1 /* SPDX-License-Identifier: LGPL-2.1+ */
3 This file is part of systemd.
5 Copyright 2014 Lennart Poettering
8 #include <netinet/tcp.h>
11 #include "alloc-util.h"
12 #include "dns-domain.h"
14 #include "hostname-util.h"
16 #include "random-util.h"
17 #include "resolved-dnssd.h"
18 #include "resolved-dns-scope.h"
19 #include "resolved-dns-zone.h"
20 #include "resolved-llmnr.h"
21 #include "resolved-mdns.h"
22 #include "socket-util.h"
25 #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
26 #define MULTICAST_RATELIMIT_BURST 1000
28 /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */
29 #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC)
30 #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC)
32 int dns_scope_new(Manager
*m
, DnsScope
**ret
, Link
*l
, DnsProtocol protocol
, int family
) {
38 s
= new0(DnsScope
, 1);
44 s
->protocol
= protocol
;
46 s
->resend_timeout
= MULTICAST_RESEND_TIMEOUT_MIN_USEC
;
48 if (protocol
== DNS_PROTOCOL_DNS
) {
49 /* Copy DNSSEC mode from the link if it is set there,
50 * otherwise take the manager's DNSSEC mode. Note that
51 * we copy this only at scope creation time, and do
52 * not update it from the on, even if the setting
56 s
->dnssec_mode
= link_get_dnssec_mode(l
);
58 s
->dnssec_mode
= manager_get_dnssec_mode(m
);
60 s
->dnssec_mode
= DNSSEC_NO
;
62 LIST_PREPEND(scopes
, m
->dns_scopes
, s
);
64 dns_scope_llmnr_membership(s
, true);
65 dns_scope_mdns_membership(s
, true);
67 log_debug("New scope on link %s, protocol %s, family %s", l
? l
->name
: "*", dns_protocol_to_string(protocol
), family
== AF_UNSPEC
? "*" : af_to_name(family
));
69 /* Enforce ratelimiting for the multicast protocols */
70 RATELIMIT_INIT(s
->ratelimit
, MULTICAST_RATELIMIT_INTERVAL_USEC
, MULTICAST_RATELIMIT_BURST
);
76 static void dns_scope_abort_transactions(DnsScope
*s
) {
79 while (s
->transactions
) {
80 DnsTransaction
*t
= s
->transactions
;
82 /* Abort the transaction, but make sure it is not
83 * freed while we still look at it */
86 if (DNS_TRANSACTION_IS_LIVE(t
->state
))
87 dns_transaction_complete(t
, DNS_TRANSACTION_ABORTED
);
90 dns_transaction_free(t
);
94 DnsScope
* dns_scope_free(DnsScope
*s
) {
98 log_debug("Removing scope on link %s, protocol %s, family %s", s
->link
? s
->link
->name
: "*", dns_protocol_to_string(s
->protocol
), s
->family
== AF_UNSPEC
? "*" : af_to_name(s
->family
));
100 dns_scope_llmnr_membership(s
, false);
101 dns_scope_mdns_membership(s
, false);
102 dns_scope_abort_transactions(s
);
104 while (s
->query_candidates
)
105 dns_query_candidate_free(s
->query_candidates
);
107 hashmap_free(s
->transactions_by_key
);
109 ordered_hashmap_free_with_destructor(s
->conflict_queue
, dns_resource_record_unref
);
110 sd_event_source_unref(s
->conflict_event_source
);
112 sd_event_source_unref(s
->announce_event_source
);
114 dns_cache_flush(&s
->cache
);
115 dns_zone_flush(&s
->zone
);
117 LIST_REMOVE(scopes
, s
->manager
->dns_scopes
, s
);
121 DnsServer
*dns_scope_get_dns_server(DnsScope
*s
) {
124 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
128 return link_get_dns_server(s
->link
);
130 return manager_get_dns_server(s
->manager
);
133 unsigned dns_scope_get_n_dns_servers(DnsScope
*s
) {
139 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
143 i
= s
->link
->dns_servers
;
145 i
= s
->manager
->dns_servers
;
147 for (; i
; i
= i
->servers_next
)
153 void dns_scope_next_dns_server(DnsScope
*s
) {
156 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
160 link_next_dns_server(s
->link
);
162 manager_next_dns_server(s
->manager
);
165 void dns_scope_packet_received(DnsScope
*s
, usec_t rtt
) {
168 if (rtt
<= s
->max_rtt
)
172 s
->resend_timeout
= MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC
, s
->max_rtt
* 2), MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
175 void dns_scope_packet_lost(DnsScope
*s
, usec_t usec
) {
178 if (s
->resend_timeout
<= usec
)
179 s
->resend_timeout
= MIN(s
->resend_timeout
* 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
182 static int dns_scope_emit_one(DnsScope
*s
, int fd
, DnsPacket
*p
) {
183 union in_addr_union addr
;
190 assert(p
->protocol
== s
->protocol
);
194 ifindex
= s
->link
->ifindex
;
196 mtu
= manager_find_mtu(s
->manager
);
198 switch (s
->protocol
) {
200 case DNS_PROTOCOL_DNS
:
203 if (DNS_PACKET_QDCOUNT(p
) > 1)
206 if (p
->size
> DNS_PACKET_UNICAST_SIZE_MAX
)
209 if (p
->size
+ UDP_PACKET_HEADER_SIZE
> mtu
)
212 r
= manager_write(s
->manager
, fd
, p
);
218 case DNS_PROTOCOL_LLMNR
:
221 if (DNS_PACKET_QDCOUNT(p
) > 1)
224 if (!ratelimit_test(&s
->ratelimit
))
229 if (family
== AF_INET
) {
230 addr
.in
= LLMNR_MULTICAST_IPV4_ADDRESS
;
231 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
232 } else if (family
== AF_INET6
) {
233 addr
.in6
= LLMNR_MULTICAST_IPV6_ADDRESS
;
234 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
236 return -EAFNOSUPPORT
;
240 r
= manager_send(s
->manager
, fd
, ifindex
, family
, &addr
, LLMNR_PORT
, NULL
, p
);
246 case DNS_PROTOCOL_MDNS
:
249 if (!ratelimit_test(&s
->ratelimit
))
254 if (family
== AF_INET
) {
255 addr
.in
= MDNS_MULTICAST_IPV4_ADDRESS
;
256 fd
= manager_mdns_ipv4_fd(s
->manager
);
257 } else if (family
== AF_INET6
) {
258 addr
.in6
= MDNS_MULTICAST_IPV6_ADDRESS
;
259 fd
= manager_mdns_ipv6_fd(s
->manager
);
261 return -EAFNOSUPPORT
;
265 r
= manager_send(s
->manager
, fd
, ifindex
, family
, &addr
, MDNS_PORT
, NULL
, p
);
272 return -EAFNOSUPPORT
;
278 int dns_scope_emit_udp(DnsScope
*s
, int fd
, DnsPacket
*p
) {
283 assert(p
->protocol
== s
->protocol
);
284 assert((s
->protocol
== DNS_PROTOCOL_DNS
) == (fd
>= 0));
287 /* If there are multiple linked packets, set the TC bit in all but the last of them */
289 assert(p
->protocol
== DNS_PROTOCOL_MDNS
);
290 dns_packet_set_flags(p
, true, true);
293 r
= dns_scope_emit_one(s
, fd
, p
);
303 static int dns_scope_socket(
307 const union in_addr_union
*address
,
311 _cleanup_close_
int fd
= -1;
312 union sockaddr_union sa
= {};
314 static const int one
= 1;
320 assert(family
== AF_UNSPEC
);
323 ifindex
= dns_server_ifindex(server
);
325 sa
.sa
.sa_family
= server
->family
;
326 if (server
->family
== AF_INET
) {
327 sa
.in
.sin_port
= htobe16(port
);
328 sa
.in
.sin_addr
= server
->address
.in
;
329 salen
= sizeof(sa
.in
);
330 } else if (server
->family
== AF_INET6
) {
331 sa
.in6
.sin6_port
= htobe16(port
);
332 sa
.in6
.sin6_addr
= server
->address
.in6
;
333 sa
.in6
.sin6_scope_id
= ifindex
;
334 salen
= sizeof(sa
.in6
);
336 return -EAFNOSUPPORT
;
338 assert(family
!= AF_UNSPEC
);
341 sa
.sa
.sa_family
= family
;
342 ifindex
= s
->link
? s
->link
->ifindex
: 0;
344 if (family
== AF_INET
) {
345 sa
.in
.sin_port
= htobe16(port
);
346 sa
.in
.sin_addr
= address
->in
;
347 salen
= sizeof(sa
.in
);
348 } else if (family
== AF_INET6
) {
349 sa
.in6
.sin6_port
= htobe16(port
);
350 sa
.in6
.sin6_addr
= address
->in6
;
351 sa
.in6
.sin6_scope_id
= ifindex
;
352 salen
= sizeof(sa
.in6
);
354 return -EAFNOSUPPORT
;
357 fd
= socket(sa
.sa
.sa_family
, type
|SOCK_CLOEXEC
|SOCK_NONBLOCK
, 0);
361 if (type
== SOCK_STREAM
) {
362 r
= setsockopt(fd
, IPPROTO_TCP
, TCP_NODELAY
, &one
, sizeof(one
));
368 be32_t ifindex_be
= htobe32(ifindex
);
370 if (sa
.sa
.sa_family
== AF_INET
) {
371 r
= setsockopt(fd
, IPPROTO_IP
, IP_UNICAST_IF
, &ifindex_be
, sizeof(ifindex_be
));
374 } else if (sa
.sa
.sa_family
== AF_INET6
) {
375 r
= setsockopt(fd
, IPPROTO_IPV6
, IPV6_UNICAST_IF
, &ifindex_be
, sizeof(ifindex_be
));
381 if (s
->protocol
== DNS_PROTOCOL_LLMNR
) {
382 /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
384 if (sa
.sa
.sa_family
== AF_INET
) {
385 r
= setsockopt(fd
, IPPROTO_IP
, IP_TTL
, &one
, sizeof(one
));
388 } else if (sa
.sa
.sa_family
== AF_INET6
) {
389 r
= setsockopt(fd
, IPPROTO_IPV6
, IPV6_UNICAST_HOPS
, &one
, sizeof(one
));
395 r
= connect(fd
, &sa
.sa
, salen
);
396 if (r
< 0 && errno
!= EINPROGRESS
)
402 int dns_scope_socket_udp(DnsScope
*s
, DnsServer
*server
, uint16_t port
) {
403 return dns_scope_socket(s
, SOCK_DGRAM
, AF_UNSPEC
, NULL
, server
, port
);
406 int dns_scope_socket_tcp(DnsScope
*s
, int family
, const union in_addr_union
*address
, DnsServer
*server
, uint16_t port
) {
407 return dns_scope_socket(s
, SOCK_STREAM
, family
, address
, server
, port
);
410 DnsScopeMatch
dns_scope_good_domain(DnsScope
*s
, int ifindex
, uint64_t flags
, const char *domain
) {
416 /* Checks if the specified domain is something to look up on
417 * this scope. Note that this accepts non-qualified hostnames,
418 * i.e. those without any search path prefixed yet. */
420 if (ifindex
!= 0 && (!s
->link
|| s
->link
->ifindex
!= ifindex
))
423 if ((SD_RESOLVED_FLAGS_MAKE(s
->protocol
, s
->family
, 0) & flags
) == 0)
426 /* Never resolve any loopback hostname or IP address via DNS,
427 * LLMNR or mDNS. Instead, always rely on synthesized RRs for
429 if (is_localhost(domain
) ||
430 dns_name_endswith(domain
, "127.in-addr.arpa") > 0 ||
431 dns_name_equal(domain
, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
434 /* Never respond to some of the domains listed in RFC6303 */
435 if (dns_name_endswith(domain
, "0.in-addr.arpa") > 0 ||
436 dns_name_equal(domain
, "255.255.255.255.in-addr.arpa") > 0 ||
437 dns_name_equal(domain
, "0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0)
440 /* Never respond to some of the domains listed in RFC6761 */
441 if (dns_name_endswith(domain
, "invalid") > 0)
444 switch (s
->protocol
) {
446 case DNS_PROTOCOL_DNS
: {
447 DnsServer
*dns_server
;
449 /* Never route things to scopes that lack DNS servers */
450 dns_server
= dns_scope_get_dns_server(s
);
454 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
455 * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
456 * won't be considered anymore. */
457 LIST_FOREACH(domains
, d
, dns_scope_get_search_domains(s
))
458 if (dns_name_endswith(domain
, d
->name
) > 0)
459 return DNS_SCOPE_YES
;
461 /* If the DNS server has route-only domains, don't send other requests to it. This would be a privacy
462 * violation, will most probably fail anyway, and adds unnecessary load. */
463 if (dns_server_limited_domains(dns_server
))
466 /* Exclude link-local IP ranges */
467 if (dns_name_endswith(domain
, "254.169.in-addr.arpa") == 0 &&
468 dns_name_endswith(domain
, "8.e.f.ip6.arpa") == 0 &&
469 dns_name_endswith(domain
, "9.e.f.ip6.arpa") == 0 &&
470 dns_name_endswith(domain
, "a.e.f.ip6.arpa") == 0 &&
471 dns_name_endswith(domain
, "b.e.f.ip6.arpa") == 0 &&
472 /* If networks use .local in their private setups, they are supposed to also add .local to their search
473 * domains, which we already checked above. Otherwise, we consider .local specific to mDNS and won't
474 * send such queries ordinary DNS servers. */
475 dns_name_endswith(domain
, "local") == 0)
476 return DNS_SCOPE_MAYBE
;
481 case DNS_PROTOCOL_MDNS
:
482 if ((s
->family
== AF_INET
&& dns_name_endswith(domain
, "in-addr.arpa") > 0) ||
483 (s
->family
== AF_INET6
&& dns_name_endswith(domain
, "ip6.arpa") > 0) ||
484 (dns_name_endswith(domain
, "local") > 0 && /* only resolve names ending in .local via mDNS */
485 dns_name_equal(domain
, "local") == 0 && /* but not the single-label "local" name itself */
486 manager_is_own_hostname(s
->manager
, domain
) <= 0)) /* never resolve the local hostname via mDNS */
487 return DNS_SCOPE_MAYBE
;
491 case DNS_PROTOCOL_LLMNR
:
492 if ((s
->family
== AF_INET
&& dns_name_endswith(domain
, "in-addr.arpa") > 0) ||
493 (s
->family
== AF_INET6
&& dns_name_endswith(domain
, "ip6.arpa") > 0) ||
494 (dns_name_is_single_label(domain
) && /* only resolve single label names via LLMNR */
495 !is_gateway_hostname(domain
) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
496 manager_is_own_hostname(s
->manager
, domain
) <= 0)) /* never resolve the local hostname via LLMNR */
497 return DNS_SCOPE_MAYBE
;
502 assert_not_reached("Unknown scope protocol");
506 bool dns_scope_good_key(DnsScope
*s
, const DnsResourceKey
*key
) {
512 /* Check if it makes sense to resolve the specified key on
513 * this scope. Note that this call assumes as fully qualified
514 * name, i.e. the search suffixes already appended. */
516 if (key
->class != DNS_CLASS_IN
)
519 if (s
->protocol
== DNS_PROTOCOL_DNS
) {
521 /* On classic DNS, looking up non-address RRs is always
522 * fine. (Specifically, we want to permit looking up
523 * DNSKEY and DS records on the root and top-level
525 if (!dns_resource_key_is_address(key
))
528 /* However, we refuse to look up A and AAAA RRs on the
529 * root and single-label domains, under the assumption
530 * that those should be resolved via LLMNR or search
531 * path only, and should not be leaked onto the
533 return !(dns_name_is_single_label(dns_resource_key_name(key
)) ||
534 dns_name_is_root(dns_resource_key_name(key
)));
537 /* On mDNS and LLMNR, send A and AAAA queries only on the
538 * respective scopes */
540 key_family
= dns_type_to_af(key
->type
);
544 return key_family
== s
->family
;
547 static int dns_scope_multicast_membership(DnsScope
*s
, bool b
, struct in_addr in
, struct in6_addr in6
) {
553 if (s
->family
== AF_INET
) {
554 struct ip_mreqn mreqn
= {
556 .imr_ifindex
= s
->link
->ifindex
,
559 if (s
->protocol
== DNS_PROTOCOL_LLMNR
)
560 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
562 fd
= manager_mdns_ipv4_fd(s
->manager
);
567 /* Always first try to drop membership before we add
568 * one. This is necessary on some devices, such as
571 (void) setsockopt(fd
, IPPROTO_IP
, IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
));
573 if (setsockopt(fd
, IPPROTO_IP
, b
? IP_ADD_MEMBERSHIP
: IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
)) < 0)
576 } else if (s
->family
== AF_INET6
) {
577 struct ipv6_mreq mreq
= {
578 .ipv6mr_multiaddr
= in6
,
579 .ipv6mr_interface
= s
->link
->ifindex
,
582 if (s
->protocol
== DNS_PROTOCOL_LLMNR
)
583 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
585 fd
= manager_mdns_ipv6_fd(s
->manager
);
591 (void) setsockopt(fd
, IPPROTO_IPV6
, IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
));
593 if (setsockopt(fd
, IPPROTO_IPV6
, b
? IPV6_ADD_MEMBERSHIP
: IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
)) < 0)
596 return -EAFNOSUPPORT
;
601 int dns_scope_llmnr_membership(DnsScope
*s
, bool b
) {
604 if (s
->protocol
!= DNS_PROTOCOL_LLMNR
)
607 return dns_scope_multicast_membership(s
, b
, LLMNR_MULTICAST_IPV4_ADDRESS
, LLMNR_MULTICAST_IPV6_ADDRESS
);
610 int dns_scope_mdns_membership(DnsScope
*s
, bool b
) {
613 if (s
->protocol
!= DNS_PROTOCOL_MDNS
)
616 return dns_scope_multicast_membership(s
, b
, MDNS_MULTICAST_IPV4_ADDRESS
, MDNS_MULTICAST_IPV6_ADDRESS
);
619 int dns_scope_make_reply_packet(
629 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
635 if (dns_question_isempty(q
) &&
636 dns_answer_isempty(answer
) &&
637 dns_answer_isempty(soa
))
640 r
= dns_packet_new(&p
, s
->protocol
, 0, DNS_PACKET_SIZE_MAX
);
644 DNS_PACKET_HEADER(p
)->id
= id
;
645 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
656 r
= dns_packet_append_question(p
, q
);
659 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(dns_question_size(q
));
661 r
= dns_packet_append_answer(p
, answer
);
664 DNS_PACKET_HEADER(p
)->ancount
= htobe16(dns_answer_size(answer
));
666 r
= dns_packet_append_answer(p
, soa
);
669 DNS_PACKET_HEADER(p
)->arcount
= htobe16(dns_answer_size(soa
));
676 static void dns_scope_verify_conflicts(DnsScope
*s
, DnsPacket
*p
) {
677 DnsResourceRecord
*rr
;
683 DNS_QUESTION_FOREACH(key
, p
->question
)
684 dns_zone_verify_conflicts(&s
->zone
, key
);
686 DNS_ANSWER_FOREACH(rr
, p
->answer
)
687 dns_zone_verify_conflicts(&s
->zone
, rr
->key
);
690 void dns_scope_process_query(DnsScope
*s
, DnsStream
*stream
, DnsPacket
*p
) {
691 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
, *soa
= NULL
;
692 _cleanup_(dns_packet_unrefp
) DnsPacket
*reply
= NULL
;
693 DnsResourceKey
*key
= NULL
;
694 bool tentative
= false;
700 if (p
->protocol
!= DNS_PROTOCOL_LLMNR
)
703 if (p
->ipproto
== IPPROTO_UDP
) {
704 /* Don't accept UDP queries directed to anything but
705 * the LLMNR multicast addresses. See RFC 4795,
708 if (p
->family
== AF_INET
&& !in_addr_equal(AF_INET
, &p
->destination
, (union in_addr_union
*) &LLMNR_MULTICAST_IPV4_ADDRESS
))
711 if (p
->family
== AF_INET6
&& !in_addr_equal(AF_INET6
, &p
->destination
, (union in_addr_union
*) &LLMNR_MULTICAST_IPV6_ADDRESS
))
715 r
= dns_packet_extract(p
);
717 log_debug_errno(r
, "Failed to extract resource records from incoming packet: %m");
721 if (DNS_PACKET_LLMNR_C(p
)) {
722 /* Somebody notified us about a possible conflict */
723 dns_scope_verify_conflicts(s
, p
);
727 assert(dns_question_size(p
->question
) == 1);
728 key
= p
->question
->keys
[0];
730 r
= dns_zone_lookup(&s
->zone
, key
, 0, &answer
, &soa
, &tentative
);
732 log_debug_errno(r
, "Failed to lookup key: %m");
739 dns_answer_order_by_scope(answer
, in_addr_is_link_local(p
->family
, &p
->sender
) > 0);
741 r
= dns_scope_make_reply_packet(s
, DNS_PACKET_ID(p
), DNS_RCODE_SUCCESS
, p
->question
, answer
, soa
, tentative
, &reply
);
743 log_debug_errno(r
, "Failed to build reply packet: %m");
748 r
= dns_stream_write_packet(stream
, reply
);
750 log_debug_errno(r
, "Failed to enqueue reply packet: %m");
754 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
755 * will be dangling until the stream is disconnected, and the default completion handler of the stream
756 * will then unref the stream and destroy it */
757 if (DNS_STREAM_QUEUED(stream
))
758 dns_stream_ref(stream
);
762 if (!ratelimit_test(&s
->ratelimit
))
765 if (p
->family
== AF_INET
)
766 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
767 else if (p
->family
== AF_INET6
)
768 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
770 log_debug("Unknown protocol");
774 log_debug_errno(fd
, "Failed to get reply socket: %m");
778 /* Note that we always immediately reply to all LLMNR
779 * requests, and do not wait any time, since we
780 * verified uniqueness for all records. Also see RFC
781 * 4795, Section 2.7 */
783 r
= manager_send(s
->manager
, fd
, p
->ifindex
, p
->family
, &p
->sender
, p
->sender_port
, NULL
, reply
);
785 log_debug_errno(r
, "Failed to send reply packet: %m");
791 DnsTransaction
*dns_scope_find_transaction(DnsScope
*scope
, DnsResourceKey
*key
, bool cache_ok
) {
797 /* Try to find an ongoing transaction that is a equal to the
798 * specified question */
799 t
= hashmap_get(scope
->transactions_by_key
, key
);
803 /* Refuse reusing transactions that completed based on cached
804 * data instead of a real packet, if that's requested. */
806 IN_SET(t
->state
, DNS_TRANSACTION_SUCCESS
, DNS_TRANSACTION_RCODE_FAILURE
) &&
807 t
->answer_source
!= DNS_TRANSACTION_NETWORK
)
813 static int dns_scope_make_conflict_packet(
815 DnsResourceRecord
*rr
,
818 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
825 r
= dns_packet_new(&p
, s
->protocol
, 0, DNS_PACKET_SIZE_MAX
);
829 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
840 /* For mDNS, the transaction ID should always be 0 */
841 if (s
->protocol
!= DNS_PROTOCOL_MDNS
)
842 random_bytes(&DNS_PACKET_HEADER(p
)->id
, sizeof(uint16_t));
844 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
845 DNS_PACKET_HEADER(p
)->arcount
= htobe16(1);
847 r
= dns_packet_append_key(p
, rr
->key
, 0, NULL
);
851 r
= dns_packet_append_rr(p
, rr
, 0, NULL
, NULL
);
860 static int on_conflict_dispatch(sd_event_source
*es
, usec_t usec
, void *userdata
) {
861 DnsScope
*scope
= userdata
;
867 scope
->conflict_event_source
= sd_event_source_unref(scope
->conflict_event_source
);
870 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
871 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
872 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
874 key
= ordered_hashmap_first_key(scope
->conflict_queue
);
878 rr
= ordered_hashmap_remove(scope
->conflict_queue
, key
);
881 r
= dns_scope_make_conflict_packet(scope
, rr
, &p
);
883 log_error_errno(r
, "Failed to make conflict packet: %m");
887 r
= dns_scope_emit_udp(scope
, -1, p
);
889 log_debug_errno(r
, "Failed to send conflict packet: %m");
895 int dns_scope_notify_conflict(DnsScope
*scope
, DnsResourceRecord
*rr
) {
902 /* We don't send these queries immediately. Instead, we queue
903 * them, and send them after some jitter delay. */
904 r
= ordered_hashmap_ensure_allocated(&scope
->conflict_queue
, &dns_resource_key_hash_ops
);
910 /* We only place one RR per key in the conflict
911 * messages, not all of them. That should be enough to
912 * indicate where there might be a conflict */
913 r
= ordered_hashmap_put(scope
->conflict_queue
, rr
->key
, rr
);
914 if (IN_SET(r
, 0, -EEXIST
))
917 return log_debug_errno(r
, "Failed to queue conflicting RR: %m");
919 dns_resource_key_ref(rr
->key
);
920 dns_resource_record_ref(rr
);
922 if (scope
->conflict_event_source
)
925 random_bytes(&jitter
, sizeof(jitter
));
926 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
928 r
= sd_event_add_time(scope
->manager
->event
,
929 &scope
->conflict_event_source
,
930 clock_boottime_or_monotonic(),
931 now(clock_boottime_or_monotonic()) + jitter
,
932 LLMNR_JITTER_INTERVAL_USEC
,
933 on_conflict_dispatch
, scope
);
935 return log_debug_errno(r
, "Failed to add conflict dispatch event: %m");
937 (void) sd_event_source_set_description(scope
->conflict_event_source
, "scope-conflict");
942 void dns_scope_check_conflicts(DnsScope
*scope
, DnsPacket
*p
) {
943 DnsResourceRecord
*rr
;
949 if (!IN_SET(p
->protocol
, DNS_PROTOCOL_LLMNR
, DNS_PROTOCOL_MDNS
))
952 if (DNS_PACKET_RRCOUNT(p
) <= 0)
955 if (p
->protocol
== DNS_PROTOCOL_LLMNR
) {
956 if (DNS_PACKET_LLMNR_C(p
) != 0)
959 if (DNS_PACKET_LLMNR_T(p
) != 0)
963 if (manager_our_packet(scope
->manager
, p
))
966 r
= dns_packet_extract(p
);
968 log_debug_errno(r
, "Failed to extract packet: %m");
972 log_debug("Checking for conflicts...");
974 DNS_ANSWER_FOREACH(rr
, p
->answer
) {
975 /* No conflict if it is DNS-SD RR used for service enumeration. */
976 if (dns_resource_key_is_dnssd_ptr(rr
->key
))
979 /* Check for conflicts against the local zone. If we
980 * found one, we won't check any further */
981 r
= dns_zone_check_conflicts(&scope
->zone
, rr
);
985 /* Check for conflicts against the local cache. If so,
986 * send out an advisory query, to inform everybody */
987 r
= dns_cache_check_conflicts(&scope
->cache
, rr
, p
->family
, &p
->sender
);
991 dns_scope_notify_conflict(scope
, rr
);
995 void dns_scope_dump(DnsScope
*s
, FILE *f
) {
1001 fputs("[Scope protocol=", f
);
1002 fputs(dns_protocol_to_string(s
->protocol
), f
);
1005 fputs(" interface=", f
);
1006 fputs(s
->link
->name
, f
);
1009 if (s
->family
!= AF_UNSPEC
) {
1010 fputs(" family=", f
);
1011 fputs(af_to_name(s
->family
), f
);
1016 if (!dns_zone_is_empty(&s
->zone
)) {
1017 fputs("ZONE:\n", f
);
1018 dns_zone_dump(&s
->zone
, f
);
1021 if (!dns_cache_is_empty(&s
->cache
)) {
1022 fputs("CACHE:\n", f
);
1023 dns_cache_dump(&s
->cache
, f
);
1027 DnsSearchDomain
*dns_scope_get_search_domains(DnsScope
*s
) {
1030 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
1034 return s
->link
->search_domains
;
1036 return s
->manager
->search_domains
;
1039 bool dns_scope_name_needs_search_domain(DnsScope
*s
, const char *name
) {
1042 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
1045 return dns_name_is_single_label(name
);
1048 bool dns_scope_network_good(DnsScope
*s
) {
1049 /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1050 * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1051 * DNS scope we check whether there are any links that are up and have an address. */
1056 return manager_routable(s
->manager
, AF_UNSPEC
);
1059 int dns_scope_ifindex(DnsScope
*s
) {
1063 return s
->link
->ifindex
;
1068 static int on_announcement_timeout(sd_event_source
*s
, usec_t usec
, void *userdata
) {
1069 DnsScope
*scope
= userdata
;
1073 scope
->announce_event_source
= sd_event_source_unref(scope
->announce_event_source
);
1075 (void) dns_scope_announce(scope
, false);
1079 int dns_scope_announce(DnsScope
*scope
, bool goodbye
) {
1080 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
;
1081 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
1082 _cleanup_set_free_ Set
*types
= NULL
;
1093 if (scope
->protocol
!= DNS_PROTOCOL_MDNS
)
1096 /* Check if we're done with probing. */
1097 LIST_FOREACH(transactions_by_scope
, t
, scope
->transactions
)
1098 if (DNS_TRANSACTION_IS_LIVE(t
->state
))
1101 /* Check if there're services pending conflict resolution. */
1102 if (manager_next_dnssd_names(scope
->manager
))
1103 return 0; /* we reach this point only if changing hostname didn't help */
1105 /* Calculate answer's size. */
1106 HASHMAP_FOREACH(z
, scope
->zone
.by_key
, iterator
) {
1107 if (z
->state
!= DNS_ZONE_ITEM_ESTABLISHED
)
1110 if (z
->rr
->key
->type
== DNS_TYPE_PTR
&&
1111 !dns_zone_contains_name(&scope
->zone
, z
->rr
->ptr
.name
)) {
1112 char key_str
[DNS_RESOURCE_KEY_STRING_MAX
];
1114 log_debug("Skip PTR RR <%s> since its counterparts seem to be withdrawn", dns_resource_key_to_string(z
->rr
->key
, key_str
, sizeof key_str
));
1115 z
->state
= DNS_ZONE_ITEM_WITHDRAWN
;
1119 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1120 if (!scope
->announced
&&
1121 dns_resource_key_is_dnssd_ptr(z
->rr
->key
)) {
1122 if (!set_contains(types
, dns_resource_key_name(z
->rr
->key
))) {
1123 r
= set_ensure_allocated(&types
, &dns_name_hash_ops
);
1125 return log_debug_errno(r
, "Failed to allocate set: %m");
1127 r
= set_put(types
, dns_resource_key_name(z
->rr
->key
));
1129 return log_debug_errno(r
, "Failed to add item to set: %m");
1133 LIST_FOREACH(by_key
, i
, z
)
1137 answer
= dns_answer_new(size
+ set_size(types
));
1141 /* Second iteration, actually add RRs to the answer. */
1142 HASHMAP_FOREACH(z
, scope
->zone
.by_key
, iterator
)
1143 LIST_FOREACH (by_key
, i
, z
) {
1144 DnsAnswerFlags flags
;
1146 if (i
->state
!= DNS_ZONE_ITEM_ESTABLISHED
)
1149 if (dns_resource_key_is_dnssd_ptr(i
->rr
->key
))
1150 flags
= goodbye
? DNS_ANSWER_GOODBYE
: 0;
1152 flags
= goodbye
? (DNS_ANSWER_GOODBYE
|DNS_ANSWER_CACHE_FLUSH
) : DNS_ANSWER_CACHE_FLUSH
;
1154 r
= dns_answer_add(answer
, i
->rr
, 0 , flags
);
1156 return log_debug_errno(r
, "Failed to add RR to announce: %m");
1159 /* Since all the active services are in the zone make them discoverable now. */
1160 SET_FOREACH(service_type
, types
, iterator
) {
1161 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
;
1163 rr
= dns_resource_record_new_full(DNS_CLASS_IN
, DNS_TYPE_PTR
,
1164 "_services._dns-sd._udp.local");
1165 rr
->ptr
.name
= strdup(service_type
);
1166 rr
->ttl
= MDNS_DEFAULT_TTL
;
1168 r
= dns_zone_put(&scope
->zone
, scope
, rr
, false);
1170 log_warning_errno(r
, "Failed to add DNS-SD PTR record to MDNS zone: %m");
1172 r
= dns_answer_add(answer
, rr
, 0 , 0);
1174 return log_debug_errno(r
, "Failed to add RR to announce: %m");
1177 if (dns_answer_isempty(answer
))
1180 r
= dns_scope_make_reply_packet(scope
, 0, DNS_RCODE_SUCCESS
, NULL
, answer
, NULL
, false, &p
);
1182 return log_debug_errno(r
, "Failed to build reply packet: %m");
1184 r
= dns_scope_emit_udp(scope
, -1, p
);
1186 return log_debug_errno(r
, "Failed to send reply packet: %m");
1188 /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1189 * responses, one second apart." */
1190 if (!scope
->announced
) {
1193 scope
->announced
= true;
1195 assert_se(sd_event_now(scope
->manager
->event
, clock_boottime_or_monotonic(), &ts
) >= 0);
1196 ts
+= MDNS_ANNOUNCE_DELAY
;
1198 r
= sd_event_add_time(
1199 scope
->manager
->event
,
1200 &scope
->announce_event_source
,
1201 clock_boottime_or_monotonic(),
1203 MDNS_JITTER_RANGE_USEC
,
1204 on_announcement_timeout
, scope
);
1206 return log_debug_errno(r
, "Failed to schedule second announcement: %m");
1208 (void) sd_event_source_set_description(scope
->announce_event_source
, "mdns-announce");
1214 int dns_scope_add_dnssd_services(DnsScope
*scope
) {
1216 DnssdService
*service
;
1217 DnssdTxtData
*txt_data
;
1222 if (hashmap_size(scope
->manager
->dnssd_services
) == 0)
1225 scope
->announced
= false;
1227 HASHMAP_FOREACH(service
, scope
->manager
->dnssd_services
, i
) {
1228 service
->withdrawn
= false;
1230 r
= dns_zone_put(&scope
->zone
, scope
, service
->ptr_rr
, false);
1232 log_warning_errno(r
, "Failed to add PTR record to MDNS zone: %m");
1234 r
= dns_zone_put(&scope
->zone
, scope
, service
->srv_rr
, true);
1236 log_warning_errno(r
, "Failed to add SRV record to MDNS zone: %m");
1238 LIST_FOREACH(items
, txt_data
, service
->txt_data_items
) {
1239 r
= dns_zone_put(&scope
->zone
, scope
, txt_data
->rr
, true);
1241 log_warning_errno(r
, "Failed to add TXT record to MDNS zone: %m");
1248 int dns_scope_remove_dnssd_services(DnsScope
*scope
) {
1249 _cleanup_(dns_resource_key_unrefp
) DnsResourceKey
*key
= NULL
;
1251 DnssdService
*service
;
1252 DnssdTxtData
*txt_data
;
1257 key
= dns_resource_key_new(DNS_CLASS_IN
, DNS_TYPE_PTR
,
1258 "_services._dns-sd._udp.local");
1262 r
= dns_zone_remove_rrs_by_key(&scope
->zone
, key
);
1266 HASHMAP_FOREACH(service
, scope
->manager
->dnssd_services
, i
) {
1267 dns_zone_remove_rr(&scope
->zone
, service
->ptr_rr
);
1268 dns_zone_remove_rr(&scope
->zone
, service
->srv_rr
);
1269 LIST_FOREACH(items
, txt_data
, service
->txt_data_items
)
1270 dns_zone_remove_rr(&scope
->zone
, txt_data
->rr
);