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