git.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                   2000-2010 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License along
  18     with this program; if not, write to the Free Software Foundation, Inc.,
  19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20 */
  21
  22 #include "system.h"
  23
  24 #include <openssl/rand.h>
  25
  26 #include "utils.h"
  27 #include "avl_tree.h"
  28 #include "conf.h"
  29 #include "connection.h"
  30 #include "device.h"
  31 #include "event.h"
  32 #include "graph.h"
  33 #include "logger.h"
  34 #include "meta.h"
  35 #include "net.h"
  36 #include "netutl.h"
  37 #include "process.h"
  38 #include "protocol.h"
  39 #include "route.h"
  40 #include "subnet.h"
  41 #include "xalloc.h"
  42
  43 bool do_purge = false;
  44 volatile bool running = false;
  45
  46 time_t now = 0;
  47
  48 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  49
  50 static void purge(void) {
  51         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  52         node_t *n;
  53         edge_t *e;
  54         subnet_t *s;
  55
  56         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
  57
  58         /* Remove all edges and subnets owned by unreachable nodes. */
  59
  60         for(nnode = node_tree->head; nnode; nnode = nnext) {
  61                 nnext = nnode->next;
  62                 n = nnode->data;
  63
  64                 if(!n->status.reachable) {
  65                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, "Purging node %s (%s)", n->name,
  66                                            n->hostname);
  67
  68                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  69                                 snext = snode->next;
  70                                 s = snode->data;
  71                                 send_del_subnet(broadcast, s);
  72                                 if(!strictsubnets)
  73                                         subnet_del(n, s);
  74                         }
  75
  76                         for(enode = n->edge_tree->head; enode; enode = enext) {
  77                                 enext = enode->next;
  78                                 e = enode->data;
  79                                 if(!tunnelserver)
  80                                         send_del_edge(broadcast, e);
  81                                 edge_del(e);
  82                         }
  83                 }
  84         }
  85
  86         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  87
  88         for(nnode = node_tree->head; nnode; nnode = nnext) {
  89                 nnext = nnode->next;
  90                 n = nnode->data;
  91
  92                 if(!n->status.reachable) {
  93                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  94                                 enext = enode->next;
  95                                 e = enode->data;
  96
  97                                 if(e->to == n)
  98                                         break;
  99                         }
 100
 101                         if(!enode && (!strictsubnets || !n->subnet_tree->head))
 102                                 /* in strictsubnets mode do not delete nodes with subnets */
 103                                 node_del(n);
 104                 }
 105         }
 106 }
 107
 108 /*
 109   put all file descriptors in an fd_set array
 110   While we're at it, purge stuff that needs to be removed.
 111 */
 112 static int build_fdset(fd_set *readset, fd_set *writeset) {
 113         avl_node_t *node, *next;
 114         connection_t *c;
 115         int i, max = 0;
 116
 117         FD_ZERO(readset);
 118         FD_ZERO(writeset);
 119
 120         for(node = connection_tree->head; node; node = next) {
 121                 next = node->next;
 122                 c = node->data;
 123
 124                 if(c->status.remove) {
 125                         connection_del(c);
 126                         if(!connection_tree->head)
 127                                 purge();
 128                 } else {
 129                         FD_SET(c->socket, readset);
 130                         if(c->outbuflen > 0)
 131                                 FD_SET(c->socket, writeset);
 132                         if(c->socket > max)
 133                                 max = c->socket;
 134                 }
 135         }
 136
 137         for(i = 0; i < listen_sockets; i++) {
 138                 FD_SET(listen_socket[i].tcp, readset);
 139                 if(listen_socket[i].tcp > max)
 140                         max = listen_socket[i].tcp;
 141                 FD_SET(listen_socket[i].udp, readset);
 142                 if(listen_socket[i].udp > max)
 143                         max = listen_socket[i].udp;
 144         }
 145
 146         if(device_fd >= 0)
 147                 FD_SET(device_fd, readset);
 148         if(device_fd > max)
 149                 max = device_fd;
 150
 151         return max;
 152 }
 153
 154 /*
 155   Terminate a connection:
 156   - Close the socket
 157   - Remove associated edge and tell other connections about it if report = true
 158   - Check if we need to retry making an outgoing connection
 159   - Deactivate the host
 160 */
 161 void terminate_connection(connection_t *c, bool report) {
 162         if(c->status.remove)
 163                 return;
 164
 165         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 166                            c->name, c->hostname);
 167
 168         c->status.remove = true;
 169         c->status.active = false;
 170
 171         if(c->node)
 172                 c->node->connection = NULL;
 173
 174         if(c->socket)
 175                 closesocket(c->socket);
 176
 177         if(c->edge) {
 178                 if(report && !tunnelserver)
 179                         send_del_edge(broadcast, c->edge);
 180
 181                 edge_del(c->edge);
 182
 183                 /* Run MST and SSSP algorithms */
 184
 185                 graph();
 186
 187                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 188
 189                 if(report && !c->node->status.reachable) {
 190                         edge_t *e;
 191                         e = lookup_edge(c->node, myself);
 192                         if(e) {
 193                                 if(!tunnelserver)
 194                                         send_del_edge(broadcast, e);
 195                                 edge_del(e);
 196                         }
 197                 }
 198         }
 199
 200         /* Check if this was our outgoing connection */
 201
 202         if(c->outgoing) {
 203                 retry_outgoing(c->outgoing);
 204                 c->outgoing = NULL;
 205         }
 206
 207         free(c->outbuf);
 208         c->outbuf = NULL;
 209         c->outbuflen = 0;
 210         c->outbufsize = 0;
 211         c->outbufstart = 0;
 212 }
 213
 214 /*
 215   Check if the other end is active.
 216   If we have sent packets, but didn't receive any,
 217   then possibly the other end is dead. We send a
 218   PING request over the meta connection. If the other
 219   end does not reply in time, we consider them dead
 220   and close the connection.
 221 */
 222 static void check_dead_connections(void) {
 223         avl_node_t *node, *next;
 224         connection_t *c;
 225
 226         for(node = connection_tree->head; node; node = next) {
 227                 next = node->next;
 228                 c = node->data;
 229
 230                 if(c->last_ping_time + pingtimeout < now) {
 231                         if(c->status.active) {
 232                                 if(c->status.pinged) {
 233                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 234                                                            c->name, c->hostname, now - c->last_ping_time);
 235                                         c->status.timeout = true;
 236                                         terminate_connection(c, true);
 237                                 } else if(c->last_ping_time + pinginterval < now) {
 238                                         send_ping(c);
 239                                 }
 240                         } else {
 241                                 if(c->status.remove) {
 242                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 243                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 244                                         connection_del(c);
 245                                         continue;
 246                                 }
 247                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 248                                                    c->name, c->hostname);
 249                                 if(c->status.connecting) {
 250                                         c->status.connecting = false;
 251                                         closesocket(c->socket);
 252                                         do_outgoing_connection(c);
 253                                 } else {
 254                                         terminate_connection(c, false);
 255                                 }
 256                         }
 257                 }
 258
 259                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 260                         if(c->status.active) {
 261                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 262                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 263                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 264                                 c->status.timeout = true;
 265                                 terminate_connection(c, true);
 266                         }
 267                 }
 268         }
 269 }
 270
 271 /*
 272   check all connections to see if anything
 273   happened on their sockets
 274 */
 275 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 276         connection_t *c;
 277         avl_node_t *node;
 278         int result, i;
 279         socklen_t len = sizeof(result);
 280         vpn_packet_t packet;
 281
 282         /* check input from kernel */
 283         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 284                 if(read_packet(&packet)) {
 285                         packet.priority = 0;
 286                         route(myself, &packet);
 287                 }
 288         }
 289
 290         /* check meta connections */
 291         for(node = connection_tree->head; node; node = node->next) {
 292                 c = node->data;
 293
 294                 if(c->status.remove)
 295                         continue;
 296
 297                 if(FD_ISSET(c->socket, readset)) {
 298                         if(c->status.connecting) {
 299                                 c->status.connecting = false;
 300                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 301
 302                                 if(!result)
 303                                         finish_connecting(c);
 304                                 else {
 305                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 306                                                            "Error while connecting to %s (%s): %s",
 307                                                            c->name, c->hostname, sockstrerror(result));
 308                                         closesocket(c->socket);
 309                                         do_outgoing_connection(c);
 310                                         continue;
 311                                 }
 312                         }
 313
 314                         if(!receive_meta(c)) {
 315                                 terminate_connection(c, c->status.active);
 316                                 continue;
 317                         }
 318                 }
 319
 320                 if(FD_ISSET(c->socket, writeset)) {
 321                         if(!flush_meta(c)) {
 322                                 terminate_connection(c, c->status.active);
 323                                 continue;
 324                         }
 325                 }
 326         }
 327
 328         for(i = 0; i < listen_sockets; i++) {
 329                 if(FD_ISSET(listen_socket[i].udp, readset))
 330                         handle_incoming_vpn_data(listen_socket[i].udp);
 331
 332                 if(FD_ISSET(listen_socket[i].tcp, readset))
 333                         handle_new_meta_connection(listen_socket[i].tcp);
 334         }
 335 }
 336
 337 /*
 338   this is where it all happens...
 339 */
 340 int main_loop(void) {
 341         fd_set readset, writeset;
 342         struct timeval tv;
 343         int r, maxfd;
 344         time_t last_ping_check, last_config_check, last_graph_dump;
 345         event_t *event;
 346
 347         last_ping_check = now;
 348         last_config_check = now;
 349         last_graph_dump = now;
 350
 351         srand(now);
 352
 353         running = true;
 354
 355         while(running) {
 356                 now = time(NULL);
 357
 358         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 359                 tv.tv_sec = 1;
 360                 tv.tv_usec = 0;
 361
 362                 maxfd = build_fdset(&readset, &writeset);
 363
 364 #ifdef HAVE_MINGW
 365                 LeaveCriticalSection(&mutex);
 366 #endif
 367                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 368 #ifdef HAVE_MINGW
 369                 EnterCriticalSection(&mutex);
 370 #endif
 371
 372                 if(r < 0) {
 373                         if(!sockwouldblock(sockerrno)) {
 374                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 375                                 dump_connections();
 376                                 return 1;
 377                         }
 378                 }
 379
 380                 if(r > 0)
 381                         check_network_activity(&readset, &writeset);
 382
 383                 if(do_purge) {
 384                         purge();
 385                         do_purge = false;
 386                 }
 387
 388                 /* Let's check if everybody is still alive */
 389
 390                 if(last_ping_check + pingtimeout < now) {
 391                         check_dead_connections();
 392                         last_ping_check = now;
 393
 394                         if(routing_mode == RMODE_SWITCH)
 395                                 age_subnets();
 396
 397                         age_past_requests();
 398
 399                         /* Should we regenerate our key? */
 400
 401                         if(keyexpires < now) {
 402                                 avl_node_t *node;
 403                                 node_t *n;
 404
 405                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 406
 407                                 for(node = node_tree->head; node; node = node->next) {
 408                                         n = node->data;
 409                                         if(n->inkey) {
 410                                                 free(n->inkey);
 411                                                 n->inkey = NULL;
 412                                         }
 413                                 }
 414
 415                                 send_key_changed(broadcast, myself);
 416                                 keyexpires = now + keylifetime;
 417                         }
 418                 }
 419
 420                 if(sigalrm) {
 421                         avl_node_t *node;
 422                         logger(LOG_INFO, "Flushing event queue");
 423                         expire_events();
 424                         for(node = connection_tree->head; node; node = node->next) {
 425                                 connection_t *c = node->data;
 426                                 send_ping(c);
 427                         }
 428                         sigalrm = false;
 429                 }
 430
 431                 while((event = get_expired_event())) {
 432                         event->handler(event->data);
 433                         free_event(event);
 434                 }
 435
 436                 if(sighup) {
 437                         connection_t *c;
 438                         avl_node_t *node, *next;
 439                         char *fname;
 440                         struct stat s;
 441
 442                         sighup = false;
 443
 444                         /* Reread our own configuration file */
 445
 446                         exit_configuration(&config_tree);
 447                         init_configuration(&config_tree);
 448
 449                         if(!read_server_config()) {
 450                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 451                                 return 1;
 452                         }
 453
 454                         /* Cancel non-active outgoing connections */
 455
 456                         for(node = connection_tree->head; node; node = next) {
 457                                 next = node->next;
 458                                 c = node->data;
 459
 460                                 c->outgoing = NULL;
 461
 462                                 if(c->status.connecting) {
 463                                         terminate_connection(c, false);
 464                                         connection_del(c);
 465                                 }
 466                         }
 467
 468                         /* Wipe list of outgoing connections */
 469
 470                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 471                                 outgoing_t *outgoing = node->data;
 472
 473                                 if(outgoing->event)
 474                                         event_del(outgoing->event);
 475                         }
 476
 477                         list_delete_list(outgoing_list);
 478
 479                         /* Close connections to hosts that have a changed or deleted host config file */
 480
 481                         for(node = connection_tree->head; node; node = node->next) {
 482                                 c = node->data;
 483
 484                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 485                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 486                                         terminate_connection(c, c->status.active);
 487                                 free(fname);
 488                         }
 489
 490                         last_config_check = now;
 491
 492                         /* Try to make outgoing connections */
 493
 494                         try_outgoing_connections();
 495                 }
 496
 497                 /* Dump graph if wanted every 60 seconds*/
 498
 499                 if(last_graph_dump + 60 < now) {
 500                         dump_graph();
 501                         last_graph_dump = now;
 502                 }
 503         }
 504
 505         return 0;
 506 }