www.tinc-vpn.org Git - tinc/blob - src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2003 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000-2003 Guus Sliepen <guus@sliepen.eu.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: net.c,v 1.40 2003/08/24 20:38:24 guus Exp $
  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 = (node_t *) 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 = (subnet_t *) snode->data;
  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 = (edge_t *) enode->data;
  82                                 send_del_edge(broadcast, e);
  83                                 edge_del(e);
  84                         }
  85                 }
  86         }
  87
  88         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  89
  90         for(nnode = node_tree->head; nnode; nnode = nnext) {
  91                 nnext = nnode->next;
  92                 n = (node_t *) nnode->data;
  93
  94                 if(!n->status.reachable) {
  95                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  96                                 enext = enode->next;
  97                                 e = (edge_t *) enode->data;
  98
  99                                 if(e->to == n)
 100                                         break;
 101                         }
 102
 103                         if(!enode)
 104                                 node_del(n);
 105                 }
 106         }
 107 }
 108
 109 /*
 110   put all file descriptors in an fd_set array
 111   While we're at it, purge stuff that needs to be removed.
 112 */
 113 static int build_fdset(fd_set * fs)
 114 {
 115         avl_node_t *node, *next;
 116         connection_t *c;
 117         int i, max = 0;
 118
 119         cp();
 120
 121         FD_ZERO(fs);
 122
 123         for(node = connection_tree->head; node; node = next) {
 124                 next = node->next;
 125                 c = (connection_t *) node->data;
 126
 127                 if(c->status.remove) {
 128                         connection_del(c);
 129                         if(!connection_tree->head)
 130                                 purge();
 131                 } else {
 132                         FD_SET(c->socket, fs);
 133                         if(c->socket > max)
 134                                 max = c->socket;
 135                 }
 136         }
 137
 138         for(i = 0; i < listen_sockets; i++) {
 139                 FD_SET(listen_socket[i].tcp, fs);
 140                 if(listen_socket[i].tcp > max)
 141                         max = listen_socket[i].tcp;
 142                 FD_SET(listen_socket[i].udp, fs);
 143                 if(listen_socket[i].udp > max)
 144                         max = listen_socket[i].udp;
 145         }
 146
 147         FD_SET(device_fd, fs);
 148         if(device_fd > max)
 149                 max = device_fd;
 150
 151         return max;
 152 }
 153
 154 /*
 155   Terminate a connection:
 156   - Close the socket
 157   - Remove associated edge and tell other connections about it if report = true
 158   - Check if we need to retry making an outgoing connection
 159   - Deactivate the host
 160 */
 161 void terminate_connection(connection_t *c, bool report)
 162 {
 163         cp();
 164
 165         if(c->status.remove)
 166                 return;
 167
 168         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 169                            c->name, c->hostname);
 170
 171         c->status.remove = true;
 172         c->status.active = false;
 173
 174         if(c->node)
 175                 c->node->connection = NULL;
 176
 177         if(c->socket)
 178                 closesocket(c->socket);
 179
 180         if(c->edge) {
 181                 if(report)
 182                         send_del_edge(broadcast, c->edge);
 183
 184                 edge_del(c->edge);
 185
 186                 /* Run MST and SSSP algorithms */
 187
 188                 graph();
 189         }
 190
 191         /* Check if this was our outgoing connection */
 192
 193         if(c->outgoing) {
 194                 retry_outgoing(c->outgoing);
 195                 c->outgoing = NULL;
 196         }
 197 }
 198
 199 /*
 200   Check if the other end is active.
 201   If we have sent packets, but didn't receive any,
 202   then possibly the other end is dead. We send a
 203   PING request over the meta connection. If the other
 204   end does not reply in time, we consider them dead
 205   and close the connection.
 206 */
 207 static void check_dead_connections(void)
 208 {
 209         avl_node_t *node, *next;
 210         connection_t *c;
 211
 212         cp();
 213
 214         for(node = connection_tree->head; node; node = next) {
 215                 next = node->next;
 216                 c = (connection_t *) node->data;
 217
 218                 if(c->last_ping_time + pingtimeout < now) {
 219                         if(c->status.active) {
 220                                 if(c->status.pinged) {
 221                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 222                                                            c->name, c->hostname);
 223                                         c->status.timeout = true;
 224                                         terminate_connection(c, true);
 225                                 } else {
 226                                         send_ping(c);
 227                                 }
 228                         } else {
 229                                 if(c->status.remove) {
 230                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 231                                                    c->name, c->hostname, *(uint32_t *)&c->status);
 232                                         connection_del(c);
 233                                         continue;
 234                                 }
 235                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 236                                                    c->name, c->hostname);
 237                                 terminate_connection(c, false);
 238                         }
 239                 }
 240         }
 241 }
 242
 243 /*
 244   check all connections to see if anything
 245   happened on their sockets
 246 */
 247 static void check_network_activity(fd_set * f)
 248 {
 249         connection_t *c;
 250         avl_node_t *node;
 251         int result, i;
 252         int len = sizeof(result);
 253         vpn_packet_t packet;
 254
 255         cp();
 256
 257         if(FD_ISSET(device_fd, f)) {
 258                 if(read_packet(&packet))
 259                         route_outgoing(&packet);
 260         }
 261
 262         for(node = connection_tree->head; node; node = node->next) {
 263                 c = (connection_t *) node->data;
 264
 265                 if(c->status.remove)
 266                         continue;
 267
 268                 if(FD_ISSET(c->socket, f)) {
 269                         if(c->status.connecting) {
 270                                 c->status.connecting = false;
 271                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 272
 273                                 if(!result)
 274                                         finish_connecting(c);
 275                                 else {
 276                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 277                                                            _("Error while connecting to %s (%s): %s"),
 278                                                            c->name, c->hostname, strerror(result));
 279                                         closesocket(c->socket);
 280                                         do_outgoing_connection(c);
 281                                         continue;
 282                                 }
 283                         }
 284
 285                         if(!receive_meta(c)) {
 286                                 terminate_connection(c, c->status.active);
 287                                 continue;
 288                         }
 289                 }
 290         }
 291
 292         for(i = 0; i < listen_sockets; i++) {
 293                 if(FD_ISSET(listen_socket[i].udp, f))
 294                         handle_incoming_vpn_data(listen_socket[i].udp);
 295
 296                 if(FD_ISSET(listen_socket[i].tcp, f))
 297                         handle_new_meta_connection(listen_socket[i].tcp);
 298         }
 299 }
 300
 301 /*
 302   this is where it all happens...
 303 */
 304 int main_loop(void)
 305 {
 306         fd_set fset;
 307         struct timeval tv;
 308         int r, maxfd;
 309         time_t last_ping_check, last_config_check;
 310         event_t *event;
 311
 312         cp();
 313
 314         last_ping_check = now;
 315         last_config_check = now;
 316         srand(now);
 317
 318         running = true;
 319
 320         while(running) {
 321                 now = time(NULL);
 322
 323                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 324                 tv.tv_usec = 0;
 325
 326                 maxfd = build_fdset(&fset);
 327
 328                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 329
 330                 if(r < 0) {
 331                         if(errno != EINTR && errno != EAGAIN) {
 332                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 333                                            strerror(errno));
 334                                 cp_trace();
 335                                 dump_connections();
 336                                 return 1;
 337                         }
 338
 339                         continue;
 340                 }
 341
 342                 check_network_activity(&fset);
 343
 344                 if(do_purge) {
 345                         purge();
 346                         do_purge = false;
 347                 }
 348
 349                 /* Let's check if everybody is still alive */
 350
 351                 if(last_ping_check + pingtimeout < now) {
 352                         check_dead_connections();
 353                         last_ping_check = now;
 354
 355                         if(routing_mode == RMODE_SWITCH)
 356                                 age_mac();
 357
 358                         age_past_requests();
 359
 360                         /* Should we regenerate our key? */
 361
 362                         if(keyexpires < now) {
 363                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 364
 365                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 366                                 if(myself->cipher)
 367                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 368                                 send_key_changed(broadcast, myself);
 369                                 keyexpires = now + keylifetime;
 370                         }
 371                 }
 372
 373
 374                 while((event = get_expired_event())) {
 375                         event->handler(event->data);
 376                         free(event);
 377                 }
 378
 379                 if(sigalrm) {
 380                         logger(LOG_INFO, _("Flushing event queue"));
 381
 382                         while(event_tree->head) {
 383                                 event = (event_t *) event_tree->head->data;
 384                                 event->handler(event->data);
 385                                 event_del(event);
 386                         }
 387                         sigalrm = false;
 388                 }
 389
 390                 if(sighup) {
 391                         connection_t *c;
 392                         avl_node_t *node;
 393                         char *fname;
 394                         struct stat s;
 395
 396                         sighup = false;
 397
 398                         /* Reread our own configuration file */
 399
 400                         exit_configuration(&config_tree);
 401                         init_configuration(&config_tree);
 402
 403                         if(!read_server_config()) {
 404                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 405                                 return 1;
 406                         }
 407
 408                         /* Close connections to hosts that have a changed or deleted host config file */
 409
 410                         for(node = connection_tree->head; node; node = node->next) {
 411                                 c = (connection_t *) node->data;
 412
 413                                 if(c->outgoing) {
 414                                         free(c->outgoing->name);
 415                                         freeaddrinfo(c->outgoing->ai);
 416                                         free(c->outgoing);
 417                                         c->outgoing = NULL;
 418                                 }
 419
 420                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 421                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 422                                         terminate_connection(c, c->status.active);
 423                                 free(fname);
 424                         }
 425
 426                         last_config_check = now;
 427
 428                         /* Try to make outgoing connections */
 429
 430                         try_outgoing_connections();
 431                 }
 432         }
 433
 434         return 0;
 435 }