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->name : "*", 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->name : "*", 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 DnsScopeMatch dns_scope_good_domain(
 463                 DnsScope *s,
 464                 int ifindex,
 465                 uint64_t flags,
 466                 const char *domain) {
 467
 468         DnsSearchDomain *d;
 469
 470         /* This returns the following return values:
 471          *
 472          *    DNS_SCOPE_NO         → This scope is not suitable for lookups of this domain, at all
 473          *    DNS_SCOPE_MAYBE      → This scope is suitable, but only if nothing else wants it
 474          *    DNS_SCOPE_YES_BASE+n → This scope is suitable, and 'n' suffix labels match
 475          *
 476          *  (The idea is that the caller will only use the scopes with the longest 'n' returned. If no scopes return
 477          *  DNS_SCOPE_YES_BASE+n, then it should use those which returned DNS_SCOPE_MAYBE. It should never use those
 478          *  which returned DNS_SCOPE_NO.)
 479          */
 480
 481         assert(s);
 482         assert(domain);
 483
 484         /* Checks if the specified domain is something to look up on
 485          * this scope. Note that this accepts non-qualified hostnames,
 486          * i.e. those without any search path prefixed yet. */
 487
 488         if (ifindex != 0 && (!s->link || s->link->ifindex != ifindex))
 489                 return DNS_SCOPE_NO;
 490
 491         if ((SD_RESOLVED_FLAGS_MAKE(s->protocol, s->family, 0) & flags) == 0)
 492                 return DNS_SCOPE_NO;
 493
 494         /* Never resolve any loopback hostname or IP address via DNS,
 495          * LLMNR or mDNS. Instead, always rely on synthesized RRs for
 496          * these. */
 497         if (is_localhost(domain) ||
 498             dns_name_endswith(domain, "127.in-addr.arpa") > 0 ||
 499             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)
 500                 return DNS_SCOPE_NO;
 501
 502         /* Never respond to some of the domains listed in RFC6303 */
 503         if (dns_name_endswith(domain, "0.in-addr.arpa") > 0 ||
 504             dns_name_equal(domain, "255.255.255.255.in-addr.arpa") > 0 ||
 505             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)
 506                 return DNS_SCOPE_NO;
 507
 508         /* Never respond to some of the domains listed in RFC6761 */
 509         if (dns_name_endswith(domain, "invalid") > 0)
 510                 return DNS_SCOPE_NO;
 511
 512         switch (s->protocol) {
 513
 514         case DNS_PROTOCOL_DNS: {
 515                 DnsServer *dns_server;
 516                 int n_best = -1;
 517
 518                 /* Never route things to scopes that lack DNS servers */
 519                 dns_server = dns_scope_get_dns_server(s);
 520                 if (!dns_server)
 521                         return DNS_SCOPE_NO;
 522
 523                 /* Always honour search domains for routing queries, except if this scope lacks DNS servers. Note that
 524                  * we return DNS_SCOPE_YES here, rather than just DNS_SCOPE_MAYBE, which means other wildcard scopes
 525                  * won't be considered anymore. */
 526                 LIST_FOREACH(domains, d, dns_scope_get_search_domains(s))
 527                         if (dns_name_endswith(domain, d->name) > 0) {
 528                                 int c;
 529
 530                                 c = dns_name_count_labels(d->name);
 531                                 if (c < 0)
 532                                         continue;
 533
 534                                 if (c > n_best)
 535                                         n_best = c;
 536                         }
 537
 538                 /* Let's return the number of labels in the best matching result */
 539                 if (n_best >= 0) {
 540                         assert(n_best <= DNS_SCOPE_YES_END - DNS_SCOPE_YES_BASE);
 541                         return DNS_SCOPE_YES_BASE + n_best;
 542                 }
 543
 544                 /* If the DNS server has route-only domains, don't send other requests to it. This would be a privacy
 545                  * violation, will most probably fail anyway, and adds unnecessary load. */
 546                 if (dns_server_limited_domains(dns_server))
 547                         return DNS_SCOPE_NO;
 548
 549                 /* Exclude link-local IP ranges */
 550                 if (dns_name_endswith(domain, "254.169.in-addr.arpa") == 0 &&
 551                     dns_name_endswith(domain, "8.e.f.ip6.arpa") == 0 &&
 552                     dns_name_endswith(domain, "9.e.f.ip6.arpa") == 0 &&
 553                     dns_name_endswith(domain, "a.e.f.ip6.arpa") == 0 &&
 554                     dns_name_endswith(domain, "b.e.f.ip6.arpa") == 0 &&
 555                     /* If networks use .local in their private setups, they are supposed to also add .local to their search
 556                      * domains, which we already checked above. Otherwise, we consider .local specific to mDNS and won't
 557                      * send such queries ordinary DNS servers. */
 558                     dns_name_endswith(domain, "local") == 0)
 559                         return DNS_SCOPE_MAYBE;
 560
 561                 return DNS_SCOPE_NO;
 562         }
 563
 564         case DNS_PROTOCOL_MDNS:
 565                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 566                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0) ||
 567                     (dns_name_endswith(domain, "local") > 0 && /* only resolve names ending in .local via mDNS */
 568                      dns_name_equal(domain, "local") == 0 &&   /* but not the single-label "local" name itself */
 569                      manager_is_own_hostname(s->manager, domain) <= 0)) /* never resolve the local hostname via mDNS */
 570                         return DNS_SCOPE_MAYBE;
 571
 572                 return DNS_SCOPE_NO;
 573
 574         case DNS_PROTOCOL_LLMNR:
 575                 if ((s->family == AF_INET && dns_name_endswith(domain, "in-addr.arpa") > 0) ||
 576                     (s->family == AF_INET6 && dns_name_endswith(domain, "ip6.arpa") > 0) ||
 577                     (dns_name_is_single_label(domain) && /* only resolve single label names via LLMNR */
 578                      !is_gateway_hostname(domain) && /* don't resolve "gateway" with LLMNR, let nss-myhostname handle this */
 579                      manager_is_own_hostname(s->manager, domain) <= 0))  /* never resolve the local hostname via LLMNR */
 580                         return DNS_SCOPE_MAYBE;
 581
 582                 return DNS_SCOPE_NO;
 583
 584         default:
 585                 assert_not_reached("Unknown scope protocol");
 586         }
 587 }
 588
 589 bool dns_scope_good_key(DnsScope *s, const DnsResourceKey *key) {
 590         int key_family;
 591
 592         assert(s);
 593         assert(key);
 594
 595         /* Check if it makes sense to resolve the specified key on
 596          * this scope. Note that this call assumes as fully qualified
 597          * name, i.e. the search suffixes already appended. */
 598
 599         if (key->class != DNS_CLASS_IN)
 600                 return false;
 601
 602         if (s->protocol == DNS_PROTOCOL_DNS) {
 603
 604                 /* On classic DNS, looking up non-address RRs is always
 605                  * fine. (Specifically, we want to permit looking up
 606                  * DNSKEY and DS records on the root and top-level
 607                  * domains.) */
 608                 if (!dns_resource_key_is_address(key))
 609                         return true;
 610
 611                 /* However, we refuse to look up A and AAAA RRs on the
 612                  * root and single-label domains, under the assumption
 613                  * that those should be resolved via LLMNR or search
 614                  * path only, and should not be leaked onto the
 615                  * internet. */
 616                 return !(dns_name_is_single_label(dns_resource_key_name(key)) ||
 617                          dns_name_is_root(dns_resource_key_name(key)));
 618         }
 619
 620         /* On mDNS and LLMNR, send A and AAAA queries only on the
 621          * respective scopes */
 622
 623         key_family = dns_type_to_af(key->type);
 624         if (key_family < 0)
 625                 return true;
 626
 627         return key_family == s->family;
 628 }
 629
 630 static int dns_scope_multicast_membership(DnsScope *s, bool b, struct in_addr in, struct in6_addr in6) {
 631         int fd;
 632
 633         assert(s);
 634         assert(s->link);
 635
 636         if (s->family == AF_INET) {
 637                 struct ip_mreqn mreqn = {
 638                         .imr_multiaddr = in,
 639                         .imr_ifindex = s->link->ifindex,
 640                 };
 641
 642                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 643                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 644                 else
 645                         fd = manager_mdns_ipv4_fd(s->manager);
 646
 647                 if (fd < 0)
 648                         return fd;
 649
 650                 /* Always first try to drop membership before we add
 651                  * one. This is necessary on some devices, such as
 652                  * veth. */
 653                 if (b)
 654                         (void) setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn));
 655
 656                 if (setsockopt(fd, IPPROTO_IP, b ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreqn, sizeof(mreqn)) < 0)
 657                         return -errno;
 658
 659         } else if (s->family == AF_INET6) {
 660                 struct ipv6_mreq mreq = {
 661                         .ipv6mr_multiaddr = in6,
 662                         .ipv6mr_interface = s->link->ifindex,
 663                 };
 664
 665                 if (s->protocol == DNS_PROTOCOL_LLMNR)
 666                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 667                 else
 668                         fd = manager_mdns_ipv6_fd(s->manager);
 669
 670                 if (fd < 0)
 671                         return fd;
 672
 673                 if (b)
 674                         (void) setsockopt(fd, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
 675
 676                 if (setsockopt(fd, IPPROTO_IPV6, b ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0)
 677                         return -errno;
 678         } else
 679                 return -EAFNOSUPPORT;
 680
 681         return 0;
 682 }
 683
 684 int dns_scope_llmnr_membership(DnsScope *s, bool b) {
 685         assert(s);
 686
 687         if (s->protocol != DNS_PROTOCOL_LLMNR)
 688                 return 0;
 689
 690         return dns_scope_multicast_membership(s, b, LLMNR_MULTICAST_IPV4_ADDRESS, LLMNR_MULTICAST_IPV6_ADDRESS);
 691 }
 692
 693 int dns_scope_mdns_membership(DnsScope *s, bool b) {
 694         assert(s);
 695
 696         if (s->protocol != DNS_PROTOCOL_MDNS)
 697                 return 0;
 698
 699         return dns_scope_multicast_membership(s, b, MDNS_MULTICAST_IPV4_ADDRESS, MDNS_MULTICAST_IPV6_ADDRESS);
 700 }
 701
 702 int dns_scope_make_reply_packet(
 703                 DnsScope *s,
 704                 uint16_t id,
 705                 int rcode,
 706                 DnsQuestion *q,
 707                 DnsAnswer *answer,
 708                 DnsAnswer *soa,
 709                 bool tentative,
 710                 DnsPacket **ret) {
 711
 712         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 713         int r;
 714
 715         assert(s);
 716         assert(ret);
 717
 718         if (dns_question_isempty(q) &&
 719             dns_answer_isempty(answer) &&
 720             dns_answer_isempty(soa))
 721                 return -EINVAL;
 722
 723         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 724         if (r < 0)
 725                 return r;
 726
 727         DNS_PACKET_HEADER(p)->id = id;
 728         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 729                                                               1 /* qr */,
 730                                                               0 /* opcode */,
 731                                                               0 /* c */,
 732                                                               0 /* tc */,
 733                                                               tentative,
 734                                                               0 /* (ra) */,
 735                                                               0 /* (ad) */,
 736                                                               0 /* (cd) */,
 737                                                               rcode));
 738
 739         r = dns_packet_append_question(p, q);
 740         if (r < 0)
 741                 return r;
 742         DNS_PACKET_HEADER(p)->qdcount = htobe16(dns_question_size(q));
 743
 744         r = dns_packet_append_answer(p, answer);
 745         if (r < 0)
 746                 return r;
 747         DNS_PACKET_HEADER(p)->ancount = htobe16(dns_answer_size(answer));
 748
 749         r = dns_packet_append_answer(p, soa);
 750         if (r < 0)
 751                 return r;
 752         DNS_PACKET_HEADER(p)->arcount = htobe16(dns_answer_size(soa));
 753
 754         *ret = TAKE_PTR(p);
 755
 756         return 0;
 757 }
 758
 759 static void dns_scope_verify_conflicts(DnsScope *s, DnsPacket *p) {
 760         DnsResourceRecord *rr;
 761         DnsResourceKey *key;
 762
 763         assert(s);
 764         assert(p);
 765
 766         DNS_QUESTION_FOREACH(key, p->question)
 767                 dns_zone_verify_conflicts(&s->zone, key);
 768
 769         DNS_ANSWER_FOREACH(rr, p->answer)
 770                 dns_zone_verify_conflicts(&s->zone, rr->key);
 771 }
 772
 773 void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
 774         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL, *soa = NULL;
 775         _cleanup_(dns_packet_unrefp) DnsPacket *reply = NULL;
 776         DnsResourceKey *key = NULL;
 777         bool tentative = false;
 778         int r;
 779
 780         assert(s);
 781         assert(p);
 782
 783         if (p->protocol != DNS_PROTOCOL_LLMNR)
 784                 return;
 785
 786         if (p->ipproto == IPPROTO_UDP) {
 787                 /* Don't accept UDP queries directed to anything but
 788                  * the LLMNR multicast addresses. See RFC 4795,
 789                  * section 2.5. */
 790
 791                 if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
 792                         return;
 793
 794                 if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS))
 795                         return;
 796         }
 797
 798         r = dns_packet_extract(p);
 799         if (r < 0) {
 800                 log_debug_errno(r, "Failed to extract resource records from incoming packet: %m");
 801                 return;
 802         }
 803
 804         if (DNS_PACKET_LLMNR_C(p)) {
 805                 /* Somebody notified us about a possible conflict */
 806                 dns_scope_verify_conflicts(s, p);
 807                 return;
 808         }
 809
 810         assert(dns_question_size(p->question) == 1);
 811         key = p->question->keys[0];
 812
 813         r = dns_zone_lookup(&s->zone, key, 0, &answer, &soa, &tentative);
 814         if (r < 0) {
 815                 log_debug_errno(r, "Failed to lookup key: %m");
 816                 return;
 817         }
 818         if (r == 0)
 819                 return;
 820
 821         if (answer)
 822                 dns_answer_order_by_scope(answer, in_addr_is_link_local(p->family, &p->sender) > 0);
 823
 824         r = dns_scope_make_reply_packet(s, DNS_PACKET_ID(p), DNS_RCODE_SUCCESS, p->question, answer, soa, tentative, &reply);
 825         if (r < 0) {
 826                 log_debug_errno(r, "Failed to build reply packet: %m");
 827                 return;
 828         }
 829
 830         if (stream) {
 831                 r = dns_stream_write_packet(stream, reply);
 832                 if (r < 0) {
 833                         log_debug_errno(r, "Failed to enqueue reply packet: %m");
 834                         return;
 835                 }
 836
 837                 /* Let's take an extra reference on this stream, so that it stays around after returning. The reference
 838                  * will be dangling until the stream is disconnected, and the default completion handler of the stream
 839                  * will then unref the stream and destroy it */
 840                 if (DNS_STREAM_QUEUED(stream))
 841                         dns_stream_ref(stream);
 842         } else {
 843                 int fd;
 844
 845                 if (!ratelimit_below(&s->ratelimit))
 846                         return;
 847
 848                 if (p->family == AF_INET)
 849                         fd = manager_llmnr_ipv4_udp_fd(s->manager);
 850                 else if (p->family == AF_INET6)
 851                         fd = manager_llmnr_ipv6_udp_fd(s->manager);
 852                 else {
 853                         log_debug("Unknown protocol");
 854                         return;
 855                 }
 856                 if (fd < 0) {
 857                         log_debug_errno(fd, "Failed to get reply socket: %m");
 858                         return;
 859                 }
 860
 861                 /* Note that we always immediately reply to all LLMNR
 862                  * requests, and do not wait any time, since we
 863                  * verified uniqueness for all records. Also see RFC
 864                  * 4795, Section 2.7 */
 865
 866                 r = manager_send(s->manager, fd, p->ifindex, p->family, &p->sender, p->sender_port, NULL, reply);
 867                 if (r < 0) {
 868                         log_debug_errno(r, "Failed to send reply packet: %m");
 869                         return;
 870                 }
 871         }
 872 }
 873
 874 DnsTransaction *dns_scope_find_transaction(DnsScope *scope, DnsResourceKey *key, bool cache_ok) {
 875         DnsTransaction *t;
 876
 877         assert(scope);
 878         assert(key);
 879
 880         /* Try to find an ongoing transaction that is a equal to the
 881          * specified question */
 882         t = hashmap_get(scope->transactions_by_key, key);
 883         if (!t)
 884                 return NULL;
 885
 886         /* Refuse reusing transactions that completed based on cached
 887          * data instead of a real packet, if that's requested. */
 888         if (!cache_ok &&
 889             IN_SET(t->state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_RCODE_FAILURE) &&
 890             t->answer_source != DNS_TRANSACTION_NETWORK)
 891                 return NULL;
 892
 893         return t;
 894 }
 895
 896 static int dns_scope_make_conflict_packet(
 897                 DnsScope *s,
 898                 DnsResourceRecord *rr,
 899                 DnsPacket **ret) {
 900
 901         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 902         int r;
 903
 904         assert(s);
 905         assert(rr);
 906         assert(ret);
 907
 908         r = dns_packet_new(&p, s->protocol, 0, DNS_PACKET_SIZE_MAX);
 909         if (r < 0)
 910                 return r;
 911
 912         DNS_PACKET_HEADER(p)->flags = htobe16(DNS_PACKET_MAKE_FLAGS(
 913                                                               0 /* qr */,
 914                                                               0 /* opcode */,
 915                                                               1 /* conflict */,
 916                                                               0 /* tc */,
 917                                                               0 /* t */,
 918                                                               0 /* (ra) */,
 919                                                               0 /* (ad) */,
 920                                                               0 /* (cd) */,
 921                                                               0));
 922
 923         /* For mDNS, the transaction ID should always be 0 */
 924         if (s->protocol != DNS_PROTOCOL_MDNS)
 925                 random_bytes(&DNS_PACKET_HEADER(p)->id, sizeof(uint16_t));
 926
 927         DNS_PACKET_HEADER(p)->qdcount = htobe16(1);
 928         DNS_PACKET_HEADER(p)->arcount = htobe16(1);
 929
 930         r = dns_packet_append_key(p, rr->key, 0, NULL);
 931         if (r < 0)
 932                 return r;
 933
 934         r = dns_packet_append_rr(p, rr, 0, NULL, NULL);
 935         if (r < 0)
 936                 return r;
 937
 938         *ret = TAKE_PTR(p);
 939
 940         return 0;
 941 }
 942
 943 static int on_conflict_dispatch(sd_event_source *es, usec_t usec, void *userdata) {
 944         DnsScope *scope = userdata;
 945         int r;
 946
 947         assert(es);
 948         assert(scope);
 949
 950         scope->conflict_event_source = sd_event_source_unref(scope->conflict_event_source);
 951
 952         for (;;) {
 953                 _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
 954                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
 955                 _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
 956
 957                 key = ordered_hashmap_first_key(scope->conflict_queue);
 958                 if (!key)
 959                         break;
 960
 961                 rr = ordered_hashmap_remove(scope->conflict_queue, key);
 962                 assert(rr);
 963
 964                 r = dns_scope_make_conflict_packet(scope, rr, &p);
 965                 if (r < 0) {
 966                         log_error_errno(r, "Failed to make conflict packet: %m");
 967                         return 0;
 968                 }
 969
 970                 r = dns_scope_emit_udp(scope, -1, p);
 971                 if (r < 0)
 972                         log_debug_errno(r, "Failed to send conflict packet: %m");
 973         }
 974
 975         return 0;
 976 }
 977
 978 int dns_scope_notify_conflict(DnsScope *scope, DnsResourceRecord *rr) {
 979         usec_t jitter;
 980         int r;
 981
 982         assert(scope);
 983         assert(rr);
 984
 985         /* We don't send these queries immediately. Instead, we queue
 986          * them, and send them after some jitter delay. */
 987         r = ordered_hashmap_ensure_allocated(&scope->conflict_queue, &dns_resource_key_hash_ops);
 988         if (r < 0) {
 989                 log_oom();
 990                 return r;
 991         }
 992
 993         /* We only place one RR per key in the conflict
 994          * messages, not all of them. That should be enough to
 995          * indicate where there might be a conflict */
 996         r = ordered_hashmap_put(scope->conflict_queue, rr->key, rr);
 997         if (IN_SET(r, 0, -EEXIST))
 998                 return 0;
 999         if (r < 0)
1000                 return log_debug_errno(r, "Failed to queue conflicting RR: %m");
1001
1002         dns_resource_key_ref(rr->key);
1003         dns_resource_record_ref(rr);
1004
1005         if (scope->conflict_event_source)
1006                 return 0;
1007
1008         random_bytes(&jitter, sizeof(jitter));
1009         jitter %= LLMNR_JITTER_INTERVAL_USEC;
1010
1011         r = sd_event_add_time(scope->manager->event,
1012                               &scope->conflict_event_source,
1013                               clock_boottime_or_monotonic(),
1014                               now(clock_boottime_or_monotonic()) + jitter,
1015                               LLMNR_JITTER_INTERVAL_USEC,
1016                               on_conflict_dispatch, scope);
1017         if (r < 0)
1018                 return log_debug_errno(r, "Failed to add conflict dispatch event: %m");
1019
1020         (void) sd_event_source_set_description(scope->conflict_event_source, "scope-conflict");
1021
1022         return 0;
1023 }
1024
1025 void dns_scope_check_conflicts(DnsScope *scope, DnsPacket *p) {
1026         DnsResourceRecord *rr;
1027         int r;
1028
1029         assert(scope);
1030         assert(p);
1031
1032         if (!IN_SET(p->protocol, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS))
1033                 return;
1034
1035         if (DNS_PACKET_RRCOUNT(p) <= 0)
1036                 return;
1037
1038         if (p->protocol == DNS_PROTOCOL_LLMNR) {
1039                 if (DNS_PACKET_LLMNR_C(p) != 0)
1040                         return;
1041
1042                 if (DNS_PACKET_LLMNR_T(p) != 0)
1043                         return;
1044         }
1045
1046         if (manager_our_packet(scope->manager, p))
1047                 return;
1048
1049         r = dns_packet_extract(p);
1050         if (r < 0) {
1051                 log_debug_errno(r, "Failed to extract packet: %m");
1052                 return;
1053         }
1054
1055         log_debug("Checking for conflicts...");
1056
1057         DNS_ANSWER_FOREACH(rr, p->answer) {
1058                 /* No conflict if it is DNS-SD RR used for service enumeration. */
1059                 if (dns_resource_key_is_dnssd_ptr(rr->key))
1060                         continue;
1061
1062                 /* Check for conflicts against the local zone. If we
1063                  * found one, we won't check any further */
1064                 r = dns_zone_check_conflicts(&scope->zone, rr);
1065                 if (r != 0)
1066                         continue;
1067
1068                 /* Check for conflicts against the local cache. If so,
1069                  * send out an advisory query, to inform everybody */
1070                 r = dns_cache_check_conflicts(&scope->cache, rr, p->family, &p->sender);
1071                 if (r <= 0)
1072                         continue;
1073
1074                 dns_scope_notify_conflict(scope, rr);
1075         }
1076 }
1077
1078 void dns_scope_dump(DnsScope *s, FILE *f) {
1079         assert(s);
1080
1081         if (!f)
1082                 f = stdout;
1083
1084         fputs("[Scope protocol=", f);
1085         fputs(dns_protocol_to_string(s->protocol), f);
1086
1087         if (s->link) {
1088                 fputs(" interface=", f);
1089                 fputs(s->link->name, f);
1090         }
1091
1092         if (s->family != AF_UNSPEC) {
1093                 fputs(" family=", f);
1094                 fputs(af_to_name(s->family), f);
1095         }
1096
1097         fputs("]\n", f);
1098
1099         if (!dns_zone_is_empty(&s->zone)) {
1100                 fputs("ZONE:\n", f);
1101                 dns_zone_dump(&s->zone, f);
1102         }
1103
1104         if (!dns_cache_is_empty(&s->cache)) {
1105                 fputs("CACHE:\n", f);
1106                 dns_cache_dump(&s->cache, f);
1107         }
1108 }
1109
1110 DnsSearchDomain *dns_scope_get_search_domains(DnsScope *s) {
1111         assert(s);
1112
1113         if (s->protocol != DNS_PROTOCOL_DNS)
1114                 return NULL;
1115
1116         if (s->link)
1117                 return s->link->search_domains;
1118
1119         return s->manager->search_domains;
1120 }
1121
1122 bool dns_scope_name_needs_search_domain(DnsScope *s, const char *name) {
1123         assert(s);
1124
1125         if (s->protocol != DNS_PROTOCOL_DNS)
1126                 return false;
1127
1128         return dns_name_is_single_label(name);
1129 }
1130
1131 bool dns_scope_network_good(DnsScope *s) {
1132         /* Checks whether the network is in good state for lookups on this scope. For mDNS/LLMNR/Classic DNS scopes
1133          * bound to links this is easy, as they don't even exist if the link isn't in a suitable state. For the global
1134          * DNS scope we check whether there are any links that are up and have an address. */
1135
1136         if (s->link)
1137                 return true;
1138
1139         return manager_routable(s->manager, AF_UNSPEC);
1140 }
1141
1142 int dns_scope_ifindex(DnsScope *s) {
1143         assert(s);
1144
1145         if (s->link)
1146                 return s->link->ifindex;
1147
1148         return 0;
1149 }
1150
1151 static int on_announcement_timeout(sd_event_source *s, usec_t usec, void *userdata) {
1152         DnsScope *scope = userdata;
1153
1154         assert(s);
1155
1156         scope->announce_event_source = sd_event_source_unref(scope->announce_event_source);
1157
1158         (void) dns_scope_announce(scope, false);
1159         return 0;
1160 }
1161
1162 int dns_scope_announce(DnsScope *scope, bool goodbye) {
1163         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
1164         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
1165         _cleanup_set_free_ Set *types = NULL;
1166         DnsTransaction *t;
1167         DnsZoneItem *z, *i;
1168         unsigned size = 0;
1169         Iterator iterator;
1170         char *service_type;
1171         int r;
1172
1173         if (!scope)
1174                 return 0;
1175
1176         if (scope->protocol != DNS_PROTOCOL_MDNS)
1177                 return 0;
1178
1179         /* Check if we're done with probing. */
1180         LIST_FOREACH(transactions_by_scope, t, scope->transactions)
1181                 if (DNS_TRANSACTION_IS_LIVE(t->state))
1182                         return 0;
1183
1184         /* Check if there're services pending conflict resolution. */
1185         if (manager_next_dnssd_names(scope->manager))
1186                 return 0; /* we reach this point only if changing hostname didn't help */
1187
1188         /* Calculate answer's size. */
1189         HASHMAP_FOREACH(z, scope->zone.by_key, iterator) {
1190                 if (z->state != DNS_ZONE_ITEM_ESTABLISHED)
1191                         continue;
1192
1193                 if (z->rr->key->type == DNS_TYPE_PTR &&
1194                     !dns_zone_contains_name(&scope->zone, z->rr->ptr.name)) {
1195                         char key_str[DNS_RESOURCE_KEY_STRING_MAX];
1196
1197                         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));
1198                         z->state = DNS_ZONE_ITEM_WITHDRAWN;
1199                         continue;
1200                 }
1201
1202                 /* Collect service types for _services._dns-sd._udp.local RRs in a set */
1203                 if (!scope->announced &&
1204                     dns_resource_key_is_dnssd_ptr(z->rr->key)) {
1205                         if (!set_contains(types, dns_resource_key_name(z->rr->key))) {
1206                                 r = set_ensure_allocated(&types, &dns_name_hash_ops);
1207                                 if (r < 0)
1208                                         return log_debug_errno(r, "Failed to allocate set: %m");
1209
1210                                 r = set_put(types, dns_resource_key_name(z->rr->key));
1211                                 if (r < 0)
1212                                         return log_debug_errno(r, "Failed to add item to set: %m");
1213                         }
1214                 }
1215
1216                 LIST_FOREACH(by_key, i, z)
1217                         size++;
1218         }
1219
1220         answer = dns_answer_new(size + set_size(types));
1221         if (!answer)
1222                 return log_oom();
1223
1224         /* Second iteration, actually add RRs to the answer. */
1225         HASHMAP_FOREACH(z, scope->zone.by_key, iterator)
1226                 LIST_FOREACH (by_key, i, z) {
1227                         DnsAnswerFlags flags;
1228
1229                         if (i->state != DNS_ZONE_ITEM_ESTABLISHED)
1230                                 continue;
1231
1232                         if (dns_resource_key_is_dnssd_ptr(i->rr->key))
1233                                 flags = goodbye ? DNS_ANSWER_GOODBYE : 0;
1234                         else
1235                                 flags = goodbye ? (DNS_ANSWER_GOODBYE|DNS_ANSWER_CACHE_FLUSH) : DNS_ANSWER_CACHE_FLUSH;
1236
1237                         r = dns_answer_add(answer, i->rr, 0 , flags);
1238                         if (r < 0)
1239                                 return log_debug_errno(r, "Failed to add RR to announce: %m");
1240                 }
1241
1242         /* Since all the active services are in the zone make them discoverable now. */
1243         SET_FOREACH(service_type, types, iterator) {
1244                 _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr;
1245
1246                 rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR,
1247                                                   "_services._dns-sd._udp.local");
1248                 rr->ptr.name = strdup(service_type);
1249                 rr->ttl = MDNS_DEFAULT_TTL;
1250
1251                 r = dns_zone_put(&scope->zone, scope, rr, false);
1252                 if (r < 0)
1253                         log_warning_errno(r, "Failed to add DNS-SD PTR record to MDNS zone: %m");
1254
1255                 r = dns_answer_add(answer, rr, 0 , 0);
1256                 if (r < 0)
1257                         return log_debug_errno(r, "Failed to add RR to announce: %m");
1258         }
1259
1260         if (dns_answer_isempty(answer))
1261                 return 0;
1262
1263         r = dns_scope_make_reply_packet(scope, 0, DNS_RCODE_SUCCESS, NULL, answer, NULL, false, &p);
1264         if (r < 0)
1265                 return log_debug_errno(r, "Failed to build reply packet: %m");
1266
1267         r = dns_scope_emit_udp(scope, -1, p);
1268         if (r < 0)
1269                 return log_debug_errno(r, "Failed to send reply packet: %m");
1270
1271         /* In section 8.3 of RFC6762: "The Multicast DNS responder MUST send at least two unsolicited
1272          * responses, one second apart." */
1273         if (!scope->announced) {
1274                 usec_t ts;
1275
1276                 scope->announced = true;
1277
1278                 assert_se(sd_event_now(scope->manager->event, clock_boottime_or_monotonic(), &ts) >= 0);
1279                 ts += MDNS_ANNOUNCE_DELAY;
1280
1281                 r = sd_event_add_time(
1282                                 scope->manager->event,
1283                                 &scope->announce_event_source,
1284                                 clock_boottime_or_monotonic(),
1285                                 ts,
1286                                 MDNS_JITTER_RANGE_USEC,
1287                                 on_announcement_timeout, scope);
1288                 if (r < 0)
1289                         return log_debug_errno(r, "Failed to schedule second announcement: %m");
1290
1291                 (void) sd_event_source_set_description(scope->announce_event_source, "mdns-announce");
1292         }
1293
1294         return 0;
1295 }
1296
1297 int dns_scope_add_dnssd_services(DnsScope *scope) {
1298         Iterator i;
1299         DnssdService *service;
1300         DnssdTxtData *txt_data;
1301         int r;
1302
1303         assert(scope);
1304
1305         if (hashmap_size(scope->manager->dnssd_services) == 0)
1306                 return 0;
1307
1308         scope->announced = false;
1309
1310         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1311                 service->withdrawn = false;
1312
1313                 r = dns_zone_put(&scope->zone, scope, service->ptr_rr, false);
1314                 if (r < 0)
1315                         log_warning_errno(r, "Failed to add PTR record to MDNS zone: %m");
1316
1317                 r = dns_zone_put(&scope->zone, scope, service->srv_rr, true);
1318                 if (r < 0)
1319                         log_warning_errno(r, "Failed to add SRV record to MDNS zone: %m");
1320
1321                 LIST_FOREACH(items, txt_data, service->txt_data_items) {
1322                         r = dns_zone_put(&scope->zone, scope, txt_data->rr, true);
1323                         if (r < 0)
1324                                 log_warning_errno(r, "Failed to add TXT record to MDNS zone: %m");
1325                 }
1326         }
1327
1328         return 0;
1329 }
1330
1331 int dns_scope_remove_dnssd_services(DnsScope *scope) {
1332         _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
1333         Iterator i;
1334         DnssdService *service;
1335         DnssdTxtData *txt_data;
1336         int r;
1337
1338         assert(scope);
1339
1340         key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_PTR,
1341                                    "_services._dns-sd._udp.local");
1342         if (!key)
1343                 return log_oom();
1344
1345         r = dns_zone_remove_rrs_by_key(&scope->zone, key);
1346         if (r < 0)
1347                 return r;
1348
1349         HASHMAP_FOREACH(service, scope->manager->dnssd_services, i) {
1350                 dns_zone_remove_rr(&scope->zone, service->ptr_rr);
1351                 dns_zone_remove_rr(&scope->zone, service->srv_rr);
1352                 LIST_FOREACH(items, txt_data, service->txt_data_items)
1353                         dns_zone_remove_rr(&scope->zone, txt_data->rr);
1354         }
1355
1356         return 0;
1357 }