1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2014 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
25 #include "resolved-dns-domain.h"
26 #include "resolved-dns-packet.h"
28 int dns_packet_new(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
35 a = DNS_PACKET_SIZE_START;
39 if (a < DNS_PACKET_HEADER_SIZE)
40 a = DNS_PACKET_HEADER_SIZE;
42 /* round up to next page size */
43 a = PAGE_ALIGN(ALIGN(sizeof(DnsPacket)) + a) - ALIGN(sizeof(DnsPacket));
45 /* make sure we never allocate more than useful */
46 if (a > DNS_PACKET_SIZE_MAX)
47 a = DNS_PACKET_SIZE_MAX;
49 p = malloc0(ALIGN(sizeof(DnsPacket)) + a);
53 p->size = p->rindex = DNS_PACKET_HEADER_SIZE;
55 p->protocol = protocol;
63 int dns_packet_new_query(DnsPacket **ret, DnsProtocol protocol, size_t mtu) {
70 r = dns_packet_new(&p, protocol, mtu);
74 h = DNS_PACKET_HEADER(p);
76 if (protocol == DNS_PROTOCOL_LLMNR)
77 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
87 h->flags = htobe16(DNS_PACKET_MAKE_FLAGS(0 /* qr */,
91 1 /* rd (ask for recursion) */,
101 DnsPacket *dns_packet_ref(DnsPacket *p) {
106 assert(p->n_ref > 0);
111 static void dns_packet_free(DnsPacket *p) {
116 dns_question_unref(p->question);
117 dns_answer_unref(p->answer);
119 while ((s = hashmap_steal_first_key(p->names)))
121 hashmap_free(p->names);
127 DnsPacket *dns_packet_unref(DnsPacket *p) {
131 assert(p->n_ref > 0);
141 int dns_packet_validate(DnsPacket *p) {
144 if (p->size < DNS_PACKET_HEADER_SIZE)
147 if (p->size > DNS_PACKET_SIZE_MAX)
153 int dns_packet_validate_reply(DnsPacket *p) {
158 r = dns_packet_validate(p);
162 if (DNS_PACKET_QR(p) != 1)
165 if (DNS_PACKET_OPCODE(p) != 0)
168 /* RFC 4795, Section 2.1.1. says to discard all replies with QDCOUNT != 1 */
169 if (p->protocol == DNS_PROTOCOL_LLMNR &&
170 DNS_PACKET_QDCOUNT(p) != 1)
176 int dns_packet_validate_query(DnsPacket *p) {
181 r = dns_packet_validate(p);
185 if (DNS_PACKET_QR(p) != 0)
188 if (DNS_PACKET_OPCODE(p) != 0)
191 if (DNS_PACKET_TC(p))
194 /* RFC 4795, Section 2.1.1. says to discard all queries with QDCOUNT != 1 */
195 if (p->protocol == DNS_PROTOCOL_LLMNR &&
196 DNS_PACKET_QDCOUNT(p) != 1)
199 /* RFC 4795, Section 2.1.1. says to discard all queries with ANCOUNT != 0 */
200 if (DNS_PACKET_ANCOUNT(p) > 0)
203 /* RFC 4795, Section 2.1.1. says to discard all queries with NSCOUNT != 0 */
204 if (DNS_PACKET_NSCOUNT(p) > 0)
210 static int dns_packet_extend(DnsPacket *p, size_t add, void **ret, size_t *start) {
213 if (p->size + add > p->allocated) {
216 a = PAGE_ALIGN((p->size + add) * 2);
217 if (a > DNS_PACKET_SIZE_MAX)
218 a = DNS_PACKET_SIZE_MAX;
220 if (p->size + add > a)
226 d = realloc(p->_data, a);
232 p->_data = malloc(a);
236 memcpy(p->_data, (uint8_t*) p + ALIGN(sizeof(DnsPacket)), p->size);
237 memzero((uint8_t*) p->_data + p->size, a - p->size);
247 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->size;
253 static void dns_packet_truncate(DnsPacket *p, size_t sz) {
263 HASHMAP_FOREACH_KEY(s, n, p->names, i) {
265 if (PTR_TO_SIZE(n) < sz)
268 hashmap_remove(p->names, s);
275 int dns_packet_append_blob(DnsPacket *p, const void *d, size_t l, size_t *start) {
281 r = dns_packet_extend(p, l, &q, start);
289 int dns_packet_append_uint8(DnsPacket *p, uint8_t v, size_t *start) {
295 r = dns_packet_extend(p, sizeof(uint8_t), &d, start);
299 ((uint8_t*) d)[0] = v;
304 int dns_packet_append_uint16(DnsPacket *p, uint16_t v, size_t *start) {
310 r = dns_packet_extend(p, sizeof(uint16_t), &d, start);
314 ((uint8_t*) d)[0] = (uint8_t) (v >> 8);
315 ((uint8_t*) d)[1] = (uint8_t) v;
320 int dns_packet_append_uint32(DnsPacket *p, uint32_t v, size_t *start) {
326 r = dns_packet_extend(p, sizeof(uint32_t), &d, start);
330 ((uint8_t*) d)[0] = (uint8_t) (v >> 24);
331 ((uint8_t*) d)[1] = (uint8_t) (v >> 16);
332 ((uint8_t*) d)[2] = (uint8_t) (v >> 8);
333 ((uint8_t*) d)[3] = (uint8_t) v;
338 int dns_packet_append_string(DnsPacket *p, const char *s, size_t *start) {
350 r = dns_packet_extend(p, 1 + l, &d, start);
354 ((uint8_t*) d)[0] = (uint8_t) l;
355 memcpy(((uint8_t*) d) + 1, s, l);
360 int dns_packet_append_label(DnsPacket *p, const char *d, size_t l, size_t *start) {
367 if (l > DNS_LABEL_MAX)
370 r = dns_packet_extend(p, 1 + l, &w, start);
374 ((uint8_t*) w)[0] = (uint8_t) l;
375 memcpy(((uint8_t*) w) + 1, d, l);
380 int dns_packet_append_name(DnsPacket *p, const char *name, size_t *start) {
387 saved_size = p->size;
390 _cleanup_free_ char *s = NULL;
391 char label[DNS_LABEL_MAX];
394 n = PTR_TO_SIZE(hashmap_get(p->names, name));
399 r = dns_packet_append_uint16(p, 0xC000 | n, NULL);
413 r = dns_label_unescape(&name, label, sizeof(label));
417 r = dns_packet_append_label(p, label, r, &n);
421 r = hashmap_ensure_allocated(&p->names, dns_name_hash_func, dns_name_compare_func);
425 r = hashmap_put(p->names, s, SIZE_TO_PTR(n));
432 r = dns_packet_append_uint8(p, 0, NULL);
443 dns_packet_truncate(p, saved_size);
447 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start) {
454 saved_size = p->size;
456 r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), NULL);
460 r = dns_packet_append_uint16(p, k->type, NULL);
464 r = dns_packet_append_uint16(p, k->class, NULL);
474 dns_packet_truncate(p, saved_size);
478 int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
479 size_t saved_size, rdlength_offset, end, rdlength;
485 saved_size = p->size;
487 r = dns_packet_append_key(p, rr->key, NULL);
491 r = dns_packet_append_uint32(p, rr->ttl, NULL);
495 /* Initially we write 0 here */
496 r = dns_packet_append_uint16(p, 0, &rdlength_offset);
500 switch (rr->key->type) {
505 r = dns_packet_append_name(p, rr->ptr.name, NULL);
509 r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
513 r = dns_packet_append_string(p, rr->hinfo.os, NULL);
516 case DNS_TYPE_SPF: /* exactly the same as TXT */
520 STRV_FOREACH(s, rr->txt.strings) {
521 r = dns_packet_append_string(p, *s, NULL);
530 r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
534 r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
538 r = dns_packet_append_name(p, rr->soa.mname, NULL);
542 r = dns_packet_append_name(p, rr->soa.rname, NULL);
546 r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
550 r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
554 r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
558 r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
562 r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
566 r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
570 r = dns_packet_append_name(p, rr->mx.exchange, NULL);
577 r = dns_packet_append_blob(p, rr->generic.data, rr->generic.size, NULL);
583 /* Let's calculate the actual data size and update the field */
584 rdlength = p->size - rdlength_offset - sizeof(uint16_t);
585 if (rdlength > 0xFFFF) {
591 p->size = rdlength_offset;
592 r = dns_packet_append_uint16(p, rdlength, NULL);
603 dns_packet_truncate(p, saved_size);
608 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
611 if (p->rindex + sz > p->size)
615 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
624 void dns_packet_rewind(DnsPacket *p, size_t idx) {
626 assert(idx <= p->size);
627 assert(idx >= DNS_PACKET_HEADER_SIZE);
632 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
639 r = dns_packet_read(p, sz, &q, start);
647 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
653 r = dns_packet_read(p, sizeof(uint8_t), &d, start);
657 *ret = ((uint8_t*) d)[0];
661 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
667 r = dns_packet_read(p, sizeof(uint16_t), &d, start);
671 *ret = (((uint16_t) ((uint8_t*) d)[0]) << 8) |
672 ((uint16_t) ((uint8_t*) d)[1]);
676 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
682 r = dns_packet_read(p, sizeof(uint32_t), &d, start);
686 *ret = (((uint32_t) ((uint8_t*) d)[0]) << 24) |
687 (((uint32_t) ((uint8_t*) d)[1]) << 16) |
688 (((uint32_t) ((uint8_t*) d)[2]) << 8) |
689 ((uint32_t) ((uint8_t*) d)[3]);
694 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
703 saved_rindex = p->rindex;
705 r = dns_packet_read_uint8(p, &c, NULL);
709 r = dns_packet_read(p, c, &d, NULL);
713 if (memchr(d, 0, c)) {
724 if (!utf8_is_valid(t)) {
733 *start = saved_rindex;
738 dns_packet_rewind(p, saved_rindex);
742 int dns_packet_read_name(DnsPacket *p, char **_ret, size_t *start) {
743 size_t saved_rindex, after_rindex = 0;
744 _cleanup_free_ char *ret = NULL;
745 size_t n = 0, allocated = 0;
752 saved_rindex = p->rindex;
757 r = dns_packet_read_uint8(p, &c, NULL);
765 _cleanup_free_ char *t = NULL;
769 r = dns_packet_read(p, c, (const void**) &label, NULL);
773 r = dns_label_escape(label, c, &t);
777 if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) {
787 memcpy(ret + n, t, c);
790 } else if ((c & 0xc0) == 0xc0) {
794 r = dns_packet_read_uint8(p, &d, NULL);
798 ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
799 if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= saved_rindex) {
804 if (after_rindex == 0)
805 after_rindex = p->rindex;
812 if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
819 if (after_rindex != 0)
820 p->rindex= after_rindex;
826 *start = saved_rindex;
831 dns_packet_rewind(p, saved_rindex);
835 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
836 _cleanup_free_ char *name = NULL;
837 uint16_t class, type;
845 saved_rindex = p->rindex;
847 r = dns_packet_read_name(p, &name, NULL);
851 r = dns_packet_read_uint16(p, &type, NULL);
855 r = dns_packet_read_uint16(p, &class, NULL);
859 key = dns_resource_key_new_consume(class, type, name);
869 *start = saved_rindex;
873 dns_packet_rewind(p, saved_rindex);
877 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
878 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
879 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
880 size_t saved_rindex, offset;
888 saved_rindex = p->rindex;
890 r = dns_packet_read_key(p, &key, NULL);
894 if (key->class == DNS_CLASS_ANY ||
895 key->type == DNS_TYPE_ANY) {
900 rr = dns_resource_record_new(key);
906 r = dns_packet_read_uint32(p, &rr->ttl, NULL);
910 r = dns_packet_read_uint16(p, &rdlength, NULL);
914 if (p->rindex + rdlength > p->size) {
921 switch (rr->key->type) {
926 r = dns_packet_read_name(p, &rr->ptr.name, NULL);
930 r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
934 r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
937 case DNS_TYPE_SPF: /* exactly the same as TXT */
941 while (p->rindex < p->size) {
942 r = dns_packet_read_string(p, &s, NULL);
946 r = strv_consume(&rr->txt.strings, s);
954 r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
958 r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
962 r = dns_packet_read_name(p, &rr->soa.mname, NULL);
966 r = dns_packet_read_name(p, &rr->soa.rname, NULL);
970 r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
974 r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
978 r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
982 r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
986 r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
990 r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
994 r = dns_packet_read_name(p, &rr->mx.exchange, NULL);
1001 r = dns_packet_read(p, rdlength, &d, NULL);
1005 rr->generic.data = memdup(d, rdlength);
1006 if (!rr->generic.data) {
1011 rr->generic.size = rdlength;
1016 if (p->rindex != offset + rdlength) {
1025 *start = saved_rindex;
1029 dns_packet_rewind(p, saved_rindex);
1033 int dns_packet_extract(DnsPacket *p) {
1034 _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
1035 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1036 size_t saved_rindex;
1040 saved_rindex = p->rindex;
1041 dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
1043 n = DNS_PACKET_QDCOUNT(p);
1045 question = dns_question_new(n);
1051 for (i = 0; i < n; i++) {
1052 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1054 r = dns_packet_read_key(p, &key, NULL);
1058 r = dns_question_add(question, key);
1064 n = DNS_PACKET_RRCOUNT(p);
1066 answer = dns_answer_new(n);
1072 for (i = 0; i < n; i++) {
1073 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1075 r = dns_packet_read_rr(p, &rr, NULL);
1079 r = dns_answer_add(answer, rr);
1085 p->question = question;
1094 p->rindex = saved_rindex;
1098 static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
1099 [DNS_RCODE_SUCCESS] = "SUCCESS",
1100 [DNS_RCODE_FORMERR] = "FORMERR",
1101 [DNS_RCODE_SERVFAIL] = "SERVFAIL",
1102 [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
1103 [DNS_RCODE_NOTIMP] = "NOTIMP",
1104 [DNS_RCODE_REFUSED] = "REFUSED",
1105 [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
1106 [DNS_RCODE_YXRRSET] = "YRRSET",
1107 [DNS_RCODE_NXRRSET] = "NXRRSET",
1108 [DNS_RCODE_NOTAUTH] = "NOTAUTH",
1109 [DNS_RCODE_NOTZONE] = "NOTZONE",
1110 [DNS_RCODE_BADVERS] = "BADVERS",
1111 [DNS_RCODE_BADKEY] = "BADKEY",
1112 [DNS_RCODE_BADTIME] = "BADTIME",
1113 [DNS_RCODE_BADMODE] = "BADMODE",
1114 [DNS_RCODE_BADNAME] = "BADNAME",
1115 [DNS_RCODE_BADALG] = "BADALG",
1116 [DNS_RCODE_BADTRUNC] = "BADTRUNC",
1118 DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
1120 static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
1121 [DNS_PROTOCOL_DNS] = "dns",
1122 [DNS_PROTOCOL_MDNS] = "mdns",
1123 [DNS_PROTOCOL_LLMNR] = "llmnr",
1125 DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);