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 1.35.4.195 2003/07/29 22:59:00 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
  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         for(nnode = node_tree->head; nnode; nnode = nnext) {
  62                 nnext = nnode->next;
  63                 n = (node_t *) nnode->data;
  64
  65                 if(!n->status.reachable) {
  66                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  67                                            n->hostname);
  68
  69                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  70                                 snext = snode->next;
  71                                 s = (subnet_t *) snode->data;
  72                                 send_del_subnet(broadcast, s);
  73                                 subnet_del(n, s);
  74                         }
  75
  76                         for(enode = n->edge_tree->head; enode; enode = enext) {
  77                                 enext = enode->next;
  78                                 e = (edge_t *) enode->data;
  79                                 send_del_edge(broadcast, e);
  80                                 edge_del(e);
  81                         }
  82
  83                         node_del(n);
  84                 }
  85         }
  86 }
  87
  88 /*
  89   put all file descriptors in an fd_set array
  90   While we're at it, purge stuff that needs to be removed.
  91 */
  92 static int build_fdset(fd_set * fs)
  93 {
  94         avl_node_t *node, *next;
  95         connection_t *c;
  96         int i, max = 0;
  97
  98         cp();
  99
 100         FD_ZERO(fs);
 101
 102         for(node = connection_tree->head; node; node = next) {
 103                 next = node->next;
 104                 c = (connection_t *) node->data;
 105
 106                 if(c->status.remove) {
 107                         connection_del(c);
 108                         if(!connection_tree->head)
 109                                 purge();
 110                 } else {
 111                         FD_SET(c->socket, fs);
 112                         if(c->socket > max)
 113                                 max = c->socket;
 114                 }
 115         }
 116
 117         for(i = 0; i < listen_sockets; i++) {
 118                 FD_SET(listen_socket[i].tcp, fs);
 119                 if(listen_socket[i].tcp > max)
 120                         max = listen_socket[i].tcp;
 121                 FD_SET(listen_socket[i].udp, fs);
 122                 if(listen_socket[i].udp > max)
 123                         max = listen_socket[i].udp;
 124         }
 125
 126         FD_SET(device_fd, fs);
 127         if(device_fd > max)
 128                 max = device_fd;
 129
 130         return max;
 131 }
 132
 133 /*
 134   Terminate a connection:
 135   - Close the socket
 136   - Remove associated edge and tell other connections about it if report = true
 137   - Check if we need to retry making an outgoing connection
 138   - Deactivate the host
 139 */
 140 void terminate_connection(connection_t *c, bool report)
 141 {
 142         cp();
 143
 144         if(c->status.remove)
 145                 return;
 146
 147         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 148                            c->name, c->hostname);
 149
 150         c->status.remove = true;
 151         c->status.active = false;
 152
 153         if(c->node)
 154                 c->node->connection = NULL;
 155
 156         if(c->socket)
 157                 closesocket(c->socket);
 158
 159         if(c->edge) {
 160                 if(report)
 161                         send_del_edge(broadcast, c->edge);
 162
 163                 edge_del(c->edge);
 164
 165                 /* Run MST and SSSP algorithms */
 166
 167                 graph();
 168         }
 169
 170         /* Check if this was our outgoing connection */
 171
 172         if(c->outgoing) {
 173                 retry_outgoing(c->outgoing);
 174                 c->outgoing = NULL;
 175         }
 176 }
 177
 178 /*
 179   Check if the other end is active.
 180   If we have sent packets, but didn't receive any,
 181   then possibly the other end is dead. We send a
 182   PING request over the meta connection. If the other
 183   end does not reply in time, we consider them dead
 184   and close the connection.
 185 */
 186 static void check_dead_connections(void)
 187 {
 188         avl_node_t *node, *next;
 189         connection_t *c;
 190
 191         cp();
 192
 193         for(node = connection_tree->head; node; node = next) {
 194                 next = node->next;
 195                 c = (connection_t *) node->data;
 196
 197                 if(c->last_ping_time + pingtimeout < now) {
 198                         if(c->status.active) {
 199                                 if(c->status.pinged) {
 200                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 201                                                            c->name, c->hostname);
 202                                         c->status.timeout = true;
 203                                         terminate_connection(c, true);
 204                                 } else {
 205                                         send_ping(c);
 206                                 }
 207                         } else {
 208                                 if(c->status.remove) {
 209                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 210                                                    c->name, c->hostname, *(uint32_t *)&c->status);
 211                                         connection_del(c);
 212                                         continue;
 213                                 }
 214                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 215                                                    c->name, c->hostname);
 216                                 terminate_connection(c, false);
 217                         }
 218                 }
 219         }
 220 }
 221
 222 /*
 223   check all connections to see if anything
 224   happened on their sockets
 225 */
 226 static void check_network_activity(fd_set * f)
 227 {
 228         connection_t *c;
 229         avl_node_t *node;
 230         int result, i;
 231         int len = sizeof(result);
 232         vpn_packet_t packet;
 233
 234         cp();
 235
 236         if(FD_ISSET(device_fd, f)) {
 237                 if(read_packet(&packet))
 238                         route_outgoing(&packet);
 239         }
 240
 241         for(node = connection_tree->head; node; node = node->next) {
 242                 c = (connection_t *) node->data;
 243
 244                 if(c->status.remove)
 245                         continue;
 246
 247                 if(FD_ISSET(c->socket, f)) {
 248                         if(c->status.connecting) {
 249                                 c->status.connecting = false;
 250                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 251
 252                                 if(!result)
 253                                         finish_connecting(c);
 254                                 else {
 255                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 256                                                            _("Error while connecting to %s (%s): %s"),
 257                                                            c->name, c->hostname, strerror(result));
 258                                         closesocket(c->socket);
 259                                         do_outgoing_connection(c);
 260                                         continue;
 261                                 }
 262                         }
 263
 264                         if(!receive_meta(c)) {
 265                                 terminate_connection(c, c->status.active);
 266                                 continue;
 267                         }
 268                 }
 269         }
 270
 271         for(i = 0; i < listen_sockets; i++) {
 272                 if(FD_ISSET(listen_socket[i].udp, f))
 273                         handle_incoming_vpn_data(listen_socket[i].udp);
 274
 275                 if(FD_ISSET(listen_socket[i].tcp, f))
 276                         handle_new_meta_connection(listen_socket[i].tcp);
 277         }
 278 }
 279
 280 /*
 281   this is where it all happens...
 282 */
 283 void main_loop(void)
 284 {
 285         fd_set fset;
 286         struct timeval tv;
 287         int r, maxfd;
 288         time_t last_ping_check, last_config_check;
 289         event_t *event;
 290
 291         cp();
 292
 293         last_ping_check = now;
 294         last_config_check = now;
 295         srand(now);
 296
 297         for(;;) {
 298                 now = time(NULL);
 299
 300                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 301                 tv.tv_usec = 0;
 302
 303                 maxfd = build_fdset(&fset);
 304
 305                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 306
 307                 if(r < 0) {
 308                         if(errno != EINTR && errno != EAGAIN) {
 309                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 310                                            strerror(errno));
 311                                 cp_trace();
 312                                 dump_connections();
 313                                 return;
 314                         }
 315
 316                         continue;
 317                 }
 318
 319                 check_network_activity(&fset);
 320
 321                 if(do_purge) {
 322                         purge();
 323                         do_purge = false;
 324                 }
 325
 326                 /* Let's check if everybody is still alive */
 327
 328                 if(last_ping_check + pingtimeout < now) {
 329                         check_dead_connections();
 330                         last_ping_check = now;
 331
 332                         if(routing_mode == RMODE_SWITCH)
 333                                 age_mac();
 334
 335                         age_past_requests();
 336
 337                         /* Should we regenerate our key? */
 338
 339                         if(keyexpires < now) {
 340                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 341
 342                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 343                                 if(myself->cipher)
 344                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 345                                 send_key_changed(broadcast, myself);
 346                                 keyexpires = now + keylifetime;
 347                         }
 348                 }
 349
 350
 351                 while((event = get_expired_event())) {
 352                         event->handler(event->data);
 353                         free(event);
 354                 }
 355
 356                 if(sigalrm) {
 357                         logger(LOG_INFO, _("Flushing event queue"));
 358
 359                         while(event_tree->head) {
 360                                 event = (event_t *) event_tree->head->data;
 361                                 event->handler(event->data);
 362                                 event_del(event);
 363                         }
 364                         sigalrm = false;
 365                 }
 366
 367                 if(sighup) {
 368                         connection_t *c;
 369                         avl_node_t *node;
 370                         char *fname;
 371                         struct stat s;
 372
 373                         sighup = false;
 374
 375                         /* Reread our own configuration file */
 376
 377                         exit_configuration(&config_tree);
 378                         init_configuration(&config_tree);
 379
 380                         if(!read_server_config()) {
 381                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 382                                 exit(1);
 383                         }
 384
 385                         /* Close connections to hosts that have a changed or deleted host config file */
 386
 387                         for(node = connection_tree->head; node; node = node->next) {
 388                                 c = (connection_t *) node->data;
 389
 390                                 if(c->outgoing) {
 391                                         free(c->outgoing->name);
 392                                         freeaddrinfo(c->outgoing->ai);
 393                                         free(c->outgoing);
 394                                         c->outgoing = NULL;
 395                                 }
 396
 397                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 398                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 399                                         terminate_connection(c, c->status.active);
 400                                 free(fname);
 401                         }
 402
 403                         last_config_check = now;
 404
 405                         /* Try to make outgoing connections */
 406
 407                         try_outgoing_connections();
 408
 409                         continue;
 410                 }
 411         }
 412 }