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                   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                                 if(!tunnelserver)
  72                                         send_del_subnet(broadcast, s);
  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)
 102                                 node_del(n);
 103                 }
 104         }
 105 }
 106
 107 /*
 108   put all file descriptors in an fd_set array
 109   While we're at it, purge stuff that needs to be removed.
 110 */
 111 static int build_fdset(fd_set *readset, fd_set *writeset) {
 112         avl_node_t *node, *next;
 113         connection_t *c;
 114         int i, max = 0;
 115
 116         FD_ZERO(readset);
 117         FD_ZERO(writeset);
 118
 119         for(node = connection_tree->head; node; node = next) {
 120                 next = node->next;
 121                 c = node->data;
 122
 123                 if(c->status.remove) {
 124                         connection_del(c);
 125                         if(!connection_tree->head)
 126                                 purge();
 127                 } else {
 128                         FD_SET(c->socket, readset);
 129                         if(c->outbuflen > 0)
 130                                 FD_SET(c->socket, writeset);
 131                         if(c->socket > max)
 132                                 max = c->socket;
 133                 }
 134         }
 135
 136         for(i = 0; i < listen_sockets; i++) {
 137                 FD_SET(listen_socket[i].tcp, readset);
 138                 if(listen_socket[i].tcp > max)
 139                         max = listen_socket[i].tcp;
 140                 FD_SET(listen_socket[i].udp, readset);
 141                 if(listen_socket[i].udp > max)
 142                         max = listen_socket[i].udp;
 143         }
 144
 145         if(device_fd >= 0)
 146                 FD_SET(device_fd, readset);
 147         if(device_fd > max)
 148                 max = device_fd;
 149
 150         return max;
 151 }
 152
 153 /*
 154   Terminate a connection:
 155   - Close the socket
 156   - Remove associated edge and tell other connections about it if report = true
 157   - Check if we need to retry making an outgoing connection
 158   - Deactivate the host
 159 */
 160 void terminate_connection(connection_t *c, bool report) {
 161         if(c->status.remove)
 162                 return;
 163
 164         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 165                            c->name, c->hostname);
 166
 167         c->status.remove = true;
 168         c->status.active = false;
 169
 170         if(c->node)
 171                 c->node->connection = NULL;
 172
 173         if(c->socket)
 174                 closesocket(c->socket);
 175
 176         if(c->edge) {
 177                 if(report && !tunnelserver)
 178                         send_del_edge(broadcast, c->edge);
 179
 180                 edge_del(c->edge);
 181
 182                 /* Run MST and SSSP algorithms */
 183
 184                 graph();
 185
 186                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 187
 188                 if(report && !c->node->status.reachable) {
 189                         edge_t *e;
 190                         e = lookup_edge(c->node, myself);
 191                         if(e) {
 192                                 if(!tunnelserver)
 193                                         send_del_edge(broadcast, e);
 194                                 edge_del(e);
 195                         }
 196                 }
 197         }
 198
 199         /* Check if this was our outgoing connection */
 200
 201         if(c->outgoing) {
 202                 retry_outgoing(c->outgoing);
 203                 c->outgoing = NULL;
 204         }
 205
 206         free(c->outbuf);
 207         c->outbuf = NULL;
 208         c->outbuflen = 0;
 209         c->outbufsize = 0;
 210         c->outbufstart = 0;
 211 }
 212
 213 /*
 214   Check if the other end is active.
 215   If we have sent packets, but didn't receive any,
 216   then possibly the other end is dead. We send a
 217   PING request over the meta connection. If the other
 218   end does not reply in time, we consider them dead
 219   and close the connection.
 220 */
 221 static void check_dead_connections(void) {
 222         avl_node_t *node, *next;
 223         connection_t *c;
 224
 225         for(node = connection_tree->head; node; node = next) {
 226                 next = node->next;
 227                 c = node->data;
 228
 229                 if(c->last_ping_time + pingtimeout < now) {
 230                         if(c->status.active) {
 231                                 if(c->status.pinged) {
 232                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 233                                                            c->name, c->hostname, now - c->last_ping_time);
 234                                         c->status.timeout = true;
 235                                         terminate_connection(c, true);
 236                                 } else if(c->last_ping_time + pinginterval < now) {
 237                                         send_ping(c);
 238                                 }
 239                         } else {
 240                                 if(c->status.remove) {
 241                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 242                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 243                                         connection_del(c);
 244                                         continue;
 245                                 }
 246                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 247                                                    c->name, c->hostname);
 248                                 if(c->status.connecting) {
 249                                         c->status.connecting = false;
 250                                         closesocket(c->socket);
 251                                         do_outgoing_connection(c);
 252                                 } else {
 253                                         terminate_connection(c, false);
 254                                 }
 255                         }
 256                 }
 257
 258                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 259                         if(c->status.active) {
 260                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 261                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 262                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 263                                 c->status.timeout = true;
 264                                 terminate_connection(c, true);
 265                         }
 266                 }
 267         }
 268 }
 269
 270 /*
 271   check all connections to see if anything
 272   happened on their sockets
 273 */
 274 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 275         connection_t *c;
 276         avl_node_t *node;
 277         int result, i;
 278         socklen_t len = sizeof(result);
 279         vpn_packet_t packet;
 280
 281         /* check input from kernel */
 282         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 283                 if(read_packet(&packet)) {
 284                         packet.priority = 0;
 285                         route(myself, &packet);
 286                 }
 287         }
 288
 289         /* check meta connections */
 290         for(node = connection_tree->head; node; node = node->next) {
 291                 c = node->data;
 292
 293                 if(c->status.remove)
 294                         continue;
 295
 296                 if(FD_ISSET(c->socket, readset)) {
 297                         if(c->status.connecting) {
 298                                 c->status.connecting = false;
 299                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 300
 301                                 if(!result)
 302                                         finish_connecting(c);
 303                                 else {
 304                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 305                                                            "Error while connecting to %s (%s): %s",
 306                                                            c->name, c->hostname, strerror(result));
 307                                         closesocket(c->socket);
 308                                         do_outgoing_connection(c);
 309                                         continue;
 310                                 }
 311                         }
 312
 313                         if(!receive_meta(c)) {
 314                                 terminate_connection(c, c->status.active);
 315                                 continue;
 316                         }
 317                 }
 318
 319                 if(FD_ISSET(c->socket, writeset)) {
 320                         if(!flush_meta(c)) {
 321                                 terminate_connection(c, c->status.active);
 322                                 continue;
 323                         }
 324                 }
 325         }
 326
 327         for(i = 0; i < listen_sockets; i++) {
 328                 if(FD_ISSET(listen_socket[i].udp, readset))
 329                         handle_incoming_vpn_data(listen_socket[i].udp);
 330
 331                 if(FD_ISSET(listen_socket[i].tcp, readset))
 332                         handle_new_meta_connection(listen_socket[i].tcp);
 333         }
 334 }
 335
 336 /*
 337   this is where it all happens...
 338 */
 339 int main_loop(void) {
 340         fd_set readset, writeset;
 341         struct timeval tv;
 342         int r, maxfd;
 343         time_t last_ping_check, last_config_check, last_graph_dump;
 344         event_t *event;
 345
 346         last_ping_check = now;
 347         last_config_check = now;
 348         last_graph_dump = now;
 349
 350         srand(now);
 351
 352         running = true;
 353
 354         while(running) {
 355                 now = time(NULL);
 356
 357         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 358                 tv.tv_sec = 1;
 359                 tv.tv_usec = 0;
 360
 361                 maxfd = build_fdset(&readset, &writeset);
 362
 363 #ifdef HAVE_MINGW
 364                 LeaveCriticalSection(&mutex);
 365 #endif
 366                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 367 #ifdef HAVE_MINGW
 368                 EnterCriticalSection(&mutex);
 369 #endif
 370
 371                 if(r < 0) {
 372                         if(errno != EINTR && errno != EAGAIN) {
 373                                 logger(LOG_ERR, "Error while waiting for input: %s",
 374                                            strerror(errno));
 375                                 dump_connections();
 376                                 return 1;
 377                         }
 378
 379                         continue;
 380                 }
 381
 382                 check_network_activity(&readset, &writeset);
 383
 384                 if(do_purge) {
 385                         purge();
 386                         do_purge = false;
 387                 }
 388
 389                 /* Let's check if everybody is still alive */
 390
 391                 if(last_ping_check + pingtimeout < now) {
 392                         check_dead_connections();
 393                         last_ping_check = now;
 394
 395                         if(routing_mode == RMODE_SWITCH)
 396                                 age_subnets();
 397
 398                         age_past_requests();
 399
 400                         /* Should we regenerate our key? */
 401
 402                         if(keyexpires < now) {
 403                                 avl_node_t *node;
 404                                 node_t *n;
 405
 406                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 407
 408                                 for(node = node_tree->head; node; node = node->next) {
 409                                         n = node->data;
 410                                         if(n->inkey) {
 411                                                 free(n->inkey);
 412                                                 n->inkey = NULL;
 413                                         }
 414                                 }
 415
 416                                 send_key_changed(broadcast, myself);
 417                                 keyexpires = now + keylifetime;
 418                         }
 419                 }
 420
 421                 if(sigalrm) {
 422                         logger(LOG_INFO, "Flushing event queue");
 423                         expire_events();
 424                         sigalrm = false;
 425                 }
 426
 427                 while((event = get_expired_event())) {
 428                         event->handler(event->data);
 429                         free_event(event);
 430                 }
 431
 432                 if(sighup) {
 433                         connection_t *c;
 434                         avl_node_t *node, *next;
 435                         char *fname;
 436                         struct stat s;
 437
 438                         sighup = false;
 439
 440                         /* Reread our own configuration file */
 441
 442                         exit_configuration(&config_tree);
 443                         init_configuration(&config_tree);
 444
 445                         if(!read_server_config()) {
 446                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 447                                 return 1;
 448                         }
 449
 450                         /* Cancel non-active outgoing connections */
 451
 452                         for(node = connection_tree->head; node; node = next) {
 453                                 next = node->next;
 454                                 c = node->data;
 455
 456                                 c->outgoing = NULL;
 457
 458                                 if(c->status.connecting) {
 459                                         terminate_connection(c, false);
 460                                         connection_del(c);
 461                                 }
 462                         }
 463
 464                         /* Wipe list of outgoing connections */
 465
 466                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 467                                 outgoing_t *outgoing = node->data;
 468
 469                                 if(outgoing->event)
 470                                         event_del(outgoing->event);
 471                         }
 472
 473                         list_delete_list(outgoing_list);
 474
 475                         /* Close connections to hosts that have a changed or deleted host config file */
 476
 477                         for(node = connection_tree->head; node; node = node->next) {
 478                                 c = node->data;
 479
 480                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 481                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 482                                         terminate_connection(c, c->status.active);
 483                                 free(fname);
 484                         }
 485
 486                         last_config_check = now;
 487
 488                         /* Try to make outgoing connections */
 489
 490                         try_outgoing_connections();
 491                 }
 492
 493                 /* Dump graph if wanted every 60 seconds*/
 494
 495                 if(last_graph_dump + 60 < now) {
 496                         dump_graph();
 497                         last_graph_dump = now;
 498                 }
 499         }
 500
 501         return 0;
 502 }