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) {
 451         return dns_scope_socket(s, SOCK_DGRAM, AF_UNSPEC, NULL, server, dns_server_port(server), 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                                                         * particularly 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 fine. (Specifically, we want to
 655                  * permit looking up DNSKEY and DS records on the root and top-level domains.) */
 656                 if (!dns_resource_key_is_address(key))
 657                         return true;
 658
 659                 /* Unless explicitly overridden, we refuse to look up A and AAAA RRs on the root and
 660                  * single-label domains, under the assumption that those should be resolved via LLMNR or
 661                  * search path only, and should not be leaked onto the internet. */
 662                 const char* name = dns_resource_key_name(key);
 663
 664                 if (!s->manager->resolve_unicast_single_label &&
 665                     dns_name_is_single_label(name))
 666                         return false;
 667
 668                 return !dns_name_is_root(name);
 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 look up 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_relative(
1063                         scope->manager->event,
1064                         &scope->conflict_event_source,
1065                         clock_boottime_or_monotonic(),
1066                         jitter,
1067                         LLMNR_JITTER_INTERVAL_USEC,
1068                         on_conflict_dispatch, scope);
1069         if (r < 0)
1070                 return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
1071
1072         (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
1073
1074         return 0;
1075 }
1076
1077 void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
1078         DnsResourceRecord *rr;
1079         int r;
1080
1081         assert(scope);
1082         assert(p);
1083
1084         if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS))
1085                 return;
1086
1087         if (DNS_PACKET_RRCOUNT(p) <= 0)
1088                 return;
1089
1090         if (p->protocol == DNS_PROTOCOL_LLMNR) {
1091                 if (DNS_PACKET_LLMNR_C(p) != 0)
1092                         return;
1093
1094                 if (DNS_PACKET_LLMNR_T(p) != 0)
1095                         return;
1096         }
1097
1098         if (manager_our_packet(scope->manager, p))
1099                 return;
1100
1101         r = dns_packet_extract(p);
1102         if (r < 0) {
1103                 log_debug_errno(r, "Failed to extract packet: %m");
1104                 return;
1105         }
1106
1107         log_debug("Checking for conflicts...");
1108
1109         DNS_ANSWER_FOREACH(rr, p->answer) {
1110                 /* No conflict if it is DNS-SD RR used for service enumeration. */
1111                 if (dns_resource_key_is_dnssd_ptr(rr->key))
1112                         continue;
1113
1114                 /* Check for conflicts against the local zone. If we
1115                  * found one, we won't check any further */
1116                 r = dns_zone_check_conflicts(&scope->zone, rr);
1117                 if (r != 0)
1118                         continue;
1119
1120                 /* Check for conflicts against the local cache. If so,
1121                  * send out an advisory query, to inform everybody */
1122                 r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender);
1123                 if (r <= 0)
1124                         continue;
1125
1126                 dns_scope_notify_conflict(scope, rr);
1127         }
1128 }
1129
1130 void dns_scope_dump(DnsScope *s, FILE *f) {
1131         assert(s);
1132
1133         if (!f)
1134                 f = stdout;
1135
1136         fputs("[Scope protocol=", f);
1137         fputs(dns_protocol_to_string(s->protocol), f);
1138
1139         if (s->link) {
1140                 fputs(" interface=", f);
1141                 fputs(s->link->ifname, f);
1142         }
1143
1144         if (s->family != AF_UNSPEC) {
1145                 fputs(" family=", f);
1146                 fputs(af_to_name(s->family), f);
1147         }
1148
1149         fputs("]\n", f);
1150
1151         if (!dns_zone_is_empty(&s->zone)) {
1152                 fputs("ZONE:\n", f);
1153                 dns_zone_dump(&s->zone, f);
1154         }
1155
1156         if (!dns_cache_is_empty(&s->cache)) {
1157                 fputs("CACHE:\n", f);
1158                 dns_cache_dump(&s->cache, f);
1159         }
1160 }
1161
1162 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
1163         assert(s);
1164
1165         if (s->protocol != DNS_PROTOCOL_DNS)
1166                 return NULL;
1167
1168         if (s->link)
1169                 return s->link->search_domains;
1170
1171         return s->manager->search_domains;
1172 }
1173
1174 bool dns_scope_name_wants_search_domain(DnsScope *s, const char *name) {
1175         assert(s);
1176
1177         if (s->protocol != DNS_PROTOCOL_DNS)
1178                 return false;
1179
1180         return dns_name_is_single_label(name);
1181 }
1182
1183 bool dns_scope_network_good(DnsScope *s) {
1184         /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1185          * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1186          * DNS scope we check whether there are any links that are up and have an address. */
1187
1188         if (s->link)
1189                 return true;
1190
1191         return manager_routable(s->manager, AF_UNSPEC);
1192 }
1193
1194 int dns_scope_ifindex(DnsScope *s) {
1195         assert(s);
1196
1197         if (s->link)
1198                 return s->link->ifindex;
1199
1200         return 0;
1201 }
1202
1203 static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1204         DnsScope *scope = userdata;
1205
1206         assert(s);
1207
1208         scope->announce_event_source = sd_event_source_unref(scope->announce_event_source);
1209
1210         (void) dns_scope_announce(scope, false);
1211         return 0;
1212 }
1213
1214 int dns_scope_announce(DnsScope *scope, bool goodbye) {
1215         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1216         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1217         _cleanup_set_free_ Set *types = NULL;
1218         DnsTransaction *t;
1219         DnsZoneItem *z, *i;
1220         unsigned size = 0;
1221         Iterator iterator;
1222         char *service_type;
1223         int r;
1224
1225         if (!scope)
1226                 return 0;
1227
1228         if (scope->protocol != DNS_PROTOCOL_MDNS)
1229                 return 0;
1230
1231         /* Check if we're done with probing. */
1232         LIST_FOREACH(transactions_by_scope, t, scope->transactions)
1233                 if (DNS_TRANSACTION_IS_LIVE(t->state))
1234                         return 0;
1235
1236         /* Check if there're services pending conflict resolution. */
1237         if (manager_next_dnssd_names(scope->manager))
1238                 return 0; /* we reach this point only if changing hostname didn't help */
1239
1240         /* Calculate answer's size. */
1241         HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
1242                 if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
1243                         continue;
1244
1245                 if (z->rr->key->type == DNS_TYPE_PTR &&
1246                     !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
1247                         char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1248
1249                         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));
1250                         z->state = DNS_ZONE_ITEM_WITHDRAWN;
1251                         continue;
1252                 }
1253
1254                 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1255                 if (!scope->announced &&
1256                     dns_resource_key_is_dnssd_ptr(z->rr->key)) {
1257                         if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
1258                                 r = set_ensure_put(&types, &dns_name_hash_ops, dns_resource_key_name(z->rr->key));
1259                                 if (r < 0)
1260                                         return log_debug_errno(r, "Failed to add item to set: %m");
1261                         }
1262                 }
1263
1264                 LIST_FOREACH(by_key, i, z)
1265                         size++;
1266         }
1267
1268         answer = dns_answer_new(size + set_size(types));
1269         if (!answer)
1270                 return log_oom();
1271
1272         /* Second iteration, actually add RRs to the answer. */
1273         HASHMAP_FOREACH(z, scope->zone.by_key, iterator)
1274                 LIST_FOREACH (by_key, i, z) {
1275                         DnsAnswerFlags flags;
1276
1277                         if (i->state != DNS_ZONE_ITEM_ESTABLISHED)
1278                                 continue;
1279
1280                         if (dns_resource_key_is_dnssd_ptr(i->rr->key))
1281                                 flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
1282                         else
1283                                 flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
1284
1285                         r = dns_answer_add(answer, i->rr, 0 , flags);
1286                         if (r < 0)
1287                                 return log_debug_errno(r, "Failed to add RR to announce: %m");
1288                 }
1289
1290         /* Since all the active services are in the zone make them discoverable now. */
1291         SET_FOREACH(service_type, types, iterator) {
1292                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr;
1293
1294                 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
1295                                                   "_services._dns-sd._udp.local");
1296                 rr->ptr.name = strdup(service_type);
1297                 rr->ttl = MDNS_DEFAULT_TTL;
1298
1299                 r = dns_zone_put(&scope->zone, scope, rr, false);
1300                 if (r < 0)
1301                         log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m");
1302
1303                 r = dns_answer_add(answer, rr, 0 , 0);
1304                 if (r < 0)
1305                         return log_debug_errno(r, "Failed to add RR to announce: %m");
1306         }
1307
1308         if (dns_answer_isempty(answer))
1309                 return 0;
1310
1311         r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p);
1312         if (r < 0)
1313                 return log_debug_errno(r, "Failed to build reply packet: %m");
1314
1315         r = dns_scope_emit_udp(scope, -1, p);
1316         if (r < 0)
1317                 return log_debug_errno(r, "Failed to send reply packet: %m");
1318
1319         /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1320          * responses, one second apart." */
1321         if (!scope->announced) {
1322                 scope->announced = true;
1323
1324                 r = sd_event_add_time_relative(
1325                                 scope->manager->event,
1326                                 &scope->announce_event_source,
1327                                 clock_boottime_or_monotonic(),
1328                                 MDNS_ANNOUNCE_DELAY,
1329                                 MDNS_JITTER_RANGE_USEC,
1330                                 on_announcement_timeout, scope);
1331                 if (r < 0)
1332                         return log_debug_errno(r, "Failed to schedule second announcement: %m");
1333
1334                 (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce");
1335         }
1336
1337         return 0;
1338 }
1339
1340 int dns_scope_add_dnssd_services(DnsScope *scope) {
1341         Iterator i;
1342         DnssdService *service;
1343         DnssdTxtData *txt_data;
1344         int r;
1345
1346         assert(scope);
1347
1348         if (hashmap_size(scope->manager->dnssd_services) == 0)
1349                 return 0;
1350
1351         scope->announced = false;
1352
1353         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1354                 service->withdrawn = false;
1355
1356                 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
1357                 if (r < 0)
1358                         log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");
1359
1360                 r = dns_zone_put(&scope->zone, scope, service->srv_rr, true);
1361                 if (r < 0)
1362                         log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m");
1363
1364                 LIST_FOREACH(items, txt_data, service->txt_data_items) {
1365                         r = dns_zone_put(&scope->zone, scope, txt_data->rr, true);
1366                         if (r < 0)
1367                                 log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m");
1368                 }
1369         }
1370
1371         return 0;
1372 }
1373
1374 int dns_scope_remove_dnssd_services(DnsScope *scope) {
1375         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1376         Iterator i;
1377         DnssdService *service;
1378         DnssdTxtData *txt_data;
1379         int r;
1380
1381         assert(scope);
1382
1383         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR,
1384                                    "_services._dns-sd._udp.local");
1385         if (!key)
1386                 return log_oom();
1387
1388         r = dns_zone_remove_rrs_by_key(&scope->zone, key);
1389         if (r < 0)
1390                 return r;
1391
1392         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1393                 dns_zone_remove_rr(&scope->zone, service->ptr_rr);
1394                 dns_zone_remove_rr(&scope->zone, service->srv_rr);
1395                 LIST_FOREACH(items, txt_data, service->txt_data_items)
1396                         dns_zone_remove_rr(&scope->zone, txt_data->rr);
1397         }
1398
1399         return 0;
1400 }
1401
1402 static bool dns_scope_has_route_only_domains(DnsScope *scope) {
1403         DnsSearchDomain *domain, *first;
1404         bool route_only = false;
1405
1406         assert(scope);
1407         assert(scope->protocol == DNS_PROTOCOL_DNS);
1408
1409         /* Returns 'true' if this scope is suitable for queries to specific domains only. For that we check
1410          * if there are any route-only domains on this interface, as a heuristic to discern VPN-style links
1411          * from non-VPN-style links. Returns 'false' for all other cases, i.e. if the scope is intended to
1412          * take queries to arbitrary domains, i.e. has no routing domains set. */
1413
1414         if (scope->link)
1415                 first = scope->link->search_domains;
1416         else
1417                 first = scope->manager->search_domains;
1418
1419         LIST_FOREACH(domains, domain, first) {
1420                 /* "." means "any domain", thus the interface takes any kind of traffic. Thus, we exit early
1421                  * here, as it doesn't really matter whether this link has any route-only domains or not,
1422                  * "~."  really trumps everything and clearly indicates that this interface shall receive all
1423                  * traffic it can get. */
1424                 if (dns_name_is_root(DNS_SEARCH_DOMAIN_NAME(domain)))
1425                         return false;
1426
1427                 if (domain->route_only)
1428                         route_only = true;
1429         }
1430
1431         return route_only;
1432 }
1433
1434 bool dns_scope_is_default_route(DnsScope *scope) {
1435         assert(scope);
1436
1437         /* Only use DNS scopes as default routes */
1438         if (scope->protocol != DNS_PROTOCOL_DNS)
1439                 return false;
1440
1441         /* The global DNS scope is always suitable as default route */
1442         if (!scope->link)
1443                 return true;
1444
1445         /* Honour whatever is explicitly configured. This is really the best approach, and trumps any
1446          * automatic logic. */
1447         if (scope->link->default_route >= 0)
1448                 return scope->link->default_route;
1449
1450         /* Otherwise check if we have any route-only domains, as a sensible heuristic: if so, let's not
1451          * volunteer as default route. */
1452         return !dns_scope_has_route_only_domains(scope);
1453 }