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