tinc-vpn.org Git - tinc/blob - src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2015 Guus Sliepen <guus@tinc-vpn.org>
   5                   2006      Scott Lamb <slamb@slamb.org>
   6                   2011      Loïc Grenié <loic.grenie@gmail.com>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License along
  19     with this program; if not, write to the Free Software Foundation, Inc.,
  20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21 */
  22
  23 #include "system.h"
  24
  25 #include "utils.h"
  26 #include "conf.h"
  27 #include "connection.h"
  28 #include "device.h"
  29 #include "graph.h"
  30 #include "logger.h"
  31 #include "meta.h"
  32 #include "names.h"
  33 #include "net.h"
  34 #include "netutl.h"
  35 #include "protocol.h"
  36 #include "subnet.h"
  37 #include "xalloc.h"
  38
  39 int contradicting_add_edge = 0;
  40 int contradicting_del_edge = 0;
  41 static int sleeptime = 10;
  42 time_t last_config_check = 0;
  43 static timeout_t pingtimer;
  44 static timeout_t periodictimer;
  45
  46 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  47
  48 void purge(void) {
  49         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
  50
  51         /* Remove all edges and subnets owned by unreachable nodes. */
  52
  53         for splay_each(node_t, n, node_tree) {
  54                 if(!n->status.reachable) {
  55                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
  56
  57                         for splay_each(subnet_t, s, n->subnet_tree) {
  58                                 send_del_subnet(everyone, s);
  59                                 if(!strictsubnets)
  60                                         subnet_del(n, s);
  61                         }
  62
  63                         for splay_each(edge_t, e, n->edge_tree) {
  64                                 if(!tunnelserver)
  65                                         send_del_edge(everyone, e);
  66                                 edge_del(e);
  67                         }
  68                 }
  69         }
  70
  71         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  72
  73         for splay_each(node_t, n, node_tree) {
  74                 if(!n->status.reachable) {
  75                         for splay_each(edge_t, e, edge_weight_tree)
  76                                 if(e->to == n)
  77                                         return;
  78
  79                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
  80                                 /* in strictsubnets mode do not delete nodes with subnets */
  81                                 node_del(n);
  82                 }
  83         }
  84 }
  85
  86 /*
  87   Terminate a connection:
  88   - Mark it as inactive
  89   - Remove the edge representing this connection
  90   - Kill it with fire
  91   - Check if we need to retry making an outgoing connection
  92 */
  93 void terminate_connection(connection_t *c, bool report) {
  94         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
  95
  96         if(c->node && c->node->connection == c)
  97                 c->node->connection = NULL;
  98
  99         if(c->edge) {
 100                 if(report && !tunnelserver)
 101                         send_del_edge(everyone, c->edge);
 102
 103                 edge_del(c->edge);
 104                 c->edge = NULL;
 105
 106                 /* Run MST and SSSP algorithms */
 107
 108                 graph();
 109
 110                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 111
 112                 if(report && !c->node->status.reachable) {
 113                         edge_t *e;
 114                         e = lookup_edge(c->node, myself);
 115                         if(e) {
 116                                 if(!tunnelserver)
 117                                         send_del_edge(everyone, e);
 118                                 edge_del(e);
 119                         }
 120                 }
 121         }
 122
 123         outgoing_t *outgoing = c->outgoing;
 124         connection_del(c);
 125
 126         /* Check if this was our outgoing connection */
 127
 128         if(outgoing)
 129                 do_outgoing_connection(outgoing);
 130
 131 #ifndef HAVE_MINGW
 132         /* Clean up dead proxy processes */
 133
 134         while(waitpid(-1, NULL, WNOHANG) > 0);
 135 #endif
 136 }
 137
 138 /*
 139   Check if the other end is active.
 140   If we have sent packets, but didn't receive any,
 141   then possibly the other end is dead. We send a
 142   PING request over the meta connection. If the other
 143   end does not reply in time, we consider them dead
 144   and close the connection.
 145 */
 146 static void timeout_handler(void *data) {
 147         for list_each(connection_t, c, connection_list) {
 148                 if(c->status.control)
 149                         continue;
 150
 151                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 152                         if(c->edge) {
 153                                 try_tx(c->node, false);
 154                                 if(c->status.pinged) {
 155                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "%s (%s) didn't respond to PING in %ld seconds", c->name, c->hostname, (long)(now.tv_sec - c->last_ping_time));
 156                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
 157                                         send_ping(c);
 158                                         continue;
 159                                 } else {
 160                                         continue;
 161                                 }
 162                         } else {
 163                                 if(c->status.connecting)
 164                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
 165                                 else
 166                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
 167                         }
 168                         terminate_connection(c, c->edge);
 169                 }
 170
 171         }
 172
 173         timeout_set(data, &(struct timeval){1, rand() % 100000});
 174 }
 175
 176 static void periodic_handler(void *data) {
 177         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
 178            This usually only happens when another node has the same Name as this node.
 179            If so, sleep for a short while to prevent a storm of contradicting messages.
 180         */
 181
 182         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 183                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 184                 nanosleep(&(struct timespec){sleeptime, 0}, NULL);
 185                 sleeptime *= 2;
 186                 if(sleeptime < 0)
 187                         sleeptime = 3600;
 188         } else {
 189                 sleeptime /= 2;
 190                 if(sleeptime < 10)
 191                         sleeptime = 10;
 192         }
 193
 194         contradicting_add_edge = 0;
 195         contradicting_del_edge = 0;
 196
 197         /* If AutoConnect is set, check if we need to make or break connections. */
 198
 199         if(autoconnect && node_tree->count > 1) {
 200                 /* Count number of active connections */
 201                 int nc = 0;
 202                 for list_each(connection_t, c, connection_list) {
 203                         if(c->edge)
 204                                 nc++;
 205                 }
 206
 207                 if(nc < 3) {
 208                         /* Not enough active connections, try to add one.
 209                            Choose a random node, if we don't have a connection to it,
 210                            and we are not already trying to make one, create an
 211                            outgoing connection to this node.
 212                         */
 213                         int count = 0;
 214                         for splay_each(node_t, n, node_tree) {
 215                                 if(n == myself || n->connection || !(n->status.has_address || n->status.reachable))
 216                                         continue;
 217                                 count++;
 218                         }
 219
 220                         if(!count)
 221                                 goto end;
 222
 223                         int r = rand() % count;
 224
 225                         for splay_each(node_t, n, node_tree) {
 226                                 if(n == myself || n->connection || !(n->status.has_address || n->status.reachable))
 227                                         continue;
 228
 229                                 if(r--)
 230                                         continue;
 231
 232                                 bool found = false;
 233
 234                                 for list_each(outgoing_t, outgoing, outgoing_list) {
 235                                         if(!strcmp(outgoing->name, n->name)) {
 236                                                 found = true;
 237                                                 break;
 238                                         }
 239                                 }
 240
 241                                 if(!found) {
 242                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
 243                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 244                                         outgoing->name = xstrdup(n->name);
 245                                         list_insert_tail(outgoing_list, outgoing);
 246                                         setup_outgoing_connection(outgoing);
 247                                 }
 248
 249                                 break;
 250                         }
 251                 } else if(nc > 3) {
 252                         /* Too many active connections, try to remove one.
 253                            Choose a random outgoing connection to a node
 254                            that has at least one other connection.
 255                         */
 256                         int r = rand() % nc;
 257                         int i = 0;
 258
 259                         for list_each(connection_t, c, connection_list) {
 260                                 if(!c->edge)
 261                                         continue;
 262
 263                                 if(i++ != r)
 264                                         continue;
 265
 266                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
 267                                         break;
 268
 269                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
 270                                 list_delete(outgoing_list, c->outgoing);
 271                                 c->outgoing = NULL;
 272                                 terminate_connection(c, c->edge);
 273                                 break;
 274                         }
 275                 }
 276
 277                 if(nc >= 3) {
 278                         /* If we have enough active connections,
 279                            remove any pending outgoing connections.
 280                         */
 281                         for list_each(outgoing_t, o, outgoing_list) {
 282                                 bool found = false;
 283                                 for list_each(connection_t, c, connection_list) {
 284                                         if(c->outgoing == o) {
 285                                                 found = true;
 286                                                 break;
 287                                         }
 288                                 }
 289                                 if(!found) {
 290                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
 291                                         list_delete_node(outgoing_list, node);
 292                                 }
 293                         }
 294                 }
 295         }
 296
 297 end:
 298         timeout_set(data, &(struct timeval){5, rand() % 100000});
 299 }
 300
 301 void handle_meta_connection_data(connection_t *c) {
 302         if (!receive_meta(c)) {
 303                 terminate_connection(c, c->edge);
 304                 return;
 305         }
 306 }
 307
 308 #ifndef HAVE_MINGW
 309 static void sigterm_handler(void *data) {
 310         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 311         event_exit();
 312 }
 313
 314 static void sighup_handler(void *data) {
 315         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 316         reopenlogger();
 317         if(reload_configuration())
 318                 exit(1);
 319 }
 320
 321 static void sigalrm_handler(void *data) {
 322         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 323         retry();
 324 }
 325 #endif
 326
 327 int reload_configuration(void) {
 328         char fname[PATH_MAX];
 329
 330         /* Reread our own configuration file */
 331
 332         exit_configuration(&config_tree);
 333         init_configuration(&config_tree);
 334
 335         if(!read_server_config()) {
 336                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
 337                 return EINVAL;
 338         }
 339
 340         read_config_options(config_tree, NULL);
 341
 342         snprintf(fname, sizeof fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
 343         read_config_file(config_tree, fname);
 344
 345         /* Parse some options that are allowed to be changed while tinc is running */
 346
 347         setup_myself_reloadable();
 348
 349         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 350
 351         if(strictsubnets) {
 352                 for splay_each(subnet_t, subnet, subnet_tree)
 353                         if (subnet->owner)
 354                                 subnet->expires = 1;
 355         }
 356
 357         for splay_each(node_t, n, node_tree)
 358                 n->status.has_address = false;
 359
 360         load_all_nodes();
 361
 362         if(strictsubnets) {
 363                 for splay_each(subnet_t, subnet, subnet_tree) {
 364                         if (!subnet->owner)
 365                                 continue;
 366                         if(subnet->expires == 1) {
 367                                 send_del_subnet(everyone, subnet);
 368                                 if(subnet->owner->status.reachable)
 369                                         subnet_update(subnet->owner, subnet, false);
 370                                 subnet_del(subnet->owner, subnet);
 371                         } else if(subnet->expires == -1) {
 372                                 subnet->expires = 0;
 373                         } else {
 374                                 send_add_subnet(everyone, subnet);
 375                                 if(subnet->owner->status.reachable)
 376                                         subnet_update(subnet->owner, subnet, true);
 377                         }
 378                 }
 379         } else { /* Only read our own subnets back in */
 380                 for splay_each(subnet_t, subnet, myself->subnet_tree)
 381                         if(!subnet->expires)
 382                                 subnet->expires = 1;
 383
 384                 config_t *cfg = lookup_config(config_tree, "Subnet");
 385
 386                 while(cfg) {
 387                         subnet_t *subnet, *s2;
 388
 389                         if(!get_config_subnet(cfg, &subnet))
 390                                 continue;
 391
 392                         if((s2 = lookup_subnet(myself, subnet))) {
 393                                 if(s2->expires == 1)
 394                                         s2->expires = 0;
 395
 396                                 free_subnet(subnet);
 397                         } else {
 398                                 subnet_add(myself, subnet);
 399                                 send_add_subnet(everyone, subnet);
 400                                 subnet_update(myself, subnet, true);
 401                         }
 402
 403                         cfg = lookup_config_next(config_tree, cfg);
 404                 }
 405
 406                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
 407                         if(subnet->expires == 1) {
 408                                 send_del_subnet(everyone, subnet);
 409                                 subnet_update(myself, subnet, false);
 410                                 subnet_del(myself, subnet);
 411                         }
 412                 }
 413         }
 414
 415         /* Try to make outgoing connections */
 416
 417         try_outgoing_connections();
 418
 419         /* Close connections to hosts that have a changed or deleted host config file */
 420
 421         for list_each(connection_t, c, connection_list) {
 422                 if(c->status.control)
 423                         continue;
 424
 425                 snprintf(fname, sizeof fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
 426                 struct stat s;
 427                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 428                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
 429                         terminate_connection(c, c->edge);
 430                 }
 431         }
 432
 433         last_config_check = now.tv_sec;
 434
 435         return 0;
 436 }
 437
 438 void retry(void) {
 439         /* Reset the reconnection timers for all outgoing connections */
 440         for list_each(outgoing_t, outgoing, outgoing_list) {
 441                 outgoing->timeout = 0;
 442                 if(outgoing->ev.cb)
 443                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
 444         }
 445
 446         /* Check for outgoing connections that are in progress, and reset their ping timers */
 447         for list_each(connection_t, c, connection_list) {
 448                 if(c->outgoing && !c->node)
 449                         c->last_ping_time = 0;
 450         }
 451
 452         /* Kick the ping timeout handler */
 453         timeout_set(&pingtimer, &(struct timeval){0, 0});
 454 }
 455
 456 /*
 457   this is where it all happens...
 458 */
 459 int main_loop(void) {
 460         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 461         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){0, 0});
 462
 463 #ifndef HAVE_MINGW
 464         signal_t sighup = {0};
 465         signal_t sigterm = {0};
 466         signal_t sigquit = {0};
 467         signal_t sigint = {0};
 468         signal_t sigalrm = {0};
 469
 470         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
 471         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
 472         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
 473         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
 474         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
 475 #endif
 476
 477         if(!event_loop()) {
 478                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 479                 return 1;
 480         }
 481
 482 #ifndef HAVE_MINGW
 483         signal_del(&sighup);
 484         signal_del(&sigterm);
 485         signal_del(&sigquit);
 486         signal_del(&sigint);
 487         signal_del(&sigalrm);
 488 #endif
 489
 490         timeout_del(&periodictimer);
 491         timeout_del(&pingtimer);
 492
 493         return 0;
 494 }