git.meshlink.io Git - meshlink/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 "graph.h"
  29 #include "logger.h"
  30 #include "meta.h"
  31 #include "names.h"
  32 #include "net.h"
  33 #include "netutl.h"
  34 #include "protocol.h"
  35 #include "subnet.h"
  36 #include "xalloc.h"
  37
  38 int contradicting_add_edge = 0;
  39 int contradicting_del_edge = 0;
  40 static int sleeptime = 10;
  41 time_t last_config_check = 0;
  42 static timeout_t pingtimer;
  43 static timeout_t periodictimer;
  44
  45 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  46
  47 void purge(void) {
  48         logger(DEBUG_PROTOCOL, LOG_DEBUG, "Purging unreachable nodes");
  49
  50         /* Remove all edges and subnets owned by unreachable nodes. */
  51
  52         for splay_each(node_t, n, node_tree) {
  53                 if(!n->status.reachable) {
  54                         logger(DEBUG_SCARY_THINGS, LOG_DEBUG, "Purging node %s (%s)", n->name, n->hostname);
  55
  56                         for splay_each(subnet_t, s, n->subnet_tree) {
  57                                 send_del_subnet(everyone, s);
  58                                 if(!strictsubnets)
  59                                         subnet_del(n, s);
  60                         }
  61
  62                         for splay_each(edge_t, e, n->edge_tree) {
  63                                 if(!tunnelserver)
  64                                         send_del_edge(everyone, e);
  65                                 edge_del(e);
  66                         }
  67                 }
  68         }
  69
  70         /* Check if anyone else claims to have an edge to an unreachable node. If not, delete node. */
  71
  72         for splay_each(node_t, n, node_tree) {
  73                 if(!n->status.reachable) {
  74                         for splay_each(edge_t, e, edge_weight_tree)
  75                                 if(e->to == n)
  76                                         return;
  77
  78                         if(!autoconnect && (!strictsubnets || !n->subnet_tree->head))
  79                                 /* in strictsubnets mode do not delete nodes with subnets */
  80                                 node_del(n);
  81                 }
  82         }
  83 }
  84
  85 /*
  86   Terminate a connection:
  87   - Mark it as inactive
  88   - Remove the edge representing this connection
  89   - Kill it with fire
  90   - Check if we need to retry making an outgoing connection
  91 */
  92 void terminate_connection(connection_t *c, bool report) {
  93         logger(DEBUG_CONNECTIONS, LOG_NOTICE, "Closing connection with %s (%s)", c->name, c->hostname);
  94
  95         c->status.active = false;
  96
  97         if(c->node && c->node->connection == c)
  98                 c->node->connection = NULL;
  99
 100         if(c->edge) {
 101                 if(report && !tunnelserver)
 102                         send_del_edge(everyone, c->edge);
 103
 104                 edge_del(c->edge);
 105                 c->edge = NULL;
 106
 107                 /* Run MST and SSSP algorithms */
 108
 109                 graph();
 110
 111                 /* If the node is not reachable anymore but we remember it had an edge to us, clean it up */
 112
 113                 if(report && !c->node->status.reachable) {
 114                         edge_t *e;
 115                         e = lookup_edge(c->node, myself);
 116                         if(e) {
 117                                 if(!tunnelserver)
 118                                         send_del_edge(everyone, e);
 119                                 edge_del(e);
 120                         }
 121                 }
 122         }
 123
 124         outgoing_t *outgoing = c->outgoing;
 125         connection_del(c);
 126
 127         /* Check if this was our outgoing connection */
 128
 129         if(outgoing)
 130                 do_outgoing_connection(outgoing);
 131
 132 #ifndef HAVE_MINGW
 133         /* Clean up dead proxy processes */
 134
 135         while(waitpid(-1, NULL, WNOHANG) > 0);
 136 #endif
 137 }
 138
 139 /*
 140   Check if the other end is active.
 141   If we have sent packets, but didn't receive any,
 142   then possibly the other end is dead. We send a
 143   PING request over the meta connection. If the other
 144   end does not reply in time, we consider them dead
 145   and close the connection.
 146 */
 147 static void timeout_handler(void *data) {
 148         for list_each(connection_t, c, connection_list) {
 149                 if(c->status.control)
 150                         continue;
 151
 152                 if(c->last_ping_time + pingtimeout <= now.tv_sec) {
 153                         if(c->status.active) {
 154                                 if(c->status.pinged) {
 155                                         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);
 156                                 } else if(c->last_ping_time + pinginterval <= now.tv_sec) {
 157                                         send_ping(c);
 158                                         continue;
 159                                 } else {
 160                                         continue;
 161                                 }
 162                         } else {
 163                                 if(c->status.connecting)
 164                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout while connecting to %s (%s)", c->name, c->hostname);
 165                                 else
 166                                         logger(DEBUG_CONNECTIONS, LOG_WARNING, "Timeout from %s (%s) during authentication", c->name, c->hostname);
 167                         }
 168                         terminate_connection(c, c->status.active);
 169                 }
 170         }
 171
 172         timeout_set(data, &(struct timeval){pingtimeout, rand() % 100000});
 173 }
 174
 175 static void periodic_handler(void *data) {
 176         /* Check if there are too many contradicting ADD_EDGE and DEL_EDGE messages.
 177            This usually only happens when another node has the same Name as this node.
 178            If so, sleep for a short while to prevent a storm of contradicting messages.
 179         */
 180
 181         if(contradicting_del_edge > 100 && contradicting_add_edge > 100) {
 182                 logger(DEBUG_ALWAYS, LOG_WARNING, "Possible node with same Name as us! Sleeping %d seconds.", sleeptime);
 183                 usleep(sleeptime * 1000000LL);
 184                 sleeptime *= 2;
 185                 if(sleeptime < 0)
 186                         sleeptime = 3600;
 187         } else {
 188                 sleeptime /= 2;
 189                 if(sleeptime < 10)
 190                         sleeptime = 10;
 191         }
 192
 193         contradicting_add_edge = 0;
 194         contradicting_del_edge = 0;
 195
 196         /* If AutoConnect is set, check if we need to make or break connections. */
 197
 198         if(autoconnect && node_tree->count > 1) {
 199                 /* Count number of active connections */
 200                 int nc = 0;
 201                 for list_each(connection_t, c, connection_list) {
 202                         if(c->status.active && !c->status.control)
 203                                 nc++;
 204                 }
 205
 206                 if(nc < autoconnect) {
 207                         /* Not enough active connections, try to add one.
 208                            Choose a random node, if we don't have a connection to it,
 209                            and we are not already trying to make one, create an
 210                            outgoing connection to this node.
 211                         */
 212                         int r = rand() % node_tree->count;
 213                         int i = 0;
 214
 215                         for splay_each(node_t, n, node_tree) {
 216                                 if(i++ != r)
 217                                         continue;
 218
 219                                 if(n->connection)
 220                                         break;
 221
 222                                 bool found = false;
 223
 224                                 for list_each(outgoing_t, outgoing, outgoing_list) {
 225                                         if(!strcmp(outgoing->name, n->name)) {
 226                                                 found = true;
 227                                                 break;
 228                                         }
 229                                 }
 230
 231                                 if(!found) {
 232                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Autoconnecting to %s", n->name);
 233                                         outgoing_t *outgoing = xzalloc(sizeof *outgoing);
 234                                         outgoing->name = xstrdup(n->name);
 235                                         list_insert_tail(outgoing_list, outgoing);
 236                                         setup_outgoing_connection(outgoing);
 237                                 }
 238                                 break;
 239                         }
 240                 } else if(nc > autoconnect) {
 241                         /* Too many active connections, try to remove one.
 242                            Choose a random outgoing connection to a node
 243                            that has at least one other connection.
 244                         */
 245                         int r = rand() % nc;
 246                         int i = 0;
 247
 248                         for list_each(connection_t, c, connection_list) {
 249                                 if(!c->status.active || c->status.control)
 250                                         continue;
 251
 252                                 if(i++ != r)
 253                                         continue;
 254
 255                                 if(!c->outgoing || !c->node || c->node->edge_tree->count < 2)
 256                                         break;
 257
 258                                 logger(DEBUG_CONNECTIONS, LOG_INFO, "Autodisconnecting from %s", c->name);
 259                                 list_delete(outgoing_list, c->outgoing);
 260                                 c->outgoing = NULL;
 261                                 terminate_connection(c, c->status.active);
 262                                 break;
 263                         }
 264                 }
 265
 266                 if(nc >= autoconnect) {
 267                         /* If we have enough active connections,
 268                            remove any pending outgoing connections.
 269                         */
 270                         for list_each(outgoing_t, o, outgoing_list) {
 271                                 bool found = false;
 272                                 for list_each(connection_t, c, connection_list) {
 273                                         if(c->outgoing == o) {
 274                                                 found = true;
 275                                                 break;
 276                                         }
 277                                 }
 278                                 if(!found) {
 279                                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Cancelled outgoing connection to %s", o->name);
 280                                         list_delete_node(outgoing_list, node);
 281                                 }
 282                         }
 283                 }
 284         }
 285
 286         timeout_set(data, &(struct timeval){5, rand() % 100000});
 287 }
 288
 289 void handle_meta_connection_data(connection_t *c) {
 290         if (!receive_meta(c)) {
 291                 terminate_connection(c, c->status.active);
 292                 return;
 293         }
 294 }
 295
 296 #ifndef HAVE_MINGW
 297 static void sigterm_handler(void *data) {
 298         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 299         event_exit();
 300 }
 301
 302 static void sighup_handler(void *data) {
 303         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 304         reopenlogger();
 305         if(reload_configuration())
 306                 exit(1);
 307 }
 308
 309 static void sigalrm_handler(void *data) {
 310         logger(DEBUG_ALWAYS, LOG_NOTICE, "Got %s signal", strsignal(((signal_t *)data)->signum));
 311         retry();
 312 }
 313 #endif
 314
 315 int reload_configuration(void) {
 316         char *fname = NULL;
 317
 318         /* Reread our own configuration file */
 319
 320         exit_configuration(&config_tree);
 321         init_configuration(&config_tree);
 322
 323         if(!read_server_config()) {
 324                 logger(DEBUG_ALWAYS, LOG_ERR, "Unable to reread configuration file.");
 325                 return EINVAL;
 326         }
 327
 328         read_config_options(config_tree, NULL);
 329
 330         xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, myself->name);
 331         read_config_file(config_tree, fname);
 332         free(fname);
 333
 334         /* Parse some options that are allowed to be changed while tinc is running */
 335
 336         setup_myself_reloadable();
 337
 338         /* If StrictSubnet is set, expire deleted Subnets and read new ones in */
 339
 340         if(strictsubnets) {
 341                 for splay_each(subnet_t, subnet, subnet_tree)
 342                         subnet->expires = 1;
 343
 344                 load_all_subnets();
 345
 346                 for splay_each(subnet_t, subnet, subnet_tree) {
 347                         if(subnet->expires == 1) {
 348                                 send_del_subnet(everyone, subnet);
 349                                 if(subnet->owner->status.reachable)
 350                                         subnet_update(subnet->owner, subnet, false);
 351                                 subnet_del(subnet->owner, subnet);
 352                         } else if(subnet->expires == -1) {
 353                                 subnet->expires = 0;
 354                         } else {
 355                                 send_add_subnet(everyone, subnet);
 356                                 if(subnet->owner->status.reachable)
 357                                         subnet_update(subnet->owner, subnet, true);
 358                         }
 359                 }
 360         } else { /* Only read our own subnets back in */
 361                 for splay_each(subnet_t, subnet, myself->subnet_tree)
 362                         if(!subnet->expires)
 363                                 subnet->expires = 1;
 364
 365                 config_t *cfg = lookup_config(config_tree, "Subnet");
 366
 367                 while(cfg) {
 368                         subnet_t *subnet, *s2;
 369
 370                         if(!get_config_subnet(cfg, &subnet))
 371                                 continue;
 372
 373                         if((s2 = lookup_subnet(myself, subnet))) {
 374                                 if(s2->expires == 1)
 375                                         s2->expires = 0;
 376
 377                                 free_subnet(subnet);
 378                         } else {
 379                                 subnet_add(myself, subnet);
 380                                 send_add_subnet(everyone, subnet);
 381                                 subnet_update(myself, subnet, true);
 382                         }
 383
 384                         cfg = lookup_config_next(config_tree, cfg);
 385                 }
 386
 387                 for splay_each(subnet_t, subnet, myself->subnet_tree) {
 388                         if(subnet->expires == 1) {
 389                                 send_del_subnet(everyone, subnet);
 390                                 subnet_update(myself, subnet, false);
 391                                 subnet_del(myself, subnet);
 392                         }
 393                 }
 394         }
 395
 396         /* Try to make outgoing connections */
 397
 398         try_outgoing_connections();
 399
 400         /* Close connections to hosts that have a changed or deleted host config file */
 401
 402         for list_each(connection_t, c, connection_list) {
 403                 if(c->status.control)
 404                         continue;
 405
 406                 xasprintf(&fname, "%s" SLASH "hosts" SLASH "%s", confbase, c->name);
 407                 struct stat s;
 408                 if(stat(fname, &s) || s.st_mtime > last_config_check) {
 409                         logger(DEBUG_CONNECTIONS, LOG_INFO, "Host config file of %s has been changed", c->name);
 410                         terminate_connection(c, c->status.active);
 411                 }
 412                 free(fname);
 413         }
 414
 415         last_config_check = now.tv_sec;
 416
 417         return 0;
 418 }
 419
 420 void retry(void) {
 421         /* Reset the reconnection timers for all outgoing connections */
 422         for list_each(outgoing_t, outgoing, outgoing_list) {
 423                 outgoing->timeout = 0;
 424                 if(outgoing->ev.cb)
 425                         timeout_set(&outgoing->ev, &(struct timeval){0, 0});
 426         }
 427
 428         /* Check for outgoing connections that are in progress, and reset their ping timers */
 429         for list_each(connection_t, c, connection_list) {
 430                 if(c->outgoing && !c->node)
 431                         c->last_ping_time = 0;
 432         }
 433
 434         /* Kick the ping timeout handler */
 435         timeout_set(&pingtimer, &(struct timeval){0, 0});
 436 }
 437
 438 /*
 439   this is where it all happens...
 440 */
 441 int main_loop(void) {
 442         timeout_add(&pingtimer, timeout_handler, &pingtimer, &(struct timeval){pingtimeout, rand() % 100000});
 443         timeout_add(&periodictimer, periodic_handler, &periodictimer, &(struct timeval){pingtimeout, rand() % 100000});
 444
 445 #ifndef HAVE_MINGW
 446         signal_t sighup = {0};
 447         signal_t sigterm = {0};
 448         signal_t sigquit = {0};
 449         signal_t sigint = {0};
 450         signal_t sigalrm = {0};
 451
 452         signal_add(&sighup, sighup_handler, &sighup, SIGHUP);
 453         signal_add(&sigterm, sigterm_handler, &sigterm, SIGTERM);
 454         signal_add(&sigquit, sigterm_handler, &sigquit, SIGQUIT);
 455         signal_add(&sigint, sigterm_handler, &sigint, SIGINT);
 456         signal_add(&sigalrm, sigalrm_handler, &sigalrm, SIGALRM);
 457 #endif
 458
 459         if(!event_loop()) {
 460                 logger(DEBUG_ALWAYS, LOG_ERR, "Error while waiting for input: %s", strerror(errno));
 461                 return 1;
 462         }
 463
 464 #ifndef HAVE_MINGW
 465         signal_del(&sighup);
 466         signal_del(&sigterm);
 467         signal_del(&sigquit);
 468         signal_del(&sigint);
 469         signal_del(&sigalrm);
 470 #endif
 471
 472         timeout_del(&periodictimer);
 473         timeout_del(&pingtimer);
 474
 475         return 0;
 476 }