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 /* Put a misbehaving connection in the tarpit */
 184 void tarpit(int fd) {
 185         static int pits[10] = {-1, -1, -1, -1, -1, -1, -1, -1, -1, -1};
 186         static int next_pit = 0;
 187
 188         if(pits[next_pit] != -1) {
 189                 closesocket(pits[next_pit]);
 190         }
 191
 192         pits[next_pit++] = fd;
 193
 194         if(next_pit >= (int)(sizeof pits / sizeof pits[0])) {
 195                 next_pit = 0;
 196         }
 197 }
 198
 199 /*
 200   Terminate a connection:
 201   - Close the socket
 202   - Remove associated edge and tell other connections about it if report = true
 203   - Check if we need to retry making an outgoing connection
 204   - Deactivate the host
 205 */
 206 void terminate_connection(connection_t *c, bool report) {
 207         if(c->status.remove) {
 208                 return;
 209         }
 210
 211         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 212                                     c->name, c->hostname);
 213
 214         c->status.remove = true;
 215         c->status.active = false;
 216
 217         if(c->node) {
 218                 c->node->connection = NULL;
 219         }
 220
 221         if(c->socket) {
 222                 if(c->status.tarpit) {
 223                         tarpit(c->socket);
 224                 } else {
 225                         closesocket(c->socket);
 226                 }
 227         }
 228
 229         if(c->edge) {
 230                 if(!c->node) {
 231                         logger(LOG_ERR, "Connection to %s (%s) has an edge but node is NULL!", c->name, c->hostname);
 232                         // And that should never happen.
 233                         abort();
 234                 }
 235
 236                 if(report && !tunnelserver) {
 237                         send_del_edge(everyone, c->edge);
 238                 }
 239
 240                 edge_del(c->edge);
 241                 c->edge = NULL;
 242
 243                 /* Run MST and SSSP algorithms */
 244
 245                 graph();
 246
 247                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 248
 249                 if(report && !c->node->status.reachable) {
 250                         edge_t *e;
 251                         e = lookup_edge(c->node, myself);
 252
 253                         if(e) {
 254                                 if(!tunnelserver) {
 255                                         send_del_edge(everyone, e);
 256                                 }
 257
 258                                 edge_del(e);
 259                         }
 260                 }
 261         }
 262
 263         free_connection_partially(c);
 264
 265         /* Check if this was our outgoing connection */
 266
 267         if(c->outgoing) {
 268                 c->status.remove = false;
 269                 do_outgoing_connection(c);
 270         }
 271
 272 #ifndef HAVE_MINGW
 273         /* Clean up dead proxy processes */
 274
 275         while(waitpid(-1, NULL, WNOHANG) > 0);
 276
 277 #endif
 278 }
 279
 280 /*
 281   Check if the other end is active.
 282   If we have sent packets, but didn't receive any,
 283   then possibly the other end is dead. We send a
 284   PING request over the meta connection. If the other
 285   end does not reply in time, we consider them dead
 286   and close the connection.
 287 */
 288 static void check_dead_connections(void) {
 289         avl_node_t *node, *next;
 290         connection_t *c;
 291
 292         for(node = connection_tree->head; node; node = next) {
 293                 next = node->next;
 294                 c = node->data;
 295
 296                 if(c->last_ping_time + pingtimeout <= now) {
 297                         if(c->status.active) {
 298                                 if(c->status.pinged) {
 299                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 300                                                                     c->name, c->hostname, (long)(now - c->last_ping_time));
 301                                         c->status.timeout = true;
 302                                         terminate_connection(c, true);
 303                                 } else if(c->last_ping_time + pinginterval <= now) {
 304                                         send_ping(c);
 305                                 }
 306                         } else {
 307                                 if(c->status.remove) {
 308                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 309                                                c->name, c->hostname, bitfield_to_int(&c->status, sizeof(c->status)));
 310                                         connection_del(c);
 311                                         continue;
 312                                 }
 313
 314                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 315                                                             c->name, c->hostname);
 316
 317                                 if(c->status.connecting) {
 318                                         c->status.connecting = false;
 319                                         closesocket(c->socket);
 320                                         do_outgoing_connection(c);
 321                                 } else {
 322                                         c->status.tarpit = true;
 323                                         terminate_connection(c, false);
 324                                 }
 325                         }
 326                 }
 327
 328                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout <= now) {
 329                         if(c->status.active) {
 330                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 331                                                             "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 332                                                             c->name, c->hostname, (long)(now - c->last_flushed_time), c->outbuflen);
 333                                 c->status.timeout = true;
 334                                 terminate_connection(c, true);
 335                         }
 336                 }
 337         }
 338 }
 339
 340 /*
 341   check all connections to see if anything
 342   happened on their sockets
 343 */
 344 static void check_network_activity(fd_set *readset, fd_set *writeset) {
 345         connection_t *c;
 346         avl_node_t *node;
 347         int result, i;
 348         socklen_t len = sizeof(result);
 349         vpn_packet_t packet;
 350         static int errors = 0;
 351
 352         /* check input from kernel */
 353         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 354                 if(devops.read(&packet)) {
 355                         if(packet.len) {
 356                                 errors = 0;
 357                                 packet.priority = 0;
 358                                 route(myself, &packet);
 359                         }
 360                 } else {
 361                         usleep(errors * 50000);
 362                         errors++;
 363
 364                         if(errors > 10) {
 365                                 logger(LOG_ERR, "Too many errors from %s, exiting!", device);
 366                                 running = false;
 367                         }
 368                 }
 369         }
 370
 371         /* check meta connections */
 372         for(node = connection_tree->head; node; node = node->next) {
 373                 c = node->data;
 374
 375                 if(c->status.remove) {
 376                         continue;
 377                 }
 378
 379                 if(FD_ISSET(c->socket, writeset)) {
 380                         if(c->status.connecting) {
 381                                 c->status.connecting = false;
 382                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 383
 384                                 if(!result) {
 385                                         finish_connecting(c);
 386                                 } else {
 387                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 388                                                                     "Error while connecting to %s (%s): %s",
 389                                                                     c->name, c->hostname, sockstrerror(result));
 390                                         closesocket(c->socket);
 391                                         do_outgoing_connection(c);
 392                                         continue;
 393                                 }
 394                         }
 395
 396                         if(!flush_meta(c)) {
 397                                 terminate_connection(c, c->status.active);
 398                                 continue;
 399                         }
 400                 }
 401
 402                 if(FD_ISSET(c->socket, readset)) {
 403                         if(!receive_meta(c)) {
 404                                 c->status.tarpit = true;
 405                                 terminate_connection(c, c->status.active);
 406                                 continue;
 407                         }
 408                 }
 409         }
 410
 411         for(i = 0; i < listen_sockets; i++) {
 412                 if(FD_ISSET(listen_socket[i].udp, readset)) {
 413                         handle_incoming_vpn_data(i);
 414                 }
 415
 416                 if(FD_ISSET(listen_socket[i].tcp, readset)) {
 417                         handle_new_meta_connection(listen_socket[i].tcp);
 418                 }
 419         }
 420 }
 421
 422 /*
 423   this is where it all happens...
 424 */
 425 int main_loop(void) {
 426         fd_set readset, writeset;
 427 #ifdef HAVE_PSELECT
 428         struct timespec tv;
 429         sigset_t omask, block_mask;
 430         time_t next_event;
 431 #else
 432         struct timeval tv;
 433 #endif
 434         int r, maxfd;
 435         time_t last_ping_check, last_config_check, last_graph_dump;
 436         event_t *event;
 437
 438         last_ping_check = now;
 439         last_config_check = now;
 440         last_graph_dump = now;
 441
 442         srand(now);
 443
 444 #ifdef HAVE_PSELECT
 445
 446         if(lookup_config(config_tree, "GraphDumpFile")) {
 447                 graph_dump = true;
 448         }
 449
 450         /* Block SIGHUP & SIGALRM */
 451         sigemptyset(&block_mask);
 452         sigaddset(&block_mask, SIGHUP);
 453         sigaddset(&block_mask, SIGALRM);
 454         sigprocmask(SIG_BLOCK, &block_mask, &omask);
 455 #endif
 456
 457         running = true;
 458
 459         while(running) {
 460 #ifdef HAVE_PSELECT
 461                 next_event = last_ping_check + pingtimeout;
 462
 463                 if(graph_dump && next_event > last_graph_dump + 60) {
 464                         next_event = last_graph_dump + 60;
 465                 }
 466
 467                 if((event = peek_next_event()) && next_event > event->time) {
 468                         next_event = event->time;
 469                 }
 470
 471                 if(next_event <= now) {
 472                         tv.tv_sec = 0;
 473                 } else {
 474                         tv.tv_sec = next_event - now;
 475                 }
 476
 477                 tv.tv_nsec = 0;
 478 #else
 479                 tv.tv_sec = 1;
 480                 tv.tv_usec = 0;
 481 #endif
 482
 483                 maxfd = build_fdset(&readset, &writeset);
 484
 485 #ifdef HAVE_MINGW
 486                 LeaveCriticalSection(&mutex);
 487 #endif
 488 #ifdef HAVE_PSELECT
 489                 r = pselect(maxfd + 1, &readset, &writeset, NULL, &tv, &omask);
 490 #else
 491                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 492 #endif
 493                 now = time(NULL);
 494 #ifdef HAVE_MINGW
 495                 EnterCriticalSection(&mutex);
 496 #endif
 497
 498                 if(r < 0) {
 499                         if(!sockwouldblock(sockerrno)) {
 500                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 501                                 dump_connections();
 502                                 return 1;
 503                         }
 504                 }
 505
 506                 if(r > 0) {
 507                         check_network_activity(&readset, &writeset);
 508                 }
 509
 510                 if(do_purge) {
 511                         purge();
 512                         do_purge = false;
 513                 }
 514
 515                 /* Let's check if everybody is still alive */
 516
 517                 if(last_ping_check + pingtimeout <= now) {
 518                         check_dead_connections();
 519                         last_ping_check = now;
 520
 521                         if(routing_mode == RMODE_SWITCH) {
 522                                 age_subnets();
 523                         }
 524
 525                         age_past_requests();
 526
 527                         /* Should we regenerate our key? */
 528
 529                         if(keyexpires <= now) {
 530                                 avl_node_t *node;
 531                                 node_t *n;
 532
 533                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 534
 535                                 for(node = node_tree->head; node; node = node->next) {
 536                                         n = node->data;
 537
 538                                         if(n->inkey) {
 539                                                 free(n->inkey);
 540                                                 n->inkey = NULL;
 541                                         }
 542                                 }
 543
 544                                 send_key_changed();
 545                                 keyexpires = now + keylifetime;
 546                         }
 547
 548                         /* Detect ADD_EDGE/DEL_EDGE storms that are caused when
 549                          * two tinc daemons with the same name are on the VPN.
 550                          * If so, sleep a while. If this happens multiple times
 551                          * in a row, sleep longer. */
 552
 553                         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 554                                 logger(LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 555                                 usleep(sleeptime * 1000000LL);
 556                                 sleeptime *= 2;
 557
 558                                 if(sleeptime < 0) {
 559                                         sleeptime = 3600;
 560                                 }
 561                         } else {
 562                                 sleeptime /= 2;
 563
 564                                 if(sleeptime < 10) {
 565                                         sleeptime = 10;
 566                                 }
 567                         }
 568
 569                         contradicting_add_edge = 0;
 570                         contradicting_del_edge = 0;
 571                 }
 572
 573                 if(sigalrm) {
 574                         avl_node_t *node;
 575                         logger(LOG_INFO, "Flushing event queue");
 576                         expire_events();
 577
 578                         for(node = connection_tree->head; node; node = node->next) {
 579                                 connection_t *c = node->data;
 580
 581                                 if(c->status.active) {
 582                                         send_ping(c);
 583                                 }
 584                         }
 585
 586                         sigalrm = false;
 587                 }
 588
 589                 while((event = get_expired_event())) {
 590                         event->handler(event->data);
 591                         free_event(event);
 592                 }
 593
 594                 if(sighup) {
 595                         connection_t *c;
 596                         avl_node_t *node, *next;
 597                         char *fname;
 598                         struct stat s;
 599
 600                         sighup = false;
 601
 602                         reopenlogger();
 603
 604                         /* Reread our own configuration file */
 605
 606                         exit_configuration(&config_tree);
 607                         init_configuration(&config_tree);
 608
 609                         if(!read_server_config()) {
 610                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 611                                 return 1;
 612                         }
 613
 614                         /* Cancel non-active outgoing connections */
 615
 616                         for(node = connection_tree->head; node; node = next) {
 617                                 next = node->next;
 618                                 c = node->data;
 619
 620                                 c->outgoing = NULL;
 621
 622                                 if(c->status.connecting) {
 623                                         terminate_connection(c, false);
 624                                         connection_del(c);
 625                                 }
 626                         }
 627
 628                         /* Wipe list of outgoing connections */
 629
 630                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 631                                 outgoing_t *outgoing = node->data;
 632
 633                                 if(outgoing->event) {
 634                                         event_del(outgoing->event);
 635                                 }
 636                         }
 637
 638                         list_delete_list(outgoing_list);
 639
 640                         /* Close connections to hosts that have a changed or deleted host config file */
 641
 642                         for(node = connection_tree->head; node; node = node->next) {
 643                                 c = node->data;
 644
 645                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 646
 647                                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 648                                         terminate_connection(c, c->status.active);
 649                                 }
 650
 651                                 free(fname);
 652                         }
 653
 654                         last_config_check = now;
 655
 656                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 657
 658                         if(strictsubnets) {
 659                                 subnet_t *subnet;
 660
 661                                 for(node = subnet_tree->head; node; node = node->next) {
 662                                         subnet = node->data;
 663                                         subnet->expires = 1;
 664                                 }
 665
 666                                 load_all_subnets();
 667
 668                                 for(node = subnet_tree->head; node; node = next) {
 669                                         next = node->next;
 670                                         subnet = node->data;
 671
 672                                         if(subnet->expires == 1) {
 673                                                 send_del_subnet(everyone, subnet);
 674
 675                                                 if(subnet->owner->status.reachable) {
 676                                                         subnet_update(subnet->owner, subnet, false);
 677                                                 }
 678
 679                                                 subnet_del(subnet->owner, subnet);
 680                                         } else if(subnet->expires == -1) {
 681                                                 subnet->expires = 0;
 682                                         } else {
 683                                                 send_add_subnet(everyone, subnet);
 684
 685                                                 if(subnet->owner->status.reachable) {
 686                                                         subnet_update(subnet->owner, subnet, true);
 687                                                 }
 688                                         }
 689                                 }
 690                         }
 691
 692                         /* Try to make outgoing connections */
 693
 694                         try_outgoing_connections();
 695                 }
 696
 697                 /* Dump graph if wanted every 60 seconds*/
 698
 699                 if(last_graph_dump + 60 <= now) {
 700                         dump_graph();
 701                         last_graph_dump = now;
 702                 }
 703         }
 704
 705 #ifdef HAVE_PSELECT
 706         /* Restore SIGHUP & SIGALARM mask */
 707         sigprocmask(SIG_SETMASK, &omask, NULL);
 708 #endif
 709
 710         return 0;
 711 }