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];
395 n = PTR_TO_SIZE(hashmap_get(p->names, name));
400 r = dns_packet_append_uint16(p, 0xC000 | n, NULL);
414 r = dns_label_unescape(&name, label, sizeof(label));
418 if (p->protocol == DNS_PROTOCOL_DNS)
419 k = dns_label_apply_idna(label, r, label, sizeof(label));
421 k = dns_label_undo_idna(label, r, label, sizeof(label));
429 r = dns_packet_append_label(p, label, r, &n);
433 r = hashmap_ensure_allocated(&p->names, dns_name_hash_func, dns_name_compare_func);
437 r = hashmap_put(p->names, s, SIZE_TO_PTR(n));
444 r = dns_packet_append_uint8(p, 0, NULL);
455 dns_packet_truncate(p, saved_size);
459 int dns_packet_append_key(DnsPacket *p, const DnsResourceKey *k, size_t *start) {
466 saved_size = p->size;
468 r = dns_packet_append_name(p, DNS_RESOURCE_KEY_NAME(k), NULL);
472 r = dns_packet_append_uint16(p, k->type, NULL);
476 r = dns_packet_append_uint16(p, k->class, NULL);
486 dns_packet_truncate(p, saved_size);
490 int dns_packet_append_rr(DnsPacket *p, const DnsResourceRecord *rr, size_t *start) {
491 size_t saved_size, rdlength_offset, end, rdlength;
497 saved_size = p->size;
499 r = dns_packet_append_key(p, rr->key, NULL);
503 r = dns_packet_append_uint32(p, rr->ttl, NULL);
507 /* Initially we write 0 here */
508 r = dns_packet_append_uint16(p, 0, &rdlength_offset);
512 switch (rr->unparseable ? _DNS_TYPE_INVALID : rr->key->type) {
515 r = dns_packet_append_uint16(p, rr->srv.priority, NULL);
519 r = dns_packet_append_uint16(p, rr->srv.weight, NULL);
523 r = dns_packet_append_uint16(p, rr->srv.port, NULL);
527 r = dns_packet_append_name(p, rr->srv.name, NULL);
534 r = dns_packet_append_name(p, rr->ptr.name, NULL);
538 r = dns_packet_append_string(p, rr->hinfo.cpu, NULL);
542 r = dns_packet_append_string(p, rr->hinfo.os, NULL);
545 case DNS_TYPE_SPF: /* exactly the same as TXT */
549 STRV_FOREACH(s, rr->txt.strings) {
550 r = dns_packet_append_string(p, *s, NULL);
560 r = dns_packet_append_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
564 r = dns_packet_append_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
568 r = dns_packet_append_name(p, rr->soa.mname, NULL);
572 r = dns_packet_append_name(p, rr->soa.rname, NULL);
576 r = dns_packet_append_uint32(p, rr->soa.serial, NULL);
580 r = dns_packet_append_uint32(p, rr->soa.refresh, NULL);
584 r = dns_packet_append_uint32(p, rr->soa.retry, NULL);
588 r = dns_packet_append_uint32(p, rr->soa.expire, NULL);
592 r = dns_packet_append_uint32(p, rr->soa.minimum, NULL);
596 r = dns_packet_append_uint16(p, rr->mx.priority, NULL);
600 r = dns_packet_append_name(p, rr->mx.exchange, NULL);
604 r = dns_packet_append_uint8(p, rr->loc.version, NULL);
608 r = dns_packet_append_uint8(p, rr->loc.size, NULL);
612 r = dns_packet_append_uint8(p, rr->loc.horiz_pre, NULL);
616 r = dns_packet_append_uint8(p, rr->loc.vert_pre, NULL);
620 r = dns_packet_append_uint32(p, rr->loc.latitude, NULL);
624 r = dns_packet_append_uint32(p, rr->loc.longitude, NULL);
628 r = dns_packet_append_uint32(p, rr->loc.altitude, NULL);
632 r = dns_packet_append_uint8(p, rr->sshfp.algorithm, NULL);
635 r = dns_packet_append_uint8(p, rr->sshfp.fptype, NULL);
639 r = dns_packet_append_blob(p, rr->sshfp.key, rr->sshfp.key_size, NULL);
642 case _DNS_TYPE_INVALID: /* unparseable */
645 r = dns_packet_append_blob(p, rr->generic.data, rr->generic.size, NULL);
651 /* Let's calculate the actual data size and update the field */
652 rdlength = p->size - rdlength_offset - sizeof(uint16_t);
653 if (rdlength > 0xFFFF) {
659 p->size = rdlength_offset;
660 r = dns_packet_append_uint16(p, rdlength, NULL);
671 dns_packet_truncate(p, saved_size);
676 int dns_packet_read(DnsPacket *p, size_t sz, const void **ret, size_t *start) {
679 if (p->rindex + sz > p->size)
683 *ret = (uint8_t*) DNS_PACKET_DATA(p) + p->rindex;
692 void dns_packet_rewind(DnsPacket *p, size_t idx) {
694 assert(idx <= p->size);
695 assert(idx >= DNS_PACKET_HEADER_SIZE);
700 int dns_packet_read_blob(DnsPacket *p, void *d, size_t sz, size_t *start) {
707 r = dns_packet_read(p, sz, &q, start);
715 int dns_packet_read_uint8(DnsPacket *p, uint8_t *ret, size_t *start) {
721 r = dns_packet_read(p, sizeof(uint8_t), &d, start);
725 *ret = ((uint8_t*) d)[0];
729 int dns_packet_read_uint16(DnsPacket *p, uint16_t *ret, size_t *start) {
735 r = dns_packet_read(p, sizeof(uint16_t), &d, start);
739 *ret = (((uint16_t) ((uint8_t*) d)[0]) << 8) |
740 ((uint16_t) ((uint8_t*) d)[1]);
744 int dns_packet_read_uint32(DnsPacket *p, uint32_t *ret, size_t *start) {
750 r = dns_packet_read(p, sizeof(uint32_t), &d, start);
754 *ret = (((uint32_t) ((uint8_t*) d)[0]) << 24) |
755 (((uint32_t) ((uint8_t*) d)[1]) << 16) |
756 (((uint32_t) ((uint8_t*) d)[2]) << 8) |
757 ((uint32_t) ((uint8_t*) d)[3]);
762 int dns_packet_read_string(DnsPacket *p, char **ret, size_t *start) {
771 saved_rindex = p->rindex;
773 r = dns_packet_read_uint8(p, &c, NULL);
777 r = dns_packet_read(p, c, &d, NULL);
781 if (memchr(d, 0, c)) {
792 if (!utf8_is_valid(t)) {
801 *start = saved_rindex;
806 dns_packet_rewind(p, saved_rindex);
810 int dns_packet_read_name(DnsPacket *p, char **_ret, size_t *start) {
811 size_t saved_rindex, after_rindex = 0;
812 _cleanup_free_ char *ret = NULL;
813 size_t n = 0, allocated = 0;
820 saved_rindex = p->rindex;
825 r = dns_packet_read_uint8(p, &c, NULL);
833 _cleanup_free_ char *t = NULL;
837 r = dns_packet_read(p, c, (const void**) &label, NULL);
841 r = dns_label_escape(label, c, &t);
845 if (!GREEDY_REALLOC(ret, allocated, n + !first + strlen(t) + 1)) {
855 memcpy(ret + n, t, r);
858 } else if ((c & 0xc0) == 0xc0) {
862 r = dns_packet_read_uint8(p, &d, NULL);
866 ptr = (uint16_t) (c & ~0xc0) << 8 | (uint16_t) d;
867 if (ptr < DNS_PACKET_HEADER_SIZE || ptr >= saved_rindex) {
872 if (after_rindex == 0)
873 after_rindex = p->rindex;
880 if (!GREEDY_REALLOC(ret, allocated, n + 1)) {
887 if (after_rindex != 0)
888 p->rindex= after_rindex;
894 *start = saved_rindex;
899 dns_packet_rewind(p, saved_rindex);
903 int dns_packet_read_key(DnsPacket *p, DnsResourceKey **ret, size_t *start) {
904 _cleanup_free_ char *name = NULL;
905 uint16_t class, type;
913 saved_rindex = p->rindex;
915 r = dns_packet_read_name(p, &name, NULL);
919 r = dns_packet_read_uint16(p, &type, NULL);
923 r = dns_packet_read_uint16(p, &class, NULL);
927 key = dns_resource_key_new_consume(class, type, name);
937 *start = saved_rindex;
941 dns_packet_rewind(p, saved_rindex);
945 static bool loc_size_ok(uint8_t size) {
946 uint8_t m = size >> 4, e = size & 0xF;
948 return m <= 9 && e <= 9 && (m > 0 || e == 0);
951 int dns_packet_read_rr(DnsPacket *p, DnsResourceRecord **ret, size_t *start) {
952 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
953 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
954 size_t saved_rindex, offset;
962 saved_rindex = p->rindex;
964 r = dns_packet_read_key(p, &key, NULL);
968 if (key->class == DNS_CLASS_ANY ||
969 key->type == DNS_TYPE_ANY) {
974 rr = dns_resource_record_new(key);
980 r = dns_packet_read_uint32(p, &rr->ttl, NULL);
984 r = dns_packet_read_uint16(p, &rdlength, NULL);
988 if (p->rindex + rdlength > p->size) {
995 switch (rr->key->type) {
998 r = dns_packet_read_uint16(p, &rr->srv.priority, NULL);
1001 r = dns_packet_read_uint16(p, &rr->srv.weight, NULL);
1004 r = dns_packet_read_uint16(p, &rr->srv.port, NULL);
1007 r = dns_packet_read_name(p, &rr->srv.name, NULL);
1012 case DNS_TYPE_CNAME:
1013 case DNS_TYPE_DNAME:
1014 r = dns_packet_read_name(p, &rr->ptr.name, NULL);
1017 case DNS_TYPE_HINFO:
1018 r = dns_packet_read_string(p, &rr->hinfo.cpu, NULL);
1022 r = dns_packet_read_string(p, &rr->hinfo.os, NULL);
1025 case DNS_TYPE_SPF: /* exactly the same as TXT */
1026 case DNS_TYPE_TXT: {
1029 while (p->rindex < offset + rdlength) {
1030 r = dns_packet_read_string(p, &s, NULL);
1034 r = strv_consume(&rr->txt.strings, s);
1044 r = dns_packet_read_blob(p, &rr->a.in_addr, sizeof(struct in_addr), NULL);
1048 r = dns_packet_read_blob(p, &rr->aaaa.in6_addr, sizeof(struct in6_addr), NULL);
1052 r = dns_packet_read_name(p, &rr->soa.mname, NULL);
1056 r = dns_packet_read_name(p, &rr->soa.rname, NULL);
1060 r = dns_packet_read_uint32(p, &rr->soa.serial, NULL);
1064 r = dns_packet_read_uint32(p, &rr->soa.refresh, NULL);
1068 r = dns_packet_read_uint32(p, &rr->soa.retry, NULL);
1072 r = dns_packet_read_uint32(p, &rr->soa.expire, NULL);
1076 r = dns_packet_read_uint32(p, &rr->soa.minimum, NULL);
1080 r = dns_packet_read_uint16(p, &rr->mx.priority, NULL);
1084 r = dns_packet_read_name(p, &rr->mx.exchange, NULL);
1087 case DNS_TYPE_LOC: {
1091 r = dns_packet_read_uint8(p, &t, &pos);
1096 rr->loc.version = t;
1098 r = dns_packet_read_uint8(p, &rr->loc.size, NULL);
1102 if (!loc_size_ok(rr->loc.size)) {
1107 r = dns_packet_read_uint8(p, &rr->loc.horiz_pre, NULL);
1111 if (!loc_size_ok(rr->loc.horiz_pre)) {
1116 r = dns_packet_read_uint8(p, &rr->loc.vert_pre, NULL);
1120 if (!loc_size_ok(rr->loc.vert_pre)) {
1125 r = dns_packet_read_uint32(p, &rr->loc.latitude, NULL);
1129 r = dns_packet_read_uint32(p, &rr->loc.longitude, NULL);
1133 r = dns_packet_read_uint32(p, &rr->loc.altitude, NULL);
1139 dns_packet_rewind(p, pos);
1140 rr->unparseable = true;
1145 case DNS_TYPE_SSHFP:
1147 r = dns_packet_read_uint8(p, &rr->sshfp.algorithm, NULL);
1151 r = dns_packet_read_uint8(p, &rr->sshfp.fptype, NULL);
1155 r = dns_packet_read(p, rdlength - 2, &d, NULL);
1159 rr->sshfp.key = memdup(d, rdlength - 2);
1160 if (!rr->sshfp.key) {
1165 rr->sshfp.key_size = rdlength - 2;
1170 r = dns_packet_read(p, rdlength, &d, NULL);
1174 rr->generic.data = memdup(d, rdlength);
1175 if (!rr->generic.data) {
1180 rr->generic.size = rdlength;
1185 if (p->rindex != offset + rdlength) {
1194 *start = saved_rindex;
1198 dns_packet_rewind(p, saved_rindex);
1202 int dns_packet_extract(DnsPacket *p) {
1203 _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
1204 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1205 size_t saved_rindex;
1209 saved_rindex = p->rindex;
1210 dns_packet_rewind(p, DNS_PACKET_HEADER_SIZE);
1212 n = DNS_PACKET_QDCOUNT(p);
1214 question = dns_question_new(n);
1220 for (i = 0; i < n; i++) {
1221 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1223 r = dns_packet_read_key(p, &key, NULL);
1227 r = dns_question_add(question, key);
1233 n = DNS_PACKET_RRCOUNT(p);
1235 answer = dns_answer_new(n);
1241 for (i = 0; i < n; i++) {
1242 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1244 r = dns_packet_read_rr(p, &rr, NULL);
1248 r = dns_answer_add(answer, rr);
1254 p->question = question;
1263 p->rindex = saved_rindex;
1267 static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
1268 [DNS_RCODE_SUCCESS] = "SUCCESS",
1269 [DNS_RCODE_FORMERR] = "FORMERR",
1270 [DNS_RCODE_SERVFAIL] = "SERVFAIL",
1271 [DNS_RCODE_NXDOMAIN] = "NXDOMAIN",
1272 [DNS_RCODE_NOTIMP] = "NOTIMP",
1273 [DNS_RCODE_REFUSED] = "REFUSED",
1274 [DNS_RCODE_YXDOMAIN] = "YXDOMAIN",
1275 [DNS_RCODE_YXRRSET] = "YRRSET",
1276 [DNS_RCODE_NXRRSET] = "NXRRSET",
1277 [DNS_RCODE_NOTAUTH] = "NOTAUTH",
1278 [DNS_RCODE_NOTZONE] = "NOTZONE",
1279 [DNS_RCODE_BADVERS] = "BADVERS",
1280 [DNS_RCODE_BADKEY] = "BADKEY",
1281 [DNS_RCODE_BADTIME] = "BADTIME",
1282 [DNS_RCODE_BADMODE] = "BADMODE",
1283 [DNS_RCODE_BADNAME] = "BADNAME",
1284 [DNS_RCODE_BADALG] = "BADALG",
1285 [DNS_RCODE_BADTRUNC] = "BADTRUNC",
1287 DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
1289 static const char* const dns_protocol_table[_DNS_PROTOCOL_MAX] = {
1290 [DNS_PROTOCOL_DNS] = "dns",
1291 [DNS_PROTOCOL_MDNS] = "mdns",
1292 [DNS_PROTOCOL_LLMNR] = "llmnr",
1294 DEFINE_STRING_TABLE_LOOKUP(dns_protocol, DnsProtocol);