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                   2000-2011 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License along
  18     with this program; if not, write to the Free Software Foundation, Inc.,
  19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20 */
  21
  22 #include "system.h"
  23
  24 #include <openssl/rand.h>
  25
  26 #include "utils.h"
  27 #include "avl_tree.h"
  28 #include "conf.h"
  29 #include "connection.h"
  30 #include "device.h"
  31 #include "event.h"
  32 #include "graph.h"
  33 #include "logger.h"
  34 #include "meta.h"
  35 #include "net.h"
  36 #include "netutl.h"
  37 #include "process.h"
  38 #include "protocol.h"
  39 #include "route.h"
  40 #include "subnet.h"
  41 #include "xalloc.h"
  42
  43 bool do_purge = false;
  44 volatile bool running = false;
  45 #ifdef HAVE_PSELECT
  46 bool graph_dump = false;
  47 #endif
  48
  49 time_t now = 0;
  50 int contradicting_add_edge = 0;
  51 int contradicting_del_edge = 0;
  52
  53 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  54
  55 static void purge(void) {
  56         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  57         node_t *n;
  58         edge_t *e;
  59         subnet_t *s;
  60
  61         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
  62
  63         /* Remove all edges and subnets owned by unreachable nodes. */
  64
  65         for(nnode = node_tree->head; nnode; nnode = nnext) {
  66                 nnext = nnode->next;
  67                 n = nnode->data;
  68
  69                 if(!n->status.reachable) {
  70                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
  71                                            n->hostname);
  72
  73                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  74                                 snext = snode->next;
  75                                 s = snode->data;
  76                                 send_del_subnet(broadcast, s);
  77                                 if(!strictsubnets)
  78                                         subnet_del(n, s);
  79                         }
  80
  81                         for(enode = n->edge_tree->head; enode; enode = enext) {
  82                                 enext = enode->next;
  83                                 e = enode->data;
  84                                 if(!tunnelserver)
  85                                         send_del_edge(broadcast, e);
  86                                 edge_del(e);
  87                         }
  88                 }
  89         }
  90
  91         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  92
  93         for(nnode = node_tree->head; nnode; nnode = nnext) {
  94                 nnext = nnode->next;
  95                 n = nnode->data;
  96
  97                 if(!n->status.reachable) {
  98                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  99                                 enext = enode->next;
 100                                 e = enode->data;
 101
 102                                 if(e->to == n)
 103                                         break;
 104                         }
 105
 106                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
 107                                 /* in strictsubnets mode do not delete nodes with subnets */
 108                                 node_del(n);
 109                 }
 110         }
 111 }
 112
 113 /*
 114   put all file descriptors in an fd_set array
 115   While we're at it, purge stuff that needs to be removed.
 116 */
 117 static int build_fdset(fd_set *readset, fd_set *writeset) {
 118         avl_node_t *node, *next;
 119         connection_t *c;
 120         int i, max = 0;
 121
 122         FD_ZERO(readset);
 123         FD_ZERO(writeset);
 124
 125         for(node = connection_tree->head; node; node = next) {
 126                 next = node->next;
 127                 c = node->data;
 128
 129                 if(c->status.remove) {
 130                         connection_del(c);
 131                         if(!connection_tree->head)
 132                                 purge();
 133                 } else {
 134                         FD_SET(c->socket, readset);
 135                         if(c->outbuflen > 0)
 136                                 FD_SET(c->socket, writeset);
 137                         if(c->socket > max)
 138                                 max = c->socket;
 139                 }
 140         }
 141
 142         for(i = 0; i < listen_sockets; i++) {
 143                 FD_SET(listen_socket[i].tcp, readset);
 144                 if(listen_socket[i].tcp > max)
 145                         max = listen_socket[i].tcp;
 146                 FD_SET(listen_socket[i].udp, readset);
 147                 if(listen_socket[i].udp > max)
 148                         max = listen_socket[i].udp;
 149         }
 150
 151         if(device_fd >= 0)
 152                 FD_SET(device_fd, readset);
 153         if(device_fd > max)
 154                 max = device_fd;
 155
 156         return max;
 157 }
 158
 159 /*
 160   Terminate a connection:
 161   - Close the socket
 162   - Remove associated edge and tell other connections about it if report = true
 163   - Check if we need to retry making an outgoing connection
 164   - Deactivate the host
 165 */
 166 void terminate_connection(connection_t *c, bool report) {
 167         if(c->status.remove)
 168                 return;
 169
 170         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 171                            c->name, c->hostname);
 172
 173         c->status.remove = true;
 174         c->status.active = false;
 175
 176         if(c->node)
 177                 c->node->connection = NULL;
 178
 179         if(c->socket)
 180                 closesocket(c->socket);
 181
 182         if(c->edge) {
 183                 if(report && !tunnelserver)
 184                         send_del_edge(broadcast, c->edge);
 185
 186                 edge_del(c->edge);
 187
 188                 /* Run MST and SSSP algorithms */
 189
 190                 graph();
 191
 192                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 193
 194                 if(report && !c->node->status.reachable) {
 195                         edge_t *e;
 196                         e = lookup_edge(c->node, myself);
 197                         if(e) {
 198                                 if(!tunnelserver)
 199                                         send_del_edge(broadcast, e);
 200                                 edge_del(e);
 201                         }
 202                 }
 203         }
 204
 205         /* Check if this was our outgoing connection */
 206
 207         if(c->outgoing) {
 208                 retry_outgoing(c->outgoing);
 209                 c->outgoing = NULL;
 210         }
 211
 212         free(c->outbuf);
 213         c->outbuf = NULL;
 214         c->outbuflen = 0;
 215         c->outbufsize = 0;
 216         c->outbufstart = 0;
 217 }
 218
 219 /*
 220   Check if the other end is active.
 221   If we have sent packets, but didn't receive any,
 222   then possibly the other end is dead. We send a
 223   PING request over the meta connection. If the other
 224   end does not reply in time, we consider them dead
 225   and close the connection.
 226 */
 227 static void check_dead_connections(void) {
 228         avl_node_t *node, *next;
 229         connection_t *c;
 230
 231         for(node = connection_tree->head; node; node = next) {
 232                 next = node->next;
 233                 c = node->data;
 234
 235                 if(c->last_ping_time + pingtimeout <= now) {
 236                         if(c->status.active) {
 237                                 if(c->status.pinged) {
 238                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 239                                                            c->name, c->hostname, now - c->last_ping_time);
 240                                         c->status.timeout = true;
 241                                         terminate_connection(c, true);
 242                                 } else if(c->last_ping_time + pinginterval <= now) {
 243                                         send_ping(c);
 244                                 }
 245                         } else {
 246                                 if(c->status.remove) {
 247                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 248                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 249                                         connection_del(c);
 250                                         continue;
 251                                 }
 252                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 253                                                    c->name, c->hostname);
 254                                 if(c->status.connecting) {
 255                                         c->status.connecting = false;
 256                                         closesocket(c->socket);
 257                                         do_outgoing_connection(c);
 258                                 } else {
 259                                         terminate_connection(c, false);
 260                                 }
 261                         }
 262                 }
 263
 264                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 265                         if(c->status.active) {
 266                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 267                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 268                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 269                                 c->status.timeout = true;
 270                                 terminate_connection(c, true);
 271                         }
 272                 }
 273         }
 274 }
 275
 276 /*
 277   check all connections to see if anything
 278   happened on their sockets
 279 */
 280 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 281         connection_t *c;
 282         avl_node_t *node;
 283         int result, i;
 284         socklen_t len = sizeof(result);
 285         vpn_packet_t packet;
 286         static int errors = 0;
 287
 288         /* check input from kernel */
 289         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 290                 if(read_packet(&packet)) {
 291                         errors = 0;
 292                         packet.priority = 0;
 293                         route(myself, &packet);
 294                 } else {
 295                         usleep(errors * 50000);
 296                         errors++;
 297                         if(errors > 10) {
 298                                 logger(LOG_ERR, "Too many errors from %s, exiting!", device);
 299                                 running = false;
 300                         }
 301                 }
 302         }
 303
 304         /* check meta connections */
 305         for(node = connection_tree->head; node; node = node->next) {
 306                 c = node->data;
 307
 308                 if(c->status.remove)
 309                         continue;
 310
 311                 if(FD_ISSET(c->socket, readset)) {
 312                         if(c->status.connecting) {
 313                                 c->status.connecting = false;
 314                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 315
 316                                 if(!result)
 317                                         finish_connecting(c);
 318                                 else {
 319                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 320                                                            "Error while connecting to %s (%s): %s",
 321                                                            c->name, c->hostname, sockstrerror(result));
 322                                         closesocket(c->socket);
 323                                         do_outgoing_connection(c);
 324                                         continue;
 325                                 }
 326                         }
 327
 328                         if(!receive_meta(c)) {
 329                                 terminate_connection(c, c->status.active);
 330                                 continue;
 331                         }
 332                 }
 333
 334                 if(FD_ISSET(c->socket, writeset)) {
 335                         if(!flush_meta(c)) {
 336                                 terminate_connection(c, c->status.active);
 337                                 continue;
 338                         }
 339                 }
 340         }
 341
 342         for(i = 0; i < listen_sockets; i++) {
 343                 if(FD_ISSET(listen_socket[i].udp, readset))
 344                         handle_incoming_vpn_data(listen_socket[i].udp);
 345
 346                 if(FD_ISSET(listen_socket[i].tcp, readset))
 347                         handle_new_meta_connection(listen_socket[i].tcp);
 348         }
 349 }
 350
 351 /*
 352   this is where it all happens...
 353 */
 354 int main_loop(void) {
 355         fd_set readset, writeset;
 356 #ifdef HAVE_PSELECT
 357         struct timespec tv;
 358         sigset_t omask, block_mask;
 359         time_t next_event;
 360 #else
 361         struct timeval tv;
 362 #endif
 363         int r, maxfd;
 364         time_t last_ping_check, last_config_check, last_graph_dump;
 365         event_t *event;
 366
 367         last_ping_check = now;
 368         last_config_check = now;
 369         last_graph_dump = now;
 370
 371         srand(now);
 372
 373 #ifdef HAVE_PSELECT
 374         if(lookup_config(config_tree, "GraphDumpFile"))
 375                 graph_dump = true;
 376         /* Block SIGHUP & SIGALRM */
 377         sigemptyset(&block_mask);
 378         sigaddset(&block_mask, SIGHUP);
 379         sigaddset(&block_mask, SIGALRM);
 380         sigprocmask(SIG_BLOCK, &block_mask, &omask);
 381 #endif
 382
 383         running = true;
 384
 385         while(running) {
 386 #ifdef HAVE_PSELECT
 387                 next_event = last_ping_check + pingtimeout;
 388                 if(graph_dump && next_event > last_graph_dump + 60)
 389                         next_event = last_graph_dump + 60;
 390
 391                 if((event = peek_next_event()) && next_event > event->time)
 392                         next_event = event->time;
 393
 394                 if(next_event <= now)
 395                         tv.tv_sec = 0;
 396                 else
 397                         tv.tv_sec = next_event - now;
 398                 tv.tv_nsec = 0;
 399 #else
 400                 tv.tv_sec = 1;
 401                 tv.tv_usec = 0;
 402 #endif
 403
 404                 maxfd = build_fdset(&readset, &writeset);
 405
 406 #ifdef HAVE_MINGW
 407                 LeaveCriticalSection(&mutex);
 408 #endif
 409 #ifdef HAVE_PSELECT
 410                 r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
 411 #else
 412                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 413 #endif
 414                 now = time(NULL);
 415 #ifdef HAVE_MINGW
 416                 EnterCriticalSection(&mutex);
 417 #endif
 418
 419                 if(r < 0) {
 420                         if(!sockwouldblock(sockerrno)) {
 421                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 422                                 dump_connections();
 423                                 return 1;
 424                         }
 425                 }
 426
 427                 if(r > 0)
 428                         check_network_activity(&readset, &writeset);
 429
 430                 if(do_purge) {
 431                         purge();
 432                         do_purge = false;
 433                 }
 434
 435                 /* Let's check if everybody is still alive */
 436
 437                 if(last_ping_check + pingtimeout <= now) {
 438                         check_dead_connections();
 439                         last_ping_check = now;
 440
 441                         if(routing_mode == RMODE_SWITCH)
 442                                 age_subnets();
 443
 444                         age_past_requests();
 445
 446                         /* Should we regenerate our key? */
 447
 448                         if(keyexpires <= now) {
 449                                 avl_node_t *node;
 450                                 node_t *n;
 451
 452                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 453
 454                                 for(node = node_tree->head; node; node = node->next) {
 455                                         n = node->data;
 456                                         if(n->inkey) {
 457                                                 free(n->inkey);
 458                                                 n->inkey = NULL;
 459                                         }
 460                                 }
 461
 462                                 send_key_changed();
 463                                 keyexpires = now + keylifetime;
 464                         }
 465
 466                         if(contradicting_del_edge > 10 && contradicting_add_edge > 10) {
 467                                 logger(LOG_WARNING, "Possible node with same Name as us!");
 468
 469                                 if(rand() % 3 == 0) {
 470                                         logger(LOG_ERR, "Shutting down, check configuration of all nodes for duplicate Names!");
 471                                         running = false;
 472                                         break;
 473                                 }
 474
 475                                 contradicting_add_edge = 0;
 476                                 contradicting_del_edge = 0;
 477                         }
 478                 }
 479
 480                 if(sigalrm) {
 481                         avl_node_t *node;
 482                         logger(LOG_INFO, "Flushing event queue");
 483                         expire_events();
 484                         for(node = connection_tree->head; node; node = node->next) {
 485                                 connection_t *c = node->data;
 486                                 send_ping(c);
 487                         }
 488                         sigalrm = false;
 489                 }
 490
 491                 while((event = get_expired_event())) {
 492                         event->handler(event->data);
 493                         free_event(event);
 494                 }
 495
 496                 if(sighup) {
 497                         connection_t *c;
 498                         avl_node_t *node, *next;
 499                         char *fname;
 500                         struct stat s;
 501
 502                         sighup = false;
 503
 504                         /* Reread our own configuration file */
 505
 506                         exit_configuration(&config_tree);
 507                         init_configuration(&config_tree);
 508
 509                         if(!read_server_config()) {
 510                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 511                                 return 1;
 512                         }
 513
 514                         /* Cancel non-active outgoing connections */
 515
 516                         for(node = connection_tree->head; node; node = next) {
 517                                 next = node->next;
 518                                 c = node->data;
 519
 520                                 c->outgoing = NULL;
 521
 522                                 if(c->status.connecting) {
 523                                         terminate_connection(c, false);
 524                                         connection_del(c);
 525                                 }
 526                         }
 527
 528                         /* Wipe list of outgoing connections */
 529
 530                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 531                                 outgoing_t *outgoing = node->data;
 532
 533                                 if(outgoing->event)
 534                                         event_del(outgoing->event);
 535                         }
 536
 537                         list_delete_list(outgoing_list);
 538
 539                         /* Close connections to hosts that have a changed or deleted host config file */
 540
 541                         for(node = connection_tree->head; node; node = node->next) {
 542                                 c = node->data;
 543
 544                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 545                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 546                                         terminate_connection(c, c->status.active);
 547                                 free(fname);
 548                         }
 549
 550                         last_config_check = now;
 551
 552                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 553
 554                         if(strictsubnets) {
 555                                 subnet_t *subnet;
 556
 557                                 for(node = subnet_tree->head; node; node = node->next) {
 558                                         subnet = node->data;
 559                                         subnet->expires = 1;
 560                                 }
 561
 562                                 load_all_subnets();
 563
 564                                 for(node = subnet_tree->head; node; node = next) {
 565                                         next = node->next;
 566                                         subnet = node->data;
 567                                         if(subnet->expires == 1) {
 568                                                 send_del_subnet(broadcast, subnet);
 569                                                 if(subnet->owner->status.reachable)
 570                                                         subnet_update(subnet->owner, subnet, false);
 571                                                 subnet_del(subnet->owner, subnet);
 572                                         } else if(subnet->expires == -1) {
 573                                                 subnet->expires = 0;
 574                                         } else {
 575                                                 send_add_subnet(broadcast, subnet);
 576                                                 if(subnet->owner->status.reachable)
 577                                                         subnet_update(subnet->owner, subnet, true);
 578                                         }
 579                                 }
 580                         }
 581
 582                         /* Try to make outgoing connections */
 583
 584                         try_outgoing_connections();
 585                 }
 586
 587                 /* Dump graph if wanted every 60 seconds*/
 588
 589                 if(last_graph_dump + 60 <= now) {
 590                         dump_graph();
 591                         last_graph_dump = now;
 592                 }
 593         }
 594
 595 #ifdef HAVE_PSELECT
 596         /* Restore SIGHUP & SIGALARM mask */
 597         sigprocmask(SIG_SETMASK, &omask, NULL);
 598 #endif
 599
 600         return 0;
 601 }