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                 } else {
 132                         short events = EV_READ;
 133                         if(c->outbuflen > 0)
 134                                 events |= EV_WRITE;
 135                         event_del(&c->ev);
 136                         event_set(&c->ev, c->socket, events,
 137                                           handle_meta_connection_data, c);
 138                         if (event_add(&c->ev, NULL) < 0)
 139                                 return -1;
 140                 }
 141         }
 142         return 0;
 143 }
 144
 145 /*
 146   Terminate a connection:
 147   - Close the socket
 148   - Remove associated edge and tell other connections about it if report = true
 149   - Check if we need to retry making an outgoing connection
 150   - Deactivate the host
 151 */
 152 void terminate_connection(connection_t *c, bool report)
 153 {
 154         cp();
 155
 156         if(c->status.remove)
 157                 return;
 158
 159         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 160                            c->name, c->hostname);
 161
 162         c->status.remove = true;
 163         c->status.active = false;
 164
 165         if(c->node)
 166                 c->node->connection = NULL;
 167
 168         if(c->socket)
 169                 closesocket(c->socket);
 170
 171         if(c->edge) {
 172                 if(report && !tunnelserver)
 173                         send_del_edge(broadcast, c->edge);
 174
 175                 edge_del(c->edge);
 176
 177                 /* Run MST and SSSP algorithms */
 178
 179                 graph();
 180
 181                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 182
 183                 if(report && !c->node->status.reachable) {
 184                         edge_t *e;
 185                         e = lookup_edge(c->node, myself);
 186                         if(e) {
 187                                 if(!tunnelserver)
 188                                         send_del_edge(broadcast, e);
 189                                 edge_del(e);
 190                         }
 191                 }
 192         }
 193
 194         /* Check if this was our outgoing connection */
 195
 196         if(c->outgoing) {
 197                 retry_outgoing(c->outgoing);
 198                 c->outgoing = NULL;
 199         }
 200
 201         free(c->outbuf);
 202         c->outbuf = NULL;
 203         c->outbuflen = 0;
 204         c->outbufsize = 0;
 205         c->outbufstart = 0;
 206 }
 207
 208 /*
 209   Check if the other end is active.
 210   If we have sent packets, but didn't receive any,
 211   then possibly the other end is dead. We send a
 212   PING request over the meta connection. If the other
 213   end does not reply in time, we consider them dead
 214   and close the connection.
 215 */
 216 static void check_dead_connections(void)
 217 {
 218         avl_node_t *node, *next;
 219         connection_t *c;
 220
 221         cp();
 222
 223         for(node = connection_tree->head; node; node = next) {
 224                 next = node->next;
 225                 c = node->data;
 226
 227                 if(c->last_ping_time + pingtimeout < now) {
 228                         if(c->status.active) {
 229                                 if(c->status.pinged) {
 230                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 231                                                            c->name, c->hostname, now - c->last_ping_time);
 232                                         c->status.timeout = true;
 233                                         terminate_connection(c, true);
 234                                 } else if(c->last_ping_time + pinginterval < now) {
 235                                         send_ping(c);
 236                                 }
 237                         } else {
 238                                 if(c->status.remove) {
 239                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 240                                                    c->name, c->hostname, c->status.value);
 241                                         connection_del(c);
 242                                         continue;
 243                                 }
 244                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 245                                                    c->name, c->hostname);
 246                                 if(c->status.connecting) {
 247                                         c->status.connecting = false;
 248                                         closesocket(c->socket);
 249                                         do_outgoing_connection(c);
 250                                 } else {
 251                                         terminate_connection(c, false);
 252                                 }
 253                         }
 254                 }
 255
 256                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 257                         if(c->status.active) {
 258                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 259                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 260                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 261                                 c->status.timeout = true;
 262                                 terminate_connection(c, true);
 263                         }
 264                 }
 265         }
 266 }
 267
 268 void handle_meta_connection_data(int fd, short events, void *data)
 269 {
 270         connection_t *c = data;
 271         int result;
 272         socklen_t len = sizeof(result);
 273
 274         if (c->status.remove)
 275                 return;
 276
 277         if (events & EV_READ) {
 278                 if(c->status.connecting) {
 279                         c->status.connecting = false;
 280                         getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 281
 282                         if(!result)
 283                                 finish_connecting(c);
 284                         else {
 285                                 ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 286                                                    _("Error while connecting to %s (%s): %s"),
 287                                                    c->name, c->hostname, strerror(result));
 288                                 closesocket(c->socket);
 289                                 do_outgoing_connection(c);
 290                                 return;
 291                         }
 292                 }
 293
 294                 if (!receive_meta(c)) {
 295                         terminate_connection(c, c->status.active);
 296                         return;
 297                 }
 298         }
 299
 300         if (events & EV_WRITE) {
 301                 if(!flush_meta(c)) {
 302                         terminate_connection(c, c->status.active);
 303                 }
 304         }
 305 }
 306
 307 static void dummy(int a, short b, void *c)
 308 {
 309 }
 310
 311 /*
 312   this is where it all happens...
 313 */
 314 int main_loop(void)
 315 {
 316         struct timeval tv;
 317         int r;
 318         time_t last_ping_check, last_config_check, last_graph_dump;
 319         tevent_t *event;
 320         struct event timeout;
 321
 322         cp();
 323
 324         last_ping_check = now;
 325         last_config_check = now;
 326         last_graph_dump = now;
 327
 328         srand(now);
 329
 330         running = true;
 331
 332         while(running) {
 333                 now = time(NULL);
 334
 335         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 336                 tv.tv_sec = 1;
 337                 tv.tv_usec = 0;
 338
 339                 /* XXX: libevent transition: old timeout code in this loop */
 340                 timeout_set(&timeout, dummy, NULL);
 341                 timeout_add(&timeout, &tv);
 342
 343                 r = build_fdset();
 344                 if(r < 0) {
 345                         logger(LOG_ERR, _("Error building fdset: %s"), strerror(errno));
 346                         cp_trace();
 347                         dump_connections();
 348                         return 1;
 349                 }
 350
 351                 r = event_loop(EVLOOP_ONCE);
 352                 now = time(NULL);
 353                 if(r < 0) {
 354                         logger(LOG_ERR, _("Error while waiting for input: %s"),
 355                                    strerror(errno));
 356                         cp_trace();
 357                         dump_connections();
 358                         return 1;
 359                 }
 360
 361                 /* XXX: more libevent transition */
 362                 timeout_del(&timeout);
 363
 364                 if(do_purge) {
 365                         purge();
 366                         do_purge = false;
 367                 }
 368
 369                 /* Let's check if everybody is still alive */
 370
 371                 if(last_ping_check + pingtimeout < now) {
 372                         check_dead_connections();
 373                         last_ping_check = now;
 374
 375                         if(routing_mode == RMODE_SWITCH)
 376                                 age_subnets();
 377
 378                         age_past_requests();
 379
 380                         /* Should we regenerate our key? */
 381
 382                         if(keyexpires < now) {
 383                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 384
 385                                 RAND_pseudo_bytes((unsigned char *)myself->key, myself->keylength);
 386                                 if(myself->cipher)
 387                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, (unsigned char *)myself->key, (unsigned char *)myself->key + myself->cipher->key_len);
 388                                 send_key_changed(broadcast, myself);
 389                                 keyexpires = now + keylifetime;
 390                         }
 391                 }
 392
 393
 394                 while((event = get_expired_tevent())) {
 395                         event->handler(event->data);
 396                         free_tevent(event);
 397                 }
 398
 399                 if(sigalrm) {
 400                         logger(LOG_INFO, _("Flushing event queue"));
 401                         flush_tevents();
 402                         sigalrm = false;
 403                 }
 404
 405                 if(sighup) {
 406                         connection_t *c;
 407                         avl_node_t *node;
 408                         char *fname;
 409                         struct stat s;
 410
 411                         sighup = false;
 412
 413                         /* Reread our own configuration file */
 414
 415                         exit_configuration(&config_tree);
 416                         init_configuration(&config_tree);
 417
 418                         if(!read_server_config()) {
 419                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 420                                 return 1;
 421                         }
 422
 423                         /* Close connections to hosts that have a changed or deleted host config file */
 424
 425                         for(node = connection_tree->head; node; node = node->next) {
 426                                 c = node->data;
 427
 428                                 if(c->outgoing) {
 429                                         free(c->outgoing->name);
 430                                         if(c->outgoing->ai)
 431                                                 freeaddrinfo(c->outgoing->ai);
 432                                         free(c->outgoing);
 433                                         c->outgoing = NULL;
 434                                 }
 435
 436                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 437                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 438                                         terminate_connection(c, c->status.active);
 439                                 free(fname);
 440                         }
 441
 442                         last_config_check = now;
 443
 444                         /* Try to make outgoing connections */
 445
 446                         try_outgoing_connections();
 447                 }
 448
 449                 /* Dump graph if wanted every 60 seconds*/
 450
 451                 if(last_graph_dump + 60 < now) {
 452                         dump_graph();
 453                         last_graph_dump = now;
 454                 }
 455         }
 456
 457         return 0;
 458 }