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1/* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3#include "sd-event.h"
4#include "sd-messages.h"
5
6#include "af-list.h"
7#include "alloc-util.h"
8#include "dns-domain.h"
9#include "errno-list.h"
10#include "errno-util.h"
11#include "fd-util.h"
12#include "glyph-util.h"
13#include "log.h"
14#include "random-util.h"
15#include "resolved-dns-answer.h"
16#include "resolved-dns-cache.h"
17#include "resolved-dns-packet.h"
18#include "resolved-dns-query.h"
19#include "resolved-dns-question.h"
20#include "resolved-dns-rr.h"
21#include "resolved-dns-scope.h"
22#include "resolved-dns-server.h"
23#include "resolved-dns-stream.h"
24#include "resolved-dns-transaction.h"
25#include "resolved-dnstls.h"
26#include "resolved-link.h"
27#include "resolved-llmnr.h"
28#include "resolved-manager.h"
29#include "resolved-socket-graveyard.h"
30#include "resolved-timeouts.h"
31#include "set.h"
32#include "string-table.h"
33#include "string-util.h"
34
35#define TRANSACTIONS_MAX 4096
36
37static void dns_transaction_reset_answer(DnsTransaction *t) {
38 assert(t);
39
40 t->received = dns_packet_unref(t->received);
41 t->answer = dns_answer_unref(t->answer);
42 t->answer_rcode = 0;
43 t->answer_ede_rcode = _DNS_EDE_RCODE_INVALID;
44 t->answer_ede_msg = mfree(t->answer_ede_msg);
45 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
46 t->answer_source = _DNS_TRANSACTION_SOURCE_INVALID;
47 t->answer_query_flags = 0;
48 t->answer_nsec_ttl = UINT32_MAX;
49 t->answer_errno = 0;
50}
51
52static void dns_transaction_flush_dnssec_transactions(DnsTransaction *t) {
53 DnsTransaction *z;
54
55 assert(t);
56
57 while ((z = set_steal_first(t->dnssec_transactions))) {
58 set_remove(z->notify_transactions, t);
59 set_remove(z->notify_transactions_done, t);
60 dns_transaction_gc(z);
61 }
62}
63
64static void dns_transaction_close_connection(
65 DnsTransaction *t,
66 bool use_graveyard) { /* Set use_graveyard = false when you know the connection is already
67 * dead, for example because you got a connection error back from the
68 * kernel. In that case there's no point in keeping the fd around,
69 * hence don't. */
70 int r;
71
72 assert(t);
73
74 if (t->stream) {
75 /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
76 LIST_REMOVE(transactions_by_stream, t->stream->transactions, t);
77
78 /* Remove packet in case it's still in the queue */
79 dns_packet_unref(ordered_set_remove(t->stream->write_queue, t->sent));
80
81 t->stream = dns_stream_unref(t->stream);
82 }
83
84 t->dns_udp_event_source = sd_event_source_disable_unref(t->dns_udp_event_source);
85
86 /* If we have a UDP socket where we sent a packet, but never received one, then add it to the socket
87 * graveyard, instead of closing it right away. That way it will stick around for a moment longer,
88 * and the reply we might still get from the server will be eaten up instead of resulting in an ICMP
89 * port unreachable error message. */
90
91 /* Skip the graveyard stuff when we're shutting down, since that requires running event loop.
92 * Note that this is also called from dns_transaction_free(). In that case, scope may be NULL. */
93 if (!t->scope ||
94 !t->scope->manager ||
95 !t->scope->manager->event ||
96 sd_event_get_state(t->scope->manager->event) == SD_EVENT_FINISHED)
97 use_graveyard = false;
98
99 if (use_graveyard && t->dns_udp_fd >= 0 && t->sent && !t->received) {
100 r = manager_add_socket_to_graveyard(t->scope->manager, t->dns_udp_fd);
101 if (r < 0)
102 log_debug_errno(r, "Failed to add UDP socket to graveyard, closing immediately: %m");
103 else
104 TAKE_FD(t->dns_udp_fd);
105 }
106
107 t->dns_udp_fd = safe_close(t->dns_udp_fd);
108}
109
110static void dns_transaction_stop_timeout(DnsTransaction *t) {
111 assert(t);
112
113 t->timeout_event_source = sd_event_source_disable_unref(t->timeout_event_source);
114}
115
116DnsTransaction* dns_transaction_free(DnsTransaction *t) {
117 DnsQueryCandidate *c;
118 DnsZoneItem *i;
119 DnsTransaction *z;
120
121 if (!t)
122 return NULL;
123
124 log_debug("Freeing transaction %" PRIu16 ".", t->id);
125
126 dns_transaction_close_connection(t, true);
127 dns_transaction_stop_timeout(t);
128
129 dns_packet_unref(t->sent);
130 dns_transaction_reset_answer(t);
131
132 dns_server_unref(t->server);
133
134 if (t->scope) {
135 if (t->key) {
136 DnsTransaction *first;
137
138 first = hashmap_get(t->scope->transactions_by_key, t->key);
139 LIST_REMOVE(transactions_by_key, first, t);
140 if (first)
141 hashmap_replace(t->scope->transactions_by_key, first->key, first);
142 else
143 hashmap_remove(t->scope->transactions_by_key, t->key);
144 }
145
146 LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
147
148 if (t->id != 0)
149 hashmap_remove(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id));
150 }
151
152 while ((c = set_steal_first(t->notify_query_candidates)))
153 set_remove(c->transactions, t);
154 set_free(t->notify_query_candidates);
155
156 while ((c = set_steal_first(t->notify_query_candidates_done)))
157 set_remove(c->transactions, t);
158 set_free(t->notify_query_candidates_done);
159
160 while ((i = set_steal_first(t->notify_zone_items)))
161 i->probe_transaction = NULL;
162 set_free(t->notify_zone_items);
163
164 while ((i = set_steal_first(t->notify_zone_items_done)))
165 i->probe_transaction = NULL;
166 set_free(t->notify_zone_items_done);
167
168 while ((z = set_steal_first(t->notify_transactions)))
169 set_remove(z->dnssec_transactions, t);
170 set_free(t->notify_transactions);
171
172 while ((z = set_steal_first(t->notify_transactions_done)))
173 set_remove(z->dnssec_transactions, t);
174 set_free(t->notify_transactions_done);
175
176 dns_transaction_flush_dnssec_transactions(t);
177 set_free(t->dnssec_transactions);
178
179 dns_answer_unref(t->validated_keys);
180 dns_resource_key_unref(t->key);
181 dns_packet_unref(t->bypass);
182
183 return mfree(t);
184}
185
186DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction*, dns_transaction_free);
187
188DnsTransaction* dns_transaction_gc(DnsTransaction *t) {
189 assert(t);
190
191 /* Returns !NULL if we can't gc yet. */
192
193 if (t->block_gc > 0)
194 return t;
195
196 if (t->wait_for_answer && IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING))
197 return t;
198
199 if (set_isempty(t->notify_query_candidates) &&
200 set_isempty(t->notify_query_candidates_done) &&
201 set_isempty(t->notify_zone_items) &&
202 set_isempty(t->notify_zone_items_done) &&
203 set_isempty(t->notify_transactions) &&
204 set_isempty(t->notify_transactions_done))
205 return dns_transaction_free(t);
206
207 return t;
208}
209
210static uint16_t pick_new_id(Manager *m) {
211 uint16_t new_id;
212
213 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the
214 * number of transactions, and it's much lower than the space of IDs. */
215
216 assert_cc(TRANSACTIONS_MAX < 0xFFFF);
217
218 do
219 random_bytes(&new_id, sizeof(new_id));
220 while (new_id == 0 ||
221 hashmap_get(m->dns_transactions, UINT_TO_PTR(new_id)));
222
223 return new_id;
224}
225
226static int key_ok(
227 DnsScope *scope,
228 DnsResourceKey *key) {
229
230 /* Don't allow looking up invalid or pseudo RRs */
231 if (!dns_type_is_valid_query(key->type))
232 return -EINVAL;
233 if (dns_type_is_obsolete(key->type))
234 return -EOPNOTSUPP;
235
236 /* We only support the IN class */
237 if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY))
238 return -EOPNOTSUPP;
239
240 /* Don't allows DNSSEC RRs to be looked up via LLMNR/mDNS. They don't really make sense
241 * there, and it speeds up our queries if we refuse this early */
242 if (scope->protocol != DNS_PROTOCOL_DNS &&
243 dns_type_is_dnssec(key->type))
244 return -EOPNOTSUPP;
245
246 return 0;
247}
248
249int dns_transaction_new(
250 DnsTransaction **ret,
251 DnsScope *s,
252 DnsResourceKey *key,
253 DnsPacket *bypass,
254 uint64_t query_flags) {
255
256 _cleanup_(dns_transaction_freep) DnsTransaction *t = NULL;
257 int r;
258
259 assert(ret);
260 assert(s);
261
262 if (key) {
263 assert(!bypass);
264
265 r = key_ok(s, key);
266 if (r < 0)
267 return r;
268 } else {
269 DnsResourceKey *qk;
270 assert(bypass);
271
272 r = dns_packet_validate_query(bypass);
273 if (r < 0)
274 return r;
275
276 DNS_QUESTION_FOREACH(qk, bypass->question) {
277 r = key_ok(s, qk);
278 if (r < 0)
279 return r;
280 }
281 }
282
283 if (hashmap_size(s->manager->dns_transactions) >= TRANSACTIONS_MAX)
284 return -EBUSY;
285
286 r = hashmap_ensure_allocated(&s->manager->dns_transactions, NULL);
287 if (r < 0)
288 return r;
289
290 if (key) {
291 r = hashmap_ensure_allocated(&s->transactions_by_key, &dns_resource_key_hash_ops);
292 if (r < 0)
293 return r;
294 }
295
296 t = new(DnsTransaction, 1);
297 if (!t)
298 return -ENOMEM;
299
300 *t = (DnsTransaction) {
301 .dns_udp_fd = -EBADF,
302 .answer_source = _DNS_TRANSACTION_SOURCE_INVALID,
303 .answer_dnssec_result = _DNSSEC_RESULT_INVALID,
304 .answer_ede_rcode = _DNS_EDE_RCODE_INVALID,
305 .answer_nsec_ttl = UINT32_MAX,
306 .key = dns_resource_key_ref(key),
307 .query_flags = query_flags,
308 .bypass = dns_packet_ref(bypass),
309 .current_feature_level = _DNS_SERVER_FEATURE_LEVEL_INVALID,
310 .clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID,
311 .id = pick_new_id(s->manager),
312 };
313
314 r = hashmap_put(s->manager->dns_transactions, UINT_TO_PTR(t->id), t);
315 if (r < 0) {
316 t->id = 0;
317 return r;
318 }
319
320 if (t->key) {
321 DnsTransaction *first;
322
323 first = hashmap_get(s->transactions_by_key, t->key);
324 LIST_PREPEND(transactions_by_key, first, t);
325
326 r = hashmap_replace(s->transactions_by_key, first->key, first);
327 if (r < 0) {
328 LIST_REMOVE(transactions_by_key, first, t);
329 return r;
330 }
331 }
332
333 LIST_PREPEND(transactions_by_scope, s->transactions, t);
334 t->scope = s;
335
336 s->manager->n_transactions_total++;
337
338 if (ret)
339 *ret = t;
340
341 TAKE_PTR(t);
342 return 0;
343}
344
345static void dns_transaction_shuffle_id(DnsTransaction *t) {
346 uint16_t new_id;
347 assert(t);
348
349 /* Pick a new ID for this transaction. */
350
351 new_id = pick_new_id(t->scope->manager);
352 assert_se(hashmap_remove_and_put(t->scope->manager->dns_transactions, UINT_TO_PTR(t->id), UINT_TO_PTR(new_id), t) >= 0);
353
354 log_debug("Transaction %" PRIu16 " is now %" PRIu16 ".", t->id, new_id);
355 t->id = new_id;
356
357 /* Make sure we generate a new packet with the new ID */
358 t->sent = dns_packet_unref(t->sent);
359}
360
361static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
362 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
363 DnsZoneItem *z;
364
365 assert(t);
366 assert(p);
367 assert(t->scope->protocol == DNS_PROTOCOL_LLMNR);
368
369 if (manager_packet_from_local_address(t->scope->manager, p) != 0)
370 return;
371
372 log_debug("Transaction %" PRIu16 " for <%s> on scope %s on %s/%s got tentative packet from %s.",
373 t->id,
374 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str),
375 dns_protocol_to_string(t->scope->protocol),
376 t->scope->link ? t->scope->link->ifname : "*",
377 af_to_name_short(t->scope->family),
378 IN_ADDR_TO_STRING(p->family, &p->sender));
379
380 /* RFC 4795, Section 4.1 says that the peer with the
381 * lexicographically smaller IP address loses */
382 if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) >= 0) {
383 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
384 return;
385 }
386
387 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
388
389 t->block_gc++;
390
391 while ((z = set_first(t->notify_zone_items))) {
392 /* First, make sure the zone item drops the reference
393 * to us */
394 dns_zone_item_probe_stop(z);
395
396 /* Secondly, report this as conflict, so that we might
397 * look for a different hostname */
398 dns_zone_item_conflict(z);
399 }
400 t->block_gc--;
401
402 dns_transaction_gc(t);
403}
404
405void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) {
406 DnsQueryCandidate *c;
407 DnsZoneItem *z;
408 DnsTransaction *d;
409 const char *st;
410 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
411
412 assert(t);
413 assert(!DNS_TRANSACTION_IS_LIVE(state));
414
415 if (state == DNS_TRANSACTION_DNSSEC_FAILED) {
416 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str);
417
418 log_struct(LOG_NOTICE,
419 LOG_MESSAGE_ID(SD_MESSAGE_DNSSEC_FAILURE_STR),
420 LOG_MESSAGE("DNSSEC validation failed for question %s: %s",
421 key_str, dnssec_result_to_string(t->answer_dnssec_result)),
422 LOG_ITEM("DNS_TRANSACTION=%" PRIu16, t->id),
423 LOG_ITEM("DNS_QUESTION=%s", key_str),
424 LOG_ITEM("DNSSEC_RESULT=%s", dnssec_result_to_string(t->answer_dnssec_result)),
425 LOG_ITEM("DNS_SERVER=%s", strna(dns_server_string_full(t->server))),
426 LOG_ITEM("DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t->server->possible_feature_level)));
427 }
428
429 /* Note that this call might invalidate the query. Callers
430 * should hence not attempt to access the query or transaction
431 * after calling this function. */
432
433 if (state == DNS_TRANSACTION_ERRNO)
434 st = errno_to_name(t->answer_errno);
435 else
436 st = dns_transaction_state_to_string(state);
437
438 log_debug("%s transaction %" PRIu16 " for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s; %s).",
439 t->bypass ? "Bypass" : "Regular",
440 t->id,
441 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str),
442 dns_protocol_to_string(t->scope->protocol),
443 t->scope->link ? t->scope->link->ifname : "*",
444 af_to_name_short(t->scope->family),
445 st,
446 t->answer_source < 0 ? "none" : dns_transaction_source_to_string(t->answer_source),
447 FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) ? "not validated" :
448 (FLAGS_SET(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED) ? "authenticated" : "unsigned"),
449 FLAGS_SET(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL) ? "confidential" : "non-confidential");
450
451 t->state = state;
452
453 dns_transaction_close_connection(t, true);
454 dns_transaction_stop_timeout(t);
455
456 /* Notify all queries that are interested, but make sure the
457 * transaction isn't freed while we are still looking at it */
458 t->block_gc++;
459
460 SET_FOREACH_MOVE(c, t->notify_query_candidates_done, t->notify_query_candidates)
461 dns_query_candidate_notify(c);
462 SWAP_TWO(t->notify_query_candidates, t->notify_query_candidates_done);
463
464 SET_FOREACH_MOVE(z, t->notify_zone_items_done, t->notify_zone_items)
465 dns_zone_item_notify(z);
466 SWAP_TWO(t->notify_zone_items, t->notify_zone_items_done);
467 if (t->probing && t->state == DNS_TRANSACTION_ATTEMPTS_MAX_REACHED)
468 (void) dns_scope_announce(t->scope, false);
469
470 SET_FOREACH_MOVE(d, t->notify_transactions_done, t->notify_transactions)
471 dns_transaction_notify(d, t);
472 SWAP_TWO(t->notify_transactions, t->notify_transactions_done);
473
474 t->block_gc--;
475 dns_transaction_gc(t);
476}
477
478static void dns_transaction_complete_errno(DnsTransaction *t, int error) {
479 assert(t);
480 assert(error != 0);
481
482 t->answer_errno = ABS(error);
483 dns_transaction_complete(t, DNS_TRANSACTION_ERRNO);
484}
485
486static int dns_transaction_pick_server(DnsTransaction *t) {
487 DnsServer *server;
488
489 assert(t);
490 assert(t->scope->protocol == DNS_PROTOCOL_DNS);
491
492 /* Pick a DNS server and a feature level for it. */
493
494 server = dns_scope_get_dns_server(t->scope);
495 if (!server)
496 return -ESRCH;
497
498 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
499 * different properties. */
500 if (server != t->server)
501 t->clamp_feature_level_servfail = _DNS_SERVER_FEATURE_LEVEL_INVALID;
502
503 t->current_feature_level = dns_server_possible_feature_level(server);
504
505 /* Clamp the feature level if that is requested. */
506 if (t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID &&
507 t->current_feature_level > t->clamp_feature_level_servfail)
508 t->current_feature_level = t->clamp_feature_level_servfail;
509
510 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t->current_feature_level), t->id);
511
512 if (server == t->server)
513 return 0;
514
515 dns_server_unref(t->server);
516 t->server = dns_server_ref(server);
517
518 t->n_picked_servers++;
519
520 log_debug("Using DNS server %s for transaction %u.", strna(dns_server_string_full(t->server)), t->id);
521
522 return 1;
523}
524
525static void dns_transaction_retry(DnsTransaction *t, bool next_server) {
526 int r;
527
528 assert(t);
529
530 /* Retries the transaction as it is, possibly on a different server */
531
532 if (next_server && t->scope->protocol == DNS_PROTOCOL_DNS)
533 log_debug("Retrying transaction %" PRIu16 ", after switching servers.", t->id);
534 else
535 log_debug("Retrying transaction %" PRIu16 ".", t->id);
536
537 /* Before we try again, switch to a new server. */
538 if (next_server)
539 dns_scope_next_dns_server(t->scope, t->server);
540
541 r = dns_transaction_go(t);
542 if (r < 0)
543 dns_transaction_complete_errno(t, r);
544}
545
546static bool dns_transaction_limited_retry(DnsTransaction *t) {
547 assert(t);
548
549 /* If we haven't tried all different servers yet, let's try again with a different server */
550
551 if (t->n_picked_servers >= dns_scope_get_n_dns_servers(t->scope))
552 return false;
553
554 dns_transaction_retry(t, /* next_server= */ true);
555 return true;
556}
557
558static int dns_transaction_maybe_restart(DnsTransaction *t) {
559 int r;
560
561 assert(t);
562
563 /* Restarts the transaction, under a new ID if the feature level of the server changed since we first
564 * tried, without changing DNS server. Returns > 0 if the transaction was restarted, 0 if not. */
565
566 if (!t->server)
567 return 0;
568
569 if (t->current_feature_level <= dns_server_possible_feature_level(t->server))
570 return 0;
571
572 /* The server's current feature level is lower than when we sent the original query. We learnt something from
573 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
574 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
575 OPT RR or DO bit. One of these cases is documented here, for example:
576 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
577
578 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
579 dns_transaction_shuffle_id(t);
580
581 r = dns_transaction_go(t);
582 if (r < 0)
583 return r;
584
585 return 1;
586}
587
588static void on_transaction_stream_error(DnsTransaction *t, int error) {
589 assert(t);
590
591 dns_transaction_close_connection(t, true);
592
593 if (ERRNO_IS_DISCONNECT(error)) {
594 if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
595 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
596 * question on this scope. */
597 dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND);
598 return;
599 }
600
601 dns_transaction_retry(t, true);
602 return;
603 }
604 if (error != 0)
605 dns_transaction_complete_errno(t, error);
606}
607
608static int dns_transaction_on_stream_packet(DnsTransaction *t, DnsStream *s, DnsPacket *p) {
609 bool encrypted;
610
611 assert(t);
612 assert(s);
613 assert(p);
614
615 encrypted = s->encrypted;
616
617 dns_transaction_close_connection(t, true);
618
619 if (dns_packet_validate_reply(p) <= 0) {
620 log_debug("Invalid TCP reply packet.");
621 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
622 return 0;
623 }
624
625 dns_scope_check_conflicts(t->scope, p);
626
627 t->block_gc++;
628 dns_transaction_process_reply(t, p, encrypted);
629 t->block_gc--;
630
631 /* If the response wasn't useful, then complete the transition
632 * now. After all, we are the worst feature set now with TCP
633 * sockets, and there's really no point in retrying. */
634 if (t->state == DNS_TRANSACTION_PENDING)
635 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
636 else
637 dns_transaction_gc(t);
638
639 return 0;
640}
641
642static int on_stream_complete(DnsStream *s, int error) {
643 assert(s);
644
645 if (ERRNO_IS_DISCONNECT(error) && s->protocol != DNS_PROTOCOL_LLMNR) {
646 log_debug_errno(error, "Connection failure for DNS TCP stream: %m");
647
648 if (error != ECONNRESET && s->transactions) {
649 DnsTransaction *t;
650
651 t = s->transactions;
652 dns_server_packet_lost(t->server, IPPROTO_TCP, t->current_feature_level);
653 }
654 }
655
656 if (error != 0) {
657 /* First, detach the stream from the server. Otherwise, transactions attached to this stream
658 * may be restarted by on_transaction_stream_error() below with this stream. */
659 dns_stream_detach(s);
660
661 /* Do not use LIST_FOREACH() here, as
662 * on_transaction_stream_error()
663 * -> dns_transaction_complete_errno()
664 * -> dns_transaction_free()
665 * may free multiple transactions in the list. */
666 DnsTransaction *t;
667 while ((t = s->transactions))
668 on_transaction_stream_error(t, error);
669 }
670
671 return 0;
672}
673
674static int on_stream_packet(DnsStream *s, DnsPacket *p) {
675 DnsTransaction *t;
676
677 assert(s);
678 assert(s->manager);
679 assert(p);
680
681 t = hashmap_get(s->manager->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
682 if (t && t->stream == s) /* Validate that the stream we got this on actually is the stream the
683 * transaction was using. */
684 return dns_transaction_on_stream_packet(t, s, p);
685
686 /* Ignore incorrect transaction id as an old transaction can have been canceled. */
687 log_debug("Received unexpected TCP reply packet with id %" PRIu16 ", ignoring.", DNS_PACKET_ID(p));
688 return 0;
689}
690
691static uint16_t dns_transaction_port(DnsTransaction *t) {
692 assert(t);
693
694 if (t->server->port > 0)
695 return t->server->port;
696
697 return DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) ? 853 : 53;
698}
699
700static int dns_transaction_emit_tcp(DnsTransaction *t) {
701 usec_t stream_timeout_usec = DNS_STREAM_DEFAULT_TIMEOUT_USEC;
702 _cleanup_(dns_stream_unrefp) DnsStream *s = NULL;
703 _cleanup_close_ int fd = -EBADF;
704 union sockaddr_union sa;
705 DnsStreamType type;
706 int r;
707
708 assert(t);
709 assert(t->sent);
710
711 dns_transaction_close_connection(t, true);
712
713 switch (t->scope->protocol) {
714
715 case DNS_PROTOCOL_DNS:
716 r = dns_transaction_pick_server(t);
717 if (r < 0)
718 return r;
719
720 if (manager_server_is_stub(t->scope->manager, t->server))
721 return -ELOOP;
722
723 if (!t->bypass) {
724 if (!dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type))
725 return -EOPNOTSUPP;
726
727 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
728 if (r < 0)
729 return r;
730 }
731
732 if (t->server->stream && (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) == t->server->stream->encrypted))
733 s = dns_stream_ref(t->server->stream);
734 else
735 fd = dns_scope_socket_tcp(t->scope, AF_UNSPEC, NULL, t->server, dns_transaction_port(t), &sa);
736
737 /* Lower timeout in DNS-over-TLS opportunistic mode. In environments where DoT is blocked
738 * without ICMP response overly long delays when contacting DoT servers are nasty, in
739 * particular if multiple DNS servers are defined which we try in turn and all are
740 * blocked. Hence, substantially lower the timeout in that case. */
741 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level) &&
742 dns_server_get_dns_over_tls_mode(t->server) == DNS_OVER_TLS_OPPORTUNISTIC)
743 stream_timeout_usec = DNS_STREAM_OPPORTUNISTIC_TLS_TIMEOUT_USEC;
744
745 type = DNS_STREAM_LOOKUP;
746 break;
747
748 case DNS_PROTOCOL_LLMNR:
749 /* When we already received a reply to this (but it was truncated), send to its sender address */
750 if (t->received)
751 fd = dns_scope_socket_tcp(t->scope, t->received->family, &t->received->sender, NULL, t->received->sender_port, &sa);
752 else {
753 union in_addr_union address;
754 int family = AF_UNSPEC;
755
756 /* Otherwise, try to talk to the owner of a
757 * the IP address, in case this is a reverse
758 * PTR lookup */
759
760 r = dns_name_address(dns_resource_key_name(dns_transaction_key(t)), &family, &address);
761 if (r < 0)
762 return r;
763 if (r == 0)
764 return -EINVAL;
765 if (family != t->scope->family)
766 return -ESRCH;
767
768 fd = dns_scope_socket_tcp(t->scope, family, &address, NULL, LLMNR_PORT, &sa);
769 }
770
771 type = DNS_STREAM_LLMNR_SEND;
772 break;
773
774 default:
775 return -EAFNOSUPPORT;
776 }
777
778 if (!s) {
779 if (fd < 0)
780 return fd;
781
782 r = dns_stream_new(t->scope->manager, &s, type, t->scope->protocol, fd, &sa,
783 on_stream_packet, on_stream_complete, stream_timeout_usec);
784 if (r < 0)
785 return r;
786
787 fd = -EBADF;
788
789#if ENABLE_DNS_OVER_TLS
790 if (t->scope->protocol == DNS_PROTOCOL_DNS &&
791 DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level)) {
792
793 assert(t->server);
794 r = dnstls_stream_connect_tls(s, t->server);
795 if (r < 0)
796 return r;
797 }
798#endif
799
800 if (t->server) {
801 dns_server_unref_stream(t->server);
802 s->server = dns_server_ref(t->server);
803 t->server->stream = dns_stream_ref(s);
804 }
805
806 /* The interface index is difficult to determine if we are
807 * connecting to the local host, hence fill this in right away
808 * instead of determining it from the socket */
809 s->ifindex = dns_scope_ifindex(t->scope);
810 }
811
812 t->stream = TAKE_PTR(s);
813 LIST_PREPEND(transactions_by_stream, t->stream->transactions, t);
814
815 r = dns_stream_write_packet(t->stream, t->sent);
816 if (r < 0) {
817 dns_transaction_close_connection(t, /* use_graveyard= */ false);
818 return r;
819 }
820
821 dns_transaction_reset_answer(t);
822
823 t->tried_stream = true;
824
825 return 0;
826}
827
828static void dns_transaction_cache_answer(DnsTransaction *t) {
829 assert(t);
830
831 /* For mDNS we cache whenever we get the packet, rather than
832 * in each transaction. */
833 if (!IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR))
834 return;
835
836 /* Caching disabled? */
837 if (t->scope->manager->enable_cache == DNS_CACHE_MODE_NO)
838 return;
839
840 /* If validation is turned off for this transaction, but DNSSEC is on, then let's not cache this */
841 if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) && t->scope->dnssec_mode != DNSSEC_NO)
842 return;
843
844 /* Packet from localhost? */
845 if (!t->scope->manager->cache_from_localhost &&
846 in_addr_is_localhost(t->received->family, &t->received->sender) != 0)
847 return;
848
849 dns_cache_put(&t->scope->cache,
850 t->scope->manager->enable_cache,
851 t->scope->protocol,
852 dns_transaction_key(t),
853 t->answer_rcode,
854 t->answer,
855 /* If neither DO nor EDE is set, the full packet isn't useful to cache */
856 dns_packet_do(t->received) || t->answer_ede_rcode > 0 || t->answer_ede_msg ? t->received : NULL,
857 t->answer_query_flags,
858 t->answer_dnssec_result,
859 t->answer_nsec_ttl,
860 t->received->family,
861 &t->received->sender,
862 t->scope->manager->stale_retention_usec);
863}
864
865static bool dns_transaction_dnssec_is_live(DnsTransaction *t) {
866 DnsTransaction *dt;
867
868 assert(t);
869
870 SET_FOREACH(dt, t->dnssec_transactions)
871 if (DNS_TRANSACTION_IS_LIVE(dt->state))
872 return true;
873
874 return false;
875}
876
877static int dns_transaction_dnssec_ready(DnsTransaction *t) {
878 DnsTransaction *dt;
879 int r;
880
881 assert(t);
882
883 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
884 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
885
886 SET_FOREACH(dt, t->dnssec_transactions) {
887
888 switch (dt->state) {
889
890 case DNS_TRANSACTION_NULL:
891 case DNS_TRANSACTION_PENDING:
892 case DNS_TRANSACTION_VALIDATING:
893 /* Still ongoing */
894 return 0;
895
896 case DNS_TRANSACTION_RCODE_FAILURE:
897 if (!IN_SET(dt->answer_rcode, DNS_RCODE_NXDOMAIN, DNS_RCODE_SERVFAIL)) {
898 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", FORMAT_DNS_RCODE(dt->answer_rcode));
899 goto fail;
900 }
901
902 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
903 * erroneously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
904 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
905 * RRs to make unsigned proofs. */
906
907 case DNS_TRANSACTION_SUCCESS:
908 /* All good. */
909 break;
910
911 case DNS_TRANSACTION_DNSSEC_FAILED:
912 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
913 * validation result */
914
915 log_debug("Auxiliary DNSSEC RR query failed validation: %s%s%s%s%s%s",
916 dnssec_result_to_string(dt->answer_dnssec_result),
917 dt->answer_ede_rcode >= 0 ? " (" : "",
918 dt->answer_ede_rcode >= 0 ? FORMAT_DNS_EDE_RCODE(dt->answer_ede_rcode) : "",
919 (dt->answer_ede_rcode >= 0 && !isempty(dt->answer_ede_msg)) ? ": " : "",
920 dt->answer_ede_rcode >= 0 ? strempty(dt->answer_ede_msg) : "",
921 dt->answer_ede_rcode >= 0 ? ")" : "");
922
923 /* Copy error code over */
924 t->answer_dnssec_result = dt->answer_dnssec_result;
925 t->answer_ede_rcode = dt->answer_ede_rcode;
926 r = free_and_strdup(&t->answer_ede_msg, dt->answer_ede_msg);
927 if (r < 0)
928 log_oom_debug();
929
930 /* The answer would normally be replaced by the validated subset, but at this point
931 * we aren't going to bother validating the rest, so just drop it. */
932 t->answer = dns_answer_unref(t->answer);
933
934 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
935 return 0;
936
937 default:
938 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt->state));
939 goto fail;
940 }
941 }
942
943 /* All is ready, we can go and validate */
944 return 1;
945
946fail:
947 /* Some auxiliary DNSSEC transaction failed for some reason. Maybe we learned something about the
948 * server due to this failure, and the feature level is now different? Let's see and restart the
949 * transaction if so. If not, let's propagate the auxiliary failure.
950 *
951 * This is particularly relevant if an auxiliary request figured out that DNSSEC doesn't work, and we
952 * are in permissive DNSSEC mode, and thus should restart things without DNSSEC magic. */
953 r = dns_transaction_maybe_restart(t);
954 if (r < 0)
955 return r;
956 if (r > 0)
957 return 0; /* don't validate just yet, we restarted things */
958
959 t->answer_dnssec_result = DNSSEC_FAILED_AUXILIARY;
960 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
961 return 0;
962}
963
964static void dns_transaction_process_dnssec(DnsTransaction *t) {
965 int r;
966
967 assert(t);
968
969 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
970 r = dns_transaction_dnssec_ready(t);
971 if (r < 0)
972 goto fail;
973 if (r == 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
974 return;
975
976 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
977 * restart the lookup immediately. */
978 r = dns_transaction_maybe_restart(t);
979 if (r < 0)
980 goto fail;
981 if (r > 0) /* Transaction got restarted... */
982 return;
983
984 /* All our auxiliary DNSSEC transactions are complete now. Try
985 * to validate our RRset now. */
986 r = dns_transaction_validate_dnssec(t);
987 if (r == -EBADMSG) {
988 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
989 return;
990 }
991 if (r < 0)
992 goto fail;
993
994 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER &&
995 t->scope->dnssec_mode == DNSSEC_YES) {
996
997 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
998 * that works. */
999
1000 if (dns_transaction_limited_retry(t))
1001 return;
1002
1003 /* OK, let's give up, apparently all servers we tried didn't work. */
1004 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
1005 return;
1006 }
1007
1008 if (!IN_SET(t->answer_dnssec_result,
1009 _DNSSEC_RESULT_INVALID, /* No DNSSEC validation enabled */
1010 DNSSEC_VALIDATED, /* Answer is signed and validated successfully */
1011 DNSSEC_UNSIGNED, /* Answer is right-fully unsigned */
1012 DNSSEC_INCOMPATIBLE_SERVER)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
1013 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
1014 return;
1015 }
1016
1017 if (t->answer_dnssec_result == DNSSEC_INCOMPATIBLE_SERVER)
1018 dns_server_warn_downgrade(t->server);
1019
1020 dns_transaction_cache_answer(t);
1021
1022 if (t->answer_rcode == DNS_RCODE_SUCCESS)
1023 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1024 else
1025 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
1026
1027 return;
1028
1029fail:
1030 dns_transaction_complete_errno(t, r);
1031}
1032
1033static int dns_transaction_has_positive_answer(DnsTransaction *t, DnsAnswerFlags *flags) {
1034 int r;
1035
1036 assert(t);
1037
1038 /* Checks whether the answer is positive, i.e. either a direct
1039 * answer to the question, or a CNAME/DNAME for it */
1040
1041 r = dns_answer_match_key(t->answer, dns_transaction_key(t), flags);
1042 if (r != 0)
1043 return r;
1044
1045 r = dns_answer_find_cname_or_dname(t->answer, dns_transaction_key(t), NULL, flags);
1046 if (r != 0)
1047 return r;
1048
1049 return false;
1050}
1051
1052static int dns_transaction_fix_rcode(DnsTransaction *t) {
1053 int r;
1054
1055 assert(t);
1056
1057 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
1058 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
1059 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
1060 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
1061 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
1062 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
1063 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
1064 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
1065 * incomplete CNAME/DNAME chain.
1066 *
1067 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
1068 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
1069 * lookup. */
1070
1071 if (t->answer_rcode != DNS_RCODE_NXDOMAIN)
1072 return 0;
1073
1074 r = dns_transaction_has_positive_answer(t, NULL);
1075 if (r <= 0)
1076 return r;
1077
1078 t->answer_rcode = DNS_RCODE_SUCCESS;
1079 return 0;
1080}
1081
1082void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p, bool encrypted) {
1083 bool retry_with_tcp = false;
1084 int r;
1085
1086 assert(t);
1087 assert(p);
1088 assert(t->scope);
1089 assert(t->scope->manager);
1090
1091 if (t->state != DNS_TRANSACTION_PENDING)
1092 return;
1093
1094 /* Increment the total failure counter only when it is the first attempt at querying and the upstream
1095 * server returns a failure response code. This ensures a more accurate count of the number of queries
1096 * that received a failure response code, as it doesn't consider retries. */
1097
1098 if (t->n_attempts == 1 && !IN_SET(dns_packet_rcode(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN))
1099 t->scope->manager->n_failure_responses_total++;
1100
1101 /* Note that this call might invalidate the query. Callers
1102 * should hence not attempt to access the query or transaction
1103 * after calling this function. */
1104
1105 log_debug("Processing incoming packet of size %zu on transaction %" PRIu16" (rcode=%s).",
1106 p->size,
1107 t->id, FORMAT_DNS_RCODE(dns_packet_rcode(p)));
1108
1109 switch (t->scope->protocol) {
1110
1111 case DNS_PROTOCOL_LLMNR:
1112 /* For LLMNR we will not accept any packets from other interfaces */
1113
1114 if (p->ifindex != dns_scope_ifindex(t->scope))
1115 return;
1116
1117 if (p->family != t->scope->family)
1118 return;
1119
1120 /* Tentative packets are not full responses but still
1121 * useful for identifying uniqueness conflicts during
1122 * probing. */
1123 if (DNS_PACKET_LLMNR_T(p)) {
1124 dns_transaction_tentative(t, p);
1125 return;
1126 }
1127
1128 break;
1129
1130 case DNS_PROTOCOL_MDNS:
1131 /* For mDNS we will not accept any packets from other interfaces */
1132
1133 if (p->ifindex != dns_scope_ifindex(t->scope))
1134 return;
1135
1136 if (p->family != t->scope->family)
1137 return;
1138
1139 break;
1140
1141 case DNS_PROTOCOL_DNS:
1142 /* Note that we do not need to verify the
1143 * addresses/port numbers of incoming traffic, as we
1144 * invoked connect() on our UDP socket in which case
1145 * the kernel already does the needed verification for
1146 * us. */
1147 break;
1148
1149 default:
1150 assert_not_reached();
1151 }
1152
1153 if (t->received != p)
1154 DNS_PACKET_REPLACE(t->received, dns_packet_ref(p));
1155
1156 t->answer_source = DNS_TRANSACTION_NETWORK;
1157
1158 if (p->ipproto == IPPROTO_TCP) {
1159 if (DNS_PACKET_TC(p)) {
1160 /* Truncated via TCP? Somebody must be fucking with us */
1161 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1162 return;
1163 }
1164
1165 if (DNS_PACKET_ID(p) != t->id) {
1166 /* Not the reply to our query? Somebody must be fucking with us */
1167 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1168 return;
1169 }
1170 }
1171
1172 if (DNS_PACKET_TC(p)) {
1173
1174 /* Truncated packets for mDNS are not allowed. Give up immediately. */
1175 if (t->scope->protocol == DNS_PROTOCOL_MDNS) {
1176 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1177 return;
1178 }
1179
1180 /* Response was truncated, let's try again with good old TCP */
1181 log_debug("Reply truncated, retrying via TCP.");
1182 retry_with_tcp = true;
1183
1184 } else if (t->scope->protocol == DNS_PROTOCOL_DNS &&
1185 DNS_PACKET_IS_FRAGMENTED(p)) {
1186
1187 /* Report the fragment size, so that we downgrade from LARGE to regular EDNS0 if needed */
1188 if (t->server)
1189 dns_server_packet_udp_fragmented(t->server, dns_packet_size_unfragmented(p));
1190
1191 if (t->current_feature_level > DNS_SERVER_FEATURE_LEVEL_UDP) {
1192 /* Packet was fragmented. Let's retry with TCP to avoid fragmentation attack
1193 * issues. (We don't do that on the lowest feature level however, since crappy DNS
1194 * servers often do not implement TCP, hence falling back to TCP on fragmentation is
1195 * counter-productive there.) */
1196
1197 log_debug("Reply fragmented, retrying via TCP. (Largest fragment size: %zu; Datagram size: %zu)",
1198 p->fragsize, p->size);
1199 retry_with_tcp = true;
1200 }
1201 }
1202
1203 if (retry_with_tcp) {
1204 r = dns_transaction_emit_tcp(t);
1205 if (r == -ESRCH) {
1206 /* No servers found? Damn! */
1207 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
1208 return;
1209 }
1210 if (r == -EOPNOTSUPP) {
1211 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1212 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
1213 return;
1214 }
1215 if (r < 0) {
1216 /* On LLMNR, if we cannot connect to the host,
1217 * we immediately give up */
1218 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1219 goto fail;
1220
1221 /* On DNS, couldn't send? Try immediately again, with a new server */
1222 if (dns_transaction_limited_retry(t))
1223 return;
1224
1225 /* No new server to try, give up */
1226 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1227 }
1228
1229 return;
1230 }
1231
1232 /* After the superficial checks, actually parse the message. */
1233 r = dns_packet_extract(p);
1234 if (r < 0) {
1235 if (t->server) {
1236 dns_server_packet_invalid(t->server, t->current_feature_level);
1237
1238 r = dns_transaction_maybe_restart(t);
1239 if (r < 0)
1240 goto fail;
1241 if (r > 0) /* Transaction got restarted... */
1242 return;
1243 }
1244
1245 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1246 return;
1247 }
1248
1249 switch (t->scope->protocol) {
1250
1251 case DNS_PROTOCOL_DNS: {
1252 assert(t->server);
1253
1254 (void) dns_packet_ede_rcode(p, &t->answer_ede_rcode, &t->answer_ede_msg);
1255
1256 if (!t->bypass &&
1257 IN_SET(dns_packet_rcode(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
1258 /* If the server has replied with detailed error data, using a degraded feature set
1259 * will likely not help anyone. Examine the detailed error to determine the best
1260 * course of action. */
1261 if (t->answer_ede_rcode >= 0 && dns_packet_rcode(p) == DNS_RCODE_SERVFAIL) {
1262 /* These codes are related to DNSSEC configuration errors. If accurate,
1263 * this is the domain operator's problem, and retrying won't help. */
1264 if (dns_ede_rcode_is_dnssec(t->answer_ede_rcode)) {
1265 log_debug("Server returned error: %s (%s%s%s). Lookup failed.",
1266 FORMAT_DNS_RCODE(dns_packet_rcode(p)),
1267 FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode),
1268 isempty(t->answer_ede_msg) ? "" : ": ",
1269 strempty(t->answer_ede_msg));
1270
1271 t->answer_dnssec_result = DNSSEC_UPSTREAM_FAILURE;
1272 dns_transaction_complete(t, DNS_TRANSACTION_DNSSEC_FAILED);
1273 return;
1274 }
1275
1276 /* These codes probably indicate a transient error. Let's try again. */
1277 if (t->answer_ede_rcode == DNS_EDE_RCODE_NOT_READY) {
1278 log_debug("Server returned error: %s (%s%s%s), retrying transaction.",
1279 FORMAT_DNS_RCODE(dns_packet_rcode(p)),
1280 FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode),
1281 isempty(t->answer_ede_msg) ? "" : ": ",
1282 strempty(t->answer_ede_msg));
1283 dns_transaction_retry(t, false);
1284 return;
1285 }
1286
1287 /* OK, the query failed, but we still shouldn't degrade the feature set for
1288 * this server. */
1289 log_debug("Server returned error: %s (%s%s%s)",
1290 FORMAT_DNS_RCODE(dns_packet_rcode(p)),
1291 FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode),
1292 isempty(t->answer_ede_msg) ? "" : ": ",
1293 strempty(t->answer_ede_msg));
1294 break;
1295 }
1296
1297 /* Request failed, immediately try again with reduced features */
1298
1299 if (t->current_feature_level <= DNS_SERVER_FEATURE_LEVEL_UDP) {
1300
1301 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
1302 * this transaction anymore, but let's see if it might make sense to send the request
1303 * to a different DNS server instead. If not let's process the response, and accept the
1304 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
1305 * packet loss, but is not going to give us better rcodes should we actually have
1306 * managed to get them already at UDP level. */
1307
1308 if (dns_transaction_limited_retry(t))
1309 return;
1310
1311 /* Give up, accept the rcode */
1312 log_debug("Server returned error: %s", FORMAT_DNS_RCODE(dns_packet_rcode(p)));
1313 break;
1314 }
1315
1316 /* SERVFAIL can happen for many reasons and may be transient.
1317 * To avoid unnecessary downgrades retry once with the initial level.
1318 * Check for clamp_feature_level_servfail having an invalid value as a sign that this is the
1319 * first attempt to downgrade. If so, clamp to the current value so that the transaction
1320 * is retried without actually downgrading. If the next try also fails we will downgrade by
1321 * hitting the else branch below. */
1322 if (dns_packet_rcode(p) == DNS_RCODE_SERVFAIL &&
1323 t->clamp_feature_level_servfail < 0) {
1324 t->clamp_feature_level_servfail = t->current_feature_level;
1325 log_debug("Server returned error %s, retrying transaction.",
1326 FORMAT_DNS_RCODE(dns_packet_rcode(p)));
1327 } else {
1328 /* Reduce this feature level by one and try again. */
1329 switch (t->current_feature_level) {
1330 case DNS_SERVER_FEATURE_LEVEL_TLS_DO:
1331 t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN;
1332 break;
1333 case DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN + 1:
1334 /* Skip plain TLS when TLS is not supported */
1335 t->clamp_feature_level_servfail = DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN - 1;
1336 break;
1337 default:
1338 t->clamp_feature_level_servfail = t->current_feature_level - 1;
1339 }
1340
1341 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
1342 FORMAT_DNS_RCODE(dns_packet_rcode(p)),
1343 dns_server_feature_level_to_string(t->clamp_feature_level_servfail));
1344 }
1345
1346 dns_transaction_retry(t, false /* use the same server */);
1347 return;
1348 }
1349
1350 if (dns_packet_rcode(p) == DNS_RCODE_REFUSED) {
1351 /* This server refused our request? If so, try again, use a different server */
1352 if (t->answer_ede_rcode >= 0)
1353 log_debug("Server returned REFUSED (%s), switching servers, and retrying.",
1354 FORMAT_DNS_EDE_RCODE(t->answer_ede_rcode));
1355 else
1356 log_debug("Server returned REFUSED, switching servers, and retrying.");
1357
1358 if (dns_transaction_limited_retry(t))
1359 return;
1360
1361 break;
1362 }
1363
1364 if (DNS_PACKET_TC(p))
1365 dns_server_packet_truncated(t->server, t->current_feature_level);
1366
1367 break;
1368 }
1369
1370 case DNS_PROTOCOL_LLMNR:
1371 case DNS_PROTOCOL_MDNS:
1372 dns_scope_packet_received(t->scope, p->timestamp - t->start_usec);
1373 break;
1374
1375 default:
1376 assert_not_reached();
1377 }
1378
1379 if (t->server) {
1380 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1381 * rcode and subsequently downgraded the protocol */
1382
1383 if (IN_SET(dns_packet_rcode(p), DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN) &&
1384 t->clamp_feature_level_servfail != _DNS_SERVER_FEATURE_LEVEL_INVALID)
1385 dns_server_packet_rcode_downgrade(t->server, t->clamp_feature_level_servfail);
1386
1387 /* Report that the OPT RR was missing */
1388 if (!p->opt)
1389 dns_server_packet_bad_opt(t->server, t->current_feature_level);
1390
1391 /* Report that the server didn't copy our query DO bit from request to response */
1392 if (dns_packet_do(t->sent) && !dns_packet_do(t->received))
1393 dns_server_packet_do_off(t->server, t->current_feature_level);
1394
1395 /* Report that we successfully received a packet. We keep track of the largest packet
1396 * size/fragment size we got. Which is useful for announcing the EDNS(0) packet size we can
1397 * receive to our server. */
1398 dns_server_packet_received(t->server, p->ipproto, t->current_feature_level, dns_packet_size_unfragmented(p));
1399 }
1400
1401 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1402 r = dns_transaction_maybe_restart(t);
1403 if (r < 0)
1404 goto fail;
1405 if (r > 0) /* Transaction got restarted... */
1406 return;
1407
1408 /* When dealing with protocols other than mDNS only consider responses with equivalent query section
1409 * to the request. For mDNS this check doesn't make sense, because the section 6 of RFC6762 states
1410 * that "Multicast DNS responses MUST NOT contain any questions in the Question Section". */
1411 if (t->scope->protocol != DNS_PROTOCOL_MDNS) {
1412 r = dns_packet_is_reply_for(p, dns_transaction_key(t));
1413 if (r < 0)
1414 goto fail;
1415 if (r == 0) {
1416 dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
1417 return;
1418 }
1419 }
1420
1421 /* Install the answer as answer to the transaction. We ref the answer twice here: the main `answer`
1422 * field is later replaced by the DNSSEC validated subset. The 'answer_auxiliary' field carries the
1423 * original complete record set, including RRSIG and friends. We use this when passing data to
1424 * clients that ask for DNSSEC metadata. */
1425 DNS_ANSWER_REPLACE(t->answer, dns_answer_ref(p->answer));
1426 t->answer_rcode = dns_packet_rcode(p);
1427 t->answer_dnssec_result = _DNSSEC_RESULT_INVALID;
1428 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false);
1429 SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, encrypted);
1430
1431 r = dns_transaction_fix_rcode(t);
1432 if (r < 0)
1433 goto fail;
1434
1435 /* Block GC while starting requests for additional DNSSEC RRs */
1436 t->block_gc++;
1437 r = dns_transaction_request_dnssec_keys(t);
1438 t->block_gc--;
1439
1440 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1441 if (!dns_transaction_gc(t))
1442 return;
1443
1444 /* Requesting additional keys might have resulted in this transaction to fail, since the auxiliary
1445 * request failed for some reason. If so, we are not in pending state anymore, and we should exit
1446 * quickly. */
1447 if (t->state != DNS_TRANSACTION_PENDING)
1448 return;
1449 if (r < 0)
1450 goto fail;
1451 if (r > 0) {
1452 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1453 t->state = DNS_TRANSACTION_VALIDATING;
1454 dns_transaction_close_connection(t, true);
1455 dns_transaction_stop_timeout(t);
1456 return;
1457 }
1458
1459 dns_transaction_process_dnssec(t);
1460 return;
1461
1462fail:
1463 dns_transaction_complete_errno(t, r);
1464}
1465
1466static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
1467 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1468 DnsTransaction *t = ASSERT_PTR(userdata);
1469 int r;
1470
1471 assert(t->scope);
1472
1473 r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
1474 if (r < 0) {
1475 if (ERRNO_IS_DISCONNECT(r)) {
1476 usec_t usec;
1477
1478 /* UDP connection failures get reported via ICMP and then are possibly delivered to us on the
1479 * next recvmsg(). Treat this like a lost packet. */
1480
1481 log_debug_errno(r, "Connection failure for DNS UDP packet: %m");
1482 assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &usec) >= 0);
1483 dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level);
1484
1485 dns_transaction_close_connection(t, /* use_graveyard = */ false);
1486
1487 if (dns_transaction_limited_retry(t)) /* Try a different server */
1488 return 0;
1489 }
1490 dns_transaction_complete_errno(t, r);
1491 return 0;
1492 }
1493 if (r == 0)
1494 /* Spurious wakeup without any data */
1495 return 0;
1496
1497 r = dns_packet_validate_reply(p);
1498 if (r < 0) {
1499 log_debug_errno(r, "Received invalid DNS packet as response, ignoring: %m");
1500 return 0;
1501 }
1502 if (r == 0) {
1503 log_debug("Received inappropriate DNS packet as response, ignoring.");
1504 return 0;
1505 }
1506
1507 if (DNS_PACKET_ID(p) != t->id) {
1508 log_debug("Received packet with incorrect transaction ID, ignoring.");
1509 return 0;
1510 }
1511
1512 dns_transaction_process_reply(t, p, false);
1513 return 0;
1514}
1515
1516static int dns_transaction_emit_udp(DnsTransaction *t) {
1517 int r;
1518
1519 assert(t);
1520
1521 if (t->scope->protocol == DNS_PROTOCOL_DNS) {
1522
1523 r = dns_transaction_pick_server(t);
1524 if (r < 0)
1525 return r;
1526
1527 if (manager_server_is_stub(t->scope->manager, t->server))
1528 return -ELOOP;
1529
1530 if (t->current_feature_level < DNS_SERVER_FEATURE_LEVEL_UDP || DNS_SERVER_FEATURE_LEVEL_IS_TLS(t->current_feature_level))
1531 return -EAGAIN; /* Sorry, can't do UDP, try TCP! */
1532
1533 if (!t->bypass && !dns_server_dnssec_supported(t->server) && dns_type_is_dnssec(dns_transaction_key(t)->type))
1534 return -EOPNOTSUPP;
1535
1536 if (r > 0 || t->dns_udp_fd < 0) { /* Server changed, or no connection yet. */
1537 int fd;
1538
1539 dns_transaction_close_connection(t, true);
1540
1541 /* Before we allocate a new UDP socket, let's process the graveyard a bit to free some fds */
1542 manager_socket_graveyard_process(t->scope->manager);
1543
1544 fd = dns_scope_socket_udp(t->scope, t->server);
1545 if (fd < 0)
1546 return fd;
1547
1548 r = sd_event_add_io(t->scope->manager->event, &t->dns_udp_event_source, fd, EPOLLIN, on_dns_packet, t);
1549 if (r < 0) {
1550 safe_close(fd);
1551 return r;
1552 }
1553
1554 (void) sd_event_source_set_description(t->dns_udp_event_source, "dns-transaction-udp");
1555 t->dns_udp_fd = fd;
1556 }
1557
1558 if (!t->bypass) {
1559 r = dns_server_adjust_opt(t->server, t->sent, t->current_feature_level);
1560 if (r < 0)
1561 return r;
1562 }
1563 } else
1564 dns_transaction_close_connection(t, true);
1565
1566 r = dns_scope_emit_udp(t->scope, t->dns_udp_fd, t->server ? t->server->family : AF_UNSPEC, t->sent);
1567 if (r < 0)
1568 return r;
1569
1570 dns_transaction_reset_answer(t);
1571
1572 return 0;
1573}
1574
1575static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1576 DnsTransaction *t = ASSERT_PTR(userdata);
1577
1578 assert(s);
1579
1580 t->seen_timeout = true;
1581
1582 if (t->initial_jitter_scheduled && !t->initial_jitter_elapsed) {
1583 log_debug("Initial jitter phase for transaction %" PRIu16 " elapsed.", t->id);
1584 t->initial_jitter_elapsed = true;
1585 } else {
1586 /* Timeout reached? Increase the timeout for the server used */
1587 switch (t->scope->protocol) {
1588
1589 case DNS_PROTOCOL_DNS:
1590 assert(t->server);
1591 dns_server_packet_lost(t->server, t->stream ? IPPROTO_TCP : IPPROTO_UDP, t->current_feature_level);
1592 break;
1593
1594 case DNS_PROTOCOL_LLMNR:
1595 case DNS_PROTOCOL_MDNS:
1596 dns_scope_packet_lost(t->scope, usec - t->start_usec);
1597 break;
1598
1599 default:
1600 assert_not_reached();
1601 }
1602
1603 log_debug("Timeout reached on transaction %" PRIu16 ".", t->id);
1604 }
1605
1606 dns_transaction_retry(t, /* next_server= */ true); /* try a different server, but given this means
1607 * packet loss, let's do so even if we already
1608 * tried a bunch */
1609 return 0;
1610}
1611
1612static int dns_transaction_setup_timeout(
1613 DnsTransaction *t,
1614 usec_t timeout_usec /* relative */,
1615 usec_t next_usec /* CLOCK_BOOTTIME */) {
1616
1617 int r;
1618
1619 assert(t);
1620
1621 dns_transaction_stop_timeout(t);
1622
1623 r = sd_event_add_time_relative(
1624 t->scope->manager->event,
1625 &t->timeout_event_source,
1626 CLOCK_BOOTTIME,
1627 timeout_usec, 0,
1628 on_transaction_timeout, t);
1629 if (r < 0)
1630 return r;
1631
1632 (void) sd_event_source_set_description(t->timeout_event_source, "dns-transaction-timeout");
1633
1634 t->next_attempt_after = next_usec;
1635 t->state = DNS_TRANSACTION_PENDING;
1636 return 0;
1637}
1638
1639static usec_t transaction_get_resend_timeout(DnsTransaction *t) {
1640 assert(t);
1641 assert(t->scope);
1642
1643 switch (t->scope->protocol) {
1644
1645 case DNS_PROTOCOL_DNS:
1646
1647 if (t->stream)
1648 return TRANSACTION_TCP_TIMEOUT_USEC;
1649
1650 return TRANSACTION_UDP_TIMEOUT_USEC;
1651
1652 case DNS_PROTOCOL_MDNS:
1653 if (t->probing)
1654 return MDNS_PROBING_INTERVAL_USEC;
1655
1656 /* See RFC 6762 Section 5.1 suggests that timeout should be a few seconds. */
1657 assert(t->n_attempts > 0);
1658 return (1 << (t->n_attempts - 1)) * USEC_PER_SEC;
1659
1660 case DNS_PROTOCOL_LLMNR:
1661 return t->scope->resend_timeout;
1662
1663 default:
1664 assert_not_reached();
1665 }
1666}
1667
1668static void dns_transaction_randomize_answer(DnsTransaction *t) {
1669 int r;
1670
1671 assert(t);
1672
1673 /* Randomizes the order of the answer array. This is done for all cached responses, so that we return
1674 * a different order each time. We do this only for DNS traffic, in order to do some minimal, crappy
1675 * load balancing. We don't do this for LLMNR or mDNS, since the order (preferring link-local
1676 * addresses, and such like) might have meaning there, and load balancing is pointless. */
1677
1678 if (t->scope->protocol != DNS_PROTOCOL_DNS)
1679 return;
1680
1681 /* No point in randomizing, if there's just one RR */
1682 if (dns_answer_size(t->answer) <= 1)
1683 return;
1684
1685 r = dns_answer_reserve_or_clone(&t->answer, 0);
1686 if (r < 0) /* If this fails, just don't randomize, this is non-essential stuff after all */
1687 return (void) log_debug_errno(r, "Failed to clone answer record, not randomizing RR order of answer: %m");
1688
1689 dns_answer_randomize(t->answer);
1690}
1691
1692static int dns_transaction_prepare(DnsTransaction *t, usec_t ts) {
1693 int r;
1694
1695 assert(t);
1696
1697 /* Returns 0 if dns_transaction_complete() has been called. In that case the transaction and query
1698 * candidate objects may have been invalidated and must not be accessed. Returns 1 if the transaction
1699 * has been prepared. */
1700
1701 dns_transaction_stop_timeout(t);
1702
1703 if (t->n_attempts == 1 && t->seen_timeout)
1704 t->scope->manager->n_timeouts_total++;
1705
1706 if (!dns_scope_network_good(t->scope)) {
1707 dns_transaction_complete(t, DNS_TRANSACTION_NETWORK_DOWN);
1708 return 0;
1709 }
1710
1711 if (t->n_attempts >= TRANSACTION_ATTEMPTS_MAX(t->scope->protocol)) {
1712 DnsTransactionState result;
1713
1714 if (t->scope->protocol == DNS_PROTOCOL_LLMNR)
1715 /* If we didn't find anything on LLMNR, it's not an error, but a failure to resolve
1716 * the name. */
1717 result = DNS_TRANSACTION_NOT_FOUND;
1718 else
1719 result = DNS_TRANSACTION_ATTEMPTS_MAX_REACHED;
1720
1721 dns_transaction_complete(t, result);
1722 return 0;
1723 }
1724
1725 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && t->tried_stream) {
1726 /* If we already tried via a stream, then we don't
1727 * retry on LLMNR. See RFC 4795, Section 2.7. */
1728 dns_transaction_complete(t, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED);
1729 return 0;
1730 }
1731
1732 t->n_attempts++;
1733 t->start_usec = ts;
1734
1735 dns_transaction_reset_answer(t);
1736 dns_transaction_flush_dnssec_transactions(t);
1737
1738 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1739 if (t->scope->protocol == DNS_PROTOCOL_DNS &&
1740 !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_TRUST_ANCHOR)) {
1741 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, dns_transaction_key(t), &t->answer);
1742 if (r < 0)
1743 return r;
1744 if (r > 0) {
1745 t->answer_rcode = DNS_RCODE_SUCCESS;
1746 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1747 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true);
1748 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1749 return 0;
1750 }
1751
1752 if (dns_name_is_root(dns_resource_key_name(dns_transaction_key(t))) &&
1753 dns_transaction_key(t)->type == DNS_TYPE_DS) {
1754
1755 /* Hmm, this is a request for the root DS? A DS RR doesn't exist in the root zone,
1756 * and if our trust anchor didn't know it either, this means we cannot do any DNSSEC
1757 * logic anymore. */
1758
1759 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
1760 /* We are in downgrade mode. In this case, synthesize an unsigned empty
1761 * response, so that the any lookup depending on this one can continue
1762 * assuming there was no DS, and hence the root zone was unsigned. */
1763
1764 t->answer_rcode = DNS_RCODE_SUCCESS;
1765 t->answer_source = DNS_TRANSACTION_TRUST_ANCHOR;
1766 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false);
1767 SET_FLAG(t->answer_query_flags, SD_RESOLVED_CONFIDENTIAL, true);
1768 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1769 } else
1770 /* If we are not in downgrade mode, then fail the lookup, because we cannot
1771 * reasonably answer it. There might be DS RRs, but we don't know them, and
1772 * the DNS server won't tell them to us (and even if it would, we couldn't
1773 * validate and trust them. */
1774 dns_transaction_complete(t, DNS_TRANSACTION_NO_TRUST_ANCHOR);
1775
1776 return 0;
1777 }
1778 }
1779
1780 /* Check the zone. */
1781 if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_ZONE)) {
1782 r = dns_zone_lookup(&t->scope->zone, dns_transaction_key(t), dns_scope_ifindex(t->scope), &t->answer, NULL, NULL);
1783 if (r < 0)
1784 return r;
1785 if (r > 0) {
1786 t->answer_rcode = DNS_RCODE_SUCCESS;
1787 t->answer_source = DNS_TRANSACTION_ZONE;
1788 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED|SD_RESOLVED_CONFIDENTIAL, true);
1789 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1790 return 0;
1791 }
1792 }
1793
1794 /* Check the cache. */
1795 if (!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_CACHE)) {
1796
1797 /* Before trying the cache, let's make sure we figured out a server to use. Should this cause
1798 * a change of server this might flush the cache. */
1799 (void) dns_scope_get_dns_server(t->scope);
1800
1801 /* Let's then prune all outdated entries */
1802 dns_cache_prune(&t->scope->cache);
1803
1804 /* For the initial attempt or when no stale data is requested, disable serve stale
1805 * and answer the question from the cache (honors ttl property).
1806 * On the second attempt, if StaleRetentionSec is greater than zero,
1807 * try to answer the question using stale date (honors until property) */
1808 uint64_t query_flags = t->query_flags;
1809 if (t->n_attempts == 1 || t->scope->manager->stale_retention_usec == 0)
1810 query_flags |= SD_RESOLVED_NO_STALE;
1811
1812 r = dns_cache_lookup(
1813 &t->scope->cache,
1814 dns_transaction_key(t),
1815 query_flags,
1816 &t->answer_rcode,
1817 &t->answer,
1818 &t->received,
1819 &t->answer_query_flags,
1820 &t->answer_dnssec_result);
1821 if (r < 0)
1822 return r;
1823 if (r > 0) {
1824 dns_transaction_randomize_answer(t);
1825
1826 if (t->bypass && t->scope->protocol == DNS_PROTOCOL_DNS && !t->received)
1827 /* When bypass mode is on, do not use cached data unless it came with a full
1828 * packet. */
1829 dns_transaction_reset_answer(t);
1830 else {
1831 if (t->n_attempts > 1 && !FLAGS_SET(query_flags, SD_RESOLVED_NO_STALE)) {
1832
1833 if (t->answer_rcode == DNS_RCODE_SUCCESS) {
1834 if (t->seen_timeout)
1835 t->scope->manager->n_timeouts_served_stale_total++;
1836 else
1837 t->scope->manager->n_failure_responses_served_stale_total++;
1838 }
1839
1840 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1841 log_debug("Serve Stale response rcode=%s for %s",
1842 FORMAT_DNS_RCODE(t->answer_rcode),
1843 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str));
1844 }
1845
1846 t->answer_source = DNS_TRANSACTION_CACHE;
1847 if (t->answer_rcode == DNS_RCODE_SUCCESS)
1848 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
1849 else {
1850 if (t->received)
1851 (void) dns_packet_ede_rcode(t->received, &t->answer_ede_rcode, &t->answer_ede_msg);
1852
1853 dns_transaction_complete(t, DNS_TRANSACTION_RCODE_FAILURE);
1854 }
1855 return 0;
1856 }
1857 }
1858 }
1859
1860 if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_NETWORK)) {
1861 dns_transaction_complete(t, DNS_TRANSACTION_NO_SOURCE);
1862 return 0;
1863 }
1864
1865 return 1;
1866}
1867
1868static int dns_packet_append_zone(DnsPacket *p, DnsTransaction *t, DnsResourceKey *k, unsigned *nscount) {
1869 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1870 bool tentative;
1871 int r;
1872
1873 assert(p);
1874 assert(t);
1875 assert(k);
1876
1877 if (k->type != DNS_TYPE_ANY)
1878 return 0;
1879
1880 r = dns_zone_lookup(&t->scope->zone, k, t->scope->link->ifindex, &answer, NULL, &tentative);
1881 if (r < 0)
1882 return r;
1883
1884 return dns_packet_append_answer(p, answer, nscount);
1885}
1886
1887static int mdns_make_dummy_packet(DnsTransaction *t, DnsPacket **ret_packet, Set **ret_keys) {
1888 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1889 _cleanup_set_free_ Set *keys = NULL;
1890 bool add_known_answers = false;
1891 unsigned qdcount;
1892 usec_t ts;
1893 int r;
1894
1895 assert(t);
1896 assert(t->scope);
1897 assert(t->scope->protocol == DNS_PROTOCOL_MDNS);
1898 assert(ret_packet);
1899 assert(ret_keys);
1900
1901 r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
1902 if (r < 0)
1903 return r;
1904
1905 r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL);
1906 if (r < 0)
1907 return r;
1908
1909 qdcount = 1;
1910
1911 if (dns_key_is_shared(dns_transaction_key(t)))
1912 add_known_answers = true;
1913
1914 r = dns_packet_append_zone(p, t, dns_transaction_key(t), NULL);
1915 if (r < 0)
1916 return r;
1917
1918 /* Save appended keys */
1919 r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(t));
1920 if (r < 0)
1921 return r;
1922
1923 assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0);
1924
1925 LIST_FOREACH(transactions_by_scope, other, t->scope->transactions) {
1926
1927 /* Skip ourselves */
1928 if (other == t)
1929 continue;
1930
1931 if (other->state != DNS_TRANSACTION_PENDING)
1932 continue;
1933
1934 if (other->next_attempt_after > ts)
1935 continue;
1936
1937 if (!set_contains(keys, dns_transaction_key(other))) {
1938 size_t saved_packet_size;
1939
1940 r = dns_packet_append_key(p, dns_transaction_key(other), 0, &saved_packet_size);
1941 /* If we can't stuff more questions into the packet, just give up.
1942 * One of the 'other' transactions will fire later and take care of the rest. */
1943 if (r == -EMSGSIZE)
1944 break;
1945 if (r < 0)
1946 return r;
1947
1948 r = dns_packet_append_zone(p, t, dns_transaction_key(other), NULL);
1949 if (r == -EMSGSIZE) {
1950 dns_packet_truncate(p, saved_packet_size);
1951 break;
1952 }
1953 if (r < 0)
1954 return r;
1955
1956 r = set_ensure_put(&keys, &dns_resource_key_hash_ops, dns_transaction_key(other));
1957 if (r < 0)
1958 return r;
1959 }
1960
1961 r = dns_transaction_prepare(other, ts);
1962 if (r < 0)
1963 return r;
1964 if (r == 0)
1965 /* In this case, not only this transaction, but multiple transactions may be
1966 * freed. Hence, we need to restart the loop. */
1967 return -EAGAIN;
1968
1969 usec_t timeout = transaction_get_resend_timeout(other);
1970 r = dns_transaction_setup_timeout(other, timeout, usec_add(ts, timeout));
1971 if (r < 0)
1972 return r;
1973
1974 if (dns_key_is_shared(dns_transaction_key(other)))
1975 add_known_answers = true;
1976
1977 qdcount++;
1978 if (qdcount >= UINT16_MAX)
1979 break;
1980 }
1981
1982 DNS_PACKET_HEADER(p)->qdcount = htobe16(qdcount);
1983
1984 /* Append known answers section if we're asking for any shared record */
1985 if (add_known_answers) {
1986 r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, 0);
1987 if (r < 0)
1988 return r;
1989 }
1990
1991 *ret_packet = TAKE_PTR(p);
1992 *ret_keys = TAKE_PTR(keys);
1993 return add_known_answers;
1994}
1995
1996static int dns_transaction_make_packet_mdns(DnsTransaction *t) {
1997 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL, *dummy = NULL;
1998 _cleanup_set_free_ Set *keys = NULL;
1999 bool add_known_answers;
2000 DnsResourceKey *k;
2001 unsigned c;
2002 int r;
2003
2004 assert(t);
2005 assert(t->scope->protocol == DNS_PROTOCOL_MDNS);
2006
2007 /* Discard any previously prepared packet, so we can start over and coalesce again */
2008 t->sent = dns_packet_unref(t->sent);
2009
2010 /* First, create a dummy packet to calculate the number of known answers to be appended in the first packet. */
2011 for (;;) {
2012 r = mdns_make_dummy_packet(t, &dummy, &keys);
2013 if (r == -EAGAIN)
2014 continue;
2015 if (r < 0)
2016 return r;
2017
2018 add_known_answers = r;
2019 break;
2020 }
2021
2022 /* Then, create actual packet. */
2023 r = dns_packet_new_query(&p, t->scope->protocol, 0, false);
2024 if (r < 0)
2025 return r;
2026
2027 /* Questions */
2028 c = 0;
2029 SET_FOREACH(k, keys) {
2030 r = dns_packet_append_key(p, k, 0, NULL);
2031 if (r < 0)
2032 return r;
2033 c++;
2034 }
2035 DNS_PACKET_HEADER(p)->qdcount = htobe16(c);
2036
2037 /* Known answers */
2038 if (add_known_answers) {
2039 usec_t ts;
2040
2041 assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0);
2042
2043 r = dns_cache_export_shared_to_packet(&t->scope->cache, p, ts, be16toh(DNS_PACKET_HEADER(dummy)->ancount));
2044 if (r < 0)
2045 return r;
2046 }
2047
2048 /* Authorities */
2049 c = 0;
2050 SET_FOREACH(k, keys) {
2051 r = dns_packet_append_zone(p, t, k, &c);
2052 if (r < 0)
2053 return r;
2054 }
2055 DNS_PACKET_HEADER(p)->nscount = htobe16(c);
2056
2057 t->sent = TAKE_PTR(p);
2058 return 0;
2059}
2060
2061static int dns_transaction_make_packet(DnsTransaction *t) {
2062 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
2063 int r;
2064
2065 assert(t);
2066
2067 if (t->scope->protocol == DNS_PROTOCOL_MDNS)
2068 return dns_transaction_make_packet_mdns(t);
2069
2070 if (t->sent)
2071 return 0;
2072
2073 if (t->bypass && t->bypass->protocol == t->scope->protocol) {
2074 /* If bypass logic is enabled and the protocol if the original packet and our scope match,
2075 * take the original packet, copy it, and patch in our new ID */
2076 r = dns_packet_dup(&p, t->bypass);
2077 if (r < 0)
2078 return r;
2079 } else {
2080 r = dns_packet_new_query(
2081 &p, t->scope->protocol,
2082 /* min_alloc_dsize = */ 0,
2083 /* dnssec_checking_disabled = */ !FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) &&
2084 t->scope->dnssec_mode != DNSSEC_NO);
2085 if (r < 0)
2086 return r;
2087
2088 r = dns_packet_append_key(p, dns_transaction_key(t), 0, NULL);
2089 if (r < 0)
2090 return r;
2091
2092 DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
2093 }
2094
2095 DNS_PACKET_HEADER(p)->id = t->id;
2096
2097 t->sent = TAKE_PTR(p);
2098 return 0;
2099}
2100
2101int dns_transaction_go(DnsTransaction *t) {
2102 usec_t ts;
2103 int r;
2104 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
2105
2106 assert(t);
2107
2108 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has
2109 * finished now. In the latter case, the transaction and query candidate objects must not be accessed.
2110 */
2111
2112 assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &ts) >= 0);
2113
2114 r = dns_transaction_prepare(t, ts);
2115 if (r <= 0)
2116 return r;
2117
2118 log_debug("Firing %s transaction %" PRIu16 " for <%s> scope %s on %s/%s (validate=%s).",
2119 t->bypass ? "bypass" : "regular",
2120 t->id,
2121 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str),
2122 dns_protocol_to_string(t->scope->protocol),
2123 t->scope->link ? t->scope->link->ifname : "*",
2124 af_to_name_short(t->scope->family),
2125 yes_no(!FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE)));
2126
2127 if (!t->initial_jitter_scheduled &&
2128 IN_SET(t->scope->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
2129 usec_t jitter;
2130
2131 /* RFC 4795 Section 2.7 suggests all LLMNR queries should be delayed by a random time from 0 to
2132 * JITTER_INTERVAL.
2133 * RFC 6762 Section 8.1 suggests initial probe queries should be delayed by a random time from
2134 * 0 to 250ms. */
2135
2136 t->initial_jitter_scheduled = true;
2137 t->n_attempts = 0;
2138
2139 switch (t->scope->protocol) {
2140
2141 case DNS_PROTOCOL_LLMNR:
2142 jitter = random_u64_range(LLMNR_JITTER_INTERVAL_USEC);
2143 break;
2144
2145 case DNS_PROTOCOL_MDNS:
2146 if (t->probing)
2147 jitter = random_u64_range(MDNS_PROBING_INTERVAL_USEC);
2148 else
2149 jitter = 0;
2150 break;
2151 default:
2152 assert_not_reached();
2153 }
2154
2155 r = dns_transaction_setup_timeout(t, jitter, ts);
2156 if (r < 0)
2157 return r;
2158
2159 log_debug("Delaying %s transaction %" PRIu16 " for " USEC_FMT "us.",
2160 dns_protocol_to_string(t->scope->protocol),
2161 t->id,
2162 jitter);
2163 return 1;
2164 }
2165
2166 /* Otherwise, we need to ask the network */
2167 r = dns_transaction_make_packet(t);
2168 if (r < 0)
2169 return r;
2170
2171 if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
2172 (dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "in-addr.arpa") > 0 ||
2173 dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), "ip6.arpa") > 0)) {
2174
2175 /* RFC 4795, Section 2.4. says reverse lookups shall
2176 * always be made via TCP on LLMNR */
2177 r = dns_transaction_emit_tcp(t);
2178 } else {
2179 /* Try via UDP, and if that fails due to large size or lack of
2180 * support try via TCP */
2181 r = dns_transaction_emit_udp(t);
2182 if (r == -EMSGSIZE)
2183 log_debug("Sending query via TCP since it is too large.");
2184 else if (r == -EAGAIN)
2185 log_debug("Sending query via TCP since UDP isn't supported or DNS-over-TLS is selected.");
2186 else if (r == -EPERM)
2187 log_debug("Sending query via TCP since UDP is blocked.");
2188 if (IN_SET(r, -EMSGSIZE, -EAGAIN, -EPERM))
2189 r = dns_transaction_emit_tcp(t);
2190 }
2191 if (r == -ELOOP) {
2192 if (t->scope->protocol != DNS_PROTOCOL_DNS)
2193 return r;
2194
2195 /* One of our own stub listeners */
2196 log_debug_errno(r, "Detected that specified DNS server is our own extra listener, switching DNS servers.");
2197
2198 dns_scope_next_dns_server(t->scope, t->server);
2199
2200 if (dns_scope_get_dns_server(t->scope) == t->server) {
2201 log_debug_errno(r, "Still pointing to extra listener after switching DNS servers, refusing operation.");
2202 dns_transaction_complete(t, DNS_TRANSACTION_STUB_LOOP);
2203 return 0;
2204 }
2205
2206 return dns_transaction_go(t);
2207 }
2208 if (r == -ESRCH) {
2209 /* No servers to send this to? */
2210 dns_transaction_complete(t, DNS_TRANSACTION_NO_SERVERS);
2211 return 0;
2212 }
2213 if (r == -EOPNOTSUPP) {
2214 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
2215 dns_transaction_complete(t, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED);
2216 return 0;
2217 }
2218 if (t->scope->protocol == DNS_PROTOCOL_LLMNR && ERRNO_IS_NEG_DISCONNECT(r)) {
2219 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
2220 * answer this request with this protocol. */
2221 dns_transaction_complete(t, DNS_TRANSACTION_NOT_FOUND);
2222 return 0;
2223 }
2224 if (r < 0) {
2225 if (t->scope->protocol != DNS_PROTOCOL_DNS)
2226 return r;
2227
2228 /* Couldn't send? Try immediately again, with a new server */
2229 dns_scope_next_dns_server(t->scope, t->server);
2230
2231 return dns_transaction_go(t);
2232 }
2233
2234 usec_t timeout = transaction_get_resend_timeout(t);
2235 r = dns_transaction_setup_timeout(t, timeout, usec_add(ts, timeout));
2236 if (r < 0)
2237 return r;
2238
2239 return 1;
2240}
2241
2242static int dns_transaction_find_cyclic(DnsTransaction *t, DnsTransaction *aux) {
2243 DnsTransaction *n;
2244 int r;
2245
2246 assert(t);
2247 assert(aux);
2248
2249 /* Try to find cyclic dependencies between transaction objects */
2250
2251 if (t == aux)
2252 return 1;
2253
2254 SET_FOREACH(n, aux->dnssec_transactions) {
2255 r = dns_transaction_find_cyclic(t, n);
2256 if (r != 0)
2257 return r;
2258 }
2259
2260 return 0;
2261}
2262
2263static int dns_transaction_add_dnssec_transaction(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) {
2264 _cleanup_(dns_transaction_gcp) DnsTransaction *aux = NULL;
2265 int r;
2266
2267 assert(t);
2268 assert(ret);
2269 assert(key);
2270
2271 aux = dns_scope_find_transaction(t->scope, key, t->query_flags);
2272 if (!aux) {
2273 r = dns_transaction_new(&aux, t->scope, key, NULL, t->query_flags);
2274 if (r < 0)
2275 return r;
2276 } else {
2277 if (set_contains(t->dnssec_transactions, aux)) {
2278 *ret = aux;
2279 return 0;
2280 }
2281
2282 r = dns_transaction_find_cyclic(t, aux);
2283 if (r < 0)
2284 return r;
2285 if (r > 0) {
2286 char s[DNS_RESOURCE_KEY_STRING_MAX], saux[DNS_RESOURCE_KEY_STRING_MAX];
2287
2288 return log_debug_errno(SYNTHETIC_ERRNO(ELOOP),
2289 "Potential cyclic dependency, refusing to add transaction %" PRIu16 " (%s) as dependency for %" PRIu16 " (%s).",
2290 aux->id,
2291 dns_resource_key_to_string(dns_transaction_key(t), s, sizeof s),
2292 t->id,
2293 dns_resource_key_to_string(dns_transaction_key(aux), saux, sizeof saux));
2294 }
2295 }
2296
2297 r = set_ensure_allocated(&aux->notify_transactions_done, NULL);
2298 if (r < 0)
2299 return r;
2300
2301 r = set_ensure_put(&t->dnssec_transactions, NULL, aux);
2302 if (r < 0)
2303 return r;
2304
2305 r = set_ensure_put(&aux->notify_transactions, NULL, t);
2306 if (r < 0) {
2307 (void) set_remove(t->dnssec_transactions, aux);
2308 return r;
2309 }
2310
2311 *ret = TAKE_PTR(aux);
2312 return 1;
2313}
2314
2315static int dns_transaction_request_dnssec_rr_full(DnsTransaction *t, DnsResourceKey *key, DnsTransaction **ret) {
2316 _cleanup_(dns_answer_unrefp) DnsAnswer *a = NULL;
2317 DnsTransaction *aux;
2318 int r;
2319
2320 assert(t);
2321 assert(key);
2322
2323 /* Try to get the data from the trust anchor */
2324 r = dns_trust_anchor_lookup_positive(&t->scope->manager->trust_anchor, key, &a);
2325 if (r < 0)
2326 return r;
2327 if (r > 0) {
2328 r = dns_answer_extend(&t->validated_keys, a);
2329 if (r < 0)
2330 return r;
2331
2332 if (ret)
2333 *ret = NULL;
2334 return 0;
2335 }
2336
2337 /* This didn't work, ask for it via the network/cache then. */
2338 r = dns_transaction_add_dnssec_transaction(t, key, &aux);
2339 if (r == -ELOOP) { /* This would result in a cyclic dependency */
2340 if (ret)
2341 *ret = NULL;
2342 return 0;
2343 }
2344 if (r < 0)
2345 return r;
2346
2347 if (aux->state == DNS_TRANSACTION_NULL) {
2348 r = dns_transaction_go(aux);
2349 if (r < 0)
2350 return r;
2351 }
2352 if (ret)
2353 *ret = aux;
2354
2355 return 1;
2356}
2357
2358static int dns_transaction_request_dnssec_rr(DnsTransaction *t, DnsResourceKey *key) {
2359 assert(t);
2360 assert(key);
2361 return dns_transaction_request_dnssec_rr_full(t, key, NULL);
2362}
2363
2364static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction *t, const char *name) {
2365 int r;
2366
2367 assert(t);
2368
2369 /* Check whether the specified name is in the NTA
2370 * database, either in the global one, or the link-local
2371 * one. */
2372
2373 r = dns_trust_anchor_lookup_negative(&t->scope->manager->trust_anchor, name);
2374 if (r != 0)
2375 return r;
2376
2377 if (!t->scope->link)
2378 return 0;
2379
2380 return link_negative_trust_anchor_lookup(t->scope->link, name);
2381}
2382
2383static int dns_transaction_has_negative_answer(DnsTransaction *t) {
2384 int r;
2385
2386 assert(t);
2387
2388 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
2389 * RRs to prove it */
2390
2391 r = dns_transaction_has_positive_answer(t, NULL);
2392 if (r < 0)
2393 return r;
2394 if (r > 0)
2395 return false;
2396
2397 /* Is this key explicitly listed as a negative trust anchor?
2398 * If so, it's nothing we need to care about */
2399 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t)));
2400 if (r < 0)
2401 return r;
2402 return !r;
2403}
2404
2405static int dns_transaction_is_primary_response(DnsTransaction *t, DnsResourceRecord *rr) {
2406 int r;
2407
2408 assert(t);
2409 assert(rr);
2410
2411 /* Check if the specified RR is the "primary" response,
2412 * i.e. either matches the question precisely or is a
2413 * CNAME/DNAME for it. */
2414
2415 r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL);
2416 if (r != 0)
2417 return r;
2418
2419 return dns_resource_key_match_cname_or_dname(dns_transaction_key(t), rr->key, NULL);
2420}
2421
2422static bool dns_transaction_dnssec_supported(DnsTransaction *t) {
2423 assert(t);
2424
2425 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
2426 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
2427
2428 if (t->scope->protocol != DNS_PROTOCOL_DNS)
2429 return false;
2430
2431 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
2432 * be supported, hence return true. */
2433 if (!t->server)
2434 return true;
2435
2436 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
2437 * the server is known to support currently, as the transaction feature level might be lower than what the
2438 * server actually supports, since we might have downgraded this transaction's feature level because we got a
2439 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
2440
2441 return dns_server_dnssec_supported(t->server);
2442}
2443
2444static bool dns_transaction_dnssec_supported_full(DnsTransaction *t) {
2445 DnsTransaction *dt;
2446
2447 assert(t);
2448
2449 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
2450
2451 if (!dns_transaction_dnssec_supported(t))
2452 return false;
2453
2454 SET_FOREACH(dt, t->dnssec_transactions)
2455 if (!dns_transaction_dnssec_supported(dt))
2456 return false;
2457
2458 return true;
2459}
2460
2461int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
2462 DnsResourceRecord *rr;
2463
2464 /* Have we already requested a record that would be sufficient to validate an insecure delegation? */
2465 bool chased_insecure = false;
2466 int r;
2467
2468 assert(t);
2469
2470 /*
2471 * Retrieve all auxiliary RRs for the answer we got, so that
2472 * we can verify signatures or prove that RRs are rightfully
2473 * unsigned. Specifically:
2474 *
2475 * - For RRSIG we get the matching DNSKEY
2476 * - For DNSKEY we get the matching DS
2477 * - For unsigned SOA/NS we get the matching DS
2478 * - For unsigned CNAME/DNAME/DS we get the parent DS RR
2479 * - For other unsigned RRs we get the matching DS RR
2480 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
2481 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's DS RR
2482 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the DS RR
2483 */
2484
2485 if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO)
2486 return 0;
2487 if (t->answer_source != DNS_TRANSACTION_NETWORK)
2488 return 0; /* We only need to validate stuff from the network */
2489 if (!dns_transaction_dnssec_supported(t))
2490 return 0; /* If we can't do DNSSEC anyway there's no point in getting the auxiliary RRs */
2491
2492 DNS_ANSWER_FOREACH(rr, t->answer) {
2493
2494 if (dns_type_is_pseudo(rr->key->type))
2495 continue;
2496
2497 /* If this RR is in the negative trust anchor, we don't need to validate it. */
2498 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2499 if (r < 0)
2500 return r;
2501 if (r > 0)
2502 continue;
2503
2504 switch (rr->key->type) {
2505
2506 case DNS_TYPE_RRSIG: {
2507 /* For each RRSIG we request the matching DNSKEY */
2508 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *dnskey = NULL;
2509 DnsTransaction *aux;
2510
2511 /* If this RRSIG is about a DNSKEY RR and the
2512 * signer is the same as the owner, then we
2513 * already have the DNSKEY, and we don't have
2514 * to look for more. */
2515 if (rr->rrsig.type_covered == DNS_TYPE_DNSKEY) {
2516 r = dns_name_equal(rr->rrsig.signer, dns_resource_key_name(rr->key));
2517 if (r < 0)
2518 return r;
2519 if (r > 0)
2520 continue;
2521 }
2522
2523 /* If the signer is not a parent of our
2524 * original query, then this is about an
2525 * auxiliary RRset, but not anything we asked
2526 * for. In this case we aren't interested,
2527 * because we don't want to request additional
2528 * RRs for stuff we didn't really ask for, and
2529 * also to avoid request loops, where
2530 * additional RRs from one transaction result
2531 * in another transaction whose additional RRs
2532 * point back to the original transaction, and
2533 * we deadlock. */
2534 r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), rr->rrsig.signer);
2535 if (r < 0)
2536 return r;
2537 if (r == 0)
2538 continue;
2539
2540 dnskey = dns_resource_key_new(rr->key->class, DNS_TYPE_DNSKEY, rr->rrsig.signer);
2541 if (!dnskey)
2542 return -ENOMEM;
2543
2544 log_debug("Requesting DNSKEY to validate transaction %" PRIu16" (%s, RRSIG with key tag: %" PRIu16 ").",
2545 t->id, dns_resource_key_name(rr->key), rr->rrsig.key_tag);
2546 r = dns_transaction_request_dnssec_rr_full(t, dnskey, &aux);
2547 if (r < 0)
2548 return r;
2549
2550 /* If we are requesting a DNSKEY, we can anticipate that we will want the matching DS
2551 * in the near future. Let's request it in advance so we don't have to wait in the
2552 * common case. */
2553 if (aux) {
2554 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds =
2555 dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(dnskey));
2556 if (!ds)
2557 return -ENOMEM;
2558 r = dns_transaction_request_dnssec_rr(t, ds);
2559 if (r < 0)
2560 return r;
2561 }
2562 break;
2563 }
2564
2565 case DNS_TYPE_DNSKEY: {
2566 /* For each DNSKEY we request the matching DS */
2567 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2568
2569 /* If the DNSKEY we are looking at is not for
2570 * zone we are interested in, nor any of its
2571 * parents, we aren't interested, and don't
2572 * request it. After all, we don't want to end
2573 * up in request loops, and want to keep
2574 * additional traffic down. */
2575
2576 r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key));
2577 if (r < 0)
2578 return r;
2579 if (r == 0)
2580 continue;
2581
2582 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2583 if (!ds)
2584 return -ENOMEM;
2585
2586 log_debug("Requesting DS to validate transaction %" PRIu16" (%s, DNSKEY with key tag: %" PRIu16 ").",
2587 t->id, dns_resource_key_name(rr->key), dnssec_keytag(rr, false));
2588 r = dns_transaction_request_dnssec_rr(t, ds);
2589 if (r < 0)
2590 return r;
2591
2592 break;
2593 }
2594
2595 case DNS_TYPE_SOA:
2596 case DNS_TYPE_NS: {
2597 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2598
2599 /* For an unsigned SOA or NS, try to acquire
2600 * the matching DS RR, as we are at a zone cut
2601 * then, and whether a DS exists tells us
2602 * whether the zone is signed. Do so only if
2603 * this RR matches our original question,
2604 * however. */
2605
2606 r = dns_resource_key_match_rr(dns_transaction_key(t), rr, NULL);
2607 if (r < 0)
2608 return r;
2609 if (r == 0) {
2610 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2611 * a negative reply, and we need the SOA RR's TTL in order to cache a negative entry?
2612 * If so, we need to validate it, too. */
2613
2614 r = dns_answer_match_key(t->answer, dns_transaction_key(t), NULL);
2615 if (r < 0)
2616 return r;
2617 if (r > 0) /* positive reply, we won't need the SOA and hence don't need to validate
2618 * it. */
2619 continue;
2620
2621 /* Only bother with this if the SOA/NS RR we are looking at is actually a parent of
2622 * what we are looking for, otherwise there's no value in it for us. */
2623 r = dns_name_endswith(dns_resource_key_name(dns_transaction_key(t)), dns_resource_key_name(rr->key));
2624 if (r < 0)
2625 return r;
2626 if (r == 0)
2627 continue;
2628
2629 /* If we were looking for the DS RR, don't request it again. */
2630 if (dns_transaction_key(t)->type == DNS_TYPE_DS)
2631 continue;
2632 }
2633
2634 r = dnssec_has_rrsig(t->answer, rr->key);
2635 if (r < 0)
2636 return r;
2637 if (r > 0)
2638 continue;
2639
2640 chased_insecure = true;
2641 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2642 if (!ds)
2643 return -ENOMEM;
2644
2645 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned SOA/NS RRset).",
2646 t->id, dns_resource_key_name(rr->key));
2647 r = dns_transaction_request_dnssec_rr(t, ds);
2648 if (r < 0)
2649 return r;
2650
2651 break;
2652 }
2653
2654 case DNS_TYPE_DS:
2655 case DNS_TYPE_CNAME:
2656 case DNS_TYPE_DNAME: {
2657 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2658 const char *name;
2659
2660 /* CNAMEs and DNAMEs cannot be located at a
2661 * zone apex, hence ask for the parent DS for
2662 * unsigned CNAME/DNAME RRs, maybe that's the
2663 * apex. But do all that only if this is
2664 * actually a response to our original
2665 * question.
2666 *
2667 * Similar for DS RRs, which are signed when
2668 * the parent SOA is signed. */
2669
2670 r = dns_transaction_is_primary_response(t, rr);
2671 if (r < 0)
2672 return r;
2673 if (r == 0)
2674 continue;
2675
2676 r = dnssec_has_rrsig(t->answer, rr->key);
2677 if (r < 0)
2678 return r;
2679 if (r > 0)
2680 continue;
2681
2682 r = dns_answer_has_dname_for_cname(t->answer, rr);
2683 if (r < 0)
2684 return r;
2685 if (r > 0)
2686 continue;
2687
2688 name = dns_resource_key_name(rr->key);
2689 r = dns_name_parent(&name);
2690 if (r < 0)
2691 return r;
2692 if (r == 0)
2693 continue;
2694
2695 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, name);
2696 if (!ds)
2697 return -ENOMEM;
2698
2699 log_debug("Requesting parent DS to validate transaction %" PRIu16 " (%s, unsigned CNAME/DNAME/DS RRset).",
2700 t->id, dns_resource_key_name(rr->key));
2701 r = dns_transaction_request_dnssec_rr(t, ds);
2702 if (r < 0)
2703 return r;
2704
2705 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE && dns_name_is_root(name)) {
2706 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *soa = NULL;
2707 /* We made it all the way to the root zone. If we are in allow-downgrade
2708 * mode, we need to make at least one request that we can be certain should
2709 * have been signed, to test for servers that are not dnssec aware. */
2710 soa = dns_resource_key_new(rr->key->class, DNS_TYPE_SOA, name);
2711 if (!soa)
2712 return -ENOMEM;
2713
2714 log_debug("Requesting root zone SOA to probe dnssec support.");
2715 r = dns_transaction_request_dnssec_rr(t, soa);
2716 if (r < 0)
2717 return r;
2718 }
2719
2720 break;
2721 }
2722
2723 default: {
2724 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2725
2726 /* For other unsigned RRsets (including
2727 * NSEC/NSEC3!), look for proof the zone is
2728 * unsigned, by requesting the DS RR of the
2729 * zone. However, do so only if they are
2730 * directly relevant to our original
2731 * question. */
2732
2733 r = dns_transaction_is_primary_response(t, rr);
2734 if (r < 0)
2735 return r;
2736 if (r == 0)
2737 continue;
2738
2739 r = dnssec_has_rrsig(t->answer, rr->key);
2740 if (r < 0)
2741 return r;
2742 if (r > 0)
2743 continue;
2744
2745 ds = dns_resource_key_new(rr->key->class, DNS_TYPE_DS, dns_resource_key_name(rr->key));
2746 if (!ds)
2747 return -ENOMEM;
2748
2749 log_debug("Requesting DS to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).",
2750 t->id, dns_resource_key_name(rr->key), dns_resource_record_to_string(rr));
2751 r = dns_transaction_request_dnssec_rr(t, ds);
2752 if (r < 0)
2753 return r;
2754 break;
2755 }}
2756 }
2757
2758 /* Above, we requested everything necessary to validate what
2759 * we got. Now, let's request what we need to validate what we
2760 * didn't get... */
2761
2762 r = dns_transaction_has_negative_answer(t);
2763 if (r < 0)
2764 return r;
2765 if (r > 0) {
2766 const char *name = dns_resource_key_name(dns_transaction_key(t));
2767 bool was_signed = dns_answer_contains_nsec_or_nsec3(t->answer);
2768
2769 /* If the response is empty, seek the DS for this name, just in case we're at a zone cut
2770 * already, unless we just requested the DS, in which case we have to ask the parent to make
2771 * progress.
2772 *
2773 * If this was an SOA or NS request, we could also skip to the parent, but in real world
2774 * setups there are too many broken DNS servers (Hello, incapdns.net!) where non-terminal
2775 * zones return NXDOMAIN even though they have further children. */
2776
2777 if (chased_insecure || was_signed)
2778 /* In this case we already requested what we need above. */
2779 name = NULL;
2780 else if (dns_transaction_key(t)->type == DNS_TYPE_DS)
2781 /* If the DS response is empty, we'll walk up the dns labels requesting DS until we
2782 * find a referral to the SOA or hit it anyway and get a positive DS response. */
2783 if (dns_name_parent(&name) <= 0)
2784 name = NULL;
2785
2786 if (name) {
2787 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *ds = NULL;
2788
2789 log_debug("Requesting DS (%s %s) to validate transaction %" PRIu16 " (%s empty response).",
2790 glyph(GLYPH_ARROW_RIGHT), name, t->id,
2791 dns_resource_key_name(dns_transaction_key(t)));
2792
2793 ds = dns_resource_key_new(dns_transaction_key(t)->class, DNS_TYPE_DS, name);
2794 if (!ds)
2795 return -ENOMEM;
2796
2797 r = dns_transaction_request_dnssec_rr(t, ds);
2798 if (r < 0)
2799 return r;
2800 }
2801 }
2802
2803 return dns_transaction_dnssec_is_live(t);
2804}
2805
2806DnsResourceKey* dns_transaction_key(DnsTransaction *t) {
2807 assert(t);
2808
2809 /* Return the lookup key of this transaction. Either takes the lookup key from the bypass packet if
2810 * we are a bypass transaction. Or take the configured key for regular transactions. */
2811
2812 if (t->key)
2813 return t->key;
2814
2815 assert(t->bypass);
2816
2817 return dns_question_first_key(t->bypass->question);
2818}
2819
2820void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source) {
2821 assert(t);
2822 assert(source);
2823
2824 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2825 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2826 the state is VALIDATING however, we should check if we are complete now. */
2827
2828 if (t->state == DNS_TRANSACTION_VALIDATING)
2829 dns_transaction_process_dnssec(t);
2830}
2831
2832static int dns_transaction_validate_dnskey_by_ds(DnsTransaction *t) {
2833 DnsAnswerItem *item;
2834 int r;
2835
2836 assert(t);
2837
2838 /* Add all DNSKEY RRs from the answer that are validated by DS
2839 * RRs from the list of validated keys to the list of
2840 * validated keys. */
2841
2842 DNS_ANSWER_FOREACH_ITEM(item, t->answer) {
2843
2844 r = dnssec_verify_dnskey_by_ds_search(item->rr, t->validated_keys);
2845 if (r < 0)
2846 return r;
2847 if (r == 0)
2848 continue;
2849
2850 /* If so, the DNSKEY is validated too. */
2851 r = dns_answer_add_extend(&t->validated_keys, item->rr, item->ifindex, item->flags|DNS_ANSWER_AUTHENTICATED, item->rrsig);
2852 if (r < 0)
2853 return r;
2854 }
2855
2856 return 0;
2857}
2858
2859static int dns_transaction_requires_rrsig(DnsTransaction *t, DnsResourceRecord *rr) {
2860 int r;
2861
2862 assert(t);
2863 assert(rr);
2864
2865 /* Checks if the RR we are looking for must be signed with an
2866 * RRSIG. This is used for positive responses. */
2867
2868 if (t->scope->dnssec_mode == DNSSEC_NO)
2869 return false;
2870
2871 if (dns_type_is_pseudo(rr->key->type))
2872 return -EINVAL;
2873
2874 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
2875 if (r < 0)
2876 return r;
2877 if (r > 0)
2878 return false;
2879
2880 switch (rr->key->type) {
2881
2882 case DNS_TYPE_RRSIG:
2883 /* RRSIGs are the signatures themselves, they need no signing. */
2884 return false;
2885
2886 case DNS_TYPE_SOA:
2887 case DNS_TYPE_NS: {
2888 DnsTransaction *dt;
2889
2890 /* For SOA or NS RRs we look for a matching DS transaction */
2891 SET_FOREACH(dt, t->dnssec_transactions) {
2892
2893 if (dns_transaction_key(dt)->class != rr->key->class)
2894 continue;
2895 if (dns_transaction_key(dt)->type != DNS_TYPE_DS)
2896 continue;
2897
2898 r = dns_name_endswith(dns_resource_key_name(rr->key), dns_resource_key_name(dns_transaction_key(dt)));
2899 if (r < 0)
2900 return r;
2901 if (r == 0)
2902 continue;
2903
2904 /* We found a DS transactions for the SOA/NS
2905 * RRs we are looking at. If it discovered signed DS
2906 * RRs, then we need to be signed, too. */
2907
2908 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
2909 return false;
2910
2911 return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL);
2912 }
2913
2914 /* We found nothing that proves this is safe to leave
2915 * this unauthenticated, hence ask inist on
2916 * authentication. */
2917 return true;
2918 }
2919
2920 case DNS_TYPE_DS:
2921 case DNS_TYPE_CNAME:
2922 case DNS_TYPE_DNAME: {
2923 const char *parent = NULL;
2924 DnsTransaction *dt;
2925
2926 /*
2927 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent DS.
2928 *
2929 * DS RRs are signed if the parent is signed, hence also look at the parent DS
2930 */
2931
2932 SET_FOREACH(dt, t->dnssec_transactions) {
2933
2934 if (dns_transaction_key(dt)->class != rr->key->class)
2935 continue;
2936 if (dns_transaction_key(dt)->type != DNS_TYPE_DS)
2937 continue;
2938
2939 if (!parent) {
2940 parent = dns_resource_key_name(rr->key);
2941 r = dns_name_parent(&parent);
2942 if (r < 0)
2943 return r;
2944 if (r == 0) {
2945 if (rr->key->type == DNS_TYPE_DS)
2946 return true;
2947
2948 /* A CNAME/DNAME without a parent? That's sooo weird. */
2949 return log_debug_errno(SYNTHETIC_ERRNO(EBADMSG),
2950 "Transaction %" PRIu16 " claims CNAME/DNAME at root. Refusing.", t->id);
2951 }
2952 }
2953
2954 r = dns_name_endswith(parent, dns_resource_key_name(dns_transaction_key(dt)));
2955 if (r < 0)
2956 return r;
2957 if (r == 0)
2958 continue;
2959
2960 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
2961 return false;
2962
2963 /* We expect this to be signed when the DS record exists, and don't expect it to be
2964 * signed when the DS record is proven not to exist. */
2965 return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL);
2966 }
2967
2968 return true;
2969 }
2970
2971 default: {
2972 DnsTransaction *dt;
2973
2974 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our DS lookup was authenticated */
2975
2976 SET_FOREACH(dt, t->dnssec_transactions) {
2977 if (dns_transaction_key(dt)->class != rr->key->class)
2978 continue;
2979 if (dns_transaction_key(dt)->type != DNS_TYPE_DS)
2980 continue;
2981
2982 r = dns_name_endswith(dns_resource_key_name(rr->key), dns_resource_key_name(dns_transaction_key(dt)));
2983 if (r < 0)
2984 return r;
2985 if (r == 0)
2986 continue;
2987
2988 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
2989 return false;
2990
2991 /* We expect this to be signed when the DS record exists, and don't expect it to be
2992 * signed when the DS record is proven not to exist. */
2993 return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL);
2994 }
2995
2996 return true;
2997 }}
2998}
2999
3000static int dns_transaction_in_private_tld(DnsTransaction *t, const DnsResourceKey *key) {
3001 DnsTransaction *dt;
3002 const char *tld;
3003 int r;
3004
3005 /* If DNSSEC downgrade mode is on, checks whether the
3006 * specified RR is one level below a TLD we have proven not to
3007 * exist. In such a case we assume that this is a private
3008 * domain, and permit it.
3009 *
3010 * This detects cases like the Fritz!Box router networks. Each
3011 * Fritz!Box router serves a private "fritz.box" zone, in the
3012 * non-existing TLD "box". Requests for the "fritz.box" domain
3013 * are served by the router itself, while requests for the
3014 * "box" domain will result in NXDOMAIN.
3015 *
3016 * Note that this logic is unable to detect cases where a
3017 * router serves a private DNS zone directly under
3018 * non-existing TLD. In such a case we cannot detect whether
3019 * the TLD is supposed to exist or not, as all requests we
3020 * make for it will be answered by the router's zone, and not
3021 * by the root zone. */
3022
3023 assert(t);
3024
3025 if (t->scope->dnssec_mode != DNSSEC_ALLOW_DOWNGRADE)
3026 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
3027
3028 tld = dns_resource_key_name(key);
3029 r = dns_name_parent(&tld);
3030 if (r < 0)
3031 return r;
3032 if (r == 0)
3033 return false; /* Already the root domain */
3034
3035 if (!dns_name_is_single_label(tld))
3036 return false;
3037
3038 SET_FOREACH(dt, t->dnssec_transactions) {
3039
3040 if (dns_transaction_key(dt)->class != key->class)
3041 continue;
3042
3043 r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), tld);
3044 if (r < 0)
3045 return r;
3046 if (r == 0)
3047 continue;
3048
3049 /* We found an auxiliary lookup we did for the TLD. If
3050 * that returned with NXDOMAIN, we know the TLD didn't
3051 * exist, and hence this might be a private zone. */
3052
3053 return dt->answer_rcode == DNS_RCODE_NXDOMAIN;
3054 }
3055
3056 return false;
3057}
3058
3059static int dns_transaction_requires_nsec(DnsTransaction *t) {
3060 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
3061 DnsTransaction *dt;
3062 const char *name;
3063 int r;
3064
3065 assert(t);
3066
3067 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
3068 * this negative reply */
3069
3070 if (t->scope->dnssec_mode == DNSSEC_NO)
3071 return false;
3072
3073 if (dns_type_is_pseudo(dns_transaction_key(t)->type))
3074 return -EINVAL;
3075
3076 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(dns_transaction_key(t)));
3077 if (r < 0)
3078 return r;
3079 if (r > 0)
3080 return false;
3081
3082 r = dns_transaction_in_private_tld(t, dns_transaction_key(t));
3083 if (r < 0)
3084 return r;
3085 if (r > 0) {
3086 /* The lookup is from a TLD that is proven not to
3087 * exist, and we are in downgrade mode, hence ignore
3088 * that fact that we didn't get any NSEC RRs. */
3089
3090 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
3091 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str));
3092 return false;
3093 }
3094
3095 name = dns_resource_key_name(dns_transaction_key(t));
3096
3097 /* For all other RRs we check the DS on the same level to see
3098 * if it's signed. */
3099
3100 SET_FOREACH(dt, t->dnssec_transactions) {
3101 if (dns_transaction_key(dt)->class != dns_transaction_key(t)->class)
3102 continue;
3103 if (dns_transaction_key(dt)->type != DNS_TYPE_DS)
3104 continue;
3105
3106 r = dns_name_endswith(name, dns_resource_key_name(dns_transaction_key(dt)));
3107 if (r < 0)
3108 return r;
3109 if (r == 0)
3110 continue;
3111
3112 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
3113 return false;
3114
3115 /* We expect this to be signed when the DS record exists, and don't expect it to be signed
3116 * when the DS record is proven not to exist. */
3117 return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL);
3118 }
3119
3120 /* If in doubt, require NSEC/NSEC3 */
3121 return true;
3122}
3123
3124static int dns_transaction_dnskey_authenticated(DnsTransaction *t, DnsResourceRecord *rr) {
3125 DnsResourceRecord *rrsig;
3126 bool found = false;
3127 int r;
3128
3129 /* Checks whether any of the DNSKEYs used for the RRSIGs for
3130 * the specified RRset is authenticated (i.e. has a matching
3131 * DS RR). */
3132
3133 r = dns_transaction_negative_trust_anchor_lookup(t, dns_resource_key_name(rr->key));
3134 if (r < 0)
3135 return r;
3136 if (r > 0)
3137 return false;
3138
3139 DNS_ANSWER_FOREACH(rrsig, t->answer) {
3140 DnsTransaction *dt;
3141
3142 r = dnssec_key_match_rrsig(rr->key, rrsig);
3143 if (r < 0)
3144 return r;
3145 if (r == 0)
3146 continue;
3147
3148 SET_FOREACH(dt, t->dnssec_transactions) {
3149
3150 if (dns_transaction_key(dt)->class != rr->key->class)
3151 continue;
3152
3153 if (dns_transaction_key(dt)->type == DNS_TYPE_DNSKEY) {
3154
3155 r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer);
3156 if (r < 0)
3157 return r;
3158 if (r == 0)
3159 continue;
3160
3161 /* OK, we found an auxiliary DNSKEY lookup. If that lookup is authenticated,
3162 * report this. */
3163
3164 if (FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
3165 return true;
3166
3167 found = true;
3168
3169 } else if (dns_transaction_key(dt)->type == DNS_TYPE_DS) {
3170
3171 r = dns_name_equal(dns_resource_key_name(dns_transaction_key(dt)), rrsig->rrsig.signer);
3172 if (r < 0)
3173 return r;
3174 if (r == 0)
3175 continue;
3176
3177 /* OK, we found an auxiliary DS lookup. If that lookup is authenticated and
3178 * non-zero, we won! */
3179
3180 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
3181 return false;
3182
3183 return dns_answer_match_key(dt->answer, dns_transaction_key(dt), NULL);
3184 }
3185 }
3186 }
3187
3188 return found ? false : -ENXIO;
3189}
3190
3191static int dns_transaction_known_signed(DnsTransaction *t, DnsResourceRecord *rr) {
3192 assert(t);
3193 assert(rr);
3194
3195 /* We know that the root domain is signed, hence if it appears
3196 * not to be signed, there's a problem with the DNS server */
3197
3198 return rr->key->class == DNS_CLASS_IN &&
3199 dns_name_is_root(dns_resource_key_name(rr->key));
3200}
3201
3202static int dns_transaction_check_revoked_trust_anchors(DnsTransaction *t) {
3203 DnsResourceRecord *rr;
3204 int r;
3205
3206 assert(t);
3207
3208 /* Maybe warn the user that we encountered a revoked DNSKEY
3209 * for a key from our trust anchor. Note that we don't care
3210 * whether the DNSKEY can be authenticated or not. It's
3211 * sufficient if it is self-signed. */
3212
3213 DNS_ANSWER_FOREACH(rr, t->answer) {
3214 r = dns_trust_anchor_check_revoked(&t->scope->manager->trust_anchor, rr, t->answer);
3215 if (r < 0)
3216 return r;
3217 }
3218
3219 return 0;
3220}
3221
3222static int dns_transaction_invalidate_revoked_keys(DnsTransaction *t) {
3223 bool changed;
3224 int r;
3225
3226 assert(t);
3227
3228 /* Removes all DNSKEY/DS objects from t->validated_keys that
3229 * our trust anchors database considers revoked. */
3230
3231 do {
3232 DnsResourceRecord *rr;
3233
3234 changed = false;
3235
3236 DNS_ANSWER_FOREACH(rr, t->validated_keys) {
3237 r = dns_trust_anchor_is_revoked(&t->scope->manager->trust_anchor, rr);
3238 if (r < 0)
3239 return r;
3240 if (r > 0) {
3241 r = dns_answer_remove_by_rr(&t->validated_keys, rr);
3242 if (r < 0)
3243 return r;
3244
3245 assert(r > 0);
3246 changed = true;
3247 break;
3248 }
3249 }
3250 } while (changed);
3251
3252 return 0;
3253}
3254
3255static int dns_transaction_copy_validated(DnsTransaction *t) {
3256 DnsTransaction *dt;
3257 int r;
3258
3259 assert(t);
3260
3261 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
3262
3263 SET_FOREACH(dt, t->dnssec_transactions) {
3264
3265 if (DNS_TRANSACTION_IS_LIVE(dt->state))
3266 continue;
3267
3268 if (!FLAGS_SET(dt->answer_query_flags, SD_RESOLVED_AUTHENTICATED))
3269 continue;
3270
3271 r = dns_answer_extend(&t->validated_keys, dt->answer);
3272 if (r < 0)
3273 return r;
3274 }
3275
3276 return 0;
3277}
3278
3279typedef enum {
3280 DNSSEC_PHASE_DNSKEY, /* Phase #1, only validate DNSKEYs */
3281 DNSSEC_PHASE_NSEC, /* Phase #2, only validate NSEC+NSEC3 */
3282 DNSSEC_PHASE_ALL, /* Phase #3, validate everything else */
3283} Phase;
3284
3285static int dnssec_validate_records(
3286 DnsTransaction *t,
3287 Phase phase,
3288 bool *have_nsec,
3289 unsigned *nvalidations,
3290 DnsAnswer **validated) {
3291
3292 DnsResourceRecord *rr;
3293 int r;
3294
3295 assert(nvalidations);
3296
3297 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
3298
3299 DNS_ANSWER_FOREACH(rr, t->answer) {
3300 _unused_ _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr_ref = dns_resource_record_ref(rr);
3301 DnsResourceRecord *rrsig = NULL;
3302 DnssecResult result;
3303
3304 switch (rr->key->type) {
3305 case DNS_TYPE_RRSIG:
3306 continue;
3307
3308 case DNS_TYPE_DNSKEY:
3309 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
3310 if (phase == DNSSEC_PHASE_NSEC)
3311 continue;
3312 break;
3313
3314 case DNS_TYPE_NSEC:
3315 case DNS_TYPE_NSEC3:
3316 *have_nsec = true;
3317
3318 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
3319 if (phase == DNSSEC_PHASE_DNSKEY)
3320 continue;
3321 break;
3322
3323 default:
3324 /* We validate all other RRs only in the ALL phases */
3325 if (phase != DNSSEC_PHASE_ALL)
3326 continue;
3327 }
3328
3329 r = dnssec_verify_rrset_search(
3330 t->answer,
3331 rr->key,
3332 t->validated_keys,
3333 USEC_INFINITY,
3334 &result,
3335 &rrsig);
3336 if (r < 0)
3337 return r;
3338 *nvalidations += r;
3339
3340 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr)), dnssec_result_to_string(result));
3341
3342 if (result == DNSSEC_VALIDATED) {
3343 assert(rrsig);
3344
3345 if (rr->key->type == DNS_TYPE_DNSKEY) {
3346 /* If we just validated a DNSKEY RRset, then let's add these keys to
3347 * the set of validated keys for this transaction. */
3348
3349 r = dns_answer_copy_by_key(&t->validated_keys, t->answer, rr->key, DNS_ANSWER_AUTHENTICATED, rrsig);
3350 if (r < 0)
3351 return r;
3352
3353 /* Some of the DNSKEYs we just added might already have been revoked,
3354 * remove them again in that case. */
3355 r = dns_transaction_invalidate_revoked_keys(t);
3356 if (r < 0)
3357 return r;
3358 }
3359
3360 /* Add the validated RRset to the new list of validated RRsets, and remove it from
3361 * the unvalidated RRsets. We mark the RRset as authenticated and cacheable. */
3362 r = dns_answer_move_by_key(validated, &t->answer, rr->key, DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE, rrsig);
3363 if (r < 0)
3364 return r;
3365
3366 manager_dnssec_verdict(t->scope->manager, DNSSEC_SECURE, rr->key);
3367
3368 /* Exit the loop, we dropped something from the answer, start from the beginning */
3369 return 1;
3370 }
3371
3372 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
3373 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
3374 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
3375 if (phase != DNSSEC_PHASE_ALL)
3376 continue;
3377
3378 if (result == DNSSEC_VALIDATED_WILDCARD) {
3379 bool authenticated = false;
3380 const char *source;
3381
3382 assert(rrsig);
3383
3384 /* This RRset validated, but as a wildcard. This means we need
3385 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
3386
3387 /* First step, determine the source of synthesis */
3388 r = dns_resource_record_source(rrsig, &source);
3389 if (r < 0)
3390 return r;
3391
3392 r = dnssec_test_positive_wildcard(*validated,
3393 dns_resource_key_name(rr->key),
3394 source,
3395 rrsig->rrsig.signer,
3396 &authenticated);
3397
3398 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
3399 if (r == 0)
3400 result = DNSSEC_INVALID;
3401 else {
3402 r = dns_answer_move_by_key(
3403 validated,
3404 &t->answer,
3405 rr->key,
3406 authenticated ? (DNS_ANSWER_AUTHENTICATED|DNS_ANSWER_CACHEABLE) : 0,
3407 rrsig);
3408 if (r < 0)
3409 return r;
3410
3411 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, rr->key);
3412
3413 /* Exit the loop, we dropped something from the answer, start from the beginning */
3414 return 1;
3415 }
3416 }
3417
3418 if (result == DNSSEC_NO_SIGNATURE) {
3419 r = dns_transaction_requires_rrsig(t, rr);
3420 if (r < 0)
3421 return r;
3422 if (r == 0) {
3423 /* Data does not require signing. In that case, just copy it over,
3424 * but remember that this is by no means authenticated. */
3425 r = dns_answer_move_by_key(
3426 validated,
3427 &t->answer,
3428 rr->key,
3429 0,
3430 NULL);
3431 if (r < 0)
3432 return r;
3433
3434 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3435 return 1;
3436 }
3437
3438 r = dns_transaction_known_signed(t, rr);
3439 if (r < 0)
3440 return r;
3441 if (r > 0) {
3442 /* This is an RR we know has to be signed. If it isn't this means
3443 * the server is not attaching RRSIGs, hence complain. */
3444
3445 dns_server_packet_rrsig_missing(t->server, t->current_feature_level);
3446
3447 if (t->scope->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE) {
3448
3449 /* Downgrading is OK? If so, just consider the information unsigned */
3450
3451 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL);
3452 if (r < 0)
3453 return r;
3454
3455 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3456 return 1;
3457 }
3458
3459 /* Otherwise, fail */
3460 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
3461 return 0;
3462 }
3463
3464 r = dns_transaction_in_private_tld(t, rr->key);
3465 if (r < 0)
3466 return r;
3467 if (r > 0) {
3468 char s[DNS_RESOURCE_KEY_STRING_MAX];
3469
3470 /* The data is from a TLD that is proven not to exist, and we are in downgrade
3471 * mode, hence ignore the fact that this was not signed. */
3472
3473 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
3474 dns_resource_key_to_string(rr->key, s, sizeof s));
3475
3476 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL);
3477 if (r < 0)
3478 return r;
3479
3480 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3481 return 1;
3482 }
3483 }
3484
3485 /* https://datatracker.ietf.org/doc/html/rfc6840#section-5.2 */
3486 if (result == DNSSEC_UNSUPPORTED_ALGORITHM) {
3487 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL);
3488 if (r < 0)
3489 return r;
3490
3491 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3492 return 1;
3493 }
3494
3495 if (IN_SET(result,
3496 DNSSEC_MISSING_KEY,
3497 DNSSEC_SIGNATURE_EXPIRED)) {
3498
3499 r = dns_transaction_dnskey_authenticated(t, rr);
3500 if (r < 0 && r != -ENXIO)
3501 return r;
3502 if (r == 0) {
3503 /* The DNSKEY transaction was not authenticated, this means there's
3504 * no DS for this, which means it's OK if no keys are found for this signature. */
3505
3506 r = dns_answer_move_by_key(validated, &t->answer, rr->key, 0, NULL);
3507 if (r < 0)
3508 return r;
3509
3510 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, rr->key);
3511 return 1;
3512 }
3513 }
3514
3515 r = dns_transaction_is_primary_response(t, rr);
3516 if (r < 0)
3517 return r;
3518 if (r > 0) {
3519 /* Look for a matching DNAME for this CNAME */
3520 r = dns_answer_has_dname_for_cname(t->answer, rr);
3521 if (r < 0)
3522 return r;
3523 if (r == 0) {
3524 /* Also look among the stuff we already validated */
3525 r = dns_answer_has_dname_for_cname(*validated, rr);
3526 if (r < 0)
3527 return r;
3528 }
3529
3530 if (r == 0) {
3531 if (IN_SET(result,
3532 DNSSEC_INVALID,
3533 DNSSEC_SIGNATURE_EXPIRED,
3534 DNSSEC_NO_SIGNATURE))
3535 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, rr->key);
3536 else /* DNSSEC_MISSING_KEY, DNSSEC_UNSUPPORTED_ALGORITHM,
3537 or DNSSEC_TOO_MANY_VALIDATIONS */
3538 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, rr->key);
3539
3540 /* This is a primary response to our question, and it failed validation.
3541 * That's fatal. */
3542 t->answer_dnssec_result = result;
3543 return 0;
3544 }
3545
3546 /* This is a primary response, but we do have a DNAME RR
3547 * in the RR that can replay this CNAME, hence rely on
3548 * that, and we can remove the CNAME in favour of it. */
3549 }
3550
3551 /* This is just some auxiliary data. Just remove the RRset and continue. */
3552 r = dns_answer_remove_by_key(&t->answer, rr->key);
3553 if (r < 0)
3554 return r;
3555
3556 /* We dropped something from the answer, start from the beginning. */
3557 return 1;
3558 }
3559
3560 return 2; /* Finito. */
3561}
3562
3563int dns_transaction_validate_dnssec(DnsTransaction *t) {
3564 _cleanup_(dns_answer_unrefp) DnsAnswer *validated = NULL;
3565 Phase phase;
3566 DnsAnswerFlags flags;
3567 int r;
3568 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
3569
3570 assert(t);
3571
3572 /* We have now collected all DS and DNSKEY RRs in t->validated_keys, let's see which RRs we can now
3573 * authenticate with that. */
3574
3575 if (FLAGS_SET(t->query_flags, SD_RESOLVED_NO_VALIDATE) || t->scope->dnssec_mode == DNSSEC_NO)
3576 return 0;
3577
3578 /* Already validated */
3579 if (t->answer_dnssec_result != _DNSSEC_RESULT_INVALID)
3580 return 0;
3581
3582 /* Our own stuff needs no validation */
3583 if (IN_SET(t->answer_source, DNS_TRANSACTION_ZONE, DNS_TRANSACTION_TRUST_ANCHOR)) {
3584 t->answer_dnssec_result = DNSSEC_VALIDATED;
3585 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true);
3586 return 0;
3587 }
3588
3589 /* Cached stuff is not affected by validation. */
3590 if (t->answer_source != DNS_TRANSACTION_NETWORK)
3591 return 0;
3592
3593 if (!dns_transaction_dnssec_supported_full(t)) {
3594 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3595 t->answer_dnssec_result = DNSSEC_INCOMPATIBLE_SERVER;
3596 log_debug("Not validating response for %" PRIu16 ", used server feature level does not support DNSSEC.", t->id);
3597 return 0;
3598 }
3599
3600 log_debug("Validating response from transaction %" PRIu16 " (%s).",
3601 t->id,
3602 dns_resource_key_to_string(dns_transaction_key(t), key_str, sizeof key_str));
3603
3604 /* First, see if this response contains any revoked trust
3605 * anchors we care about */
3606 r = dns_transaction_check_revoked_trust_anchors(t);
3607 if (r < 0)
3608 return r;
3609
3610 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3611 r = dns_transaction_copy_validated(t);
3612 if (r < 0)
3613 return r;
3614
3615 /* Second, see if there are DNSKEYs we already know a
3616 * validated DS for. */
3617 r = dns_transaction_validate_dnskey_by_ds(t);
3618 if (r < 0)
3619 return r;
3620
3621 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3622 * anchor says are revoked. After all we might have marked
3623 * some keys revoked above, but they might still be lingering
3624 * in our validated_keys list. */
3625 r = dns_transaction_invalidate_revoked_keys(t);
3626 if (r < 0)
3627 return r;
3628
3629 phase = DNSSEC_PHASE_DNSKEY;
3630 for (unsigned nvalidations = 0;;) {
3631 bool have_nsec = false;
3632
3633 r = dnssec_validate_records(t, phase, &have_nsec, &nvalidations, &validated);
3634 if (r <= 0) {
3635 DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated));
3636 return r;
3637 }
3638
3639 if (nvalidations > DNSSEC_VALIDATION_MAX) {
3640 /* This reply requires an onerous number of signature validations to verify. Let's
3641 * not waste our time trying, as this shouldn't happen for well-behaved domains
3642 * anyway. */
3643 t->answer_dnssec_result = DNSSEC_TOO_MANY_VALIDATIONS;
3644 DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated));
3645 return 0;
3646 }
3647
3648 /* Try again as long as we managed to achieve something */
3649 if (r == 1)
3650 continue;
3651
3652 if (phase == DNSSEC_PHASE_DNSKEY && have_nsec) {
3653 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3654 phase = DNSSEC_PHASE_NSEC;
3655 continue;
3656 }
3657
3658 if (phase != DNSSEC_PHASE_ALL) {
3659 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3660 * Note that in this third phase we start to remove RRs we couldn't validate. */
3661 phase = DNSSEC_PHASE_ALL;
3662 continue;
3663 }
3664
3665 /* We're done */
3666 break;
3667 }
3668
3669 DNS_ANSWER_REPLACE(t->answer, TAKE_PTR(validated));
3670
3671 /* At this point the answer only contains validated
3672 * RRsets. Now, let's see if it actually answers the question
3673 * we asked. If so, great! If it doesn't, then see if
3674 * NSEC/NSEC3 can prove this. */
3675 r = dns_transaction_has_positive_answer(t, &flags);
3676 if (r > 0) {
3677 /* Yes, it answers the question! */
3678
3679 if (flags & DNS_ANSWER_AUTHENTICATED) {
3680 /* The answer is fully authenticated, yay. */
3681 t->answer_dnssec_result = DNSSEC_VALIDATED;
3682 t->answer_rcode = DNS_RCODE_SUCCESS;
3683 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, true);
3684 } else {
3685 /* The answer is not fully authenticated. */
3686 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3687 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false);
3688 }
3689
3690 } else if (r == 0) {
3691 DnssecNsecResult nr;
3692 bool authenticated = false;
3693
3694 /* Bummer! Let's check NSEC/NSEC3 */
3695 r = dnssec_nsec_test(t->answer, dns_transaction_key(t), &nr, &authenticated, &t->answer_nsec_ttl);
3696 if (r < 0)
3697 return r;
3698
3699 switch (nr) {
3700
3701 case DNSSEC_NSEC_NXDOMAIN:
3702 /* NSEC proves the domain doesn't exist. Very good. */
3703 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3704 t->answer_dnssec_result = DNSSEC_VALIDATED;
3705 t->answer_rcode = DNS_RCODE_NXDOMAIN;
3706 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated);
3707
3708 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t));
3709 break;
3710
3711 case DNSSEC_NSEC_NODATA:
3712 /* NSEC proves that there's no data here, very good. */
3713 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3714 t->answer_dnssec_result = DNSSEC_VALIDATED;
3715 t->answer_rcode = DNS_RCODE_SUCCESS;
3716 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, authenticated);
3717
3718 manager_dnssec_verdict(t->scope->manager, authenticated ? DNSSEC_SECURE : DNSSEC_INSECURE, dns_transaction_key(t));
3719 break;
3720
3721 case DNSSEC_NSEC_OPTOUT:
3722 /* NSEC3 says the data might not be signed */
3723 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t->id, key_str);
3724 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3725 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false);
3726
3727 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t));
3728 break;
3729
3730 case DNSSEC_NSEC_NO_RR:
3731 /* No NSEC data? Bummer! */
3732
3733 r = dns_transaction_requires_nsec(t);
3734 if (r < 0)
3735 return r;
3736 if (r > 0) {
3737 t->answer_dnssec_result = DNSSEC_NO_SIGNATURE;
3738 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t));
3739 } else {
3740 t->answer_dnssec_result = DNSSEC_UNSIGNED;
3741 SET_FLAG(t->answer_query_flags, SD_RESOLVED_AUTHENTICATED, false);
3742 manager_dnssec_verdict(t->scope->manager, DNSSEC_INSECURE, dns_transaction_key(t));
3743 }
3744
3745 break;
3746
3747 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM:
3748 /* We don't know the NSEC3 algorithm used? */
3749 t->answer_dnssec_result = DNSSEC_UNSUPPORTED_ALGORITHM;
3750 manager_dnssec_verdict(t->scope->manager, DNSSEC_INDETERMINATE, dns_transaction_key(t));
3751 break;
3752
3753 case DNSSEC_NSEC_FOUND:
3754 case DNSSEC_NSEC_CNAME:
3755 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3756 t->answer_dnssec_result = DNSSEC_NSEC_MISMATCH;
3757 manager_dnssec_verdict(t->scope->manager, DNSSEC_BOGUS, dns_transaction_key(t));
3758 break;
3759
3760 default:
3761 assert_not_reached();
3762 }
3763 }
3764
3765 return 1;
3766}
3767
3768static const char* const dns_transaction_state_table[_DNS_TRANSACTION_STATE_MAX] = {
3769 [DNS_TRANSACTION_NULL] = "null",
3770 [DNS_TRANSACTION_PENDING] = "pending",
3771 [DNS_TRANSACTION_VALIDATING] = "validating",
3772 [DNS_TRANSACTION_RCODE_FAILURE] = "rcode-failure",
3773 [DNS_TRANSACTION_SUCCESS] = "success",
3774 [DNS_TRANSACTION_NO_SERVERS] = "no-servers",
3775 [DNS_TRANSACTION_TIMEOUT] = "timeout",
3776 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED] = "attempts-max-reached",
3777 [DNS_TRANSACTION_INVALID_REPLY] = "invalid-reply",
3778 [DNS_TRANSACTION_ERRNO] = "errno",
3779 [DNS_TRANSACTION_ABORTED] = "aborted",
3780 [DNS_TRANSACTION_DNSSEC_FAILED] = "dnssec-failed",
3781 [DNS_TRANSACTION_NO_TRUST_ANCHOR] = "no-trust-anchor",
3782 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED] = "rr-type-unsupported",
3783 [DNS_TRANSACTION_NETWORK_DOWN] = "network-down",
3784 [DNS_TRANSACTION_NOT_FOUND] = "not-found",
3785 [DNS_TRANSACTION_NO_SOURCE] = "no-source",
3786 [DNS_TRANSACTION_STUB_LOOP] = "stub-loop",
3787};
3788DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state, DnsTransactionState);
3789
3790static const char* const dns_transaction_source_table[_DNS_TRANSACTION_SOURCE_MAX] = {
3791 [DNS_TRANSACTION_NETWORK] = "network",
3792 [DNS_TRANSACTION_CACHE] = "cache",
3793 [DNS_TRANSACTION_ZONE] = "zone",
3794 [DNS_TRANSACTION_TRUST_ANCHOR] = "trust-anchor",
3795};
3796DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source, DnsTransactionSource);