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

   1 /*
   2     net.c -- most of the network code
   3     Copyright (C) 1998-2002 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000-2002 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 1.35.4.187 2003/07/06 17:15:25 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 <syslog.h>
  36 #include <unistd.h>
  37 #include <sys/ioctl.h>
  38 /* SunOS really wants sys/socket.h BEFORE net/if.h,
  39    and FreeBSD wants these lines below the rest. */
  40 #include <arpa/inet.h>
  41 #include <sys/socket.h>
  42 #include <net/if.h>
  43 #ifdef HAVE_NETINET_IN_SYSTM_H
  44 #include <netinet/in_systm.h>
  45 #endif
  46 #include <netinet/in.h>
  47 #ifdef HAVE_NETINET_IP_H
  48 #include <netinet/ip.h>
  49 #endif
  50 #ifdef HAVE_NETINET_TCP_H
  51 #include <netinet/tcp.h>
  52 #endif
  53
  54 #include <openssl/rand.h>
  55
  56 #include <utils.h>
  57 #include <xalloc.h>
  58 #include <avl_tree.h>
  59 #include <list.h>
  60
  61 #include "conf.h"
  62 #include "connection.h"
  63 #include "meta.h"
  64 #include "net.h"
  65 #include "netutl.h"
  66 #include "process.h"
  67 #include "protocol.h"
  68 #include "subnet.h"
  69 #include "graph.h"
  70 #include "process.h"
  71 #include "route.h"
  72 #include "device.h"
  73 #include "event.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 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         if(debug_lvl >= DEBUG_PROTOCOL)
  95                 syslog(LOG_DEBUG, _("Purging unreachable nodes"));
  96
  97         for(nnode = node_tree->head; nnode; nnode = nnext) {
  98                 nnext = nnode->next;
  99                 n = (node_t *) nnode->data;
 100
 101                 if(!n->status.reachable) {
 102                         if(debug_lvl >= DEBUG_SCARY_THINGS)
 103                                 syslog(LOG_DEBUG, _("Purging node %s (%s)"), n->name,
 104                                            n->hostname);
 105
 106                         for(snode = n->subnet_tree->head; snode; snode = snext) {
 107                                 snext = snode->next;
 108                                 s = (subnet_t *) snode->data;
 109                                 send_del_subnet(broadcast, s);
 110                                 subnet_del(n, s);
 111                         }
 112
 113                         for(enode = n->edge_tree->head; enode; enode = enext) {
 114                                 enext = enode->next;
 115                                 e = (edge_t *) enode->data;
 116                                 send_del_edge(broadcast, e);
 117                                 edge_del(e);
 118                         }
 119
 120                         node_del(n);
 121                 }
 122         }
 123 }
 124
 125 /*
 126   put all file descriptors in an fd_set array
 127   While we're at it, purge stuff that needs to be removed.
 128 */
 129 int build_fdset(fd_set * fs)
 130 {
 131         avl_node_t *node, *next;
 132         connection_t *c;
 133         int i, max = 0;
 134
 135         cp();
 136
 137         FD_ZERO(fs);
 138
 139         for(node = connection_tree->head; node; node = next) {
 140                 next = node->next;
 141                 c = (connection_t *) node->data;
 142
 143                 if(c->status.remove) {
 144                         connection_del(c);
 145                         if(!connection_tree->head)
 146                                 purge();
 147                 } else {
 148                         FD_SET(c->socket, fs);
 149                         if(c->socket > max)
 150                                 max = c->socket;
 151                 }
 152         }
 153
 154         for(i = 0; i < listen_sockets; i++) {
 155                 FD_SET(listen_socket[i].tcp, fs);
 156                 if(listen_socket[i].tcp > max)
 157                         max = listen_socket[i].tcp;
 158                 FD_SET(listen_socket[i].udp, fs);
 159                 if(listen_socket[i].udp > max)
 160                         max = listen_socket[i].udp;
 161         }
 162
 163         FD_SET(device_fd, fs);
 164         if(device_fd > max)
 165                 max = device_fd;
 166
 167         return max;
 168 }
 169
 170 /*
 171   Terminate a connection:
 172   - Close the socket
 173   - Remove associated edge and tell other connections about it if report = 1
 174   - Check if we need to retry making an outgoing connection
 175   - Deactivate the host
 176 */
 177 void terminate_connection(connection_t *c, int report)
 178 {
 179         cp();
 180
 181         if(c->status.remove)
 182                 return;
 183
 184         if(debug_lvl >= DEBUG_CONNECTIONS)
 185                 syslog(LOG_NOTICE, _("Closing connection with %s (%s)"),
 186                            c->name, c->hostname);
 187
 188         c->status.remove = 1;
 189         c->status.active = 0;
 190
 191         if(c->node)
 192                 c->node->connection = NULL;
 193
 194         if(c->socket)
 195                 close(c->socket);
 196
 197         if(c->edge) {
 198                 if(report)
 199                         send_del_edge(broadcast, c->edge);
 200
 201                 edge_del(c->edge);
 202
 203                 /* Run MST and SSSP algorithms */
 204
 205                 graph();
 206         }
 207
 208         /* Check if this was our outgoing connection */
 209
 210         if(c->outgoing) {
 211                 retry_outgoing(c->outgoing);
 212                 c->outgoing = NULL;
 213         }
 214 }
 215
 216 /*
 217   Check if the other end is active.
 218   If we have sent packets, but didn't receive any,
 219   then possibly the other end is dead. We send a
 220   PING request over the meta connection. If the other
 221   end does not reply in time, we consider them dead
 222   and close the connection.
 223 */
 224 void check_dead_connections(void)
 225 {
 226         avl_node_t *node, *next;
 227         connection_t *c;
 228
 229         cp();
 230
 231         for(node = connection_tree->head; node; node = next) {
 232                 next = node->next;
 233                 c = (connection_t *) node->data;
 234
 235                 if(c->last_ping_time + pingtimeout < now) {
 236                         if(c->status.active) {
 237                                 if(c->status.pinged) {
 238                                         if(debug_lvl >= DEBUG_PROTOCOL)
 239                                                 syslog(LOG_INFO, _("%s (%s) didn't respond to PING"),
 240                                                            c->name, c->hostname);
 241                                         c->status.timeout = 1;
 242                                         terminate_connection(c, 1);
 243                                 } else {
 244                                         send_ping(c);
 245                                 }
 246                         } else {
 247                                 if(c->status.remove) {
 248                                         syslog(LOG_WARNING, _("Old connection_t for %s (%s) status %04x still lingering, deleting..."),
 249                                                    c->name, c->hostname, c->status);
 250                                         connection_del(c);
 251                                         continue;
 252                                 }
 253                                 if(debug_lvl >= DEBUG_CONNECTIONS)
 254                                         syslog(LOG_WARNING, _("Timeout from %s (%s) during authentication"),
 255                                                    c->name, c->hostname);
 256                                 terminate_connection(c, 0);
 257                         }
 258                 }
 259         }
 260 }
 261
 262 /*
 263   check all connections to see if anything
 264   happened on their sockets
 265 */
 266 void check_network_activity(fd_set * f)
 267 {
 268         connection_t *c;
 269         avl_node_t *node;
 270         int result, i;
 271         int len = sizeof(result);
 272         vpn_packet_t packet;
 273
 274         cp();
 275
 276         if(FD_ISSET(device_fd, f)) {
 277                 if(!read_packet(&packet))
 278                         route_outgoing(&packet);
 279         }
 280
 281         for(node = connection_tree->head; node; node = node->next) {
 282                 c = (connection_t *) node->data;
 283
 284                 if(c->status.remove)
 285                         continue;
 286
 287                 if(FD_ISSET(c->socket, f)) {
 288                         if(c->status.connecting) {
 289                                 c->status.connecting = 0;
 290                                 getsockopt(c->socket, SOL_SOCKET, SO_ERROR, &result, &len);
 291
 292                                 if(!result)
 293                                         finish_connecting(c);
 294                                 else {
 295                                         if(debug_lvl >= DEBUG_CONNECTIONS)
 296                                                 syslog(LOG_DEBUG,
 297                                                            _("Error while connecting to %s (%s): %s"),
 298                                                            c->name, c->hostname, strerror(result));
 299                                         close(c->socket);
 300                                         do_outgoing_connection(c);
 301                                         continue;
 302                                 }
 303                         }
 304
 305                         if(receive_meta(c) < 0) {
 306                                 terminate_connection(c, c->status.active);
 307                                 continue;
 308                         }
 309                 }
 310         }
 311
 312         for(i = 0; i < listen_sockets; i++) {
 313                 if(FD_ISSET(listen_socket[i].udp, f))
 314                         handle_incoming_vpn_data(listen_socket[i].udp);
 315
 316                 if(FD_ISSET(listen_socket[i].tcp, f))
 317                         handle_new_meta_connection(listen_socket[i].tcp);
 318         }
 319 }
 320
 321 /*
 322   this is where it all happens...
 323 */
 324 void main_loop(void)
 325 {
 326         fd_set fset;
 327         struct timeval tv;
 328         int r, maxfd;
 329         time_t last_ping_check, last_config_check;
 330         event_t *event;
 331
 332         cp();
 333
 334         last_ping_check = now;
 335         last_config_check = now;
 336         srand(now);
 337
 338         for(;;) {
 339                 now = time(NULL);
 340
 341                 tv.tv_sec = 1 + (rand() & 7);   /* Approx. 5 seconds, randomized to prevent global synchronisation effects */
 342                 tv.tv_usec = 0;
 343
 344                 maxfd = build_fdset(&fset);
 345
 346                 r = select(maxfd + 1, &fset, NULL, NULL, &tv);
 347
 348                 if(r < 0) {
 349                         if(errno != EINTR && errno != EAGAIN) {
 350                                 syslog(LOG_ERR, _("Error while waiting for input: %s"),
 351                                            strerror(errno));
 352                                 cp_trace();
 353                                 dump_connections();
 354                                 return;
 355                         }
 356
 357                         continue;
 358                 }
 359
 360                 check_network_activity(&fset);
 361
 362                 if(do_purge) {
 363                         purge();
 364                         do_purge = 0;
 365                 }
 366
 367                 /* Let's check if everybody is still alive */
 368
 369                 if(last_ping_check + pingtimeout < now) {
 370                         check_dead_connections();
 371                         last_ping_check = now;
 372
 373                         if(routing_mode == RMODE_SWITCH)
 374                                 age_mac();
 375
 376                         age_past_requests();
 377
 378                         /* Should we regenerate our key? */
 379
 380                         if(keyexpires < now) {
 381                                 if(debug_lvl >= DEBUG_STATUS)
 382                                         syslog(LOG_INFO, _("Regenerating symmetric key"));
 383
 384                                 RAND_pseudo_bytes(myself->key, myself->keylength);
 385                                 EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key, myself->key + myself->cipher->key_len);
 386                                 send_key_changed(broadcast, myself);
 387                                 keyexpires = now + keylifetime;
 388                         }
 389                 }
 390
 391
 392                 while((event = get_expired_event())) {
 393                         event->handler(event->data);
 394                         free(event);
 395                 }
 396
 397                 if(sigalrm) {
 398                         syslog(LOG_INFO, _("Flushing event queue"));
 399
 400                         while(event_tree->head) {
 401                                 event = (event_t *) event_tree->head->data;
 402                                 event->handler(event->data);
 403                                 event_del(event);
 404                         }
 405                         sigalrm = 0;
 406                 }
 407
 408                 if(sighup) {
 409                         connection_t *c;
 410                         avl_node_t *node;
 411                         char *fname;
 412                         struct stat s;
 413
 414                         sighup = 0;
 415
 416                         /* Reread our own configuration file */
 417
 418                         exit_configuration(&config_tree);
 419                         init_configuration(&config_tree);
 420
 421                         if(read_server_config()) {
 422                                 syslog(LOG_ERR, _("Unable to reread configuration file, exitting."));
 423                                 exit(1);
 424                         }
 425
 426                         /* Close connections to hosts that have a changed or deleted host config file */
 427
 428                         for(node = connection_tree->head; node; node = node->next) {
 429                                 c = (connection_t *) node->data;
 430
 431                                 if(c->outgoing) {
 432                                         free(c->outgoing->name);
 433                                         freeaddrinfo(c->outgoing->ai);
 434                                         free(c->outgoing);
 435                                         c->outgoing = NULL;
 436                                 }
 437
 438                                 asprintf(&fname, "%s/hosts/%s", confbase, c->name);
 439                                 if(stat(fname, &s) || s.st_mtime > last_config_check)
 440                                         terminate_connection(c, c->status.active);
 441                                 free(fname);
 442                         }
 443
 444                         last_config_check = now;
 445
 446                         /* Try to make outgoing connections */
 447
 448                         try_outgoing_connections();
 449
 450                         continue;
 451                 }
 452         }
 453 }