src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2010 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License along
  18     with this program; if not, write to the Free Software Foundation, Inc.,
  19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20 */
  21
  22 #include "system.h"
  23
  24 #include <openssl/rand.h>
  25
  26 #include "utils.h"
  27 #include "avl_tree.h"
  28 #include "conf.h"
  29 #include "connection.h"
  30 #include "device.h"
  31 #include "event.h"
  32 #include "graph.h"
  33 #include "logger.h"
  34 #include "meta.h"
  35 #include "net.h"
  36 #include "netutl.h"
  37 #include "process.h"
  38 #include "protocol.h"
  39 #include "route.h"
  40 #include "subnet.h"
  41 #include "xalloc.h"
  42
  43 bool do_purge = false;
  44 volatile bool running = false;
  45
  46 time_t now = 0;
  47 int contradicting_add_edge = 0;
  48 int contradicting_del_edge = 0;
  49
  50 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  51
  52 static void purge(void) {
  53         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  54         node_t *n;
  55         edge_t *e;
  56         subnet_t *s;
  57
  58         ifdebug(PROTOCOL) logger(LOG_DEBUG, "Purging unreachable nodes");
  59
  60         /* Remove all edges and subnets owned by unreachable nodes. */
  61
  62         for(nnode = node_tree->head; nnode; nnode = nnext) {
  63                 nnext = nnode->next;
  64                 n = 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 = snode->data;
  73                                 send_del_subnet(broadcast, s);
  74                                 if(!strictsubnets)
  75                                         subnet_del(n, s);
  76                         }
  77
  78                         for(enode = n->edge_tree->head; enode; enode = enext) {
  79                                 enext = enode->next;
  80                                 e = enode->data;
  81                                 if(!tunnelserver)
  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 && (!strictsubnets || !n->subnet_tree->head))
 104                                 /* in strictsubnets mode do not delete nodes with subnets */
 105                                 node_del(n);
 106                 }
 107         }
 108 }
 109
 110 /*
 111   put all file descriptors in an fd_set array
 112   While we're at it, purge stuff that needs to be removed.
 113 */
 114 static int build_fdset(fd_set *readset, fd_set *writeset) {
 115         avl_node_t *node, *next;
 116         connection_t *c;
 117         int i, max = 0;
 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         if(c->status.remove)
 165                 return;
 166
 167         ifdebug(CONNECTIONS) logger(LOG_NOTICE, "Closing connection with %s (%s)",
 168                            c->name, c->hostname);
 169
 170         c->status.remove = true;
 171         c->status.active = false;
 172
 173         if(c->node)
 174                 c->node->connection = NULL;
 175
 176         if(c->socket)
 177                 closesocket(c->socket);
 178
 179         if(c->edge) {
 180                 if(report && !tunnelserver)
 181                         send_del_edge(broadcast, c->edge);
 182
 183                 edge_del(c->edge);
 184
 185                 /* Run MST and SSSP algorithms */
 186
 187                 graph();
 188
 189                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 190
 191                 if(report && !c->node->status.reachable) {
 192                         edge_t *e;
 193                         e = lookup_edge(c->node, myself);
 194                         if(e) {
 195                                 if(!tunnelserver)
 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         free(c->outbuf);
 210         c->outbuf = NULL;
 211         c->outbuflen = 0;
 212         c->outbufsize = 0;
 213         c->outbufstart = 0;
 214 }
 215
 216 /*
 217   Check if the other end is active.
 218   If we have sent packets, but didn't receive any,
 219   then possibly the other end is dead. We send a
 220   PING request over the meta connection. If the other
 221   end does not reply in time, we consider them dead
 222   and close the connection.
 223 */
 224 static void check_dead_connections(void) {
 225         avl_node_t *node, *next;
 226         connection_t *c;
 227
 228         for(node = connection_tree->head; node; node = next) {
 229                 next = node->next;
 230                 c = node->data;
 231
 232                 if(c->last_ping_time + pingtimeout < now) {
 233                         if(c->status.active) {
 234                                 if(c->status.pinged) {
 235                                         ifdebug(CONNECTIONS) logger(LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds",
 236                                                            c->name, c->hostname, now - c->last_ping_time);
 237                                         c->status.timeout = true;
 238                                         terminate_connection(c, true);
 239                                 } else if(c->last_ping_time + pinginterval < now) {
 240                                         send_ping(c);
 241                                 }
 242                         } else {
 243                                 if(c->status.remove) {
 244                                         logger(LOG_WARNING, "Old connection_t for %s (%s) status %04x still lingering, deleting...",
 245                                                    c->name, c->hostname, bitfield_to_int(&c->status, sizeof c->status));
 246                                         connection_del(c);
 247                                         continue;
 248                                 }
 249                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, "Timeout from %s (%s) during authentication",
 250                                                    c->name, c->hostname);
 251                                 if(c->status.connecting) {
 252                                         c->status.connecting = false;
 253                                         closesocket(c->socket);
 254                                         do_outgoing_connection(c);
 255                                 } else {
 256                                         terminate_connection(c, false);
 257                                 }
 258                         }
 259                 }
 260
 261                 if(c->outbuflen > 0 && c->last_flushed_time + pingtimeout < now) {
 262                         if(c->status.active) {
 263                                 ifdebug(CONNECTIONS) logger(LOG_INFO,
 264                                                 "%s (%s) could not flush for %ld seconds (%d bytes remaining)",
 265                                                 c->name, c->hostname, now - c->last_flushed_time, c->outbuflen);
 266                                 c->status.timeout = true;
 267                                 terminate_connection(c, true);
 268                         }
 269                 }
 270         }
 271 }
 272
 273 /*
 274   check all connections to see if anything
 275   happened on their sockets
 276 */
 277 static void check_network_activity(fd_set * readset, fd_set * writeset) {
 278         connection_t *c;
 279         avl_node_t *node;
 280         int result, i;
 281         socklen_t len = sizeof(result);
 282         vpn_packet_t packet;
 283
 284         /* check input from kernel */
 285         if(device_fd >= 0 && FD_ISSET(device_fd, readset)) {
 286                 if(read_packet(&packet)) {
 287                         packet.priority = 0;
 288                         route(myself, &packet);
 289                 }
 290         }
 291
 292         /* check meta connections */
 293         for(node = connection_tree->head; node; node = node->next) {
 294                 c = node->data;
 295
 296                 if(c->status.remove)
 297                         continue;
 298
 299                 if(FD_ISSET(c->socket, readset)) {
 300                         if(c->status.connecting) {
 301                                 c->status.connecting = false;
 302                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, (void *)&result, &len);
 303
 304                                 if(!result)
 305                                         finish_connecting(c);
 306                                 else {
 307                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 308                                                            "Error while connecting to %s (%s): %s",
 309                                                            c->name, c->hostname, sockstrerror(result));
 310                                         closesocket(c->socket);
 311                                         do_outgoing_connection(c);
 312                                         continue;
 313                                 }
 314                         }
 315
 316                         if(!receive_meta(c)) {
 317                                 terminate_connection(c, c->status.active);
 318                                 continue;
 319                         }
 320                 }
 321
 322                 if(FD_ISSET(c->socket, writeset)) {
 323                         if(!flush_meta(c)) {
 324                                 terminate_connection(c, c->status.active);
 325                                 continue;
 326                         }
 327                 }
 328         }
 329
 330         for(i = 0; i < listen_sockets; i++) {
 331                 if(FD_ISSET(listen_socket[i].udp, readset))
 332                         handle_incoming_vpn_data(listen_socket[i].udp);
 333
 334                 if(FD_ISSET(listen_socket[i].tcp, readset))
 335                         handle_new_meta_connection(listen_socket[i].tcp);
 336         }
 337 }
 338
 339 /*
 340   this is where it all happens...
 341 */
 342 int main_loop(void) {
 343         fd_set readset, writeset;
 344         struct timeval tv;
 345         int r, maxfd;
 346         time_t last_ping_check, last_config_check, last_graph_dump;
 347         event_t *event;
 348
 349         last_ping_check = now;
 350         last_config_check = now;
 351         last_graph_dump = now;
 352
 353         srand(now);
 354
 355         running = true;
 356
 357         while(running) {
 358                 now = time(NULL);
 359
 360         //      tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 361                 tv.tv_sec = 1;
 362                 tv.tv_usec = 0;
 363
 364                 maxfd = build_fdset(&readset, &writeset);
 365
 366 #ifdef HAVE_MINGW
 367                 LeaveCriticalSection(&mutex);
 368 #endif
 369                 r = select(maxfd + 1, &readset, &writeset, NULL, &tv);
 370 #ifdef HAVE_MINGW
 371                 EnterCriticalSection(&mutex);
 372 #endif
 373
 374                 if(r < 0) {
 375                         if(!sockwouldblock(sockerrno)) {
 376                                 logger(LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 377                                 dump_connections();
 378                                 return 1;
 379                         }
 380                 }
 381
 382                 if(r > 0)
 383                         check_network_activity(&readset, &writeset);
 384
 385                 if(do_purge) {
 386                         purge();
 387                         do_purge = false;
 388                 }
 389
 390                 /* Let's check if everybody is still alive */
 391
 392                 if(last_ping_check + pingtimeout < now) {
 393                         check_dead_connections();
 394                         last_ping_check = now;
 395
 396                         if(routing_mode == RMODE_SWITCH)
 397                                 age_subnets();
 398
 399                         age_past_requests();
 400
 401                         /* Should we regenerate our key? */
 402
 403                         if(keyexpires < now) {
 404                                 avl_node_t *node;
 405                                 node_t *n;
 406
 407                                 ifdebug(STATUS) logger(LOG_INFO, "Expiring symmetric keys");
 408
 409                                 for(node = node_tree->head; node; node = node->next) {
 410                                         n = node->data;
 411                                         if(n->inkey) {
 412                                                 free(n->inkey);
 413                                                 n->inkey = NULL;
 414                                         }
 415                                 }
 416
 417                                 send_key_changed(broadcast, myself);
 418                                 keyexpires = now + keylifetime;
 419                         }
 420
 421                         if(contradicting_del_edge && contradicting_add_edge) {
 422                                 logger(LOG_WARNING, "Possible node with same Name as us!");
 423
 424                                 if(rand() % 3 == 0) {
 425                                         logger(LOG_ERR, "Shutting down, check configuration of all nodes for duplicate Names!");
 426                                         running = false;
 427                                         break;
 428                                 }
 429
 430                                 contradicting_add_edge = 0;
 431                                 contradicting_del_edge = 0;
 432                         }
 433                 }
 434
 435                 if(sigalrm) {
 436                         avl_node_t *node;
 437                         logger(LOG_INFO, "Flushing event queue");
 438                         expire_events();
 439                         for(node = connection_tree->head; node; node = node->next) {
 440                                 connection_t *c = node->data;
 441                                 send_ping(c);
 442                         }
 443                         sigalrm = false;
 444                 }
 445
 446                 while((event = get_expired_event())) {
 447                         event->handler(event->data);
 448                         free_event(event);
 449                 }
 450
 451                 if(sighup) {
 452                         connection_t *c;
 453                         avl_node_t *node, *next;
 454                         char *fname;
 455                         struct stat s;
 456
 457                         sighup = false;
 458
 459                         /* Reread our own configuration file */
 460
 461                         exit_configuration(&config_tree);
 462                         init_configuration(&config_tree);
 463
 464                         if(!read_server_config()) {
 465                                 logger(LOG_ERR, "Unable to reread configuration file, exitting.");
 466                                 return 1;
 467                         }
 468
 469                         /* Cancel non-active outgoing connections */
 470
 471                         for(node = connection_tree->head; node; node = next) {
 472                                 next = node->next;
 473                                 c = node->data;
 474
 475                                 c->outgoing = NULL;
 476
 477                                 if(c->status.connecting) {
 478                                         terminate_connection(c, false);
 479                                         connection_del(c);
 480                                 }
 481                         }
 482
 483                         /* Wipe list of outgoing connections */
 484
 485                         for(list_node_t *node = outgoing_list->head; node; node = node->next) {
 486                                 outgoing_t *outgoing = node->data;
 487
 488                                 if(outgoing->event)
 489                                         event_del(outgoing->event);
 490                         }
 491
 492                         list_delete_list(outgoing_list);
 493
 494                         /* Close connections to hosts that have a changed or deleted host config file */
 495
 496                         for(node = connection_tree->head; node; node = node->next) {
 497                                 c = node->data;
 498
 499                                 xasprintf(&fname, "%s/hosts/%s", confbase, c->name);
 500                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 501                                         terminate_connection(c, c->status.active);
 502                                 free(fname);
 503                         }
 504
 505                         last_config_check = now;
 506
 507                         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 508
 509                         if(strictsubnets) {
 510                                 subnet_t *subnet;
 511
 512                                 for(node = subnet_tree->head; node; node = node->next) {
 513                                         subnet = node->data;
 514                                         subnet->expires = 1;
 515                                 }
 516
 517                                 load_all_subnets();
 518
 519                                 for(node = subnet_tree->head; node; node = next) {
 520                                         next = node->next;
 521                                         subnet = node->data;
 522                                         if(subnet->expires == 1) {
 523                                                 send_del_subnet(broadcast, subnet);
 524                                                 if(subnet->owner->status.reachable)
 525                                                         subnet_update(subnet->owner, subnet, false);
 526                                                 subnet_del(subnet->owner, subnet);
 527                                         } else if(subnet->expires == -1) {
 528                                                 subnet->expires = 0;
 529                                         } else {
 530                                                 send_add_subnet(broadcast, subnet);
 531                                                 if(subnet->owner->status.reachable)
 532                                                         subnet_update(subnet->owner, subnet, true);
 533                                         }
 534                                 }
 535                         }
 536
 537                         /* Try to make outgoing connections */
 538
 539                         try_outgoing_connections();
 540                 }
 541
 542                 /* Dump graph if wanted every 60 seconds*/
 543
 544                 if(last_graph_dump + 60 < now) {
 545                         dump_graph();
 546                         last_graph_dump = now;
 547                 }
 548         }
 549
 550         return 0;
 551 }