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