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Merge pull request #9534 from martinpitt/nm-test
[thirdparty/systemd.git] / src / resolve / resolved-dns-transaction.c
1 /* SPDX-License-Identifier: LGPL-2.1+ */
2
3 #include "sd-messages.h"
4
5 #include "af-list.h"
6 #include "alloc-util.h"
7 #include "dns-domain.h"
8 #include "errno-list.h"
9 #include "fd-util.h"
10 #include "random-util.h"
11 #include "resolved-dns-cache.h"
12 #include "resolved-dns-transaction.h"
13 #include "resolved-llmnr.h"
14 #include "string-table.h"
15
16 #if ENABLE_DNS_OVER_TLS
17 #include <gnutls/socket.h>
18 #endif
19
20 #define TRANSACTIONS_MAX 4096
21 #define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC)
22
23 /* After how much time to repeat classic DNS requests */
24 #define DNS_TIMEOUT_USEC (SD_RESOLVED_QUERY_TIMEOUT_USEC / DNS_TRANSACTION_ATTEMPTS_MAX)
25
26 static void dns_transaction_reset_answer(DnsTransaction *t) {
27 assert(t);
28
29 t->received = dns_packet_unref(t->received);
30 t->answer = dns_answer_unref(t->answer);
31 t->answer_rcode = 0;
32 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
33 t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
34 t->answer_authenticated = false;
35 t->answer_nsec_ttl = (uint32_t) -1;
36 t->answer_errno = 0;
37 }
38
39 static void dns_transaction_flush_dnssec_transactions(DnsTransaction *t) {
40 DnsTransaction *z;
41
42 assert(t);
43
44 while ((z = set_steal_first(t->dnssec_transactions))) {
45 set_remove(z->notify_transactions, t);
46 set_remove(z->notify_transactions_done, t);
47 dns_transaction_gc(z);
48 }
49 }
50
51 static void dns_transaction_close_connection(DnsTransaction *t) {
52 assert(t);
53
54 if (t->stream) {
55 /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
56 LIST_REMOVE(transactions_by_stream, t->stream->transactions, t);
57
58 /* Remove packet in case it's still in the queue */
59 dns_packet_unref(ordered_set_remove(t->stream->write_queue, t->sent));
60
61 t->stream = dns_stream_unref(t->stream);
62 }
63
64 t->dns_udp_event_source = sd_event_source_unref(t->dns_udp_event_source);
65 t->dns_udp_fd = safe_close(t->dns_udp_fd);
66 }
67
68 static void dns_transaction_stop_timeout(DnsTransaction *t) {
69 assert(t);
70
71 t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
72 }
73
74 DnsTransaction* dns_transaction_free(DnsTransaction *t) {
75 DnsQueryCandidate *c;
76 DnsZoneItem *i;
77 DnsTransaction *z;
78
79 if (!t)
80 return NULL;
81
82 log_debug("Freeing transaction %" PRIu16 ".", t->id);
83
84 dns_transaction_close_connection(t);
85 dns_transaction_stop_timeout(t);
86
87 dns_packet_unref(t->sent);
88 dns_transaction_reset_answer(t);
89
90 dns_server_unref(t->server);
91
92 if (t->scope) {
93 hashmap_remove_value(t->scope->transactions_by_key, t->key, t);
94 LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
95
96 if (t->id != 0)
97 hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
98 }
99
100 while ((c = set_steal_first(t->notify_query_candidates)))
101 set_remove(c->transactions, t);
102 set_free(t->notify_query_candidates);
103
104 while ((c = set_steal_first(t->notify_query_candidates_done)))
105 set_remove(c->transactions, t);
106 set_free(t->notify_query_candidates_done);
107
108 while ((i = set_steal_first(t->notify_zone_items)))
109 i->probe_transaction = NULL;
110 set_free(t->notify_zone_items);
111
112 while ((i = set_steal_first(t->notify_zone_items_done)))
113 i->probe_transaction = NULL;
114 set_free(t->notify_zone_items_done);
115
116 while ((z = set_steal_first(t->notify_transactions)))
117 set_remove(z->dnssec_transactions, t);
118 set_free(t->notify_transactions);
119
120 while ((z = set_steal_first(t->notify_transactions_done)))
121 set_remove(z->dnssec_transactions, t);
122 set_free(t->notify_transactions_done);
123
124 dns_transaction_flush_dnssec_transactions(t);
125 set_free(t->dnssec_transactions);
126
127 dns_answer_unref(t->validated_keys);
128 dns_resource_key_unref(t->key);
129
130 return mfree(t);
131 }
132
133 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);
134
135 bool dns_transaction_gc(DnsTransaction *t) {
136 assert(t);
137
138 if (t->block_gc > 0)
139 return true;
140
141 if (set_isempty(t->notify_query_candidates) &&
142 set_isempty(t->notify_query_candidates_done) &&
143 set_isempty(t->notify_zone_items) &&
144 set_isempty(t->notify_zone_items_done) &&
145 set_isempty(t->notify_transactions) &&
146 set_isempty(t->notify_transactions_done)) {
147 dns_transaction_free(t);
148 return false;
149 }
150
151 return true;
152 }
153
154 static uint16_t pick_new_id(Manager *m) {
155 uint16_t new_id;
156
157 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of
158 * transactions, and it's much lower than the space of IDs. */
159
160 assert_cc(TRANSACTIONS_MAX < 0xFFFF);
161
162 do
163 random_bytes(&new_id, sizeof(new_id));
164 while (new_id == 0 ||
165 hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id)));
166
167 return new_id;
168 }
169
170 int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key) {
171 _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL;
172 int r;
173
174 assert(ret);
175 assert(s);
176 assert(key);
177
178 /* Don't allow looking up invalid or pseudo RRs */
179 if (!dns_type_is_valid_query(key->type))
180 return -EINVAL;
181 if (dns_type_is_obsolete(key->type))
182 return -EOPNOTSUPP;
183
184 /* We only support the IN class */
185 if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY))
186 return -EOPNOTSUPP;
187
188 if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX)
189 return -EBUSY;
190
191 r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL);
192 if (r < 0)
193 return r;
194
195 r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops);
196 if (r < 0)
197 return r;
198
199 t = new0(DnsTransaction, 1);
200 if (!t)
201 return -ENOMEM;
202
203 t->dns_udp_fd = -1;
204 t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
205 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
206 t->answer_nsec_ttl = (uint32_t) -1;
207 t->key = dns_resource_key_ref(key);
208 t->current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
209 t->clamp_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
210
211 t->id = pick_new_id(s->manager);
212
213 r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t);
214 if (r < 0) {
215 t->id = 0;
216 return r;
217 }
218
219 r = hashmap_replace(s->transactions_by_key, t->key, t);
220 if (r < 0) {
221 hashmap_remove(s->manager->dns_transactions, UINT_TO_PTR(t->id));
222 return r;
223 }
224
225 LIST_PREPEND(transactions_by_scope, s->transactions, t);
226 t->scope = s;
227
228 s->manager->n_transactions_total++;
229
230 if (ret)
231 *ret = t;
232
233 t = NULL;
234
235 return 0;
236 }
237
238 static void dns_transaction_shuffle_id(DnsTransaction *t) {
239 uint16_t new_id;
240 assert(t);
241
242 /* Pick a new ID for this transaction. */
243
244 new_id = pick_new_id(t->scope->manager);
245 assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0);
246
247 log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id);
248 t->id = new_id;
249
250 /* Make sure we generate a new packet with the new ID */
251 t->sent = dns_packet_unref(t->sent);
252 }
253
254 static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
255 _cleanup_free_ char *pretty = NULL;
256 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
257 DnsZoneItem *z;
258
259 assert(t);
260 assert(p);
261
262 if (manager_our_packet(t->scope->manager, p) != 0)
263 return;
264
265 (void) in_addr_to_string(p->family, &p->sender, &pretty);
266
267 log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.",
268 t->id,
269 dns_resource_key_to_string(t->key, key_str, sizeof key_str),
270 dns_protocol_to_string(t->scope->protocol),
271 t->scope->link ? t->scope->link->name : "*",
272 af_to_name_short(t->scope->family),
273 strnull(pretty));
274
275 /* RFC 4795, Section 4.1 says that the peer with the
276 * lexicographically smaller IP address loses */
277 if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) {
278 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
279 return;
280 }
281
282 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
283
284 t->block_gc++;
285
286 while ((z = set_first(t->notify_zone_items))) {
287 /* First, make sure the zone item drops the reference
288 * to us */
289 dns_zone_item_probe_stop(z);
290
291 /* Secondly, report this as conflict, so that we might
292 * look for a different hostname */
293 dns_zone_item_conflict(z);
294 }
295 t->block_gc--;
296
297 dns_transaction_gc(t);
298 }
299
300 void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) {
301 DnsQueryCandidate *c;
302 DnsZoneItem *z;
303 DnsTransaction *d;
304 const char *st;
305 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
306
307 assert(t);
308 assert(!DNS_TRANSACTION_IS_LIVE(state));
309
310 if (state == DNS_TRANSACTION_DNSSEC_FAILED) {
311 dns_resource_key_to_string(t->key, key_str, sizeof key_str);
312
313 log_struct(LOG_NOTICE,
314 "MESSAGE_ID=" SD_MESSAGE_DNSSEC_FAILURE_STR,
315 LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str, dnssec_result_to_string(t->answer_dnssec_result)),
316 "DNS_TRANSACTION=%" PRIu16, t->id,
317 "DNS_QUESTION=%s", key_str,
318 "DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result),
319 "DNS_SERVER=%s", dns_server_string(t->server),
320 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level));
321 }
322
323 /* Note that this call might invalidate the query. Callers
324 * should hence not attempt to access the query or transaction
325 * after calling this function. */
326
327 if (state == DNS_TRANSACTION_ERRNO)
328 st = errno_to_name(t->answer_errno);
329 else
330 st = dns_transaction_state_to_string(state);
331
332 log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
333 t->id,
334 dns_resource_key_to_string(t->key, key_str, sizeof key_str),
335 dns_protocol_to_string(t->scope->protocol),
336 t->scope->link ? t->scope->link->name : "*",
337 af_to_name_short(t->scope->family),
338 st,
339 t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source),
340 t->answer_authenticated ? "authenticated" : "unsigned");
341
342 t->state = state;
343
344 dns_transaction_close_connection(t);
345 dns_transaction_stop_timeout(t);
346
347 /* Notify all queries that are interested, but make sure the
348 * transaction isn't freed while we are still looking at it */
349 t->block_gc++;
350
351 SET_FOREACH_MOVE(c, t->notify_query_candidates_done, t->notify_query_candidates)
352 dns_query_candidate_notify(c);
353 SWAP_TWO(t->notify_query_candidates, t->notify_query_candidates_done);
354
355 SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items)
356 dns_zone_item_notify(z);
357 SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done);
358 if (t->probing && t->state == DNS_TRANSACTION_ATTEMPTS_MAX_REACHED)
359 (void) dns_scope_announce(t->scope, false);
360
361 SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions)
362 dns_transaction_notify(d, t);
363 SWAP_TWO(t->notify_transactions, t->notify_transactions_done);
364
365 t->block_gc--;
366 dns_transaction_gc(t);
367 }
368
369 static int dns_transaction_pick_server(DnsTransaction *t) {
370 DnsServer *server;
371
372 assert(t);
373 assert(t->scope->protocol == DNS_PROTOCOL_DNS);
374
375 /* Pick a DNS server and a feature level for it. */
376
377 server = dns_scope_get_dns_server(t->scope);
378 if (!server)
379 return -ESRCH;
380
381 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
382 * different properties. */
383 if (server != t->server)
384 t->clamp_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID;
385
386 t->current_feature_level = dns_server_possible_feature_level(server);
387
388 /* Clamp the feature level if that is requested. */
389 if (t->clamp_feature_level != _DNS_SERVER_FEATURE_LEVEL_INVALID &&
390 t->current_feature_level > t->clamp_feature_level)
391 t->current_feature_level = t->clamp_feature_level;
392
393 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t->current_feature_level), t->id);
394
395 if (server == t->server)
396 return 0;
397
398 dns_server_unref(t->server);
399 t->server = dns_server_ref(server);
400
401 t->n_picked_servers ++;
402
403 log_debug("Using DNS server %s for transaction %u.", dns_server_string(t->server), t->id);
404
405 return 1;
406 }
407
408 static void dns_transaction_retry(DnsTransaction *t, bool next_server) {
409 int r;
410
411 assert(t);
412
413 log_debug("Retrying transaction %" PRIu16 ".", t->id);
414
415 /* Before we try again, switch to a new server. */
416 if (next_server)
417 dns_scope_next_dns_server(t->scope);
418
419 r = dns_transaction_go(t);
420 if (r < 0) {
421 t->answer_errno = -r;
422 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
423 }
424 }
425
426 static int dns_transaction_maybe_restart(DnsTransaction *t) {
427 int r;
428
429 assert(t);
430
431 /* Returns > 0 if the transaction was restarted, 0 if not */
432
433 if (!t->server)
434 return 0;
435
436 if (t->current_feature_level <= dns_server_possible_feature_level(t->server))
437 return 0;
438
439 /* The server's current feature level is lower than when we sent the original query. We learnt something from
440 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
441 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
442 OPT RR or DO bit. One of these cases is documented here, for example:
443 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
444
445 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
446 dns_transaction_shuffle_id(t);
447
448 r = dns_transaction_go(t);
449 if (r < 0)
450 return r;
451
452 return 1;
453 }
454
455 static void on_transaction_stream_error(DnsTransaction *t, int error) {
456 assert(t);
457
458 dns_transaction_close_connection(t);
459
460 if (ERRNO_IS_DISCONNECT(error)) {
461 if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
462 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
463 * question on this scope. */
464 dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND);
465 return;
466 }
467
468 dns_transaction_retry(t, true);
469 return;
470 }
471 if (error != 0) {
472 t->answer_errno = error;
473 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
474 }
475 }
476
477 static int dns_transaction_on_stream_packet(DnsTransaction *t, DnsPacket *p) {
478 assert(t);
479 assert(p);
480
481 dns_transaction_close_connection(t);
482
483 if (dns_packet_validate_reply(p) <= 0) {
484 log_debug("Invalid TCP reply packet.");
485 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
486 return 0;
487 }
488
489 dns_scope_check_conflicts(t->scope, p);
490
491 t->block_gc++;
492 dns_transaction_process_reply(t, p);
493 t->block_gc--;
494
495 /* If the response wasn't useful, then complete the transition
496 * now. After all, we are the worst feature set now with TCP
497 * sockets, and there's really no point in retrying. */
498 if (t->state == DNS_TRANSACTION_PENDING)
499 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
500 else
501 dns_transaction_gc(t);
502
503 return 0;
504 }
505
506 static int on_stream_connection(DnsStream *s) {
507 #if ENABLE_DNS_OVER_TLS
508 /* Store TLS Ticket for faster succesive TLS handshakes */
509 if (s->tls_session && s->server) {
510 if (s->server->tls_session_data.data)
511 gnutls_free(s->server->tls_session_data.data);
512
513 gnutls_session_get_data2(s->tls_session, &s->server->tls_session_data);
514 }
515 #endif
516
517 return 0;
518 }
519
520 static int on_stream_complete(DnsStream *s, int error) {
521 _cleanup_(dns_stream_unrefp) DnsStream *p = NULL;
522 DnsTransaction *t, *n;
523 int r = 0;
524
525 /* Do not let new transactions use this stream */
526 if (s->server && s->server->stream == s)
527 p = TAKE_PTR(s->server->stream);
528
529 if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) {
530 usec_t usec;
531
532 log_debug_errno(error, "Connection failure for DNS TCP stream: %m");
533
534 if (s->transactions) {
535 t = s->transactions;
536 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
537 dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level);
538 }
539 }
540
541 LIST_FOREACH_SAFE(transactions_by_stream, t, n, s->transactions)
542 if (error != 0)
543 on_transaction_stream_error(t, error);
544 else if (DNS_PACKET_ID(s->read_packet) == t->id)
545 /* As each transaction have a unique id the return code is only set once */
546 r = dns_transaction_on_stream_packet(t, s->read_packet);
547
548 return r;
549 }
550
551 static int dns_stream_on_packet(DnsStream *s) {
552 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
553 int r = 0;
554 DnsTransaction *t;
555
556 /* Take ownership of packet to be able to receive new packets */
557 p = TAKE_PTR(s->read_packet);
558 s->n_read = 0;
559
560 t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
561
562 /* Ignore incorrect transaction id as transaction can have been canceled */
563 if (t)
564 r = dns_transaction_on_stream_packet(t, p);
565 else {
566 if (dns_packet_validate_reply(p) <= 0) {
567 log_debug("Invalid TCP reply packet.");
568 on_stream_complete(s, 0);
569 }
570 return 0;
571 }
572
573 return r;
574 }
575
576 static int dns_transaction_emit_tcp(DnsTransaction *t) {
577 _cleanup_close_ int fd = -1;
578 _cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
579 union sockaddr_union sa;
580 int r;
581 #if ENABLE_DNS_OVER_TLS
582 gnutls_session_t gs;
583 #endif
584
585 assert(t);
586
587 dns_transaction_close_connection(t);
588
589 switch (t->scope->protocol) {
590
591 case DNS_PROTOCOL_DNS:
592 r = dns_transaction_pick_server(t);
593 if (r < 0)
594 return r;
595
596 if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type))
597 return -EOPNOTSUPP;
598
599 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
600 if (r < 0)
601 return r;
602
603 if (t->server->stream && (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) == t->server->stream->encrypted))
604 s = dns_stream_ref(t->server->stream);
605 else
606 fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) ? 853 : 53, &sa);
607
608 break;
609
610 case DNS_PROTOCOL_LLMNR:
611 /* When we already received a reply to this (but it was truncated), send to its sender address */
612 if (t->received)
613 fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port, &sa);
614 else {
615 union in_addr_union address;
616 int family = AF_UNSPEC;
617
618 /* Otherwise, try to talk to the owner of a
619 * the IP address, in case this is a reverse
620 * PTR lookup */
621
622 r = dns_name_address(dns_resource_key_name(t->key), &family, &address);
623 if (r < 0)
624 return r;
625 if (r == 0)
626 return -EINVAL;
627 if (family != t->scope->family)
628 return -ESRCH;
629
630 fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT, &sa);
631 }
632
633 break;
634
635 default:
636 return -EAFNOSUPPORT;
637 }
638
639 if (!s) {
640 if (fd < 0)
641 return fd;
642
643 r = dns_stream_new(t->scope->manager, &s, t->scope->protocol, fd, &sa);
644 if (r < 0)
645 return r;
646
647 fd = -1;
648
649 if (t->server) {
650 dns_stream_unref(t->server->stream);
651 t->server->stream = dns_stream_ref(s);
652 s->server = dns_server_ref(t->server);
653 }
654
655 #if ENABLE_DNS_OVER_TLS
656 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) {
657 assert(t->server);
658
659 r = gnutls_init(&gs, GNUTLS_CLIENT | GNUTLS_ENABLE_FALSE_START | GNUTLS_NONBLOCK);
660 if (r < 0)
661 return r;
662
663 /* As DNS-over-TLS is a recent protocol, older TLS versions can be disabled */
664 r = gnutls_priority_set_direct(gs, "NORMAL:-VERS-ALL:+VERS-TLS1.2", NULL);
665 if (r < 0)
666 return r;
667
668 r = gnutls_credentials_set(gs, GNUTLS_CRD_CERTIFICATE, t->server->tls_cert_cred);
669 if (r < 0)
670 return r;
671
672 if (t->server->tls_session_data.size > 0)
673 gnutls_session_set_data(gs, t->server->tls_session_data.data, t->server->tls_session_data.size);
674
675 gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
676
677 r = dns_stream_connect_tls(s, gs);
678 if (r < 0)
679 return r;
680 }
681 #endif
682
683 s->on_connection = on_stream_connection;
684 s->complete = on_stream_complete;
685 s->on_packet = dns_stream_on_packet;
686
687 /* The interface index is difficult to determine if we are
688 * connecting to the local host, hence fill this in right away
689 * instead of determining it from the socket */
690 s->ifindex = dns_scope_ifindex(t->scope);
691 }
692
693 t->stream = TAKE_PTR(s);
694 LIST_PREPEND(transactions_by_stream, t->stream->transactions, t);
695
696 r = dns_stream_write_packet(t->stream, t->sent);
697 if (r < 0) {
698 dns_transaction_close_connection(t);
699 return r;
700 }
701
702 dns_transaction_reset_answer(t);
703
704 t->tried_stream = true;
705
706 return 0;
707 }
708
709 static void dns_transaction_cache_answer(DnsTransaction *t) {
710 assert(t);
711
712 /* For mDNS we cache whenever we get the packet, rather than
713 * in each transaction. */
714 if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR))
715 return;
716
717 /* Caching disabled? */
718 if (!t->scope->manager->enable_cache)
719 return;
720
721 /* We never cache if this packet is from the local host, under
722 * the assumption that a locally running DNS server would
723 * cache this anyway, and probably knows better when to flush
724 * the cache then we could. */
725 if (!DNS_PACKET_SHALL_CACHE(t->received))
726 return;
727
728 dns_cache_put(&t->scope->cache,
729 t->key,
730 t->answer_rcode,
731 t->answer,
732 t->answer_authenticated,
733 t->answer_nsec_ttl,
734 0,
735 t->received->family,
736 &t->received->sender);
737 }
738
739 static bool dns_transaction_dnssec_is_live(DnsTransaction *t) {
740 DnsTransaction *dt;
741 Iterator i;
742
743 assert(t);
744
745 SET_FOREACH(dt, t->dnssec_transactions, i)
746 if (DNS_TRANSACTION_IS_LIVE(dt->state))
747 return true;
748
749 return false;
750 }
751
752 static int dns_transaction_dnssec_ready(DnsTransaction *t) {
753 DnsTransaction *dt;
754 Iterator i;
755
756 assert(t);
757
758 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
759 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
760
761 SET_FOREACH(dt, t->dnssec_transactions, i) {
762
763 switch (dt->state) {
764
765 case DNS_TRANSACTION_NULL:
766 case DNS_TRANSACTION_PENDING:
767 case DNS_TRANSACTION_VALIDATING:
768 /* Still ongoing */
769 return 0;
770
771 case DNS_TRANSACTION_RCODE_FAILURE:
772 if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) {
773 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt->answer_rcode));
774 goto fail;
775 }
776
777 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
778 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
779 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
780 * RRs to make unsigned proofs. */
781
782 case DNS_TRANSACTION_SUCCESS:
783 /* All good. */
784 break;
785
786 case DNS_TRANSACTION_DNSSEC_FAILED:
787 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
788 * validationr result */
789
790 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt->answer_dnssec_result));
791 t->answer_dnssec_result = dt->answer_dnssec_result; /* Copy error code over */
792 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
793 return 0;
794
795 default:
796 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state));
797 goto fail;
798 }
799 }
800
801 /* All is ready, we can go and validate */
802 return 1;
803
804 fail:
805 t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY;
806 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
807 return 0;
808 }
809
810 static void dns_transaction_process_dnssec(DnsTransaction *t) {
811 int r;
812
813 assert(t);
814
815 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
816 r = dns_transaction_dnssec_ready(t);
817 if (r < 0)
818 goto fail;
819 if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
820 return;
821
822 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
823 * restart the lookup immediately. */
824 r = dns_transaction_maybe_restart(t);
825 if (r < 0)
826 goto fail;
827 if (r > 0) /* Transaction got restarted... */
828 return;
829
830 /* All our auxiliary DNSSEC transactions are complete now. Try
831 * to validate our RRset now. */
832 r = dns_transaction_validate_dnssec(t);
833 if (r == -EBADMSG) {
834 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
835 return;
836 }
837 if (r < 0)
838 goto fail;
839
840 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER &&
841 t->scope->dnssec_mode == DNSSEC_YES) {
842
843 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
844 * that works. */
845
846 if (t->n_picked_servers < dns_scope_get_n_dns_servers(t->scope)) {
847 /* We tried fewer servers on this transaction than we know, let's try another one then */
848 dns_transaction_retry(t, true);
849 return;
850 }
851
852 /* OK, let's give up, apparently all servers we tried didn't work. */
853 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
854 return;
855 }
856
857 if (!IN_SET(t->answer_dnssec_result,
858 _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */
859 DNSSEC_VALIDATED, /* Answer is signed and validated successfully */
860 DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */
861 DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
862 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
863 return;
864 }
865
866 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER)
867 dns_server_warn_downgrade(t->server);
868
869 dns_transaction_cache_answer(t);
870
871 if (t->answer_rcode == DNS_RCODE_SUCCESS)
872 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
873 else
874 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
875
876 return;
877
878 fail:
879 t->answer_errno = -r;
880 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
881 }
882
883 static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) {
884 int r;
885
886 assert(t);
887
888 /* Checks whether the answer is positive, i.e. either a direct
889 * answer to the question, or a CNAME/DNAME for it */
890
891 r = dns_answer_match_key(t->answer, t->key, flags);
892 if (r != 0)
893 return r;
894
895 r = dns_answer_find_cname_or_dname(t->answer, t->key, NULL, flags);
896 if (r != 0)
897 return r;
898
899 return false;
900 }
901
902 static int dns_transaction_fix_rcode(DnsTransaction *t) {
903 int r;
904
905 assert(t);
906
907 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
908 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
909 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
910 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
911 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
912 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
913 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
914 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
915 * incomplete CNAME/DNAME chain.
916 *
917 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
918 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
919 * lookup. */
920
921 if (t->answer_rcode != DNS_RCODE_NXDOMAIN)
922 return 0;
923
924 r = dns_transaction_has_positive_answer(t, NULL);
925 if (r <= 0)
926 return r;
927
928 t->answer_rcode = DNS_RCODE_SUCCESS;
929 return 0;
930 }
931
932 void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
933 usec_t ts;
934 int r;
935
936 assert(t);
937 assert(p);
938 assert(t->scope);
939 assert(t->scope->manager);
940
941 if (t->state != DNS_TRANSACTION_PENDING)
942 return;
943
944 /* Note that this call might invalidate the query. Callers
945 * should hence not attempt to access the query or transaction
946 * after calling this function. */
947
948 log_debug("Processing incoming packet on transaction %" PRIu16" (rcode=%s).",
949 t->id, dns_rcode_to_string(DNS_PACKET_RCODE(p)));
950
951 switch (t->scope->protocol) {
952
953 case DNS_PROTOCOL_LLMNR:
954 /* For LLMNR we will not accept any packets from other interfaces */
955
956 if (p->ifindex != dns_scope_ifindex(t->scope))
957 return;
958
959 if (p->family != t->scope->family)
960 return;
961
962 /* Tentative packets are not full responses but still
963 * useful for identifying uniqueness conflicts during
964 * probing. */
965 if (DNS_PACKET_LLMNR_T(p)) {
966 dns_transaction_tentative(t, p);
967 return;
968 }
969
970 break;
971
972 case DNS_PROTOCOL_MDNS:
973 /* For mDNS we will not accept any packets from other interfaces */
974
975 if (p->ifindex != dns_scope_ifindex(t->scope))
976 return;
977
978 if (p->family != t->scope->family)
979 return;
980
981 break;
982
983 case DNS_PROTOCOL_DNS:
984 /* Note that we do not need to verify the
985 * addresses/port numbers of incoming traffic, as we
986 * invoked connect() on our UDP socket in which case
987 * the kernel already does the needed verification for
988 * us. */
989 break;
990
991 default:
992 assert_not_reached("Invalid DNS protocol.");
993 }
994
995 if (t->received != p) {
996 dns_packet_unref(t->received);
997 t->received = dns_packet_ref(p);
998 }
999
1000 t->answer_source = DNS_TRANSACTION_NETWORK;
1001
1002 if (p->ipproto == IPPROTO_TCP) {
1003 if (DNS_PACKET_TC(p)) {
1004 /* Truncated via TCP? Somebody must be fucking with us */
1005 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1006 return;
1007 }
1008
1009 if (DNS_PACKET_ID(p) != t->id) {
1010 /* Not the reply to our query? Somebody must be fucking with us */
1011 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1012 return;
1013 }
1014 }
1015
1016 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1017
1018 switch (t->scope->protocol) {
1019
1020 case DNS_PROTOCOL_DNS:
1021 assert(t->server);
1022
1023 if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
1024
1025 /* Request failed, immediately try again with reduced features */
1026
1027 if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) {
1028
1029 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
1030 * this transaction anymore, but let's see if it might make sense to send the request
1031 * to a different DNS server instead. If not let's process the response, and accept the
1032 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
1033 * packet loss, but is not going to give us better rcodes should we actually have
1034 * managed to get them already at UDP level. */
1035
1036 if (t->n_picked_servers < dns_scope_get_n_dns_servers(t->scope)) {
1037 /* We tried fewer servers on this transaction than we know, let's try another one then */
1038 dns_transaction_retry(t, true);
1039 return;
1040 }
1041
1042 /* Give up, accept the rcode */
1043 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
1044 break;
1045 }
1046
1047 /* Reduce this feature level by one and try again. */
1048 switch (t->current_feature_level) {
1049 case DNS_SERVER_FEATURE_LEVEL_TLS_DO:
1050 t->clamp_feature_level = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN;
1051 break;
1052 case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN + 1:
1053 /* Skip plain TLS when TLS is not supported */
1054 t->clamp_feature_level = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN - 1;
1055 break;
1056 default:
1057 t->clamp_feature_level = t->current_feature_level - 1;
1058 }
1059
1060 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
1061 dns_rcode_to_string(DNS_PACKET_RCODE(p)),
1062 dns_server_feature_level_to_string(t->clamp_feature_level));
1063
1064 dns_transaction_retry(t, false /* use the same server */);
1065 return;
1066 }
1067
1068 if (DNS_PACKET_RCODE(p) == DNS_RCODE_REFUSED) {
1069 /* This server refused our request? If so, try again, use a different server */
1070 log_debug("Server returned REFUSED, switching servers, and retrying.");
1071 dns_transaction_retry(t, true /* pick a new server */);
1072 return;
1073 }
1074
1075 if (DNS_PACKET_TC(p))
1076 dns_server_packet_truncated(t->server, t->current_feature_level);
1077
1078 break;
1079
1080 case DNS_PROTOCOL_LLMNR:
1081 case DNS_PROTOCOL_MDNS:
1082 dns_scope_packet_received(t->scope, ts - t->start_usec);
1083 break;
1084
1085 default:
1086 assert_not_reached("Invalid DNS protocol.");
1087 }
1088
1089 if (DNS_PACKET_TC(p)) {
1090
1091 /* Truncated packets for mDNS are not allowed. Give up immediately. */
1092 if (t->scope->protocol == DNS_PROTOCOL_MDNS) {
1093 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1094 return;
1095 }
1096
1097 log_debug("Reply truncated, retrying via TCP.");
1098
1099 /* Response was truncated, let's try again with good old TCP */
1100 r = dns_transaction_emit_tcp(t);
1101 if (r == -ESRCH) {
1102 /* No servers found? Damn! */
1103 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
1104 return;
1105 }
1106 if (r == -EOPNOTSUPP) {
1107 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1108 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
1109 return;
1110 }
1111 if (r < 0) {
1112 /* On LLMNR, if we cannot connect to the host,
1113 * we immediately give up */
1114 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1115 goto fail;
1116
1117 /* On DNS, couldn't send? Try immediately again, with a new server */
1118 dns_transaction_retry(t, true);
1119 }
1120
1121 return;
1122 }
1123
1124 /* After the superficial checks, actually parse the message. */
1125 r = dns_packet_extract(p);
1126 if (r < 0) {
1127 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1128 return;
1129 }
1130
1131 if (t->server) {
1132 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1133 * rcode and subsequently downgraded the protocol */
1134
1135 if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) &&
1136 t->clamp_feature_level != _DNS_SERVER_FEATURE_LEVEL_INVALID)
1137 dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level);
1138
1139 /* Report that the OPT RR was missing */
1140 if (!p->opt)
1141 dns_server_packet_bad_opt(t->server, t->current_feature_level);
1142
1143 /* Report that we successfully received a packet */
1144 dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, p->size);
1145 }
1146
1147 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1148 r = dns_transaction_maybe_restart(t);
1149 if (r < 0)
1150 goto fail;
1151 if (r > 0) /* Transaction got restarted... */
1152 return;
1153
1154 if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
1155
1156 /* When dealing with protocols other than mDNS only consider responses with
1157 * equivalent query section to the request. For mDNS this check doesn't make
1158 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1159 * contain any questions in the Question Section". */
1160 if (t->scope->protocol != DNS_PROTOCOL_MDNS) {
1161 r = dns_packet_is_reply_for(p, t->key);
1162 if (r < 0)
1163 goto fail;
1164 if (r == 0) {
1165 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1166 return;
1167 }
1168 }
1169
1170 /* Install the answer as answer to the transaction */
1171 dns_answer_unref(t->answer);
1172 t->answer = dns_answer_ref(p->answer);
1173 t->answer_rcode = DNS_PACKET_RCODE(p);
1174 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
1175 t->answer_authenticated = false;
1176
1177 r = dns_transaction_fix_rcode(t);
1178 if (r < 0)
1179 goto fail;
1180
1181 /* Block GC while starting requests for additional DNSSEC RRs */
1182 t->block_gc++;
1183 r = dns_transaction_request_dnssec_keys(t);
1184 t->block_gc--;
1185
1186 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1187 if (!dns_transaction_gc(t))
1188 return;
1189
1190 /* Requesting additional keys might have resulted in
1191 * this transaction to fail, since the auxiliary
1192 * request failed for some reason. If so, we are not
1193 * in pending state anymore, and we should exit
1194 * quickly. */
1195 if (t->state != DNS_TRANSACTION_PENDING)
1196 return;
1197 if (r < 0)
1198 goto fail;
1199 if (r > 0) {
1200 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1201 t->state = DNS_TRANSACTION_VALIDATING;
1202 dns_transaction_close_connection(t);
1203 dns_transaction_stop_timeout(t);
1204 return;
1205 }
1206 }
1207
1208 dns_transaction_process_dnssec(t);
1209 return;
1210
1211 fail:
1212 t->answer_errno = -r;
1213 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
1214 }
1215
1216 static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
1217 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1218 DnsTransaction *t = userdata;
1219 int r;
1220
1221 assert(t);
1222 assert(t->scope);
1223
1224 r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
1225 if (ERRNO_IS_DISCONNECT(-r)) {
1226 usec_t usec;
1227
1228 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1229 * recvmsg(). Treat this like a lost packet. */
1230
1231 log_debug_errno(r, "Connection failure for DNS UDP packet: %m");
1232 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
1233 dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level);
1234
1235 dns_transaction_retry(t, true);
1236 return 0;
1237 }
1238 if (r < 0) {
1239 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
1240 t->answer_errno = -r;
1241 return 0;
1242 }
1243
1244 r = dns_packet_validate_reply(p);
1245 if (r < 0) {
1246 log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m");
1247 return 0;
1248 }
1249 if (r == 0) {
1250 log_debug("Received inappropriate DNS packet as response, ignoring.");
1251 return 0;
1252 }
1253
1254 if (DNS_PACKET_ID(p) != t->id) {
1255 log_debug("Received packet with incorrect transaction ID, ignoring.");
1256 return 0;
1257 }
1258
1259 dns_transaction_process_reply(t, p);
1260 return 0;
1261 }
1262
1263 static int dns_transaction_emit_udp(DnsTransaction *t) {
1264 int r;
1265
1266 assert(t);
1267
1268 if (t->scope->protocol == DNS_PROTOCOL_DNS) {
1269
1270 r = dns_transaction_pick_server(t);
1271 if (r < 0)
1272 return r;
1273
1274 if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP || DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level))
1275 return -EAGAIN; /* Sorry, can't do UDP, try TCP! */
1276
1277 if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type))
1278 return -EOPNOTSUPP;
1279
1280 if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */
1281 int fd;
1282
1283 dns_transaction_close_connection(t);
1284
1285 fd = dns_scope_socket_udp(t->scope, t->server, 53);
1286 if (fd < 0)
1287 return fd;
1288
1289 r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
1290 if (r < 0) {
1291 safe_close(fd);
1292 return r;
1293 }
1294
1295 (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp");
1296 t->dns_udp_fd = fd;
1297 }
1298
1299 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
1300 if (r < 0)
1301 return r;
1302 } else
1303 dns_transaction_close_connection(t);
1304
1305 r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->sent);
1306 if (r < 0)
1307 return r;
1308
1309 dns_transaction_reset_answer(t);
1310
1311 return 0;
1312 }
1313
1314 static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1315 DnsTransaction *t = userdata;
1316
1317 assert(s);
1318 assert(t);
1319
1320 if (!t->initial_jitter_scheduled || t->initial_jitter_elapsed) {
1321 /* Timeout reached? Increase the timeout for the server used */
1322 switch (t->scope->protocol) {
1323
1324 case DNS_PROTOCOL_DNS:
1325 assert(t->server);
1326 dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level);
1327 break;
1328
1329 case DNS_PROTOCOL_LLMNR:
1330 case DNS_PROTOCOL_MDNS:
1331 dns_scope_packet_lost(t->scope, usec - t->start_usec);
1332 break;
1333
1334 default:
1335 assert_not_reached("Invalid DNS protocol.");
1336 }
1337
1338 if (t->initial_jitter_scheduled)
1339 t->initial_jitter_elapsed = true;
1340 }
1341
1342 log_debug("Timeout reached on transaction %" PRIu16 ".", t->id);
1343
1344 dns_transaction_retry(t, true);
1345 return 0;
1346 }
1347
1348 static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
1349 assert(t);
1350 assert(t->scope);
1351
1352 switch (t->scope->protocol) {
1353
1354 case DNS_PROTOCOL_DNS:
1355
1356 /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
1357 * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
1358 * needlessly. */
1359 if (t->stream)
1360 return TRANSACTION_TCP_TIMEOUT_USEC;
1361
1362 return DNS_TIMEOUT_USEC;
1363
1364 case DNS_PROTOCOL_MDNS:
1365 assert(t->n_attempts > 0);
1366 if (t->probing)
1367 return MDNS_PROBING_INTERVAL_USEC;
1368 else
1369 return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
1370
1371 case DNS_PROTOCOL_LLMNR:
1372 return t->scope->resend_timeout;
1373
1374 default:
1375 assert_not_reached("Invalid DNS protocol.");
1376 }
1377 }
1378
1379 static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
1380 int r;
1381
1382 assert(t);
1383
1384 dns_transaction_stop_timeout(t);
1385
1386 if (!dns_scope_network_good(t->scope)) {
1387 dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN);
1388 return 0;
1389 }
1390
1391 if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
1392 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1393 return 0;
1394 }
1395
1396 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) {
1397 /* If we already tried via a stream, then we don't
1398 * retry on LLMNR. See RFC 4795, Section 2.7. */
1399 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1400 return 0;
1401 }
1402
1403 t->n_attempts++;
1404 t->start_usec = ts;
1405
1406 dns_transaction_reset_answer(t);
1407 dns_transaction_flush_dnssec_transactions(t);
1408
1409 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1410 if (t->scope->protocol == DNS_PROTOCOL_DNS) {
1411 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer);
1412 if (r < 0)
1413 return r;
1414 if (r > 0) {
1415 t->answer_rcode = DNS_RCODE_SUCCESS;
1416 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1417 t->answer_authenticated = true;
1418 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1419 return 0;
1420 }
1421
1422 if (dns_name_is_root(dns_resource_key_name(t->key)) &&
1423 t->key->type == DNS_TYPE_DS) {
1424
1425 /* Hmm, this is a request for the root DS? A
1426 * DS RR doesn't exist in the root zone, and
1427 * if our trust anchor didn't know it either,
1428 * this means we cannot do any DNSSEC logic
1429 * anymore. */
1430
1431 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
1432 /* We are in downgrade mode. In this
1433 * case, synthesize an unsigned empty
1434 * response, so that the any lookup
1435 * depending on this one can continue
1436 * assuming there was no DS, and hence
1437 * the root zone was unsigned. */
1438
1439 t->answer_rcode = DNS_RCODE_SUCCESS;
1440 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1441 t->answer_authenticated = false;
1442 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1443 } else
1444 /* If we are not in downgrade mode,
1445 * then fail the lookup, because we
1446 * cannot reasonably answer it. There
1447 * might be DS RRs, but we don't know
1448 * them, and the DNS server won't tell
1449 * them to us (and even if it would,
1450 * we couldn't validate and trust them. */
1451 dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR);
1452
1453 return 0;
1454 }
1455 }
1456
1457 /* Check the zone, but only if this transaction is not used
1458 * for probing or verifying a zone item. */
1459 if (set_isempty(t->notify_zone_items)) {
1460
1461 r = dns_zone_lookup(&t->scope->zone, t->key, dns_scope_ifindex(t->scope), &t->answer, NULL, NULL);
1462 if (r < 0)
1463 return r;
1464 if (r > 0) {
1465 t->answer_rcode = DNS_RCODE_SUCCESS;
1466 t->answer_source = DNS_TRANSACTION_ZONE;
1467 t->answer_authenticated = true;
1468 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1469 return 0;
1470 }
1471 }
1472
1473 /* Check the cache, but only if this transaction is not used
1474 * for probing or verifying a zone item. */
1475 if (set_isempty(t->notify_zone_items)) {
1476
1477 /* Before trying the cache, let's make sure we figured out a
1478 * server to use. Should this cause a change of server this
1479 * might flush the cache. */
1480 (void) dns_scope_get_dns_server(t->scope);
1481
1482 /* Let's then prune all outdated entries */
1483 dns_cache_prune(&t->scope->cache);
1484
1485 r = dns_cache_lookup(&t->scope->cache, t->key, t->clamp_ttl, &t->answer_rcode, &t->answer, &t->answer_authenticated);
1486 if (r < 0)
1487 return r;
1488 if (r > 0) {
1489 t->answer_source = DNS_TRANSACTION_CACHE;
1490 if (t->answer_rcode == DNS_RCODE_SUCCESS)
1491 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1492 else
1493 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
1494 return 0;
1495 }
1496 }
1497
1498 return 1;
1499 }
1500
1501 static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
1502
1503 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1504 bool add_known_answers = false;
1505 DnsTransaction *other;
1506 Iterator i;
1507 DnsResourceKey *tkey;
1508 _cleanup_set_free_ Set *keys = NULL;
1509 unsigned qdcount;
1510 unsigned nscount = 0;
1511 usec_t ts;
1512 int r;
1513
1514 assert(t);
1515 assert(t->scope->protocol == DNS_PROTOCOL_MDNS);
1516
1517 /* Discard any previously prepared packet, so we can start over and coalesce again */
1518 t->sent = dns_packet_unref(t->sent);
1519
1520 r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
1521 if (r < 0)
1522 return r;
1523
1524 r = dns_packet_append_key(p, t->key, 0, NULL);
1525 if (r < 0)
1526 return r;
1527
1528 qdcount = 1;
1529
1530 if (dns_key_is_shared(t->key))
1531 add_known_answers = true;
1532
1533 if (t->key->type == DNS_TYPE_ANY) {
1534 r = set_ensure_allocated(&keys, &dns_resource_key_hash_ops);
1535 if (r < 0)
1536 return r;
1537
1538 r = set_put(keys, t->key);
1539 if (r < 0)
1540 return r;
1541 }
1542
1543 /*
1544 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1545 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1546 * in our current scope, and see whether their timing contraints allow them to be sent.
1547 */
1548
1549 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1550
1551 LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
1552
1553 /* Skip ourselves */
1554 if (other == t)
1555 continue;
1556
1557 if (other->state != DNS_TRANSACTION_PENDING)
1558 continue;
1559
1560 if (other->next_attempt_after > ts)
1561 continue;
1562
1563 if (qdcount >= UINT16_MAX)
1564 break;
1565
1566 r = dns_packet_append_key(p, other->key, 0, NULL);
1567
1568 /*
1569 * If we can't stuff more questions into the packet, just give up.
1570 * One of the 'other' transactions will fire later and take care of the rest.
1571 */
1572 if (r == -EMSGSIZE)
1573 break;
1574
1575 if (r < 0)
1576 return r;
1577
1578 r = dns_transaction_prepare(other, ts);
1579 if (r <= 0)
1580 continue;
1581
1582 ts += transaction_get_resend_timeout(other);
1583
1584 r = sd_event_add_time(
1585 other->scope->manager->event,
1586 &other->timeout_event_source,
1587 clock_boottime_or_monotonic(),
1588 ts, 0,
1589 on_transaction_timeout, other);
1590 if (r < 0)
1591 return r;
1592
1593 (void) sd_event_source_set_description(other->timeout_event_source, "dns-transaction-timeout");
1594
1595 other->state = DNS_TRANSACTION_PENDING;
1596 other->next_attempt_after = ts;
1597
1598 qdcount++;
1599
1600 if (dns_key_is_shared(other->key))
1601 add_known_answers = true;
1602
1603 if (other->key->type == DNS_TYPE_ANY) {
1604 r = set_ensure_allocated(&keys, &dns_resource_key_hash_ops);
1605 if (r < 0)
1606 return r;
1607
1608 r = set_put(keys, other->key);
1609 if (r < 0)
1610 return r;
1611 }
1612 }
1613
1614 DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
1615
1616 /* Append known answer section if we're asking for any shared record */
1617 if (add_known_answers) {
1618 r = dns_cache_export_shared_to_packet(&t->scope->cache, p);
1619 if (r < 0)
1620 return r;
1621 }
1622
1623 SET_FOREACH(tkey, keys, i) {
1624 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1625 bool tentative;
1626
1627 r = dns_zone_lookup(&t->scope->zone, tkey, t->scope->link->ifindex, &answer, NULL, &tentative);
1628 if (r < 0)
1629 return r;
1630
1631 r = dns_packet_append_answer(p, answer);
1632 if (r < 0)
1633 return r;
1634
1635 nscount += dns_answer_size(answer);
1636 }
1637 DNS_PACKET_HEADER(p)->nscount = htobe16(nscount);
1638
1639 t->sent = TAKE_PTR(p);
1640
1641 return 0;
1642 }
1643
1644 static int dns_transaction_make_packet(DnsTransaction *t) {
1645 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1646 int r;
1647
1648 assert(t);
1649
1650 if (t->scope->protocol == DNS_PROTOCOL_MDNS)
1651 return dns_transaction_make_packet_mdns(t);
1652
1653 if (t->sent)
1654 return 0;
1655
1656 r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO);
1657 if (r < 0)
1658 return r;
1659
1660 r = dns_packet_append_key(p, t->key, 0, NULL);
1661 if (r < 0)
1662 return r;
1663
1664 DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
1665 DNS_PACKET_HEADER(p)->id = t->id;
1666
1667 t->sent = TAKE_PTR(p);
1668
1669 return 0;
1670 }
1671
1672 int dns_transaction_go(DnsTransaction *t) {
1673 usec_t ts;
1674 int r;
1675 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1676
1677 assert(t);
1678
1679 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1680 * now. */
1681
1682 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1683
1684 r = dns_transaction_prepare(t, ts);
1685 if (r <= 0)
1686 return r;
1687
1688 log_debug("Transaction %" PRIu16 " for <%s> scope %s on %s/%s.",
1689 t->id,
1690 dns_resource_key_to_string(t->key, key_str, sizeof key_str),
1691 dns_protocol_to_string(t->scope->protocol),
1692 t->scope->link ? t->scope->link->name : "*",
1693 af_to_name_short(t->scope->family));
1694
1695 if (!t->initial_jitter_scheduled &&
1696 IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
1697 usec_t jitter, accuracy;
1698
1699 /* RFC 4795 Section 2.7 suggests all queries should be
1700 * delayed by a random time from 0 to JITTER_INTERVAL. */
1701
1702 t->initial_jitter_scheduled = true;
1703
1704 random_bytes(&jitter, sizeof(jitter));
1705
1706 switch (t->scope->protocol) {
1707
1708 case DNS_PROTOCOL_LLMNR:
1709 jitter %= LLMNR_JITTER_INTERVAL_USEC;
1710 accuracy = LLMNR_JITTER_INTERVAL_USEC;
1711 break;
1712
1713 case DNS_PROTOCOL_MDNS:
1714 jitter %= MDNS_JITTER_RANGE_USEC;
1715 jitter += MDNS_JITTER_MIN_USEC;
1716 accuracy = MDNS_JITTER_RANGE_USEC;
1717 break;
1718 default:
1719 assert_not_reached("bad protocol");
1720 }
1721
1722 r = sd_event_add_time(
1723 t->scope->manager->event,
1724 &t->timeout_event_source,
1725 clock_boottime_or_monotonic(),
1726 ts + jitter, accuracy,
1727 on_transaction_timeout, t);
1728 if (r < 0)
1729 return r;
1730
1731 (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
1732
1733 t->n_attempts = 0;
1734 t->next_attempt_after = ts;
1735 t->state = DNS_TRANSACTION_PENDING;
1736
1737 log_debug("Delaying %s transaction for " USEC_FMT "us.", dns_protocol_to_string(t->scope->protocol), jitter);
1738 return 0;
1739 }
1740
1741 /* Otherwise, we need to ask the network */
1742 r = dns_transaction_make_packet(t);
1743 if (r < 0)
1744 return r;
1745
1746 if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
1747 (dns_name_endswith(dns_resource_key_name(t->key), "in-addr.arpa") > 0 ||
1748 dns_name_endswith(dns_resource_key_name(t->key), "ip6.arpa") > 0)) {
1749
1750 /* RFC 4795, Section 2.4. says reverse lookups shall
1751 * always be made via TCP on LLMNR */
1752 r = dns_transaction_emit_tcp(t);
1753 } else {
1754 /* Try via UDP, and if that fails due to large size or lack of
1755 * support try via TCP */
1756 r = dns_transaction_emit_udp(t);
1757 if (r == -EMSGSIZE)
1758 log_debug("Sending query via TCP since it is too large.");
1759 else if (r == -EAGAIN)
1760 log_debug("Sending query via TCP since UDP isn't supported.");
1761 if (IN_SET(r, -EMSGSIZE, -EAGAIN))
1762 r = dns_transaction_emit_tcp(t);
1763 }
1764
1765 if (r == -ESRCH) {
1766 /* No servers to send this to? */
1767 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
1768 return 0;
1769 }
1770 if (r == -EOPNOTSUPP) {
1771 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1772 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
1773 return 0;
1774 }
1775 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_DISCONNECT(-r)) {
1776 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1777 * answer this request with this protocol. */
1778 dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND);
1779 return 0;
1780 }
1781 if (r < 0) {
1782 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1783 return r;
1784
1785 /* Couldn't send? Try immediately again, with a new server */
1786 dns_scope_next_dns_server(t->scope);
1787
1788 return dns_transaction_go(t);
1789 }
1790
1791 ts += transaction_get_resend_timeout(t);
1792
1793 r = sd_event_add_time(
1794 t->scope->manager->event,
1795 &t->timeout_event_source,
1796 clock_boottime_or_monotonic(),
1797 ts, 0,
1798 on_transaction_timeout, t);
1799 if (r < 0)
1800 return r;
1801
1802 (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
1803
1804 t->state = DNS_TRANSACTION_PENDING;
1805 t->next_attempt_after = ts;
1806
1807 return 1;
1808 }
1809
1810 static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) {
1811 DnsTransaction *n;
1812 Iterator i;
1813 int r;
1814
1815 assert(t);
1816 assert(aux);
1817
1818 /* Try to find cyclic dependencies between transaction objects */
1819
1820 if (t == aux)
1821 return 1;
1822
1823 SET_FOREACH(n, aux->dnssec_transactions, i) {
1824 r = dns_transaction_find_cyclic(t, n);
1825 if (r != 0)
1826 return r;
1827 }
1828
1829 return 0;
1830 }
1831
1832 static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) {
1833 DnsTransaction *aux;
1834 int r;
1835
1836 assert(t);
1837 assert(ret);
1838 assert(key);
1839
1840 aux = dns_scope_find_transaction(t->scope, key, true);
1841 if (!aux) {
1842 r = dns_transaction_new(&aux, t->scope, key);
1843 if (r < 0)
1844 return r;
1845 } else {
1846 if (set_contains(t->dnssec_transactions, aux)) {
1847 *ret = aux;
1848 return 0;
1849 }
1850
1851 r = dns_transaction_find_cyclic(t, aux);
1852 if (r < 0)
1853 return r;
1854 if (r > 0) {
1855 char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX];
1856
1857 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).",
1858 aux->id,
1859 dns_resource_key_to_string(t->key, s, sizeof s),
1860 t->id,
1861 dns_resource_key_to_string(aux->key, saux, sizeof saux));
1862
1863 return -ELOOP;
1864 }
1865 }
1866
1867 r = set_ensure_allocated(&t->dnssec_transactions, NULL);
1868 if (r < 0)
1869 goto gc;
1870
1871 r = set_ensure_allocated(&aux->notify_transactions, NULL);
1872 if (r < 0)
1873 goto gc;
1874
1875 r = set_ensure_allocated(&aux->notify_transactions_done, NULL);
1876 if (r < 0)
1877 goto gc;
1878
1879 r = set_put(t->dnssec_transactions, aux);
1880 if (r < 0)
1881 goto gc;
1882
1883 r = set_put(aux->notify_transactions, t);
1884 if (r < 0) {
1885 (void) set_remove(t->dnssec_transactions, aux);
1886 goto gc;
1887 }
1888
1889 *ret = aux;
1890 return 1;
1891
1892 gc:
1893 dns_transaction_gc(aux);
1894 return r;
1895 }
1896
1897 static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) {
1898 _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL;
1899 DnsTransaction *aux;
1900 int r;
1901
1902 assert(t);
1903 assert(key);
1904
1905 /* Try to get the data from the trust anchor */
1906 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a);
1907 if (r < 0)
1908 return r;
1909 if (r > 0) {
1910 r = dns_answer_extend(&t->validated_keys, a);
1911 if (r < 0)
1912 return r;
1913
1914 return 0;
1915 }
1916
1917 /* This didn't work, ask for it via the network/cache then. */
1918 r = dns_transaction_add_dnssec_transaction(t, key, &aux);
1919 if (r == -ELOOP) /* This would result in a cyclic dependency */
1920 return 0;
1921 if (r < 0)
1922 return r;
1923
1924 if (aux->state == DNS_TRANSACTION_NULL) {
1925 r = dns_transaction_go(aux);
1926 if (r < 0)
1927 return r;
1928 }
1929
1930 return 1;
1931 }
1932
1933 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) {
1934 int r;
1935
1936 assert(t);
1937
1938 /* Check whether the specified name is in the NTA
1939 * database, either in the global one, or the link-local
1940 * one. */
1941
1942 r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name);
1943 if (r != 0)
1944 return r;
1945
1946 if (!t->scope->link)
1947 return 0;
1948
1949 return set_contains(t->scope->link->dnssec_negative_trust_anchors, name);
1950 }
1951
1952 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction *t) {
1953 int r;
1954
1955 assert(t);
1956
1957 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1958 * RRs to prove it */
1959
1960 r = dns_transaction_has_positive_answer(t, NULL);
1961 if (r < 0)
1962 return r;
1963 if (r > 0)
1964 return false;
1965
1966 /* Is this key explicitly listed as a negative trust anchor?
1967 * If so, it's nothing we need to care about */
1968 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key));
1969 if (r < 0)
1970 return r;
1971 if (r > 0)
1972 return false;
1973
1974 /* The answer does not contain any RRs that match to the
1975 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1976 * included. If not, the answer is unsigned. */
1977
1978 r = dns_answer_contains_nsec_or_nsec3(t->answer);
1979 if (r < 0)
1980 return r;
1981 if (r > 0)
1982 return false;
1983
1984 return true;
1985 }
1986
1987 static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) {
1988 int r;
1989
1990 assert(t);
1991 assert(rr);
1992
1993 /* Check if the specified RR is the "primary" response,
1994 * i.e. either matches the question precisely or is a
1995 * CNAME/DNAME for it. */
1996
1997 r = dns_resource_key_match_rr(t->key, rr, NULL);
1998 if (r != 0)
1999 return r;
2000
2001 return dns_resource_key_match_cname_or_dname(t->key, rr->key, NULL);
2002 }
2003
2004 static bool dns_transaction_dnssec_supported(DnsTransaction *t) {
2005 assert(t);
2006
2007 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
2008 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
2009
2010 if (t->scope->protocol != DNS_PROTOCOL_DNS)
2011 return false;
2012
2013 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
2014 * be supported, hence return true. */
2015 if (!t->server)
2016 return true;
2017
2018 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
2019 * the server is known to support currently, as the transaction feature level might be lower than what the
2020 * server actually supports, since we might have downgraded this transaction's feature level because we got a
2021 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
2022
2023 return dns_server_dnssec_supported(t->server);
2024 }
2025
2026 static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) {
2027 DnsTransaction *dt;
2028 Iterator i;
2029
2030 assert(t);
2031
2032 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
2033
2034 if (!dns_transaction_dnssec_supported(t))
2035 return false;
2036
2037 SET_FOREACH(dt, t->dnssec_transactions, i)
2038 if (!dns_transaction_dnssec_supported(dt))
2039 return false;
2040
2041 return true;
2042 }
2043
2044 int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
2045 DnsResourceRecord *rr;
2046
2047 int r;
2048
2049 assert(t);
2050
2051 /*
2052 * Retrieve all auxiliary RRs for the answer we got, so that
2053 * we can verify signatures or prove that RRs are rightfully
2054 * unsigned. Specifically:
2055 *
2056 * - For RRSIG we get the matching DNSKEY
2057 * - For DNSKEY we get the matching DS
2058 * - For unsigned SOA/NS we get the matching DS
2059 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
2060 * - For other unsigned RRs we get the matching SOA RR
2061 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
2062 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
2063 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
2064 */
2065
2066 if (t->scope->dnssec_mode == DNSSEC_NO)
2067 return 0;
2068 if (t->answer_source != DNS_TRANSACTION_NETWORK)
2069 return 0; /* We only need to validate stuff from the network */
2070 if (!dns_transaction_dnssec_supported(t))
2071 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
2072
2073 DNS_ANSWER_FOREACH(rr, t->answer) {
2074
2075 if (dns_type_is_pseudo(rr->key->type))
2076 continue;
2077
2078 /* If this RR is in the negative trust anchor, we don't need to validate it. */
2079 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2080 if (r < 0)
2081 return r;
2082 if (r > 0)
2083 continue;
2084
2085 switch (rr->key->type) {
2086
2087 case DNS_TYPE_RRSIG: {
2088 /* For each RRSIG we request the matching DNSKEY */
2089 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL;
2090
2091 /* If this RRSIG is about a DNSKEY RR and the
2092 * signer is the same as the owner, then we
2093 * already have the DNSKEY, and we don't have
2094 * to look for more. */
2095 if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) {
2096 r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key));
2097 if (r < 0)
2098 return r;
2099 if (r > 0)
2100 continue;
2101 }
2102
2103 /* If the signer is not a parent of our
2104 * original query, then this is about an
2105 * auxiliary RRset, but not anything we asked
2106 * for. In this case we aren't interested,
2107 * because we don't want to request additional
2108 * RRs for stuff we didn't really ask for, and
2109 * also to avoid request loops, where
2110 * additional RRs from one transaction result
2111 * in another transaction whose additonal RRs
2112 * point back to the original transaction, and
2113 * we deadlock. */
2114 r = dns_name_endswith(dns_resource_key_name(t->key), rr->rrsig.signer);
2115 if (r < 0)
2116 return r;
2117 if (r == 0)
2118 continue;
2119
2120 dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer);
2121 if (!dnskey)
2122 return -ENOMEM;
2123
2124 log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").",
2125 t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag);
2126 r = dns_transaction_request_dnssec_rr(t, dnskey);
2127 if (r < 0)
2128 return r;
2129 break;
2130 }
2131
2132 case DNS_TYPE_DNSKEY: {
2133 /* For each DNSKEY we request the matching DS */
2134 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2135
2136 /* If the DNSKEY we are looking at is not for
2137 * zone we are interested in, nor any of its
2138 * parents, we aren't interested, and don't
2139 * request it. After all, we don't want to end
2140 * up in request loops, and want to keep
2141 * additional traffic down. */
2142
2143 r = dns_name_endswith(dns_resource_key_name(t->key), dns_resource_key_name(rr->key));
2144 if (r < 0)
2145 return r;
2146 if (r == 0)
2147 continue;
2148
2149 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2150 if (!ds)
2151 return -ENOMEM;
2152
2153 log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").",
2154 t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false));
2155 r = dns_transaction_request_dnssec_rr(t, ds);
2156 if (r < 0)
2157 return r;
2158
2159 break;
2160 }
2161
2162 case DNS_TYPE_SOA:
2163 case DNS_TYPE_NS: {
2164 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2165
2166 /* For an unsigned SOA or NS, try to acquire
2167 * the matching DS RR, as we are at a zone cut
2168 * then, and whether a DS exists tells us
2169 * whether the zone is signed. Do so only if
2170 * this RR matches our original question,
2171 * however. */
2172
2173 r = dns_resource_key_match_rr(t->key, rr, NULL);
2174 if (r < 0)
2175 return r;
2176 if (r == 0) {
2177 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2178 * a negative reply, and we need the a SOA RR's TTL in order to cache a negative entry?
2179 * If so, we need to validate it, too. */
2180
2181 r = dns_answer_match_key(t->answer, t->key, NULL);
2182 if (r < 0)
2183 return r;
2184 if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate
2185 * it. */
2186 continue;
2187 }
2188
2189 r = dnssec_has_rrsig(t->answer, rr->key);
2190 if (r < 0)
2191 return r;
2192 if (r > 0)
2193 continue;
2194
2195 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2196 if (!ds)
2197 return -ENOMEM;
2198
2199 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).",
2200 t->id, dns_resource_key_name(rr->key));
2201 r = dns_transaction_request_dnssec_rr(t, ds);
2202 if (r < 0)
2203 return r;
2204
2205 break;
2206 }
2207
2208 case DNS_TYPE_DS:
2209 case DNS_TYPE_CNAME:
2210 case DNS_TYPE_DNAME: {
2211 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2212 const char *name;
2213
2214 /* CNAMEs and DNAMEs cannot be located at a
2215 * zone apex, hence ask for the parent SOA for
2216 * unsigned CNAME/DNAME RRs, maybe that's the
2217 * apex. But do all that only if this is
2218 * actually a response to our original
2219 * question.
2220 *
2221 * Similar for DS RRs, which are signed when
2222 * the parent SOA is signed. */
2223
2224 r = dns_transaction_is_primary_response(t, rr);
2225 if (r < 0)
2226 return r;
2227 if (r == 0)
2228 continue;
2229
2230 r = dnssec_has_rrsig(t->answer, rr->key);
2231 if (r < 0)
2232 return r;
2233 if (r > 0)
2234 continue;
2235
2236 r = dns_answer_has_dname_for_cname(t->answer, rr);
2237 if (r < 0)
2238 return r;
2239 if (r > 0)
2240 continue;
2241
2242 name = dns_resource_key_name(rr->key);
2243 r = dns_name_parent(&name);
2244 if (r < 0)
2245 return r;
2246 if (r == 0)
2247 continue;
2248
2249 soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name);
2250 if (!soa)
2251 return -ENOMEM;
2252
2253 log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).",
2254 t->id, dns_resource_key_name(rr->key));
2255 r = dns_transaction_request_dnssec_rr(t, soa);
2256 if (r < 0)
2257 return r;
2258
2259 break;
2260 }
2261
2262 default: {
2263 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2264
2265 /* For other unsigned RRsets (including
2266 * NSEC/NSEC3!), look for proof the zone is
2267 * unsigned, by requesting the SOA RR of the
2268 * zone. However, do so only if they are
2269 * directly relevant to our original
2270 * question. */
2271
2272 r = dns_transaction_is_primary_response(t, rr);
2273 if (r < 0)
2274 return r;
2275 if (r == 0)
2276 continue;
2277
2278 r = dnssec_has_rrsig(t->answer, rr->key);
2279 if (r < 0)
2280 return r;
2281 if (r > 0)
2282 continue;
2283
2284 soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, dns_resource_key_name(rr->key));
2285 if (!soa)
2286 return -ENOMEM;
2287
2288 log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).",
2289 t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr));
2290 r = dns_transaction_request_dnssec_rr(t, soa);
2291 if (r < 0)
2292 return r;
2293 break;
2294 }}
2295 }
2296
2297 /* Above, we requested everything necessary to validate what
2298 * we got. Now, let's request what we need to validate what we
2299 * didn't get... */
2300
2301 r = dns_transaction_has_unsigned_negative_answer(t);
2302 if (r < 0)
2303 return r;
2304 if (r > 0) {
2305 const char *name;
2306 uint16_t type = 0;
2307
2308 name = dns_resource_key_name(t->key);
2309
2310 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2311 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2312 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2313 * though they have further children. If this was a DS request, then it's signed when the parent zone
2314 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2315 * to see if that is signed. */
2316
2317 if (t->key->type == DNS_TYPE_DS) {
2318 r = dns_name_parent(&name);
2319 if (r > 0) {
2320 type = DNS_TYPE_SOA;
2321 log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty DS response).",
2322 t->id, dns_resource_key_name(t->key));
2323 } else
2324 name = NULL;
2325
2326 } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS)) {
2327
2328 type = DNS_TYPE_DS;
2329 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS response).",
2330 t->id, dns_resource_key_name(t->key));
2331
2332 } else {
2333 type = DNS_TYPE_SOA;
2334 log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned empty non-SOA/NS/DS response).",
2335 t->id, dns_resource_key_name(t->key));
2336 }
2337
2338 if (name) {
2339 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2340
2341 soa = dns_resource_key_new(t->key->class, type, name);
2342 if (!soa)
2343 return -ENOMEM;
2344
2345 r = dns_transaction_request_dnssec_rr(t, soa);
2346 if (r < 0)
2347 return r;
2348 }
2349 }
2350
2351 return dns_transaction_dnssec_is_live(t);
2352 }
2353
2354 void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) {
2355 assert(t);
2356 assert(source);
2357
2358 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2359 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2360 the state is VALIDATING however, we should check if we are complete now. */
2361
2362 if (t->state == DNS_TRANSACTION_VALIDATING)
2363 dns_transaction_process_dnssec(t);
2364 }
2365
2366 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) {
2367 DnsResourceRecord *rr;
2368 int ifindex, r;
2369
2370 assert(t);
2371
2372 /* Add all DNSKEY RRs from the answer that are validated by DS
2373 * RRs from the list of validated keys to the list of
2374 * validated keys. */
2375
2376 DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, t->answer) {
2377
2378 r = dnssec_verify_dnskey_by_ds_search(rr, t->validated_keys);
2379 if (r < 0)
2380 return r;
2381 if (r == 0)
2382 continue;
2383
2384 /* If so, the DNSKEY is validated too. */
2385 r = dns_answer_add_extend(&t->validated_keys, rr, ifindex, DNS_ANSWER_AUTHENTICATED);
2386 if (r < 0)
2387 return r;
2388 }
2389
2390 return 0;
2391 }
2392
2393 static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) {
2394 int r;
2395
2396 assert(t);
2397 assert(rr);
2398
2399 /* Checks if the RR we are looking for must be signed with an
2400 * RRSIG. This is used for positive responses. */
2401
2402 if (t->scope->dnssec_mode == DNSSEC_NO)
2403 return false;
2404
2405 if (dns_type_is_pseudo(rr->key->type))
2406 return -EINVAL;
2407
2408 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2409 if (r < 0)
2410 return r;
2411 if (r > 0)
2412 return false;
2413
2414 switch (rr->key->type) {
2415
2416 case DNS_TYPE_RRSIG:
2417 /* RRSIGs are the signatures themselves, they need no signing. */
2418 return false;
2419
2420 case DNS_TYPE_SOA:
2421 case DNS_TYPE_NS: {
2422 DnsTransaction *dt;
2423 Iterator i;
2424
2425 /* For SOA or NS RRs we look for a matching DS transaction */
2426
2427 SET_FOREACH(dt, t->dnssec_transactions, i) {
2428
2429 if (dt->key->class != rr->key->class)
2430 continue;
2431 if (dt->key->type != DNS_TYPE_DS)
2432 continue;
2433
2434 r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key));
2435 if (r < 0)
2436 return r;
2437 if (r == 0)
2438 continue;
2439
2440 /* We found a DS transactions for the SOA/NS
2441 * RRs we are looking at. If it discovered signed DS
2442 * RRs, then we need to be signed, too. */
2443
2444 if (!dt->answer_authenticated)
2445 return false;
2446
2447 return dns_answer_match_key(dt->answer, dt->key, NULL);
2448 }
2449
2450 /* We found nothing that proves this is safe to leave
2451 * this unauthenticated, hence ask inist on
2452 * authentication. */
2453 return true;
2454 }
2455
2456 case DNS_TYPE_DS:
2457 case DNS_TYPE_CNAME:
2458 case DNS_TYPE_DNAME: {
2459 const char *parent = NULL;
2460 DnsTransaction *dt;
2461 Iterator i;
2462
2463 /*
2464 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2465 *
2466 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2467 */
2468
2469 SET_FOREACH(dt, t->dnssec_transactions, i) {
2470
2471 if (dt->key->class != rr->key->class)
2472 continue;
2473 if (dt->key->type != DNS_TYPE_SOA)
2474 continue;
2475
2476 if (!parent) {
2477 parent = dns_resource_key_name(rr->key);
2478 r = dns_name_parent(&parent);
2479 if (r < 0)
2480 return r;
2481 if (r == 0) {
2482 if (rr->key->type == DNS_TYPE_DS)
2483 return true;
2484
2485 /* A CNAME/DNAME without a parent? That's sooo weird. */
2486 log_debug("Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id);
2487 return -EBADMSG;
2488 }
2489 }
2490
2491 r = dns_name_equal(dns_resource_key_name(dt->key), parent);
2492 if (r < 0)
2493 return r;
2494 if (r == 0)
2495 continue;
2496
2497 return t->answer_authenticated;
2498 }
2499
2500 return true;
2501 }
2502
2503 default: {
2504 DnsTransaction *dt;
2505 Iterator i;
2506
2507 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2508
2509 SET_FOREACH(dt, t->dnssec_transactions, i) {
2510
2511 if (dt->key->class != rr->key->class)
2512 continue;
2513 if (dt->key->type != DNS_TYPE_SOA)
2514 continue;
2515
2516 r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key));
2517 if (r < 0)
2518 return r;
2519 if (r == 0)
2520 continue;
2521
2522 /* We found the transaction that was supposed to find
2523 * the SOA RR for us. It was successful, but found no
2524 * RR for us. This means we are not at a zone cut. In
2525 * this case, we require authentication if the SOA
2526 * lookup was authenticated too. */
2527 return t->answer_authenticated;
2528 }
2529
2530 return true;
2531 }}
2532 }
2533
2534 static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) {
2535 DnsTransaction *dt;
2536 const char *tld;
2537 Iterator i;
2538 int r;
2539
2540 /* If DNSSEC downgrade mode is on, checks whether the
2541 * specified RR is one level below a TLD we have proven not to
2542 * exist. In such a case we assume that this is a private
2543 * domain, and permit it.
2544 *
2545 * This detects cases like the Fritz!Box router networks. Each
2546 * Fritz!Box router serves a private "fritz.box" zone, in the
2547 * non-existing TLD "box". Requests for the "fritz.box" domain
2548 * are served by the router itself, while requests for the
2549 * "box" domain will result in NXDOMAIN.
2550 *
2551 * Note that this logic is unable to detect cases where a
2552 * router serves a private DNS zone directly under
2553 * non-existing TLD. In such a case we cannot detect whether
2554 * the TLD is supposed to exist or not, as all requests we
2555 * make for it will be answered by the router's zone, and not
2556 * by the root zone. */
2557
2558 assert(t);
2559
2560 if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE)
2561 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2562
2563 tld = dns_resource_key_name(key);
2564 r = dns_name_parent(&tld);
2565 if (r < 0)
2566 return r;
2567 if (r == 0)
2568 return false; /* Already the root domain */
2569
2570 if (!dns_name_is_single_label(tld))
2571 return false;
2572
2573 SET_FOREACH(dt, t->dnssec_transactions, i) {
2574
2575 if (dt->key->class != key->class)
2576 continue;
2577
2578 r = dns_name_equal(dns_resource_key_name(dt->key), tld);
2579 if (r < 0)
2580 return r;
2581 if (r == 0)
2582 continue;
2583
2584 /* We found an auxiliary lookup we did for the TLD. If
2585 * that returned with NXDOMAIN, we know the TLD didn't
2586 * exist, and hence this might be a private zone. */
2587
2588 return dt->answer_rcode == DNS_RCODE_NXDOMAIN;
2589 }
2590
2591 return false;
2592 }
2593
2594 static int dns_transaction_requires_nsec(DnsTransaction *t) {
2595 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
2596 DnsTransaction *dt;
2597 const char *name;
2598 uint16_t type = 0;
2599 Iterator i;
2600 int r;
2601
2602 assert(t);
2603
2604 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2605 * this negative reply */
2606
2607 if (t->scope->dnssec_mode == DNSSEC_NO)
2608 return false;
2609
2610 if (dns_type_is_pseudo(t->key->type))
2611 return -EINVAL;
2612
2613 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key));
2614 if (r < 0)
2615 return r;
2616 if (r > 0)
2617 return false;
2618
2619 r = dns_transaction_in_private_tld(t, t->key);
2620 if (r < 0)
2621 return r;
2622 if (r > 0) {
2623 /* The lookup is from a TLD that is proven not to
2624 * exist, and we are in downgrade mode, hence ignore
2625 * that fact that we didn't get any NSEC RRs. */
2626
2627 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2628 dns_resource_key_to_string(t->key, key_str, sizeof key_str));
2629 return false;
2630 }
2631
2632 name = dns_resource_key_name(t->key);
2633
2634 if (t->key->type == DNS_TYPE_DS) {
2635
2636 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2637 * hence check the parent SOA in this case. */
2638
2639 r = dns_name_parent(&name);
2640 if (r < 0)
2641 return r;
2642 if (r == 0)
2643 return true;
2644
2645 type = DNS_TYPE_SOA;
2646
2647 } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS))
2648 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2649 type = DNS_TYPE_DS;
2650 else
2651 /* For all other negative replies, check for the SOA lookup */
2652 type = DNS_TYPE_SOA;
2653
2654 /* For all other RRs we check the SOA on the same level to see
2655 * if it's signed. */
2656
2657 SET_FOREACH(dt, t->dnssec_transactions, i) {
2658
2659 if (dt->key->class != t->key->class)
2660 continue;
2661 if (dt->key->type != type)
2662 continue;
2663
2664 r = dns_name_equal(dns_resource_key_name(dt->key), name);
2665 if (r < 0)
2666 return r;
2667 if (r == 0)
2668 continue;
2669
2670 return dt->answer_authenticated;
2671 }
2672
2673 /* If in doubt, require NSEC/NSEC3 */
2674 return true;
2675 }
2676
2677 static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) {
2678 DnsResourceRecord *rrsig;
2679 bool found = false;
2680 int r;
2681
2682 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2683 * the specified RRset is authenticated (i.e. has a matching
2684 * DS RR). */
2685
2686 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2687 if (r < 0)
2688 return r;
2689 if (r > 0)
2690 return false;
2691
2692 DNS_ANSWER_FOREACH(rrsig, t->answer) {
2693 DnsTransaction *dt;
2694 Iterator i;
2695
2696 r = dnssec_key_match_rrsig(rr->key, rrsig);
2697 if (r < 0)
2698 return r;
2699 if (r == 0)
2700 continue;
2701
2702 SET_FOREACH(dt, t->dnssec_transactions, i) {
2703
2704 if (dt->key->class != rr->key->class)
2705 continue;
2706
2707 if (dt->key->type == DNS_TYPE_DNSKEY) {
2708
2709 r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer);
2710 if (r < 0)
2711 return r;
2712 if (r == 0)
2713 continue;
2714
2715 /* OK, we found an auxiliary DNSKEY
2716 * lookup. If that lookup is
2717 * authenticated, report this. */
2718
2719 if (dt->answer_authenticated)
2720 return true;
2721
2722 found = true;
2723
2724 } else if (dt->key->type == DNS_TYPE_DS) {
2725
2726 r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer);
2727 if (r < 0)
2728 return r;
2729 if (r == 0)
2730 continue;
2731
2732 /* OK, we found an auxiliary DS
2733 * lookup. If that lookup is
2734 * authenticated and non-zero, we
2735 * won! */
2736
2737 if (!dt->answer_authenticated)
2738 return false;
2739
2740 return dns_answer_match_key(dt->answer, dt->key, NULL);
2741 }
2742 }
2743 }
2744
2745 return found ? false : -ENXIO;
2746 }
2747
2748 static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) {
2749 assert(t);
2750 assert(rr);
2751
2752 /* We know that the root domain is signed, hence if it appears
2753 * not to be signed, there's a problem with the DNS server */
2754
2755 return rr->key->class == DNS_CLASS_IN &&
2756 dns_name_is_root(dns_resource_key_name(rr->key));
2757 }
2758
2759 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) {
2760 DnsResourceRecord *rr;
2761 int r;
2762
2763 assert(t);
2764
2765 /* Maybe warn the user that we encountered a revoked DNSKEY
2766 * for a key from our trust anchor. Note that we don't care
2767 * whether the DNSKEY can be authenticated or not. It's
2768 * sufficient if it is self-signed. */
2769
2770 DNS_ANSWER_FOREACH(rr, t->answer) {
2771 r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer);
2772 if (r < 0)
2773 return r;
2774 }
2775
2776 return 0;
2777 }
2778
2779 static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) {
2780 bool changed;
2781 int r;
2782
2783 assert(t);
2784
2785 /* Removes all DNSKEY/DS objects from t->validated_keys that
2786 * our trust anchors database considers revoked. */
2787
2788 do {
2789 DnsResourceRecord *rr;
2790
2791 changed = false;
2792
2793 DNS_ANSWER_FOREACH(rr, t->validated_keys) {
2794 r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr);
2795 if (r < 0)
2796 return r;
2797 if (r > 0) {
2798 r = dns_answer_remove_by_rr(&t->validated_keys, rr);
2799 if (r < 0)
2800 return r;
2801
2802 assert(r > 0);
2803 changed = true;
2804 break;
2805 }
2806 }
2807 } while (changed);
2808
2809 return 0;
2810 }
2811
2812 static int dns_transaction_copy_validated(DnsTransaction *t) {
2813 DnsTransaction *dt;
2814 Iterator i;
2815 int r;
2816
2817 assert(t);
2818
2819 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2820
2821 SET_FOREACH(dt, t->dnssec_transactions, i) {
2822
2823 if (DNS_TRANSACTION_IS_LIVE(dt->state))
2824 continue;
2825
2826 if (!dt->answer_authenticated)
2827 continue;
2828
2829 r = dns_answer_extend(&t->validated_keys, dt->answer);
2830 if (r < 0)
2831 return r;
2832 }
2833
2834 return 0;
2835 }
2836
2837 typedef enum {
2838 DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */
2839 DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */
2840 DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */
2841 } Phase;
2842
2843 static int dnssec_validate_records(
2844 DnsTransaction *t,
2845 Phase phase,
2846 bool *have_nsec,
2847 DnsAnswer **validated) {
2848
2849 DnsResourceRecord *rr;
2850 int r;
2851
2852 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2853
2854 DNS_ANSWER_FOREACH(rr, t->answer) {
2855 DnsResourceRecord *rrsig = NULL;
2856 DnssecResult result;
2857
2858 switch (rr->key->type) {
2859 case DNS_TYPE_RRSIG:
2860 continue;
2861
2862 case DNS_TYPE_DNSKEY:
2863 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2864 if (phase == DNSSEC_PHASE_NSEC)
2865 continue;
2866 break;
2867
2868 case DNS_TYPE_NSEC:
2869 case DNS_TYPE_NSEC3:
2870 *have_nsec = true;
2871
2872 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2873 if (phase == DNSSEC_PHASE_DNSKEY)
2874 continue;
2875 break;
2876
2877 default:
2878 /* We validate all other RRs only in the ALL phases */
2879 if (phase != DNSSEC_PHASE_ALL)
2880 continue;
2881 }
2882
2883 r = dnssec_verify_rrset_search(t->answer, rr->key, t->validated_keys, USEC_INFINITY, &result, &rrsig);
2884 if (r < 0)
2885 return r;
2886
2887 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result));
2888
2889 if (result == DNSSEC_VALIDATED) {
2890
2891 if (rr->key->type == DNS_TYPE_DNSKEY) {
2892 /* If we just validated a DNSKEY RRset, then let's add these keys to
2893 * the set of validated keys for this transaction. */
2894
2895 r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED);
2896 if (r < 0)
2897 return r;
2898
2899 /* Some of the DNSKEYs we just added might already have been revoked,
2900 * remove them again in that case. */
2901 r = dns_transaction_invalidate_revoked_keys(t);
2902 if (r < 0)
2903 return r;
2904 }
2905
2906 /* Add the validated RRset to the new list of validated
2907 * RRsets, and remove it from the unvalidated RRsets.
2908 * We mark the RRset as authenticated and cacheable. */
2909 r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE);
2910 if (r < 0)
2911 return r;
2912
2913 manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key);
2914
2915 /* Exit the loop, we dropped something from the answer, start from the beginning */
2916 return 1;
2917 }
2918
2919 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2920 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2921 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2922 if (phase != DNSSEC_PHASE_ALL)
2923 continue;
2924
2925 if (result == DNSSEC_VALIDATED_WILDCARD) {
2926 bool authenticated = false;
2927 const char *source;
2928
2929 /* This RRset validated, but as a wildcard. This means we need
2930 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
2931
2932 /* First step, determine the source of synthesis */
2933 r = dns_resource_record_source(rrsig, &source);
2934 if (r < 0)
2935 return r;
2936
2937 r = dnssec_test_positive_wildcard(*validated,
2938 dns_resource_key_name(rr->key),
2939 source,
2940 rrsig->rrsig.signer,
2941 &authenticated);
2942
2943 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2944 if (r == 0)
2945 result = DNSSEC_INVALID;
2946 else {
2947 r = dns_answer_move_by_key(validated, &t->answer, rr->key,
2948 authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0);
2949 if (r < 0)
2950 return r;
2951
2952 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key);
2953
2954 /* Exit the loop, we dropped something from the answer, start from the beginning */
2955 return 1;
2956 }
2957 }
2958
2959 if (result == DNSSEC_NO_SIGNATURE) {
2960 r = dns_transaction_requires_rrsig(t, rr);
2961 if (r < 0)
2962 return r;
2963 if (r == 0) {
2964 /* Data does not require signing. In that case, just copy it over,
2965 * but remember that this is by no means authenticated. */
2966 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
2967 if (r < 0)
2968 return r;
2969
2970 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
2971 return 1;
2972 }
2973
2974 r = dns_transaction_known_signed(t, rr);
2975 if (r < 0)
2976 return r;
2977 if (r > 0) {
2978 /* This is an RR we know has to be signed. If it isn't this means
2979 * the server is not attaching RRSIGs, hence complain. */
2980
2981 dns_server_packet_rrsig_missing(t->server, t->current_feature_level);
2982
2983 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
2984
2985 /* Downgrading is OK? If so, just consider the information unsigned */
2986
2987 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
2988 if (r < 0)
2989 return r;
2990
2991 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
2992 return 1;
2993 }
2994
2995 /* Otherwise, fail */
2996 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
2997 return 0;
2998 }
2999
3000 r = dns_transaction_in_private_tld(t, rr->key);
3001 if (r < 0)
3002 return r;
3003 if (r > 0) {
3004 char s[DNS_RESOURCE_KEY_STRING_MAX];
3005
3006 /* The data is from a TLD that is proven not to exist, and we are in downgrade
3007 * mode, hence ignore the fact that this was not signed. */
3008
3009 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
3010 dns_resource_key_to_string(rr->key, s, sizeof s));
3011
3012 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
3013 if (r < 0)
3014 return r;
3015
3016 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3017 return 1;
3018 }
3019 }
3020
3021 if (IN_SET(result,
3022 DNSSEC_MISSING_KEY,
3023 DNSSEC_SIGNATURE_EXPIRED,
3024 DNSSEC_UNSUPPORTED_ALGORITHM)) {
3025
3026 r = dns_transaction_dnskey_authenticated(t, rr);
3027 if (r < 0 && r != -ENXIO)
3028 return r;
3029 if (r == 0) {
3030 /* The DNSKEY transaction was not authenticated, this means there's
3031 * no DS for this, which means it's OK if no keys are found for this signature. */
3032
3033 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
3034 if (r < 0)
3035 return r;
3036
3037 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3038 return 1;
3039 }
3040 }
3041
3042 r = dns_transaction_is_primary_response(t, rr);
3043 if (r < 0)
3044 return r;
3045 if (r > 0) {
3046 /* Look for a matching DNAME for this CNAME */
3047 r = dns_answer_has_dname_for_cname(t->answer, rr);
3048 if (r < 0)
3049 return r;
3050 if (r == 0) {
3051 /* Also look among the stuff we already validated */
3052 r = dns_answer_has_dname_for_cname(*validated, rr);
3053 if (r < 0)
3054 return r;
3055 }
3056
3057 if (r == 0) {
3058 if (IN_SET(result,
3059 DNSSEC_INVALID,
3060 DNSSEC_SIGNATURE_EXPIRED,
3061 DNSSEC_NO_SIGNATURE))
3062 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key);
3063 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
3064 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key);
3065
3066 /* This is a primary response to our question, and it failed validation.
3067 * That's fatal. */
3068 t->answer_dnssec_result = result;
3069 return 0;
3070 }
3071
3072 /* This is a primary response, but we do have a DNAME RR
3073 * in the RR that can replay this CNAME, hence rely on
3074 * that, and we can remove the CNAME in favour of it. */
3075 }
3076
3077 /* This is just some auxiliary data. Just remove the RRset and continue. */
3078 r = dns_answer_remove_by_key(&t->answer, rr->key);
3079 if (r < 0)
3080 return r;
3081
3082 /* We dropped something from the answer, start from the beginning. */
3083 return 1;
3084 }
3085
3086 return 2; /* Finito. */
3087 }
3088
3089 int dns_transaction_validate_dnssec(DnsTransaction *t) {
3090 _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL;
3091 Phase phase;
3092 DnsAnswerFlags flags;
3093 int r;
3094 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
3095
3096 assert(t);
3097
3098 /* We have now collected all DS and DNSKEY RRs in
3099 * t->validated_keys, let's see which RRs we can now
3100 * authenticate with that. */
3101
3102 if (t->scope->dnssec_mode == DNSSEC_NO)
3103 return 0;
3104
3105 /* Already validated */
3106 if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID)
3107 return 0;
3108
3109 /* Our own stuff needs no validation */
3110 if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) {
3111 t->answer_dnssec_result = DNSSEC_VALIDATED;
3112 t->answer_authenticated = true;
3113 return 0;
3114 }
3115
3116 /* Cached stuff is not affected by validation. */
3117 if (t->answer_source != DNS_TRANSACTION_NETWORK)
3118 return 0;
3119
3120 if (!dns_transaction_dnssec_supported_full(t)) {
3121 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3122 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
3123 log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id);
3124 return 0;
3125 }
3126
3127 log_debug("Validating response from transaction %" PRIu16 " (%s).",
3128 t->id,
3129 dns_resource_key_to_string(t->key, key_str, sizeof key_str));
3130
3131 /* First, see if this response contains any revoked trust
3132 * anchors we care about */
3133 r = dns_transaction_check_revoked_trust_anchors(t);
3134 if (r < 0)
3135 return r;
3136
3137 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3138 r = dns_transaction_copy_validated(t);
3139 if (r < 0)
3140 return r;
3141
3142 /* Second, see if there are DNSKEYs we already know a
3143 * validated DS for. */
3144 r = dns_transaction_validate_dnskey_by_ds(t);
3145 if (r < 0)
3146 return r;
3147
3148 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3149 * anchor says are revoked. After all we might have marked
3150 * some keys revoked above, but they might still be lingering
3151 * in our validated_keys list. */
3152 r = dns_transaction_invalidate_revoked_keys(t);
3153 if (r < 0)
3154 return r;
3155
3156 phase = DNSSEC_PHASE_DNSKEY;
3157 for (;;) {
3158 bool have_nsec = false;
3159
3160 r = dnssec_validate_records(t, phase, &have_nsec, &validated);
3161 if (r <= 0)
3162 return r;
3163
3164 /* Try again as long as we managed to achieve something */
3165 if (r == 1)
3166 continue;
3167
3168 if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) {
3169 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3170 phase = DNSSEC_PHASE_NSEC;
3171 continue;
3172 }
3173
3174 if (phase != DNSSEC_PHASE_ALL) {
3175 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3176 * Note that in this third phase we start to remove RRs we couldn't validate. */
3177 phase = DNSSEC_PHASE_ALL;
3178 continue;
3179 }
3180
3181 /* We're done */
3182 break;
3183 }
3184
3185 dns_answer_unref(t->answer);
3186 t->answer = TAKE_PTR(validated);
3187
3188 /* At this point the answer only contains validated
3189 * RRsets. Now, let's see if it actually answers the question
3190 * we asked. If so, great! If it doesn't, then see if
3191 * NSEC/NSEC3 can prove this. */
3192 r = dns_transaction_has_positive_answer(t, &flags);
3193 if (r > 0) {
3194 /* Yes, it answers the question! */
3195
3196 if (flags & DNS_ANSWER_AUTHENTICATED) {
3197 /* The answer is fully authenticated, yay. */
3198 t->answer_dnssec_result = DNSSEC_VALIDATED;
3199 t->answer_rcode = DNS_RCODE_SUCCESS;
3200 t->answer_authenticated = true;
3201 } else {
3202 /* The answer is not fully authenticated. */
3203 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3204 t->answer_authenticated = false;
3205 }
3206
3207 } else if (r == 0) {
3208 DnssecNsecResult nr;
3209 bool authenticated = false;
3210
3211 /* Bummer! Let's check NSEC/NSEC3 */
3212 r = dnssec_nsec_test(t->answer, t->key, &nr, &authenticated, &t->answer_nsec_ttl);
3213 if (r < 0)
3214 return r;
3215
3216 switch (nr) {
3217
3218 case DNSSEC_NSEC_NXDOMAIN:
3219 /* NSEC proves the domain doesn't exist. Very good. */
3220 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3221 t->answer_dnssec_result = DNSSEC_VALIDATED;
3222 t->answer_rcode = DNS_RCODE_NXDOMAIN;
3223 t->answer_authenticated = authenticated;
3224
3225 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key);
3226 break;
3227
3228 case DNSSEC_NSEC_NODATA:
3229 /* NSEC proves that there's no data here, very good. */
3230 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3231 t->answer_dnssec_result = DNSSEC_VALIDATED;
3232 t->answer_rcode = DNS_RCODE_SUCCESS;
3233 t->answer_authenticated = authenticated;
3234
3235 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key);
3236 break;
3237
3238 case DNSSEC_NSEC_OPTOUT:
3239 /* NSEC3 says the data might not be signed */
3240 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3241 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3242 t->answer_authenticated = false;
3243
3244 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key);
3245 break;
3246
3247 case DNSSEC_NSEC_NO_RR:
3248 /* No NSEC data? Bummer! */
3249
3250 r = dns_transaction_requires_nsec(t);
3251 if (r < 0)
3252 return r;
3253 if (r > 0) {
3254 t->answer_dnssec_result = DNSSEC_NO_SIGNATURE;
3255 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key);
3256 } else {
3257 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3258 t->answer_authenticated = false;
3259 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key);
3260 }
3261
3262 break;
3263
3264 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM:
3265 /* We don't know the NSEC3 algorithm used? */
3266 t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM;
3267 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, t->key);
3268 break;
3269
3270 case DNSSEC_NSEC_FOUND:
3271 case DNSSEC_NSEC_CNAME:
3272 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3273 t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH;
3274 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key);
3275 break;
3276
3277 default:
3278 assert_not_reached("Unexpected NSEC result.");
3279 }
3280 }
3281
3282 return 1;
3283 }
3284
3285 static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = {
3286 [DNS_TRANSACTION_NULL] = "null",
3287 [DNS_TRANSACTION_PENDING] = "pending",
3288 [DNS_TRANSACTION_VALIDATING] = "validating",
3289 [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure",
3290 [DNS_TRANSACTION_SUCCESS] = "success",
3291 [DNS_TRANSACTION_NO_SERVERS] = "no-servers",
3292 [DNS_TRANSACTION_TIMEOUT] = "timeout",
3293 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached",
3294 [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply",
3295 [DNS_TRANSACTION_ERRNO] = "errno",
3296 [DNS_TRANSACTION_ABORTED] = "aborted",
3297 [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed",
3298 [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor",
3299 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported",
3300 [DNS_TRANSACTION_NETWORK_DOWN] = "network-down",
3301 [DNS_TRANSACTION_NOT_FOUND] = "not-found",
3302 };
3303 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState);
3304
3305 static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = {
3306 [DNS_TRANSACTION_NETWORK] = "network",
3307 [DNS_TRANSACTION_CACHE] = "cache",
3308 [DNS_TRANSACTION_ZONE] = "zone",
3309 [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor",
3310 };
3311 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource);
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