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 1.35.4.191 2003/07/17 15:06:26 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
  43 int do_purge = 0;
  44 int sighup = 0;
  45 int sigalrm = 0;
  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         for(nnode = node_tree->head; nnode; nnode = nnext) {
  63                 nnext = nnode->next;
  64                 n = (node_t *) nnode->data;
  65
  66                 if(!n->status.reachable) {
  67                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  68                                            n->hostname);
  69
  70                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  71                                 snext = snode->next;
  72                                 s = (subnet_t *) snode->data;
  73                                 send_del_subnet(broadcast, s);
  74                                 subnet_del(n, s);
  75                         }
  76
  77                         for(enode = n->edge_tree->head; enode; enode = enext) {
  78                                 enext = enode->next;
  79                                 e = (edge_t *) enode->data;
  80                                 send_del_edge(broadcast, e);
  81                                 edge_del(e);
  82                         }
  83
  84                         node_del(n);
  85                 }
  86         }
  87 }
  88
  89 /*
  90   put all file descriptors in an fd_set array
  91   While we're at it, purge stuff that needs to be removed.
  92 */
  93 static int build_fdset(fd_set * fs)
  94 {
  95         avl_node_t *node, *next;
  96         connection_t *c;
  97         int i, max = 0;
  98
  99         cp();
 100
 101         FD_ZERO(fs);
 102
 103         for(node = connection_tree->head; node; node = next) {
 104                 next = node->next;
 105                 c = (connection_t *) node->data;
 106
 107                 if(c->status.remove) {
 108                         connection_del(c);
 109                         if(!connection_tree->head)
 110                                 purge();
 111                 } else {
 112                         FD_SET(c->socket, fs);
 113                         if(c->socket > max)
 114                                 max = c->socket;
 115                 }
 116         }
 117
 118         for(i = 0; i < listen_sockets; i++) {
 119                 FD_SET(listen_socket[i].tcp, fs);
 120                 if(listen_socket[i].tcp > max)
 121                         max = listen_socket[i].tcp;
 122                 FD_SET(listen_socket[i].udp, fs);
 123                 if(listen_socket[i].udp > max)
 124                         max = listen_socket[i].udp;
 125         }
 126
 127         FD_SET(device_fd, fs);
 128         if(device_fd > max)
 129                 max = device_fd;
 130
 131         return max;
 132 }
 133
 134 /*
 135   Terminate a connection:
 136   - Close the socket
 137   - Remove associated edge and tell other connections about it if report = 1
 138   - Check if we need to retry making an outgoing connection
 139   - Deactivate the host
 140 */
 141 void terminate_connection(connection_t *c, int report)
 142 {
 143         cp();
 144
 145         if(c->status.remove)
 146                 return;
 147
 148         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 149                            c->name, c->hostname);
 150
 151         c->status.remove = 1;
 152         c->status.active = 0;
 153
 154         if(c->node)
 155                 c->node->connection = NULL;
 156
 157         if(c->socket)
 158                 close(c->socket);
 159
 160         if(c->edge) {
 161                 if(report)
 162                         send_del_edge(broadcast, c->edge);
 163
 164                 edge_del(c->edge);
 165
 166                 /* Run MST and SSSP algorithms */
 167
 168                 graph();
 169         }
 170
 171         /* Check if this was our outgoing connection */
 172
 173         if(c->outgoing) {
 174                 retry_outgoing(c->outgoing);
 175                 c->outgoing = NULL;
 176         }
 177 }
 178
 179 /*
 180   Check if the other end is active.
 181   If we have sent packets, but didn't receive any,
 182   then possibly the other end is dead. We send a
 183   PING request over the meta connection. If the other
 184   end does not reply in time, we consider them dead
 185   and close the connection.
 186 */
 187 static void check_dead_connections(void)
 188 {
 189         avl_node_t *node, *next;
 190         connection_t *c;
 191
 192         cp();
 193
 194         for(node = connection_tree->head; node; node = next) {
 195                 next = node->next;
 196                 c = (connection_t *) node->data;
 197
 198                 if(c->last_ping_time + pingtimeout < now) {
 199                         if(c->status.active) {
 200                                 if(c->status.pinged) {
 201                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 202                                                            c->name, c->hostname);
 203                                         c->status.timeout = 1;
 204                                         terminate_connection(c, 1);
 205                                 } else {
 206                                         send_ping(c);
 207                                 }
 208                         } else {
 209                                 if(c->status.remove) {
 210                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 211                                                    c->name, c->hostname, c->status);
 212                                         connection_del(c);
 213                                         continue;
 214                                 }
 215                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 216                                                    c->name, c->hostname);
 217                                 terminate_connection(c, 0);
 218                         }
 219                 }
 220         }
 221 }
 222
 223 /*
 224   check all connections to see if anything
 225   happened on their sockets
 226 */
 227 static void check_network_activity(fd_set * f)
 228 {
 229         connection_t *c;
 230         avl_node_t *node;
 231         int result, i;
 232         int len = sizeof(result);
 233         vpn_packet_t packet;
 234
 235         cp();
 236
 237         if(FD_ISSET(device_fd, f)) {
 238                 if(!read_packet(&packet))
 239                         route_outgoing(&packet);
 240         }
 241
 242         for(node = connection_tree->head; node; node = node->next) {
 243                 c = (connection_t *) node->data;
 244
 245                 if(c->status.remove)
 246                         continue;
 247
 248                 if(FD_ISSET(c->socket, f)) {
 249                         if(c->status.connecting) {
 250                                 c->status.connecting = 0;
 251                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 252
 253                                 if(!result)
 254                                         finish_connecting(c);
 255                                 else {
 256                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 257                                                            _("Error while connecting to %s (%s): %s"),
 258                                                            c->name, c->hostname, strerror(result));
 259                                         close(c->socket);
 260                                         do_outgoing_connection(c);
 261                                         continue;
 262                                 }
 263                         }
 264
 265                         if(receive_meta(c) < 0) {
 266                                 terminate_connection(c, c->status.active);
 267                                 continue;
 268                         }
 269                 }
 270         }
 271
 272         for(i = 0; i < listen_sockets; i++) {
 273                 if(FD_ISSET(listen_socket[i].udp, f))
 274                         handle_incoming_vpn_data(listen_socket[i].udp);
 275
 276                 if(FD_ISSET(listen_socket[i].tcp, f))
 277                         handle_new_meta_connection(listen_socket[i].tcp);
 278         }
 279 }
 280
 281 /*
 282   this is where it all happens...
 283 */
 284 void main_loop(void)
 285 {
 286         fd_set fset;
 287         struct timeval tv;
 288         int r, maxfd;
 289         time_t last_ping_check, last_config_check;
 290         event_t *event;
 291
 292         cp();
 293
 294         last_ping_check = now;
 295         last_config_check = now;
 296         srand(now);
 297
 298         for(;;) {
 299                 now = time(NULL);
 300
 301                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 302                 tv.tv_usec = 0;
 303
 304                 maxfd = build_fdset(&fset);
 305
 306                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 307
 308                 if(r < 0) {
 309                         if(errno != EINTR && errno != EAGAIN) {
 310                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 311                                            strerror(errno));
 312                                 cp_trace();
 313                                 dump_connections();
 314                                 return;
 315                         }
 316
 317                         continue;
 318                 }
 319
 320                 check_network_activity(&fset);
 321
 322                 if(do_purge) {
 323                         purge();
 324                         do_purge = 0;
 325                 }
 326
 327                 /* Let's check if everybody is still alive */
 328
 329                 if(last_ping_check + pingtimeout < now) {
 330                         check_dead_connections();
 331                         last_ping_check = now;
 332
 333                         if(routing_mode == RMODE_SWITCH)
 334                                 age_mac();
 335
 336                         age_past_requests();
 337
 338                         /* Should we regenerate our key? */
 339
 340                         if(keyexpires < now) {
 341                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 342
 343                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 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 = 0;
 365                 }
 366
 367                 if(sighup) {
 368                         connection_t *c;
 369                         avl_node_t *node;
 370                         char *fname;
 371                         struct stat s;
 372
 373                         sighup = 0;
 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 }