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                   2000-2012 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 "net.h"
  33 #include "netutl.h"
  34 #include "process.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
  44 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  45
  46 void purge(void) {
  47         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
  48
  49         /* Remove all edges and subnets owned by unreachable nodes. */
  50
  51         for splay_each(node_t, n, node_tree) {
  52                 if(!n->status.reachable) {
  53                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
  54
  55                         for splay_each(subnet_t, s, n->subnet_tree) {
  56                                 send_del_subnet(everyone, s);
  57                                 if(!strictsubnets)
  58                                         subnet_del(n, s);
  59                         }
  60
  61                         for splay_each(edge_t, e, n->edge_tree) {
  62                                 if(!tunnelserver)
  63                                         send_del_edge(everyone, e);
  64                                 edge_del(e);
  65                         }
  66                 }
  67         }
  68
  69         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  70
  71         for splay_each(node_t, n, node_tree) {
  72                 if(!n->status.reachable) {
  73                         for splay_each(edge_t, e, edge_weight_tree)
  74                                 if(e->to == n)
  75                                         return;
  76
  77                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
  78                                 /* in strictsubnets mode do not delete nodes with subnets */
  79                                 node_del(n);
  80                 }
  81         }
  82 }
  83
  84 /*
  85   Terminate a connection:
  86   - Mark it as inactive
  87   - Remove the edge representing this connection
  88   - Kill it with fire
  89   - Check if we need to retry making an outgoing connection
  90 */
  91 void terminate_connection(connection_t *c, bool report) {
  92         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
  93
  94         c->status.active = false;
  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
 132 /*
 133   Check if the other end is active.
 134   If we have sent packets, but didn't receive any,
 135   then possibly the other end is dead. We send a
 136   PING request over the meta connection. If the other
 137   end does not reply in time, we consider them dead
 138   and close the connection.
 139 */
 140 static void timeout_handler(void *data) {
 141         for list_each(connection_t, c, connection_list) {
 142                 if(c->status.control)
 143                         continue;
 144
 145                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 146                         if(c->status.active) {
 147                                 if(c->status.pinged) {
 148                                         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);
 149                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
 150                                         send_ping(c);
 151                                         continue;
 152                                 } else {
 153                                         continue;
 154                                 }
 155                         } else {
 156                                 if(c->status.connecting)
 157                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
 158                                 else
 159                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
 160                         }
 161                         terminate_connection(c, c->status.active);
 162                 }
 163         }
 164
 165         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
 166 }
 167
 168 static void periodic_handler(void *data) {
 169         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
 170            This usually only happens when another node has the same Name as this node.
 171            If so, sleep for a short while to prevent a storm of contradicting messages.
 172         */
 173
 174         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 175                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 176                 usleep(sleeptime * 1000000LL);
 177                 sleeptime *= 2;
 178                 if(sleeptime < 0)
 179                         sleeptime = 3600;
 180         } else {
 181                 sleeptime /= 2;
 182                 if(sleeptime < 10)
 183                         sleeptime = 10;
 184         }
 185
 186         contradicting_add_edge = 0;
 187         contradicting_del_edge = 0;
 188
 189         /* If AutoConnect is set, check if we need to make or break connections. */
 190
 191         if(autoconnect && node_tree->count > 1) {
 192                 /* Count number of active connections */
 193                 int nc = 0;
 194                 for list_each(connection_t, c, connection_list) {
 195                         if(c->status.active && !c->status.control)
 196                                 nc++;
 197                 }
 198
 199                 if(nc < autoconnect) {
 200                         /* Not enough active connections, try to add one.
 201                            Choose a random node, if we don't have a connection to it,
 202                            and we are not already trying to make one, create an
 203                            outgoing connection to this node.
 204                         */
 205                         int r = rand() % node_tree->count;
 206                         int i = 0;
 207
 208                         for splay_each(node_t, n, node_tree) {
 209                                 if(i++ != r)
 210                                         continue;
 211
 212                                 if(n->connection)
 213                                         break;
 214
 215                                 bool found = false;
 216
 217                                 for list_each(outgoing_t, outgoing, outgoing_list) {
 218                                         if(!strcmp(outgoing->name, n->name)) {
 219                                                 found = true;
 220                                                 break;
 221                                         }
 222                                 }
 223
 224                                 if(!found) {
 225                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
 226                                         outgoing_t *outgoing = xmalloc_and_zero(sizeof *outgoing);
 227                                         outgoing->name = xstrdup(n->name);
 228                                         list_insert_tail(outgoing_list, outgoing);
 229                                         setup_outgoing_connection(outgoing);
 230                                 }
 231                                 break;
 232                         }
 233                 } else if(nc > autoconnect) {
 234                         /* Too many active connections, try to remove one.
 235                            Choose a random outgoing connection to a node
 236                            that has at least one other connection.
 237                         */
 238                         int r = rand() % nc;
 239                         int i = 0;
 240
 241                         for list_each(connection_t, c, connection_list) {
 242                                 if(!c->status.active || c->status.control)
 243                                         continue;
 244
 245                                 if(i++ != r)
 246                                         continue;
 247
 248                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
 249                                         break;
 250
 251                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
 252                                 list_delete(outgoing_list, c->outgoing);
 253                                 c->outgoing = NULL;
 254                                 terminate_connection(c, c->status.active);
 255                                 break;
 256                         }
 257                 }
 258
 259                 if(nc >= autoconnect) {
 260                         /* If we have enough active connections,
 261                            remove any pending outgoing connections.
 262                         */
 263                         for list_each(outgoing_t, o, outgoing_list) {
 264                                 bool found = false;
 265                                 for list_each(connection_t, c, connection_list) {
 266                                         if(c->outgoing == o) {
 267                                                 found = true;
 268                                                 break;
 269                                         }
 270                                 }
 271                                 if(!found) {
 272                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
 273                                         list_delete_node(outgoing_list, node);
 274                                 }
 275                         }
 276                 }
 277         }
 278
 279         timeout_set(data, &(struct timeval){5, rand() % 100000});
 280 }
 281
 282 void handle_meta_connection_data(connection_t *c) {
 283         int result;
 284         socklen_t len = sizeof result;
 285
 286         if(c->status.connecting) {
 287                 c->status.connecting = false;
 288
 289                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 290
 291                 if(!result)
 292                         finish_connecting(c);
 293                 else {
 294                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
 295                         terminate_connection(c, false);
 296                         return;
 297                 }
 298         }
 299
 300         if (!receive_meta(c)) {
 301                 terminate_connection(c, c->status.active);
 302                 return;
 303         }
 304 }
 305
 306 static void sigterm_handler(void *data) {
 307         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 308         event_exit();
 309 }
 310
 311 static void sighup_handler(void *data) {
 312         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 313         reopenlogger();
 314         reload_configuration();
 315 }
 316
 317 static void sigalrm_handler(void *data) {
 318         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 319         retry();
 320 }
 321
 322 int reload_configuration(void) {
 323         char *fname;
 324
 325         /* Reread our own configuration file */
 326
 327         exit_configuration(&config_tree);
 328         init_configuration(&config_tree);
 329
 330         if(!read_server_config()) {
 331                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file, exitting.");
 332                 event_exit();
 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 = time(NULL);
 424
 425         return 0;
 426 }
 427
 428 void retry(void) {
 429         for list_each(connection_t, c, connection_list) {
 430                 if(c->outgoing && !c->node) {
 431                         timeout_del(&c->outgoing->ev);
 432                         if(c->status.connecting)
 433                                 close(c->socket);
 434                         c->outgoing->timeout = 0;
 435                         terminate_connection(c, c->status.active);
 436                 }
 437         }
 438 }
 439
 440 /*
 441   this is where it all happens...
 442 */
 443 int main_loop(void) {
 444         timeout_t pingtimer = {{0}};
 445         timeout_t periodictimer = {{0}};
 446
 447         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 448         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
 449
 450 #ifndef HAVE_MINGW
 451         signal_t sighup = {0};
 452         signal_t sigterm = {0};
 453         signal_t sigquit = {0};
 454         signal_t sigalrm = {0};
 455
 456         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
 457         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
 458         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
 459         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
 460 #endif
 461
 462         if(!event_loop()) {
 463                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", strerror(errno));
 464                 return 1;
 465         }
 466
 467 #ifndef HAVE_MINGW
 468         signal_del(&sighup);
 469         signal_del(&sigalrm);
 470         signal_del(&sigquit);
 471         signal_del(&sigterm);
 472 #endif
 473
 474         timeout_del(&periodictimer);
 475         timeout_del(&pingtimer);
 476
 477         return 0;
 478 }