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)
 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
 217 /*
 218   Check if the other end is active.
 219   If we have sent packets, but didn't receive any,
 220   then possibly the other end is dead. We send a
 221   PING request over the meta connection. If the other
 222   end does not reply in time, we consider them dead
 223   and close the connection.
 224 */
 225 static void check_dead_connections(void) {
 226         avl_node_t *node, *next;
 227         connection_t *c;
 228
 229         for(node = connection_tree->head; node; node = next) {
 230                 next = node->next;
 231                 c = node->data;
 232
 233                 if(c->last_ping_time + pingtimeout <= now) {
 234                         if(c->status.active) {
 235                                 if(c->status.pinged) {
 236                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 237                                                            c->name, c->hostname, now - c->last_ping_time);
 238                                         c->status.timeout = true;
 239                                         terminate_connection(c, true);
 240                                 } else if(c->last_ping_time + pinginterval <= now) {
 241                                         send_ping(c);
 242                                 }
 243                         } else {
 244                                 if(c->status.remove) {
 245                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 246                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 247                                         connection_del(c);
 248                                         continue;
 249                                 }
 250                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 251                                                    c->name, c->hostname);
 252                                 if(c->status.connecting) {
 253                                         c->status.connecting = false;
 254                                         closesocket(c->socket);
 255                                         do_outgoing_connection(c);
 256                                 } else {
 257                                         terminate_connection(c, false);
 258                                 }
 259                         }
 260                 }
 261
 262                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 263                         if(c->status.active) {
 264                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 265                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 266                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 267                                 c->status.timeout = true;
 268                                 terminate_connection(c, true);
 269                         }
 270                 }
 271         }
 272 }
 273
 274 /*
 275   check all connections to see if anything
 276   happened on their sockets
 277 */
 278 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 279         connection_t *c;
 280         avl_node_t *node;
 281         int result, i;
 282         socklen_t len = sizeof(result);
 283         vpn_packet_t packet;
 284         static int errors = 0;
 285
 286         /* check input from kernel */
 287         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 288                 if(devops.read(&packet)) {
 289                         if(packet.len) {
 290                                 errors = 0;
 291                                 packet.priority = 0;
 292                                 route(myself, &packet);
 293                         }
 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(i);
 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                         /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
 467                          * two tinc daemons with the same name are on the VPN.
 468                          * If so, sleep a while. If this happens multiple times
 469                          * in a row, sleep longer. */
 470
 471                         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 472                                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 473                                 usleep(sleeptime * 1000000LL);
 474                                 sleeptime *= 2;
 475                                 if(sleeptime < 0)
 476                                         sleeptime = 3600;
 477                         } else {
 478                                 sleeptime /= 2;
 479                                 if(sleeptime < 10)
 480                                         sleeptime = 10;
 481                         }
 482
 483                         contradicting_add_edge = 0;
 484                         contradicting_del_edge = 0;
 485                 }
 486
 487                 if(sigalrm) {
 488                         avl_node_t *node;
 489                         logger(LOG_INFO, "Flushing event queue");
 490                         expire_events();
 491                         for(node = connection_tree->head; node; node = node->next) {
 492                                 connection_t *c = node->data;
 493                                 send_ping(c);
 494                         }
 495                         sigalrm = false;
 496                 }
 497
 498                 while((event = get_expired_event())) {
 499                         event->handler(event->data);
 500                         free_event(event);
 501                 }
 502
 503                 if(sighup) {
 504                         connection_t *c;
 505                         avl_node_t *node, *next;
 506                         char *fname;
 507                         struct stat s;
 508
 509                         sighup = false;
 510
 511                         reopenlogger();
 512
 513                         /* Reread our own configuration file */
 514
 515                         exit_configuration(&config_tree);
 516                         init_configuration(&config_tree);
 517
 518                         if(!read_server_config()) {
 519                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 520                                 return 1;
 521                         }
 522
 523                         /* Cancel non-active outgoing connections */
 524
 525                         for(node = connection_tree->head; node; node = next) {
 526                                 next = node->next;
 527                                 c = node->data;
 528
 529                                 c->outgoing = NULL;
 530
 531                                 if(c->status.connecting) {
 532                                         terminate_connection(c, false);
 533                                         connection_del(c);
 534                                 }
 535                         }
 536
 537                         /* Wipe list of outgoing connections */
 538
 539                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 540                                 outgoing_t *outgoing = node->data;
 541
 542                                 if(outgoing->event)
 543                                         event_del(outgoing->event);
 544                         }
 545
 546                         list_delete_list(outgoing_list);
 547
 548                         /* Close connections to hosts that have a changed or deleted host config file */
 549
 550                         for(node = connection_tree->head; node; node = node->next) {
 551                                 c = node->data;
 552
 553                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 554                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 555                                         terminate_connection(c, c->status.active);
 556                                 free(fname);
 557                         }
 558
 559                         last_config_check = now;
 560
 561                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 562
 563                         if(strictsubnets) {
 564                                 subnet_t *subnet;
 565
 566                                 for(node = subnet_tree->head; node; node = node->next) {
 567                                         subnet = node->data;
 568                                         subnet->expires = 1;
 569                                 }
 570
 571                                 load_all_subnets();
 572
 573                                 for(node = subnet_tree->head; node; node = next) {
 574                                         next = node->next;
 575                                         subnet = node->data;
 576                                         if(subnet->expires == 1) {
 577                                                 send_del_subnet(everyone, subnet);
 578                                                 if(subnet->owner->status.reachable)
 579                                                         subnet_update(subnet->owner, subnet, false);
 580                                                 subnet_del(subnet->owner, subnet);
 581                                         } else if(subnet->expires == -1) {
 582                                                 subnet->expires = 0;
 583                                         } else {
 584                                                 send_add_subnet(everyone, subnet);
 585                                                 if(subnet->owner->status.reachable)
 586                                                         subnet_update(subnet->owner, subnet, true);
 587                                         }
 588                                 }
 589                         }
 590
 591                         /* Try to make outgoing connections */
 592
 593                         try_outgoing_connections();
 594                 }
 595
 596                 /* Dump graph if wanted every 60 seconds*/
 597
 598                 if(last_graph_dump + 60 <= now) {
 599                         dump_graph();
 600                         last_graph_dump = now;
 601                 }
 602         }
 603
 604 #ifdef HAVE_PSELECT
 605         /* Restore SIGHUP & SIGALARM mask */
 606         sigprocmask(SIG_SETMASK, &omask, NULL);
 607 #endif
 608
 609         return 0;
 610 }