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                   2000-2009 Guus Sliepen <guus@tinc-vpn.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id$
  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
  47 time_t now = 0;
  48
  49 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  50
  51 static void purge(void)
  52 {
  53         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  54         node_t *n;
  55         edge_t *e;
  56         subnet_t *s;
  57
  58         cp();
  59
  60         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  61
  62         /* Remove all edges and subnets owned by unreachable nodes. */
  63
  64         for(nnode = node_tree->head; nnode; nnode = nnext) {
  65                 nnext = nnode->next;
  66                 n = nnode->data;
  67
  68                 if(!n->status.reachable) {
  69                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  70                                            n->hostname);
  71
  72                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  73                                 snext = snode->next;
  74                                 s = snode->data;
  75                                 if(!tunnelserver)
  76                                         send_del_subnet(broadcast, s);
  77                                 subnet_del(n, s);
  78                         }
  79
  80                         for(enode = n->edge_tree->head; enode; enode = enext) {
  81                                 enext = enode->next;
  82                                 e = enode->data;
  83                                 if(!tunnelserver)
  84                                         send_del_edge(broadcast, e);
  85                                 edge_del(e);
  86                         }
  87                 }
  88         }
  89
  90         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  91
  92         for(nnode = node_tree->head; nnode; nnode = nnext) {
  93                 nnext = nnode->next;
  94                 n = nnode->data;
  95
  96                 if(!n->status.reachable) {
  97                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  98                                 enext = enode->next;
  99                                 e = enode->data;
 100
 101                                 if(e->to == n)
 102                                         break;
 103                         }
 104
 105                         if(!enode)
 106                                 node_del(n);
 107                 }
 108         }
 109 }
 110
 111 /*
 112   put all file descriptors in an fd_set array
 113   While we're at it, purge stuff that needs to be removed.
 114 */
 115 static int build_fdset(fd_set *readset, fd_set *writeset)
 116 {
 117         avl_node_t *node, *next;
 118         connection_t *c;
 119         int i, max = 0;
 120
 121         cp();
 122
 123         FD_ZERO(readset);
 124         FD_ZERO(writeset);
 125
 126         for(node = connection_tree->head; node; node = next) {
 127                 next = node->next;
 128                 c = node->data;
 129
 130                 if(c->status.remove) {
 131                         connection_del(c);
 132                         if(!connection_tree->head)
 133                                 purge();
 134                 } else {
 135                         FD_SET(c->socket, readset);
 136                         if(c->outbuflen > 0)
 137                                 FD_SET(c->socket, writeset);
 138                         if(c->socket > max)
 139                                 max = c->socket;
 140                 }
 141         }
 142
 143         for(i = 0; i < listen_sockets; i++) {
 144                 FD_SET(listen_socket[i].tcp, readset);
 145                 if(listen_socket[i].tcp > max)
 146                         max = listen_socket[i].tcp;
 147                 FD_SET(listen_socket[i].udp, readset);
 148                 if(listen_socket[i].udp > max)
 149                         max = listen_socket[i].udp;
 150         }
 151
 152         if(device_fd >= 0)
 153                 FD_SET(device_fd, readset);
 154         if(device_fd > max)
 155                 max = device_fd;
 156
 157         return max;
 158 }
 159
 160 /*
 161   Terminate a connection:
 162   - Close the socket
 163   - Remove associated edge and tell other connections about it if report = true
 164   - Check if we need to retry making an outgoing connection
 165   - Deactivate the host
 166 */
 167 void terminate_connection(connection_t *c, bool report)
 168 {
 169         cp();
 170
 171         if(c->status.remove)
 172                 return;
 173
 174         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 175                            c->name, c->hostname);
 176
 177         c->status.remove = true;
 178         c->status.active = false;
 179
 180         if(c->node)
 181                 c->node->connection = NULL;
 182
 183         if(c->socket)
 184                 closesocket(c->socket);
 185
 186         if(c->edge) {
 187                 if(report && !tunnelserver)
 188                         send_del_edge(broadcast, c->edge);
 189
 190                 edge_del(c->edge);
 191
 192                 /* Run MST and SSSP algorithms */
 193
 194                 graph();
 195
 196                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 197
 198                 if(report && !c->node->status.reachable) {
 199                         edge_t *e;
 200                         e = lookup_edge(c->node, myself);
 201                         if(e) {
 202                                 if(!tunnelserver)
 203                                         send_del_edge(broadcast, e);
 204                                 edge_del(e);
 205                         }
 206                 }
 207         }
 208
 209         /* Check if this was our outgoing connection */
 210
 211         if(c->outgoing) {
 212                 retry_outgoing(c->outgoing);
 213                 c->outgoing = NULL;
 214         }
 215
 216         free(c->outbuf);
 217         c->outbuf = NULL;
 218         c->outbuflen = 0;
 219         c->outbufsize = 0;
 220         c->outbufstart = 0;
 221 }
 222
 223 /*
 224   Check if the other end is active.
 225   If we have sent packets, but didn't receive any,
 226   then possibly the other end is dead. We send a
 227   PING request over the meta connection. If the other
 228   end does not reply in time, we consider them dead
 229   and close the connection.
 230 */
 231 static void check_dead_connections(void)
 232 {
 233         avl_node_t *node, *next;
 234         connection_t *c;
 235
 236         cp();
 237
 238         for(node = connection_tree->head; node; node = next) {
 239                 next = node->next;
 240                 c = node->data;
 241
 242                 if(c->last_ping_time + pingtimeout < now) {
 243                         if(c->status.active) {
 244                                 if(c->status.pinged) {
 245                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 246                                                            c->name, c->hostname, now - c->last_ping_time);
 247                                         c->status.timeout = true;
 248                                         terminate_connection(c, true);
 249                                 } else if(c->last_ping_time + pinginterval < now) {
 250                                         send_ping(c);
 251                                 }
 252                         } else {
 253                                 if(c->status.remove) {
 254                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 255                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 256                                         connection_del(c);
 257                                         continue;
 258                                 }
 259                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 260                                                    c->name, c->hostname);
 261                                 if(c->status.connecting) {
 262                                         c->status.connecting = false;
 263                                         closesocket(c->socket);
 264                                         do_outgoing_connection(c);
 265                                 } else {
 266                                         terminate_connection(c, false);
 267                                 }
 268                         }
 269                 }
 270
 271                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 272                         if(c->status.active) {
 273                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 274                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 275                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 276                                 c->status.timeout = true;
 277                                 terminate_connection(c, true);
 278                         }
 279                 }
 280         }
 281 }
 282
 283 /*
 284   check all connections to see if anything
 285   happened on their sockets
 286 */
 287 static void check_network_activity(fd_set * readset, fd_set * writeset)
 288 {
 289         connection_t *c;
 290         avl_node_t *node;
 291         int result, i;
 292         socklen_t len = sizeof(result);
 293         vpn_packet_t packet;
 294
 295         cp();
 296
 297         /* check input from kernel */
 298         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 299                 if(read_packet(&packet)) {
 300                         packet.priority = 0;
 301                         route(myself, &packet);
 302                 }
 303         }
 304
 305         /* check meta connections */
 306         for(node = connection_tree->head; node; node = node->next) {
 307                 c = node->data;
 308
 309                 if(c->status.remove)
 310                         continue;
 311
 312                 if(FD_ISSET(c->socket, readset)) {
 313                         if(c->status.connecting) {
 314                                 c->status.connecting = false;
 315                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 316
 317                                 if(!result)
 318                                         finish_connecting(c);
 319                                 else {
 320                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 321                                                            _("Error while connecting to %s (%s): %s"),
 322                                                            c->name, c->hostname, strerror(result));
 323                                         closesocket(c->socket);
 324                                         do_outgoing_connection(c);
 325                                         continue;
 326                                 }
 327                         }
 328
 329                         if(!receive_meta(c)) {
 330                                 terminate_connection(c, c->status.active);
 331                                 continue;
 332                         }
 333                 }
 334
 335                 if(FD_ISSET(c->socket, writeset)) {
 336                         if(!flush_meta(c)) {
 337                                 terminate_connection(c, c->status.active);
 338                                 continue;
 339                         }
 340                 }
 341         }
 342
 343         for(i = 0; i < listen_sockets; i++) {
 344                 if(FD_ISSET(listen_socket[i].udp, readset))
 345                         handle_incoming_vpn_data(listen_socket[i].udp);
 346
 347                 if(FD_ISSET(listen_socket[i].tcp, readset))
 348                         handle_new_meta_connection(listen_socket[i].tcp);
 349         }
 350 }
 351
 352 /*
 353   this is where it all happens...
 354 */
 355 int main_loop(void)
 356 {
 357         fd_set readset, writeset;
 358         struct timeval tv;
 359         int r, maxfd;
 360         time_t last_ping_check, last_config_check, last_graph_dump;
 361         event_t *event;
 362
 363         cp();
 364
 365         last_ping_check = now;
 366         last_config_check = now;
 367         last_graph_dump = now;
 368
 369         srand(now);
 370
 371         running = true;
 372
 373         while(running) {
 374                 now = time(NULL);
 375
 376         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 377                 tv.tv_sec = 1;
 378                 tv.tv_usec = 0;
 379
 380                 maxfd = build_fdset(&readset, &writeset);
 381
 382 #ifdef HAVE_MINGW
 383                 LeaveCriticalSection(&mutex);
 384 #endif
 385                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 386 #ifdef HAVE_MINGW
 387                 EnterCriticalSection(&mutex);
 388 #endif
 389
 390                 if(r < 0) {
 391                         if(errno != EINTR && errno != EAGAIN) {
 392                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 393                                            strerror(errno));
 394                                 cp_trace();
 395                                 dump_connections();
 396                                 return 1;
 397                         }
 398
 399                         continue;
 400                 }
 401
 402                 check_network_activity(&readset, &writeset);
 403
 404                 if(do_purge) {
 405                         purge();
 406                         do_purge = false;
 407                 }
 408
 409                 /* Let's check if everybody is still alive */
 410
 411                 if(last_ping_check + pingtimeout < now) {
 412                         check_dead_connections();
 413                         last_ping_check = now;
 414
 415                         if(routing_mode == RMODE_SWITCH)
 416                                 age_subnets();
 417
 418                         age_past_requests();
 419
 420                         /* Should we regenerate our key? */
 421
 422                         if(keyexpires < now) {
 423                                 avl_node_t *node;
 424                                 node_t *n;
 425
 426                                 ifdebug(STATUS) logger(LOG_INFO, _("Expiring symmetric keys"));
 427
 428                                 for(node = node_tree->head; node; node = node->next) {
 429                                         n = node->data;
 430                                         if(n->inkey) {
 431                                                 free(n->inkey);
 432                                                 n->inkey = NULL;
 433                                         }
 434                                 }
 435
 436                                 send_key_changed(broadcast, myself);
 437                                 keyexpires = now + keylifetime;
 438                         }
 439                 }
 440
 441                 if(sigalrm) {
 442                         logger(LOG_INFO, _("Flushing event queue"));
 443                         expire_events();
 444                         sigalrm = false;
 445                 }
 446
 447                 while((event = get_expired_event())) {
 448                         event->handler(event->data);
 449                         free_event(event);
 450                 }
 451
 452                 if(sighup) {
 453                         connection_t *c;
 454                         avl_node_t *node;
 455                         char *fname;
 456                         struct stat s;
 457
 458                         sighup = false;
 459
 460                         /* Reread our own configuration file */
 461
 462                         exit_configuration(&config_tree);
 463                         init_configuration(&config_tree);
 464
 465                         if(!read_server_config()) {
 466                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 467                                 return 1;
 468                         }
 469
 470                         /* Close connections to hosts that have a changed or deleted host config file */
 471
 472                         for(node = connection_tree->head; node; node = node->next) {
 473                                 c = node->data;
 474
 475                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 476                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 477                                         terminate_connection(c, c->status.active);
 478                                 free(fname);
 479                         }
 480
 481                         last_config_check = now;
 482
 483                         /* Try to make outgoing connections */
 484
 485                         try_outgoing_connections();
 486                 }
 487
 488                 /* Dump graph if wanted every 60 seconds*/
 489
 490                 if(last_graph_dump + 60 < now) {
 491                         dump_graph();
 492                         last_graph_dump = now;
 493                 }
 494         }
 495
 496         return 0;
 497 }