src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2015 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
  80                                 if(!strictsubnets) {
  81                                         subnet_del(n, s);
  82                                 }
  83                         }
  84
  85                         for(enode = n->edge_tree->head; enode; enode = enext) {
  86                                 enext = enode->next;
  87                                 e = enode->data;
  88
  89                                 if(!tunnelserver) {
  90                                         send_del_edge(everyone, e);
  91                                 }
  92
  93                                 edge_del(e);
  94                         }
  95                 }
  96         }
  97
  98         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  99
 100         for(nnode = node_tree->head; nnode; nnode = nnext) {
 101                 nnext = nnode->next;
 102                 n = nnode->data;
 103
 104                 if(!n->status.reachable) {
 105                         for(enode = edge_weight_tree->head; enode; enode = enext) {
 106                                 enext = enode->next;
 107                                 e = enode->data;
 108
 109                                 if(e->to == n) {
 110                                         break;
 111                                 }
 112                         }
 113
 114                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
 115                                 /* in strictsubnets mode do not delete nodes with subnets */
 116                         {
 117                                 node_del(n);
 118                         }
 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
 142                         if(!connection_tree->head) {
 143                                 purge();
 144                         }
 145                 } else {
 146                         FD_SET(c->socket, readset);
 147
 148                         if(c->outbuflen > 0 || c->status.connecting) {
 149                                 FD_SET(c->socket, writeset);
 150                         }
 151
 152                         if(c->socket > max) {
 153                                 max = c->socket;
 154                         }
 155                 }
 156         }
 157
 158         for(i = 0; i < listen_sockets; i++) {
 159                 FD_SET(listen_socket[i].tcp, readset);
 160
 161                 if(listen_socket[i].tcp > max) {
 162                         max = listen_socket[i].tcp;
 163                 }
 164
 165                 FD_SET(listen_socket[i].udp, readset);
 166
 167                 if(listen_socket[i].udp > max) {
 168                         max = listen_socket[i].udp;
 169                 }
 170         }
 171
 172         if(device_fd >= 0) {
 173                 FD_SET(device_fd, readset);
 174         }
 175
 176         if(device_fd > max) {
 177                 max = device_fd;
 178         }
 179
 180         return max;
 181 }
 182
 183 /*
 184   Terminate a connection:
 185   - Close the socket
 186   - Remove associated edge and tell other connections about it if report = true
 187   - Check if we need to retry making an outgoing connection
 188   - Deactivate the host
 189 */
 190 void terminate_connection(connection_t *c, bool report) {
 191         if(c->status.remove) {
 192                 return;
 193         }
 194
 195         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 196                                     c->name, c->hostname);
 197
 198         c->status.remove = true;
 199         c->status.active = false;
 200
 201         if(c->node) {
 202                 c->node->connection = NULL;
 203         }
 204
 205         if(c->socket) {
 206                 closesocket(c->socket);
 207         }
 208
 209         if(c->edge) {
 210                 if(!c->node) {
 211                         logger(LOG_ERR, "Connection to %s (%s) has an edge but node is NULL!", c->name, c->hostname);
 212                         // And that should never happen.
 213                         abort();
 214                 }
 215
 216                 if(report && !tunnelserver) {
 217                         send_del_edge(everyone, c->edge);
 218                 }
 219
 220                 edge_del(c->edge);
 221                 c->edge = NULL;
 222
 223                 /* Run MST and SSSP algorithms */
 224
 225                 graph();
 226
 227                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 228
 229                 if(report && !c->node->status.reachable) {
 230                         edge_t *e;
 231                         e = lookup_edge(c->node, myself);
 232
 233                         if(e) {
 234                                 if(!tunnelserver) {
 235                                         send_del_edge(everyone, e);
 236                                 }
 237
 238                                 edge_del(e);
 239                         }
 240                 }
 241         }
 242
 243         free_connection_partially(c);
 244
 245         /* Check if this was our outgoing connection */
 246
 247         if(c->outgoing) {
 248                 c->status.remove = false;
 249                 do_outgoing_connection(c);
 250         }
 251
 252 #ifndef HAVE_MINGW
 253         /* Clean up dead proxy processes */
 254
 255         while(waitpid(-1, NULL, WNOHANG) > 0);
 256
 257 #endif
 258 }
 259
 260 /*
 261   Check if the other end is active.
 262   If we have sent packets, but didn't receive any,
 263   then possibly the other end is dead. We send a
 264   PING request over the meta connection. If the other
 265   end does not reply in time, we consider them dead
 266   and close the connection.
 267 */
 268 static void check_dead_connections(void) {
 269         avl_node_t *node, *next;
 270         connection_t *c;
 271
 272         for(node = connection_tree->head; node; node = next) {
 273                 next = node->next;
 274                 c = node->data;
 275
 276                 if(c->last_ping_time + pingtimeout <= now) {
 277                         if(c->status.active) {
 278                                 if(c->status.pinged) {
 279                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 280                                                                     c->name, c->hostname, (long)(now - c->last_ping_time));
 281                                         c->status.timeout = true;
 282                                         terminate_connection(c, true);
 283                                 } else if(c->last_ping_time + pinginterval <= now) {
 284                                         send_ping(c);
 285                                 }
 286                         } else {
 287                                 if(c->status.remove) {
 288                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 289                                                c->name, c->hostname, bitfield_to_int(&c->status, sizeof(c->status)));
 290                                         connection_del(c);
 291                                         continue;
 292                                 }
 293
 294                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 295                                                             c->name, c->hostname);
 296
 297                                 if(c->status.connecting) {
 298                                         c->status.connecting = false;
 299                                         closesocket(c->socket);
 300                                         do_outgoing_connection(c);
 301                                 } else {
 302                                         terminate_connection(c, false);
 303                                 }
 304                         }
 305                 }
 306
 307                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 308                         if(c->status.active) {
 309                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 310                                                             "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 311                                                             c->name, c->hostname, (long)(now - c->last_flushed_time), c->outbuflen);
 312                                 c->status.timeout = true;
 313                                 terminate_connection(c, true);
 314                         }
 315                 }
 316         }
 317 }
 318
 319 /*
 320   check all connections to see if anything
 321   happened on their sockets
 322 */
 323 static void check_network_activity(fd_set *readset, fd_set *writeset) {
 324         connection_t *c;
 325         avl_node_t *node;
 326         int result, i;
 327         socklen_t len = sizeof(result);
 328         vpn_packet_t packet;
 329         static int errors = 0;
 330
 331         /* check input from kernel */
 332         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 333                 if(devops.read(&packet)) {
 334                         if(packet.len) {
 335                                 errors = 0;
 336                                 packet.priority = 0;
 337                                 route(myself, &packet);
 338                         }
 339                 } else {
 340                         usleep(errors * 50000);
 341                         errors++;
 342
 343                         if(errors > 10) {
 344                                 logger(LOG_ERR, "Too many errors from %s, exiting!", device);
 345                                 running = false;
 346                         }
 347                 }
 348         }
 349
 350         /* check meta connections */
 351         for(node = connection_tree->head; node; node = node->next) {
 352                 c = node->data;
 353
 354                 if(c->status.remove) {
 355                         continue;
 356                 }
 357
 358                 if(FD_ISSET(c->socket, writeset)) {
 359                         if(c->status.connecting) {
 360                                 c->status.connecting = false;
 361                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 362
 363                                 if(!result) {
 364                                         finish_connecting(c);
 365                                 } else {
 366                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 367                                                                     "Error while connecting to %s (%s): %s",
 368                                                                     c->name, c->hostname, sockstrerror(result));
 369                                         closesocket(c->socket);
 370                                         do_outgoing_connection(c);
 371                                         continue;
 372                                 }
 373                         }
 374
 375                         if(!flush_meta(c)) {
 376                                 terminate_connection(c, c->status.active);
 377                                 continue;
 378                         }
 379                 }
 380
 381                 if(FD_ISSET(c->socket, readset)) {
 382                         if(!receive_meta(c)) {
 383                                 terminate_connection(c, c->status.active);
 384                                 continue;
 385                         }
 386                 }
 387         }
 388
 389         for(i = 0; i < listen_sockets; i++) {
 390                 if(FD_ISSET(listen_socket[i].udp, readset)) {
 391                         handle_incoming_vpn_data(i);
 392                 }
 393
 394                 if(FD_ISSET(listen_socket[i].tcp, readset)) {
 395                         handle_new_meta_connection(listen_socket[i].tcp);
 396                 }
 397         }
 398 }
 399
 400 /*
 401   this is where it all happens...
 402 */
 403 int main_loop(void) {
 404         fd_set readset, writeset;
 405 #ifdef HAVE_PSELECT
 406         struct timespec tv;
 407         sigset_t omask, block_mask;
 408         time_t next_event;
 409 #else
 410         struct timeval tv;
 411 #endif
 412         int r, maxfd;
 413         time_t last_ping_check, last_config_check, last_graph_dump;
 414         event_t *event;
 415
 416         last_ping_check = now;
 417         last_config_check = now;
 418         last_graph_dump = now;
 419
 420         srand(now);
 421
 422 #ifdef HAVE_PSELECT
 423
 424         if(lookup_config(config_tree, "GraphDumpFile")) {
 425                 graph_dump = true;
 426         }
 427
 428         /* Block SIGHUP & SIGALRM */
 429         sigemptyset(&block_mask);
 430         sigaddset(&block_mask, SIGHUP);
 431         sigaddset(&block_mask, SIGALRM);
 432         sigprocmask(SIG_BLOCK, &block_mask, &omask);
 433 #endif
 434
 435         running = true;
 436
 437         while(running) {
 438 #ifdef HAVE_PSELECT
 439                 next_event = last_ping_check + pingtimeout;
 440
 441                 if(graph_dump && next_event > last_graph_dump + 60) {
 442                         next_event = last_graph_dump + 60;
 443                 }
 444
 445                 if((event = peek_next_event()) && next_event > event->time) {
 446                         next_event = event->time;
 447                 }
 448
 449                 if(next_event <= now) {
 450                         tv.tv_sec = 0;
 451                 } else {
 452                         tv.tv_sec = next_event - now;
 453                 }
 454
 455                 tv.tv_nsec = 0;
 456 #else
 457                 tv.tv_sec = 1;
 458                 tv.tv_usec = 0;
 459 #endif
 460
 461                 maxfd = build_fdset(&readset, &writeset);
 462
 463 #ifdef HAVE_MINGW
 464                 LeaveCriticalSection(&mutex);
 465 #endif
 466 #ifdef HAVE_PSELECT
 467                 r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
 468 #else
 469                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 470 #endif
 471                 now = time(NULL);
 472 #ifdef HAVE_MINGW
 473                 EnterCriticalSection(&mutex);
 474 #endif
 475
 476                 if(r < 0) {
 477                         if(!sockwouldblock(sockerrno)) {
 478                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 479                                 dump_connections();
 480                                 return 1;
 481                         }
 482                 }
 483
 484                 if(r > 0) {
 485                         check_network_activity(&readset, &writeset);
 486                 }
 487
 488                 if(do_purge) {
 489                         purge();
 490                         do_purge = false;
 491                 }
 492
 493                 /* Let's check if everybody is still alive */
 494
 495                 if(last_ping_check + pingtimeout <= now) {
 496                         check_dead_connections();
 497                         last_ping_check = now;
 498
 499                         if(routing_mode == RMODE_SWITCH) {
 500                                 age_subnets();
 501                         }
 502
 503                         age_past_requests();
 504
 505                         /* Should we regenerate our key? */
 506
 507                         if(keyexpires <= now) {
 508                                 avl_node_t *node;
 509                                 node_t *n;
 510
 511                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 512
 513                                 for(node = node_tree->head; node; node = node->next) {
 514                                         n = node->data;
 515
 516                                         if(n->inkey) {
 517                                                 free(n->inkey);
 518                                                 n->inkey = NULL;
 519                                         }
 520                                 }
 521
 522                                 send_key_changed();
 523                                 keyexpires = now + keylifetime;
 524                         }
 525
 526                         /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
 527                          * two tinc daemons with the same name are on the VPN.
 528                          * If so, sleep a while. If this happens multiple times
 529                          * in a row, sleep longer. */
 530
 531                         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 532                                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 533                                 usleep(sleeptime * 1000000LL);
 534                                 sleeptime *= 2;
 535
 536                                 if(sleeptime < 0) {
 537                                         sleeptime = 3600;
 538                                 }
 539                         } else {
 540                                 sleeptime /= 2;
 541
 542                                 if(sleeptime < 10) {
 543                                         sleeptime = 10;
 544                                 }
 545                         }
 546
 547                         contradicting_add_edge = 0;
 548                         contradicting_del_edge = 0;
 549                 }
 550
 551                 if(sigalrm) {
 552                         avl_node_t *node;
 553                         logger(LOG_INFO, "Flushing event queue");
 554                         expire_events();
 555
 556                         for(node = connection_tree->head; node; node = node->next) {
 557                                 connection_t *c = node->data;
 558
 559                                 if(c->status.active) {
 560                                         send_ping(c);
 561                                 }
 562                         }
 563
 564                         sigalrm = false;
 565                 }
 566
 567                 while((event = get_expired_event())) {
 568                         event->handler(event->data);
 569                         free_event(event);
 570                 }
 571
 572                 if(sighup) {
 573                         connection_t *c;
 574                         avl_node_t *node, *next;
 575                         char *fname;
 576                         struct stat s;
 577
 578                         sighup = false;
 579
 580                         reopenlogger();
 581
 582                         /* Reread our own configuration file */
 583
 584                         exit_configuration(&config_tree);
 585                         init_configuration(&config_tree);
 586
 587                         if(!read_server_config()) {
 588                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 589                                 return 1;
 590                         }
 591
 592                         /* Cancel non-active outgoing connections */
 593
 594                         for(node = connection_tree->head; node; node = next) {
 595                                 next = node->next;
 596                                 c = node->data;
 597
 598                                 c->outgoing = NULL;
 599
 600                                 if(c->status.connecting) {
 601                                         terminate_connection(c, false);
 602                                         connection_del(c);
 603                                 }
 604                         }
 605
 606                         /* Wipe list of outgoing connections */
 607
 608                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 609                                 outgoing_t *outgoing = node->data;
 610
 611                                 if(outgoing->event) {
 612                                         event_del(outgoing->event);
 613                                 }
 614                         }
 615
 616                         list_delete_list(outgoing_list);
 617
 618                         /* Close connections to hosts that have a changed or deleted host config file */
 619
 620                         for(node = connection_tree->head; node; node = node->next) {
 621                                 c = node->data;
 622
 623                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 624
 625                                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 626                                         terminate_connection(c, c->status.active);
 627                                 }
 628
 629                                 free(fname);
 630                         }
 631
 632                         last_config_check = now;
 633
 634                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 635
 636                         if(strictsubnets) {
 637                                 subnet_t *subnet;
 638
 639                                 for(node = subnet_tree->head; node; node = node->next) {
 640                                         subnet = node->data;
 641                                         subnet->expires = 1;
 642                                 }
 643
 644                                 load_all_subnets();
 645
 646                                 for(node = subnet_tree->head; node; node = next) {
 647                                         next = node->next;
 648                                         subnet = node->data;
 649
 650                                         if(subnet->expires == 1) {
 651                                                 send_del_subnet(everyone, subnet);
 652
 653                                                 if(subnet->owner->status.reachable) {
 654                                                         subnet_update(subnet->owner, subnet, false);
 655                                                 }
 656
 657                                                 subnet_del(subnet->owner, subnet);
 658                                         } else if(subnet->expires == -1) {
 659                                                 subnet->expires = 0;
 660                                         } else {
 661                                                 send_add_subnet(everyone, subnet);
 662
 663                                                 if(subnet->owner->status.reachable) {
 664                                                         subnet_update(subnet->owner, subnet, true);
 665                                                 }
 666                                         }
 667                                 }
 668                         }
 669
 670                         /* Try to make outgoing connections */
 671
 672                         try_outgoing_connections();
 673                 }
 674
 675                 /* Dump graph if wanted every 60 seconds*/
 676
 677                 if(last_graph_dump + 60 <= now) {
 678                         dump_graph();
 679                         last_graph_dump = now;
 680                 }
 681         }
 682
 683 #ifdef HAVE_PSELECT
 684         /* Restore SIGHUP & SIGALARM mask */
 685         sigprocmask(SIG_SETMASK, &omask, NULL);
 686 #endif
 687
 688         return 0;
 689 }