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