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 1.1.2.42 2003/10/10 16:24:24 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, result;
 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, NULL, NULL, NULL, NULL);
 149                 if(!EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 150                                         (char *) &inpkt->seqno, inpkt->len)) {
 151                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 152                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 153                         return;
 154                 }
 155                 if(!EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 156                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 157                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 158                         return;
 159                 }
 160
 161                 outpkt->len = outlen + outpad;
 162                 inpkt = outpkt;
 163         }
 164
 165         /* Check the sequence number */
 166
 167         inpkt->len -= sizeof(inpkt->seqno);
 168         inpkt->seqno = ntohl(inpkt->seqno);
 169
 170         if(inpkt->seqno != n->received_seqno + 1) {
 171                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 172                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 173                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 174
 175                         memset(n->late, 0, sizeof(n->late));
 176                 } else if (inpkt->seqno <= n->received_seqno) {
 177                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 178                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 179                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 180                         } else
 181                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 182                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 183                 }
 184         }
 185
 186         n->received_seqno = inpkt->seqno;
 187         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 188
 189         if(n->received_seqno > MAX_SEQNO)
 190                 keyexpires = 0;
 191
 192         /* Decompress the packet */
 193
 194         if(myself->compression) {
 195                 outpkt = pkt[nextpkt++];
 196
 197                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 198                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 199                                                  n->name, n->hostname);
 200                         return;
 201                 }
 202
 203                 inpkt = outpkt;
 204         }
 205
 206         if(n->connection)
 207                 n->connection->last_ping_time = now;
 208
 209         receive_packet(n, inpkt);
 210 }
 211
 212 void receive_tcppacket(connection_t *c, char *buffer, int len)
 213 {
 214         vpn_packet_t outpkt;
 215
 216         cp();
 217
 218         outpkt.len = len;
 219         memcpy(outpkt.data, buffer, len);
 220
 221         receive_packet(c->node, &outpkt);
 222 }
 223
 224 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 225 {
 226         vpn_packet_t pkt1, pkt2;
 227         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 228         int nextpkt = 0;
 229         vpn_packet_t *outpkt;
 230         int origlen;
 231         int outlen, outpad;
 232         vpn_packet_t *copy;
 233         static int priority = 0;
 234         int origpriority;
 235         int sock;
 236
 237         cp();
 238
 239         /* Make sure we have a valid key */
 240
 241         if(!n->status.validkey) {
 242                 ifdebug(TRAFFIC) logger(LOG_INFO,
 243                                    _("No valid key known yet for %s (%s), queueing packet"),
 244                                    n->name, n->hostname);
 245
 246                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 247
 248                 copy = xmalloc(sizeof(vpn_packet_t));
 249                 memcpy(copy, inpkt, sizeof(vpn_packet_t));
 250
 251                 list_insert_tail(n->queue, copy);
 252
 253                 if(n->queue->count > MAXQUEUELENGTH)
 254                         list_delete_head(n->queue);
 255
 256                 if(!n->status.waitingforkey)
 257                         send_req_key(n->nexthop->connection, myself, n);
 258
 259                 n->status.waitingforkey = true;
 260
 261                 return;
 262         }
 263
 264         origlen = inpkt->len;
 265         origpriority = inpkt->priority;
 266
 267         /* Compress the packet */
 268
 269         if(n->compression) {
 270                 outpkt = pkt[nextpkt++];
 271
 272                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 273                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 274                                    n->name, n->hostname);
 275                         return;
 276                 }
 277
 278                 inpkt = outpkt;
 279         }
 280
 281         /* Add sequence number */
 282
 283         inpkt->seqno = htonl(++(n->sent_seqno));
 284         inpkt->len += sizeof(inpkt->seqno);
 285
 286         /* Encrypt the packet */
 287
 288         if(n->cipher) {
 289                 outpkt = pkt[nextpkt++];
 290
 291                 EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL);
 292                 if(!EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 293                                         (char *) &inpkt->seqno, inpkt->len)) {
 294                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 295                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 296                         return;
 297                 }
 298                 if(!EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 299                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 300                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 301                         return;
 302                 }
 303
 304                 outpkt->len = outlen + outpad;
 305                 inpkt = outpkt;
 306         }
 307
 308         /* Add the message authentication code */
 309
 310         if(n->digest && n->maclength) {
 311                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 312                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 313                 inpkt->len += n->maclength;
 314         }
 315
 316         /* Determine which socket we have to use */
 317
 318         for(sock = 0; sock < listen_sockets; sock++)
 319                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 320                         break;
 321
 322         if(sock >= listen_sockets)
 323                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 324
 325         /* Send the packet */
 326
 327 #if defined(SOL_IP) && defined(IP_TOS)
 328         if(priorityinheritance && origpriority != priority
 329            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 330                 priority = origpriority;
 331                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 332                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 333                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 334         }
 335 #endif
 336
 337         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 338                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 339                 return;
 340         }
 341
 342         inpkt->len = origlen;
 343 }
 344
 345 /*
 346   send a packet to the given vpn ip.
 347 */
 348 void send_packet(const node_t *n, vpn_packet_t *packet)
 349 {
 350         node_t *via;
 351
 352         cp();
 353
 354         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 355                            packet->len, n->name, n->hostname);
 356
 357         if(n == myself) {
 358                 ifdebug(TRAFFIC) logger(LOG_NOTICE, _("Packet is looping back to us!"));
 359                 return;
 360         }
 361
 362         if(!n->status.reachable) {
 363                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 364                                    n->name, n->hostname);
 365                 return;
 366         }
 367
 368         via = (n->via == myself) ? n->nexthop : n->via;
 369
 370         if(via != n)
 371                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 372                            n->name, via->name, n->via->hostname);
 373
 374         if((myself->options | via->options) & OPTION_TCPONLY) {
 375                 if(!send_tcppacket(via->connection, packet))
 376                         terminate_connection(via->connection, true);
 377         } else
 378                 send_udppacket(via, packet);
 379 }
 380
 381 /* Broadcast a packet using the minimum spanning tree */
 382
 383 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 384 {
 385         avl_node_t *node;
 386         connection_t *c;
 387
 388         cp();
 389
 390         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 391                            packet->len, from->name, from->hostname);
 392
 393         for(node = connection_tree->head; node; node = node->next) {
 394                 c = node->data;
 395
 396                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 397                         send_packet(c->node, packet);
 398         }
 399 }
 400
 401 void flush_queue(node_t *n)
 402 {
 403         list_node_t *node, *next;
 404
 405         cp();
 406
 407         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 408
 409         for(node = n->queue->head; node; node = next) {
 410                 next = node->next;
 411                 send_udppacket(n, node->data);
 412                 list_delete_node(n->queue, node);
 413         }
 414 }
 415
 416 void handle_incoming_vpn_data(int sock)
 417 {
 418         vpn_packet_t pkt;
 419         char *hostname;
 420         sockaddr_t from;
 421         socklen_t fromlen = sizeof(from);
 422         node_t *n;
 423
 424         cp();
 425
 426         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 427
 428         if(pkt.len < 0) {
 429                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 430                 return;
 431         }
 432
 433         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 434
 435         n = lookup_node_udp(&from);
 436
 437         if(!n) {
 438                 hostname = sockaddr2hostname(&from);
 439                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 440                            hostname);
 441                 free(hostname);
 442                 return;
 443         }
 444
 445         receive_udppacket(n, &pkt);
 446 }