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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
74b2466e | 2 | |
ad867662 LP |
3 | #include <netinet/tcp.h> |
4 | ||
46f08bea | 5 | #include "af-list.h" |
b5efdb8a | 6 | #include "alloc-util.h" |
4ad7f276 | 7 | #include "dns-domain.h" |
3ffd4af2 LP |
8 | #include "fd-util.h" |
9 | #include "hostname-util.h" | |
f5947a5e | 10 | #include "missing_network.h" |
3ffd4af2 | 11 | #include "random-util.h" |
6db6a464 | 12 | #include "resolved-dnssd.h" |
74b2466e | 13 | #include "resolved-dns-scope.h" |
a2bf8a19 | 14 | #include "resolved-dns-zone.h" |
3ffd4af2 | 15 | #include "resolved-llmnr.h" |
b4f1862d | 16 | #include "resolved-mdns.h" |
3ffd4af2 LP |
17 | #include "socket-util.h" |
18 | #include "strv.h" | |
74b2466e | 19 | |
aea2429d LP |
20 | #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC) |
21 | #define MULTICAST_RATELIMIT_BURST 1000 | |
22 | ||
9df3ba6c TG |
23 | /* After how much time to repeat LLMNR requests, see RFC 4795 Section 7 */ |
24 | #define MULTICAST_RESEND_TIMEOUT_MIN_USEC (100 * USEC_PER_MSEC) | |
25 | #define MULTICAST_RESEND_TIMEOUT_MAX_USEC (1 * USEC_PER_SEC) | |
26 | ||
0dd25fb9 | 27 | int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) { |
74b2466e LP |
28 | DnsScope *s; |
29 | ||
30 | assert(m); | |
31 | assert(ret); | |
32 | ||
9a1bbc66 | 33 | s = new(DnsScope, 1); |
74b2466e LP |
34 | if (!s) |
35 | return -ENOMEM; | |
36 | ||
9a1bbc66 LP |
37 | *s = (DnsScope) { |
38 | .manager = m, | |
39 | .link = l, | |
40 | .protocol = protocol, | |
41 | .family = family, | |
42 | .resend_timeout = MULTICAST_RESEND_TIMEOUT_MIN_USEC, | |
43 | }; | |
74b2466e | 44 | |
ad6c0475 LP |
45 | if (protocol == DNS_PROTOCOL_DNS) { |
46 | /* Copy DNSSEC mode from the link if it is set there, | |
47 | * otherwise take the manager's DNSSEC mode. Note that | |
48 | * we copy this only at scope creation time, and do | |
49 | * not update it from the on, even if the setting | |
50 | * changes. */ | |
51 | ||
d050561a | 52 | if (l) { |
c69fa7e3 | 53 | s->dnssec_mode = link_get_dnssec_mode(l); |
c9299be2 | 54 | s->dns_over_tls_mode = link_get_dns_over_tls_mode(l); |
d050561a | 55 | } else { |
c69fa7e3 | 56 | s->dnssec_mode = manager_get_dnssec_mode(m); |
c9299be2 | 57 | s->dns_over_tls_mode = manager_get_dns_over_tls_mode(m); |
d050561a | 58 | } |
5d67a7ae | 59 | |
5d67a7ae | 60 | } else { |
658f7f02 | 61 | s->dnssec_mode = DNSSEC_NO; |
c9299be2 | 62 | s->dns_over_tls_mode = DNS_OVER_TLS_NO; |
5d67a7ae | 63 | } |
ad6c0475 | 64 | |
74b2466e LP |
65 | LIST_PREPEND(scopes, m->dns_scopes, s); |
66 | ||
1716f6dc | 67 | dns_scope_llmnr_membership(s, true); |
0db4c90a | 68 | dns_scope_mdns_membership(s, true); |
1716f6dc | 69 | |
6ff79f76 | 70 | 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)); |
1716f6dc | 71 | |
aea2429d | 72 | /* Enforce ratelimiting for the multicast protocols */ |
8c227e7f | 73 | s->ratelimit = (RateLimit) { MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST }; |
aea2429d | 74 | |
74b2466e LP |
75 | *ret = s; |
76 | return 0; | |
77 | } | |
78 | ||
801ad6a6 | 79 | static void dns_scope_abort_transactions(DnsScope *s) { |
801ad6a6 | 80 | assert(s); |
1716f6dc | 81 | |
f9ebb22a LP |
82 | while (s->transactions) { |
83 | DnsTransaction *t = s->transactions; | |
84 | ||
faa133f3 LP |
85 | /* Abort the transaction, but make sure it is not |
86 | * freed while we still look at it */ | |
74b2466e | 87 | |
faa133f3 | 88 | t->block_gc++; |
f4e38037 LP |
89 | if (DNS_TRANSACTION_IS_LIVE(t->state)) |
90 | dns_transaction_complete(t, DNS_TRANSACTION_ABORTED); | |
faa133f3 | 91 | t->block_gc--; |
74b2466e | 92 | |
ec2c5e43 | 93 | dns_transaction_free(t); |
74b2466e | 94 | } |
801ad6a6 LP |
95 | } |
96 | ||
97 | DnsScope* dns_scope_free(DnsScope *s) { | |
801ad6a6 LP |
98 | if (!s) |
99 | return NULL; | |
100 | ||
6ff79f76 | 101 | 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)); |
801ad6a6 LP |
102 | |
103 | dns_scope_llmnr_membership(s, false); | |
0db4c90a | 104 | dns_scope_mdns_membership(s, false); |
801ad6a6 LP |
105 | dns_scope_abort_transactions(s); |
106 | ||
107 | while (s->query_candidates) | |
108 | dns_query_candidate_free(s->query_candidates); | |
74b2466e | 109 | |
f9ebb22a | 110 | hashmap_free(s->transactions_by_key); |
da0c630e | 111 | |
224b0e7a | 112 | ordered_hashmap_free_with_destructor(s->conflict_queue, dns_resource_record_unref); |
a4076574 LP |
113 | sd_event_source_unref(s->conflict_event_source); |
114 | ||
53fda2bb DR |
115 | sd_event_source_unref(s->announce_event_source); |
116 | ||
322345fd | 117 | dns_cache_flush(&s->cache); |
623a4c97 | 118 | dns_zone_flush(&s->zone); |
322345fd | 119 | |
74b2466e | 120 | LIST_REMOVE(scopes, s->manager->dns_scopes, s); |
6b430fdb | 121 | return mfree(s); |
74b2466e LP |
122 | } |
123 | ||
2c27fbca | 124 | DnsServer *dns_scope_get_dns_server(DnsScope *s) { |
74b2466e LP |
125 | assert(s); |
126 | ||
1716f6dc LP |
127 | if (s->protocol != DNS_PROTOCOL_DNS) |
128 | return NULL; | |
129 | ||
74b2466e LP |
130 | if (s->link) |
131 | return link_get_dns_server(s->link); | |
132 | else | |
133 | return manager_get_dns_server(s->manager); | |
134 | } | |
135 | ||
44db02d0 LP |
136 | unsigned dns_scope_get_n_dns_servers(DnsScope *s) { |
137 | unsigned n = 0; | |
138 | DnsServer *i; | |
139 | ||
140 | assert(s); | |
141 | ||
142 | if (s->protocol != DNS_PROTOCOL_DNS) | |
143 | return 0; | |
144 | ||
145 | if (s->link) | |
146 | i = s->link->dns_servers; | |
147 | else | |
148 | i = s->manager->dns_servers; | |
149 | ||
150 | for (; i; i = i->servers_next) | |
151 | n++; | |
152 | ||
153 | return n; | |
154 | } | |
155 | ||
74b2466e LP |
156 | void dns_scope_next_dns_server(DnsScope *s) { |
157 | assert(s); | |
158 | ||
1716f6dc LP |
159 | if (s->protocol != DNS_PROTOCOL_DNS) |
160 | return; | |
161 | ||
74b2466e LP |
162 | if (s->link) |
163 | link_next_dns_server(s->link); | |
164 | else | |
165 | manager_next_dns_server(s->manager); | |
166 | } | |
167 | ||
9df3ba6c TG |
168 | void dns_scope_packet_received(DnsScope *s, usec_t rtt) { |
169 | assert(s); | |
170 | ||
84129d46 LP |
171 | if (rtt <= s->max_rtt) |
172 | return; | |
173 | ||
174 | s->max_rtt = rtt; | |
175 | s->resend_timeout = MIN(MAX(MULTICAST_RESEND_TIMEOUT_MIN_USEC, s->max_rtt * 2), MULTICAST_RESEND_TIMEOUT_MAX_USEC); | |
9df3ba6c TG |
176 | } |
177 | ||
178 | void dns_scope_packet_lost(DnsScope *s, usec_t usec) { | |
179 | assert(s); | |
180 | ||
181 | if (s->resend_timeout <= usec) | |
182 | s->resend_timeout = MIN(s->resend_timeout * 2, MULTICAST_RESEND_TIMEOUT_MAX_USEC); | |
183 | } | |
184 | ||
519ef046 | 185 | static int dns_scope_emit_one(DnsScope *s, int fd, DnsPacket *p) { |
1716f6dc LP |
186 | union in_addr_union addr; |
187 | int ifindex = 0, r; | |
0dd25fb9 | 188 | int family; |
1716f6dc | 189 | uint32_t mtu; |
74b2466e LP |
190 | |
191 | assert(s); | |
192 | assert(p); | |
1716f6dc | 193 | assert(p->protocol == s->protocol); |
ad867662 LP |
194 | |
195 | if (s->link) { | |
1716f6dc | 196 | mtu = s->link->mtu; |
74b2466e | 197 | ifindex = s->link->ifindex; |
1716f6dc | 198 | } else |
e1c95994 | 199 | mtu = manager_find_mtu(s->manager); |
74b2466e | 200 | |
106784eb | 201 | switch (s->protocol) { |
519ef046 | 202 | |
106784eb | 203 | case DNS_PROTOCOL_DNS: |
519ef046 | 204 | assert(fd >= 0); |
9c5e12a4 | 205 | |
623a4c97 | 206 | if (DNS_PACKET_QDCOUNT(p) > 1) |
15411c0c | 207 | return -EOPNOTSUPP; |
623a4c97 | 208 | |
1716f6dc LP |
209 | if (p->size > DNS_PACKET_UNICAST_SIZE_MAX) |
210 | return -EMSGSIZE; | |
211 | ||
a0166609 | 212 | if (p->size + UDP_PACKET_HEADER_SIZE > mtu) |
1716f6dc LP |
213 | return -EMSGSIZE; |
214 | ||
72290734 TG |
215 | r = manager_write(s->manager, fd, p); |
216 | if (r < 0) | |
217 | return r; | |
218 | ||
106784eb | 219 | break; |
1716f6dc | 220 | |
106784eb | 221 | case DNS_PROTOCOL_LLMNR: |
519ef046 LP |
222 | assert(fd < 0); |
223 | ||
1716f6dc | 224 | if (DNS_PACKET_QDCOUNT(p) > 1) |
15411c0c | 225 | return -EOPNOTSUPP; |
1716f6dc | 226 | |
7994ac1d | 227 | if (!ratelimit_below(&s->ratelimit)) |
aea2429d LP |
228 | return -EBUSY; |
229 | ||
1716f6dc | 230 | family = s->family; |
1716f6dc LP |
231 | |
232 | if (family == AF_INET) { | |
233 | addr.in = LLMNR_MULTICAST_IPV4_ADDRESS; | |
1716f6dc LP |
234 | fd = manager_llmnr_ipv4_udp_fd(s->manager); |
235 | } else if (family == AF_INET6) { | |
236 | addr.in6 = LLMNR_MULTICAST_IPV6_ADDRESS; | |
237 | fd = manager_llmnr_ipv6_udp_fd(s->manager); | |
1716f6dc LP |
238 | } else |
239 | return -EAFNOSUPPORT; | |
240 | if (fd < 0) | |
241 | return fd; | |
72290734 | 242 | |
b30bf55d | 243 | r = manager_send(s->manager, fd, ifindex, family, &addr, LLMNR_PORT, NULL, p); |
b4f1862d DM |
244 | if (r < 0) |
245 | return r; | |
246 | ||
247 | break; | |
248 | ||
249 | case DNS_PROTOCOL_MDNS: | |
519ef046 LP |
250 | assert(fd < 0); |
251 | ||
7994ac1d | 252 | if (!ratelimit_below(&s->ratelimit)) |
b4f1862d DM |
253 | return -EBUSY; |
254 | ||
255 | family = s->family; | |
256 | ||
257 | if (family == AF_INET) { | |
258 | addr.in = MDNS_MULTICAST_IPV4_ADDRESS; | |
259 | fd = manager_mdns_ipv4_fd(s->manager); | |
260 | } else if (family == AF_INET6) { | |
261 | addr.in6 = MDNS_MULTICAST_IPV6_ADDRESS; | |
262 | fd = manager_mdns_ipv6_fd(s->manager); | |
263 | } else | |
264 | return -EAFNOSUPPORT; | |
265 | if (fd < 0) | |
266 | return fd; | |
267 | ||
b30bf55d | 268 | r = manager_send(s->manager, fd, ifindex, family, &addr, MDNS_PORT, NULL, p); |
72290734 TG |
269 | if (r < 0) |
270 | return r; | |
106784eb DM |
271 | |
272 | break; | |
273 | ||
274 | default: | |
74b2466e | 275 | return -EAFNOSUPPORT; |
106784eb | 276 | } |
74b2466e | 277 | |
74b2466e LP |
278 | return 1; |
279 | } | |
280 | ||
519ef046 | 281 | int dns_scope_emit_udp(DnsScope *s, int fd, DnsPacket *p) { |
80a62095 DM |
282 | int r; |
283 | ||
284 | assert(s); | |
285 | assert(p); | |
286 | assert(p->protocol == s->protocol); | |
519ef046 | 287 | assert((s->protocol == DNS_PROTOCOL_DNS) == (fd >= 0)); |
80a62095 DM |
288 | |
289 | do { | |
290 | /* If there are multiple linked packets, set the TC bit in all but the last of them */ | |
291 | if (p->more) { | |
292 | assert(p->protocol == DNS_PROTOCOL_MDNS); | |
261f3673 | 293 | dns_packet_set_flags(p, true, true); |
80a62095 DM |
294 | } |
295 | ||
519ef046 | 296 | r = dns_scope_emit_one(s, fd, p); |
80a62095 DM |
297 | if (r < 0) |
298 | return r; | |
299 | ||
300 | p = p->more; | |
519ef046 | 301 | } while (p); |
80a62095 DM |
302 | |
303 | return 0; | |
304 | } | |
305 | ||
519ef046 LP |
306 | static int dns_scope_socket( |
307 | DnsScope *s, | |
308 | int type, | |
309 | int family, | |
310 | const union in_addr_union *address, | |
311 | DnsServer *server, | |
91ccab1e IT |
312 | uint16_t port, |
313 | union sockaddr_union *ret_socket_address) { | |
519ef046 | 314 | |
ad867662 | 315 | _cleanup_close_ int fd = -1; |
91ccab1e | 316 | union sockaddr_union sa; |
ad867662 | 317 | socklen_t salen; |
c10d6bdb | 318 | int r, ifindex; |
ad867662 LP |
319 | |
320 | assert(s); | |
be808ea0 | 321 | |
519ef046 LP |
322 | if (server) { |
323 | assert(family == AF_UNSPEC); | |
324 | assert(!address); | |
be808ea0 | 325 | |
2817157b LP |
326 | ifindex = dns_server_ifindex(server); |
327 | ||
7b3bae21 YW |
328 | switch (server->family) { |
329 | case AF_INET: | |
330 | sa = (union sockaddr_union) { | |
331 | .in.sin_family = server->family, | |
332 | .in.sin_port = htobe16(port), | |
333 | .in.sin_addr = server->address.in, | |
334 | }; | |
623a4c97 | 335 | salen = sizeof(sa.in); |
7b3bae21 YW |
336 | break; |
337 | case AF_INET6: | |
338 | sa = (union sockaddr_union) { | |
339 | .in6.sin6_family = server->family, | |
340 | .in6.sin6_port = htobe16(port), | |
341 | .in6.sin6_addr = server->address.in6, | |
342 | .in6.sin6_scope_id = ifindex, | |
343 | }; | |
623a4c97 | 344 | salen = sizeof(sa.in6); |
7b3bae21 YW |
345 | break; |
346 | default: | |
623a4c97 | 347 | return -EAFNOSUPPORT; |
7b3bae21 | 348 | } |
623a4c97 | 349 | } else { |
519ef046 LP |
350 | assert(family != AF_UNSPEC); |
351 | assert(address); | |
352 | ||
2817157b | 353 | ifindex = s->link ? s->link->ifindex : 0; |
623a4c97 | 354 | |
7b3bae21 YW |
355 | switch (family) { |
356 | case AF_INET: | |
357 | sa = (union sockaddr_union) { | |
358 | .in.sin_family = family, | |
359 | .in.sin_port = htobe16(port), | |
360 | .in.sin_addr = address->in, | |
361 | }; | |
623a4c97 | 362 | salen = sizeof(sa.in); |
7b3bae21 YW |
363 | break; |
364 | case AF_INET6: | |
365 | sa = (union sockaddr_union) { | |
366 | .in6.sin6_family = family, | |
367 | .in6.sin6_port = htobe16(port), | |
368 | .in6.sin6_addr = address->in6, | |
369 | .in6.sin6_scope_id = ifindex, | |
370 | }; | |
623a4c97 | 371 | salen = sizeof(sa.in6); |
7b3bae21 YW |
372 | break; |
373 | default: | |
623a4c97 | 374 | return -EAFNOSUPPORT; |
7b3bae21 | 375 | } |
623a4c97 | 376 | } |
ad867662 | 377 | |
0db64366 | 378 | fd = socket(sa.sa.sa_family, type|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
ad867662 LP |
379 | if (fd < 0) |
380 | return -errno; | |
381 | ||
0db64366 | 382 | if (type == SOCK_STREAM) { |
2ff48e98 | 383 | r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true); |
0db64366 | 384 | if (r < 0) |
2ff48e98 | 385 | return r; |
0db64366 | 386 | } |
623a4c97 LP |
387 | |
388 | if (s->link) { | |
5d0fe423 LP |
389 | r = socket_set_unicast_if(fd, sa.sa.sa_family, ifindex); |
390 | if (r < 0) | |
391 | return r; | |
623a4c97 LP |
392 | } |
393 | ||
394 | if (s->protocol == DNS_PROTOCOL_LLMNR) { | |
bf3f1271 | 395 | /* RFC 4795, section 2.5 requires the TTL to be set to 1 */ |
5d0fe423 LP |
396 | r = socket_set_ttl(fd, sa.sa.sa_family, 1); |
397 | if (r < 0) | |
398 | return r; | |
623a4c97 | 399 | } |
ad867662 | 400 | |
9fcdab9c YW |
401 | if (type == SOCK_DGRAM) { |
402 | /* Set IP_RECVERR or IPV6_RECVERR to get ICMP error feedback. See discussion in #10345. */ | |
5d0fe423 LP |
403 | r = socket_set_recverr(fd, sa.sa.sa_family, true); |
404 | if (r < 0) | |
405 | return r; | |
c9e69182 | 406 | |
5d0fe423 LP |
407 | r = socket_set_recvpktinfo(fd, sa.sa.sa_family, true); |
408 | if (r < 0) | |
409 | return r; | |
9fcdab9c YW |
410 | } |
411 | ||
91ccab1e IT |
412 | if (ret_socket_address) |
413 | *ret_socket_address = sa; | |
414 | else { | |
415 | r = connect(fd, &sa.sa, salen); | |
416 | if (r < 0 && errno != EINPROGRESS) | |
417 | return -errno; | |
418 | } | |
ad867662 | 419 | |
c10d6bdb | 420 | return TAKE_FD(fd); |
ad867662 LP |
421 | } |
422 | ||
da9de738 YW |
423 | int dns_scope_socket_udp(DnsScope *s, DnsServer *server) { |
424 | return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, dns_server_port(server), NULL); | |
0db64366 TG |
425 | } |
426 | ||
91ccab1e | 427 | 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) { |
5238e957 | 428 | /* If ret_socket_address is not NULL, the caller is responsible |
91ccab1e IT |
429 | * for calling connect() or sendmsg(). This is required by TCP |
430 | * Fast Open, to be able to send the initial SYN packet along | |
431 | * with the first data packet. */ | |
432 | return dns_scope_socket(s, SOCK_STREAM, family, address, server, port, ret_socket_address); | |
0db64366 TG |
433 | } |
434 | ||
17508549 LP |
435 | static DnsScopeMatch accept_link_local_reverse_lookups(const char *domain) { |
436 | assert(domain); | |
437 | ||
438 | if (dns_name_endswith(domain, "254.169.in-addr.arpa") > 0) | |
439 | return DNS_SCOPE_YES_BASE + 4; /* 4 labels match */ | |
440 | ||
441 | if (dns_name_endswith(domain, "8.e.f.ip6.arpa") > 0 || | |
442 | dns_name_endswith(domain, "9.e.f.ip6.arpa") > 0 || | |
443 | dns_name_endswith(domain, "a.e.f.ip6.arpa") > 0 || | |
444 | dns_name_endswith(domain, "b.e.f.ip6.arpa") > 0) | |
445 | return DNS_SCOPE_YES_BASE + 5; /* 5 labels match */ | |
446 | ||
447 | return _DNS_SCOPE_MATCH_INVALID; | |
448 | } | |
449 | ||
a97a3b25 LP |
450 | DnsScopeMatch dns_scope_good_domain( |
451 | DnsScope *s, | |
452 | int ifindex, | |
453 | uint64_t flags, | |
454 | const char *domain) { | |
455 | ||
a51c1048 | 456 | DnsSearchDomain *d; |
74b2466e | 457 | |
a97a3b25 LP |
458 | /* This returns the following return values: |
459 | * | |
460 | * DNS_SCOPE_NO → This scope is not suitable for lookups of this domain, at all | |
461 | * DNS_SCOPE_MAYBE → This scope is suitable, but only if nothing else wants it | |
462 | * DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match | |
463 | * | |
464 | * (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return | |
465 | * DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those | |
466 | * which returned DNS_SCOPE_NO.) | |
467 | */ | |
468 | ||
74b2466e LP |
469 | assert(s); |
470 | assert(domain); | |
471 | ||
3d334c40 ZJS |
472 | /* Checks if the specified domain is something to look up on this scope. Note that this accepts |
473 | * non-qualified hostnames, i.e. those without any search path suffixed. */ | |
28b9b764 | 474 | |
51323288 LP |
475 | if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex)) |
476 | return DNS_SCOPE_NO; | |
477 | ||
931851e8 | 478 | if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & flags) == 0) |
51323288 LP |
479 | return DNS_SCOPE_NO; |
480 | ||
78c6a153 LP |
481 | /* Never resolve any loopback hostname or IP address via DNS, |
482 | * LLMNR or mDNS. Instead, always rely on synthesized RRs for | |
483 | * these. */ | |
484 | if (is_localhost(domain) || | |
485 | dns_name_endswith(domain, "127.in-addr.arpa") > 0 || | |
9436e8ca LP |
486 | 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) |
487 | return DNS_SCOPE_NO; | |
488 | ||
c9ad0edb LP |
489 | /* Never respond to some of the domains listed in RFC6303 */ |
490 | if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 || | |
491 | dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 || | |
492 | 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) | |
493 | return DNS_SCOPE_NO; | |
494 | ||
7bcffc2e LP |
495 | /* Never respond to some of the domains listed in RFC6761 */ |
496 | if (dns_name_endswith(domain, "invalid") > 0) | |
497 | return DNS_SCOPE_NO; | |
498 | ||
106784eb | 499 | switch (s->protocol) { |
801ad6a6 | 500 | |
613dca46 | 501 | case DNS_PROTOCOL_DNS: { |
fea46786 | 502 | bool has_search_domains = false; |
a97a3b25 | 503 | int n_best = -1; |
613dca46 LP |
504 | |
505 | /* Never route things to scopes that lack DNS servers */ | |
f76fa088 | 506 | if (!dns_scope_get_dns_server(s)) |
613dca46 LP |
507 | return DNS_SCOPE_NO; |
508 | ||
509 | /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that | |
510 | * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes | |
511 | * won't be considered anymore. */ | |
fea46786 LP |
512 | LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) { |
513 | ||
514 | if (!d->route_only && !dns_name_is_root(d->name)) | |
515 | has_search_domains = true; | |
516 | ||
a97a3b25 LP |
517 | if (dns_name_endswith(domain, d->name) > 0) { |
518 | int c; | |
519 | ||
520 | c = dns_name_count_labels(d->name); | |
521 | if (c < 0) | |
522 | continue; | |
523 | ||
524 | if (c > n_best) | |
525 | n_best = c; | |
526 | } | |
fea46786 LP |
527 | } |
528 | ||
529 | /* If there's a true search domain defined for this scope, and the query is single-label, | |
530 | * then let's resolve things here, prefereably. Note that LLMNR considers itself | |
531 | * authoritative for single-label names too, at the same preference, see below. */ | |
532 | if (has_search_domains && dns_name_is_single_label(domain)) | |
533 | return DNS_SCOPE_YES_BASE + 1; | |
a97a3b25 LP |
534 | |
535 | /* Let's return the number of labels in the best matching result */ | |
536 | if (n_best >= 0) { | |
537 | assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE); | |
538 | return DNS_SCOPE_YES_BASE + n_best; | |
539 | } | |
613dca46 | 540 | |
ca5394d2 LP |
541 | /* See if this scope is suitable as default route. */ |
542 | if (!dns_scope_is_default_route(s)) | |
613dca46 | 543 | return DNS_SCOPE_NO; |
801ad6a6 | 544 | |
28b9b764 LP |
545 | /* Exclude link-local IP ranges */ |
546 | if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 && | |
c9ad0edb LP |
547 | dns_name_endswith(domain, "8.e.f.ip6.arpa") == 0 && |
548 | dns_name_endswith(domain, "9.e.f.ip6.arpa") == 0 && | |
549 | dns_name_endswith(domain, "a.e.f.ip6.arpa") == 0 && | |
b43d96b0 DM |
550 | dns_name_endswith(domain, "b.e.f.ip6.arpa") == 0 && |
551 | /* If networks use .local in their private setups, they are supposed to also add .local to their search | |
552 | * domains, which we already checked above. Otherwise, we consider .local specific to mDNS and won't | |
553 | * send such queries ordinary DNS servers. */ | |
554 | dns_name_endswith(domain, "local") == 0) | |
faa133f3 | 555 | return DNS_SCOPE_MAYBE; |
1716f6dc | 556 | |
faa133f3 | 557 | return DNS_SCOPE_NO; |
613dca46 | 558 | } |
1716f6dc | 559 | |
17508549 LP |
560 | case DNS_PROTOCOL_MDNS: { |
561 | DnsScopeMatch m; | |
562 | ||
563 | m = accept_link_local_reverse_lookups(domain); | |
564 | if (m >= 0) | |
565 | return m; | |
566 | ||
78c6a153 | 567 | if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) || |
17508549 LP |
568 | (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0)) |
569 | return DNS_SCOPE_MAYBE; | |
570 | ||
571 | if ((dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */ | |
78c6a153 LP |
572 | dns_name_equal(domain, "local") == 0 && /* but not the single-label "local" name itself */ |
573 | manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */ | |
17508549 | 574 | return DNS_SCOPE_YES_BASE + 1; /* Return +1, as the top-level .local domain matches, i.e. one label */ |
74b2466e LP |
575 | |
576 | return DNS_SCOPE_NO; | |
17508549 LP |
577 | } |
578 | ||
579 | case DNS_PROTOCOL_LLMNR: { | |
580 | DnsScopeMatch m; | |
581 | ||
582 | m = accept_link_local_reverse_lookups(domain); | |
583 | if (m >= 0) | |
584 | return m; | |
74b2466e | 585 | |
78c6a153 | 586 | if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) || |
17508549 LP |
587 | (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0)) |
588 | return DNS_SCOPE_MAYBE; | |
589 | ||
590 | if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */ | |
78c6a153 | 591 | !is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */ |
088648d0 | 592 | dns_name_equal(domain, "local") == 0 && /* don't resolve "local" with LLMNR, it's the top-level domain of mDNS after all, see above */ |
78c6a153 | 593 | manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via LLMNR */ |
fea46786 LP |
594 | return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative |
595 | * for single-label names, i.e. one label. This is | |
3b5bd7d6 | 596 | * particularly relevant as it means a "." route on some |
fea46786 LP |
597 | * other scope won't pull all traffic away from |
598 | * us. (If people actually want to pull traffic away | |
599 | * from us they should turn off LLMNR on the | |
600 | * link). Note that unicast DNS scopes with search | |
601 | * domains also consider themselves authoritative for | |
602 | * single-label domains, at the same preference (see | |
603 | * above). */ | |
74b2466e | 604 | |
1716f6dc | 605 | return DNS_SCOPE_NO; |
17508549 | 606 | } |
74b2466e | 607 | |
106784eb DM |
608 | default: |
609 | assert_not_reached("Unknown scope protocol"); | |
610 | } | |
1716f6dc LP |
611 | } |
612 | ||
011696f7 LP |
613 | bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) { |
614 | int key_family; | |
615 | ||
1716f6dc LP |
616 | assert(s); |
617 | assert(key); | |
618 | ||
28b9b764 LP |
619 | /* Check if it makes sense to resolve the specified key on |
620 | * this scope. Note that this call assumes as fully qualified | |
621 | * name, i.e. the search suffixes already appended. */ | |
622 | ||
011696f7 LP |
623 | if (key->class != DNS_CLASS_IN) |
624 | return false; | |
625 | ||
28b9b764 LP |
626 | if (s->protocol == DNS_PROTOCOL_DNS) { |
627 | ||
3b5bd7d6 ZJS |
628 | /* On classic DNS, looking up non-address RRs is always fine. (Specifically, we want to |
629 | * permit looking up DNSKEY and DS records on the root and top-level domains.) */ | |
28b9b764 LP |
630 | if (!dns_resource_key_is_address(key)) |
631 | return true; | |
632 | ||
3b5bd7d6 ZJS |
633 | /* Unless explicitly overridden, we refuse to look up A and AAAA RRs on the root and |
634 | * single-label domains, under the assumption that those should be resolved via LLMNR or | |
635 | * search path only, and should not be leaked onto the internet. */ | |
636 | const char* name = dns_resource_key_name(key); | |
637 | ||
638 | if (!s->manager->resolve_unicast_single_label && | |
639 | dns_name_is_single_label(name)) | |
640 | return false; | |
641 | ||
642 | return !dns_name_is_root(name); | |
28b9b764 | 643 | } |
1716f6dc LP |
644 | |
645 | /* On mDNS and LLMNR, send A and AAAA queries only on the | |
646 | * respective scopes */ | |
647 | ||
011696f7 LP |
648 | key_family = dns_type_to_af(key->type); |
649 | if (key_family < 0) | |
650 | return true; | |
1716f6dc | 651 | |
011696f7 | 652 | return key_family == s->family; |
1716f6dc LP |
653 | } |
654 | ||
0db4c90a | 655 | static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) { |
1716f6dc LP |
656 | int fd; |
657 | ||
5ba73e9b | 658 | assert(s); |
5ba73e9b LP |
659 | assert(s->link); |
660 | ||
1716f6dc LP |
661 | if (s->family == AF_INET) { |
662 | struct ip_mreqn mreqn = { | |
0db4c90a | 663 | .imr_multiaddr = in, |
1716f6dc LP |
664 | .imr_ifindex = s->link->ifindex, |
665 | }; | |
666 | ||
d37baf40 DR |
667 | if (s->protocol == DNS_PROTOCOL_LLMNR) |
668 | fd = manager_llmnr_ipv4_udp_fd(s->manager); | |
669 | else | |
670 | fd = manager_mdns_ipv4_fd(s->manager); | |
671 | ||
1716f6dc LP |
672 | if (fd < 0) |
673 | return fd; | |
674 | ||
7b4c2ee7 LP |
675 | /* Always first try to drop membership before we add |
676 | * one. This is necessary on some devices, such as | |
677 | * veth. */ | |
678 | if (b) | |
dc751688 | 679 | (void) setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)); |
7b4c2ee7 | 680 | |
1716f6dc LP |
681 | if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0) |
682 | return -errno; | |
683 | ||
684 | } else if (s->family == AF_INET6) { | |
685 | struct ipv6_mreq mreq = { | |
0db4c90a | 686 | .ipv6mr_multiaddr = in6, |
1716f6dc LP |
687 | .ipv6mr_interface = s->link->ifindex, |
688 | }; | |
689 | ||
d37baf40 DR |
690 | if (s->protocol == DNS_PROTOCOL_LLMNR) |
691 | fd = manager_llmnr_ipv6_udp_fd(s->manager); | |
692 | else | |
693 | fd = manager_mdns_ipv6_fd(s->manager); | |
694 | ||
1716f6dc LP |
695 | if (fd < 0) |
696 | return fd; | |
697 | ||
7b4c2ee7 | 698 | if (b) |
dc751688 | 699 | (void) setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)); |
7b4c2ee7 | 700 | |
1716f6dc LP |
701 | if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) |
702 | return -errno; | |
703 | } else | |
704 | return -EAFNOSUPPORT; | |
705 | ||
706 | return 0; | |
74b2466e | 707 | } |
623a4c97 | 708 | |
0db4c90a | 709 | int dns_scope_llmnr_membership(DnsScope *s, bool b) { |
f471bc11 | 710 | assert(s); |
0db4c90a DM |
711 | |
712 | if (s->protocol != DNS_PROTOCOL_LLMNR) | |
713 | return 0; | |
714 | ||
715 | return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS); | |
716 | } | |
717 | ||
718 | int dns_scope_mdns_membership(DnsScope *s, bool b) { | |
f471bc11 | 719 | assert(s); |
0db4c90a DM |
720 | |
721 | if (s->protocol != DNS_PROTOCOL_MDNS) | |
722 | return 0; | |
723 | ||
724 | return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS); | |
725 | } | |
726 | ||
3b991089 | 727 | int dns_scope_make_reply_packet( |
ec2c5e43 LP |
728 | DnsScope *s, |
729 | uint16_t id, | |
730 | int rcode, | |
731 | DnsQuestion *q, | |
732 | DnsAnswer *answer, | |
733 | DnsAnswer *soa, | |
734 | bool tentative, | |
735 | DnsPacket **ret) { | |
736 | ||
623a4c97 | 737 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
623a4c97 LP |
738 | int r; |
739 | ||
740 | assert(s); | |
a4076574 | 741 | assert(ret); |
623a4c97 | 742 | |
501e8eb0 LP |
743 | if (dns_question_isempty(q) && |
744 | dns_answer_isempty(answer) && | |
745 | dns_answer_isempty(soa)) | |
623a4c97 LP |
746 | return -EINVAL; |
747 | ||
51027656 | 748 | r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX); |
623a4c97 LP |
749 | if (r < 0) |
750 | return r; | |
751 | ||
752 | DNS_PACKET_HEADER(p)->id = id; | |
ea917db9 LP |
753 | DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( |
754 | 1 /* qr */, | |
755 | 0 /* opcode */, | |
756 | 0 /* c */, | |
757 | 0 /* tc */, | |
ec2c5e43 | 758 | tentative, |
ea917db9 LP |
759 | 0 /* (ra) */, |
760 | 0 /* (ad) */, | |
761 | 0 /* (cd) */, | |
762 | rcode)); | |
623a4c97 | 763 | |
f471bc11 LP |
764 | r = dns_packet_append_question(p, q); |
765 | if (r < 0) | |
766 | return r; | |
767 | DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q)); | |
8bf52d3d | 768 | |
f471bc11 LP |
769 | r = dns_packet_append_answer(p, answer); |
770 | if (r < 0) | |
771 | return r; | |
772 | DNS_PACKET_HEADER(p)->ancount = htobe16(dns_answer_size(answer)); | |
8bf52d3d | 773 | |
f471bc11 LP |
774 | r = dns_packet_append_answer(p, soa); |
775 | if (r < 0) | |
776 | return r; | |
777 | DNS_PACKET_HEADER(p)->arcount = htobe16(dns_answer_size(soa)); | |
623a4c97 | 778 | |
1cc6c93a | 779 | *ret = TAKE_PTR(p); |
623a4c97 LP |
780 | |
781 | return 0; | |
782 | } | |
783 | ||
a4076574 | 784 | static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) { |
2a3900d7 LP |
785 | DnsResourceRecord *rr; |
786 | DnsResourceKey *key; | |
a4076574 LP |
787 | |
788 | assert(s); | |
789 | assert(p); | |
790 | ||
2a3900d7 LP |
791 | DNS_QUESTION_FOREACH(key, p->question) |
792 | dns_zone_verify_conflicts(&s->zone, key); | |
793 | ||
794 | DNS_ANSWER_FOREACH(rr, p->answer) | |
795 | dns_zone_verify_conflicts(&s->zone, rr->key); | |
a4076574 LP |
796 | } |
797 | ||
623a4c97 | 798 | void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) { |
8bf52d3d | 799 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL; |
b30bf55d | 800 | _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL; |
5032b16d | 801 | DnsResourceKey *key = NULL; |
ec2c5e43 | 802 | bool tentative = false; |
b30bf55d | 803 | int r; |
623a4c97 LP |
804 | |
805 | assert(s); | |
806 | assert(p); | |
807 | ||
808 | if (p->protocol != DNS_PROTOCOL_LLMNR) | |
809 | return; | |
810 | ||
2442b93d LP |
811 | if (p->ipproto == IPPROTO_UDP) { |
812 | /* Don't accept UDP queries directed to anything but | |
813 | * the LLMNR multicast addresses. See RFC 4795, | |
d076c6f9 | 814 | * section 2.5. */ |
2442b93d LP |
815 | |
816 | if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS)) | |
817 | return; | |
818 | ||
819 | if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS)) | |
820 | return; | |
821 | } | |
822 | ||
623a4c97 LP |
823 | r = dns_packet_extract(p); |
824 | if (r < 0) { | |
b30bf55d | 825 | log_debug_errno(r, "Failed to extract resource records from incoming packet: %m"); |
623a4c97 LP |
826 | return; |
827 | } | |
828 | ||
8b757a38 | 829 | if (DNS_PACKET_LLMNR_C(p)) { |
a4076574 LP |
830 | /* Somebody notified us about a possible conflict */ |
831 | dns_scope_verify_conflicts(s, p); | |
ea917db9 LP |
832 | return; |
833 | } | |
834 | ||
501e8eb0 | 835 | assert(dns_question_size(p->question) == 1); |
5032b16d LP |
836 | key = p->question->keys[0]; |
837 | ||
97ebebbc | 838 | r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative); |
623a4c97 | 839 | if (r < 0) { |
105a1a36 | 840 | log_debug_errno(r, "Failed to look up key: %m"); |
623a4c97 LP |
841 | return; |
842 | } | |
843 | if (r == 0) | |
844 | return; | |
845 | ||
fcf57f9c LP |
846 | if (answer) |
847 | dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0); | |
af93291c | 848 | |
ec2c5e43 | 849 | r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply); |
623a4c97 | 850 | if (r < 0) { |
da927ba9 | 851 | log_debug_errno(r, "Failed to build reply packet: %m"); |
623a4c97 LP |
852 | return; |
853 | } | |
854 | ||
b30bf55d | 855 | if (stream) { |
623a4c97 | 856 | r = dns_stream_write_packet(stream, reply); |
b30bf55d LP |
857 | if (r < 0) { |
858 | log_debug_errno(r, "Failed to enqueue reply packet: %m"); | |
859 | return; | |
860 | } | |
861 | ||
862 | /* Let's take an extra reference on this stream, so that it stays around after returning. The reference | |
863 | * will be dangling until the stream is disconnected, and the default completion handler of the stream | |
864 | * will then unref the stream and destroy it */ | |
865 | if (DNS_STREAM_QUEUED(stream)) | |
866 | dns_stream_ref(stream); | |
867 | } else { | |
868 | int fd; | |
869 | ||
7994ac1d | 870 | if (!ratelimit_below(&s->ratelimit)) |
aea2429d LP |
871 | return; |
872 | ||
623a4c97 LP |
873 | if (p->family == AF_INET) |
874 | fd = manager_llmnr_ipv4_udp_fd(s->manager); | |
875 | else if (p->family == AF_INET6) | |
876 | fd = manager_llmnr_ipv6_udp_fd(s->manager); | |
877 | else { | |
878 | log_debug("Unknown protocol"); | |
879 | return; | |
880 | } | |
881 | if (fd < 0) { | |
da927ba9 | 882 | log_debug_errno(fd, "Failed to get reply socket: %m"); |
623a4c97 LP |
883 | return; |
884 | } | |
885 | ||
6e068472 LP |
886 | /* Note that we always immediately reply to all LLMNR |
887 | * requests, and do not wait any time, since we | |
888 | * verified uniqueness for all records. Also see RFC | |
889 | * 4795, Section 2.7 */ | |
890 | ||
b30bf55d LP |
891 | r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, NULL, reply); |
892 | if (r < 0) { | |
893 | log_debug_errno(r, "Failed to send reply packet: %m"); | |
894 | return; | |
895 | } | |
623a4c97 LP |
896 | } |
897 | } | |
ec2c5e43 | 898 | |
f52e61da | 899 | DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsResourceKey *key, bool cache_ok) { |
ec2c5e43 LP |
900 | DnsTransaction *t; |
901 | ||
902 | assert(scope); | |
f52e61da | 903 | assert(key); |
ec2c5e43 | 904 | |
da0c630e LP |
905 | /* Try to find an ongoing transaction that is a equal to the |
906 | * specified question */ | |
f9ebb22a | 907 | t = hashmap_get(scope->transactions_by_key, key); |
4a46ed1b LP |
908 | if (!t) |
909 | return NULL; | |
dc4d47e2 | 910 | |
da0c630e LP |
911 | /* Refuse reusing transactions that completed based on cached |
912 | * data instead of a real packet, if that's requested. */ | |
913 | if (!cache_ok && | |
3bbdc31d | 914 | IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_RCODE_FAILURE) && |
c3bc53e6 | 915 | t->answer_source != DNS_TRANSACTION_NETWORK) |
da0c630e | 916 | return NULL; |
ec2c5e43 | 917 | |
da0c630e | 918 | return t; |
ec2c5e43 | 919 | } |
a4076574 LP |
920 | |
921 | static int dns_scope_make_conflict_packet( | |
922 | DnsScope *s, | |
923 | DnsResourceRecord *rr, | |
924 | DnsPacket **ret) { | |
925 | ||
926 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
927 | int r; | |
928 | ||
929 | assert(s); | |
930 | assert(rr); | |
931 | assert(ret); | |
932 | ||
51027656 | 933 | r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX); |
a4076574 LP |
934 | if (r < 0) |
935 | return r; | |
936 | ||
937 | DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS( | |
938 | 0 /* qr */, | |
939 | 0 /* opcode */, | |
940 | 1 /* conflict */, | |
941 | 0 /* tc */, | |
942 | 0 /* t */, | |
943 | 0 /* (ra) */, | |
944 | 0 /* (ad) */, | |
945 | 0 /* (cd) */, | |
946 | 0)); | |
fe2dfc8b DM |
947 | |
948 | /* For mDNS, the transaction ID should always be 0 */ | |
949 | if (s->protocol != DNS_PROTOCOL_MDNS) | |
950 | random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t)); | |
951 | ||
a4076574 LP |
952 | DNS_PACKET_HEADER(p)->qdcount = htobe16(1); |
953 | DNS_PACKET_HEADER(p)->arcount = htobe16(1); | |
954 | ||
58ab31d5 | 955 | r = dns_packet_append_key(p, rr->key, 0, NULL); |
a4076574 LP |
956 | if (r < 0) |
957 | return r; | |
958 | ||
58ab31d5 | 959 | r = dns_packet_append_rr(p, rr, 0, NULL, NULL); |
a4076574 LP |
960 | if (r < 0) |
961 | return r; | |
962 | ||
1cc6c93a | 963 | *ret = TAKE_PTR(p); |
a4076574 LP |
964 | |
965 | return 0; | |
966 | } | |
967 | ||
968 | static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) { | |
969 | DnsScope *scope = userdata; | |
970 | int r; | |
971 | ||
972 | assert(es); | |
973 | assert(scope); | |
974 | ||
975 | scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source); | |
976 | ||
977 | for (;;) { | |
432d108c | 978 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
a4076574 LP |
979 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; |
980 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
981 | ||
432d108c DR |
982 | key = ordered_hashmap_first_key(scope->conflict_queue); |
983 | if (!key) | |
a4076574 LP |
984 | break; |
985 | ||
432d108c DR |
986 | rr = ordered_hashmap_remove(scope->conflict_queue, key); |
987 | assert(rr); | |
988 | ||
a4076574 LP |
989 | r = dns_scope_make_conflict_packet(scope, rr, &p); |
990 | if (r < 0) { | |
da927ba9 | 991 | log_error_errno(r, "Failed to make conflict packet: %m"); |
a4076574 LP |
992 | return 0; |
993 | } | |
994 | ||
519ef046 | 995 | r = dns_scope_emit_udp(scope, -1, p); |
a4076574 | 996 | if (r < 0) |
da927ba9 | 997 | log_debug_errno(r, "Failed to send conflict packet: %m"); |
a4076574 LP |
998 | } |
999 | ||
1000 | return 0; | |
1001 | } | |
1002 | ||
1003 | int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) { | |
1004 | usec_t jitter; | |
1005 | int r; | |
1006 | ||
1007 | assert(scope); | |
1008 | assert(rr); | |
1009 | ||
1010 | /* We don't send these queries immediately. Instead, we queue | |
1011 | * them, and send them after some jitter delay. */ | |
1e43061b | 1012 | r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops); |
a4076574 LP |
1013 | if (r < 0) { |
1014 | log_oom(); | |
1015 | return r; | |
1016 | } | |
1017 | ||
1018 | /* We only place one RR per key in the conflict | |
1019 | * messages, not all of them. That should be enough to | |
1020 | * indicate where there might be a conflict */ | |
1e43061b | 1021 | r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr); |
4c701096 | 1022 | if (IN_SET(r, 0, -EEXIST)) |
a4076574 | 1023 | return 0; |
f647962d MS |
1024 | if (r < 0) |
1025 | return log_debug_errno(r, "Failed to queue conflicting RR: %m"); | |
a4076574 | 1026 | |
432d108c | 1027 | dns_resource_key_ref(rr->key); |
a4076574 LP |
1028 | dns_resource_record_ref(rr); |
1029 | ||
1030 | if (scope->conflict_event_source) | |
1031 | return 0; | |
1032 | ||
1033 | random_bytes(&jitter, sizeof(jitter)); | |
1034 | jitter %= LLMNR_JITTER_INTERVAL_USEC; | |
1035 | ||
39cf0351 LP |
1036 | r = sd_event_add_time_relative( |
1037 | scope->manager->event, | |
1038 | &scope->conflict_event_source, | |
1039 | clock_boottime_or_monotonic(), | |
1040 | jitter, | |
1041 | LLMNR_JITTER_INTERVAL_USEC, | |
1042 | on_conflict_dispatch, scope); | |
f647962d MS |
1043 | if (r < 0) |
1044 | return log_debug_errno(r, "Failed to add conflict dispatch event: %m"); | |
a4076574 | 1045 | |
aa4a9deb LP |
1046 | (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict"); |
1047 | ||
a4076574 LP |
1048 | return 0; |
1049 | } | |
1050 | ||
1051 | void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) { | |
c1227a18 | 1052 | DnsResourceRecord *rr; |
a4076574 LP |
1053 | int r; |
1054 | ||
1055 | assert(scope); | |
1056 | assert(p); | |
1057 | ||
53fda2bb | 1058 | if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) |
a4076574 LP |
1059 | return; |
1060 | ||
1061 | if (DNS_PACKET_RRCOUNT(p) <= 0) | |
1062 | return; | |
1063 | ||
53fda2bb DR |
1064 | if (p->protocol == DNS_PROTOCOL_LLMNR) { |
1065 | if (DNS_PACKET_LLMNR_C(p) != 0) | |
1066 | return; | |
a4076574 | 1067 | |
53fda2bb DR |
1068 | if (DNS_PACKET_LLMNR_T(p) != 0) |
1069 | return; | |
1070 | } | |
a4076574 LP |
1071 | |
1072 | if (manager_our_packet(scope->manager, p)) | |
1073 | return; | |
1074 | ||
1075 | r = dns_packet_extract(p); | |
1076 | if (r < 0) { | |
da927ba9 | 1077 | log_debug_errno(r, "Failed to extract packet: %m"); |
a4076574 LP |
1078 | return; |
1079 | } | |
1080 | ||
1081 | log_debug("Checking for conflicts..."); | |
1082 | ||
c1227a18 | 1083 | DNS_ANSWER_FOREACH(rr, p->answer) { |
cfcc8dcc | 1084 | /* No conflict if it is DNS-SD RR used for service enumeration. */ |
c1227a18 | 1085 | if (dns_resource_key_is_dnssd_ptr(rr->key)) |
cfcc8dcc DR |
1086 | continue; |
1087 | ||
a4076574 LP |
1088 | /* Check for conflicts against the local zone. If we |
1089 | * found one, we won't check any further */ | |
c1227a18 | 1090 | r = dns_zone_check_conflicts(&scope->zone, rr); |
a4076574 LP |
1091 | if (r != 0) |
1092 | continue; | |
1093 | ||
1094 | /* Check for conflicts against the local cache. If so, | |
1095 | * send out an advisory query, to inform everybody */ | |
c1227a18 | 1096 | r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender); |
a4076574 LP |
1097 | if (r <= 0) |
1098 | continue; | |
1099 | ||
c1227a18 | 1100 | dns_scope_notify_conflict(scope, rr); |
a4076574 LP |
1101 | } |
1102 | } | |
4d506d6b LP |
1103 | |
1104 | void dns_scope_dump(DnsScope *s, FILE *f) { | |
1105 | assert(s); | |
1106 | ||
1107 | if (!f) | |
1108 | f = stdout; | |
1109 | ||
1110 | fputs("[Scope protocol=", f); | |
1111 | fputs(dns_protocol_to_string(s->protocol), f); | |
1112 | ||
1113 | if (s->link) { | |
1114 | fputs(" interface=", f); | |
6ff79f76 | 1115 | fputs(s->link->ifname, f); |
4d506d6b LP |
1116 | } |
1117 | ||
1118 | if (s->family != AF_UNSPEC) { | |
1119 | fputs(" family=", f); | |
1120 | fputs(af_to_name(s->family), f); | |
1121 | } | |
1122 | ||
1123 | fputs("]\n", f); | |
1124 | ||
1125 | if (!dns_zone_is_empty(&s->zone)) { | |
1126 | fputs("ZONE:\n", f); | |
1127 | dns_zone_dump(&s->zone, f); | |
1128 | } | |
1129 | ||
1130 | if (!dns_cache_is_empty(&s->cache)) { | |
1131 | fputs("CACHE:\n", f); | |
1132 | dns_cache_dump(&s->cache, f); | |
1133 | } | |
1134 | } | |
a51c1048 LP |
1135 | |
1136 | DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) { | |
801ad6a6 LP |
1137 | assert(s); |
1138 | ||
a51c1048 LP |
1139 | if (s->protocol != DNS_PROTOCOL_DNS) |
1140 | return NULL; | |
1141 | ||
1142 | if (s->link) | |
1143 | return s->link->search_domains; | |
1144 | ||
28b9b764 | 1145 | return s->manager->search_domains; |
801ad6a6 LP |
1146 | } |
1147 | ||
3b5bd7d6 | 1148 | bool dns_scope_name_wants_search_domain(DnsScope *s, const char *name) { |
801ad6a6 LP |
1149 | assert(s); |
1150 | ||
1151 | if (s->protocol != DNS_PROTOCOL_DNS) | |
dc477e73 | 1152 | return false; |
801ad6a6 | 1153 | |
dc477e73 | 1154 | return dns_name_is_single_label(name); |
801ad6a6 | 1155 | } |
edbcc1fd LP |
1156 | |
1157 | bool dns_scope_network_good(DnsScope *s) { | |
edbcc1fd LP |
1158 | /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes |
1159 | * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global | |
de4a0138 LP |
1160 | * DNS scope we check whether there are any links that are up and have an address. |
1161 | * | |
1162 | * Note that Linux routing is complex and even systems that superficially have no IPv4 address might | |
1163 | * be able to route IPv4 (and similar for IPv6), hence let's make a check here independent of address | |
1164 | * family. */ | |
edbcc1fd LP |
1165 | |
1166 | if (s->link) | |
1167 | return true; | |
1168 | ||
de4a0138 | 1169 | return manager_routable(s->manager); |
edbcc1fd | 1170 | } |
97ebebbc LP |
1171 | |
1172 | int dns_scope_ifindex(DnsScope *s) { | |
1173 | assert(s); | |
1174 | ||
1175 | if (s->link) | |
1176 | return s->link->ifindex; | |
1177 | ||
1178 | return 0; | |
1179 | } | |
53fda2bb DR |
1180 | |
1181 | static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) { | |
1182 | DnsScope *scope = userdata; | |
1183 | ||
1184 | assert(s); | |
1185 | ||
1186 | scope->announce_event_source = sd_event_source_unref(scope->announce_event_source); | |
1187 | ||
1a63fc54 | 1188 | (void) dns_scope_announce(scope, false); |
53fda2bb DR |
1189 | return 0; |
1190 | } | |
1191 | ||
1a63fc54 | 1192 | int dns_scope_announce(DnsScope *scope, bool goodbye) { |
53fda2bb DR |
1193 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
1194 | _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; | |
a2bf8a19 DR |
1195 | _cleanup_set_free_ Set *types = NULL; |
1196 | DnsTransaction *t; | |
400f54fb | 1197 | DnsZoneItem *z, *i; |
a2bf8a19 | 1198 | unsigned size = 0; |
a2bf8a19 | 1199 | char *service_type; |
53fda2bb DR |
1200 | int r; |
1201 | ||
1202 | if (!scope) | |
1a63fc54 | 1203 | return 0; |
53fda2bb DR |
1204 | |
1205 | if (scope->protocol != DNS_PROTOCOL_MDNS) | |
1a63fc54 | 1206 | return 0; |
53fda2bb | 1207 | |
a2bf8a19 DR |
1208 | /* Check if we're done with probing. */ |
1209 | LIST_FOREACH(transactions_by_scope, t, scope->transactions) | |
1210 | if (DNS_TRANSACTION_IS_LIVE(t->state)) | |
1211 | return 0; | |
1212 | ||
e7c1b0e4 DR |
1213 | /* Check if there're services pending conflict resolution. */ |
1214 | if (manager_next_dnssd_names(scope->manager)) | |
1215 | return 0; /* we reach this point only if changing hostname didn't help */ | |
1216 | ||
a2bf8a19 | 1217 | /* Calculate answer's size. */ |
90e74a66 | 1218 | HASHMAP_FOREACH(z, scope->zone.by_key) { |
a2bf8a19 DR |
1219 | if (z->state != DNS_ZONE_ITEM_ESTABLISHED) |
1220 | continue; | |
1221 | ||
1222 | if (z->rr->key->type == DNS_TYPE_PTR && | |
1223 | !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) { | |
1224 | char key_str[DNS_RESOURCE_KEY_STRING_MAX]; | |
1225 | ||
1226 | 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)); | |
1227 | z->state = DNS_ZONE_ITEM_WITHDRAWN; | |
1228 | continue; | |
1229 | } | |
1230 | ||
1231 | /* Collect service types for _services._dns-sd._udp.local RRs in a set */ | |
1232 | if (!scope->announced && | |
1233 | dns_resource_key_is_dnssd_ptr(z->rr->key)) { | |
1234 | if (!set_contains(types, dns_resource_key_name(z->rr->key))) { | |
de7fef4b | 1235 | r = set_ensure_put(&types, &dns_name_hash_ops, dns_resource_key_name(z->rr->key)); |
a2bf8a19 DR |
1236 | if (r < 0) |
1237 | return log_debug_errno(r, "Failed to add item to set: %m"); | |
1238 | } | |
1239 | } | |
1240 | ||
400f54fb DR |
1241 | LIST_FOREACH(by_key, i, z) |
1242 | size++; | |
a2bf8a19 DR |
1243 | } |
1244 | ||
1245 | answer = dns_answer_new(size + set_size(types)); | |
1a63fc54 LP |
1246 | if (!answer) |
1247 | return log_oom(); | |
1248 | ||
a2bf8a19 | 1249 | /* Second iteration, actually add RRs to the answer. */ |
90e74a66 | 1250 | HASHMAP_FOREACH(z, scope->zone.by_key) |
400f54fb DR |
1251 | LIST_FOREACH (by_key, i, z) { |
1252 | DnsAnswerFlags flags; | |
a2bf8a19 | 1253 | |
400f54fb DR |
1254 | if (i->state != DNS_ZONE_ITEM_ESTABLISHED) |
1255 | continue; | |
a2bf8a19 | 1256 | |
400f54fb DR |
1257 | if (dns_resource_key_is_dnssd_ptr(i->rr->key)) |
1258 | flags = goodbye ? DNS_ANSWER_GOODBYE : 0; | |
1259 | else | |
1260 | flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH; | |
a2bf8a19 | 1261 | |
400f54fb DR |
1262 | r = dns_answer_add(answer, i->rr, 0 , flags); |
1263 | if (r < 0) | |
1264 | return log_debug_errno(r, "Failed to add RR to announce: %m"); | |
1265 | } | |
a2bf8a19 DR |
1266 | |
1267 | /* Since all the active services are in the zone make them discoverable now. */ | |
90e74a66 | 1268 | SET_FOREACH(service_type, types) { |
a2bf8a19 DR |
1269 | _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr; |
1270 | ||
1271 | rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, | |
1272 | "_services._dns-sd._udp.local"); | |
1273 | rr->ptr.name = strdup(service_type); | |
1274 | rr->ttl = MDNS_DEFAULT_TTL; | |
1275 | ||
1276 | r = dns_zone_put(&scope->zone, scope, rr, false); | |
1a63fc54 | 1277 | if (r < 0) |
a2bf8a19 | 1278 | log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m"); |
1a63fc54 | 1279 | |
a2bf8a19 | 1280 | r = dns_answer_add(answer, rr, 0 , 0); |
1a63fc54 | 1281 | if (r < 0) |
a2bf8a19 | 1282 | return log_debug_errno(r, "Failed to add RR to announce: %m"); |
53fda2bb DR |
1283 | } |
1284 | ||
1285 | if (dns_answer_isempty(answer)) | |
1a63fc54 | 1286 | return 0; |
53fda2bb DR |
1287 | |
1288 | r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p); | |
1a63fc54 LP |
1289 | if (r < 0) |
1290 | return log_debug_errno(r, "Failed to build reply packet: %m"); | |
1291 | ||
53fda2bb | 1292 | r = dns_scope_emit_udp(scope, -1, p); |
1a63fc54 LP |
1293 | if (r < 0) |
1294 | return log_debug_errno(r, "Failed to send reply packet: %m"); | |
53fda2bb DR |
1295 | |
1296 | /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited | |
1297 | * responses, one second apart." */ | |
1298 | if (!scope->announced) { | |
53fda2bb DR |
1299 | scope->announced = true; |
1300 | ||
39cf0351 | 1301 | r = sd_event_add_time_relative( |
53fda2bb DR |
1302 | scope->manager->event, |
1303 | &scope->announce_event_source, | |
1304 | clock_boottime_or_monotonic(), | |
39cf0351 | 1305 | MDNS_ANNOUNCE_DELAY, |
53fda2bb DR |
1306 | MDNS_JITTER_RANGE_USEC, |
1307 | on_announcement_timeout, scope); | |
1308 | if (r < 0) | |
1a63fc54 | 1309 | return log_debug_errno(r, "Failed to schedule second announcement: %m"); |
19fee3ef LP |
1310 | |
1311 | (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce"); | |
53fda2bb | 1312 | } |
1a63fc54 LP |
1313 | |
1314 | return 0; | |
53fda2bb | 1315 | } |
6db6a464 DR |
1316 | |
1317 | int dns_scope_add_dnssd_services(DnsScope *scope) { | |
6db6a464 | 1318 | DnssdService *service; |
400f54fb | 1319 | DnssdTxtData *txt_data; |
6db6a464 DR |
1320 | int r; |
1321 | ||
1322 | assert(scope); | |
1323 | ||
1324 | if (hashmap_size(scope->manager->dnssd_services) == 0) | |
1325 | return 0; | |
1326 | ||
1327 | scope->announced = false; | |
1328 | ||
90e74a66 | 1329 | HASHMAP_FOREACH(service, scope->manager->dnssd_services) { |
c3036641 DR |
1330 | service->withdrawn = false; |
1331 | ||
6db6a464 DR |
1332 | r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false); |
1333 | if (r < 0) | |
1334 | log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m"); | |
1335 | ||
1336 | r = dns_zone_put(&scope->zone, scope, service->srv_rr, true); | |
1337 | if (r < 0) | |
1338 | log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m"); | |
1339 | ||
400f54fb DR |
1340 | LIST_FOREACH(items, txt_data, service->txt_data_items) { |
1341 | r = dns_zone_put(&scope->zone, scope, txt_data->rr, true); | |
1342 | if (r < 0) | |
1343 | log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m"); | |
1344 | } | |
6db6a464 DR |
1345 | } |
1346 | ||
1347 | return 0; | |
1348 | } | |
1349 | ||
1350 | int dns_scope_remove_dnssd_services(DnsScope *scope) { | |
1351 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; | |
6db6a464 | 1352 | DnssdService *service; |
400f54fb | 1353 | DnssdTxtData *txt_data; |
6db6a464 DR |
1354 | int r; |
1355 | ||
1356 | assert(scope); | |
1357 | ||
1358 | key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR, | |
1359 | "_services._dns-sd._udp.local"); | |
1360 | if (!key) | |
1361 | return log_oom(); | |
1362 | ||
1363 | r = dns_zone_remove_rrs_by_key(&scope->zone, key); | |
1364 | if (r < 0) | |
1365 | return r; | |
1366 | ||
90e74a66 | 1367 | HASHMAP_FOREACH(service, scope->manager->dnssd_services) { |
6db6a464 DR |
1368 | dns_zone_remove_rr(&scope->zone, service->ptr_rr); |
1369 | dns_zone_remove_rr(&scope->zone, service->srv_rr); | |
400f54fb DR |
1370 | LIST_FOREACH(items, txt_data, service->txt_data_items) |
1371 | dns_zone_remove_rr(&scope->zone, txt_data->rr); | |
6db6a464 DR |
1372 | } |
1373 | ||
1374 | return 0; | |
1375 | } | |
f76fa088 | 1376 | |
ca5394d2 | 1377 | static bool dns_scope_has_route_only_domains(DnsScope *scope) { |
f76fa088 LP |
1378 | DnsSearchDomain *domain, *first; |
1379 | bool route_only = false; | |
1380 | ||
ca5394d2 LP |
1381 | assert(scope); |
1382 | assert(scope->protocol == DNS_PROTOCOL_DNS); | |
f76fa088 | 1383 | |
ca5394d2 LP |
1384 | /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check |
1385 | * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links | |
1386 | * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to | |
1387 | * take queries to arbitrary domains, i.e. has no routing domains set. */ | |
f76fa088 LP |
1388 | |
1389 | if (scope->link) | |
1390 | first = scope->link->search_domains; | |
1391 | else | |
1392 | first = scope->manager->search_domains; | |
1393 | ||
1394 | LIST_FOREACH(domains, domain, first) { | |
ca5394d2 LP |
1395 | /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early |
1396 | * here, as it doesn't really matter whether this link has any route-only domains or not, | |
1397 | * "~." really trumps everything and clearly indicates that this interface shall receive all | |
1398 | * traffic it can get. */ | |
f76fa088 LP |
1399 | if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain))) |
1400 | return false; | |
1401 | ||
1402 | if (domain->route_only) | |
1403 | route_only = true; | |
1404 | } | |
1405 | ||
1406 | return route_only; | |
1407 | } | |
ca5394d2 LP |
1408 | |
1409 | bool dns_scope_is_default_route(DnsScope *scope) { | |
1410 | assert(scope); | |
1411 | ||
1412 | /* Only use DNS scopes as default routes */ | |
1413 | if (scope->protocol != DNS_PROTOCOL_DNS) | |
1414 | return false; | |
1415 | ||
1416 | /* The global DNS scope is always suitable as default route */ | |
1417 | if (!scope->link) | |
1418 | return true; | |
1419 | ||
1420 | /* Honour whatever is explicitly configured. This is really the best approach, and trumps any | |
1421 | * automatic logic. */ | |
1422 | if (scope->link->default_route >= 0) | |
1423 | return scope->link->default_route; | |
1424 | ||
1425 | /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not | |
1426 | * volunteer as default route. */ | |
1427 | return !dns_scope_has_route_only_domains(scope); | |
1428 | } |