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

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2002 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000-2002 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 1.1.2.28 2003/05/06 21:13:17 guus Exp $
  21 */
  22
  23 #include "config.h"
  24
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <netdb.h>
  28 #include <netinet/in.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <signal.h>
  33 #include <sys/time.h>
  34 #include <sys/types.h>
  35 #include <syslog.h>
  36 #include <unistd.h>
  37 #include <sys/ioctl.h>
  38 /* SunOS really wants sys/socket.h BEFORE net/if.h,
  39    and FreeBSD wants these lines below the rest. */
  40 #include <arpa/inet.h>
  41 #include <sys/socket.h>
  42 #include <net/if.h>
  43 #ifdef HAVE_NETINET_IN_SYSTM_H
  44 #include <netinet/in_systm.h>
  45 #endif
  46 #ifdef HAVE_NETINET_IP_H
  47 #include <netinet/ip.h>
  48 #endif
  49 #ifdef HAVE_NETINET_TCP_H
  50 #include <netinet/tcp.h>
  51 #endif
  52
  53 #include <openssl/rand.h>
  54 #include <openssl/evp.h>
  55 #include <openssl/pem.h>
  56 #include <openssl/hmac.h>
  57
  58 #include <zlib.h>
  59 #include <lzo1x.h>
  60
  61 #include <utils.h>
  62 #include <xalloc.h>
  63 #include <avl_tree.h>
  64 #include <list.h>
  65
  66 #include "conf.h"
  67 #include "connection.h"
  68 #include "meta.h"
  69 #include "net.h"
  70 #include "netutl.h"
  71 #include "process.h"
  72 #include "protocol.h"
  73 #include "subnet.h"
  74 #include "graph.h"
  75 #include "process.h"
  76 #include "route.h"
  77 #include "device.h"
  78 #include "event.h"
  79
  80 #include "system.h"
  81
  82 int keylifetime = 0;
  83 int keyexpires = 0;
  84 EVP_CIPHER_CTX packet_ctx;
  85 char lzo_wrkmem[MAXSIZE];
  86
  87
  88 #define MAX_SEQNO 1073741824
  89
  90 length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
  91 {
  92         if(level == 10) {
  93                 lzo_uint lzolen = sizeof(lzo_wrkmem);
  94                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
  95                 return lzolen;
  96         } else if(level < 10) {
  97                 unsigned long destlen;
  98                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
  99                         return destlen;
 100                 else
 101                         return -1;
 102         } else {
 103                 lzo_uint lzolen = sizeof(lzo_wrkmem);
 104                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 105                 return lzolen;
 106         }
 107
 108         return -1;
 109 }
 110
 111 length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 112 {
 113         if(level > 9) {
 114                 lzo_uint lzolen = sizeof(lzo_wrkmem);
 115                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 116                         return lzolen;
 117                 else
 118                         return -1;
 119         } else {
 120                 unsigned long destlen;
 121                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 122                         return destlen;
 123                 else
 124                         return -1;
 125         }
 126
 127         return -1;
 128 }
 129
 130 /* VPN packet I/O */
 131
 132 void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 133 {
 134         vpn_packet_t pkt1, pkt2;
 135         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 136         int nextpkt = 0;
 137         vpn_packet_t *outpkt = pkt[0];
 138         int outlen, outpad;
 139         long int complen = MTU + 12;
 140         char hmac[EVP_MAX_MD_SIZE];
 141         int i;
 142
 143         cp();
 144
 145         /* Check the message authentication code */
 146
 147         if(myself->digest && myself->maclength) {
 148                 inpkt->len -= myself->maclength;
 149                 HMAC(myself->digest, myself->key, myself->keylength,
 150                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 151
 152                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 153                         if(debug_lvl >= DEBUG_TRAFFIC)
 154                                 syslog(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 155                                            n->name, n->hostname);
 156                         return;
 157                 }
 158         }
 159
 160         /* Decrypt the packet */
 161
 162         if(myself->cipher) {
 163                 outpkt = pkt[nextpkt++];
 164
 165 //              EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key,
 166 //                                              myself->key + myself->cipher->key_len);
 167                 EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL);
 168                 EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 169                                                   (char *) &inpkt->seqno, inpkt->len);
 170                 EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 171
 172                 outpkt->len = outlen + outpad;
 173                 inpkt = outpkt;
 174         }
 175
 176         /* Check the sequence number */
 177
 178         inpkt->len -= sizeof(inpkt->seqno);
 179         inpkt->seqno = ntohl(inpkt->seqno);
 180
 181         if(inpkt->seqno != n->received_seqno + 1) {
 182                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 183                         if(debug_lvl >= DEBUG_TRAFFIC)
 184                                 syslog(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 185                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 186
 187                         memset(n->late, 0, sizeof(n->late));
 188                 } else if (inpkt->seqno <= n->received_seqno) {
 189                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 190                                 syslog(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 191                                            n->name, n->hostname, inpkt->seqno, n->received_seqno, n->late[(inpkt->seqno / 8) % sizeof(n->late)]);
 192                         } else
 193                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 194                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 195                 }
 196         }
 197
 198         n->received_seqno = inpkt->seqno;
 199         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 200
 201         if(n->received_seqno > MAX_SEQNO)
 202                 keyexpires = 0;
 203
 204         /* Decompress the packet */
 205
 206         if(myself->compression) {
 207                 outpkt = pkt[nextpkt++];
 208
 209                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 210                         syslog(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 211                                    n->name, n->hostname);
 212                         return;
 213                 }
 214
 215                 inpkt = outpkt;
 216         }
 217
 218         receive_packet(n, inpkt);
 219 }
 220
 221 void receive_tcppacket(connection_t *c, char *buffer, int len)
 222 {
 223         vpn_packet_t outpkt;
 224
 225         cp();
 226
 227         outpkt.len = len;
 228         memcpy(outpkt.data, buffer, len);
 229
 230         receive_packet(c->node, &outpkt);
 231 }
 232
 233 void receive_packet(node_t *n, vpn_packet_t *packet)
 234 {
 235         cp();
 236
 237         if(debug_lvl >= DEBUG_TRAFFIC)
 238                 syslog(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 239                            packet->len, n->name, n->hostname);
 240
 241         route_incoming(n, packet);
 242 }
 243
 244 void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 245 {
 246         vpn_packet_t pkt1, pkt2;
 247         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 248         int nextpkt = 0;
 249         vpn_packet_t *outpkt;
 250         int origlen;
 251         int outlen, outpad;
 252         long int complen = MTU + 12;
 253         vpn_packet_t *copy;
 254         static int priority = 0;
 255         int origpriority;
 256         int sock;
 257
 258         cp();
 259
 260         /* Make sure we have a valid key */
 261
 262         if(!n->status.validkey) {
 263                 if(debug_lvl >= DEBUG_TRAFFIC)
 264                         syslog(LOG_INFO,
 265                                    _("No valid key known yet for %s (%s), queueing packet"),
 266                                    n->name, n->hostname);
 267
 268                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 269
 270                 copy = xmalloc(sizeof(vpn_packet_t));
 271                 memcpy(copy, inpkt, sizeof(vpn_packet_t));
 272
 273                 list_insert_tail(n->queue, copy);
 274
 275                 if(n->queue->count > MAXQUEUELENGTH)
 276                         list_delete_head(n->queue);
 277
 278                 if(!n->status.waitingforkey)
 279                         send_req_key(n->nexthop->connection, myself, n);
 280
 281                 n->status.waitingforkey = 1;
 282
 283                 return;
 284         }
 285
 286         origlen = inpkt->len;
 287         origpriority = inpkt->priority;
 288
 289         /* Compress the packet */
 290
 291         if(n->compression) {
 292                 outpkt = pkt[nextpkt++];
 293
 294                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 295                         syslog(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 296                                    n->name, n->hostname);
 297                         return;
 298                 }
 299
 300                 inpkt = outpkt;
 301         }
 302
 303         /* Add sequence number */
 304
 305         inpkt->seqno = htonl(++(n->sent_seqno));
 306         inpkt->len += sizeof(inpkt->seqno);
 307
 308         /* Encrypt the packet */
 309
 310         if(n->cipher) {
 311                 outpkt = pkt[nextpkt++];
 312
 313 //              EVP_EncryptInit_ex(&packet_ctx, n->cipher, NULL, n->key, n->key + n->cipher->key_len);
 314                 EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL);
 315                 EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 316                                                   (char *) &inpkt->seqno, inpkt->len);
 317                 EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 318
 319                 outpkt->len = outlen + outpad;
 320                 inpkt = outpkt;
 321         }
 322
 323         /* Add the message authentication code */
 324
 325         if(n->digest && n->maclength) {
 326                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 327                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 328                 inpkt->len += n->maclength;
 329         }
 330
 331         /* Determine which socket we have to use */
 332
 333         for(sock = 0; sock < listen_sockets; sock++)
 334                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 335                         break;
 336
 337         if(sock >= listen_sockets)
 338                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 339
 340         /* Send the packet */
 341
 342 #if defined(SOL_IP) && defined(IP_TOS)
 343         if(priorityinheritance && origpriority != priority
 344            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 345                 priority = origpriority;
 346                 if(debug_lvl >= DEBUG_TRAFFIC)
 347                         syslog(LOG_DEBUG, _("Setting outgoing packet priority to %d"),
 348                                    priority);
 349                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 350                         syslog(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt",
 351                                    strerror(errno));
 352         }
 353 #endif
 354
 355         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 356                 syslog(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name,
 357                            n->hostname, strerror(errno));
 358                 return;
 359         }
 360
 361         inpkt->len = origlen;
 362 }
 363
 364 /*
 365   send a packet to the given vpn ip.
 366 */
 367 void send_packet(node_t *n, vpn_packet_t *packet)
 368 {
 369         node_t *via;
 370
 371         cp();
 372
 373         if(debug_lvl >= DEBUG_TRAFFIC)
 374                 syslog(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 375                            packet->len, n->name, n->hostname);
 376
 377         if(n == myself) {
 378                 if(debug_lvl >= DEBUG_TRAFFIC)
 379                         syslog(LOG_NOTICE, _("Packet is looping back to us!"));
 380
 381                 return;
 382         }
 383
 384         if(!n->status.reachable) {
 385                 if(debug_lvl >= DEBUG_TRAFFIC)
 386                         syslog(LOG_INFO, _("Node %s (%s) is not reachable"),
 387                                    n->name, n->hostname);
 388
 389                 return;
 390         }
 391
 392         via = (n->via == myself) ? n->nexthop : n->via;
 393
 394         if(via != n && debug_lvl >= DEBUG_TRAFFIC)
 395                 syslog(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 396                            n->name, via->name, n->via->hostname);
 397
 398         if((myself->options | via->options) & OPTION_TCPONLY) {
 399                 if(send_tcppacket(via->connection, packet))
 400                         terminate_connection(via->connection, 1);
 401         } else
 402                 send_udppacket(via, packet);
 403 }
 404
 405 /* Broadcast a packet using the minimum spanning tree */
 406
 407 void broadcast_packet(node_t *from, vpn_packet_t *packet)
 408 {
 409         avl_node_t *node;
 410         connection_t *c;
 411
 412         cp();
 413
 414         if(debug_lvl >= DEBUG_TRAFFIC)
 415                 syslog(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 416                            packet->len, from->name, from->hostname);
 417
 418         for(node = connection_tree->head; node; node = node->next) {
 419                 c = (connection_t *) node->data;
 420
 421                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 422                         send_packet(c->node, packet);
 423         }
 424 }
 425
 426 void flush_queue(node_t *n)
 427 {
 428         list_node_t *node, *next;
 429
 430         cp();
 431
 432         if(debug_lvl >= DEBUG_TRAFFIC)
 433                 syslog(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 434
 435         for(node = n->queue->head; node; node = next) {
 436                 next = node->next;
 437                 send_udppacket(n, (vpn_packet_t *) node->data);
 438                 list_delete_node(n->queue, node);
 439         }
 440 }
 441
 442 void handle_incoming_vpn_data(int sock)
 443 {
 444         vpn_packet_t pkt;
 445         int x, l = sizeof(x);
 446         char *hostname;
 447         sockaddr_t from;
 448         socklen_t fromlen = sizeof(from);
 449         node_t *n;
 450
 451         cp();
 452
 453         if(getsockopt(sock, SOL_SOCKET, SO_ERROR, &x, &l) < 0) {
 454                 syslog(LOG_ERR, _("This is a bug: %s:%d: %d:%s"),
 455                            __FILE__, __LINE__, sock, strerror(errno));
 456                 cp_trace();
 457                 exit(1);
 458         }
 459
 460         if(x) {
 461                 syslog(LOG_ERR, _("Incoming data socket error: %s"), strerror(x));
 462                 return;
 463         }
 464
 465         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 466
 467         if(pkt.len <= 0) {
 468                 syslog(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 469                 return;
 470         }
 471
 472         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 473
 474         n = lookup_node_udp(&from);
 475
 476         if(!n) {
 477                 hostname = sockaddr2hostname(&from);
 478                 syslog(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 479                            hostname);
 480                 free(hostname);
 481                 return;
 482         }
 483
 484         if(n->connection)
 485                 n->connection->last_ping_time = now;
 486
 487         receive_udppacket(n, &pkt);
 488 }