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