1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2014 Lennart Poettering
8 #include "sd-messages.h"
10 #include "alloc-util.h"
11 #include "resolved-dns-server.h"
12 #include "resolved-dns-stub.h"
13 #include "resolved-resolv-conf.h"
14 #include "siphash24.h"
15 #include "string-table.h"
16 #include "string-util.h"
18 /* The amount of time to wait before retrying with a full feature set */
19 #define DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC (6 * USEC_PER_HOUR)
20 #define DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC (5 * USEC_PER_MINUTE)
22 /* The number of times we will attempt a certain feature set before degrading */
23 #define DNS_SERVER_FEATURE_RETRY_ATTEMPTS 3
31 const union in_addr_union
*in_addr
,
37 assert((type
== DNS_SERVER_LINK
) == !!l
);
40 if (!IN_SET(family
, AF_INET
, AF_INET6
))
44 if (l
->n_dns_servers
>= LINK_DNS_SERVERS_MAX
)
47 if (m
->n_dns_servers
>= MANAGER_DNS_SERVERS_MAX
)
51 s
= new0(DnsServer
, 1);
59 s
->address
= *in_addr
;
62 dns_server_reset_features(s
);
68 LIST_APPEND(servers
, l
->dns_servers
, s
);
72 case DNS_SERVER_SYSTEM
:
73 LIST_APPEND(servers
, m
->dns_servers
, s
);
77 case DNS_SERVER_FALLBACK
:
78 LIST_APPEND(servers
, m
->fallback_dns_servers
, s
);
83 assert_not_reached("Unknown server type");
89 /* Do not verify cerificate */
90 gnutls_certificate_allocate_credentials(&s
->tls_cert_cred
);
93 /* A new DNS server that isn't fallback is added and the one
94 * we used so far was a fallback one? Then let's try to pick
96 if (type
!= DNS_SERVER_FALLBACK
&&
97 m
->current_dns_server
&&
98 m
->current_dns_server
->type
== DNS_SERVER_FALLBACK
)
99 manager_set_dns_server(m
, NULL
);
107 DnsServer
* dns_server_ref(DnsServer
*s
) {
111 assert(s
->n_ref
> 0);
117 DnsServer
* dns_server_unref(DnsServer
*s
) {
121 assert(s
->n_ref
> 0);
127 dns_stream_unref(s
->stream
);
130 if (s
->tls_cert_cred
)
131 gnutls_certificate_free_credentials(s
->tls_cert_cred
);
133 if (s
->tls_session_data
.data
)
134 gnutls_free(s
->tls_session_data
.data
);
137 free(s
->server_string
);
141 void dns_server_unlink(DnsServer
*s
) {
145 /* This removes the specified server from the linked list of
146 * servers, but any server might still stay around if it has
147 * refs, for example from an ongoing transaction. */
154 case DNS_SERVER_LINK
:
156 assert(s
->link
->n_dns_servers
> 0);
157 LIST_REMOVE(servers
, s
->link
->dns_servers
, s
);
158 s
->link
->n_dns_servers
--;
161 case DNS_SERVER_SYSTEM
:
162 assert(s
->manager
->n_dns_servers
> 0);
163 LIST_REMOVE(servers
, s
->manager
->dns_servers
, s
);
164 s
->manager
->n_dns_servers
--;
167 case DNS_SERVER_FALLBACK
:
168 assert(s
->manager
->n_dns_servers
> 0);
169 LIST_REMOVE(servers
, s
->manager
->fallback_dns_servers
, s
);
170 s
->manager
->n_dns_servers
--;
176 if (s
->link
&& s
->link
->current_dns_server
== s
)
177 link_set_dns_server(s
->link
, NULL
);
179 if (s
->manager
->current_dns_server
== s
)
180 manager_set_dns_server(s
->manager
, NULL
);
185 void dns_server_move_back_and_unmark(DnsServer
*s
) {
195 if (!s
->linked
|| !s
->servers_next
)
198 /* Move us to the end of the list, so that the order is
199 * strictly kept, if we are not at the end anyway. */
203 case DNS_SERVER_LINK
:
205 LIST_FIND_TAIL(servers
, s
, tail
);
206 LIST_REMOVE(servers
, s
->link
->dns_servers
, s
);
207 LIST_INSERT_AFTER(servers
, s
->link
->dns_servers
, tail
, s
);
210 case DNS_SERVER_SYSTEM
:
211 LIST_FIND_TAIL(servers
, s
, tail
);
212 LIST_REMOVE(servers
, s
->manager
->dns_servers
, s
);
213 LIST_INSERT_AFTER(servers
, s
->manager
->dns_servers
, tail
, s
);
216 case DNS_SERVER_FALLBACK
:
217 LIST_FIND_TAIL(servers
, s
, tail
);
218 LIST_REMOVE(servers
, s
->manager
->fallback_dns_servers
, s
);
219 LIST_INSERT_AFTER(servers
, s
->manager
->fallback_dns_servers
, tail
, s
);
223 assert_not_reached("Unknown server type");
227 static void dns_server_verified(DnsServer
*s
, DnsServerFeatureLevel level
) {
230 if (s
->verified_feature_level
> level
)
233 if (s
->verified_feature_level
!= level
) {
234 log_debug("Verified we get a response at feature level %s from DNS server %s.",
235 dns_server_feature_level_to_string(level
),
236 dns_server_string(s
));
237 s
->verified_feature_level
= level
;
240 assert_se(sd_event_now(s
->manager
->event
, clock_boottime_or_monotonic(), &s
->verified_usec
) >= 0);
243 static void dns_server_reset_counters(DnsServer
*s
) {
249 s
->packet_truncated
= false;
250 s
->verified_usec
= 0;
252 /* Note that we do not reset s->packet_bad_opt and s->packet_rrsig_missing here. We reset them only when the
253 * grace period ends, but not when lowering the possible feature level, as a lower level feature level should
254 * not make RRSIGs appear or OPT appear, but rather make them disappear. If the reappear anyway, then that's
255 * indication for a differently broken OPT/RRSIG implementation, and we really don't want to support that
258 * This is particularly important to deal with certain Belkin routers which break OPT for certain lookups (A),
259 * but pass traffic through for others (AAAA). If we detect the broken behaviour on one lookup we should not
260 * reenable it for another, because we cannot validate things anyway, given that the RRSIG/OPT data will be
264 void dns_server_packet_received(DnsServer
*s
, int protocol
, DnsServerFeatureLevel level
, size_t size
) {
267 if (protocol
== IPPROTO_UDP
) {
268 if (s
->possible_feature_level
== level
)
270 } else if (protocol
== IPPROTO_TCP
) {
271 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(level
)) {
272 if (s
->possible_feature_level
== level
)
275 if (s
->possible_feature_level
== level
)
278 /* Successful TCP connections are only useful to verify the TCP feature level. */
279 level
= DNS_SERVER_FEATURE_LEVEL_TCP
;
283 /* If the RRSIG data is missing, then we can only validate EDNS0 at max */
284 if (s
->packet_rrsig_missing
&& level
>= DNS_SERVER_FEATURE_LEVEL_DO
)
285 level
= DNS_SERVER_FEATURE_LEVEL_IS_TLS(level
) ? DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
: DNS_SERVER_FEATURE_LEVEL_EDNS0
;
287 /* If the OPT RR got lost, then we can only validate UDP at max */
288 if (s
->packet_bad_opt
&& level
>= DNS_SERVER_FEATURE_LEVEL_EDNS0
)
289 level
= DNS_SERVER_FEATURE_LEVEL_EDNS0
- 1;
291 /* Even if we successfully receive a reply to a request announcing support for large packets,
292 that does not mean we can necessarily receive large packets. */
293 if (level
== DNS_SERVER_FEATURE_LEVEL_LARGE
)
294 level
= DNS_SERVER_FEATURE_LEVEL_LARGE
- 1;
296 dns_server_verified(s
, level
);
298 /* Remember the size of the largest UDP packet we received from a server,
299 we know that we can always announce support for packets with at least
301 if (protocol
== IPPROTO_UDP
&& s
->received_udp_packet_max
< size
)
302 s
->received_udp_packet_max
= size
;
305 void dns_server_packet_lost(DnsServer
*s
, int protocol
, DnsServerFeatureLevel level
, usec_t usec
) {
309 if (s
->possible_feature_level
== level
) {
310 if (protocol
== IPPROTO_UDP
)
312 else if (protocol
== IPPROTO_TCP
) {
313 if (DNS_SERVER_FEATURE_LEVEL_IS_TLS(level
))
321 void dns_server_packet_truncated(DnsServer
*s
, DnsServerFeatureLevel level
) {
324 /* Invoked whenever we get a packet with TC bit set. */
326 if (s
->possible_feature_level
!= level
)
329 s
->packet_truncated
= true;
332 void dns_server_packet_rrsig_missing(DnsServer
*s
, DnsServerFeatureLevel level
) {
335 if (level
< DNS_SERVER_FEATURE_LEVEL_DO
)
338 /* If the RRSIG RRs are missing, we have to downgrade what we previously verified */
339 if (s
->verified_feature_level
>= DNS_SERVER_FEATURE_LEVEL_DO
)
340 s
->verified_feature_level
= DNS_SERVER_FEATURE_LEVEL_IS_TLS(level
) ? DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
: DNS_SERVER_FEATURE_LEVEL_EDNS0
;
342 s
->packet_rrsig_missing
= true;
345 void dns_server_packet_bad_opt(DnsServer
*s
, DnsServerFeatureLevel level
) {
348 if (level
< DNS_SERVER_FEATURE_LEVEL_EDNS0
)
351 /* If the OPT RR got lost, we have to downgrade what we previously verified */
352 if (s
->verified_feature_level
>= DNS_SERVER_FEATURE_LEVEL_EDNS0
)
353 s
->verified_feature_level
= DNS_SERVER_FEATURE_LEVEL_EDNS0
-1;
355 s
->packet_bad_opt
= true;
358 void dns_server_packet_rcode_downgrade(DnsServer
*s
, DnsServerFeatureLevel level
) {
361 /* Invoked whenever we got a FORMERR, SERVFAIL or NOTIMP rcode from a server and downgrading the feature level
362 * for the transaction made it go away. In this case we immediately downgrade to the feature level that made
365 if (s
->verified_feature_level
> level
)
366 s
->verified_feature_level
= level
;
368 if (s
->possible_feature_level
> level
) {
369 s
->possible_feature_level
= level
;
370 dns_server_reset_counters(s
);
373 log_debug("Downgrading transaction feature level fixed an RCODE error, downgrading server %s too.", dns_server_string(s
));
376 static bool dns_server_grace_period_expired(DnsServer
*s
) {
382 if (s
->verified_usec
== 0)
385 assert_se(sd_event_now(s
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
387 if (s
->verified_usec
+ s
->features_grace_period_usec
> ts
)
390 s
->features_grace_period_usec
= MIN(s
->features_grace_period_usec
* 2, DNS_SERVER_FEATURE_GRACE_PERIOD_MAX_USEC
);
395 DnsServerFeatureLevel
dns_server_possible_feature_level(DnsServer
*s
) {
396 DnsServerFeatureLevel best
;
400 /* Determine the best feature level we care about. If DNSSEC mode is off there's no point in using anything
401 * better than EDNS0, hence don't even try. */
402 if (dns_server_get_dnssec_mode(s
) != DNSSEC_NO
)
403 best
= dns_server_get_private_dns_mode(s
) == PRIVATE_DNS_NO
?
404 DNS_SERVER_FEATURE_LEVEL_LARGE
:
405 DNS_SERVER_FEATURE_LEVEL_TLS_DO
;
407 best
= dns_server_get_private_dns_mode(s
) == PRIVATE_DNS_NO
?
408 DNS_SERVER_FEATURE_LEVEL_EDNS0
:
409 DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
;
411 /* Clamp the feature level the highest level we care about. The DNSSEC mode might have changed since the last
412 * time, hence let's downgrade if we are still at a higher level. */
413 if (s
->possible_feature_level
> best
)
414 s
->possible_feature_level
= best
;
416 if (s
->possible_feature_level
< best
&& dns_server_grace_period_expired(s
)) {
418 s
->possible_feature_level
= best
;
420 dns_server_reset_counters(s
);
422 s
->packet_bad_opt
= false;
423 s
->packet_rrsig_missing
= false;
425 log_info("Grace period over, resuming full feature set (%s) for DNS server %s.",
426 dns_server_feature_level_to_string(s
->possible_feature_level
),
427 dns_server_string(s
));
429 dns_server_flush_cache(s
);
431 } else if (s
->possible_feature_level
<= s
->verified_feature_level
)
432 s
->possible_feature_level
= s
->verified_feature_level
;
434 DnsServerFeatureLevel p
= s
->possible_feature_level
;
436 if (s
->n_failed_tcp
>= DNS_SERVER_FEATURE_RETRY_ATTEMPTS
&&
437 s
->possible_feature_level
== DNS_SERVER_FEATURE_LEVEL_TCP
) {
439 /* We are at the TCP (lowest) level, and we tried a couple of TCP connections, and it didn't
440 * work. Upgrade back to UDP again. */
441 log_debug("Reached maximum number of failed TCP connection attempts, trying UDP again...");
442 s
->possible_feature_level
= DNS_SERVER_FEATURE_LEVEL_UDP
;
443 } else if (s
->n_failed_tls
> 0 &&
444 DNS_SERVER_FEATURE_LEVEL_IS_TLS(s
->possible_feature_level
)) {
446 /* We tried to connect using DNS-over-TLS, and it didn't work. Downgrade to plaintext UDP
447 * if we don't require DNS-over-TLS */
449 log_debug("Server doesn't support seem to support DNS-over-TLS, downgrading protocol...");
450 s
->possible_feature_level
--;
451 } else if (s
->packet_bad_opt
&&
452 s
->possible_feature_level
>= DNS_SERVER_FEATURE_LEVEL_EDNS0
) {
454 /* A reply to one of our EDNS0 queries didn't carry a valid OPT RR, then downgrade to below
455 * EDNS0 levels. After all, some records generate different responses with and without OPT RR
456 * in the request. Example:
457 * https://open.nlnetlabs.nl/pipermail/dnssec-trigger/2014-November/000376.html */
459 log_debug("Server doesn't support EDNS(0) properly, downgrading feature level...");
460 s
->possible_feature_level
= DNS_SERVER_FEATURE_LEVEL_UDP
;
462 } else if (s
->packet_rrsig_missing
&&
463 s
->possible_feature_level
>= DNS_SERVER_FEATURE_LEVEL_DO
) {
465 /* RRSIG data was missing on a EDNS0 packet with DO bit set. This means the server doesn't
466 * augment responses with DNSSEC RRs. If so, let's better not ask the server for it anymore,
467 * after all some servers generate different replies depending if an OPT RR is in the query or
470 log_debug("Detected server responses lack RRSIG records, downgrading feature level...");
471 s
->possible_feature_level
= DNS_SERVER_FEATURE_LEVEL_IS_TLS(s
->possible_feature_level
) ? DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
: DNS_SERVER_FEATURE_LEVEL_EDNS0
;
473 } else if (s
->n_failed_udp
>= DNS_SERVER_FEATURE_RETRY_ATTEMPTS
&&
474 s
->possible_feature_level
>= (dns_server_get_dnssec_mode(s
) == DNSSEC_YES
? DNS_SERVER_FEATURE_LEVEL_LARGE
: DNS_SERVER_FEATURE_LEVEL_UDP
)) {
476 /* We lost too many UDP packets in a row, and are on a feature level of UDP or higher. If the
477 * packets are lost, maybe the server cannot parse them, hence downgrading sounds like a good
478 * idea. We might downgrade all the way down to TCP this way.
480 * If strict DNSSEC mode is used we won't downgrade below DO level however, as packet loss
481 * might have many reasons, a broken DNSSEC implementation being only one reason. And if the
482 * user is strict on DNSSEC, then let's assume that DNSSEC is not the fault here. */
484 log_debug("Lost too many UDP packets, downgrading feature level...");
485 s
->possible_feature_level
--;
487 } else if (s
->n_failed_tcp
>= DNS_SERVER_FEATURE_RETRY_ATTEMPTS
&&
488 s
->packet_truncated
&&
489 s
->possible_feature_level
> (dns_server_get_dnssec_mode(s
) == DNSSEC_YES
? DNS_SERVER_FEATURE_LEVEL_LARGE
: DNS_SERVER_FEATURE_LEVEL_UDP
)) {
491 /* We got too many TCP connection failures in a row, we had at least one truncated packet, and
492 * are on a feature level above UDP. By downgrading things and getting rid of DNSSEC or EDNS0
493 * data we hope to make the packet smaller, so that it still works via UDP given that TCP
494 * appears not to be a fallback. Note that if we are already at the lowest UDP level, we don't
495 * go further down, since that's TCP, and TCP failed too often after all. */
497 log_debug("Got too many failed TCP connection failures and truncated UDP packets, downgrading feature level...");
498 s
->possible_feature_level
--;
501 if (p
!= s
->possible_feature_level
) {
503 /* We changed the feature level, reset the counting */
504 dns_server_reset_counters(s
);
506 log_warning("Using degraded feature set (%s) for DNS server %s.",
507 dns_server_feature_level_to_string(s
->possible_feature_level
),
508 dns_server_string(s
));
512 return s
->possible_feature_level
;
515 int dns_server_adjust_opt(DnsServer
*server
, DnsPacket
*packet
, DnsServerFeatureLevel level
) {
522 assert(packet
->protocol
== DNS_PROTOCOL_DNS
);
524 /* Fix the OPT field in the packet to match our current feature level. */
526 r
= dns_packet_truncate_opt(packet
);
530 if (level
< DNS_SERVER_FEATURE_LEVEL_EDNS0
)
533 edns_do
= level
>= DNS_SERVER_FEATURE_LEVEL_DO
;
535 if (level
>= DNS_SERVER_FEATURE_LEVEL_LARGE
)
536 packet_size
= DNS_PACKET_UNICAST_SIZE_LARGE_MAX
;
538 packet_size
= server
->received_udp_packet_max
;
540 return dns_packet_append_opt(packet
, packet_size
, edns_do
, 0, NULL
);
543 int dns_server_ifindex(const DnsServer
*s
) {
546 /* The link ifindex always takes precedence */
548 return s
->link
->ifindex
;
556 const char *dns_server_string(DnsServer
*server
) {
559 if (!server
->server_string
)
560 (void) in_addr_ifindex_to_string(server
->family
, &server
->address
, dns_server_ifindex(server
), &server
->server_string
);
562 return strna(server
->server_string
);
565 bool dns_server_dnssec_supported(DnsServer
*server
) {
568 /* Returns whether the server supports DNSSEC according to what we know about it */
570 if (server
->possible_feature_level
< DNS_SERVER_FEATURE_LEVEL_DO
)
573 if (server
->packet_bad_opt
)
576 if (server
->packet_rrsig_missing
)
579 /* DNSSEC servers need to support TCP properly (see RFC5966), if they don't, we assume DNSSEC is borked too */
580 if (server
->n_failed_tcp
>= DNS_SERVER_FEATURE_RETRY_ATTEMPTS
)
586 void dns_server_warn_downgrade(DnsServer
*server
) {
589 if (server
->warned_downgrade
)
592 log_struct(LOG_NOTICE
,
593 "MESSAGE_ID=" SD_MESSAGE_DNSSEC_DOWNGRADE_STR
,
594 LOG_MESSAGE("Server %s does not support DNSSEC, downgrading to non-DNSSEC mode.", dns_server_string(server
)),
595 "DNS_SERVER=%s", dns_server_string(server
),
596 "DNS_SERVER_FEATURE_LEVEL=%s", dns_server_feature_level_to_string(server
->possible_feature_level
));
598 server
->warned_downgrade
= true;
601 bool dns_server_limited_domains(DnsServer
*server
) {
602 DnsSearchDomain
*domain
;
603 bool domain_restricted
= false;
605 /* Check if the server has route-only domains without ~., i. e. whether
606 * it should only be used for particular domains */
610 LIST_FOREACH(domains
, domain
, server
->link
->search_domains
)
611 if (domain
->route_only
) {
612 domain_restricted
= true;
613 /* ~. means "any domain", thus it is a global server */
614 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain
)))
618 return domain_restricted
;
621 static void dns_server_hash_func(const void *p
, struct siphash
*state
) {
622 const DnsServer
*s
= p
;
626 siphash24_compress(&s
->family
, sizeof(s
->family
), state
);
627 siphash24_compress(&s
->address
, FAMILY_ADDRESS_SIZE(s
->family
), state
);
628 siphash24_compress(&s
->ifindex
, sizeof(s
->ifindex
), state
);
631 static int dns_server_compare_func(const void *a
, const void *b
) {
632 const DnsServer
*x
= a
, *y
= b
;
635 if (x
->family
< y
->family
)
637 if (x
->family
> y
->family
)
640 r
= memcmp(&x
->address
, &y
->address
, FAMILY_ADDRESS_SIZE(x
->family
));
644 if (x
->ifindex
< y
->ifindex
)
646 if (x
->ifindex
> y
->ifindex
)
652 const struct hash_ops dns_server_hash_ops
= {
653 .hash
= dns_server_hash_func
,
654 .compare
= dns_server_compare_func
657 void dns_server_unlink_all(DnsServer
*first
) {
663 next
= first
->servers_next
;
664 dns_server_unlink(first
);
666 dns_server_unlink_all(next
);
669 void dns_server_unlink_marked(DnsServer
*first
) {
675 next
= first
->servers_next
;
678 dns_server_unlink(first
);
680 dns_server_unlink_marked(next
);
683 void dns_server_mark_all(DnsServer
*first
) {
687 first
->marked
= true;
688 dns_server_mark_all(first
->servers_next
);
691 DnsServer
*dns_server_find(DnsServer
*first
, int family
, const union in_addr_union
*in_addr
, int ifindex
) {
694 LIST_FOREACH(servers
, s
, first
)
695 if (s
->family
== family
&& in_addr_equal(family
, &s
->address
, in_addr
) > 0 && s
->ifindex
== ifindex
)
701 DnsServer
*manager_get_first_dns_server(Manager
*m
, DnsServerType t
) {
706 case DNS_SERVER_SYSTEM
:
707 return m
->dns_servers
;
709 case DNS_SERVER_FALLBACK
:
710 return m
->fallback_dns_servers
;
717 DnsServer
*manager_set_dns_server(Manager
*m
, DnsServer
*s
) {
720 if (m
->current_dns_server
== s
)
724 log_debug("Switching to %s DNS server %s.",
725 dns_server_type_to_string(s
->type
),
726 dns_server_string(s
));
728 dns_server_unref(m
->current_dns_server
);
729 m
->current_dns_server
= dns_server_ref(s
);
731 if (m
->unicast_scope
)
732 dns_cache_flush(&m
->unicast_scope
->cache
);
737 DnsServer
*manager_get_dns_server(Manager
*m
) {
741 /* Try to read updates resolv.conf */
742 manager_read_resolv_conf(m
);
744 /* If no DNS server was chosen so far, pick the first one */
745 if (!m
->current_dns_server
)
746 manager_set_dns_server(m
, m
->dns_servers
);
748 if (!m
->current_dns_server
) {
752 /* No DNS servers configured, let's see if there are
753 * any on any links. If not, we use the fallback
756 HASHMAP_FOREACH(l
, m
->links
, i
)
757 if (l
->dns_servers
) {
763 manager_set_dns_server(m
, m
->fallback_dns_servers
);
766 return m
->current_dns_server
;
769 void manager_next_dns_server(Manager
*m
) {
772 /* If there's currently no DNS server set, then the next
773 * manager_get_dns_server() will find one */
774 if (!m
->current_dns_server
)
777 /* Change to the next one, but make sure to follow the linked
778 * list only if the server is still linked. */
779 if (m
->current_dns_server
->linked
&& m
->current_dns_server
->servers_next
) {
780 manager_set_dns_server(m
, m
->current_dns_server
->servers_next
);
784 /* If there was no next one, then start from the beginning of
786 if (m
->current_dns_server
->type
== DNS_SERVER_FALLBACK
)
787 manager_set_dns_server(m
, m
->fallback_dns_servers
);
789 manager_set_dns_server(m
, m
->dns_servers
);
792 bool dns_server_address_valid(int family
, const union in_addr_union
*sa
) {
794 /* Refuses the 0 IP addresses as well as 127.0.0.53 (which is our own DNS stub) */
796 if (in_addr_is_null(family
, sa
))
799 if (family
== AF_INET
&& sa
->in
.s_addr
== htobe32(INADDR_DNS_STUB
))
805 DnssecMode
dns_server_get_dnssec_mode(DnsServer
*s
) {
809 return link_get_dnssec_mode(s
->link
);
811 return manager_get_dnssec_mode(s
->manager
);
814 PrivateDnsMode
dns_server_get_private_dns_mode(DnsServer
*s
) {
818 return link_get_private_dns_mode(s
->link
);
820 return manager_get_private_dns_mode(s
->manager
);
823 void dns_server_flush_cache(DnsServer
*s
) {
829 /* Flush the cache of the scope this server belongs to */
831 current
= s
->link
? s
->link
->current_dns_server
: s
->manager
->current_dns_server
;
835 scope
= s
->link
? s
->link
->unicast_scope
: s
->manager
->unicast_scope
;
839 dns_cache_flush(&scope
->cache
);
842 void dns_server_reset_features(DnsServer
*s
) {
845 s
->verified_feature_level
= _DNS_SERVER_FEATURE_LEVEL_INVALID
;
846 s
->possible_feature_level
= DNS_SERVER_FEATURE_LEVEL_BEST
;
848 s
->received_udp_packet_max
= DNS_PACKET_UNICAST_SIZE_MAX
;
850 s
->packet_bad_opt
= false;
851 s
->packet_rrsig_missing
= false;
853 s
->features_grace_period_usec
= DNS_SERVER_FEATURE_GRACE_PERIOD_MIN_USEC
;
855 s
->warned_downgrade
= false;
857 dns_server_reset_counters(s
);
860 void dns_server_reset_features_all(DnsServer
*s
) {
863 LIST_FOREACH(servers
, i
, s
)
864 dns_server_reset_features(i
);
867 void dns_server_dump(DnsServer
*s
, FILE *f
) {
873 fputs("[Server ", f
);
874 fputs(dns_server_string(s
), f
);
876 fputs(dns_server_type_to_string(s
->type
), f
);
878 if (s
->type
== DNS_SERVER_LINK
) {
881 fputs(" interface=", f
);
882 fputs(s
->link
->name
, f
);
887 fputs("\tVerified feature level: ", f
);
888 fputs(strna(dns_server_feature_level_to_string(s
->verified_feature_level
)), f
);
891 fputs("\tPossible feature level: ", f
);
892 fputs(strna(dns_server_feature_level_to_string(s
->possible_feature_level
)), f
);
895 fputs("\tDNSSEC Mode: ", f
);
896 fputs(strna(dnssec_mode_to_string(dns_server_get_dnssec_mode(s
))), f
);
899 fputs("\tCan do DNSSEC: ", f
);
900 fputs(yes_no(dns_server_dnssec_supported(s
)), f
);
904 "\tMaximum UDP packet size received: %zu\n"
905 "\tFailed UDP attempts: %u\n"
906 "\tFailed TCP attempts: %u\n"
907 "\tSeen truncated packet: %s\n"
908 "\tSeen OPT RR getting lost: %s\n"
909 "\tSeen RRSIG RR missing: %s\n",
910 s
->received_udp_packet_max
,
913 yes_no(s
->packet_truncated
),
914 yes_no(s
->packet_bad_opt
),
915 yes_no(s
->packet_rrsig_missing
));
918 static const char* const dns_server_type_table
[_DNS_SERVER_TYPE_MAX
] = {
919 [DNS_SERVER_SYSTEM
] = "system",
920 [DNS_SERVER_FALLBACK
] = "fallback",
921 [DNS_SERVER_LINK
] = "link",
923 DEFINE_STRING_TABLE_LOOKUP(dns_server_type
, DnsServerType
);
925 static const char* const dns_server_feature_level_table
[_DNS_SERVER_FEATURE_LEVEL_MAX
] = {
926 [DNS_SERVER_FEATURE_LEVEL_TCP
] = "TCP",
927 [DNS_SERVER_FEATURE_LEVEL_UDP
] = "UDP",
928 [DNS_SERVER_FEATURE_LEVEL_EDNS0
] = "UDP+EDNS0",
929 [DNS_SERVER_FEATURE_LEVEL_TLS_PLAIN
] = "TLS+EDNS0",
930 [DNS_SERVER_FEATURE_LEVEL_DO
] = "UDP+EDNS0+DO",
931 [DNS_SERVER_FEATURE_LEVEL_LARGE
] = "UDP+EDNS0+DO+LARGE",
932 [DNS_SERVER_FEATURE_LEVEL_TLS_DO
] = "TLS+EDNS0+D0",
934 DEFINE_STRING_TABLE_LOOKUP(dns_server_feature_level
, DnsServerFeatureLevel
);