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->status.reachable) {
  69                 logger(LOG_DEBUG, _("Trying to send MTU probe to unreachable node %s (%s)"), n->name, n->hostname);
  70                 return;
  71         }
  72
  73         if(n->mtuprobes >= 10 && !n->minmtu) {
  74                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  75                 return;
  76         }
  77
  78         for(i = 0; i < 3; i++) {
  79                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  80                         n->mtu = n->minmtu;
  81                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  82                         return;
  83                 }
  84
  85                 len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
  86                 if(len < 64)
  87                         len = 64;
  88
  89                 memset(packet.data, 0, 14);
  90                 randomize(packet.data + 14, len - 14);
  91                 packet.len = len;
  92                 packet.priority = 0;
  93
  94                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
  95
  96                 send_udppacket(n, &packet);
  97         }
  98
  99         event_add(&n->mtuevent, &(struct timeval){1, 0});
 100 }
 101
 102 void send_mtu_probe(node_t *n) {
 103         if(!timeout_initialized(&n->mtuevent))
 104                 timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
 105         send_mtu_probe_handler(0, 0, n);
 106 }
 107
 108 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 109         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 110
 111         if(!packet->data[0]) {
 112                 packet->data[0] = 1;
 113                 send_packet(n, packet);
 114         } else {
 115                 if(n->minmtu < len)
 116                         n->minmtu = len;
 117         }
 118 }
 119
 120 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 121         if(level == 10) {
 122                 lzo_uint lzolen = MAXSIZE;
 123                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 124                 return lzolen;
 125         } else if(level < 10) {
 126                 unsigned long destlen = MAXSIZE;
 127                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 128                         return destlen;
 129                 else
 130                         return -1;
 131         } else {
 132                 lzo_uint lzolen = MAXSIZE;
 133                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 134                 return lzolen;
 135         }
 136
 137         return -1;
 138 }
 139
 140 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 141         if(level > 9) {
 142                 lzo_uint lzolen = MAXSIZE;
 143                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 144                         return lzolen;
 145                 else
 146                         return -1;
 147         } else {
 148                 unsigned long destlen = MAXSIZE;
 149                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 150                         return destlen;
 151                 else
 152                         return -1;
 153         }
 154
 155         return -1;
 156 }
 157
 158 /* VPN packet I/O */
 159
 160 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 161         cp();
 162
 163         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 164                            packet->len, n->name, n->hostname);
 165
 166         route(n, packet);
 167 }
 168
 169 static bool try_mac(node_t *n, const vpn_packet_t *inpkt)
 170 {
 171         if(!digest_active(&n->indigest) || inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest))
 172                 return false;
 173
 174         return digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len);
 175 }
 176
 177 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 178 {
 179         vpn_packet_t pkt1, pkt2;
 180         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 181         int nextpkt = 0;
 182         vpn_packet_t *outpkt = pkt[0];
 183         size_t outlen;
 184         int i;
 185
 186         cp();
 187
 188         if(!cipher_active(&n->incipher)) {
 189                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got packet from %s (%s) but he hasn't got our key yet"),
 190                                         n->name, n->hostname);
 191                 return;
 192         }
 193
 194         /* Check packet length */
 195
 196         if(inpkt->len < sizeof inpkt->seqno + digest_length(&n->indigest)) {
 197                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 198                                         n->name, n->hostname);
 199                 return;
 200         }
 201
 202         /* Check the message authentication code */
 203
 204         if(digest_active(&n->indigest) && !digest_verify(&n->indigest, &inpkt->seqno, inpkt->len, (const char *)&inpkt->seqno + inpkt->len)) {
 205                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
 206                 return;
 207         }
 208
 209         /* Decrypt the packet */
 210
 211         if(cipher_active(&n->incipher)) {
 212                 outpkt = pkt[nextpkt++];
 213                 outlen = MAXSIZE;
 214
 215                 if(!cipher_decrypt(&n->incipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 216                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s)"), n->name, n->hostname);
 217                         return;
 218                 }
 219
 220                 outpkt->len = outlen;
 221                 inpkt = outpkt;
 222         }
 223
 224         /* Check the sequence number */
 225
 226         inpkt->len -= sizeof inpkt->seqno;
 227         inpkt->seqno = ntohl(inpkt->seqno);
 228
 229         if(inpkt->seqno != n->received_seqno + 1) {
 230                 if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
 231                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 232                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 233
 234                         memset(n->late, 0, sizeof n->late);
 235                 } else if (inpkt->seqno <= n->received_seqno) {
 236                         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))) {
 237                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 238                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 239                                 return;
 240                         }
 241                 } else {
 242                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 243                                 n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
 244                 }
 245         }
 246
 247         n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
 248
 249         if(inpkt->seqno > n->received_seqno)
 250                 n->received_seqno = inpkt->seqno;
 251
 252         if(n->received_seqno > MAX_SEQNO)
 253                 regenerate_key();
 254
 255         /* Decompress the packet */
 256
 257         length_t origlen = inpkt->len;
 258
 259         if(n->incompression) {
 260                 outpkt = pkt[nextpkt++];
 261
 262                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 263                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 264                                                  n->name, n->hostname);
 265                         return;
 266                 }
 267
 268                 inpkt = outpkt;
 269
 270                 origlen -= MTU/64 + 20;
 271         }
 272
 273         inpkt->priority = 0;
 274
 275         if(!inpkt->data[12] && !inpkt->data[13])
 276                 mtu_probe_h(n, inpkt, origlen);
 277         else
 278                 receive_packet(n, inpkt);
 279 }
 280
 281 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 282         vpn_packet_t outpkt;
 283
 284         cp();
 285
 286         outpkt.len = len;
 287         if(c->options & OPTION_TCPONLY)
 288                 outpkt.priority = 0;
 289         else
 290                 outpkt.priority = -1;
 291         memcpy(outpkt.data, buffer, len);
 292
 293         receive_packet(c->node, &outpkt);
 294 }
 295
 296 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 297         vpn_packet_t pkt1, pkt2;
 298         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 299         vpn_packet_t *inpkt = origpkt;
 300         int nextpkt = 0;
 301         vpn_packet_t *outpkt;
 302         int origlen;
 303         size_t outlen;
 304         static int priority = 0;
 305         int origpriority;
 306         int sock;
 307
 308         cp();
 309
 310         if(!n->status.reachable) {
 311                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Trying to send UDP packet to unreachable node %s (%s)"), n->name, n->hostname);
 312                 return;
 313         }
 314
 315         /* Make sure we have a valid key */
 316
 317         if(!n->status.validkey) {
 318                 ifdebug(TRAFFIC) logger(LOG_INFO,
 319                                    _("No valid key known yet for %s (%s), forwarding via TCP"),
 320                                    n->name, n->hostname);
 321
 322                 if(!n->status.waitingforkey)
 323                         send_req_key(n);
 324
 325                 n->status.waitingforkey = true;
 326
 327                 send_tcppacket(n->nexthop->connection, origpkt);
 328
 329                 return;
 330         }
 331
 332         if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 333                 ifdebug(TRAFFIC) logger(LOG_INFO,
 334                                 _("Packet for %s (%s) larger than minimum MTU, forwarding via TCP"),
 335                                 n->name, n->hostname);
 336
 337                 send_tcppacket(n->nexthop->connection, origpkt);
 338
 339                 return;
 340         }
 341
 342         origlen = inpkt->len;
 343         origpriority = inpkt->priority;
 344
 345         /* Compress the packet */
 346
 347         if(n->outcompression) {
 348                 outpkt = pkt[nextpkt++];
 349
 350                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 351                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 352                                    n->name, n->hostname);
 353                         return;
 354                 }
 355
 356                 inpkt = outpkt;
 357         }
 358
 359         /* Add sequence number */
 360
 361         inpkt->seqno = htonl(++(n->sent_seqno));
 362         inpkt->len += sizeof inpkt->seqno;
 363
 364         /* Encrypt the packet */
 365
 366         if(cipher_active(&n->outcipher)) {
 367                 outpkt = pkt[nextpkt++];
 368                 outlen = MAXSIZE;
 369
 370                 if(!cipher_encrypt(&n->outcipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 371                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s)"), n->name, n->hostname);
 372                         goto end;
 373                 }
 374
 375                 outpkt->len = outlen;
 376                 inpkt = outpkt;
 377         }
 378
 379         /* Add the message authentication code */
 380
 381         if(digest_active(&n->outdigest)) {
 382                 digest_create(&n->outdigest, &inpkt->seqno, inpkt->len, (char *)&inpkt->seqno + inpkt->len);
 383                 inpkt->len += digest_length(&n->outdigest);
 384         }
 385
 386         /* Determine which socket we have to use */
 387
 388         for(sock = 0; sock < listen_sockets; sock++)
 389                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 390                         break;
 391
 392         if(sock >= listen_sockets)
 393                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 394
 395         /* Send the packet */
 396
 397 #if defined(SOL_IP) && defined(IP_TOS)
 398         if(priorityinheritance && origpriority != priority
 399            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 400                 priority = origpriority;
 401                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 402                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority))     /* SO_PRIORITY doesn't seem to work */
 403                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 404         }
 405 #endif
 406
 407         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 408                 if(errno == EMSGSIZE) {
 409                         if(n->maxmtu >= origlen)
 410                                 n->maxmtu = origlen - 1;
 411                         if(n->mtu >= origlen)
 412                                 n->mtu = origlen - 1;
 413                 } else
 414                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 415         }
 416
 417 end:
 418         origpkt->len = origlen;
 419 }
 420
 421 /*
 422   send a packet to the given vpn ip.
 423 */
 424 void send_packet(const node_t *n, vpn_packet_t *packet) {
 425         node_t *via;
 426
 427         cp();
 428
 429         if(n == myself) {
 430                 if(overwrite_mac)
 431                          memcpy(packet->data, mymac.x, ETH_ALEN);
 432                 write_packet(packet);
 433                 return;
 434         }
 435
 436         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 437                            packet->len, n->name, n->hostname);
 438
 439         if(!n->status.reachable) {
 440                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 441                                    n->name, n->hostname);
 442                 return;
 443         }
 444
 445         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 446
 447         if(via != n)
 448                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending packet to %s via %s (%s)"),
 449                            n->name, via->name, n->via->hostname);
 450
 451         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 452                 if(!send_tcppacket(via->connection, packet))
 453                         terminate_connection(via->connection, true);
 454         } else
 455                 send_udppacket(via, packet);
 456 }
 457
 458 /* Broadcast a packet using the minimum spanning tree */
 459
 460 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 461         splay_node_t *node;
 462         connection_t *c;
 463
 464         cp();
 465
 466         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 467                            packet->len, from->name, from->hostname);
 468
 469         if(from != myself) {
 470                 send_packet(myself, packet);
 471
 472                 // In TunnelServer mode, do not forward broadcast packets.
 473                 // The MST might not be valid and create loops.
 474                 if(tunnelserver)
 475                         return;
 476         }
 477
 478         for(node = connection_tree->head; node; node = node->next) {
 479                 c = node->data;
 480
 481                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 482                         send_packet(c->node, packet);
 483         }
 484 }
 485
 486 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 487         splay_node_t *node;
 488         edge_t *e;
 489         node_t *n = NULL;
 490
 491         for(node = edge_weight_tree->head; node; node = node->next) {
 492                 e = node->data;
 493
 494                 if(sockaddrcmp_noport(from, &e->address))
 495                         continue;
 496
 497                 if(!n)
 498                         n = e->to;
 499
 500                 if(!try_mac(e->to, pkt))
 501                         continue;
 502
 503                 n = e->to;
 504                 break;
 505         }
 506
 507         return n;
 508 }
 509
 510 void handle_incoming_vpn_data(int sock, short events, void *data)
 511 {
 512         vpn_packet_t pkt;
 513         char *hostname;
 514         sockaddr_t from;
 515         socklen_t fromlen = sizeof from;
 516         node_t *n;
 517
 518         cp();
 519
 520         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 521
 522         if(pkt.len < 0) {
 523                 if(errno != EAGAIN && errno != EINTR)
 524                         logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 525                 return;
 526         }
 527
 528         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 529
 530         n = lookup_node_udp(&from);
 531
 532         if(!n) {
 533                 n = try_harder(&from, &pkt);
 534                 if(n)
 535                         update_node_udp(n, &from);
 536                 else ifdebug(PROTOCOL) {
 537                         hostname = sockaddr2hostname(&from);
 538                         logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
 539                         free(hostname);
 540                         return;
 541                 }
 542                 else
 543                         return;
 544         }
 545
 546         receive_udppacket(n, &pkt);
 547 }
 548
 549 void handle_device_data(int sock, short events, void *data) {
 550         vpn_packet_t packet;
 551
 552         if(read_packet(&packet))
 553                 route(myself, &packet);
 554 }