1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2014 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 #include <netinet/tcp.h>
26 #include "socket-util.h"
28 #include "random-util.h"
29 #include "hostname-util.h"
30 #include "dns-domain.h"
31 #include "resolved-llmnr.h"
32 #include "resolved-dns-scope.h"
34 #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
35 #define MULTICAST_RATELIMIT_BURST 1000
37 /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */
38 #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC)
39 #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC)
41 int dns_scope_new(Manager
*m
, DnsScope
**ret
, Link
*l
, DnsProtocol protocol
, int family
) {
47 s
= new0(DnsScope
, 1);
53 s
->protocol
= protocol
;
55 s
->resend_timeout
= MULTICAST_RESEND_TIMEOUT_MIN_USEC
;
57 LIST_PREPEND(scopes
, m
->dns_scopes
, s
);
59 dns_scope_llmnr_membership(s
, true);
61 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
));
63 /* Enforce ratelimiting for the multicast protocols */
64 RATELIMIT_INIT(s
->ratelimit
, MULTICAST_RATELIMIT_INTERVAL_USEC
, MULTICAST_RATELIMIT_BURST
);
70 DnsScope
* dns_scope_free(DnsScope
*s
) {
72 DnsResourceRecord
*rr
;
77 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
));
79 dns_scope_llmnr_membership(s
, false);
81 while ((t
= s
->transactions
)) {
83 /* Abort the transaction, but make sure it is not
84 * freed while we still look at it */
87 dns_transaction_complete(t
, DNS_TRANSACTION_ABORTED
);
90 dns_transaction_free(t
);
93 while ((rr
= ordered_hashmap_steal_first(s
->conflict_queue
)))
94 dns_resource_record_unref(rr
);
96 ordered_hashmap_free(s
->conflict_queue
);
97 sd_event_source_unref(s
->conflict_event_source
);
99 dns_cache_flush(&s
->cache
);
100 dns_zone_flush(&s
->zone
);
102 LIST_REMOVE(scopes
, s
->manager
->dns_scopes
, s
);
103 strv_free(s
->domains
);
109 DnsServer
*dns_scope_get_dns_server(DnsScope
*s
) {
112 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
116 return link_get_dns_server(s
->link
);
118 return manager_get_dns_server(s
->manager
);
121 void dns_scope_next_dns_server(DnsScope
*s
) {
124 if (s
->protocol
!= DNS_PROTOCOL_DNS
)
128 link_next_dns_server(s
->link
);
130 manager_next_dns_server(s
->manager
);
133 void dns_scope_packet_received(DnsScope
*s
, usec_t rtt
) {
136 if (rtt
> s
->max_rtt
) {
138 s
->resend_timeout
= MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC
, s
->max_rtt
* 2),
139 MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
143 void dns_scope_packet_lost(DnsScope
*s
, usec_t usec
) {
146 if (s
->resend_timeout
<= usec
)
147 s
->resend_timeout
= MIN(s
->resend_timeout
* 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC
);
150 int dns_scope_emit(DnsScope
*s
, int fd
, DnsPacket
*p
) {
151 union in_addr_union addr
;
159 assert(p
->protocol
== s
->protocol
);
160 assert((s
->protocol
== DNS_PROTOCOL_DNS
) != (fd
< 0));
164 ifindex
= s
->link
->ifindex
;
166 mtu
= manager_find_mtu(s
->manager
);
168 if (s
->protocol
== DNS_PROTOCOL_DNS
) {
169 if (DNS_PACKET_QDCOUNT(p
) > 1)
172 if (p
->size
> DNS_PACKET_UNICAST_SIZE_MAX
)
175 if (p
->size
+ UDP_PACKET_HEADER_SIZE
> mtu
)
178 r
= manager_write(s
->manager
, fd
, p
);
182 } else if (s
->protocol
== DNS_PROTOCOL_LLMNR
) {
184 if (DNS_PACKET_QDCOUNT(p
) > 1)
187 if (!ratelimit_test(&s
->ratelimit
))
193 if (family
== AF_INET
) {
194 addr
.in
= LLMNR_MULTICAST_IPV4_ADDRESS
;
195 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
196 } else if (family
== AF_INET6
) {
197 addr
.in6
= LLMNR_MULTICAST_IPV6_ADDRESS
;
198 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
200 return -EAFNOSUPPORT
;
204 r
= manager_send(s
->manager
, fd
, ifindex
, family
, &addr
, port
, p
);
208 return -EAFNOSUPPORT
;
213 static int dns_scope_socket(DnsScope
*s
, int type
, int family
, const union in_addr_union
*address
, uint16_t port
, DnsServer
**server
) {
214 DnsServer
*srv
= NULL
;
215 _cleanup_close_
int fd
= -1;
216 union sockaddr_union sa
= {};
218 static const int one
= 1;
222 assert((family
== AF_UNSPEC
) == !address
);
224 if (family
== AF_UNSPEC
) {
225 srv
= dns_scope_get_dns_server(s
);
229 sa
.sa
.sa_family
= srv
->family
;
230 if (srv
->family
== AF_INET
) {
231 sa
.in
.sin_port
= htobe16(port
);
232 sa
.in
.sin_addr
= srv
->address
.in
;
233 salen
= sizeof(sa
.in
);
234 } else if (srv
->family
== AF_INET6
) {
235 sa
.in6
.sin6_port
= htobe16(port
);
236 sa
.in6
.sin6_addr
= srv
->address
.in6
;
237 sa
.in6
.sin6_scope_id
= s
->link
? s
->link
->ifindex
: 0;
238 salen
= sizeof(sa
.in6
);
240 return -EAFNOSUPPORT
;
242 sa
.sa
.sa_family
= family
;
244 if (family
== AF_INET
) {
245 sa
.in
.sin_port
= htobe16(port
);
246 sa
.in
.sin_addr
= address
->in
;
247 salen
= sizeof(sa
.in
);
248 } else if (family
== AF_INET6
) {
249 sa
.in6
.sin6_port
= htobe16(port
);
250 sa
.in6
.sin6_addr
= address
->in6
;
251 sa
.in6
.sin6_scope_id
= s
->link
? s
->link
->ifindex
: 0;
252 salen
= sizeof(sa
.in6
);
254 return -EAFNOSUPPORT
;
257 fd
= socket(sa
.sa
.sa_family
, type
|SOCK_CLOEXEC
|SOCK_NONBLOCK
, 0);
261 if (type
== SOCK_STREAM
) {
262 r
= setsockopt(fd
, IPPROTO_TCP
, TCP_NODELAY
, &one
, sizeof(one
));
268 uint32_t ifindex
= htobe32(s
->link
->ifindex
);
270 if (sa
.sa
.sa_family
== AF_INET
) {
271 r
= setsockopt(fd
, IPPROTO_IP
, IP_UNICAST_IF
, &ifindex
, sizeof(ifindex
));
274 } else if (sa
.sa
.sa_family
== AF_INET6
) {
275 r
= setsockopt(fd
, IPPROTO_IPV6
, IPV6_UNICAST_IF
, &ifindex
, sizeof(ifindex
));
281 if (s
->protocol
== DNS_PROTOCOL_LLMNR
) {
282 /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
284 if (sa
.sa
.sa_family
== AF_INET
) {
285 r
= setsockopt(fd
, IPPROTO_IP
, IP_TTL
, &one
, sizeof(one
));
288 } else if (sa
.sa
.sa_family
== AF_INET6
) {
289 r
= setsockopt(fd
, IPPROTO_IPV6
, IPV6_UNICAST_HOPS
, &one
, sizeof(one
));
295 r
= connect(fd
, &sa
.sa
, salen
);
296 if (r
< 0 && errno
!= EINPROGRESS
)
308 int dns_scope_udp_dns_socket(DnsScope
*s
, DnsServer
**server
) {
309 return dns_scope_socket(s
, SOCK_DGRAM
, AF_UNSPEC
, NULL
, 53, server
);
312 int dns_scope_tcp_socket(DnsScope
*s
, int family
, const union in_addr_union
*address
, uint16_t port
, DnsServer
**server
) {
313 return dns_scope_socket(s
, SOCK_STREAM
, family
, address
, port
, server
);
316 DnsScopeMatch
dns_scope_good_domain(DnsScope
*s
, int ifindex
, uint64_t flags
, const char *domain
) {
322 if (ifindex
!= 0 && (!s
->link
|| s
->link
->ifindex
!= ifindex
))
325 if ((SD_RESOLVED_FLAGS_MAKE(s
->protocol
, s
->family
) & flags
) == 0)
328 STRV_FOREACH(i
, s
->domains
)
329 if (dns_name_endswith(domain
, *i
) > 0)
330 return DNS_SCOPE_YES
;
332 if (dns_name_root(domain
) != 0)
335 if (is_localhost(domain
))
338 /* Never resolve any loopback IP address via DNS, LLMNR or mDNS */
339 if (dns_name_endswith(domain
, "127.in-addr.arpa") > 0 ||
340 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)
343 if (s
->protocol
== DNS_PROTOCOL_DNS
) {
344 if (dns_name_endswith(domain
, "254.169.in-addr.arpa") == 0 &&
345 dns_name_endswith(domain
, "0.8.e.f.ip6.arpa") == 0 &&
346 dns_name_single_label(domain
) == 0)
347 return DNS_SCOPE_MAYBE
;
352 if (s
->protocol
== DNS_PROTOCOL_MDNS
) {
353 if (dns_name_endswith(domain
, "254.169.in-addr.arpa") > 0 ||
354 dns_name_endswith(domain
, "0.8.e.f.ip6.arpa") > 0 ||
355 (dns_name_endswith(domain
, "local") > 0 && dns_name_equal(domain
, "local") == 0))
356 return DNS_SCOPE_MAYBE
;
361 if (s
->protocol
== DNS_PROTOCOL_LLMNR
) {
362 if (dns_name_endswith(domain
, "in-addr.arpa") > 0 ||
363 dns_name_endswith(domain
, "ip6.arpa") > 0 ||
364 (dns_name_single_label(domain
) > 0 &&
365 dns_name_equal(domain
, "gateway") <= 0)) /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
366 return DNS_SCOPE_MAYBE
;
371 assert_not_reached("Unknown scope protocol");
374 int dns_scope_good_key(DnsScope
*s
, DnsResourceKey
*key
) {
378 if (s
->protocol
== DNS_PROTOCOL_DNS
)
381 /* On mDNS and LLMNR, send A and AAAA queries only on the
382 * respective scopes */
384 if (s
->family
== AF_INET
&& key
->class == DNS_CLASS_IN
&& key
->type
== DNS_TYPE_AAAA
)
387 if (s
->family
== AF_INET6
&& key
->class == DNS_CLASS_IN
&& key
->type
== DNS_TYPE_A
)
393 int dns_scope_llmnr_membership(DnsScope
*s
, bool b
) {
398 if (s
->protocol
!= DNS_PROTOCOL_LLMNR
)
403 if (s
->family
== AF_INET
) {
404 struct ip_mreqn mreqn
= {
405 .imr_multiaddr
= LLMNR_MULTICAST_IPV4_ADDRESS
,
406 .imr_ifindex
= s
->link
->ifindex
,
409 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
413 /* Always first try to drop membership before we add
414 * one. This is necessary on some devices, such as
417 (void) setsockopt(fd
, IPPROTO_IP
, IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
));
419 if (setsockopt(fd
, IPPROTO_IP
, b
? IP_ADD_MEMBERSHIP
: IP_DROP_MEMBERSHIP
, &mreqn
, sizeof(mreqn
)) < 0)
422 } else if (s
->family
== AF_INET6
) {
423 struct ipv6_mreq mreq
= {
424 .ipv6mr_multiaddr
= LLMNR_MULTICAST_IPV6_ADDRESS
,
425 .ipv6mr_interface
= s
->link
->ifindex
,
428 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
433 (void) setsockopt(fd
, IPPROTO_IPV6
, IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
));
435 if (setsockopt(fd
, IPPROTO_IPV6
, b
? IPV6_ADD_MEMBERSHIP
: IPV6_DROP_MEMBERSHIP
, &mreq
, sizeof(mreq
)) < 0)
438 return -EAFNOSUPPORT
;
443 static int dns_scope_make_reply_packet(
453 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
460 if ((!q
|| q
->n_keys
<= 0)
461 && (!answer
|| answer
->n_rrs
<= 0)
462 && (!soa
|| soa
->n_rrs
<= 0))
465 r
= dns_packet_new(&p
, s
->protocol
, 0);
469 DNS_PACKET_HEADER(p
)->id
= id
;
470 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
482 for (i
= 0; i
< q
->n_keys
; i
++) {
483 r
= dns_packet_append_key(p
, q
->keys
[i
], NULL
);
488 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(q
->n_keys
);
492 for (i
= 0; i
< answer
->n_rrs
; i
++) {
493 r
= dns_packet_append_rr(p
, answer
->rrs
[i
], NULL
);
498 DNS_PACKET_HEADER(p
)->ancount
= htobe16(answer
->n_rrs
);
502 for (i
= 0; i
< soa
->n_rrs
; i
++) {
503 r
= dns_packet_append_rr(p
, soa
->rrs
[i
], NULL
);
508 DNS_PACKET_HEADER(p
)->arcount
= htobe16(soa
->n_rrs
);
517 static void dns_scope_verify_conflicts(DnsScope
*s
, DnsPacket
*p
) {
524 for (n
= 0; n
< p
->question
->n_keys
; n
++)
525 dns_zone_verify_conflicts(&s
->zone
, p
->question
->keys
[n
]);
527 for (n
= 0; n
< p
->answer
->n_rrs
; n
++)
528 dns_zone_verify_conflicts(&s
->zone
, p
->answer
->rrs
[n
]->key
);
531 void dns_scope_process_query(DnsScope
*s
, DnsStream
*stream
, DnsPacket
*p
) {
532 _cleanup_(dns_packet_unrefp
) DnsPacket
*reply
= NULL
;
533 _cleanup_(dns_answer_unrefp
) DnsAnswer
*answer
= NULL
, *soa
= NULL
;
534 bool tentative
= false;
540 if (p
->protocol
!= DNS_PROTOCOL_LLMNR
)
543 if (p
->ipproto
== IPPROTO_UDP
) {
544 /* Don't accept UDP queries directed to anything but
545 * the LLMNR multicast addresses. See RFC 4795,
548 if (p
->family
== AF_INET
&& !in_addr_equal(AF_INET
, &p
->destination
, (union in_addr_union
*) &LLMNR_MULTICAST_IPV4_ADDRESS
))
551 if (p
->family
== AF_INET6
&& !in_addr_equal(AF_INET6
, &p
->destination
, (union in_addr_union
*) &LLMNR_MULTICAST_IPV6_ADDRESS
))
555 r
= dns_packet_extract(p
);
557 log_debug_errno(r
, "Failed to extract resources from incoming packet: %m");
561 if (DNS_PACKET_LLMNR_C(p
)) {
562 /* Somebody notified us about a possible conflict */
563 dns_scope_verify_conflicts(s
, p
);
567 r
= dns_zone_lookup(&s
->zone
, p
->question
, &answer
, &soa
, &tentative
);
569 log_debug_errno(r
, "Failed to lookup key: %m");
576 dns_answer_order_by_scope(answer
, in_addr_is_link_local(p
->family
, &p
->sender
) > 0);
578 r
= dns_scope_make_reply_packet(s
, DNS_PACKET_ID(p
), DNS_RCODE_SUCCESS
, p
->question
, answer
, soa
, tentative
, &reply
);
580 log_debug_errno(r
, "Failed to build reply packet: %m");
585 r
= dns_stream_write_packet(stream
, reply
);
587 if (!ratelimit_test(&s
->ratelimit
))
590 if (p
->family
== AF_INET
)
591 fd
= manager_llmnr_ipv4_udp_fd(s
->manager
);
592 else if (p
->family
== AF_INET6
)
593 fd
= manager_llmnr_ipv6_udp_fd(s
->manager
);
595 log_debug("Unknown protocol");
599 log_debug_errno(fd
, "Failed to get reply socket: %m");
603 /* Note that we always immediately reply to all LLMNR
604 * requests, and do not wait any time, since we
605 * verified uniqueness for all records. Also see RFC
606 * 4795, Section 2.7 */
608 r
= manager_send(s
->manager
, fd
, p
->ifindex
, p
->family
, &p
->sender
, p
->sender_port
, reply
);
612 log_debug_errno(r
, "Failed to send reply packet: %m");
617 DnsTransaction
*dns_scope_find_transaction(DnsScope
*scope
, DnsQuestion
*question
, bool cache_ok
) {
623 /* Try to find an ongoing transaction that is a equal or a
624 * superset of the specified question */
626 LIST_FOREACH(transactions_by_scope
, t
, scope
->transactions
) {
628 /* Refuse reusing transactions that completed based on
629 * cached data instead of a real packet, if that's
632 IN_SET(t
->state
, DNS_TRANSACTION_SUCCESS
, DNS_TRANSACTION_FAILURE
) &&
636 if (dns_question_is_superset(t
->question
, question
) > 0)
643 static int dns_scope_make_conflict_packet(
645 DnsResourceRecord
*rr
,
648 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
655 r
= dns_packet_new(&p
, s
->protocol
, 0);
659 DNS_PACKET_HEADER(p
)->flags
= htobe16(DNS_PACKET_MAKE_FLAGS(
669 random_bytes(&DNS_PACKET_HEADER(p
)->id
, sizeof(uint16_t));
670 DNS_PACKET_HEADER(p
)->qdcount
= htobe16(1);
671 DNS_PACKET_HEADER(p
)->arcount
= htobe16(1);
673 r
= dns_packet_append_key(p
, rr
->key
, NULL
);
677 r
= dns_packet_append_rr(p
, rr
, NULL
);
687 static int on_conflict_dispatch(sd_event_source
*es
, usec_t usec
, void *userdata
) {
688 DnsScope
*scope
= userdata
;
694 scope
->conflict_event_source
= sd_event_source_unref(scope
->conflict_event_source
);
697 _cleanup_(dns_resource_record_unrefp
) DnsResourceRecord
*rr
= NULL
;
698 _cleanup_(dns_packet_unrefp
) DnsPacket
*p
= NULL
;
700 rr
= ordered_hashmap_steal_first(scope
->conflict_queue
);
704 r
= dns_scope_make_conflict_packet(scope
, rr
, &p
);
706 log_error_errno(r
, "Failed to make conflict packet: %m");
710 r
= dns_scope_emit(scope
, -1, p
);
712 log_debug_errno(r
, "Failed to send conflict packet: %m");
718 int dns_scope_notify_conflict(DnsScope
*scope
, DnsResourceRecord
*rr
) {
725 /* We don't send these queries immediately. Instead, we queue
726 * them, and send them after some jitter delay. */
727 r
= ordered_hashmap_ensure_allocated(&scope
->conflict_queue
, &dns_resource_key_hash_ops
);
733 /* We only place one RR per key in the conflict
734 * messages, not all of them. That should be enough to
735 * indicate where there might be a conflict */
736 r
= ordered_hashmap_put(scope
->conflict_queue
, rr
->key
, rr
);
737 if (r
== -EEXIST
|| r
== 0)
740 return log_debug_errno(r
, "Failed to queue conflicting RR: %m");
742 dns_resource_record_ref(rr
);
744 if (scope
->conflict_event_source
)
747 random_bytes(&jitter
, sizeof(jitter
));
748 jitter
%= LLMNR_JITTER_INTERVAL_USEC
;
750 r
= sd_event_add_time(scope
->manager
->event
,
751 &scope
->conflict_event_source
,
752 clock_boottime_or_monotonic(),
753 now(clock_boottime_or_monotonic()) + jitter
,
754 LLMNR_JITTER_INTERVAL_USEC
,
755 on_conflict_dispatch
, scope
);
757 return log_debug_errno(r
, "Failed to add conflict dispatch event: %m");
762 void dns_scope_check_conflicts(DnsScope
*scope
, DnsPacket
*p
) {
769 if (p
->protocol
!= DNS_PROTOCOL_LLMNR
)
772 if (DNS_PACKET_RRCOUNT(p
) <= 0)
775 if (DNS_PACKET_LLMNR_C(p
) != 0)
778 if (DNS_PACKET_LLMNR_T(p
) != 0)
781 if (manager_our_packet(scope
->manager
, p
))
784 r
= dns_packet_extract(p
);
786 log_debug_errno(r
, "Failed to extract packet: %m");
790 log_debug("Checking for conflicts...");
792 for (i
= 0; i
< p
->answer
->n_rrs
; i
++) {
794 /* Check for conflicts against the local zone. If we
795 * found one, we won't check any further */
796 r
= dns_zone_check_conflicts(&scope
->zone
, p
->answer
->rrs
[i
]);
800 /* Check for conflicts against the local cache. If so,
801 * send out an advisory query, to inform everybody */
802 r
= dns_cache_check_conflicts(&scope
->cache
, p
->answer
->rrs
[i
], p
->family
, &p
->sender
);
806 dns_scope_notify_conflict(scope
, p
->answer
->rrs
[i
]);