src/resolve/resolved-llmnr.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2014 Tom Gundersen <teg@jklm.no>
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18  ***/
  19
  20 #include <netinet/in.h>
  21 #include <resolv.h>
  22
  23 #include "fd-util.h"
  24 #include "resolved-llmnr.h"
  25 #include "resolved-manager.h"
  26
  27 void manager_llmnr_stop(Manager *m) {
  28         assert(m);
  29
  30         m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
  31         m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
  32
  33         m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
  34         m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
  35
  36         m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
  37         m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
  38
  39         m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
  40         m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
  41 }
  42
  43 int manager_llmnr_start(Manager *m) {
  44         int r;
  45
  46         assert(m);
  47
  48         if (m->llmnr_support == RESOLVE_SUPPORT_NO)
  49                 return 0;
  50
  51         r = manager_llmnr_ipv4_udp_fd(m);
  52         if (r == -EADDRINUSE)
  53                 goto eaddrinuse;
  54         if (r < 0)
  55                 return r;
  56
  57         r = manager_llmnr_ipv4_tcp_fd(m);
  58         if (r == -EADDRINUSE)
  59                 goto eaddrinuse;
  60         if (r < 0)
  61                 return r;
  62
  63         if (socket_ipv6_is_supported()) {
  64                 r = manager_llmnr_ipv6_udp_fd(m);
  65                 if (r == -EADDRINUSE)
  66                         goto eaddrinuse;
  67                 if (r < 0)
  68                         return r;
  69
  70                 r = manager_llmnr_ipv6_tcp_fd(m);
  71                 if (r == -EADDRINUSE)
  72                         goto eaddrinuse;
  73                 if (r < 0)
  74                         return r;
  75         }
  76
  77         return 0;
  78
  79 eaddrinuse:
  80         log_warning("There appears to be another LLMNR responder running. Turning off LLMNR support.");
  81         m->llmnr_support = RESOLVE_SUPPORT_NO;
  82         manager_llmnr_stop(m);
  83
  84         return 0;
  85 }
  86
  87 static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
  88         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
  89         DnsTransaction *t = NULL;
  90         Manager *m = userdata;
  91         DnsScope *scope;
  92         int r;
  93
  94         assert(s);
  95         assert(fd >= 0);
  96         assert(m);
  97
  98         r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
  99         if (r <= 0)
 100                 return r;
 101
 102         scope = manager_find_scope(m, p);
 103         if (!scope)
 104                 log_warning("Got LLMNR UDP packet on unknown scope. Ignoring.");
 105         else if (dns_packet_validate_reply(p) > 0) {
 106                 log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
 107
 108                 dns_scope_check_conflicts(scope, p);
 109
 110                 t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
 111                 if (t)
 112                         dns_transaction_process_reply(t, p);
 113
 114         } else if (dns_packet_validate_query(p) > 0)  {
 115                 log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
 116
 117                 dns_scope_process_query(scope, NULL, p);
 118         } else
 119                 log_debug("Invalid LLMNR UDP packet, ignoring.");
 120
 121         return 0;
 122 }
 123
 124 int manager_llmnr_ipv4_udp_fd(Manager *m) {
 125         union sockaddr_union sa = {
 126                 .in.sin_family = AF_INET,
 127                 .in.sin_port = htobe16(LLMNR_PORT),
 128         };
 129         static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
 130         int r;
 131
 132         assert(m);
 133
 134         if (m->llmnr_ipv4_udp_fd >= 0)
 135                 return m->llmnr_ipv4_udp_fd;
 136
 137         m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 138         if (m->llmnr_ipv4_udp_fd < 0)
 139                 return -errno;
 140
 141         /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
 142         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
 143         if (r < 0) {
 144                 r = -errno;
 145                 goto fail;
 146         }
 147
 148         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
 149         if (r < 0) {
 150                 r = -errno;
 151                 goto fail;
 152         }
 153
 154         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
 155         if (r < 0) {
 156                 r = -errno;
 157                 goto fail;
 158         }
 159
 160         r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 161         if (r < 0) {
 162                 r = -errno;
 163                 goto fail;
 164         }
 165
 166         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
 167         if (r < 0) {
 168                 r = -errno;
 169                 goto fail;
 170         }
 171
 172         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
 173         if (r < 0) {
 174                 r = -errno;
 175                 goto fail;
 176         }
 177
 178         /* Disable Don't-Fragment bit in the IP header */
 179         r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
 180         if (r < 0) {
 181                 r = -errno;
 182                 goto fail;
 183         }
 184
 185         r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
 186         if (r < 0) {
 187                 r = -errno;
 188                 goto fail;
 189         }
 190
 191         r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
 192         if (r < 0)
 193                 goto fail;
 194
 195         (void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
 196
 197         return m->llmnr_ipv4_udp_fd;
 198
 199 fail:
 200         m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
 201         return r;
 202 }
 203
 204 int manager_llmnr_ipv6_udp_fd(Manager *m) {
 205         union sockaddr_union sa = {
 206                 .in6.sin6_family = AF_INET6,
 207                 .in6.sin6_port = htobe16(LLMNR_PORT),
 208         };
 209         static const int one = 1, ttl = 255;
 210         int r;
 211
 212         assert(m);
 213
 214         if (m->llmnr_ipv6_udp_fd >= 0)
 215                 return m->llmnr_ipv6_udp_fd;
 216
 217         m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 218         if (m->llmnr_ipv6_udp_fd < 0)
 219                 return -errno;
 220
 221         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
 222         if (r < 0) {
 223                 r = -errno;
 224                 goto fail;
 225         }
 226
 227         /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
 228         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
 229         if (r < 0) {
 230                 r = -errno;
 231                 goto fail;
 232         }
 233
 234         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
 235         if (r < 0) {
 236                 r = -errno;
 237                 goto fail;
 238         }
 239
 240         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 241         if (r < 0) {
 242                 r = -errno;
 243                 goto fail;
 244         }
 245
 246         r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 247         if (r < 0) {
 248                 r = -errno;
 249                 goto fail;
 250         }
 251
 252         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
 253         if (r < 0) {
 254                 r = -errno;
 255                 goto fail;
 256         }
 257
 258         r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
 259         if (r < 0) {
 260                 r = -errno;
 261                 goto fail;
 262         }
 263
 264         r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
 265         if (r < 0) {
 266                 r = -errno;
 267                 goto fail;
 268         }
 269
 270         r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
 271         if (r < 0)
 272                 goto fail;
 273
 274         (void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
 275
 276         return m->llmnr_ipv6_udp_fd;
 277
 278 fail:
 279         m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
 280         return r;
 281 }
 282
 283 static int on_llmnr_stream_packet(DnsStream *s) {
 284         DnsScope *scope;
 285
 286         assert(s);
 287         assert(s->read_packet);
 288
 289         scope = manager_find_scope(s->manager, s->read_packet);
 290         if (!scope)
 291                 log_warning("Got LLMNR TCP packet on unknown scope. Ignoring.");
 292         else if (dns_packet_validate_query(s->read_packet) > 0) {
 293                 log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
 294
 295                 dns_scope_process_query(scope, s, s->read_packet);
 296         } else
 297                 log_debug("Invalid LLMNR TCP packet, ignoring.");
 298
 299         dns_stream_unref(s);
 300         return 0;
 301 }
 302
 303 static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
 304         DnsStream *stream;
 305         Manager *m = userdata;
 306         int cfd, r;
 307
 308         cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
 309         if (cfd < 0) {
 310                 if (errno == EAGAIN || errno == EINTR)
 311                         return 0;
 312
 313                 return -errno;
 314         }
 315
 316         r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd);
 317         if (r < 0) {
 318                 safe_close(cfd);
 319                 return r;
 320         }
 321
 322         stream->on_packet = on_llmnr_stream_packet;
 323         return 0;
 324 }
 325
 326 int manager_llmnr_ipv4_tcp_fd(Manager *m) {
 327         union sockaddr_union sa = {
 328                 .in.sin_family = AF_INET,
 329                 .in.sin_port = htobe16(LLMNR_PORT),
 330         };
 331         static const int one = 1, pmtu = IP_PMTUDISC_DONT;
 332         int r;
 333
 334         assert(m);
 335
 336         if (m->llmnr_ipv4_tcp_fd >= 0)
 337                 return m->llmnr_ipv4_tcp_fd;
 338
 339         m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 340         if (m->llmnr_ipv4_tcp_fd < 0)
 341                 return -errno;
 342
 343         /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
 344         r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
 345         if (r < 0) {
 346                 r = -errno;
 347                 goto fail;
 348         }
 349
 350         r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 351         if (r < 0) {
 352                 r = -errno;
 353                 goto fail;
 354         }
 355
 356         r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
 357         if (r < 0) {
 358                 r = -errno;
 359                 goto fail;
 360         }
 361
 362         r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
 363         if (r < 0) {
 364                 r = -errno;
 365                 goto fail;
 366         }
 367
 368         /* Disable Don't-Fragment bit in the IP header */
 369         r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
 370         if (r < 0) {
 371                 r = -errno;
 372                 goto fail;
 373         }
 374
 375         r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
 376         if (r < 0) {
 377                 r = -errno;
 378                 goto fail;
 379         }
 380
 381         r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
 382         if (r < 0) {
 383                 r = -errno;
 384                 goto fail;
 385         }
 386
 387         r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
 388         if (r < 0)
 389                 goto fail;
 390
 391         (void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
 392
 393         return m->llmnr_ipv4_tcp_fd;
 394
 395 fail:
 396         m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
 397         return r;
 398 }
 399
 400 int manager_llmnr_ipv6_tcp_fd(Manager *m) {
 401         union sockaddr_union sa = {
 402                 .in6.sin6_family = AF_INET6,
 403                 .in6.sin6_port = htobe16(LLMNR_PORT),
 404         };
 405         static const int one = 1;
 406         int r;
 407
 408         assert(m);
 409
 410         if (m->llmnr_ipv6_tcp_fd >= 0)
 411                 return m->llmnr_ipv6_tcp_fd;
 412
 413         m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 414         if (m->llmnr_ipv6_tcp_fd < 0)
 415                 return -errno;
 416
 417         /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
 418         r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
 419         if (r < 0) {
 420                 r = -errno;
 421                 goto fail;
 422         }
 423
 424         r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
 425         if (r < 0) {
 426                 r = -errno;
 427                 goto fail;
 428         }
 429
 430         r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
 431         if (r < 0) {
 432                 r = -errno;
 433                 goto fail;
 434         }
 435
 436         r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
 437         if (r < 0) {
 438                 r = -errno;
 439                 goto fail;
 440         }
 441
 442         r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
 443         if (r < 0) {
 444                 r = -errno;
 445                 goto fail;
 446         }
 447
 448         r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
 449         if (r < 0) {
 450                 r = -errno;
 451                 goto fail;
 452         }
 453
 454         r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
 455         if (r < 0) {
 456                 r = -errno;
 457                 goto fail;
 458         }
 459
 460         r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
 461         if (r < 0)
 462                 goto fail;
 463
 464         (void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
 465
 466         return m->llmnr_ipv6_tcp_fd;
 467
 468 fail:
 469         m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
 470         return r;
 471 }