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

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2003 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_packet.c,v 1.1.2.49 2003/12/27 16:32:52 guus Exp $
  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 EVP_CIPHER_CTX packet_ctx;
  58 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  59
  60 static void send_udppacket(node_t *, vpn_packet_t *);
  61
  62 #define MAX_SEQNO 1073741824
  63
  64 void send_mtu_probe(node_t *n)
  65 {
  66         vpn_packet_t packet;
  67         int len, i;
  68
  69         cp();
  70
  71         n->mtuprobes++;
  72         n->mtuevent = NULL;
  73
  74         if(n->mtuprobes >= 10 && !n->minmtu) {
  75                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  76                 return;
  77         }
  78
  79         for(i = 0; i < 3; i++) {
  80                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  81                         n->mtu = n->minmtu;
  82                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  83                         return;
  84                 }
  85
  86                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
  87                 if(len < 64)
  88                         len = 64;
  89
  90                 memset(packet.data, 0, 14);
  91                 RAND_pseudo_bytes(packet.data + 14, len - 14);
  92                 packet.len = len;
  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 = xmalloc(sizeof(*n->mtuevent));
 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 void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 171 {
 172         vpn_packet_t pkt1, pkt2;
 173         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 174         int nextpkt = 0;
 175         vpn_packet_t *outpkt = pkt[0];
 176         int outlen, outpad;
 177         char hmac[EVP_MAX_MD_SIZE];
 178         int i;
 179
 180         cp();
 181
 182         /* Check packet length */
 183
 184         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 185                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 186                                         n->name, n->hostname);
 187                 return;
 188         }
 189
 190         /* Check the message authentication code */
 191
 192         if(myself->digest && myself->maclength) {
 193                 inpkt->len -= myself->maclength;
 194                 HMAC(myself->digest, myself->key, myself->keylength,
 195                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 196
 197                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 198                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 199                                            n->name, n->hostname);
 200                         return;
 201                 }
 202         }
 203
 204         /* Decrypt the packet */
 205
 206         if(myself->cipher) {
 207                 outpkt = pkt[nextpkt++];
 208
 209                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
 210                                 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 211                                         (char *) &inpkt->seqno, inpkt->len)
 212                                 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 213                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 214                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 215                         return;
 216                 }
 217
 218                 outpkt->len = outlen + outpad;
 219                 inpkt = outpkt;
 220         }
 221
 222         /* Check the sequence number */
 223
 224         inpkt->len -= sizeof(inpkt->seqno);
 225         inpkt->seqno = ntohl(inpkt->seqno);
 226
 227         if(inpkt->seqno != n->received_seqno + 1) {
 228                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 229                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 230                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 231
 232                         memset(n->late, 0, sizeof(n->late));
 233                 } else if (inpkt->seqno <= n->received_seqno) {
 234                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 235                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 236                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 237                         } else
 238                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 239                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 240                 }
 241         }
 242
 243         n->received_seqno = inpkt->seqno;
 244         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 245
 246         if(n->received_seqno > MAX_SEQNO)
 247                 keyexpires = 0;
 248
 249         /* Decompress the packet */
 250
 251         if(myself->compression) {
 252                 outpkt = pkt[nextpkt++];
 253
 254                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 255                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 256                                                  n->name, n->hostname);
 257                         return;
 258                 }
 259
 260                 inpkt = outpkt;
 261         }
 262
 263         if(n->connection)
 264                 n->connection->last_ping_time = now;
 265
 266         if(!inpkt->data[12] && !inpkt->data[13])
 267                 mtu_probe_h(n, inpkt);
 268         else
 269                 receive_packet(n, inpkt);
 270 }
 271
 272 void receive_tcppacket(connection_t *c, char *buffer, int len)
 273 {
 274         vpn_packet_t outpkt;
 275
 276         cp();
 277
 278         outpkt.len = len;
 279         memcpy(outpkt.data, buffer, len);
 280
 281         receive_packet(c->node, &outpkt);
 282 }
 283
 284 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 285 {
 286         vpn_packet_t pkt1, pkt2;
 287         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 288         int nextpkt = 0;
 289         vpn_packet_t *outpkt;
 290         int origlen;
 291         int outlen, outpad;
 292         vpn_packet_t *copy;
 293         static int priority = 0;
 294         int origpriority;
 295         int sock;
 296
 297         cp();
 298
 299         /* Make sure we have a valid key */
 300
 301         if(!n->status.validkey) {
 302                 ifdebug(TRAFFIC) logger(LOG_INFO,
 303                                    _("No valid key known yet for %s (%s), queueing packet"),
 304                                    n->name, n->hostname);
 305
 306                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 307
 308                 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
 309
 310                 list_insert_tail(n->queue, copy);
 311
 312                 if(n->queue->count > MAXQUEUELENGTH)
 313                         list_delete_head(n->queue);
 314
 315                 if(!n->status.waitingforkey)
 316                         send_req_key(n->nexthop->connection, myself, n);
 317
 318                 n->status.waitingforkey = true;
 319
 320                 return;
 321         }
 322
 323         origlen = inpkt->len;
 324         origpriority = inpkt->priority;
 325
 326         /* Compress the packet */
 327
 328         if(n->compression) {
 329                 outpkt = pkt[nextpkt++];
 330
 331                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 332                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 333                                    n->name, n->hostname);
 334                         return;
 335                 }
 336
 337                 inpkt = outpkt;
 338         }
 339
 340         /* Add sequence number */
 341
 342         inpkt->seqno = htonl(++(n->sent_seqno));
 343         inpkt->len += sizeof(inpkt->seqno);
 344
 345         /* Encrypt the packet */
 346
 347         if(n->cipher) {
 348                 outpkt = pkt[nextpkt++];
 349
 350                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
 351                                 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 352                                         (char *) &inpkt->seqno, inpkt->len)
 353                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 354                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 355                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 356                         goto end;
 357                 }
 358
 359                 outpkt->len = outlen + outpad;
 360                 inpkt = outpkt;
 361         }
 362
 363         /* Add the message authentication code */
 364
 365         if(n->digest && n->maclength) {
 366                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 367                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 368                 inpkt->len += n->maclength;
 369         }
 370
 371         /* Determine which socket we have to use */
 372
 373         for(sock = 0; sock < listen_sockets; sock++)
 374                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 375                         break;
 376
 377         if(sock >= listen_sockets)
 378                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 379
 380         /* Send the packet */
 381
 382 #if defined(SOL_IP) && defined(IP_TOS)
 383         if(priorityinheritance && origpriority != priority
 384            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 385                 priority = origpriority;
 386                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 387                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 388                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 389         }
 390 #endif
 391
 392         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 393                 if(errno == EMSGSIZE) {
 394                         if(n->maxmtu >= origlen)
 395                                 n->maxmtu = origlen - 1;
 396                         if(n->mtu >= origlen)
 397                                 n->mtu = origlen - 1;
 398                 } else
 399                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 400         }
 401
 402 end:
 403         inpkt->len = origlen;
 404 }
 405
 406 /*
 407   send a packet to the given vpn ip.
 408 */
 409 void send_packet(const node_t *n, vpn_packet_t *packet)
 410 {
 411         node_t *via;
 412
 413         cp();
 414
 415         if(n == myself) {
 416                 if(overwrite_mac)
 417                          memcpy(packet->data, mymac.x, ETH_ALEN);
 418                 write_packet(packet);
 419                 return;
 420         }
 421
 422         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 423                            packet->len, n->name, n->hostname);
 424
 425         if(!n->status.reachable) {
 426                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 427                                    n->name, n->hostname);
 428                 return;
 429         }
 430
 431         via = (n->via == myself) ? n->nexthop : n->via;
 432
 433         if(via != n)
 434                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 435                            n->name, via->name, n->via->hostname);
 436
 437         if((myself->options | via->options) & OPTION_TCPONLY) {
 438                 if(!send_tcppacket(via->connection, packet))
 439                         terminate_connection(via->connection, true);
 440         } else
 441                 send_udppacket(via, packet);
 442 }
 443
 444 /* Broadcast a packet using the minimum spanning tree */
 445
 446 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 447 {
 448         avl_node_t *node;
 449         connection_t *c;
 450
 451         cp();
 452
 453         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 454                            packet->len, from->name, from->hostname);
 455
 456         for(node = connection_tree->head; node; node = node->next) {
 457                 c = node->data;
 458
 459                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 460                         send_packet(c->node, packet);
 461         }
 462 }
 463
 464 void flush_queue(node_t *n)
 465 {
 466         list_node_t *node, *next;
 467
 468         cp();
 469
 470         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 471
 472         for(node = n->queue->head; node; node = next) {
 473                 next = node->next;
 474                 send_udppacket(n, node->data);
 475                 list_delete_node(n->queue, node);
 476         }
 477 }
 478
 479 void handle_incoming_vpn_data(int sock)
 480 {
 481         vpn_packet_t pkt;
 482         char *hostname;
 483         sockaddr_t from;
 484         socklen_t fromlen = sizeof(from);
 485         node_t *n;
 486
 487         cp();
 488
 489         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 490
 491         if(pkt.len < 0) {
 492                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 493                 return;
 494         }
 495
 496         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 497
 498         n = lookup_node_udp(&from);
 499
 500         if(!n) {
 501                 hostname = sockaddr2hostname(&from);
 502                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 503                            hostname);
 504                 free(hostname);
 505                 return;
 506         }
 507
 508         receive_udppacket(n, &pkt);
 509 }