www.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 <openssl/rand.h>
  26 #include <openssl/err.h>
  27 #include <openssl/evp.h>
  28 #include <openssl/pem.h>
  29 #include <openssl/hmac.h>
  30
  31 #include <zlib.h>
  32 #include LZO1X_H
  33
  34 #include "avl_tree.h"
  35 #include "conf.h"
  36 #include "connection.h"
  37 #include "device.h"
  38 #include "ethernet.h"
  39 #include "event.h"
  40 #include "graph.h"
  41 #include "list.h"
  42 #include "logger.h"
  43 #include "net.h"
  44 #include "netutl.h"
  45 #include "protocol.h"
  46 #include "process.h"
  47 #include "route.h"
  48 #include "utils.h"
  49 #include "xalloc.h"
  50
  51 #ifdef WSAEMSGSIZE
  52 #define EMSGSIZE WSAEMSGSIZE
  53 #endif
  54
  55 int keylifetime = 0;
  56 int keyexpires = 0;
  57 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  58
  59 static void send_udppacket(node_t *, vpn_packet_t *);
  60
  61 #define MAX_SEQNO 1073741824
  62
  63 void send_mtu_probe(node_t *n)
  64 {
  65         vpn_packet_t packet;
  66         int len, i;
  67
  68         cp();
  69
  70         n->mtuprobes++;
  71         n->mtuevent = NULL;
  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 + random() % (n->maxmtu - n->minmtu);
  86                 if(len < 64)
  87                         len = 64;
  88
  89                 memset(packet.data, 0, 14);
  90                 RAND_pseudo_bytes(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         n->mtuevent = new_event();
 100         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 101         n->mtuevent->data = n;
 102         n->mtuevent->time = now + 1;
 103         event_add(n->mtuevent);
 104 }
 105
 106 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 107         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 108
 109         if(!packet->data[0]) {
 110                 packet->data[0] = 1;
 111                 send_packet(n, packet);
 112         } else {
 113                 if(n->minmtu < packet->len)
 114                         n->minmtu = packet->len;
 115         }
 116 }
 117
 118 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 119 {
 120         if(level == 10) {
 121                 lzo_uint lzolen = MAXSIZE;
 122                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 123                 return lzolen;
 124         } else if(level < 10) {
 125                 unsigned long destlen = MAXSIZE;
 126                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 127                         return destlen;
 128                 else
 129                         return -1;
 130         } else {
 131                 lzo_uint lzolen = MAXSIZE;
 132                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 133                 return lzolen;
 134         }
 135
 136         return -1;
 137 }
 138
 139 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 140 {
 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 {
 162         cp();
 163
 164         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 165                            packet->len, n->name, n->hostname);
 166
 167         route(n, packet);
 168 }
 169
 170 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt)
 171 {
 172         unsigned char hmac[EVP_MAX_MD_SIZE];
 173
 174         if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 175                 return false;
 176
 177         HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
 178
 179         return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
 180 }
 181
 182 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 183 {
 184         vpn_packet_t pkt1, pkt2;
 185         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 186         int nextpkt = 0;
 187         vpn_packet_t *outpkt = pkt[0];
 188         int outlen, outpad;
 189         unsigned char hmac[EVP_MAX_MD_SIZE];
 190         int i;
 191
 192         cp();
 193
 194         if(!n->inkey) {
 195                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got packet from %s (%s) but he hasn't got our key yet"),
 196                                         n->name, n->hostname);
 197                 return;
 198         }
 199
 200         /* Check packet length */
 201
 202         if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
 203                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 204                                         n->name, n->hostname);
 205                 return;
 206         }
 207
 208         /* Check the message authentication code */
 209
 210         if(n->indigest && n->inmaclength) {
 211                 inpkt->len -= n->inmaclength;
 212                 HMAC(n->indigest, n->inkey, n->inkeylength,
 213                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 214
 215                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
 216                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 217                                            n->name, n->hostname);
 218                         return;
 219                 }
 220         }
 221
 222         /* Decrypt the packet */
 223
 224         if(n->incipher) {
 225                 outpkt = pkt[nextpkt++];
 226
 227                 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
 228                                 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
 229                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 230                                 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 231                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 232                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 233                         return;
 234                 }
 235
 236                 outpkt->len = outlen + outpad;
 237                 inpkt = outpkt;
 238         }
 239
 240         /* Check the sequence number */
 241
 242         inpkt->len -= sizeof(inpkt->seqno);
 243         inpkt->seqno = ntohl(inpkt->seqno);
 244
 245         if(inpkt->seqno != n->received_seqno + 1) {
 246                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 247                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 248                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 249
 250                         memset(n->late, 0, sizeof(n->late));
 251                 } else if (inpkt->seqno <= n->received_seqno) {
 252                         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))) {
 253                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 254                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 255                                 return;
 256                         }
 257                 } else {
 258                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 259                                 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
 260                 }
 261         }
 262
 263         n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
 264
 265         if(inpkt->seqno > n->received_seqno)
 266                 n->received_seqno = inpkt->seqno;
 267
 268         if(n->received_seqno > MAX_SEQNO)
 269                 keyexpires = 0;
 270
 271         /* Decompress the packet */
 272
 273         if(n->incompression) {
 274                 outpkt = pkt[nextpkt++];
 275
 276                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 277                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 278                                                  n->name, n->hostname);
 279                         return;
 280                 }
 281
 282                 inpkt = outpkt;
 283         }
 284
 285         inpkt->priority = 0;
 286
 287         if(n->connection)
 288                 n->connection->last_ping_time = now;
 289
 290         if(!inpkt->data[12] && !inpkt->data[13])
 291                 mtu_probe_h(n, inpkt);
 292         else
 293                 receive_packet(n, inpkt);
 294 }
 295
 296 void receive_tcppacket(connection_t *c, char *buffer, int len)
 297 {
 298         vpn_packet_t outpkt;
 299
 300         cp();
 301
 302         outpkt.len = len;
 303         if(c->options & OPTION_TCPONLY)
 304                 outpkt.priority = 0;
 305         else
 306                 outpkt.priority = -1;
 307         memcpy(outpkt.data, buffer, len);
 308
 309         receive_packet(c->node, &outpkt);
 310 }
 311
 312 static void send_udppacket(node_t *n, vpn_packet_t *origpkt)
 313 {
 314         vpn_packet_t pkt1, pkt2;
 315         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 316         vpn_packet_t *inpkt = origpkt;
 317         int nextpkt = 0;
 318         vpn_packet_t *outpkt;
 319         int origlen;
 320         int outlen, outpad;
 321         static int priority = 0;
 322         int origpriority;
 323         int sock;
 324
 325         cp();
 326
 327         /* Make sure we have a valid key */
 328
 329         if(!n->status.validkey) {
 330                 ifdebug(TRAFFIC) logger(LOG_INFO,
 331                                    _("No valid key known yet for %s (%s), forwarding via TCP"),
 332                                    n->name, n->hostname);
 333
 334                 if(!n->status.waitingforkey)
 335                         send_req_key(n);
 336
 337                 n->status.waitingforkey = true;
 338
 339                 send_tcppacket(n->nexthop->connection, origpkt);
 340
 341                 return;
 342         }
 343
 344         if(n->options & OPTION_PMTU_DISCOVERY && !n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 345                 ifdebug(TRAFFIC) logger(LOG_INFO,
 346                                 _("No minimum MTU established yet for %s (%s), forwarding via TCP"),
 347                                 n->name, n->hostname);
 348
 349                 send_tcppacket(n->nexthop->connection, origpkt);
 350
 351                 return;
 352         }
 353
 354         origlen = inpkt->len;
 355         origpriority = inpkt->priority;
 356
 357         /* Compress the packet */
 358
 359         if(n->outcompression) {
 360                 outpkt = pkt[nextpkt++];
 361
 362                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 363                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 364                                    n->name, n->hostname);
 365                         return;
 366                 }
 367
 368                 inpkt = outpkt;
 369         }
 370
 371         /* Add sequence number */
 372
 373         inpkt->seqno = htonl(++(n->sent_seqno));
 374         inpkt->len += sizeof(inpkt->seqno);
 375
 376         /* Encrypt the packet */
 377
 378         if(n->outcipher) {
 379                 outpkt = pkt[nextpkt++];
 380
 381                 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
 382                                 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
 383                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 384                                 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 385                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 386                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 387                         goto end;
 388                 }
 389
 390                 outpkt->len = outlen + outpad;
 391                 inpkt = outpkt;
 392         }
 393
 394         /* Add the message authentication code */
 395
 396         if(n->outdigest && n->outmaclength) {
 397                 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
 398                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 399                 inpkt->len += n->outmaclength;
 400         }
 401
 402         /* Determine which socket we have to use */
 403
 404         for(sock = 0; sock < listen_sockets; sock++)
 405                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 406                         break;
 407
 408         if(sock >= listen_sockets)
 409                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 410
 411         /* Send the packet */
 412
 413 #if defined(SOL_IP) && defined(IP_TOS)
 414         if(priorityinheritance && origpriority != priority
 415            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 416                 priority = origpriority;
 417                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 418                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 419                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 420         }
 421 #endif
 422
 423         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 424                 if(errno == EMSGSIZE) {
 425                         if(n->maxmtu >= origlen)
 426                                 n->maxmtu = origlen - 1;
 427                         if(n->mtu >= origlen)
 428                                 n->mtu = origlen - 1;
 429                 } else
 430                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 431         }
 432
 433 end:
 434         origpkt->len = origlen;
 435 }
 436
 437 /*
 438   send a packet to the given vpn ip.
 439 */
 440 void send_packet(const node_t *n, vpn_packet_t *packet)
 441 {
 442         node_t *via;
 443
 444         cp();
 445
 446         if(n == myself) {
 447                 if(overwrite_mac)
 448                          memcpy(packet->data, mymac.x, ETH_ALEN);
 449                 write_packet(packet);
 450                 return;
 451         }
 452
 453         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 454                            packet->len, n->name, n->hostname);
 455
 456         if(!n->status.reachable) {
 457                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 458                                    n->name, n->hostname);
 459                 return;
 460         }
 461
 462         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 463
 464         if(via != n)
 465                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending packet to %s via %s (%s)"),
 466                            n->name, via->name, n->via->hostname);
 467
 468         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 469                 if(!send_tcppacket(via->connection, packet))
 470                         terminate_connection(via->connection, true);
 471         } else
 472                 send_udppacket(via, packet);
 473 }
 474
 475 /* Broadcast a packet using the minimum spanning tree */
 476
 477 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 478 {
 479         avl_node_t *node;
 480         connection_t *c;
 481
 482         cp();
 483
 484         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 485                            packet->len, from->name, from->hostname);
 486
 487         if(from != myself)
 488                 send_packet(myself, packet);
 489
 490         for(node = connection_tree->head; node; node = node->next) {
 491                 c = node->data;
 492
 493                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 494                         send_packet(c->node, packet);
 495         }
 496 }
 497
 498 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 499         avl_node_t *node;
 500         edge_t *e;
 501         node_t *n = NULL;
 502
 503         for(node = edge_weight_tree->head; node; node = node->next) {
 504                 e = node->data;
 505
 506                 if(sockaddrcmp_noport(from, &e->address))
 507                         continue;
 508
 509                 if(!n)
 510                         n = e->to;
 511
 512                 if(!try_mac(e->to, pkt))
 513                         continue;
 514
 515                 n = e->to;
 516                 break;
 517         }
 518
 519         return n;
 520 }
 521
 522 void handle_incoming_vpn_data(int sock)
 523 {
 524         vpn_packet_t pkt;
 525         char *hostname;
 526         sockaddr_t from;
 527         socklen_t fromlen = sizeof(from);
 528         node_t *n;
 529
 530         cp();
 531
 532         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 533
 534         if(pkt.len < 0) {
 535                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 536                 return;
 537         }
 538
 539         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 540
 541         n = lookup_node_udp(&from);
 542
 543         if(!n) {
 544                 n = try_harder(&from, &pkt);
 545                 if(n)
 546                         update_node_udp(n, &from);
 547                 else ifdebug(PROTOCOL) {
 548                         hostname = sockaddr2hostname(&from);
 549                         logger(LOG_WARNING, _("Received UDP packet from unknown source %s"), hostname);
 550                         free(hostname);
 551                         return;
 552                 }
 553                 else
 554                         return;
 555         }
 556
 557         receive_udppacket(n, &pkt);
 558 }