src/net_socket.c

   1 /*
   2     net_socket.c -- Handle various kinds of sockets.
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2013 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6                   2009      Florian Forster <octo@verplant.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License along
  19     with this program; if not, write to the Free Software Foundation, Inc.,
  20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21 */
  22
  23 #include "system.h"
  24
  25 #include "avl_tree.h"
  26 #include "conf.h"
  27 #include "connection.h"
  28 #include "event.h"
  29 #include "logger.h"
  30 #include "meta.h"
  31 #include "net.h"
  32 #include "netutl.h"
  33 #include "protocol.h"
  34 #include "utils.h"
  35 #include "xalloc.h"
  36
  37 /* Needed on Mac OS/X */
  38 #ifndef SOL_TCP
  39 #define SOL_TCP IPPROTO_TCP
  40 #endif
  41
  42 int addressfamily = AF_UNSPEC;
  43 int maxtimeout = 900;
  44 int seconds_till_retry = 5;
  45 int udp_rcvbuf = 0;
  46 int udp_sndbuf = 0;
  47
  48 listen_socket_t listen_socket[MAXSOCKETS];
  49 int listen_sockets;
  50 list_t *outgoing_list = NULL;
  51
  52 /* Setup sockets */
  53
  54 static void configure_tcp(connection_t *c) {
  55         int option;
  56
  57 #ifdef O_NONBLOCK
  58         int flags = fcntl(c->socket, F_GETFL);
  59
  60         if(fcntl(c->socket, F_SETFL, flags | O_NONBLOCK) < 0) {
  61                 logger(LOG_ERR, "fcntl for %s: %s", c->hostname, strerror(errno));
  62         }
  63 #elif defined(WIN32)
  64         unsigned long arg = 1;
  65
  66         if(ioctlsocket(c->socket, FIONBIO, &arg) != 0) {
  67                 logger(LOG_ERR, "ioctlsocket for %s: %s", c->hostname, sockstrerror(sockerrno));
  68         }
  69 #endif
  70
  71 #if defined(SOL_TCP) && defined(TCP_NODELAY)
  72         option = 1;
  73         setsockopt(c->socket, SOL_TCP, TCP_NODELAY, (void *)&option, sizeof(option));
  74 #endif
  75
  76 #if defined(SOL_IP) && defined(IP_TOS) && defined(IPTOS_LOWDELAY)
  77         option = IPTOS_LOWDELAY;
  78         setsockopt(c->socket, SOL_IP, IP_TOS, (void *)&option, sizeof(option));
  79 #endif
  80 }
  81
  82 static bool bind_to_interface(int sd) {
  83         char *iface;
  84
  85 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
  86         struct ifreq ifr;
  87         int status;
  88 #endif /* defined(SOL_SOCKET) && defined(SO_BINDTODEVICE) */
  89
  90         if(!get_config_string (lookup_config (config_tree, "BindToInterface"), &iface))
  91                 return true;
  92
  93 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
  94         memset(&ifr, 0, sizeof(ifr));
  95         strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
  96         ifr.ifr_ifrn.ifrn_name[IFNAMSIZ - 1] = 0;
  97
  98         status = setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr));
  99         if(status) {
 100                 logger(LOG_ERR, "Can't bind to interface %s: %s", iface,
 101                                 strerror(errno));
 102                 return false;
 103         }
 104 #else /* if !defined(SOL_SOCKET) || !defined(SO_BINDTODEVICE) */
 105         logger(LOG_WARNING, "%s not supported on this platform", "BindToInterface");
 106 #endif
 107
 108         return true;
 109 }
 110
 111 int setup_listen_socket(const sockaddr_t *sa) {
 112         int nfd;
 113         char *addrstr;
 114         int option;
 115         char *iface;
 116
 117         nfd = socket(sa->sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 118
 119         if(nfd < 0) {
 120                 ifdebug(STATUS) logger(LOG_ERR, "Creating metasocket failed: %s", sockstrerror(sockerrno));
 121                 return -1;
 122         }
 123
 124 #ifdef FD_CLOEXEC
 125         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 126 #endif
 127
 128         /* Optimize TCP settings */
 129
 130         option = 1;
 131         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
 132
 133 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 134         if(sa->sa.sa_family == AF_INET6)
 135                 setsockopt(nfd, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 136 #endif
 137
 138         if(get_config_string
 139            (lookup_config(config_tree, "BindToInterface"), &iface)) {
 140 #if defined(SOL_SOCKET) && defined(SO_BINDTODEVICE)
 141                 struct ifreq ifr;
 142
 143                 memset(&ifr, 0, sizeof(ifr));
 144                 strncpy(ifr.ifr_ifrn.ifrn_name, iface, IFNAMSIZ);
 145
 146                 if(setsockopt(nfd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) {
 147                         closesocket(nfd);
 148                         logger(LOG_ERR, "Can't bind to interface %s: %s", iface,
 149                                    strerror(sockerrno));
 150                         return -1;
 151                 }
 152 #else
 153                 logger(LOG_WARNING, "%s not supported on this platform", "BindToInterface");
 154 #endif
 155         }
 156
 157         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 158                 closesocket(nfd);
 159                 addrstr = sockaddr2hostname(sa);
 160                 logger(LOG_ERR, "Can't bind to %s/tcp: %s", addrstr, sockstrerror(sockerrno));
 161                 free(addrstr);
 162                 return -1;
 163         }
 164
 165         if(listen(nfd, 3)) {
 166                 closesocket(nfd);
 167                 logger(LOG_ERR, "System call `%s' failed: %s", "listen", sockstrerror(sockerrno));
 168                 return -1;
 169         }
 170
 171         return nfd;
 172 }
 173
 174 int setup_vpn_in_socket(const sockaddr_t *sa) {
 175         int nfd;
 176         char *addrstr;
 177         int option;
 178
 179         nfd = socket(sa->sa.sa_family, SOCK_DGRAM, IPPROTO_UDP);
 180
 181         if(nfd < 0) {
 182                 logger(LOG_ERR, "Creating UDP socket failed: %s", sockstrerror(sockerrno));
 183                 return -1;
 184         }
 185
 186 #ifdef FD_CLOEXEC
 187         fcntl(nfd, F_SETFD, FD_CLOEXEC);
 188 #endif
 189
 190 #ifdef O_NONBLOCK
 191         {
 192                 int flags = fcntl(nfd, F_GETFL);
 193
 194                 if(fcntl(nfd, F_SETFL, flags | O_NONBLOCK) < 0) {
 195                         closesocket(nfd);
 196                         logger(LOG_ERR, "System call `%s' failed: %s", "fcntl",
 197                                    strerror(errno));
 198                         return -1;
 199                 }
 200         }
 201 #elif defined(WIN32)
 202         {
 203                 unsigned long arg = 1;
 204                 if(ioctlsocket(nfd, FIONBIO, &arg) != 0) {
 205                         closesocket(nfd);
 206                         logger(LOG_ERR, "Call to `%s' failed: %s", "ioctlsocket", sockstrerror(sockerrno));
 207                         return -1;
 208                 }
 209         }
 210 #endif
 211
 212         option = 1;
 213         setsockopt(nfd, SOL_SOCKET, SO_REUSEADDR, (void *)&option, sizeof(option));
 214         setsockopt(nfd, SOL_SOCKET, SO_BROADCAST, (void *)&option, sizeof(option));
 215
 216         if(udp_rcvbuf && setsockopt(nfd, SOL_SOCKET, SO_RCVBUF, (void *)&udp_rcvbuf, sizeof(udp_rcvbuf)))
 217                 logger(LOG_WARNING, "Can't set UDP SO_RCVBUF to %i: %s", udp_rcvbuf, strerror(errno));
 218
 219         if(udp_sndbuf && setsockopt(nfd, SOL_SOCKET, SO_SNDBUF, (void *)&udp_sndbuf, sizeof(udp_sndbuf)))
 220                 logger(LOG_WARNING, "Can't set UDP SO_SNDBUF to %i: %s", udp_sndbuf, strerror(errno));
 221
 222 #if defined(IPPROTO_IPV6) && defined(IPV6_V6ONLY)
 223         if(sa->sa.sa_family == AF_INET6)
 224                 setsockopt(nfd, IPPROTO_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 225 #endif
 226
 227 #if defined(IP_DONTFRAG) && !defined(IP_DONTFRAGMENT)
 228 #define IP_DONTFRAGMENT IP_DONTFRAG
 229 #endif
 230
 231 #if defined(SOL_IP) && defined(IP_MTU_DISCOVER) && defined(IP_PMTUDISC_DO)
 232         if(myself->options & OPTION_PMTU_DISCOVERY) {
 233                 option = IP_PMTUDISC_DO;
 234                 setsockopt(nfd, SOL_IP, IP_MTU_DISCOVER, (void *)&option, sizeof(option));
 235         }
 236 #elif defined(IPPROTO_IP) && defined(IP_DONTFRAGMENT)
 237         if(myself->options & OPTION_PMTU_DISCOVERY) {
 238                 option = 1;
 239                 setsockopt(nfd, IPPROTO_IP, IP_DONTFRAGMENT, (void *)&option, sizeof(option));
 240         }
 241 #else
 242 #warning No way to disable IPv4 fragmentation
 243 #endif
 244
 245 #if defined(SOL_IPV6) && defined(IPV6_MTU_DISCOVER) && defined(IPV6_PMTUDISC_DO)
 246         if(myself->options & OPTION_PMTU_DISCOVERY) {
 247                 option = IPV6_PMTUDISC_DO;
 248                 setsockopt(nfd, SOL_IPV6, IPV6_MTU_DISCOVER, (void *)&option, sizeof(option));
 249         }
 250 #elif defined(IPPROTO_IPV6) && defined(IPV6_DONTFRAG)
 251         if(myself->options & OPTION_PMTU_DISCOVERY) {
 252                 option = 1;
 253                 setsockopt(nfd, IPPROTO_IPV6, IPV6_DONTFRAG, (void *)&option, sizeof(option));
 254         }
 255 #else
 256 #warning No way to disable IPv6 fragmentation
 257 #endif
 258
 259         if (!bind_to_interface(nfd)) {
 260                 closesocket(nfd);
 261                 return -1;
 262         }
 263
 264         if(bind(nfd, &sa->sa, SALEN(sa->sa))) {
 265                 closesocket(nfd);
 266                 addrstr = sockaddr2hostname(sa);
 267                 logger(LOG_ERR, "Can't bind to %s/udp: %s", addrstr, sockstrerror(sockerrno));
 268                 free(addrstr);
 269                 return -1;
 270         }
 271
 272         return nfd;
 273 } /* int setup_vpn_in_socket */
 274
 275 void retry_outgoing(outgoing_t *outgoing) {
 276         outgoing->timeout += 5;
 277
 278         if(outgoing->timeout > maxtimeout)
 279                 outgoing->timeout = maxtimeout;
 280
 281         if(outgoing->event)
 282                 event_del(outgoing->event);
 283         outgoing->event = new_event();
 284         outgoing->event->handler = (event_handler_t) setup_outgoing_connection;
 285         outgoing->event->time = now + outgoing->timeout;
 286         outgoing->event->data = outgoing;
 287         event_add(outgoing->event);
 288
 289         ifdebug(CONNECTIONS) logger(LOG_NOTICE,
 290                            "Trying to re-establish outgoing connection in %d seconds",
 291                            outgoing->timeout);
 292 }
 293
 294 void finish_connecting(connection_t *c) {
 295         ifdebug(CONNECTIONS) logger(LOG_INFO, "Connected to %s (%s)", c->name, c->hostname);
 296
 297         c->last_ping_time = now;
 298
 299         send_id(c);
 300 }
 301
 302 static void do_outgoing_pipe(connection_t *c, char *command) {
 303 #ifndef HAVE_MINGW
 304         int fd[2];
 305
 306         if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
 307                 logger(LOG_ERR, "Could not create socketpair: %s\n", strerror(errno));
 308                 return;
 309         }
 310
 311         if(fork()) {
 312                 c->socket = fd[0];
 313                 close(fd[1]);
 314                 ifdebug(CONNECTIONS) logger(LOG_DEBUG, "Using proxy %s", command);
 315                 return;
 316         }
 317
 318         close(0);
 319         close(1);
 320         close(fd[0]);
 321         dup2(fd[1], 0);
 322         dup2(fd[1], 1);
 323         close(fd[1]);
 324
 325         // Other filedescriptors should be closed automatically by CLOEXEC
 326
 327         char *host = NULL;
 328         char *port = NULL;
 329
 330         sockaddr2str(&c->address, &host, &port);
 331         setenv("REMOTEADDRESS", host, true);
 332         setenv("REMOTEPORT", port, true);
 333         setenv("NODE", c->name, true);
 334         setenv("NAME", myself->name, true);
 335         if(netname)
 336                 setenv("NETNAME", netname, true);
 337
 338         int result = system(command);
 339         if(result < 0)
 340                 logger(LOG_ERR, "Could not execute %s: %s\n", command, strerror(errno));
 341         else if(result)
 342                 logger(LOG_ERR, "%s exited with non-zero status %d", command, result);
 343         exit(result);
 344 #else
 345         logger(LOG_ERR, "Proxy type exec not supported on this platform!");
 346         return;
 347 #endif
 348 }
 349
 350 void do_outgoing_connection(connection_t *c) {
 351         char *address, *port, *space;
 352         struct addrinfo *proxyai = NULL;
 353         int result;
 354
 355         if(!c->outgoing) {
 356                 logger(LOG_ERR, "do_outgoing_connection() for %s called without c->outgoing", c->name);
 357                 abort();
 358         }
 359
 360 begin:
 361         if(!c->outgoing->ai) {
 362                 if(!c->outgoing->cfg) {
 363                         ifdebug(CONNECTIONS) logger(LOG_ERR, "Could not set up a meta connection to %s",
 364                                            c->name);
 365                         c->status.remove = true;
 366                         retry_outgoing(c->outgoing);
 367                         c->outgoing = NULL;
 368                         return;
 369                 }
 370
 371                 get_config_string(c->outgoing->cfg, &address);
 372
 373                 space = strchr(address, ' ');
 374                 if(space) {
 375                         port = xstrdup(space + 1);
 376                         *space = 0;
 377                 } else {
 378                         if(!get_config_string(lookup_config(c->config_tree, "Port"), &port))
 379                                 port = xstrdup("655");
 380                 }
 381
 382                 c->outgoing->ai = str2addrinfo(address, port, SOCK_STREAM);
 383                 free(address);
 384                 free(port);
 385
 386                 c->outgoing->aip = c->outgoing->ai;
 387                 c->outgoing->cfg = lookup_config_next(c->config_tree, c->outgoing->cfg);
 388         }
 389
 390         if(!c->outgoing->aip) {
 391                 if(c->outgoing->ai)
 392                         freeaddrinfo(c->outgoing->ai);
 393                 c->outgoing->ai = NULL;
 394                 goto begin;
 395         }
 396
 397         memcpy(&c->address, c->outgoing->aip->ai_addr, c->outgoing->aip->ai_addrlen);
 398         c->outgoing->aip = c->outgoing->aip->ai_next;
 399
 400         if(c->hostname)
 401                 free(c->hostname);
 402
 403         c->hostname = sockaddr2hostname(&c->address);
 404
 405         ifdebug(CONNECTIONS) logger(LOG_INFO, "Trying to connect to %s (%s)", c->name,
 406                            c->hostname);
 407
 408         if(!proxytype) {
 409                 c->socket = socket(c->address.sa.sa_family, SOCK_STREAM, IPPROTO_TCP);
 410                 configure_tcp(c);
 411         } else if(proxytype == PROXY_EXEC) {
 412                 do_outgoing_pipe(c, proxyhost);
 413         } else {
 414                 proxyai = str2addrinfo(proxyhost, proxyport, SOCK_STREAM);
 415                 if(!proxyai)
 416                         goto begin;
 417                 ifdebug(CONNECTIONS) logger(LOG_INFO, "Using proxy at %s port %s", proxyhost, proxyport);
 418                 c->socket = socket(proxyai->ai_family, SOCK_STREAM, IPPROTO_TCP);
 419                 configure_tcp(c);
 420         }
 421
 422         if(c->socket == -1) {
 423                 ifdebug(CONNECTIONS) logger(LOG_ERR, "Creating socket for %s failed: %s", c->hostname, sockstrerror(sockerrno));
 424                 goto begin;
 425         }
 426
 427 #ifdef FD_CLOEXEC
 428         fcntl(c->socket, F_SETFD, FD_CLOEXEC);
 429 #endif
 430
 431         if(proxytype != PROXY_EXEC) {
 432 #if defined(SOL_IPV6) && defined(IPV6_V6ONLY)
 433                 int option = 1;
 434                 if(c->address.sa.sa_family == AF_INET6)
 435                         setsockopt(c->socket, SOL_IPV6, IPV6_V6ONLY, (void *)&option, sizeof option);
 436 #endif
 437
 438                 bind_to_interface(c->socket);
 439         }
 440
 441         /* Connect */
 442
 443         if(!proxytype) {
 444                 result = connect(c->socket, &c->address.sa, SALEN(c->address.sa));
 445         } else if(proxytype == PROXY_EXEC) {
 446                 result = 0;
 447         } else {
 448                 result = connect(c->socket, proxyai->ai_addr, proxyai->ai_addrlen);
 449                 freeaddrinfo(proxyai);
 450         }
 451
 452         if(result == -1) {
 453                 if(sockinprogress(sockerrno)) {
 454                         c->status.connecting = true;
 455                         return;
 456                 }
 457
 458                 closesocket(c->socket);
 459
 460                 ifdebug(CONNECTIONS) logger(LOG_ERR, "%s: %s", c->hostname, sockstrerror(sockerrno));
 461
 462                 goto begin;
 463         }
 464
 465         finish_connecting(c);
 466
 467         return;
 468 }
 469
 470 void setup_outgoing_connection(outgoing_t *outgoing) {
 471         connection_t *c;
 472         node_t *n;
 473
 474         outgoing->event = NULL;
 475
 476         n = lookup_node(outgoing->name);
 477
 478         if(n)
 479                 if(n->connection) {
 480                         ifdebug(CONNECTIONS) logger(LOG_INFO, "Already connected to %s", outgoing->name);
 481
 482                         n->connection->outgoing = outgoing;
 483                         return;
 484                 }
 485
 486         c = new_connection();
 487         c->name = xstrdup(outgoing->name);
 488         c->outcipher = myself->connection->outcipher;
 489         c->outdigest = myself->connection->outdigest;
 490         c->outmaclength = myself->connection->outmaclength;
 491         c->outcompression = myself->connection->outcompression;
 492
 493         init_configuration(&c->config_tree);
 494         read_connection_config(c);
 495
 496         outgoing->cfg = lookup_config(c->config_tree, "Address");
 497
 498         if(!outgoing->cfg) {
 499                 logger(LOG_ERR, "No address specified for %s", c->name);
 500                 free_connection(c);
 501                 return;
 502         }
 503
 504         c->outgoing = outgoing;
 505         c->last_ping_time = now;
 506
 507         connection_add(c);
 508
 509         do_outgoing_connection(c);
 510 }
 511
 512 /*
 513   accept a new tcp connect and create a
 514   new connection
 515 */
 516 bool handle_new_meta_connection(int sock) {
 517         connection_t *c;
 518         sockaddr_t sa;
 519         int fd;
 520         socklen_t len = sizeof(sa);
 521
 522         fd = accept(sock, &sa.sa, &len);
 523
 524         if(fd < 0) {
 525                 logger(LOG_ERR, "Accepting a new connection failed: %s", sockstrerror(sockerrno));
 526                 return false;
 527         }
 528
 529         sockaddrunmap(&sa);
 530
 531         c = new_connection();
 532         c->name = xstrdup("<unknown>");
 533         c->outcipher = myself->connection->outcipher;
 534         c->outdigest = myself->connection->outdigest;
 535         c->outmaclength = myself->connection->outmaclength;
 536         c->outcompression = myself->connection->outcompression;
 537
 538         c->address = sa;
 539         c->hostname = sockaddr2hostname(&sa);
 540         c->socket = fd;
 541         c->last_ping_time = now;
 542
 543         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Connection from %s", c->hostname);
 544
 545         configure_tcp(c);
 546
 547         connection_add(c);
 548
 549         c->allow_request = ID;
 550         send_id(c);
 551
 552         return true;
 553 }
 554
 555 static void free_outgoing(outgoing_t *outgoing) {
 556         if(outgoing->ai)
 557                 freeaddrinfo(outgoing->ai);
 558
 559         if(outgoing->name)
 560                 free(outgoing->name);
 561
 562         free(outgoing);
 563 }
 564
 565 void try_outgoing_connections(void) {
 566         static config_t *cfg = NULL;
 567         char *name;
 568         outgoing_t *outgoing;
 569
 570         outgoing_list = list_alloc((list_action_t)free_outgoing);
 571
 572         for(cfg = lookup_config(config_tree, "ConnectTo"); cfg; cfg = lookup_config_next(config_tree, cfg)) {
 573                 get_config_string(cfg, &name);
 574
 575                 if(!check_id(name)) {
 576                         logger(LOG_ERR,
 577                                    "Invalid name for outgoing connection in %s line %d",
 578                                    cfg->file, cfg->line);
 579                         free(name);
 580                         continue;
 581                 }
 582
 583                 outgoing = xmalloc_and_zero(sizeof(*outgoing));
 584                 outgoing->name = name;
 585                 list_insert_tail(outgoing_list, outgoing);
 586                 setup_outgoing_connection(outgoing);
 587         }
 588 }