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                   2000-2006 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 #ifdef HAVE_LZO_LZO1X_H
  33 #include <lzo/lzo1x.h>
  34 #endif
  35 #ifdef HAVE_LZO1X_H
  36 #include <lzo1x.h>
  37 #endif
  38
  39 #include "avl_tree.h"
  40 #include "conf.h"
  41 #include "connection.h"
  42 #include "device.h"
  43 #include "ethernet.h"
  44 #include "event.h"
  45 #include "graph.h"
  46 #include "list.h"
  47 #include "logger.h"
  48 #include "net.h"
  49 #include "netutl.h"
  50 #include "protocol.h"
  51 #include "process.h"
  52 #include "route.h"
  53 #include "utils.h"
  54 #include "xalloc.h"
  55
  56 #ifdef WSAEMSGSIZE
  57 #define EMSGSIZE WSAEMSGSIZE
  58 #endif
  59
  60 int keylifetime = 0;
  61 int keyexpires = 0;
  62 EVP_CIPHER_CTX packet_ctx;
  63 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  64
  65 static void send_udppacket(node_t *, vpn_packet_t *);
  66
  67 #define MAX_SEQNO 1073741824
  68
  69 void send_mtu_probe(node_t *n)
  70 {
  71         vpn_packet_t packet;
  72         int len, i;
  73
  74         cp();
  75
  76         n->mtuprobes++;
  77         n->mtuevent = NULL;
  78
  79         if(n->mtuprobes >= 10 && !n->minmtu) {
  80                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  81                 return;
  82         }
  83
  84         for(i = 0; i < 3; i++) {
  85                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  86                         n->mtu = n->minmtu;
  87                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  88                         return;
  89                 }
  90
  91                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
  92                 if(len < 64)
  93                         len = 64;
  94
  95                 memset(packet.data, 0, 14);
  96                 RAND_pseudo_bytes(packet.data + 14, len - 14);
  97                 packet.len = len;
  98
  99                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
 100
 101                 send_udppacket(n, &packet);
 102         }
 103
 104         n->mtuevent = new_event();
 105         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 106         n->mtuevent->data = n;
 107         n->mtuevent->time = now + 1;
 108         event_add(n->mtuevent);
 109 }
 110
 111 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 112         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 113
 114         if(!packet->data[0]) {
 115                 packet->data[0] = 1;
 116                 send_packet(n, packet);
 117         } else {
 118                 if(n->minmtu < packet->len)
 119                         n->minmtu = packet->len;
 120         }
 121 }
 122
 123 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 124 {
 125         if(level == 10) {
 126                 lzo_uint lzolen = MAXSIZE;
 127                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 128                 return lzolen;
 129         } else if(level < 10) {
 130                 unsigned long destlen = MAXSIZE;
 131                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 132                         return destlen;
 133                 else
 134                         return -1;
 135         } else {
 136                 lzo_uint lzolen = MAXSIZE;
 137                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 138                 return lzolen;
 139         }
 140
 141         return -1;
 142 }
 143
 144 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 145 {
 146         if(level > 9) {
 147                 lzo_uint lzolen = MAXSIZE;
 148                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 149                         return lzolen;
 150                 else
 151                         return -1;
 152         } else {
 153                 unsigned long destlen = MAXSIZE;
 154                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 155                         return destlen;
 156                 else
 157                         return -1;
 158         }
 159
 160         return -1;
 161 }
 162
 163 /* VPN packet I/O */
 164
 165 static void receive_packet(node_t *n, vpn_packet_t *packet)
 166 {
 167         cp();
 168
 169         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 170                            packet->len, n->name, n->hostname);
 171
 172         route(n, packet);
 173 }
 174
 175 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 176 {
 177         vpn_packet_t pkt1, pkt2;
 178         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 179         int nextpkt = 0;
 180         vpn_packet_t *outpkt = pkt[0];
 181         int outlen, outpad;
 182         unsigned char hmac[EVP_MAX_MD_SIZE];
 183         int i;
 184
 185         cp();
 186
 187         /* Check packet length */
 188
 189         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 190                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 191                                         n->name, n->hostname);
 192                 return;
 193         }
 194
 195         /* Check the message authentication code */
 196
 197         if(myself->digest && myself->maclength) {
 198                 inpkt->len -= myself->maclength;
 199                 HMAC(myself->digest, myself->key, myself->keylength,
 200                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 201
 202                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 203                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 204                                            n->name, n->hostname);
 205                         return;
 206                 }
 207         }
 208
 209         /* Decrypt the packet */
 210
 211         if(myself->cipher) {
 212                 outpkt = pkt[nextpkt++];
 213
 214                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
 215                                 || !EVP_DecryptUpdate(&packet_ctx, (unsigned char *) &outpkt->seqno, &outlen,
 216                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 217                                 || !EVP_DecryptFinal_ex(&packet_ctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 218                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 219                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 220                         return;
 221                 }
 222
 223                 outpkt->len = outlen + outpad;
 224                 inpkt = outpkt;
 225         }
 226
 227         /* Check the sequence number */
 228
 229         inpkt->len -= sizeof(inpkt->seqno);
 230         inpkt->seqno = ntohl(inpkt->seqno);
 231
 232         if(inpkt->seqno != n->received_seqno + 1) {
 233                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 234                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 235                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 236
 237                         memset(n->late, 0, sizeof(n->late));
 238                 } else if (inpkt->seqno <= n->received_seqno) {
 239                         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))) {
 240                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 241                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 242                                 return;
 243                         }
 244                 } else {
 245                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 246                                 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
 247                 }
 248         }
 249
 250         n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
 251
 252         if(inpkt->seqno > n->received_seqno)
 253                 n->received_seqno = inpkt->seqno;
 254
 255         if(n->received_seqno > MAX_SEQNO)
 256                 keyexpires = 0;
 257
 258         /* Decompress the packet */
 259
 260         if(myself->compression) {
 261                 outpkt = pkt[nextpkt++];
 262
 263                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 264                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 265                                                  n->name, n->hostname);
 266                         return;
 267                 }
 268
 269                 inpkt = outpkt;
 270         }
 271
 272         if(n->connection)
 273                 n->connection->last_ping_time = now;
 274
 275         if(!inpkt->data[12] && !inpkt->data[13])
 276                 mtu_probe_h(n, inpkt);
 277         else
 278                 receive_packet(n, inpkt);
 279 }
 280
 281 void receive_tcppacket(connection_t *c, char *buffer, int len)
 282 {
 283         vpn_packet_t outpkt;
 284
 285         cp();
 286
 287         outpkt.len = len;
 288         memcpy(outpkt.data, buffer, len);
 289
 290         receive_packet(c->node, &outpkt);
 291 }
 292
 293 static void send_udppacket(node_t *n, vpn_packet_t *origpkt)
 294 {
 295         vpn_packet_t pkt1, pkt2;
 296         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 297         vpn_packet_t *inpkt = origpkt;
 298         int nextpkt = 0;
 299         vpn_packet_t *outpkt;
 300         int origlen;
 301         int outlen, outpad;
 302         vpn_packet_t *copy;
 303         static int priority = 0;
 304         int origpriority;
 305         int sock;
 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                 outpkt = pkt[nextpkt++];
 359
 360                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
 361                                 || !EVP_EncryptUpdate(&n->packet_ctx, (unsigned char *) &outpkt->seqno, &outlen,
 362                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 363                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 364                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 365                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 366                         goto end;
 367                 }
 368
 369                 outpkt->len = outlen + outpad;
 370                 inpkt = outpkt;
 371         }
 372
 373         /* Add the message authentication code */
 374
 375         if(n->digest && n->maclength) {
 376                 HMAC(n->digest, n->key, n->keylength, (unsigned char *) &inpkt->seqno,
 377                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 378                 inpkt->len += n->maclength;
 379         }
 380
 381         /* Determine which socket we have to use */
 382
 383         for(sock = 0; sock < listen_sockets; sock++)
 384                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 385                         break;
 386
 387         if(sock >= listen_sockets)
 388                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 389
 390         /* Send the packet */
 391
 392 #if defined(SOL_IP) && defined(IP_TOS)
 393         if(priorityinheritance && origpriority != priority
 394            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 395                 priority = origpriority;
 396                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 397                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 398                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 399         }
 400 #endif
 401
 402         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 403                 if(errno == EMSGSIZE) {
 404                         if(n->maxmtu >= origlen)
 405                                 n->maxmtu = origlen - 1;
 406                         if(n->mtu >= origlen)
 407                                 n->mtu = origlen - 1;
 408                 } else
 409                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 410         }
 411
 412 end:
 413         origpkt->len = origlen;
 414 }
 415
 416 /*
 417   send a packet to the given vpn ip.
 418 */
 419 void send_packet(const node_t *n, vpn_packet_t *packet)
 420 {
 421         node_t *via;
 422
 423         cp();
 424
 425         if(n == myself) {
 426                 if(overwrite_mac)
 427                          memcpy(packet->data, mymac.x, ETH_ALEN);
 428                 write_packet(packet);
 429                 return;
 430         }
 431
 432         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 433                            packet->len, n->name, n->hostname);
 434
 435         if(!n->status.reachable) {
 436                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 437                                    n->name, n->hostname);
 438                 return;
 439         }
 440
 441         via = (n->via == myself) ? n->nexthop : n->via;
 442
 443         if(via != n)
 444                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 445                            n->name, via->name, n->via->hostname);
 446
 447         if((myself->options | via->options) & OPTION_TCPONLY) {
 448                 if(!send_tcppacket(via->connection, packet))
 449                         terminate_connection(via->connection, true);
 450         } else
 451                 send_udppacket(via, packet);
 452 }
 453
 454 /* Broadcast a packet using the minimum spanning tree */
 455
 456 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 457 {
 458         avl_node_t *node;
 459         connection_t *c;
 460
 461         cp();
 462
 463         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 464                            packet->len, from->name, from->hostname);
 465
 466         if(from != myself)
 467                 send_packet(myself, packet);
 468
 469         for(node = connection_tree->head; node; node = node->next) {
 470                 c = node->data;
 471
 472                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 473                         send_packet(c->node, packet);
 474         }
 475 }
 476
 477 void flush_queue(node_t *n)
 478 {
 479         list_node_t *node, *next;
 480
 481         cp();
 482
 483         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 484
 485         for(node = n->queue->head; node; node = next) {
 486                 next = node->next;
 487                 send_udppacket(n, node->data);
 488                 list_delete_node(n->queue, node);
 489         }
 490 }
 491
 492 void handle_incoming_vpn_data(int sock)
 493 {
 494         vpn_packet_t pkt;
 495         char *hostname;
 496         sockaddr_t from;
 497         socklen_t fromlen = sizeof(from);
 498         node_t *n;
 499
 500         cp();
 501
 502         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 503
 504         if(pkt.len < 0) {
 505                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 506                 return;
 507         }
 508
 509         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 510
 511         n = lookup_node_udp(&from);
 512
 513         if(!n) {
 514                 hostname = sockaddr2hostname(&from);
 515                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 516                            hostname);
 517                 free(hostname);
 518                 return;
 519         }
 520
 521         receive_udppacket(n, &pkt);
 522 }