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                   2000-2014 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_ARPA_NAMESER_H
  45 #include <arpa/nameser.h>
  46 #endif
  47
  48 #ifdef HAVE_RESOLV_H
  49 #include <resolv.h>
  50 #endif
  51
  52 bool do_purge = false;
  53 volatile bool running = false;
  54 #ifdef HAVE_PSELECT
  55 bool graph_dump = false;
  56 #endif
  57
  58 time_t now = 0;
  59 int contradicting_add_edge = 0;
  60 int contradicting_del_edge = 0;
  61 static int sleeptime = 10;
  62
  63 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  64
  65 static void purge(void) {
  66         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  67         node_t *n;
  68         edge_t *e;
  69         subnet_t *s;
  70
  71         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
  72
  73         /* Remove all edges and subnets owned by unreachable nodes. */
  74
  75         for(nnode = node_tree->head; nnode; nnode = nnext) {
  76                 nnext = nnode->next;
  77                 n = nnode->data;
  78
  79                 if(!n->status.reachable) {
  80                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
  81                                            n->hostname);
  82
  83                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  84                                 snext = snode->next;
  85                                 s = snode->data;
  86                                 send_del_subnet(everyone, s);
  87                                 if(!strictsubnets)
  88                                         subnet_del(n, s);
  89                         }
  90
  91                         for(enode = n->edge_tree->head; enode; enode = enext) {
  92                                 enext = enode->next;
  93                                 e = enode->data;
  94                                 if(!tunnelserver)
  95                                         send_del_edge(everyone, e);
  96                                 edge_del(e);
  97                         }
  98                 }
  99         }
 100
 101         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
 102
 103         for(nnode = node_tree->head; nnode; nnode = nnext) {
 104                 nnext = nnode->next;
 105                 n = nnode->data;
 106
 107                 if(!n->status.reachable) {
 108                         for(enode = edge_weight_tree->head; enode; enode = enext) {
 109                                 enext = enode->next;
 110                                 e = enode->data;
 111
 112                                 if(e->to == n)
 113                                         break;
 114                         }
 115
 116                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
 117                                 /* in strictsubnets mode do not delete nodes with subnets */
 118                                 node_del(n);
 119                 }
 120         }
 121 }
 122
 123 /*
 124   put all file descriptors in an fd_set array
 125   While we're at it, purge stuff that needs to be removed.
 126 */
 127 static int build_fdset(fd_set *readset, fd_set *writeset) {
 128         avl_node_t *node, *next;
 129         connection_t *c;
 130         int i, max = 0;
 131
 132         FD_ZERO(readset);
 133         FD_ZERO(writeset);
 134
 135         for(node = connection_tree->head; node; node = next) {
 136                 next = node->next;
 137                 c = node->data;
 138
 139                 if(c->status.remove) {
 140                         connection_del(c);
 141                         if(!connection_tree->head)
 142                                 purge();
 143                 } else {
 144                         FD_SET(c->socket, readset);
 145                         if(c->outbuflen > 0 || c->status.connecting)
 146                                 FD_SET(c->socket, writeset);
 147                         if(c->socket > max)
 148                                 max = c->socket;
 149                 }
 150         }
 151
 152         for(i = 0; i < listen_sockets; i++) {
 153                 FD_SET(listen_socket[i].tcp, readset);
 154                 if(listen_socket[i].tcp > max)
 155                         max = listen_socket[i].tcp;
 156                 FD_SET(listen_socket[i].udp, readset);
 157                 if(listen_socket[i].udp > max)
 158                         max = listen_socket[i].udp;
 159         }
 160
 161         if(device_fd >= 0)
 162                 FD_SET(device_fd, readset);
 163         if(device_fd > max)
 164                 max = device_fd;
 165
 166         return max;
 167 }
 168
 169 /*
 170   Terminate a connection:
 171   - Close the socket
 172   - Remove associated edge and tell other connections about it if report = true
 173   - Check if we need to retry making an outgoing connection
 174   - Deactivate the host
 175 */
 176 void terminate_connection(connection_t *c, bool report) {
 177         if(c->status.remove)
 178                 return;
 179
 180         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 181                            c->name, c->hostname);
 182
 183         c->status.remove = true;
 184         c->status.active = false;
 185
 186         if(c->node)
 187                 c->node->connection = NULL;
 188
 189         if(c->socket)
 190                 closesocket(c->socket);
 191
 192         if(c->edge) {
 193                 if(!c->node) {
 194                         logger(LOG_ERR, "Connection to %s (%s) has an edge but node is NULL!", c->name, c->hostname);
 195                         // And that should never happen.
 196                         abort();
 197                 }
 198
 199                 if(report && !tunnelserver)
 200                         send_del_edge(everyone, c->edge);
 201
 202                 edge_del(c->edge);
 203
 204                 /* Run MST and SSSP algorithms */
 205
 206                 graph();
 207
 208                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 209
 210                 if(report && !c->node->status.reachable) {
 211                         edge_t *e;
 212                         e = lookup_edge(c->node, myself);
 213                         if(e) {
 214                                 if(!tunnelserver)
 215                                         send_del_edge(everyone, e);
 216                                 edge_del(e);
 217                         }
 218                 }
 219         }
 220
 221         free_connection_partially(c);
 222
 223         /* Check if this was our outgoing connection */
 224
 225         if(c->outgoing) {
 226                 c->status.remove = false;
 227                 do_outgoing_connection(c);
 228         }
 229
 230 #ifndef HAVE_MINGW
 231         /* Clean up dead proxy processes */
 232
 233         while(waitpid(-1, NULL, WNOHANG) > 0);
 234 #endif
 235 }
 236
 237 /*
 238   Check if the other end is active.
 239   If we have sent packets, but didn't receive any,
 240   then possibly the other end is dead. We send a
 241   PING request over the meta connection. If the other
 242   end does not reply in time, we consider them dead
 243   and close the connection.
 244 */
 245 static void check_dead_connections(void) {
 246         avl_node_t *node, *next;
 247         connection_t *c;
 248
 249         for(node = connection_tree->head; node; node = next) {
 250                 next = node->next;
 251                 c = node->data;
 252
 253                 if(c->last_ping_time + pingtimeout <= now) {
 254                         if(c->status.active) {
 255                                 if(c->status.pinged) {
 256                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 257                                                            c->name, c->hostname, (long)now - c->last_ping_time);
 258                                         c->status.timeout = true;
 259                                         terminate_connection(c, true);
 260                                 } else if(c->last_ping_time + pinginterval <= now) {
 261                                         send_ping(c);
 262                                 }
 263                         } else {
 264                                 if(c->status.remove) {
 265                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 266                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 267                                         connection_del(c);
 268                                         continue;
 269                                 }
 270                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 271                                                    c->name, c->hostname);
 272                                 if(c->status.connecting) {
 273                                         c->status.connecting = false;
 274                                         closesocket(c->socket);
 275                                         do_outgoing_connection(c);
 276                                 } else {
 277                                         terminate_connection(c, false);
 278                                 }
 279                         }
 280                 }
 281
 282                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 283                         if(c->status.active) {
 284                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 285                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 286                                                 c->name, c->hostname, (long)now - c->last_flushed_time, c->outbuflen);
 287                                 c->status.timeout = true;
 288                                 terminate_connection(c, true);
 289                         }
 290                 }
 291         }
 292 }
 293
 294 /*
 295   check all connections to see if anything
 296   happened on their sockets
 297 */
 298 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 299         connection_t *c;
 300         avl_node_t *node;
 301         int result, i;
 302         socklen_t len = sizeof(result);
 303         vpn_packet_t packet;
 304         static int errors = 0;
 305
 306         /* check input from kernel */
 307         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 308                 if(devops.read(&packet)) {
 309                         if(packet.len) {
 310                                 errors = 0;
 311                                 packet.priority = 0;
 312                                 route(myself, &packet);
 313                         }
 314                 } else {
 315                         usleep(errors * 50000);
 316                         errors++;
 317                         if(errors > 10) {
 318                                 logger(LOG_ERR, "Too many errors from %s, exiting!", device);
 319                                 running = false;
 320                         }
 321                 }
 322         }
 323
 324         /* check meta connections */
 325         for(node = connection_tree->head; node; node = node->next) {
 326                 c = node->data;
 327
 328                 if(c->status.remove)
 329                         continue;
 330
 331                 if(FD_ISSET(c->socket, writeset)) {
 332                         if(c->status.connecting) {
 333                                 c->status.connecting = false;
 334                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 335
 336                                 if(!result)
 337                                         finish_connecting(c);
 338                                 else {
 339                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 340                                                            "Error while connecting to %s (%s): %s",
 341                                                            c->name, c->hostname, sockstrerror(result));
 342                                         closesocket(c->socket);
 343                                         do_outgoing_connection(c);
 344                                         continue;
 345                                 }
 346                         }
 347
 348                         if(!flush_meta(c)) {
 349                                 terminate_connection(c, c->status.active);
 350                                 continue;
 351                         }
 352                 }
 353
 354                 if(FD_ISSET(c->socket, readset)) {
 355                         if(!receive_meta(c)) {
 356                                 terminate_connection(c, c->status.active);
 357                                 continue;
 358                         }
 359                 }
 360         }
 361
 362         for(i = 0; i < listen_sockets; i++) {
 363                 if(FD_ISSET(listen_socket[i].udp, readset))
 364                         handle_incoming_vpn_data(i);
 365
 366                 if(FD_ISSET(listen_socket[i].tcp, readset))
 367                         handle_new_meta_connection(listen_socket[i].tcp);
 368         }
 369 }
 370
 371 /*
 372   this is where it all happens...
 373 */
 374 int main_loop(void) {
 375         fd_set readset, writeset;
 376 #ifdef HAVE_PSELECT
 377         struct timespec tv;
 378         sigset_t omask, block_mask;
 379         time_t next_event;
 380 #else
 381         struct timeval tv;
 382 #endif
 383         int r, maxfd;
 384         time_t last_ping_check, last_config_check, last_graph_dump;
 385         event_t *event;
 386
 387         last_ping_check = now;
 388         last_config_check = now;
 389         last_graph_dump = now;
 390
 391         srand(now);
 392
 393 #ifdef HAVE_PSELECT
 394         if(lookup_config(config_tree, "GraphDumpFile"))
 395                 graph_dump = true;
 396         /* Block SIGHUP & SIGALRM */
 397         sigemptyset(&block_mask);
 398         sigaddset(&block_mask, SIGHUP);
 399         sigaddset(&block_mask, SIGALRM);
 400         sigprocmask(SIG_BLOCK, &block_mask, &omask);
 401 #endif
 402
 403         running = true;
 404
 405         while(running) {
 406 #ifdef HAVE_PSELECT
 407                 next_event = last_ping_check + pingtimeout;
 408                 if(graph_dump && next_event > last_graph_dump + 60)
 409                         next_event = last_graph_dump + 60;
 410
 411                 if((event = peek_next_event()) && next_event > event->time)
 412                         next_event = event->time;
 413
 414                 if(next_event <= now)
 415                         tv.tv_sec = 0;
 416                 else
 417                         tv.tv_sec = next_event - now;
 418                 tv.tv_nsec = 0;
 419 #else
 420                 tv.tv_sec = 1;
 421                 tv.tv_usec = 0;
 422 #endif
 423
 424                 maxfd = build_fdset(&readset, &writeset);
 425
 426 #ifdef HAVE_MINGW
 427                 LeaveCriticalSection(&mutex);
 428 #endif
 429 #ifdef HAVE_PSELECT
 430                 r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
 431 #else
 432                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 433 #endif
 434                 now = time(NULL);
 435 #ifdef HAVE_MINGW
 436                 EnterCriticalSection(&mutex);
 437 #endif
 438
 439                 if(r < 0) {
 440                         if(!sockwouldblock(sockerrno)) {
 441                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 442                                 dump_connections();
 443                                 return 1;
 444                         }
 445                 }
 446
 447                 if(r > 0)
 448                         check_network_activity(&readset, &writeset);
 449
 450                 if(do_purge) {
 451                         purge();
 452                         do_purge = false;
 453                 }
 454
 455                 /* Let's check if everybody is still alive */
 456
 457                 if(last_ping_check + pingtimeout <= now) {
 458                         check_dead_connections();
 459                         last_ping_check = now;
 460
 461                         if(routing_mode == RMODE_SWITCH)
 462                                 age_subnets();
 463
 464                         age_past_requests();
 465
 466                         /* Should we regenerate our key? */
 467
 468                         if(keyexpires <= now) {
 469                                 avl_node_t *node;
 470                                 node_t *n;
 471
 472                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 473
 474                                 for(node = node_tree->head; node; node = node->next) {
 475                                         n = node->data;
 476                                         if(n->inkey) {
 477                                                 free(n->inkey);
 478                                                 n->inkey = NULL;
 479                                         }
 480                                 }
 481
 482                                 send_key_changed();
 483                                 keyexpires = now + keylifetime;
 484                         }
 485
 486                         /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
 487                          * two tinc daemons with the same name are on the VPN.
 488                          * If so, sleep a while. If this happens multiple times
 489                          * in a row, sleep longer. */
 490
 491                         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 492                                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 493                                 usleep(sleeptime * 1000000LL);
 494                                 sleeptime *= 2;
 495                                 if(sleeptime < 0)
 496                                         sleeptime = 3600;
 497                         } else {
 498                                 sleeptime /= 2;
 499                                 if(sleeptime < 10)
 500                                         sleeptime = 10;
 501                         }
 502
 503                         contradicting_add_edge = 0;
 504                         contradicting_del_edge = 0;
 505                 }
 506
 507                 if(sigalrm) {
 508                         avl_node_t *node;
 509                         logger(LOG_INFO, "Flushing event queue");
 510                         expire_events();
 511 #if HAVE_DECL_RES_INIT
 512                         res_init();
 513 #endif
 514                         for(node = connection_tree->head; node; node = node->next) {
 515                                 connection_t *c = node->data;
 516                                 if(c->status.active)
 517                                         send_ping(c);
 518                         }
 519                         sigalrm = false;
 520                 }
 521
 522                 while((event = get_expired_event())) {
 523                         event->handler(event->data);
 524                         free_event(event);
 525                 }
 526
 527                 if(sighup) {
 528                         connection_t *c;
 529                         avl_node_t *node, *next;
 530                         char *fname;
 531                         struct stat s;
 532
 533                         sighup = false;
 534
 535                         reopenlogger();
 536
 537                         /* Reread our own configuration file */
 538
 539                         exit_configuration(&config_tree);
 540                         init_configuration(&config_tree);
 541
 542                         if(!read_server_config()) {
 543                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 544                                 return 1;
 545                         }
 546
 547                         /* Cancel non-active outgoing connections */
 548
 549                         for(node = connection_tree->head; node; node = next) {
 550                                 next = node->next;
 551                                 c = node->data;
 552
 553                                 c->outgoing = NULL;
 554
 555                                 if(c->status.connecting) {
 556                                         terminate_connection(c, false);
 557                                         connection_del(c);
 558                                 }
 559                         }
 560
 561                         /* Wipe list of outgoing connections */
 562
 563                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 564                                 outgoing_t *outgoing = node->data;
 565
 566                                 if(outgoing->event)
 567                                         event_del(outgoing->event);
 568                         }
 569
 570                         list_delete_list(outgoing_list);
 571
 572                         /* Close connections to hosts that have a changed or deleted host config file */
 573
 574                         for(node = connection_tree->head; node; node = node->next) {
 575                                 c = node->data;
 576
 577                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 578                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 579                                         terminate_connection(c, c->status.active);
 580                                 free(fname);
 581                         }
 582
 583                         last_config_check = now;
 584
 585                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 586
 587                         if(strictsubnets) {
 588                                 subnet_t *subnet;
 589
 590                                 for(node = subnet_tree->head; node; node = node->next) {
 591                                         subnet = node->data;
 592                                         subnet->expires = 1;
 593                                 }
 594
 595                                 load_all_subnets();
 596
 597                                 for(node = subnet_tree->head; node; node = next) {
 598                                         next = node->next;
 599                                         subnet = node->data;
 600                                         if(subnet->expires == 1) {
 601                                                 send_del_subnet(everyone, subnet);
 602                                                 if(subnet->owner->status.reachable)
 603                                                         subnet_update(subnet->owner, subnet, false);
 604                                                 subnet_del(subnet->owner, subnet);
 605                                         } else if(subnet->expires == -1) {
 606                                                 subnet->expires = 0;
 607                                         } else {
 608                                                 send_add_subnet(everyone, subnet);
 609                                                 if(subnet->owner->status.reachable)
 610                                                         subnet_update(subnet->owner, subnet, true);
 611                                         }
 612                                 }
 613                         }
 614
 615                         /* Try to make outgoing connections */
 616
 617                         try_outgoing_connections();
 618                 }
 619
 620                 /* Dump graph if wanted every 60 seconds*/
 621
 622                 if(last_graph_dump + 60 <= now) {
 623                         dump_graph();
 624                         last_graph_dump = now;
 625                 }
 626         }
 627
 628 #ifdef HAVE_PSELECT
 629         /* Restore SIGHUP & SIGALARM mask */
 630         sigprocmask(SIG_SETMASK, &omask, NULL);
 631 #endif
 632
 633         return 0;
 634 }