src/resolve/resolved-dns-scope.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <netinet/tcp.h>
   4
   5 #include "af-list.h"
   6 #include "alloc-util.h"
   7 #include "dns-domain.h"
   8 #include "fd-util.h"
   9 #include "hostname-util.h"
  10 #include "missing_network.h"
  11 #include "random-util.h"
  12 #include "resolved-dnssd.h"
  13 #include "resolved-dns-scope.h"
  14 #include "resolved-dns-zone.h"
  15 #include "resolved-llmnr.h"
  16 #include "resolved-mdns.h"
  17 #include "socket-util.h"
  18 #include "strv.h"
  19
  20 #define MULTICAST_RATELIMIT_INTERVAL_USEC (1*USEC_PER_SEC)
  21 #define MULTICAST_RATELIMIT_BURST 1000
  22
  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
  27 int dns_scope_new(Manager *m, DnsScope **ret, Link *l, DnsProtocol protocol, int family) {
  28         DnsScope *s;
  29
  30         assert(m);
  31         assert(ret);
  32
  33         s = new(DnsScope, 1);
  34         if (!s)
  35                 return -ENOMEM;
  36
  37         *s = (DnsScope) {
  38                 .manager = m,
  39                 .link = l,
  40                 .protocol = protocol,
  41                 .family = family,
  42                 .resend_timeout = MULTICAST_RESEND_TIMEOUT_MIN_USEC,
  43         };
  44
  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
  52                 if (l) {
  53                         s->dnssec_mode = link_get_dnssec_mode(l);
  54                         s->dns_over_tls_mode = link_get_dns_over_tls_mode(l);
  55                 } else {
  56                         s->dnssec_mode = manager_get_dnssec_mode(m);
  57                         s->dns_over_tls_mode = manager_get_dns_over_tls_mode(m);
  58                 }
  59
  60         } else {
  61                 s->dnssec_mode = DNSSEC_NO;
  62                 s->dns_over_tls_mode = DNS_OVER_TLS_NO;
  63         }
  64
  65         LIST_PREPEND(scopes, m->dns_scopes, s);
  66
  67         dns_scope_llmnr_membership(s, true);
  68         dns_scope_mdns_membership(s, true);
  69
  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));
  71
  72         /* Enforce ratelimiting for the multicast protocols */
  73         s->ratelimit = (RateLimit) { MULTICAST_RATELIMIT_INTERVAL_USEC, MULTICAST_RATELIMIT_BURST };
  74
  75         *ret = s;
  76         return 0;
  77 }
  78
  79 static void dns_scope_abort_transactions(DnsScope *s) {
  80         assert(s);
  81
  82         while (s->transactions) {
  83                 DnsTransaction *t = s->transactions;
  84
  85                 /* Abort the transaction, but make sure it is not
  86                  * freed while we still look at it */
  87
  88                 t->block_gc++;
  89                 if (DNS_TRANSACTION_IS_LIVE(t->state))
  90                         dns_transaction_complete(t, DNS_TRANSACTION_ABORTED);
  91                 t->block_gc--;
  92
  93                 dns_transaction_free(t);
  94         }
  95 }
  96
  97 DnsScope* dns_scope_free(DnsScope *s) {
  98         if (!s)
  99                 return NULL;
 100
 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));
 102
 103         dns_scope_llmnr_membership(s, false);
 104         dns_scope_mdns_membership(s, false);
 105         dns_scope_abort_transactions(s);
 106
 107         while (s->query_candidates)
 108                 dns_query_candidate_free(s->query_candidates);
 109
 110         hashmap_free(s->transactions_by_key);
 111
 112         ordered_hashmap_free_with_destructor(s->conflict_queue, dns_resource_record_unref);
 113         sd_event_source_unref(s->conflict_event_source);
 114
 115         sd_event_source_unref(s->announce_event_source);
 116
 117         dns_cache_flush(&s->cache);
 118         dns_zone_flush(&s->zone);
 119
 120         LIST_REMOVE(scopes, s->manager->dns_scopes, s);
 121         return mfree(s);
 122 }
 123
 124 DnsServer *dns_scope_get_dns_server(DnsScope *s) {
 125         assert(s);
 126
 127         if (s->protocol != DNS_PROTOCOL_DNS)
 128                 return NULL;
 129
 130         if (s->link)
 131                 return link_get_dns_server(s->link);
 132         else
 133                 return manager_get_dns_server(s->manager);
 134 }
 135
 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
 156 void dns_scope_next_dns_server(DnsScope *s) {
 157         assert(s);
 158
 159         if (s->protocol != DNS_PROTOCOL_DNS)
 160                 return;
 161
 162         if (s->link)
 163                 link_next_dns_server(s->link);
 164         else
 165                 manager_next_dns_server(s->manager);
 166 }
 167
 168 void dns_scope_packet_received(DnsScope *s, usec_t rtt) {
 169         assert(s);
 170
 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);
 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
 185 static int dns_scope_emit_one(DnsScope *s, int fd, DnsPacket *p) {
 186         union in_addr_union addr;
 187         int ifindex = 0, r;
 188         int family;
 189         uint32_t mtu;
 190
 191         assert(s);
 192         assert(p);
 193         assert(p->protocol == s->protocol);
 194
 195         if (s->link) {
 196                 mtu = s->link->mtu;
 197                 ifindex = s->link->ifindex;
 198         } else
 199                 mtu = manager_find_mtu(s->manager);
 200
 201         switch (s->protocol) {
 202
 203         case DNS_PROTOCOL_DNS:
 204                 assert(fd >= 0);
 205
 206                 if (DNS_PACKET_QDCOUNT(p) > 1)
 207                         return -EOPNOTSUPP;
 208
 209                 if (p->size > DNS_PACKET_UNICAST_SIZE_MAX)
 210                         return -EMSGSIZE;
 211
 212                 if (p->size + UDP_PACKET_HEADER_SIZE > mtu)
 213                         return -EMSGSIZE;
 214
 215                 r = manager_write(s->manager, fd, p);
 216                 if (r < 0)
 217                         return r;
 218
 219                 break;
 220
 221         case DNS_PROTOCOL_LLMNR:
 222                 assert(fd < 0);
 223
 224                 if (DNS_PACKET_QDCOUNT(p) > 1)
 225                         return -EOPNOTSUPP;
 226
 227                 if (!ratelimit_below(&s->ratelimit))
 228                         return -EBUSY;
 229
 230                 family = s->family;
 231
 232                 if (family == AF_INET) {
 233                         addr.in = LLMNR_MULTICAST_IPV4_ADDRESS;
 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);
 238                 } else
 239                         return -EAFNOSUPPORT;
 240                 if (fd < 0)
 241                         return fd;
 242
 243                 r = manager_send(s->manager, fd, ifindex, family, &addr, LLMNR_PORT, NULL, p);
 244                 if (r < 0)
 245                         return r;
 246
 247                 break;
 248
 249         case DNS_PROTOCOL_MDNS:
 250                 assert(fd < 0);
 251
 252                 if (!ratelimit_below(&s->ratelimit))
 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
 268                 r = manager_send(s->manager, fd, ifindex, family, &addr, MDNS_PORT, NULL, p);
 269                 if (r < 0)
 270                         return r;
 271
 272                 break;
 273
 274         default:
 275                 return -EAFNOSUPPORT;
 276         }
 277
 278         return 1;
 279 }
 280
 281 int dns_scope_emit_udp(DnsScope *s, int fd, DnsPacket *p) {
 282         int r;
 283
 284         assert(s);
 285         assert(p);
 286         assert(p->protocol == s->protocol);
 287         assert((s->protocol == DNS_PROTOCOL_DNS) == (fd >= 0));
 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);
 293                         dns_packet_set_flags(p, true, true);
 294                 }
 295
 296                 r = dns_scope_emit_one(s, fd, p);
 297                 if (r < 0)
 298                         return r;
 299
 300                 p = p->more;
 301         } while (p);
 302
 303         return 0;
 304 }
 305
 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,
 312                 uint16_t port,
 313                 union sockaddr_union *ret_socket_address) {
 314
 315         _cleanup_close_ int fd = -1;
 316         union sockaddr_union sa;
 317         socklen_t salen;
 318         int r, ifindex;
 319
 320         assert(s);
 321
 322         if (server) {
 323                 assert(family == AF_UNSPEC);
 324                 assert(!address);
 325
 326                 ifindex = dns_server_ifindex(server);
 327
 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                         };
 335                         salen = sizeof(sa.in);
 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                         };
 344                         salen = sizeof(sa.in6);
 345                         break;
 346                 default:
 347                         return -EAFNOSUPPORT;
 348                 }
 349         } else {
 350                 assert(family != AF_UNSPEC);
 351                 assert(address);
 352
 353                 ifindex = s->link ? s->link->ifindex : 0;
 354
 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                         };
 362                         salen = sizeof(sa.in);
 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                         };
 371                         salen = sizeof(sa.in6);
 372                         break;
 373                 default:
 374                         return -EAFNOSUPPORT;
 375                 }
 376         }
 377
 378         fd = socket(sa.sa.sa_family, type|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 379         if (fd < 0)
 380                 return -errno;
 381
 382         if (type == SOCK_STREAM) {
 383                 r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true);
 384                 if (r < 0)
 385                         return r;
 386         }
 387
 388         if (s->link) {
 389                 be32_t ifindex_be = htobe32(ifindex);
 390
 391                 if (sa.sa.sa_family == AF_INET) {
 392                         r = setsockopt(fd, IPPROTO_IP, IP_UNICAST_IF, &ifindex_be, sizeof(ifindex_be));
 393                         if (r < 0)
 394                                 return -errno;
 395                 } else if (sa.sa.sa_family == AF_INET6) {
 396                         r = setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_IF, &ifindex_be, sizeof(ifindex_be));
 397                         if (r < 0)
 398                                 return -errno;
 399                 }
 400         }
 401
 402         if (s->protocol == DNS_PROTOCOL_LLMNR) {
 403                 /* RFC 4795, section 2.5 requires the TTL to be set to 1 */
 404
 405                 if (sa.sa.sa_family == AF_INET) {
 406                         r = setsockopt_int(fd, IPPROTO_IP, IP_TTL, true);
 407                         if (r < 0)
 408                                 return r;
 409                 } else if (sa.sa.sa_family == AF_INET6) {
 410                         r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, true);
 411                         if (r < 0)
 412                                 return r;
 413                 }
 414         }
 415
 416         if (type == SOCK_DGRAM) {
 417                 /* Set IP_RECVERR or IPV6_RECVERR to get ICMP error feedback. See discussion in #10345. */
 418
 419                 if (sa.sa.sa_family == AF_INET) {
 420                         r = setsockopt_int(fd, IPPROTO_IP, IP_RECVERR, true);
 421                         if (r < 0)
 422                                 return r;
 423
 424                         r = setsockopt_int(fd, IPPROTO_IP, IP_PKTINFO, true);
 425                         if (r < 0)
 426                                 return r;
 427
 428                 } else if (sa.sa.sa_family == AF_INET6) {
 429                         r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_RECVERR, true);
 430                         if (r < 0)
 431                                 return r;
 432
 433                         r = setsockopt_int(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, true);
 434                         if (r < 0)
 435                                 return r;
 436                 }
 437         }
 438
 439         if (ret_socket_address)
 440                 *ret_socket_address = sa;
 441         else {
 442                 r = connect(fd, &sa.sa, salen);
 443                 if (r < 0 && errno != EINPROGRESS)
 444                         return -errno;
 445         }
 446
 447         return TAKE_FD(fd);
 448 }
 449
 450 int dns_scope_socket_udp(DnsScope *s, DnsServer *server, uint16_t port) {
 451         return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, port, NULL);
 452 }
 453
 454 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) {
 455         /* If ret_socket_address is not NULL, the caller is responsible
 456          * for calling connect() or sendmsg(). This is required by TCP
 457          * Fast Open, to be able to send the initial SYN packet along
 458          * with the first data packet. */
 459         return dns_scope_socket(s, SOCK_STREAM, family, address, server, port, ret_socket_address);
 460 }
 461
 462 static DnsScopeMatch accept_link_local_reverse_lookups(const char *domain) {
 463         assert(domain);
 464
 465         if (dns_name_endswith(domain, "254.169.in-addr.arpa") > 0)
 466                 return DNS_SCOPE_YES_BASE + 4; /* 4 labels match */
 467
 468         if (dns_name_endswith(domain, "8.e.f.ip6.arpa") > 0 ||
 469             dns_name_endswith(domain, "9.e.f.ip6.arpa") > 0 ||
 470             dns_name_endswith(domain, "a.e.f.ip6.arpa") > 0 ||
 471             dns_name_endswith(domain, "b.e.f.ip6.arpa") > 0)
 472                 return DNS_SCOPE_YES_BASE + 5; /* 5 labels match */
 473
 474         return _DNS_SCOPE_MATCH_INVALID;
 475 }
 476
 477 DnsScopeMatch dns_scope_good_domain(
 478                 DnsScope *s,
 479                 int ifindex,
 480                 uint64_t flags,
 481                 const char *domain) {
 482
 483         DnsSearchDomain *d;
 484
 485         /* This returns the following return values:
 486          *
 487          *    DNS_SCOPE_NO         → This scope is not suitable for lookups of this domain, at all
 488          *    DNS_SCOPE_MAYBE      → This scope is suitable, but only if nothing else wants it
 489          *    DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match
 490          *
 491          *  (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return
 492          *  DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those
 493          *  which returned DNS_SCOPE_NO.)
 494          */
 495
 496         assert(s);
 497         assert(domain);
 498
 499         /* Checks if the specified domain is something to look up on this scope. Note that this accepts
 500          * non-qualified hostnames, i.e. those without any search path suffixed. */
 501
 502         if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
 503                 return DNS_SCOPE_NO;
 504
 505         if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & flags) == 0)
 506                 return DNS_SCOPE_NO;
 507
 508         /* Never resolve any loopback hostname or IP address via DNS,
 509          * LLMNR or mDNS. Instead, always rely on synthesized RRs for
 510          * these. */
 511         if (is_localhost(domain) ||
 512             dns_name_endswith(domain, "127.in-addr.arpa") > 0 ||
 513             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)
 514                 return DNS_SCOPE_NO;
 515
 516         /* Never respond to some of the domains listed in RFC6303 */
 517         if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 ||
 518             dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 ||
 519             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)
 520                 return DNS_SCOPE_NO;
 521
 522         /* Never respond to some of the domains listed in RFC6761 */
 523         if (dns_name_endswith(domain, "invalid") > 0)
 524                 return DNS_SCOPE_NO;
 525
 526         switch (s->protocol) {
 527
 528         case DNS_PROTOCOL_DNS: {
 529                 bool has_search_domains = false;
 530                 int n_best = -1;
 531
 532                 /* Never route things to scopes that lack DNS servers */
 533                 if (!dns_scope_get_dns_server(s))
 534                         return DNS_SCOPE_NO;
 535
 536                 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
 537                  * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
 538                  * won't be considered anymore. */
 539                 LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) {
 540
 541                         if (!d->route_only && !dns_name_is_root(d->name))
 542                                 has_search_domains = true;
 543
 544                         if (dns_name_endswith(domain, d->name) > 0) {
 545                                 int c;
 546
 547                                 c = dns_name_count_labels(d->name);
 548                                 if (c < 0)
 549                                         continue;
 550
 551                                 if (c > n_best)
 552                                         n_best = c;
 553                         }
 554                 }
 555
 556                 /* If there's a true search domain defined for this scope, and the query is single-label,
 557                  * then let's resolve things here, prefereably. Note that LLMNR considers itself
 558                  * authoritative for single-label names too, at the same preference, see below. */
 559                 if (has_search_domains && dns_name_is_single_label(domain))
 560                         return DNS_SCOPE_YES_BASE + 1;
 561
 562                 /* Let's return the number of labels in the best matching result */
 563                 if (n_best >= 0) {
 564                         assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE);
 565                         return DNS_SCOPE_YES_BASE + n_best;
 566                 }
 567
 568                 /* See if this scope is suitable as default route. */
 569                 if (!dns_scope_is_default_route(s))
 570                         return DNS_SCOPE_NO;
 571
 572                 /* Exclude link-local IP ranges */
 573                 if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
 574                     dns_name_endswith(domain, "8.e.f.ip6.arpa") == 0 &&
 575                     dns_name_endswith(domain, "9.e.f.ip6.arpa") == 0 &&
 576                     dns_name_endswith(domain, "a.e.f.ip6.arpa") == 0 &&
 577                     dns_name_endswith(domain, "b.e.f.ip6.arpa") == 0 &&
 578                     /* If networks use .local in their private setups, they are supposed to also add .local to their search
 579                      * domains, which we already checked above. Otherwise, we consider .local specific to mDNS and won't
 580                      * send such queries ordinary DNS servers. */
 581                     dns_name_endswith(domain, "local") == 0)
 582                         return DNS_SCOPE_MAYBE;
 583
 584                 return DNS_SCOPE_NO;
 585         }
 586
 587         case DNS_PROTOCOL_MDNS: {
 588                 DnsScopeMatch m;
 589
 590                 m = accept_link_local_reverse_lookups(domain);
 591                 if (m >= 0)
 592                         return m;
 593
 594                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 595                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
 596                         return DNS_SCOPE_MAYBE;
 597
 598                 if ((dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */
 599                      dns_name_equal(domain, "local") == 0 &&   /* but not the single-label "local" name itself */
 600                      manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */
 601                         return DNS_SCOPE_YES_BASE + 1; /* Return +1, as the top-level .local domain matches, i.e. one label */
 602
 603                 return DNS_SCOPE_NO;
 604         }
 605
 606         case DNS_PROTOCOL_LLMNR: {
 607                 DnsScopeMatch m;
 608
 609                 m = accept_link_local_reverse_lookups(domain);
 610                 if (m >= 0)
 611                         return m;
 612
 613                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 614                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
 615                         return DNS_SCOPE_MAYBE;
 616
 617                 if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
 618                      !is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
 619                      manager_is_own_hostname(s->manager, domain) <= 0))  /* never resolve the local hostname via LLMNR */
 620                         return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative
 621                                                         * for single-label names, i.e. one label. This is
 622                                                         * particular relevant as it means a "." route on some
 623                                                         * other scope won't pull all traffic away from
 624                                                         * us. (If people actually want to pull traffic away
 625                                                         * from us they should turn off LLMNR on the
 626                                                         * link). Note that unicast DNS scopes with search
 627                                                         * domains also consider themselves authoritative for
 628                                                         * single-label domains, at the same preference (see
 629                                                         * above). */
 630
 631                 return DNS_SCOPE_NO;
 632         }
 633
 634         default:
 635                 assert_not_reached("Unknown scope protocol");
 636         }
 637 }
 638
 639 bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) {
 640         int key_family;
 641
 642         assert(s);
 643         assert(key);
 644
 645         /* Check if it makes sense to resolve the specified key on
 646          * this scope. Note that this call assumes as fully qualified
 647          * name, i.e. the search suffixes already appended. */
 648
 649         if (key->class != DNS_CLASS_IN)
 650                 return false;
 651
 652         if (s->protocol == DNS_PROTOCOL_DNS) {
 653
 654                 /* On classic DNS, looking up non-address RRs is always
 655                  * fine. (Specifically, we want to permit looking up
 656                  * DNSKEY and DS records on the root and top-level
 657                  * domains.) */
 658                 if (!dns_resource_key_is_address(key))
 659                         return true;
 660
 661                 /* However, we refuse to look up A and AAAA RRs on the
 662                  * root and single-label domains, under the assumption
 663                  * that those should be resolved via LLMNR or search
 664                  * path only, and should not be leaked onto the
 665                  * internet. */
 666                 return !(dns_name_is_single_label(dns_resource_key_name(key)) ||
 667                          dns_name_is_root(dns_resource_key_name(key)));
 668         }
 669
 670         /* On mDNS and LLMNR, send A and AAAA queries only on the
 671          * respective scopes */
 672
 673         key_family = dns_type_to_af(key->type);
 674         if (key_family < 0)
 675                 return true;
 676
 677         return key_family == s->family;
 678 }
 679
 680 static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) {
 681         int fd;
 682
 683         assert(s);
 684         assert(s->link);
 685
 686         if (s->family == AF_INET) {
 687                 struct ip_mreqn mreqn = {
 688                         .imr_multiaddr = in,
 689                         .imr_ifindex = s->link->ifindex,
 690                 };
 691
 692                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 693                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 694                 else
 695                         fd = manager_mdns_ipv4_fd(s->manager);
 696
 697                 if (fd < 0)
 698                         return fd;
 699
 700                 /* Always first try to drop membership before we add
 701                  * one. This is necessary on some devices, such as
 702                  * veth. */
 703                 if (b)
 704                         (void) setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn));
 705
 706                 if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0)
 707                         return -errno;
 708
 709         } else if (s->family == AF_INET6) {
 710                 struct ipv6_mreq mreq = {
 711                         .ipv6mr_multiaddr = in6,
 712                         .ipv6mr_interface = s->link->ifindex,
 713                 };
 714
 715                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 716                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 717                 else
 718                         fd = manager_mdns_ipv6_fd(s->manager);
 719
 720                 if (fd < 0)
 721                         return fd;
 722
 723                 if (b)
 724                         (void) setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 725
 726                 if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
 727                         return -errno;
 728         } else
 729                 return -EAFNOSUPPORT;
 730
 731         return 0;
 732 }
 733
 734 int dns_scope_llmnr_membership(DnsScope *s, bool b) {
 735         assert(s);
 736
 737         if (s->protocol != DNS_PROTOCOL_LLMNR)
 738                 return 0;
 739
 740         return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS);
 741 }
 742
 743 int dns_scope_mdns_membership(DnsScope *s, bool b) {
 744         assert(s);
 745
 746         if (s->protocol != DNS_PROTOCOL_MDNS)
 747                 return 0;
 748
 749         return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS);
 750 }
 751
 752 int dns_scope_make_reply_packet(
 753                 DnsScope *s,
 754                 uint16_t id,
 755                 int rcode,
 756                 DnsQuestion *q,
 757                 DnsAnswer *answer,
 758                 DnsAnswer *soa,
 759                 bool tentative,
 760                 DnsPacket **ret) {
 761
 762         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 763         int r;
 764
 765         assert(s);
 766         assert(ret);
 767
 768         if (dns_question_isempty(q) &&
 769             dns_answer_isempty(answer) &&
 770             dns_answer_isempty(soa))
 771                 return -EINVAL;
 772
 773         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 774         if (r < 0)
 775                 return r;
 776
 777         DNS_PACKET_HEADER(p)->id = id;
 778         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 779                                                               1 /* qr */,
 780                                                               0 /* opcode */,
 781                                                               0 /* c */,
 782                                                               0 /* tc */,
 783                                                               tentative,
 784                                                               0 /* (ra) */,
 785                                                               0 /* (ad) */,
 786                                                               0 /* (cd) */,
 787                                                               rcode));
 788
 789         r = dns_packet_append_question(p, q);
 790         if (r < 0)
 791                 return r;
 792         DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
 793
 794         r = dns_packet_append_answer(p, answer);
 795         if (r < 0)
 796                 return r;
 797         DNS_PACKET_HEADER(p)->ancount = htobe16(dns_answer_size(answer));
 798
 799         r = dns_packet_append_answer(p, soa);
 800         if (r < 0)
 801                 return r;
 802         DNS_PACKET_HEADER(p)->arcount = htobe16(dns_answer_size(soa));
 803
 804         *ret = TAKE_PTR(p);
 805
 806         return 0;
 807 }
 808
 809 static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) {
 810         DnsResourceRecord *rr;
 811         DnsResourceKey *key;
 812
 813         assert(s);
 814         assert(p);
 815
 816         DNS_QUESTION_FOREACH(key, p->question)
 817                 dns_zone_verify_conflicts(&s->zone, key);
 818
 819         DNS_ANSWER_FOREACH(rr, p->answer)
 820                 dns_zone_verify_conflicts(&s->zone, rr->key);
 821 }
 822
 823 void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
 824         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
 825         _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
 826         DnsResourceKey *key = NULL;
 827         bool tentative = false;
 828         int r;
 829
 830         assert(s);
 831         assert(p);
 832
 833         if (p->protocol != DNS_PROTOCOL_LLMNR)
 834                 return;
 835
 836         if (p->ipproto == IPPROTO_UDP) {
 837                 /* Don't accept UDP queries directed to anything but
 838                  * the LLMNR multicast addresses. See RFC 4795,
 839                  * section 2.5. */
 840
 841                 if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
 842                         return;
 843
 844                 if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS))
 845                         return;
 846         }
 847
 848         r = dns_packet_extract(p);
 849         if (r < 0) {
 850                 log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
 851                 return;
 852         }
 853
 854         if (DNS_PACKET_LLMNR_C(p)) {
 855                 /* Somebody notified us about a possible conflict */
 856                 dns_scope_verify_conflicts(s, p);
 857                 return;
 858         }
 859
 860         assert(dns_question_size(p->question) == 1);
 861         key = p->question->keys[0];
 862
 863         r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
 864         if (r < 0) {
 865                 log_debug_errno(r, "Failed to look up key: %m");
 866                 return;
 867         }
 868         if (r == 0)
 869                 return;
 870
 871         if (answer)
 872                 dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0);
 873
 874         r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply);
 875         if (r < 0) {
 876                 log_debug_errno(r, "Failed to build reply packet: %m");
 877                 return;
 878         }
 879
 880         if (stream) {
 881                 r = dns_stream_write_packet(stream, reply);
 882                 if (r < 0) {
 883                         log_debug_errno(r, "Failed to enqueue reply packet: %m");
 884                         return;
 885                 }
 886
 887                 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
 888                  * will be dangling until the stream is disconnected, and the default completion handler of the stream
 889                  * will then unref the stream and destroy it */
 890                 if (DNS_STREAM_QUEUED(stream))
 891                         dns_stream_ref(stream);
 892         } else {
 893                 int fd;
 894
 895                 if (!ratelimit_below(&s->ratelimit))
 896                         return;
 897
 898                 if (p->family == AF_INET)
 899                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 900                 else if (p->family == AF_INET6)
 901                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 902                 else {
 903                         log_debug("Unknown protocol");
 904                         return;
 905                 }
 906                 if (fd < 0) {
 907                         log_debug_errno(fd, "Failed to get reply socket: %m");
 908                         return;
 909                 }
 910
 911                 /* Note that we always immediately reply to all LLMNR
 912                  * requests, and do not wait any time, since we
 913                  * verified uniqueness for all records. Also see RFC
 914                  * 4795, Section 2.7 */
 915
 916                 r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, NULL, reply);
 917                 if (r < 0) {
 918                         log_debug_errno(r, "Failed to send reply packet: %m");
 919                         return;
 920                 }
 921         }
 922 }
 923
 924 DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsResourceKey *key, bool cache_ok) {
 925         DnsTransaction *t;
 926
 927         assert(scope);
 928         assert(key);
 929
 930         /* Try to find an ongoing transaction that is a equal to the
 931          * specified question */
 932         t = hashmap_get(scope->transactions_by_key, key);
 933         if (!t)
 934                 return NULL;
 935
 936         /* Refuse reusing transactions that completed based on cached
 937          * data instead of a real packet, if that's requested. */
 938         if (!cache_ok &&
 939             IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_RCODE_FAILURE) &&
 940             t->answer_source != DNS_TRANSACTION_NETWORK)
 941                 return NULL;
 942
 943         return t;
 944 }
 945
 946 static int dns_scope_make_conflict_packet(
 947                 DnsScope *s,
 948                 DnsResourceRecord *rr,
 949                 DnsPacket **ret) {
 950
 951         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 952         int r;
 953
 954         assert(s);
 955         assert(rr);
 956         assert(ret);
 957
 958         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 959         if (r < 0)
 960                 return r;
 961
 962         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 963                                                               0 /* qr */,
 964                                                               0 /* opcode */,
 965                                                               1 /* conflict */,
 966                                                               0 /* tc */,
 967                                                               0 /* t */,
 968                                                               0 /* (ra) */,
 969                                                               0 /* (ad) */,
 970                                                               0 /* (cd) */,
 971                                                               0));
 972
 973         /* For mDNS, the transaction ID should always be 0 */
 974         if (s->protocol != DNS_PROTOCOL_MDNS)
 975                 random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t));
 976
 977         DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
 978         DNS_PACKET_HEADER(p)->arcount = htobe16(1);
 979
 980         r = dns_packet_append_key(p, rr->key, 0, NULL);
 981         if (r < 0)
 982                 return r;
 983
 984         r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
 985         if (r < 0)
 986                 return r;
 987
 988         *ret = TAKE_PTR(p);
 989
 990         return 0;
 991 }
 992
 993 static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) {
 994         DnsScope *scope = userdata;
 995         int r;
 996
 997         assert(es);
 998         assert(scope);
 999
1000         scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source);
1001
1002         for (;;) {
1003                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1004                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1005                 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1006
1007                 key = ordered_hashmap_first_key(scope->conflict_queue);
1008                 if (!key)
1009                         break;
1010
1011                 rr = ordered_hashmap_remove(scope->conflict_queue, key);
1012                 assert(rr);
1013
1014                 r = dns_scope_make_conflict_packet(scope, rr, &p);
1015                 if (r < 0) {
1016                         log_error_errno(r, "Failed to make conflict packet: %m");
1017                         return 0;
1018                 }
1019
1020                 r = dns_scope_emit_udp(scope, -1, p);
1021                 if (r < 0)
1022                         log_debug_errno(r, "Failed to send conflict packet: %m");
1023         }
1024
1025         return 0;
1026 }
1027
1028 int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
1029         usec_t jitter;
1030         int r;
1031
1032         assert(scope);
1033         assert(rr);
1034
1035         /* We don't send these queries immediately. Instead, we queue
1036          * them, and send them after some jitter delay. */
1037         r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops);
1038         if (r < 0) {
1039                 log_oom();
1040                 return r;
1041         }
1042
1043         /* We only place one RR per key in the conflict
1044          * messages, not all of them. That should be enough to
1045          * indicate where there might be a conflict */
1046         r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr);
1047         if (IN_SET(r, 0, -EEXIST))
1048                 return 0;
1049         if (r < 0)
1050                 return log_debug_errno(r, "Failed to queue conflicting RR: %m");
1051
1052         dns_resource_key_ref(rr->key);
1053         dns_resource_record_ref(rr);
1054
1055         if (scope->conflict_event_source)
1056                 return 0;
1057
1058         random_bytes(&jitter, sizeof(jitter));
1059         jitter %= LLMNR_JITTER_INTERVAL_USEC;
1060
1061         r = sd_event_add_time(scope->manager->event,
1062                               &scope->conflict_event_source,
1063                               clock_boottime_or_monotonic(),
1064                               now(clock_boottime_or_monotonic()) + jitter,
1065                               LLMNR_JITTER_INTERVAL_USEC,
1066                               on_conflict_dispatch, scope);
1067         if (r < 0)
1068                 return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
1069
1070         (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
1071
1072         return 0;
1073 }
1074
1075 void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
1076         DnsResourceRecord *rr;
1077         int r;
1078
1079         assert(scope);
1080         assert(p);
1081
1082         if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS))
1083                 return;
1084
1085         if (DNS_PACKET_RRCOUNT(p) <= 0)
1086                 return;
1087
1088         if (p->protocol == DNS_PROTOCOL_LLMNR) {
1089                 if (DNS_PACKET_LLMNR_C(p) != 0)
1090                         return;
1091
1092                 if (DNS_PACKET_LLMNR_T(p) != 0)
1093                         return;
1094         }
1095
1096         if (manager_our_packet(scope->manager, p))
1097                 return;
1098
1099         r = dns_packet_extract(p);
1100         if (r < 0) {
1101                 log_debug_errno(r, "Failed to extract packet: %m");
1102                 return;
1103         }
1104
1105         log_debug("Checking for conflicts...");
1106
1107         DNS_ANSWER_FOREACH(rr, p->answer) {
1108                 /* No conflict if it is DNS-SD RR used for service enumeration. */
1109                 if (dns_resource_key_is_dnssd_ptr(rr->key))
1110                         continue;
1111
1112                 /* Check for conflicts against the local zone. If we
1113                  * found one, we won't check any further */
1114                 r = dns_zone_check_conflicts(&scope->zone, rr);
1115                 if (r != 0)
1116                         continue;
1117
1118                 /* Check for conflicts against the local cache. If so,
1119                  * send out an advisory query, to inform everybody */
1120                 r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender);
1121                 if (r <= 0)
1122                         continue;
1123
1124                 dns_scope_notify_conflict(scope, rr);
1125         }
1126 }
1127
1128 void dns_scope_dump(DnsScope *s, FILE *f) {
1129         assert(s);
1130
1131         if (!f)
1132                 f = stdout;
1133
1134         fputs("[Scope protocol=", f);
1135         fputs(dns_protocol_to_string(s->protocol), f);
1136
1137         if (s->link) {
1138                 fputs(" interface=", f);
1139                 fputs(s->link->ifname, f);
1140         }
1141
1142         if (s->family != AF_UNSPEC) {
1143                 fputs(" family=", f);
1144                 fputs(af_to_name(s->family), f);
1145         }
1146
1147         fputs("]\n", f);
1148
1149         if (!dns_zone_is_empty(&s->zone)) {
1150                 fputs("ZONE:\n", f);
1151                 dns_zone_dump(&s->zone, f);
1152         }
1153
1154         if (!dns_cache_is_empty(&s->cache)) {
1155                 fputs("CACHE:\n", f);
1156                 dns_cache_dump(&s->cache, f);
1157         }
1158 }
1159
1160 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
1161         assert(s);
1162
1163         if (s->protocol != DNS_PROTOCOL_DNS)
1164                 return NULL;
1165
1166         if (s->link)
1167                 return s->link->search_domains;
1168
1169         return s->manager->search_domains;
1170 }
1171
1172 bool dns_scope_name_needs_search_domain(DnsScope *s, const char *name) {
1173         assert(s);
1174
1175         if (s->protocol != DNS_PROTOCOL_DNS)
1176                 return false;
1177
1178         return dns_name_is_single_label(name);
1179 }
1180
1181 bool dns_scope_network_good(DnsScope *s) {
1182         /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1183          * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1184          * DNS scope we check whether there are any links that are up and have an address. */
1185
1186         if (s->link)
1187                 return true;
1188
1189         return manager_routable(s->manager, AF_UNSPEC);
1190 }
1191
1192 int dns_scope_ifindex(DnsScope *s) {
1193         assert(s);
1194
1195         if (s->link)
1196                 return s->link->ifindex;
1197
1198         return 0;
1199 }
1200
1201 static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1202         DnsScope *scope = userdata;
1203
1204         assert(s);
1205
1206         scope->announce_event_source = sd_event_source_unref(scope->announce_event_source);
1207
1208         (void) dns_scope_announce(scope, false);
1209         return 0;
1210 }
1211
1212 int dns_scope_announce(DnsScope *scope, bool goodbye) {
1213         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1214         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1215         _cleanup_set_free_ Set *types = NULL;
1216         DnsTransaction *t;
1217         DnsZoneItem *z, *i;
1218         unsigned size = 0;
1219         Iterator iterator;
1220         char *service_type;
1221         int r;
1222
1223         if (!scope)
1224                 return 0;
1225
1226         if (scope->protocol != DNS_PROTOCOL_MDNS)
1227                 return 0;
1228
1229         /* Check if we're done with probing. */
1230         LIST_FOREACH(transactions_by_scope, t, scope->transactions)
1231                 if (DNS_TRANSACTION_IS_LIVE(t->state))
1232                         return 0;
1233
1234         /* Check if there're services pending conflict resolution. */
1235         if (manager_next_dnssd_names(scope->manager))
1236                 return 0; /* we reach this point only if changing hostname didn't help */
1237
1238         /* Calculate answer's size. */
1239         HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
1240                 if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
1241                         continue;
1242
1243                 if (z->rr->key->type == DNS_TYPE_PTR &&
1244                     !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
1245                         char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1246
1247                         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));
1248                         z->state = DNS_ZONE_ITEM_WITHDRAWN;
1249                         continue;
1250                 }
1251
1252                 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1253                 if (!scope->announced &&
1254                     dns_resource_key_is_dnssd_ptr(z->rr->key)) {
1255                         if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
1256                                 r = set_ensure_allocated(&types, &dns_name_hash_ops);
1257                                 if (r < 0)
1258                                         return log_debug_errno(r, "Failed to allocate set: %m");
1259
1260                                 r = set_put(types, dns_resource_key_name(z->rr->key));
1261                                 if (r < 0)
1262                                         return log_debug_errno(r, "Failed to add item to set: %m");
1263                         }
1264                 }
1265
1266                 LIST_FOREACH(by_key, i, z)
1267                         size++;
1268         }
1269
1270         answer = dns_answer_new(size + set_size(types));
1271         if (!answer)
1272                 return log_oom();
1273
1274         /* Second iteration, actually add RRs to the answer. */
1275         HASHMAP_FOREACH(z, scope->zone.by_key, iterator)
1276                 LIST_FOREACH (by_key, i, z) {
1277                         DnsAnswerFlags flags;
1278
1279                         if (i->state != DNS_ZONE_ITEM_ESTABLISHED)
1280                                 continue;
1281
1282                         if (dns_resource_key_is_dnssd_ptr(i->rr->key))
1283                                 flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
1284                         else
1285                                 flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
1286
1287                         r = dns_answer_add(answer, i->rr, 0 , flags);
1288                         if (r < 0)
1289                                 return log_debug_errno(r, "Failed to add RR to announce: %m");
1290                 }
1291
1292         /* Since all the active services are in the zone make them discoverable now. */
1293         SET_FOREACH(service_type, types, iterator) {
1294                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr;
1295
1296                 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
1297                                                   "_services._dns-sd._udp.local");
1298                 rr->ptr.name = strdup(service_type);
1299                 rr->ttl = MDNS_DEFAULT_TTL;
1300
1301                 r = dns_zone_put(&scope->zone, scope, rr, false);
1302                 if (r < 0)
1303                         log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m");
1304
1305                 r = dns_answer_add(answer, rr, 0 , 0);
1306                 if (r < 0)
1307                         return log_debug_errno(r, "Failed to add RR to announce: %m");
1308         }
1309
1310         if (dns_answer_isempty(answer))
1311                 return 0;
1312
1313         r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p);
1314         if (r < 0)
1315                 return log_debug_errno(r, "Failed to build reply packet: %m");
1316
1317         r = dns_scope_emit_udp(scope, -1, p);
1318         if (r < 0)
1319                 return log_debug_errno(r, "Failed to send reply packet: %m");
1320
1321         /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1322          * responses, one second apart." */
1323         if (!scope->announced) {
1324                 usec_t ts;
1325
1326                 scope->announced = true;
1327
1328                 assert_se(sd_event_now(scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1329                 ts += MDNS_ANNOUNCE_DELAY;
1330
1331                 r = sd_event_add_time(
1332                                 scope->manager->event,
1333                                 &scope->announce_event_source,
1334                                 clock_boottime_or_monotonic(),
1335                                 ts,
1336                                 MDNS_JITTER_RANGE_USEC,
1337                                 on_announcement_timeout, scope);
1338                 if (r < 0)
1339                         return log_debug_errno(r, "Failed to schedule second announcement: %m");
1340
1341                 (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce");
1342         }
1343
1344         return 0;
1345 }
1346
1347 int dns_scope_add_dnssd_services(DnsScope *scope) {
1348         Iterator i;
1349         DnssdService *service;
1350         DnssdTxtData *txt_data;
1351         int r;
1352
1353         assert(scope);
1354
1355         if (hashmap_size(scope->manager->dnssd_services) == 0)
1356                 return 0;
1357
1358         scope->announced = false;
1359
1360         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1361                 service->withdrawn = false;
1362
1363                 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
1364                 if (r < 0)
1365                         log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");
1366
1367                 r = dns_zone_put(&scope->zone, scope, service->srv_rr, true);
1368                 if (r < 0)
1369                         log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m");
1370
1371                 LIST_FOREACH(items, txt_data, service->txt_data_items) {
1372                         r = dns_zone_put(&scope->zone, scope, txt_data->rr, true);
1373                         if (r < 0)
1374                                 log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m");
1375                 }
1376         }
1377
1378         return 0;
1379 }
1380
1381 int dns_scope_remove_dnssd_services(DnsScope *scope) {
1382         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1383         Iterator i;
1384         DnssdService *service;
1385         DnssdTxtData *txt_data;
1386         int r;
1387
1388         assert(scope);
1389
1390         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR,
1391                                    "_services._dns-sd._udp.local");
1392         if (!key)
1393                 return log_oom();
1394
1395         r = dns_zone_remove_rrs_by_key(&scope->zone, key);
1396         if (r < 0)
1397                 return r;
1398
1399         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1400                 dns_zone_remove_rr(&scope->zone, service->ptr_rr);
1401                 dns_zone_remove_rr(&scope->zone, service->srv_rr);
1402                 LIST_FOREACH(items, txt_data, service->txt_data_items)
1403                         dns_zone_remove_rr(&scope->zone, txt_data->rr);
1404         }
1405
1406         return 0;
1407 }
1408
1409 static bool dns_scope_has_route_only_domains(DnsScope *scope) {
1410         DnsSearchDomain *domain, *first;
1411         bool route_only = false;
1412
1413         assert(scope);
1414         assert(scope->protocol == DNS_PROTOCOL_DNS);
1415
1416         /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check
1417          * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links
1418          * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to
1419          * take queries to arbitrary domains, i.e. has no routing domains set. */
1420
1421         if (scope->link)
1422                 first = scope->link->search_domains;
1423         else
1424                 first = scope->manager->search_domains;
1425
1426         LIST_FOREACH(domains, domain, first) {
1427                 /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early
1428                  * here, as it doesn't really matter whether this link has any route-only domains or not,
1429                  * "~."  really trumps everything and clearly indicates that this interface shall receive all
1430                  * traffic it can get. */
1431                 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain)))
1432                         return false;
1433
1434                 if (domain->route_only)
1435                         route_only = true;
1436         }
1437
1438         return route_only;
1439 }
1440
1441 bool dns_scope_is_default_route(DnsScope *scope) {
1442         assert(scope);
1443
1444         /* Only use DNS scopes as default routes */
1445         if (scope->protocol != DNS_PROTOCOL_DNS)
1446                 return false;
1447
1448         /* The global DNS scope is always suitable as default route */
1449         if (!scope->link)
1450                 return true;
1451
1452         /* Honour whatever is explicitly configured. This is really the best approach, and trumps any
1453          * automatic logic. */
1454         if (scope->link->default_route >= 0)
1455                 return scope->link->default_route;
1456
1457         /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not
1458          * volunteer as default route. */
1459         return !dns_scope_has_route_only_domains(scope);
1460 }