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                   2000-2013 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 #ifdef HAVE_RESOLV_H
  40 #include <resolv.h>
  41 #endif
  42
  43 int contradicting_add_edge = 0;
  44 int contradicting_del_edge = 0;
  45 static int sleeptime = 10;
  46 time_t last_config_check = 0;
  47 static timeout_t pingtimer;
  48 static timeout_t periodictimer;
  49
  50 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  51
  52 void purge(void) {
  53         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
  54
  55         /* Remove all edges and subnets owned by unreachable nodes. */
  56
  57         for splay_each(node_t, n, node_tree) {
  58                 if(!n->status.reachable) {
  59                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
  60
  61                         for splay_each(subnet_t, s, n->subnet_tree) {
  62                                 send_del_subnet(everyone, s);
  63                                 if(!strictsubnets)
  64                                         subnet_del(n, s);
  65                         }
  66
  67                         for splay_each(edge_t, e, n->edge_tree) {
  68                                 if(!tunnelserver)
  69                                         send_del_edge(everyone, e);
  70                                 edge_del(e);
  71                         }
  72                 }
  73         }
  74
  75         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  76
  77         for splay_each(node_t, n, node_tree) {
  78                 if(!n->status.reachable) {
  79                         for splay_each(edge_t, e, edge_weight_tree)
  80                                 if(e->to == n)
  81                                         return;
  82
  83                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
  84                                 /* in strictsubnets mode do not delete nodes with subnets */
  85                                 node_del(n);
  86                 }
  87         }
  88 }
  89
  90 /*
  91   Terminate a connection:
  92   - Mark it as inactive
  93   - Remove the edge representing this connection
  94   - Kill it with fire
  95   - Check if we need to retry making an outgoing connection
  96 */
  97 void terminate_connection(connection_t *c, bool report) {
  98         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
  99
 100         c->status.active = false;
 101
 102         if(c->node && c->node->connection == c)
 103                 c->node->connection = NULL;
 104
 105         if(c->edge) {
 106                 if(report && !tunnelserver)
 107                         send_del_edge(everyone, c->edge);
 108
 109                 edge_del(c->edge);
 110                 c->edge = NULL;
 111
 112                 /* Run MST and SSSP algorithms */
 113
 114                 graph();
 115
 116                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 117
 118                 if(report && !c->node->status.reachable) {
 119                         edge_t *e;
 120                         e = lookup_edge(c->node, myself);
 121                         if(e) {
 122                                 if(!tunnelserver)
 123                                         send_del_edge(everyone, e);
 124                                 edge_del(e);
 125                         }
 126                 }
 127         }
 128
 129         outgoing_t *outgoing = c->outgoing;
 130         connection_del(c);
 131
 132         /* Check if this was our outgoing connection */
 133
 134         if(outgoing)
 135                 do_outgoing_connection(outgoing);
 136
 137 #ifndef HAVE_MINGW
 138         /* Clean up dead proxy processes */
 139
 140         while(waitpid(-1, NULL, WNOHANG) > 0);
 141 #endif
 142 }
 143
 144 /*
 145   Check if the other end is active.
 146   If we have sent packets, but didn't receive any,
 147   then possibly the other end is dead. We send a
 148   PING request over the meta connection. If the other
 149   end does not reply in time, we consider them dead
 150   and close the connection.
 151 */
 152 static void timeout_handler(void *data) {
 153         for list_each(connection_t, c, connection_list) {
 154                 if(c->status.control)
 155                         continue;
 156
 157                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 158                         if(c->status.active) {
 159                                 if(c->status.pinged) {
 160                                         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);
 161                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
 162                                         send_ping(c);
 163                                         continue;
 164                                 } else {
 165                                         continue;
 166                                 }
 167                         } else {
 168                                 if(c->status.connecting)
 169                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
 170                                 else
 171                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
 172                         }
 173                         terminate_connection(c, c->status.active);
 174                 }
 175         }
 176
 177         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
 178 }
 179
 180 static void periodic_handler(void *data) {
 181         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
 182            This usually only happens when another node has the same Name as this node.
 183            If so, sleep for a short while to prevent a storm of contradicting messages.
 184         */
 185
 186         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 187                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 188                 usleep(sleeptime * 1000000LL);
 189                 sleeptime *= 2;
 190                 if(sleeptime < 0)
 191                         sleeptime = 3600;
 192         } else {
 193                 sleeptime /= 2;
 194                 if(sleeptime < 10)
 195                         sleeptime = 10;
 196         }
 197
 198         contradicting_add_edge = 0;
 199         contradicting_del_edge = 0;
 200
 201         /* If AutoConnect is set, check if we need to make or break connections. */
 202
 203         if(autoconnect && node_tree->count > 1) {
 204                 /* Count number of active connections */
 205                 int nc = 0;
 206                 for list_each(connection_t, c, connection_list) {
 207                         if(c->status.active && !c->status.control)
 208                                 nc++;
 209                 }
 210
 211                 if(nc < 3) {
 212                         /* Not enough active connections, try to add one.
 213                            Choose a random node, if we don't have a connection to it,
 214                            and we are not already trying to make one, create an
 215                            outgoing connection to this node.
 216                         */
 217                         int r = rand() % node_tree->count;
 218                         int i = 0;
 219
 220                         for splay_each(node_t, n, node_tree) {
 221                                 if(i++ != r)
 222                                         continue;
 223
 224                                 if(n->connection)
 225                                         break;
 226
 227                                 bool found = false;
 228
 229                                 for list_each(outgoing_t, outgoing, outgoing_list) {
 230                                         if(!strcmp(outgoing->name, n->name)) {
 231                                                 found = true;
 232                                                 break;
 233                                         }
 234                                 }
 235
 236                                 if(!found) {
 237                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
 238                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 239                                         outgoing->name = xstrdup(n->name);
 240                                         list_insert_tail(outgoing_list, outgoing);
 241                                         setup_outgoing_connection(outgoing);
 242                                 }
 243                                 break;
 244                         }
 245                 } else if(nc > 3) {
 246                         /* Too many active connections, try to remove one.
 247                            Choose a random outgoing connection to a node
 248                            that has at least one other connection.
 249                         */
 250                         int r = rand() % nc;
 251                         int i = 0;
 252
 253                         for list_each(connection_t, c, connection_list) {
 254                                 if(!c->status.active || c->status.control)
 255                                         continue;
 256
 257                                 if(i++ != r)
 258                                         continue;
 259
 260                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
 261                                         break;
 262
 263                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
 264                                 list_delete(outgoing_list, c->outgoing);
 265                                 c->outgoing = NULL;
 266                                 terminate_connection(c, c->status.active);
 267                                 break;
 268                         }
 269                 }
 270
 271                 if(nc >= 3) {
 272                         /* If we have enough active connections,
 273                            remove any pending outgoing connections.
 274                         */
 275                         for list_each(outgoing_t, o, outgoing_list) {
 276                                 bool found = false;
 277                                 for list_each(connection_t, c, connection_list) {
 278                                         if(c->outgoing == o) {
 279                                                 found = true;
 280                                                 break;
 281                                         }
 282                                 }
 283                                 if(!found) {
 284                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
 285                                         list_delete_node(outgoing_list, node);
 286                                 }
 287                         }
 288                 }
 289         }
 290
 291         timeout_set(data, &(struct timeval){5, rand() % 100000});
 292 }
 293
 294 void handle_meta_connection_data(connection_t *c) {
 295         if (!receive_meta(c)) {
 296                 terminate_connection(c, c->status.active);
 297                 return;
 298         }
 299 }
 300
 301 #ifndef HAVE_MINGW
 302 static void sigterm_handler(void *data) {
 303         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 304         event_exit();
 305 }
 306
 307 static void sighup_handler(void *data) {
 308         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 309         reopenlogger();
 310         if(reload_configuration())
 311                 exit(1);
 312 }
 313
 314 static void sigalrm_handler(void *data) {
 315         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 316 #ifdef HAVE_DECL_RES_INIT
 317         res_init();
 318 #endif
 319         retry();
 320 }
 321 #endif
 322
 323 int reload_configuration(void) {
 324         char *fname = NULL;
 325
 326         /* Reread our own configuration file */
 327
 328         exit_configuration(&config_tree);
 329         init_configuration(&config_tree);
 330
 331         if(!read_server_config()) {
 332                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
 333                 return EINVAL;
 334         }
 335
 336         read_config_options(config_tree, NULL);
 337
 338         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
 339         read_config_file(config_tree, fname);
 340         free(fname);
 341
 342         /* Parse some options that are allowed to be changed while tinc is running */
 343
 344         setup_myself_reloadable();
 345
 346         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 347
 348         if(strictsubnets) {
 349                 for splay_each(subnet_t, subnet, subnet_tree)
 350                         subnet->expires = 1;
 351
 352                 load_all_subnets();
 353
 354                 for splay_each(subnet_t, subnet, subnet_tree) {
 355                         if(subnet->expires == 1) {
 356                                 send_del_subnet(everyone, subnet);
 357                                 if(subnet->owner->status.reachable)
 358                                         subnet_update(subnet->owner, subnet, false);
 359                                 subnet_del(subnet->owner, subnet);
 360                         } else if(subnet->expires == -1) {
 361                                 subnet->expires = 0;
 362                         } else {
 363                                 send_add_subnet(everyone, subnet);
 364                                 if(subnet->owner->status.reachable)
 365                                         subnet_update(subnet->owner, subnet, true);
 366                         }
 367                 }
 368         } else { /* Only read our own subnets back in */
 369                 for splay_each(subnet_t, subnet, myself->subnet_tree)
 370                         if(!subnet->expires)
 371                                 subnet->expires = 1;
 372
 373                 config_t *cfg = lookup_config(config_tree, "Subnet");
 374
 375                 while(cfg) {
 376                         subnet_t *subnet, *s2;
 377
 378                         if(!get_config_subnet(cfg, &subnet))
 379                                 continue;
 380
 381                         if((s2 = lookup_subnet(myself, subnet))) {
 382                                 if(s2->expires == 1)
 383                                         s2->expires = 0;
 384
 385                                 free_subnet(subnet);
 386                         } else {
 387                                 subnet_add(myself, subnet);
 388                                 send_add_subnet(everyone, subnet);
 389                                 subnet_update(myself, subnet, true);
 390                         }
 391
 392                         cfg = lookup_config_next(config_tree, cfg);
 393                 }
 394
 395                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
 396                         if(subnet->expires == 1) {
 397                                 send_del_subnet(everyone, subnet);
 398                                 subnet_update(myself, subnet, false);
 399                                 subnet_del(myself, subnet);
 400                         }
 401                 }
 402         }
 403
 404         /* Try to make outgoing connections */
 405
 406         try_outgoing_connections();
 407
 408         /* Close connections to hosts that have a changed or deleted host config file */
 409
 410         for list_each(connection_t, c, connection_list) {
 411                 if(c->status.control)
 412                         continue;
 413
 414                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
 415                 struct stat s;
 416                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 417                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
 418                         terminate_connection(c, c->status.active);
 419                 }
 420                 free(fname);
 421         }
 422
 423         last_config_check = now.tv_sec;
 424
 425         return 0;
 426 }
 427
 428 void retry(void) {
 429         /* Reset the reconnection timers for all outgoing connections */
 430         for list_each(outgoing_t, outgoing, outgoing_list) {
 431                 outgoing->timeout = 0;
 432                 if(outgoing->ev.cb)
 433                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
 434         }
 435
 436         /* Check for outgoing connections that are in progress, and reset their ping timers */
 437         for list_each(connection_t, c, connection_list) {
 438                 if(c->outgoing && !c->node)
 439                         c->last_ping_time = 0;
 440         }
 441
 442         /* Kick the ping timeout handler */
 443         timeout_set(&pingtimer, &(struct timeval){0, 0});
 444 }
 445
 446 /*
 447   this is where it all happens...
 448 */
 449 int main_loop(void) {
 450         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 451         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
 452
 453 #ifndef HAVE_MINGW
 454         signal_t sighup = {0};
 455         signal_t sigterm = {0};
 456         signal_t sigquit = {0};
 457         signal_t sigint = {0};
 458         signal_t sigalrm = {0};
 459
 460         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
 461         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
 462         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
 463         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
 464         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
 465 #endif
 466
 467         if(!event_loop()) {
 468                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", strerror(errno));
 469                 return 1;
 470         }
 471
 472 #ifndef HAVE_MINGW
 473         signal_del(&sighup);
 474         signal_del(&sigterm);
 475         signal_del(&sigquit);
 476         signal_del(&sigint);
 477         signal_del(&sigalrm);
 478 #endif
 479
 480         timeout_del(&periodictimer);
 481         timeout_del(&pingtimer);
 482
 483         return 0;
 484 }