1 files changed, 825 insertions, 0 deletions

diff --git a/src/libknot/packet/pkt.c b/src/libknot/packet/pkt.c
new file mode 100644
index 0000000..ddda72e
--- /dev/null
+++ b/src/libknot/packet/pkt.c
@@ -0,0 +1,825 @@
+/*  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 the old data. */
+	memcpy(rr_info, pkt->rr_info, pkt->rrset_allocd * sizeof(knot_rrinfo_t));
+	memcpy(rr, pkt->rr, pkt->rrset_allocd * sizeof(knot_rrset_t));
+
+	/* Reassign and free old data. */
+	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, sizeof(knot_pkt_t));
+
+	/* 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);
+
+	pkt->qname_size = query->qname_size;
+	if (query->qname_size == 0) {
+		/* Reset question count if malformed. */
+		knot_wire_set_qdcount(pkt->wire, 0);
+	}
+
+	/* 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);
+}
+
+_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 wireformat. */
+	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 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;
+
+	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 : "";
+}