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