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
),
320 /* Note that this call might invalidate the query. Callers
321 * should hence not attempt to access the query or transaction
322 * after calling this function. */
324 if (state
== DNS_TRANSACTION_ERRNO
)
325 st
= errno_to_name(t
->answer_errno
);
327 st
= dns_transaction_state_to_string(state
);
329 log_debug("Transaction %" PRIu16
" for <%s> on scope %s on %s/%s now complete with <%s> from %s (%s).",
331 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
332 dns_protocol_to_string(t
->scope
->protocol
),
333 t
->scope
->link
? t
->scope
->link
->name
: "*",
334 af_to_name_short(t
->scope
->family
),
336 t
->answer_source
< 0 ? "none" : dns_transaction_source_to_string(t
->answer_source
),
337 t
->answer_authenticated
? "authenticated" : "unsigned");
341 dns_transaction_close_connection(t
);
342 dns_transaction_stop_timeout(t
);
344 /* Notify all queries that are interested, but make sure the
345 * transaction isn't freed while we are still looking at it */
348 SET_FOREACH_MOVE(c
, t
->notify_query_candidates_done
, t
->notify_query_candidates
)
349 dns_query_candidate_notify(c
);
350 SWAP_TWO(t
->notify_query_candidates
, t
->notify_query_candidates_done
);
352 SET_FOREACH_MOVE(z
, t
->notify_zone_items_done
, t
->notify_zone_items
)
353 dns_zone_item_notify(z
);
354 SWAP_TWO(t
->notify_zone_items
, t
->notify_zone_items_done
);
355 if (t
->probing
&& t
->state
== DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
)
356 (void) dns_scope_announce(t
->scope
, false);
358 SET_FOREACH_MOVE(d
, t
->notify_transactions_done
, t
->notify_transactions
)
359 dns_transaction_notify(d
, t
);
360 SWAP_TWO(t
->notify_transactions
, t
->notify_transactions_done
);
363 dns_transaction_gc(t
);
366 static int dns_transaction_pick_server(DnsTransaction
*t
) {
370 assert(t
->scope
->protocol
== DNS_PROTOCOL_DNS
);
372 /* Pick a DNS server and a feature level for it. */
374 server
= dns_scope_get_dns_server(t
->scope
);
378 /* If we changed the server invalidate the feature level clamping, as the new server might have completely
379 * different properties. */
380 if (server
!= t
->server
)
381 t
->clamp_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
383 t
->current_feature_level
= dns_server_possible_feature_level(server
);
385 /* Clamp the feature level if that is requested. */
386 if (t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
&&
387 t
->current_feature_level
> t
->clamp_feature_level
)
388 t
->current_feature_level
= t
->clamp_feature_level
;
390 log_debug("Using feature level %s for transaction %u.", dns_server_feature_level_to_string(t
->current_feature_level
), t
->id
);
392 if (server
== t
->server
)
395 dns_server_unref(t
->server
);
396 t
->server
= dns_server_ref(server
);
398 t
->n_picked_servers
++;
400 log_debug("Using DNS server %s for transaction %u.", dns_server_string(t
->server
), t
->id
);
405 static void dns_transaction_retry(DnsTransaction
*t
, bool next_server
) {
410 log_debug("Retrying transaction %" PRIu16
".", t
->id
);
412 /* Before we try again, switch to a new server. */
414 dns_scope_next_dns_server(t
->scope
);
416 r
= dns_transaction_go(t
);
418 t
->answer_errno
= -r
;
419 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
423 static int dns_transaction_maybe_restart(DnsTransaction
*t
) {
428 /* Returns > 0 if the transaction was restarted, 0 if not */
433 if (t
->current_feature_level
<= dns_server_possible_feature_level(t
->server
))
436 /* The server's current feature level is lower than when we sent the original query. We learnt something from
437 the response or possibly an auxiliary DNSSEC response that we didn't know before. We take that as reason to
438 restart the whole transaction. This is a good idea to deal with servers that respond rubbish if we include
439 OPT RR or DO bit. One of these cases is documented here, for example:
440 https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
442 log_debug("Server feature level is now lower than when we began our transaction. Restarting with new ID.");
443 dns_transaction_shuffle_id(t
);
445 r
= dns_transaction_go(t
);
452 static int on_stream_complete(DnsStream
*s
, int error
) {
453 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
457 assert(s
->transaction
);
459 /* Copy the data we care about out of the stream before we
462 p
= dns_packet_ref(s
->read_packet
);
464 dns_transaction_close_connection(t
);
466 if (ERRNO_IS_DISCONNECT(error
)) {
469 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
) {
470 /* If the LLMNR/TCP connection failed, the host doesn't support LLMNR, and we cannot answer the
471 * question on this scope. */
472 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
476 log_debug_errno(error
, "Connection failure for DNS TCP stream: %m");
477 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
478 dns_server_packet_lost(t
->server
, IPPROTO_TCP
, t
->current_feature_level
, usec
- t
->start_usec
);
480 dns_transaction_retry(t
, true);
484 t
->answer_errno
= error
;
485 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
489 if (dns_packet_validate_reply(p
) <= 0) {
490 log_debug("Invalid TCP reply packet.");
491 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
495 dns_scope_check_conflicts(t
->scope
, p
);
498 dns_transaction_process_reply(t
, p
);
501 /* If the response wasn't useful, then complete the transition
502 * now. After all, we are the worst feature set now with TCP
503 * sockets, and there's really no point in retrying. */
504 if (t
->state
== DNS_TRANSACTION_PENDING
)
505 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
507 dns_transaction_gc(t
);
512 static int dns_transaction_open_tcp(DnsTransaction
*t
) {
513 _cleanup_close_
int fd
= -1;
518 dns_transaction_close_connection(t
);
520 switch (t
->scope
->protocol
) {
522 case DNS_PROTOCOL_DNS
:
523 r
= dns_transaction_pick_server(t
);
527 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
530 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
534 fd
= dns_scope_socket_tcp(t
->scope
, AF_UNSPEC
, NULL
, t
->server
, 53);
537 case DNS_PROTOCOL_LLMNR
:
538 /* When we already received a reply to this (but it was truncated), send to its sender address */
540 fd
= dns_scope_socket_tcp(t
->scope
, t
->received
->family
, &t
->received
->sender
, NULL
, t
->received
->sender_port
);
542 union in_addr_union address
;
543 int family
= AF_UNSPEC
;
545 /* Otherwise, try to talk to the owner of a
546 * the IP address, in case this is a reverse
549 r
= dns_name_address(dns_resource_key_name(t
->key
), &family
, &address
);
554 if (family
!= t
->scope
->family
)
557 fd
= dns_scope_socket_tcp(t
->scope
, family
, &address
, NULL
, LLMNR_PORT
);
563 return -EAFNOSUPPORT
;
569 r
= dns_stream_new(t
->scope
->manager
, &t
->stream
, t
->scope
->protocol
, fd
);
574 r
= dns_stream_write_packet(t
->stream
, t
->sent
);
576 t
->stream
= dns_stream_unref(t
->stream
);
580 t
->stream
->complete
= on_stream_complete
;
581 t
->stream
->transaction
= t
;
583 /* The interface index is difficult to determine if we are
584 * connecting to the local host, hence fill this in right away
585 * instead of determining it from the socket */
586 t
->stream
->ifindex
= dns_scope_ifindex(t
->scope
);
588 dns_transaction_reset_answer(t
);
590 t
->tried_stream
= true;
595 static void dns_transaction_cache_answer(DnsTransaction
*t
) {
598 /* For mDNS we cache whenever we get the packet, rather than
599 * in each transaction. */
600 if (!IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
))
603 /* Caching disabled? */
604 if (!t
->scope
->manager
->enable_cache
)
607 /* We never cache if this packet is from the local host, under
608 * the assumption that a locally running DNS server would
609 * cache this anyway, and probably knows better when to flush
610 * the cache then we could. */
611 if (!DNS_PACKET_SHALL_CACHE(t
->received
))
614 dns_cache_put(&t
->scope
->cache
,
618 t
->answer_authenticated
,
622 &t
->received
->sender
);
625 static bool dns_transaction_dnssec_is_live(DnsTransaction
*t
) {
631 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
632 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
638 static int dns_transaction_dnssec_ready(DnsTransaction
*t
) {
644 /* Checks whether the auxiliary DNSSEC transactions of our transaction have completed, or are still
645 * ongoing. Returns 0, if we aren't ready for the DNSSEC validation, positive if we are. */
647 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
651 case DNS_TRANSACTION_NULL
:
652 case DNS_TRANSACTION_PENDING
:
653 case DNS_TRANSACTION_VALIDATING
:
657 case DNS_TRANSACTION_RCODE_FAILURE
:
658 if (!IN_SET(dt
->answer_rcode
, DNS_RCODE_NXDOMAIN
, DNS_RCODE_SERVFAIL
)) {
659 log_debug("Auxiliary DNSSEC RR query failed with rcode=%s.", dns_rcode_to_string(dt
->answer_rcode
));
663 /* Fall-through: NXDOMAIN/SERVFAIL is good enough for us. This is because some DNS servers
664 * erronously return NXDOMAIN/SERVFAIL for empty non-terminals (Akamai...) or missing DS
665 * records (Facebook), and we need to handle that nicely, when asking for parent SOA or similar
666 * RRs to make unsigned proofs. */
668 case DNS_TRANSACTION_SUCCESS
:
672 case DNS_TRANSACTION_DNSSEC_FAILED
:
673 /* We handle DNSSEC failures different from other errors, as we care about the DNSSEC
674 * validationr result */
676 log_debug("Auxiliary DNSSEC RR query failed validation: %s", dnssec_result_to_string(dt
->answer_dnssec_result
));
677 t
->answer_dnssec_result
= dt
->answer_dnssec_result
; /* Copy error code over */
678 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
683 log_debug("Auxiliary DNSSEC RR query failed with %s", dns_transaction_state_to_string(dt
->state
));
688 /* All is ready, we can go and validate */
692 t
->answer_dnssec_result
= DNSSEC_FAILED_AUXILIARY
;
693 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
697 static void dns_transaction_process_dnssec(DnsTransaction
*t
) {
702 /* Are there ongoing DNSSEC transactions? If so, let's wait for them. */
703 r
= dns_transaction_dnssec_ready(t
);
706 if (r
== 0) /* We aren't ready yet (or one of our auxiliary transactions failed, and we shouldn't validate now */
709 /* See if we learnt things from the additional DNSSEC transactions, that we didn't know before, and better
710 * restart the lookup immediately. */
711 r
= dns_transaction_maybe_restart(t
);
714 if (r
> 0) /* Transaction got restarted... */
717 /* All our auxiliary DNSSEC transactions are complete now. Try
718 * to validate our RRset now. */
719 r
= dns_transaction_validate_dnssec(t
);
721 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
727 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
&&
728 t
->scope
->dnssec_mode
== DNSSEC_YES
) {
730 /* We are not in automatic downgrade mode, and the server is bad. Let's try a different server, maybe
733 if (t
->n_picked_servers
< dns_scope_get_n_dns_servers(t
->scope
)) {
734 /* We tried fewer servers on this transaction than we know, let's try another one then */
735 dns_transaction_retry(t
, true);
739 /* OK, let's give up, apparently all servers we tried didn't work. */
740 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
744 if (!IN_SET(t
->answer_dnssec_result
,
745 _DNSSEC_RESULT_INVALID
, /* No DNSSEC validation enabled */
746 DNSSEC_VALIDATED
, /* Answer is signed and validated successfully */
747 DNSSEC_UNSIGNED
, /* Answer is right-fully unsigned */
748 DNSSEC_INCOMPATIBLE_SERVER
)) { /* Server does not do DNSSEC (Yay, we are downgrade attack vulnerable!) */
749 dns_transaction_complete(t
, DNS_TRANSACTION_DNSSEC_FAILED
);
753 if (t
->answer_dnssec_result
== DNSSEC_INCOMPATIBLE_SERVER
)
754 dns_server_warn_downgrade(t
->server
);
756 dns_transaction_cache_answer(t
);
758 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
759 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
761 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
766 t
->answer_errno
= -r
;
767 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
770 static int dns_transaction_has_positive_answer(DnsTransaction
*t
, DnsAnswerFlags
*flags
) {
775 /* Checks whether the answer is positive, i.e. either a direct
776 * answer to the question, or a CNAME/DNAME for it */
778 r
= dns_answer_match_key(t
->answer
, t
->key
, flags
);
782 r
= dns_answer_find_cname_or_dname(t
->answer
, t
->key
, NULL
, flags
);
789 static int dns_transaction_fix_rcode(DnsTransaction
*t
) {
794 /* Fix up the RCODE to SUCCESS if we get at least one matching RR in a response. Note that this contradicts the
795 * DNS RFCs a bit. Specifically, RFC 6604 Section 3 clarifies that the RCODE shall say something about a
796 * CNAME/DNAME chain element coming after the last chain element contained in the message, and not the first
797 * one included. However, it also indicates that not all DNS servers implement this correctly. Moreover, when
798 * using DNSSEC we usually only can prove the first element of a CNAME/DNAME chain anyway, hence let's settle
799 * on always processing the RCODE as referring to the immediate look-up we do, i.e. the first element of a
800 * CNAME/DNAME chain. This way, we uniformly handle CNAME/DNAME chains, regardless if the DNS server
801 * incorrectly implements RCODE, whether DNSSEC is in use, or whether the DNS server only supplied us with an
802 * incomplete CNAME/DNAME chain.
804 * Or in other words: if we get at least one positive reply in a message we patch NXDOMAIN to become SUCCESS,
805 * and then rely on the CNAME chasing logic to figure out that there's actually a CNAME error with a new
808 if (t
->answer_rcode
!= DNS_RCODE_NXDOMAIN
)
811 r
= dns_transaction_has_positive_answer(t
, NULL
);
815 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
819 void dns_transaction_process_reply(DnsTransaction
*t
, DnsPacket
*p
) {
826 assert(t
->scope
->manager
);
828 if (t
->state
!= DNS_TRANSACTION_PENDING
)
831 /* Note that this call might invalidate the query. Callers
832 * should hence not attempt to access the query or transaction
833 * after calling this function. */
835 log_debug("Processing incoming packet on transaction %" PRIu16
". (rcode=%s)", t
->id
, dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
837 switch (t
->scope
->protocol
) {
839 case DNS_PROTOCOL_LLMNR
:
840 /* For LLMNR we will not accept any packets from other interfaces */
842 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
845 if (p
->family
!= t
->scope
->family
)
848 /* Tentative packets are not full responses but still
849 * useful for identifying uniqueness conflicts during
851 if (DNS_PACKET_LLMNR_T(p
)) {
852 dns_transaction_tentative(t
, p
);
858 case DNS_PROTOCOL_MDNS
:
859 /* For mDNS we will not accept any packets from other interfaces */
861 if (p
->ifindex
!= dns_scope_ifindex(t
->scope
))
864 if (p
->family
!= t
->scope
->family
)
869 case DNS_PROTOCOL_DNS
:
870 /* Note that we do not need to verify the
871 * addresses/port numbers of incoming traffic, as we
872 * invoked connect() on our UDP socket in which case
873 * the kernel already does the needed verification for
878 assert_not_reached("Invalid DNS protocol.");
881 if (t
->received
!= p
) {
882 dns_packet_unref(t
->received
);
883 t
->received
= dns_packet_ref(p
);
886 t
->answer_source
= DNS_TRANSACTION_NETWORK
;
888 if (p
->ipproto
== IPPROTO_TCP
) {
889 if (DNS_PACKET_TC(p
)) {
890 /* Truncated via TCP? Somebody must be fucking with us */
891 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
895 if (DNS_PACKET_ID(p
) != t
->id
) {
896 /* Not the reply to our query? Somebody must be fucking with us */
897 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
902 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
904 switch (t
->scope
->protocol
) {
906 case DNS_PROTOCOL_DNS
:
909 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_FORMERR
, DNS_RCODE_SERVFAIL
, DNS_RCODE_NOTIMP
)) {
911 /* Request failed, immediately try again with reduced features */
913 if (t
->current_feature_level
<= DNS_SERVER_FEATURE_LEVEL_UDP
) {
915 /* This was already at UDP feature level? If so, it doesn't make sense to downgrade
916 * this transaction anymore, but let's see if it might make sense to send the request
917 * to a different DNS server instead. If not let's process the response, and accept the
918 * rcode. Note that we don't retry on TCP, since that's a suitable way to mitigate
919 * packet loss, but is not going to give us better rcodes should we actually have
920 * managed to get them already at UDP level. */
922 if (t
->n_picked_servers
< dns_scope_get_n_dns_servers(t
->scope
)) {
923 /* We tried fewer servers on this transaction than we know, let's try another one then */
924 dns_transaction_retry(t
, true);
928 /* Give up, accept the rcode */
929 log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p
)));
933 /* Reduce this feature level by one and try again. */
934 t
->clamp_feature_level
= t
->current_feature_level
- 1;
936 log_debug("Server returned error %s, retrying transaction with reduced feature level %s.",
937 dns_rcode_to_string(DNS_PACKET_RCODE(p
)),
938 dns_server_feature_level_to_string(t
->clamp_feature_level
));
940 dns_transaction_retry(t
, false /* use the same server */);
944 if (DNS_PACKET_RCODE(p
) == DNS_RCODE_REFUSED
) {
945 /* This server refused our request? If so, try again, use a different server */
946 log_debug("Server returned REFUSED, switching servers, and retrying.");
947 dns_transaction_retry(t
, true /* pick a new server */);
951 if (DNS_PACKET_TC(p
))
952 dns_server_packet_truncated(t
->server
, t
->current_feature_level
);
956 case DNS_PROTOCOL_LLMNR
:
957 case DNS_PROTOCOL_MDNS
:
958 dns_scope_packet_received(t
->scope
, ts
- t
->start_usec
);
962 assert_not_reached("Invalid DNS protocol.");
965 if (DNS_PACKET_TC(p
)) {
967 /* Truncated packets for mDNS are not allowed. Give up immediately. */
968 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
) {
969 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
973 log_debug("Reply truncated, retrying via TCP.");
975 /* Response was truncated, let's try again with good old TCP */
976 r
= dns_transaction_open_tcp(t
);
978 /* No servers found? Damn! */
979 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
982 if (r
== -EOPNOTSUPP
) {
983 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
984 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
988 /* On LLMNR, if we cannot connect to the host,
989 * we immediately give up */
990 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
993 /* On DNS, couldn't send? Try immediately again, with a new server */
994 dns_transaction_retry(t
, true);
1000 /* After the superficial checks, actually parse the message. */
1001 r
= dns_packet_extract(p
);
1003 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1008 /* Report that we successfully received a valid packet with a good rcode after we initially got a bad
1009 * rcode and subsequently downgraded the protocol */
1011 if (IN_SET(DNS_PACKET_RCODE(p
), DNS_RCODE_SUCCESS
, DNS_RCODE_NXDOMAIN
) &&
1012 t
->clamp_feature_level
!= _DNS_SERVER_FEATURE_LEVEL_INVALID
)
1013 dns_server_packet_rcode_downgrade(t
->server
, t
->clamp_feature_level
);
1015 /* Report that the OPT RR was missing */
1017 dns_server_packet_bad_opt(t
->server
, t
->current_feature_level
);
1019 /* Report that we successfully received a packet */
1020 dns_server_packet_received(t
->server
, p
->ipproto
, t
->current_feature_level
, ts
- t
->start_usec
, p
->size
);
1023 /* See if we know things we didn't know before that indicate we better restart the lookup immediately. */
1024 r
= dns_transaction_maybe_restart(t
);
1027 if (r
> 0) /* Transaction got restarted... */
1030 if (IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_DNS
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1032 /* When dealing with protocols other than mDNS only consider responses with
1033 * equivalent query section to the request. For mDNS this check doesn't make
1034 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
1035 * contain any questions in the Question Section". */
1036 if (t
->scope
->protocol
!= DNS_PROTOCOL_MDNS
) {
1037 r
= dns_packet_is_reply_for(p
, t
->key
);
1041 dns_transaction_complete(t
, DNS_TRANSACTION_INVALID_REPLY
);
1046 /* Install the answer as answer to the transaction */
1047 dns_answer_unref(t
->answer
);
1048 t
->answer
= dns_answer_ref(p
->answer
);
1049 t
->answer_rcode
= DNS_PACKET_RCODE(p
);
1050 t
->answer_dnssec_result
= _DNSSEC_RESULT_INVALID
;
1051 t
->answer_authenticated
= false;
1053 r
= dns_transaction_fix_rcode(t
);
1057 /* Block GC while starting requests for additional DNSSEC RRs */
1059 r
= dns_transaction_request_dnssec_keys(t
);
1062 /* Maybe the transaction is ready for GC'ing now? If so, free it and return. */
1063 if (!dns_transaction_gc(t
))
1066 /* Requesting additional keys might have resulted in
1067 * this transaction to fail, since the auxiliary
1068 * request failed for some reason. If so, we are not
1069 * in pending state anymore, and we should exit
1071 if (t
->state
!= DNS_TRANSACTION_PENDING
)
1076 /* There are DNSSEC transactions pending now. Update the state accordingly. */
1077 t
->state
= DNS_TRANSACTION_VALIDATING
;
1078 dns_transaction_close_connection(t
);
1079 dns_transaction_stop_timeout(t
);
1084 dns_transaction_process_dnssec(t
);
1088 t
->answer_errno
= -r
;
1089 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1092 static int on_dns_packet(sd_event_source
*s
, int fd
, uint32_t revents
, void *userdata
) {
1093 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1094 DnsTransaction
*t
= userdata
;
1100 r
= manager_recv(t
->scope
->manager
, fd
, DNS_PROTOCOL_DNS
, &p
);
1101 if (ERRNO_IS_DISCONNECT(-r
)) {
1104 /* UDP connection failure get reported via ICMP and then are possible delivered to us on the next
1105 * recvmsg(). Treat this like a lost packet. */
1107 log_debug_errno(r
, "Connection failure for DNS UDP packet: %m");
1108 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &usec
) >= 0);
1109 dns_server_packet_lost(t
->server
, IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1111 dns_transaction_retry(t
, true);
1115 dns_transaction_complete(t
, DNS_TRANSACTION_ERRNO
);
1116 t
->answer_errno
= -r
;
1120 r
= dns_packet_validate_reply(p
);
1122 log_debug_errno(r
, "Received invalid DNS packet as response, ignoring: %m");
1126 log_debug("Received inappropriate DNS packet as response, ignoring.");
1130 if (DNS_PACKET_ID(p
) != t
->id
) {
1131 log_debug("Received packet with incorrect transaction ID, ignoring.");
1135 dns_transaction_process_reply(t
, p
);
1139 static int dns_transaction_emit_udp(DnsTransaction
*t
) {
1144 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1146 r
= dns_transaction_pick_server(t
);
1150 if (t
->current_feature_level
< DNS_SERVER_FEATURE_LEVEL_UDP
)
1151 return -EAGAIN
; /* Sorry, can't do UDP, try TCP! */
1153 if (!dns_server_dnssec_supported(t
->server
) && dns_type_is_dnssec(t
->key
->type
))
1156 if (r
> 0 || t
->dns_udp_fd
< 0) { /* Server changed, or no connection yet. */
1159 dns_transaction_close_connection(t
);
1161 fd
= dns_scope_socket_udp(t
->scope
, t
->server
, 53);
1165 r
= sd_event_add_io(t
->scope
->manager
->event
, &t
->dns_udp_event_source
, fd
, EPOLLIN
, on_dns_packet
, t
);
1171 (void) sd_event_source_set_description(t
->dns_udp_event_source
, "dns-transaction-udp");
1175 r
= dns_server_adjust_opt(t
->server
, t
->sent
, t
->current_feature_level
);
1179 dns_transaction_close_connection(t
);
1181 r
= dns_scope_emit_udp(t
->scope
, t
->dns_udp_fd
, t
->sent
);
1185 dns_transaction_reset_answer(t
);
1190 static int on_transaction_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1191 DnsTransaction
*t
= userdata
;
1196 if (!t
->initial_jitter_scheduled
|| t
->initial_jitter_elapsed
) {
1197 /* Timeout reached? Increase the timeout for the server used */
1198 switch (t
->scope
->protocol
) {
1200 case DNS_PROTOCOL_DNS
:
1202 dns_server_packet_lost(t
->server
, t
->stream
? IPPROTO_TCP
: IPPROTO_UDP
, t
->current_feature_level
, usec
- t
->start_usec
);
1205 case DNS_PROTOCOL_LLMNR
:
1206 case DNS_PROTOCOL_MDNS
:
1207 dns_scope_packet_lost(t
->scope
, usec
- t
->start_usec
);
1211 assert_not_reached("Invalid DNS protocol.");
1214 if (t
->initial_jitter_scheduled
)
1215 t
->initial_jitter_elapsed
= true;
1218 log_debug("Timeout reached on transaction %" PRIu16
".", t
->id
);
1220 dns_transaction_retry(t
, true);
1224 static usec_t
transaction_get_resend_timeout(DnsTransaction
*t
) {
1229 switch (t
->scope
->protocol
) {
1231 case DNS_PROTOCOL_DNS
:
1233 /* When we do TCP, grant a much longer timeout, as in this case there's no need for us to quickly
1234 * resend, as the kernel does that anyway for us, and we really don't want to interrupt it in that
1237 return TRANSACTION_TCP_TIMEOUT_USEC
;
1240 return t
->server
->resend_timeout
;
1242 case DNS_PROTOCOL_MDNS
:
1243 assert(t
->n_attempts
> 0);
1245 return MDNS_PROBING_INTERVAL_USEC
;
1247 return (1 << (t
->n_attempts
- 1)) * USEC_PER_SEC
;
1249 case DNS_PROTOCOL_LLMNR
:
1250 return t
->scope
->resend_timeout
;
1253 assert_not_reached("Invalid DNS protocol.");
1257 static int dns_transaction_prepare(DnsTransaction
*t
, usec_t ts
) {
1262 dns_transaction_stop_timeout(t
);
1264 r
= dns_scope_network_good(t
->scope
);
1268 dns_transaction_complete(t
, DNS_TRANSACTION_NETWORK_DOWN
);
1272 if (t
->n_attempts
>= TRANSACTION_ATTEMPTS_MAX(t
->scope
->protocol
)) {
1273 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1277 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& t
->tried_stream
) {
1278 /* If we already tried via a stream, then we don't
1279 * retry on LLMNR. See RFC 4795, Section 2.7. */
1280 dns_transaction_complete(t
, DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
);
1287 dns_transaction_reset_answer(t
);
1288 dns_transaction_flush_dnssec_transactions(t
);
1290 /* Check the trust anchor. Do so only on classic DNS, since DNSSEC does not apply otherwise. */
1291 if (t
->scope
->protocol
== DNS_PROTOCOL_DNS
) {
1292 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, t
->key
, &t
->answer
);
1296 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1297 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1298 t
->answer_authenticated
= true;
1299 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1303 if (dns_name_is_root(dns_resource_key_name(t
->key
)) &&
1304 t
->key
->type
== DNS_TYPE_DS
) {
1306 /* Hmm, this is a request for the root DS? A
1307 * DS RR doesn't exist in the root zone, and
1308 * if our trust anchor didn't know it either,
1309 * this means we cannot do any DNSSEC logic
1312 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
1313 /* We are in downgrade mode. In this
1314 * case, synthesize an unsigned empty
1315 * response, so that the any lookup
1316 * depending on this one can continue
1317 * assuming there was no DS, and hence
1318 * the root zone was unsigned. */
1320 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1321 t
->answer_source
= DNS_TRANSACTION_TRUST_ANCHOR
;
1322 t
->answer_authenticated
= false;
1323 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1325 /* If we are not in downgrade mode,
1326 * then fail the lookup, because we
1327 * cannot reasonably answer it. There
1328 * might be DS RRs, but we don't know
1329 * them, and the DNS server won't tell
1330 * them to us (and even if it would,
1331 * we couldn't validate and trust them. */
1332 dns_transaction_complete(t
, DNS_TRANSACTION_NO_TRUST_ANCHOR
);
1338 /* Check the zone, but only if this transaction is not used
1339 * for probing or verifying a zone item. */
1340 if (set_isempty(t
->notify_zone_items
)) {
1342 r
= dns_zone_lookup(&t
->scope
->zone
, t
->key
, dns_scope_ifindex(t
->scope
), &t
->answer
, NULL
, NULL
);
1346 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
1347 t
->answer_source
= DNS_TRANSACTION_ZONE
;
1348 t
->answer_authenticated
= true;
1349 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1354 /* Check the cache, but only if this transaction is not used
1355 * for probing or verifying a zone item. */
1356 if (set_isempty(t
->notify_zone_items
)) {
1358 /* Before trying the cache, let's make sure we figured out a
1359 * server to use. Should this cause a change of server this
1360 * might flush the cache. */
1361 (void) dns_scope_get_dns_server(t
->scope
);
1363 /* Let's then prune all outdated entries */
1364 dns_cache_prune(&t
->scope
->cache
);
1366 r
= dns_cache_lookup(&t
->scope
->cache
, t
->key
, t
->clamp_ttl
, &t
->answer_rcode
, &t
->answer
, &t
->answer_authenticated
);
1370 t
->answer_source
= DNS_TRANSACTION_CACHE
;
1371 if (t
->answer_rcode
== DNS_RCODE_SUCCESS
)
1372 dns_transaction_complete(t
, DNS_TRANSACTION_SUCCESS
);
1374 dns_transaction_complete(t
, DNS_TRANSACTION_RCODE_FAILURE
);
1382 static int dns_transaction_make_packet_mdns(DnsTransaction
*t
) {
1384 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1385 bool add_known_answers
= false;
1386 DnsTransaction
*other
;
1388 DnsResourceKey
*tkey
;
1389 _cleanup_set_free_ Set
*keys
= NULL
;
1391 unsigned nscount
= 0;
1396 assert(t
->scope
->protocol
== DNS_PROTOCOL_MDNS
);
1398 /* Discard any previously prepared packet, so we can start over and coalesce again */
1399 t
->sent
= dns_packet_unref(t
->sent
);
1401 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, false);
1405 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1411 if (dns_key_is_shared(t
->key
))
1412 add_known_answers
= true;
1414 if (t
->key
->type
== DNS_TYPE_ANY
) {
1415 r
= set_ensure_allocated(&keys
, &dns_resource_key_hash_ops
);
1419 r
= set_put(keys
, t
->key
);
1425 * For mDNS, we want to coalesce as many open queries in pending transactions into one single
1426 * query packet on the wire as possible. To achieve that, we iterate through all pending transactions
1427 * in our current scope, and see whether their timing contraints allow them to be sent.
1430 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1432 LIST_FOREACH(transactions_by_scope
, other
, t
->scope
->transactions
) {
1434 /* Skip ourselves */
1438 if (other
->state
!= DNS_TRANSACTION_PENDING
)
1441 if (other
->next_attempt_after
> ts
)
1444 if (qdcount
>= UINT16_MAX
)
1447 r
= dns_packet_append_key(p
, other
->key
, 0, NULL
);
1450 * If we can't stuff more questions into the packet, just give up.
1451 * One of the 'other' transactions will fire later and take care of the rest.
1459 r
= dns_transaction_prepare(other
, ts
);
1463 ts
+= transaction_get_resend_timeout(other
);
1465 r
= sd_event_add_time(
1466 other
->scope
->manager
->event
,
1467 &other
->timeout_event_source
,
1468 clock_boottime_or_monotonic(),
1470 on_transaction_timeout
, other
);
1474 (void) sd_event_source_set_description(other
->timeout_event_source
, "dns-transaction-timeout");
1476 other
->state
= DNS_TRANSACTION_PENDING
;
1477 other
->next_attempt_after
= ts
;
1481 if (dns_key_is_shared(other
->key
))
1482 add_known_answers
= true;
1484 if (other
->key
->type
== DNS_TYPE_ANY
) {
1485 r
= set_ensure_allocated(&keys
, &dns_resource_key_hash_ops
);
1489 r
= set_put(keys
, other
->key
);
1495 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(qdcount
);
1497 /* Append known answer section if we're asking for any shared record */
1498 if (add_known_answers
) {
1499 r
= dns_cache_export_shared_to_packet(&t
->scope
->cache
, p
);
1504 SET_FOREACH(tkey
, keys
, i
) {
1505 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
1508 r
= dns_zone_lookup(&t
->scope
->zone
, tkey
, t
->scope
->link
->ifindex
, &answer
, NULL
, &tentative
);
1512 r
= dns_packet_append_answer(p
, answer
);
1516 nscount
+= dns_answer_size(answer
);
1518 DNS_PACKET_HEADER(p
)->nscount
= htobe16(nscount
);
1520 t
->sent
= TAKE_PTR(p
);
1525 static int dns_transaction_make_packet(DnsTransaction
*t
) {
1526 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1531 if (t
->scope
->protocol
== DNS_PROTOCOL_MDNS
)
1532 return dns_transaction_make_packet_mdns(t
);
1537 r
= dns_packet_new_query(&p
, t
->scope
->protocol
, 0, t
->scope
->dnssec_mode
!= DNSSEC_NO
);
1541 r
= dns_packet_append_key(p
, t
->key
, 0, NULL
);
1545 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
1546 DNS_PACKET_HEADER(p
)->id
= t
->id
;
1548 t
->sent
= TAKE_PTR(p
);
1553 int dns_transaction_go(DnsTransaction
*t
) {
1556 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1560 /* Returns > 0 if the transaction is now pending, returns 0 if could be processed immediately and has finished
1563 assert_se(sd_event_now(t
->scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1565 r
= dns_transaction_prepare(t
, ts
);
1569 log_debug("Transaction %" PRIu16
" for <%s> scope %s on %s/%s.",
1571 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
),
1572 dns_protocol_to_string(t
->scope
->protocol
),
1573 t
->scope
->link
? t
->scope
->link
->name
: "*",
1574 af_to_name_short(t
->scope
->family
));
1576 if (!t
->initial_jitter_scheduled
&&
1577 IN_SET(t
->scope
->protocol
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
)) {
1578 usec_t jitter
, accuracy
;
1580 /* RFC 4795 Section 2.7 suggests all queries should be
1581 * delayed by a random time from 0 to JITTER_INTERVAL. */
1583 t
->initial_jitter_scheduled
= true;
1585 random_bytes(&jitter
, sizeof(jitter
));
1587 switch (t
->scope
->protocol
) {
1589 case DNS_PROTOCOL_LLMNR
:
1590 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
1591 accuracy
= LLMNR_JITTER_INTERVAL_USEC
;
1594 case DNS_PROTOCOL_MDNS
:
1595 jitter
%= MDNS_JITTER_RANGE_USEC
;
1596 jitter
+= MDNS_JITTER_MIN_USEC
;
1597 accuracy
= MDNS_JITTER_RANGE_USEC
;
1600 assert_not_reached("bad protocol");
1603 r
= sd_event_add_time(
1604 t
->scope
->manager
->event
,
1605 &t
->timeout_event_source
,
1606 clock_boottime_or_monotonic(),
1607 ts
+ jitter
, accuracy
,
1608 on_transaction_timeout
, t
);
1612 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1615 t
->next_attempt_after
= ts
;
1616 t
->state
= DNS_TRANSACTION_PENDING
;
1618 log_debug("Delaying %s transaction for " USEC_FMT
"us.", dns_protocol_to_string(t
->scope
->protocol
), jitter
);
1622 /* Otherwise, we need to ask the network */
1623 r
= dns_transaction_make_packet(t
);
1627 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&&
1628 (dns_name_endswith(dns_resource_key_name(t
->key
), "in-addr.arpa") > 0 ||
1629 dns_name_endswith(dns_resource_key_name(t
->key
), "ip6.arpa") > 0)) {
1631 /* RFC 4795, Section 2.4. says reverse lookups shall
1632 * always be made via TCP on LLMNR */
1633 r
= dns_transaction_open_tcp(t
);
1635 /* Try via UDP, and if that fails due to large size or lack of
1636 * support try via TCP */
1637 r
= dns_transaction_emit_udp(t
);
1639 log_debug("Sending query via TCP since it is too large.");
1640 else if (r
== -EAGAIN
)
1641 log_debug("Sending query via TCP since server doesn't support UDP.");
1642 if (IN_SET(r
, -EMSGSIZE
, -EAGAIN
))
1643 r
= dns_transaction_open_tcp(t
);
1647 /* No servers to send this to? */
1648 dns_transaction_complete(t
, DNS_TRANSACTION_NO_SERVERS
);
1651 if (r
== -EOPNOTSUPP
) {
1652 /* Tried to ask for DNSSEC RRs, on a server that doesn't do DNSSEC */
1653 dns_transaction_complete(t
, DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
);
1656 if (t
->scope
->protocol
== DNS_PROTOCOL_LLMNR
&& ERRNO_IS_DISCONNECT(-r
)) {
1657 /* On LLMNR, if we cannot connect to a host via TCP when doing reverse lookups. This means we cannot
1658 * answer this request with this protocol. */
1659 dns_transaction_complete(t
, DNS_TRANSACTION_NOT_FOUND
);
1663 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1666 /* Couldn't send? Try immediately again, with a new server */
1667 dns_scope_next_dns_server(t
->scope
);
1669 return dns_transaction_go(t
);
1672 ts
+= transaction_get_resend_timeout(t
);
1674 r
= sd_event_add_time(
1675 t
->scope
->manager
->event
,
1676 &t
->timeout_event_source
,
1677 clock_boottime_or_monotonic(),
1679 on_transaction_timeout
, t
);
1683 (void) sd_event_source_set_description(t
->timeout_event_source
, "dns-transaction-timeout");
1685 t
->state
= DNS_TRANSACTION_PENDING
;
1686 t
->next_attempt_after
= ts
;
1691 static int dns_transaction_find_cyclic(DnsTransaction
*t
, DnsTransaction
*aux
) {
1699 /* Try to find cyclic dependencies between transaction objects */
1704 SET_FOREACH(n
, aux
->dnssec_transactions
, i
) {
1705 r
= dns_transaction_find_cyclic(t
, n
);
1713 static int dns_transaction_add_dnssec_transaction(DnsTransaction
*t
, DnsResourceKey
*key
, DnsTransaction
**ret
) {
1714 DnsTransaction
*aux
;
1721 aux
= dns_scope_find_transaction(t
->scope
, key
, true);
1723 r
= dns_transaction_new(&aux
, t
->scope
, key
);
1727 if (set_contains(t
->dnssec_transactions
, aux
)) {
1732 r
= dns_transaction_find_cyclic(t
, aux
);
1736 char s
[DNS_RESOURCE_KEY_STRING_MAX
], saux
[DNS_RESOURCE_KEY_STRING_MAX
];
1738 log_debug("Potential cyclic dependency, refusing to add transaction %" PRIu16
" (%s) as dependency for %" PRIu16
" (%s).",
1740 dns_resource_key_to_string(t
->key
, s
, sizeof s
),
1742 dns_resource_key_to_string(aux
->key
, saux
, sizeof saux
));
1748 r
= set_ensure_allocated(&t
->dnssec_transactions
, NULL
);
1752 r
= set_ensure_allocated(&aux
->notify_transactions
, NULL
);
1756 r
= set_ensure_allocated(&aux
->notify_transactions_done
, NULL
);
1760 r
= set_put(t
->dnssec_transactions
, aux
);
1764 r
= set_put(aux
->notify_transactions
, t
);
1766 (void) set_remove(t
->dnssec_transactions
, aux
);
1774 dns_transaction_gc(aux
);
1778 static int dns_transaction_request_dnssec_rr(DnsTransaction
*t
, DnsResourceKey
*key
) {
1779 _cleanup_(dns_answer_unrefp
) DnsAnswer
*a
= NULL
;
1780 DnsTransaction
*aux
;
1786 /* Try to get the data from the trust anchor */
1787 r
= dns_trust_anchor_lookup_positive(&t
->scope
->manager
->trust_anchor
, key
, &a
);
1791 r
= dns_answer_extend(&t
->validated_keys
, a
);
1798 /* This didn't work, ask for it via the network/cache then. */
1799 r
= dns_transaction_add_dnssec_transaction(t
, key
, &aux
);
1800 if (r
== -ELOOP
) /* This would result in a cyclic dependency */
1805 if (aux
->state
== DNS_TRANSACTION_NULL
) {
1806 r
= dns_transaction_go(aux
);
1814 static int dns_transaction_negative_trust_anchor_lookup(DnsTransaction
*t
, const char *name
) {
1819 /* Check whether the specified name is in the NTA
1820 * database, either in the global one, or the link-local
1823 r
= dns_trust_anchor_lookup_negative(&t
->scope
->manager
->trust_anchor
, name
);
1827 if (!t
->scope
->link
)
1830 return set_contains(t
->scope
->link
->dnssec_negative_trust_anchors
, name
);
1833 static int dns_transaction_has_unsigned_negative_answer(DnsTransaction
*t
) {
1838 /* Checks whether the answer is negative, and lacks NSEC/NSEC3
1839 * RRs to prove it */
1841 r
= dns_transaction_has_positive_answer(t
, NULL
);
1847 /* Is this key explicitly listed as a negative trust anchor?
1848 * If so, it's nothing we need to care about */
1849 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
1855 /* The answer does not contain any RRs that match to the
1856 * question. If so, let's see if there are any NSEC/NSEC3 RRs
1857 * included. If not, the answer is unsigned. */
1859 r
= dns_answer_contains_nsec_or_nsec3(t
->answer
);
1868 static int dns_transaction_is_primary_response(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
1874 /* Check if the specified RR is the "primary" response,
1875 * i.e. either matches the question precisely or is a
1876 * CNAME/DNAME for it. */
1878 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
1882 return dns_resource_key_match_cname_or_dname(t
->key
, rr
->key
, NULL
);
1885 static bool dns_transaction_dnssec_supported(DnsTransaction
*t
) {
1888 /* Checks whether our transaction's DNS server is assumed to be compatible with DNSSEC. Returns false as soon
1889 * as we changed our mind about a server, and now believe it is incompatible with DNSSEC. */
1891 if (t
->scope
->protocol
!= DNS_PROTOCOL_DNS
)
1894 /* If we have picked no server, then we are working from the cache or some other source, and DNSSEC might well
1895 * be supported, hence return true. */
1899 /* Note that we do not check the feature level actually used for the transaction but instead the feature level
1900 * the server is known to support currently, as the transaction feature level might be lower than what the
1901 * server actually supports, since we might have downgraded this transaction's feature level because we got a
1902 * SERVFAIL earlier and wanted to check whether downgrading fixes it. */
1904 return dns_server_dnssec_supported(t
->server
);
1907 static bool dns_transaction_dnssec_supported_full(DnsTransaction
*t
) {
1913 /* Checks whether our transaction our any of the auxiliary transactions couldn't do DNSSEC. */
1915 if (!dns_transaction_dnssec_supported(t
))
1918 SET_FOREACH(dt
, t
->dnssec_transactions
, i
)
1919 if (!dns_transaction_dnssec_supported(dt
))
1925 int dns_transaction_request_dnssec_keys(DnsTransaction
*t
) {
1926 DnsResourceRecord
*rr
;
1933 * Retrieve all auxiliary RRs for the answer we got, so that
1934 * we can verify signatures or prove that RRs are rightfully
1935 * unsigned. Specifically:
1937 * - For RRSIG we get the matching DNSKEY
1938 * - For DNSKEY we get the matching DS
1939 * - For unsigned SOA/NS we get the matching DS
1940 * - For unsigned CNAME/DNAME/DS we get the parent SOA RR
1941 * - For other unsigned RRs we get the matching SOA RR
1942 * - For SOA/NS queries with no matching response RR, and no NSEC/NSEC3, the DS RR
1943 * - For DS queries with no matching response RRs, and no NSEC/NSEC3, the parent's SOA RR
1944 * - For other queries with no matching response RRs, and no NSEC/NSEC3, the SOA RR
1947 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
1949 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
1950 return 0; /* We only need to validate stuff from the network */
1951 if (!dns_transaction_dnssec_supported(t
))
1952 return 0; /* If we can't do DNSSEC anyway there's no point in geting the auxiliary RRs */
1954 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
1956 if (dns_type_is_pseudo(rr
->key
->type
))
1959 /* If this RR is in the negative trust anchor, we don't need to validate it. */
1960 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
1966 switch (rr
->key
->type
) {
1968 case DNS_TYPE_RRSIG
: {
1969 /* For each RRSIG we request the matching DNSKEY */
1970 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*dnskey
= NULL
;
1972 /* If this RRSIG is about a DNSKEY RR and the
1973 * signer is the same as the owner, then we
1974 * already have the DNSKEY, and we don't have
1975 * to look for more. */
1976 if (rr
->rrsig
.type_covered
== DNS_TYPE_DNSKEY
) {
1977 r
= dns_name_equal(rr
->rrsig
.signer
, dns_resource_key_name(rr
->key
));
1984 /* If the signer is not a parent of our
1985 * original query, then this is about an
1986 * auxiliary RRset, but not anything we asked
1987 * for. In this case we aren't interested,
1988 * because we don't want to request additional
1989 * RRs for stuff we didn't really ask for, and
1990 * also to avoid request loops, where
1991 * additional RRs from one transaction result
1992 * in another transaction whose additonal RRs
1993 * point back to the original transaction, and
1995 r
= dns_name_endswith(dns_resource_key_name(t
->key
), rr
->rrsig
.signer
);
2001 dnskey
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DNSKEY
, rr
->rrsig
.signer
);
2005 log_debug("Requesting DNSKEY to validate transaction %" PRIu16
" (%s, RRSIG with key tag: %" PRIu16
").",
2006 t
->id
, dns_resource_key_name(rr
->key
), rr
->rrsig
.key_tag
);
2007 r
= dns_transaction_request_dnssec_rr(t
, dnskey
);
2013 case DNS_TYPE_DNSKEY
: {
2014 /* For each DNSKEY we request the matching DS */
2015 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2017 /* If the DNSKEY we are looking at is not for
2018 * zone we are interested in, nor any of its
2019 * parents, we aren't interested, and don't
2020 * request it. After all, we don't want to end
2021 * up in request loops, and want to keep
2022 * additional traffic down. */
2024 r
= dns_name_endswith(dns_resource_key_name(t
->key
), dns_resource_key_name(rr
->key
));
2030 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2034 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, DNSKEY with key tag: %" PRIu16
").",
2035 t
->id
, dns_resource_key_name(rr
->key
), dnssec_keytag(rr
, false));
2036 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2045 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*ds
= NULL
;
2047 /* For an unsigned SOA or NS, try to acquire
2048 * the matching DS RR, as we are at a zone cut
2049 * then, and whether a DS exists tells us
2050 * whether the zone is signed. Do so only if
2051 * this RR matches our original question,
2054 r
= dns_resource_key_match_rr(t
->key
, rr
, NULL
);
2058 /* Hmm, so this SOA RR doesn't match our original question. In this case, maybe this is
2059 * a negative reply, and we need the a SOA RR's TTL in order to cache a negative entry?
2060 * If so, we need to validate it, too. */
2062 r
= dns_answer_match_key(t
->answer
, t
->key
, NULL
);
2065 if (r
> 0) /* positive reply, we won't need the SOA and hence don't need to validate
2070 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2076 ds
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_DS
, dns_resource_key_name(rr
->key
));
2080 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned SOA/NS RRset).",
2081 t
->id
, dns_resource_key_name(rr
->key
));
2082 r
= dns_transaction_request_dnssec_rr(t
, ds
);
2090 case DNS_TYPE_CNAME
:
2091 case DNS_TYPE_DNAME
: {
2092 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2095 /* CNAMEs and DNAMEs cannot be located at a
2096 * zone apex, hence ask for the parent SOA for
2097 * unsigned CNAME/DNAME RRs, maybe that's the
2098 * apex. But do all that only if this is
2099 * actually a response to our original
2102 * Similar for DS RRs, which are signed when
2103 * the parent SOA is signed. */
2105 r
= dns_transaction_is_primary_response(t
, rr
);
2111 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2117 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2123 name
= dns_resource_key_name(rr
->key
);
2124 r
= dns_name_parent(&name
);
2130 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, name
);
2134 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned CNAME/DNAME/DS RRset).",
2135 t
->id
, dns_resource_key_name(rr
->key
));
2136 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2144 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2146 /* For other unsigned RRsets (including
2147 * NSEC/NSEC3!), look for proof the zone is
2148 * unsigned, by requesting the SOA RR of the
2149 * zone. However, do so only if they are
2150 * directly relevant to our original
2153 r
= dns_transaction_is_primary_response(t
, rr
);
2159 r
= dnssec_has_rrsig(t
->answer
, rr
->key
);
2165 soa
= dns_resource_key_new(rr
->key
->class, DNS_TYPE_SOA
, dns_resource_key_name(rr
->key
));
2169 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned non-SOA/NS RRset <%s>).",
2170 t
->id
, dns_resource_key_name(rr
->key
), dns_resource_record_to_string(rr
));
2171 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2178 /* Above, we requested everything necessary to validate what
2179 * we got. Now, let's request what we need to validate what we
2182 r
= dns_transaction_has_unsigned_negative_answer(t
);
2189 name
= dns_resource_key_name(t
->key
);
2191 /* If this was a SOA or NS request, then check if there's a DS RR for the same domain. Note that this
2192 * could also be used as indication that we are not at a zone apex, but in real world setups there are
2193 * too many broken DNS servers (Hello, incapdns.net!) where non-terminal zones return NXDOMAIN even
2194 * though they have further children. If this was a DS request, then it's signed when the parent zone
2195 * is signed, hence ask the parent SOA in that case. If this was any other RR then ask for the SOA RR,
2196 * to see if that is signed. */
2198 if (t
->key
->type
== DNS_TYPE_DS
) {
2199 r
= dns_name_parent(&name
);
2201 type
= DNS_TYPE_SOA
;
2202 log_debug("Requesting parent SOA to validate transaction %" PRIu16
" (%s, unsigned empty DS response).",
2203 t
->id
, dns_resource_key_name(t
->key
));
2207 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
)) {
2210 log_debug("Requesting DS to validate transaction %" PRIu16
" (%s, unsigned empty SOA/NS response).",
2211 t
->id
, dns_resource_key_name(t
->key
));
2214 type
= DNS_TYPE_SOA
;
2215 log_debug("Requesting SOA to validate transaction %" PRIu16
" (%s, unsigned empty non-SOA/NS/DS response).",
2216 t
->id
, dns_resource_key_name(t
->key
));
2220 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*soa
= NULL
;
2222 soa
= dns_resource_key_new(t
->key
->class, type
, name
);
2226 r
= dns_transaction_request_dnssec_rr(t
, soa
);
2232 return dns_transaction_dnssec_is_live(t
);
2235 void dns_transaction_notify(DnsTransaction
*t
, DnsTransaction
*source
) {
2239 /* Invoked whenever any of our auxiliary DNSSEC transactions completed its work. If the state is still PENDING,
2240 we are still in the loop that adds further DNSSEC transactions, hence don't check if we are ready yet. If
2241 the state is VALIDATING however, we should check if we are complete now. */
2243 if (t
->state
== DNS_TRANSACTION_VALIDATING
)
2244 dns_transaction_process_dnssec(t
);
2247 static int dns_transaction_validate_dnskey_by_ds(DnsTransaction
*t
) {
2248 DnsResourceRecord
*rr
;
2253 /* Add all DNSKEY RRs from the answer that are validated by DS
2254 * RRs from the list of validated keys to the list of
2255 * validated keys. */
2257 DNS_ANSWER_FOREACH_IFINDEX(rr
, ifindex
, t
->answer
) {
2259 r
= dnssec_verify_dnskey_by_ds_search(rr
, t
->validated_keys
);
2265 /* If so, the DNSKEY is validated too. */
2266 r
= dns_answer_add_extend(&t
->validated_keys
, rr
, ifindex
, DNS_ANSWER_AUTHENTICATED
);
2274 static int dns_transaction_requires_rrsig(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2280 /* Checks if the RR we are looking for must be signed with an
2281 * RRSIG. This is used for positive responses. */
2283 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2286 if (dns_type_is_pseudo(rr
->key
->type
))
2289 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2295 switch (rr
->key
->type
) {
2297 case DNS_TYPE_RRSIG
:
2298 /* RRSIGs are the signatures themselves, they need no signing. */
2306 /* For SOA or NS RRs we look for a matching DS transaction */
2308 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2310 if (dt
->key
->class != rr
->key
->class)
2312 if (dt
->key
->type
!= DNS_TYPE_DS
)
2315 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2321 /* We found a DS transactions for the SOA/NS
2322 * RRs we are looking at. If it discovered signed DS
2323 * RRs, then we need to be signed, too. */
2325 if (!dt
->answer_authenticated
)
2328 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2331 /* We found nothing that proves this is safe to leave
2332 * this unauthenticated, hence ask inist on
2333 * authentication. */
2338 case DNS_TYPE_CNAME
:
2339 case DNS_TYPE_DNAME
: {
2340 const char *parent
= NULL
;
2345 * CNAME/DNAME RRs cannot be located at a zone apex, hence look directly for the parent SOA.
2347 * DS RRs are signed if the parent is signed, hence also look at the parent SOA
2350 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2352 if (dt
->key
->class != rr
->key
->class)
2354 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2358 parent
= dns_resource_key_name(rr
->key
);
2359 r
= dns_name_parent(&parent
);
2363 if (rr
->key
->type
== DNS_TYPE_DS
)
2366 /* A CNAME/DNAME without a parent? That's sooo weird. */
2367 log_debug("Transaction %" PRIu16
" claims CNAME/DNAME at root. Refusing.", t
->id
);
2372 r
= dns_name_equal(dns_resource_key_name(dt
->key
), parent
);
2378 return t
->answer_authenticated
;
2388 /* Any other kind of RR (including DNSKEY/NSEC/NSEC3). Let's see if our SOA lookup was authenticated */
2390 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2392 if (dt
->key
->class != rr
->key
->class)
2394 if (dt
->key
->type
!= DNS_TYPE_SOA
)
2397 r
= dns_name_equal(dns_resource_key_name(dt
->key
), dns_resource_key_name(rr
->key
));
2403 /* We found the transaction that was supposed to find
2404 * the SOA RR for us. It was successful, but found no
2405 * RR for us. This means we are not at a zone cut. In
2406 * this case, we require authentication if the SOA
2407 * lookup was authenticated too. */
2408 return t
->answer_authenticated
;
2415 static int dns_transaction_in_private_tld(DnsTransaction
*t
, const DnsResourceKey
*key
) {
2421 /* If DNSSEC downgrade mode is on, checks whether the
2422 * specified RR is one level below a TLD we have proven not to
2423 * exist. In such a case we assume that this is a private
2424 * domain, and permit it.
2426 * This detects cases like the Fritz!Box router networks. Each
2427 * Fritz!Box router serves a private "fritz.box" zone, in the
2428 * non-existing TLD "box". Requests for the "fritz.box" domain
2429 * are served by the router itself, while requests for the
2430 * "box" domain will result in NXDOMAIN.
2432 * Note that this logic is unable to detect cases where a
2433 * router serves a private DNS zone directly under
2434 * non-existing TLD. In such a case we cannot detect whether
2435 * the TLD is supposed to exist or not, as all requests we
2436 * make for it will be answered by the router's zone, and not
2437 * by the root zone. */
2441 if (t
->scope
->dnssec_mode
!= DNSSEC_ALLOW_DOWNGRADE
)
2442 return false; /* In strict DNSSEC mode what doesn't exist, doesn't exist */
2444 tld
= dns_resource_key_name(key
);
2445 r
= dns_name_parent(&tld
);
2449 return false; /* Already the root domain */
2451 if (!dns_name_is_single_label(tld
))
2454 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2456 if (dt
->key
->class != key
->class)
2459 r
= dns_name_equal(dns_resource_key_name(dt
->key
), tld
);
2465 /* We found an auxiliary lookup we did for the TLD. If
2466 * that returned with NXDOMAIN, we know the TLD didn't
2467 * exist, and hence this might be a private zone. */
2469 return dt
->answer_rcode
== DNS_RCODE_NXDOMAIN
;
2475 static int dns_transaction_requires_nsec(DnsTransaction
*t
) {
2476 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2485 /* Checks if we need to insist on NSEC/NSEC3 RRs for proving
2486 * this negative reply */
2488 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2491 if (dns_type_is_pseudo(t
->key
->type
))
2494 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(t
->key
));
2500 r
= dns_transaction_in_private_tld(t
, t
->key
);
2504 /* The lookup is from a TLD that is proven not to
2505 * exist, and we are in downgrade mode, hence ignore
2506 * that fact that we didn't get any NSEC RRs. */
2508 log_info("Detected a negative query %s in a private DNS zone, permitting unsigned response.",
2509 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
2513 name
= dns_resource_key_name(t
->key
);
2515 if (t
->key
->type
== DNS_TYPE_DS
) {
2517 /* We got a negative reply for this DS lookup? DS RRs are signed when their parent zone is signed,
2518 * hence check the parent SOA in this case. */
2520 r
= dns_name_parent(&name
);
2526 type
= DNS_TYPE_SOA
;
2528 } else if (IN_SET(t
->key
->type
, DNS_TYPE_SOA
, DNS_TYPE_NS
))
2529 /* We got a negative reply for this SOA/NS lookup? If so, check if there's a DS RR for this */
2532 /* For all other negative replies, check for the SOA lookup */
2533 type
= DNS_TYPE_SOA
;
2535 /* For all other RRs we check the SOA on the same level to see
2536 * if it's signed. */
2538 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2540 if (dt
->key
->class != t
->key
->class)
2542 if (dt
->key
->type
!= type
)
2545 r
= dns_name_equal(dns_resource_key_name(dt
->key
), name
);
2551 return dt
->answer_authenticated
;
2554 /* If in doubt, require NSEC/NSEC3 */
2558 static int dns_transaction_dnskey_authenticated(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2559 DnsResourceRecord
*rrsig
;
2563 /* Checks whether any of the DNSKEYs used for the RRSIGs for
2564 * the specified RRset is authenticated (i.e. has a matching
2567 r
= dns_transaction_negative_trust_anchor_lookup(t
, dns_resource_key_name(rr
->key
));
2573 DNS_ANSWER_FOREACH(rrsig
, t
->answer
) {
2577 r
= dnssec_key_match_rrsig(rr
->key
, rrsig
);
2583 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2585 if (dt
->key
->class != rr
->key
->class)
2588 if (dt
->key
->type
== DNS_TYPE_DNSKEY
) {
2590 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2596 /* OK, we found an auxiliary DNSKEY
2597 * lookup. If that lookup is
2598 * authenticated, report this. */
2600 if (dt
->answer_authenticated
)
2605 } else if (dt
->key
->type
== DNS_TYPE_DS
) {
2607 r
= dns_name_equal(dns_resource_key_name(dt
->key
), rrsig
->rrsig
.signer
);
2613 /* OK, we found an auxiliary DS
2614 * lookup. If that lookup is
2615 * authenticated and non-zero, we
2618 if (!dt
->answer_authenticated
)
2621 return dns_answer_match_key(dt
->answer
, dt
->key
, NULL
);
2626 return found
? false : -ENXIO
;
2629 static int dns_transaction_known_signed(DnsTransaction
*t
, DnsResourceRecord
*rr
) {
2633 /* We know that the root domain is signed, hence if it appears
2634 * not to be signed, there's a problem with the DNS server */
2636 return rr
->key
->class == DNS_CLASS_IN
&&
2637 dns_name_is_root(dns_resource_key_name(rr
->key
));
2640 static int dns_transaction_check_revoked_trust_anchors(DnsTransaction
*t
) {
2641 DnsResourceRecord
*rr
;
2646 /* Maybe warn the user that we encountered a revoked DNSKEY
2647 * for a key from our trust anchor. Note that we don't care
2648 * whether the DNSKEY can be authenticated or not. It's
2649 * sufficient if it is self-signed. */
2651 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2652 r
= dns_trust_anchor_check_revoked(&t
->scope
->manager
->trust_anchor
, rr
, t
->answer
);
2660 static int dns_transaction_invalidate_revoked_keys(DnsTransaction
*t
) {
2666 /* Removes all DNSKEY/DS objects from t->validated_keys that
2667 * our trust anchors database considers revoked. */
2670 DnsResourceRecord
*rr
;
2674 DNS_ANSWER_FOREACH(rr
, t
->validated_keys
) {
2675 r
= dns_trust_anchor_is_revoked(&t
->scope
->manager
->trust_anchor
, rr
);
2679 r
= dns_answer_remove_by_rr(&t
->validated_keys
, rr
);
2693 static int dns_transaction_copy_validated(DnsTransaction
*t
) {
2700 /* Copy all validated RRs from the auxiliary DNSSEC transactions into our set of validated RRs */
2702 SET_FOREACH(dt
, t
->dnssec_transactions
, i
) {
2704 if (DNS_TRANSACTION_IS_LIVE(dt
->state
))
2707 if (!dt
->answer_authenticated
)
2710 r
= dns_answer_extend(&t
->validated_keys
, dt
->answer
);
2719 DNSSEC_PHASE_DNSKEY
, /* Phase #1, only validate DNSKEYs */
2720 DNSSEC_PHASE_NSEC
, /* Phase #2, only validate NSEC+NSEC3 */
2721 DNSSEC_PHASE_ALL
, /* Phase #3, validate everything else */
2724 static int dnssec_validate_records(
2728 DnsAnswer
**validated
) {
2730 DnsResourceRecord
*rr
;
2733 /* Returns negative on error, 0 if validation failed, 1 to restart validation, 2 when finished. */
2735 DNS_ANSWER_FOREACH(rr
, t
->answer
) {
2736 DnsResourceRecord
*rrsig
= NULL
;
2737 DnssecResult result
;
2739 switch (rr
->key
->type
) {
2740 case DNS_TYPE_RRSIG
:
2743 case DNS_TYPE_DNSKEY
:
2744 /* We validate DNSKEYs only in the DNSKEY and ALL phases */
2745 if (phase
== DNSSEC_PHASE_NSEC
)
2750 case DNS_TYPE_NSEC3
:
2753 /* We validate NSEC/NSEC3 only in the NSEC and ALL phases */
2754 if (phase
== DNSSEC_PHASE_DNSKEY
)
2759 /* We validate all other RRs only in the ALL phases */
2760 if (phase
!= DNSSEC_PHASE_ALL
)
2764 r
= dnssec_verify_rrset_search(t
->answer
, rr
->key
, t
->validated_keys
, USEC_INFINITY
, &result
, &rrsig
);
2768 log_debug("Looking at %s: %s", strna(dns_resource_record_to_string(rr
)), dnssec_result_to_string(result
));
2770 if (result
== DNSSEC_VALIDATED
) {
2772 if (rr
->key
->type
== DNS_TYPE_DNSKEY
) {
2773 /* If we just validated a DNSKEY RRset, then let's add these keys to
2774 * the set of validated keys for this transaction. */
2776 r
= dns_answer_copy_by_key(&t
->validated_keys
, t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
);
2780 /* Some of the DNSKEYs we just added might already have been revoked,
2781 * remove them again in that case. */
2782 r
= dns_transaction_invalidate_revoked_keys(t
);
2787 /* Add the validated RRset to the new list of validated
2788 * RRsets, and remove it from the unvalidated RRsets.
2789 * We mark the RRset as authenticated and cacheable. */
2790 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
);
2794 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_SECURE
, rr
->key
);
2796 /* Exit the loop, we dropped something from the answer, start from the beginning */
2800 /* If we haven't read all DNSKEYs yet a negative result of the validation is irrelevant, as
2801 * there might be more DNSKEYs coming. Similar, if we haven't read all NSEC/NSEC3 RRs yet,
2802 * we cannot do positive wildcard proofs yet, as those require the NSEC/NSEC3 RRs. */
2803 if (phase
!= DNSSEC_PHASE_ALL
)
2806 if (result
== DNSSEC_VALIDATED_WILDCARD
) {
2807 bool authenticated
= false;
2810 /* This RRset validated, but as a wildcard. This means we need
2811 * to prove via NSEC/NSEC3 that no matching non-wildcard RR exists. */
2813 /* First step, determine the source of synthesis */
2814 r
= dns_resource_record_source(rrsig
, &source
);
2818 r
= dnssec_test_positive_wildcard(*validated
,
2819 dns_resource_key_name(rr
->key
),
2821 rrsig
->rrsig
.signer
,
2824 /* Unless the NSEC proof showed that the key really doesn't exist something is off. */
2826 result
= DNSSEC_INVALID
;
2828 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
,
2829 authenticated
? (DNS_ANSWER_AUTHENTICATED
|DNS_ANSWER_CACHEABLE
) : 0);
2833 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, rr
->key
);
2835 /* Exit the loop, we dropped something from the answer, start from the beginning */
2840 if (result
== DNSSEC_NO_SIGNATURE
) {
2841 r
= dns_transaction_requires_rrsig(t
, rr
);
2845 /* Data does not require signing. In that case, just copy it over,
2846 * but remember that this is by no means authenticated. */
2847 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2851 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2855 r
= dns_transaction_known_signed(t
, rr
);
2859 /* This is an RR we know has to be signed. If it isn't this means
2860 * the server is not attaching RRSIGs, hence complain. */
2862 dns_server_packet_rrsig_missing(t
->server
, t
->current_feature_level
);
2864 if (t
->scope
->dnssec_mode
== DNSSEC_ALLOW_DOWNGRADE
) {
2866 /* Downgrading is OK? If so, just consider the information unsigned */
2868 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2872 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2876 /* Otherwise, fail */
2877 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
2881 r
= dns_transaction_in_private_tld(t
, rr
->key
);
2885 char s
[DNS_RESOURCE_KEY_STRING_MAX
];
2887 /* The data is from a TLD that is proven not to exist, and we are in downgrade
2888 * mode, hence ignore the fact that this was not signed. */
2890 log_info("Detected RRset %s is in a private DNS zone, permitting unsigned RRs.",
2891 dns_resource_key_to_string(rr
->key
, s
, sizeof s
));
2893 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2897 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2904 DNSSEC_SIGNATURE_EXPIRED
,
2905 DNSSEC_UNSUPPORTED_ALGORITHM
)) {
2907 r
= dns_transaction_dnskey_authenticated(t
, rr
);
2908 if (r
< 0 && r
!= -ENXIO
)
2911 /* The DNSKEY transaction was not authenticated, this means there's
2912 * no DS for this, which means it's OK if no keys are found for this signature. */
2914 r
= dns_answer_move_by_key(validated
, &t
->answer
, rr
->key
, 0);
2918 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, rr
->key
);
2923 r
= dns_transaction_is_primary_response(t
, rr
);
2927 /* Look for a matching DNAME for this CNAME */
2928 r
= dns_answer_has_dname_for_cname(t
->answer
, rr
);
2932 /* Also look among the stuff we already validated */
2933 r
= dns_answer_has_dname_for_cname(*validated
, rr
);
2941 DNSSEC_SIGNATURE_EXPIRED
,
2942 DNSSEC_NO_SIGNATURE
))
2943 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, rr
->key
);
2944 else /* DNSSEC_MISSING_KEY or DNSSEC_UNSUPPORTED_ALGORITHM */
2945 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, rr
->key
);
2947 /* This is a primary response to our question, and it failed validation.
2949 t
->answer_dnssec_result
= result
;
2953 /* This is a primary response, but we do have a DNAME RR
2954 * in the RR that can replay this CNAME, hence rely on
2955 * that, and we can remove the CNAME in favour of it. */
2958 /* This is just some auxiliary data. Just remove the RRset and continue. */
2959 r
= dns_answer_remove_by_key(&t
->answer
, rr
->key
);
2963 /* We dropped something from the answer, start from the beginning. */
2967 return 2; /* Finito. */
2970 int dns_transaction_validate_dnssec(DnsTransaction
*t
) {
2971 _cleanup_(dns_answer_unrefp
) DnsAnswer
*validated
= NULL
;
2973 DnsAnswerFlags flags
;
2975 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
2979 /* We have now collected all DS and DNSKEY RRs in
2980 * t->validated_keys, let's see which RRs we can now
2981 * authenticate with that. */
2983 if (t
->scope
->dnssec_mode
== DNSSEC_NO
)
2986 /* Already validated */
2987 if (t
->answer_dnssec_result
!= _DNSSEC_RESULT_INVALID
)
2990 /* Our own stuff needs no validation */
2991 if (IN_SET(t
->answer_source
, DNS_TRANSACTION_ZONE
, DNS_TRANSACTION_TRUST_ANCHOR
)) {
2992 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
2993 t
->answer_authenticated
= true;
2997 /* Cached stuff is not affected by validation. */
2998 if (t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
3001 if (!dns_transaction_dnssec_supported_full(t
)) {
3002 /* The server does not support DNSSEC, or doesn't augment responses with RRSIGs. */
3003 t
->answer_dnssec_result
= DNSSEC_INCOMPATIBLE_SERVER
;
3004 log_debug("Not validating response for %" PRIu16
", used server feature level does not support DNSSEC.", t
->id
);
3008 log_debug("Validating response from transaction %" PRIu16
" (%s).",
3010 dns_resource_key_to_string(t
->key
, key_str
, sizeof key_str
));
3012 /* First, see if this response contains any revoked trust
3013 * anchors we care about */
3014 r
= dns_transaction_check_revoked_trust_anchors(t
);
3018 /* Third, copy all RRs we acquired successfully from auxiliary RRs over. */
3019 r
= dns_transaction_copy_validated(t
);
3023 /* Second, see if there are DNSKEYs we already know a
3024 * validated DS for. */
3025 r
= dns_transaction_validate_dnskey_by_ds(t
);
3029 /* Fourth, remove all DNSKEY and DS RRs again that our trust
3030 * anchor says are revoked. After all we might have marked
3031 * some keys revoked above, but they might still be lingering
3032 * in our validated_keys list. */
3033 r
= dns_transaction_invalidate_revoked_keys(t
);
3037 phase
= DNSSEC_PHASE_DNSKEY
;
3039 bool have_nsec
= false;
3041 r
= dnssec_validate_records(t
, phase
, &have_nsec
, &validated
);
3045 /* Try again as long as we managed to achieve something */
3049 if (phase
== DNSSEC_PHASE_DNSKEY
&& have_nsec
) {
3050 /* OK, we processed all DNSKEYs, and there are NSEC/NSEC3 RRs, look at those now. */
3051 phase
= DNSSEC_PHASE_NSEC
;
3055 if (phase
!= DNSSEC_PHASE_ALL
) {
3056 /* OK, we processed all DNSKEYs and NSEC/NSEC3 RRs, look at all the rest now.
3057 * Note that in this third phase we start to remove RRs we couldn't validate. */
3058 phase
= DNSSEC_PHASE_ALL
;
3066 dns_answer_unref(t
->answer
);
3067 t
->answer
= TAKE_PTR(validated
);
3069 /* At this point the answer only contains validated
3070 * RRsets. Now, let's see if it actually answers the question
3071 * we asked. If so, great! If it doesn't, then see if
3072 * NSEC/NSEC3 can prove this. */
3073 r
= dns_transaction_has_positive_answer(t
, &flags
);
3075 /* Yes, it answers the question! */
3077 if (flags
& DNS_ANSWER_AUTHENTICATED
) {
3078 /* The answer is fully authenticated, yay. */
3079 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3080 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3081 t
->answer_authenticated
= true;
3083 /* The answer is not fully authenticated. */
3084 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3085 t
->answer_authenticated
= false;
3088 } else if (r
== 0) {
3089 DnssecNsecResult nr
;
3090 bool authenticated
= false;
3092 /* Bummer! Let's check NSEC/NSEC3 */
3093 r
= dnssec_nsec_test(t
->answer
, t
->key
, &nr
, &authenticated
, &t
->answer_nsec_ttl
);
3099 case DNSSEC_NSEC_NXDOMAIN
:
3100 /* NSEC proves the domain doesn't exist. Very good. */
3101 log_debug("Proved NXDOMAIN via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3102 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3103 t
->answer_rcode
= DNS_RCODE_NXDOMAIN
;
3104 t
->answer_authenticated
= authenticated
;
3106 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3109 case DNSSEC_NSEC_NODATA
:
3110 /* NSEC proves that there's no data here, very good. */
3111 log_debug("Proved NODATA via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3112 t
->answer_dnssec_result
= DNSSEC_VALIDATED
;
3113 t
->answer_rcode
= DNS_RCODE_SUCCESS
;
3114 t
->answer_authenticated
= authenticated
;
3116 manager_dnssec_verdict(t
->scope
->manager
, authenticated
? DNSSEC_SECURE
: DNSSEC_INSECURE
, t
->key
);
3119 case DNSSEC_NSEC_OPTOUT
:
3120 /* NSEC3 says the data might not be signed */
3121 log_debug("Data is NSEC3 opt-out via NSEC/NSEC3 for transaction %u (%s)", t
->id
, key_str
);
3122 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3123 t
->answer_authenticated
= false;
3125 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3128 case DNSSEC_NSEC_NO_RR
:
3129 /* No NSEC data? Bummer! */
3131 r
= dns_transaction_requires_nsec(t
);
3135 t
->answer_dnssec_result
= DNSSEC_NO_SIGNATURE
;
3136 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3138 t
->answer_dnssec_result
= DNSSEC_UNSIGNED
;
3139 t
->answer_authenticated
= false;
3140 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INSECURE
, t
->key
);
3145 case DNSSEC_NSEC_UNSUPPORTED_ALGORITHM
:
3146 /* We don't know the NSEC3 algorithm used? */
3147 t
->answer_dnssec_result
= DNSSEC_UNSUPPORTED_ALGORITHM
;
3148 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_INDETERMINATE
, t
->key
);
3151 case DNSSEC_NSEC_FOUND
:
3152 case DNSSEC_NSEC_CNAME
:
3153 /* NSEC says it needs to be there, but we couldn't find it? Bummer! */
3154 t
->answer_dnssec_result
= DNSSEC_NSEC_MISMATCH
;
3155 manager_dnssec_verdict(t
->scope
->manager
, DNSSEC_BOGUS
, t
->key
);
3159 assert_not_reached("Unexpected NSEC result.");
3166 static const char* const dns_transaction_state_table
[_DNS_TRANSACTION_STATE_MAX
] = {
3167 [DNS_TRANSACTION_NULL
] = "null",
3168 [DNS_TRANSACTION_PENDING
] = "pending",
3169 [DNS_TRANSACTION_VALIDATING
] = "validating",
3170 [DNS_TRANSACTION_RCODE_FAILURE
] = "rcode-failure",
3171 [DNS_TRANSACTION_SUCCESS
] = "success",
3172 [DNS_TRANSACTION_NO_SERVERS
] = "no-servers",
3173 [DNS_TRANSACTION_TIMEOUT
] = "timeout",
3174 [DNS_TRANSACTION_ATTEMPTS_MAX_REACHED
] = "attempts-max-reached",
3175 [DNS_TRANSACTION_INVALID_REPLY
] = "invalid-reply",
3176 [DNS_TRANSACTION_ERRNO
] = "errno",
3177 [DNS_TRANSACTION_ABORTED
] = "aborted",
3178 [DNS_TRANSACTION_DNSSEC_FAILED
] = "dnssec-failed",
3179 [DNS_TRANSACTION_NO_TRUST_ANCHOR
] = "no-trust-anchor",
3180 [DNS_TRANSACTION_RR_TYPE_UNSUPPORTED
] = "rr-type-unsupported",
3181 [DNS_TRANSACTION_NETWORK_DOWN
] = "network-down",
3182 [DNS_TRANSACTION_NOT_FOUND
] = "not-found",
3184 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_state
, DnsTransactionState
);
3186 static const char* const dns_transaction_source_table
[_DNS_TRANSACTION_SOURCE_MAX
] = {
3187 [DNS_TRANSACTION_NETWORK
] = "network",
3188 [DNS_TRANSACTION_CACHE
] = "cache",
3189 [DNS_TRANSACTION_ZONE
] = "zone",
3190 [DNS_TRANSACTION_TRUST_ANCHOR
] = "trust-anchor",
3192 DEFINE_STRING_TABLE_LOOKUP(dns_transaction_source
, DnsTransactionSource
);