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 1.35.4.192 2003/07/22 20:55:19 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 bool do_purge = false;
  44
  45 time_t now = 0;
  46
  47 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  48
  49 static void purge(void)
  50 {
  51         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  52         node_t *n;
  53         edge_t *e;
  54         subnet_t *s;
  55
  56         cp();
  57
  58         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  59
  60         for(nnode = node_tree->head; nnode; nnode = nnext) {
  61                 nnext = nnode->next;
  62                 n = (node_t *) nnode->data;
  63
  64                 if(!n->status.reachable) {
  65                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
  66                                            n->hostname);
  67
  68                         for(snode = n->subnet_tree->head; snode; snode = snext) {
  69                                 snext = snode->next;
  70                                 s = (subnet_t *) snode->data;
  71                                 send_del_subnet(broadcast, s);
  72                                 subnet_del(n, s);
  73                         }
  74
  75                         for(enode = n->edge_tree->head; enode; enode = enext) {
  76                                 enext = enode->next;
  77                                 e = (edge_t *) enode->data;
  78                                 send_del_edge(broadcast, e);
  79                                 edge_del(e);
  80                         }
  81
  82                         node_del(n);
  83                 }
  84         }
  85 }
  86
  87 /*
  88   put all file descriptors in an fd_set array
  89   While we're at it, purge stuff that needs to be removed.
  90 */
  91 static int build_fdset(fd_set * fs)
  92 {
  93         avl_node_t *node, *next;
  94         connection_t *c;
  95         int i, max = 0;
  96
  97         cp();
  98
  99         FD_ZERO(fs);
 100
 101         for(node = connection_tree->head; node; node = next) {
 102                 next = node->next;
 103                 c = (connection_t *) node->data;
 104
 105                 if(c->status.remove) {
 106                         connection_del(c);
 107                         if(!connection_tree->head)
 108                                 purge();
 109                 } else {
 110                         FD_SET(c->socket, fs);
 111                         if(c->socket > max)
 112                                 max = c->socket;
 113                 }
 114         }
 115
 116         for(i = 0; i < listen_sockets; i++) {
 117                 FD_SET(listen_socket[i].tcp, fs);
 118                 if(listen_socket[i].tcp > max)
 119                         max = listen_socket[i].tcp;
 120                 FD_SET(listen_socket[i].udp, fs);
 121                 if(listen_socket[i].udp > max)
 122                         max = listen_socket[i].udp;
 123         }
 124
 125         FD_SET(device_fd, fs);
 126         if(device_fd > max)
 127                 max = device_fd;
 128
 129         return max;
 130 }
 131
 132 /*
 133   Terminate a connection:
 134   - Close the socket
 135   - Remove associated edge and tell other connections about it if report = true
 136   - Check if we need to retry making an outgoing connection
 137   - Deactivate the host
 138 */
 139 void terminate_connection(connection_t *c, bool report)
 140 {
 141         cp();
 142
 143         if(c->status.remove)
 144                 return;
 145
 146         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 147                            c->name, c->hostname);
 148
 149         c->status.remove = true;
 150         c->status.active = false;
 151
 152         if(c->node)
 153                 c->node->connection = NULL;
 154
 155         if(c->socket)
 156                 close(c->socket);
 157
 158         if(c->edge) {
 159                 if(report)
 160                         send_del_edge(broadcast, c->edge);
 161
 162                 edge_del(c->edge);
 163
 164                 /* Run MST and SSSP algorithms */
 165
 166                 graph();
 167         }
 168
 169         /* Check if this was our outgoing connection */
 170
 171         if(c->outgoing) {
 172                 retry_outgoing(c->outgoing);
 173                 c->outgoing = NULL;
 174         }
 175 }
 176
 177 /*
 178   Check if the other end is active.
 179   If we have sent packets, but didn't receive any,
 180   then possibly the other end is dead. We send a
 181   PING request over the meta connection. If the other
 182   end does not reply in time, we consider them dead
 183   and close the connection.
 184 */
 185 static void check_dead_connections(void)
 186 {
 187         avl_node_t *node, *next;
 188         connection_t *c;
 189
 190         cp();
 191
 192         for(node = connection_tree->head; node; node = next) {
 193                 next = node->next;
 194                 c = (connection_t *) node->data;
 195
 196                 if(c->last_ping_time + pingtimeout < now) {
 197                         if(c->status.active) {
 198                                 if(c->status.pinged) {
 199                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 200                                                            c->name, c->hostname);
 201                                         c->status.timeout = true;
 202                                         terminate_connection(c, true);
 203                                 } else {
 204                                         send_ping(c);
 205                                 }
 206                         } else {
 207                                 if(c->status.remove) {
 208                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 209                                                    c->name, c->hostname, c->status);
 210                                         connection_del(c);
 211                                         continue;
 212                                 }
 213                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 214                                                    c->name, c->hostname);
 215                                 terminate_connection(c, false);
 216                         }
 217                 }
 218         }
 219 }
 220
 221 /*
 222   check all connections to see if anything
 223   happened on their sockets
 224 */
 225 static void check_network_activity(fd_set * f)
 226 {
 227         connection_t *c;
 228         avl_node_t *node;
 229         int result, i;
 230         int len = sizeof(result);
 231         vpn_packet_t packet;
 232
 233         cp();
 234
 235         if(FD_ISSET(device_fd, f)) {
 236                 if(read_packet(&packet))
 237                         route_outgoing(&packet);
 238         }
 239
 240         for(node = connection_tree->head; node; node = node->next) {
 241                 c = (connection_t *) node->data;
 242
 243                 if(c->status.remove)
 244                         continue;
 245
 246                 if(FD_ISSET(c->socket, f)) {
 247                         if(c->status.connecting) {
 248                                 c->status.connecting = false;
 249                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 250
 251                                 if(!result)
 252                                         finish_connecting(c);
 253                                 else {
 254                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 255                                                            _("Error while connecting to %s (%s): %s"),
 256                                                            c->name, c->hostname, strerror(result));
 257                                         close(c->socket);
 258                                         do_outgoing_connection(c);
 259                                         continue;
 260                                 }
 261                         }
 262
 263                         if(!receive_meta(c)) {
 264                                 terminate_connection(c, c->status.active);
 265                                 continue;
 266                         }
 267                 }
 268         }
 269
 270         for(i = 0; i < listen_sockets; i++) {
 271                 if(FD_ISSET(listen_socket[i].udp, f))
 272                         handle_incoming_vpn_data(listen_socket[i].udp);
 273
 274                 if(FD_ISSET(listen_socket[i].tcp, f))
 275                         handle_new_meta_connection(listen_socket[i].tcp);
 276         }
 277 }
 278
 279 /*
 280   this is where it all happens...
 281 */
 282 void main_loop(void)
 283 {
 284         fd_set fset;
 285         struct timeval tv;
 286         int r, maxfd;
 287         time_t last_ping_check, last_config_check;
 288         event_t *event;
 289
 290         cp();
 291
 292         last_ping_check = now;
 293         last_config_check = now;
 294         srand(now);
 295
 296         for(;;) {
 297                 now = time(NULL);
 298
 299                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 300                 tv.tv_usec = 0;
 301
 302                 maxfd = build_fdset(&fset);
 303
 304                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 305
 306                 if(r < 0) {
 307                         if(errno != EINTR && errno != EAGAIN) {
 308                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 309                                            strerror(errno));
 310                                 cp_trace();
 311                                 dump_connections();
 312                                 return;
 313                         }
 314
 315                         continue;
 316                 }
 317
 318                 check_network_activity(&fset);
 319
 320                 if(do_purge) {
 321                         purge();
 322                         do_purge = false;
 323                 }
 324
 325                 /* Let's check if everybody is still alive */
 326
 327                 if(last_ping_check + pingtimeout < now) {
 328                         check_dead_connections();
 329                         last_ping_check = now;
 330
 331                         if(routing_mode == RMODE_SWITCH)
 332                                 age_mac();
 333
 334                         age_past_requests();
 335
 336                         /* Should we regenerate our key? */
 337
 338                         if(keyexpires < now) {
 339                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 340
 341                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 342                                 EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 343                                 send_key_changed(broadcast, myself);
 344                                 keyexpires = now + keylifetime;
 345                         }
 346                 }
 347
 348
 349                 while((event = get_expired_event())) {
 350                         event->handler(event->data);
 351                         free(event);
 352                 }
 353
 354                 if(sigalrm) {
 355                         logger(LOG_INFO, _("Flushing event queue"));
 356
 357                         while(event_tree->head) {
 358                                 event = (event_t *) event_tree->head->data;
 359                                 event->handler(event->data);
 360                                 event_del(event);
 361                         }
 362                         sigalrm = false;
 363                 }
 364
 365                 if(sighup) {
 366                         connection_t *c;
 367                         avl_node_t *node;
 368                         char *fname;
 369                         struct stat s;
 370
 371                         sighup = false;
 372
 373                         /* Reread our own configuration file */
 374
 375                         exit_configuration(&config_tree);
 376                         init_configuration(&config_tree);
 377
 378                         if(!read_server_config()) {
 379                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 380                                 exit(1);
 381                         }
 382
 383                         /* Close connections to hosts that have a changed or deleted host config file */
 384
 385                         for(node = connection_tree->head; node; node = node->next) {
 386                                 c = (connection_t *) node->data;
 387
 388                                 if(c->outgoing) {
 389                                         free(c->outgoing->name);
 390                                         freeaddrinfo(c->outgoing->ai);
 391                                         free(c->outgoing);
 392                                         c->outgoing = NULL;
 393                                 }
 394
 395                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 396                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 397                                         terminate_connection(c, c->status.active);
 398                                 free(fname);
 399                         }
 400
 401                         last_config_check = now;
 402
 403                         /* Try to make outgoing connections */
 404
 405                         try_outgoing_connections();
 406
 407                         continue;
 408                 }
 409         }
 410 }