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Merge pull request #4522 from lucaswerkmeister/unescape-template
[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 DnsTransaction *t, *n;
522 int r = 0;
523
524 /* Do not let new transactions use this stream */
525 if (s->server && s->server->stream == s)
526 s->server->stream = dns_stream_unref(s->server->stream);
527
528 if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) {
529 usec_t usec;
530
531 log_debug_errno(error, "Connection failure for DNS TCP stream: %m");
532
533 if (s->transactions) {
534 t = s->transactions;
535 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
536 dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level);
537 }
538 }
539
540 LIST_FOREACH_SAFE(transactions_by_stream, t, n, s->transactions)
541 if (error != 0)
542 on_transaction_stream_error(t, error);
543 else if (DNS_PACKET_ID(s->read_packet) == t->id)
544 /* As each transaction have a unique id the return code is only set once */
545 r = dns_transaction_on_stream_packet(t, s->read_packet);
546
547 return r;
548 }
549
550 static int dns_stream_on_packet(DnsStream *s) {
551 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
552 int r = 0;
553 DnsTransaction *t;
554
555 /* Take ownership of packet to be able to receive new packets */
556 p = TAKE_PTR(s->read_packet);
557 s->n_read = 0;
558
559 t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
560
561 /* Ignore incorrect transaction id as transaction can have been canceled */
562 if (t)
563 r = dns_transaction_on_stream_packet(t, p);
564 else {
565 if (dns_packet_validate_reply(p) <= 0) {
566 log_debug("Invalid TCP reply packet.");
567 on_stream_complete(s, 0);
568 }
569 return 0;
570 }
571
572 return r;
573 }
574
575 static int dns_transaction_emit_tcp(DnsTransaction *t) {
576 _cleanup_close_ int fd = -1;
577 _cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
578 union sockaddr_union sa;
579 int r;
580 #if ENABLE_DNS_OVER_TLS
581 gnutls_session_t gs;
582 #endif
583
584 assert(t);
585
586 dns_transaction_close_connection(t);
587
588 switch (t->scope->protocol) {
589
590 case DNS_PROTOCOL_DNS:
591 r = dns_transaction_pick_server(t);
592 if (r < 0)
593 return r;
594
595 if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type))
596 return -EOPNOTSUPP;
597
598 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
599 if (r < 0)
600 return r;
601
602 if (t->server->stream && (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) == t->server->stream->encrypted))
603 s = dns_stream_ref(t->server->stream);
604 else
605 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);
606
607 break;
608
609 case DNS_PROTOCOL_LLMNR:
610 /* When we already received a reply to this (but it was truncated), send to its sender address */
611 if (t->received)
612 fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port, &sa);
613 else {
614 union in_addr_union address;
615 int family = AF_UNSPEC;
616
617 /* Otherwise, try to talk to the owner of a
618 * the IP address, in case this is a reverse
619 * PTR lookup */
620
621 r = dns_name_address(dns_resource_key_name(t->key), &family, &address);
622 if (r < 0)
623 return r;
624 if (r == 0)
625 return -EINVAL;
626 if (family != t->scope->family)
627 return -ESRCH;
628
629 fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT, &sa);
630 }
631
632 break;
633
634 default:
635 return -EAFNOSUPPORT;
636 }
637
638 if (!s) {
639 if (fd < 0)
640 return fd;
641
642 r = dns_stream_new(t->scope->manager, &s, t->scope->protocol, fd, &sa);
643 if (r < 0)
644 return r;
645
646 fd = -1;
647
648 if (t->server) {
649 dns_stream_unref(t->server->stream);
650 t->server->stream = dns_stream_ref(s);
651 s->server = dns_server_ref(t->server);
652 }
653
654 #if ENABLE_DNS_OVER_TLS
655 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) {
656 assert(t->server);
657
658 r = gnutls_init(&gs, GNUTLS_CLIENT | GNUTLS_ENABLE_FALSE_START | GNUTLS_NONBLOCK);
659 if (r < 0)
660 return r;
661
662 /* As DNS-over-TLS is a recent protocol, older TLS versions can be disabled */
663 r = gnutls_priority_set_direct(gs, "NORMAL:-VERS-ALL:+VERS-TLS1.2", NULL);
664 if (r < 0)
665 return r;
666
667 r = gnutls_credentials_set(gs, GNUTLS_CRD_CERTIFICATE, t->server->tls_cert_cred);
668 if (r < 0)
669 return r;
670
671 if (t->server->tls_session_data.size > 0)
672 gnutls_session_set_data(gs, t->server->tls_session_data.data, t->server->tls_session_data.size);
673
674 gnutls_handshake_set_timeout(gs, GNUTLS_DEFAULT_HANDSHAKE_TIMEOUT);
675
676 r = dns_stream_connect_tls(s, gs);
677 if (r < 0)
678 return r;
679 }
680 #endif
681
682 s->on_connection = on_stream_connection;
683 s->complete = on_stream_complete;
684 s->on_packet = dns_stream_on_packet;
685
686 /* The interface index is difficult to determine if we are
687 * connecting to the local host, hence fill this in right away
688 * instead of determining it from the socket */
689 s->ifindex = dns_scope_ifindex(t->scope);
690 }
691
692 t->stream = TAKE_PTR(s);
693 LIST_PREPEND(transactions_by_stream, t->stream->transactions, t);
694
695 r = dns_stream_write_packet(t->stream, t->sent);
696 if (r < 0) {
697 dns_transaction_close_connection(t);
698 return r;
699 }
700
701 dns_transaction_reset_answer(t);
702
703 t->tried_stream = true;
704
705 return 0;
706 }
707
708 static void dns_transaction_cache_answer(DnsTransaction *t) {
709 assert(t);
710
711 /* For mDNS we cache whenever we get the packet, rather than
712 * in each transaction. */
713 if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR))
714 return;
715
716 /* Caching disabled? */
717 if (!t->scope->manager->enable_cache)
718 return;
719
720 /* We never cache if this packet is from the local host, under
721 * the assumption that a locally running DNS server would
722 * cache this anyway, and probably knows better when to flush
723 * the cache then we could. */
724 if (!DNS_PACKET_SHALL_CACHE(t->received))
725 return;
726
727 dns_cache_put(&t->scope->cache,
728 t->key,
729 t->answer_rcode,
730 t->answer,
731 t->answer_authenticated,
732 t->answer_nsec_ttl,
733 0,
734 t->received->family,
735 &t->received->sender);
736 }
737
738 static bool dns_transaction_dnssec_is_live(DnsTransaction *t) {
739 DnsTransaction *dt;
740 Iterator i;
741
742 assert(t);
743
744 SET_FOREACH(dt, t->dnssec_transactions, i)
745 if (DNS_TRANSACTION_IS_LIVE(dt->state))
746 return true;
747
748 return false;
749 }
750
751 static int dns_transaction_dnssec_ready(DnsTransaction *t) {
752 DnsTransaction *dt;
753 Iterator i;
754
755 assert(t);
756
757 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
758 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
759
760 SET_FOREACH(dt, t->dnssec_transactions, i) {
761
762 switch (dt->state) {
763
764 case DNS_TRANSACTION_NULL:
765 case DNS_TRANSACTION_PENDING:
766 case DNS_TRANSACTION_VALIDATING:
767 /* Still ongoing */
768 return 0;
769
770 case DNS_TRANSACTION_RCODE_FAILURE:
771 if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) {
772 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt->answer_rcode));
773 goto fail;
774 }
775
776 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
777 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
778 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
779 * RRs to make unsigned proofs. */
780
781 case DNS_TRANSACTION_SUCCESS:
782 /* All good. */
783 break;
784
785 case DNS_TRANSACTION_DNSSEC_FAILED:
786 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
787 * validationr result */
788
789 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt->answer_dnssec_result));
790 t->answer_dnssec_result = dt->answer_dnssec_result; /* Copy error code over */
791 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
792 return 0;
793
794 default:
795 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state));
796 goto fail;
797 }
798 }
799
800 /* All is ready, we can go and validate */
801 return 1;
802
803 fail:
804 t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY;
805 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
806 return 0;
807 }
808
809 static void dns_transaction_process_dnssec(DnsTransaction *t) {
810 int r;
811
812 assert(t);
813
814 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
815 r = dns_transaction_dnssec_ready(t);
816 if (r < 0)
817 goto fail;
818 if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
819 return;
820
821 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
822 * restart the lookup immediately. */
823 r = dns_transaction_maybe_restart(t);
824 if (r < 0)
825 goto fail;
826 if (r > 0) /* Transaction got restarted... */
827 return;
828
829 /* All our auxiliary DNSSEC transactions are complete now. Try
830 * to validate our RRset now. */
831 r = dns_transaction_validate_dnssec(t);
832 if (r == -EBADMSG) {
833 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
834 return;
835 }
836 if (r < 0)
837 goto fail;
838
839 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER &&
840 t->scope->dnssec_mode == DNSSEC_YES) {
841
842 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
843 * that works. */
844
845 if (t->n_picked_servers < dns_scope_get_n_dns_servers(t->scope)) {
846 /* We tried fewer servers on this transaction than we know, let's try another one then */
847 dns_transaction_retry(t, true);
848 return;
849 }
850
851 /* OK, let's give up, apparently all servers we tried didn't work. */
852 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
853 return;
854 }
855
856 if (!IN_SET(t->answer_dnssec_result,
857 _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */
858 DNSSEC_VALIDATED, /* Answer is signed and validated successfully */
859 DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */
860 DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
861 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
862 return;
863 }
864
865 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER)
866 dns_server_warn_downgrade(t->server);
867
868 dns_transaction_cache_answer(t);
869
870 if (t->answer_rcode == DNS_RCODE_SUCCESS)
871 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
872 else
873 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
874
875 return;
876
877 fail:
878 t->answer_errno = -r;
879 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
880 }
881
882 static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) {
883 int r;
884
885 assert(t);
886
887 /* Checks whether the answer is positive, i.e. either a direct
888 * answer to the question, or a CNAME/DNAME for it */
889
890 r = dns_answer_match_key(t->answer, t->key, flags);
891 if (r != 0)
892 return r;
893
894 r = dns_answer_find_cname_or_dname(t->answer, t->key, NULL, flags);
895 if (r != 0)
896 return r;
897
898 return false;
899 }
900
901 static int dns_transaction_fix_rcode(DnsTransaction *t) {
902 int r;
903
904 assert(t);
905
906 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
907 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
908 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
909 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
910 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
911 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
912 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
913 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
914 * incomplete CNAME/DNAME chain.
915 *
916 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
917 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
918 * lookup. */
919
920 if (t->answer_rcode != DNS_RCODE_NXDOMAIN)
921 return 0;
922
923 r = dns_transaction_has_positive_answer(t, NULL);
924 if (r <= 0)
925 return r;
926
927 t->answer_rcode = DNS_RCODE_SUCCESS;
928 return 0;
929 }
930
931 void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
932 usec_t ts;
933 int r;
934
935 assert(t);
936 assert(p);
937 assert(t->scope);
938 assert(t->scope->manager);
939
940 if (t->state != DNS_TRANSACTION_PENDING)
941 return;
942
943 /* Note that this call might invalidate the query. Callers
944 * should hence not attempt to access the query or transaction
945 * after calling this function. */
946
947 log_debug("Processing incoming packet on transaction %" PRIu16" (rcode=%s).",
948 t->id, dns_rcode_to_string(DNS_PACKET_RCODE(p)));
949
950 switch (t->scope->protocol) {
951
952 case DNS_PROTOCOL_LLMNR:
953 /* For LLMNR we will not accept any packets from other interfaces */
954
955 if (p->ifindex != dns_scope_ifindex(t->scope))
956 return;
957
958 if (p->family != t->scope->family)
959 return;
960
961 /* Tentative packets are not full responses but still
962 * useful for identifying uniqueness conflicts during
963 * probing. */
964 if (DNS_PACKET_LLMNR_T(p)) {
965 dns_transaction_tentative(t, p);
966 return;
967 }
968
969 break;
970
971 case DNS_PROTOCOL_MDNS:
972 /* For mDNS we will not accept any packets from other interfaces */
973
974 if (p->ifindex != dns_scope_ifindex(t->scope))
975 return;
976
977 if (p->family != t->scope->family)
978 return;
979
980 break;
981
982 case DNS_PROTOCOL_DNS:
983 /* Note that we do not need to verify the
984 * addresses/port numbers of incoming traffic, as we
985 * invoked connect() on our UDP socket in which case
986 * the kernel already does the needed verification for
987 * us. */
988 break;
989
990 default:
991 assert_not_reached("Invalid DNS protocol.");
992 }
993
994 if (t->received != p) {
995 dns_packet_unref(t->received);
996 t->received = dns_packet_ref(p);
997 }
998
999 t->answer_source = DNS_TRANSACTION_NETWORK;
1000
1001 if (p->ipproto == IPPROTO_TCP) {
1002 if (DNS_PACKET_TC(p)) {
1003 /* Truncated via TCP? Somebody must be fucking with us */
1004 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1005 return;
1006 }
1007
1008 if (DNS_PACKET_ID(p) != t->id) {
1009 /* Not the reply to our query? Somebody must be fucking with us */
1010 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1011 return;
1012 }
1013 }
1014
1015 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1016
1017 switch (t->scope->protocol) {
1018
1019 case DNS_PROTOCOL_DNS:
1020 assert(t->server);
1021
1022 if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
1023
1024 /* Request failed, immediately try again with reduced features */
1025
1026 if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) {
1027
1028 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
1029 * this transaction anymore, but let's see if it might make sense to send the request
1030 * to a different DNS server instead. If not let's process the response, and accept the
1031 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
1032 * packet loss, but is not going to give us better rcodes should we actually have
1033 * managed to get them already at UDP level. */
1034
1035 if (t->n_picked_servers < dns_scope_get_n_dns_servers(t->scope)) {
1036 /* We tried fewer servers on this transaction than we know, let's try another one then */
1037 dns_transaction_retry(t, true);
1038 return;
1039 }
1040
1041 /* Give up, accept the rcode */
1042 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
1043 break;
1044 }
1045
1046 /* Reduce this feature level by one and try again. */
1047 switch (t->current_feature_level) {
1048 case DNS_SERVER_FEATURE_LEVEL_TLS_DO:
1049 t->clamp_feature_level = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN;
1050 break;
1051 case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN + 1:
1052 /* Skip plain TLS when TLS is not supported */
1053 t->clamp_feature_level = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN - 1;
1054 break;
1055 default:
1056 t->clamp_feature_level = t->current_feature_level - 1;
1057 }
1058
1059 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
1060 dns_rcode_to_string(DNS_PACKET_RCODE(p)),
1061 dns_server_feature_level_to_string(t->clamp_feature_level));
1062
1063 dns_transaction_retry(t, false /* use the same server */);
1064 return;
1065 }
1066
1067 if (DNS_PACKET_RCODE(p) == DNS_RCODE_REFUSED) {
1068 /* This server refused our request? If so, try again, use a different server */
1069 log_debug("Server returned REFUSED, switching servers, and retrying.");
1070 dns_transaction_retry(t, true /* pick a new server */);
1071 return;
1072 }
1073
1074 if (DNS_PACKET_TC(p))
1075 dns_server_packet_truncated(t->server, t->current_feature_level);
1076
1077 break;
1078
1079 case DNS_PROTOCOL_LLMNR:
1080 case DNS_PROTOCOL_MDNS:
1081 dns_scope_packet_received(t->scope, ts - t->start_usec);
1082 break;
1083
1084 default:
1085 assert_not_reached("Invalid DNS protocol.");
1086 }
1087
1088 if (DNS_PACKET_TC(p)) {
1089
1090 /* Truncated packets for mDNS are not allowed. Give up immediately. */
1091 if (t->scope->protocol == DNS_PROTOCOL_MDNS) {
1092 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1093 return;
1094 }
1095
1096 log_debug("Reply truncated, retrying via TCP.");
1097
1098 /* Response was truncated, let's try again with good old TCP */
1099 r = dns_transaction_emit_tcp(t);
1100 if (r == -ESRCH) {
1101 /* No servers found? Damn! */
1102 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
1103 return;
1104 }
1105 if (r == -EOPNOTSUPP) {
1106 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1107 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
1108 return;
1109 }
1110 if (r < 0) {
1111 /* On LLMNR, if we cannot connect to the host,
1112 * we immediately give up */
1113 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1114 goto fail;
1115
1116 /* On DNS, couldn't send? Try immediately again, with a new server */
1117 dns_transaction_retry(t, true);
1118 }
1119
1120 return;
1121 }
1122
1123 /* After the superficial checks, actually parse the message. */
1124 r = dns_packet_extract(p);
1125 if (r < 0) {
1126 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1127 return;
1128 }
1129
1130 if (t->server) {
1131 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1132 * rcode and subsequently downgraded the protocol */
1133
1134 if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) &&
1135 t->clamp_feature_level != _DNS_SERVER_FEATURE_LEVEL_INVALID)
1136 dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level);
1137
1138 /* Report that the OPT RR was missing */
1139 if (!p->opt)
1140 dns_server_packet_bad_opt(t->server, t->current_feature_level);
1141
1142 /* Report that we successfully received a packet */
1143 dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, p->size);
1144 }
1145
1146 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1147 r = dns_transaction_maybe_restart(t);
1148 if (r < 0)
1149 goto fail;
1150 if (r > 0) /* Transaction got restarted... */
1151 return;
1152
1153 if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
1154
1155 /* When dealing with protocols other than mDNS only consider responses with
1156 * equivalent query section to the request. For mDNS this check doesn't make
1157 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1158 * contain any questions in the Question Section". */
1159 if (t->scope->protocol != DNS_PROTOCOL_MDNS) {
1160 r = dns_packet_is_reply_for(p, t->key);
1161 if (r < 0)
1162 goto fail;
1163 if (r == 0) {
1164 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1165 return;
1166 }
1167 }
1168
1169 /* Install the answer as answer to the transaction */
1170 dns_answer_unref(t->answer);
1171 t->answer = dns_answer_ref(p->answer);
1172 t->answer_rcode = DNS_PACKET_RCODE(p);
1173 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
1174 t->answer_authenticated = false;
1175
1176 r = dns_transaction_fix_rcode(t);
1177 if (r < 0)
1178 goto fail;
1179
1180 /* Block GC while starting requests for additional DNSSEC RRs */
1181 t->block_gc++;
1182 r = dns_transaction_request_dnssec_keys(t);
1183 t->block_gc--;
1184
1185 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1186 if (!dns_transaction_gc(t))
1187 return;
1188
1189 /* Requesting additional keys might have resulted in
1190 * this transaction to fail, since the auxiliary
1191 * request failed for some reason. If so, we are not
1192 * in pending state anymore, and we should exit
1193 * quickly. */
1194 if (t->state != DNS_TRANSACTION_PENDING)
1195 return;
1196 if (r < 0)
1197 goto fail;
1198 if (r > 0) {
1199 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1200 t->state = DNS_TRANSACTION_VALIDATING;
1201 dns_transaction_close_connection(t);
1202 dns_transaction_stop_timeout(t);
1203 return;
1204 }
1205 }
1206
1207 dns_transaction_process_dnssec(t);
1208 return;
1209
1210 fail:
1211 t->answer_errno = -r;
1212 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
1213 }
1214
1215 static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
1216 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1217 DnsTransaction *t = userdata;
1218 int r;
1219
1220 assert(t);
1221 assert(t->scope);
1222
1223 r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
1224 if (ERRNO_IS_DISCONNECT(-r)) {
1225 usec_t usec;
1226
1227 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1228 * recvmsg(). Treat this like a lost packet. */
1229
1230 log_debug_errno(r, "Connection failure for DNS UDP packet: %m");
1231 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &usec) >= 0);
1232 dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level);
1233
1234 dns_transaction_retry(t, true);
1235 return 0;
1236 }
1237 if (r < 0) {
1238 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
1239 t->answer_errno = -r;
1240 return 0;
1241 }
1242
1243 r = dns_packet_validate_reply(p);
1244 if (r < 0) {
1245 log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m");
1246 return 0;
1247 }
1248 if (r == 0) {
1249 log_debug("Received inappropriate DNS packet as response, ignoring.");
1250 return 0;
1251 }
1252
1253 if (DNS_PACKET_ID(p) != t->id) {
1254 log_debug("Received packet with incorrect transaction ID, ignoring.");
1255 return 0;
1256 }
1257
1258 dns_transaction_process_reply(t, p);
1259 return 0;
1260 }
1261
1262 static int dns_transaction_emit_udp(DnsTransaction *t) {
1263 int r;
1264
1265 assert(t);
1266
1267 if (t->scope->protocol == DNS_PROTOCOL_DNS) {
1268
1269 r = dns_transaction_pick_server(t);
1270 if (r < 0)
1271 return r;
1272
1273 if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP || DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level))
1274 return -EAGAIN; /* Sorry, can't do UDP, try TCP! */
1275
1276 if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(t->key->type))
1277 return -EOPNOTSUPP;
1278
1279 if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */
1280 int fd;
1281
1282 dns_transaction_close_connection(t);
1283
1284 fd = dns_scope_socket_udp(t->scope, t->server, 53);
1285 if (fd < 0)
1286 return fd;
1287
1288 r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
1289 if (r < 0) {
1290 safe_close(fd);
1291 return r;
1292 }
1293
1294 (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp");
1295 t->dns_udp_fd = fd;
1296 }
1297
1298 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
1299 if (r < 0)
1300 return r;
1301 } else
1302 dns_transaction_close_connection(t);
1303
1304 r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->sent);
1305 if (r < 0)
1306 return r;
1307
1308 dns_transaction_reset_answer(t);
1309
1310 return 0;
1311 }
1312
1313 static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1314 DnsTransaction *t = userdata;
1315
1316 assert(s);
1317 assert(t);
1318
1319 if (!t->initial_jitter_scheduled || t->initial_jitter_elapsed) {
1320 /* Timeout reached? Increase the timeout for the server used */
1321 switch (t->scope->protocol) {
1322
1323 case DNS_PROTOCOL_DNS:
1324 assert(t->server);
1325 dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level);
1326 break;
1327
1328 case DNS_PROTOCOL_LLMNR:
1329 case DNS_PROTOCOL_MDNS:
1330 dns_scope_packet_lost(t->scope, usec - t->start_usec);
1331 break;
1332
1333 default:
1334 assert_not_reached("Invalid DNS protocol.");
1335 }
1336
1337 if (t->initial_jitter_scheduled)
1338 t->initial_jitter_elapsed = true;
1339 }
1340
1341 log_debug("Timeout reached on transaction %" PRIu16 ".", t->id);
1342
1343 dns_transaction_retry(t, true);
1344 return 0;
1345 }
1346
1347 static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
1348 assert(t);
1349 assert(t->scope);
1350
1351 switch (t->scope->protocol) {
1352
1353 case DNS_PROTOCOL_DNS:
1354
1355 /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
1356 * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
1357 * needlessly. */
1358 if (t->stream)
1359 return TRANSACTION_TCP_TIMEOUT_USEC;
1360
1361 return DNS_TIMEOUT_USEC;
1362
1363 case DNS_PROTOCOL_MDNS:
1364 assert(t->n_attempts > 0);
1365 if (t->probing)
1366 return MDNS_PROBING_INTERVAL_USEC;
1367 else
1368 return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
1369
1370 case DNS_PROTOCOL_LLMNR:
1371 return t->scope->resend_timeout;
1372
1373 default:
1374 assert_not_reached("Invalid DNS protocol.");
1375 }
1376 }
1377
1378 static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
1379 int r;
1380
1381 assert(t);
1382
1383 dns_transaction_stop_timeout(t);
1384
1385 if (!dns_scope_network_good(t->scope)) {
1386 dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN);
1387 return 0;
1388 }
1389
1390 if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
1391 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1392 return 0;
1393 }
1394
1395 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) {
1396 /* If we already tried via a stream, then we don't
1397 * retry on LLMNR. See RFC 4795, Section 2.7. */
1398 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1399 return 0;
1400 }
1401
1402 t->n_attempts++;
1403 t->start_usec = ts;
1404
1405 dns_transaction_reset_answer(t);
1406 dns_transaction_flush_dnssec_transactions(t);
1407
1408 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1409 if (t->scope->protocol == DNS_PROTOCOL_DNS) {
1410 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, t->key, &t->answer);
1411 if (r < 0)
1412 return r;
1413 if (r > 0) {
1414 t->answer_rcode = DNS_RCODE_SUCCESS;
1415 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1416 t->answer_authenticated = true;
1417 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1418 return 0;
1419 }
1420
1421 if (dns_name_is_root(dns_resource_key_name(t->key)) &&
1422 t->key->type == DNS_TYPE_DS) {
1423
1424 /* Hmm, this is a request for the root DS? A
1425 * DS RR doesn't exist in the root zone, and
1426 * if our trust anchor didn't know it either,
1427 * this means we cannot do any DNSSEC logic
1428 * anymore. */
1429
1430 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
1431 /* We are in downgrade mode. In this
1432 * case, synthesize an unsigned empty
1433 * response, so that the any lookup
1434 * depending on this one can continue
1435 * assuming there was no DS, and hence
1436 * the root zone was unsigned. */
1437
1438 t->answer_rcode = DNS_RCODE_SUCCESS;
1439 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1440 t->answer_authenticated = false;
1441 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1442 } else
1443 /* If we are not in downgrade mode,
1444 * then fail the lookup, because we
1445 * cannot reasonably answer it. There
1446 * might be DS RRs, but we don't know
1447 * them, and the DNS server won't tell
1448 * them to us (and even if it would,
1449 * we couldn't validate and trust them. */
1450 dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR);
1451
1452 return 0;
1453 }
1454 }
1455
1456 /* Check the zone, but only if this transaction is not used
1457 * for probing or verifying a zone item. */
1458 if (set_isempty(t->notify_zone_items)) {
1459
1460 r = dns_zone_lookup(&t->scope->zone, t->key, dns_scope_ifindex(t->scope), &t->answer, NULL, NULL);
1461 if (r < 0)
1462 return r;
1463 if (r > 0) {
1464 t->answer_rcode = DNS_RCODE_SUCCESS;
1465 t->answer_source = DNS_TRANSACTION_ZONE;
1466 t->answer_authenticated = true;
1467 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1468 return 0;
1469 }
1470 }
1471
1472 /* Check the cache, but only if this transaction is not used
1473 * for probing or verifying a zone item. */
1474 if (set_isempty(t->notify_zone_items)) {
1475
1476 /* Before trying the cache, let's make sure we figured out a
1477 * server to use. Should this cause a change of server this
1478 * might flush the cache. */
1479 (void) dns_scope_get_dns_server(t->scope);
1480
1481 /* Let's then prune all outdated entries */
1482 dns_cache_prune(&t->scope->cache);
1483
1484 r = dns_cache_lookup(&t->scope->cache, t->key, t->clamp_ttl, &t->answer_rcode, &t->answer, &t->answer_authenticated);
1485 if (r < 0)
1486 return r;
1487 if (r > 0) {
1488 t->answer_source = DNS_TRANSACTION_CACHE;
1489 if (t->answer_rcode == DNS_RCODE_SUCCESS)
1490 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1491 else
1492 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
1493 return 0;
1494 }
1495 }
1496
1497 return 1;
1498 }
1499
1500 static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
1501
1502 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1503 bool add_known_answers = false;
1504 DnsTransaction *other;
1505 Iterator i;
1506 DnsResourceKey *tkey;
1507 _cleanup_set_free_ Set *keys = NULL;
1508 unsigned qdcount;
1509 unsigned nscount = 0;
1510 usec_t ts;
1511 int r;
1512
1513 assert(t);
1514 assert(t->scope->protocol == DNS_PROTOCOL_MDNS);
1515
1516 /* Discard any previously prepared packet, so we can start over and coalesce again */
1517 t->sent = dns_packet_unref(t->sent);
1518
1519 r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
1520 if (r < 0)
1521 return r;
1522
1523 r = dns_packet_append_key(p, t->key, 0, NULL);
1524 if (r < 0)
1525 return r;
1526
1527 qdcount = 1;
1528
1529 if (dns_key_is_shared(t->key))
1530 add_known_answers = true;
1531
1532 if (t->key->type == DNS_TYPE_ANY) {
1533 r = set_ensure_allocated(&keys, &dns_resource_key_hash_ops);
1534 if (r < 0)
1535 return r;
1536
1537 r = set_put(keys, t->key);
1538 if (r < 0)
1539 return r;
1540 }
1541
1542 /*
1543 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1544 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1545 * in our current scope, and see whether their timing contraints allow them to be sent.
1546 */
1547
1548 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1549
1550 LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
1551
1552 /* Skip ourselves */
1553 if (other == t)
1554 continue;
1555
1556 if (other->state != DNS_TRANSACTION_PENDING)
1557 continue;
1558
1559 if (other->next_attempt_after > ts)
1560 continue;
1561
1562 if (qdcount >= UINT16_MAX)
1563 break;
1564
1565 r = dns_packet_append_key(p, other->key, 0, NULL);
1566
1567 /*
1568 * If we can't stuff more questions into the packet, just give up.
1569 * One of the 'other' transactions will fire later and take care of the rest.
1570 */
1571 if (r == -EMSGSIZE)
1572 break;
1573
1574 if (r < 0)
1575 return r;
1576
1577 r = dns_transaction_prepare(other, ts);
1578 if (r <= 0)
1579 continue;
1580
1581 ts += transaction_get_resend_timeout(other);
1582
1583 r = sd_event_add_time(
1584 other->scope->manager->event,
1585 &other->timeout_event_source,
1586 clock_boottime_or_monotonic(),
1587 ts, 0,
1588 on_transaction_timeout, other);
1589 if (r < 0)
1590 return r;
1591
1592 (void) sd_event_source_set_description(other->timeout_event_source, "dns-transaction-timeout");
1593
1594 other->state = DNS_TRANSACTION_PENDING;
1595 other->next_attempt_after = ts;
1596
1597 qdcount++;
1598
1599 if (dns_key_is_shared(other->key))
1600 add_known_answers = true;
1601
1602 if (other->key->type == DNS_TYPE_ANY) {
1603 r = set_ensure_allocated(&keys, &dns_resource_key_hash_ops);
1604 if (r < 0)
1605 return r;
1606
1607 r = set_put(keys, other->key);
1608 if (r < 0)
1609 return r;
1610 }
1611 }
1612
1613 DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
1614
1615 /* Append known answer section if we're asking for any shared record */
1616 if (add_known_answers) {
1617 r = dns_cache_export_shared_to_packet(&t->scope->cache, p);
1618 if (r < 0)
1619 return r;
1620 }
1621
1622 SET_FOREACH(tkey, keys, i) {
1623 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1624 bool tentative;
1625
1626 r = dns_zone_lookup(&t->scope->zone, tkey, t->scope->link->ifindex, &answer, NULL, &tentative);
1627 if (r < 0)
1628 return r;
1629
1630 r = dns_packet_append_answer(p, answer);
1631 if (r < 0)
1632 return r;
1633
1634 nscount += dns_answer_size(answer);
1635 }
1636 DNS_PACKET_HEADER(p)->nscount = htobe16(nscount);
1637
1638 t->sent = TAKE_PTR(p);
1639
1640 return 0;
1641 }
1642
1643 static int dns_transaction_make_packet(DnsTransaction *t) {
1644 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1645 int r;
1646
1647 assert(t);
1648
1649 if (t->scope->protocol == DNS_PROTOCOL_MDNS)
1650 return dns_transaction_make_packet_mdns(t);
1651
1652 if (t->sent)
1653 return 0;
1654
1655 r = dns_packet_new_query(&p, t->scope->protocol, 0, t->scope->dnssec_mode != DNSSEC_NO);
1656 if (r < 0)
1657 return r;
1658
1659 r = dns_packet_append_key(p, t->key, 0, NULL);
1660 if (r < 0)
1661 return r;
1662
1663 DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
1664 DNS_PACKET_HEADER(p)->id = t->id;
1665
1666 t->sent = TAKE_PTR(p);
1667
1668 return 0;
1669 }
1670
1671 int dns_transaction_go(DnsTransaction *t) {
1672 usec_t ts;
1673 int r;
1674 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1675
1676 assert(t);
1677
1678 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1679 * now. */
1680
1681 assert_se(sd_event_now(t->scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1682
1683 r = dns_transaction_prepare(t, ts);
1684 if (r <= 0)
1685 return r;
1686
1687 log_debug("Transaction %" PRIu16 " for <%s> scope %s on %s/%s.",
1688 t->id,
1689 dns_resource_key_to_string(t->key, key_str, sizeof key_str),
1690 dns_protocol_to_string(t->scope->protocol),
1691 t->scope->link ? t->scope->link->name : "*",
1692 af_to_name_short(t->scope->family));
1693
1694 if (!t->initial_jitter_scheduled &&
1695 IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
1696 usec_t jitter, accuracy;
1697
1698 /* RFC 4795 Section 2.7 suggests all queries should be
1699 * delayed by a random time from 0 to JITTER_INTERVAL. */
1700
1701 t->initial_jitter_scheduled = true;
1702
1703 random_bytes(&jitter, sizeof(jitter));
1704
1705 switch (t->scope->protocol) {
1706
1707 case DNS_PROTOCOL_LLMNR:
1708 jitter %= LLMNR_JITTER_INTERVAL_USEC;
1709 accuracy = LLMNR_JITTER_INTERVAL_USEC;
1710 break;
1711
1712 case DNS_PROTOCOL_MDNS:
1713 jitter %= MDNS_JITTER_RANGE_USEC;
1714 jitter += MDNS_JITTER_MIN_USEC;
1715 accuracy = MDNS_JITTER_RANGE_USEC;
1716 break;
1717 default:
1718 assert_not_reached("bad protocol");
1719 }
1720
1721 r = sd_event_add_time(
1722 t->scope->manager->event,
1723 &t->timeout_event_source,
1724 clock_boottime_or_monotonic(),
1725 ts + jitter, accuracy,
1726 on_transaction_timeout, t);
1727 if (r < 0)
1728 return r;
1729
1730 (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
1731
1732 t->n_attempts = 0;
1733 t->next_attempt_after = ts;
1734 t->state = DNS_TRANSACTION_PENDING;
1735
1736 log_debug("Delaying %s transaction for " USEC_FMT "us.", dns_protocol_to_string(t->scope->protocol), jitter);
1737 return 0;
1738 }
1739
1740 /* Otherwise, we need to ask the network */
1741 r = dns_transaction_make_packet(t);
1742 if (r < 0)
1743 return r;
1744
1745 if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
1746 (dns_name_endswith(dns_resource_key_name(t->key), "in-addr.arpa") > 0 ||
1747 dns_name_endswith(dns_resource_key_name(t->key), "ip6.arpa") > 0)) {
1748
1749 /* RFC 4795, Section 2.4. says reverse lookups shall
1750 * always be made via TCP on LLMNR */
1751 r = dns_transaction_emit_tcp(t);
1752 } else {
1753 /* Try via UDP, and if that fails due to large size or lack of
1754 * support try via TCP */
1755 r = dns_transaction_emit_udp(t);
1756 if (r == -EMSGSIZE)
1757 log_debug("Sending query via TCP since it is too large.");
1758 else if (r == -EAGAIN)
1759 log_debug("Sending query via TCP since UDP isn't supported.");
1760 if (IN_SET(r, -EMSGSIZE, -EAGAIN))
1761 r = dns_transaction_emit_tcp(t);
1762 }
1763
1764 if (r == -ESRCH) {
1765 /* No servers to send this to? */
1766 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
1767 return 0;
1768 }
1769 if (r == -EOPNOTSUPP) {
1770 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1771 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
1772 return 0;
1773 }
1774 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_DISCONNECT(-r)) {
1775 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1776 * answer this request with this protocol. */
1777 dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND);
1778 return 0;
1779 }
1780 if (r < 0) {
1781 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1782 return r;
1783
1784 /* Couldn't send? Try immediately again, with a new server */
1785 dns_scope_next_dns_server(t->scope);
1786
1787 return dns_transaction_go(t);
1788 }
1789
1790 ts += transaction_get_resend_timeout(t);
1791
1792 r = sd_event_add_time(
1793 t->scope->manager->event,
1794 &t->timeout_event_source,
1795 clock_boottime_or_monotonic(),
1796 ts, 0,
1797 on_transaction_timeout, t);
1798 if (r < 0)
1799 return r;
1800
1801 (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
1802
1803 t->state = DNS_TRANSACTION_PENDING;
1804 t->next_attempt_after = ts;
1805
1806 return 1;
1807 }
1808
1809 static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) {
1810 DnsTransaction *n;
1811 Iterator i;
1812 int r;
1813
1814 assert(t);
1815 assert(aux);
1816
1817 /* Try to find cyclic dependencies between transaction objects */
1818
1819 if (t == aux)
1820 return 1;
1821
1822 SET_FOREACH(n, aux->dnssec_transactions, i) {
1823 r = dns_transaction_find_cyclic(t, n);
1824 if (r != 0)
1825 return r;
1826 }
1827
1828 return 0;
1829 }
1830
1831 static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) {
1832 DnsTransaction *aux;
1833 int r;
1834
1835 assert(t);
1836 assert(ret);
1837 assert(key);
1838
1839 aux = dns_scope_find_transaction(t->scope, key, true);
1840 if (!aux) {
1841 r = dns_transaction_new(&aux, t->scope, key);
1842 if (r < 0)
1843 return r;
1844 } else {
1845 if (set_contains(t->dnssec_transactions, aux)) {
1846 *ret = aux;
1847 return 0;
1848 }
1849
1850 r = dns_transaction_find_cyclic(t, aux);
1851 if (r < 0)
1852 return r;
1853 if (r > 0) {
1854 char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX];
1855
1856 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).",
1857 aux->id,
1858 dns_resource_key_to_string(t->key, s, sizeof s),
1859 t->id,
1860 dns_resource_key_to_string(aux->key, saux, sizeof saux));
1861
1862 return -ELOOP;
1863 }
1864 }
1865
1866 r = set_ensure_allocated(&t->dnssec_transactions, NULL);
1867 if (r < 0)
1868 goto gc;
1869
1870 r = set_ensure_allocated(&aux->notify_transactions, NULL);
1871 if (r < 0)
1872 goto gc;
1873
1874 r = set_ensure_allocated(&aux->notify_transactions_done, NULL);
1875 if (r < 0)
1876 goto gc;
1877
1878 r = set_put(t->dnssec_transactions, aux);
1879 if (r < 0)
1880 goto gc;
1881
1882 r = set_put(aux->notify_transactions, t);
1883 if (r < 0) {
1884 (void) set_remove(t->dnssec_transactions, aux);
1885 goto gc;
1886 }
1887
1888 *ret = aux;
1889 return 1;
1890
1891 gc:
1892 dns_transaction_gc(aux);
1893 return r;
1894 }
1895
1896 static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) {
1897 _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL;
1898 DnsTransaction *aux;
1899 int r;
1900
1901 assert(t);
1902 assert(key);
1903
1904 /* Try to get the data from the trust anchor */
1905 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a);
1906 if (r < 0)
1907 return r;
1908 if (r > 0) {
1909 r = dns_answer_extend(&t->validated_keys, a);
1910 if (r < 0)
1911 return r;
1912
1913 return 0;
1914 }
1915
1916 /* This didn't work, ask for it via the network/cache then. */
1917 r = dns_transaction_add_dnssec_transaction(t, key, &aux);
1918 if (r == -ELOOP) /* This would result in a cyclic dependency */
1919 return 0;
1920 if (r < 0)
1921 return r;
1922
1923 if (aux->state == DNS_TRANSACTION_NULL) {
1924 r = dns_transaction_go(aux);
1925 if (r < 0)
1926 return r;
1927 }
1928
1929 return 1;
1930 }
1931
1932 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) {
1933 int r;
1934
1935 assert(t);
1936
1937 /* Check whether the specified name is in the NTA
1938 * database, either in the global one, or the link-local
1939 * one. */
1940
1941 r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name);
1942 if (r != 0)
1943 return r;
1944
1945 if (!t->scope->link)
1946 return 0;
1947
1948 return set_contains(t->scope->link->dnssec_negative_trust_anchors, name);
1949 }
1950
1951 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction *t) {
1952 int r;
1953
1954 assert(t);
1955
1956 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1957 * RRs to prove it */
1958
1959 r = dns_transaction_has_positive_answer(t, NULL);
1960 if (r < 0)
1961 return r;
1962 if (r > 0)
1963 return false;
1964
1965 /* Is this key explicitly listed as a negative trust anchor?
1966 * If so, it's nothing we need to care about */
1967 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key));
1968 if (r < 0)
1969 return r;
1970 if (r > 0)
1971 return false;
1972
1973 /* The answer does not contain any RRs that match to the
1974 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1975 * included. If not, the answer is unsigned. */
1976
1977 r = dns_answer_contains_nsec_or_nsec3(t->answer);
1978 if (r < 0)
1979 return r;
1980 if (r > 0)
1981 return false;
1982
1983 return true;
1984 }
1985
1986 static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) {
1987 int r;
1988
1989 assert(t);
1990 assert(rr);
1991
1992 /* Check if the specified RR is the "primary" response,
1993 * i.e. either matches the question precisely or is a
1994 * CNAME/DNAME for it. */
1995
1996 r = dns_resource_key_match_rr(t->key, rr, NULL);
1997 if (r != 0)
1998 return r;
1999
2000 return dns_resource_key_match_cname_or_dname(t->key, rr->key, NULL);
2001 }
2002
2003 static bool dns_transaction_dnssec_supported(DnsTransaction *t) {
2004 assert(t);
2005
2006 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
2007 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
2008
2009 if (t->scope->protocol != DNS_PROTOCOL_DNS)
2010 return false;
2011
2012 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
2013 * be supported, hence return true. */
2014 if (!t->server)
2015 return true;
2016
2017 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
2018 * the server is known to support currently, as the transaction feature level might be lower than what the
2019 * server actually supports, since we might have downgraded this transaction's feature level because we got a
2020 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
2021
2022 return dns_server_dnssec_supported(t->server);
2023 }
2024
2025 static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) {
2026 DnsTransaction *dt;
2027 Iterator i;
2028
2029 assert(t);
2030
2031 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
2032
2033 if (!dns_transaction_dnssec_supported(t))
2034 return false;
2035
2036 SET_FOREACH(dt, t->dnssec_transactions, i)
2037 if (!dns_transaction_dnssec_supported(dt))
2038 return false;
2039
2040 return true;
2041 }
2042
2043 int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
2044 DnsResourceRecord *rr;
2045
2046 int r;
2047
2048 assert(t);
2049
2050 /*
2051 * Retrieve all auxiliary RRs for the answer we got, so that
2052 * we can verify signatures or prove that RRs are rightfully
2053 * unsigned. Specifically:
2054 *
2055 * - For RRSIG we get the matching DNSKEY
2056 * - For DNSKEY we get the matching DS
2057 * - For unsigned SOA/NS we get the matching DS
2058 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
2059 * - For other unsigned RRs we get the matching SOA RR
2060 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
2061 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
2062 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
2063 */
2064
2065 if (t->scope->dnssec_mode == DNSSEC_NO)
2066 return 0;
2067 if (t->answer_source != DNS_TRANSACTION_NETWORK)
2068 return 0; /* We only need to validate stuff from the network */
2069 if (!dns_transaction_dnssec_supported(t))
2070 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
2071
2072 DNS_ANSWER_FOREACH(rr, t->answer) {
2073
2074 if (dns_type_is_pseudo(rr->key->type))
2075 continue;
2076
2077 /* If this RR is in the negative trust anchor, we don't need to validate it. */
2078 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2079 if (r < 0)
2080 return r;
2081 if (r > 0)
2082 continue;
2083
2084 switch (rr->key->type) {
2085
2086 case DNS_TYPE_RRSIG: {
2087 /* For each RRSIG we request the matching DNSKEY */
2088 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL;
2089
2090 /* If this RRSIG is about a DNSKEY RR and the
2091 * signer is the same as the owner, then we
2092 * already have the DNSKEY, and we don't have
2093 * to look for more. */
2094 if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) {
2095 r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key));
2096 if (r < 0)
2097 return r;
2098 if (r > 0)
2099 continue;
2100 }
2101
2102 /* If the signer is not a parent of our
2103 * original query, then this is about an
2104 * auxiliary RRset, but not anything we asked
2105 * for. In this case we aren't interested,
2106 * because we don't want to request additional
2107 * RRs for stuff we didn't really ask for, and
2108 * also to avoid request loops, where
2109 * additional RRs from one transaction result
2110 * in another transaction whose additonal RRs
2111 * point back to the original transaction, and
2112 * we deadlock. */
2113 r = dns_name_endswith(dns_resource_key_name(t->key), rr->rrsig.signer);
2114 if (r < 0)
2115 return r;
2116 if (r == 0)
2117 continue;
2118
2119 dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer);
2120 if (!dnskey)
2121 return -ENOMEM;
2122
2123 log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").",
2124 t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag);
2125 r = dns_transaction_request_dnssec_rr(t, dnskey);
2126 if (r < 0)
2127 return r;
2128 break;
2129 }
2130
2131 case DNS_TYPE_DNSKEY: {
2132 /* For each DNSKEY we request the matching DS */
2133 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2134
2135 /* If the DNSKEY we are looking at is not for
2136 * zone we are interested in, nor any of its
2137 * parents, we aren't interested, and don't
2138 * request it. After all, we don't want to end
2139 * up in request loops, and want to keep
2140 * additional traffic down. */
2141
2142 r = dns_name_endswith(dns_resource_key_name(t->key), dns_resource_key_name(rr->key));
2143 if (r < 0)
2144 return r;
2145 if (r == 0)
2146 continue;
2147
2148 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2149 if (!ds)
2150 return -ENOMEM;
2151
2152 log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").",
2153 t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false));
2154 r = dns_transaction_request_dnssec_rr(t, ds);
2155 if (r < 0)
2156 return r;
2157
2158 break;
2159 }
2160
2161 case DNS_TYPE_SOA:
2162 case DNS_TYPE_NS: {
2163 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2164
2165 /* For an unsigned SOA or NS, try to acquire
2166 * the matching DS RR, as we are at a zone cut
2167 * then, and whether a DS exists tells us
2168 * whether the zone is signed. Do so only if
2169 * this RR matches our original question,
2170 * however. */
2171
2172 r = dns_resource_key_match_rr(t->key, rr, NULL);
2173 if (r < 0)
2174 return r;
2175 if (r == 0) {
2176 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2177 * a negative reply, and we need the a SOA RR's TTL in order to cache a negative entry?
2178 * If so, we need to validate it, too. */
2179
2180 r = dns_answer_match_key(t->answer, t->key, NULL);
2181 if (r < 0)
2182 return r;
2183 if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate
2184 * it. */
2185 continue;
2186 }
2187
2188 r = dnssec_has_rrsig(t->answer, rr->key);
2189 if (r < 0)
2190 return r;
2191 if (r > 0)
2192 continue;
2193
2194 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2195 if (!ds)
2196 return -ENOMEM;
2197
2198 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).",
2199 t->id, dns_resource_key_name(rr->key));
2200 r = dns_transaction_request_dnssec_rr(t, ds);
2201 if (r < 0)
2202 return r;
2203
2204 break;
2205 }
2206
2207 case DNS_TYPE_DS:
2208 case DNS_TYPE_CNAME:
2209 case DNS_TYPE_DNAME: {
2210 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2211 const char *name;
2212
2213 /* CNAMEs and DNAMEs cannot be located at a
2214 * zone apex, hence ask for the parent SOA for
2215 * unsigned CNAME/DNAME RRs, maybe that's the
2216 * apex. But do all that only if this is
2217 * actually a response to our original
2218 * question.
2219 *
2220 * Similar for DS RRs, which are signed when
2221 * the parent SOA is signed. */
2222
2223 r = dns_transaction_is_primary_response(t, rr);
2224 if (r < 0)
2225 return r;
2226 if (r == 0)
2227 continue;
2228
2229 r = dnssec_has_rrsig(t->answer, rr->key);
2230 if (r < 0)
2231 return r;
2232 if (r > 0)
2233 continue;
2234
2235 r = dns_answer_has_dname_for_cname(t->answer, rr);
2236 if (r < 0)
2237 return r;
2238 if (r > 0)
2239 continue;
2240
2241 name = dns_resource_key_name(rr->key);
2242 r = dns_name_parent(&name);
2243 if (r < 0)
2244 return r;
2245 if (r == 0)
2246 continue;
2247
2248 soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name);
2249 if (!soa)
2250 return -ENOMEM;
2251
2252 log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).",
2253 t->id, dns_resource_key_name(rr->key));
2254 r = dns_transaction_request_dnssec_rr(t, soa);
2255 if (r < 0)
2256 return r;
2257
2258 break;
2259 }
2260
2261 default: {
2262 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2263
2264 /* For other unsigned RRsets (including
2265 * NSEC/NSEC3!), look for proof the zone is
2266 * unsigned, by requesting the SOA RR of the
2267 * zone. However, do so only if they are
2268 * directly relevant to our original
2269 * question. */
2270
2271 r = dns_transaction_is_primary_response(t, rr);
2272 if (r < 0)
2273 return r;
2274 if (r == 0)
2275 continue;
2276
2277 r = dnssec_has_rrsig(t->answer, rr->key);
2278 if (r < 0)
2279 return r;
2280 if (r > 0)
2281 continue;
2282
2283 soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, dns_resource_key_name(rr->key));
2284 if (!soa)
2285 return -ENOMEM;
2286
2287 log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).",
2288 t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr));
2289 r = dns_transaction_request_dnssec_rr(t, soa);
2290 if (r < 0)
2291 return r;
2292 break;
2293 }}
2294 }
2295
2296 /* Above, we requested everything necessary to validate what
2297 * we got. Now, let's request what we need to validate what we
2298 * didn't get... */
2299
2300 r = dns_transaction_has_unsigned_negative_answer(t);
2301 if (r < 0)
2302 return r;
2303 if (r > 0) {
2304 const char *name;
2305 uint16_t type = 0;
2306
2307 name = dns_resource_key_name(t->key);
2308
2309 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2310 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2311 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2312 * though they have further children. If this was a DS request, then it's signed when the parent zone
2313 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2314 * to see if that is signed. */
2315
2316 if (t->key->type == DNS_TYPE_DS) {
2317 r = dns_name_parent(&name);
2318 if (r > 0) {
2319 type = DNS_TYPE_SOA;
2320 log_debug("Requesting parent SOA to validate transaction %" PRIu16 " (%s, unsigned empty DS response).",
2321 t->id, dns_resource_key_name(t->key));
2322 } else
2323 name = NULL;
2324
2325 } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS)) {
2326
2327 type = DNS_TYPE_DS;
2328 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned empty SOA/NS response).",
2329 t->id, dns_resource_key_name(t->key));
2330
2331 } else {
2332 type = DNS_TYPE_SOA;
2333 log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned empty non-SOA/NS/DS response).",
2334 t->id, dns_resource_key_name(t->key));
2335 }
2336
2337 if (name) {
2338 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2339
2340 soa = dns_resource_key_new(t->key->class, type, name);
2341 if (!soa)
2342 return -ENOMEM;
2343
2344 r = dns_transaction_request_dnssec_rr(t, soa);
2345 if (r < 0)
2346 return r;
2347 }
2348 }
2349
2350 return dns_transaction_dnssec_is_live(t);
2351 }
2352
2353 void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) {
2354 assert(t);
2355 assert(source);
2356
2357 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2358 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2359 the state is VALIDATING however, we should check if we are complete now. */
2360
2361 if (t->state == DNS_TRANSACTION_VALIDATING)
2362 dns_transaction_process_dnssec(t);
2363 }
2364
2365 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) {
2366 DnsResourceRecord *rr;
2367 int ifindex, r;
2368
2369 assert(t);
2370
2371 /* Add all DNSKEY RRs from the answer that are validated by DS
2372 * RRs from the list of validated keys to the list of
2373 * validated keys. */
2374
2375 DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, t->answer) {
2376
2377 r = dnssec_verify_dnskey_by_ds_search(rr, t->validated_keys);
2378 if (r < 0)
2379 return r;
2380 if (r == 0)
2381 continue;
2382
2383 /* If so, the DNSKEY is validated too. */
2384 r = dns_answer_add_extend(&t->validated_keys, rr, ifindex, DNS_ANSWER_AUTHENTICATED);
2385 if (r < 0)
2386 return r;
2387 }
2388
2389 return 0;
2390 }
2391
2392 static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) {
2393 int r;
2394
2395 assert(t);
2396 assert(rr);
2397
2398 /* Checks if the RR we are looking for must be signed with an
2399 * RRSIG. This is used for positive responses. */
2400
2401 if (t->scope->dnssec_mode == DNSSEC_NO)
2402 return false;
2403
2404 if (dns_type_is_pseudo(rr->key->type))
2405 return -EINVAL;
2406
2407 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2408 if (r < 0)
2409 return r;
2410 if (r > 0)
2411 return false;
2412
2413 switch (rr->key->type) {
2414
2415 case DNS_TYPE_RRSIG:
2416 /* RRSIGs are the signatures themselves, they need no signing. */
2417 return false;
2418
2419 case DNS_TYPE_SOA:
2420 case DNS_TYPE_NS: {
2421 DnsTransaction *dt;
2422 Iterator i;
2423
2424 /* For SOA or NS RRs we look for a matching DS transaction */
2425
2426 SET_FOREACH(dt, t->dnssec_transactions, i) {
2427
2428 if (dt->key->class != rr->key->class)
2429 continue;
2430 if (dt->key->type != DNS_TYPE_DS)
2431 continue;
2432
2433 r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key));
2434 if (r < 0)
2435 return r;
2436 if (r == 0)
2437 continue;
2438
2439 /* We found a DS transactions for the SOA/NS
2440 * RRs we are looking at. If it discovered signed DS
2441 * RRs, then we need to be signed, too. */
2442
2443 if (!dt->answer_authenticated)
2444 return false;
2445
2446 return dns_answer_match_key(dt->answer, dt->key, NULL);
2447 }
2448
2449 /* We found nothing that proves this is safe to leave
2450 * this unauthenticated, hence ask inist on
2451 * authentication. */
2452 return true;
2453 }
2454
2455 case DNS_TYPE_DS:
2456 case DNS_TYPE_CNAME:
2457 case DNS_TYPE_DNAME: {
2458 const char *parent = NULL;
2459 DnsTransaction *dt;
2460 Iterator i;
2461
2462 /*
2463 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2464 *
2465 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2466 */
2467
2468 SET_FOREACH(dt, t->dnssec_transactions, i) {
2469
2470 if (dt->key->class != rr->key->class)
2471 continue;
2472 if (dt->key->type != DNS_TYPE_SOA)
2473 continue;
2474
2475 if (!parent) {
2476 parent = dns_resource_key_name(rr->key);
2477 r = dns_name_parent(&parent);
2478 if (r < 0)
2479 return r;
2480 if (r == 0) {
2481 if (rr->key->type == DNS_TYPE_DS)
2482 return true;
2483
2484 /* A CNAME/DNAME without a parent? That's sooo weird. */
2485 log_debug("Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id);
2486 return -EBADMSG;
2487 }
2488 }
2489
2490 r = dns_name_equal(dns_resource_key_name(dt->key), parent);
2491 if (r < 0)
2492 return r;
2493 if (r == 0)
2494 continue;
2495
2496 return t->answer_authenticated;
2497 }
2498
2499 return true;
2500 }
2501
2502 default: {
2503 DnsTransaction *dt;
2504 Iterator i;
2505
2506 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2507
2508 SET_FOREACH(dt, t->dnssec_transactions, i) {
2509
2510 if (dt->key->class != rr->key->class)
2511 continue;
2512 if (dt->key->type != DNS_TYPE_SOA)
2513 continue;
2514
2515 r = dns_name_equal(dns_resource_key_name(dt->key), dns_resource_key_name(rr->key));
2516 if (r < 0)
2517 return r;
2518 if (r == 0)
2519 continue;
2520
2521 /* We found the transaction that was supposed to find
2522 * the SOA RR for us. It was successful, but found no
2523 * RR for us. This means we are not at a zone cut. In
2524 * this case, we require authentication if the SOA
2525 * lookup was authenticated too. */
2526 return t->answer_authenticated;
2527 }
2528
2529 return true;
2530 }}
2531 }
2532
2533 static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) {
2534 DnsTransaction *dt;
2535 const char *tld;
2536 Iterator i;
2537 int r;
2538
2539 /* If DNSSEC downgrade mode is on, checks whether the
2540 * specified RR is one level below a TLD we have proven not to
2541 * exist. In such a case we assume that this is a private
2542 * domain, and permit it.
2543 *
2544 * This detects cases like the Fritz!Box router networks. Each
2545 * Fritz!Box router serves a private "fritz.box" zone, in the
2546 * non-existing TLD "box". Requests for the "fritz.box" domain
2547 * are served by the router itself, while requests for the
2548 * "box" domain will result in NXDOMAIN.
2549 *
2550 * Note that this logic is unable to detect cases where a
2551 * router serves a private DNS zone directly under
2552 * non-existing TLD. In such a case we cannot detect whether
2553 * the TLD is supposed to exist or not, as all requests we
2554 * make for it will be answered by the router's zone, and not
2555 * by the root zone. */
2556
2557 assert(t);
2558
2559 if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE)
2560 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2561
2562 tld = dns_resource_key_name(key);
2563 r = dns_name_parent(&tld);
2564 if (r < 0)
2565 return r;
2566 if (r == 0)
2567 return false; /* Already the root domain */
2568
2569 if (!dns_name_is_single_label(tld))
2570 return false;
2571
2572 SET_FOREACH(dt, t->dnssec_transactions, i) {
2573
2574 if (dt->key->class != key->class)
2575 continue;
2576
2577 r = dns_name_equal(dns_resource_key_name(dt->key), tld);
2578 if (r < 0)
2579 return r;
2580 if (r == 0)
2581 continue;
2582
2583 /* We found an auxiliary lookup we did for the TLD. If
2584 * that returned with NXDOMAIN, we know the TLD didn't
2585 * exist, and hence this might be a private zone. */
2586
2587 return dt->answer_rcode == DNS_RCODE_NXDOMAIN;
2588 }
2589
2590 return false;
2591 }
2592
2593 static int dns_transaction_requires_nsec(DnsTransaction *t) {
2594 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
2595 DnsTransaction *dt;
2596 const char *name;
2597 uint16_t type = 0;
2598 Iterator i;
2599 int r;
2600
2601 assert(t);
2602
2603 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2604 * this negative reply */
2605
2606 if (t->scope->dnssec_mode == DNSSEC_NO)
2607 return false;
2608
2609 if (dns_type_is_pseudo(t->key->type))
2610 return -EINVAL;
2611
2612 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(t->key));
2613 if (r < 0)
2614 return r;
2615 if (r > 0)
2616 return false;
2617
2618 r = dns_transaction_in_private_tld(t, t->key);
2619 if (r < 0)
2620 return r;
2621 if (r > 0) {
2622 /* The lookup is from a TLD that is proven not to
2623 * exist, and we are in downgrade mode, hence ignore
2624 * that fact that we didn't get any NSEC RRs. */
2625
2626 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2627 dns_resource_key_to_string(t->key, key_str, sizeof key_str));
2628 return false;
2629 }
2630
2631 name = dns_resource_key_name(t->key);
2632
2633 if (t->key->type == DNS_TYPE_DS) {
2634
2635 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2636 * hence check the parent SOA in this case. */
2637
2638 r = dns_name_parent(&name);
2639 if (r < 0)
2640 return r;
2641 if (r == 0)
2642 return true;
2643
2644 type = DNS_TYPE_SOA;
2645
2646 } else if (IN_SET(t->key->type, DNS_TYPE_SOA, DNS_TYPE_NS))
2647 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2648 type = DNS_TYPE_DS;
2649 else
2650 /* For all other negative replies, check for the SOA lookup */
2651 type = DNS_TYPE_SOA;
2652
2653 /* For all other RRs we check the SOA on the same level to see
2654 * if it's signed. */
2655
2656 SET_FOREACH(dt, t->dnssec_transactions, i) {
2657
2658 if (dt->key->class != t->key->class)
2659 continue;
2660 if (dt->key->type != type)
2661 continue;
2662
2663 r = dns_name_equal(dns_resource_key_name(dt->key), name);
2664 if (r < 0)
2665 return r;
2666 if (r == 0)
2667 continue;
2668
2669 return dt->answer_authenticated;
2670 }
2671
2672 /* If in doubt, require NSEC/NSEC3 */
2673 return true;
2674 }
2675
2676 static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) {
2677 DnsResourceRecord *rrsig;
2678 bool found = false;
2679 int r;
2680
2681 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2682 * the specified RRset is authenticated (i.e. has a matching
2683 * DS RR). */
2684
2685 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2686 if (r < 0)
2687 return r;
2688 if (r > 0)
2689 return false;
2690
2691 DNS_ANSWER_FOREACH(rrsig, t->answer) {
2692 DnsTransaction *dt;
2693 Iterator i;
2694
2695 r = dnssec_key_match_rrsig(rr->key, rrsig);
2696 if (r < 0)
2697 return r;
2698 if (r == 0)
2699 continue;
2700
2701 SET_FOREACH(dt, t->dnssec_transactions, i) {
2702
2703 if (dt->key->class != rr->key->class)
2704 continue;
2705
2706 if (dt->key->type == DNS_TYPE_DNSKEY) {
2707
2708 r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer);
2709 if (r < 0)
2710 return r;
2711 if (r == 0)
2712 continue;
2713
2714 /* OK, we found an auxiliary DNSKEY
2715 * lookup. If that lookup is
2716 * authenticated, report this. */
2717
2718 if (dt->answer_authenticated)
2719 return true;
2720
2721 found = true;
2722
2723 } else if (dt->key->type == DNS_TYPE_DS) {
2724
2725 r = dns_name_equal(dns_resource_key_name(dt->key), rrsig->rrsig.signer);
2726 if (r < 0)
2727 return r;
2728 if (r == 0)
2729 continue;
2730
2731 /* OK, we found an auxiliary DS
2732 * lookup. If that lookup is
2733 * authenticated and non-zero, we
2734 * won! */
2735
2736 if (!dt->answer_authenticated)
2737 return false;
2738
2739 return dns_answer_match_key(dt->answer, dt->key, NULL);
2740 }
2741 }
2742 }
2743
2744 return found ? false : -ENXIO;
2745 }
2746
2747 static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) {
2748 assert(t);
2749 assert(rr);
2750
2751 /* We know that the root domain is signed, hence if it appears
2752 * not to be signed, there's a problem with the DNS server */
2753
2754 return rr->key->class == DNS_CLASS_IN &&
2755 dns_name_is_root(dns_resource_key_name(rr->key));
2756 }
2757
2758 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) {
2759 DnsResourceRecord *rr;
2760 int r;
2761
2762 assert(t);
2763
2764 /* Maybe warn the user that we encountered a revoked DNSKEY
2765 * for a key from our trust anchor. Note that we don't care
2766 * whether the DNSKEY can be authenticated or not. It's
2767 * sufficient if it is self-signed. */
2768
2769 DNS_ANSWER_FOREACH(rr, t->answer) {
2770 r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer);
2771 if (r < 0)
2772 return r;
2773 }
2774
2775 return 0;
2776 }
2777
2778 static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) {
2779 bool changed;
2780 int r;
2781
2782 assert(t);
2783
2784 /* Removes all DNSKEY/DS objects from t->validated_keys that
2785 * our trust anchors database considers revoked. */
2786
2787 do {
2788 DnsResourceRecord *rr;
2789
2790 changed = false;
2791
2792 DNS_ANSWER_FOREACH(rr, t->validated_keys) {
2793 r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr);
2794 if (r < 0)
2795 return r;
2796 if (r > 0) {
2797 r = dns_answer_remove_by_rr(&t->validated_keys, rr);
2798 if (r < 0)
2799 return r;
2800
2801 assert(r > 0);
2802 changed = true;
2803 break;
2804 }
2805 }
2806 } while (changed);
2807
2808 return 0;
2809 }
2810
2811 static int dns_transaction_copy_validated(DnsTransaction *t) {
2812 DnsTransaction *dt;
2813 Iterator i;
2814 int r;
2815
2816 assert(t);
2817
2818 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2819
2820 SET_FOREACH(dt, t->dnssec_transactions, i) {
2821
2822 if (DNS_TRANSACTION_IS_LIVE(dt->state))
2823 continue;
2824
2825 if (!dt->answer_authenticated)
2826 continue;
2827
2828 r = dns_answer_extend(&t->validated_keys, dt->answer);
2829 if (r < 0)
2830 return r;
2831 }
2832
2833 return 0;
2834 }
2835
2836 typedef enum {
2837 DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */
2838 DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */
2839 DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */
2840 } Phase;
2841
2842 static int dnssec_validate_records(
2843 DnsTransaction *t,
2844 Phase phase,
2845 bool *have_nsec,
2846 DnsAnswer **validated) {
2847
2848 DnsResourceRecord *rr;
2849 int r;
2850
2851 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2852
2853 DNS_ANSWER_FOREACH(rr, t->answer) {
2854 DnsResourceRecord *rrsig = NULL;
2855 DnssecResult result;
2856
2857 switch (rr->key->type) {
2858 case DNS_TYPE_RRSIG:
2859 continue;
2860
2861 case DNS_TYPE_DNSKEY:
2862 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2863 if (phase == DNSSEC_PHASE_NSEC)
2864 continue;
2865 break;
2866
2867 case DNS_TYPE_NSEC:
2868 case DNS_TYPE_NSEC3:
2869 *have_nsec = true;
2870
2871 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2872 if (phase == DNSSEC_PHASE_DNSKEY)
2873 continue;
2874 break;
2875
2876 default:
2877 /* We validate all other RRs only in the ALL phases */
2878 if (phase != DNSSEC_PHASE_ALL)
2879 continue;
2880 }
2881
2882 r = dnssec_verify_rrset_search(t->answer, rr->key, t->validated_keys, USEC_INFINITY, &result, &rrsig);
2883 if (r < 0)
2884 return r;
2885
2886 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result));
2887
2888 if (result == DNSSEC_VALIDATED) {
2889
2890 if (rr->key->type == DNS_TYPE_DNSKEY) {
2891 /* If we just validated a DNSKEY RRset, then let's add these keys to
2892 * the set of validated keys for this transaction. */
2893
2894 r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED);
2895 if (r < 0)
2896 return r;
2897
2898 /* Some of the DNSKEYs we just added might already have been revoked,
2899 * remove them again in that case. */
2900 r = dns_transaction_invalidate_revoked_keys(t);
2901 if (r < 0)
2902 return r;
2903 }
2904
2905 /* Add the validated RRset to the new list of validated
2906 * RRsets, and remove it from the unvalidated RRsets.
2907 * We mark the RRset as authenticated and cacheable. */
2908 r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE);
2909 if (r < 0)
2910 return r;
2911
2912 manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key);
2913
2914 /* Exit the loop, we dropped something from the answer, start from the beginning */
2915 return 1;
2916 }
2917
2918 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2919 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2920 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2921 if (phase != DNSSEC_PHASE_ALL)
2922 continue;
2923
2924 if (result == DNSSEC_VALIDATED_WILDCARD) {
2925 bool authenticated = false;
2926 const char *source;
2927
2928 /* This RRset validated, but as a wildcard. This means we need
2929 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
2930
2931 /* First step, determine the source of synthesis */
2932 r = dns_resource_record_source(rrsig, &source);
2933 if (r < 0)
2934 return r;
2935
2936 r = dnssec_test_positive_wildcard(*validated,
2937 dns_resource_key_name(rr->key),
2938 source,
2939 rrsig->rrsig.signer,
2940 &authenticated);
2941
2942 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2943 if (r == 0)
2944 result = DNSSEC_INVALID;
2945 else {
2946 r = dns_answer_move_by_key(validated, &t->answer, rr->key,
2947 authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0);
2948 if (r < 0)
2949 return r;
2950
2951 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key);
2952
2953 /* Exit the loop, we dropped something from the answer, start from the beginning */
2954 return 1;
2955 }
2956 }
2957
2958 if (result == DNSSEC_NO_SIGNATURE) {
2959 r = dns_transaction_requires_rrsig(t, rr);
2960 if (r < 0)
2961 return r;
2962 if (r == 0) {
2963 /* Data does not require signing. In that case, just copy it over,
2964 * but remember that this is by no means authenticated. */
2965 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
2966 if (r < 0)
2967 return r;
2968
2969 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
2970 return 1;
2971 }
2972
2973 r = dns_transaction_known_signed(t, rr);
2974 if (r < 0)
2975 return r;
2976 if (r > 0) {
2977 /* This is an RR we know has to be signed. If it isn't this means
2978 * the server is not attaching RRSIGs, hence complain. */
2979
2980 dns_server_packet_rrsig_missing(t->server, t->current_feature_level);
2981
2982 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
2983
2984 /* Downgrading is OK? If so, just consider the information unsigned */
2985
2986 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
2987 if (r < 0)
2988 return r;
2989
2990 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
2991 return 1;
2992 }
2993
2994 /* Otherwise, fail */
2995 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
2996 return 0;
2997 }
2998
2999 r = dns_transaction_in_private_tld(t, rr->key);
3000 if (r < 0)
3001 return r;
3002 if (r > 0) {
3003 char s[DNS_RESOURCE_KEY_STRING_MAX];
3004
3005 /* The data is from a TLD that is proven not to exist, and we are in downgrade
3006 * mode, hence ignore the fact that this was not signed. */
3007
3008 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
3009 dns_resource_key_to_string(rr->key, s, sizeof s));
3010
3011 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
3012 if (r < 0)
3013 return r;
3014
3015 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3016 return 1;
3017 }
3018 }
3019
3020 if (IN_SET(result,
3021 DNSSEC_MISSING_KEY,
3022 DNSSEC_SIGNATURE_EXPIRED,
3023 DNSSEC_UNSUPPORTED_ALGORITHM)) {
3024
3025 r = dns_transaction_dnskey_authenticated(t, rr);
3026 if (r < 0 && r != -ENXIO)
3027 return r;
3028 if (r == 0) {
3029 /* The DNSKEY transaction was not authenticated, this means there's
3030 * no DS for this, which means it's OK if no keys are found for this signature. */
3031
3032 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0);
3033 if (r < 0)
3034 return r;
3035
3036 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3037 return 1;
3038 }
3039 }
3040
3041 r = dns_transaction_is_primary_response(t, rr);
3042 if (r < 0)
3043 return r;
3044 if (r > 0) {
3045 /* Look for a matching DNAME for this CNAME */
3046 r = dns_answer_has_dname_for_cname(t->answer, rr);
3047 if (r < 0)
3048 return r;
3049 if (r == 0) {
3050 /* Also look among the stuff we already validated */
3051 r = dns_answer_has_dname_for_cname(*validated, rr);
3052 if (r < 0)
3053 return r;
3054 }
3055
3056 if (r == 0) {
3057 if (IN_SET(result,
3058 DNSSEC_INVALID,
3059 DNSSEC_SIGNATURE_EXPIRED,
3060 DNSSEC_NO_SIGNATURE))
3061 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key);
3062 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
3063 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key);
3064
3065 /* This is a primary response to our question, and it failed validation.
3066 * That's fatal. */
3067 t->answer_dnssec_result = result;
3068 return 0;
3069 }
3070
3071 /* This is a primary response, but we do have a DNAME RR
3072 * in the RR that can replay this CNAME, hence rely on
3073 * that, and we can remove the CNAME in favour of it. */
3074 }
3075
3076 /* This is just some auxiliary data. Just remove the RRset and continue. */
3077 r = dns_answer_remove_by_key(&t->answer, rr->key);
3078 if (r < 0)
3079 return r;
3080
3081 /* We dropped something from the answer, start from the beginning. */
3082 return 1;
3083 }
3084
3085 return 2; /* Finito. */
3086 }
3087
3088 int dns_transaction_validate_dnssec(DnsTransaction *t) {
3089 _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL;
3090 Phase phase;
3091 DnsAnswerFlags flags;
3092 int r;
3093 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
3094
3095 assert(t);
3096
3097 /* We have now collected all DS and DNSKEY RRs in
3098 * t->validated_keys, let's see which RRs we can now
3099 * authenticate with that. */
3100
3101 if (t->scope->dnssec_mode == DNSSEC_NO)
3102 return 0;
3103
3104 /* Already validated */
3105 if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID)
3106 return 0;
3107
3108 /* Our own stuff needs no validation */
3109 if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) {
3110 t->answer_dnssec_result = DNSSEC_VALIDATED;
3111 t->answer_authenticated = true;
3112 return 0;
3113 }
3114
3115 /* Cached stuff is not affected by validation. */
3116 if (t->answer_source != DNS_TRANSACTION_NETWORK)
3117 return 0;
3118
3119 if (!dns_transaction_dnssec_supported_full(t)) {
3120 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3121 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
3122 log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id);
3123 return 0;
3124 }
3125
3126 log_debug("Validating response from transaction %" PRIu16 " (%s).",
3127 t->id,
3128 dns_resource_key_to_string(t->key, key_str, sizeof key_str));
3129
3130 /* First, see if this response contains any revoked trust
3131 * anchors we care about */
3132 r = dns_transaction_check_revoked_trust_anchors(t);
3133 if (r < 0)
3134 return r;
3135
3136 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3137 r = dns_transaction_copy_validated(t);
3138 if (r < 0)
3139 return r;
3140
3141 /* Second, see if there are DNSKEYs we already know a
3142 * validated DS for. */
3143 r = dns_transaction_validate_dnskey_by_ds(t);
3144 if (r < 0)
3145 return r;
3146
3147 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3148 * anchor says are revoked. After all we might have marked
3149 * some keys revoked above, but they might still be lingering
3150 * in our validated_keys list. */
3151 r = dns_transaction_invalidate_revoked_keys(t);
3152 if (r < 0)
3153 return r;
3154
3155 phase = DNSSEC_PHASE_DNSKEY;
3156 for (;;) {
3157 bool have_nsec = false;
3158
3159 r = dnssec_validate_records(t, phase, &have_nsec, &validated);
3160 if (r <= 0)
3161 return r;
3162
3163 /* Try again as long as we managed to achieve something */
3164 if (r == 1)
3165 continue;
3166
3167 if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) {
3168 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3169 phase = DNSSEC_PHASE_NSEC;
3170 continue;
3171 }
3172
3173 if (phase != DNSSEC_PHASE_ALL) {
3174 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3175 * Note that in this third phase we start to remove RRs we couldn't validate. */
3176 phase = DNSSEC_PHASE_ALL;
3177 continue;
3178 }
3179
3180 /* We're done */
3181 break;
3182 }
3183
3184 dns_answer_unref(t->answer);
3185 t->answer = TAKE_PTR(validated);
3186
3187 /* At this point the answer only contains validated
3188 * RRsets. Now, let's see if it actually answers the question
3189 * we asked. If so, great! If it doesn't, then see if
3190 * NSEC/NSEC3 can prove this. */
3191 r = dns_transaction_has_positive_answer(t, &flags);
3192 if (r > 0) {
3193 /* Yes, it answers the question! */
3194
3195 if (flags & DNS_ANSWER_AUTHENTICATED) {
3196 /* The answer is fully authenticated, yay. */
3197 t->answer_dnssec_result = DNSSEC_VALIDATED;
3198 t->answer_rcode = DNS_RCODE_SUCCESS;
3199 t->answer_authenticated = true;
3200 } else {
3201 /* The answer is not fully authenticated. */
3202 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3203 t->answer_authenticated = false;
3204 }
3205
3206 } else if (r == 0) {
3207 DnssecNsecResult nr;
3208 bool authenticated = false;
3209
3210 /* Bummer! Let's check NSEC/NSEC3 */
3211 r = dnssec_nsec_test(t->answer, t->key, &nr, &authenticated, &t->answer_nsec_ttl);
3212 if (r < 0)
3213 return r;
3214
3215 switch (nr) {
3216
3217 case DNSSEC_NSEC_NXDOMAIN:
3218 /* NSEC proves the domain doesn't exist. Very good. */
3219 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3220 t->answer_dnssec_result = DNSSEC_VALIDATED;
3221 t->answer_rcode = DNS_RCODE_NXDOMAIN;
3222 t->answer_authenticated = authenticated;
3223
3224 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key);
3225 break;
3226
3227 case DNSSEC_NSEC_NODATA:
3228 /* NSEC proves that there's no data here, very good. */
3229 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3230 t->answer_dnssec_result = DNSSEC_VALIDATED;
3231 t->answer_rcode = DNS_RCODE_SUCCESS;
3232 t->answer_authenticated = authenticated;
3233
3234 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, t->key);
3235 break;
3236
3237 case DNSSEC_NSEC_OPTOUT:
3238 /* NSEC3 says the data might not be signed */
3239 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3240 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3241 t->answer_authenticated = false;
3242
3243 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key);
3244 break;
3245
3246 case DNSSEC_NSEC_NO_RR:
3247 /* No NSEC data? Bummer! */
3248
3249 r = dns_transaction_requires_nsec(t);
3250 if (r < 0)
3251 return r;
3252 if (r > 0) {
3253 t->answer_dnssec_result = DNSSEC_NO_SIGNATURE;
3254 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key);
3255 } else {
3256 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3257 t->answer_authenticated = false;
3258 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, t->key);
3259 }
3260
3261 break;
3262
3263 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM:
3264 /* We don't know the NSEC3 algorithm used? */
3265 t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM;
3266 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, t->key);
3267 break;
3268
3269 case DNSSEC_NSEC_FOUND:
3270 case DNSSEC_NSEC_CNAME:
3271 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3272 t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH;
3273 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, t->key);
3274 break;
3275
3276 default:
3277 assert_not_reached("Unexpected NSEC result.");
3278 }
3279 }
3280
3281 return 1;
3282 }
3283
3284 static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = {
3285 [DNS_TRANSACTION_NULL] = "null",
3286 [DNS_TRANSACTION_PENDING] = "pending",
3287 [DNS_TRANSACTION_VALIDATING] = "validating",
3288 [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure",
3289 [DNS_TRANSACTION_SUCCESS] = "success",
3290 [DNS_TRANSACTION_NO_SERVERS] = "no-servers",
3291 [DNS_TRANSACTION_TIMEOUT] = "timeout",
3292 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached",
3293 [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply",
3294 [DNS_TRANSACTION_ERRNO] = "errno",
3295 [DNS_TRANSACTION_ABORTED] = "aborted",
3296 [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed",
3297 [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor",
3298 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported",
3299 [DNS_TRANSACTION_NETWORK_DOWN] = "network-down",
3300 [DNS_TRANSACTION_NOT_FOUND] = "not-found",
3301 };
3302 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState);
3303
3304 static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = {
3305 [DNS_TRANSACTION_NETWORK] = "network",
3306 [DNS_TRANSACTION_CACHE] = "cache",
3307 [DNS_TRANSACTION_ZONE] = "zone",
3308 [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor",
3309 };
3310 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource);
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