1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2014 Lennart Poettering
8 #include "sd-messages.h"
11 #include "alloc-util.h"
12 #include "dns-domain.h"
13 #include "errno-list.h"
15 #include "random-util.h"
16 #include "resolved-dns-cache.h"
17 #include "resolved-dns-transaction.h"
18 #include "resolved-llmnr.h"
19 #include "string-table.h"
21 #define TRANSACTIONS_MAX 4096
22 #define TRANSACTION_TCP_TIMEOUT_USEC (10U*USEC_PER_SEC)
24 static void dns_transaction_reset_answer(DnsTransaction
*t
) {
27 t
->received
= dns_packet_unref(t
->received
);
28 t
->answer
= dns_answer_unref(t
->answer
);
30 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
31 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
32 t
->answer_authenticated
= false;
33 t
->answer_nsec_ttl
= (uint32_t) -1;
37 static void dns_transaction_flush_dnssec_transactions(DnsTransaction
*t
) {
42 while ((z
= set_steal_first(t
->dnssec_transactions
))) {
43 set_remove(z
->notify_transactions
, t
);
44 set_remove(z
->notify_transactions_done
, t
);
45 dns_transaction_gc(z
);
49 static void dns_transaction_close_connection(DnsTransaction
*t
) {
53 /* Let's detach the stream from our transaction, in case something else keeps a reference to it. */
54 t
->stream
->complete
= NULL
;
55 t
->stream
->on_packet
= NULL
;
56 t
->stream
->transaction
= NULL
;
57 t
->stream
= dns_stream_unref(t
->stream
);
60 t
->dns_udp_event_source
= sd_event_source_unref(t
->dns_udp_event_source
);
61 t
->dns_udp_fd
= safe_close(t
->dns_udp_fd
);
64 static void dns_transaction_stop_timeout(DnsTransaction
*t
) {
67 t
->timeout_event_source
= sd_event_source_unref(t
->timeout_event_source
);
70 DnsTransaction
* dns_transaction_free(DnsTransaction
*t
) {
78 log_debug("Freeing transaction %" PRIu16
".", t
->id
);
80 dns_transaction_close_connection(t
);
81 dns_transaction_stop_timeout(t
);
83 dns_packet_unref(t
->sent
);
84 dns_transaction_reset_answer(t
);
86 dns_server_unref(t
->server
);
89 hashmap_remove_value(t
->scope
->transactions_by_key
, t
->key
, t
);
90 LIST_REMOVE(transactions_by_scope
, t
->scope
->transactions
, t
);
93 hashmap_remove(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
96 while ((c
= set_steal_first(t
->notify_query_candidates
)))
97 set_remove(c
->transactions
, t
);
98 set_free(t
->notify_query_candidates
);
100 while ((c
= set_steal_first(t
->notify_query_candidates_done
)))
101 set_remove(c
->transactions
, t
);
102 set_free(t
->notify_query_candidates_done
);
104 while ((i
= set_steal_first(t
->notify_zone_items
)))
105 i
->probe_transaction
= NULL
;
106 set_free(t
->notify_zone_items
);
108 while ((i
= set_steal_first(t
->notify_zone_items_done
)))
109 i
->probe_transaction
= NULL
;
110 set_free(t
->notify_zone_items_done
);
112 while ((z
= set_steal_first(t
->notify_transactions
)))
113 set_remove(z
->dnssec_transactions
, t
);
114 set_free(t
->notify_transactions
);
116 while ((z
= set_steal_first(t
->notify_transactions_done
)))
117 set_remove(z
->dnssec_transactions
, t
);
118 set_free(t
->notify_transactions_done
);
120 dns_transaction_flush_dnssec_transactions(t
);
121 set_free(t
->dnssec_transactions
);
123 dns_answer_unref(t
->validated_keys
);
124 dns_resource_key_unref(t
->key
);
129 DEFINE_TRIVIAL_CLEANUP_FUNC(DnsTransaction
*, dns_transaction_free
);
131 bool dns_transaction_gc(DnsTransaction
*t
) {
137 if (set_isempty(t
->notify_query_candidates
) &&
138 set_isempty(t
->notify_query_candidates_done
) &&
139 set_isempty(t
->notify_zone_items
) &&
140 set_isempty(t
->notify_zone_items_done
) &&
141 set_isempty(t
->notify_transactions
) &&
142 set_isempty(t
->notify_transactions_done
)) {
143 dns_transaction_free(t
);
150 static uint16_t pick_new_id(Manager
*m
) {
153 /* Find a fresh, unused transaction id. Note that this loop is bounded because there's a limit on the number of
154 * transactions, and it's much lower than the space of IDs. */
156 assert_cc(TRANSACTIONS_MAX
< 0xFFFF);
159 random_bytes(&new_id
, sizeof(new_id
));
160 while (new_id
== 0 ||
161 hashmap_get(m
->dns_transactions
, UINT_TO_PTR(new_id
)));
166 int dns_transaction_new(DnsTransaction
**ret
, DnsScope
*s
, DnsResourceKey
*key
) {
167 _cleanup_(dns_transaction_freep
) DnsTransaction
*t
= NULL
;
174 /* Don't allow looking up invalid or pseudo RRs */
175 if (!dns_type_is_valid_query(key
->type
))
177 if (dns_type_is_obsolete(key
->type
))
180 /* We only support the IN class */
181 if (!IN_SET(key
->class, DNS_CLASS_IN
, DNS_CLASS_ANY
))
184 if (hashmap_size(s
->manager
->dns_transactions
) >= TRANSACTIONS_MAX
)
187 r
= hashmap_ensure_allocated(&s
->manager
->dns_transactions
, NULL
);
191 r
= hashmap_ensure_allocated(&s
->transactions_by_key
, &dns_resource_key_hash_ops
);
195 t
= new0(DnsTransaction
, 1);
200 t
->answer_source
= _DNS_TRANSACTION_SOURCE_INVALID
;
201 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
202 t
->answer_nsec_ttl
= (uint32_t) -1;
203 t
->key
= dns_resource_key_ref(key
);
204 t
->current_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
205 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
207 t
->id
= pick_new_id(s
->manager
);
209 r
= hashmap_put(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), t
);
215 r
= hashmap_replace(s
->transactions_by_key
, t
->key
, t
);
217 hashmap_remove(s
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
));
221 LIST_PREPEND(transactions_by_scope
, s
->transactions
, t
);
224 s
->manager
->n_transactions_total
++;
234 static void dns_transaction_shuffle_id(DnsTransaction
*t
) {
238 /* Pick a new ID for this transaction. */
240 new_id
= pick_new_id(t
->scope
->manager
);
241 assert_se(hashmap_remove_and_put(t
->scope
->manager
->dns_transactions
, UINT_TO_PTR(t
->id
), UINT_TO_PTR(new_id
), t
) >= 0);
243 log_debug("Transaction %" PRIu16
" is now %" PRIu16
".", t
->id
, new_id
);
246 /* Make sure we generate a new packet with the new ID */
247 t
->sent
= dns_packet_unref(t
->sent
);
250 static void dns_transaction_tentative(DnsTransaction
*t
, DnsPacket
*p
) {
251 _cleanup_free_
char *pretty
= NULL
;
252 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
258 if (manager_our_packet(t
->scope
->manager
, p
) != 0)
261 (void) in_addr_to_string(p
->family
, &p
->sender
, &pretty
);
263 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s got tentative packet from %s.",
265 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
266 dns_protocol_to_string(t
->scope
->protocol
),
267 t
->scope
->link
? t
->scope
->link
->name
: "*",
268 af_to_name_short(t
->scope
->family
),
271 /* RFC 4795, Section 4.1 says that the peer with the
272 * lexicographically smaller IP address loses */
273 if (memcmp(&p
->sender
, &p
->destination
, FAMILY_ADDRESS_SIZE(p
->family
)) >= 0) {
274 log_debug("Peer has lexicographically larger IP address and thus lost in the conflict.");
278 log_debug("We have the lexicographically larger IP address and thus lost in the conflict.");
282 while ((z
= set_first(t
->notify_zone_items
))) {
283 /* First, make sure the zone item drops the reference
285 dns_zone_item_probe_stop(z
);
287 /* Secondly, report this as conflict, so that we might
288 * look for a different hostname */
289 dns_zone_item_conflict(z
);
293 dns_transaction_gc(t
);
296 void dns_transaction_complete(DnsTransaction
*t
, DnsTransactionState state
) {
297 DnsQueryCandidate
*c
;
301 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
304 assert(!DNS_TRANSACTION_IS_LIVE(state
));
306 if (state
== DNS_TRANSACTION_DNSSEC_FAILED
) {
307 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
);
309 log_struct(LOG_NOTICE
,
310 "MESSAGE_ID=" SD_MESSAGE_DNSSEC_FAILURE_STR
,
311 LOG_MESSAGE("DNSSEC validation failed for question %s: %s", key_str
, dnssec_result_to_string(t
->answer_dnssec_result
)),
312 "DNS_TRANSACTION=%" PRIu16
, t
->id
,
313 "DNS_QUESTION=%s", key_str
,
314 "DNSSEC_RESULT=%s", dnssec_result_to_string(t
->answer_dnssec_result
),
315 "DNS_SERVER=%s", dns_server_string(t
->server
),
316 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(t
->server
->possible_feature_level
));
319 /* Note that this call might invalidate the query. Callers
320 * should hence not attempt to access the query or transaction
321 * after calling this function. */
323 if (state
== DNS_TRANSACTION_ERRNO
)
324 st
= errno_to_name(t
->answer_errno
);
326 st
= dns_transaction_state_to_string(state
);
328 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
330 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
331 dns_protocol_to_string(t
->scope
->protocol
),
332 t
->scope
->link
? t
->scope
->link
->name
: "*",
333 af_to_name_short(t
->scope
->family
),
335 t
->answer_source
< 0 ? "none" : dns_transaction_source_to_string(t
->answer_source
),
336 t
->answer_authenticated
? "authenticated" : "unsigned");
340 dns_transaction_close_connection(t
);
341 dns_transaction_stop_timeout(t
);
343 /* Notify all queries that are interested, but make sure the
344 * transaction isn't freed while we are still looking at it */
347 SET_FOREACH_MOVE(c
, t
->notify_query_candidates_done
, t
->notify_query_candidates
)
348 dns_query_candidate_notify(c
);
349 SWAP_TWO(t
->notify_query_candidates
, t
->notify_query_candidates_done
);
351 SET_FOREACH_MOVE(z
, t
->notify_zone_items_done
, t
->notify_zone_items
)
352 dns_zone_item_notify(z
);
353 SWAP_TWO(t
->notify_zone_items
, t
->notify_zone_items_done
);
354 if (t
->probing
&& t
->state
== DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
)
355 (void) dns_scope_announce(t
->scope
, false);
357 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
358 dns_transaction_notify(d
, t
);
359 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
362 dns_transaction_gc(t
);
365 static int dns_transaction_pick_server(DnsTransaction
*t
) {
369 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
371 /* Pick a DNS server and a feature level for it. */
373 server
= dns_scope_get_dns_server(t
->scope
);
377 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
378 * different properties. */
379 if (server
!= t
->server
)
380 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
382 t
->current_feature_level
= dns_server_possible_feature_level(server
);
384 /* Clamp the feature level if that is requested. */
385 if (t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
386 t
->current_feature_level
> t
->clamp_feature_level
)
387 t
->current_feature_level
= t
->clamp_feature_level
;
389 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t
->current_feature_level
), t
->id
);
391 if (server
== t
->server
)
394 dns_server_unref(t
->server
);
395 t
->server
= dns_server_ref(server
);
397 t
->n_picked_servers
++;
399 log_debug("Using DNS server %s for transaction %u.", dns_server_string(t
->server
), t
->id
);
404 static void dns_transaction_retry(DnsTransaction
*t
, bool next_server
) {
409 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
411 /* Before we try again, switch to a new server. */
413 dns_scope_next_dns_server(t
->scope
);
415 r
= dns_transaction_go(t
);
417 t
->answer_errno
= -r
;
418 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
422 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
427 /* Returns > 0 if the transaction was restarted, 0 if not */
432 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
435 /* The server's current feature level is lower than when we sent the original query. We learnt something from
436 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
437 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
438 OPT RR or DO bit. One of these cases is documented here, for example:
439 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
441 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
442 dns_transaction_shuffle_id(t
);
444 r
= dns_transaction_go(t
);
451 static int on_stream_complete(DnsStream
*s
, int error
) {
452 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
456 assert(s
->transaction
);
458 /* Copy the data we care about out of the stream before we
461 p
= dns_packet_ref(s
->read_packet
);
463 dns_transaction_close_connection(t
);
465 if (ERRNO_IS_DISCONNECT(error
)) {
468 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
469 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
470 * question on this scope. */
471 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
475 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
476 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
477 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
479 dns_transaction_retry(t
, true);
483 t
->answer_errno
= error
;
484 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
488 if (dns_packet_validate_reply(p
) <= 0) {
489 log_debug("Invalid TCP reply packet.");
490 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
494 dns_scope_check_conflicts(t
->scope
, p
);
497 dns_transaction_process_reply(t
, p
);
500 /* If the response wasn't useful, then complete the transition
501 * now. After all, we are the worst feature set now with TCP
502 * sockets, and there's really no point in retrying. */
503 if (t
->state
== DNS_TRANSACTION_PENDING
)
504 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
506 dns_transaction_gc(t
);
511 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
512 _cleanup_close_
int fd
= -1;
517 dns_transaction_close_connection(t
);
519 switch (t
->scope
->protocol
) {
521 case DNS_PROTOCOL_DNS
:
522 r
= dns_transaction_pick_server(t
);
526 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
529 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
533 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
536 case DNS_PROTOCOL_LLMNR
:
537 /* When we already received a reply to this (but it was truncated), send to its sender address */
539 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
541 union in_addr_union address
;
542 int family
= AF_UNSPEC
;
544 /* Otherwise, try to talk to the owner of a
545 * the IP address, in case this is a reverse
548 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
553 if (family
!= t
->scope
->family
)
556 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
562 return -EAFNOSUPPORT
;
568 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
573 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
575 t
->stream
= dns_stream_unref(t
->stream
);
579 t
->stream
->complete
= on_stream_complete
;
580 t
->stream
->transaction
= t
;
582 /* The interface index is difficult to determine if we are
583 * connecting to the local host, hence fill this in right away
584 * instead of determining it from the socket */
585 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
587 dns_transaction_reset_answer(t
);
589 t
->tried_stream
= true;
594 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
597 /* For mDNS we cache whenever we get the packet, rather than
598 * in each transaction. */
599 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
602 /* Caching disabled? */
603 if (!t
->scope
->manager
->enable_cache
)
606 /* We never cache if this packet is from the local host, under
607 * the assumption that a locally running DNS server would
608 * cache this anyway, and probably knows better when to flush
609 * the cache then we could. */
610 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
613 dns_cache_put(&t
->scope
->cache
,
617 t
->answer_authenticated
,
621 &t
->received
->sender
);
624 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
630 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
631 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
637 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
643 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
644 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
646 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
650 case DNS_TRANSACTION_NULL
:
651 case DNS_TRANSACTION_PENDING
:
652 case DNS_TRANSACTION_VALIDATING
:
656 case DNS_TRANSACTION_RCODE_FAILURE
:
657 if (!IN_SET(dt
->answer_rcode
, DNS_RCODE_NXDOMAIN
, DNS_RCODE_SERVFAIL
)) {
658 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
662 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
663 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
664 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
665 * RRs to make unsigned proofs. */
667 case DNS_TRANSACTION_SUCCESS
:
671 case DNS_TRANSACTION_DNSSEC_FAILED
:
672 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
673 * validationr result */
675 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
676 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
677 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
681 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
686 /* All is ready, we can go and validate */
690 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
691 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
695 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
700 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
701 r
= dns_transaction_dnssec_ready(t
);
704 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
707 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
708 * restart the lookup immediately. */
709 r
= dns_transaction_maybe_restart(t
);
712 if (r
> 0) /* Transaction got restarted... */
715 /* All our auxiliary DNSSEC transactions are complete now. Try
716 * to validate our RRset now. */
717 r
= dns_transaction_validate_dnssec(t
);
719 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
725 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
726 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
728 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
731 if (t
->n_picked_servers
< dns_scope_get_n_dns_servers(t
->scope
)) {
732 /* We tried fewer servers on this transaction than we know, let's try another one then */
733 dns_transaction_retry(t
, true);
737 /* OK, let's give up, apparently all servers we tried didn't work. */
738 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
742 if (!IN_SET(t
->answer_dnssec_result
,
743 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
744 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
745 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
746 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
747 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
751 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
752 dns_server_warn_downgrade(t
->server
);
754 dns_transaction_cache_answer(t
);
756 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
757 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
759 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
764 t
->answer_errno
= -r
;
765 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
768 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
773 /* Checks whether the answer is positive, i.e. either a direct
774 * answer to the question, or a CNAME/DNAME for it */
776 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
780 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
787 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
792 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
793 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
794 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
795 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
796 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
797 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
798 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
799 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
800 * incomplete CNAME/DNAME chain.
802 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
803 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
806 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
809 r
= dns_transaction_has_positive_answer(t
, NULL
);
813 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
817 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
824 assert(t
->scope
->manager
);
826 if (t
->state
!= DNS_TRANSACTION_PENDING
)
829 /* Note that this call might invalidate the query. Callers
830 * should hence not attempt to access the query or transaction
831 * after calling this function. */
833 log_debug("Processing incoming packet on transaction %" PRIu16
". (rcode=%s)", t
->id
, dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
835 switch (t
->scope
->protocol
) {
837 case DNS_PROTOCOL_LLMNR
:
838 /* For LLMNR we will not accept any packets from other interfaces */
840 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
843 if (p
->family
!= t
->scope
->family
)
846 /* Tentative packets are not full responses but still
847 * useful for identifying uniqueness conflicts during
849 if (DNS_PACKET_LLMNR_T(p
)) {
850 dns_transaction_tentative(t
, p
);
856 case DNS_PROTOCOL_MDNS
:
857 /* For mDNS we will not accept any packets from other interfaces */
859 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
862 if (p
->family
!= t
->scope
->family
)
867 case DNS_PROTOCOL_DNS
:
868 /* Note that we do not need to verify the
869 * addresses/port numbers of incoming traffic, as we
870 * invoked connect() on our UDP socket in which case
871 * the kernel already does the needed verification for
876 assert_not_reached("Invalid DNS protocol.");
879 if (t
->received
!= p
) {
880 dns_packet_unref(t
->received
);
881 t
->received
= dns_packet_ref(p
);
884 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
886 if (p
->ipproto
== IPPROTO_TCP
) {
887 if (DNS_PACKET_TC(p
)) {
888 /* Truncated via TCP? Somebody must be fucking with us */
889 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
893 if (DNS_PACKET_ID(p
) != t
->id
) {
894 /* Not the reply to our query? Somebody must be fucking with us */
895 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
900 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
902 switch (t
->scope
->protocol
) {
904 case DNS_PROTOCOL_DNS
:
907 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
909 /* Request failed, immediately try again with reduced features */
911 if (t
->current_feature_level
<= DNS_SERVER_FEATURE_LEVEL_UDP
) {
913 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
914 * this transaction anymore, but let's see if it might make sense to send the request
915 * to a different DNS server instead. If not let's process the response, and accept the
916 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
917 * packet loss, but is not going to give us better rcodes should we actually have
918 * managed to get them already at UDP level. */
920 if (t
->n_picked_servers
< dns_scope_get_n_dns_servers(t
->scope
)) {
921 /* We tried fewer servers on this transaction than we know, let's try another one then */
922 dns_transaction_retry(t
, true);
926 /* Give up, accept the rcode */
927 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
931 /* Reduce this feature level by one and try again. */
932 t
->clamp_feature_level
= t
->current_feature_level
- 1;
934 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
935 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
936 dns_server_feature_level_to_string(t
->clamp_feature_level
));
938 dns_transaction_retry(t
, false /* use the same server */);
942 if (DNS_PACKET_RCODE(p
) == DNS_RCODE_REFUSED
) {
943 /* This server refused our request? If so, try again, use a different server */
944 log_debug("Server returned REFUSED, switching servers, and retrying.");
945 dns_transaction_retry(t
, true /* pick a new server */);
949 if (DNS_PACKET_TC(p
))
950 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
954 case DNS_PROTOCOL_LLMNR
:
955 case DNS_PROTOCOL_MDNS
:
956 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
960 assert_not_reached("Invalid DNS protocol.");
963 if (DNS_PACKET_TC(p
)) {
965 /* Truncated packets for mDNS are not allowed. Give up immediately. */
966 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
967 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
971 log_debug("Reply truncated, retrying via TCP.");
973 /* Response was truncated, let's try again with good old TCP */
974 r
= dns_transaction_open_tcp(t
);
976 /* No servers found? Damn! */
977 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
980 if (r
== -EOPNOTSUPP
) {
981 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
982 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
986 /* On LLMNR, if we cannot connect to the host,
987 * we immediately give up */
988 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
991 /* On DNS, couldn't send? Try immediately again, with a new server */
992 dns_transaction_retry(t
, true);
998 /* After the superficial checks, actually parse the message. */
999 r
= dns_packet_extract(p
);
1001 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1006 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1007 * rcode and subsequently downgraded the protocol */
1009 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_SUCCESS
, DNS_RCODE_NXDOMAIN
) &&
1010 t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
)
1011 dns_server_packet_rcode_downgrade(t
->server
, t
->clamp_feature_level
);
1013 /* Report that the OPT RR was missing */
1015 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
1017 /* Report that we successfully received a packet */
1018 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
1021 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1022 r
= dns_transaction_maybe_restart(t
);
1025 if (r
> 0) /* Transaction got restarted... */
1028 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1030 /* When dealing with protocols other than mDNS only consider responses with
1031 * equivalent query section to the request. For mDNS this check doesn't make
1032 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1033 * contain any questions in the Question Section". */
1034 if (t
->scope
->protocol
!= DNS_PROTOCOL_MDNS
) {
1035 r
= dns_packet_is_reply_for(p
, t
->key
);
1039 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1044 /* Install the answer as answer to the transaction */
1045 dns_answer_unref(t
->answer
);
1046 t
->answer
= dns_answer_ref(p
->answer
);
1047 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
1048 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
1049 t
->answer_authenticated
= false;
1051 r
= dns_transaction_fix_rcode(t
);
1055 /* Block GC while starting requests for additional DNSSEC RRs */
1057 r
= dns_transaction_request_dnssec_keys(t
);
1060 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1061 if (!dns_transaction_gc(t
))
1064 /* Requesting additional keys might have resulted in
1065 * this transaction to fail, since the auxiliary
1066 * request failed for some reason. If so, we are not
1067 * in pending state anymore, and we should exit
1069 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1074 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1075 t
->state
= DNS_TRANSACTION_VALIDATING
;
1076 dns_transaction_close_connection(t
);
1077 dns_transaction_stop_timeout(t
);
1082 dns_transaction_process_dnssec(t
);
1086 t
->answer_errno
= -r
;
1087 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1090 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1091 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1092 DnsTransaction
*t
= userdata
;
1098 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1099 if (ERRNO_IS_DISCONNECT(-r
)) {
1102 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1103 * recvmsg(). Treat this like a lost packet. */
1105 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1106 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1107 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1109 dns_transaction_retry(t
, true);
1113 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1114 t
->answer_errno
= -r
;
1118 r
= dns_packet_validate_reply(p
);
1120 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1124 log_debug("Received inappropriate DNS packet as response, ignoring.");
1128 if (DNS_PACKET_ID(p
) != t
->id
) {
1129 log_debug("Received packet with incorrect transaction ID, ignoring.");
1133 dns_transaction_process_reply(t
, p
);
1137 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1142 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1144 r
= dns_transaction_pick_server(t
);
1148 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1149 return -EAGAIN
; /* Sorry, can't do UDP, try TCP! */
1151 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1154 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1157 dns_transaction_close_connection(t
);
1159 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1163 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1169 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1173 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1177 dns_transaction_close_connection(t
);
1179 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1183 dns_transaction_reset_answer(t
);
1188 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1189 DnsTransaction
*t
= userdata
;
1194 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1195 /* Timeout reached? Increase the timeout for the server used */
1196 switch (t
->scope
->protocol
) {
1198 case DNS_PROTOCOL_DNS
:
1200 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1203 case DNS_PROTOCOL_LLMNR
:
1204 case DNS_PROTOCOL_MDNS
:
1205 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1209 assert_not_reached("Invalid DNS protocol.");
1212 if (t
->initial_jitter_scheduled
)
1213 t
->initial_jitter_elapsed
= true;
1216 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1218 dns_transaction_retry(t
, true);
1222 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1226 switch (t
->scope
->protocol
) {
1228 case DNS_PROTOCOL_DNS
:
1230 /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
1231 * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
1234 return TRANSACTION_TCP_TIMEOUT_USEC
;
1237 return t
->server
->resend_timeout
;
1239 case DNS_PROTOCOL_MDNS
:
1240 assert(t
->n_attempts
> 0);
1242 return MDNS_PROBING_INTERVAL_USEC
;
1244 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1246 case DNS_PROTOCOL_LLMNR
:
1247 return t
->scope
->resend_timeout
;
1250 assert_not_reached("Invalid DNS protocol.");
1254 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1259 dns_transaction_stop_timeout(t
);
1261 r
= dns_scope_network_good(t
->scope
);
1265 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1269 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1270 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1274 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1275 /* If we already tried via a stream, then we don't
1276 * retry on LLMNR. See RFC 4795, Section 2.7. */
1277 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1284 dns_transaction_reset_answer(t
);
1285 dns_transaction_flush_dnssec_transactions(t
);
1287 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1288 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1289 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1293 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1294 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1295 t
->answer_authenticated
= true;
1296 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1300 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1301 t
->key
->type
== DNS_TYPE_DS
) {
1303 /* Hmm, this is a request for the root DS? A
1304 * DS RR doesn't exist in the root zone, and
1305 * if our trust anchor didn't know it either,
1306 * this means we cannot do any DNSSEC logic
1309 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1310 /* We are in downgrade mode. In this
1311 * case, synthesize an unsigned empty
1312 * response, so that the any lookup
1313 * depending on this one can continue
1314 * assuming there was no DS, and hence
1315 * the root zone was unsigned. */
1317 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1318 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1319 t
->answer_authenticated
= false;
1320 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1322 /* If we are not in downgrade mode,
1323 * then fail the lookup, because we
1324 * cannot reasonably answer it. There
1325 * might be DS RRs, but we don't know
1326 * them, and the DNS server won't tell
1327 * them to us (and even if it would,
1328 * we couldn't validate and trust them. */
1329 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1335 /* Check the zone, but only if this transaction is not used
1336 * for probing or verifying a zone item. */
1337 if (set_isempty(t
->notify_zone_items
)) {
1339 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1343 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1344 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1345 t
->answer_authenticated
= true;
1346 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1351 /* Check the cache, but only if this transaction is not used
1352 * for probing or verifying a zone item. */
1353 if (set_isempty(t
->notify_zone_items
)) {
1355 /* Before trying the cache, let's make sure we figured out a
1356 * server to use. Should this cause a change of server this
1357 * might flush the cache. */
1358 (void) dns_scope_get_dns_server(t
->scope
);
1360 /* Let's then prune all outdated entries */
1361 dns_cache_prune(&t
->scope
->cache
);
1363 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, t
->clamp_ttl
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1367 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1368 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1369 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1371 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1379 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1381 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1382 bool add_known_answers
= false;
1383 DnsTransaction
*other
;
1385 DnsResourceKey
*tkey
;
1386 _cleanup_set_free_ Set
*keys
= NULL
;
1388 unsigned nscount
= 0;
1393 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1395 /* Discard any previously prepared packet, so we can start over and coalesce again */
1396 t
->sent
= dns_packet_unref(t
->sent
);
1398 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1402 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1408 if (dns_key_is_shared(t
->key
))
1409 add_known_answers
= true;
1411 if (t
->key
->type
== DNS_TYPE_ANY
) {
1412 r
= set_ensure_allocated(&keys
, &dns_resource_key_hash_ops
);
1416 r
= set_put(keys
, t
->key
);
1422 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1423 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1424 * in our current scope, and see whether their timing contraints allow them to be sent.
1427 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1429 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1431 /* Skip ourselves */
1435 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1438 if (other
->next_attempt_after
> ts
)
1441 if (qdcount
>= UINT16_MAX
)
1444 r
= dns_packet_append_key(p
, other
->key
, 0, NULL
);
1447 * If we can't stuff more questions into the packet, just give up.
1448 * One of the 'other' transactions will fire later and take care of the rest.
1456 r
= dns_transaction_prepare(other
, ts
);
1460 ts
+= transaction_get_resend_timeout(other
);
1462 r
= sd_event_add_time(
1463 other
->scope
->manager
->event
,
1464 &other
->timeout_event_source
,
1465 clock_boottime_or_monotonic(),
1467 on_transaction_timeout
, other
);
1471 (void) sd_event_source_set_description(other
->timeout_event_source
, "dns-transaction-timeout");
1473 other
->state
= DNS_TRANSACTION_PENDING
;
1474 other
->next_attempt_after
= ts
;
1478 if (dns_key_is_shared(other
->key
))
1479 add_known_answers
= true;
1481 if (other
->key
->type
== DNS_TYPE_ANY
) {
1482 r
= set_ensure_allocated(&keys
, &dns_resource_key_hash_ops
);
1486 r
= set_put(keys
, other
->key
);
1492 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1494 /* Append known answer section if we're asking for any shared record */
1495 if (add_known_answers
) {
1496 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1501 SET_FOREACH(tkey
, keys
, i
) {
1502 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
1505 r
= dns_zone_lookup(&t
->scope
->zone
, tkey
, t
->scope
->link
->ifindex
, &answer
, NULL
, &tentative
);
1509 r
= dns_packet_append_answer(p
, answer
);
1513 nscount
+= dns_answer_size(answer
);
1515 DNS_PACKET_HEADER(p
)->nscount
= htobe16(nscount
);
1517 t
->sent
= TAKE_PTR(p
);
1522 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1523 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1528 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1529 return dns_transaction_make_packet_mdns(t
);
1534 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1538 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1542 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1543 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1545 t
->sent
= TAKE_PTR(p
);
1550 int dns_transaction_go(DnsTransaction
*t
) {
1553 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1557 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1560 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1562 r
= dns_transaction_prepare(t
, ts
);
1566 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1568 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1569 dns_protocol_to_string(t
->scope
->protocol
),
1570 t
->scope
->link
? t
->scope
->link
->name
: "*",
1571 af_to_name_short(t
->scope
->family
));
1573 if (!t
->initial_jitter_scheduled
&&
1574 IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1575 usec_t jitter
, accuracy
;
1577 /* RFC 4795 Section 2.7 suggests all queries should be
1578 * delayed by a random time from 0 to JITTER_INTERVAL. */
1580 t
->initial_jitter_scheduled
= true;
1582 random_bytes(&jitter
, sizeof(jitter
));
1584 switch (t
->scope
->protocol
) {
1586 case DNS_PROTOCOL_LLMNR
:
1587 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1588 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1591 case DNS_PROTOCOL_MDNS
:
1592 jitter
%= MDNS_JITTER_RANGE_USEC
;
1593 jitter
+= MDNS_JITTER_MIN_USEC
;
1594 accuracy
= MDNS_JITTER_RANGE_USEC
;
1597 assert_not_reached("bad protocol");
1600 r
= sd_event_add_time(
1601 t
->scope
->manager
->event
,
1602 &t
->timeout_event_source
,
1603 clock_boottime_or_monotonic(),
1604 ts
+ jitter
, accuracy
,
1605 on_transaction_timeout
, t
);
1609 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1612 t
->next_attempt_after
= ts
;
1613 t
->state
= DNS_TRANSACTION_PENDING
;
1615 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1619 /* Otherwise, we need to ask the network */
1620 r
= dns_transaction_make_packet(t
);
1624 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1625 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1626 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1628 /* RFC 4795, Section 2.4. says reverse lookups shall
1629 * always be made via TCP on LLMNR */
1630 r
= dns_transaction_open_tcp(t
);
1632 /* Try via UDP, and if that fails due to large size or lack of
1633 * support try via TCP */
1634 r
= dns_transaction_emit_udp(t
);
1636 log_debug("Sending query via TCP since it is too large.");
1637 else if (r
== -EAGAIN
)
1638 log_debug("Sending query via TCP since server doesn't support UDP.");
1639 if (IN_SET(r
, -EMSGSIZE
, -EAGAIN
))
1640 r
= dns_transaction_open_tcp(t
);
1644 /* No servers to send this to? */
1645 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1648 if (r
== -EOPNOTSUPP
) {
1649 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1650 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1653 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1654 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1655 * answer this request with this protocol. */
1656 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1660 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1663 /* Couldn't send? Try immediately again, with a new server */
1664 dns_scope_next_dns_server(t
->scope
);
1666 return dns_transaction_go(t
);
1669 ts
+= transaction_get_resend_timeout(t
);
1671 r
= sd_event_add_time(
1672 t
->scope
->manager
->event
,
1673 &t
->timeout_event_source
,
1674 clock_boottime_or_monotonic(),
1676 on_transaction_timeout
, t
);
1680 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1682 t
->state
= DNS_TRANSACTION_PENDING
;
1683 t
->next_attempt_after
= ts
;
1688 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1696 /* Try to find cyclic dependencies between transaction objects */
1701 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1702 r
= dns_transaction_find_cyclic(t
, n
);
1710 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1711 DnsTransaction
*aux
;
1718 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1720 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1724 if (set_contains(t
->dnssec_transactions
, aux
)) {
1729 r
= dns_transaction_find_cyclic(t
, aux
);
1733 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1735 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1737 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1739 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1745 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1749 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1753 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1757 r
= set_put(t
->dnssec_transactions
, aux
);
1761 r
= set_put(aux
->notify_transactions
, t
);
1763 (void) set_remove(t
->dnssec_transactions
, aux
);
1771 dns_transaction_gc(aux
);
1775 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1776 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1777 DnsTransaction
*aux
;
1783 /* Try to get the data from the trust anchor */
1784 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1788 r
= dns_answer_extend(&t
->validated_keys
, a
);
1795 /* This didn't work, ask for it via the network/cache then. */
1796 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1797 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1802 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1803 r
= dns_transaction_go(aux
);
1811 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1816 /* Check whether the specified name is in the NTA
1817 * database, either in the global one, or the link-local
1820 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1824 if (!t
->scope
->link
)
1827 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1830 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1835 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1836 * RRs to prove it */
1838 r
= dns_transaction_has_positive_answer(t
, NULL
);
1844 /* Is this key explicitly listed as a negative trust anchor?
1845 * If so, it's nothing we need to care about */
1846 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1852 /* The answer does not contain any RRs that match to the
1853 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1854 * included. If not, the answer is unsigned. */
1856 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1865 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1871 /* Check if the specified RR is the "primary" response,
1872 * i.e. either matches the question precisely or is a
1873 * CNAME/DNAME for it. */
1875 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1879 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1882 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1885 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1886 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1888 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1891 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1892 * be supported, hence return true. */
1896 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
1897 * the server is known to support currently, as the transaction feature level might be lower than what the
1898 * server actually supports, since we might have downgraded this transaction's feature level because we got a
1899 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
1901 return dns_server_dnssec_supported(t
->server
);
1904 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1910 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1912 if (!dns_transaction_dnssec_supported(t
))
1915 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1916 if (!dns_transaction_dnssec_supported(dt
))
1922 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1923 DnsResourceRecord
*rr
;
1930 * Retrieve all auxiliary RRs for the answer we got, so that
1931 * we can verify signatures or prove that RRs are rightfully
1932 * unsigned. Specifically:
1934 * - For RRSIG we get the matching DNSKEY
1935 * - For DNSKEY we get the matching DS
1936 * - For unsigned SOA/NS we get the matching DS
1937 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1938 * - For other unsigned RRs we get the matching SOA RR
1939 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1940 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1941 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1944 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1946 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1947 return 0; /* We only need to validate stuff from the network */
1948 if (!dns_transaction_dnssec_supported(t
))
1949 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1951 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1953 if (dns_type_is_pseudo(rr
->key
->type
))
1956 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1957 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1963 switch (rr
->key
->type
) {
1965 case DNS_TYPE_RRSIG
: {
1966 /* For each RRSIG we request the matching DNSKEY */
1967 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1969 /* If this RRSIG is about a DNSKEY RR and the
1970 * signer is the same as the owner, then we
1971 * already have the DNSKEY, and we don't have
1972 * to look for more. */
1973 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1974 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1981 /* If the signer is not a parent of our
1982 * original query, then this is about an
1983 * auxiliary RRset, but not anything we asked
1984 * for. In this case we aren't interested,
1985 * because we don't want to request additional
1986 * RRs for stuff we didn't really ask for, and
1987 * also to avoid request loops, where
1988 * additional RRs from one transaction result
1989 * in another transaction whose additonal RRs
1990 * point back to the original transaction, and
1992 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
1998 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
2002 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
2003 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
2004 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
2010 case DNS_TYPE_DNSKEY
: {
2011 /* For each DNSKEY we request the matching DS */
2012 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2014 /* If the DNSKEY we are looking at is not for
2015 * zone we are interested in, nor any of its
2016 * parents, we aren't interested, and don't
2017 * request it. After all, we don't want to end
2018 * up in request loops, and want to keep
2019 * additional traffic down. */
2021 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
2027 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2031 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
2032 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
2033 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2042 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2044 /* For an unsigned SOA or NS, try to acquire
2045 * the matching DS RR, as we are at a zone cut
2046 * then, and whether a DS exists tells us
2047 * whether the zone is signed. Do so only if
2048 * this RR matches our original question,
2051 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
2055 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2056 * a negative reply, and we need the a SOA RR's TTL in order to cache a negative entry?
2057 * If so, we need to validate it, too. */
2059 r
= dns_answer_match_key(t
->answer
, t
->key
, NULL
);
2062 if (r
> 0) /* positive reply, we won't need the SOA and hence don't need to validate
2067 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2073 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2077 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
2078 t
->id
, dns_resource_key_name(rr
->key
));
2079 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2087 case DNS_TYPE_CNAME
:
2088 case DNS_TYPE_DNAME
: {
2089 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2092 /* CNAMEs and DNAMEs cannot be located at a
2093 * zone apex, hence ask for the parent SOA for
2094 * unsigned CNAME/DNAME RRs, maybe that's the
2095 * apex. But do all that only if this is
2096 * actually a response to our original
2099 * Similar for DS RRs, which are signed when
2100 * the parent SOA is signed. */
2102 r
= dns_transaction_is_primary_response(t
, rr
);
2108 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2114 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2120 name
= dns_resource_key_name(rr
->key
);
2121 r
= dns_name_parent(&name
);
2127 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
2131 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
2132 t
->id
, dns_resource_key_name(rr
->key
));
2133 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2141 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2143 /* For other unsigned RRsets (including
2144 * NSEC/NSEC3!), look for proof the zone is
2145 * unsigned, by requesting the SOA RR of the
2146 * zone. However, do so only if they are
2147 * directly relevant to our original
2150 r
= dns_transaction_is_primary_response(t
, rr
);
2156 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2162 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2166 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2167 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2168 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2175 /* Above, we requested everything necessary to validate what
2176 * we got. Now, let's request what we need to validate what we
2179 r
= dns_transaction_has_unsigned_negative_answer(t
);
2186 name
= dns_resource_key_name(t
->key
);
2188 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2189 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2190 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2191 * though they have further children. If this was a DS request, then it's signed when the parent zone
2192 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2193 * to see if that is signed. */
2195 if (t
->key
->type
== DNS_TYPE_DS
) {
2196 r
= dns_name_parent(&name
);
2198 type
= DNS_TYPE_SOA
;
2199 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2200 t
->id
, dns_resource_key_name(t
->key
));
2204 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2207 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2208 t
->id
, dns_resource_key_name(t
->key
));
2211 type
= DNS_TYPE_SOA
;
2212 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2213 t
->id
, dns_resource_key_name(t
->key
));
2217 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2219 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2223 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2229 return dns_transaction_dnssec_is_live(t
);
2232 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2236 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2237 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2238 the state is VALIDATING however, we should check if we are complete now. */
2240 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2241 dns_transaction_process_dnssec(t
);
2244 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2245 DnsResourceRecord
*rr
;
2250 /* Add all DNSKEY RRs from the answer that are validated by DS
2251 * RRs from the list of validated keys to the list of
2252 * validated keys. */
2254 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2256 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2262 /* If so, the DNSKEY is validated too. */
2263 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2271 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2277 /* Checks if the RR we are looking for must be signed with an
2278 * RRSIG. This is used for positive responses. */
2280 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2283 if (dns_type_is_pseudo(rr
->key
->type
))
2286 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2292 switch (rr
->key
->type
) {
2294 case DNS_TYPE_RRSIG
:
2295 /* RRSIGs are the signatures themselves, they need no signing. */
2303 /* For SOA or NS RRs we look for a matching DS transaction */
2305 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2307 if (dt
->key
->class != rr
->key
->class)
2309 if (dt
->key
->type
!= DNS_TYPE_DS
)
2312 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2318 /* We found a DS transactions for the SOA/NS
2319 * RRs we are looking at. If it discovered signed DS
2320 * RRs, then we need to be signed, too. */
2322 if (!dt
->answer_authenticated
)
2325 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2328 /* We found nothing that proves this is safe to leave
2329 * this unauthenticated, hence ask inist on
2330 * authentication. */
2335 case DNS_TYPE_CNAME
:
2336 case DNS_TYPE_DNAME
: {
2337 const char *parent
= NULL
;
2342 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2344 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2347 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2349 if (dt
->key
->class != rr
->key
->class)
2351 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2355 parent
= dns_resource_key_name(rr
->key
);
2356 r
= dns_name_parent(&parent
);
2360 if (rr
->key
->type
== DNS_TYPE_DS
)
2363 /* A CNAME/DNAME without a parent? That's sooo weird. */
2364 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2369 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2375 return t
->answer_authenticated
;
2385 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2387 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2389 if (dt
->key
->class != rr
->key
->class)
2391 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2394 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2400 /* We found the transaction that was supposed to find
2401 * the SOA RR for us. It was successful, but found no
2402 * RR for us. This means we are not at a zone cut. In
2403 * this case, we require authentication if the SOA
2404 * lookup was authenticated too. */
2405 return t
->answer_authenticated
;
2412 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2418 /* If DNSSEC downgrade mode is on, checks whether the
2419 * specified RR is one level below a TLD we have proven not to
2420 * exist. In such a case we assume that this is a private
2421 * domain, and permit it.
2423 * This detects cases like the Fritz!Box router networks. Each
2424 * Fritz!Box router serves a private "fritz.box" zone, in the
2425 * non-existing TLD "box". Requests for the "fritz.box" domain
2426 * are served by the router itself, while requests for the
2427 * "box" domain will result in NXDOMAIN.
2429 * Note that this logic is unable to detect cases where a
2430 * router serves a private DNS zone directly under
2431 * non-existing TLD. In such a case we cannot detect whether
2432 * the TLD is supposed to exist or not, as all requests we
2433 * make for it will be answered by the router's zone, and not
2434 * by the root zone. */
2438 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2439 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2441 tld
= dns_resource_key_name(key
);
2442 r
= dns_name_parent(&tld
);
2446 return false; /* Already the root domain */
2448 if (!dns_name_is_single_label(tld
))
2451 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2453 if (dt
->key
->class != key
->class)
2456 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2462 /* We found an auxiliary lookup we did for the TLD. If
2463 * that returned with NXDOMAIN, we know the TLD didn't
2464 * exist, and hence this might be a private zone. */
2466 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2472 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2473 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2482 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2483 * this negative reply */
2485 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2488 if (dns_type_is_pseudo(t
->key
->type
))
2491 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2497 r
= dns_transaction_in_private_tld(t
, t
->key
);
2501 /* The lookup is from a TLD that is proven not to
2502 * exist, and we are in downgrade mode, hence ignore
2503 * that fact that we didn't get any NSEC RRs. */
2505 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2506 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2510 name
= dns_resource_key_name(t
->key
);
2512 if (t
->key
->type
== DNS_TYPE_DS
) {
2514 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2515 * hence check the parent SOA in this case. */
2517 r
= dns_name_parent(&name
);
2523 type
= DNS_TYPE_SOA
;
2525 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2526 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2529 /* For all other negative replies, check for the SOA lookup */
2530 type
= DNS_TYPE_SOA
;
2532 /* For all other RRs we check the SOA on the same level to see
2533 * if it's signed. */
2535 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2537 if (dt
->key
->class != t
->key
->class)
2539 if (dt
->key
->type
!= type
)
2542 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2548 return dt
->answer_authenticated
;
2551 /* If in doubt, require NSEC/NSEC3 */
2555 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2556 DnsResourceRecord
*rrsig
;
2560 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2561 * the specified RRset is authenticated (i.e. has a matching
2564 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2570 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2574 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2580 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2582 if (dt
->key
->class != rr
->key
->class)
2585 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2587 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2593 /* OK, we found an auxiliary DNSKEY
2594 * lookup. If that lookup is
2595 * authenticated, report this. */
2597 if (dt
->answer_authenticated
)
2602 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2604 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2610 /* OK, we found an auxiliary DS
2611 * lookup. If that lookup is
2612 * authenticated and non-zero, we
2615 if (!dt
->answer_authenticated
)
2618 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2623 return found
? false : -ENXIO
;
2626 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2630 /* We know that the root domain is signed, hence if it appears
2631 * not to be signed, there's a problem with the DNS server */
2633 return rr
->key
->class == DNS_CLASS_IN
&&
2634 dns_name_is_root(dns_resource_key_name(rr
->key
));
2637 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2638 DnsResourceRecord
*rr
;
2643 /* Maybe warn the user that we encountered a revoked DNSKEY
2644 * for a key from our trust anchor. Note that we don't care
2645 * whether the DNSKEY can be authenticated or not. It's
2646 * sufficient if it is self-signed. */
2648 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2649 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2657 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2663 /* Removes all DNSKEY/DS objects from t->validated_keys that
2664 * our trust anchors database considers revoked. */
2667 DnsResourceRecord
*rr
;
2671 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2672 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2676 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2690 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2697 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2699 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2701 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2704 if (!dt
->answer_authenticated
)
2707 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2716 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2717 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2718 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2721 static int dnssec_validate_records(
2725 DnsAnswer
**validated
) {
2727 DnsResourceRecord
*rr
;
2730 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2732 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2733 DnsResourceRecord
*rrsig
= NULL
;
2734 DnssecResult result
;
2736 switch (rr
->key
->type
) {
2737 case DNS_TYPE_RRSIG
:
2740 case DNS_TYPE_DNSKEY
:
2741 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2742 if (phase
== DNSSEC_PHASE_NSEC
)
2747 case DNS_TYPE_NSEC3
:
2750 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2751 if (phase
== DNSSEC_PHASE_DNSKEY
)
2756 /* We validate all other RRs only in the ALL phases */
2757 if (phase
!= DNSSEC_PHASE_ALL
)
2761 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2765 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2767 if (result
== DNSSEC_VALIDATED
) {
2769 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2770 /* If we just validated a DNSKEY RRset, then let's add these keys to
2771 * the set of validated keys for this transaction. */
2773 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2777 /* Some of the DNSKEYs we just added might already have been revoked,
2778 * remove them again in that case. */
2779 r
= dns_transaction_invalidate_revoked_keys(t
);
2784 /* Add the validated RRset to the new list of validated
2785 * RRsets, and remove it from the unvalidated RRsets.
2786 * We mark the RRset as authenticated and cacheable. */
2787 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2791 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2793 /* Exit the loop, we dropped something from the answer, start from the beginning */
2797 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2798 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2799 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2800 if (phase
!= DNSSEC_PHASE_ALL
)
2803 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2804 bool authenticated
= false;
2807 /* This RRset validated, but as a wildcard. This means we need
2808 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
2810 /* First step, determine the source of synthesis */
2811 r
= dns_resource_record_source(rrsig
, &source
);
2815 r
= dnssec_test_positive_wildcard(*validated
,
2816 dns_resource_key_name(rr
->key
),
2818 rrsig
->rrsig
.signer
,
2821 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2823 result
= DNSSEC_INVALID
;
2825 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2826 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2830 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2832 /* Exit the loop, we dropped something from the answer, start from the beginning */
2837 if (result
== DNSSEC_NO_SIGNATURE
) {
2838 r
= dns_transaction_requires_rrsig(t
, rr
);
2842 /* Data does not require signing. In that case, just copy it over,
2843 * but remember that this is by no means authenticated. */
2844 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2848 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2852 r
= dns_transaction_known_signed(t
, rr
);
2856 /* This is an RR we know has to be signed. If it isn't this means
2857 * the server is not attaching RRSIGs, hence complain. */
2859 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2861 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2863 /* Downgrading is OK? If so, just consider the information unsigned */
2865 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2869 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2873 /* Otherwise, fail */
2874 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2878 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2882 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2884 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2885 * mode, hence ignore the fact that this was not signed. */
2887 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2888 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2890 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2894 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2901 DNSSEC_SIGNATURE_EXPIRED
,
2902 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2904 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2905 if (r
< 0 && r
!= -ENXIO
)
2908 /* The DNSKEY transaction was not authenticated, this means there's
2909 * no DS for this, which means it's OK if no keys are found for this signature. */
2911 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2915 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2920 r
= dns_transaction_is_primary_response(t
, rr
);
2924 /* Look for a matching DNAME for this CNAME */
2925 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2929 /* Also look among the stuff we already validated */
2930 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2938 DNSSEC_SIGNATURE_EXPIRED
,
2939 DNSSEC_NO_SIGNATURE
))
2940 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2941 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2942 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2944 /* This is a primary response to our question, and it failed validation.
2946 t
->answer_dnssec_result
= result
;
2950 /* This is a primary response, but we do have a DNAME RR
2951 * in the RR that can replay this CNAME, hence rely on
2952 * that, and we can remove the CNAME in favour of it. */
2955 /* This is just some auxiliary data. Just remove the RRset and continue. */
2956 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2960 /* We dropped something from the answer, start from the beginning. */
2964 return 2; /* Finito. */
2967 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2968 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2970 DnsAnswerFlags flags
;
2972 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2976 /* We have now collected all DS and DNSKEY RRs in
2977 * t->validated_keys, let's see which RRs we can now
2978 * authenticate with that. */
2980 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2983 /* Already validated */
2984 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2987 /* Our own stuff needs no validation */
2988 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2989 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2990 t
->answer_authenticated
= true;
2994 /* Cached stuff is not affected by validation. */
2995 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
2998 if (!dns_transaction_dnssec_supported_full(t
)) {
2999 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3000 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
3001 log_debug("Not validating response for %" PRIu16
", used server feature level does not support DNSSEC.", t
->id
);
3005 log_debug("Validating response from transaction %" PRIu16
" (%s).",
3007 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
3009 /* First, see if this response contains any revoked trust
3010 * anchors we care about */
3011 r
= dns_transaction_check_revoked_trust_anchors(t
);
3015 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3016 r
= dns_transaction_copy_validated(t
);
3020 /* Second, see if there are DNSKEYs we already know a
3021 * validated DS for. */
3022 r
= dns_transaction_validate_dnskey_by_ds(t
);
3026 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3027 * anchor says are revoked. After all we might have marked
3028 * some keys revoked above, but they might still be lingering
3029 * in our validated_keys list. */
3030 r
= dns_transaction_invalidate_revoked_keys(t
);
3034 phase
= DNSSEC_PHASE_DNSKEY
;
3036 bool have_nsec
= false;
3038 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
3042 /* Try again as long as we managed to achieve something */
3046 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
3047 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3048 phase
= DNSSEC_PHASE_NSEC
;
3052 if (phase
!= DNSSEC_PHASE_ALL
) {
3053 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3054 * Note that in this third phase we start to remove RRs we couldn't validate. */
3055 phase
= DNSSEC_PHASE_ALL
;
3063 dns_answer_unref(t
->answer
);
3064 t
->answer
= TAKE_PTR(validated
);
3066 /* At this point the answer only contains validated
3067 * RRsets. Now, let's see if it actually answers the question
3068 * we asked. If so, great! If it doesn't, then see if
3069 * NSEC/NSEC3 can prove this. */
3070 r
= dns_transaction_has_positive_answer(t
, &flags
);
3072 /* Yes, it answers the question! */
3074 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
3075 /* The answer is fully authenticated, yay. */
3076 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3077 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3078 t
->answer_authenticated
= true;
3080 /* The answer is not fully authenticated. */
3081 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3082 t
->answer_authenticated
= false;
3085 } else if (r
== 0) {
3086 DnssecNsecResult nr
;
3087 bool authenticated
= false;
3089 /* Bummer! Let's check NSEC/NSEC3 */
3090 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
3096 case DNSSEC_NSEC_NXDOMAIN
:
3097 /* NSEC proves the domain doesn't exist. Very good. */
3098 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3099 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3100 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
3101 t
->answer_authenticated
= authenticated
;
3103 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3106 case DNSSEC_NSEC_NODATA
:
3107 /* NSEC proves that there's no data here, very good. */
3108 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3109 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3110 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3111 t
->answer_authenticated
= authenticated
;
3113 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3116 case DNSSEC_NSEC_OPTOUT
:
3117 /* NSEC3 says the data might not be signed */
3118 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3119 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3120 t
->answer_authenticated
= false;
3122 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3125 case DNSSEC_NSEC_NO_RR
:
3126 /* No NSEC data? Bummer! */
3128 r
= dns_transaction_requires_nsec(t
);
3132 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
3133 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3135 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3136 t
->answer_authenticated
= false;
3137 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3142 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3143 /* We don't know the NSEC3 algorithm used? */
3144 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3145 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3148 case DNSSEC_NSEC_FOUND
:
3149 case DNSSEC_NSEC_CNAME
:
3150 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3151 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3152 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3156 assert_not_reached("Unexpected NSEC result.");
3163 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3164 [DNS_TRANSACTION_NULL
] = "null",
3165 [DNS_TRANSACTION_PENDING
] = "pending",
3166 [DNS_TRANSACTION_VALIDATING
] = "validating",
3167 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3168 [DNS_TRANSACTION_SUCCESS
] = "success",
3169 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3170 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3171 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3172 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3173 [DNS_TRANSACTION_ERRNO
] = "errno",
3174 [DNS_TRANSACTION_ABORTED
] = "aborted",
3175 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3176 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3177 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3178 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3179 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3181 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3183 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3184 [DNS_TRANSACTION_NETWORK
] = "network",
3185 [DNS_TRANSACTION_CACHE
] = "cache",
3186 [DNS_TRANSACTION_ZONE
] = "zone",
3187 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3189 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);