www.tinc-vpn.org Git - tinc/blob - src/net.c

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