git.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 1.1.2.43 2003/10/11 12:16:12 guus Exp $
  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 #include <lzo1x.h>
  33
  34 #include "avl_tree.h"
  35 #include "conf.h"
  36 #include "connection.h"
  37 #include "device.h"
  38 #include "event.h"
  39 #include "graph.h"
  40 #include "list.h"
  41 #include "logger.h"
  42 #include "net.h"
  43 #include "netutl.h"
  44 #include "protocol.h"
  45 #include "process.h"
  46 #include "route.h"
  47 #include "utils.h"
  48 #include "xalloc.h"
  49
  50 int keylifetime = 0;
  51 int keyexpires = 0;
  52 EVP_CIPHER_CTX packet_ctx;
  53 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  54
  55
  56 #define MAX_SEQNO 1073741824
  57
  58 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
  59 {
  60         if(level == 10) {
  61                 lzo_uint lzolen = MAXSIZE;
  62                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
  63                 return lzolen;
  64         } else if(level < 10) {
  65                 unsigned long destlen = MAXSIZE;
  66                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
  67                         return destlen;
  68                 else
  69                         return -1;
  70         } else {
  71                 lzo_uint lzolen = MAXSIZE;
  72                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
  73                 return lzolen;
  74         }
  75
  76         return -1;
  77 }
  78
  79 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
  80 {
  81         if(level > 9) {
  82                 lzo_uint lzolen = MAXSIZE;
  83                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
  84                         return lzolen;
  85                 else
  86                         return -1;
  87         } else {
  88                 unsigned long destlen = MAXSIZE;
  89                 if(uncompress(dest, &destlen, source, len) == Z_OK)
  90                         return destlen;
  91                 else
  92                         return -1;
  93         }
  94
  95         return -1;
  96 }
  97
  98 /* VPN packet I/O */
  99
 100 static void receive_packet(node_t *n, vpn_packet_t *packet)
 101 {
 102         cp();
 103
 104         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 105                            packet->len, n->name, n->hostname);
 106
 107         route_incoming(n, packet);
 108 }
 109
 110 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 111 {
 112         vpn_packet_t pkt1, pkt2;
 113         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 114         int nextpkt = 0;
 115         vpn_packet_t *outpkt = pkt[0];
 116         int outlen, outpad;
 117         char hmac[EVP_MAX_MD_SIZE];
 118         int i;
 119
 120         cp();
 121
 122         /* Check packet length */
 123
 124         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 125                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 126                                         n->name, n->hostname);
 127                 return;
 128         }
 129
 130         /* Check the message authentication code */
 131
 132         if(myself->digest && myself->maclength) {
 133                 inpkt->len -= myself->maclength;
 134                 HMAC(myself->digest, myself->key, myself->keylength,
 135                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 136
 137                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 138                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 139                                            n->name, n->hostname);
 140                         return;
 141                 }
 142         }
 143
 144         /* Decrypt the packet */
 145
 146         if(myself->cipher) {
 147                 outpkt = pkt[nextpkt++];
 148
 149                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
 150                                 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 151                                         (char *) &inpkt->seqno, inpkt->len)
 152                                 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 153                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 154                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 155                         return;
 156                 }
 157
 158                 outpkt->len = outlen + outpad;
 159                 inpkt = outpkt;
 160         }
 161
 162         /* Check the sequence number */
 163
 164         inpkt->len -= sizeof(inpkt->seqno);
 165         inpkt->seqno = ntohl(inpkt->seqno);
 166
 167         if(inpkt->seqno != n->received_seqno + 1) {
 168                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 169                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 170                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 171
 172                         memset(n->late, 0, sizeof(n->late));
 173                 } else if (inpkt->seqno <= n->received_seqno) {
 174                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 175                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 176                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 177                         } else
 178                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 179                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 180                 }
 181         }
 182
 183         n->received_seqno = inpkt->seqno;
 184         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 185
 186         if(n->received_seqno > MAX_SEQNO)
 187                 keyexpires = 0;
 188
 189         /* Decompress the packet */
 190
 191         if(myself->compression) {
 192                 outpkt = pkt[nextpkt++];
 193
 194                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 195                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 196                                                  n->name, n->hostname);
 197                         return;
 198                 }
 199
 200                 inpkt = outpkt;
 201         }
 202
 203         if(n->connection)
 204                 n->connection->last_ping_time = now;
 205
 206         receive_packet(n, inpkt);
 207 }
 208
 209 void receive_tcppacket(connection_t *c, char *buffer, int len)
 210 {
 211         vpn_packet_t outpkt;
 212
 213         cp();
 214
 215         outpkt.len = len;
 216         memcpy(outpkt.data, buffer, len);
 217
 218         receive_packet(c->node, &outpkt);
 219 }
 220
 221 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 222 {
 223         vpn_packet_t pkt1, pkt2;
 224         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 225         int nextpkt = 0;
 226         vpn_packet_t *outpkt;
 227         int origlen;
 228         int outlen, outpad;
 229         vpn_packet_t *copy;
 230         static int priority = 0;
 231         int origpriority;
 232         int sock;
 233
 234         cp();
 235
 236         /* Make sure we have a valid key */
 237
 238         if(!n->status.validkey) {
 239                 ifdebug(TRAFFIC) logger(LOG_INFO,
 240                                    _("No valid key known yet for %s (%s), queueing packet"),
 241                                    n->name, n->hostname);
 242
 243                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 244
 245                 copy = xmalloc(sizeof(vpn_packet_t));
 246                 memcpy(copy, inpkt, sizeof(vpn_packet_t));
 247
 248                 list_insert_tail(n->queue, copy);
 249
 250                 if(n->queue->count > MAXQUEUELENGTH)
 251                         list_delete_head(n->queue);
 252
 253                 if(!n->status.waitingforkey)
 254                         send_req_key(n->nexthop->connection, myself, n);
 255
 256                 n->status.waitingforkey = true;
 257
 258                 return;
 259         }
 260
 261         origlen = inpkt->len;
 262         origpriority = inpkt->priority;
 263
 264         /* Compress the packet */
 265
 266         if(n->compression) {
 267                 outpkt = pkt[nextpkt++];
 268
 269                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 270                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 271                                    n->name, n->hostname);
 272                         return;
 273                 }
 274
 275                 inpkt = outpkt;
 276         }
 277
 278         /* Add sequence number */
 279
 280         inpkt->seqno = htonl(++(n->sent_seqno));
 281         inpkt->len += sizeof(inpkt->seqno);
 282
 283         /* Encrypt the packet */
 284
 285         if(n->cipher) {
 286                 outpkt = pkt[nextpkt++];
 287
 288                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
 289                                 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 290                                         (char *) &inpkt->seqno, inpkt->len)
 291                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 292                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 293                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 294                         return;
 295                 }
 296
 297                 outpkt->len = outlen + outpad;
 298                 inpkt = outpkt;
 299         }
 300
 301         /* Add the message authentication code */
 302
 303         if(n->digest && n->maclength) {
 304                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 305                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 306                 inpkt->len += n->maclength;
 307         }
 308
 309         /* Determine which socket we have to use */
 310
 311         for(sock = 0; sock < listen_sockets; sock++)
 312                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 313                         break;
 314
 315         if(sock >= listen_sockets)
 316                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 317
 318         /* Send the packet */
 319
 320 #if defined(SOL_IP) && defined(IP_TOS)
 321         if(priorityinheritance && origpriority != priority
 322            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 323                 priority = origpriority;
 324                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 325                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 326                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 327         }
 328 #endif
 329
 330         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 331                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 332                 return;
 333         }
 334
 335         inpkt->len = origlen;
 336 }
 337
 338 /*
 339   send a packet to the given vpn ip.
 340 */
 341 void send_packet(const node_t *n, vpn_packet_t *packet)
 342 {
 343         node_t *via;
 344
 345         cp();
 346
 347         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 348                            packet->len, n->name, n->hostname);
 349
 350         if(n == myself) {
 351                 ifdebug(TRAFFIC) logger(LOG_NOTICE, _("Packet is looping back to us!"));
 352                 return;
 353         }
 354
 355         if(!n->status.reachable) {
 356                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 357                                    n->name, n->hostname);
 358                 return;
 359         }
 360
 361         via = (n->via == myself) ? n->nexthop : n->via;
 362
 363         if(via != n)
 364                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 365                            n->name, via->name, n->via->hostname);
 366
 367         if((myself->options | via->options) & OPTION_TCPONLY) {
 368                 if(!send_tcppacket(via->connection, packet))
 369                         terminate_connection(via->connection, true);
 370         } else
 371                 send_udppacket(via, packet);
 372 }
 373
 374 /* Broadcast a packet using the minimum spanning tree */
 375
 376 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 377 {
 378         avl_node_t *node;
 379         connection_t *c;
 380
 381         cp();
 382
 383         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 384                            packet->len, from->name, from->hostname);
 385
 386         for(node = connection_tree->head; node; node = node->next) {
 387                 c = node->data;
 388
 389                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 390                         send_packet(c->node, packet);
 391         }
 392 }
 393
 394 void flush_queue(node_t *n)
 395 {
 396         list_node_t *node, *next;
 397
 398         cp();
 399
 400         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 401
 402         for(node = n->queue->head; node; node = next) {
 403                 next = node->next;
 404                 send_udppacket(n, node->data);
 405                 list_delete_node(n->queue, node);
 406         }
 407 }
 408
 409 void handle_incoming_vpn_data(int sock)
 410 {
 411         vpn_packet_t pkt;
 412         char *hostname;
 413         sockaddr_t from;
 414         socklen_t fromlen = sizeof(from);
 415         node_t *n;
 416
 417         cp();
 418
 419         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 420
 421         if(pkt.len < 0) {
 422                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 423                 return;
 424         }
 425
 426         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 427
 428         n = lookup_node_udp(&from);
 429
 430         if(!n) {
 431                 hostname = sockaddr2hostname(&from);
 432                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 433                            hostname);
 434                 free(hostname);
 435                 return;
 436         }
 437
 438         receive_udppacket(n, &pkt);
 439 }