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.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         RATELIMIT_INIT(s->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 responisble
 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
 500          * this scope. Note that this accepts non-qualified hostnames,
 501          * i.e. those without any search path prefixed yet. */
 502
 503         if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
 504                 return DNS_SCOPE_NO;
 505
 506         if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & flags) == 0)
 507                 return DNS_SCOPE_NO;
 508
 509         /* Never resolve any loopback hostname or IP address via DNS,
 510          * LLMNR or mDNS. Instead, always rely on synthesized RRs for
 511          * these. */
 512         if (is_localhost(domain) ||
 513             dns_name_endswith(domain, "127.in-addr.arpa") > 0 ||
 514             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)
 515                 return DNS_SCOPE_NO;
 516
 517         /* Never respond to some of the domains listed in RFC6303 */
 518         if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 ||
 519             dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 ||
 520             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)
 521                 return DNS_SCOPE_NO;
 522
 523         /* Never respond to some of the domains listed in RFC6761 */
 524         if (dns_name_endswith(domain, "invalid") > 0)
 525                 return DNS_SCOPE_NO;
 526
 527         switch (s->protocol) {
 528
 529         case DNS_PROTOCOL_DNS: {
 530                 bool has_search_domains = false;
 531                 int n_best = -1;
 532
 533                 /* Never route things to scopes that lack DNS servers */
 534                 if (!dns_scope_get_dns_server(s))
 535                         return DNS_SCOPE_NO;
 536
 537                 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
 538                  * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
 539                  * won't be considered anymore. */
 540                 LIST_FOREACH(domains, d, dns_scope_get_search_domains(s)) {
 541
 542                         if (!d->route_only && !dns_name_is_root(d->name))
 543                                 has_search_domains = true;
 544
 545                         if (dns_name_endswith(domain, d->name) > 0) {
 546                                 int c;
 547
 548                                 c = dns_name_count_labels(d->name);
 549                                 if (c < 0)
 550                                         continue;
 551
 552                                 if (c > n_best)
 553                                         n_best = c;
 554                         }
 555                 }
 556
 557                 /* If there's a true search domain defined for this scope, and the query is single-label,
 558                  * then let's resolve things here, prefereably. Note that LLMNR considers itself
 559                  * authoritative for single-label names too, at the same preference, see below. */
 560                 if (has_search_domains && dns_name_is_single_label(domain))
 561                         return DNS_SCOPE_YES_BASE + 1;
 562
 563                 /* Let's return the number of labels in the best matching result */
 564                 if (n_best >= 0) {
 565                         assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE);
 566                         return DNS_SCOPE_YES_BASE + n_best;
 567                 }
 568
 569                 /* See if this scope is suitable as default route. */
 570                 if (!dns_scope_is_default_route(s))
 571                         return DNS_SCOPE_NO;
 572
 573                 /* Exclude link-local IP ranges */
 574                 if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
 575                     dns_name_endswith(domain, "8.e.f.ip6.arpa") == 0 &&
 576                     dns_name_endswith(domain, "9.e.f.ip6.arpa") == 0 &&
 577                     dns_name_endswith(domain, "a.e.f.ip6.arpa") == 0 &&
 578                     dns_name_endswith(domain, "b.e.f.ip6.arpa") == 0 &&
 579                     /* If networks use .local in their private setups, they are supposed to also add .local to their search
 580                      * domains, which we already checked above. Otherwise, we consider .local specific to mDNS and won't
 581                      * send such queries ordinary DNS servers. */
 582                     dns_name_endswith(domain, "local") == 0)
 583                         return DNS_SCOPE_MAYBE;
 584
 585                 return DNS_SCOPE_NO;
 586         }
 587
 588         case DNS_PROTOCOL_MDNS: {
 589                 DnsScopeMatch m;
 590
 591                 m = accept_link_local_reverse_lookups(domain);
 592                 if (m >= 0)
 593                         return m;
 594
 595                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 596                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
 597                         return DNS_SCOPE_MAYBE;
 598
 599                 if ((dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */
 600                      dns_name_equal(domain, "local") == 0 &&   /* but not the single-label "local" name itself */
 601                      manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */
 602                         return DNS_SCOPE_YES_BASE + 1; /* Return +1, as the top-level .local domain matches, i.e. one label */
 603
 604                 return DNS_SCOPE_NO;
 605         }
 606
 607         case DNS_PROTOCOL_LLMNR: {
 608                 DnsScopeMatch m;
 609
 610                 m = accept_link_local_reverse_lookups(domain);
 611                 if (m >= 0)
 612                         return m;
 613
 614                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 615                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0))
 616                         return DNS_SCOPE_MAYBE;
 617
 618                 if ((dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
 619                      !is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
 620                      manager_is_own_hostname(s->manager, domain) <= 0))  /* never resolve the local hostname via LLMNR */
 621                         return DNS_SCOPE_YES_BASE + 1; /* Return +1, as we consider ourselves authoritative
 622                                                         * for single-label names, i.e. one label. This is
 623                                                         * particular relevant as it means a "." route on some
 624                                                         * other scope won't pull all traffic away from
 625                                                         * us. (If people actually want to pull traffic away
 626                                                         * from us they should turn off LLMNR on the
 627                                                         * link). Note that unicast DNS scopes with search
 628                                                         * domains also consider themselves authoritative for
 629                                                         * single-label domains, at the same preference (see
 630                                                         * above). */
 631
 632                 return DNS_SCOPE_NO;
 633         }
 634
 635         default:
 636                 assert_not_reached("Unknown scope protocol");
 637         }
 638 }
 639
 640 bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) {
 641         int key_family;
 642
 643         assert(s);
 644         assert(key);
 645
 646         /* Check if it makes sense to resolve the specified key on
 647          * this scope. Note that this call assumes as fully qualified
 648          * name, i.e. the search suffixes already appended. */
 649
 650         if (key->class != DNS_CLASS_IN)
 651                 return false;
 652
 653         if (s->protocol == DNS_PROTOCOL_DNS) {
 654
 655                 /* On classic DNS, looking up non-address RRs is always
 656                  * fine. (Specifically, we want to permit looking up
 657                  * DNSKEY and DS records on the root and top-level
 658                  * domains.) */
 659                 if (!dns_resource_key_is_address(key))
 660                         return true;
 661
 662                 /* However, we refuse to look up A and AAAA RRs on the
 663                  * root and single-label domains, under the assumption
 664                  * that those should be resolved via LLMNR or search
 665                  * path only, and should not be leaked onto the
 666                  * internet. */
 667                 return !(dns_name_is_single_label(dns_resource_key_name(key)) ||
 668                          dns_name_is_root(dns_resource_key_name(key)));
 669         }
 670
 671         /* On mDNS and LLMNR, send A and AAAA queries only on the
 672          * respective scopes */
 673
 674         key_family = dns_type_to_af(key->type);
 675         if (key_family < 0)
 676                 return true;
 677
 678         return key_family == s->family;
 679 }
 680
 681 static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) {
 682         int fd;
 683
 684         assert(s);
 685         assert(s->link);
 686
 687         if (s->family == AF_INET) {
 688                 struct ip_mreqn mreqn = {
 689                         .imr_multiaddr = in,
 690                         .imr_ifindex = s->link->ifindex,
 691                 };
 692
 693                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 694                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 695                 else
 696                         fd = manager_mdns_ipv4_fd(s->manager);
 697
 698                 if (fd < 0)
 699                         return fd;
 700
 701                 /* Always first try to drop membership before we add
 702                  * one. This is necessary on some devices, such as
 703                  * veth. */
 704                 if (b)
 705                         (void) setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn));
 706
 707                 if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0)
 708                         return -errno;
 709
 710         } else if (s->family == AF_INET6) {
 711                 struct ipv6_mreq mreq = {
 712                         .ipv6mr_multiaddr = in6,
 713                         .ipv6mr_interface = s->link->ifindex,
 714                 };
 715
 716                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 717                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 718                 else
 719                         fd = manager_mdns_ipv6_fd(s->manager);
 720
 721                 if (fd < 0)
 722                         return fd;
 723
 724                 if (b)
 725                         (void) setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 726
 727                 if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
 728                         return -errno;
 729         } else
 730                 return -EAFNOSUPPORT;
 731
 732         return 0;
 733 }
 734
 735 int dns_scope_llmnr_membership(DnsScope *s, bool b) {
 736         assert(s);
 737
 738         if (s->protocol != DNS_PROTOCOL_LLMNR)
 739                 return 0;
 740
 741         return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS);
 742 }
 743
 744 int dns_scope_mdns_membership(DnsScope *s, bool b) {
 745         assert(s);
 746
 747         if (s->protocol != DNS_PROTOCOL_MDNS)
 748                 return 0;
 749
 750         return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS);
 751 }
 752
 753 int dns_scope_make_reply_packet(
 754                 DnsScope *s,
 755                 uint16_t id,
 756                 int rcode,
 757                 DnsQuestion *q,
 758                 DnsAnswer *answer,
 759                 DnsAnswer *soa,
 760                 bool tentative,
 761                 DnsPacket **ret) {
 762
 763         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 764         int r;
 765
 766         assert(s);
 767         assert(ret);
 768
 769         if (dns_question_isempty(q) &&
 770             dns_answer_isempty(answer) &&
 771             dns_answer_isempty(soa))
 772                 return -EINVAL;
 773
 774         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 775         if (r < 0)
 776                 return r;
 777
 778         DNS_PACKET_HEADER(p)->id = id;
 779         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 780                                                               1 /* qr */,
 781                                                               0 /* opcode */,
 782                                                               0 /* c */,
 783                                                               0 /* tc */,
 784                                                               tentative,
 785                                                               0 /* (ra) */,
 786                                                               0 /* (ad) */,
 787                                                               0 /* (cd) */,
 788                                                               rcode));
 789
 790         r = dns_packet_append_question(p, q);
 791         if (r < 0)
 792                 return r;
 793         DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
 794
 795         r = dns_packet_append_answer(p, answer);
 796         if (r < 0)
 797                 return r;
 798         DNS_PACKET_HEADER(p)->ancount = htobe16(dns_answer_size(answer));
 799
 800         r = dns_packet_append_answer(p, soa);
 801         if (r < 0)
 802                 return r;
 803         DNS_PACKET_HEADER(p)->arcount = htobe16(dns_answer_size(soa));
 804
 805         *ret = TAKE_PTR(p);
 806
 807         return 0;
 808 }
 809
 810 static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) {
 811         DnsResourceRecord *rr;
 812         DnsResourceKey *key;
 813
 814         assert(s);
 815         assert(p);
 816
 817         DNS_QUESTION_FOREACH(key, p->question)
 818                 dns_zone_verify_conflicts(&s->zone, key);
 819
 820         DNS_ANSWER_FOREACH(rr, p->answer)
 821                 dns_zone_verify_conflicts(&s->zone, rr->key);
 822 }
 823
 824 void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
 825         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
 826         _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
 827         DnsResourceKey *key = NULL;
 828         bool tentative = false;
 829         int r;
 830
 831         assert(s);
 832         assert(p);
 833
 834         if (p->protocol != DNS_PROTOCOL_LLMNR)
 835                 return;
 836
 837         if (p->ipproto == IPPROTO_UDP) {
 838                 /* Don't accept UDP queries directed to anything but
 839                  * the LLMNR multicast addresses. See RFC 4795,
 840                  * section 2.5. */
 841
 842                 if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
 843                         return;
 844
 845                 if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS))
 846                         return;
 847         }
 848
 849         r = dns_packet_extract(p);
 850         if (r < 0) {
 851                 log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
 852                 return;
 853         }
 854
 855         if (DNS_PACKET_LLMNR_C(p)) {
 856                 /* Somebody notified us about a possible conflict */
 857                 dns_scope_verify_conflicts(s, p);
 858                 return;
 859         }
 860
 861         assert(dns_question_size(p->question) == 1);
 862         key = p->question->keys[0];
 863
 864         r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
 865         if (r < 0) {
 866                 log_debug_errno(r, "Failed to lookup key: %m");
 867                 return;
 868         }
 869         if (r == 0)
 870                 return;
 871
 872         if (answer)
 873                 dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0);
 874
 875         r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply);
 876         if (r < 0) {
 877                 log_debug_errno(r, "Failed to build reply packet: %m");
 878                 return;
 879         }
 880
 881         if (stream) {
 882                 r = dns_stream_write_packet(stream, reply);
 883                 if (r < 0) {
 884                         log_debug_errno(r, "Failed to enqueue reply packet: %m");
 885                         return;
 886                 }
 887
 888                 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
 889                  * will be dangling until the stream is disconnected, and the default completion handler of the stream
 890                  * will then unref the stream and destroy it */
 891                 if (DNS_STREAM_QUEUED(stream))
 892                         dns_stream_ref(stream);
 893         } else {
 894                 int fd;
 895
 896                 if (!ratelimit_below(&s->ratelimit))
 897                         return;
 898
 899                 if (p->family == AF_INET)
 900                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 901                 else if (p->family == AF_INET6)
 902                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 903                 else {
 904                         log_debug("Unknown protocol");
 905                         return;
 906                 }
 907                 if (fd < 0) {
 908                         log_debug_errno(fd, "Failed to get reply socket: %m");
 909                         return;
 910                 }
 911
 912                 /* Note that we always immediately reply to all LLMNR
 913                  * requests, and do not wait any time, since we
 914                  * verified uniqueness for all records. Also see RFC
 915                  * 4795, Section 2.7 */
 916
 917                 r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, NULL, reply);
 918                 if (r < 0) {
 919                         log_debug_errno(r, "Failed to send reply packet: %m");
 920                         return;
 921                 }
 922         }
 923 }
 924
 925 DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsResourceKey *key, bool cache_ok) {
 926         DnsTransaction *t;
 927
 928         assert(scope);
 929         assert(key);
 930
 931         /* Try to find an ongoing transaction that is a equal to the
 932          * specified question */
 933         t = hashmap_get(scope->transactions_by_key, key);
 934         if (!t)
 935                 return NULL;
 936
 937         /* Refuse reusing transactions that completed based on cached
 938          * data instead of a real packet, if that's requested. */
 939         if (!cache_ok &&
 940             IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_RCODE_FAILURE) &&
 941             t->answer_source != DNS_TRANSACTION_NETWORK)
 942                 return NULL;
 943
 944         return t;
 945 }
 946
 947 static int dns_scope_make_conflict_packet(
 948                 DnsScope *s,
 949                 DnsResourceRecord *rr,
 950                 DnsPacket **ret) {
 951
 952         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 953         int r;
 954
 955         assert(s);
 956         assert(rr);
 957         assert(ret);
 958
 959         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 960         if (r < 0)
 961                 return r;
 962
 963         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 964                                                               0 /* qr */,
 965                                                               0 /* opcode */,
 966                                                               1 /* conflict */,
 967                                                               0 /* tc */,
 968                                                               0 /* t */,
 969                                                               0 /* (ra) */,
 970                                                               0 /* (ad) */,
 971                                                               0 /* (cd) */,
 972                                                               0));
 973
 974         /* For mDNS, the transaction ID should always be 0 */
 975         if (s->protocol != DNS_PROTOCOL_MDNS)
 976                 random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t));
 977
 978         DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
 979         DNS_PACKET_HEADER(p)->arcount = htobe16(1);
 980
 981         r = dns_packet_append_key(p, rr->key, 0, NULL);
 982         if (r < 0)
 983                 return r;
 984
 985         r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
 986         if (r < 0)
 987                 return r;
 988
 989         *ret = TAKE_PTR(p);
 990
 991         return 0;
 992 }
 993
 994 static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) {
 995         DnsScope *scope = userdata;
 996         int r;
 997
 998         assert(es);
 999         assert(scope);
1000
1001         scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source);
1002
1003         for (;;) {
1004                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1005                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
1006                 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1007
1008                 key = ordered_hashmap_first_key(scope->conflict_queue);
1009                 if (!key)
1010                         break;
1011
1012                 rr = ordered_hashmap_remove(scope->conflict_queue, key);
1013                 assert(rr);
1014
1015                 r = dns_scope_make_conflict_packet(scope, rr, &p);
1016                 if (r < 0) {
1017                         log_error_errno(r, "Failed to make conflict packet: %m");
1018                         return 0;
1019                 }
1020
1021                 r = dns_scope_emit_udp(scope, -1, p);
1022                 if (r < 0)
1023                         log_debug_errno(r, "Failed to send conflict packet: %m");
1024         }
1025
1026         return 0;
1027 }
1028
1029 int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
1030         usec_t jitter;
1031         int r;
1032
1033         assert(scope);
1034         assert(rr);
1035
1036         /* We don't send these queries immediately. Instead, we queue
1037          * them, and send them after some jitter delay. */
1038         r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops);
1039         if (r < 0) {
1040                 log_oom();
1041                 return r;
1042         }
1043
1044         /* We only place one RR per key in the conflict
1045          * messages, not all of them. That should be enough to
1046          * indicate where there might be a conflict */
1047         r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr);
1048         if (IN_SET(r, 0, -EEXIST))
1049                 return 0;
1050         if (r < 0)
1051                 return log_debug_errno(r, "Failed to queue conflicting RR: %m");
1052
1053         dns_resource_key_ref(rr->key);
1054         dns_resource_record_ref(rr);
1055
1056         if (scope->conflict_event_source)
1057                 return 0;
1058
1059         random_bytes(&jitter, sizeof(jitter));
1060         jitter %= LLMNR_JITTER_INTERVAL_USEC;
1061
1062         r = sd_event_add_time(scope->manager->event,
1063                               &scope->conflict_event_source,
1064                               clock_boottime_or_monotonic(),
1065                               now(clock_boottime_or_monotonic()) + jitter,
1066                               LLMNR_JITTER_INTERVAL_USEC,
1067                               on_conflict_dispatch, scope);
1068         if (r < 0)
1069                 return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
1070
1071         (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
1072
1073         return 0;
1074 }
1075
1076 void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
1077         DnsResourceRecord *rr;
1078         int r;
1079
1080         assert(scope);
1081         assert(p);
1082
1083         if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS))
1084                 return;
1085
1086         if (DNS_PACKET_RRCOUNT(p) <= 0)
1087                 return;
1088
1089         if (p->protocol == DNS_PROTOCOL_LLMNR) {
1090                 if (DNS_PACKET_LLMNR_C(p) != 0)
1091                         return;
1092
1093                 if (DNS_PACKET_LLMNR_T(p) != 0)
1094                         return;
1095         }
1096
1097         if (manager_our_packet(scope->manager, p))
1098                 return;
1099
1100         r = dns_packet_extract(p);
1101         if (r < 0) {
1102                 log_debug_errno(r, "Failed to extract packet: %m");
1103                 return;
1104         }
1105
1106         log_debug("Checking for conflicts...");
1107
1108         DNS_ANSWER_FOREACH(rr, p->answer) {
1109                 /* No conflict if it is DNS-SD RR used for service enumeration. */
1110                 if (dns_resource_key_is_dnssd_ptr(rr->key))
1111                         continue;
1112
1113                 /* Check for conflicts against the local zone. If we
1114                  * found one, we won't check any further */
1115                 r = dns_zone_check_conflicts(&scope->zone, rr);
1116                 if (r != 0)
1117                         continue;
1118
1119                 /* Check for conflicts against the local cache. If so,
1120                  * send out an advisory query, to inform everybody */
1121                 r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender);
1122                 if (r <= 0)
1123                         continue;
1124
1125                 dns_scope_notify_conflict(scope, rr);
1126         }
1127 }
1128
1129 void dns_scope_dump(DnsScope *s, FILE *f) {
1130         assert(s);
1131
1132         if (!f)
1133                 f = stdout;
1134
1135         fputs("[Scope protocol=", f);
1136         fputs(dns_protocol_to_string(s->protocol), f);
1137
1138         if (s->link) {
1139                 fputs(" interface=", f);
1140                 fputs(s->link->ifname, f);
1141         }
1142
1143         if (s->family != AF_UNSPEC) {
1144                 fputs(" family=", f);
1145                 fputs(af_to_name(s->family), f);
1146         }
1147
1148         fputs("]\n", f);
1149
1150         if (!dns_zone_is_empty(&s->zone)) {
1151                 fputs("ZONE:\n", f);
1152                 dns_zone_dump(&s->zone, f);
1153         }
1154
1155         if (!dns_cache_is_empty(&s->cache)) {
1156                 fputs("CACHE:\n", f);
1157                 dns_cache_dump(&s->cache, f);
1158         }
1159 }
1160
1161 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
1162         assert(s);
1163
1164         if (s->protocol != DNS_PROTOCOL_DNS)
1165                 return NULL;
1166
1167         if (s->link)
1168                 return s->link->search_domains;
1169
1170         return s->manager->search_domains;
1171 }
1172
1173 bool dns_scope_name_needs_search_domain(DnsScope *s, const char *name) {
1174         assert(s);
1175
1176         if (s->protocol != DNS_PROTOCOL_DNS)
1177                 return false;
1178
1179         return dns_name_is_single_label(name);
1180 }
1181
1182 bool dns_scope_network_good(DnsScope *s) {
1183         /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1184          * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1185          * DNS scope we check whether there are any links that are up and have an address. */
1186
1187         if (s->link)
1188                 return true;
1189
1190         return manager_routable(s->manager, AF_UNSPEC);
1191 }
1192
1193 int dns_scope_ifindex(DnsScope *s) {
1194         assert(s);
1195
1196         if (s->link)
1197                 return s->link->ifindex;
1198
1199         return 0;
1200 }
1201
1202 static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1203         DnsScope *scope = userdata;
1204
1205         assert(s);
1206
1207         scope->announce_event_source = sd_event_source_unref(scope->announce_event_source);
1208
1209         (void) dns_scope_announce(scope, false);
1210         return 0;
1211 }
1212
1213 int dns_scope_announce(DnsScope *scope, bool goodbye) {
1214         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1215         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1216         _cleanup_set_free_ Set *types = NULL;
1217         DnsTransaction *t;
1218         DnsZoneItem *z, *i;
1219         unsigned size = 0;
1220         Iterator iterator;
1221         char *service_type;
1222         int r;
1223
1224         if (!scope)
1225                 return 0;
1226
1227         if (scope->protocol != DNS_PROTOCOL_MDNS)
1228                 return 0;
1229
1230         /* Check if we're done with probing. */
1231         LIST_FOREACH(transactions_by_scope, t, scope->transactions)
1232                 if (DNS_TRANSACTION_IS_LIVE(t->state))
1233                         return 0;
1234
1235         /* Check if there're services pending conflict resolution. */
1236         if (manager_next_dnssd_names(scope->manager))
1237                 return 0; /* we reach this point only if changing hostname didn't help */
1238
1239         /* Calculate answer's size. */
1240         HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
1241                 if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
1242                         continue;
1243
1244                 if (z->rr->key->type == DNS_TYPE_PTR &&
1245                     !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
1246                         char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1247
1248                         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));
1249                         z->state = DNS_ZONE_ITEM_WITHDRAWN;
1250                         continue;
1251                 }
1252
1253                 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1254                 if (!scope->announced &&
1255                     dns_resource_key_is_dnssd_ptr(z->rr->key)) {
1256                         if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
1257                                 r = set_ensure_allocated(&types, &dns_name_hash_ops);
1258                                 if (r < 0)
1259                                         return log_debug_errno(r, "Failed to allocate set: %m");
1260
1261                                 r = set_put(types, dns_resource_key_name(z->rr->key));
1262                                 if (r < 0)
1263                                         return log_debug_errno(r, "Failed to add item to set: %m");
1264                         }
1265                 }
1266
1267                 LIST_FOREACH(by_key, i, z)
1268                         size++;
1269         }
1270
1271         answer = dns_answer_new(size + set_size(types));
1272         if (!answer)
1273                 return log_oom();
1274
1275         /* Second iteration, actually add RRs to the answer. */
1276         HASHMAP_FOREACH(z, scope->zone.by_key, iterator)
1277                 LIST_FOREACH (by_key, i, z) {
1278                         DnsAnswerFlags flags;
1279
1280                         if (i->state != DNS_ZONE_ITEM_ESTABLISHED)
1281                                 continue;
1282
1283                         if (dns_resource_key_is_dnssd_ptr(i->rr->key))
1284                                 flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
1285                         else
1286                                 flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
1287
1288                         r = dns_answer_add(answer, i->rr, 0 , flags);
1289                         if (r < 0)
1290                                 return log_debug_errno(r, "Failed to add RR to announce: %m");
1291                 }
1292
1293         /* Since all the active services are in the zone make them discoverable now. */
1294         SET_FOREACH(service_type, types, iterator) {
1295                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr;
1296
1297                 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
1298                                                   "_services._dns-sd._udp.local");
1299                 rr->ptr.name = strdup(service_type);
1300                 rr->ttl = MDNS_DEFAULT_TTL;
1301
1302                 r = dns_zone_put(&scope->zone, scope, rr, false);
1303                 if (r < 0)
1304                         log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m");
1305
1306                 r = dns_answer_add(answer, rr, 0 , 0);
1307                 if (r < 0)
1308                         return log_debug_errno(r, "Failed to add RR to announce: %m");
1309         }
1310
1311         if (dns_answer_isempty(answer))
1312                 return 0;
1313
1314         r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p);
1315         if (r < 0)
1316                 return log_debug_errno(r, "Failed to build reply packet: %m");
1317
1318         r = dns_scope_emit_udp(scope, -1, p);
1319         if (r < 0)
1320                 return log_debug_errno(r, "Failed to send reply packet: %m");
1321
1322         /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1323          * responses, one second apart." */
1324         if (!scope->announced) {
1325                 usec_t ts;
1326
1327                 scope->announced = true;
1328
1329                 assert_se(sd_event_now(scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1330                 ts += MDNS_ANNOUNCE_DELAY;
1331
1332                 r = sd_event_add_time(
1333                                 scope->manager->event,
1334                                 &scope->announce_event_source,
1335                                 clock_boottime_or_monotonic(),
1336                                 ts,
1337                                 MDNS_JITTER_RANGE_USEC,
1338                                 on_announcement_timeout, scope);
1339                 if (r < 0)
1340                         return log_debug_errno(r, "Failed to schedule second announcement: %m");
1341
1342                 (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce");
1343         }
1344
1345         return 0;
1346 }
1347
1348 int dns_scope_add_dnssd_services(DnsScope *scope) {
1349         Iterator i;
1350         DnssdService *service;
1351         DnssdTxtData *txt_data;
1352         int r;
1353
1354         assert(scope);
1355
1356         if (hashmap_size(scope->manager->dnssd_services) == 0)
1357                 return 0;
1358
1359         scope->announced = false;
1360
1361         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1362                 service->withdrawn = false;
1363
1364                 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
1365                 if (r < 0)
1366                         log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");
1367
1368                 r = dns_zone_put(&scope->zone, scope, service->srv_rr, true);
1369                 if (r < 0)
1370                         log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m");
1371
1372                 LIST_FOREACH(items, txt_data, service->txt_data_items) {
1373                         r = dns_zone_put(&scope->zone, scope, txt_data->rr, true);
1374                         if (r < 0)
1375                                 log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m");
1376                 }
1377         }
1378
1379         return 0;
1380 }
1381
1382 int dns_scope_remove_dnssd_services(DnsScope *scope) {
1383         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1384         Iterator i;
1385         DnssdService *service;
1386         DnssdTxtData *txt_data;
1387         int r;
1388
1389         assert(scope);
1390
1391         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR,
1392                                    "_services._dns-sd._udp.local");
1393         if (!key)
1394                 return log_oom();
1395
1396         r = dns_zone_remove_rrs_by_key(&scope->zone, key);
1397         if (r < 0)
1398                 return r;
1399
1400         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1401                 dns_zone_remove_rr(&scope->zone, service->ptr_rr);
1402                 dns_zone_remove_rr(&scope->zone, service->srv_rr);
1403                 LIST_FOREACH(items, txt_data, service->txt_data_items)
1404                         dns_zone_remove_rr(&scope->zone, txt_data->rr);
1405         }
1406
1407         return 0;
1408 }
1409
1410 static bool dns_scope_has_route_only_domains(DnsScope *scope) {
1411         DnsSearchDomain *domain, *first;
1412         bool route_only = false;
1413
1414         assert(scope);
1415         assert(scope->protocol == DNS_PROTOCOL_DNS);
1416
1417         /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check
1418          * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links
1419          * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to
1420          * take queries to arbitrary domains, i.e. has no routing domains set. */
1421
1422         if (scope->link)
1423                 first = scope->link->search_domains;
1424         else
1425                 first = scope->manager->search_domains;
1426
1427         LIST_FOREACH(domains, domain, first) {
1428                 /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early
1429                  * here, as it doesn't really matter whether this link has any route-only domains or not,
1430                  * "~."  really trumps everything and clearly indicates that this interface shall receive all
1431                  * traffic it can get. */
1432                 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain)))
1433                         return false;
1434
1435                 if (domain->route_only)
1436                         route_only = true;
1437         }
1438
1439         return route_only;
1440 }
1441
1442 bool dns_scope_is_default_route(DnsScope *scope) {
1443         assert(scope);
1444
1445         /* Only use DNS scopes as default routes */
1446         if (scope->protocol != DNS_PROTOCOL_DNS)
1447                 return false;
1448
1449         /* The global DNS scope is always suitable as default route */
1450         if (!scope->link)
1451                 return true;
1452
1453         /* Honour whatever is explicitly configured. This is really the best approach, and trumps any
1454          * automatic logic. */
1455         if (scope->link->default_route >= 0)
1456                 return scope->link->default_route;
1457
1458         /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not
1459          * volunteer as default route. */
1460         return !dns_scope_has_route_only_domains(scope);
1461 }