src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans <ivo@tinc-vpn.org>,
   4                   2000-2005 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 * fs)
 116 {
 117         avl_node_t *node, *next;
 118         connection_t *c;
 119         int i, max = 0;
 120
 121         cp();
 122
 123         FD_ZERO(fs);
 124
 125         for(node = connection_tree->head; node; node = next) {
 126                 next = node->next;
 127                 c = node->data;
 128
 129                 if(c->status.remove) {
 130                         connection_del(c);
 131                         if(!connection_tree->head)
 132                                 purge();
 133                 } else {
 134                         FD_SET(c->socket, fs);
 135                         if(c->socket > max)
 136                                 max = c->socket;
 137                 }
 138         }
 139
 140         for(i = 0; i < listen_sockets; i++) {
 141                 FD_SET(listen_socket[i].tcp, fs);
 142                 if(listen_socket[i].tcp > max)
 143                         max = listen_socket[i].tcp;
 144                 FD_SET(listen_socket[i].udp, fs);
 145                 if(listen_socket[i].udp > max)
 146                         max = listen_socket[i].udp;
 147         }
 148
 149         FD_SET(device_fd, fs);
 150         if(device_fd > max)
 151                 max = device_fd;
 152
 153         return max;
 154 }
 155
 156 /*
 157   Terminate a connection:
 158   - Close the socket
 159   - Remove associated edge and tell other connections about it if report = true
 160   - Check if we need to retry making an outgoing connection
 161   - Deactivate the host
 162 */
 163 void terminate_connection(connection_t *c, bool report)
 164 {
 165         cp();
 166
 167         if(c->status.remove)
 168                 return;
 169
 170         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 171                            c->name, c->hostname);
 172
 173         c->status.remove = true;
 174         c->status.active = false;
 175
 176         if(c->node)
 177                 c->node->connection = NULL;
 178
 179         if(c->socket)
 180                 closesocket(c->socket);
 181
 182         if(c->edge) {
 183                 if(report && !tunnelserver)
 184                         send_del_edge(broadcast, c->edge);
 185
 186                 edge_del(c->edge);
 187
 188                 /* Run MST and SSSP algorithms */
 189
 190                 graph();
 191
 192                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 193
 194                 if(report && !c->node->status.reachable) {
 195                         edge_t *e;
 196                         e = lookup_edge(c->node, myself);
 197                         if(e) {
 198                                 if(!tunnelserver)
 199                                         send_del_edge(broadcast, e);
 200                                 edge_del(e);
 201                         }
 202                 }
 203         }
 204
 205         /* Check if this was our outgoing connection */
 206
 207         if(c->outgoing) {
 208                 retry_outgoing(c->outgoing);
 209                 c->outgoing = NULL;
 210         }
 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 {
 223         avl_node_t *node, *next;
 224         connection_t *c;
 225
 226         cp();
 227
 228         for(node = connection_tree->head; node; node = next) {
 229                 next = node->next;
 230                 c = node->data;
 231
 232                 if(c->last_ping_time + pingtimeout < now) {
 233                         if(c->status.active) {
 234                                 if(c->status.pinged) {
 235                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 236                                                            c->name, c->hostname);
 237                                         c->status.timeout = true;
 238                                         terminate_connection(c, true);
 239                                 } else {
 240                                         send_ping(c);
 241                                 }
 242                         } else {
 243                                 if(c->status.remove) {
 244                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 245                                                    c->name, c->hostname, *(uint32_t *)&c->status);
 246                                         connection_del(c);
 247                                         continue;
 248                                 }
 249                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 250                                                    c->name, c->hostname);
 251                                 if(c->status.connecting) {
 252                                         c->status.connecting = false;
 253                                         closesocket(c->socket);
 254                                         do_outgoing_connection(c);
 255                                 } else {
 256                                         terminate_connection(c, false);
 257                                 }
 258                         }
 259                 }
 260         }
 261 }
 262
 263 /*
 264   check all connections to see if anything
 265   happened on their sockets
 266 */
 267 static void check_network_activity(fd_set * f)
 268 {
 269         connection_t *c;
 270         avl_node_t *node;
 271         int result, i;
 272         int len = sizeof(result);
 273         vpn_packet_t packet;
 274
 275         cp();
 276
 277         if(FD_ISSET(device_fd, f)) {
 278                 if(read_packet(&packet))
 279                         route(myself, &packet);
 280         }
 281
 282         for(node = connection_tree->head; node; node = node->next) {
 283                 c = node->data;
 284
 285                 if(c->status.remove)
 286                         continue;
 287
 288                 if(FD_ISSET(c->socket, f)) {
 289                         if(c->status.connecting) {
 290                                 c->status.connecting = false;
 291                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 292
 293                                 if(!result)
 294                                         finish_connecting(c);
 295                                 else {
 296                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 297                                                            _("Error while connecting to %s (%s): %s"),
 298                                                            c->name, c->hostname, strerror(result));
 299                                         closesocket(c->socket);
 300                                         do_outgoing_connection(c);
 301                                         continue;
 302                                 }
 303                         }
 304
 305                         if(!receive_meta(c)) {
 306                                 terminate_connection(c, c->status.active);
 307                                 continue;
 308                         }
 309                 }
 310         }
 311
 312         for(i = 0; i < listen_sockets; i++) {
 313                 if(FD_ISSET(listen_socket[i].udp, f))
 314                         handle_incoming_vpn_data(listen_socket[i].udp);
 315
 316                 if(FD_ISSET(listen_socket[i].tcp, f))
 317                         handle_new_meta_connection(listen_socket[i].tcp);
 318         }
 319 }
 320
 321 /*
 322   this is where it all happens...
 323 */
 324 int main_loop(void)
 325 {
 326         fd_set fset;
 327         struct timeval tv;
 328         int r, maxfd;
 329         time_t last_ping_check, last_config_check;
 330         event_t *event;
 331
 332         cp();
 333
 334         last_ping_check = now;
 335         last_config_check = now;
 336         srand(now);
 337
 338         running = true;
 339
 340         while(running) {
 341                 now = time(NULL);
 342
 343         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 344                 tv.tv_sec = 1;
 345                 tv.tv_usec = 0;
 346
 347                 maxfd = build_fdset(&fset);
 348
 349                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 350
 351                 if(r < 0) {
 352                         if(errno != EINTR && errno != EAGAIN) {
 353                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 354                                            strerror(errno));
 355                                 cp_trace();
 356                                 dump_connections();
 357                                 return 1;
 358                         }
 359
 360                         continue;
 361                 }
 362
 363                 check_network_activity(&fset);
 364
 365                 if(do_purge) {
 366                         purge();
 367                         do_purge = false;
 368                 }
 369
 370                 /* Let's check if everybody is still alive */
 371
 372                 if(last_ping_check + pingtimeout < now) {
 373                         check_dead_connections();
 374                         last_ping_check = now;
 375
 376                         if(routing_mode == RMODE_SWITCH)
 377                                 age_subnets();
 378
 379                         age_past_requests();
 380
 381                         /* Should we regenerate our key? */
 382
 383                         if(keyexpires < now) {
 384                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 385
 386                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 387                                 if(myself->cipher)
 388                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 389                                 send_key_changed(broadcast, myself);
 390                                 keyexpires = now + keylifetime;
 391                         }
 392                 }
 393
 394
 395                 while((event = get_expired_event())) {
 396                         event->handler(event->data);
 397                         free(event);
 398                 }
 399
 400                 if(sigalrm) {
 401                         logger(LOG_INFO, _("Flushing event queue"));
 402
 403                         while(event_tree->head) {
 404                                 event = event_tree->head->data;
 405                                 event->handler(event->data);
 406                                 event_del(event);
 407                         }
 408                         sigalrm = false;
 409                 }
 410
 411                 if(sighup) {
 412                         connection_t *c;
 413                         avl_node_t *node;
 414                         char *fname;
 415                         struct stat s;
 416
 417                         sighup = false;
 418
 419                         /* Reread our own configuration file */
 420
 421                         exit_configuration(&config_tree);
 422                         init_configuration(&config_tree);
 423
 424                         if(!read_server_config()) {
 425                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 426                                 return 1;
 427                         }
 428
 429                         /* Close connections to hosts that have a changed or deleted host config file */
 430
 431                         for(node = connection_tree->head; node; node = node->next) {
 432                                 c = node->data;
 433
 434                                 if(c->outgoing) {
 435                                         free(c->outgoing->name);
 436                                         freeaddrinfo(c->outgoing->ai);
 437                                         free(c->outgoing);
 438                                         c->outgoing = NULL;
 439                                 }
 440
 441                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 442                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 443                                         terminate_connection(c, c->status.active);
 444                                 free(fname);
 445                         }
 446
 447                         last_config_check = now;
 448
 449                         /* Try to make outgoing connections */
 450
 451                         try_outgoing_connections();
 452                 }
 453         }
 454
 455         return 0;
 456 }