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 1.1.2.41 2003/09/23 20:59:01 guus Exp $
  21 */
  22
  23 #include "system.h"
  24
  25 #include <openssl/rand.h>
  26 #include <openssl/evp.h>
  27 #include <openssl/pem.h>
  28 #include <openssl/hmac.h>
  29
  30 #include <zlib.h>
  31 #include <lzo1x.h>
  32
  33 #include "avl_tree.h"
  34 #include "conf.h"
  35 #include "connection.h"
  36 #include "device.h"
  37 #include "event.h"
  38 #include "graph.h"
  39 #include "list.h"
  40 #include "logger.h"
  41 #include "net.h"
  42 #include "netutl.h"
  43 #include "protocol.h"
  44 #include "process.h"
  45 #include "route.h"
  46 #include "utils.h"
  47 #include "xalloc.h"
  48
  49 int keylifetime = 0;
  50 int keyexpires = 0;
  51 EVP_CIPHER_CTX packet_ctx;
  52 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  53
  54
  55 #define MAX_SEQNO 1073741824
  56
  57 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
  58 {
  59         if(level == 10) {
  60                 lzo_uint lzolen = MAXSIZE;
  61                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
  62                 return lzolen;
  63         } else if(level < 10) {
  64                 unsigned long destlen = MAXSIZE;
  65                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
  66                         return destlen;
  67                 else
  68                         return -1;
  69         } else {
  70                 lzo_uint lzolen = MAXSIZE;
  71                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
  72                 return lzolen;
  73         }
  74
  75         return -1;
  76 }
  77
  78 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
  79 {
  80         if(level > 9) {
  81                 lzo_uint lzolen = MAXSIZE;
  82                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
  83                         return lzolen;
  84                 else
  85                         return -1;
  86         } else {
  87                 unsigned long destlen = MAXSIZE;
  88                 if(uncompress(dest, &destlen, source, len) == Z_OK)
  89                         return destlen;
  90                 else
  91                         return -1;
  92         }
  93
  94         return -1;
  95 }
  96
  97 /* VPN packet I/O */
  98
  99 static void receive_packet(node_t *n, vpn_packet_t *packet)
 100 {
 101         cp();
 102
 103         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 104                            packet->len, n->name, n->hostname);
 105
 106         route_incoming(n, packet);
 107 }
 108
 109 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 110 {
 111         vpn_packet_t pkt1, pkt2;
 112         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 113         int nextpkt = 0;
 114         vpn_packet_t *outpkt = pkt[0];
 115         int outlen, outpad;
 116         char hmac[EVP_MAX_MD_SIZE];
 117         int i;
 118
 119         cp();
 120
 121         /* Check packet length */
 122
 123         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 124                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 125                                         n->name, n->hostname);
 126                 return;
 127         }
 128
 129         /* Check the message authentication code */
 130
 131         if(myself->digest && myself->maclength) {
 132                 inpkt->len -= myself->maclength;
 133                 HMAC(myself->digest, myself->key, myself->keylength,
 134                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 135
 136                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 137                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 138                                            n->name, n->hostname);
 139                         return;
 140                 }
 141         }
 142
 143         /* Decrypt the packet */
 144
 145         if(myself->cipher) {
 146                 outpkt = pkt[nextpkt++];
 147
 148 //              EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key,
 149 //                                              myself->key + myself->cipher->key_len);
 150                 EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL);
 151                 EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 152                                                   (char *) &inpkt->seqno, inpkt->len);
 153                 EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 154
 155                 outpkt->len = outlen + outpad;
 156                 inpkt = outpkt;
 157         }
 158
 159         /* Check the sequence number */
 160
 161         inpkt->len -= sizeof(inpkt->seqno);
 162         inpkt->seqno = ntohl(inpkt->seqno);
 163
 164         if(inpkt->seqno != n->received_seqno + 1) {
 165                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 166                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 167                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 168
 169                         memset(n->late, 0, sizeof(n->late));
 170                 } else if (inpkt->seqno <= n->received_seqno) {
 171                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 172                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 173                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 174                         } else
 175                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 176                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 177                 }
 178         }
 179
 180         n->received_seqno = inpkt->seqno;
 181         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 182
 183         if(n->received_seqno > MAX_SEQNO)
 184                 keyexpires = 0;
 185
 186         /* Decompress the packet */
 187
 188         if(myself->compression) {
 189                 outpkt = pkt[nextpkt++];
 190
 191                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 192                         logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 193                                    n->name, n->hostname);
 194                         return;
 195                 }
 196
 197                 inpkt = outpkt;
 198         }
 199
 200         if(n->connection)
 201                 n->connection->last_ping_time = now;
 202
 203         receive_packet(n, inpkt);
 204 }
 205
 206 void receive_tcppacket(connection_t *c, char *buffer, int len)
 207 {
 208         vpn_packet_t outpkt;
 209
 210         cp();
 211
 212         outpkt.len = len;
 213         memcpy(outpkt.data, buffer, len);
 214
 215         receive_packet(c->node, &outpkt);
 216 }
 217
 218 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 219 {
 220         vpn_packet_t pkt1, pkt2;
 221         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 222         int nextpkt = 0;
 223         vpn_packet_t *outpkt;
 224         int origlen;
 225         int outlen, outpad;
 226         vpn_packet_t *copy;
 227         static int priority = 0;
 228         int origpriority;
 229         int sock;
 230
 231         cp();
 232
 233         /* Make sure we have a valid key */
 234
 235         if(!n->status.validkey) {
 236                 ifdebug(TRAFFIC) logger(LOG_INFO,
 237                                    _("No valid key known yet for %s (%s), queueing packet"),
 238                                    n->name, n->hostname);
 239
 240                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 241
 242                 copy = xmalloc(sizeof(vpn_packet_t));
 243                 memcpy(copy, inpkt, sizeof(vpn_packet_t));
 244
 245                 list_insert_tail(n->queue, copy);
 246
 247                 if(n->queue->count > MAXQUEUELENGTH)
 248                         list_delete_head(n->queue);
 249
 250                 if(!n->status.waitingforkey)
 251                         send_req_key(n->nexthop->connection, myself, n);
 252
 253                 n->status.waitingforkey = true;
 254
 255                 return;
 256         }
 257
 258         origlen = inpkt->len;
 259         origpriority = inpkt->priority;
 260
 261         /* Compress the packet */
 262
 263         if(n->compression) {
 264                 outpkt = pkt[nextpkt++];
 265
 266                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 267                         logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 268                                    n->name, n->hostname);
 269                         return;
 270                 }
 271
 272                 inpkt = outpkt;
 273         }
 274
 275         /* Add sequence number */
 276
 277         inpkt->seqno = htonl(++(n->sent_seqno));
 278         inpkt->len += sizeof(inpkt->seqno);
 279
 280         /* Encrypt the packet */
 281
 282         if(n->cipher) {
 283                 outpkt = pkt[nextpkt++];
 284
 285 //              EVP_EncryptInit_ex(&packet_ctx, n->cipher, NULL, n->key, n->key + n->cipher->key_len);
 286                 EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL);
 287                 EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 288                                                   (char *) &inpkt->seqno, inpkt->len);
 289                 EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 290
 291                 outpkt->len = outlen + outpad;
 292                 inpkt = outpkt;
 293         }
 294
 295         /* Add the message authentication code */
 296
 297         if(n->digest && n->maclength) {
 298                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 299                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 300                 inpkt->len += n->maclength;
 301         }
 302
 303         /* Determine which socket we have to use */
 304
 305         for(sock = 0; sock < listen_sockets; sock++)
 306                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 307                         break;
 308
 309         if(sock >= listen_sockets)
 310                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 311
 312         /* Send the packet */
 313
 314 #if defined(SOL_IP) && defined(IP_TOS)
 315         if(priorityinheritance && origpriority != priority
 316            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 317                 priority = origpriority;
 318                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 319                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 320                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 321         }
 322 #endif
 323
 324         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 325                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 326                 return;
 327         }
 328
 329         inpkt->len = origlen;
 330 }
 331
 332 /*
 333   send a packet to the given vpn ip.
 334 */
 335 void send_packet(const node_t *n, vpn_packet_t *packet)
 336 {
 337         node_t *via;
 338
 339         cp();
 340
 341         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 342                            packet->len, n->name, n->hostname);
 343
 344         if(n == myself) {
 345                 ifdebug(TRAFFIC) logger(LOG_NOTICE, _("Packet is looping back to us!"));
 346                 return;
 347         }
 348
 349         if(!n->status.reachable) {
 350                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 351                                    n->name, n->hostname);
 352                 return;
 353         }
 354
 355         via = (n->via == myself) ? n->nexthop : n->via;
 356
 357         if(via != n)
 358                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 359                            n->name, via->name, n->via->hostname);
 360
 361         if((myself->options | via->options) & OPTION_TCPONLY) {
 362                 if(!send_tcppacket(via->connection, packet))
 363                         terminate_connection(via->connection, true);
 364         } else
 365                 send_udppacket(via, packet);
 366 }
 367
 368 /* Broadcast a packet using the minimum spanning tree */
 369
 370 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 371 {
 372         avl_node_t *node;
 373         connection_t *c;
 374
 375         cp();
 376
 377         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 378                            packet->len, from->name, from->hostname);
 379
 380         for(node = connection_tree->head; node; node = node->next) {
 381                 c = node->data;
 382
 383                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 384                         send_packet(c->node, packet);
 385         }
 386 }
 387
 388 void flush_queue(node_t *n)
 389 {
 390         list_node_t *node, *next;
 391
 392         cp();
 393
 394         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 395
 396         for(node = n->queue->head; node; node = next) {
 397                 next = node->next;
 398                 send_udppacket(n, node->data);
 399                 list_delete_node(n->queue, node);
 400         }
 401 }
 402
 403 void handle_incoming_vpn_data(int sock)
 404 {
 405         vpn_packet_t pkt;
 406         char *hostname;
 407         sockaddr_t from;
 408         socklen_t fromlen = sizeof(from);
 409         node_t *n;
 410
 411         cp();
 412
 413         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 414
 415         if(pkt.len < 0) {
 416                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 417                 return;
 418         }
 419
 420         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 421
 422         n = lookup_node_udp(&from);
 423
 424         if(!n) {
 425                 hostname = sockaddr2hostname(&from);
 426                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 427                            hostname);
 428                 free(hostname);
 429                 return;
 430         }
 431
 432         receive_udppacket(n, &pkt);
 433 }