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         if(c->node && c->node->connection == c)
 101                 c->node->connection = NULL;
 102
 103         if(c->edge) {
 104                 if(report && !tunnelserver)
 105                         send_del_edge(everyone, c->edge);
 106
 107                 edge_del(c->edge);
 108                 c->edge = NULL;
 109
 110                 /* Run MST and SSSP algorithms */
 111
 112                 graph();
 113
 114                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 115
 116                 if(report && !c->node->status.reachable) {
 117                         edge_t *e;
 118                         e = lookup_edge(c->node, myself);
 119                         if(e) {
 120                                 if(!tunnelserver)
 121                                         send_del_edge(everyone, e);
 122                                 edge_del(e);
 123                         }
 124                 }
 125         }
 126
 127         outgoing_t *outgoing = c->outgoing;
 128         connection_del(c);
 129
 130         /* Check if this was our outgoing connection */
 131
 132         if(outgoing)
 133                 do_outgoing_connection(outgoing);
 134
 135 #ifndef HAVE_MINGW
 136         /* Clean up dead proxy processes */
 137
 138         while(waitpid(-1, NULL, WNOHANG) > 0);
 139 #endif
 140 }
 141
 142 /*
 143   Check if the other end is active.
 144   If we have sent packets, but didn't receive any,
 145   then possibly the other end is dead. We send a
 146   PING request over the meta connection. If the other
 147   end does not reply in time, we consider them dead
 148   and close the connection.
 149 */
 150 static void timeout_handler(void *data) {
 151         for list_each(connection_t, c, connection_list) {
 152                 if(c->status.control)
 153                         continue;
 154
 155                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 156                         if(c->edge) {
 157                                 if(c->status.pinged) {
 158                                         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);
 159                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
 160                                         send_ping(c);
 161                                         continue;
 162                                 } else {
 163                                         continue;
 164                                 }
 165                         } else {
 166                                 if(c->status.connecting)
 167                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
 168                                 else
 169                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
 170                         }
 171                         terminate_connection(c, c->edge);
 172                 }
 173         }
 174
 175         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
 176 }
 177
 178 static void periodic_handler(void *data) {
 179         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
 180            This usually only happens when another node has the same Name as this node.
 181            If so, sleep for a short while to prevent a storm of contradicting messages.
 182         */
 183
 184         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 185                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 186                 usleep(sleeptime * 1000000LL);
 187                 sleeptime *= 2;
 188                 if(sleeptime < 0)
 189                         sleeptime = 3600;
 190         } else {
 191                 sleeptime /= 2;
 192                 if(sleeptime < 10)
 193                         sleeptime = 10;
 194         }
 195
 196         contradicting_add_edge = 0;
 197         contradicting_del_edge = 0;
 198
 199         /* If AutoConnect is set, check if we need to make or break connections. */
 200
 201         if(autoconnect && node_tree->count > 1) {
 202                 /* Count number of active connections */
 203                 int nc = 0;
 204                 for list_each(connection_t, c, connection_list) {
 205                         if(c->edge)
 206                                 nc++;
 207                 }
 208
 209                 if(nc < 3) {
 210                         /* Not enough active connections, try to add one.
 211                            Choose a random node, if we don't have a connection to it,
 212                            and we are not already trying to make one, create an
 213                            outgoing connection to this node.
 214                         */
 215                         int r = rand() % node_tree->count;
 216                         int i = 0;
 217
 218                         for splay_each(node_t, n, node_tree) {
 219                                 if(i++ != r)
 220                                         continue;
 221
 222                                 if(n->connection)
 223                                         break;
 224
 225                                 bool found = false;
 226
 227                                 for list_each(outgoing_t, outgoing, outgoing_list) {
 228                                         if(!strcmp(outgoing->name, n->name)) {
 229                                                 found = true;
 230                                                 break;
 231                                         }
 232                                 }
 233
 234                                 if(!found) {
 235                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
 236                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 237                                         outgoing->name = xstrdup(n->name);
 238                                         list_insert_tail(outgoing_list, outgoing);
 239                                         setup_outgoing_connection(outgoing);
 240                                 }
 241                                 break;
 242                         }
 243                 } else if(nc > 3) {
 244                         /* Too many active connections, try to remove one.
 245                            Choose a random outgoing connection to a node
 246                            that has at least one other connection.
 247                         */
 248                         int r = rand() % nc;
 249                         int i = 0;
 250
 251                         for list_each(connection_t, c, connection_list) {
 252                                 if(!c->edge)
 253                                         continue;
 254
 255                                 if(i++ != r)
 256                                         continue;
 257
 258                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
 259                                         break;
 260
 261                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
 262                                 list_delete(outgoing_list, c->outgoing);
 263                                 c->outgoing = NULL;
 264                                 terminate_connection(c, c->edge);
 265                                 break;
 266                         }
 267                 }
 268
 269                 if(nc >= 3) {
 270                         /* If we have enough active connections,
 271                            remove any pending outgoing connections.
 272                         */
 273                         for list_each(outgoing_t, o, outgoing_list) {
 274                                 bool found = false;
 275                                 for list_each(connection_t, c, connection_list) {
 276                                         if(c->outgoing == o) {
 277                                                 found = true;
 278                                                 break;
 279                                         }
 280                                 }
 281                                 if(!found) {
 282                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
 283                                         list_delete_node(outgoing_list, node);
 284                                 }
 285                         }
 286                 }
 287         }
 288
 289         timeout_set(data, &(struct timeval){5, rand() % 100000});
 290 }
 291
 292 void handle_meta_connection_data(connection_t *c) {
 293         if (!receive_meta(c)) {
 294                 terminate_connection(c, c->edge);
 295                 return;
 296         }
 297 }
 298
 299 #ifndef HAVE_MINGW
 300 static void sigterm_handler(void *data) {
 301         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 302         event_exit();
 303 }
 304
 305 static void sighup_handler(void *data) {
 306         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 307         reopenlogger();
 308         if(reload_configuration())
 309                 exit(1);
 310 }
 311
 312 static void sigalrm_handler(void *data) {
 313         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 314 #ifdef HAVE_DECL_RES_INIT
 315         res_init();
 316 #endif
 317         retry();
 318 }
 319 #endif
 320
 321 int reload_configuration(void) {
 322         char *fname = NULL;
 323
 324         /* Reread our own configuration file */
 325
 326         exit_configuration(&config_tree);
 327         init_configuration(&config_tree);
 328
 329         if(!read_server_config()) {
 330                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
 331                 return EINVAL;
 332         }
 333
 334         read_config_options(config_tree, NULL);
 335
 336         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
 337         read_config_file(config_tree, fname);
 338         free(fname);
 339
 340         /* Parse some options that are allowed to be changed while tinc is running */
 341
 342         setup_myself_reloadable();
 343
 344         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 345
 346         if(strictsubnets) {
 347                 for splay_each(subnet_t, subnet, subnet_tree)
 348                         if (subnet->owner)
 349                                 subnet->expires = 1;
 350
 351                 load_all_subnets();
 352
 353                 for splay_each(subnet_t, subnet, subnet_tree) {
 354                         if (!subnet->owner)
 355                                 continue;
 356                         if(subnet->expires == 1) {
 357                                 send_del_subnet(everyone, subnet);
 358                                 if(subnet->owner->status.reachable)
 359                                         subnet_update(subnet->owner, subnet, false);
 360                                 subnet_del(subnet->owner, subnet);
 361                         } else if(subnet->expires == -1) {
 362                                 subnet->expires = 0;
 363                         } else {
 364                                 send_add_subnet(everyone, subnet);
 365                                 if(subnet->owner->status.reachable)
 366                                         subnet_update(subnet->owner, subnet, true);
 367                         }
 368                 }
 369         } else { /* Only read our own subnets back in */
 370                 for splay_each(subnet_t, subnet, myself->subnet_tree)
 371                         if(!subnet->expires)
 372                                 subnet->expires = 1;
 373
 374                 config_t *cfg = lookup_config(config_tree, "Subnet");
 375
 376                 while(cfg) {
 377                         subnet_t *subnet, *s2;
 378
 379                         if(!get_config_subnet(cfg, &subnet))
 380                                 continue;
 381
 382                         if((s2 = lookup_subnet(myself, subnet))) {
 383                                 if(s2->expires == 1)
 384                                         s2->expires = 0;
 385
 386                                 free_subnet(subnet);
 387                         } else {
 388                                 subnet_add(myself, subnet);
 389                                 send_add_subnet(everyone, subnet);
 390                                 subnet_update(myself, subnet, true);
 391                         }
 392
 393                         cfg = lookup_config_next(config_tree, cfg);
 394                 }
 395
 396                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
 397                         if(subnet->expires == 1) {
 398                                 send_del_subnet(everyone, subnet);
 399                                 subnet_update(myself, subnet, false);
 400                                 subnet_del(myself, subnet);
 401                         }
 402                 }
 403         }
 404
 405         /* Try to make outgoing connections */
 406
 407         try_outgoing_connections();
 408
 409         /* Close connections to hosts that have a changed or deleted host config file */
 410
 411         for list_each(connection_t, c, connection_list) {
 412                 if(c->status.control)
 413                         continue;
 414
 415                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
 416                 struct stat s;
 417                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 418                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
 419                         terminate_connection(c, c->edge);
 420                 }
 421                 free(fname);
 422         }
 423
 424         last_config_check = now.tv_sec;
 425
 426         return 0;
 427 }
 428
 429 void retry(void) {
 430         /* Reset the reconnection timers for all outgoing connections */
 431         for list_each(outgoing_t, outgoing, outgoing_list) {
 432                 outgoing->timeout = 0;
 433                 if(outgoing->ev.cb)
 434                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
 435         }
 436
 437         /* Check for outgoing connections that are in progress, and reset their ping timers */
 438         for list_each(connection_t, c, connection_list) {
 439                 if(c->outgoing && !c->node)
 440                         c->last_ping_time = 0;
 441         }
 442
 443         /* Kick the ping timeout handler */
 444         timeout_set(&pingtimer, &(struct timeval){0, 0});
 445 }
 446
 447 /*
 448   this is where it all happens...
 449 */
 450 int main_loop(void) {
 451         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 452         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
 453
 454 #ifndef HAVE_MINGW
 455         signal_t sighup = {0};
 456         signal_t sigterm = {0};
 457         signal_t sigquit = {0};
 458         signal_t sigint = {0};
 459         signal_t sigalrm = {0};
 460
 461         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
 462         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
 463         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
 464         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
 465         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
 466 #endif
 467
 468         if(!event_loop()) {
 469                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", sockstrerror(sockerrno));
 470                 return 1;
 471         }
 472
 473 #ifndef HAVE_MINGW
 474         signal_del(&sighup);
 475         signal_del(&sigterm);
 476         signal_del(&sigquit);
 477         signal_del(&sigint);
 478         signal_del(&sigalrm);
 479 #endif
 480
 481         timeout_del(&periodictimer);
 482         timeout_del(&pingtimer);
 483
 484         return 0;
 485 }