www.tinc-vpn.org Git - tinc/blob - src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2012 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6                   2011      Loïc Grenié <loic.grenie@gmail.com>
   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 <openssl/rand.h>
  26
  27 #include "utils.h"
  28 #include "avl_tree.h"
  29 #include "conf.h"
  30 #include "connection.h"
  31 #include "device.h"
  32 #include "event.h"
  33 #include "graph.h"
  34 #include "logger.h"
  35 #include "meta.h"
  36 #include "net.h"
  37 #include "netutl.h"
  38 #include "process.h"
  39 #include "protocol.h"
  40 #include "route.h"
  41 #include "subnet.h"
  42 #include "xalloc.h"
  43
  44 #ifdef HAVE_RESOLV_H
  45 #include <resolv.h>
  46 #endif
  47
  48 bool do_purge = false;
  49 volatile bool running = false;
  50 #ifdef HAVE_PSELECT
  51 bool graph_dump = false;
  52 #endif
  53
  54 time_t now = 0;
  55 int contradicting_add_edge = 0;
  56 int contradicting_del_edge = 0;
  57 static int sleeptime = 10;
  58
  59 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  60
  61 static void purge(void) {
  62         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  63         node_t *n;
  64         edge_t *e;
  65         subnet_t *s;
  66
  67         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
  68
  69         /* Remove all edges and subnets owned by unreachable nodes. */
  70
  71         for(nnode = node_tree->head; nnode; nnode = nnext) {
  72                 nnext = nnode->next;
  73                 n = nnode->data;
  74
  75                 if(!n->status.reachable) {
  76                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
  77                                            n->hostname);
  78
  79                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  80                                 snext = snode->next;
  81                                 s = snode->data;
  82                                 send_del_subnet(everyone, s);
  83                                 if(!strictsubnets)
  84                                         subnet_del(n, s);
  85                         }
  86
  87                         for(enode = n->edge_tree->head; enode; enode = enext) {
  88                                 enext = enode->next;
  89                                 e = enode->data;
  90                                 if(!tunnelserver)
  91                                         send_del_edge(everyone, e);
  92                                 edge_del(e);
  93                         }
  94                 }
  95         }
  96
  97         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  98
  99         for(nnode = node_tree->head; nnode; nnode = nnext) {
 100                 nnext = nnode->next;
 101                 n = nnode->data;
 102
 103                 if(!n->status.reachable) {
 104                         for(enode = edge_weight_tree->head; enode; enode = enext) {
 105                                 enext = enode->next;
 106                                 e = enode->data;
 107
 108                                 if(e->to == n)
 109                                         break;
 110                         }
 111
 112                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
 113                                 /* in strictsubnets mode do not delete nodes with subnets */
 114                                 node_del(n);
 115                 }
 116         }
 117 }
 118
 119 /*
 120   put all file descriptors in an fd_set array
 121   While we're at it, purge stuff that needs to be removed.
 122 */
 123 static int build_fdset(fd_set *readset, fd_set *writeset) {
 124         avl_node_t *node, *next;
 125         connection_t *c;
 126         int i, max = 0;
 127
 128         FD_ZERO(readset);
 129         FD_ZERO(writeset);
 130
 131         for(node = connection_tree->head; node; node = next) {
 132                 next = node->next;
 133                 c = node->data;
 134
 135                 if(c->status.remove) {
 136                         connection_del(c);
 137                         if(!connection_tree->head)
 138                                 purge();
 139                 } else {
 140                         FD_SET(c->socket, readset);
 141                         if(c->outbuflen > 0 || c->status.connecting)
 142                                 FD_SET(c->socket, writeset);
 143                         if(c->socket > max)
 144                                 max = c->socket;
 145                 }
 146         }
 147
 148         for(i = 0; i < listen_sockets; i++) {
 149                 FD_SET(listen_socket[i].tcp, readset);
 150                 if(listen_socket[i].tcp > max)
 151                         max = listen_socket[i].tcp;
 152                 FD_SET(listen_socket[i].udp, readset);
 153                 if(listen_socket[i].udp > max)
 154                         max = listen_socket[i].udp;
 155         }
 156
 157         if(device_fd >= 0)
 158                 FD_SET(device_fd, readset);
 159         if(device_fd > max)
 160                 max = device_fd;
 161
 162         return max;
 163 }
 164
 165 /*
 166   Terminate a connection:
 167   - Close the socket
 168   - Remove associated edge and tell other connections about it if report = true
 169   - Check if we need to retry making an outgoing connection
 170   - Deactivate the host
 171 */
 172 void terminate_connection(connection_t *c, bool report) {
 173         if(c->status.remove)
 174                 return;
 175
 176         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 177                            c->name, c->hostname);
 178
 179         c->status.remove = true;
 180         c->status.active = false;
 181
 182         if(c->node)
 183                 c->node->connection = NULL;
 184
 185         if(c->socket)
 186                 closesocket(c->socket);
 187
 188         if(c->edge) {
 189                 if(!c->node) {
 190                         logger(LOG_ERR, "Connection to %s (%s) has an edge but node is NULL!", c->name, c->hostname);
 191                         // And that should never happen.
 192                         abort();
 193                 }
 194
 195                 if(report && !tunnelserver)
 196                         send_del_edge(everyone, c->edge);
 197
 198                 edge_del(c->edge);
 199
 200                 /* Run MST and SSSP algorithms */
 201
 202                 graph();
 203
 204                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 205
 206                 if(report && !c->node->status.reachable) {
 207                         edge_t *e;
 208                         e = lookup_edge(c->node, myself);
 209                         if(e) {
 210                                 if(!tunnelserver)
 211                                         send_del_edge(everyone, e);
 212                                 edge_del(e);
 213                         }
 214                 }
 215         }
 216
 217         free_connection_partially(c);
 218
 219         /* Check if this was our outgoing connection */
 220
 221         if(c->outgoing) {
 222                 c->status.remove = false;
 223                 do_outgoing_connection(c);
 224         }
 225
 226 #ifndef HAVE_MINGW
 227         /* Clean up dead proxy processes */
 228
 229         while(waitpid(-1, NULL, WNOHANG) > 0);
 230 #endif
 231 }
 232
 233 /*
 234   Check if the other end is active.
 235   If we have sent packets, but didn't receive any,
 236   then possibly the other end is dead. We send a
 237   PING request over the meta connection. If the other
 238   end does not reply in time, we consider them dead
 239   and close the connection.
 240 */
 241 static void check_dead_connections(void) {
 242         avl_node_t *node, *next;
 243         connection_t *c;
 244
 245         for(node = connection_tree->head; node; node = next) {
 246                 next = node->next;
 247                 c = node->data;
 248
 249                 if(c->last_ping_time + pingtimeout <= now) {
 250                         if(c->status.active) {
 251                                 if(c->status.pinged) {
 252                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 253                                                            c->name, c->hostname, (long)now - c->last_ping_time);
 254                                         c->status.timeout = true;
 255                                         terminate_connection(c, true);
 256                                 } else if(c->last_ping_time + pinginterval <= now) {
 257                                         send_ping(c);
 258                                 }
 259                         } else {
 260                                 if(c->status.remove) {
 261                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 262                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 263                                         connection_del(c);
 264                                         continue;
 265                                 }
 266                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 267                                                    c->name, c->hostname);
 268                                 if(c->status.connecting) {
 269                                         c->status.connecting = false;
 270                                         closesocket(c->socket);
 271                                         do_outgoing_connection(c);
 272                                 } else {
 273                                         terminate_connection(c, false);
 274                                 }
 275                         }
 276                 }
 277
 278                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 279                         if(c->status.active) {
 280                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 281                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 282                                                 c->name, c->hostname, (long)now - c->last_flushed_time, c->outbuflen);
 283                                 c->status.timeout = true;
 284                                 terminate_connection(c, true);
 285                         }
 286                 }
 287         }
 288 }
 289
 290 /*
 291   check all connections to see if anything
 292   happened on their sockets
 293 */
 294 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 295         connection_t *c;
 296         avl_node_t *node;
 297         int result, i;
 298         socklen_t len = sizeof(result);
 299         vpn_packet_t packet;
 300         static int errors = 0;
 301
 302         /* check input from kernel */
 303         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 304                 if(devops.read(&packet)) {
 305                         if(packet.len) {
 306                                 errors = 0;
 307                                 packet.priority = 0;
 308                                 route(myself, &packet);
 309                         }
 310                 } else {
 311                         usleep(errors * 50000);
 312                         errors++;
 313                         if(errors > 10) {
 314                                 logger(LOG_ERR, "Too many errors from %s, exiting!", device);
 315                                 running = false;
 316                         }
 317                 }
 318         }
 319
 320         /* check meta connections */
 321         for(node = connection_tree->head; node; node = node->next) {
 322                 c = node->data;
 323
 324                 if(c->status.remove)
 325                         continue;
 326
 327                 if(FD_ISSET(c->socket, writeset)) {
 328                         if(c->status.connecting) {
 329                                 c->status.connecting = false;
 330                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 331
 332                                 if(!result)
 333                                         finish_connecting(c);
 334                                 else {
 335                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 336                                                            "Error while connecting to %s (%s): %s",
 337                                                            c->name, c->hostname, sockstrerror(result));
 338                                         closesocket(c->socket);
 339                                         do_outgoing_connection(c);
 340                                         continue;
 341                                 }
 342                         }
 343
 344                         if(!flush_meta(c)) {
 345                                 terminate_connection(c, c->status.active);
 346                                 continue;
 347                         }
 348                 }
 349
 350                 if(FD_ISSET(c->socket, readset)) {
 351                         if(!receive_meta(c)) {
 352                                 terminate_connection(c, c->status.active);
 353                                 continue;
 354                         }
 355                 }
 356         }
 357
 358         for(i = 0; i < listen_sockets; i++) {
 359                 if(FD_ISSET(listen_socket[i].udp, readset))
 360                         handle_incoming_vpn_data(i);
 361
 362                 if(FD_ISSET(listen_socket[i].tcp, readset))
 363                         handle_new_meta_connection(listen_socket[i].tcp);
 364         }
 365 }
 366
 367 /*
 368   this is where it all happens...
 369 */
 370 int main_loop(void) {
 371         fd_set readset, writeset;
 372 #ifdef HAVE_PSELECT
 373         struct timespec tv;
 374         sigset_t omask, block_mask;
 375         time_t next_event;
 376 #else
 377         struct timeval tv;
 378 #endif
 379         int r, maxfd;
 380         time_t last_ping_check, last_config_check, last_graph_dump;
 381         event_t *event;
 382
 383         last_ping_check = now;
 384         last_config_check = now;
 385         last_graph_dump = now;
 386
 387         srand(now);
 388
 389 #ifdef HAVE_PSELECT
 390         if(lookup_config(config_tree, "GraphDumpFile"))
 391                 graph_dump = true;
 392         /* Block SIGHUP & SIGALRM */
 393         sigemptyset(&block_mask);
 394         sigaddset(&block_mask, SIGHUP);
 395         sigaddset(&block_mask, SIGALRM);
 396         sigprocmask(SIG_BLOCK, &block_mask, &omask);
 397 #endif
 398
 399         running = true;
 400
 401         while(running) {
 402 #ifdef HAVE_PSELECT
 403                 next_event = last_ping_check + pingtimeout;
 404                 if(graph_dump && next_event > last_graph_dump + 60)
 405                         next_event = last_graph_dump + 60;
 406
 407                 if((event = peek_next_event()) && next_event > event->time)
 408                         next_event = event->time;
 409
 410                 if(next_event <= now)
 411                         tv.tv_sec = 0;
 412                 else
 413                         tv.tv_sec = next_event - now;
 414                 tv.tv_nsec = 0;
 415 #else
 416                 tv.tv_sec = 1;
 417                 tv.tv_usec = 0;
 418 #endif
 419
 420                 maxfd = build_fdset(&readset, &writeset);
 421
 422 #ifdef HAVE_MINGW
 423                 LeaveCriticalSection(&mutex);
 424 #endif
 425 #ifdef HAVE_PSELECT
 426                 r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
 427 #else
 428                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 429 #endif
 430                 now = time(NULL);
 431 #ifdef HAVE_MINGW
 432                 EnterCriticalSection(&mutex);
 433 #endif
 434
 435                 if(r < 0) {
 436                         if(!sockwouldblock(sockerrno)) {
 437                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 438                                 dump_connections();
 439                                 return 1;
 440                         }
 441                 }
 442
 443                 if(r > 0)
 444                         check_network_activity(&readset, &writeset);
 445
 446                 if(do_purge) {
 447                         purge();
 448                         do_purge = false;
 449                 }
 450
 451                 /* Let's check if everybody is still alive */
 452
 453                 if(last_ping_check + pingtimeout <= now) {
 454                         check_dead_connections();
 455                         last_ping_check = now;
 456
 457                         if(routing_mode == RMODE_SWITCH)
 458                                 age_subnets();
 459
 460                         age_past_requests();
 461
 462                         /* Should we regenerate our key? */
 463
 464                         if(keyexpires <= now) {
 465                                 avl_node_t *node;
 466                                 node_t *n;
 467
 468                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 469
 470                                 for(node = node_tree->head; node; node = node->next) {
 471                                         n = node->data;
 472                                         if(n->inkey) {
 473                                                 free(n->inkey);
 474                                                 n->inkey = NULL;
 475                                         }
 476                                 }
 477
 478                                 send_key_changed();
 479                                 keyexpires = now + keylifetime;
 480                         }
 481
 482                         /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
 483                          * two tinc daemons with the same name are on the VPN.
 484                          * If so, sleep a while. If this happens multiple times
 485                          * in a row, sleep longer. */
 486
 487                         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 488                                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 489                                 usleep(sleeptime * 1000000LL);
 490                                 sleeptime *= 2;
 491                                 if(sleeptime < 0)
 492                                         sleeptime = 3600;
 493                         } else {
 494                                 sleeptime /= 2;
 495                                 if(sleeptime < 10)
 496                                         sleeptime = 10;
 497                         }
 498
 499                         contradicting_add_edge = 0;
 500                         contradicting_del_edge = 0;
 501                 }
 502
 503                 if(sigalrm) {
 504                         avl_node_t *node;
 505                         logger(LOG_INFO, "Flushing event queue");
 506                         expire_events();
 507 #ifdef HAVE_DECL_RES_INIT
 508                         res_init();
 509 #endif
 510                         for(node = connection_tree->head; node; node = node->next) {
 511                                 connection_t *c = node->data;
 512                                 if(c->status.active)
 513                                         send_ping(c);
 514                         }
 515                         sigalrm = false;
 516                 }
 517
 518                 while((event = get_expired_event())) {
 519                         event->handler(event->data);
 520                         free_event(event);
 521                 }
 522
 523                 if(sighup) {
 524                         connection_t *c;
 525                         avl_node_t *node, *next;
 526                         char *fname;
 527                         struct stat s;
 528
 529                         sighup = false;
 530
 531                         reopenlogger();
 532
 533                         /* Reread our own configuration file */
 534
 535                         exit_configuration(&config_tree);
 536                         init_configuration(&config_tree);
 537
 538                         if(!read_server_config()) {
 539                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 540                                 return 1;
 541                         }
 542
 543                         /* Cancel non-active outgoing connections */
 544
 545                         for(node = connection_tree->head; node; node = next) {
 546                                 next = node->next;
 547                                 c = node->data;
 548
 549                                 c->outgoing = NULL;
 550
 551                                 if(c->status.connecting) {
 552                                         terminate_connection(c, false);
 553                                         connection_del(c);
 554                                 }
 555                         }
 556
 557                         /* Wipe list of outgoing connections */
 558
 559                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 560                                 outgoing_t *outgoing = node->data;
 561
 562                                 if(outgoing->event)
 563                                         event_del(outgoing->event);
 564                         }
 565
 566                         list_delete_list(outgoing_list);
 567
 568                         /* Close connections to hosts that have a changed or deleted host config file */
 569
 570                         for(node = connection_tree->head; node; node = node->next) {
 571                                 c = node->data;
 572
 573                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 574                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 575                                         terminate_connection(c, c->status.active);
 576                                 free(fname);
 577                         }
 578
 579                         last_config_check = now;
 580
 581                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 582
 583                         if(strictsubnets) {
 584                                 subnet_t *subnet;
 585
 586                                 for(node = subnet_tree->head; node; node = node->next) {
 587                                         subnet = node->data;
 588                                         subnet->expires = 1;
 589                                 }
 590
 591                                 load_all_subnets();
 592
 593                                 for(node = subnet_tree->head; node; node = next) {
 594                                         next = node->next;
 595                                         subnet = node->data;
 596                                         if(subnet->expires == 1) {
 597                                                 send_del_subnet(everyone, subnet);
 598                                                 if(subnet->owner->status.reachable)
 599                                                         subnet_update(subnet->owner, subnet, false);
 600                                                 subnet_del(subnet->owner, subnet);
 601                                         } else if(subnet->expires == -1) {
 602                                                 subnet->expires = 0;
 603                                         } else {
 604                                                 send_add_subnet(everyone, subnet);
 605                                                 if(subnet->owner->status.reachable)
 606                                                         subnet_update(subnet->owner, subnet, true);
 607                                         }
 608                                 }
 609                         }
 610
 611                         /* Try to make outgoing connections */
 612
 613                         try_outgoing_connections();
 614                 }
 615
 616                 /* Dump graph if wanted every 60 seconds*/
 617
 618                 if(last_graph_dump + 60 <= now) {
 619                         dump_graph();
 620                         last_graph_dump = now;
 621                 }
 622         }
 623
 624 #ifdef HAVE_PSELECT
 625         /* Restore SIGHUP & SIGALARM mask */
 626         sigprocmask(SIG_SETMASK, &omask, NULL);
 627 #endif
 628
 629         return 0;
 630 }