www.tinc-vpn.org Git - tinc/blob - src/net.c

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2003 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000-2003 Guus Sliepen <guus@sliepen.eu.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id: net.c,v 1.35.4.190 2003/07/12 17:41:45 guus Exp $
  21 */
  22
  23 #include "config.h"
  24
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <netdb.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <signal.h>
  32 #include <sys/time.h>
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35 #include <unistd.h>
  36 #include <sys/ioctl.h>
  37 /* SunOS really wants sys/socket.h BEFORE net/if.h,
  38    and FreeBSD wants these lines below the rest. */
  39 #include <arpa/inet.h>
  40 #include <sys/socket.h>
  41 #include <net/if.h>
  42 #ifdef HAVE_NETINET_IN_SYSTM_H
  43 #include <netinet/in_systm.h>
  44 #endif
  45 #include <netinet/in.h>
  46 #ifdef HAVE_NETINET_IP_H
  47 #include <netinet/ip.h>
  48 #endif
  49 #ifdef HAVE_NETINET_TCP_H
  50 #include <netinet/tcp.h>
  51 #endif
  52
  53 #include <openssl/rand.h>
  54
  55 #include <utils.h>
  56 #include <xalloc.h>
  57 #include <avl_tree.h>
  58 #include <list.h>
  59
  60 #include "conf.h"
  61 #include "connection.h"
  62 #include "meta.h"
  63 #include "net.h"
  64 #include "netutl.h"
  65 #include "process.h"
  66 #include "protocol.h"
  67 #include "subnet.h"
  68 #include "graph.h"
  69 #include "process.h"
  70 #include "route.h"
  71 #include "device.h"
  72 #include "event.h"
  73 #include "logger.h"
  74
  75 #include "system.h"
  76
  77 int do_purge = 0;
  78 int sighup = 0;
  79 int sigalrm = 0;
  80
  81 time_t now = 0;
  82
  83 /* Purge edges and subnets of unreachable nodes. Use carefully. */
  84
  85 static void purge(void)
  86 {
  87         avl_node_t *nnode, *nnext, *enode, *enext, *snode, *snext;
  88         node_t *n;
  89         edge_t *e;
  90         subnet_t *s;
  91
  92         cp();
  93
  94         ifdebug(PROTOCOL) logger(LOG_DEBUG, _("Purging unreachable nodes"));
  95
  96         for(nnode = node_tree->head; nnode; nnode = nnext) {
  97                 nnext = nnode->next;
  98                 n = (node_t *) nnode->data;
  99
 100                 if(!n->status.reachable) {
 101                         ifdebug(SCARY_THINGS) logger(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
 102                                            n->hostname);
 103
 104                         for(snode = n->subnet_tree->head; snode; snode = snext) {
 105                                 snext = snode->next;
 106                                 s = (subnet_t *) snode->data;
 107                                 send_del_subnet(broadcast, s);
 108                                 subnet_del(n, s);
 109                         }
 110
 111                         for(enode = n->edge_tree->head; enode; enode = enext) {
 112                                 enext = enode->next;
 113                                 e = (edge_t *) enode->data;
 114                                 send_del_edge(broadcast, e);
 115                                 edge_del(e);
 116                         }
 117
 118                         node_del(n);
 119                 }
 120         }
 121 }
 122
 123 /*
 124   put all file descriptors in an fd_set array
 125   While we're at it, purge stuff that needs to be removed.
 126 */
 127 static int build_fdset(fd_set * fs)
 128 {
 129         avl_node_t *node, *next;
 130         connection_t *c;
 131         int i, max = 0;
 132
 133         cp();
 134
 135         FD_ZERO(fs);
 136
 137         for(node = connection_tree->head; node; node = next) {
 138                 next = node->next;
 139                 c = (connection_t *) node->data;
 140
 141                 if(c->status.remove) {
 142                         connection_del(c);
 143                         if(!connection_tree->head)
 144                                 purge();
 145                 } else {
 146                         FD_SET(c->socket, fs);
 147                         if(c->socket > max)
 148                                 max = c->socket;
 149                 }
 150         }
 151
 152         for(i = 0; i < listen_sockets; i++) {
 153                 FD_SET(listen_socket[i].tcp, fs);
 154                 if(listen_socket[i].tcp > max)
 155                         max = listen_socket[i].tcp;
 156                 FD_SET(listen_socket[i].udp, fs);
 157                 if(listen_socket[i].udp > max)
 158                         max = listen_socket[i].udp;
 159         }
 160
 161         FD_SET(device_fd, fs);
 162         if(device_fd > max)
 163                 max = device_fd;
 164
 165         return max;
 166 }
 167
 168 /*
 169   Terminate a connection:
 170   - Close the socket
 171   - Remove associated edge and tell other connections about it if report = 1
 172   - Check if we need to retry making an outgoing connection
 173   - Deactivate the host
 174 */
 175 void terminate_connection(connection_t *c, int report)
 176 {
 177         cp();
 178
 179         if(c->status.remove)
 180                 return;
 181
 182         ifdebug(CONNECTIONS) logger(LOG_NOTICE, _("Closing connection with %s (%s)"),
 183                            c->name, c->hostname);
 184
 185         c->status.remove = 1;
 186         c->status.active = 0;
 187
 188         if(c->node)
 189                 c->node->connection = NULL;
 190
 191         if(c->socket)
 192                 close(c->socket);
 193
 194         if(c->edge) {
 195                 if(report)
 196                         send_del_edge(broadcast, c->edge);
 197
 198                 edge_del(c->edge);
 199
 200                 /* Run MST and SSSP algorithms */
 201
 202                 graph();
 203         }
 204
 205         /* Check if this was our outgoing connection */
 206
 207         if(c->outgoing) {
 208                 retry_outgoing(c->outgoing);
 209                 c->outgoing = NULL;
 210         }
 211 }
 212
 213 /*
 214   Check if the other end is active.
 215   If we have sent packets, but didn't receive any,
 216   then possibly the other end is dead. We send a
 217   PING request over the meta connection. If the other
 218   end does not reply in time, we consider them dead
 219   and close the connection.
 220 */
 221 static void check_dead_connections(void)
 222 {
 223         avl_node_t *node, *next;
 224         connection_t *c;
 225
 226         cp();
 227
 228         for(node = connection_tree->head; node; node = next) {
 229                 next = node->next;
 230                 c = (connection_t *) node->data;
 231
 232                 if(c->last_ping_time + pingtimeout < now) {
 233                         if(c->status.active) {
 234                                 if(c->status.pinged) {
 235                                         ifdebug(CONNECTIONS) logger(LOG_INFO, _("%s (%s) didn't respond to PING"),
 236                                                            c->name, c->hostname);
 237                                         c->status.timeout = 1;
 238                                         terminate_connection(c, 1);
 239                                 } else {
 240                                         send_ping(c);
 241                                 }
 242                         } else {
 243                                 if(c->status.remove) {
 244                                         logger(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 245                                                    c->name, c->hostname, c->status);
 246                                         connection_del(c);
 247                                         continue;
 248                                 }
 249                                 ifdebug(CONNECTIONS) logger(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 250                                                    c->name, c->hostname);
 251                                 terminate_connection(c, 0);
 252                         }
 253                 }
 254         }
 255 }
 256
 257 /*
 258   check all connections to see if anything
 259   happened on their sockets
 260 */
 261 static void check_network_activity(fd_set * f)
 262 {
 263         connection_t *c;
 264         avl_node_t *node;
 265         int result, i;
 266         int len = sizeof(result);
 267         vpn_packet_t packet;
 268
 269         cp();
 270
 271         if(FD_ISSET(device_fd, f)) {
 272                 if(!read_packet(&packet))
 273                         route_outgoing(&packet);
 274         }
 275
 276         for(node = connection_tree->head; node; node = node->next) {
 277                 c = (connection_t *) node->data;
 278
 279                 if(c->status.remove)
 280                         continue;
 281
 282                 if(FD_ISSET(c->socket, f)) {
 283                         if(c->status.connecting) {
 284                                 c->status.connecting = 0;
 285                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 286
 287                                 if(!result)
 288                                         finish_connecting(c);
 289                                 else {
 290                                         ifdebug(CONNECTIONS) logger(LOG_DEBUG,
 291                                                            _("Error while connecting to %s (%s): %s"),
 292                                                            c->name, c->hostname, strerror(result));
 293                                         close(c->socket);
 294                                         do_outgoing_connection(c);
 295                                         continue;
 296                                 }
 297                         }
 298
 299                         if(receive_meta(c) < 0) {
 300                                 terminate_connection(c, c->status.active);
 301                                 continue;
 302                         }
 303                 }
 304         }
 305
 306         for(i = 0; i < listen_sockets; i++) {
 307                 if(FD_ISSET(listen_socket[i].udp, f))
 308                         handle_incoming_vpn_data(listen_socket[i].udp);
 309
 310                 if(FD_ISSET(listen_socket[i].tcp, f))
 311                         handle_new_meta_connection(listen_socket[i].tcp);
 312         }
 313 }
 314
 315 /*
 316   this is where it all happens...
 317 */
 318 void main_loop(void)
 319 {
 320         fd_set fset;
 321         struct timeval tv;
 322         int r, maxfd;
 323         time_t last_ping_check, last_config_check;
 324         event_t *event;
 325
 326         cp();
 327
 328         last_ping_check = now;
 329         last_config_check = now;
 330         srand(now);
 331
 332         for(;;) {
 333                 now = time(NULL);
 334
 335                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 336                 tv.tv_usec = 0;
 337
 338                 maxfd = build_fdset(&fset);
 339
 340                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 341
 342                 if(r < 0) {
 343                         if(errno != EINTR && errno != EAGAIN) {
 344                                 logger(LOG_ERR, _("Error while waiting for input: %s"),
 345                                            strerror(errno));
 346                                 cp_trace();
 347                                 dump_connections();
 348                                 return;
 349                         }
 350
 351                         continue;
 352                 }
 353
 354                 check_network_activity(&fset);
 355
 356                 if(do_purge) {
 357                         purge();
 358                         do_purge = 0;
 359                 }
 360
 361                 /* Let's check if everybody is still alive */
 362
 363                 if(last_ping_check + pingtimeout < now) {
 364                         check_dead_connections();
 365                         last_ping_check = now;
 366
 367                         if(routing_mode == RMODE_SWITCH)
 368                                 age_mac();
 369
 370                         age_past_requests();
 371
 372                         /* Should we regenerate our key? */
 373
 374                         if(keyexpires < now) {
 375                                 ifdebug(STATUS) logger(LOG_INFO, _("Regenerating symmetric key"));
 376
 377                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 378                                 EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 379                                 send_key_changed(broadcast, myself);
 380                                 keyexpires = now + keylifetime;
 381                         }
 382                 }
 383
 384
 385                 while((event = get_expired_event())) {
 386                         event->handler(event->data);
 387                         free(event);
 388                 }
 389
 390                 if(sigalrm) {
 391                         logger(LOG_INFO, _("Flushing event queue"));
 392
 393                         while(event_tree->head) {
 394                                 event = (event_t *) event_tree->head->data;
 395                                 event->handler(event->data);
 396                                 event_del(event);
 397                         }
 398                         sigalrm = 0;
 399                 }
 400
 401                 if(sighup) {
 402                         connection_t *c;
 403                         avl_node_t *node;
 404                         char *fname;
 405                         struct stat s;
 406
 407                         sighup = 0;
 408
 409                         /* Reread our own configuration file */
 410
 411                         exit_configuration(&config_tree);
 412                         init_configuration(&config_tree);
 413
 414                         if(read_server_config()) {
 415                                 logger(LOG_ERR, _("Unable to reread configuration file, exitting."));
 416                                 exit(1);
 417                         }
 418
 419                         /* Close connections to hosts that have a changed or deleted host config file */
 420
 421                         for(node = connection_tree->head; node; node = node->next) {
 422                                 c = (connection_t *) node->data;
 423
 424                                 if(c->outgoing) {
 425                                         free(c->outgoing->name);
 426                                         freeaddrinfo(c->outgoing->ai);
 427                                         free(c->outgoing);
 428                                         c->outgoing = NULL;
 429                                 }
 430
 431                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 432                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 433                                         terminate_connection(c, c->status.active);
 434                                 free(fname);
 435                         }
 436
 437                         last_config_check = now;
 438
 439                         /* Try to make outgoing connections */
 440
 441                         try_outgoing_connections();
 442
 443                         continue;
 444                 }
 445         }
 446 }