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                   2000-2009 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 along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include <openssl/rand.h>
  24
  25 #include "utils.h"
  26 #include "avl_tree.h"
  27 #include "conf.h"
  28 #include "connection.h"
  29 #include "device.h"
  30 #include "event.h"
  31 #include "graph.h"
  32 #include "logger.h"
  33 #include "meta.h"
  34 #include "net.h"
  35 #include "netutl.h"
  36 #include "process.h"
  37 #include "protocol.h"
  38 #include "route.h"
  39 #include "subnet.h"
  40 #include "xalloc.h"
  41
  42 bool do_purge = false;
  43 volatile bool running = false;
  44
  45 time_t now = 0;
  46
  47 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  48
  49 static void purge(void)
  50 {
  51         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  52         node_t *n;
  53         edge_t *e;
  54         subnet_t *s;
  55
  56         cp();
  57
  58         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  59
  60         /* Remove all edges and subnets owned by unreachable nodes. */
  61
  62         for(nnode = node_tree->head; nnode; nnode = nnext) {
  63                 nnext = nnode->next;
  64                 n = nnode->data;
  65
  66                 if(!n->status.reachable) {
  67                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  68                                            n->hostname);
  69
  70                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  71                                 snext = snode->next;
  72                                 s = snode->data;
  73                                 if(!tunnelserver)
  74                                         send_del_subnet(broadcast, s);
  75                                 subnet_del(n, s);
  76                         }
  77
  78                         for(enode = n->edge_tree->head; enode; enode = enext) {
  79                                 enext = enode->next;
  80                                 e = enode->data;
  81                                 if(!tunnelserver)
  82                                         send_del_edge(broadcast, e);
  83                                 edge_del(e);
  84                         }
  85                 }
  86         }
  87
  88         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  89
  90         for(nnode = node_tree->head; nnode; nnode = nnext) {
  91                 nnext = nnode->next;
  92                 n = nnode->data;
  93
  94                 if(!n->status.reachable) {
  95                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  96                                 enext = enode->next;
  97                                 e = enode->data;
  98
  99                                 if(e->to == n)
 100                                         break;
 101                         }
 102
 103                         if(!enode)
 104                                 node_del(n);
 105                 }
 106         }
 107 }
 108
 109 /*
 110   put all file descriptors in an fd_set array
 111   While we're at it, purge stuff that needs to be removed.
 112 */
 113 static int build_fdset(fd_set *readset, fd_set *writeset)
 114 {
 115         avl_node_t *node, *next;
 116         connection_t *c;
 117         int i, max = 0;
 118
 119         cp();
 120
 121         FD_ZERO(readset);
 122         FD_ZERO(writeset);
 123
 124         for(node = connection_tree->head; node; node = next) {
 125                 next = node->next;
 126                 c = node->data;
 127
 128                 if(c->status.remove) {
 129                         connection_del(c);
 130                         if(!connection_tree->head)
 131                                 purge();
 132                 } else {
 133                         FD_SET(c->socket, readset);
 134                         if(c->outbuflen > 0)
 135                                 FD_SET(c->socket, writeset);
 136                         if(c->socket > max)
 137                                 max = c->socket;
 138                 }
 139         }
 140
 141         for(i = 0; i < listen_sockets; i++) {
 142                 FD_SET(listen_socket[i].tcp, readset);
 143                 if(listen_socket[i].tcp > max)
 144                         max = listen_socket[i].tcp;
 145                 FD_SET(listen_socket[i].udp, readset);
 146                 if(listen_socket[i].udp > max)
 147                         max = listen_socket[i].udp;
 148         }
 149
 150         if(device_fd >= 0)
 151                 FD_SET(device_fd, readset);
 152         if(device_fd > max)
 153                 max = device_fd;
 154
 155         return max;
 156 }
 157
 158 /*
 159   Terminate a connection:
 160   - Close the socket
 161   - Remove associated edge and tell other connections about it if report = true
 162   - Check if we need to retry making an outgoing connection
 163   - Deactivate the host
 164 */
 165 void terminate_connection(connection_t *c, bool report)
 166 {
 167         cp();
 168
 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(report && !tunnelserver)
 186                         send_del_edge(broadcast, c->edge);
 187
 188                 edge_del(c->edge);
 189
 190                 /* Run MST and SSSP algorithms */
 191
 192                 graph();
 193
 194                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 195
 196                 if(report && !c->node->status.reachable) {
 197                         edge_t *e;
 198                         e = lookup_edge(c->node, myself);
 199                         if(e) {
 200                                 if(!tunnelserver)
 201                                         send_del_edge(broadcast, e);
 202                                 edge_del(e);
 203                         }
 204                 }
 205         }
 206
 207         /* Check if this was our outgoing connection */
 208
 209         if(c->outgoing) {
 210                 retry_outgoing(c->outgoing);
 211                 c->outgoing = NULL;
 212         }
 213
 214         free(c->outbuf);
 215         c->outbuf = NULL;
 216         c->outbuflen = 0;
 217         c->outbufsize = 0;
 218         c->outbufstart = 0;
 219 }
 220
 221 /*
 222   Check if the other end is active.
 223   If we have sent packets, but didn't receive any,
 224   then possibly the other end is dead. We send a
 225   PING request over the meta connection. If the other
 226   end does not reply in time, we consider them dead
 227   and close the connection.
 228 */
 229 static void check_dead_connections(void)
 230 {
 231         avl_node_t *node, *next;
 232         connection_t *c;
 233
 234         cp();
 235
 236         for(node = connection_tree->head; node; node = next) {
 237                 next = node->next;
 238                 c = node->data;
 239
 240                 if(c->last_ping_time + pingtimeout < now) {
 241                         if(c->status.active) {
 242                                 if(c->status.pinged) {
 243                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 244                                                            c->name, c->hostname, now - c->last_ping_time);
 245                                         c->status.timeout = true;
 246                                         terminate_connection(c, true);
 247                                 } else if(c->last_ping_time + pinginterval < now) {
 248                                         send_ping(c);
 249                                 }
 250                         } else {
 251                                 if(c->status.remove) {
 252                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 253                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 254                                         connection_del(c);
 255                                         continue;
 256                                 }
 257                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 258                                                    c->name, c->hostname);
 259                                 if(c->status.connecting) {
 260                                         c->status.connecting = false;
 261                                         closesocket(c->socket);
 262                                         do_outgoing_connection(c);
 263                                 } else {
 264                                         terminate_connection(c, false);
 265                                 }
 266                         }
 267                 }
 268
 269                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 270                         if(c->status.active) {
 271                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 272                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 273                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 274                                 c->status.timeout = true;
 275                                 terminate_connection(c, true);
 276                         }
 277                 }
 278         }
 279 }
 280
 281 /*
 282   check all connections to see if anything
 283   happened on their sockets
 284 */
 285 static void check_network_activity(fd_set * readset, fd_set * writeset)
 286 {
 287         connection_t *c;
 288         avl_node_t *node;
 289         int result, i;
 290         socklen_t len = sizeof(result);
 291         vpn_packet_t packet;
 292
 293         cp();
 294
 295         /* check input from kernel */
 296         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 297                 if(read_packet(&packet)) {
 298                         packet.priority = 0;
 299                         route(myself, &packet);
 300                 }
 301         }
 302
 303         /* check meta connections */
 304         for(node = connection_tree->head; node; node = node->next) {
 305                 c = node->data;
 306
 307                 if(c->status.remove)
 308                         continue;
 309
 310                 if(FD_ISSET(c->socket, readset)) {
 311                         if(c->status.connecting) {
 312                                 c->status.connecting = false;
 313                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 314
 315                                 if(!result)
 316                                         finish_connecting(c);
 317                                 else {
 318                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 319                                                            _("Error while connecting to %s (%s): %s"),
 320                                                            c->name, c->hostname, strerror(result));
 321                                         closesocket(c->socket);
 322                                         do_outgoing_connection(c);
 323                                         continue;
 324                                 }
 325                         }
 326
 327                         if(!receive_meta(c)) {
 328                                 terminate_connection(c, c->status.active);
 329                                 continue;
 330                         }
 331                 }
 332
 333                 if(FD_ISSET(c->socket, writeset)) {
 334                         if(!flush_meta(c)) {
 335                                 terminate_connection(c, c->status.active);
 336                                 continue;
 337                         }
 338                 }
 339         }
 340
 341         for(i = 0; i < listen_sockets; i++) {
 342                 if(FD_ISSET(listen_socket[i].udp, readset))
 343                         handle_incoming_vpn_data(listen_socket[i].udp);
 344
 345                 if(FD_ISSET(listen_socket[i].tcp, readset))
 346                         handle_new_meta_connection(listen_socket[i].tcp);
 347         }
 348 }
 349
 350 /*
 351   this is where it all happens...
 352 */
 353 int main_loop(void)
 354 {
 355         fd_set readset, writeset;
 356         struct timeval tv;
 357         int r, maxfd;
 358         time_t last_ping_check, last_config_check, last_graph_dump;
 359         event_t *event;
 360
 361         cp();
 362
 363         last_ping_check = now;
 364         last_config_check = now;
 365         last_graph_dump = now;
 366
 367         srand(now);
 368
 369         running = true;
 370
 371         while(running) {
 372                 now = time(NULL);
 373
 374         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 375                 tv.tv_sec = 1;
 376                 tv.tv_usec = 0;
 377
 378                 maxfd = build_fdset(&readset, &writeset);
 379
 380 #ifdef HAVE_MINGW
 381                 LeaveCriticalSection(&mutex);
 382 #endif
 383                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 384 #ifdef HAVE_MINGW
 385                 EnterCriticalSection(&mutex);
 386 #endif
 387
 388                 if(r < 0) {
 389                         if(errno != EINTR && errno != EAGAIN) {
 390                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 391                                            strerror(errno));
 392                                 cp_trace();
 393                                 dump_connections();
 394                                 return 1;
 395                         }
 396
 397                         continue;
 398                 }
 399
 400                 check_network_activity(&readset, &writeset);
 401
 402                 if(do_purge) {
 403                         purge();
 404                         do_purge = false;
 405                 }
 406
 407                 /* Let's check if everybody is still alive */
 408
 409                 if(last_ping_check + pingtimeout < now) {
 410                         check_dead_connections();
 411                         last_ping_check = now;
 412
 413                         if(routing_mode == RMODE_SWITCH)
 414                                 age_subnets();
 415
 416                         age_past_requests();
 417
 418                         /* Should we regenerate our key? */
 419
 420                         if(keyexpires < now) {
 421                                 avl_node_t *node;
 422                                 node_t *n;
 423
 424                                 ifdebug(STATUS) logger(LOG_INFO, _("Expiring symmetric keys"));
 425
 426                                 for(node = node_tree->head; node; node = node->next) {
 427                                         n = node->data;
 428                                         if(n->inkey) {
 429                                                 free(n->inkey);
 430                                                 n->inkey = NULL;
 431                                         }
 432                                 }
 433
 434                                 send_key_changed(broadcast, myself);
 435                                 keyexpires = now + keylifetime;
 436                         }
 437                 }
 438
 439                 if(sigalrm) {
 440                         logger(LOG_INFO, _("Flushing event queue"));
 441                         expire_events();
 442                         sigalrm = false;
 443                 }
 444
 445                 while((event = get_expired_event())) {
 446                         event->handler(event->data);
 447                         free_event(event);
 448                 }
 449
 450                 if(sighup) {
 451                         connection_t *c;
 452                         avl_node_t *node;
 453                         char *fname;
 454                         struct stat s;
 455
 456                         sighup = false;
 457
 458                         /* Reread our own configuration file */
 459
 460                         exit_configuration(&config_tree);
 461                         init_configuration(&config_tree);
 462
 463                         if(!read_server_config()) {
 464                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 465                                 return 1;
 466                         }
 467
 468                         /* Close connections to hosts that have a changed or deleted host config file */
 469
 470                         for(node = connection_tree->head; node; node = node->next) {
 471                                 c = node->data;
 472
 473                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 474                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 475                                         terminate_connection(c, c->status.active);
 476                                 free(fname);
 477                         }
 478
 479                         last_config_check = now;
 480
 481                         /* Try to make outgoing connections */
 482
 483                         try_outgoing_connections();
 484                 }
 485
 486                 /* Dump graph if wanted every 60 seconds*/
 487
 488                 if(last_graph_dump + 60 < now) {
 489                         dump_graph();
 490                         last_graph_dump = now;
 491                 }
 492         }
 493
 494         return 0;
 495 }