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 1.1.2.33 2003/07/12 17:41:46 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 <unistd.h>
  36 #include <sys/ioctl.h>
  37 /* SunOS really wants sys/socket.h BEFORE net/if.h,
  38    and FreeBSD wants these lines below the rest. */
  39 #include <arpa/inet.h>
  40 #include <sys/socket.h>
  41 #include <net/if.h>
  42 #ifdef HAVE_NETINET_IN_SYSTM_H
  43 #include <netinet/in_systm.h>
  44 #endif
  45 #ifdef HAVE_NETINET_IP_H
  46 #include <netinet/ip.h>
  47 #endif
  48 #ifdef HAVE_NETINET_TCP_H
  49 #include <netinet/tcp.h>
  50 #endif
  51
  52 #include <openssl/rand.h>
  53 #include <openssl/evp.h>
  54 #include <openssl/pem.h>
  55 #include <openssl/hmac.h>
  56
  57 #include <zlib.h>
  58 #include <lzo1x.h>
  59
  60 #include <utils.h>
  61 #include <xalloc.h>
  62 #include <avl_tree.h>
  63 #include <list.h>
  64
  65 #include "conf.h"
  66 #include "connection.h"
  67 #include "meta.h"
  68 #include "net.h"
  69 #include "netutl.h"
  70 #include "process.h"
  71 #include "protocol.h"
  72 #include "subnet.h"
  73 #include "graph.h"
  74 #include "process.h"
  75 #include "route.h"
  76 #include "device.h"
  77 #include "event.h"
  78 #include "logger.h"
  79
  80 #include "system.h"
  81
  82 int keylifetime = 0;
  83 int keyexpires = 0;
  84 EVP_CIPHER_CTX packet_ctx;
  85 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  86
  87
  88 #define MAX_SEQNO 1073741824
  89
  90 static 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 = MAXSIZE;
  94                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
  95                 return lzolen;
  96         } else if(level < 10) {
  97                 unsigned long destlen = MAXSIZE;
  98                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
  99                         return destlen;
 100                 else
 101                         return -1;
 102         } else {
 103                 lzo_uint lzolen = MAXSIZE;
 104                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 105                 return lzolen;
 106         }
 107
 108         return -1;
 109 }
 110
 111 static 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 = MAXSIZE;
 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 = MAXSIZE;
 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 static void receive_packet(node_t *n, vpn_packet_t *packet)
 133 {
 134         cp();
 135
 136         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 137                            packet->len, n->name, n->hostname);
 138
 139         route_incoming(n, packet);
 140 }
 141
 142 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 143 {
 144         vpn_packet_t pkt1, pkt2;
 145         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 146         int nextpkt = 0;
 147         vpn_packet_t *outpkt = pkt[0];
 148         int outlen, outpad;
 149         char hmac[EVP_MAX_MD_SIZE];
 150         int i;
 151
 152         cp();
 153
 154         /* Check the message authentication code */
 155
 156         if(myself->digest && myself->maclength) {
 157                 inpkt->len -= myself->maclength;
 158                 HMAC(myself->digest, myself->key, myself->keylength,
 159                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 160
 161                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 162                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 163                                            n->name, n->hostname);
 164                         return;
 165                 }
 166         }
 167
 168         /* Decrypt the packet */
 169
 170         if(myself->cipher) {
 171                 outpkt = pkt[nextpkt++];
 172
 173 //              EVP_DecryptInit_ex(&packet_ctx, myself->cipher, NULL, myself->key,
 174 //                                              myself->key + myself->cipher->key_len);
 175                 EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL);
 176                 EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 177                                                   (char *) &inpkt->seqno, inpkt->len);
 178                 EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 179
 180                 outpkt->len = outlen + outpad;
 181                 inpkt = outpkt;
 182         }
 183
 184         /* Check the sequence number */
 185
 186         inpkt->len -= sizeof(inpkt->seqno);
 187         inpkt->seqno = ntohl(inpkt->seqno);
 188
 189         if(inpkt->seqno != n->received_seqno + 1) {
 190                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 191                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 192                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 193
 194                         memset(n->late, 0, sizeof(n->late));
 195                 } else if (inpkt->seqno <= n->received_seqno) {
 196                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 197                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 198                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 199                         } else
 200                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 201                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 202                 }
 203         }
 204
 205         n->received_seqno = inpkt->seqno;
 206         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 207
 208         if(n->received_seqno > MAX_SEQNO)
 209                 keyexpires = 0;
 210
 211         /* Decompress the packet */
 212
 213         if(myself->compression) {
 214                 outpkt = pkt[nextpkt++];
 215
 216                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 217                         logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 218                                    n->name, n->hostname);
 219                         return;
 220                 }
 221
 222                 inpkt = outpkt;
 223         }
 224
 225         receive_packet(n, inpkt);
 226 }
 227
 228 void receive_tcppacket(connection_t *c, char *buffer, int len)
 229 {
 230         vpn_packet_t outpkt;
 231
 232         cp();
 233
 234         outpkt.len = len;
 235         memcpy(outpkt.data, buffer, len);
 236
 237         receive_packet(c->node, &outpkt);
 238 }
 239
 240 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 241 {
 242         vpn_packet_t pkt1, pkt2;
 243         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 244         int nextpkt = 0;
 245         vpn_packet_t *outpkt;
 246         int origlen;
 247         int outlen, outpad;
 248         vpn_packet_t *copy;
 249         static int priority = 0;
 250         int origpriority;
 251         int sock;
 252
 253         cp();
 254
 255         /* Make sure we have a valid key */
 256
 257         if(!n->status.validkey) {
 258                 ifdebug(TRAFFIC) logger(LOG_INFO,
 259                                    _("No valid key known yet for %s (%s), queueing packet"),
 260                                    n->name, n->hostname);
 261
 262                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 263
 264                 copy = xmalloc(sizeof(vpn_packet_t));
 265                 memcpy(copy, inpkt, sizeof(vpn_packet_t));
 266
 267                 list_insert_tail(n->queue, copy);
 268
 269                 if(n->queue->count > MAXQUEUELENGTH)
 270                         list_delete_head(n->queue);
 271
 272                 if(!n->status.waitingforkey)
 273                         send_req_key(n->nexthop->connection, myself, n);
 274
 275                 n->status.waitingforkey = 1;
 276
 277                 return;
 278         }
 279
 280         origlen = inpkt->len;
 281         origpriority = inpkt->priority;
 282
 283         /* Compress the packet */
 284
 285         if(n->compression) {
 286                 outpkt = pkt[nextpkt++];
 287
 288                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 289                         logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 290                                    n->name, n->hostname);
 291                         return;
 292                 }
 293
 294                 inpkt = outpkt;
 295         }
 296
 297         /* Add sequence number */
 298
 299         inpkt->seqno = htonl(++(n->sent_seqno));
 300         inpkt->len += sizeof(inpkt->seqno);
 301
 302         /* Encrypt the packet */
 303
 304         if(n->cipher) {
 305                 outpkt = pkt[nextpkt++];
 306
 307 //              EVP_EncryptInit_ex(&packet_ctx, n->cipher, NULL, n->key, n->key + n->cipher->key_len);
 308                 EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL);
 309                 EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 310                                                   (char *) &inpkt->seqno, inpkt->len);
 311                 EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad);
 312
 313                 outpkt->len = outlen + outpad;
 314                 inpkt = outpkt;
 315         }
 316
 317         /* Add the message authentication code */
 318
 319         if(n->digest && n->maclength) {
 320                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 321                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 322                 inpkt->len += n->maclength;
 323         }
 324
 325         /* Determine which socket we have to use */
 326
 327         for(sock = 0; sock < listen_sockets; sock++)
 328                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 329                         break;
 330
 331         if(sock >= listen_sockets)
 332                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 333
 334         /* Send the packet */
 335
 336 #if defined(SOL_IP) && defined(IP_TOS)
 337         if(priorityinheritance && origpriority != priority
 338            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 339                 priority = origpriority;
 340                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 341                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 342                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt",
 343                                    strerror(errno));
 344         }
 345 #endif
 346
 347         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 348                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name,
 349                            n->hostname, strerror(errno));
 350                 return;
 351         }
 352
 353         inpkt->len = origlen;
 354 }
 355
 356 /*
 357   send a packet to the given vpn ip.
 358 */
 359 void send_packet(node_t *n, vpn_packet_t *packet)
 360 {
 361         node_t *via;
 362
 363         cp();
 364
 365         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 366                            packet->len, n->name, n->hostname);
 367
 368         if(n == myself) {
 369                 ifdebug(TRAFFIC) logger(LOG_NOTICE, _("Packet is looping back to us!"));
 370                 return;
 371         }
 372
 373         if(!n->status.reachable) {
 374                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 375                                    n->name, n->hostname);
 376                 return;
 377         }
 378
 379         via = (n->via == myself) ? n->nexthop : n->via;
 380
 381         if(via != n)
 382                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 383                            n->name, via->name, n->via->hostname);
 384
 385         if((myself->options | via->options) & OPTION_TCPONLY) {
 386                 if(send_tcppacket(via->connection, packet))
 387                         terminate_connection(via->connection, 1);
 388         } else
 389                 send_udppacket(via, packet);
 390 }
 391
 392 /* Broadcast a packet using the minimum spanning tree */
 393
 394 void broadcast_packet(node_t *from, vpn_packet_t *packet)
 395 {
 396         avl_node_t *node;
 397         connection_t *c;
 398
 399         cp();
 400
 401         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 402                            packet->len, from->name, from->hostname);
 403
 404         for(node = connection_tree->head; node; node = node->next) {
 405                 c = (connection_t *) node->data;
 406
 407                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 408                         send_packet(c->node, packet);
 409         }
 410 }
 411
 412 void flush_queue(node_t *n)
 413 {
 414         list_node_t *node, *next;
 415
 416         cp();
 417
 418         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 419
 420         for(node = n->queue->head; node; node = next) {
 421                 next = node->next;
 422                 send_udppacket(n, (vpn_packet_t *) node->data);
 423                 list_delete_node(n->queue, node);
 424         }
 425 }
 426
 427 void handle_incoming_vpn_data(int sock)
 428 {
 429         vpn_packet_t pkt;
 430         int x, l = sizeof(x);
 431         char *hostname;
 432         sockaddr_t from;
 433         socklen_t fromlen = sizeof(from);
 434         node_t *n;
 435
 436         cp();
 437
 438         if(getsockopt(sock, SOL_SOCKET, SO_ERROR, &x, &l) < 0) {
 439                 logger(LOG_ERR, _("This is a bug: %s:%d: %d:%s"),
 440                            __FILE__, __LINE__, sock, strerror(errno));
 441                 cp_trace();
 442                 exit(1);
 443         }
 444
 445         if(x) {
 446                 logger(LOG_ERR, _("Incoming data socket error: %s"), strerror(x));
 447                 return;
 448         }
 449
 450         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 451
 452         if(pkt.len <= 0) {
 453                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 454                 return;
 455         }
 456
 457         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 458
 459         n = lookup_node_udp(&from);
 460
 461         if(!n) {
 462                 hostname = sockaddr2hostname(&from);
 463                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 464                            hostname);
 465                 free(hostname);
 466                 return;
 467         }
 468
 469         if(n->connection)
 470                 n->connection->last_ping_time = now;
 471
 472         receive_udppacket(n, &pkt);
 473 }