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(int fd, short events, void *event) {
 141         time_t now = time(NULL);
 142
 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) {
 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 - c->last_ping_time);
 151                                 } else if(c->last_ping_time + pinginterval <= now) {
 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         event_add(event, &(struct timeval){pingtimeout, rand() % 100000});
 168 }
 169
 170 static void periodic_handler(int fd, short events, void *event) {
 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 = xmalloc_and_zero(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         event_add(event, &(struct timeval){5, rand() % 100000});
 282 }
 283
 284 void handle_meta_connection_data(int fd, short events, void *data) {
 285         connection_t *c = data;
 286         int result;
 287         socklen_t len = sizeof result;
 288
 289         if(c->status.connecting) {
 290                 c->status.connecting = false;
 291
 292                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 293
 294                 if(!result)
 295                         finish_connecting(c);
 296                 else {
 297                         logger(DEBUG_CONNECTIONS, LOG_DEBUG, "Error while connecting to %s (%s): %s", c->name, c->hostname, sockstrerror(result));
 298                         terminate_connection(c, false);
 299                         return;
 300                 }
 301         }
 302
 303         if (!receive_meta(c)) {
 304                 terminate_connection(c, c->status.active);
 305                 return;
 306         }
 307 }
 308
 309 static void sigterm_handler(int signal, short events, void *data) {
 310         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(signal));
 311         event_loopexit(NULL);
 312 }
 313
 314 static void sighup_handler(int signal, short events, void *data) {
 315         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(signal));
 316         reopenlogger();
 317         reload_configuration();
 318 }
 319
 320 static void sigalrm_handler(int signal, short events, void *data) {
 321         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(signal));
 322         retry();
 323 }
 324
 325 int reload_configuration(void) {
 326         char *fname;
 327
 328         /* Reread our own configuration file */
 329
 330         exit_configuration(&config_tree);
 331         init_configuration(&config_tree);
 332
 333         if(!read_server_config()) {
 334                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file, exitting.");
 335                 event_loopexit(NULL);
 336                 return EINVAL;
 337         }
 338
 339         read_config_options(config_tree, NULL);
 340
 341         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
 342         read_config_file(config_tree, fname);
 343         free(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                         subnet->expires = 1;
 354
 355                 load_all_subnets();
 356
 357                 for splay_each(subnet_t, subnet, subnet_tree) {
 358                         if(subnet->expires == 1) {
 359                                 send_del_subnet(everyone, subnet);
 360                                 if(subnet->owner->status.reachable)
 361                                         subnet_update(subnet->owner, subnet, false);
 362                                 subnet_del(subnet->owner, subnet);
 363                         } else if(subnet->expires == -1) {
 364                                 subnet->expires = 0;
 365                         } else {
 366                                 send_add_subnet(everyone, subnet);
 367                                 if(subnet->owner->status.reachable)
 368                                         subnet_update(subnet->owner, subnet, true);
 369                         }
 370                 }
 371         } else { /* Only read our own subnets back in */
 372                 for splay_each(subnet_t, subnet, myself->subnet_tree)
 373                         if(!subnet->expires)
 374                                 subnet->expires = 1;
 375
 376                 config_t *cfg = lookup_config(config_tree, "Subnet");
 377
 378                 while(cfg) {
 379                         subnet_t *subnet, *s2;
 380
 381                         if(!get_config_subnet(cfg, &subnet))
 382                                 continue;
 383
 384                         if((s2 = lookup_subnet(myself, subnet))) {
 385                                 if(s2->expires == 1)
 386                                         s2->expires = 0;
 387
 388                                 free_subnet(subnet);
 389                         } else {
 390                                 subnet_add(myself, subnet);
 391                                 send_add_subnet(everyone, subnet);
 392                                 subnet_update(myself, subnet, true);
 393                         }
 394
 395                         cfg = lookup_config_next(config_tree, cfg);
 396                 }
 397
 398                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
 399                         if(subnet->expires == 1) {
 400                                 send_del_subnet(everyone, subnet);
 401                                 subnet_update(myself, subnet, false);
 402                                 subnet_del(myself, subnet);
 403                         }
 404                 }
 405         }
 406
 407         /* Try to make outgoing connections */
 408
 409         try_outgoing_connections();
 410
 411         /* Close connections to hosts that have a changed or deleted host config file */
 412
 413         for list_each(connection_t, c, connection_list) {
 414                 if(c->status.control)
 415                         continue;
 416
 417                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
 418                 struct stat s;
 419                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 420                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
 421                         terminate_connection(c, c->status.active);
 422                 }
 423                 free(fname);
 424         }
 425
 426         last_config_check = time(NULL);
 427
 428         return 0;
 429 }
 430
 431 void retry(void) {
 432         for list_each(connection_t, c, connection_list) {
 433                 if(c->outgoing && !c->node) {
 434                         if(timeout_initialized(&c->outgoing->ev))
 435                                 event_del(&c->outgoing->ev);
 436                         if(c->status.connecting)
 437                                 close(c->socket);
 438                         c->outgoing->timeout = 0;
 439                         terminate_connection(c, c->status.active);
 440                 }
 441         }
 442 }
 443
 444 /*
 445   this is where it all happens...
 446 */
 447 int main_loop(void) {
 448         struct event timeout_event;
 449         struct event periodic_event;
 450
 451         timeout_set(&timeout_event, timeout_handler, &timeout_event);
 452         event_add(&timeout_event, &(struct timeval){pingtimeout, rand() % 100000});
 453
 454         timeout_set(&periodic_event, periodic_handler, &periodic_event);
 455         event_add(&periodic_event, &(struct timeval){5, rand() % 100000});
 456
 457 #ifndef HAVE_MINGW
 458         struct event sighup_event;
 459         struct event sigterm_event;
 460         struct event sigquit_event;
 461         struct event sigalrm_event;
 462
 463         signal_set(&sighup_event, SIGHUP, sighup_handler, NULL);
 464         signal_add(&sighup_event, NULL);
 465         signal_set(&sigterm_event, SIGTERM, sigterm_handler, NULL);
 466         signal_add(&sigterm_event, NULL);
 467         signal_set(&sigquit_event, SIGQUIT, sigterm_handler, NULL);
 468         signal_add(&sigquit_event, NULL);
 469         signal_set(&sigalrm_event, SIGALRM, sigalrm_handler, NULL);
 470         signal_add(&sigalrm_event, NULL);
 471 #endif
 472
 473         if(event_loop(0) < 0) {
 474                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", strerror(errno));
 475                 return 1;
 476         }
 477
 478 #ifndef HAVE_MINGW
 479         signal_del(&sighup_event);
 480         signal_del(&sigterm_event);
 481         signal_del(&sigquit_event);
 482         signal_del(&sigalrm_event);
 483 #endif
 484
 485         event_del(&timeout_event);
 486
 487         return 0;
 488 }