src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2009 Guus Sliepen <guus@tinc-vpn.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 along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include <openssl/rand.h>
  24
  25 #include "utils.h"
  26 #include "avl_tree.h"
  27 #include "conf.h"
  28 #include "connection.h"
  29 #include "device.h"
  30 #include "event.h"
  31 #include "graph.h"
  32 #include "logger.h"
  33 #include "meta.h"
  34 #include "net.h"
  35 #include "netutl.h"
  36 #include "process.h"
  37 #include "protocol.h"
  38 #include "route.h"
  39 #include "subnet.h"
  40 #include "xalloc.h"
  41
  42 bool do_purge = false;
  43 volatile bool running = 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         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  51         node_t *n;
  52         edge_t *e;
  53         subnet_t *s;
  54
  55         cp();
  56
  57         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  58
  59         /* Remove all edges and subnets owned by unreachable nodes. */
  60
  61         for(nnode = node_tree->head; nnode; nnode = nnext) {
  62                 nnext = nnode->next;
  63                 n = 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 = snode->data;
  72                                 if(!tunnelserver)
  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 = enode->data;
  80                                 if(!tunnelserver)
  81                                         send_del_edge(broadcast, e);
  82                                 edge_del(e);
  83                         }
  84                 }
  85         }
  86
  87         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  88
  89         for(nnode = node_tree->head; nnode; nnode = nnext) {
  90                 nnext = nnode->next;
  91                 n = nnode->data;
  92
  93                 if(!n->status.reachable) {
  94                         for(enode = edge_weight_tree->head; enode; enode = enext) {
  95                                 enext = enode->next;
  96                                 e = enode->data;
  97
  98                                 if(e->to == n)
  99                                         break;
 100                         }
 101
 102                         if(!enode)
 103                                 node_del(n);
 104                 }
 105         }
 106 }
 107
 108 /*
 109   put all file descriptors in an fd_set array
 110   While we're at it, purge stuff that needs to be removed.
 111 */
 112 static int build_fdset(fd_set *readset, fd_set *writeset) {
 113         avl_node_t *node, *next;
 114         connection_t *c;
 115         int i, max = 0;
 116
 117         cp();
 118
 119         FD_ZERO(readset);
 120         FD_ZERO(writeset);
 121
 122         for(node = connection_tree->head; node; node = next) {
 123                 next = node->next;
 124                 c = node->data;
 125
 126                 if(c->status.remove) {
 127                         connection_del(c);
 128                         if(!connection_tree->head)
 129                                 purge();
 130                 } else {
 131                         FD_SET(c->socket, readset);
 132                         if(c->outbuflen > 0)
 133                                 FD_SET(c->socket, writeset);
 134                         if(c->socket > max)
 135                                 max = c->socket;
 136                 }
 137         }
 138
 139         for(i = 0; i < listen_sockets; i++) {
 140                 FD_SET(listen_socket[i].tcp, readset);
 141                 if(listen_socket[i].tcp > max)
 142                         max = listen_socket[i].tcp;
 143                 FD_SET(listen_socket[i].udp, readset);
 144                 if(listen_socket[i].udp > max)
 145                         max = listen_socket[i].udp;
 146         }
 147
 148         if(device_fd >= 0)
 149                 FD_SET(device_fd, readset);
 150         if(device_fd > max)
 151                 max = device_fd;
 152
 153         return max;
 154 }
 155
 156 /*
 157   Terminate a connection:
 158   - Close the socket
 159   - Remove associated edge and tell other connections about it if report = true
 160   - Check if we need to retry making an outgoing connection
 161   - Deactivate the host
 162 */
 163 void terminate_connection(connection_t *c, bool report) {
 164         cp();
 165
 166         if(c->status.remove)
 167                 return;
 168
 169         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 170                            c->name, c->hostname);
 171
 172         c->status.remove = true;
 173         c->status.active = false;
 174
 175         if(c->node)
 176                 c->node->connection = NULL;
 177
 178         if(c->socket)
 179                 closesocket(c->socket);
 180
 181         if(c->edge) {
 182                 if(report && !tunnelserver)
 183                         send_del_edge(broadcast, c->edge);
 184
 185                 edge_del(c->edge);
 186
 187                 /* Run MST and SSSP algorithms */
 188
 189                 graph();
 190
 191                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 192
 193                 if(report && !c->node->status.reachable) {
 194                         edge_t *e;
 195                         e = lookup_edge(c->node, myself);
 196                         if(e) {
 197                                 if(!tunnelserver)
 198                                         send_del_edge(broadcast, e);
 199                                 edge_del(e);
 200                         }
 201                 }
 202         }
 203
 204         /* Check if this was our outgoing connection */
 205
 206         if(c->outgoing) {
 207                 retry_outgoing(c->outgoing);
 208                 c->outgoing = NULL;
 209         }
 210
 211         free(c->outbuf);
 212         c->outbuf = NULL;
 213         c->outbuflen = 0;
 214         c->outbufsize = 0;
 215         c->outbufstart = 0;
 216 }
 217
 218 /*
 219   Check if the other end is active.
 220   If we have sent packets, but didn't receive any,
 221   then possibly the other end is dead. We send a
 222   PING request over the meta connection. If the other
 223   end does not reply in time, we consider them dead
 224   and close the connection.
 225 */
 226 static void check_dead_connections(void) {
 227         avl_node_t *node, *next;
 228         connection_t *c;
 229
 230         cp();
 231
 232         for(node = connection_tree->head; node; node = next) {
 233                 next = node->next;
 234                 c = node->data;
 235
 236                 if(c->last_ping_time + pingtimeout < now) {
 237                         if(c->status.active) {
 238                                 if(c->status.pinged) {
 239                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING in %ld seconds"),
 240                                                            c->name, c->hostname, now - c->last_ping_time);
 241                                         c->status.timeout = true;
 242                                         terminate_connection(c, true);
 243                                 } else if(c->last_ping_time + pinginterval < now) {
 244                                         send_ping(c);
 245                                 }
 246                         } else {
 247                                 if(c->status.remove) {
 248                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 249                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 250                                         connection_del(c);
 251                                         continue;
 252                                 }
 253                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 254                                                    c->name, c->hostname);
 255                                 if(c->status.connecting) {
 256                                         c->status.connecting = false;
 257                                         closesocket(c->socket);
 258                                         do_outgoing_connection(c);
 259                                 } else {
 260                                         terminate_connection(c, false);
 261                                 }
 262                         }
 263                 }
 264
 265                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 266                         if(c->status.active) {
 267                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 268                                                 _("%s (%s) could not flush for %ld seconds (%d bytes remaining)"),
 269                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 270                                 c->status.timeout = true;
 271                                 terminate_connection(c, true);
 272                         }
 273                 }
 274         }
 275 }
 276
 277 /*
 278   check all connections to see if anything
 279   happened on their sockets
 280 */
 281 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 282         connection_t *c;
 283         avl_node_t *node;
 284         int result, i;
 285         socklen_t len = sizeof(result);
 286         vpn_packet_t packet;
 287
 288         cp();
 289
 290         /* check input from kernel */
 291         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 292                 if(read_packet(&packet)) {
 293                         packet.priority = 0;
 294                         route(myself, &packet);
 295                 }
 296         }
 297
 298         /* check meta connections */
 299         for(node = connection_tree->head; node; node = node->next) {
 300                 c = node->data;
 301
 302                 if(c->status.remove)
 303                         continue;
 304
 305                 if(FD_ISSET(c->socket, readset)) {
 306                         if(c->status.connecting) {
 307                                 c->status.connecting = false;
 308                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 309
 310                                 if(!result)
 311                                         finish_connecting(c);
 312                                 else {
 313                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 314                                                            _("Error while connecting to %s (%s): %s"),
 315                                                            c->name, c->hostname, strerror(result));
 316                                         closesocket(c->socket);
 317                                         do_outgoing_connection(c);
 318                                         continue;
 319                                 }
 320                         }
 321
 322                         if(!receive_meta(c)) {
 323                                 terminate_connection(c, c->status.active);
 324                                 continue;
 325                         }
 326                 }
 327
 328                 if(FD_ISSET(c->socket, writeset)) {
 329                         if(!flush_meta(c)) {
 330                                 terminate_connection(c, c->status.active);
 331                                 continue;
 332                         }
 333                 }
 334         }
 335
 336         for(i = 0; i < listen_sockets; i++) {
 337                 if(FD_ISSET(listen_socket[i].udp, readset))
 338                         handle_incoming_vpn_data(listen_socket[i].udp);
 339
 340                 if(FD_ISSET(listen_socket[i].tcp, readset))
 341                         handle_new_meta_connection(listen_socket[i].tcp);
 342         }
 343 }
 344
 345 /*
 346   this is where it all happens...
 347 */
 348 int main_loop(void) {
 349         fd_set readset, writeset;
 350         struct timeval tv;
 351         int r, maxfd;
 352         time_t last_ping_check, last_config_check, last_graph_dump;
 353         event_t *event;
 354
 355         cp();
 356
 357         last_ping_check = now;
 358         last_config_check = now;
 359         last_graph_dump = now;
 360
 361         srand(now);
 362
 363         running = true;
 364
 365         while(running) {
 366                 now = time(NULL);
 367
 368         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 369                 tv.tv_sec = 1;
 370                 tv.tv_usec = 0;
 371
 372                 maxfd = build_fdset(&readset, &writeset);
 373
 374 #ifdef HAVE_MINGW
 375                 LeaveCriticalSection(&mutex);
 376 #endif
 377                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 378 #ifdef HAVE_MINGW
 379                 EnterCriticalSection(&mutex);
 380 #endif
 381
 382                 if(r < 0) {
 383                         if(errno != EINTR && errno != EAGAIN) {
 384                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 385                                            strerror(errno));
 386                                 cp_trace();
 387                                 dump_connections();
 388                                 return 1;
 389                         }
 390
 391                         continue;
 392                 }
 393
 394                 check_network_activity(&readset, &writeset);
 395
 396                 if(do_purge) {
 397                         purge();
 398                         do_purge = false;
 399                 }
 400
 401                 /* Let's check if everybody is still alive */
 402
 403                 if(last_ping_check + pingtimeout < now) {
 404                         check_dead_connections();
 405                         last_ping_check = now;
 406
 407                         if(routing_mode == RMODE_SWITCH)
 408                                 age_subnets();
 409
 410                         age_past_requests();
 411
 412                         /* Should we regenerate our key? */
 413
 414                         if(keyexpires < now) {
 415                                 avl_node_t *node;
 416                                 node_t *n;
 417
 418                                 ifdebug(STATUS) logger(LOG_INFO, _("Expiring symmetric keys"));
 419
 420                                 for(node = node_tree->head; node; node = node->next) {
 421                                         n = node->data;
 422                                         if(n->inkey) {
 423                                                 free(n->inkey);
 424                                                 n->inkey = NULL;
 425                                         }
 426                                 }
 427
 428                                 send_key_changed(broadcast, myself);
 429                                 keyexpires = now + keylifetime;
 430                         }
 431                 }
 432
 433                 if(sigalrm) {
 434                         logger(LOG_INFO, _("Flushing event queue"));
 435                         expire_events();
 436                         sigalrm = false;
 437                 }
 438
 439                 while((event = get_expired_event())) {
 440                         event->handler(event->data);
 441                         free_event(event);
 442                 }
 443
 444                 if(sighup) {
 445                         connection_t *c;
 446                         avl_node_t *node;
 447                         char *fname;
 448                         struct stat s;
 449
 450                         sighup = false;
 451
 452                         /* Reread our own configuration file */
 453
 454                         exit_configuration(&config_tree);
 455                         init_configuration(&config_tree);
 456
 457                         if(!read_server_config()) {
 458                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 459                                 return 1;
 460                         }
 461
 462                         /* Close connections to hosts that have a changed or deleted host config file */
 463
 464                         for(node = connection_tree->head; node; node = node->next) {
 465                                 c = node->data;
 466
 467                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 468                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 469                                         terminate_connection(c, c->status.active);
 470                                 free(fname);
 471                         }
 472
 473                         last_config_check = now;
 474
 475                         /* Try to make outgoing connections */
 476
 477                         try_outgoing_connections();
 478                 }
 479
 480                 /* Dump graph if wanted every 60 seconds*/
 481
 482                 if(last_graph_dump + 60 < now) {
 483                         dump_graph();
 484                         last_graph_dump = now;
 485                 }
 486         }
 487
 488         return 0;
 489 }