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 "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 {
  52         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  53         node_t *n;
  54         edge_t *e;
  55         subnet_t *s;
  56
  57         cp();
  58
  59         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  60
  61         /* Remove all edges and subnets owned by unreachable nodes. */
  62
  63         for(nnode = node_tree->head; nnode; nnode = nnext) {
  64                 nnext = nnode->next;
  65                 n = nnode->data;
  66
  67                 if(!n->status.reachable) {
  68                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  69                                            n->hostname);
  70
  71                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  72                                 snext = snode->next;
  73                                 s = snode->data;
  74                                 if(!tunnelserver)
  75                                         send_del_subnet(broadcast, s);
  76                                 subnet_del(n, s);
  77                         }
  78
  79                         for(enode = n->edge_tree->head; enode; enode = enext) {
  80                                 enext = enode->next;
  81                                 e = enode->data;
  82                                 if(!tunnelserver)
  83                                         send_del_edge(broadcast, e);
  84                                 edge_del(e);
  85                         }
  86                 }
  87         }
  88
  89         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  90
  91         for(nnode = node_tree->head; nnode; nnode = nnext) {
  92                 nnext = nnode->next;
  93                 n = nnode->data;
  94
  95                 if(!n->status.reachable) {
  96                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  97                                 enext = enode->next;
  98                                 e = enode->data;
  99
 100                                 if(e->to == n)
 101                                         break;
 102                         }
 103
 104                         if(!enode)
 105                                 node_del(n);
 106                 }
 107         }
 108 }
 109
 110 /*
 111   put all file descriptors into events
 112   While we're at it, purge stuf that needs to be removed.
 113 */
 114 static int build_fdset(void)
 115 {
 116         avl_node_t *node, *next;
 117         connection_t *c;
 118         int i, max = 0;
 119
 120         cp();
 121
 122         for(node = connection_tree->head; node; node = next) {
 123                 next = node->next;
 124                 c = node->data;
 125
 126                 if(c->status.remove) {
 127                         connection_del(c);
 128                         if(!connection_tree->head)
 129                                 purge();
 130                 }
 131         }
 132
 133         return 0;
 134 }
 135
 136 /*
 137   Terminate a connection:
 138   - Close the socket
 139   - Remove associated edge and tell other connections about it if report = true
 140   - Check if we need to retry making an outgoing connection
 141   - Deactivate the host
 142 */
 143 void terminate_connection(connection_t *c, bool report)
 144 {
 145         cp();
 146
 147         if(c->status.remove)
 148                 return;
 149
 150         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 151                            c->name, c->hostname);
 152
 153         c->status.remove = true;
 154         c->status.active = false;
 155
 156         if(c->node)
 157                 c->node->connection = NULL;
 158
 159         if(c->socket)
 160                 closesocket(c->socket);
 161
 162         event_del(&c->ev);
 163
 164         if(c->edge) {
 165                 if(report && !tunnelserver)
 166                         send_del_edge(broadcast, c->edge);
 167
 168                 edge_del(c->edge);
 169
 170                 /* Run MST and SSSP algorithms */
 171
 172                 graph();
 173
 174                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 175
 176                 if(report && !c->node->status.reachable) {
 177                         edge_t *e;
 178                         e = lookup_edge(c->node, myself);
 179                         if(e) {
 180                                 if(!tunnelserver)
 181                                         send_del_edge(broadcast, e);
 182                                 edge_del(e);
 183                         }
 184                 }
 185         }
 186
 187         /* Check if this was our outgoing connection */
 188
 189         if(c->outgoing) {
 190                 retry_outgoing(c->outgoing);
 191                 c->outgoing = NULL;
 192         }
 193
 194         free(c->outbuf);
 195         c->outbuf = NULL;
 196         c->outbuflen = 0;
 197         c->outbufsize = 0;
 198         c->outbufstart = 0;
 199 }
 200
 201 /*
 202   Check if the other end is active.
 203   If we have sent packets, but didn't receive any,
 204   then possibly the other end is dead. We send a
 205   PING request over the meta connection. If the other
 206   end does not reply in time, we consider them dead
 207   and close the connection.
 208 */
 209 static void check_dead_connections(void)
 210 {
 211         avl_node_t *node, *next;
 212         connection_t *c;
 213
 214         cp();
 215
 216         for(node = connection_tree->head; node; node = next) {
 217                 next = node->next;
 218                 c = node->data;
 219
 220                 if(c->last_ping_time + pingtimeout < now) {
 221                         if(c->status.active) {
 222                                 if(c->status.pinged) {
 223                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 224                                                            c->name, c->hostname, now - c->last_ping_time);
 225                                         c->status.timeout = true;
 226                                         terminate_connection(c, true);
 227                                 } else if(c->last_ping_time + pinginterval < now) {
 228                                         send_ping(c);
 229                                 }
 230                         } else {
 231                                 if(c->status.remove) {
 232                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 233                                                    c->name, c->hostname, c->status.value);
 234                                         connection_del(c);
 235                                         continue;
 236                                 }
 237                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 238                                                    c->name, c->hostname);
 239                                 if(c->status.connecting) {
 240                                         c->status.connecting = false;
 241                                         closesocket(c->socket);
 242                                         do_outgoing_connection(c);
 243                                 } else {
 244                                         terminate_connection(c, false);
 245                                 }
 246                         }
 247                 }
 248
 249                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 250                         if(c->status.active) {
 251                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 252                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 253                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 254                                 c->status.timeout = true;
 255                                 terminate_connection(c, true);
 256                         }
 257                 }
 258         }
 259 }
 260
 261 void handle_meta_connection_data(int fd, short events, void *data)
 262 {
 263         connection_t *c = data;
 264         int result;
 265         socklen_t len = sizeof(result);
 266
 267         if (c->status.remove)
 268                 return;
 269
 270         if(c->status.connecting) {
 271                 c->status.connecting = false;
 272                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 273
 274                 if(!result)
 275                         finish_connecting(c);
 276                 else {
 277                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 278                                            _("Error while connecting to %s (%s): %s"),
 279                                            c->name, c->hostname, strerror(result));
 280                         closesocket(c->socket);
 281                         do_outgoing_connection(c);
 282                         return;
 283                 }
 284         }
 285
 286         if (!receive_meta(c)) {
 287                 terminate_connection(c, c->status.active);
 288                 return;
 289         }
 290 }
 291
 292 static void dummy(int a, short b, void *c)
 293 {
 294 }
 295
 296 void sighup_handler(int signal, short events, void *data) {
 297         connection_t *c;
 298         avl_node_t *node;
 299         char *fname;
 300         struct stat s;
 301         static time_t last_config_check = 0;
 302
 303         /* Reread our own configuration file */
 304
 305         exit_configuration(&config_tree);
 306         init_configuration(&config_tree);
 307
 308         if(!read_server_config()) {
 309                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 310                 event_loopexit(NULL);
 311                 return;
 312         }
 313
 314         /* Close connections to hosts that have a changed or deleted host config file */
 315
 316         for(node = connection_tree->head; node; node = node->next) {
 317                 c = node->data;
 318
 319                 if(c->outgoing) {
 320                         free(c->outgoing->name);
 321                         if(c->outgoing->ai)
 322                                 freeaddrinfo(c->outgoing->ai);
 323                         free(c->outgoing);
 324                         c->outgoing = NULL;
 325                 }
 326
 327                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 328                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 329                         terminate_connection(c, c->status.active);
 330                 free(fname);
 331         }
 332
 333         last_config_check = time(NULL);
 334
 335         /* Try to make outgoing connections */
 336
 337         try_outgoing_connections();
 338 }
 339
 340 /*
 341   this is where it all happens...
 342 */
 343 int main_loop(void)
 344 {
 345         struct timeval tv;
 346         int r;
 347         time_t last_ping_check;
 348         struct event timeout;
 349         struct event sighup_event;
 350
 351         cp();
 352
 353         signal_set(&sighup_event, SIGHUP, sighup_handler, NULL);
 354         signal_add(&sighup_event, NULL);
 355
 356         last_ping_check = now;
 357
 358         srand(now);
 359
 360         running = true;
 361
 362         while(running) {
 363                 now = time(NULL);
 364
 365         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 366                 tv.tv_sec = 1;
 367                 tv.tv_usec = 0;
 368
 369                 /* XXX: libevent transition: old timeout code in this loop */
 370                 timeout_set(&timeout, dummy, NULL);
 371                 timeout_add(&timeout, &tv);
 372
 373                 r = build_fdset();
 374                 if(r < 0) {
 375                         logger(LOG_ERR, _("Error building fdset: %s"), strerror(errno));
 376                         cp_trace();
 377                         dump_connections();
 378                         return 1;
 379                 }
 380
 381                 r = event_loop(EVLOOP_ONCE);
 382                 now = time(NULL);
 383                 if(r < 0) {
 384                         logger(LOG_ERR, _("Error while waiting for input: %s"),
 385                                    strerror(errno));
 386                         cp_trace();
 387                         dump_connections();
 388                         return 1;
 389                 }
 390
 391                 /* XXX: more libevent transition */
 392                 timeout_del(&timeout);
 393
 394                 if(do_purge) {
 395                         purge();
 396                         do_purge = false;
 397                 }
 398
 399                 /* Let's check if everybody is still alive */
 400
 401                 if(last_ping_check + pingtimeout < now) {
 402                         check_dead_connections();
 403                         last_ping_check = now;
 404
 405                         if(routing_mode == RMODE_SWITCH)
 406                                 age_subnets();
 407
 408                         age_past_requests();
 409
 410                         /* Should we regenerate our key? */
 411
 412                         if(keyexpires < now) {
 413                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 414
 415                                 RAND_pseudo_bytes((unsigned char *)myself->key, myself->keylength);
 416                                 if(myself->cipher)
 417                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, (unsigned char *)myself->key, (unsigned char *)myself->key + myself->cipher->key_len);
 418                                 send_key_changed(broadcast, myself);
 419                                 keyexpires = now + keylifetime;
 420                         }
 421                 }
 422
 423                 if(sigalrm) {
 424                         logger(LOG_INFO, _("Flushing event queue"));
 425                         // TODO: do this another way
 426                         sigalrm = false;
 427                 }
 428         }
 429
 430         signal_del(&sighup_event);
 431
 432         return 0;
 433 }