tinc-vpn.org Git - tinc/blob - src/net_packet.c

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2009 Guus Sliepen <guus@tinc-vpn.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     $Id$
  21 */
  22
  23 #include "system.h"
  24
  25 #include <zlib.h>
  26 #include LZO1X_H
  27
  28 #include "splay_tree.h"
  29 #include "cipher.h"
  30 #include "conf.h"
  31 #include "connection.h"
  32 #include "crypto.h"
  33 #include "digest.h"
  34 #include "device.h"
  35 #include "ethernet.h"
  36 #include "graph.h"
  37 #include "list.h"
  38 #include "logger.h"
  39 #include "net.h"
  40 #include "netutl.h"
  41 #include "protocol.h"
  42 #include "process.h"
  43 #include "route.h"
  44 #include "utils.h"
  45 #include "xalloc.h"
  46
  47 #ifdef WSAEMSGSIZE
  48 #define EMSGSIZE WSAEMSGSIZE
  49 #endif
  50
  51 int keylifetime = 0;
  52 int keyexpires = 0;
  53 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  54
  55 static void send_udppacket(node_t *, vpn_packet_t *);
  56
  57 #define MAX_SEQNO 1073741824
  58
  59 static void send_mtu_probe_handler(int fd, short events, void *data) {
  60         node_t *n = data;
  61         vpn_packet_t packet;
  62         int len, i;
  63
  64         cp();
  65
  66         n->mtuprobes++;
  67
  68         if(n->mtuprobes >= 10 && !n->minmtu) {
  69                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  70                 return;
  71         }
  72
  73         for(i = 0; i < 3; i++) {
  74                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  75                         n->mtu = n->minmtu;
  76                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  77                         return;
  78                 }
  79
  80                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
  81                 if(len < 64)
  82                         len = 64;
  83
  84                 memset(packet.data, 0, 14);
  85                 randomize(packet.data + 14, len - 14);
  86                 packet.len = len;
  87                 packet.priority = 0;
  88
  89                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
  90
  91                 send_udppacket(n, &packet);
  92         }
  93
  94         event_add(&n->mtuevent, &(struct timeval){1, 0});
  95 }
  96
  97 void send_mtu_probe(node_t *n) {
  98         if(!timeout_initialized(&n->mtuevent))
  99                 timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
 100         send_mtu_probe_handler(0, 0, n);
 101 }
 102
 103 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 104         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 105
 106         if(!packet->data[0]) {
 107                 packet->data[0] = 1;
 108                 send_packet(n, packet);
 109         } else {
 110                 if(n->minmtu < len)
 111                         n->minmtu = len;
 112         }
 113 }
 114
 115 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 116         if(level == 10) {
 117                 lzo_uint lzolen = MAXSIZE;
 118                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 119                 return lzolen;
 120         } else if(level < 10) {
 121                 unsigned long destlen = MAXSIZE;
 122                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 123                         return destlen;
 124                 else
 125                         return -1;
 126         } else {
 127                 lzo_uint lzolen = MAXSIZE;
 128                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 129                 return lzolen;
 130         }
 131
 132         return -1;
 133 }
 134
 135 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 136         if(level > 9) {
 137                 lzo_uint lzolen = MAXSIZE;
 138                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 139                         return lzolen;
 140                 else
 141                         return -1;
 142         } else {
 143                 unsigned long destlen = MAXSIZE;
 144                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 145                         return destlen;
 146                 else
 147                         return -1;
 148         }
 149
 150         return -1;
 151 }
 152
 153 /* VPN packet I/O */
 154
 155 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 156         cp();
 157
 158         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 159                            packet->len, n->name, n->hostname);
 160
 161         route(n, packet);
 162 }
 163
 164 static bool try_mac(node_t *n, const vpn_packet_t *inpkt)
 165 {
 166         if(!digest_active(&n->indigest) || !n->inmaclength || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 167                 return false;
 168
 169         return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len);
 170 }
 171
 172 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 173 {
 174         vpn_packet_t pkt1, pkt2;
 175         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 176         int nextpkt = 0;
 177         vpn_packet_t *outpkt = pkt[0];
 178         size_t outlen;
 179         int i;
 180
 181         cp();
 182
 183         if(!cipher_active(&n->incipher)) {
 184                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got packet from %s (%s) but he hasn't got our key yet"),
 185                                         n->name, n->hostname);
 186                 return;
 187         }
 188
 189         /* Check packet length */
 190
 191         if(inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) {
 192                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 193                                         n->name, n->hostname);
 194                 return;
 195         }
 196
 197         /* Check the message authentication code */
 198
 199         if(digest_active(&n->indigest) && !digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len)) {
 200                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
 201                 return;
 202         }
 203
 204         /* Decrypt the packet */
 205
 206         if(cipher_active(&n->incipher)) {
 207                 outpkt = pkt[nextpkt++];
 208                 outlen = MAXSIZE;
 209
 210                 if(!cipher_decrypt(&n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 211                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s)"), n->name, n->hostname);
 212                         return;
 213                 }
 214
 215                 outpkt->len = outlen;
 216                 inpkt = outpkt;
 217         }
 218
 219         /* Check the sequence number */
 220
 221         inpkt->len -= sizeof inpkt->seqno;
 222         inpkt->seqno = ntohl(inpkt->seqno);
 223
 224         if(inpkt->seqno != n->received_seqno + 1) {
 225                 if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
 226                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 227                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 228
 229                         memset(n->late, 0, sizeof n->late);
 230                 } else if (inpkt->seqno <= n->received_seqno) {
 231                         if((n->received_seqno >= sizeof n->late * 8 && inpkt->seqno <= n->received_seqno - sizeof n->late * 8) || !(n->late[(inpkt->seqno / 8) % sizeof n->late] & (1 << inpkt->seqno % 8))) {
 232                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 233                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 234                                 return;
 235                         }
 236                 } else {
 237                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 238                                 n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
 239                 }
 240         }
 241
 242         n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
 243
 244         if(inpkt->seqno > n->received_seqno)
 245                 n->received_seqno = inpkt->seqno;
 246
 247         if(n->received_seqno > MAX_SEQNO)
 248                 regenerate_key();
 249
 250         /* Decompress the packet */
 251
 252         length_t origlen = inpkt->len;
 253
 254         if(n->incompression) {
 255                 outpkt = pkt[nextpkt++];
 256
 257                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 258                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 259                                                  n->name, n->hostname);
 260                         return;
 261                 }
 262
 263                 inpkt = outpkt;
 264
 265                 origlen -= MTU/64 + 20;
 266         }
 267
 268         inpkt->priority = 0;
 269
 270         if(!inpkt->data[12] && !inpkt->data[13])
 271                 mtu_probe_h(n, inpkt, origlen);
 272         else
 273                 receive_packet(n, inpkt);
 274 }
 275
 276 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 277         vpn_packet_t outpkt;
 278
 279         cp();
 280
 281         outpkt.len = len;
 282         if(c->options & OPTION_TCPONLY)
 283                 outpkt.priority = 0;
 284         else
 285                 outpkt.priority = -1;
 286         memcpy(outpkt.data, buffer, len);
 287
 288         receive_packet(c->node, &outpkt);
 289 }
 290
 291 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 292         vpn_packet_t pkt1, pkt2;
 293         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 294         vpn_packet_t *inpkt = origpkt;
 295         int nextpkt = 0;
 296         vpn_packet_t *outpkt;
 297         int origlen;
 298         size_t outlen;
 299         static int priority = 0;
 300         int origpriority;
 301         int sock;
 302
 303         cp();
 304
 305         /* Make sure we have a valid key */
 306
 307         if(!n->status.validkey) {
 308                 ifdebug(TRAFFIC) logger(LOG_INFO,
 309                                    _("No valid key known yet for %s (%s), forwarding via TCP"),
 310                                    n->name, n->hostname);
 311
 312                 if(!n->status.waitingforkey)
 313                         send_req_key(n);
 314
 315                 n->status.waitingforkey = true;
 316
 317                 send_tcppacket(n->nexthop->connection, origpkt);
 318
 319                 return;
 320         }
 321
 322         if(n->options & OPTION_PMTU_DISCOVERY && !n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 323                 ifdebug(TRAFFIC) logger(LOG_INFO,
 324                                 _("No minimum MTU established yet for %s (%s), forwarding via TCP"),
 325                                 n->name, n->hostname);
 326
 327                 send_tcppacket(n->nexthop->connection, origpkt);
 328
 329                 return;
 330         }
 331
 332         origlen = inpkt->len;
 333         origpriority = inpkt->priority;
 334
 335         /* Compress the packet */
 336
 337         if(n->outcompression) {
 338                 outpkt = pkt[nextpkt++];
 339
 340                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 341                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 342                                    n->name, n->hostname);
 343                         return;
 344                 }
 345
 346                 inpkt = outpkt;
 347         }
 348
 349         /* Add sequence number */
 350
 351         inpkt->seqno = htonl(++(n->sent_seqno));
 352         inpkt->len += sizeof inpkt->seqno;
 353
 354         /* Encrypt the packet */
 355
 356         if(cipher_active(&n->outcipher)) {
 357                 outpkt = pkt[nextpkt++];
 358                 outlen = MAXSIZE;
 359
 360                 if(!cipher_encrypt(&n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 361                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s)"), n->name, n->hostname);
 362                         goto end;
 363                 }
 364
 365                 outpkt->len = outlen;
 366                 inpkt = outpkt;
 367         }
 368
 369         /* Add the message authentication code */
 370
 371         if(digest_active(&n->outdigest)) {
 372                 digest_create(&n->outdigest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len);
 373                 inpkt->len += digest_length(&n->outdigest);
 374         }
 375
 376         /* Determine which socket we have to use */
 377
 378         for(sock = 0; sock < listen_sockets; sock++)
 379                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 380                         break;
 381
 382         if(sock >= listen_sockets)
 383                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 384
 385         /* Send the packet */
 386
 387 #if defined(SOL_IP) && defined(IP_TOS)
 388         if(priorityinheritance && origpriority != priority
 389            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 390                 priority = origpriority;
 391                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 392                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority))     /* SO_PRIORITY doesn't seem to work */
 393                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 394         }
 395 #endif
 396
 397         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 398                 if(errno == EMSGSIZE) {
 399                         if(n->maxmtu >= origlen)
 400                                 n->maxmtu = origlen - 1;
 401                         if(n->mtu >= origlen)
 402                                 n->mtu = origlen - 1;
 403                 } else
 404                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 405         }
 406
 407 end:
 408         origpkt->len = origlen;
 409 }
 410
 411 /*
 412   send a packet to the given vpn ip.
 413 */
 414 void send_packet(const node_t *n, vpn_packet_t *packet) {
 415         node_t *via;
 416
 417         cp();
 418
 419         if(n == myself) {
 420                 if(overwrite_mac)
 421                          memcpy(packet->data, mymac.x, ETH_ALEN);
 422                 write_packet(packet);
 423                 return;
 424         }
 425
 426         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 427                            packet->len, n->name, n->hostname);
 428
 429         if(!n->status.reachable) {
 430                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 431                                    n->name, n->hostname);
 432                 return;
 433         }
 434
 435         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 436
 437         if(via != n)
 438                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending packet to %s via %s (%s)"),
 439                            n->name, via->name, n->via->hostname);
 440
 441         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 442                 if(!send_tcppacket(via->connection, packet))
 443                         terminate_connection(via->connection, true);
 444         } else
 445                 send_udppacket(via, packet);
 446 }
 447
 448 /* Broadcast a packet using the minimum spanning tree */
 449
 450 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 451         splay_node_t *node;
 452         connection_t *c;
 453
 454         cp();
 455
 456         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 457                            packet->len, from->name, from->hostname);
 458
 459         if(from != myself) {
 460                 send_packet(myself, packet);
 461
 462                 // In TunnelServer mode, do not forward broadcast packets.
 463                 // The MST might not be valid and create loops.
 464                 if(tunnelserver)
 465                         return;
 466         }
 467
 468         for(node = connection_tree->head; node; node = node->next) {
 469                 c = node->data;
 470
 471                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 472                         send_packet(c->node, packet);
 473         }
 474 }
 475
 476 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 477         splay_node_t *node;
 478         edge_t *e;
 479         node_t *n = NULL;
 480
 481         for(node = edge_weight_tree->head; node; node = node->next) {
 482                 e = node->data;
 483
 484                 if(sockaddrcmp_noport(from, &e->address))
 485                         continue;
 486
 487                 if(!n)
 488                         n = e->to;
 489
 490                 if(!try_mac(e->to, pkt))
 491                         continue;
 492
 493                 n = e->to;
 494                 break;
 495         }
 496
 497         return n;
 498 }
 499
 500 void handle_incoming_vpn_data(int sock, short events, void *data)
 501 {
 502         vpn_packet_t pkt;
 503         char *hostname;
 504         sockaddr_t from;
 505         socklen_t fromlen = sizeof from;
 506         node_t *n;
 507
 508         cp();
 509
 510         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 511
 512         if(pkt.len < 0) {
 513                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 514                 return;
 515         }
 516
 517         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 518
 519         n = lookup_node_udp(&from);
 520
 521         if(!n) {
 522                 n = try_harder(&from, &pkt);
 523                 if(n)
 524                         update_node_udp(n, &from);
 525                 else ifdebug(PROTOCOL) {
 526                         hostname = sockaddr2hostname(&from);
 527                         logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
 528                         free(hostname);
 529                         return;
 530                 }
 531                 else
 532                         return;
 533         }
 534
 535         receive_udppacket(n, &pkt);
 536 }
 537
 538 void handle_device_data(int sock, short events, void *data) {
 539         vpn_packet_t packet;
 540
 541         if(read_packet(&packet))
 542                 route(myself, &packet);
 543 }