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->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
503 r = dns_packet_append_uint16(p, rr->srv.priority, NULL);
507 r = dns_packet_append_uint16(p, rr->srv.weight, NULL);
511 r = dns_packet_append_uint16(p, rr->srv.port, NULL);
515 r = dns_packet_append_name(p, rr->srv.name, NULL);
522 r = dns_packet_append_name(p, rr->ptr.name, NULL);
526 r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
530 r = dns_packet_append_string(p, rr->hinfo.os, NULL);
533 case DNS_TYPE_SPF: /* exactly the same as TXT */
537 STRV_FOREACH(s, rr->txt.strings) {
538 r = dns_packet_append_string(p, *s, NULL);
548 r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
552 r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
556 r = dns_packet_append_name(p, rr->soa.mname, NULL);
560 r = dns_packet_append_name(p, rr->soa.rname, NULL);
564 r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
568 r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
572 r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
576 r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
580 r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
584 r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
588 r = dns_packet_append_name(p, rr->mx.exchange, NULL);
592 r = dns_packet_append_uint8(p, rr->loc.version, NULL);
596 r = dns_packet_append_uint8(p, rr->loc.size, NULL);
600 r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL);
604 r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL);
608 r = dns_packet_append_uint16(p, rr->loc.latitude, NULL);
612 r = dns_packet_append_uint16(p, rr->loc.longitude, NULL);
616 r = dns_packet_append_uint16(p, rr->loc.altitude, NULL);
620 case _DNS_TYPE_INVALID: /* unparseable */
623 r = dns_packet_append_blob(p, rr->generic.data, rr->generic.size, NULL);
629 /* Let's calculate the actual data size and update the field */
630 rdlength = p->size - rdlength_offset - sizeof(uint16_t);
631 if (rdlength > 0xFFFF) {
637 p->size = rdlength_offset;
638 r = dns_packet_append_uint16(p, rdlength, NULL);
649 dns_packet_truncate(p, saved_size);
654 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
657 if (p->rindex + sz > p->size)
661 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
670 void dns_packet_rewind(DnsPacket *p, size_t idx) {
672 assert(idx <= p->size);
673 assert(idx >= DNS_PACKET_HEADER_SIZE);
678 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
685 r = dns_packet_read(p, sz, &q, start);
693 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
699 r = dns_packet_read(p, sizeof(uint8_t), &d, start);
703 *ret = ((uint8_t*) d)[0];
707 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
713 r = dns_packet_read(p, sizeof(uint16_t), &d, start);
717 *ret = (((uint16_t) ((uint8_t*) d)[0]) << 8) |
718 ((uint16_t) ((uint8_t*) d)[1]);
722 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
728 r = dns_packet_read(p, sizeof(uint32_t), &d, start);
732 *ret = (((uint32_t) ((uint8_t*) d)[0]) << 24) |
733 (((uint32_t) ((uint8_t*) d)[1]) << 16) |
734 (((uint32_t) ((uint8_t*) d)[2]) << 8) |
735 ((uint32_t) ((uint8_t*) d)[3]);
740 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
749 saved_rindex = p->rindex;
751 r = dns_packet_read_uint8(p, &c, NULL);
755 r = dns_packet_read(p, c, &d, NULL);
759 if (memchr(d, 0, c)) {
770 if (!utf8_is_valid(t)) {
779 *start = saved_rindex;
784 dns_packet_rewind(p, saved_rindex);
788 int dns_packet_read_name(DnsPacket *p, char **_ret, size_t *start) {
789 size_t saved_rindex, after_rindex = 0;
790 _cleanup_free_ char *ret = NULL;
791 size_t n = 0, allocated = 0;
798 saved_rindex = p->rindex;
803 r = dns_packet_read_uint8(p, &c, NULL);
811 _cleanup_free_ char *t = NULL;
815 r = dns_packet_read(p, c, (const void**) &label, NULL);
819 r = dns_label_escape(label, c, &t);
823 if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) {
833 memcpy(ret + n, t, c);
836 } else if ((c & 0xc0) == 0xc0) {
840 r = dns_packet_read_uint8(p, &d, NULL);
844 ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
845 if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= saved_rindex) {
850 if (after_rindex == 0)
851 after_rindex = p->rindex;
858 if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
865 if (after_rindex != 0)
866 p->rindex= after_rindex;
872 *start = saved_rindex;
877 dns_packet_rewind(p, saved_rindex);
881 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
882 _cleanup_free_ char *name = NULL;
883 uint16_t class, type;
891 saved_rindex = p->rindex;
893 r = dns_packet_read_name(p, &name, NULL);
897 r = dns_packet_read_uint16(p, &type, NULL);
901 r = dns_packet_read_uint16(p, &class, NULL);
905 key = dns_resource_key_new_consume(class, type, name);
915 *start = saved_rindex;
919 dns_packet_rewind(p, saved_rindex);
923 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
924 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
925 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
926 size_t saved_rindex, offset;
934 saved_rindex = p->rindex;
936 r = dns_packet_read_key(p, &key, NULL);
940 if (key->class == DNS_CLASS_ANY ||
941 key->type == DNS_TYPE_ANY) {
946 rr = dns_resource_record_new(key);
952 r = dns_packet_read_uint32(p, &rr->ttl, NULL);
956 r = dns_packet_read_uint16(p, &rdlength, NULL);
960 if (p->rindex + rdlength > p->size) {
967 switch (rr->key->type) {
970 r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
973 r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
976 r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
979 r = dns_packet_read_name(p, &rr->srv.name, NULL);
986 r = dns_packet_read_name(p, &rr->ptr.name, NULL);
990 r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
994 r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
997 case DNS_TYPE_SPF: /* exactly the same as TXT */
1001 while (p->rindex < offset + rdlength) {
1002 r = dns_packet_read_string(p, &s, NULL);
1006 r = strv_consume(&rr->txt.strings, s);
1016 r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
1020 r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
1024 r = dns_packet_read_name(p, &rr->soa.mname, NULL);
1028 r = dns_packet_read_name(p, &rr->soa.rname, NULL);
1032 r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
1036 r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
1040 r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
1044 r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
1048 r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
1052 r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
1056 r = dns_packet_read_name(p, &rr->mx.exchange, NULL);
1059 case DNS_TYPE_LOC: {
1063 r = dns_packet_read_uint8(p, &t, &pos);
1068 rr->loc.version = t;
1070 r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
1074 r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
1078 r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
1082 r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
1086 r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
1090 r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
1096 dns_packet_rewind(p, pos);
1097 rr->unparseable = true;
1102 case DNS_TYPE_SSHFP:
1104 r = dns_packet_read(p, rdlength, &d, NULL);
1108 rr->generic.data = memdup(d, rdlength);
1109 if (!rr->generic.data) {
1114 rr->generic.size = rdlength;
1119 if (p->rindex != offset + rdlength) {
1128 *start = saved_rindex;
1132 dns_packet_rewind(p, saved_rindex);
1136 int dns_packet_extract(DnsPacket *p) {
1137 _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
1138 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1139 size_t saved_rindex;
1143 saved_rindex = p->rindex;
1144 dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
1146 n = DNS_PACKET_QDCOUNT(p);
1148 question = dns_question_new(n);
1154 for (i = 0; i < n; i++) {
1155 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1157 r = dns_packet_read_key(p, &key, NULL);
1161 r = dns_question_add(question, key);
1167 n = DNS_PACKET_RRCOUNT(p);
1169 answer = dns_answer_new(n);
1175 for (i = 0; i < n; i++) {
1176 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1178 r = dns_packet_read_rr(p, &rr, NULL);
1182 r = dns_answer_add(answer, rr);
1188 p->question = question;
1197 p->rindex = saved_rindex;
1201 static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
1202 [DNS_RCODE_SUCCESS] = "SUCCESS",
1203 [DNS_RCODE_FORMERR] = "FORMERR",
1204 [DNS_RCODE_SERVFAIL] = "SERVFAIL",
1205 [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
1206 [DNS_RCODE_NOTIMP] = "NOTIMP",
1207 [DNS_RCODE_REFUSED] = "REFUSED",
1208 [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
1209 [DNS_RCODE_YXRRSET] = "YRRSET",
1210 [DNS_RCODE_NXRRSET] = "NXRRSET",
1211 [DNS_RCODE_NOTAUTH] = "NOTAUTH",
1212 [DNS_RCODE_NOTZONE] = "NOTZONE",
1213 [DNS_RCODE_BADVERS] = "BADVERS",
1214 [DNS_RCODE_BADKEY] = "BADKEY",
1215 [DNS_RCODE_BADTIME] = "BADTIME",
1216 [DNS_RCODE_BADMODE] = "BADMODE",
1217 [DNS_RCODE_BADNAME] = "BADNAME",
1218 [DNS_RCODE_BADALG] = "BADALG",
1219 [DNS_RCODE_BADTRUNC] = "BADTRUNC",
1221 DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
1223 static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
1224 [DNS_PROTOCOL_DNS] = "dns",
1225 [DNS_PROTOCOL_MDNS] = "mdns",
1226 [DNS_PROTOCOL_LLMNR] = "llmnr",
1228 DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);