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                   2000-2006 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 "tevent.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 into events
 113   While we're at it, purge stuf that needs to be removed.
 114 */
 115 static int build_fdset(void)
 116 {
 117         avl_node_t *node, *next;
 118         connection_t *c;
 119         int i, max = 0;
 120
 121         cp();
 122
 123         for(node = connection_tree->head; node; node = next) {
 124                 next = node->next;
 125                 c = node->data;
 126
 127                 if(c->status.remove) {
 128                         connection_del(c);
 129                         if(!connection_tree->head)
 130                                 purge();
 131                 }
 132         }
 133
 134         return 0;
 135 }
 136
 137 /*
 138   Terminate a connection:
 139   - Close the socket
 140   - Remove associated edge and tell other connections about it if report = true
 141   - Check if we need to retry making an outgoing connection
 142   - Deactivate the host
 143 */
 144 void terminate_connection(connection_t *c, bool report)
 145 {
 146         cp();
 147
 148         if(c->status.remove)
 149                 return;
 150
 151         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 152                            c->name, c->hostname);
 153
 154         c->status.remove = true;
 155         c->status.active = false;
 156
 157         if(c->node)
 158                 c->node->connection = NULL;
 159
 160         if(c->socket)
 161                 closesocket(c->socket);
 162
 163         event_del(&c->ev);
 164
 165         if(c->edge) {
 166                 if(report && !tunnelserver)
 167                         send_del_edge(broadcast, c->edge);
 168
 169                 edge_del(c->edge);
 170
 171                 /* Run MST and SSSP algorithms */
 172
 173                 graph();
 174
 175                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 176
 177                 if(report && !c->node->status.reachable) {
 178                         edge_t *e;
 179                         e = lookup_edge(c->node, myself);
 180                         if(e) {
 181                                 if(!tunnelserver)
 182                                         send_del_edge(broadcast, e);
 183                                 edge_del(e);
 184                         }
 185                 }
 186         }
 187
 188         /* Check if this was our outgoing connection */
 189
 190         if(c->outgoing) {
 191                 retry_outgoing(c->outgoing);
 192                 c->outgoing = NULL;
 193         }
 194
 195         free(c->outbuf);
 196         c->outbuf = NULL;
 197         c->outbuflen = 0;
 198         c->outbufsize = 0;
 199         c->outbufstart = 0;
 200 }
 201
 202 /*
 203   Check if the other end is active.
 204   If we have sent packets, but didn't receive any,
 205   then possibly the other end is dead. We send a
 206   PING request over the meta connection. If the other
 207   end does not reply in time, we consider them dead
 208   and close the connection.
 209 */
 210 static void check_dead_connections(void)
 211 {
 212         avl_node_t *node, *next;
 213         connection_t *c;
 214
 215         cp();
 216
 217         for(node = connection_tree->head; node; node = next) {
 218                 next = node->next;
 219                 c = node->data;
 220
 221                 if(c->last_ping_time + pingtimeout < now) {
 222                         if(c->status.active) {
 223                                 if(c->status.pinged) {
 224                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 225                                                            c->name, c->hostname, now - c->last_ping_time);
 226                                         c->status.timeout = true;
 227                                         terminate_connection(c, true);
 228                                 } else if(c->last_ping_time + pinginterval < now) {
 229                                         send_ping(c);
 230                                 }
 231                         } else {
 232                                 if(c->status.remove) {
 233                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 234                                                    c->name, c->hostname, c->status.value);
 235                                         connection_del(c);
 236                                         continue;
 237                                 }
 238                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 239                                                    c->name, c->hostname);
 240                                 if(c->status.connecting) {
 241                                         c->status.connecting = false;
 242                                         closesocket(c->socket);
 243                                         do_outgoing_connection(c);
 244                                 } else {
 245                                         terminate_connection(c, false);
 246                                 }
 247                         }
 248                 }
 249
 250                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 251                         if(c->status.active) {
 252                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 253                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 254                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 255                                 c->status.timeout = true;
 256                                 terminate_connection(c, true);
 257                         }
 258                 }
 259         }
 260 }
 261
 262 void handle_meta_connection_data(int fd, short events, void *data)
 263 {
 264         connection_t *c = data;
 265         int result;
 266         socklen_t len = sizeof(result);
 267
 268         if (c->status.remove)
 269                 return;
 270
 271         if(c->status.connecting) {
 272                 c->status.connecting = false;
 273                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 274
 275                 if(!result)
 276                         finish_connecting(c);
 277                 else {
 278                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 279                                            _("Error while connecting to %s (%s): %s"),
 280                                            c->name, c->hostname, strerror(result));
 281                         closesocket(c->socket);
 282                         do_outgoing_connection(c);
 283                         return;
 284                 }
 285         }
 286
 287         if (!receive_meta(c)) {
 288                 terminate_connection(c, c->status.active);
 289                 return;
 290         }
 291 }
 292
 293 static void dummy(int a, short b, void *c)
 294 {
 295 }
 296
 297 void sighup_handler(int signal, short events, void *data) {
 298         connection_t *c;
 299         avl_node_t *node;
 300         char *fname;
 301         struct stat s;
 302         static time_t last_config_check = 0;
 303
 304         /* Reread our own configuration file */
 305
 306         exit_configuration(&config_tree);
 307         init_configuration(&config_tree);
 308
 309         if(!read_server_config()) {
 310                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 311                 event_loopexit(NULL);
 312                 return;
 313         }
 314
 315         /* Close connections to hosts that have a changed or deleted host config file */
 316
 317         for(node = connection_tree->head; node; node = node->next) {
 318                 c = node->data;
 319
 320                 if(c->outgoing) {
 321                         free(c->outgoing->name);
 322                         if(c->outgoing->ai)
 323                                 freeaddrinfo(c->outgoing->ai);
 324                         free(c->outgoing);
 325                         c->outgoing = NULL;
 326                 }
 327
 328                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 329                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 330                         terminate_connection(c, c->status.active);
 331                 free(fname);
 332         }
 333
 334         last_config_check = time(NULL);
 335
 336         /* Try to make outgoing connections */
 337
 338         try_outgoing_connections();
 339 }
 340
 341 /*
 342   this is where it all happens...
 343 */
 344 int main_loop(void)
 345 {
 346         struct timeval tv;
 347         int r;
 348         time_t last_ping_check;
 349         tevent_t *event;
 350         struct event timeout;
 351         struct event sighup_event;
 352
 353         cp();
 354
 355         signal_set(&sighup_event, SIGHUP, sighup_handler, NULL);
 356         signal_add(&sighup_event, NULL);
 357
 358         last_ping_check = now;
 359
 360         srand(now);
 361
 362         running = true;
 363
 364         while(running) {
 365                 now = time(NULL);
 366
 367         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 368                 tv.tv_sec = 1;
 369                 tv.tv_usec = 0;
 370
 371                 /* XXX: libevent transition: old timeout code in this loop */
 372                 timeout_set(&timeout, dummy, NULL);
 373                 timeout_add(&timeout, &tv);
 374
 375                 r = build_fdset();
 376                 if(r < 0) {
 377                         logger(LOG_ERR, _("Error building fdset: %s"), strerror(errno));
 378                         cp_trace();
 379                         dump_connections();
 380                         return 1;
 381                 }
 382
 383                 r = event_loop(EVLOOP_ONCE);
 384                 now = time(NULL);
 385                 if(r < 0) {
 386                         logger(LOG_ERR, _("Error while waiting for input: %s"),
 387                                    strerror(errno));
 388                         cp_trace();
 389                         dump_connections();
 390                         return 1;
 391                 }
 392
 393                 /* XXX: more libevent transition */
 394                 timeout_del(&timeout);
 395
 396                 if(do_purge) {
 397                         purge();
 398                         do_purge = false;
 399                 }
 400
 401                 /* Let's check if everybody is still alive */
 402
 403                 if(last_ping_check + pingtimeout < now) {
 404                         check_dead_connections();
 405                         last_ping_check = now;
 406
 407                         if(routing_mode == RMODE_SWITCH)
 408                                 age_subnets();
 409
 410                         age_past_requests();
 411
 412                         /* Should we regenerate our key? */
 413
 414                         if(keyexpires < now) {
 415                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 416
 417                                 RAND_pseudo_bytes((unsigned char *)myself->key, myself->keylength);
 418                                 if(myself->cipher)
 419                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, (unsigned char *)myself->key, (unsigned char *)myself->key + myself->cipher->key_len);
 420                                 send_key_changed(broadcast, myself);
 421                                 keyexpires = now + keylifetime;
 422                         }
 423                 }
 424
 425
 426                 while((event = get_expired_tevent())) {
 427                         event->handler(event->data);
 428                         free_tevent(event);
 429                 }
 430
 431                 if(sigalrm) {
 432                         logger(LOG_INFO, _("Flushing event queue"));
 433                         flush_tevents();
 434                         sigalrm = false;
 435                 }
 436
 437         }
 438
 439         signal_del(&sighup_event);
 440
 441         return 0;
 442 }