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) 1998-2003 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 <gcrypt.h>
  26
  27 #include <zlib.h>
  28 #include <lzo1x.h>
  29
  30 #include "avl_tree.h"
  31 #include "conf.h"
  32 #include "connection.h"
  33 #include "device.h"
  34 #include "ethernet.h"
  35 #include "event.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 void send_mtu_probe(node_t *n)
  60 {
  61         vpn_packet_t packet;
  62         int len, i;
  63
  64         cp();
  65
  66         n->mtuprobes++;
  67         n->mtuevent = NULL;
  68
  69         if(n->mtuprobes >= 10 && !n->minmtu) {
  70                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  71                 return;
  72         }
  73
  74         for(i = 0; i < 3; i++) {
  75                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  76                         n->mtu = n->minmtu;
  77                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  78                         return;
  79                 }
  80
  81                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
  82                 if(len < 64)
  83                         len = 64;
  84
  85                 memset(packet.data, 0, 14);
  86                 gcry_randomize(packet.data + 14, len - 14, GCRY_WEAK_RANDOM);
  87                 packet.len = len;
  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         n->mtuevent = xmalloc(sizeof(*n->mtuevent));
  95         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
  96         n->mtuevent->data = n;
  97         n->mtuevent->time = now + 1;
  98         event_add(n->mtuevent);
  99 }
 100
 101 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 102         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 103
 104         if(!packet->data[0]) {
 105                 packet->data[0] = 1;
 106                 send_packet(n, packet);
 107         } else {
 108                 if(n->minmtu < packet->len)
 109                         n->minmtu = packet->len;
 110         }
 111 }
 112
 113 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 114 {
 115         if(level == 10) {
 116                 lzo_uint lzolen = MAXSIZE;
 117                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 118                 return lzolen;
 119         } else if(level < 10) {
 120                 unsigned long destlen = MAXSIZE;
 121                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 122                         return destlen;
 123                 else
 124                         return -1;
 125         } else {
 126                 lzo_uint lzolen = MAXSIZE;
 127                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 128                 return lzolen;
 129         }
 130
 131         return -1;
 132 }
 133
 134 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 135 {
 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 {
 157         cp();
 158
 159         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 160                            packet->len, n->name, n->hostname);
 161
 162         route(n, packet);
 163 }
 164
 165 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 166 {
 167         vpn_packet_t pkt1, pkt2;
 168         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 169         int nextpkt = 0;
 170         vpn_packet_t *outpkt = pkt[0];
 171         char *hmac = NULL;
 172         int result;
 173         int i;
 174         static char iv[32] = {0};
 175
 176         cp();
 177
 178         /* Check packet length */
 179
 180         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 181                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 182                                         n->name, n->hostname);
 183                 return;
 184         }
 185
 186         /* Check the message authentication code */
 187
 188         if(myself->digest && myself->maclength) {
 189                 inpkt->len -= myself->maclength;
 190                 gcry_md_reset(myself->digest_ctx);
 191                 gcry_md_write(myself->digest_ctx, (char *)&inpkt->seqno, inpkt->len);
 192                 hmac = gcry_md_read(myself->digest_ctx, 0);
 193
 194                 if(!hmac || memcmp(hmac, (char *)&inpkt->seqno + inpkt->len, myself->maclength)) {
 195                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 196                                            n->name, n->hostname);
 197                         return;
 198                 }
 199         }
 200
 201         /* Decrypt the packet */
 202
 203         if(myself->cipher) {
 204                 gcry_cipher_reset(myself->cipher_ctx);
 205                 //memcpy(iv, &inpkt->seqno, sizeof inpkt->seqno);
 206                 //gcry_cipher_setiv(myself->cipher_ctx, iv, myself->cipherblklen);
 207                 result = gcry_cipher_decrypt(myself->cipher_ctx, (char *)&inpkt->seqno, inpkt->len, NULL, 0);
 208
 209                 if(result) {
 210                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 211                                                 n->name, n->hostname, gpg_strerror(result));
 212                         logger(LOG_DEBUG, "%p %p %d", myself->cipher_ctx, (char *)&inpkt->seqno, inpkt->len);
 213                         return;
 214                 }
 215         }
 216
 217         /* Remove padding */
 218
 219         if(myself->cipherblklen > 1) {
 220                 int padlen;
 221
 222                 padlen = ((uint8_t *)&inpkt->seqno)[inpkt->len - 1];
 223
 224                 if(padlen && padlen <= myself->cipherblklen)
 225                         inpkt->len -= padlen;
 226         }
 227
 228         /* Check the sequence number */
 229
 230         inpkt->len -= sizeof(inpkt->seqno);
 231         inpkt->seqno = ntohl(inpkt->seqno);
 232
 233         if(inpkt->seqno != n->received_seqno + 1) {
 234                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 235                         logger(LOG_WARNING, _("Lost %u packets from %s (%s)"),
 236                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 237
 238                         memset(n->late, 0, sizeof(n->late));
 239                 } else if (inpkt->seqno <= n->received_seqno) {
 240                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 241                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %u, last received %u"),
 242                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 243                         } else
 244                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 245                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 246                 }
 247         }
 248
 249         if(inpkt->seqno > n->received_seqno) {
 250                 n->received_seqno = inpkt->seqno;
 251                 n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 252         }
 253
 254         if(n->received_seqno > MAX_SEQNO)
 255                 keyexpires = 0;
 256
 257         /* Decompress the packet */
 258
 259         if(myself->compression) {
 260                 outpkt = pkt[nextpkt++];
 261
 262                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 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
 271         if(n->connection)
 272                 n->connection->last_ping_time = now;
 273
 274         if(!inpkt->data[12] && !inpkt->data[13])
 275                 mtu_probe_h(n, inpkt);
 276         else
 277                 receive_packet(n, inpkt);
 278 }
 279
 280 void receive_tcppacket(connection_t *c, char *buffer, int len)
 281 {
 282         vpn_packet_t outpkt;
 283
 284         cp();
 285
 286         outpkt.len = len;
 287         memcpy(outpkt.data, buffer, len);
 288
 289         receive_packet(c->node, &outpkt);
 290 }
 291
 292 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 293 {
 294         vpn_packet_t pkt1, pkt2;
 295         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 296         int nextpkt = 0;
 297         vpn_packet_t *outpkt;
 298         int origlen;
 299         int result;
 300         vpn_packet_t *copy;
 301         static int priority = 0;
 302         int origpriority;
 303         int sock;
 304         char *hmac = NULL;
 305         static char iv[32] = {0};
 306
 307         cp();
 308
 309         /* Make sure we have a valid key */
 310
 311         if(!n->status.validkey) {
 312                 ifdebug(TRAFFIC) logger(LOG_INFO,
 313                                    _("No valid key known yet for %s (%s), queueing packet"),
 314                                    n->name, n->hostname);
 315
 316                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 317
 318                 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
 319
 320                 list_insert_tail(n->queue, copy);
 321
 322                 if(n->queue->count > MAXQUEUELENGTH)
 323                         list_delete_head(n->queue);
 324
 325                 if(!n->status.waitingforkey)
 326                         send_req_key(n->nexthop->connection, myself, n);
 327
 328                 n->status.waitingforkey = true;
 329
 330                 return;
 331         }
 332
 333         origlen = inpkt->len;
 334         origpriority = inpkt->priority;
 335
 336         /* Compress the packet */
 337
 338         if(n->compression) {
 339                 outpkt = pkt[nextpkt++];
 340
 341                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 342                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 343                                    n->name, n->hostname);
 344                         return;
 345                 }
 346
 347                 inpkt = outpkt;
 348         }
 349
 350         /* Add sequence number */
 351
 352         inpkt->seqno = htonl(++(n->sent_seqno));
 353         inpkt->len += sizeof(inpkt->seqno);
 354
 355         /* Encrypt the packet */
 356
 357         if(n->cipher) {
 358                 /* Add padding */
 359
 360                 if(n->cipherblklen > 1) {
 361                         int padlen, i;
 362                         uint8_t *p;
 363
 364                         padlen = n->cipherblklen - inpkt->len % n->cipherblklen;
 365                         p = (char *)&inpkt->seqno + inpkt->len;
 366
 367                         if(padlen == n->cipherblklen) {
 368                                 if(p[-1] != 0 && p[-1] <= n->cipherblklen) {
 369                                         inpkt->len += n->cipherblklen;
 370                                         for(i = 0; i < n->cipherblklen; i++)
 371                                                 *p++ = i + 1;
 372                                 }
 373                         } else {
 374                                 inpkt->len += padlen;
 375                                 for(i = 0; i < padlen; i++)
 376                                         *p++ = i + 1;
 377                         }
 378                 }
 379
 380                 gcry_cipher_reset(n->cipher_ctx);
 381                 //memcpy(iv, &inpkt->seqno, sizeof inpkt->seqno);
 382                 //gcry_cipher_setiv(n->cipher_ctx, iv, n->cipherblklen);
 383                 result = gcry_cipher_encrypt(n->cipher_ctx, (char *)&inpkt->seqno, inpkt->len, NULL, 0);
 384
 385                 if(result) {
 386                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 387                                                 n->name, n->hostname, gpg_strerror(result));
 388                         goto end;
 389                 }
 390         }
 391
 392         /* Add the message authentication code */
 393
 394         if(n->digest && n->maclength) {
 395                 gcry_md_reset(n->digest_ctx);
 396                 gcry_md_write(n->digest_ctx, (char *)&inpkt->seqno, inpkt->len);
 397                 hmac = gcry_md_read(n->digest_ctx, 0);
 398
 399                 if(!hmac) {
 400                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while authenticating packet to %s (%s)"),
 401                                                 n->name, n->hostname);
 402                         goto end;
 403                 }
 404
 405                 memcpy((char *)&inpkt->seqno + inpkt->len, hmac, n->maclength);
 406                 inpkt->len += n->maclength;
 407         }
 408
 409         /* Determine which socket we have to use */
 410
 411         for(sock = 0; sock < listen_sockets; sock++)
 412                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 413                         break;
 414
 415         if(sock >= listen_sockets)
 416                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 417
 418         /* Send the packet */
 419
 420 #if defined(SOL_IP) && defined(IP_TOS)
 421         if(priorityinheritance && origpriority != priority
 422            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 423                 priority = origpriority;
 424                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 425                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 426                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 427         }
 428 #endif
 429
 430         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 431                 if(errno == EMSGSIZE) {
 432                         if(n->maxmtu >= origlen)
 433                                 n->maxmtu = origlen - 1;
 434                         if(n->mtu >= origlen)
 435                                 n->mtu = origlen - 1;
 436                 } else
 437                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 438         }
 439
 440 end:
 441         inpkt->len = origlen;
 442 }
 443
 444 /*
 445   send a packet to the given vpn ip.
 446 */
 447 void send_packet(const node_t *n, vpn_packet_t *packet)
 448 {
 449         node_t *via;
 450
 451         cp();
 452
 453         if(n == myself) {
 454                 if(overwrite_mac)
 455                          memcpy(packet->data, mymac.x, ETH_ALEN);
 456                 write_packet(packet);
 457                 return;
 458         }
 459
 460         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 461                            packet->len, n->name, n->hostname);
 462
 463         if(!n->status.reachable) {
 464                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 465                                    n->name, n->hostname);
 466                 return;
 467         }
 468
 469         via = (n->via == myself) ? n->nexthop : n->via;
 470
 471         if(via != n)
 472                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 473                            n->name, via->name, n->via->hostname);
 474
 475         if((myself->options | via->options) & OPTION_TCPONLY) {
 476                 if(!send_tcppacket(via->connection, packet))
 477                         terminate_connection(via->connection, true);
 478         } else
 479                 send_udppacket(via, packet);
 480 }
 481
 482 /* Broadcast a packet using the minimum spanning tree */
 483
 484 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 485 {
 486         avl_node_t *node;
 487         connection_t *c;
 488
 489         cp();
 490
 491         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 492                            packet->len, from->name, from->hostname);
 493
 494         for(node = connection_tree->head; node; node = node->next) {
 495                 c = node->data;
 496
 497                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 498                         send_packet(c->node, packet);
 499         }
 500 }
 501
 502 void flush_queue(node_t *n)
 503 {
 504         list_node_t *node, *next;
 505
 506         cp();
 507
 508         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 509
 510         for(node = n->queue->head; node; node = next) {
 511                 next = node->next;
 512                 send_udppacket(n, node->data);
 513                 list_delete_node(n->queue, node);
 514         }
 515 }
 516
 517 void handle_incoming_vpn_data(int sock)
 518 {
 519         vpn_packet_t pkt;
 520         char *hostname;
 521         sockaddr_t from;
 522         socklen_t fromlen = sizeof(from);
 523         node_t *n;
 524
 525         cp();
 526
 527         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 528
 529         if(pkt.len < 0) {
 530                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 531                 return;
 532         }
 533
 534         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 535
 536         n = lookup_node_udp(&from);
 537
 538         if(!n) {
 539                 hostname = sockaddr2hostname(&from);
 540                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 541                            hostname);
 542                 free(hostname);
 543                 return;
 544         }
 545
 546         receive_udppacket(n, &pkt);
 547 }