src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2006 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         FD_SET(device_fd, readset);
 153         if(device_fd > max)
 154                 max = device_fd;
 155
 156         return max;
 157 }
 158
 159 /*
 160   Terminate a connection:
 161   - Close the socket
 162   - Remove associated edge and tell other connections about it if report = true
 163   - Check if we need to retry making an outgoing connection
 164   - Deactivate the host
 165 */
 166 void terminate_connection(connection_t *c, bool report)
 167 {
 168         cp();
 169
 170         if(c->status.remove)
 171                 return;
 172
 173         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 174                            c->name, c->hostname);
 175
 176         c->status.remove = true;
 177         c->status.active = false;
 178
 179         if(c->node)
 180                 c->node->connection = NULL;
 181
 182         if(c->socket)
 183                 closesocket(c->socket);
 184
 185         if(c->edge) {
 186                 if(report && !tunnelserver)
 187                         send_del_edge(broadcast, c->edge);
 188
 189                 edge_del(c->edge);
 190
 191                 /* Run MST and SSSP algorithms */
 192
 193                 graph();
 194
 195                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 196
 197                 if(report && !c->node->status.reachable) {
 198                         edge_t *e;
 199                         e = lookup_edge(c->node, myself);
 200                         if(e) {
 201                                 if(!tunnelserver)
 202                                         send_del_edge(broadcast, e);
 203                                 edge_del(e);
 204                         }
 205                 }
 206         }
 207
 208         /* Check if this was our outgoing connection */
 209
 210         if(c->outgoing) {
 211                 retry_outgoing(c->outgoing);
 212                 c->outgoing = NULL;
 213         }
 214
 215         free(c->outbuf);
 216         c->outbuf = NULL;
 217         c->outbuflen = 0;
 218         c->outbufsize = 0;
 219         c->outbufstart = 0;
 220 }
 221
 222 /*
 223   Check if the other end is active.
 224   If we have sent packets, but didn't receive any,
 225   then possibly the other end is dead. We send a
 226   PING request over the meta connection. If the other
 227   end does not reply in time, we consider them dead
 228   and close the connection.
 229 */
 230 static void check_dead_connections(void)
 231 {
 232         avl_node_t *node, *next;
 233         connection_t *c;
 234
 235         cp();
 236
 237         for(node = connection_tree->head; node; node = next) {
 238                 next = node->next;
 239                 c = node->data;
 240
 241                 if(c->last_ping_time + pingtimeout < now) {
 242                         if(c->status.active) {
 243                                 if(c->status.pinged) {
 244                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %d seconds"),
 245                                                            c->name, c->hostname, now - c->last_ping_time);
 246                                         c->status.timeout = true;
 247                                         terminate_connection(c, true);
 248                                 } else if(c->last_ping_time + pinginterval < now) {
 249                                         send_ping(c);
 250                                 }
 251                         } else {
 252                                 if(c->status.remove) {
 253                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 254                                                    c->name, c->hostname, *(uint32_t *)&c->status);
 255                                         connection_del(c);
 256                                         continue;
 257                                 }
 258                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 259                                                    c->name, c->hostname);
 260                                 if(c->status.connecting) {
 261                                         c->status.connecting = false;
 262                                         closesocket(c->socket);
 263                                         do_outgoing_connection(c);
 264                                 } else {
 265                                         terminate_connection(c, false);
 266                                 }
 267                         }
 268                 }
 269
 270                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 271                         if(c->status.active) {
 272                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 273                                                 _("%s (%s) could not flush for %d seconds (%d bytes remaining)"),
 274                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 275                                 c->status.timeout = true;
 276                                 terminate_connection(c, true);
 277                         }
 278                 }
 279         }
 280 }
 281
 282 /*
 283   check all connections to see if anything
 284   happened on their sockets
 285 */
 286 static void check_network_activity(fd_set * readset, fd_set * writeset)
 287 {
 288         connection_t *c;
 289         avl_node_t *node;
 290         int result, i;
 291         socklen_t len = sizeof(result);
 292         vpn_packet_t packet;
 293
 294         cp();
 295
 296         /* check input from kernel */
 297         if(FD_ISSET(device_fd, readset)) {
 298                 if(read_packet(&packet))
 299                         route(myself, &packet);
 300         }
 301
 302         /* check meta connections */
 303         for(node = connection_tree->head; node; node = node->next) {
 304                 c = node->data;
 305
 306                 if(c->status.remove)
 307                         continue;
 308
 309                 if(FD_ISSET(c->socket, readset)) {
 310                         if(c->status.connecting) {
 311                                 c->status.connecting = false;
 312                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 313
 314                                 if(!result)
 315                                         finish_connecting(c);
 316                                 else {
 317                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 318                                                            _("Error while connecting to %s (%s): %s"),
 319                                                            c->name, c->hostname, strerror(result));
 320                                         closesocket(c->socket);
 321                                         do_outgoing_connection(c);
 322                                         continue;
 323                                 }
 324                         }
 325
 326                         if(!receive_meta(c)) {
 327                                 terminate_connection(c, c->status.active);
 328                                 continue;
 329                         }
 330                 }
 331
 332                 if(FD_ISSET(c->socket, writeset)) {
 333                         if(!flush_meta(c)) {
 334                                 terminate_connection(c, c->status.active);
 335                                 continue;
 336                         }
 337                 }
 338         }
 339
 340         for(i = 0; i < listen_sockets; i++) {
 341                 if(FD_ISSET(listen_socket[i].udp, readset))
 342                         handle_incoming_vpn_data(listen_socket[i].udp);
 343
 344                 if(FD_ISSET(listen_socket[i].tcp, readset))
 345                         handle_new_meta_connection(listen_socket[i].tcp);
 346         }
 347 }
 348
 349 /*
 350   this is where it all happens...
 351 */
 352 int main_loop(void)
 353 {
 354         fd_set readset, writeset;
 355         struct timeval tv;
 356         int r, maxfd;
 357         time_t last_ping_check, last_config_check;
 358         event_t *event;
 359
 360         cp();
 361
 362         last_ping_check = now;
 363         last_config_check = now;
 364         srand(now);
 365
 366         running = true;
 367
 368         while(running) {
 369                 now = time(NULL);
 370
 371         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 372                 tv.tv_sec = 1;
 373                 tv.tv_usec = 0;
 374
 375                 maxfd = build_fdset(&readset, &writeset);
 376
 377                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 378
 379                 if(r < 0) {
 380                         if(errno != EINTR && errno != EAGAIN) {
 381                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 382                                            strerror(errno));
 383                                 cp_trace();
 384                                 dump_connections();
 385                                 return 1;
 386                         }
 387
 388                         continue;
 389                 }
 390
 391                 check_network_activity(&readset, &writeset);
 392
 393                 if(do_purge) {
 394                         purge();
 395                         do_purge = false;
 396                 }
 397
 398                 /* Let's check if everybody is still alive */
 399
 400                 if(last_ping_check + pingtimeout < now) {
 401                         check_dead_connections();
 402                         last_ping_check = now;
 403
 404                         if(routing_mode == RMODE_SWITCH)
 405                                 age_subnets();
 406
 407                         age_past_requests();
 408
 409                         /* Should we regenerate our key? */
 410
 411                         if(keyexpires < now) {
 412                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 413
 414                                 RAND_pseudo_bytes((unsigned char *)myself->key, myself->keylength);
 415                                 if(myself->cipher)
 416                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, (unsigned char *)myself->key, (unsigned char *)myself->key + myself->cipher->key_len);
 417                                 send_key_changed(broadcast, myself);
 418                                 keyexpires = now + keylifetime;
 419                         }
 420                 }
 421
 422
 423                 while((event = get_expired_event())) {
 424                         event->handler(event->data);
 425                         free(event);
 426                 }
 427
 428                 if(sigalrm) {
 429                         logger(LOG_INFO, _("Flushing event queue"));
 430
 431                         while(event_tree->head) {
 432                                 event = event_tree->head->data;
 433                                 event->handler(event->data);
 434                                 event_del(event);
 435                         }
 436                         sigalrm = false;
 437                 }
 438
 439                 if(sighup) {
 440                         connection_t *c;
 441                         avl_node_t *node;
 442                         char *fname;
 443                         struct stat s;
 444
 445                         sighup = false;
 446
 447                         /* Reread our own configuration file */
 448
 449                         exit_configuration(&config_tree);
 450                         init_configuration(&config_tree);
 451
 452                         if(!read_server_config()) {
 453                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 454                                 return 1;
 455                         }
 456
 457                         /* Close connections to hosts that have a changed or deleted host config file */
 458
 459                         for(node = connection_tree->head; node; node = node->next) {
 460                                 c = node->data;
 461
 462                                 if(c->outgoing) {
 463                                         free(c->outgoing->name);
 464                                         freeaddrinfo(c->outgoing->ai);
 465                                         free(c->outgoing);
 466                                         c->outgoing = NULL;
 467                                 }
 468
 469                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 470                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 471                                         terminate_connection(c, c->status.active);
 472                                 free(fname);
 473                         }
 474
 475                         last_config_check = now;
 476
 477                         /* Try to make outgoing connections */
 478
 479                         try_outgoing_connections();
 480                 }
 481         }
 482
 483         return 0;
 484 }