git.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 1.35.4.200 2003/08/28 21:05:10 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 = 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                                 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                                 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 = nnode->data;
  93
  94                 if(!n->status.reachable) {
  95                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  96                                 enext = enode->next;
  97                                 e = 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 = 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                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 191
 192                 if(report && !c->node->status.reachable) {
 193                         edge_t *e;
 194                         e = lookup_edge(c->node, myself);
 195                         if(e) {
 196                                 send_del_edge(broadcast, e);
 197                                 edge_del(e);
 198                         }
 199                 }
 200         }
 201
 202         /* Check if this was our outgoing connection */
 203
 204         if(c->outgoing) {
 205                 retry_outgoing(c->outgoing);
 206                 c->outgoing = NULL;
 207         }
 208 }
 209
 210 /*
 211   Check if the other end is active.
 212   If we have sent packets, but didn't receive any,
 213   then possibly the other end is dead. We send a
 214   PING request over the meta connection. If the other
 215   end does not reply in time, we consider them dead
 216   and close the connection.
 217 */
 218 static void check_dead_connections(void)
 219 {
 220         avl_node_t *node, *next;
 221         connection_t *c;
 222
 223         cp();
 224
 225         for(node = connection_tree->head; node; node = next) {
 226                 next = node->next;
 227                 c = node->data;
 228
 229                 if(c->last_ping_time + pingtimeout < now) {
 230                         if(c->status.active) {
 231                                 if(c->status.pinged) {
 232                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 233                                                            c->name, c->hostname);
 234                                         c->status.timeout = true;
 235                                         terminate_connection(c, true);
 236                                 } else {
 237                                         send_ping(c);
 238                                 }
 239                         } else {
 240                                 if(c->status.remove) {
 241                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 242                                                    c->name, c->hostname, *(uint32_t *)&c->status);
 243                                         connection_del(c);
 244                                         continue;
 245                                 }
 246                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 247                                                    c->name, c->hostname);
 248                                 terminate_connection(c, false);
 249                         }
 250                 }
 251         }
 252 }
 253
 254 /*
 255   check all connections to see if anything
 256   happened on their sockets
 257 */
 258 static void check_network_activity(fd_set * f)
 259 {
 260         connection_t *c;
 261         avl_node_t *node;
 262         int result, i;
 263         int len = sizeof(result);
 264         vpn_packet_t packet;
 265
 266         cp();
 267
 268         if(FD_ISSET(device_fd, f)) {
 269                 if(read_packet(&packet))
 270                         route_outgoing(&packet);
 271         }
 272
 273         for(node = connection_tree->head; node; node = node->next) {
 274                 c = node->data;
 275
 276                 if(c->status.remove)
 277                         continue;
 278
 279                 if(FD_ISSET(c->socket, f)) {
 280                         if(c->status.connecting) {
 281                                 c->status.connecting = false;
 282                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 283
 284                                 if(!result)
 285                                         finish_connecting(c);
 286                                 else {
 287                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 288                                                            _("Error while connecting to %s (%s): %s"),
 289                                                            c->name, c->hostname, strerror(result));
 290                                         closesocket(c->socket);
 291                                         do_outgoing_connection(c);
 292                                         continue;
 293                                 }
 294                         }
 295
 296                         if(!receive_meta(c)) {
 297                                 terminate_connection(c, c->status.active);
 298                                 continue;
 299                         }
 300                 }
 301         }
 302
 303         for(i = 0; i < listen_sockets; i++) {
 304                 if(FD_ISSET(listen_socket[i].udp, f))
 305                         handle_incoming_vpn_data(listen_socket[i].udp);
 306
 307                 if(FD_ISSET(listen_socket[i].tcp, f))
 308                         handle_new_meta_connection(listen_socket[i].tcp);
 309         }
 310 }
 311
 312 /*
 313   this is where it all happens...
 314 */
 315 int main_loop(void)
 316 {
 317         fd_set fset;
 318         struct timeval tv;
 319         int r, maxfd;
 320         time_t last_ping_check, last_config_check;
 321         event_t *event;
 322
 323         cp();
 324
 325         last_ping_check = now;
 326         last_config_check = now;
 327         srand(now);
 328
 329         running = true;
 330
 331         while(running) {
 332                 now = time(NULL);
 333
 334                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 335                 tv.tv_usec = 0;
 336
 337                 maxfd = build_fdset(&fset);
 338
 339                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 340
 341                 if(r < 0) {
 342                         if(errno != EINTR && errno != EAGAIN) {
 343                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 344                                            strerror(errno));
 345                                 cp_trace();
 346                                 dump_connections();
 347                                 return 1;
 348                         }
 349
 350                         continue;
 351                 }
 352
 353                 check_network_activity(&fset);
 354
 355                 if(do_purge) {
 356                         purge();
 357                         do_purge = false;
 358                 }
 359
 360                 /* Let's check if everybody is still alive */
 361
 362                 if(last_ping_check + pingtimeout < now) {
 363                         check_dead_connections();
 364                         last_ping_check = now;
 365
 366                         if(routing_mode == RMODE_SWITCH)
 367                                 age_mac();
 368
 369                         age_past_requests();
 370
 371                         /* Should we regenerate our key? */
 372
 373                         if(keyexpires < now) {
 374                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 375
 376                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 377                                 if(myself->cipher)
 378                                         EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 379                                 send_key_changed(broadcast, myself);
 380                                 keyexpires = now + keylifetime;
 381                         }
 382                 }
 383
 384
 385                 while((event = get_expired_event())) {
 386                         event->handler(event->data);
 387                         free(event);
 388                 }
 389
 390                 if(sigalrm) {
 391                         logger(LOG_INFO, _("Flushing event queue"));
 392
 393                         while(event_tree->head) {
 394                                 event = event_tree->head->data;
 395                                 event->handler(event->data);
 396                                 event_del(event);
 397                         }
 398                         sigalrm = false;
 399                 }
 400
 401                 if(sighup) {
 402                         connection_t *c;
 403                         avl_node_t *node;
 404                         char *fname;
 405                         struct stat s;
 406
 407                         sighup = false;
 408
 409                         /* Reread our own configuration file */
 410
 411                         exit_configuration(&config_tree);
 412                         init_configuration(&config_tree);
 413
 414                         if(!read_server_config()) {
 415                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 416                                 return 1;
 417                         }
 418
 419                         /* Close connections to hosts that have a changed or deleted host config file */
 420
 421                         for(node = connection_tree->head; node; node = node->next) {
 422                                 c = node->data;
 423
 424                                 if(c->outgoing) {
 425                                         free(c->outgoing->name);
 426                                         freeaddrinfo(c->outgoing->ai);
 427                                         free(c->outgoing);
 428                                         c->outgoing = NULL;
 429                                 }
 430
 431                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 432                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 433                                         terminate_connection(c, c->status.active);
 434                                 free(fname);
 435                         }
 436
 437                         last_config_check = now;
 438
 439                         /* Try to make outgoing connections */
 440
 441                         try_outgoing_connections();
 442                 }
 443         }
 444
 445         return 0;
 446 }