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