_t *)ctx->xquic_table->hash_secret,
+			sizeof(ctx->xquic_table->hash_secret),
+			path.remote.addr, path.remote.addrlen, ts);
+	if (tokenlen < 0) {
+		return NGTCP2_ERR_CALLBACK_FAILURE;
+	}
+
+	if (ngtcp2_conn_submit_new_token(ctx->conn, token, tokenlen) != 0) {
+		return NGTCP2_ERR_CALLBACK_FAILURE;
+	}
+
+	return 0;
+}
+
+static int recv_stream_data(ngtcp2_conn *conn, uint32_t flags,
+                            int64_t stream_id, uint64_t offset,
+                            const uint8_t *data, size_t datalen,
+                            void *user_data, void *stream_user_data)
+{
+	(void)(stream_user_data); // always NULL
+	(void)(offset); // QUIC shall ensure that data arrive in-order
+
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	int ret = knot_xquic_stream_recv_data(ctx, stream_id, data, datalen, (flags & NGTCP2_STREAM_DATA_FLAG_FIN));
+
+	return ret == KNOT_EOK ? 0 : NGTCP2_ERR_CALLBACK_FAILURE;
+}
+
+static int acked_stream_data_offset_cb(ngtcp2_conn *conn, int64_t stream_id,
+                                    uint64_t offset, uint64_t datalen,
+                                    void *user_data, void *stream_user_data)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+
+	bool keep = !ngtcp2_conn_is_server(conn); // kxdpgun: await incomming reply after query sent&acked
+
+	knot_xquic_stream_ack_data(ctx, stream_id, offset + datalen, keep);
+
+	return 0;
+}
+
+static int stream_closed(ngtcp2_conn *conn, uint32_t flags, int64_t stream_id,
+			 uint64_t app_error_code, void *user_data, void *stream_user_data)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	// NOTE possible error is stored in (flags & NGTCP2_STREAM_CLOSE_FLAG_APP_ERROR_CODE_SET)
+
+	bool keep = !ngtcp2_conn_is_server(conn); // kxdpgun: process incomming reply after recvd&closed
+	if (!keep) {
+		xquic_stream_free(ctx, stream_id);
+	}
+	return 0;
+}
+
+static int recv_stateless_rst(ngtcp2_conn *conn, const ngtcp2_pkt_stateless_reset *sr, void *user_data)
+{
+	// NOTE server can't receive stateless resets, only client
+
+	// ngtcp2 verified stateless reset token already
+	(void)(sr);
+
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	assert(ctx->conn == conn);
+
+	knot_xquic_table_rem(ctx, ctx->xquic_table);
+
+	return 0;
+}
+
+static int recv_stream_rst(ngtcp2_conn *conn, int64_t stream_id, uint64_t final_size,
+                           uint64_t app_error_code, void *user_data, void *stream_user_data)
+{
+	(void)final_size;
+	return stream_closed(conn, NGTCP2_STREAM_CLOSE_FLAG_APP_ERROR_CODE_SET,
+	                     stream_id, app_error_code, user_data, stream_user_data);
+}
+
+static void user_printf(void *user_data, const char *format, ...)
+{
+	knot_xquic_conn_t *ctx = (knot_xquic_conn_t *)user_data;
+	if (ctx->xquic_table->log_cb != NULL) {
+		char buf[256];
+		va_list args;
+		va_start(args, format);
+		vsnprintf(buf, sizeof(buf), format, args);
+		va_end(args);
+		ctx->xquic_table->log_cb(buf);
+	}
+}
+
+static int conn_new(ngtcp2_conn **pconn, const ngtcp2_path *path, const ngtcp2_cid *scid,
+                    const ngtcp2_cid *dcid, const ngtcp2_cid *odcid, uint32_t version,
+                    uint64_t now, size_t udp_pl, uint64_t idle_timeout_ns,
+                    void *user_data, bool server, bool retry_sent)
+{
+	// I. CALLBACKS
+	const ngtcp2_callbacks callbacks = {
+		ngtcp2_crypto_client_initial_cb,
+		ngtcp2_crypto_recv_client_initial_cb,
+		ngtcp2_crypto_recv_crypto_data_cb,
+		handshake_completed_cb,
+		NULL, // recv_version_negotiation not needed on server, nor kxdpgun
+		ngtcp2_crypto_encrypt_cb,
+		ngtcp2_crypto_decrypt_cb,
+		ngtcp2_crypto_hp_mask_cb,
+		recv_stream_data,
+		acked_stream_data_offset_cb,
+		NULL, // stream_opened
+		stream_closed,
+		recv_stateless_rst,
+		ngtcp2_crypto_recv_retry_cb,
+		NULL, // extend_max_streams_bidi
+		NULL, // extend_max_streams_uni
+		knot_quic_rand_cb,
+		get_new_connection_id,
+		remove_connection_id,
+		ngtcp2_crypto_update_key_cb,
+		NULL, // path_validation,
+		NULL, // select_preferred_addr
+		recv_stream_rst,
+		NULL, // extend_max_remote_streams_bidi, might be useful to some allocation optimizations?
+		NULL, // extend_max_remote_streams_uni
+		NULL, // extend_max_stream_data,
+		NULL, // dcid_status
+		NULL, // handshake_confirmed
+		NULL, // recv_new_token
+		ngtcp2_crypto_delete_crypto_aead_ctx_cb,
+		ngtcp2_crypto_delete_crypto_cipher_ctx_cb,
+		NULL, // recv_datagram
+		NULL, // ack_datagram
+		NULL, // lost_datagram
+		ngtcp2_crypto_get_path_challenge_data_cb,
+		NULL, // stream_stop_sending
+		ngtcp2_crypto_version_negotiation_cb,
+		NULL, // recv_rx_key
+		NULL  // recv_tx_key
+	};
+
+	// II. SETTINGS
+	ngtcp2_settings settings;
+	ngtcp2_settings_default(&settings);
+	settings.initial_ts = now;
+	settings.log_printf = user_printf;
+	settings.max_tx_udp_payload_size = udp_pl;
+	settings.qlog.odcid = *odcid;
+	settings.handshake_timeout = idle_timeout_ns; // NOTE setting handshake timeout to idle_timeout for simplicity
+	settings.no_pmtud = true;
+
+	// III. PARAMS
+	ngtcp2_transport_params params;
+	ngtcp2_transport_params_default(&params);
+
+	params.initial_max_data = 786432;
+	params.initial_max_stream_data_bidi_local = 524288;
+	params.initial_max_stream_data_bidi_remote = 524288;
+	params.initial_max_stream_data_uni = 524288;
+
+	// params.initial_max_stream_data_bidi_local = config.max_stream_data_bidi_local;
+	// params.initial_max_stream_data_bidi_remote = config.max_stream_data_bidi_remote;
+	// params.initial_max_stream_data_uni = config.max_stream_data_uni;
+	// params.initial_max_data = config.max_data;
+	params.initial_max_streams_bidi = 100;
+	params.initial_max_streams_uni = 3;
+	params.max_idle_timeout = idle_timeout_ns;
+	// params.stateless_reset_token_present = 1;
+	// params.active_connection_id_limit = 7;
+	if (odcid) {
+		params.original_dcid = *odcid;
+	} else {
+		params.original_dcid = *scid;
+	}
+	if (retry_sent) {
+		params.retry_scid_present = 1;
+		params.retry_scid = *scid;
+	}
+	if (dnssec_random_buffer(params.stateless_reset_token, NGTCP2_STATELESS_RESET_TOKENLEN) != DNSSEC_EOK) {
+		return KNOT_ERROR;
+	}
+
+	if (server) {
+		return ngtcp2_conn_server_new(pconn, dcid, scid, path, version, &callbacks, &settings, &params, NULL, user_data);
+	} else {
+		return ngtcp2_conn_client_new(pconn, dcid, scid, path, version, &callbacks, &settings, &params, NULL, user_data);
+	}
+}
+
+_public_
+int knot_xquic_client(knot_xquic_table_t *table, struct sockaddr_in6 *dest,
+                      struct sockaddr_in6 *via, knot_xquic_conn_t **out_conn)
+{
+	ngtcp2_cid scid = { 0 }, dcid = { 0 };
+	uint64_t now = get_timestamp();
+
+	init_random_cid(&scid, 0);
+	init_random_cid(&dcid, 0);
+
+	knot_xquic_conn_t *xconn = xquic_table_add(NULL, &dcid, table);
+	if (xconn == NULL) {
+		return ENOMEM;
+	}
+	xquic_conn_mark_used(xconn, table, now);
+
+	ngtcp2_path path;
+	path.remote.addr = (struct sockaddr *)dest;
+	path.remote.addrlen = addr_len((const struct sockaddr_in6 *)dest);
+	path.local.addr = (struct sockaddr *)via;
+	path.local.addrlen = addr_len((const struct sockaddr_in6 *)via);
+
+	int ret = conn_new(&xconn->conn, &path, &dcid, &scid, &dcid, NGTCP2_PROTO_VER_V1, now,
+	                   table->udp_payload_limit, 5000000000L, xconn, false, false);
+	if (ret == KNOT_EOK) {
+		ret = tls_init_conn_session(xconn, false);
+	}
+	if (ret == KNOT_EOK) {
+		char *hostname = sockaddr_hostname();
+		if (hostname == NULL) {
+			ret = KNOT_ENOMEM;
+		} else {
+			ret = gnutls_server_name_set(xconn->tls_session, GNUTLS_NAME_DNS,
+			                             hostname, strlen(hostname));
+			free(hostname);
+		}
+	}
+	if (ret != KNOT_EOK) {
+		knot_xquic_table_rem(xconn, table);
+		return ret;
+	}
+
+	*out_conn = xconn;
+	return KNOT_EOK;
+}
+
+_public_
+int knot_xquic_handle(knot_xquic_table_t *table, knot_xdp_msg_t *msg, uint64_t idle_timeout, knot_xquic_conn_t **out_conn)
+{
+	*out_conn = NULL;
+
+	ngtcp2_version_cid decoded_cids = { 0 };
+	ngtcp2_cid scid = { 0 }, dcid = { 0 }, odcid = { 0 };
+	uint64_t now = get_timestamp();
+	int ret = ngtcp2_pkt_decode_version_cid(&decoded_cids,
+	                                        msg->payload.iov_base,
+	                                        msg->payload.iov_len,
+	                                        SERVER_DEFAULT_SCIDLEN);
+	if (ret == NGTCP2_ERR_VERSION_NEGOTIATION) {
+		return -XQUIC_SEND_VERSION_NEGOTIATION;
+	} else if (ret != NGTCP2_NO_ERROR) {
+		return ret;
+	}
+	ngtcp2_cid_init(&dcid, decoded_cids.dcid, decoded_cids.dcidlen);
+	ngtcp2_cid_init(&scid, decoded_cids.scid, decoded_cids.scidlen);
+
+	knot_xquic_conn_t *xconn = xquic_table_lookup(&dcid, table);
+
+	if (decoded_cids.version == 0 /* short header */ && xconn == NULL) {
+		return KNOT_EOK; // NOOP
+	}
+
+	ngtcp2_path path;
+	path.remote.addr = (struct sockaddr *)&msg->ip_from;
+	path.remote.addrlen = addr_len(&msg->ip_from);
+	path.local.addr = (struct sockaddr *)&msg->ip_to;
+	path.local.addrlen = addr_len(&msg->ip_to);
+
+	if (xconn == NULL) {
+		// new conn
+
+		ngtcp2_pkt_hd header = { 0 };
+		ret = ngtcp2_accept(&header, msg->payload.iov_base, msg->payload.iov_len);
+		if (ret == NGTCP2_ERR_RETRY) {
+			return -XQUIC_SEND_RETRY;
+		} else if (ret != NGTCP2_NO_ERROR) { // discard packet
+			return KNOT_EOK;
+		}
+
+		assert(header.type == NGTCP2_PKT_INITIAL);
+		if (header.tokenlen == 0 && xquic_require_retry(table)) {
+			return -XQUIC_SEND_RETRY;
+		}
+
+		if (header.tokenlen > 0) {
+			ret = ngtcp2_crypto_verify_retry_token(
+				&odcid, header.token, header.tokenlen,
+				(const uint8_t *)table->hash_secret, sizeof(table->hash_secret), header.version,
+				(const struct sockaddr *)&msg->ip_from, addr_len(&msg->ip_from),
+				&dcid, idle_timeout, now // NOTE setting retry token validity to idle_timeout for simplicity
+			);
+			if (ret != 0) {
+				return KNOT_EOK;
+			}
+		} else {
+			memcpy(&odcid, &dcid, sizeof(odcid));
+		}
+
+		// server chooses his CID to his liking
+		if (!init_unique_cid(&dcid, 0, table)) {
+			return KNOT_ERROR;
+		}
+
+		xconn = xquic_table_add(NULL, &dcid, table);
+		if (xconn == NULL) {
+			return ENOMEM;
+		}
+		xquic_conn_mark_used(xconn, table, now);
+
+		ret = conn_new(&xconn->conn, &path, &dcid, &scid, &odcid, decoded_cids.version, now,
+		               table->udp_payload_limit, idle_timeout, xconn, true, header.tokenlen > 0);
+		if (ret >= 0) {
+			ret = tls_init_conn_session(xconn, true);
+		}
+		if (ret < 0) {
+			knot_xquic_table_rem(xconn, table);
+			return ret;
+		}
+	}
+
+	ngtcp2_pkt_info pi = { .ecn = NGTCP2_ECN_NOT_ECT, };
+
+	ret = ngtcp2_conn_read_pkt(xconn->conn, &path, &pi, msg->payload.iov_base, msg->payload.iov_len, now);
+
+	*out_conn = xconn;
+	if (ret == NGTCP2_ERR_DRAINING) { // received CONNECTION_CLOSE from the counterpart
+		knot_xquic_table_rem(xconn, table);
+		return KNOT_EOK;
+	} else if(ngtcp2_err_is_fatal(ret)) { // connection doomed
+		knot_xquic_table_rem(xconn, table);
+		return KNOT_ECONN;
+	} else if (ret != NGTCP2_NO_ERROR) { // non-fatal error, discard packet
+		return KNOT_EOK;
+	}
+
+	xquic_conn_mark_used(xconn, table, now);
+
+	return KNOT_EOK;
+}
+
+static bool stream_exists(knot_xquic_conn_t *xconn, int64_t stream_id)
+{
+	// TRICK, we never use stream_user_data
+	return (ngtcp2_conn_set_stream_user_data(xconn->conn, stream_id, NULL) == NGTCP2_NO_ERROR);
+}
+
+static int send_stream(knot_xquic_table_t *quic_table, knot_xdp_socket_t *sock,
+		       knot_xdp_msg_t *in_msg, knot_xquic_conn_t *relay, int64_t stream_id,
+		       uint8_t *data, size_t len, bool fin, ngtcp2_ssize *sent)
+{
+	(void)quic_table;
+	assert(stream_id >= 0 || (data == NULL && len == 0));
+
+	while (stream_id >= 0 && !stream_exists(relay, stream_id)) {
+		int64_t opened = 0;
+		int ret = ngtcp2_conn_open_bidi_stream(relay->conn, &opened, NULL);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		assert((bool)(opened == stream_id) == stream_exists(relay, stream_id));
+	}
+
+	uint32_t xdp_sent = 0;
+	knot_xdp_msg_t out_msg = { 0 };
+	int ret = knot_xdp_reply_alloc(sock, in_msg, &out_msg);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	uint32_t fl = ((stream_id >= 0 && fin) ? NGTCP2_WRITE_STREAM_FLAG_FIN : NGTCP2_WRITE_STREAM_FLAG_NONE);
+	ngtcp2_vec vec = { .base = data, .len = len };
+
+	ret = ngtcp2_conn_writev_stream(relay->conn, NULL, NULL, out_msg.payload.iov_base, out_msg.payload.iov_len,
+	                                sent, fl, stream_id, &vec, (stream_id >= 0 ? 1 : 0), get_timestamp());
+	if (ret <= 0) {
+		knot_xdp_send_free(sock, &out_msg, 1);
+		return ret;
+	}
+	if (*sent < 0) {
+		*sent = 0;
+	}
+
+	out_msg.payload.iov_len = ret;
+	ret = knot_xdp_send(sock, &out_msg, 1, &xdp_sent);
+	if (ret == KNOT_EOK) {
+		assert(xdp_sent == 1);
+		return 1;
+	}
+	return ret;
+}
+
+static int send_special(knot_xquic_table_t *quic_table, knot_xdp_socket_t *sock,
+                        knot_xdp_msg_t *in_msg, int handle_ret)
+{
+	knot_xdp_msg_t out_msg;
+	int ret = knot_xdp_reply_alloc(sock, in_msg, &out_msg);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	uint64_t now = get_timestamp();
+	ngtcp2_version_cid decoded_cids = { 0 };
+	ngtcp2_cid scid = { 0 }, dcid = { 0 };
+
+	int dvc_ret = ngtcp2_pkt_decode_version_cid(&decoded_cids,
+	                                            in_msg->payload.iov_base,
+	                                            in_msg->payload.iov_len,
+	                                            SERVER_DEFAULT_SCIDLEN);
+
+	uint8_t rnd = 0;
+	dnssec_random_buffer(&rnd, sizeof(rnd));
+	uint32_t supported_quic[1] = { NGTCP2_PROTO_VER_V1 };
+	ngtcp2_cid new_dcid;
+	uint8_t retry_token[NGTCP2_CRYPTO_MAX_RETRY_TOKENLEN];
+	uint8_t stateless_reset_token[NGTCP2_STATELESS_RESET_TOKENLEN];
+	uint8_t sreset_rand[NGTCP2_MIN_STATELESS_RESET_RANDLEN];
+	dnssec_random_buffer(sreset_rand, sizeof(sreset_rand));
+
+	switch (handle_ret) {
+	case -XQUIC_SEND_VERSION_NEGOTIATION:
+		if (dvc_ret != NGTCP2_ERR_VERSION_NEGOTIATION) {
+			return KNOT_ERROR;
+		}
+		ret = ngtcp2_pkt_write_version_negotiation(
+			out_msg.payload.iov_base, out_msg.payload.iov_len,
+			rnd, decoded_cids.scid, decoded_cids.scidlen, decoded_cids.dcid,
+			decoded_cids.dcidlen, supported_quic,
+			sizeof(supported_quic) / sizeof(*supported_quic)
+		);
+		break;
+	case -XQUIC_SEND_RETRY:
+		ngtcp2_cid_init(&dcid, decoded_cids.dcid, decoded_cids.dcidlen);
+		ngtcp2_cid_init(&scid, decoded_cids.scid, decoded_cids.scidlen);
+
+		init_random_cid(&new_dcid, 0);
+
+		ret = ngtcp2_crypto_generate_retry_token(
+			retry_token, (const uint8_t *)quic_table->hash_secret, sizeof(quic_table->hash_secret), decoded_cids.version,
+			(const struct sockaddr *)&in_msg->ip_from, sockaddr_len((const struct sockaddr_storage *)&in_msg->ip_from),
+			&new_dcid, &dcid, now
+		);
+
+		if (ret >= 0) {
+			ret = ngtcp2_crypto_write_retry(
+				out_msg.payload.iov_base, out_msg.payload.iov_len,
+				decoded_cids.version, &scid, &new_dcid, &dcid, retry_token, ret
+			);
+		}
+		break;
+	case -XQUIC_SEND_STATELESS_RESET:
+		ret = ngtcp2_pkt_write_stateless_reset(
+			out_msg.payload.iov_base, out_msg.payload.iov_len,
+			stateless_reset_token, sreset_rand, sizeof(sreset_rand)
+		);
+		break;
+	default:
+		ret = KNOT_EINVAL;
+		break;
+	}
+
+	if (ret < 0) {
+		knot_xdp_send_free(sock, &out_msg, 1);
+	} else {
+		uint32_t sent;
+		out_msg.payload.iov_len = ret;
+		ret = knot_xdp_send(sock, &out_msg, 1, &sent);
+	}
+	return ret;
+}
+
+_public_
+int knot_xquic_send(knot_xquic_table_t *quic_table, knot_xquic_conn_t *relay,
+                    knot_xdp_socket_t *sock, knot_xdp_msg_t *in_msg,
+                    int handle_ret, unsigned max_msgs, bool ignore_lastbyte)
+{
+	if (handle_ret < 0) {
+		return handle_ret;
+	} else if (handle_ret > 0) {
+		return send_special(quic_table, sock, in_msg, handle_ret);
+	} else if (relay == NULL) {
+		return KNOT_EINVAL;
+	} else if (relay->conn == NULL) {
+		return KNOT_EOK;
+	}
+
+	unsigned sent_msgs = 0, stream_msgs = 0;
+	int ret = 1;
+	for (int64_t si = 0; si < relay->streams_count && sent_msgs < max_msgs; /* NO INCREMENT */) {
+		int64_t stream_id = 4 * (relay->streams_first + si);
+
+		ngtcp2_ssize sent = 0;
+		size_t uf = relay->streams[si].unsent_offset;
+		knot_xquic_obuf_t *uo = relay->streams[si].unsent_obuf;
+		if (uo == NULL) {
+			si++;
+			continue;
+		}
+
+		bool fin = (((node_t *)uo->node.next)->next == NULL) && !ignore_lastbyte;
+		ret = send_stream(quic_table, sock, in_msg, relay, stream_id,
+		                  uo->buf + uf, uo->len - uf - (ignore_lastbyte ? 1 : 0),
+		                  fin, &sent);
+		if (ret < 0) {
+			return ret;
+		}
+
+		sent_msgs++;
+		stream_msgs++;
+		if (sent > 0 && ignore_lastbyte) {
+			sent++;
+		}
+		if (sent > 0) {
+			knot_xquic_stream_mark_sent(relay, stream_id, sent);
+		}
+
+		if (stream_msgs >= max_msgs / relay->streams_count) {
+			stream_msgs = 0;
+			si++; // if this stream is sending too much, give chance to other streams
+		}
+	}
+
+	while (ret == 1) {
+		ngtcp2_ssize unused = 0;
+		ret = send_stream(quic_table, sock, in_msg, relay, -1, NULL, 0, false, &unused);
+	}
+
+	return ret;
+}
diff --git a/src/libknot/xdp/quic.h b/src/libknot/xdp/quic.h
new file mode 100644
index 0000000..943a2f3
--- /dev/null
+++ b/src/libknot/xdp/quic.h
@@ -0,0 +1,134 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief General QUIC functionality.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/xdp/quic_conn.h"
+#include "libknot/xdp/xdp.h"
+
+struct knot_quic_creds;
+struct knot_quic_session;
+
+/*!
+ * \brief Gets data needed for session resumption.
+ *
+ * \param conn   QUIC connection.
+ *
+ * \return QUIC session context.
+ */
+struct knot_quic_session *knot_xquic_session_save(knot_xquic_conn_t *conn);
+
+/*!
+ * \brief Loads data needed for session resumption.
+ *
+ * \param conn     QUIC connection.
+ * \param session  QUIC session context.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_session_load(knot_xquic_conn_t *conn, struct knot_quic_session *session);
+
+/*!
+ * \brief Init server TLS certificate for DoQ.
+ *
+ * \param server      Initializing for server-side (client otherwise).
+ * \param tls_cert    X509 certificate PEM file path/name.
+ * \param tls_key     Key PEM file path/name.
+ *
+ * \return Initialized creds.
+ */
+struct knot_quic_creds *knot_xquic_init_creds(bool server, const char *tls_cert,
+                                              const char *tls_key);
+
+/*!
+ * \brief Init server TLS certificate for DoQ.
+ */
+void knot_xquic_free_creds(struct knot_quic_creds *creds);
+
+/*!
+ * \brief Returns timeout value for the connection.
+ */
+uint64_t xquic_conn_get_timeout(knot_xquic_conn_t *conn);
+
+/*!
+ * \brief Check if connection timed out due to inactivity.
+ *
+ * \param conn   QUIC connection.
+ * \param now    In/out: current monotonic time. Use zero first and reuse for
+ *               next calls for optimization.
+ *
+ * \return True if the connection timed out idle.
+ */
+bool xquic_conn_timeout(knot_xquic_conn_t *conn, uint64_t *now);
+
+/*!
+ * \brief Returns measured connection RTT in usecs.
+ */
+uint32_t knot_xquic_conn_rtt(knot_xquic_conn_t *conn);
+
+/*!
+ * \brief Create new outgoing QUIC connection.
+ *
+ * \param table       QUIC connections table to be added to.
+ * \param dest        Destination IP address.
+ * \param via         Source IP address.
+ * \param out_conn    Out: new connection.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_client(knot_xquic_table_t *table, struct sockaddr_in6 *dest,
+                      struct sockaddr_in6 *via, knot_xquic_conn_t **out_conn);
+
+/*!
+ * \brief Handle incoming QUIC packet.
+ *
+ * \param table           QUIC connectoins table-
+ * \param msg             Incoming XDP packet.
+ * \param idle_timeout    Configured idle timeout for connections (in nanoseconds).
+ * \param out_conn        Out: QUIC connection that this packet belongs to.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_handle(knot_xquic_table_t *table, knot_xdp_msg_t *msg,
+                      uint64_t idle_timeout, knot_xquic_conn_t **out_conn);
+
+/*!
+ * \brief Send outgoing QUIC packet(s) for a connection.
+ *
+ * \param quic_table         QUIC connection table.
+ * \param relay              QUIC connection.
+ * \param sock               XDP socket.
+ * \param in_msg             Previous incomming packet for this connection.
+ * \param handle_ret         Error returned from knot_xquic_handle() for incoming packet.
+ * \param max_msgs           Maxmimum packets to be sent.
+ * \param ignore_lastbyte    Cut off last byte of QUIC paylod.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_send(knot_xquic_table_t *quic_table, knot_xquic_conn_t *relay,
+                    knot_xdp_socket_t *sock, knot_xdp_msg_t *in_msg,
+                    int handle_ret, unsigned max_msgs, bool ignore_lastbyte);
+
+/*! @} */
diff --git a/src/libknot/xdp/quic_conn.c b/src/libknot/xdp/quic_conn.c
new file mode 100644
index 0000000..40a5d5b
--- /dev/null
+++ b/src/libknot/xdp/quic_conn.c
@@ -0,0 +1,506 @@
+/*  Copyright (C) 2022 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 <gnutls/gnutls.h>
+#include <ngtcp2/ngtcp2.h>
+#include <string.h>
+
+#include "libknot/xdp/quic_conn.h"
+
+#include "contrib/macros.h"
+#include "contrib/openbsd/siphash.h"
+#include "contrib/ucw/lists.h"
+#include "libdnssec/random.h"
+#include "libknot/attribute.h"
+#include "libknot/error.h"
+#include "libknot/xdp/quic.h"
+#include "libknot/xdp/tcp_iobuf.h"
+#include "libknot/wire.h"
+
+#define STREAM_INCR 4 // DoQ only uses client-initiated bi-directional streams, so stream IDs increment by four
+#define BUCKETS_PER_CONNS 8 // Each connecion has several dCIDs, and each CID takes one hash table bucket.
+
+_public_
+knot_xquic_table_t *knot_xquic_table_new(size_t max_conns, size_t max_ibufs, size_t max_obufs,
+                                         size_t udp_payload, struct knot_quic_creds *creds)
+{
+	size_t table_size = max_conns * BUCKETS_PER_CONNS;
+
+	knot_xquic_table_t *res = calloc(1, sizeof(*res) + table_size * sizeof(res->conns[0]));
+	if (res == NULL) {
+		return NULL;
+	}
+
+	res->size = table_size;
+	res->max_conns = max_conns;
+	res->ibufs_max = max_ibufs;
+	res->obufs_max = max_obufs;
+	res->udp_payload_limit = udp_payload;
+	init_list((list_t *)&res->timeout);
+
+	res->creds = creds;
+
+	res->hash_secret[0] = dnssec_random_uint64_t();
+	res->hash_secret[1] = dnssec_random_uint64_t();
+	res->hash_secret[2] = dnssec_random_uint64_t();
+	res->hash_secret[3] = dnssec_random_uint64_t();
+
+	return res;
+}
+
+_public_
+void knot_xquic_table_free(knot_xquic_table_t *table)
+{
+	if (table != NULL) {
+		knot_xquic_conn_t *c, *next;
+		list_t *tto = (list_t *)&table->timeout;
+		WALK_LIST_DELSAFE(c, next, *tto) {
+			knot_xquic_table_rem(c, table);
+			knot_xquic_cleanup(&c, 1);
+		}
+		assert(table->usage == 0);
+		assert(table->pointers == 0);
+		assert(table->obufs_size == 0);
+
+		free(table);
+	}
+}
+
+_public_
+int knot_xquic_table_sweep(knot_xquic_table_t *table, struct knot_sweep_stats *stats)
+{
+	uint64_t now = 0;
+	knot_xquic_conn_t *c, *next;
+	list_t *tto = (list_t *)&table->timeout;
+	WALK_LIST_DELSAFE(c, next, *tto) {
+		if (xquic_conn_timeout(c, &now)) {
+			knot_sweep_stats_incr(stats, KNOT_SWEEP_CTR_TIMEOUT);
+			knot_xquic_table_rem(c, table);
+		} else if (table->usage > table->max_conns) {
+			knot_sweep_stats_incr(stats, KNOT_SWEEP_CTR_LIMIT_CONN);
+			knot_xquic_table_rem(c, table);
+			// NOTE here it would be correct to send Immediate close
+			// with DoQ errcode DOQ_EXCESSIVE_LOAD
+			// nowever, we don't do this for the sake of simplicty
+			// it would be possible to send by using ngtcp2_conn_get_path()...
+			// (also applies to below case)
+		} else if (table->obufs_size > table->obufs_max) {
+			if (c->obufs_size > 0) {
+				knot_sweep_stats_incr(stats, KNOT_SWEEP_CTR_LIMIT_OBUF);
+				knot_xquic_table_rem(c, table);
+			}
+		} else if (table->ibufs_size > table->ibufs_max) {
+			if (c->ibufs_size > 0) {
+				knot_sweep_stats_incr(stats, KNOT_SWEEP_CTR_LIMIT_IBUF);
+				knot_xquic_table_rem(c, table);
+			}
+		} else {
+			break;
+		}
+		knot_xquic_cleanup(&c, 1);
+	}
+	return KNOT_EOK;
+}
+
+static uint64_t cid2hash(const ngtcp2_cid *cid, knot_xquic_table_t *table)
+{
+	SIPHASH_CTX ctx;
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)(table->hash_secret));
+	SipHash24_Update(&ctx, cid->data, MIN(cid->datalen, 8));
+	uint64_t ret = SipHash24_End(&ctx);
+	return ret;
+}
+
+knot_xquic_cid_t **xquic_table_insert(knot_xquic_conn_t *xconn, const ngtcp2_cid *cid,
+                                      knot_xquic_table_t *table)
+{
+	uint64_t hash = cid2hash(cid, table);
+
+	knot_xquic_cid_t *cidobj = malloc(sizeof(*cidobj));
+	if (cidobj == NULL) {
+		return NULL;
+	}
+	_Static_assert(sizeof(*cid) <= sizeof(cidobj->cid_placeholder), "insufficient placeholder for CID struct");
+	memcpy(cidobj->cid_placeholder, cid, sizeof(*cid));
+	cidobj->conn = xconn;
+
+	knot_xquic_cid_t **addto = table->conns + (hash % table->size);
+
+	cidobj->next = *addto;
+	*addto = cidobj;
+	table->pointers++;
+
+	return addto;
+}
+
+knot_xquic_conn_t *xquic_table_add(ngtcp2_conn *conn, const ngtcp2_cid *cid,
+                                   knot_xquic_table_t *table)
+{
+	knot_xquic_conn_t *xconn = calloc(1, sizeof(*xconn));
+	if (xconn == NULL) {
+		return NULL;
+	}
+
+	xconn->conn = conn;
+	xconn->xquic_table = table;
+	xconn->stream_inprocess = -1;
+
+	knot_xquic_cid_t **addto = xquic_table_insert(xconn, cid, table);
+	if (addto == NULL) {
+		free(xconn);
+		return NULL;
+	}
+	table->usage++;
+
+	return xconn;
+}
+
+knot_xquic_cid_t **xquic_table_lookup2(const ngtcp2_cid *cid, knot_xquic_table_t *table)
+{
+	uint64_t hash = cid2hash(cid, table);
+
+	knot_xquic_cid_t **res = table->conns + (hash % table->size);
+	while (*res != NULL && !ngtcp2_cid_eq(cid, (const ngtcp2_cid *)(*res)->cid_placeholder)) {
+		res = &(*res)->next;
+	}
+	return res;
+}
+
+knot_xquic_conn_t *xquic_table_lookup(const ngtcp2_cid *cid, knot_xquic_table_t *table)
+{
+	knot_xquic_cid_t **pcid = xquic_table_lookup2(cid, table);
+	assert(pcid != NULL);
+	return *pcid == NULL ? NULL : (*pcid)->conn;
+}
+
+void xquic_conn_mark_used(knot_xquic_conn_t *conn, knot_xquic_table_t *table,
+                          uint64_t now)
+{
+	node_t *n = (node_t *)&conn->timeout;
+	list_t *l = (list_t *)&table->timeout;
+	if (n->next != NULL) {
+		rem_node(n);
+	}
+	add_tail(l, n);
+	conn->last_ts = now;
+}
+
+void xquic_table_rem2(knot_xquic_cid_t **pcid, knot_xquic_table_t *table)
+{
+	knot_xquic_cid_t *cid = *pcid;
+	*pcid = cid->next;
+	free(cid);
+	table->pointers--;
+}
+
+void xquic_stream_free(knot_xquic_conn_t *xconn, int64_t stream_id)
+{
+	knot_xquic_stream_ack_data(xconn, stream_id, SIZE_MAX, false);
+}
+
+_public_
+void knot_xquic_table_rem(knot_xquic_conn_t *conn, knot_xquic_table_t *table)
+{
+	if (conn->streams_count == -1) { // kxdpgun special
+		conn->streams_count = 1;
+	}
+	for (ssize_t i = conn->streams_count - 1; i >= 0; i--) {
+		xquic_stream_free(conn, (i + conn->streams_first) * 4);
+	}
+	assert(conn->streams_count <= 0);
+	assert(conn->obufs_size == 0);
+
+	size_t num_scid = ngtcp2_conn_get_num_scid(conn->conn);
+	ngtcp2_cid *scids = calloc(num_scid, sizeof(*scids));
+	ngtcp2_conn_get_scid(conn->conn, scids);
+
+	for (size_t i = 0; i < num_scid; i++) {
+		knot_xquic_cid_t **pcid = xquic_table_lookup2(&scids[i], table);
+		assert(pcid != NULL);
+		if (*pcid == NULL) {
+			continue;
+		}
+		assert((*pcid)->conn == conn);
+		xquic_table_rem2(pcid, table);
+	}
+
+	rem_node((node_t *)&conn->timeout);
+
+	free(scids);
+
+	gnutls_deinit(conn->tls_session);
+	ngtcp2_conn_del(conn->conn);
+	conn->conn = NULL;
+
+	table->usage--;
+}
+
+_public_
+knot_xquic_stream_t *knot_xquic_conn_get_stream(knot_xquic_conn_t *xconn,
+                                                int64_t stream_id, bool create)
+{
+	if (stream_id % 4 != 0) {
+		return NULL;
+	}
+	stream_id /= 4;
+
+	if (xconn->streams_first > stream_id) {
+		return NULL;
+	}
+	if (xconn->streams_count > stream_id - xconn->streams_first) {
+		return &xconn->streams[stream_id - xconn->streams_first];
+	}
+
+	if (create) {
+		size_t new_streams_count;
+		knot_xquic_stream_t *new_streams;
+
+		if (xconn->streams_count == 0) {
+			new_streams = malloc(sizeof(new_streams[0]));
+			if (new_streams == NULL) {
+				return NULL;
+			}
+			new_streams_count = 1;
+			xconn->streams_first = stream_id;
+		} else {
+			new_streams_count = stream_id + 1 - xconn->streams_first;
+			if (new_streams_count > MAX_STREAMS_PER_CONN) {
+				return NULL;
+			}
+			new_streams = realloc(xconn->streams, new_streams_count * sizeof(*new_streams));
+			if (new_streams == NULL) {
+				return NULL;
+			}
+		}
+
+		for (knot_xquic_stream_t *si = new_streams;
+		     si < new_streams + xconn->streams_count; si++) {
+			if (si->obufs_size == 0) {
+				init_list((list_t *)&si->outbufs);
+			} else {
+				fix_list((list_t *)&si->outbufs);
+			}
+		}
+
+		for (knot_xquic_stream_t *si = new_streams + xconn->streams_count;
+		     si < new_streams + new_streams_count; si++) {
+			memset(si, 0, sizeof(*si));
+			init_list((list_t *)&si->outbufs);
+		}
+		xconn->streams = new_streams;
+		xconn->streams_count = new_streams_count;
+
+		return &xconn->streams[stream_id - xconn->streams_first];
+	}
+	return NULL;
+}
+
+static void stream_inprocess(knot_xquic_conn_t *xconn, knot_xquic_stream_t *stream)
+{
+	int16_t idx = stream - xconn->streams;
+	assert(idx >= 0);
+	assert(idx < xconn->streams_count);
+	if (xconn->stream_inprocess < 0 || xconn->stream_inprocess > idx) {
+		xconn->stream_inprocess = idx;
+	}
+}
+
+static void stream_outprocess(knot_xquic_conn_t *xconn, knot_xquic_stream_t *stream)
+{
+	if (stream != &xconn->streams[xconn->stream_inprocess]) {
+		return;
+	}
+
+	for (int16_t idx = xconn->stream_inprocess + 1; idx < xconn->streams_count; idx++) {
+		stream = &xconn->streams[idx];
+		if (stream->inbuf_fin != NULL) {
+			xconn->stream_inprocess = stream - xconn->streams;
+			return;
+		}
+	}
+	xconn->stream_inprocess = -1;
+}
+
+int knot_xquic_stream_recv_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                const uint8_t *data, size_t len, bool fin)
+{
+	if (len == 0) {
+		return KNOT_EINVAL;
+	}
+
+	knot_xquic_stream_t *stream = knot_xquic_conn_get_stream(xconn, stream_id, true);
+	if (stream == NULL) {
+		return KNOT_ENOENT;
+	}
+
+	struct iovec in = { (void *)data, len }, *outs;
+	size_t outs_count;
+	int ret = knot_tcp_inbuf_update(&stream->inbuf, in, &outs, &outs_count,
+	                                &xconn->ibufs_size);
+	if (ret != KNOT_EOK || (outs_count == 0 && !fin)) {
+		return ret;
+	}
+	if (outs_count != 1 || !fin) {
+		free(outs);
+		return KNOT_ESEMCHECK;
+	}
+
+	stream->inbuf_fin = outs;
+	stream_inprocess(xconn, stream);
+	return KNOT_EOK;
+}
+
+_public_
+knot_xquic_stream_t *knot_xquic_stream_get_process(knot_xquic_conn_t *xconn,
+                                                   int64_t *stream_id)
+{
+	if (xconn->stream_inprocess < 0) {
+		return NULL;
+	}
+
+	knot_xquic_stream_t *stream = &xconn->streams[xconn->stream_inprocess];
+	*stream_id = (xconn->streams_first + xconn->stream_inprocess) * 4;
+	stream_outprocess(xconn, stream);
+	return stream;
+}
+
+_public_
+uint8_t *knot_xquic_stream_add_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                    uint8_t *data, size_t len)
+{
+	knot_xquic_stream_t *s = knot_xquic_conn_get_stream(xconn, stream_id, true);
+	if (s == NULL) {
+		return NULL;
+	}
+
+	size_t prefix = sizeof(uint16_t);
+
+	knot_xquic_obuf_t *obuf = malloc(sizeof(*obuf) + prefix + len);
+	if (obuf == NULL) {
+		return NULL;
+	}
+
+	obuf->len = len + prefix;
+	knot_wire_write_u16(obuf->buf, len);
+	if (data != NULL) {
+		memcpy(obuf->buf + prefix, data, len);
+	}
+
+	list_t *list = (list_t *)&s->outbufs;
+	if (EMPTY_LIST(*list)) {
+		s->unsent_obuf = obuf;
+	}
+	add_tail((list_t *)&s->outbufs, (node_t *)obuf);
+	s->obufs_size += obuf->len;
+	xconn->obufs_size += obuf->len;
+	xconn->xquic_table->obufs_size += obuf->len;
+
+	return obuf->buf + prefix;
+}
+
+void knot_xquic_stream_ack_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                size_t end_acked, bool keep_stream)
+{
+	knot_xquic_stream_t *s = knot_xquic_conn_get_stream(xconn, stream_id, false);
+	if (s == NULL) {
+		return;
+	}
+
+	list_t *obs = (list_t *)&s->outbufs;
+
+	knot_xquic_obuf_t *first;
+	while (!EMPTY_LIST(*obs) && end_acked >= (first = HEAD(*obs))->len + s->first_offset) {
+		rem_node((node_t *)first);
+		s->obufs_size -= first->len;
+		xconn->obufs_size -= first->len;
+		xconn->xquic_table->obufs_size -= first->len;
+		s->first_offset += first->len;
+		free(first);
+		if (s->unsent_obuf == first) {
+			s->unsent_obuf = EMPTY_LIST(*obs) ? NULL : HEAD(*obs);
+			s->unsent_offset = 0;
+		}
+	}
+
+	if (EMPTY_LIST(*obs) && !keep_stream) {
+		stream_outprocess(xconn, s);
+		memset(s, 0, sizeof(*s));
+		while (s = &xconn->streams[0], s->inbuf.iov_len == 0 && s->inbuf_fin == NULL && s->obufs_size == 0) {
+			assert(xconn->streams_count > 0);
+			xconn->streams_count--;
+
+			if (xconn->streams_count == 0) {
+				free(xconn->streams);
+				xconn->streams = 0;
+				xconn->streams_first = 0;
+				break;
+			} else {
+				xconn->streams_first++;
+				xconn->stream_inprocess--;
+				memmove(s, s + 1, sizeof(*s) * xconn->streams_count);
+				// possible realloc to shrink allocated space, but probably useless
+				for (knot_xquic_stream_t *si = s;  si < s + xconn->streams_count; si++) {
+					if (si->obufs_size == 0) {
+						init_list((list_t *)&si->outbufs);
+					} else {
+						fix_list((list_t *)&si->outbufs);
+					}
+				}
+			}
+		}
+	}
+}
+
+void knot_xquic_stream_mark_sent(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                 size_t amount_sent)
+{
+	knot_xquic_stream_t *s = knot_xquic_conn_get_stream(xconn, stream_id, false);
+	if (s == NULL) {
+		return;
+	}
+
+	s->unsent_offset += amount_sent;
+	assert(s->unsent_offset <= s->unsent_obuf->len);
+	if (s->unsent_offset == s->unsent_obuf->len) {
+		s->unsent_offset = 0;
+		s->unsent_obuf = (knot_xquic_obuf_t *)s->unsent_obuf->node.next;
+		if (s->unsent_obuf->node.next == NULL) { // already behind the tail of list
+			s->unsent_obuf = NULL;
+		}
+	}
+}
+
+_public_
+void knot_xquic_cleanup(knot_xquic_conn_t *conns[], size_t n_conns)
+{
+	for (size_t i = 0; i < n_conns; i++) {
+		if (conns[i] != NULL && conns[i]->conn == NULL) {
+			free(conns[i]);
+			for (size_t j = i + 1; j < n_conns; j++) {
+				if (conns[j] == conns[i]) {
+					conns[j] = NULL;
+				}
+			}
+		}
+	}
+}
+
+bool xquic_require_retry(knot_xquic_table_t *table)
+{
+	(void)table;
+	return false;
+}
diff --git a/src/libknot/xdp/quic_conn.h b/src/libknot/xdp/quic_conn.h
new file mode 100644
index 0000000..20ee176
--- /dev/null
+++ b/src/libknot/xdp/quic_conn.h
@@ -0,0 +1,314 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief QUIC connection management.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <linux/if_ether.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <sys/uio.h>
+
+#define MAX_STREAMS_PER_CONN 10
+
+struct ngtcp2_cid; // declaration taken from wherever in ngtcp2
+struct knot_quic_creds;
+struct knot_sweep_stats;
+
+// those are equivalent to contrib/ucw/lists.h , just must not be included.
+typedef struct knot_xquic_ucw_node {
+	struct knot_xquic_ucw_node *next, *prev;
+} knot_xquic_ucw_node_t;
+typedef struct knot_xquic_ucw_list {
+	knot_xquic_ucw_node_t head, tail;
+} knot_xquic_ucw_list_t;
+
+typedef struct {
+	void *get_conn;
+	void *user_data;
+} nc_conn_ref_placeholder_t;
+
+typedef struct {
+	knot_xquic_ucw_node_t node;
+	size_t len;
+	uint8_t buf[];
+} knot_xquic_obuf_t;
+
+typedef struct {
+	struct iovec inbuf;
+	struct iovec *inbuf_fin;
+	knot_xquic_ucw_list_t outbufs;
+	size_t obufs_size;
+
+	knot_xquic_obuf_t *unsent_obuf;
+	size_t first_offset;
+	size_t unsent_offset;
+} knot_xquic_stream_t;
+
+typedef struct knot_xquic_conn {
+	knot_xquic_ucw_node_t timeout; // MUST be first field of the struct
+	uint64_t last_ts;
+
+	nc_conn_ref_placeholder_t conn_ref; // placeholder for internal struct ngtcp2_crypto_conn_ref
+
+	struct ngtcp2_conn *conn;
+
+	struct gnutls_session_int *tls_session;
+
+	knot_xquic_stream_t *streams;
+	int16_t streams_count; // number of allocated streams structures
+	int16_t stream_inprocess; // index of first stream that has complete incomming data to be processed (aka inbuf_fin)
+	bool handshake_done;
+	bool session_taken; // TODO ... ?
+	int64_t streams_first; // stream_id/4 of first allocated stream
+	size_t ibufs_size;
+	size_t obufs_size;
+
+	struct knot_xquic_table *xquic_table;
+
+	struct knot_xquic_conn *next;
+} knot_xquic_conn_t;
+
+typedef struct knot_xquic_cid {
+	uint8_t cid_placeholder[32];
+	knot_xquic_conn_t *conn;
+	struct knot_xquic_cid *next;
+} knot_xquic_cid_t;
+
+typedef struct knot_xquic_table {
+	size_t size;
+	size_t usage;
+	size_t pointers;
+	size_t max_conns;
+	size_t ibufs_max;
+	size_t obufs_max;
+	size_t ibufs_size;
+	size_t obufs_size;
+	size_t udp_payload_limit; // for simplicity not distinguishing IPv4/6
+	void (*log_cb)(const char *);
+	uint64_t hash_secret[4];
+	struct knot_quic_creds *creds;
+	knot_xquic_ucw_list_t timeout;
+	knot_xquic_cid_t *conns[];
+} knot_xquic_table_t;
+
+/*!
+ * \brief Allocate QUIC connections hash table.
+ *
+ * \param max_conns    Maximum nuber of connections.
+ * \param max_ibufs    Maximum size of buffers for fragmented incomming DNS msgs.
+ * \param max_obufs    Maximum size of buffers for un-ACKed outgoing data.
+ * \param udp_pl       Maximum UDP payload size (both IPv4 and 6).
+ * \param creds        QUIC crypto context..
+ *
+ * \return Allocated table, or NULL.
+ */
+knot_xquic_table_t *knot_xquic_table_new(size_t max_conns, size_t max_ibufs, size_t max_obufs,
+                                         size_t udp_payload, struct knot_quic_creds *creds);
+
+/*!
+ * \brief Free QUIC table including its contents.
+ *
+ * \param table    Table to be freed.
+ */
+void knot_xquic_table_free(knot_xquic_table_t *table);
+
+/*!
+ * \brief Close timed out connections and some oldest ones if table full.
+ *
+ * \param table       QUIC table to be cleaned up.
+ * \param stats       Out: sweep statistics.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_table_sweep(knot_xquic_table_t *table, struct knot_sweep_stats *stats);
+
+/*!
+ * \brief Add new connection/CID link to table.
+ *
+ * \param xconn    QUIC connection linked.
+ * \param cid      New CID to be added.
+ * \param table    QUIC table to be modified.
+ *
+ * \return Pointer on the CID reference in table, or NULL.
+ */
+knot_xquic_cid_t **xquic_table_insert(knot_xquic_conn_t *xconn,
+                                      const struct ngtcp2_cid *cid,
+                                      knot_xquic_table_t *table);
+
+/*!
+ * \brief Add new connection to the table, allocating conn struct.
+ *
+ * \param conn      Ngtcp2 conn struct.
+ * \param cid       CID to be linked (usually oscid for server).
+ * \param table     QUIC table to be modified.
+ *
+ * \return Allocated (and linked) Knot conn struct, or NULL.
+ */
+knot_xquic_conn_t *xquic_table_add(struct ngtcp2_conn *conn,
+                                   const struct ngtcp2_cid *cid,
+                                   knot_xquic_table_t *table);
+
+/*!
+ * \brief Lookup connection/CID link in table.
+ *
+ * \param cid      CID to be searched for.
+ * \param table    QUIC table.
+ *
+ * \return Pointer on the CID reference in table, or NULL.
+ */
+knot_xquic_cid_t **xquic_table_lookup2(const struct ngtcp2_cid *cid,
+                                       knot_xquic_table_t *table);
+
+/*!
+ * \brief Lookup QUIC connection in table.
+ *
+ * \param cid      CID to be searched for.
+ * \param table    QUIC table.
+ *
+ * \return Connection that the CID belongs to, or NULL.
+ */
+knot_xquic_conn_t *xquic_table_lookup(const struct ngtcp2_cid *cid,
+                                      knot_xquic_table_t *table);
+
+/*!
+ * \brief Put the connection on the end of timeout queue.
+ */
+void xquic_conn_mark_used(knot_xquic_conn_t *conn, knot_xquic_table_t *table,
+                          uint64_t now);
+
+/*!
+ * \brief Remove connection/CID link from table.
+ *
+ * \param pcid     CID to be removed.
+ * \param table    QUIC table.
+ */
+void xquic_table_rem2(knot_xquic_cid_t **pcid, knot_xquic_table_t *table);
+
+/*!
+ * \brief Remove specified stream from QUIC connection, freeing all buffers.
+ *
+ * \param xconn         QUIC connection to remove from.
+ * \param stream_id     Stream QUIC ID.
+ */
+void xquic_stream_free(knot_xquic_conn_t *xconn, int64_t stream_id);
+
+/*!
+ * \brief Remove and deinitialize connection completely.
+ *
+ * \param conn      Connection to be removed.
+ * \param table     Table to remove from.
+ */
+void knot_xquic_table_rem(knot_xquic_conn_t *conn, knot_xquic_table_t *table);
+
+/*!
+ * \brief Fetch or initialize a QUIC stream.
+ *
+ * \param xconn          QUIC connection.
+ * \param stream_id      Stream QUIC ID.
+ * \param create         Trigger stream creation if not exists.
+ *
+ * \return Stream or NULL.
+ */
+knot_xquic_stream_t *knot_xquic_conn_get_stream(knot_xquic_conn_t *xconn,
+                                                int64_t stream_id, bool create);
+
+/*!
+ * \brief Process incomming stream data to stream structure.
+ *
+ * \param xconn         QUIC connection that has received data.
+ * \param stream_id     Stream QUIC ID of the incomming data.
+ * \param data          Incomming payload data.
+ * \param len           Incomming payload data length.
+ * \param fin           FIN flag set for incomming data.
+ *
+ * \return KNOT_E*
+ */
+int knot_xquic_stream_recv_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                const uint8_t *data, size_t len, bool fin);
+
+/*!
+ * \brief Get next stream which has pending incomming data to be processed.
+ *
+ * \param xconn        QUIC connection.
+ * \param stream_id    Out: strem QUIC ID of the returned stream.
+ *
+ * \return Stream with incomming data.
+ */
+knot_xquic_stream_t *knot_xquic_stream_get_process(knot_xquic_conn_t *xconn,
+                                                   int64_t *stream_id);
+
+/*!
+ * \brief Add outgiong data to the stream for sending.
+ *
+ * \param xconn         QUIC connection that shall send data.
+ * \param stream_id     Stream ID for outgoing data.
+ * \param data          Data payload.
+ * \param len           Data payload length.
+ *
+ * \return NULL if error, or pinter at the data in outgiong buffer.
+ */
+uint8_t *knot_xquic_stream_add_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                    uint8_t *data, size_t len);
+
+/*!
+ * \brief Mark outgiong data as acknowledged after ACK received.
+ *
+ * \param xconn          QUIC connection that received ACK.
+ * \param stream_id      Stream ID of ACKed data.
+ * \param end_acked      Offset of ACKed data + ACKed length.
+ * \param keep_stream    Don't free the stream even when ACKed all outgoing data.
+ */
+void knot_xquic_stream_ack_data(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                size_t end_acked, bool keep_stream);
+
+/*!
+ * \brief Mark outgoing data as sent.
+ *
+ * \param xconn          QUIC connection that sent data.
+ * \param stream_id      Stream ID of sent data.
+ * \param amount_sent    Length of sent data.
+ */
+void knot_xquic_stream_mark_sent(knot_xquic_conn_t *xconn, int64_t stream_id,
+                                 size_t amount_sent);
+
+/*!
+ * \brief Free rest of resources of closed conns.
+ *
+ * \param conns      Array with recently used conns (possibly NULLs).
+ * \param n_conns    Size of the array.
+ */
+void knot_xquic_cleanup(knot_xquic_conn_t *conns[], size_t n_conns);
+
+/*!
+ * \brief Toggle sending Retry packet as a reaction to Initial packet of new connection.
+ *
+ * \param table       Connection table.
+ *
+ * \return True if instead of continuing handshake, Retry packet shall be sent
+ *              to verify counterpart's address.
+ */
+bool xquic_require_retry(knot_xquic_table_t *table);
+
+/*! @} */
diff --git a/src/libknot/xdp/tcp.c b/src/libknot/xdp/tcp.c
new file mode 100644
index 0000000..752e9ef
--- /dev/null
+++ b/src/libknot/xdp/tcp.c
@@ -0,0 +1,729 @@
+/*  Copyright (C) 2022 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 <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include "libknot/xdp/tcp.h"
+#include "libknot/xdp/tcp_iobuf.h"
+#include "libknot/attribute.h"
+#include "libknot/error.h"
+#include "libdnssec/random.h"
+#include "contrib/macros.h"
+#include "contrib/openbsd/siphash.h"
+#include "contrib/ucw/lists.h"
+
+static uint32_t get_timestamp(void)
+{
+	struct timespec t;
+	clock_gettime(CLOCK_MONOTONIC, &t);
+	uint64_t res = (uint64_t)t.tv_sec * 1000000;
+	res += (uint64_t)t.tv_nsec / 1000;
+	return res & 0xffffffff; // overflow does not matter since we are working with differences
+}
+
+static size_t sockaddr_data_len(const struct sockaddr_in6 *rem, const struct sockaddr_in6 *loc)
+{
+	assert(rem->sin6_family == loc->sin6_family);
+	if (rem->sin6_family == AF_INET) {
+		return offsetof(struct sockaddr_in, sin_zero);
+	} else {
+		assert(rem->sin6_family == AF_INET6);
+		return offsetof(struct sockaddr_in6, sin6_scope_id);
+	}
+}
+
+static uint64_t hash_four_tuple(const struct sockaddr_in6 *rem, const struct sockaddr_in6 *loc,
+                                knot_tcp_table_t *table)
+{
+	size_t socka_data_len = sockaddr_data_len(rem, loc);
+	SIPHASH_CTX ctx;
+	SipHash24_Init(&ctx, (const SIPHASH_KEY *)(table->hash_secret));
+	SipHash24_Update(&ctx, rem, socka_data_len);
+	SipHash24_Update(&ctx, loc, socka_data_len);
+	return SipHash24_End(&ctx);
+}
+
+static list_t *tcp_table_timeout(knot_tcp_table_t *table)
+{
+	return (list_t *)&table->conns[table->size];
+}
+
+static node_t *tcp_conn_node(knot_tcp_conn_t *conn)
+{
+	return (node_t *)&conn->list_node_placeholder;
+}
+
+static void next_node_ptr(knot_tcp_conn_t **ptr)
+{
+	if (*ptr != NULL) {
+		*ptr = (*ptr)->list_node_placeholder.list_node_next;
+		if ((*ptr)->list_node_placeholder.list_node_next == NULL) { // detected tail of list
+			*ptr = NULL;
+		}
+	}
+}
+
+static void next_ptr_ibuf(knot_tcp_conn_t **ptr)
+{
+	do {
+		next_node_ptr(ptr);
+	} while (*ptr != NULL && (*ptr)->inbuf.iov_len == 0);
+}
+
+static void next_ptr_obuf(knot_tcp_conn_t **ptr)
+{
+	do {
+		next_node_ptr(ptr);
+	} while (*ptr != NULL && knot_tcp_outbufs_usage((*ptr)->outbufs) == 0);
+}
+
+_public_
+knot_tcp_table_t *knot_tcp_table_new(size_t size, knot_tcp_table_t *secret_share)
+{
+	knot_tcp_table_t *table = calloc(1, sizeof(*table) + sizeof(list_t) +
+	                                    size * sizeof(table->conns[0]));
+	if (table == NULL) {
+		return table;
+	}
+
+	table->size = size;
+	init_list(tcp_table_timeout(table));
+
+	assert(sizeof(table->hash_secret) == sizeof(SIPHASH_KEY));
+	if (secret_share == NULL) {
+		table->hash_secret[0] = dnssec_random_uint64_t();
+		table->hash_secret[1] = dnssec_random_uint64_t();
+	} else {
+		table->hash_secret[0] = secret_share->hash_secret[0];
+		table->hash_secret[1] = secret_share->hash_secret[1];
+	}
+
+	return table;
+}
+
+static void del_conn(knot_tcp_conn_t *conn)
+{
+	if (conn != NULL) {
+		free(conn->inbuf.iov_base);
+		while (conn->outbufs != NULL) {
+			struct knot_tcp_outbuf *next = conn->outbufs->next;
+			free(conn->outbufs);
+			conn->outbufs = next;
+		}
+		free(conn);
+	}
+}
+
+_public_
+void knot_tcp_table_free(knot_tcp_table_t *table)
+{
+	if (table != NULL) {
+		knot_tcp_conn_t *conn, *next;
+		WALK_LIST_DELSAFE(conn, next, *tcp_table_timeout(table)) {
+			del_conn(conn);
+		}
+		free(table);
+	}
+}
+
+static knot_tcp_conn_t **tcp_table_lookup(const struct sockaddr_in6 *rem,
+                                          const struct sockaddr_in6 *loc,
+                                          uint64_t *hash, knot_tcp_table_t *table)
+{
+	if (*hash == 0) {
+		*hash = hash_four_tuple(rem, loc, table);
+	}
+	size_t sdl = sockaddr_data_len(rem, loc);
+	knot_tcp_conn_t **res = table->conns + (*hash % table->size);
+	while (*res != NULL) {
+		if (memcmp(&(*res)->ip_rem, rem, sdl) == 0 &&
+		    memcmp(&(*res)->ip_loc, loc, sdl) == 0) {
+			break;
+		}
+		res = &(*res)->next;
+	}
+	return res;
+}
+
+static knot_tcp_conn_t **tcp_table_re_lookup(knot_tcp_conn_t *conn,
+                                             knot_tcp_table_t *table)
+{
+	uint64_t unused_hash = 0;
+	knot_tcp_conn_t **res = tcp_table_lookup(&conn->ip_rem, &conn->ip_loc,
+	                                         &unused_hash, table);
+	assert(*res == conn);
+	return res;
+}
+
+static void rem_align_pointers(knot_tcp_conn_t *to_rem, knot_tcp_table_t *table)
+{
+	if (to_rem == table->next_close) {
+		next_node_ptr(&table->next_close);
+	}
+	if (to_rem == table->next_ibuf) {
+		next_ptr_ibuf(&table->next_ibuf);
+	}
+	if (to_rem == table->next_obuf) {
+		next_ptr_obuf(&table->next_obuf);
+	}
+	if (to_rem == table->next_resend) {
+		next_ptr_obuf(&table->next_resend);
+	}
+}
+
+static void tcp_table_remove_conn(knot_tcp_conn_t **todel)
+{
+	rem_node(tcp_conn_node(*todel)); // remove from timeout double-linked list
+	*todel = (*todel)->next; // remove from conn-table linked list
+}
+
+static void tcp_table_remove(knot_tcp_conn_t **todel, knot_tcp_table_t *table)
+{
+	assert(table->usage > 0);
+	rem_align_pointers(*todel, table);
+	table->inbufs_total -= (*todel)->inbuf.iov_len;
+	table->outbufs_total -= knot_tcp_outbufs_usage((*todel)->outbufs);
+	tcp_table_remove_conn(todel);
+	table->usage--;
+}
+
+static void conn_init_from_msg(knot_tcp_conn_t *conn, knot_xdp_msg_t *msg)
+{
+	memcpy(&conn->ip_rem, &msg->ip_from, sizeof(conn->ip_rem));
+	memcpy(&conn->ip_loc, &msg->ip_to,   sizeof(conn->ip_loc));
+
+	memcpy(&conn->last_eth_rem, &msg->eth_from, sizeof(conn->last_eth_rem));
+	memcpy(&conn->last_eth_loc, &msg->eth_to,   sizeof(conn->last_eth_loc));
+
+	conn->seqno = msg->seqno;
+	conn->ackno = msg->ackno;
+	conn->acked = msg->ackno;
+
+	conn->last_active = get_timestamp();
+	conn->state = XDP_TCP_NORMAL;
+	conn->establish_rtt = 0;
+
+	memset(&conn->inbuf, 0, sizeof(conn->inbuf));
+	memset(&conn->outbufs, 0, sizeof(conn->outbufs));
+}
+
+static void tcp_table_insert(knot_tcp_conn_t *conn, uint64_t hash,
+                             knot_tcp_table_t *table)
+{
+	knot_tcp_conn_t **addto = table->conns + (hash % table->size);
+	add_tail(tcp_table_timeout(table), tcp_conn_node(conn));
+	if (table->next_close == NULL) {
+		table->next_close = conn;
+	}
+	conn->next = *addto;
+	*addto = conn;
+	table->usage++;
+}
+
+// WARNING you shall ensure that it's not in the table already!
+static int tcp_table_add(knot_xdp_msg_t *msg, uint64_t hash, knot_tcp_table_t *table,
+                         knot_tcp_conn_t **res)
+{
+	knot_tcp_conn_t *c = malloc(sizeof(*c));
+	if (c == NULL) {
+		return KNOT_ENOMEM;
+	}
+	conn_init_from_msg(c, msg);
+	tcp_table_insert(c, hash, table);
+	*res = c;
+	return KNOT_EOK;
+}
+
+static bool check_seq_ack(const knot_xdp_msg_t *msg, const knot_tcp_conn_t *conn)
+{
+	if (conn == NULL || conn->seqno != msg->seqno) {
+		return false;
+	}
+
+	if (conn->acked <= conn->ackno) { // ackno does not wrap around uint32
+		return (msg->ackno >= conn->acked && msg->ackno <= conn->ackno);
+	} else { // this is more tricky
+		return (msg->ackno >= conn->acked || msg->ackno <= conn->ackno);
+	}
+}
+
+static void conn_update(knot_tcp_conn_t *conn, const knot_xdp_msg_t *msg)
+{
+	conn->seqno = knot_tcp_next_seqno(msg);
+	memcpy(conn->last_eth_rem, msg->eth_from, sizeof(conn->last_eth_rem));
+	memcpy(conn->last_eth_loc, msg->eth_to, sizeof(conn->last_eth_loc));
+	conn->window_size = (uint32_t)msg->win * (1LU << conn->window_scale);
+
+	uint32_t now = get_timestamp();
+	if (conn->establish_rtt == 0 && conn->last_active != 0) {
+		conn->establish_rtt = now - conn->last_active;
+	}
+	conn->last_active = now;
+}
+
+_public_
+int knot_tcp_recv(knot_tcp_relay_t *relays, knot_xdp_msg_t msgs[], uint32_t msg_count,
+                  knot_tcp_table_t *tcp_table, knot_tcp_table_t *syn_table,
+                  knot_tcp_ignore_t ignore)
+{
+	if (msg_count == 0) {
+		return KNOT_EOK;
+	}
+	if (relays == NULL || msgs == NULL || tcp_table == NULL) {
+		return KNOT_EINVAL;
+	}
+	memset(relays, 0, msg_count * sizeof(*relays));
+
+	knot_tcp_relay_t *relay = relays;
+	int ret = KNOT_EOK;
+
+	for (knot_xdp_msg_t *msg = msgs; msg != msgs + msg_count && ret == KNOT_EOK; msg++) {
+		if (!(msg->flags & KNOT_XDP_MSG_TCP)) {
+			continue;
+		}
+
+		uint64_t conn_hash = 0;
+		knot_tcp_conn_t **pconn = tcp_table_lookup(&msg->ip_from, &msg->ip_to,
+		                                           &conn_hash, tcp_table);
+		knot_tcp_conn_t *conn = *pconn;
+		bool seq_ack_match = check_seq_ack(msg, conn);
+		if (seq_ack_match) {
+			assert(conn->mss != 0);
+			conn_update(conn, msg);
+
+			rem_align_pointers(conn, tcp_table);
+			rem_node(tcp_conn_node(conn));
+			add_tail(tcp_table_timeout(tcp_table), tcp_conn_node(conn));
+
+			if (msg->flags & KNOT_XDP_MSG_ACK) {
+				conn->acked = msg->ackno;
+				knot_tcp_outbufs_ack(&conn->outbufs, msg->ackno, &tcp_table->outbufs_total);
+			}
+		}
+
+		relay->msg = msg;
+		relay->conn = conn;
+
+		// process incoming data
+		if (seq_ack_match && (msg->flags & KNOT_XDP_MSG_ACK) && msg->payload.iov_len > 0) {
+			if (!(ignore & XDP_TCP_IGNORE_DATA_ACK)) {
+				relay->auto_answer = KNOT_XDP_MSG_ACK;
+			}
+			ret = knot_tcp_inbuf_update(&conn->inbuf, msg->payload, &relay->inbufs,
+			                            &relay->inbufs_count, &tcp_table->inbufs_total);
+			if (ret != KNOT_EOK) {
+				break;
+			}
+			if (conn->inbuf.iov_len > 0 && tcp_table->next_ibuf == NULL) {
+				tcp_table->next_ibuf = conn;
+			}
+		}
+
+		// process TCP connection state
+		switch (msg->flags & (KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_ACK |
+		                      KNOT_XDP_MSG_FIN | KNOT_XDP_MSG_RST)) {
+		case KNOT_XDP_MSG_SYN:
+		case (KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_ACK):
+			if (conn == NULL) {
+				bool synack = (msg->flags & KNOT_XDP_MSG_ACK);
+
+				knot_tcp_table_t *add_table = tcp_table;
+				if (syn_table != NULL && !synack) {
+					add_table = syn_table;
+					if (*tcp_table_lookup(&msg->ip_from, &msg->ip_to, &conn_hash, syn_table) != NULL) {
+						break;
+					}
+				}
+
+				ret = tcp_table_add(msg, conn_hash, add_table, &relay->conn);
+				if (ret == KNOT_EOK) {
+					relay->action = synack ? XDP_TCP_ESTABLISH : XDP_TCP_SYN;
+					if (!(ignore & XDP_TCP_IGNORE_ESTABLISH)) {
+						relay->auto_answer = synack ? KNOT_XDP_MSG_ACK : (KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_ACK);
+					}
+
+					conn = relay->conn;
+					conn->state = synack ? XDP_TCP_NORMAL: XDP_TCP_ESTABLISHING;
+					conn->mss = MAX(msg->mss, 536); // minimal MSS, most importantly not zero!
+					conn->window_scale = msg->win_scale;
+					conn_update(conn, msg);
+					if (!synack) {
+						conn->acked = dnssec_random_uint32_t();
+						conn->ackno = conn->acked;
+					}
+				}
+			} else {
+				relay->auto_answer = KNOT_XDP_MSG_ACK;
+			}
+			break;
+		case KNOT_XDP_MSG_ACK:
+			if (!seq_ack_match) {
+				if (syn_table != NULL && msg->payload.iov_len == 0 &&
+				    (pconn = tcp_table_lookup(&msg->ip_from, &msg->ip_to, &conn_hash, syn_table)) != NULL &&
+				    (conn = *pconn) != NULL && check_seq_ack(msg, conn)) {
+					// move conn from syn_table to tcp_table
+					tcp_table_remove(pconn, syn_table);
+					tcp_table_insert(conn, conn_hash, tcp_table);
+					relay->conn = conn;
+					relay->action = XDP_TCP_ESTABLISH;
+					conn->state = XDP_TCP_NORMAL;
+					conn_update(conn, msg);
+				}
+			} else {
+				switch (conn->state) {
+				case XDP_TCP_NORMAL:
+				case XDP_TCP_CLOSING1: // just a mess, ignore
+					break;
+				case XDP_TCP_ESTABLISHING:
+					conn->state = XDP_TCP_NORMAL;
+					relay->action = XDP_TCP_ESTABLISH;
+					break;
+				case XDP_TCP_CLOSING2:
+					if (msg->payload.iov_len == 0) { // otherwise ignore close
+						tcp_table_remove(pconn, tcp_table);
+						relay->answer = XDP_TCP_FREE;
+					}
+					break;
+				}
+			}
+			break;
+		case (KNOT_XDP_MSG_FIN | KNOT_XDP_MSG_ACK):
+			if (ignore & XDP_TCP_IGNORE_FIN) {
+				break;
+			}
+			if (!seq_ack_match) {
+				if (conn != NULL) {
+					relay->auto_answer = KNOT_XDP_MSG_RST;
+					relay->auto_seqno = msg->ackno;
+				} // else ignore. It would be better and possible, but no big value for the price of CPU.
+			} else {
+				if (conn->state == XDP_TCP_CLOSING1) {
+					relay->action = XDP_TCP_CLOSE;
+					relay->auto_answer = KNOT_XDP_MSG_ACK;
+					relay->answer = XDP_TCP_FREE;
+					tcp_table_remove(pconn, tcp_table);
+				} else if (msg->payload.iov_len == 0) { // otherwise ignore FIN
+					relay->action = XDP_TCP_CLOSE;
+					relay->auto_answer = KNOT_XDP_MSG_FIN | KNOT_XDP_MSG_ACK;
+					conn->state = XDP_TCP_CLOSING2;
+				}
+			}
+			break;
+		case KNOT_XDP_MSG_RST:
+			if (conn != NULL && msg->seqno == conn->seqno) {
+				relay->action = XDP_TCP_RESET;
+				tcp_table_remove(pconn, tcp_table);
+				relay->answer = XDP_TCP_FREE;
+			} else if (conn != NULL) {
+				relay->auto_answer = KNOT_XDP_MSG_ACK;
+			}
+			break;
+		default:
+			break;
+		}
+
+		if (!knot_tcp_relay_empty(relay)) {
+			relay++;
+		}
+	}
+
+	return ret;
+}
+
+_public_
+int knot_tcp_reply_data(knot_tcp_relay_t *relay, knot_tcp_table_t *tcp_table,
+                        bool ignore_lastbyte, uint8_t *data, uint32_t len)
+{
+	if (relay == NULL || tcp_table == NULL || relay->conn == NULL) {
+		return KNOT_EINVAL;
+	}
+	int ret = knot_tcp_outbufs_add(&relay->conn->outbufs, data, len, ignore_lastbyte,
+	                               relay->conn->mss, &tcp_table->outbufs_total);
+
+	if (tcp_table->next_obuf == NULL && knot_tcp_outbufs_usage(relay->conn->outbufs) > 0) {
+		tcp_table->next_obuf = relay->conn;
+	}
+	if (tcp_table->next_resend == NULL && knot_tcp_outbufs_usage(relay->conn->outbufs) > 0) {
+		tcp_table->next_resend = relay->conn;
+	}
+	return ret;
+}
+
+static knot_xdp_msg_t *first_msg(knot_xdp_msg_t *msgs, uint32_t n_msgs)
+{
+	memset(msgs, 0, n_msgs * sizeof(*msgs));
+	return msgs - 1; // will be incremented just before first use
+}
+
+static int send_msgs(knot_xdp_msg_t *msgs, uint32_t n_msgs, knot_xdp_socket_t *socket)
+{
+	assert(socket);
+	assert(msgs);
+
+	if (n_msgs > 0) {
+		uint32_t unused;
+		return knot_xdp_send(socket, msgs, n_msgs, &unused);
+	}
+
+	return KNOT_EOK;
+}
+
+static void msg_init_from_conn(knot_xdp_msg_t *msg, knot_tcp_conn_t *conn)
+{
+	memcpy( msg->eth_from, conn->last_eth_loc, sizeof(msg->eth_from));
+	memcpy( msg->eth_to,   conn->last_eth_rem, sizeof(msg->eth_to));
+	memcpy(&msg->ip_from, &conn->ip_loc,  sizeof(msg->ip_from));
+	memcpy(&msg->ip_to,   &conn->ip_rem,  sizeof(msg->ip_to));
+
+	msg->ackno = conn->seqno;
+	msg->seqno = conn->ackno;
+
+	msg->payload.iov_len = 0;
+
+	msg->win_scale = 14; // maximum possible
+	msg->win = 0xffff;
+}
+
+static int next_msg(knot_xdp_msg_t *msgs, uint32_t n_msgs, knot_xdp_msg_t **cur,
+                    knot_xdp_socket_t *socket, knot_tcp_relay_t *rl)
+{
+	(*cur)++;
+	if (*cur - msgs >= n_msgs) {
+		int ret = send_msgs(msgs, n_msgs, socket);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		*cur = first_msg(msgs, n_msgs);
+		(*cur)++;
+	}
+
+	knot_xdp_msg_t *msg = *cur;
+
+	knot_xdp_msg_flag_t fl = KNOT_XDP_MSG_TCP;
+	if (rl->conn->ip_loc.sin6_family == AF_INET6) {
+		fl |= KNOT_XDP_MSG_IPV6;
+	}
+	if (rl->conn->state == XDP_TCP_ESTABLISHING) {
+		fl |= KNOT_XDP_MSG_MSS | KNOT_XDP_MSG_WSC;
+	}
+
+	int ret = knot_xdp_send_alloc(socket, fl, msg);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	msg_init_from_conn(msg, rl->conn);
+
+	return ret;
+}
+
+_public_
+int knot_tcp_send(knot_xdp_socket_t *socket, knot_tcp_relay_t relays[],
+                  uint32_t relay_count, uint32_t max_at_once)
+{
+	if (relay_count == 0) {
+		return KNOT_EOK;
+	}
+	if (socket == NULL || relays == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	knot_xdp_msg_t msgs[max_at_once], *first = first_msg(msgs, max_at_once), *msg = first;
+
+	for (uint32_t i = 0; i < relay_count; i++) {
+		knot_tcp_relay_t *rl = &relays[i];
+
+#define NEXT_MSG { \
+	int ret = next_msg(msgs, max_at_once, &msg, socket, rl); \
+	if (ret != KNOT_EOK) { return ret; } \
+}
+
+		if (rl->auto_answer != 0) {
+			NEXT_MSG
+			msg->flags |= rl->auto_answer;
+			if (msg->flags & (KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_FIN)) {
+				rl->conn->ackno++;
+			}
+			if (rl->auto_answer == KNOT_XDP_MSG_RST) {
+				msg->seqno = rl->auto_seqno;
+			}
+		}
+
+		switch (rl->answer & 0x0f) {
+		case XDP_TCP_ESTABLISH:
+			NEXT_MSG
+			msg->flags |= KNOT_XDP_MSG_SYN;
+			rl->conn->ackno++;
+			break;
+		case XDP_TCP_CLOSE:
+			NEXT_MSG
+			msg->flags |= (KNOT_XDP_MSG_FIN | KNOT_XDP_MSG_ACK);
+			rl->conn->ackno++;
+			rl->conn->state = XDP_TCP_CLOSING1;
+			break;
+		case XDP_TCP_RESET:
+			NEXT_MSG
+			msg->flags |= KNOT_XDP_MSG_RST;
+			break;
+		case XDP_TCP_NOOP:
+		default:
+			break;
+		}
+
+		size_t can_data = 0;
+		knot_tcp_outbuf_t *ob;
+		if (rl->conn != NULL) {
+			knot_tcp_outbufs_can_send(rl->conn->outbufs, rl->conn->window_size,
+			                          rl->answer == XDP_TCP_RESEND, &ob, &can_data);
+		}
+		while (can_data > 0) {
+			NEXT_MSG
+			msg->flags |= KNOT_XDP_MSG_ACK;
+			msg->payload.iov_len = ob->len;
+			memcpy(msg->payload.iov_base, ob->bytes, ob->len);
+
+			if (!ob->sent) {
+				assert(rl->conn->ackno == msg->seqno);
+				rl->conn->ackno += msg->payload.iov_len;
+			} else {
+				msg->seqno = ob->seqno;
+			}
+
+			ob->sent = true;
+			ob->seqno = msg->seqno;
+
+			can_data--;
+			ob = ob->next;
+		}
+#undef NEXT_MSG
+	}
+
+	return send_msgs(msgs, msg - first, socket);
+}
+
+static void sweep_reset(knot_tcp_table_t *tcp_table, knot_tcp_relay_t *rl,
+                        ssize_t *free_conns, ssize_t *free_inbuf, ssize_t *free_outbuf,
+                        knot_sweep_stats_t *stats, knot_sweep_counter_t counter)
+{
+	rl->answer = XDP_TCP_RESET | XDP_TCP_FREE;
+	tcp_table_remove(tcp_table_re_lookup(rl->conn, tcp_table), tcp_table); // also updates tcp_table->next_*
+
+	*free_conns -= 1;
+	*free_inbuf -= rl->conn->inbuf.iov_len;
+	*free_outbuf -= knot_tcp_outbufs_usage(rl->conn->outbufs);
+
+	knot_sweep_stats_incr(stats, counter);
+}
+
+_public_
+int knot_tcp_sweep(knot_tcp_table_t *tcp_table,
+                   uint32_t close_timeout, uint32_t reset_timeout,
+                   uint32_t resend_timeout, uint32_t limit_conn_count,
+                   size_t limit_ibuf_size, size_t limit_obuf_size,
+                   knot_tcp_relay_t *relays, uint32_t max_relays,
+                   struct knot_sweep_stats *stats)
+{
+	if (tcp_table == NULL || relays == NULL || max_relays < 1) {
+		return KNOT_EINVAL;
+	}
+
+	uint32_t now = get_timestamp();
+	memset(relays, 0, max_relays * sizeof(*relays));
+	knot_tcp_relay_t *rl = relays, *rl_max = rl + max_relays;
+
+	ssize_t free_conns =  (ssize_t)(tcp_table->usage - limit_conn_count);
+	ssize_t free_inbuf =  (ssize_t)(tcp_table->inbufs_total - MIN(limit_ibuf_size, SSIZE_MAX));
+	ssize_t free_outbuf = (ssize_t)(tcp_table->outbufs_total - MIN(limit_obuf_size, SSIZE_MAX));
+
+	// reset connections to free ibufs
+	while (free_inbuf > 0 && rl != rl_max) {
+		if (tcp_table->next_ibuf->inbuf.iov_len == 0) { // this conn might have get rid of ibuf in the meantime
+			next_ptr_ibuf(&tcp_table->next_ibuf);
+		}
+		assert(tcp_table->next_ibuf != NULL);
+		rl->conn = tcp_table->next_ibuf;
+		sweep_reset(tcp_table, rl, &free_conns, &free_inbuf, &free_outbuf,
+		            stats, KNOT_SWEEP_CTR_LIMIT_IBUF);
+		rl++;
+	}
+
+	// reset connections to free obufs
+	while (free_outbuf > 0 && rl != rl_max) {
+		if (knot_tcp_outbufs_usage(tcp_table->next_obuf->outbufs) == 0) {
+			next_ptr_obuf(&tcp_table->next_obuf);
+		}
+		assert(tcp_table->next_obuf != NULL);
+		rl->conn = tcp_table->next_obuf;
+		sweep_reset(tcp_table, rl, &free_conns, &free_inbuf, &free_outbuf,
+		            stats, KNOT_SWEEP_CTR_LIMIT_OBUF);
+		rl++;
+	}
+
+	// reset connections to free their count, and old ones
+	knot_tcp_conn_t *conn, *next;
+	WALK_LIST_DELSAFE(conn, next, *tcp_table_timeout(tcp_table)) {
+		if ((free_conns <= 0 && now - conn->last_active < reset_timeout) || rl == rl_max) {
+			break;
+		}
+
+		rl->conn = conn;
+		sweep_reset(tcp_table, rl, &free_conns, &free_inbuf, &free_outbuf,
+		            stats, KNOT_SWEEP_CTR_LIMIT_CONN);
+		rl++;
+	}
+
+	// close old connections
+	while (tcp_table->next_close != NULL &&
+	       now - tcp_table->next_close->last_active >= close_timeout &&
+	       rl != rl_max) {
+		if (tcp_table->next_close->state != XDP_TCP_CLOSING1) {
+			rl->conn = tcp_table->next_close;
+			rl->answer = XDP_TCP_CLOSE;
+			knot_sweep_stats_incr(stats, KNOT_SWEEP_CTR_TIMEOUT);
+			rl++;
+		}
+		next_node_ptr(&tcp_table->next_close);
+	}
+
+	// resend unACKed data
+	while (tcp_table->next_resend != NULL &&
+	       now - tcp_table->next_resend->last_active >= resend_timeout &&
+	       rl != rl_max) {
+		rl->conn = tcp_table->next_resend;
+		rl->answer = XDP_TCP_RESEND;
+		rl++;
+		next_ptr_obuf(&tcp_table->next_resend);
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_tcp_cleanup(knot_tcp_table_t *tcp_table, knot_tcp_relay_t relays[],
+                      uint32_t relay_count)
+{
+	(void)tcp_table;
+	for (uint32_t i = 0; i < relay_count; i++) {
+		if (relays[i].answer & XDP_TCP_FREE) {
+			del_conn(relays[i].conn);
+		}
+		free(relays[i].inbufs);
+	}
+}
diff --git a/src/libknot/xdp/tcp.h b/src/libknot/xdp/tcp.h
new file mode 100644
index 0000000..da0f1a4
--- /dev/null
+++ b/src/libknot/xdp/tcp.h
@@ -0,0 +1,227 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief TCP over XDP IO interface.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/xdp/msg.h"
+#include "libknot/xdp/xdp.h"
+
+struct knot_sweep_stats;
+
+typedef enum {
+	XDP_TCP_NOOP      = 0,
+	XDP_TCP_SYN       = 1,
+	XDP_TCP_ESTABLISH = 2,
+	XDP_TCP_CLOSE     = 3,
+	XDP_TCP_RESET     = 4,
+	XDP_TCP_RESEND    = 5,
+
+	XDP_TCP_FREE      = 0x10,
+} knot_tcp_action_t;
+
+typedef enum {
+	XDP_TCP_NORMAL,
+	XDP_TCP_ESTABLISHING,
+	XDP_TCP_CLOSING1, // FIN+ACK sent
+	XDP_TCP_CLOSING2, // FIN+ACK received and sent
+} knot_tcp_state_t;
+
+typedef enum {
+	XDP_TCP_FREE_NONE,
+	XDP_TCP_FREE_DATA,
+	XDP_TCP_FREE_PREFIX,
+} knot_tcp_relay_free_t;
+
+typedef enum {
+	XDP_TCP_IGNORE_NONE        = 0,
+	XDP_TCP_IGNORE_ESTABLISH   = (1 << 0),
+	XDP_TCP_IGNORE_DATA_ACK    = (1 << 1),
+	XDP_TCP_IGNORE_FIN         = (1 << 2),
+} knot_tcp_ignore_t;
+
+typedef struct knot_tcp_conn {
+	struct {
+		struct knot_tcp_conn *list_node_next;
+		struct knot_tcp_conn *list_node_prev;
+	} list_node_placeholder;
+	struct sockaddr_in6 ip_rem;
+	struct sockaddr_in6 ip_loc;
+	uint8_t last_eth_rem[ETH_ALEN];
+	uint8_t last_eth_loc[ETH_ALEN];
+	uint16_t mss;
+	uint8_t window_scale;
+	uint32_t seqno;
+	uint32_t ackno;
+	uint32_t acked;
+	uint32_t window_size;
+	uint32_t last_active;
+	uint32_t establish_rtt; // in microseconds
+	knot_tcp_state_t state;
+	struct iovec inbuf;
+	struct knot_tcp_outbuf *outbufs;
+	struct knot_tcp_conn *next;
+} knot_tcp_conn_t;
+
+typedef struct {
+	size_t size;
+	size_t usage;
+	size_t inbufs_total;
+	size_t outbufs_total;
+	uint64_t hash_secret[2];
+	knot_tcp_conn_t *next_close;
+	knot_tcp_conn_t *next_ibuf;
+	knot_tcp_conn_t *next_obuf;
+	knot_tcp_conn_t *next_resend;
+	knot_tcp_conn_t *conns[];
+} knot_tcp_table_t;
+
+typedef struct {
+	const knot_xdp_msg_t *msg;
+	knot_tcp_action_t action;
+	knot_xdp_msg_flag_t auto_answer;
+	uint32_t auto_seqno;
+	knot_tcp_action_t answer;
+	struct iovec *inbufs;
+	size_t inbufs_count;
+	knot_tcp_conn_t *conn;
+} knot_tcp_relay_t;
+
+/*!
+ * \brief Return next TCP sequence number.
+ */
+inline static uint32_t knot_tcp_next_seqno(const knot_xdp_msg_t *msg)
+{
+	uint32_t res = msg->seqno + msg->payload.iov_len;
+	if (msg->flags & (KNOT_XDP_MSG_SYN | KNOT_XDP_MSG_FIN)) {
+		res++;
+	}
+	return res;
+}
+
+/*!
+ * \brief Check if the relay is empty.
+ */
+inline static bool knot_tcp_relay_empty(const knot_tcp_relay_t *relay)
+{
+	return relay->action == XDP_TCP_NOOP && relay->answer == XDP_TCP_NOOP &&
+	       relay->auto_answer == 0 && relay->inbufs_count == 0;
+}
+
+/*!
+ * \brief Allocate TCP connection-handling hash table.
+ *
+ * \param size           Number of records for the hash table.
+ * \param secret_share   Optional: share the hashing secret with another table.
+ *
+ * \note Hashing conflicts are solved by single-linked-lists in each record.
+ *
+ * \return The table, or NULL.
+ */
+knot_tcp_table_t *knot_tcp_table_new(size_t size, knot_tcp_table_t *secret_share);
+
+/*!
+ * \brief Free TCP connection hash table including all connection records.
+ *
+ * \note The freed connections are not closed nor reset.
+ */
+void knot_tcp_table_free(knot_tcp_table_t *table);
+
+/*!
+ * \brief Process received packets, prepare automatic responses (e.g. ACK), pick incoming data.
+ *
+ * \param relays      Out: relays to be filled with message/connection details.
+ * \param msgs        Packets received by knot_xdp_recv().
+ * \param msg_count   Number of received packets.
+ * \param tcp_table   Table of TCP connections.
+ * \param syn_table   Optional: extra table for handling partially established connections.
+ * \param ignore      Ignore specific TCP packets indication.
+ *
+ * \return KNOT_E*
+ */
+int knot_tcp_recv(knot_tcp_relay_t *relays, knot_xdp_msg_t msgs[], uint32_t msg_count,
+                  knot_tcp_table_t *tcp_table, knot_tcp_table_t *syn_table,
+                  knot_tcp_ignore_t ignore);
+
+/*!
+ * \brief Prepare data (payload) to be sent as a response on specific relay.
+ *
+ * \param relay            Relay with active connection.
+ * \param tcp_table        TCP table.
+ * \param ignore_lastbyte  Evil mode: drop last byte of the payload.
+ * \param data             Data payload, possibly > MSS and > window.
+ * \param len              Payload length, < 64k.
+ *
+ * \return KNOT_E*
+ */
+int knot_tcp_reply_data(knot_tcp_relay_t *relay, knot_tcp_table_t *tcp_table,
+                        bool ignore_lastbyte, uint8_t *data, uint32_t len);
+
+/*!
+ * \brief Send TCP packets.
+ *
+ * \param socket       XDP socket to send through.
+ * \param relays       Connection changes and data.
+ * \param relay_count  Number of connection changes and data.
+ * \param max_at_once  Limit of packet batch sent by knot_xdp_send().
+ *
+ * \return KNOT_E*
+ */
+int knot_tcp_send(knot_xdp_socket_t *socket, knot_tcp_relay_t relays[],
+                  uint32_t relay_count, uint32_t max_at_once);
+
+/*!
+ * \brief Cleanup old TCP connections, perform timeout checks.
+ *
+ * \param tcp_table        TCP connection table to clean up.
+ * \param close_timeout    Gracefully close connections older than this (usecs).
+ * \param reset_timeout    Reset connections older than this (usecs).
+ * \param resend_timeout   Resend unAcked data older than this (usecs).
+ * \param limit_conn_count Limit of active connections in TCP table, reset if more.
+ * \param limit_ibuf_size  Limit of memory usage by input buffers, reset if exceeded.
+ * \param limit_obuf_size  Limit of memory usage by output buffers, reset if exceeded.
+ * \param relays           Out: relays to be filled with close/reset instructions for knot_tcp_send().
+ * \param max_relays       Maximum relays to be used.
+ * \param stats            Out: sweeped out connection statistics.
+ *
+ * \return KNOT_E*
+ */
+int knot_tcp_sweep(knot_tcp_table_t *tcp_table,
+                   uint32_t close_timeout, uint32_t reset_timeout,
+                   uint32_t resend_timeout, uint32_t limit_conn_count,
+                   size_t limit_ibuf_size, size_t limit_obuf_size,
+                   knot_tcp_relay_t *relays, uint32_t max_relays,
+                   struct knot_sweep_stats *stats);
+
+/*!
+ * \brief Free resources of closed/reset connections.
+ *
+ * \param tcp_table    TCP table with connections.
+ * \param relays       Relays with closed/reset (or other, ignored) connections.
+ * \param relay_count  Number of relays.
+ */
+void knot_tcp_cleanup(knot_tcp_table_t *tcp_table, knot_tcp_relay_t relays[],
+                      uint32_t relay_count);
+
+/*! @} */
diff --git a/src/libknot/xdp/tcp_iobuf.c b/src/libknot/xdp/tcp_iobuf.c
new file mode 100644
index 0000000..88ebcc3
--- /dev/null
+++ b/src/libknot/xdp/tcp_iobuf.c
@@ -0,0 +1,266 @@
+/*  Copyright (C) 2022 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 <stdlib.h>
+#include <string.h>
+
+#include "libknot/xdp/tcp_iobuf.h"
+
+#include "contrib/macros.h"
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/error.h"
+
+static void iov_clear(struct iovec *iov)
+{
+	free(iov->iov_base);
+	memset(iov, 0, sizeof(*iov));
+}
+
+static void iov_inc(struct iovec *iov, size_t shift)
+{
+	assert(shift <= iov->iov_len);
+	iov->iov_base += shift;
+	iov->iov_len -= shift;
+}
+
+/*! \brief Strip 2-byte length prefix from a payload. */
+static void iov_inc2(struct iovec *iov)
+{
+	iov_inc(iov, sizeof(uint16_t));
+}
+
+static size_t tcp_payload_len(const struct iovec *payload)
+{
+	assert(payload->iov_len >= 2);
+	uint16_t val;
+	memcpy(&val, payload->iov_base, sizeof(val));
+	return be16toh(val) + sizeof(val);
+}
+
+static bool iov_inc_pf(struct iovec *iov)
+{
+	size_t shift = tcp_payload_len(iov);
+	if (iov->iov_len >= shift) {
+		iov_inc(iov, shift);
+		return true;
+	} else {
+		return false;
+	}
+}
+
+static size_t iov_count(const struct iovec *iov)
+{
+	size_t res = 0;
+	struct iovec tmp = *iov;
+	while (tmp.iov_len >= sizeof(uint16_t) && iov_inc_pf(&tmp)) {
+		res++;
+	}
+	return res;
+}
+
+static void iov_append(struct iovec *what, const struct iovec *with)
+{
+	// NOTE: what->iov_base must be pre-allocated large enough
+	memcpy(what->iov_base + what->iov_len, with->iov_base, with->iov_len);
+	what->iov_len += with->iov_len;
+}
+
+_public_
+int knot_tcp_inbuf_update(struct iovec *buffer, struct iovec data,
+                          struct iovec **inbufs, size_t *inbufs_count,
+                          size_t *buffers_total)
+{
+	size_t res_count = 0;
+	struct iovec *res = NULL, *cur = NULL;
+
+	*inbufs = NULL;
+	*inbufs_count = 0;
+
+	if (data.iov_len < 1) {
+		return KNOT_EOK;
+	}
+	if (buffer->iov_len == 1) {
+		((uint8_t *)buffer->iov_base)[1] = ((uint8_t *)data.iov_base)[0];
+		buffer->iov_len++;
+		iov_inc(&data, 1);
+		if (data.iov_len < 1) {
+			return KNOT_EOK;
+		}
+	}
+	if (buffer->iov_len > 0) {
+		size_t buffer_req = tcp_payload_len(buffer);
+		assert(buffer_req > buffer->iov_len);
+		struct iovec data_use = { data.iov_base, buffer_req - buffer->iov_len };
+		if (data_use.iov_len <= data.iov_len) { // usable payload combined from buffer and data ---> res[0] allocated tohether with res
+			iov_inc(&data, data_use.iov_len);
+
+			res_count = 1 + iov_count(&data);
+			res = malloc(res_count * sizeof(*res) + buffer_req);
+			if (res == NULL) {
+				return KNOT_ENOMEM;
+			}
+			res[0].iov_base = (void *)(res + res_count);
+			res[0].iov_len = 0;
+			iov_append(&res[0], buffer);
+			iov_append(&res[0], &data_use);
+			assert(res[0].iov_len == buffer_req);
+			iov_inc2(&res[0]);
+
+			cur = &res[1];
+			*buffers_total -= buffer->iov_len;
+			iov_clear(buffer);
+		} else { // just extend the buffer with data
+			void *bufnew = realloc(buffer->iov_base, buffer->iov_len + data.iov_len);
+			if (bufnew == NULL) {
+				return KNOT_ENOMEM;
+			}
+			buffer->iov_base = bufnew;
+			iov_append(buffer, &data);
+			*buffers_total += data.iov_len;
+			return KNOT_EOK;
+		}
+	} else { // just allocate res
+		res_count = iov_count(&data);
+		if (res_count > 0) {
+			res = malloc(res_count * sizeof(*res));
+			if (res == NULL) {
+				return KNOT_ENOMEM;
+			}
+			cur = &res[0];
+		}
+	}
+
+	void *last;
+	while (data.iov_len > 1) {
+		last = data.iov_base;
+		if (!iov_inc_pf(&data)) {
+			break;
+		}
+		assert(cur);
+		cur->iov_base = last;
+		cur->iov_len = data.iov_base - last;
+		iov_inc2(cur);
+		cur++;
+	}
+	assert(cur == ((res_count) ? res + res_count : res));
+
+	// store the final incomplete payload to buffer
+	if (data.iov_len > 0) {
+		assert(buffer->iov_base == NULL);
+		buffer->iov_base = malloc(MAX(data.iov_len, 2));
+		if (buffer->iov_base == NULL) {
+			free(res);
+			return KNOT_ENOMEM;
+		}
+		*buffers_total += MAX(data.iov_len, 2);
+		buffer->iov_len = 0;
+		iov_append(buffer, &data);
+	}
+
+	*inbufs = res;
+	*inbufs_count = res_count;
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_tcp_outbufs_add(knot_tcp_outbuf_t **bufs, uint8_t *data, size_t len,
+                         bool ignore_lastbyte, uint32_t mss, size_t *outbufs_total)
+{
+	if (len > UINT16_MAX) {
+		return KNOT_ELIMIT;
+	}
+	knot_tcp_outbuf_t **end = bufs;
+	while (*end != NULL) { // NOTE: this can be optimized by adding "end" pointer for the price of larger knot_tcp_conn_t struct
+		end = &(*end)->next;
+	}
+	uint16_t prefix = htobe16(len), prefix_len = sizeof(prefix);
+	while (len > 0) {
+		uint16_t newlen = MIN(len + prefix_len, mss);
+		knot_tcp_outbuf_t *newob = calloc(1, sizeof(*newob) + newlen);
+		if (newob == NULL) {
+			return KNOT_ENOMEM;
+		}
+		*outbufs_total += sizeof(*newob) + newlen;
+		newob->len = newlen;
+		if (ignore_lastbyte) {
+			newob->len--;
+		}
+		memcpy(newob->bytes, &prefix, prefix_len);
+		memcpy(newob->bytes + prefix_len, data, newlen - prefix_len);
+
+		*end = newob;
+		end = &newob->next;
+
+		data += newlen - prefix_len;
+		len -= newlen - prefix_len;
+
+		prefix_len = 0;
+	}
+	return KNOT_EOK;
+}
+
+static bool seqno_lower(uint32_t seqno, uint32_t ackno, uint32_t ackno_min)
+{
+	if (ackno_min <= ackno) {
+		return (seqno >= ackno_min && seqno <= ackno);
+	} else {
+		return (seqno >= ackno_min || seqno <= ackno);
+	}
+}
+
+_public_
+void knot_tcp_outbufs_ack(knot_tcp_outbuf_t **bufs, uint32_t ackno, size_t *outbufs_total)
+{
+	uint32_t ackno_min = ackno - (UINT32_MAX / 2); // FIXME better?
+	while (*bufs != NULL && (*bufs)->sent && seqno_lower((*bufs)->seqno + (*bufs)->len, ackno, ackno_min)) {
+		knot_tcp_outbuf_t *tofree = *bufs;
+		*bufs = tofree->next;
+		*outbufs_total -= tofree->len + sizeof(*tofree);
+		free(tofree);
+	}
+}
+
+_public_
+void knot_tcp_outbufs_can_send(knot_tcp_outbuf_t *bufs, ssize_t window_size, bool resend,
+                               knot_tcp_outbuf_t **send_start, size_t *send_count)
+{
+	*send_count = 0;
+	*send_start = bufs;
+	while (*send_start != NULL && (*send_start)->sent && !resend) {
+		window_size -= (*send_start)->len;
+		*send_start = (*send_start)->next;
+	}
+
+	knot_tcp_outbuf_t *can_send = *send_start;
+	while (can_send != NULL && window_size >= can_send->len) {
+		(*send_count)++;
+		window_size -= can_send->len;
+		can_send = can_send->next;
+	}
+}
+
+_public_
+size_t knot_tcp_outbufs_usage(knot_tcp_outbuf_t *bufs)
+{
+	size_t res = 0;
+	for (knot_tcp_outbuf_t *i = bufs; i != NULL; i = i->next) {
+		res += i->len + sizeof(*i);
+	}
+	return res;
+}
diff --git a/src/libknot/xdp/tcp_iobuf.h b/src/libknot/xdp/tcp_iobuf.h
new file mode 100644
index 0000000..a27eeab
--- /dev/null
+++ b/src/libknot/xdp/tcp_iobuf.h
@@ -0,0 +1,120 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief TCP buffer helpers.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/uio.h>
+
+typedef struct knot_tcp_outbuf {
+	struct knot_tcp_outbuf *next;
+	uint32_t len;
+	uint32_t seqno;
+	bool sent;
+	uint8_t bytes[];
+} knot_tcp_outbuf_t;
+
+typedef enum {
+	KNOT_SWEEP_CTR_TIMEOUT    = 0,
+	KNOT_SWEEP_CTR_LIMIT_CONN = 1,
+	KNOT_SWEEP_CTR_LIMIT_IBUF = 2,
+	KNOT_SWEEP_CTR_LIMIT_OBUF = 3,
+} knot_sweep_counter_t;
+
+typedef struct knot_sweep_stats {
+	uint32_t total;
+	uint32_t counters[4];
+} knot_sweep_stats_t;
+
+inline static void knot_sweep_stats_incr(knot_sweep_stats_t *stats, knot_sweep_counter_t counter)
+{
+	(stats->counters[counter])++;
+	(stats->total)++;
+}
+
+inline static void knot_sweep_stats_reset(knot_sweep_stats_t *stats)
+{
+	memset(stats, 0, sizeof(*stats));
+}
+
+/*!
+ * \brief Handle DNS-over-TCP payloads in buffer and message.
+ *
+ * \param buffer         In/out: persistent buffer to store incomplete DNS payloads between receiving packets.
+ * \param data           In: momental DNS payloads in incoming packet.
+ * \param inbufs         Out: list of incoming DNS messages.
+ * \param inbufs_count   Out: number of inbufs.
+ * \param buffers_total  In/Out: total size of buffers (will be increased or decreased).
+ *
+ * \return KNOT_EOK, KNOT_ENOMEM
+ */
+int knot_tcp_inbuf_update(struct iovec *buffer, struct iovec data,
+                          struct iovec **inbufs, size_t *inbufs_count,
+                          size_t *buffers_total);
+
+/*!
+ * \brief Add payload to be sent by TCP, to output buffers.
+ *
+ * \param bufs             Output buffers to be updated.
+ * \param data             Payload to be sent.
+ * \param len              Payload length.
+ * \param ignore_lastbyte  Evil mode: drop last byte of the payload.
+ * \param mss              Connection outgoing MSS.
+ * \param outbufs_total    In/out: total outbuf statistic to be updated.
+ *
+ * \return KNOT_E*
+ */
+int knot_tcp_outbufs_add(knot_tcp_outbuf_t **bufs, uint8_t *data, size_t len,
+                         bool ignore_lastbyte, uint32_t mss, size_t *outbufs_total);
+
+/*!
+ * \brief Remove+free acked data from output buffers.
+ *
+ * \param bufs             Output buffers to be updated.
+ * \param ackno            Ackno of received ACK.
+ * \param outbufs_total    In/out: total outbuf statistic to be updated.
+ */
+void knot_tcp_outbufs_ack(knot_tcp_outbuf_t **bufs, uint32_t ackno, size_t *outbufs_total);
+
+/*!
+ * \brief Prepare output buffers to be sent now.
+ *
+ * \param bufs          Output buffers to be updated.
+ * \param window_size   Connection outgoing window size.
+ * \param resend        Send also possibly already sent data.
+ * \param send_start    Out: first output buffer to be sent.
+ * \param send_count    Out: number of output buffers to be sent.
+ */
+void knot_tcp_outbufs_can_send(knot_tcp_outbuf_t *bufs, ssize_t window_size, bool resend,
+                               knot_tcp_outbuf_t **send_start, size_t *send_count);
+
+/*!
+ * \brief Compute allocated size of output buffers.
+ */
+size_t knot_tcp_outbufs_usage(knot_tcp_outbuf_t *bufs);
+
+/*! @} */
diff --git a/src/libknot/xdp/xdp.c b/src/libknot/xdp/xdp.c
new file mode 100644
index 0000000..975276d
--- /dev/null
+++ b/src/libknot/xdp/xdp.c
@@ -0,0 +1,568 @@
+/*  Copyright (C) 2022 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 <netinet/in.h>
+#include <linux/if_ether.h>
+#include <linux/udp.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "libknot/attribute.h"
+#include "libknot/endian.h"
+#include "libknot/errcode.h"
+#include "libknot/xdp/bpf-consts.h"
+#include "libknot/xdp/bpf-user.h"
+#include "libknot/xdp/eth.h"
+#include "libknot/xdp/msg_init.h"
+#include "libknot/xdp/protocols.h"
+#include "libknot/xdp/xdp.h"
+#include "contrib/macros.h"
+#include "contrib/net.h"
+
+#define FRAME_SIZE		2048
+
+#define FRAME_COUNT_TX		2048
+#define FRAME_COUNT_RX		2048
+#define FRAME_COUNT		(FRAME_COUNT_TX + FRAME_COUNT_RX)
+
+#define RING_LEN_TX		FRAME_COUNT_TX
+#define RING_LEN_CQ		FRAME_COUNT_TX
+#define RING_LEN_RX		FRAME_COUNT_RX
+/* It's recommended that the FQ ring size >= HW RX ring size + AF_XDP RX ring size. */
+#define RING_LEN_FQ		8192
+
+#define ALLOC_RETRY_NUM		15
+#define ALLOC_RETRY_DELAY	20 // In nanoseconds.
+
+/* With recent compilers we statically check #defines for settings that
+ * get refused by AF_XDP drivers (in current versions, at least). */
+#if (__STDC_VERSION__ >= 201112L)
+#define IS_POWER_OF_2(n) (((n) & (n - 1)) == 0)
+_Static_assert((FRAME_SIZE == 4096 || FRAME_SIZE == 2048)
+	&& IS_POWER_OF_2(RING_LEN_TX) && IS_POWER_OF_2(RING_LEN_RX)
+	&& IS_POWER_OF_2(RING_LEN_CQ) && IS_POWER_OF_2(RING_LEN_FQ)
+	&& FRAME_COUNT_TX <= (1 << 16) /* see tx_free_indices */
+	, "Incorrect #define combination for AF_XDP.");
+#endif
+
+struct umem_frame {
+	uint8_t bytes[FRAME_SIZE];
+};
+
+static int configure_xsk_umem(struct kxsk_umem **out_umem)
+{
+	/* Allocate memory and call driver to create the UMEM. */
+	struct kxsk_umem *umem = calloc(1,
+		offsetof(struct kxsk_umem, tx_free_indices)
+		+ sizeof(umem->tx_free_indices[0]) * FRAME_COUNT_TX);
+	if (umem == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	int ret = posix_memalign((void **)&umem->frames, getpagesize(),
+	                         FRAME_SIZE * FRAME_COUNT);
+	if (ret != 0) {
+		free(umem);
+		return KNOT_ENOMEM;
+	}
+
+	const struct xsk_umem_config config = {
+		.fill_size = RING_LEN_FQ,
+		.comp_size = RING_LEN_CQ,
+		.frame_size = FRAME_SIZE,
+		.frame_headroom = KNOT_XDP_PKT_ALIGNMENT,
+	};
+
+	ret = xsk_umem__create(&umem->umem, umem->frames, FRAME_SIZE * FRAME_COUNT,
+	                       &umem->fq, &umem->cq, &config);
+	if (ret != KNOT_EOK) {
+		free(umem->frames);
+		free(umem);
+		return ret;
+	}
+	*out_umem = umem;
+
+	/* Designate the starting chunk of buffers for TX, and put them onto the stack. */
+	umem->tx_free_count = FRAME_COUNT_TX;
+	for (uint32_t i = 0; i < FRAME_COUNT_TX; ++i) {
+		umem->tx_free_indices[i] = i;
+	}
+
+	/* Designate the rest of buffers for RX, and pass them to the driver. */
+	uint32_t idx = 0;
+	ret = xsk_ring_prod__reserve(&umem->fq, FRAME_COUNT_RX, &idx);
+	if (ret != FRAME_COUNT_RX) {
+		assert(0);
+		return KNOT_ERROR;
+	}
+	assert(idx == 0);
+	assert(FRAME_COUNT == FRAME_COUNT_TX + FRAME_COUNT_RX);
+	for (uint32_t i = FRAME_COUNT_TX; i < FRAME_COUNT; ++i) {
+		*xsk_ring_prod__fill_addr(&umem->fq, idx++) = i * FRAME_SIZE;
+	}
+	xsk_ring_prod__submit(&umem->fq, FRAME_COUNT_RX);
+
+	return KNOT_EOK;
+}
+
+static void deconfigure_xsk_umem(struct kxsk_umem *umem)
+{
+	(void)xsk_umem__delete(umem->umem);
+	free(umem->frames);
+	free(umem);
+}
+
+static int configure_xsk_socket(struct kxsk_umem *umem,
+                                const struct kxsk_iface *iface,
+                                knot_xdp_socket_t **out_sock)
+{
+	knot_xdp_socket_t *xsk_info = calloc(1, sizeof(*xsk_info));
+	if (xsk_info == NULL) {
+		return KNOT_ENOMEM;
+	}
+	xsk_info->iface = iface;
+	xsk_info->umem = umem;
+
+	const struct xsk_socket_config sock_conf = {
+		.tx_size = RING_LEN_TX,
+		.rx_size = RING_LEN_RX,
+		.libbpf_flags = XSK_LIBBPF_FLAGS__INHIBIT_PROG_LOAD,
+	};
+
+	int ret = xsk_socket__create(&xsk_info->xsk, iface->if_name,
+	                             iface->if_queue, umem->umem,
+	                             &xsk_info->rx, &xsk_info->tx, &sock_conf);
+	if (ret != 0) {
+		free(xsk_info);
+		return ret;
+	}
+
+	*out_sock = xsk_info;
+	return KNOT_EOK;
+}
+
+_public_
+int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
+                  knot_xdp_filter_flag_t flags, uint16_t udp_port, uint16_t quic_port,
+                  knot_xdp_load_bpf_t load_bpf, const void *xdp_config)
+{
+	if (socket == NULL || if_name == NULL ||
+	    (udp_port == quic_port && (flags & KNOT_XDP_FILTER_UDP) && (flags & KNOT_XDP_FILTER_QUIC)) ||
+	    (flags & (KNOT_XDP_FILTER_UDP | KNOT_XDP_FILTER_TCP | KNOT_XDP_FILTER_QUIC)) == 0) {
+		return KNOT_EINVAL;
+	}
+
+	struct kxsk_iface *iface;
+	int ret = kxsk_iface_new(if_name, if_queue, load_bpf, &iface);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	/* Initialize shared packet_buffer for umem usage. */
+	struct kxsk_umem *umem = NULL;
+	ret = configure_xsk_umem(&umem);
+	if (ret != KNOT_EOK) {
+		kxsk_iface_free(iface);
+		return ret;
+	}
+
+	ret = configure_xsk_socket(umem, iface, socket);
+	if (ret != KNOT_EOK) {
+		deconfigure_xsk_umem(umem);
+		kxsk_iface_free(iface);
+		return ret;
+	}
+
+	(*socket)->frame_limit = FRAME_SIZE;
+	ret = knot_eth_mtu(if_name);
+	if (ret > 0) {
+		(*socket)->frame_limit = MIN((unsigned)ret, (*socket)->frame_limit);
+	}
+
+	if (flags & KNOT_XDP_FILTER_ROUTE) {
+		ret = knot_eth_vlans(&(*socket)->vlan_map, &(*socket)->vlan_map_max);
+		if (ret != KNOT_EOK) {
+			xsk_socket__delete((*socket)->xsk);
+			deconfigure_xsk_umem(umem);
+			kxsk_iface_free(iface);
+			free(*socket);
+			*socket = NULL;
+			return ret;
+		}
+	}
+
+	ret = kxsk_socket_start(iface, flags, udp_port, quic_port, (*socket)->xsk);
+	if (ret != KNOT_EOK) {
+		free((*socket)->vlan_map);
+		xsk_socket__delete((*socket)->xsk);
+		deconfigure_xsk_umem(umem);
+		kxsk_iface_free(iface);
+		free(*socket);
+		*socket = NULL;
+		return ret;
+	}
+
+	return ret;
+}
+
+_public_
+void knot_xdp_deinit(knot_xdp_socket_t *socket)
+{
+	if (socket == NULL) {
+		return;
+	}
+	if (unlikely(socket->send_mock != NULL)) {
+		free(socket);
+		return;
+	}
+
+	kxsk_socket_stop(socket->iface);
+	xsk_socket__delete(socket->xsk);
+	deconfigure_xsk_umem(socket->umem);
+
+	kxsk_iface_free((struct kxsk_iface *)/*const-cast*/socket->iface);
+	free(socket->vlan_map);
+	free(socket);
+}
+
+_public_
+int knot_xdp_socket_fd(knot_xdp_socket_t *socket)
+{
+	if (socket == NULL) {
+		return 0;
+	}
+
+	return xsk_socket__fd(socket->xsk);
+}
+
+static void tx_free_relative(struct kxsk_umem *umem, uint64_t addr_relative)
+{
+	/* The address may not point to *start* of buffer, but `/` solves that. */
+	uint64_t index = addr_relative / FRAME_SIZE;
+	assert(index < FRAME_COUNT);
+	umem->tx_free_indices[umem->tx_free_count++] = index;
+}
+
+_public_
+void knot_xdp_send_prepare(knot_xdp_socket_t *socket)
+{
+	if (socket == NULL || unlikely(socket->send_mock != NULL)) {
+		return;
+	}
+
+	struct kxsk_umem *const umem = socket->umem;
+	struct xsk_ring_cons *const cq = &umem->cq;
+
+	uint32_t idx = 0;
+	const uint32_t completed = xsk_ring_cons__peek(cq, UINT32_MAX, &idx);
+	if (completed == 0) {
+		return;
+	}
+	assert(umem->tx_free_count + completed <= FRAME_COUNT_TX);
+
+	for (uint32_t i = 0; i < completed; ++i) {
+		uint64_t addr_relative = *xsk_ring_cons__comp_addr(cq, idx++);
+		tx_free_relative(umem, addr_relative);
+	}
+
+	xsk_ring_cons__release(cq, completed);
+}
+
+static struct umem_frame *alloc_tx_frame(knot_xdp_socket_t *socket)
+{
+	if (unlikely(socket->send_mock != NULL)) {
+		return malloc(sizeof(struct umem_frame));
+	}
+
+	const struct timespec delay = { .tv_nsec = ALLOC_RETRY_DELAY };
+	struct kxsk_umem *umem = socket->umem;
+
+	for (int i = 0; unlikely(umem->tx_free_count == 0); i++) {
+		if (i == ALLOC_RETRY_NUM) {
+			return NULL;
+		}
+		nanosleep(&delay, NULL);
+		knot_xdp_send_prepare(socket);
+	}
+
+	uint32_t index = umem->tx_free_indices[--umem->tx_free_count];
+	return umem->frames + index;
+}
+
+static void prepare_payload(knot_xdp_msg_t *msg, void *uframe)
+{
+	size_t hdr_len = prot_write_hdrs_len(msg);
+	msg->payload.iov_base = uframe + hdr_len + KNOT_XDP_PKT_ALIGNMENT;
+	msg->payload.iov_len = FRAME_SIZE - hdr_len - KNOT_XDP_PKT_ALIGNMENT;
+}
+
+_public_
+int knot_xdp_send_alloc(knot_xdp_socket_t *socket, knot_xdp_msg_flag_t flags,
+                        knot_xdp_msg_t *out)
+{
+	if (socket == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct umem_frame *uframe = alloc_tx_frame(socket);
+	if (uframe == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	msg_init(out, flags);
+	prepare_payload(out, uframe);
+
+	return KNOT_EOK;
+}
+
+_public_
+int knot_xdp_reply_alloc(knot_xdp_socket_t *socket, const knot_xdp_msg_t *query,
+                         knot_xdp_msg_t *out)
+{
+	if (socket == NULL || query == NULL || out == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	struct umem_frame *uframe = alloc_tx_frame(socket);
+	if (uframe == NULL) {
+		return KNOT_ENOMEM;
+	}
+
+	msg_init_reply(out, query);
+	prepare_payload(out, uframe);
+
+	return KNOT_EOK;
+}
+
+static void free_unsent(knot_xdp_socket_t *socket, const knot_xdp_msg_t *msg)
+{
+	if (unlikely(socket->send_mock != NULL)) {
+		free(msg->payload.iov_base - prot_write_hdrs_len(msg) - KNOT_XDP_PKT_ALIGNMENT);
+		return;
+	}
+	uint64_t addr_relative = (uint8_t *)msg->payload.iov_base
+	                         - socket->umem->frames->bytes;
+	tx_free_relative(socket->umem, addr_relative);
+}
+
+_public_
+int knot_xdp_send(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                  uint32_t count, uint32_t *sent)
+{
+	if (socket == NULL || msgs == NULL || sent == NULL) {
+		return KNOT_EINVAL;
+	}
+	if (unlikely(socket->send_mock != NULL)) {
+		int ret = socket->send_mock(socket, msgs, count, sent);
+		for (uint32_t i = 0; i < count; ++i) {
+			free_unsent(socket, &msgs[i]);
+		}
+		return ret;
+	}
+
+	/* Now we want to do something close to
+	 *   xsk_ring_prod__reserve(&socket->tx, count, *idx)
+	 * but we don't know in advance if we utilize *whole* `count`,
+	 * and the API doesn't allow "cancelling reservations".
+	 * Therefore we handle `socket->tx.cached_prod` by hand.
+	 */
+	if (xsk_prod_nb_free(&socket->tx, count) < count) {
+		/* This situation was sometimes observed in the emulated XDP mode. */
+		for (uint32_t i = 0; i < count; ++i) {
+			free_unsent(socket, &msgs[i]);
+		}
+		return KNOT_ENOBUFS;
+	}
+	uint32_t idx = socket->tx.cached_prod;
+
+	for (uint32_t i = 0; i < count; ++i) {
+		const knot_xdp_msg_t *msg = &msgs[i];
+
+		if (empty_msg(msg)) {
+			free_unsent(socket, msg);
+		} else {
+			size_t hdr_len = prot_write_hdrs_len(msg);
+			size_t tot_len = hdr_len + msg->payload.iov_len;
+			uint8_t *msg_beg = msg->payload.iov_base - hdr_len;
+			uint16_t mss = MIN(socket->frame_limit - hdr_len, KNOT_TCP_MSS);
+			prot_write_eth(msg_beg, msg, msg_beg + tot_len, mss);
+
+			*xsk_ring_prod__tx_desc(&socket->tx, idx++) = (struct xdp_desc) {
+				.addr = msg_beg - socket->umem->frames->bytes,
+				.len = tot_len,
+			};
+		}
+	}
+
+	*sent = idx - socket->tx.cached_prod;
+	assert(*sent <= count);
+	socket->tx.cached_prod = idx;
+	xsk_ring_prod__submit(&socket->tx, *sent);
+	socket->kernel_needs_wakeup = true;
+
+	return KNOT_EOK;
+}
+
+_public_
+void knot_xdp_send_free(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                        uint32_t count)
+{
+	for (uint32_t i = 0; i < count; i++) {
+		free_unsent(socket, &msgs[i]);
+	}
+}
+
+_public_
+int knot_xdp_send_finish(knot_xdp_socket_t *socket)
+{
+	if (socket == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	/* Trigger sending queued packets. */
+	if (!socket->kernel_needs_wakeup) {
+		return KNOT_EOK;
+	}
+
+	int ret = sendto(xsk_socket__fd(socket->xsk), NULL, 0, MSG_DONTWAIT, NULL, 0);
+	const bool is_ok = (ret >= 0);
+	// List of "safe" errors taken from
+	// https://github.com/torvalds/linux/blame/master/samples/bpf/xdpsock_user.c
+	const bool is_again = !is_ok && (errno == ENOBUFS || errno == EAGAIN
+	                                || errno == EBUSY || errno == ENETDOWN);
+	// Some of the !is_ok cases are a little unclear - what to do about the syscall,
+	// including how caller of _sendmsg_finish() should react.
+	if (is_ok || !is_again) {
+		socket->kernel_needs_wakeup = false;
+	}
+	if (is_again) {
+		return KNOT_EAGAIN;
+	} else if (is_ok) {
+		return KNOT_EOK;
+	} else {
+		return -errno;
+	}
+	/* This syscall might be avoided with a newer kernel feature (>= 5.4):
+	   https://www.kernel.org/doc/html/latest/networking/af_xdp.html#xdp-use-need-wakeup-bind-flag
+	   Unfortunately it's not easy to continue supporting older kernels
+	   when using this feature on newer ones.
+	 */
+}
+
+_public_
+int knot_xdp_recv(knot_xdp_socket_t *socket, knot_xdp_msg_t msgs[],
+                  uint32_t max_count, uint32_t *count, size_t *wire_size)
+{
+	if (socket == NULL || msgs == NULL || count == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	uint32_t idx = 0;
+	const uint32_t available = xsk_ring_cons__peek(&socket->rx, max_count, &idx);
+	if (available == 0) {
+		*count = 0;
+		return KNOT_EOK;
+	}
+	assert(available <= max_count);
+
+	for (uint32_t i = 0; i < available; ++i) {
+		knot_xdp_msg_t *msg = &msgs[i];
+		const struct xdp_desc *desc = xsk_ring_cons__rx_desc(&socket->rx, idx++);
+		uint8_t *uframe_p = (uint8_t *)socket->umem->frames + desc->addr;
+
+		void *payl_end;
+		void *payl_start = prot_read_eth(uframe_p, msg, &payl_end,
+		                                 socket->vlan_map, socket->vlan_map_max);
+
+		msg->payload.iov_base = payl_start;
+		msg->payload.iov_len = payl_end - payl_start;
+		msg->mss = MIN(msg->mss, FRAME_SIZE - (payl_start - (void *)uframe_p));
+
+		if (wire_size != NULL) {
+			(*wire_size) += desc->len;
+		}
+	}
+
+	xsk_ring_cons__release(&socket->rx, available);
+	*count = available;
+
+	return KNOT_EOK;
+}
+
+static uint8_t *msg_uframe_ptr(const knot_xdp_msg_t *msg)
+{
+	return NULL + ((msg->payload.iov_base - NULL) & ~(FRAME_SIZE - 1));
+}
+
+_public_
+void knot_xdp_recv_finish(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                          uint32_t count)
+{
+	if (socket == NULL || msgs == NULL) {
+		return;
+	}
+
+	struct kxsk_umem *const umem = socket->umem;
+	struct xsk_ring_prod *const fq = &umem->fq;
+
+	uint32_t idx = 0;
+	const uint32_t reserved = xsk_ring_prod__reserve(fq, count, &idx);
+	assert(reserved == count);
+
+	for (uint32_t i = 0; i < reserved; ++i) {
+		uint8_t *uframe_p = msg_uframe_ptr(&msgs[i]);
+		uint64_t offset = uframe_p - umem->frames->bytes;
+		*xsk_ring_prod__fill_addr(fq, idx++) = offset;
+	}
+
+	xsk_ring_prod__submit(fq, reserved);
+}
+
+_public_
+void knot_xdp_info(const knot_xdp_socket_t *socket, FILE *file)
+{
+	if (socket == NULL || file == NULL) {
+		return;
+	}
+
+	// The number of busy frames
+	#define RING_BUSY(ring) \
+		((*(ring)->producer - *(ring)->consumer) & (ring)->mask)
+
+	#define RING_PRINFO(name, ring) \
+		fprintf(file, "Ring %s: size %4d, busy %4d (prod %4d, cons %4d)\n", \
+		        name, (unsigned)(ring)->size, \
+		        (unsigned)RING_BUSY((ring)), \
+		        (unsigned)*(ring)->producer, (unsigned)*(ring)->consumer)
+
+	const int rx_busyf = RING_BUSY(&socket->umem->fq) + RING_BUSY(&socket->rx);
+	fprintf(file, "\nLOST RX frames: %4d", (int)(FRAME_COUNT_RX - rx_busyf));
+
+	const int tx_busyf = RING_BUSY(&socket->umem->cq) + RING_BUSY(&socket->tx);
+	const int tx_freef = socket->umem->tx_free_count;
+	fprintf(file, "\nLOST TX frames: %4d\n", (int)(FRAME_COUNT_TX - tx_busyf - tx_freef));
+
+	RING_PRINFO("FQ", &socket->umem->fq);
+	RING_PRINFO("RX", &socket->rx);
+	RING_PRINFO("TX", &socket->tx);
+	RING_PRINFO("CQ", &socket->umem->cq);
+	fprintf(file, "TX free frames: %4d\n", tx_freef);
+}
diff --git a/src/libknot/xdp/xdp.h b/src/libknot/xdp/xdp.h
new file mode 100644
index 0000000..a7606fe
--- /dev/null
+++ b/src/libknot/xdp/xdp.h
@@ -0,0 +1,189 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief XDP IO interface.
+ *
+ * \addtogroup xdp
+ * @{
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <netinet/in.h>
+
+#include "libknot/xdp/bpf-consts.h"
+#include "libknot/xdp/msg.h"
+
+/*!
+ * \brief Styles of loading BPF program.
+ *
+ * \note In *all* the cases loading can only succeed if at the end
+ *       a compatible BPF program is loaded on the interface.
+ */
+typedef enum {
+	KNOT_XDP_LOAD_BPF_NEVER,         /*!< Do not load; error out if not loaded already. */
+	KNOT_XDP_LOAD_BPF_ALWAYS,        /*!< Always load a program (overwrite it). */
+	KNOT_XDP_LOAD_BPF_ALWAYS_UNLOAD, /*!< KNOT_XDP_LOAD_BPF_ALWAYS + unload previous. */
+	KNOT_XDP_LOAD_BPF_MAYBE,         /*!< Try with present program or load if none. */
+	/* Implementation caveat: when re-using program in _MAYBE case, we get a message:
+	 * libbpf: Kernel error message: XDP program already attached */
+} knot_xdp_load_bpf_t;
+
+/*! \brief Context structure for one XDP socket. */
+typedef struct knot_xdp_socket knot_xdp_socket_t;
+
+/*!
+ * \brief Initialize XDP socket.
+ *
+ * \param socket       XDP socket.
+ * \param if_name      Name of the net iface (e.g. eth0).
+ * \param if_queue     Network card queue to be used (normally 1 socket per each queue).
+ * \param flags        XDP filter configuration flags.
+ * \param udp_port     UDP and/or TCP port to listen on if enabled via \a opts.
+ * \param quic_port    QUIC/UDP port to listen on if enabled via \a opts.
+ * \param load_bpf     Insert BPF program into packet processing.
+ * \param xdp_config   Optional XDP socket configuration.
+ *
+ * \return KNOT_E* or -errno
+ */
+int knot_xdp_init(knot_xdp_socket_t **socket, const char *if_name, int if_queue,
+                  knot_xdp_filter_flag_t flags, uint16_t udp_port, uint16_t quic_port,
+                  knot_xdp_load_bpf_t load_bpf, const void *xdp_config);
+
+/*!
+ * \brief De-init XDP socket.
+ *
+ * \param socket  XDP socket.
+ */
+void knot_xdp_deinit(knot_xdp_socket_t *socket);
+
+/*!
+ * \brief Return a file descriptor to be polled on for incoming packets.
+ *
+ * \param socket  XDP socket.
+ *
+ * \return KNOT_E*
+ */
+int knot_xdp_socket_fd(knot_xdp_socket_t *socket);
+
+/*!
+ * \brief Collect completed TX buffers, so they can be used by knot_xdp_send_alloc().
+ *
+ * \param socket  XDP socket.
+ */
+void knot_xdp_send_prepare(knot_xdp_socket_t *socket);
+
+/*!
+ * \brief Allocate one buffer for an outgoing packet.
+ *
+ * \param socket       XDP socket.
+ * \param flags        Flags for new message.
+ * \param out          Out: the allocated packet buffer.
+ *
+ * \return KNOT_E*
+ */
+int knot_xdp_send_alloc(knot_xdp_socket_t *socket, knot_xdp_msg_flag_t flags,
+                        knot_xdp_msg_t *out);
+
+/*!
+ * \brief Allocate one buffer for a reply packet.
+ *
+ * \param socket       XDP socket.
+ * \param query        The packet to be replied to.
+ * \param out          Out: the allocated packet buffer.
+ *
+ * \return KNOT_E*
+ */
+int knot_xdp_reply_alloc(knot_xdp_socket_t *socket, const knot_xdp_msg_t *query,
+                         knot_xdp_msg_t *out);
+
+/*!
+ * \brief Send multiple packets thru XDP.
+ *
+ * \note The packets all must have been allocated by knot_xdp_send_alloc()!
+ * \note Do not free the packet payloads afterwards.
+ * \note Packets with zero length will be skipped.
+ *
+ * \param socket  XDP socket.
+ * \param msgs    Packets to be sent.
+ * \param count   Number of packets.
+ * \param sent    Out: number of packet successfully sent.
+ *
+ * \return KNOT_E*
+ */
+int knot_xdp_send(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                  uint32_t count, uint32_t *sent);
+
+/*!
+ * \brief Cleanup messages that have not been knot_xdp_send().
+ *
+ * ...possibly due to some error.
+ *
+ * \param socket   XDP socket.
+ * \param msgs     Messages to be freed.
+ * \param count    Number of messages.
+ */
+void knot_xdp_send_free(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                        uint32_t count);
+
+/*!
+ * \brief Syscall to kernel to wake up the network card driver after knot_xdp_send().
+ *
+ * \param socket  XDP socket.
+ *
+ * \return KNOT_E* or -errno
+ */
+int knot_xdp_send_finish(knot_xdp_socket_t *socket);
+
+/*!
+ * \brief Receive multiple packets thru XDP.
+ *
+ * \param socket     XDP socket.
+ * \param msgs       Out: buffers to be filled in with incoming packets.
+ * \param max_count  Limit for number of packets received at once.
+ * \param count      Out: real number of received packets.
+ * \param wire_size  Out: (optional) total wire size of received packets.
+ *
+ * \return KNOT_E*
+ */
+int knot_xdp_recv(knot_xdp_socket_t *socket, knot_xdp_msg_t msgs[],
+                  uint32_t max_count, uint32_t *count, size_t *wire_size);
+
+/*!
+ * \brief Free buffers with received packets.
+ *
+ * \param socket  XDP socket.
+ * \param msgs    Buffers with received packets.
+ * \param count   Number of received packets to free.
+ */
+void knot_xdp_recv_finish(knot_xdp_socket_t *socket, const knot_xdp_msg_t msgs[],
+                          uint32_t count);
+
+/*!
+ * \brief Print some info about the XDP socket.
+ *
+ * \param socket  XDP socket.
+ * \param file    Output file.
+ */
+void knot_xdp_info(const knot_xdp_socket_t *socket, FILE *file);
+
+/*! @} */
diff --git a/src/libknot/yparser/yparser.c b/src/libknot/yparser/yparser.c
new file mode 100644
index 0000000..3004761
--- /dev/null
+++ b/src/libknot/yparser/yparser.c
@@ -0,0 +1,176 @@
+/*  Copyright (C) 2021 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 <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <unistd.h>
+
+#include "libknot/yparser/yparser.h"
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+
+extern int _yp_start_state;
+extern int _yp_parse(yp_parser_t *parser);
+
+_public_
+void yp_init(
+	yp_parser_t *parser)
+{
+	if (parser == NULL) {
+		return;
+	}
+
+	memset(parser, 0, sizeof(*parser));
+
+	parser->cs = _yp_start_state;
+	parser->file.descriptor = -1;
+	parser->line_count = 1;
+}
+
+_public_
+void yp_deinit(
+	yp_parser_t *parser)
+{
+	if (parser == NULL) {
+		return;
+	}
+
+	if (parser->file.descriptor != -1) {
+		munmap((void *)parser->input.start,
+		       parser->input.end - parser->input.start);
+		close(parser->file.descriptor);
+		free(parser->file.name);
+	}
+}
+
+_public_
+int yp_set_input_string(
+	yp_parser_t *parser,
+	const char *input,
+	size_t size)
+{
+	if (parser == NULL || input == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Reinitialize the parser.
+	yp_deinit(parser);
+	yp_init(parser);
+
+	// Set the parser input limits.
+	parser->input.start   = input;
+	parser->input.current = input;
+	parser->input.end     = input + size;
+	parser->input.eof     = false;
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_set_input_file(
+	yp_parser_t *parser,
+	const char *file_name)
+{
+	if (parser == NULL || file_name == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Reinitialize the parser.
+	yp_deinit(parser);
+	yp_init(parser);
+
+	// Try to open the file.
+	parser->file.descriptor = open(file_name, O_RDONLY);
+	if (parser->file.descriptor == -1) {
+		return knot_map_errno();
+	}
+
+	// Check for regular file input.
+	struct stat file_stat;
+	if (fstat(parser->file.descriptor, &file_stat) == -1) {
+		close(parser->file.descriptor);
+		return knot_map_errno();
+	} else if (!S_ISREG(file_stat.st_mode)) {
+		close(parser->file.descriptor);
+		return KNOT_EFILE;
+	}
+
+	// Check for empty file (cannot mmap).
+	if (file_stat.st_size > 0) {
+		// Map the file to the memory.
+		char *start = mmap(0, file_stat.st_size, PROT_READ, MAP_SHARED,
+		                   parser->file.descriptor, 0);
+		if (start == MAP_FAILED) {
+			close(parser->file.descriptor);
+			return KNOT_ENOMEM;
+		}
+
+		// Try to set the mapped memory advise to sequential.
+#if defined(MADV_SEQUENTIAL) && !defined(__sun)
+		(void)madvise(start, file_stat.st_size, MADV_SEQUENTIAL);
+#else
+#ifdef POSIX_MADV_SEQUENTIAL
+		(void)posix_madvise(start, file_stat.st_size, POSIX_MADV_SEQUENTIAL);
+#endif /* POSIX_MADV_SEQUENTIAL */
+#endif /* MADV_SEQUENTIAL && !__sun */
+
+		// Set the parser input limits.
+		parser->input.start   = start;
+		parser->input.current = start;
+		parser->input.end     = start + file_stat.st_size;
+
+		parser->input.eof = false;
+	} else {
+		parser->input.eof = true;
+	}
+
+	parser->file.name = strdup(file_name);
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_parse(
+	yp_parser_t *parser)
+{
+	if (parser == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret = KNOT_EPARSEFAIL;
+
+	// Run the parser until found new item, error or end of input.
+	do {
+		// Check for the end of the input.
+		if (parser->input.current == parser->input.end) {
+			if (parser->input.eof) {
+				// End of parsing.
+				return KNOT_EOF;
+			} else {
+				// Set the parser to final parsing.
+				parser->input.eof = true;
+			}
+		}
+
+		// Parse the next item.
+		ret = _yp_parse(parser);
+	} while (ret == KNOT_EFEWDATA);
+
+	return ret;
+}
diff --git a/src/libknot/yparser/yparser.h b/src/libknot/yparser/yparser.h
new file mode 100644
index 0000000..88e0e00
--- /dev/null
+++ b/src/libknot/yparser/yparser.h
@@ -0,0 +1,149 @@
+/*  Copyright (C) 2022 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Simple parser (Yparser) of a YAML-inspired data format.
+ *
+ * \addtogroup yparser
+ * @{
+ */
+
+#pragma once
+
+#include <stdbool.h>
+#include <stddef.h>
+
+/*! Maximal length of textual key value. */
+#define YP_MAX_TXT_KEY_LEN	127
+/*! Maximal length of textual data value. */
+#define YP_MAX_TXT_DATA_LEN	32767
+
+/*! Parser events indicating type of lastly parsed item. */
+typedef enum {
+	YP_ENULL = 0, /*!< No valid data. */
+	YP_EKEY0,     /*!< First level item. */
+	YP_EKEY1,     /*!< Second level item. */
+	YP_EID,       /*!< Second level identifier. */
+} yp_event_t;
+
+/*! Context structure of yparser. */
+typedef struct {
+	/*! Current parser state (Ragel internals). */
+	int cs;
+	/*! Indication if the current item was already processed. */
+	bool processed;
+	/*! Current block indentation. */
+	size_t indent;
+	/*! Last id dash position. */
+	size_t id_pos;
+
+	/*! Input parameters. */
+	struct {
+		/*! Start of the block. */
+		const char *start;
+		/*! Current parser position. */
+		const char *current;
+		/*! End of the block. */
+		const char *end;
+		/*! Indication for the final block parsing. */
+		bool eof;
+	} input;
+
+	/*! File input parameters. */
+	struct {
+		/*! File name. */
+		char *name;
+		/*! File descriptor. */
+		int descriptor;
+	} file;
+
+	/*! [out] Current line number (error location). */
+	size_t line_count;
+	/*! [out] Current event. */
+	yp_event_t event;
+	/*! [out] Parsed key (zero terminated string). */
+	char key[YP_MAX_TXT_KEY_LEN + 1];
+	/*! [out] Key length. */
+	size_t key_len;
+	/*! [out] Parsed data (zero terminated string). */
+	char data[YP_MAX_TXT_DATA_LEN + 1];
+	/*! [out] Data length. */
+	size_t data_len;
+} yp_parser_t;
+
+/*!
+ * Initializes the parser.
+ *
+ * \param[in] parser Parser context.
+ */
+void yp_init(
+	yp_parser_t *parser
+);
+
+/*!
+ * Deinitializes the parser.
+ *
+ * \param[in] parser Parser context.
+ */
+void yp_deinit(
+	yp_parser_t *parser
+);
+
+/*!
+ * Sets the parser to parse given string.
+ *
+ * \param[in] parser Parser context.
+ * \param[in] input The string to parse.
+ * \param[in] size Length of the string.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_set_input_string(
+	yp_parser_t *parser,
+	const char *input,
+	size_t size
+);
+
+/*!
+ * Sets the parser to parse given file.
+ *
+ * \param[in] parser Parser context.
+ * \param[in] file_name The filename to parse.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_set_input_file(
+	yp_parser_t *parser,
+	const char *file_name
+);
+
+/*!
+ * Parses one item from the input.
+ *
+ * If the item has more values, this function returns for each value. The item
+ * can also have no value.
+ *
+ * \param[in] parser Parser context.
+ *
+ * \return Error code, KNOT_EOK if success, KNOT_EOF if end of data.
+ */
+int yp_parse(
+	yp_parser_t *parser
+);
+
+/*! @} */
diff --git a/src/libknot/yparser/ypbody.c b/src/libknot/yparser/ypbody.c
new file mode 100644
index 0000000..ad9cf1f
--- /dev/null
+++ b/src/libknot/yparser/ypbody.c
@@ -0,0 +1,460 @@
+
+/*  Copyright (C) 2021 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 <string.h>
+
+#include "libknot/yparser/yparser.h"
+#include "libknot/errcode.h"
+
+
+
+
+// Include parser static data (Ragel internals).
+
+static const char _yparser_actions[] = {
+	0, 1, 0, 1, 1, 1, 2, 1,
+	3, 1, 4, 1, 6, 1, 8, 1,
+	9, 1, 10, 1, 11, 1, 12, 1,
+	15, 2, 1, 0, 2, 1, 2, 2,
+	1, 15, 2, 2, 0, 2, 3, 4,
+	2, 5, 4, 2, 6, 0, 2, 7,
+	8, 2, 12, 13, 2, 14, 12, 3,
+	1, 2, 0, 3, 1, 7, 8, 3,
+	1, 12, 13, 3, 1, 14, 12, 3,
+	2, 7, 8, 3, 2, 12, 13, 3,
+	2, 14, 12, 4, 1, 2, 7, 8,
+	4, 1, 2, 12, 13, 4, 1, 2,
+	14, 12
+};
+
+static const unsigned char _yparser_key_offsets[] = {
+	0, 0, 14, 16, 27, 29, 32, 43,
+	44, 54, 65, 67, 68, 78, 90, 94,
+	96, 99, 104, 107, 110, 122, 132, 142,
+	145, 148, 151, 156, 159, 162, 176, 190,
+	204
+};
+
+static const char _yparser_trans_keys[] = {
+	10, 13, 32, 35, 42, 45, 92, 95,
+	46, 57, 65, 90, 97, 122, 10, 13,
+	32, 42, 58, 92, 95, 45, 57, 65,
+	90, 97, 122, 32, 58, 10, 13, 32,
+	32, 42, 58, 92, 95, 45, 57, 65,
+	90, 97, 122, 32, 32, 42, 92, 95,
+	46, 57, 65, 90, 97, 122, 32, 42,
+	58, 92, 95, 45, 57, 65, 90, 97,
+	122, 32, 58, 32, 32, 34, 35, 44,
+	92, 127, 0, 31, 91, 93, 10, 13,
+	32, 44, 92, 127, 0, 31, 34, 35,
+	91, 93, 10, 13, 32, 35, 10, 13,
+	34, 32, 126, 34, 92, 127, 0, 31,
+	10, 13, 32, 34, 32, 126, 10, 13,
+	32, 34, 35, 44, 91, 92, 93, 127,
+	0, 31, 32, 34, 35, 44, 92, 127,
+	0, 31, 91, 93, 32, 44, 91, 92,
+	93, 127, 0, 31, 34, 35, 32, 44,
+	93, 10, 13, 32, 34, 32, 126, 34,
+	92, 127, 0, 31, 32, 44, 93, 34,
+	32, 126, 10, 13, 32, 35, 42, 45,
+	92, 95, 46, 57, 65, 90, 97, 122,
+	10, 13, 32, 35, 42, 45, 92, 95,
+	46, 57, 65, 90, 97, 122, 10, 13,
+	32, 35, 42, 45, 92, 95, 46, 57,
+	65, 90, 97, 122, 10, 13, 32, 35,
+	42, 45, 92, 95, 46, 57, 65, 90,
+	97, 122, 0
+};
+
+static const char _yparser_single_lengths[] = {
+	0, 8, 2, 5, 2, 3, 5, 1,
+	4, 5, 2, 1, 6, 6, 4, 2,
+	1, 3, 3, 1, 10, 6, 6, 3,
+	3, 1, 3, 3, 1, 8, 8, 8,
+	8
+};
+
+static const char _yparser_range_lengths[] = {
+	0, 3, 0, 3, 0, 0, 3, 0,
+	3, 3, 0, 0, 2, 3, 0, 0,
+	1, 1, 0, 1, 1, 2, 2, 0,
+	0, 1, 1, 0, 1, 3, 3, 3,
+	3
+};
+
+static const unsigned char _yparser_index_offsets[] = {
+	0, 0, 12, 15, 24, 27, 31, 40,
+	42, 50, 59, 62, 64, 73, 83, 88,
+	91, 94, 99, 103, 106, 118, 127, 136,
+	140, 144, 147, 152, 156, 159, 171, 183,
+	195
+};
+
+static const char _yparser_indicies[] = {
+	1, 2, 3, 4, 5, 6, 5, 5,
+	5, 5, 5, 0, 1, 2, 4, 7,
+	8, 9, 8, 8, 8, 8, 8, 0,
+	10, 11, 0, 12, 13, 14, 0, 15,
+	16, 17, 16, 16, 16, 16, 16, 0,
+	18, 0, 18, 19, 19, 19, 19, 19,
+	19, 0, 20, 21, 22, 21, 21, 21,
+	21, 21, 0, 23, 24, 0, 25, 0,
+	25, 27, 0, 0, 28, 0, 0, 0,
+	26, 30, 31, 32, 0, 33, 0, 0,
+	0, 0, 29, 12, 13, 34, 35, 0,
+	12, 13, 35, 36, 29, 0, 38, 39,
+	0, 0, 37, 30, 31, 32, 0, 40,
+	37, 0, 12, 13, 14, 27, 35, 0,
+	41, 28, 0, 0, 0, 26, 41, 43,
+	0, 0, 44, 0, 0, 0, 42, 46,
+	47, 0, 48, 49, 0, 0, 0, 45,
+	50, 41, 51, 0, 12, 13, 34, 0,
+	52, 45, 0, 54, 55, 0, 0, 53,
+	46, 47, 49, 0, 56, 53, 0, 1,
+	2, 3, 4, 57, 6, 57, 57, 57,
+	57, 57, 0, 59, 60, 61, 62, 63,
+	64, 63, 63, 63, 63, 63, 58, 65,
+	66, 67, 68, 69, 70, 69, 69, 69,
+	69, 69, 0, 71, 72, 73, 74, 75,
+	76, 75, 75, 75, 75, 75, 58, 0
+};
+
+static const char _yparser_trans_targs[] = {
+	0, 30, 31, 1, 2, 3, 7, 4,
+	3, 5, 4, 5, 32, 29, 20, 4,
+	6, 5, 8, 9, 10, 9, 11, 10,
+	11, 12, 13, 17, 16, 13, 32, 29,
+	14, 16, 14, 15, 13, 17, 18, 19,
+	17, 21, 22, 26, 25, 22, 23, 21,
+	25, 24, 23, 24, 22, 26, 27, 28,
+	26, 6, 0, 30, 31, 1, 2, 6,
+	7, 30, 31, 1, 2, 6, 7, 30,
+	31, 1, 2, 6, 7
+};
+
+static const char _yparser_trans_actions[] = {
+	23, 1, 0, 49, 0, 46, 52, 17,
+	13, 17, 0, 0, 1, 0, 0, 15,
+	13, 15, 21, 46, 19, 13, 19, 0,
+	0, 0, 37, 7, 37, 9, 43, 11,
+	11, 9, 0, 0, 40, 9, 0, 9,
+	40, 0, 37, 7, 37, 9, 11, 11,
+	9, 11, 0, 0, 40, 9, 0, 9,
+	40, 46, 31, 55, 28, 88, 28, 83,
+	93, 34, 5, 75, 5, 71, 79, 25,
+	3, 63, 3, 59, 67
+};
+
+static const char _yparser_eof_actions[] = {
+	0, 23, 23, 23, 23, 23, 23, 23,
+	23, 23, 23, 23, 23, 23, 23, 23,
+	23, 23, 23, 23, 23, 23, 23, 23,
+	23, 23, 23, 23, 23, 0, 28, 5,
+	3
+};
+
+
+
+
+
+int _yp_start_state = 29;
+
+int _yp_parse(
+	yp_parser_t *parser)
+{
+	// Parser input limits (Ragel internals).
+	const char *p, *pe, *eof;
+
+	// Current item indent.
+	size_t indent = 0;
+	// Current id dash position.
+	size_t id_pos = 0;
+	// Indicates if the current parsing step contains an item.
+	bool found = false;
+
+	if (!parser->input.eof) { // Restore parser input limits.
+		p = parser->input.current;
+		pe = parser->input.end;
+		eof = NULL;
+	} else { // Set the last artificial block with just one new line char.
+		p = "\n";
+		pe = p + 1;
+		eof = pe;
+	}
+
+	// Include parser body.
+
+	{
+	int _klen;
+	unsigned int _trans;
+	const char *_acts;
+	unsigned int _nacts;
+	const char *_keys;
+
+	if ( p == pe )
+		goto _test_eof;
+	if (  parser->cs == 0 )
+		goto _out;
+_resume:
+	_keys = _yparser_trans_keys + _yparser_key_offsets[ parser->cs];
+	_trans = _yparser_index_offsets[ parser->cs];
+
+	_klen = _yparser_single_lengths[ parser->cs];
+	if ( _klen > 0 ) {
+		const char *_lower = _keys;
+		const char *_mid;
+		const char *_upper = _keys + _klen - 1;
+		while (1) {
+			if ( _upper < _lower )
+				break;
+
+			_mid = _lower + ((_upper-_lower) >> 1);
+			if ( (*p) < *_mid )
+				_upper = _mid - 1;
+			else if ( (*p) > *_mid )
+				_lower = _mid + 1;
+			else {
+				_trans += (unsigned int)(_mid - _keys);
+				goto _match;
+			}
+		}
+		_keys += _klen;
+		_trans += _klen;
+	}
+
+	_klen = _yparser_range_lengths[ parser->cs];
+	if ( _klen > 0 ) {
+		const char *_lower = _keys;
+		const char *_mid;
+		const char *_upper = _keys + (_klen<<1) - 2;
+		while (1) {
+			if ( _upper < _lower )
+				break;
+
+			_mid = _lower + (((_upper-_lower) >> 1) & ~1);
+			if ( (*p) < _mid[0] )
+				_upper = _mid - 2;
+			else if ( (*p) > _mid[1] )
+				_lower = _mid + 2;
+			else {
+				_trans += (unsigned int)((_mid - _keys)>>1);
+				goto _match;
+			}
+		}
+		_trans += _klen;
+	}
+
+_match:
+	_trans = _yparser_indicies[_trans];
+	 parser->cs = _yparser_trans_targs[_trans];
+
+	if ( _yparser_trans_actions[_trans] == 0 )
+		goto _again;
+
+	_acts = _yparser_actions + _yparser_trans_actions[_trans];
+	_nacts = (unsigned int) *_acts++;
+	while ( _nacts-- > 0 )
+	{
+		switch ( *_acts++ )
+		{
+	case 0:
+	{
+		// Return if key without value.
+		if (parser->event != YP_ENULL && !parser->processed) {
+			parser->processed = true;
+			found = true;
+			{p++; goto _out; }
+		}
+	}
+	break;
+	case 1:
+	{
+		parser->line_count++;
+		parser->event = YP_ENULL;
+		parser->processed = false;
+	}
+	break;
+	case 2:
+	{
+		indent = 0;
+		id_pos = 0;
+	}
+	break;
+	case 3:
+	{
+		parser->data_len = 0;
+	}
+	break;
+	case 4:
+	{
+		if (parser->data_len >= sizeof(parser->data) - 1) {
+			return KNOT_ESPACE;
+		}
+		parser->data[parser->data_len++] = (*p);
+	}
+	break;
+	case 5:
+	{
+		parser->data_len--;
+	}
+	break;
+	case 6:
+	{
+		// Return if a value parsed.
+		parser->data[parser->data_len] = '\0';
+		parser->processed = true;
+		found = true;
+		{p++; goto _out; }
+	}
+	break;
+	case 7:
+	{
+		if (indent > 0 && parser->indent > 0 &&
+		    indent != parser->indent) {
+			return KNOT_YP_EINVAL_INDENT;
+		}
+		parser->processed = false;
+		parser->key_len = 0;
+		parser->data_len = 0;
+		parser->event = YP_ENULL;
+	}
+	break;
+	case 8:
+	{
+		if (parser->key_len >= sizeof(parser->key) - 1) {
+			return KNOT_ESPACE;
+		}
+		parser->key[parser->key_len++] = (*p);
+	}
+	break;
+	case 9:
+	{
+		parser->key[parser->key_len] = '\0';
+		parser->indent = 0;
+		parser->id_pos = 0;
+		parser->event = YP_EKEY0;
+	}
+	break;
+	case 10:
+	{
+		parser->key[parser->key_len] = '\0';
+		parser->indent = indent;
+		parser->event = YP_EKEY1;
+	}
+	break;
+	case 11:
+	{
+		parser->key[parser->key_len] = '\0';
+		parser->indent = indent;
+		parser->id_pos = id_pos;
+		parser->event = YP_EID;
+	}
+	break;
+	case 12:
+	{
+		indent++;
+	}
+	break;
+	case 13:
+	{
+		id_pos++;
+	}
+	break;
+	case 14:
+	{
+		if (id_pos > 0 && parser->id_pos > 0 &&
+		    id_pos != parser->id_pos) {
+			return KNOT_YP_EINVAL_INDENT;
+		}
+		parser->indent = 0;
+	}
+	break;
+	case 15:
+	{
+		switch ((*p)) {
+		case '\t':
+			return KNOT_YP_ECHAR_TAB;
+		default:
+			return KNOT_EPARSEFAIL;
+		}
+	}
+	break;
+		}
+	}
+
+_again:
+	if (  parser->cs == 0 )
+		goto _out;
+	if ( ++p != pe )
+		goto _resume;
+	_test_eof: {}
+	if ( p == eof )
+	{
+	const char *__acts = _yparser_actions + _yparser_eof_actions[ parser->cs];
+	unsigned int __nacts = (unsigned int) *__acts++;
+	while ( __nacts-- > 0 ) {
+		switch ( *__acts++ ) {
+	case 1:
+	{
+		parser->line_count++;
+		parser->event = YP_ENULL;
+		parser->processed = false;
+	}
+	break;
+	case 2:
+	{
+		indent = 0;
+		id_pos = 0;
+	}
+	break;
+	case 15:
+	{
+		switch ((*p)) {
+		case '\t':
+			return KNOT_YP_ECHAR_TAB;
+		default:
+			return KNOT_EPARSEFAIL;
+		}
+	}
+	break;
+		}
+	}
+	}
+
+	_out: {}
+	}
+
+
+	// Store the current parser position.
+	if (!parser->input.eof) {
+		parser->input.current = p;
+	} else {
+		parser->input.current = parser->input.end;
+	}
+
+	// Check for general parser error.
+	if (parser->cs == 0) {
+		return KNOT_EPARSEFAIL;
+	}
+
+	// Check if parsed an item.
+	if (found) {
+		return KNOT_EOK;
+	} else {
+		return KNOT_EFEWDATA;
+	}
+}
diff --git a/src/libknot/yparser/ypformat.c b/src/libknot/yparser/ypformat.c
new file mode 100644
index 0000000..3284924
--- /dev/null
+++ b/src/libknot/yparser/ypformat.c
@@ -0,0 +1,121 @@
+/*  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 <stdio.h>
+
+#include "libknot/yparser/yptrafo.h"
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+
+static int format_item(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style,
+	const char *prefix,
+	bool first_value,
+	bool last_value)
+{
+	if (item == NULL || out == NULL || prefix == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Format key part.
+	int ret = snprintf(out, out_len, "%s%s%s%s",
+	                   first_value ? prefix : "",
+	                   first_value ? item->name + 1 : "",
+	                   first_value ? ":" : "",
+	                   item->type == YP_TGRP ?
+	                     "\n" : (first_value && !last_value ? " [ " : " "));
+	if (ret < 0 || ret >= out_len) {
+		return KNOT_ESPACE;
+	}
+	out     += ret;
+	out_len -= ret;
+
+	// Finish if group.
+	if (item->type == YP_TGRP) {
+		return KNOT_EOK;
+	}
+
+	// Format data part.
+	size_t aux_len = out_len;
+	ret = yp_item_to_txt(item, data, data_len, out, &aux_len, style);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+	out     += aux_len;
+	out_len -= aux_len;
+
+	// Format data end.
+	ret = snprintf(out, out_len, "%s%s",
+	               last_value && !first_value ? " ]" : "",
+	               last_value ? "\n" : ",");
+	if (ret < 0 || ret >= out_len) {
+		return KNOT_ESPACE;
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_format_key0(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style,
+	bool first_value,
+	bool last_value)
+{
+	return format_item(item, data, data_len, out, out_len, style, "",
+	                   first_value, last_value);
+}
+
+_public_
+int yp_format_id(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style)
+{
+	if (data == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	return format_item(item, data, data_len, out, out_len, style, "  - ",
+	                   true, true);
+}
+
+_public_
+int yp_format_key1(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style,
+	bool first_value,
+	bool last_value)
+{
+	return format_item(item, data, data_len, out, out_len, style, "    ",
+	                   first_value, last_value);
+}
diff --git a/src/libknot/yparser/ypformat.h b/src/libknot/yparser/ypformat.h
new file mode 100644
index 0000000..c1d21bd
--- /dev/null
+++ b/src/libknot/yparser/ypformat.h
@@ -0,0 +1,101 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Tools for Yparser format creation.
+ *
+ * \addtogroup yparser
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/yparser/ypschema.h"
+
+/*!
+ * Formats key0 item.
+ *
+ * \param[in] item Schema item to format.
+ * \param[in] data Data to format.
+ * \param[in] data_len Data length.
+ * \param[out] out Output buffer.
+ * \param[in, out] out_len Output buffer length, output length.
+ * \param[in] style Value style.
+ * \param[in] first_value First value indication (multivalued support).
+ * \param[in] last_value Last value indication (multivalued support).
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_format_key0(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style,
+	bool first_value,
+	bool last_value
+);
+
+/*!
+ * Formats identifier item.
+ *
+ * \param[in] item Schema item to format.
+ * \param[in] data Data to format.
+ * \param[in] data_len Data length.
+ * \param[out] out Output buffer.
+ * \param[in, out] out_len Output buffer length, output length.
+ * \param[in] style Value style.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_format_id(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style
+);
+
+/*!
+ * Formats key1 item.
+ *
+ * \param[in] item Schema item to format.
+ * \param[in] data Data to format.
+ * \param[in] data_len Data length.
+ * \param[out] out Output buffer.
+ * \param[in, out] out_len Output buffer length, output length.
+ * \param[in] style Value style.
+ * \param[in] first_value First value indication (multivalued support).
+ * \param[in] last_value Last value indication (multivalued support).
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_format_key1(
+	const yp_item_t *item,
+	const uint8_t *data,
+	size_t data_len,
+	char *out,
+	size_t out_len,
+	yp_style_t style,
+	bool first_value,
+	bool last_value
+);
+
+/*! @} */
diff --git a/src/libknot/yparser/ypschema.c b/src/libknot/yparser/ypschema.c
new file mode 100644
index 0000000..0ac5b57
--- /dev/null
+++ b/src/libknot/yparser/ypschema.c
@@ -0,0 +1,598 @@
+/*  Copyright (C) 2021 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 <stdlib.h>
+#include <string.h>
+
+#include "libknot/yparser/ypschema.h"
+#include "libknot/yparser/yptrafo.h"
+#include "libknot/attribute.h"
+#include "libknot/errcode.h"
+
+static size_t schema_count(
+	const yp_item_t *src)
+{
+	size_t count = 0;
+	for (const yp_item_t *item = src; item->name != NULL; item++) {
+		count++;
+	}
+
+	return count;
+}
+
+/*! Initializes the referenced item. */
+static int set_ref_item(
+	yp_item_t *dst,
+	const yp_item_t *schema)
+{
+	if (schema == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Get referenced section.
+	const yp_name_t *ref_name = dst->var.r.ref_name;
+	const yp_item_t *ref = yp_schema_find(ref_name, NULL, schema);
+	if (ref == NULL) {
+		return KNOT_YP_EINVAL_ITEM;
+	}
+	dst->var.r.ref = ref;
+
+	// Get referenced group if supported.
+	const yp_name_t *grp_ref_name = dst->var.r.grp_ref_name;
+	if (grp_ref_name != NULL) {
+		const yp_item_t *grp_ref = yp_schema_find(grp_ref_name, NULL, schema);
+		if (grp_ref == NULL) {
+			return KNOT_YP_EINVAL_ITEM;
+		}
+		dst->var.r.grp_ref = grp_ref;
+	}
+
+	return KNOT_EOK;
+}
+
+/*! Copies the sub_items list and initializes pointer to the identifier item. */
+static int set_grp_item(
+	yp_item_t *dst,
+	const yp_item_t *src,
+	const yp_item_t *schema)
+{
+	// Count subitems.
+	size_t count = schema_count(src->var.g.sub_items);
+
+	// Allocate space for subitems + terminal zero item.
+	size_t memsize = (count + 1) * sizeof(yp_item_t);
+	dst->sub_items = malloc(memsize);
+	if (dst->sub_items == NULL) {
+		return KNOT_ENOMEM;
+	}
+	memset(dst->sub_items, 0, memsize);
+
+	// Copy subitems.
+	for (size_t i = 0; i < count; i++) {
+		// The first item is an identifier if multi group.
+		if (i == 0 && (dst->flags & YP_FMULTI)) {
+			dst->var.g.id = &dst->sub_items[0];
+		}
+
+		// Copy sub-item.
+		dst->sub_items[i] = src->var.g.sub_items[i];
+
+		// Initialize sub-item.
+		int ret = KNOT_EOK;
+		switch (dst->sub_items[i].type) {
+		case YP_TREF:
+			ret = set_ref_item(dst->sub_items + i, schema);
+			break;
+		case YP_TGRP: // Deeper hierarchy is not supported.
+			ret = KNOT_ENOTSUP;
+			break;
+		default:
+			break;
+		}
+
+		// Set the parent item.
+		dst->sub_items[i].parent = dst;
+
+		if (ret != KNOT_EOK) {
+			free(dst->sub_items);
+			dst->sub_items = NULL;
+			return ret;
+		}
+	}
+
+	if (src->flags & YP_FALLOC) {
+		dst->var.g.sub_items = malloc(memsize);
+		if (dst->var.g.sub_items == NULL) {
+			free(dst->sub_items);
+			dst->sub_items = NULL;
+			return KNOT_ENOMEM;
+		}
+		memcpy((void *)dst->var.g.sub_items, src->var.g.sub_items, memsize);
+	}
+
+	return KNOT_EOK;
+}
+
+static int set_item(
+	yp_item_t *dst,
+	const yp_item_t *src,
+	const yp_item_t *schema)
+{
+	// Check maximal item name length.
+	if ((uint8_t)src->name[0] > YP_MAX_ITEM_NAME_LEN) {
+		return KNOT_ERANGE;
+	}
+
+	// Copy the static data.
+	*dst = *src;
+
+	// Copy item name into dynamic memory.
+	if (src->flags & YP_FALLOC) {
+		dst->name = malloc(src->name[0] + 2);
+		if (dst->name == NULL) {
+			return KNOT_ENOMEM;
+		}
+		memcpy((void *)dst->name, src->name, src->name[0] + 2);
+	}
+
+	int ret;
+
+	// Item type specific preparation.
+	switch (src->type) {
+	case YP_TREF:
+		ret = set_ref_item(dst, schema);
+		break;
+	case YP_TGRP:
+		ret = set_grp_item(dst, src, schema);
+		break;
+	default:
+		ret = KNOT_EOK;
+	}
+
+	if (ret != KNOT_EOK && src->flags & YP_FALLOC) {
+		free((void *)dst->name);
+	}
+
+	return ret;
+}
+
+static void unset_item(
+	yp_item_t *item)
+{
+	if (item->flags & YP_FALLOC) {
+		free((void *)item->name);
+	}
+	if (item->type & YP_TGRP) {
+		free(item->sub_items);
+		if (item->flags & YP_FALLOC) {
+			free((void *)item->var.g.sub_items);
+		}
+	}
+
+	memset(item, 0, sizeof(yp_item_t));
+}
+
+static int schema_copy(
+	yp_item_t *dst,
+	const yp_item_t *src,
+	const yp_item_t *schema)
+{
+	// Copy the schema.
+	for (int i = 0; src[i].name != NULL; i++) {
+		int ret = set_item(&dst[i], &src[i], schema);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_schema_copy(
+	yp_item_t **dst,
+	const yp_item_t *src)
+{
+	if (dst == NULL || src == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Allocate space for new schema (+ terminal NULL item).
+	size_t size = (schema_count(src) + 1) * sizeof(yp_item_t);
+	yp_item_t *out = malloc(size);
+	if (out == NULL) {
+		return KNOT_ENOMEM;
+	}
+	memset(out, 0, size);
+
+	// Copy the schema.
+	int ret = schema_copy(out, src, out);
+	if (ret != KNOT_EOK) {
+		free(out);
+		return ret;
+	}
+
+	*dst = out;
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_schema_merge(
+	yp_item_t **dst,
+	const yp_item_t *src1,
+	const yp_item_t *src2)
+{
+	if (dst == NULL || src1 == NULL || src2 == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t count1 = schema_count(src1);
+	size_t count2 = schema_count(src2);
+
+	// Allocate space for new schema (+ terminal NULL item).
+	size_t size = (count1 + count2 + 1) * sizeof(yp_item_t);
+	yp_item_t *out = malloc(size);
+	if (out == NULL) {
+		return KNOT_ENOMEM;
+	}
+	memset(out, 0, size);
+
+	// Copy the first schema.
+	int ret = schema_copy(out, src1, out);
+	if (ret != KNOT_EOK) {
+		free(out);
+		return ret;
+	}
+
+	// Copy the second schema.
+	ret = schema_copy(out + count1, src2, out);
+	if (ret != KNOT_EOK) {
+		free(out);
+		return ret;
+	}
+
+	*dst = out;
+
+	return KNOT_EOK;
+}
+
+_public_
+void yp_schema_purge_dynamic(
+	yp_item_t *schema)
+{
+	if (schema == NULL) {
+		return;
+	}
+
+	for (yp_item_t *item = schema; item->name != NULL; item++) {
+		if (item->flags & YP_FALLOC) {
+			unset_item(item);
+		}
+	}
+}
+
+_public_
+void yp_schema_free(
+	yp_item_t *schema)
+{
+	if (schema == NULL) {
+		return;
+	}
+
+	for (yp_item_t *item = schema; item->name != NULL; item++) {
+		unset_item(item);
+	}
+	free(schema);
+}
+
+/*! Search the schema for an item with the given name. */
+static const yp_item_t* find_item(
+	const char *name,
+	size_t name_len,
+	const yp_item_t *schema)
+{
+	if (name == NULL || schema == NULL) {
+		return NULL;
+	}
+
+	for (const yp_item_t *item = schema; item->name != NULL; item++) {
+		if (item->name[0] != name_len) {
+			continue;
+		}
+		if (memcmp(item->name + 1, name, name_len) == 0) {
+			return item;
+		}
+	}
+
+	return NULL;
+}
+
+_public_
+const yp_item_t* yp_schema_find(
+	const yp_name_t *name,
+	const yp_name_t *parent_name,
+	const yp_item_t *schema)
+{
+	if (name == NULL || schema == NULL) {
+		return NULL;
+	}
+
+	if (parent_name == NULL) {
+		return find_item(name + 1, name[0], schema);
+	} else {
+		const yp_item_t *parent = find_item(parent_name + 1,
+		                                    parent_name[0], schema);
+		if (parent == NULL) {
+			return NULL;
+		}
+		return find_item(name + 1, name[0], parent->sub_items);
+	}
+}
+
+_public_
+yp_check_ctx_t* yp_schema_check_init(
+	yp_item_t **schema)
+{
+	if (schema == NULL) {
+		return NULL;
+	}
+
+	yp_check_ctx_t *ctx = malloc(sizeof(yp_check_ctx_t));
+	if (ctx == NULL) {
+		return NULL;
+	}
+	memset(ctx, 0, sizeof(yp_check_ctx_t));
+
+	ctx->schema = schema;
+
+	return ctx;
+}
+
+static void reset_ctx(
+	yp_check_ctx_t *ctx,
+	size_t index)
+{
+	assert(index < YP_MAX_NODE_DEPTH);
+
+	yp_node_t *node = &ctx->nodes[index];
+
+	node->parent = (index > 0) ? &ctx->nodes[index - 1] : NULL;
+	node->item = NULL;
+	node->id_len = 0;
+	node->data_len = 0;
+
+	ctx->current = index;
+}
+
+static int check_item(
+	const char *key,
+	size_t key_len,
+	const char *data,
+	size_t data_len,
+	yp_check_ctx_t *ctx,
+	bool allow_key1_without_id)
+{
+	yp_node_t *node = &ctx->nodes[ctx->current];
+	yp_node_t *parent = node->parent;
+	bool is_id = false;
+
+	if (parent != NULL) {
+		// Check for invalid indentation.
+		if (parent->item == NULL) {
+			return KNOT_YP_EINVAL_INDENT;
+		}
+
+		// Check if valid group parent.
+		if (parent->item->type != YP_TGRP) {
+			return KNOT_YP_EINVAL_ITEM;
+		}
+
+		// Check if valid subitem.
+		node->item = find_item(key, key_len, parent->item->sub_items);
+	} else {
+		node->item = find_item(key, key_len, *ctx->schema);
+	}
+	if (node->item == NULL) {
+		return KNOT_YP_EINVAL_ITEM;
+	}
+
+	// Check if the parent requires id specification.
+	if (parent != NULL && parent->item->var.g.id != NULL) {
+		// Check if id.
+		if (node->item == parent->item->var.g.id) {
+			is_id = true;
+			// Move current to the parent.
+			--(ctx->current);
+		// Check for missing id.
+		} else if (parent->id_len == 0 && !allow_key1_without_id) {
+			return KNOT_YP_ENOID;
+		}
+	}
+
+	// Return if no data provided.
+	if (data == NULL) {
+		return KNOT_EOK;
+	}
+
+	// Group cannot have data.
+	if (data_len != 0 && node->item->type == YP_TGRP) {
+		return KNOT_YP_ENOTSUP_DATA;
+	}
+
+	// Convert item data to binary format.
+	const yp_item_t *item = (node->item->type != YP_TREF) ?
+	                        node->item : node->item->var.r.ref->var.g.id;
+	if (is_id) {
+		// Textual id must not be empty.
+		if (data_len == 0) {
+			return KNOT_YP_ENODATA;
+		}
+
+		parent->id_len = sizeof(((yp_node_t *)NULL)->id);
+		int ret = yp_item_to_bin(item, data, data_len, parent->id,
+		                         &parent->id_len);
+
+		// Binary id must not be empty.
+		if (ret == KNOT_EOK && parent->id_len == 0) {
+			return KNOT_YP_EINVAL_DATA;
+		}
+
+		return ret;
+	} else {
+		node->data_len = sizeof(((yp_node_t *)NULL)->data);
+		int ret = yp_item_to_bin(item, data, data_len, node->data,
+		                         &node->data_len);
+		return ret;
+	}
+}
+
+_public_
+int yp_schema_check_parser(
+	yp_check_ctx_t *ctx,
+	const yp_parser_t *parser)
+{
+	if (ctx == NULL || parser == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	int ret;
+
+	switch (parser->event) {
+	case YP_EKEY0:
+		reset_ctx(ctx, 0);
+		ret = check_item(parser->key, parser->key_len, parser->data,
+		                 parser->data_len, ctx, false);
+		break;
+	case YP_EKEY1:
+		reset_ctx(ctx, 1);
+		ret = check_item(parser->key, parser->key_len, parser->data,
+		                 parser->data_len, ctx, false);
+		if (ret != KNOT_EOK) {
+			break;
+		}
+
+		// Check for KEY1 event with id item.
+		if (ctx->current != 1) {
+			return KNOT_YP_ENOTSUP_ID;
+		}
+
+		break;
+	case YP_EID:
+		reset_ctx(ctx, 1);
+		ret = check_item(parser->key, parser->key_len, parser->data,
+		                 parser->data_len, ctx, false);
+		if (ret != KNOT_EOK) {
+			break;
+		}
+
+		// Check for ID event with nonid item.
+		if (ctx->current != 0) {
+			return KNOT_YP_EINVAL_ID;
+		}
+
+		break;
+	default:
+		ret = KNOT_EPARSEFAIL;
+		break;
+	}
+
+	return ret;
+}
+
+_public_
+int yp_schema_check_str(
+	yp_check_ctx_t *ctx,
+	const char *key0,
+	const char *key1,
+	const char *id,
+	const char *data)
+{
+	if (ctx == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	size_t key0_len = (key0 != NULL) ? strlen(key0) : 0;
+	size_t key1_len = (key1 != NULL) ? strlen(key1) : 0;
+	size_t id_len   = (id   != NULL) ? strlen(id)   : 0;
+	size_t data_len = (data != NULL) ? strlen(data) : 0;
+
+	// Key0 must always be non-empty.
+	if (key0_len == 0) {
+		return KNOT_YP_EINVAL_ITEM;
+	}
+
+	// Process key0.
+	reset_ctx(ctx, 0);
+	if (key1_len == 0) {
+		int ret = check_item(key0, key0_len, data, data_len, ctx, false);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	} else {
+		int ret = check_item(key0, key0_len, NULL, 0, ctx, false);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	// Process id.
+	if (id_len != 0) {
+		if (ctx->nodes[0].item->type != YP_TGRP ||
+		    ctx->nodes[0].item->var.g.id == NULL) {
+			return KNOT_YP_ENOTSUP_ID;
+		}
+		const yp_name_t *name = ctx->nodes[0].item->var.g.id->name;
+
+		reset_ctx(ctx, 1);
+		int ret = check_item(name + 1, name[0], id, id_len, ctx, true);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+
+		// Check for non-id item (should not happen).
+		assert(ctx->current == 0);
+
+		// Check for group id with data.
+		if (key1_len == 0 && data != NULL) {
+			return KNOT_YP_ENOTSUP_DATA;
+		}
+	}
+
+	// Process key1.
+	if (key1_len != 0) {
+		reset_ctx(ctx, 1);
+		int ret = check_item(key1, key1_len, data, data_len, ctx, true);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+
+		// Check for id in key1 with extra data.
+		if (ctx->current != 1 && id_len != 0 && data != NULL) {
+			return KNOT_YP_ENOTSUP_DATA;
+		}
+	}
+
+	return KNOT_EOK;
+}
+
+_public_
+void yp_schema_check_deinit(
+	yp_check_ctx_t* ctx)
+{
+	free(ctx);
+}
diff --git a/src/libknot/yparser/ypschema.h b/src/libknot/yparser/ypschema.h
new file mode 100644
index 0000000..91e5165
--- /dev/null
+++ b/src/libknot/yparser/ypschema.h
@@ -0,0 +1,352 @@
+/*  Copyright (C) 2021 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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Schema layer for Yparser.
+ *
+ * \addtogroup yparser
+ * @{
+ */
+
+#pragma once
+
+#include <stdint.h>
+#include <stddef.h>
+
+#include "libknot/yparser/yparser.h"
+#include "libknot/lookup.h"
+
+struct wire_ctx;
+
+/*! Maximal length of item name. */
+#define YP_MAX_ITEM_NAME_LEN	64
+/*! Maximal length of binary identifier name (maximal dname length). */
+#define YP_MAX_ID_LEN		255
+/*! Maximal length of binary data (rough limit). */
+#define YP_MAX_DATA_LEN		32768
+/*! Integer item nil definition. */
+#define YP_NIL			INT64_MIN
+/*! Maximal number of miscellaneous callbacks/pointers. */
+#define YP_MAX_MISC_COUNT	4
+/*! Maximal node stack depth. */
+#define YP_MAX_NODE_DEPTH	2
+
+#define YP_TXT_BIN_PARAMS 	struct wire_ctx *in, struct wire_ctx *out, const uint8_t *stop
+#define YP_BIN_TXT_PARAMS	struct wire_ctx *in, struct wire_ctx *out
+
+/*! Helper macros for item variables definition. */
+#define YP_VNONE	.var.i = { 0 }
+#define YP_VINT		.var.i
+#define YP_VBOOL	.var.b
+#define YP_VOPT		.var.o
+#define YP_VSTR		.var.s
+#define YP_VADDR	.var.a
+#define YP_VNET		.var.d
+#define YP_VDNAME	.var.d
+#define YP_VHEX		.var.d
+#define YP_VB64		.var.d
+#define YP_VDATA	.var.d
+#define YP_VREF		.var.r
+#define YP_VGRP		.var.g
+
+/*! Schema item name is a char string with a leading byte (string length). */
+typedef char yp_name_t;
+
+/*! Schema item type. */
+typedef enum {
+	YP_TNONE = 0, /*!< Unspecified. */
+	YP_TINT,      /*!< Integer. */
+	YP_TBOOL,     /*!< Boolean. */
+	YP_TOPT,      /*!< Option from the list. */
+	YP_TSTR,      /*!< String. */
+	YP_THEX,      /*!< String or hexadecimal string if "0x" prefix. */
+	YP_TADDR,     /*!< Address (address[\@port] or UNIX socket path). */
+	YP_TNET,      /*!< Network address range (address[/mask] or address-address). */
+	YP_TDNAME,    /*!< Domain name. */
+	YP_TB64,      /*!< Base64 encoded string. */
+	YP_TDATA,     /*!< Customized data. */
+	YP_TREF,      /*!< Reference to another item. */
+	YP_TGRP,      /*!< Group of sub-items. */
+} yp_type_t;
+
+/*! Schema item flags. */
+typedef enum {
+	YP_FNONE  = 0,       /*!< Unspecified. */
+	YP_FMULTI = 1 <<  0, /*!< Multivalued item. */
+	YP_FALLOC = 1 <<  1, /*!< Allocated item. */
+	YP_FUSR1  = 1 <<  5, /*!< User-defined flag1. */
+	YP_FUSR2  = 1 <<  6, /*!< User-defined flag2. */
+	YP_FUSR3  = 1 <<  7, /*!< User-defined flag3. */
+	YP_FUSR4  = 1 <<  8, /*!< User-defined flag4. */
+	YP_FUSR5  = 1 <<  9, /*!< User-defined flag5. */
+	YP_FUSR6  = 1 << 10, /*!< User-defined flag6. */
+	YP_FUSR7  = 1 << 11, /*!< User-defined flag7. */
+	YP_FUSR8  = 1 << 12, /*!< User-defined flag8. */
+	YP_FUSR9  = 1 << 13, /*!< User-defined flag9. */
+	YP_FUSR10 = 1 << 14, /*!< User-defined flag10. */
+	YP_FUSR11 = 1 << 15, /*!< User-defined flag11. */
+	YP_FUSR12 = 1 << 16, /*!< User-defined flag12. */
+	YP_FUSR13 = 1 << 17, /*!< User-defined flag13. */
+	YP_FUSR14 = 1 << 18, /*!< User-defined flag14. */
+	YP_FUSR15 = 1 << 19, /*!< User-defined flag15. */
+	YP_FUSR16 = 1 << 20, /*!< User-defined flag16. */
+} yp_flag_t;
+
+/*! Schema item style. */
+typedef enum {
+	YP_SNONE    = 0,      /*!< Unspecified. */
+	YP_SSIZE    = 1 << 0, /*!< Size unit (B, K, M, G) (in, out). */
+	YP_STIME    = 1 << 1, /*!< Time unit (s, m, h, d) (in, out). */
+	YP_SUNIT    = YP_SSIZE | YP_STIME, /*!< Unit (in, out). */
+	YP_SNOQUOTE = 1 << 2  /*!< Unquoted value (out). */
+} yp_style_t;
+
+typedef struct yp_item yp_item_t;
+
+/*! Schema item variables (type dependent). */
+typedef union {
+	/*! Integer variables. */
+	struct {
+		/*! Minimal value. */
+		int64_t min;
+		/*! Maximal value. */
+		int64_t max;
+		/*! Default value. */
+		int64_t dflt;
+		/*! Possible unit type. */
+		yp_style_t unit;
+	} i;
+	/*! Boolean variables. */
+	struct {
+		/*! Default value. */
+		bool dflt;
+	} b;
+	/*! Option variables. */
+	struct {
+		/*! List of options (maximal value is 255). */
+		struct knot_lookup const *opts;
+		/*! Default value. */
+		unsigned dflt;
+	} o;
+	/*! String variables. */
+	struct {
+		/*! Default value. */
+		char const *dflt;
+	} s;
+	/*! Address variables. */
+	struct {
+		/*! Default port. */
+		uint16_t dflt_port;
+		/*! Default socket. */
+		char const *dflt_socket;
+	} a;
+	/*! Customized data variables. */
+	struct {
+		/*! Length of default data. */
+		size_t dflt_len;
+		/*! Default data. */
+		uint8_t const *dflt;
+		/*! Text to binary transformation function. */
+		int (*to_bin)(YP_TXT_BIN_PARAMS);
+		/*! Binary to text transformation function. */
+		int (*to_txt)(YP_BIN_TXT_PARAMS);
+	} d;
+	/*! Reference variables. */
+	struct {
+		/*! Referenced section name. */
+		yp_name_t const *ref_name;
+		/*! Referenced group section name (optional). */
+		yp_name_t const *grp_ref_name;
+		/*! Referenced section item (dynamic value). */
+		yp_item_t const *ref;
+		/*! Referenced group section item (dynamic value). */
+		yp_item_t const *grp_ref;
+	} r;
+	/*! Group variables. */
+	struct {
+		/*! List of sub-items. */
+		yp_item_t const *sub_items;
+		/*! ID item of sub-items (dynamic value). */
+		yp_item_t const *id;
+	} g;
+} yp_var_t;
+
+/*! Schema item specification. */
+struct yp_item {
+	/*! Item name. */
+	const yp_name_t *name;
+	/*! Item type. */
+	yp_type_t type;
+	/*! Item parameters. */
+	yp_var_t var;
+	/*! Item flags. */
+	yp_flag_t flags;
+	/*! Arbitrary data/callbacks. */
+	const void *misc[YP_MAX_MISC_COUNT];
+	/*! Parent item. */
+	yp_item_t *parent;
+	/*! Item group subitems (name=NULL terminated array). */
+	yp_item_t *sub_items;
+};
+
+typedef struct yp_node yp_node_t;
+struct yp_node {
+	/*! Parent node. */
+	yp_node_t *parent;
+	/*! Node item descriptor. */
+	const yp_item_t *item;
+	/*! Current binary id length. */
+	size_t id_len;
+	/*! Current binary id. */
+	uint8_t id[YP_MAX_ID_LEN];
+	/*! Current item data length. */
+	size_t data_len;
+	/*! Current item data. */
+	uint8_t data[YP_MAX_DATA_LEN];
+};
+
+/*! Context parameters for check operations. */
+typedef struct {
+	/*! Used schema. */
+	yp_item_t **schema;
+	/*! Index of the current node. */
+	size_t current;
+	/*! Node stack. */
+	yp_node_t nodes[YP_MAX_NODE_DEPTH];
+} yp_check_ctx_t;
+
+/*!
+ * Copies the schema and reinitializes dynamic parameters.
+ *
+ * \param[out] dst New copy of the schema.
+ * \param[in] src Source schema.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_schema_copy(
+	yp_item_t **dst,
+	const yp_item_t *src
+);
+
+/*!
+ * Merges two schemas.
+ *
+ * \param[out] dst Merged schema.
+ * \param[in] src1 Source schema1.
+ * \param[in] src2 Source schema2.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_schema_merge(
+	yp_item_t **dst,
+	const yp_item_t *src1,
+	const yp_item_t *src2
+);
+
+/*!
+ * Purges dynamic items from the schema.
+ *
+ * \param[in] schema Schema to purge.
+ */
+void yp_schema_purge_dynamic(
+	yp_item_t *schema
+);
+
+/*!
+ * Deallocates the schema.
+ *
+ * \param[in] schema A schema returned by #yp_schema_copy().
+ */
+void yp_schema_free(
+	yp_item_t *schema
+);
+
+/*!
+ * Tries to find given parent_name/name in the schema.
+ *
+ * \param[in] name Name of the item.
+ * \param[in] parent_name Name of the parent item (NULL if no parent).
+ * \param[in] schema Schema.
+ *
+ * \return Item, NULL if not found or error.
+ */
+const yp_item_t* yp_schema_find(
+	const yp_name_t *name,
+	const yp_name_t *parent_name,
+	const yp_item_t *schema
+);
+
+/*!
+ * Prepares a context for item check against the schema.
+ *
+ * \param[in] schema Schema.
+ *
+ * \return Context, NULL if error.
+ */
+yp_check_ctx_t* yp_schema_check_init(
+	yp_item_t **schema
+);
+
+/*!
+ * Checks the current parser output against the schema.
+ *
+ * If the item is correct, context also contains binary value of the item.
+ *
+ * \param[in,out] ctx Check context.
+ * \param[in] parser Parser context.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_schema_check_parser(
+	yp_check_ctx_t *ctx,
+	const yp_parser_t *parser
+);
+
+/*!
+ * Checks the string data against the schema.
+ *
+ * Description: key0[id].key1 data
+ *
+ * If the item is correct, context also contains binary value of the item.
+ *
+ * \param[in,out] ctx Check context.
+ * \param[in] key0 Key0 item name.
+ * \param[in] key1 Key1 item name.
+ * \param[in] id Item identifier.
+ * \param[in] data Item data (NULL means no data provided).
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_schema_check_str(
+	yp_check_ctx_t *ctx,
+	const char *key0,
+	const char *key1,
+	const char *id,
+	const char *data
+);
+
+/*!
+ * Deallocates the context.
+ *
+ * \param[in,out] ctx Check context.
+ */
+void yp_schema_check_deinit(
+	yp_check_ctx_t *ctx
+);
+
+/*! @} */
diff --git a/src/libknot/yparser/yptrafo.c b/src/libknot/yparser/yptrafo.c
new file mode 100644
index 0000000..7b040d9
--- /dev/null
+++ b/src/libknot/yparser/yptrafo.c
@@ -0,0 +1,1099 @@
+/*  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 <arpa/inet.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "libknot/yparser/yptrafo.h"
+#include "libknot/attribute.h"
+#include "libknot/consts.h"
+#include "libknot/dname.h"
+#include "contrib/base64.h"
+#include "contrib/ctype.h"
+#include "contrib/musl/inet_ntop.h"
+#include "contrib/sockaddr.h"
+#include "contrib/wire_ctx.h"
+
+enum {
+	UNIT_BYTE = 'B',
+	UNIT_KILO = 'K',
+	UNIT_MEGA = 'M',
+	UNIT_GIGA = 'G',
+	UNIT_SEC  = 's',
+	UNIT_MIN  = 'm',
+	UNIT_HOUR = 'h',
+	UNIT_DAY  = 'd'
+};
+
+enum {
+	MULTI_BYTE = 1,
+	MULTI_KILO = 1024,
+	MULTI_MEGA = 1024 * 1024,
+	MULTI_GIGA = 1024 * 1024 * 1024,
+	MULTI_SEC  = 1,
+	MULTI_MIN  = 60,
+	MULTI_HOUR = 3600,
+	MULTI_DAY  = 24 * 3600
+};
+
+static wire_ctx_t copy_in(
+	wire_ctx_t *in,
+	size_t in_len,
+	char *buf,
+	size_t buf_len)
+{
+	wire_ctx_t ctx = wire_ctx_init((uint8_t *)buf, buf_len);
+	wire_ctx_write(&ctx, in->position, in_len);
+	wire_ctx_skip(in, in_len);
+	// Write the terminator.
+	wire_ctx_write_u8(&ctx, '\0');
+	wire_ctx_skip(&ctx, -1);
+	return ctx;
+}
+
+_public_
+int yp_str_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	wire_ctx_write(out, in->position, YP_LEN);
+	wire_ctx_skip(in, YP_LEN);
+	// Write string terminator.
+	wire_ctx_write_u8(out, '\0');
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_str_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	size_t len = strlen((char *)in->position) + 1;
+
+	wire_ctx_write(out, in->position, len);
+	wire_ctx_skip(in, len);
+	// Set the terminator as a current position.
+	wire_ctx_skip(out, -1);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_bool_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	if (strncasecmp((char *)in->position, "on",   YP_LEN) == 0 ||
+	    strncasecmp((char *)in->position, "true", YP_LEN) == 0) {
+		wire_ctx_write_u8(out, 1);
+	} else if (strncasecmp((char *)in->position, "off",   YP_LEN) == 0 ||
+	           strncasecmp((char *)in->position, "false", YP_LEN) == 0) {
+		wire_ctx_write_u8(out, 0);
+	} else {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_skip(in, YP_LEN);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_bool_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	const char *value;
+
+	switch (wire_ctx_read_u8(in)) {
+	case 0:
+		value = "off";
+		break;
+	case 1:
+		value = "on";
+		break;
+	default:
+		return KNOT_EINVAL;
+	}
+
+	int ret = snprintf((char *)out->position, wire_ctx_available(out), "%s",
+	                   value);
+	if (ret <= 0 || ret >= wire_ctx_available(out)) {
+		return KNOT_ESPACE;
+	}
+	wire_ctx_skip(out, ret);
+
+	YP_CHECK_RET;
+}
+
+static int remove_unit(
+	int64_t *number,
+	char unit,
+	yp_style_t style)
+{
+	int64_t multiplier = 1;
+
+	// Get the multiplier for the unit.
+	if (style & YP_SSIZE) {
+		switch (unit) {
+		case UNIT_BYTE:
+			multiplier = MULTI_BYTE;
+			break;
+		case UNIT_KILO:
+			multiplier = MULTI_KILO;
+			break;
+		case UNIT_MEGA:
+			multiplier = MULTI_MEGA;
+			break;
+		case UNIT_GIGA:
+			multiplier = MULTI_GIGA;
+			break;
+		default:
+			return KNOT_EINVAL;
+		}
+	} else if (style & YP_STIME) {
+		switch (unit) {
+		case UNIT_SEC:
+			multiplier = MULTI_SEC;
+			break;
+		case UNIT_MIN:
+			multiplier = MULTI_MIN;
+			break;
+		case UNIT_HOUR:
+			multiplier = MULTI_HOUR;
+			break;
+		case UNIT_DAY:
+			multiplier = MULTI_DAY;
+			break;
+		default:
+			return KNOT_EINVAL;
+		}
+	} else {
+		return KNOT_EINVAL;
+	}
+
+	// Check for possible number overflow.
+	if (INT64_MAX / multiplier < (*number >= 0 ? *number : -*number)) {
+		return KNOT_ERANGE;
+	}
+
+	*number *= multiplier;
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_int_to_bin(
+	YP_TXT_BIN_PARAMS,
+	int64_t min,
+	int64_t max,
+	yp_style_t style)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Copy input string to the buffer to limit strtoll overread.
+	char buf[32];
+	wire_ctx_t buf_ctx = copy_in(in, YP_LEN, buf, sizeof(buf));
+	if (buf_ctx.error != KNOT_EOK) {
+		return buf_ctx.error;
+	}
+
+	// Parse the number.
+	char *end;
+	errno = 0;
+	int64_t number = strtoll(buf, &end, 10);
+
+	// Check for number overflow.
+	if (errno == ERANGE && (number == LLONG_MAX || number == LLONG_MIN)) {
+		return KNOT_ERANGE;
+	}
+	// Check if the whole string is invalid.
+	if ((errno != 0 && number == 0) || end == buf) {
+		return KNOT_EINVAL;
+	}
+	// Check the rest of the string for a unit.
+	if (*end != '\0') {
+		// Check just for one-char rest.
+		if (*(end + 1) != '\0') {
+			return KNOT_EINVAL;
+		}
+
+		// Try to apply a unit on the number.
+		int ret = remove_unit(&number, *end, style);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	}
+
+	// Check for the result number overflow.
+	if (number < min || number > max) {
+		return KNOT_ERANGE;
+	}
+
+	// Write the result.
+	wire_ctx_write_u64(out, number);
+
+	YP_CHECK_RET;
+}
+
+static void add_unit(
+	int64_t *number,
+	char *unit,
+	yp_style_t style)
+{
+	int64_t multiplier = 1;
+	char basic_unit = '\0';
+	char new_unit = '\0';
+
+	// Get the multiplier for the unit.
+	if (style & YP_SSIZE) {
+		basic_unit = UNIT_BYTE;
+
+		if (*number < MULTI_KILO) {
+			multiplier = MULTI_BYTE;
+			new_unit = UNIT_BYTE;
+		} else if (*number < MULTI_MEGA) {
+			multiplier = MULTI_KILO;
+			new_unit = UNIT_KILO;
+		} else if (*number < MULTI_GIGA) {
+			multiplier = MULTI_MEGA;
+			new_unit = UNIT_MEGA;
+		} else {
+			multiplier = MULTI_GIGA;
+			new_unit = UNIT_GIGA;
+		}
+	} else if (style & YP_STIME) {
+		basic_unit = UNIT_SEC;
+
+		if (*number < MULTI_MIN) {
+			multiplier = MULTI_SEC;
+			new_unit = UNIT_SEC;
+		} else if (*number < MULTI_HOUR) {
+			multiplier = MULTI_MIN;
+			new_unit = UNIT_MIN;
+		} else if (*number < MULTI_DAY) {
+			multiplier = MULTI_HOUR;
+			new_unit = UNIT_HOUR;
+		} else {
+			multiplier = MULTI_DAY;
+			new_unit = UNIT_DAY;
+		}
+	}
+
+	// Check for unit application without any remainder.
+	if ((*number % multiplier) == 0) {
+		*number /= multiplier;
+		*unit = new_unit;
+	} else {
+		*unit = basic_unit;
+	}
+}
+
+_public_
+int yp_int_to_txt(
+	YP_BIN_TXT_PARAMS,
+	yp_style_t style)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	char unit[2] = { '\0' };
+	int64_t number = wire_ctx_read_u64(in);
+	add_unit(&number, unit, style);
+
+	int ret = snprintf((char *)out->position, wire_ctx_available(out),
+	                   "%"PRId64"%s", number, unit);
+	if (ret <= 0 || ret >= wire_ctx_available(out)) {
+		return KNOT_ESPACE;
+	}
+	wire_ctx_skip(out, ret);
+
+	YP_CHECK_RET;
+}
+
+static uint8_t sock_type_guess(
+	const uint8_t *str,
+	size_t len)
+{
+	size_t dots = 0;
+	size_t semicolons = 0;
+	size_t digits = 0;
+
+	// Analyze the string.
+	for (size_t i = 0; i < len; i++) {
+		if (str[i] == '.') dots++;
+		else if (str[i] == ':') semicolons++;
+		else if (is_digit(str[i])) digits++;
+	}
+
+	// Guess socket type.
+	if (semicolons >= 1) {
+		return 6;
+	} else if (semicolons == 0 && dots == 3 && digits >= 3) {
+		return 4;
+	} else {
+		return 0;
+	}
+}
+
+_public_
+int yp_addr_noport_to_bin(
+	YP_TXT_BIN_PARAMS,
+	bool allow_unix)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	struct in_addr  addr4;
+	struct in6_addr addr6;
+
+	uint8_t type = sock_type_guess(in->position, YP_LEN);
+
+	// Copy address to the buffer to limit inet_pton overread.
+	char buf[INET6_ADDRSTRLEN];
+	if (type == 4 || type == 6) {
+		wire_ctx_t buf_ctx = copy_in(in, YP_LEN, buf, sizeof(buf));
+		if (buf_ctx.error != KNOT_EOK) {
+			return buf_ctx.error;
+		}
+	}
+
+	// Write address type.
+	wire_ctx_write_u8(out, type);
+
+	// Write address as such.
+	if (type == 4 && inet_pton(AF_INET, buf, &addr4) == 1) {
+		wire_ctx_write(out, (uint8_t *)&(addr4.s_addr),
+		               sizeof(addr4.s_addr));
+	} else if (type == 6 && inet_pton(AF_INET6, buf, &addr6) == 1) {
+		wire_ctx_write(out, (uint8_t *)&(addr6.s6_addr),
+	                       sizeof(addr6.s6_addr));
+	} else if (type == 0 && allow_unix) {
+		int ret = yp_str_to_bin(in, out, stop);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	} else {
+		return KNOT_EINVAL;
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_addr_noport_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	struct in_addr  addr4;
+	struct in6_addr addr6;
+
+	int ret;
+
+	switch (wire_ctx_read_u8(in)) {
+	case 0:
+		ret = yp_str_to_txt(in, out);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		break;
+	case 4:
+		wire_ctx_read(in, &(addr4.s_addr), sizeof(addr4.s_addr));
+		if (knot_inet_ntop(AF_INET, &addr4, (char *)out->position,
+		    wire_ctx_available(out)) == NULL) {
+			return KNOT_EINVAL;
+		}
+		wire_ctx_skip(out, strlen((char *)out->position));
+		break;
+	case 6:
+		wire_ctx_read(in, &(addr6.s6_addr), sizeof(addr6.s6_addr));
+		if (knot_inet_ntop(AF_INET6, &addr6, (char *)out->position,
+		    wire_ctx_available(out)) == NULL) {
+			return KNOT_EINVAL;
+		}
+		wire_ctx_skip(out, strlen((char *)out->position));
+		break;
+	default:
+		return KNOT_EINVAL;
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_addr_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Check for address@port separator.
+	const uint8_t *pos = (uint8_t *)strrchr((char *)in->position, '@');
+	// Ignore out-of-bounds result.
+	if (pos >= stop) {
+		pos = NULL;
+	}
+
+	// Store address type position.
+	uint8_t *type = out->position;
+
+	// Write the address without a port.
+	int ret = yp_addr_noport_to_bin(in, out, pos, true);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	if (pos != NULL) {
+		if (*type == 0) {
+			// Rewrite string terminator.
+			wire_ctx_skip(out, -1);
+			// Append the rest (separator and port) as a string.
+			ret = yp_str_to_bin(in, out, stop);
+		} else {
+			// Skip the separator.
+			wire_ctx_skip(in, sizeof(uint8_t));
+
+			// Write the port as a number.
+			ret = yp_int_to_bin(in, out, stop, 0, UINT16_MAX, YP_SNONE);
+		}
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+	} else if (*type == 4 || *type == 6) {
+		wire_ctx_write_u64(out, (uint64_t)-1);
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_addr_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	// Store address type position.
+	uint8_t *type = in->position;
+
+	// Write address.
+	int ret = yp_addr_noport_to_txt(in, out);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	// Write port.
+	if (*type == 4 || *type == 6) {
+		int64_t port = wire_ctx_read_u64(in);
+
+		if (port >= 0) {
+			// Write separator.
+			wire_ctx_write_u8(out, '@');
+
+			// Write port.
+			wire_ctx_skip(in, -sizeof(uint64_t));
+			ret = yp_int_to_txt(in, out, YP_SNONE);
+			if (ret != KNOT_EOK) {
+				return ret;
+			}
+		}
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_addr_range_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Format: 0 - single address, 1 - address prefix, 2 - address range.
+	uint8_t format = 0;
+
+	// Check for the "addr/mask" format.
+	const uint8_t *pos = (uint8_t *)strchr((char *)in->position, '/');
+	if (pos >= stop) {
+		pos = NULL;
+	}
+
+	if (pos != NULL) {
+		format = 1;
+	} else {
+		// Check for the "addr1-addr2" format.
+		pos = (uint8_t *)strchr((char *)in->position, '-');
+		if (pos >= stop) {
+			pos = NULL;
+		}
+		if (pos != NULL) {
+			format = 2;
+		}
+	}
+
+	// Store address1 type position.
+	uint8_t *type1 = out->position;
+
+	// Write the first address.
+	int ret = yp_addr_noport_to_bin(in, out, pos, false);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	wire_ctx_write_u8(out, format);
+
+	switch (format) {
+	case 1:
+		// Skip the separator.
+		wire_ctx_skip(in, sizeof(uint8_t));
+
+		// Write the prefix length.
+		ret = yp_int_to_bin(in, out, stop, 0, (*type1 == 4) ? 32 : 128,
+		                    YP_SNONE);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		break;
+	case 2:
+		// Skip the separator.
+		wire_ctx_skip(in, sizeof(uint8_t));
+
+		// Store address2 type position.
+		uint8_t *type2 = out->position;
+
+		// Write the second address.
+		ret = yp_addr_noport_to_bin(in, out, stop, false);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+
+		// Check for address mismatch.
+		if (*type1 != *type2) {
+			return KNOT_EINVAL;
+		}
+		break;
+	default:
+		break;
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_addr_range_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	// Write the first address.
+	int ret = yp_addr_noport_to_txt(in, out);
+	if (ret != KNOT_EOK) {
+		return ret;
+	}
+
+	uint8_t format = wire_ctx_read_u8(in);
+
+	switch (format) {
+	case 1:
+		// Write the separator.
+		wire_ctx_write_u8(out, '/');
+
+		// Write the prefix length.
+		ret = yp_int_to_txt(in, out, YP_SNONE);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		break;
+	case 2:
+		// Write the separator.
+		wire_ctx_write_u8(out, '-');
+
+		// Write the second address.
+		ret = yp_addr_noport_to_txt(in, out);
+		if (ret != KNOT_EOK) {
+			return ret;
+		}
+		break;
+	default:
+		break;
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_option_to_bin(
+	YP_TXT_BIN_PARAMS,
+	const knot_lookup_t *opts)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	while (opts->name != NULL) {
+		if (YP_LEN == strlen(opts->name) &&
+		    strncasecmp((char *)in->position, opts->name, YP_LEN) == 0) {
+			wire_ctx_write_u8(out, opts->id);
+			wire_ctx_skip(in, YP_LEN);
+			YP_CHECK_RET;
+		}
+		opts++;
+	}
+
+	return KNOT_EINVAL;
+}
+
+_public_
+int yp_option_to_txt(
+	YP_BIN_TXT_PARAMS,
+	const knot_lookup_t *opts)
+{
+	uint8_t id = wire_ctx_read_u8(in);
+
+	while (opts->name != NULL) {
+		if (id == opts->id) {
+			int ret = snprintf((char *)out->position,
+			                   wire_ctx_available(out), "%s",
+			                   opts->name);
+			if (ret <= 0 || ret >= wire_ctx_available(out)) {
+				return KNOT_ESPACE;
+			}
+			wire_ctx_skip(out, ret);
+			YP_CHECK_RET;
+		}
+		opts++;
+	}
+
+	return KNOT_EINVAL;
+}
+
+_public_
+int yp_dname_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Copy dname string to the buffer to limit dname_from_str overread.
+	knot_dname_txt_storage_t buf;
+	wire_ctx_t buf_ctx = copy_in(in, YP_LEN, buf, sizeof(buf));
+	if (buf_ctx.error != KNOT_EOK) {
+		return buf_ctx.error;
+	}
+
+	// Convert the dname.
+	if (knot_dname_from_str(out->position, buf, wire_ctx_available(out)) == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	// Check the result and count the length.
+	int ret = knot_dname_wire_check(out->position,
+	                                out->position + wire_ctx_available(out),
+	                                NULL);
+	if (ret <= 0) {
+		return KNOT_EINVAL;
+	}
+
+	// Convert the result to lower case.
+	knot_dname_to_lower(out->position);
+
+	wire_ctx_skip(out, ret);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_dname_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	if (knot_dname_to_str((char *)out->position, in->position,
+	                      wire_ctx_available(out)) == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_skip(out, strlen((char *)out->position));
+
+	YP_CHECK_RET;
+}
+
+static int hex_to_num(char hex) {
+	if (hex >= '0' && hex <= '9') return hex - '0';
+	if (hex >= 'a' && hex <= 'f') return hex - 'a' + 10;
+	if (hex >= 'A' && hex <= 'F') return hex - 'A' + 10;
+	return -1;
+}
+
+_public_
+int yp_hex_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Check for hex notation (leading "0x").
+	if (wire_ctx_available(in) >= 2 &&
+	    in->position[0] == '0' && in->position[1] == 'x') {
+		wire_ctx_skip(in, 2);
+
+		if (YP_LEN % 2 != 0) {
+			return KNOT_EINVAL;
+		}
+
+		// Write data length.
+		wire_ctx_write_u16(out, YP_LEN / 2);
+
+		// Decode hex string.
+		while (YP_LEN > 0) {
+			uint8_t buf[2] = { 0 };
+			wire_ctx_read(in, buf, sizeof(buf));
+
+			if (!is_xdigit(buf[0]) ||
+			    !is_xdigit(buf[1])) {
+				return KNOT_EINVAL;
+			}
+
+			wire_ctx_write_u8(out, 16 * hex_to_num(buf[0]) +
+			                            hex_to_num(buf[1]));
+		}
+	} else {
+		// Write data length.
+		wire_ctx_write_u16(out, YP_LEN);
+
+		// Write textual string (without terminator).
+		wire_ctx_write(out, in->position, YP_LEN);
+		wire_ctx_skip(in, YP_LEN);
+	}
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_hex_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	size_t len = wire_ctx_read_u16(in);
+
+	bool printable = true;
+
+	// Check for printable string.
+	for (size_t i = 0; i < len; i++) {
+		if (!is_print(in->position[i])) {
+			printable = false;
+			break;
+		}
+	}
+
+	if (printable) {
+		wire_ctx_write(out, in->position, len);
+		wire_ctx_skip(in, len);
+	} else {
+		const char *prefix = "0x";
+		const char *hex = "0123456789ABCDEF";
+
+		// Write hex prefix.
+		wire_ctx_write(out, (uint8_t *)prefix, strlen(prefix));
+
+		// Encode data to hex.
+		for (size_t i = 0; i < len; i++) {
+			uint8_t bin = wire_ctx_read_u8(in);
+			wire_ctx_write_u8(out, hex[bin / 16]);
+			wire_ctx_write_u8(out, hex[bin % 16]);
+		}
+	}
+
+	// Write the terminator.
+	wire_ctx_write_u8(out, '\0');
+	wire_ctx_skip(out, -1);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_base64_to_bin(
+	YP_TXT_BIN_PARAMS)
+{
+	YP_CHECK_PARAMS_BIN;
+
+	// Reserve some space for data length.
+	wire_ctx_skip(out, sizeof(uint16_t));
+
+	int ret = knot_base64_decode(in->position, YP_LEN, out->position,
+	                        wire_ctx_available(out));
+	if (ret < 0) {
+		return ret;
+	}
+	wire_ctx_skip(in, YP_LEN);
+
+	// Write the data length.
+	wire_ctx_skip(out, -sizeof(uint16_t));
+	wire_ctx_write_u16(out, ret);
+	wire_ctx_skip(out, ret);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_base64_to_txt(
+	YP_BIN_TXT_PARAMS)
+{
+	YP_CHECK_PARAMS_TXT;
+
+	// Read the data length.
+	uint16_t len = wire_ctx_read_u16(in);
+
+	int ret = knot_base64_encode(in->position, len, out->position,
+	                        wire_ctx_available(out));
+	if (ret < 0) {
+		return ret;
+	}
+	wire_ctx_skip(out, ret);
+
+	// Write the terminator.
+	wire_ctx_write_u8(out, '\0');
+	wire_ctx_skip(out, -1);
+
+	YP_CHECK_RET;
+}
+
+_public_
+int yp_item_to_bin(
+	const yp_item_t *item,
+	const char *txt,
+	size_t txt_len,
+	uint8_t *bin,
+	size_t *bin_len)
+{
+	if (item == NULL || txt == NULL || bin == NULL || bin_len == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t in = wire_ctx_init_const((const uint8_t *)txt, txt_len);
+	wire_ctx_t out = wire_ctx_init(bin, *bin_len);
+
+	int ret;
+	size_t ref_len;
+
+	switch (item->type) {
+	case YP_TINT:
+		ret = yp_int_to_bin(&in, &out, NULL, item->var.i.min,
+		                    item->var.i.max, item->var.i.unit);
+		break;
+	case YP_TBOOL:
+		ret = yp_bool_to_bin(&in, &out, NULL);
+		break;
+	case YP_TOPT:
+		ret = yp_option_to_bin(&in, &out, NULL, item->var.o.opts);
+		break;
+	case YP_TSTR:
+		ret = yp_str_to_bin(&in, &out, NULL);
+		break;
+	case YP_TADDR:
+		ret = yp_addr_to_bin(&in, &out, NULL);
+		break;
+	case YP_TNET:
+		ret = yp_addr_range_to_bin(&in, &out, NULL);
+		break;
+	case YP_TDNAME:
+		ret = yp_dname_to_bin(&in, &out, NULL);
+		break;
+	case YP_THEX:
+		ret = yp_hex_to_bin(&in, &out, NULL);
+		break;
+	case YP_TB64:
+		ret = yp_base64_to_bin(&in, &out, NULL);
+		break;
+	case YP_TDATA:
+		ret = item->var.d.to_bin(&in, &out, NULL);
+		break;
+	case YP_TREF:
+		ref_len = wire_ctx_available(&out);
+		ret = yp_item_to_bin(item->var.r.ref->var.g.id,
+		                     (char *)in.position, wire_ctx_available(&in),
+		                     out.position, &ref_len);
+		wire_ctx_skip(&out, ref_len);
+		break;
+	default:
+		ret = KNOT_EOK;
+	}
+
+	if (ret != KNOT_EOK) {
+		return ret;
+	} else if (in.error != KNOT_EOK) {
+		return in.error;
+	} else if (out.error != KNOT_EOK) {
+		return out.error;
+	}
+
+	*bin_len = wire_ctx_offset(&out);
+
+	return KNOT_EOK;
+}
+
+_public_
+int yp_item_to_txt(
+	const yp_item_t *item,
+	const uint8_t *bin,
+	size_t bin_len,
+	char *txt,
+	size_t *txt_len,
+	yp_style_t style)
+{
+	if (item == NULL || bin == NULL || txt == NULL || txt_len == NULL) {
+		return KNOT_EINVAL;
+	}
+
+	wire_ctx_t in = wire_ctx_init_const(bin, bin_len);
+	wire_ctx_t out = wire_ctx_init((uint8_t *)txt, *txt_len);
+
+	// Write leading quote.
+	if (!(style & YP_SNOQUOTE)) {
+		wire_ctx_write_u8(&out, '"');
+	}
+
+	int ret;
+	size_t ref_len;
+
+	switch (item->type) {
+	case YP_TINT:
+		ret = yp_int_to_txt(&in, &out, item->var.i.unit & style);
+		break;
+	case YP_TBOOL:
+		ret = yp_bool_to_txt(&in, &out);
+		break;
+	case YP_TOPT:
+		ret = yp_option_to_txt(&in, &out, item->var.o.opts);
+		break;
+	case YP_TSTR:
+		ret = yp_str_to_txt(&in, &out);
+		break;
+	case YP_TADDR:
+		ret = yp_addr_to_txt(&in, &out);
+		break;
+	case YP_TNET:
+		ret = yp_addr_range_to_txt(&in, &out);
+		break;
+	case YP_TDNAME:
+		ret = yp_dname_to_txt(&in, &out);
+		break;
+	case YP_THEX:
+		ret = yp_hex_to_txt(&in, &out);
+		break;
+	case YP_TB64:
+		ret = yp_base64_to_txt(&in, &out);
+		break;
+	case YP_TDATA:
+		ret = item->var.d.to_txt(&in, &out);
+		break;
+	case YP_TREF:
+		ref_len = wire_ctx_available(&out);
+		ret = yp_item_to_txt(item->var.r.ref->var.g.id,
+		                     in.position, wire_ctx_available(&in),
+		                     (char *)out.position,
+		                     &ref_len, style | YP_SNOQUOTE);
+		wire_ctx_skip(&out, ref_len);
+		break;
+	default:
+		ret = KNOT_EOK;
+	}
+
+	// Write trailing quote.
+	if (!(style & YP_SNOQUOTE)) {
+		wire_ctx_write_u8(&out, '"');
+	}
+
+	// Write string terminator.
+	wire_ctx_write_u8(&out, '\0');
+	wire_ctx_skip(&out, -1);
+
+	if (ret != KNOT_EOK) {
+		return ret;
+	} else if (in.error != KNOT_EOK) {
+		return in.error;
+	} else if (out.error != KNOT_EOK) {
+		return out.error;
+	}
+
+	*txt_len = wire_ctx_offset(&out);
+
+	return KNOT_EOK;
+}
+
+_public_
+struct sockaddr_storage yp_addr_noport(
+	const uint8_t *data)
+{
+	struct sockaddr_storage ss = { AF_UNSPEC };
+
+	// Read address type.
+	uint8_t type = *data;
+	data += sizeof(type);
+
+	// Set address.
+	switch (type) {
+	case 0:
+		sockaddr_set(&ss, AF_UNIX, (char *)data, 0);
+		break;
+	case 4:
+		sockaddr_set_raw(&ss, AF_INET, data,
+		                 sizeof(((struct in_addr *)NULL)->s_addr));
+		break;
+	case 6:
+		sockaddr_set_raw(&ss, AF_INET6, data,
+		                 sizeof(((struct in6_addr *)NULL)->s6_addr));
+		break;
+	}
+
+	return ss;
+}
+
+_public_
+struct sockaddr_storage yp_addr(
+	const uint8_t *data,
+	bool *no_port)
+{
+	struct sockaddr_storage ss = yp_addr_noport(data);
+
+	size_t addr_len;
+
+	// Get binary address length.
+	switch (ss.ss_family) {
+	case AF_INET:
+		addr_len = sizeof(((struct in_addr *)NULL)->s_addr);
+		break;
+	case AF_INET6:
+		addr_len = sizeof(((struct in6_addr *)NULL)->s6_addr);
+		break;
+	default:
+		addr_len = 0;
+		*no_port = true;
+	}
+
+	if (addr_len > 0) {
+		int64_t port = knot_wire_read_u64(data + sizeof(uint8_t) + addr_len);
+		if (port >= 0) {
+			sockaddr_port_set(&ss, port);
+			*no_port = false;
+		} else {
+			*no_port = true;
+		}
+	}
+
+	return ss;
+}
diff --git a/src/libknot/yparser/yptrafo.h b/src/libknot/yparser/yptrafo.h
new file mode 100644
index 0000000..285ab98
--- /dev/null
+++ b/src/libknot/yparser/yptrafo.h
@@ -0,0 +1,311 @@
+/*  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/>.
+ */
+
+/*!
+ * \file
+ *
+ * \brief Value transformations for Yparser.
+ *
+ * \addtogroup yparser
+ * @{
+ */
+
+#pragma once
+
+#include "libknot/yparser/ypschema.h"
+#include "libknot/lookup.h"
+#include "libknot/wire.h"
+
+/*!
+ * Transforms textual item value to binary form.
+ *
+ * \param[in] item Schema item to transform.
+ * \param[in] txt Value to transform.
+ * \param[in] txt_len Value length.
+ * \param[out] bin Output buffer.
+ * \param[in, out] bin_len Output buffer length, output length.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_item_to_bin(
+	const yp_item_t *item,
+	const char *txt,
+	size_t txt_len,
+	uint8_t *bin,
+	size_t *bin_len
+);
+
+/*!
+ * Transforms binary item value to textual form.
+ *
+ * \param[in] item Schema item to transform.
+ * \param[in] bin Value to transform.
+ * \param[in] bin_len Value length.
+ * \param[out] txt Output buffer.
+ * \param[in, out] txt_len Output buffer length, output length.
+ * \param[in] style Value style.
+ *
+ * \return Error code, KNOT_EOK if success.
+ */
+int yp_item_to_txt(
+	const yp_item_t *item,
+	const uint8_t *bin,
+	size_t bin_len,
+	char *txt,
+	size_t *txt_len,
+	yp_style_t style
+);
+
+/*!
+ * Converts binary value to string pointer.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return String pointer.
+ */
+inline static const char* yp_str(
+	const uint8_t *data)
+{
+	return (const char *)data;
+}
+
+/*!
+ * Converts binary value to boolean value.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Boolean value.
+ */
+inline static bool yp_bool(
+	const uint8_t *data)
+{
+	return (data[0] == 0) ? false : true;
+}
+
+/*!
+ * Converts binary value to integer value.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Integer value.
+ */
+inline static int64_t yp_int(
+	const uint8_t *data)
+{
+	return (int64_t)knot_wire_read_u64(data);
+}
+
+/*!
+ * Converts binary value to address value.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Address value.
+ */
+struct sockaddr_storage yp_addr_noport(
+	const uint8_t *data
+);
+
+/*!
+ * Converts binary value to address value with an optional port.
+ *
+ * \param[in] data Binary value to transform.
+ * \param[out] no_port No port indicator.
+ *
+ * \return Address value.
+ */
+struct sockaddr_storage yp_addr(
+	const uint8_t *data,
+	bool *no_port
+);
+
+/*!
+ * Converts binary value to option value.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Unsigned value.
+ */
+inline static unsigned yp_opt(
+	const uint8_t *data)
+{
+	return (unsigned)data[0];
+}
+
+/*!
+ * Converts binary value to dname pointer.
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Dname pointer.
+ */
+inline static const uint8_t* yp_dname(
+	const uint8_t *data)
+{
+	return data;
+}
+
+/*!
+ * Converts binary value to data pointer.
+ *
+ * Applies to all data types with 2-byte length prefix (YP_THEX, YP_TB64).
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Data pointer.
+ */
+inline static const uint8_t* yp_bin(
+	const uint8_t *data)
+{
+	return data + 2;
+}
+
+/*!
+ * Gets binary value length.
+ *
+ * Applies to all data types with 2-byte length prefix (YP_THEX, YP_TB64).
+ *
+ * \param[in] data Binary value to transform.
+ *
+ * \return Data length.
+ */
+inline static size_t yp_bin_len(
+	const uint8_t *data)
+{
+	return knot_wire_read_u16(data);
+}
+
+/*!
+ * \brief Helper macros for conversion functions.
+ */
+
+#define YP_CHECK_CTX \
+	if (in->error != KNOT_EOK) { \
+		return in->error; \
+	} else if (out->error != KNOT_EOK) { \
+		return out->error; \
+	} \
+
+#define YP_CHECK_STOP \
+	if (stop != NULL) { \
+		assert(stop <= in->position + wire_ctx_available(in)); \
+	} else { \
+		stop = in->position + wire_ctx_available(in); \
+	}
+
+#define YP_LEN (stop - in->position)
+
+#define YP_CHECK_PARAMS_BIN \
+	YP_CHECK_CTX YP_CHECK_STOP
+
+#define YP_CHECK_PARAMS_TXT \
+	YP_CHECK_CTX
+
+#define YP_CHECK_RET \
+	YP_CHECK_CTX return KNOT_EOK;
+
+/*!
+ * \brief Conversion functions for basic types.
+ */
+
+int yp_str_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_str_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_bool_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_bool_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_int_to_bin(
+	YP_TXT_BIN_PARAMS,
+	int64_t min,
+	int64_t max,
+	yp_style_t style
+);
+
+int yp_int_to_txt(
+	YP_BIN_TXT_PARAMS,
+	yp_style_t style
+);
+
+int yp_addr_noport_to_bin(
+	YP_TXT_BIN_PARAMS,
+	bool allow_unix
+);
+
+int yp_addr_noport_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_addr_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_addr_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_addr_range_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_addr_range_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_option_to_bin(
+	YP_TXT_BIN_PARAMS,
+	const struct knot_lookup *opts
+);
+
+int yp_option_to_txt(
+	YP_BIN_TXT_PARAMS,
+	const struct knot_lookup *opts
+);
+
+int yp_dname_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_dname_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_hex_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_hex_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+int yp_base64_to_bin(
+	YP_TXT_BIN_PARAMS
+);
+
+int yp_base64_to_txt(
+	YP_BIN_TXT_PARAMS
+);
+
+/*! @} */