]> git.ipfire.org Git - thirdparty/systemd.git/blob - src/resolve/resolved-dns-scope.c
projects / thirdparty / systemd.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
resolve: fix no mDNS announcement after probing
[thirdparty/systemd.git] / src / resolve / resolved-dns-scope.c
1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
2
3 #include <netinet/tcp.h>
4
5 #include "af-list.h"
6 #include "alloc-util.h"
7 #include "dns-domain.h"
8 #include "errno-util.h"
9 #include "fd-util.h"
10 #include "hostname-util.h"
11 #include "missing_network.h"
12 #include "random-util.h"
13 #include "resolved-dnssd.h"
14 #include "resolved-dns-scope.h"
15 #include "resolved-dns-zone.h"
16 #include "resolved-llmnr.h"
17 #include "resolved-mdns.h"
18 #include "socket-util.h"
19 #include "strv.h"
20
21 #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
22 #define MULTICAST_RATELIMIT_BURST 1000
23
24 /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */
25 #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC)
26 #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC)
27
28 int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) {
29 DnsScope *s;
30
31 assert(m);
32 assert(ret);
33
34 s = new(DnsScope, 1);
35 if (!s)
36 return -ENOMEM;
37
38 *s = (DnsScope) {
39 .manager = m,
40 .link = l,
41 .protocol = protocol,
42 .family = family,
43 .resend_timeout = MULTICAST_RESEND_TIMEOUT_MIN_USEC,
44 };
45
46 if (protocol == DNS_PROTOCOL_DNS) {
47 /* Copy DNSSEC mode from the link if it is set there,
48 * otherwise take the manager's DNSSEC mode. Note that
49 * we copy this only at scope creation time, and do
50 * not update it from the on, even if the setting
51 * changes. */
52
53 if (l) {
54 s->dnssec_mode = link_get_dnssec_mode(l);
55 s->dns_over_tls_mode = link_get_dns_over_tls_mode(l);
56 } else {
57 s->dnssec_mode = manager_get_dnssec_mode(m);
58 s->dns_over_tls_mode = manager_get_dns_over_tls_mode(m);
59 }
60
61 } else {
62 s->dnssec_mode = DNSSEC_NO;
63 s->dns_over_tls_mode = DNS_OVER_TLS_NO;
64 }
65
66 LIST_PREPEND(scopes, m->dns_scopes, s);
67
68 dns_scope_llmnr_membership(s, true);
69 dns_scope_mdns_membership(s, true);
70
71 log_debug("New scope on link %s, protocol %s, family %s", l ? l->ifname : "*", dns_protocol_to_string(protocol), family == AF_UNSPEC ? "*" : af_to_name(family));
72
73 /* Enforce ratelimiting for the multicast protocols */
74 s->ratelimit = (const RateLimit) { MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST };
75
76 *ret = s;
77 return 0;
78 }
79
80 static void dns_scope_abort_transactions(DnsScope *s) {
81 assert(s);
82
83 while (s->transactions) {
84 DnsTransaction *t = s->transactions;
85
86 /* Abort the transaction, but make sure it is not
87 * freed while we still look at it */
88
89 t->block_gc++;
90 if (DNS_TRANSACTION_IS_LIVE(t->state))
91 dns_transaction_complete(t, DNS_TRANSACTION_ABORTED);
92 t->block_gc--;
93
94 dns_transaction_free(t);
95 }
96 }
97
98 DnsScope* dns_scope_free(DnsScope *s) {
99 if (!s)
100 return NULL;
101
102 log_debug("Removing scope on link %s, protocol %s, family %s", s->link ? s->link->ifname : "*", dns_protocol_to_string(s->protocol), s->family == AF_UNSPEC ? "*" : af_to_name(s->family));
103
104 dns_scope_llmnr_membership(s, false);
105 dns_scope_mdns_membership(s, false);
106 dns_scope_abort_transactions(s);
107
108 while (s->query_candidates)
109 dns_query_candidate_unref(s->query_candidates);
110
111 hashmap_free(s->transactions_by_key);
112
113 ordered_hashmap_free_with_destructor(s->conflict_queue, dns_resource_record_unref);
114 sd_event_source_disable_unref(s->conflict_event_source);
115
116 sd_event_source_disable_unref(s->announce_event_source);
117
118 dns_cache_flush(&s->cache);
119 dns_zone_flush(&s->zone);
120
121 LIST_REMOVE(scopes, s->manager->dns_scopes, s);
122 return mfree(s);
123 }
124
125 DnsServer *dns_scope_get_dns_server(DnsScope *s) {
126 assert(s);
127
128 if (s->protocol != DNS_PROTOCOL_DNS)
129 return NULL;
130
131 if (s->link)
132 return link_get_dns_server(s->link);
133 else
134 return manager_get_dns_server(s->manager);
135 }
136
137 unsigned dns_scope_get_n_dns_servers(DnsScope *s) {
138 unsigned n = 0;
139 DnsServer *i;
140
141 assert(s);
142
143 if (s->protocol != DNS_PROTOCOL_DNS)
144 return 0;
145
146 if (s->link)
147 i = s->link->dns_servers;
148 else
149 i = s->manager->dns_servers;
150
151 for (; i; i = i->servers_next)
152 n++;
153
154 return n;
155 }
156
157 void dns_scope_next_dns_server(DnsScope *s, DnsServer *if_current) {
158 assert(s);
159
160 if (s->protocol != DNS_PROTOCOL_DNS)
161 return;
162
163 /* Changes to the next DNS server in the list. If 'if_current' is passed will do so only if the
164 * current DNS server still matches it. */
165
166 if (s->link)
167 link_next_dns_server(s->link, if_current);
168 else
169 manager_next_dns_server(s->manager, if_current);
170 }
171
172 void dns_scope_packet_received(DnsScope *s, usec_t rtt) {
173 assert(s);
174
175 if (rtt <= s->max_rtt)
176 return;
177
178 s->max_rtt = rtt;
179 s->resend_timeout = MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC, s->max_rtt * 2), MULTICAST_RESEND_TIMEOUT_MAX_USEC);
180 }
181
182 void dns_scope_packet_lost(DnsScope *s, usec_t usec) {
183 assert(s);
184
185 if (s->resend_timeout <= usec)
186 s->resend_timeout = MIN(s->resend_timeout * 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC);
187 }
188
189 static int dns_scope_emit_one(DnsScope *s, int fd, int family, DnsPacket *p) {
190 int r;
191
192 assert(s);
193 assert(p);
194 assert(p->protocol == s->protocol);
195
196 if (family == AF_UNSPEC) {
197 if (s->family == AF_UNSPEC)
198 return -EAFNOSUPPORT;
199
200 family = s->family;
201 }
202
203 switch (s->protocol) {
204
205 case DNS_PROTOCOL_DNS: {
206 size_t mtu, udp_size, min_mtu, socket_mtu = 0;
207
208 assert(fd >= 0);
209
210 if (DNS_PACKET_QDCOUNT(p) > 1) /* Classic DNS only allows one question per packet */
211 return -EOPNOTSUPP;
212
213 if (p->size > DNS_PACKET_UNICAST_SIZE_MAX)
214 return -EMSGSIZE;
215
216 /* Determine the local most accurate MTU */
217 if (s->link)
218 mtu = s->link->mtu;
219 else
220 mtu = manager_find_mtu(s->manager);
221
222 /* Acquire the socket's PMDU MTU */
223 r = socket_get_mtu(fd, family, &socket_mtu);
224 if (r < 0 && !ERRNO_IS_DISCONNECT(r)) /* Will return ENOTCONN if no information is available yet */
225 return log_debug_errno(r, "Failed to read socket MTU: %m");
226
227 /* Determine the appropriate UDP header size */
228 udp_size = udp_header_size(family);
229 min_mtu = udp_size + DNS_PACKET_HEADER_SIZE;
230
231 log_debug("Emitting UDP, link MTU is %zu, socket MTU is %zu, minimal MTU is %zu",
232 mtu, socket_mtu, min_mtu);
233
234 /* Clamp by the kernel's idea of the (path) MTU */
235 if (socket_mtu != 0 && socket_mtu < mtu)
236 mtu = socket_mtu;
237
238 /* Put a lower limit, in case all MTU data we acquired was rubbish */
239 if (mtu < min_mtu)
240 mtu = min_mtu;
241
242 /* Now check our packet size against the MTU we determined */
243 if (udp_size + p->size > mtu)
244 return -EMSGSIZE; /* This means: try TCP instead */
245
246 r = manager_write(s->manager, fd, p);
247 if (r < 0)
248 return r;
249
250 break;
251 }
252
253 case DNS_PROTOCOL_LLMNR: {
254 union in_addr_union addr;
255
256 assert(fd < 0);
257
258 if (DNS_PACKET_QDCOUNT(p) > 1)
259 return -EOPNOTSUPP;
260
261 if (!ratelimit_below(&s->ratelimit))
262 return -EBUSY;
263
264 if (family == AF_INET) {
265 addr.in = LLMNR_MULTICAST_IPV4_ADDRESS;
266 fd = manager_llmnr_ipv4_udp_fd(s->manager);
267 } else if (family == AF_INET6) {
268 addr.in6 = LLMNR_MULTICAST_IPV6_ADDRESS;
269 fd = manager_llmnr_ipv6_udp_fd(s->manager);
270 } else
271 return -EAFNOSUPPORT;
272 if (fd < 0)
273 return fd;
274
275 r = manager_send(s->manager, fd, s->link->ifindex, family, &addr, LLMNR_PORT, NULL, p);
276 if (r < 0)
277 return r;
278
279 break;
280 }
281
282 case DNS_PROTOCOL_MDNS: {
283 union in_addr_union addr;
284 assert(fd < 0);
285
286 if (!ratelimit_below(&s->ratelimit))
287 return -EBUSY;
288
289 if (family == AF_INET) {
290 if (in4_addr_is_null(&p->destination.in))
291 addr.in = MDNS_MULTICAST_IPV4_ADDRESS;
292 else
293 addr = p->destination;
294 fd = manager_mdns_ipv4_fd(s->manager);
295 } else if (family == AF_INET6) {
296 if (in6_addr_is_null(&p->destination.in6))
297 addr.in6 = MDNS_MULTICAST_IPV6_ADDRESS;
298 else
299 addr = p->destination;
300 fd = manager_mdns_ipv6_fd(s->manager);
301 } else
302 return -EAFNOSUPPORT;
303 if (fd < 0)
304 return fd;
305
306 r = manager_send(s->manager, fd, s->link->ifindex, family, &addr, p->destination_port ?: MDNS_PORT, NULL, p);
307 if (r < 0)
308 return r;
309
310 break;
311 }
312
313 default:
314 return -EAFNOSUPPORT;
315 }
316
317 return 1;
318 }
319
320 int dns_scope_emit_udp(DnsScope *s, int fd, int af, DnsPacket *p) {
321 int r;
322
323 assert(s);
324 assert(p);
325 assert(p->protocol == s->protocol);
326 assert((s->protocol == DNS_PROTOCOL_DNS) == (fd >= 0));
327
328 do {
329 /* If there are multiple linked packets, set the TC bit in all but the last of them */
330 if (p->more) {
331 assert(p->protocol == DNS_PROTOCOL_MDNS);
332 dns_packet_set_flags(p, true, true);
333 }
334
335 r = dns_scope_emit_one(s, fd, af, p);
336 if (r < 0)
337 return r;
338
339 p = p->more;
340 } while (p);
341
342 return 0;
343 }
344
345 static int dns_scope_socket(
346 DnsScope *s,
347 int type,
348 int family,
349 const union in_addr_union *address,
350 DnsServer *server,
351 uint16_t port,
352 union sockaddr_union *ret_socket_address) {
353
354 _cleanup_close_ int fd = -EBADF;
355 union sockaddr_union sa;
356 socklen_t salen;
357 int r, ifindex;
358
359 assert(s);
360
361 if (server) {
362 assert(family == AF_UNSPEC);
363 assert(!address);
364
365 ifindex = dns_server_ifindex(server);
366
367 switch (server->family) {
368 case AF_INET:
369 sa = (union sockaddr_union) {
370 .in.sin_family = server->family,
371 .in.sin_port = htobe16(port),
372 .in.sin_addr = server->address.in,
373 };
374 salen = sizeof(sa.in);
375 break;
376 case AF_INET6:
377 sa = (union sockaddr_union) {
378 .in6.sin6_family = server->family,
379 .in6.sin6_port = htobe16(port),
380 .in6.sin6_addr = server->address.in6,
381 .in6.sin6_scope_id = ifindex,
382 };
383 salen = sizeof(sa.in6);
384 break;
385 default:
386 return -EAFNOSUPPORT;
387 }
388 } else {
389 assert(family != AF_UNSPEC);
390 assert(address);
391
392 ifindex = s->link ? s->link->ifindex : 0;
393
394 switch (family) {
395 case AF_INET:
396 sa = (union sockaddr_union) {
397 .in.sin_family = family,
398 .in.sin_port = htobe16(port),
399 .in.sin_addr = address->in,
400 };
401 salen = sizeof(sa.in);
402 break;
403 case AF_INET6:
404 sa = (union sockaddr_union) {
405 .in6.sin6_family = family,
406 .in6.sin6_port = htobe16(port),
407 .in6.sin6_addr = address->in6,
408 .in6.sin6_scope_id = ifindex,
409 };
410 salen = sizeof(sa.in6);
411 break;
412 default:
413 return -EAFNOSUPPORT;
414 }
415 }
416
417 fd = socket(sa.sa.sa_family, type|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
418 if (fd < 0)
419 return -errno;
420
421 if (type == SOCK_STREAM) {
422 r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true);
423 if (r < 0)
424 return r;
425 }
426
427 if (ifindex != 0) {
428 r = socket_set_unicast_if(fd, sa.sa.sa_family, ifindex);
429 if (r < 0)
430 return r;
431 }
432
433 if (s->protocol == DNS_PROTOCOL_LLMNR) {
434 /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
435 r = socket_set_ttl(fd, sa.sa.sa_family, 1);
436 if (r < 0)
437 return r;
438 }
439
440 if (type == SOCK_DGRAM) {
441 /* Set IP_RECVERR or IPV6_RECVERR to get ICMP error feedback. See discussion in #10345. */
442 r = socket_set_recverr(fd, sa.sa.sa_family, true);
443 if (r < 0)
444 return r;
445
446 r = socket_set_recvpktinfo(fd, sa.sa.sa_family, true);
447 if (r < 0)
448 return r;
449
450 /* Turn of path MTU discovery for security reasons */
451 r = socket_disable_pmtud(fd, sa.sa.sa_family);
452 if (r < 0)
453 log_debug_errno(r, "Failed to disable UDP PMTUD, ignoring: %m");
454
455 /* Learn about fragmentation taking place */
456 r = socket_set_recvfragsize(fd, sa.sa.sa_family, true);
457 if (r < 0)
458 log_debug_errno(r, "Failed to enable fragment size reception, ignoring: %m");
459 }
460
461 if (ret_socket_address)
462 *ret_socket_address = sa;
463 else {
464 bool bound = false;
465
466 /* Let's temporarily bind the socket to the specified ifindex. The kernel currently takes
467 * only the SO_BINDTODEVICE/SO_BINDTOINDEX ifindex into account when making routing decisions
468 * in connect() — and not IP_UNICAST_IF. We don't really want any of the other semantics of
469 * SO_BINDTODEVICE/SO_BINDTOINDEX, hence we immediately unbind the socket after the fact
470 * again.
471 *
472 * As a special exception we don't do this if we notice that the specified IP address is on
473 * the local host. SO_BINDTODEVICE in combination with destination addresses on the local
474 * host result in EHOSTUNREACH, since Linux won't send the packets out of the specified
475 * interface, but delivers them directly to the local socket. */
476 if (s->link &&
477 !manager_find_link_address(s->manager, sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) &&
478 in_addr_is_localhost(sa.sa.sa_family, sockaddr_in_addr(&sa.sa)) == 0) {
479 r = socket_bind_to_ifindex(fd, ifindex);
480 if (r < 0)
481 return r;
482
483 bound = true;
484 }
485
486 r = connect(fd, &sa.sa, salen);
487 if (r < 0 && errno != EINPROGRESS)
488 return -errno;
489
490 if (bound) {
491 r = socket_bind_to_ifindex(fd, 0);
492 if (r < 0)
493 return r;
494 }
495 }
496
497 return TAKE_FD(fd);
498 }
499
500 int dns_scope_socket_udp(DnsScope *s, DnsServer *server) {
501 return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, dns_server_port(server), NULL);
502 }
503
504 int dns_scope_socket_tcp(DnsScope *s, int family, const union in_addr_union *address, DnsServer *server, uint16_t port, union sockaddr_union *ret_socket_address) {
505 /* If ret_socket_address is not NULL, the caller is responsible
506 * for calling connect() or sendmsg(). This is required by TCP
507 * Fast Open, to be able to send the initial SYN packet along
508 * with the first data packet. */
509 return dns_scope_socket(s, SOCK_STREAM, family, address, server, port, ret_socket_address);
510 }
511
512 static DnsScopeMatch match_link_local_reverse_lookups(const char *domain) {
513 assert(domain);
514
515 if (dns_name_endswith(domain, "254.169.in-addr.arpa") > 0)
516 return DNS_SCOPE_YES_BASE + 4; /* 4 labels match */
517
518 if (dns_name_endswith(domain, "8.e.f.ip6.arpa") > 0 ||
519 dns_name_endswith(domain, "9.e.f.ip6.arpa") > 0 ||
520 dns_name_endswith(domain, "a.e.f.ip6.arpa") > 0 ||
521 dns_name_endswith(domain, "b.e.f.ip6.arpa") > 0)
522 return DNS_SCOPE_YES_BASE + 5; /* 5 labels match */
523
524 return _DNS_SCOPE_MATCH_INVALID;
525 }
526
527 static DnsScopeMatch match_subnet_reverse_lookups(
528 DnsScope *s,
529 const char *domain,
530 bool exclude_own) {
531
532 union in_addr_union ia;
533 int f, r;
534
535 assert(s);
536 assert(domain);
537
538 /* Checks whether the specified domain is a reverse address domain (i.e. in the .in-addr.arpa or
539 * .ip6.arpa area), and if so, whether the address matches any of the local subnets of the link the
540 * scope is associated with. If so, our scope should consider itself relevant for any lookup in the
541 * domain, since it apparently refers to hosts on this link's subnet.
542 *
543 * If 'exclude_own' is true this will return DNS_SCOPE_NO for any IP addresses assigned locally. This
544 * is useful for LLMNR/mDNS as we never want to look up our own hostname on LLMNR/mDNS but always use
545 * the locally synthesized one. */
546
547 if (!s->link)
548 return _DNS_SCOPE_MATCH_INVALID; /* No link, hence no local addresses to check */
549
550 r = dns_name_address(domain, &f, &ia);
551 if (r < 0)
552 log_debug_errno(r, "Failed to determine whether '%s' is an address domain: %m", domain);
553 if (r <= 0)
554 return _DNS_SCOPE_MATCH_INVALID;
555
556 if (s->family != AF_UNSPEC && f != s->family)
557 return _DNS_SCOPE_MATCH_INVALID; /* Don't look for IPv4 addresses on LLMNR/mDNS over IPv6 and vice versa */
558
559 if (in_addr_is_null(f, &ia))
560 return DNS_SCOPE_NO;
561
562 LIST_FOREACH(addresses, a, s->link->addresses) {
563
564 if (a->family != f)
565 continue;
566
567 /* Equals our own address? nah, let's not use this scope. The local synthesizer will pick it up for us. */
568 if (exclude_own &&
569 in_addr_equal(f, &a->in_addr, &ia) > 0)
570 return DNS_SCOPE_NO;
571
572 if (a->prefixlen == UCHAR_MAX) /* don't know subnet mask */
573 continue;
574
575 /* Don't send mDNS queries for the IPv4 broadcast address */
576 if (f == AF_INET && in_addr_equal(f, &a->in_addr_broadcast, &ia) > 0)
577 return DNS_SCOPE_NO;
578
579 /* Check if the address is in the local subnet */
580 r = in_addr_prefix_covers(f, &a->in_addr, a->prefixlen, &ia);
581 if (r < 0)
582 log_debug_errno(r, "Failed to determine whether link address covers lookup address '%s': %m", domain);
583 if (r > 0)
584 /* Note that we only claim zero labels match. This is so that this is at the same
585 * priority a DNS scope with "." as routing domain is. */
586 return DNS_SCOPE_YES_BASE + 0;
587 }
588
589 return _DNS_SCOPE_MATCH_INVALID;
590 }
591
592 DnsScopeMatch dns_scope_good_domain(
593 DnsScope *s,
594 DnsQuery *q) {
595
596 DnsQuestion *question;
597 const char *domain;
598 uint64_t flags;
599 int ifindex;
600
601 /* This returns the following return values:
602 *
603 * DNS_SCOPE_NO → This scope is not suitable for lookups of this domain, at all
604 * DNS_SCOPE_MAYBE → This scope is suitable, but only if nothing else wants it
605 * DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match
606 *
607 * (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return
608 * DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those
609 * which returned DNS_SCOPE_NO.)
610 */
611
612 assert(s);
613 assert(q);
614
615 question = dns_query_question_for_protocol(q, s->protocol);
616 if (!question)
617 return DNS_SCOPE_NO;
618
619 domain = dns_question_first_name(question);
620 if (!domain)
621 return DNS_SCOPE_NO;
622
623 ifindex = q->ifindex;
624 flags = q->flags;
625
626 /* Checks if the specified domain is something to look up on this scope. Note that this accepts
627 * non-qualified hostnames, i.e. those without any search path suffixed. */
628
629 if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
630 return DNS_SCOPE_NO;
631
632 if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, false, false) & flags) == 0)
633 return DNS_SCOPE_NO;
634
635 /* Never resolve any loopback hostname or IP address via DNS, LLMNR or mDNS. Instead, always rely on
636 * synthesized RRs for these. */
637 if (is_localhost(domain) ||
638 dns_name_endswith(domain, "127.in-addr.arpa") > 0 ||
639 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)
640 return DNS_SCOPE_NO;
641
642 /* Never respond to some of the domains listed in RFC6303 + RFC6761 */
643 if (dns_name_dont_resolve(domain))
644 return DNS_SCOPE_NO;
645
646 /* Never go to network for the _gateway, _outbound, _localdnsstub, _localdnsproxy domain — they're something special, synthesized locally. */
647 if (is_gateway_hostname(domain) ||
648 is_outbound_hostname(domain) ||
649 is_dns_stub_hostname(domain) ||
650 is_dns_proxy_stub_hostname(domain))
651 return DNS_SCOPE_NO;
652
653 switch (s->protocol) {
654
655 case DNS_PROTOCOL_DNS: {
656 bool has_search_domains = false;
657 DnsScopeMatch m;
658 int n_best = -1;
659
660 if (dns_name_is_root(domain)) {
661 DnsResourceKey *t;
662 bool found = false;
663
664 /* Refuse root name if only A and/or AAAA records are requested. */
665
666 DNS_QUESTION_FOREACH(t, question)
667 if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA)) {
668 found = true;
669 break;
670 }
671
672 if (!found)
673 return DNS_SCOPE_NO;
674 }
675
676 /* Never route things to scopes that lack DNS servers */
677 if (!dns_scope_get_dns_server(s))
678 return DNS_SCOPE_NO;
679
680 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
681 * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
682 * won't be considered anymore. */
683 LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) {
684
685 if (!d->route_only && !dns_name_is_root(d->name))
686 has_search_domains = true;
687
688 if (dns_name_endswith(domain, d->name) > 0) {
689 int c;
690
691 c = dns_name_count_labels(d->name);
692 if (c < 0)
693 continue;
694
695 if (c > n_best)
696 n_best = c;
697 }
698 }
699
700 /* If there's a true search domain defined for this scope, and the query is single-label,
701 * then let's resolve things here, preferably. Note that LLMNR considers itself
702 * authoritative for single-label names too, at the same preference, see below. */
703 if (has_search_domains && dns_name_is_single_label(domain))
704 return DNS_SCOPE_YES_BASE + 1;
705
706 /* If ResolveUnicastSingleLabel=yes and the query is single-label, then bump match result
707 to prevent LLMNR monopoly among candidates. */
708 if (s->manager->resolve_unicast_single_label && dns_name_is_single_label(domain))
709 return DNS_SCOPE_YES_BASE + 1;
710
711 /* Let's return the number of labels in the best matching result */
712 if (n_best >= 0) {
713 assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE);
714 return DNS_SCOPE_YES_BASE + n_best;
715 }
716
717 /* Exclude link-local IP ranges */
718 if (match_link_local_reverse_lookups(domain) >= DNS_SCOPE_YES_BASE ||
719 /* If networks use .local in their private setups, they are supposed to also add .local
720 * to their search domains, which we already checked above. Otherwise, we consider .local
721 * specific to mDNS and won't send such queries ordinary DNS servers. */
722 dns_name_endswith(domain, "local") > 0)
723 return DNS_SCOPE_NO;
724
725 /* If the IP address to look up matches the local subnet, then implicitly synthesizes
726 * DNS_SCOPE_YES_BASE + 0 on this interface, i.e. preferably resolve IP addresses via the DNS
727 * server belonging to this interface. */
728 m = match_subnet_reverse_lookups(s, domain, false);
729 if (m >= 0)
730 return m;
731
732 /* If there was no match at all, then see if this scope is suitable as default route. */
733 if (!dns_scope_is_default_route(s))
734 return DNS_SCOPE_NO;
735
736 return DNS_SCOPE_MAYBE;
737 }
738
739 case DNS_PROTOCOL_MDNS: {
740 DnsScopeMatch m;
741
742 m = match_link_local_reverse_lookups(domain);
743 if (m >= 0)
744 return m;
745
746 m = match_subnet_reverse_lookups(s, domain, true);
747 if (m >= 0)
748 return m;
749
750 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
751 (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
752 return DNS_SCOPE_MAYBE;
753
754 if ((dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */
755 dns_name_equal(domain, "local") == 0 && /* but not the single-label "local" name itself */
756 manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */
757 return DNS_SCOPE_YES_BASE + 1; /* Return +1, as the top-level .local domain matches, i.e. one label */
758
759 return DNS_SCOPE_NO;
760 }
761
762 case DNS_PROTOCOL_LLMNR: {
763 DnsScopeMatch m;
764
765 m = match_link_local_reverse_lookups(domain);
766 if (m >= 0)
767 return m;
768
769 m = match_subnet_reverse_lookups(s, domain, true);
770 if (m >= 0)
771 return m;
772
773 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
774 (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
775 return DNS_SCOPE_MAYBE;
776
777 if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
778 dns_name_equal(domain, "local") == 0 && /* don't resolve "local" with LLMNR, it's the top-level domain of mDNS after all, see above */
779 manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via LLMNR */
780 return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative
781 * for single-label names, i.e. one label. This is
782 * particularly relevant as it means a "." route on some
783 * other scope won't pull all traffic away from
784 * us. (If people actually want to pull traffic away
785 * from us they should turn off LLMNR on the
786 * link). Note that unicast DNS scopes with search
787 * domains also consider themselves authoritative for
788 * single-label domains, at the same preference (see
789 * above). */
790
791 return DNS_SCOPE_NO;
792 }
793
794 default:
795 assert_not_reached();
796 }
797 }
798
799 bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) {
800 int key_family;
801
802 assert(s);
803 assert(key);
804
805 /* Check if it makes sense to resolve the specified key on this scope. Note that this call assumes a
806 * fully qualified name, i.e. the search suffixes already appended. */
807
808 if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY))
809 return false;
810
811 if (s->protocol == DNS_PROTOCOL_DNS) {
812
813 /* On classic DNS, looking up non-address RRs is always fine. (Specifically, we want to
814 * permit looking up DNSKEY and DS records on the root and top-level domains.) */
815 if (!dns_resource_key_is_address(key))
816 return true;
817
818 /* Unless explicitly overridden, we refuse to look up A and AAAA RRs on the root and
819 * single-label domains, under the assumption that those should be resolved via LLMNR or
820 * search path only, and should not be leaked onto the internet. */
821 const char* name = dns_resource_key_name(key);
822
823 if (!s->manager->resolve_unicast_single_label &&
824 dns_name_is_single_label(name))
825 return false;
826
827 return !dns_name_is_root(name);
828 }
829
830 /* Never route DNSSEC RR queries to LLMNR/mDNS scopes */
831 if (dns_type_is_dnssec(key->type))
832 return false;
833
834 /* On mDNS and LLMNR, send A and AAAA queries only on the respective scopes */
835
836 key_family = dns_type_to_af(key->type);
837 if (key_family < 0)
838 return true;
839
840 return key_family == s->family;
841 }
842
843 static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) {
844 int fd;
845
846 assert(s);
847 assert(s->link);
848
849 if (s->family == AF_INET) {
850 struct ip_mreqn mreqn = {
851 .imr_multiaddr = in,
852 .imr_ifindex = s->link->ifindex,
853 };
854
855 if (s->protocol == DNS_PROTOCOL_LLMNR)
856 fd = manager_llmnr_ipv4_udp_fd(s->manager);
857 else
858 fd = manager_mdns_ipv4_fd(s->manager);
859
860 if (fd < 0)
861 return fd;
862
863 /* Always first try to drop membership before we add
864 * one. This is necessary on some devices, such as
865 * veth. */
866 if (b)
867 (void) setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn));
868
869 if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0)
870 return -errno;
871
872 } else if (s->family == AF_INET6) {
873 struct ipv6_mreq mreq = {
874 .ipv6mr_multiaddr = in6,
875 .ipv6mr_interface = s->link->ifindex,
876 };
877
878 if (s->protocol == DNS_PROTOCOL_LLMNR)
879 fd = manager_llmnr_ipv6_udp_fd(s->manager);
880 else
881 fd = manager_mdns_ipv6_fd(s->manager);
882
883 if (fd < 0)
884 return fd;
885
886 if (b)
887 (void) setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
888
889 if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
890 return -errno;
891 } else
892 return -EAFNOSUPPORT;
893
894 return 0;
895 }
896
897 int dns_scope_llmnr_membership(DnsScope *s, bool b) {
898 assert(s);
899
900 if (s->protocol != DNS_PROTOCOL_LLMNR)
901 return 0;
902
903 return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS);
904 }
905
906 int dns_scope_mdns_membership(DnsScope *s, bool b) {
907 assert(s);
908
909 if (s->protocol != DNS_PROTOCOL_MDNS)
910 return 0;
911
912 return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS);
913 }
914
915 int dns_scope_make_reply_packet(
916 DnsScope *s,
917 uint16_t id,
918 int rcode,
919 DnsQuestion *q,
920 DnsAnswer *answer,
921 DnsAnswer *soa,
922 bool tentative,
923 DnsPacket **ret) {
924
925 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
926 unsigned n_answer = 0, n_soa = 0;
927 int r;
928 bool c_or_aa;
929
930 assert(s);
931 assert(ret);
932
933 if (dns_question_isempty(q) &&
934 dns_answer_isempty(answer) &&
935 dns_answer_isempty(soa))
936 return -EINVAL;
937
938 r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
939 if (r < 0)
940 return r;
941
942 /* mDNS answers must have the Authoritative Answer bit set, see RFC 6762, section 18.4. */
943 c_or_aa = s->protocol == DNS_PROTOCOL_MDNS;
944
945 DNS_PACKET_HEADER(p)->id = id;
946 DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
947 1 /* qr */,
948 0 /* opcode */,
949 c_or_aa,
950 0 /* tc */,
951 tentative,
952 0 /* (ra) */,
953 0 /* (ad) */,
954 0 /* (cd) */,
955 rcode));
956
957 r = dns_packet_append_question(p, q);
958 if (r < 0)
959 return r;
960 DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
961
962 r = dns_packet_append_answer(p, answer, &n_answer);
963 if (r < 0)
964 return r;
965 DNS_PACKET_HEADER(p)->ancount = htobe16(n_answer);
966
967 r = dns_packet_append_answer(p, soa, &n_soa);
968 if (r < 0)
969 return r;
970 DNS_PACKET_HEADER(p)->arcount = htobe16(n_soa);
971
972 *ret = TAKE_PTR(p);
973
974 return 0;
975 }
976
977 static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) {
978 DnsResourceRecord *rr;
979 DnsResourceKey *key;
980
981 assert(s);
982 assert(p);
983
984 DNS_QUESTION_FOREACH(key, p->question)
985 dns_zone_verify_conflicts(&s->zone, key);
986
987 DNS_ANSWER_FOREACH(rr, p->answer)
988 dns_zone_verify_conflicts(&s->zone, rr->key);
989 }
990
991 void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
992 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
993 _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
994 DnsResourceKey *key = NULL;
995 bool tentative = false;
996 int r;
997
998 assert(s);
999 assert(p);
1000
1001 if (p->protocol != DNS_PROTOCOL_LLMNR)
1002 return;
1003
1004 if (p->ipproto == IPPROTO_UDP) {
1005 /* Don't accept UDP queries directed to anything but
1006 * the LLMNR multicast addresses. See RFC 4795,
1007 * section 2.5. */
1008
1009 if (p->family == AF_INET && !in4_addr_equal(&p->destination.in, &LLMNR_MULTICAST_IPV4_ADDRESS))
1010 return;
1011
1012 if (p->family == AF_INET6 && !in6_addr_equal(&p->destination.in6, &LLMNR_MULTICAST_IPV6_ADDRESS))
1013 return;
1014 }
1015
1016 r = dns_packet_extract(p);
1017 if (r < 0) {
1018 log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
1019 return;
1020 }
1021
1022 if (DNS_PACKET_LLMNR_C(p)) {
1023 /* Somebody notified us about a possible conflict */
1024 dns_scope_verify_conflicts(s, p);
1025 return;
1026 }
1027
1028 if (dns_question_size(p->question) != 1)
1029 return (void) log_debug("Received LLMNR query without question or multiple questions, ignoring.");
1030
1031 key = dns_question_first_key(p->question);
1032
1033 r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
1034 if (r < 0) {
1035 log_debug_errno(r, "Failed to look up key: %m");
1036 return;
1037 }
1038 if (r == 0)
1039 return;
1040
1041 if (answer)
1042 dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0);
1043
1044 r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply);
1045 if (r < 0) {
1046 log_debug_errno(r, "Failed to build reply packet: %m");
1047 return;
1048 }
1049
1050 if (stream) {
1051 r = dns_stream_write_packet(stream, reply);
1052 if (r < 0) {
1053 log_debug_errno(r, "Failed to enqueue reply packet: %m");
1054 return;
1055 }
1056
1057 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
1058 * will be dangling until the stream is disconnected, and the default completion handler of the stream
1059 * will then unref the stream and destroy it */
1060 if (DNS_STREAM_QUEUED(stream))
1061 dns_stream_ref(stream);
1062 } else {
1063 int fd;
1064
1065 if (!ratelimit_below(&s->ratelimit))
1066 return;
1067
1068 if (p->family == AF_INET)
1069 fd = manager_llmnr_ipv4_udp_fd(s->manager);
1070 else if (p->family == AF_INET6)
1071 fd = manager_llmnr_ipv6_udp_fd(s->manager);
1072 else {
1073 log_debug("Unknown protocol");
1074 return;
1075 }
1076 if (fd < 0) {
1077 log_debug_errno(fd, "Failed to get reply socket: %m");
1078 return;
1079 }
1080
1081 /* Note that we always immediately reply to all LLMNR
1082 * requests, and do not wait any time, since we
1083 * verified uniqueness for all records. Also see RFC
1084 * 4795, Section 2.7 */
1085
1086 r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, NULL, reply);
1087 if (r < 0) {
1088 log_debug_errno(r, "Failed to send reply packet: %m");
1089 return;
1090 }
1091 }
1092 }
1093
1094 DnsTransaction *dns_scope_find_transaction(
1095 DnsScope *scope,
1096 DnsResourceKey *key,
1097 uint64_t query_flags) {
1098
1099 DnsTransaction *first;
1100
1101 assert(scope);
1102 assert(key);
1103
1104 /* Iterate through the list of transactions with a matching key */
1105 first = hashmap_get(scope->transactions_by_key, key);
1106 LIST_FOREACH(transactions_by_key, t, first) {
1107
1108 /* These four flags must match exactly: we cannot use a validated response for a
1109 * non-validating client, and we cannot use a non-validated response for a validating
1110 * client. Similar, if the sources don't match things aren't usable either. */
1111 if (((query_flags ^ t->query_flags) &
1112 (SD_RESOLVED_NO_VALIDATE|
1113 SD_RESOLVED_NO_ZONE|
1114 SD_RESOLVED_NO_TRUST_ANCHOR|
1115 SD_RESOLVED_NO_NETWORK)) != 0)
1116 continue;
1117
1118 /* We can reuse a primary query if a regular one is requested, but not vice versa */
1119 if ((query_flags & SD_RESOLVED_REQUIRE_PRIMARY) &&
1120 !(t->query_flags & SD_RESOLVED_REQUIRE_PRIMARY))
1121 continue;
1122
1123 /* Don't reuse a transaction that allowed caching when we got told not to use it */
1124 if ((query_flags & SD_RESOLVED_NO_CACHE) &&
1125 !(t->query_flags & SD_RESOLVED_NO_CACHE))
1126 continue;
1127
1128 /* If we are asked to clamp ttls and the existing transaction doesn't do it, we can't
1129 * reuse */
1130 if ((query_flags & SD_RESOLVED_CLAMP_TTL) &&
1131 !(t->query_flags & SD_RESOLVED_CLAMP_TTL))
1132 continue;
1133
1134 return t;
1135 }
1136
1137 return NULL;
1138 }
1139
1140 static int dns_scope_make_conflict_packet(
1141 DnsScope *s,
1142 DnsResourceRecord *rr,
1143 DnsPacket **ret) {
1144
1145 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1146 int r;
1147
1148 assert(s);
1149 assert(rr);
1150 assert(ret);
1151
1152 r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
1153 if (r < 0)
1154 return r;
1155
1156 DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
1157 0 /* qr */,
1158 0 /* opcode */,
1159 1 /* conflict */,
1160 0 /* tc */,
1161 0 /* t */,
1162 0 /* (ra) */,
1163 0 /* (ad) */,
1164 0 /* (cd) */,
1165 0));
1166
1167 /* For mDNS, the transaction ID should always be 0 */
1168 if (s->protocol != DNS_PROTOCOL_MDNS)
1169 random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t));
1170
1171 DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
1172 DNS_PACKET_HEADER(p)->arcount = htobe16(1);
1173
1174 r = dns_packet_append_key(p, rr->key, 0, NULL);
1175 if (r < 0)
1176 return r;
1177
1178 r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
1179 if (r < 0)
1180 return r;
1181
1182 *ret = TAKE_PTR(p);
1183
1184 return 0;
1185 }
1186
1187 static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) {
1188 DnsScope *scope = ASSERT_PTR(userdata);
1189 int r;
1190
1191 assert(es);
1192
1193 scope->conflict_event_source = sd_event_source_disable_unref(scope->conflict_event_source);
1194
1195 for (;;) {
1196 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1197 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1198 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1199
1200 key = ordered_hashmap_first_key(scope->conflict_queue);
1201 if (!key)
1202 break;
1203
1204 rr = ordered_hashmap_remove(scope->conflict_queue, key);
1205 assert(rr);
1206
1207 r = dns_scope_make_conflict_packet(scope, rr, &p);
1208 if (r < 0) {
1209 log_error_errno(r, "Failed to make conflict packet: %m");
1210 return 0;
1211 }
1212
1213 r = dns_scope_emit_udp(scope, -1, AF_UNSPEC, p);
1214 if (r < 0)
1215 log_debug_errno(r, "Failed to send conflict packet: %m");
1216 }
1217
1218 return 0;
1219 }
1220
1221 int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
1222 int r;
1223
1224 assert(scope);
1225 assert(rr);
1226
1227 /* We don't send these queries immediately. Instead, we queue
1228 * them, and send them after some jitter delay. */
1229 r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops);
1230 if (r < 0) {
1231 log_oom();
1232 return r;
1233 }
1234
1235 /* We only place one RR per key in the conflict
1236 * messages, not all of them. That should be enough to
1237 * indicate where there might be a conflict */
1238 r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr);
1239 if (IN_SET(r, 0, -EEXIST))
1240 return 0;
1241 if (r < 0)
1242 return log_debug_errno(r, "Failed to queue conflicting RR: %m");
1243
1244 dns_resource_key_ref(rr->key);
1245 dns_resource_record_ref(rr);
1246
1247 if (scope->conflict_event_source)
1248 return 0;
1249
1250 r = sd_event_add_time_relative(
1251 scope->manager->event,
1252 &scope->conflict_event_source,
1253 CLOCK_BOOTTIME,
1254 random_u64_range(LLMNR_JITTER_INTERVAL_USEC),
1255 0,
1256 on_conflict_dispatch, scope);
1257 if (r < 0)
1258 return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
1259
1260 (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
1261
1262 return 0;
1263 }
1264
1265 void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
1266 DnsResourceRecord *rr;
1267 int r;
1268
1269 assert(scope);
1270 assert(p);
1271
1272 if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS))
1273 return;
1274
1275 if (DNS_PACKET_RRCOUNT(p) <= 0)
1276 return;
1277
1278 if (p->protocol == DNS_PROTOCOL_LLMNR) {
1279 if (DNS_PACKET_LLMNR_C(p) != 0)
1280 return;
1281
1282 if (DNS_PACKET_LLMNR_T(p) != 0)
1283 return;
1284 }
1285
1286 if (manager_packet_from_local_address(scope->manager, p))
1287 return;
1288
1289 r = dns_packet_extract(p);
1290 if (r < 0) {
1291 log_debug_errno(r, "Failed to extract packet: %m");
1292 return;
1293 }
1294
1295 log_debug("Checking for conflicts...");
1296
1297 DNS_ANSWER_FOREACH(rr, p->answer) {
1298 /* No conflict if it is DNS-SD RR used for service enumeration. */
1299 if (dns_resource_key_is_dnssd_ptr(rr->key))
1300 continue;
1301
1302 /* Check for conflicts against the local zone. If we
1303 * found one, we won't check any further */
1304 r = dns_zone_check_conflicts(&scope->zone, rr);
1305 if (r != 0)
1306 continue;
1307
1308 /* Check for conflicts against the local cache. If so,
1309 * send out an advisory query, to inform everybody */
1310 r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender);
1311 if (r <= 0)
1312 continue;
1313
1314 dns_scope_notify_conflict(scope, rr);
1315 }
1316 }
1317
1318 void dns_scope_dump(DnsScope *s, FILE *f) {
1319 assert(s);
1320
1321 if (!f)
1322 f = stdout;
1323
1324 fputs("[Scope protocol=", f);
1325 fputs(dns_protocol_to_string(s->protocol), f);
1326
1327 if (s->link) {
1328 fputs(" interface=", f);
1329 fputs(s->link->ifname, f);
1330 }
1331
1332 if (s->family != AF_UNSPEC) {
1333 fputs(" family=", f);
1334 fputs(af_to_name(s->family), f);
1335 }
1336
1337 fputs("]\n", f);
1338
1339 if (!dns_zone_is_empty(&s->zone)) {
1340 fputs("ZONE:\n", f);
1341 dns_zone_dump(&s->zone, f);
1342 }
1343
1344 if (!dns_cache_is_empty(&s->cache)) {
1345 fputs("CACHE:\n", f);
1346 dns_cache_dump(&s->cache, f);
1347 }
1348 }
1349
1350 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
1351 assert(s);
1352
1353 if (s->protocol != DNS_PROTOCOL_DNS)
1354 return NULL;
1355
1356 if (s->link)
1357 return s->link->search_domains;
1358
1359 return s->manager->search_domains;
1360 }
1361
1362 bool dns_scope_name_wants_search_domain(DnsScope *s, const char *name) {
1363 assert(s);
1364
1365 if (s->protocol != DNS_PROTOCOL_DNS)
1366 return false;
1367
1368 return dns_name_is_single_label(name);
1369 }
1370
1371 bool dns_scope_network_good(DnsScope *s) {
1372 /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1373 * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1374 * DNS scope we check whether there are any links that are up and have an address.
1375 *
1376 * Note that Linux routing is complex and even systems that superficially have no IPv4 address might
1377 * be able to route IPv4 (and similar for IPv6), hence let's make a check here independent of address
1378 * family. */
1379
1380 if (s->link)
1381 return true;
1382
1383 return manager_routable(s->manager);
1384 }
1385
1386 int dns_scope_ifindex(DnsScope *s) {
1387 assert(s);
1388
1389 if (s->link)
1390 return s->link->ifindex;
1391
1392 return 0;
1393 }
1394
1395 static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1396 DnsScope *scope = userdata;
1397
1398 assert(s);
1399
1400 scope->announce_event_source = sd_event_source_disable_unref(scope->announce_event_source);
1401
1402 (void) dns_scope_announce(scope, false);
1403 return 0;
1404 }
1405
1406 int dns_scope_announce(DnsScope *scope, bool goodbye) {
1407 _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1408 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1409 _cleanup_set_free_ Set *types = NULL;
1410 DnsZoneItem *z;
1411 unsigned size = 0;
1412 char *service_type;
1413 int r;
1414
1415 if (!scope)
1416 return 0;
1417
1418 if (scope->protocol != DNS_PROTOCOL_MDNS)
1419 return 0;
1420
1421 /* Check if we're done with probing. */
1422 LIST_FOREACH(transactions_by_scope, t, scope->transactions)
1423 if (t->probing && DNS_TRANSACTION_IS_LIVE(t->state))
1424 return 0;
1425
1426 /* Check if there're services pending conflict resolution. */
1427 if (manager_next_dnssd_names(scope->manager))
1428 return 0; /* we reach this point only if changing hostname didn't help */
1429
1430 /* Calculate answer's size. */
1431 HASHMAP_FOREACH(z, scope->zone.by_key) {
1432 if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
1433 continue;
1434
1435 if (z->rr->key->type == DNS_TYPE_PTR &&
1436 !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
1437 char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1438
1439 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));
1440 z->state = DNS_ZONE_ITEM_WITHDRAWN;
1441 continue;
1442 }
1443
1444 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1445 if (!scope->announced &&
1446 dns_resource_key_is_dnssd_ptr(z->rr->key)) {
1447 if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
1448 r = set_ensure_put(&types, &dns_name_hash_ops, dns_resource_key_name(z->rr->key));
1449 if (r < 0)
1450 return log_debug_errno(r, "Failed to add item to set: %m");
1451 }
1452 }
1453
1454 LIST_FOREACH(by_key, i, z)
1455 size++;
1456 }
1457
1458 answer = dns_answer_new(size + set_size(types));
1459 if (!answer)
1460 return log_oom();
1461
1462 /* Second iteration, actually add RRs to the answer. */
1463 HASHMAP_FOREACH(z, scope->zone.by_key)
1464 LIST_FOREACH (by_key, i, z) {
1465 DnsAnswerFlags flags;
1466
1467 if (i->state != DNS_ZONE_ITEM_ESTABLISHED)
1468 continue;
1469
1470 if (dns_resource_key_is_dnssd_ptr(i->rr->key))
1471 flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
1472 else
1473 flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
1474
1475 r = dns_answer_add(answer, i->rr, 0, flags, NULL);
1476 if (r < 0)
1477 return log_debug_errno(r, "Failed to add RR to announce: %m");
1478 }
1479
1480 /* Since all the active services are in the zone make them discoverable now. */
1481 SET_FOREACH(service_type, types) {
1482 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1483
1484 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
1485 "_services._dns-sd._udp.local");
1486 if (!rr)
1487 return log_oom();
1488
1489 rr->ptr.name = strdup(service_type);
1490 if (!rr->ptr.name)
1491 return log_oom();
1492
1493 rr->ttl = MDNS_DEFAULT_TTL;
1494
1495 r = dns_zone_put(&scope->zone, scope, rr, false);
1496 if (r < 0)
1497 log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone, ignoring: %m");
1498
1499 r = dns_answer_add(answer, rr, 0, 0, NULL);
1500 if (r < 0)
1501 return log_debug_errno(r, "Failed to add RR to announce: %m");
1502 }
1503
1504 if (dns_answer_isempty(answer))
1505 return 0;
1506
1507 r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p);
1508 if (r < 0)
1509 return log_debug_errno(r, "Failed to build reply packet: %m");
1510
1511 r = dns_scope_emit_udp(scope, -1, AF_UNSPEC, p);
1512 if (r < 0)
1513 return log_debug_errno(r, "Failed to send reply packet: %m");
1514
1515 /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1516 * responses, one second apart." */
1517 if (!scope->announced) {
1518 scope->announced = true;
1519
1520 r = sd_event_add_time_relative(
1521 scope->manager->event,
1522 &scope->announce_event_source,
1523 CLOCK_BOOTTIME,
1524 MDNS_ANNOUNCE_DELAY,
1525 0,
1526 on_announcement_timeout, scope);
1527 if (r < 0)
1528 return log_debug_errno(r, "Failed to schedule second announcement: %m");
1529
1530 (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce");
1531 }
1532
1533 return 0;
1534 }
1535
1536 int dns_scope_add_dnssd_services(DnsScope *scope) {
1537 DnssdService *service;
1538 int r;
1539
1540 assert(scope);
1541
1542 if (hashmap_size(scope->manager->dnssd_services) == 0)
1543 return 0;
1544
1545 scope->announced = false;
1546
1547 HASHMAP_FOREACH(service, scope->manager->dnssd_services) {
1548 service->withdrawn = false;
1549
1550 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
1551 if (r < 0)
1552 log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");
1553
1554 r = dns_zone_put(&scope->zone, scope, service->srv_rr, true);
1555 if (r < 0)
1556 log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m");
1557
1558 LIST_FOREACH(items, txt_data, service->txt_data_items) {
1559 r = dns_zone_put(&scope->zone, scope, txt_data->rr, true);
1560 if (r < 0)
1561 log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m");
1562 }
1563 }
1564
1565 return 0;
1566 }
1567
1568 int dns_scope_remove_dnssd_services(DnsScope *scope) {
1569 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1570 DnssdService *service;
1571 int r;
1572
1573 assert(scope);
1574
1575 key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR,
1576 "_services._dns-sd._udp.local");
1577 if (!key)
1578 return log_oom();
1579
1580 r = dns_zone_remove_rrs_by_key(&scope->zone, key);
1581 if (r < 0)
1582 return r;
1583
1584 HASHMAP_FOREACH(service, scope->manager->dnssd_services) {
1585 dns_zone_remove_rr(&scope->zone, service->ptr_rr);
1586 dns_zone_remove_rr(&scope->zone, service->srv_rr);
1587 LIST_FOREACH(items, txt_data, service->txt_data_items)
1588 dns_zone_remove_rr(&scope->zone, txt_data->rr);
1589 }
1590
1591 return 0;
1592 }
1593
1594 static bool dns_scope_has_route_only_domains(DnsScope *scope) {
1595 DnsSearchDomain *first;
1596 bool route_only = false;
1597
1598 assert(scope);
1599 assert(scope->protocol == DNS_PROTOCOL_DNS);
1600
1601 /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check
1602 * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links
1603 * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to
1604 * take queries to arbitrary domains, i.e. has no routing domains set. */
1605
1606 if (scope->link)
1607 first = scope->link->search_domains;
1608 else
1609 first = scope->manager->search_domains;
1610
1611 LIST_FOREACH(domains, domain, first) {
1612 /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early
1613 * here, as it doesn't really matter whether this link has any route-only domains or not,
1614 * "~." really trumps everything and clearly indicates that this interface shall receive all
1615 * traffic it can get. */
1616 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain)))
1617 return false;
1618
1619 if (domain->route_only)
1620 route_only = true;
1621 }
1622
1623 return route_only;
1624 }
1625
1626 bool dns_scope_is_default_route(DnsScope *scope) {
1627 assert(scope);
1628
1629 /* Only use DNS scopes as default routes */
1630 if (scope->protocol != DNS_PROTOCOL_DNS)
1631 return false;
1632
1633 /* The global DNS scope is always suitable as default route */
1634 if (!scope->link)
1635 return true;
1636
1637 /* Honour whatever is explicitly configured. This is really the best approach, and trumps any
1638 * automatic logic. */
1639 if (scope->link->default_route >= 0)
1640 return scope->link->default_route;
1641
1642 /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not
1643 * volunteer as default route. */
1644 return !dns_scope_has_route_only_domains(scope);
1645 }
1646
1647 int dns_scope_dump_cache_to_json(DnsScope *scope, JsonVariant **ret) {
1648 _cleanup_(json_variant_unrefp) JsonVariant *cache = NULL;
1649 int r;
1650
1651 assert(scope);
1652 assert(ret);
1653
1654 r = dns_cache_dump_to_json(&scope->cache, &cache);
1655 if (r < 0)
1656 return r;
1657
1658 return json_build(ret,
1659 JSON_BUILD_OBJECT(
1660 JSON_BUILD_PAIR_STRING("protocol", dns_protocol_to_string(scope->protocol)),
1661 JSON_BUILD_PAIR_CONDITION(scope->family != AF_UNSPEC, "family", JSON_BUILD_INTEGER(scope->family)),
1662 JSON_BUILD_PAIR_CONDITION(scope->link, "ifindex", JSON_BUILD_INTEGER(scope->link ? scope->link->ifindex : 0)),
1663 JSON_BUILD_PAIR_CONDITION(scope->link, "ifname", JSON_BUILD_STRING(scope->link ? scope->link->ifname : NULL)),
1664 JSON_BUILD_PAIR_VARIANT("cache", cache)));
1665 }
Unnamed repository; edit this file 'description' to name the repository.