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 1.1.2.46 2003/12/20 21:09:33 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 static void send_udppacket(node_t *, vpn_packet_t *);
  56
  57 #define MAX_SEQNO 1073741824
  58
  59 void send_mtu_probe(node_t *n)
  60 {
  61         vpn_packet_t packet;
  62         int len, i;
  63
  64         cp();
  65
  66         n->mtuprobes++;
  67
  68         if(n->mtuprobes >= 10 && !n->probedmtu) {
  69                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  70                 return;
  71         }
  72
  73         for(i = 0; i < 3; i++) {
  74                 if(n->mtuprobes >= 30 || n->probedmtu >= n->mtu) {
  75                         n->mtu = n->probedmtu;
  76                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  77                         return;
  78                 }
  79
  80                 len = n->probedmtu + 1 + random() % (n->mtu - n->probedmtu);
  81                 if(len < 64)
  82                         len = 64;
  83
  84                 memset(packet.data, 0, 14);
  85                 RAND_pseudo_bytes(packet.data + 14, len - 14);
  86                 packet.len = len;
  87
  88                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
  89
  90                 send_udppacket(n, &packet);
  91         }
  92
  93         n->mtuevent = xmalloc(sizeof(*n->mtuevent));
  94         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
  95         n->mtuevent->data = n;
  96         n->mtuevent->time = now + 1;
  97         event_add(n->mtuevent);
  98 }
  99
 100 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 101         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 102
 103         if(!packet->data[0]) {
 104                 packet->data[0] = 1;
 105                 send_packet(n, packet);
 106         } else {
 107                 if(n->probedmtu < packet->len)
 108                         n->probedmtu = packet->len;
 109         }
 110 }
 111
 112 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 113 {
 114         if(level == 10) {
 115                 lzo_uint lzolen = MAXSIZE;
 116                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 117                 return lzolen;
 118         } else if(level < 10) {
 119                 unsigned long destlen = MAXSIZE;
 120                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 121                         return destlen;
 122                 else
 123                         return -1;
 124         } else {
 125                 lzo_uint lzolen = MAXSIZE;
 126                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 127                 return lzolen;
 128         }
 129
 130         return -1;
 131 }
 132
 133 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 134 {
 135         if(level > 9) {
 136                 lzo_uint lzolen = MAXSIZE;
 137                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 138                         return lzolen;
 139                 else
 140                         return -1;
 141         } else {
 142                 unsigned long destlen = MAXSIZE;
 143                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 144                         return destlen;
 145                 else
 146                         return -1;
 147         }
 148
 149         return -1;
 150 }
 151
 152 /* VPN packet I/O */
 153
 154 static void receive_packet(node_t *n, vpn_packet_t *packet)
 155 {
 156         cp();
 157
 158         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 159                            packet->len, n->name, n->hostname);
 160
 161         route(n, packet);
 162 }
 163
 164 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 165 {
 166         vpn_packet_t pkt1, pkt2;
 167         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 168         int nextpkt = 0;
 169         vpn_packet_t *outpkt = pkt[0];
 170         int outlen, outpad;
 171         char hmac[EVP_MAX_MD_SIZE];
 172         int i;
 173
 174         cp();
 175
 176         /* Check packet length */
 177
 178         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 179                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 180                                         n->name, n->hostname);
 181                 return;
 182         }
 183
 184         /* Check the message authentication code */
 185
 186         if(myself->digest && myself->maclength) {
 187                 inpkt->len -= myself->maclength;
 188                 HMAC(myself->digest, myself->key, myself->keylength,
 189                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 190
 191                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 192                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 193                                            n->name, n->hostname);
 194                         return;
 195                 }
 196         }
 197
 198         /* Decrypt the packet */
 199
 200         if(myself->cipher) {
 201                 outpkt = pkt[nextpkt++];
 202
 203                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
 204                                 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 205                                         (char *) &inpkt->seqno, inpkt->len)
 206                                 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 207                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 208                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 209                         return;
 210                 }
 211
 212                 outpkt->len = outlen + outpad;
 213                 inpkt = outpkt;
 214         }
 215
 216         /* Check the sequence number */
 217
 218         inpkt->len -= sizeof(inpkt->seqno);
 219         inpkt->seqno = ntohl(inpkt->seqno);
 220
 221         if(inpkt->seqno != n->received_seqno + 1) {
 222                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 223                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 224                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 225
 226                         memset(n->late, 0, sizeof(n->late));
 227                 } else if (inpkt->seqno <= n->received_seqno) {
 228                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 229                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 230                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 231                         } else
 232                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 233                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 234                 }
 235         }
 236
 237         n->received_seqno = inpkt->seqno;
 238         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 239
 240         if(n->received_seqno > MAX_SEQNO)
 241                 keyexpires = 0;
 242
 243         /* Decompress the packet */
 244
 245         if(myself->compression) {
 246                 outpkt = pkt[nextpkt++];
 247
 248                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 249                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 250                                                  n->name, n->hostname);
 251                         return;
 252                 }
 253
 254                 inpkt = outpkt;
 255         }
 256
 257         if(n->connection)
 258                 n->connection->last_ping_time = now;
 259
 260         if(!inpkt->data[12] && !inpkt->data[13])
 261                 mtu_probe_h(n, inpkt);
 262         else
 263                 receive_packet(n, inpkt);
 264 }
 265
 266 void receive_tcppacket(connection_t *c, char *buffer, int len)
 267 {
 268         vpn_packet_t outpkt;
 269
 270         cp();
 271
 272         outpkt.len = len;
 273         memcpy(outpkt.data, buffer, len);
 274
 275         receive_packet(c->node, &outpkt);
 276 }
 277
 278 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 279 {
 280         vpn_packet_t pkt1, pkt2;
 281         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 282         int nextpkt = 0;
 283         vpn_packet_t *outpkt;
 284         int origlen;
 285         int outlen, outpad;
 286         vpn_packet_t *copy;
 287         static int priority = 0;
 288         int origpriority;
 289         int sock;
 290
 291         cp();
 292
 293         /* Make sure we have a valid key */
 294
 295         if(!n->status.validkey) {
 296                 ifdebug(TRAFFIC) logger(LOG_INFO,
 297                                    _("No valid key known yet for %s (%s), queueing packet"),
 298                                    n->name, n->hostname);
 299
 300                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 301
 302                 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
 303
 304                 list_insert_tail(n->queue, copy);
 305
 306                 if(n->queue->count > MAXQUEUELENGTH)
 307                         list_delete_head(n->queue);
 308
 309                 if(!n->status.waitingforkey)
 310                         send_req_key(n->nexthop->connection, myself, n);
 311
 312                 n->status.waitingforkey = true;
 313
 314                 return;
 315         }
 316
 317         origlen = inpkt->len;
 318         origpriority = inpkt->priority;
 319
 320         /* Compress the packet */
 321
 322         if(n->compression) {
 323                 outpkt = pkt[nextpkt++];
 324
 325                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 326                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 327                                    n->name, n->hostname);
 328                         return;
 329                 }
 330
 331                 inpkt = outpkt;
 332         }
 333
 334         /* Add sequence number */
 335
 336         inpkt->seqno = htonl(++(n->sent_seqno));
 337         inpkt->len += sizeof(inpkt->seqno);
 338
 339         /* Encrypt the packet */
 340
 341         if(n->cipher) {
 342                 outpkt = pkt[nextpkt++];
 343
 344                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
 345                                 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 346                                         (char *) &inpkt->seqno, inpkt->len)
 347                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 348                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 349                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 350                         return;
 351                 }
 352
 353                 outpkt->len = outlen + outpad;
 354                 inpkt = outpkt;
 355         }
 356
 357         /* Add the message authentication code */
 358
 359         if(n->digest && n->maclength) {
 360                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 361                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 362                 inpkt->len += n->maclength;
 363         }
 364
 365         /* Determine which socket we have to use */
 366
 367         for(sock = 0; sock < listen_sockets; sock++)
 368                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 369                         break;
 370
 371         if(sock >= listen_sockets)
 372                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 373
 374         /* Send the packet */
 375
 376 #if defined(SOL_IP) && defined(IP_TOS)
 377         if(priorityinheritance && origpriority != priority
 378            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 379                 priority = origpriority;
 380                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 381                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 382                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 383         }
 384 #endif
 385
 386         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 387                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 388                 if(errno == EMSGSIZE) {
 389                         if(n->mtu >= origlen)
 390                                 n->mtu = origlen - 1;
 391                 }
 392                 return;
 393         }
 394
 395         inpkt->len = origlen;
 396 }
 397
 398 /*
 399   send a packet to the given vpn ip.
 400 */
 401 void send_packet(const node_t *n, vpn_packet_t *packet)
 402 {
 403         node_t *via;
 404
 405         cp();
 406
 407         if(n == myself) {
 408                 write_packet(packet);
 409                 return;
 410         }
 411
 412         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 413                            packet->len, n->name, n->hostname);
 414
 415         if(!n->status.reachable) {
 416                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 417                                    n->name, n->hostname);
 418                 return;
 419         }
 420
 421         via = (n->via == myself) ? n->nexthop : n->via;
 422
 423         if(via != n)
 424                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 425                            n->name, via->name, n->via->hostname);
 426
 427         if((myself->options | via->options) & OPTION_TCPONLY) {
 428                 if(!send_tcppacket(via->connection, packet))
 429                         terminate_connection(via->connection, true);
 430         } else
 431                 send_udppacket(via, packet);
 432 }
 433
 434 /* Broadcast a packet using the minimum spanning tree */
 435
 436 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 437 {
 438         avl_node_t *node;
 439         connection_t *c;
 440
 441         cp();
 442
 443         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 444                            packet->len, from->name, from->hostname);
 445
 446         for(node = connection_tree->head; node; node = node->next) {
 447                 c = node->data;
 448
 449                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 450                         send_packet(c->node, packet);
 451         }
 452 }
 453
 454 void flush_queue(node_t *n)
 455 {
 456         list_node_t *node, *next;
 457
 458         cp();
 459
 460         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 461
 462         for(node = n->queue->head; node; node = next) {
 463                 next = node->next;
 464                 send_udppacket(n, node->data);
 465                 list_delete_node(n->queue, node);
 466         }
 467 }
 468
 469 void handle_incoming_vpn_data(int sock)
 470 {
 471         vpn_packet_t pkt;
 472         char *hostname;
 473         sockaddr_t from;
 474         socklen_t fromlen = sizeof(from);
 475         node_t *n;
 476
 477         cp();
 478
 479         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 480
 481         if(pkt.len < 0) {
 482                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 483                 return;
 484         }
 485
 486         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 487
 488         n = lookup_node_udp(&from);
 489
 490         if(!n) {
 491                 hostname = sockaddr2hostname(&from);
 492                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 493                            hostname);
 494                 free(hostname);
 495                 return;
 496         }
 497
 498         receive_udppacket(n, &pkt);
 499 }