git.meshlink.io Git - meshlink/blob - src/net_packet.c

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2009 Guus Sliepen <guus@tinc-vpn.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     $Id$
  21 */
  22
  23 #include "system.h"
  24
  25 #include <zlib.h>
  26 #include LZO1X_H
  27
  28 #include "splay_tree.h"
  29 #include "cipher.h"
  30 #include "conf.h"
  31 #include "connection.h"
  32 #include "crypto.h"
  33 #include "digest.h"
  34 #include "device.h"
  35 #include "ethernet.h"
  36 #include "graph.h"
  37 #include "list.h"
  38 #include "logger.h"
  39 #include "net.h"
  40 #include "netutl.h"
  41 #include "protocol.h"
  42 #include "process.h"
  43 #include "route.h"
  44 #include "utils.h"
  45 #include "xalloc.h"
  46
  47 #ifdef WSAEMSGSIZE
  48 #define EMSGSIZE WSAEMSGSIZE
  49 #endif
  50
  51 int keylifetime = 0;
  52 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  53
  54 static void send_udppacket(node_t *, vpn_packet_t *);
  55
  56 #define MAX_SEQNO 1073741824
  57
  58 static void send_mtu_probe_handler(int fd, short events, void *data) {
  59         node_t *n = data;
  60         vpn_packet_t packet;
  61         int len, i;
  62
  63         cp();
  64
  65         n->mtuprobes++;
  66
  67         if(n->mtuprobes >= 10 && !n->minmtu) {
  68                 ifdebug(TRAFFIC) logger(LOG_INFO, _("No response to MTU probes from %s (%s)"), n->name, n->hostname);
  69                 return;
  70         }
  71
  72         for(i = 0; i < 3; i++) {
  73                 if(n->mtuprobes >= 30 || n->minmtu >= n->maxmtu) {
  74                         n->mtu = n->minmtu;
  75                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  76                         return;
  77                 }
  78
  79                 len = n->minmtu + 1 + random() % (n->maxmtu - n->minmtu);
  80                 if(len < 64)
  81                         len = 64;
  82
  83                 memset(packet.data, 0, 14);
  84                 randomize(packet.data + 14, len - 14);
  85                 packet.len = len;
  86                 packet.priority = 0;
  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         event_add(&n->mtuevent, &(struct timeval){1, 0});
  94 }
  95
  96 void send_mtu_probe(node_t *n) {
  97         if(!timeout_initialized(&n->mtuevent))
  98                 timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
  99         send_mtu_probe_handler(0, 0, n);
 100 }
 101
 102 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 103         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 104
 105         if(!packet->data[0]) {
 106                 packet->data[0] = 1;
 107                 send_packet(n, packet);
 108         } else {
 109                 if(n->minmtu < packet->len)
 110                         n->minmtu = packet->len;
 111         }
 112 }
 113
 114 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 115         if(level == 10) {
 116                 lzo_uint lzolen = MAXSIZE;
 117                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 118                 return lzolen;
 119         } else if(level < 10) {
 120                 unsigned long destlen = MAXSIZE;
 121                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 122                         return destlen;
 123                 else
 124                         return -1;
 125         } else {
 126                 lzo_uint lzolen = MAXSIZE;
 127                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 128                 return lzolen;
 129         }
 130
 131         return -1;
 132 }
 133
 134 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 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         cp();
 156
 157         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 158                            packet->len, n->name, n->hostname);
 159
 160         route(n, packet);
 161 }
 162
 163 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 164         vpn_packet_t pkt1, pkt2;
 165         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 166         int nextpkt = 0;
 167         vpn_packet_t *outpkt = pkt[0];
 168         size_t outlen;
 169         int i;
 170
 171         cp();
 172
 173         /* Check packet length */
 174
 175         if(inpkt->len < sizeof inpkt->seqno + digest_length(&myself->digest)) {
 176                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 177                                         n->name, n->hostname);
 178                 return;
 179         }
 180
 181         /* Check the message authentication code */
 182
 183         if(digest_active(&myself->digest) && !digest_verify(&myself->digest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len)) {
 184                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
 185                 return;
 186         }
 187
 188         /* Decrypt the packet */
 189
 190         if(cipher_active(&myself->cipher)) {
 191                 outpkt = pkt[nextpkt++];
 192                 outlen = MAXSIZE;
 193
 194                 if(!cipher_decrypt(&myself->cipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 195                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s)"), n->name, n->hostname);
 196                         return;
 197                 }
 198
 199                 outpkt->len = outlen;
 200                 inpkt = outpkt;
 201         }
 202
 203         /* Check the sequence number */
 204
 205         inpkt->len -= sizeof inpkt->seqno;
 206         inpkt->seqno = ntohl(inpkt->seqno);
 207
 208         if(inpkt->seqno != n->received_seqno + 1) {
 209                 if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
 210                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 211                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 212
 213                         memset(n->late, 0, sizeof n->late);
 214                 } else if (inpkt->seqno <= n->received_seqno) {
 215                         if((n->received_seqno >= sizeof n->late * 8 && inpkt->seqno <= n->received_seqno - sizeof n->late * 8) || !(n->late[(inpkt->seqno / 8) % sizeof n->late] & (1 << inpkt->seqno % 8))) {
 216                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 217                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 218                                 return;
 219                         }
 220                 } else {
 221                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 222                                 n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
 223                 }
 224         }
 225
 226         n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
 227
 228         if(inpkt->seqno > n->received_seqno)
 229                 n->received_seqno = inpkt->seqno;
 230
 231         if(n->received_seqno > MAX_SEQNO)
 232                 regenerate_key();
 233
 234         /* Decompress the packet */
 235
 236         if(myself->compression) {
 237                 outpkt = pkt[nextpkt++];
 238
 239                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 240                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 241                                                  n->name, n->hostname);
 242                         return;
 243                 }
 244
 245                 inpkt = outpkt;
 246         }
 247
 248         inpkt->priority = 0;
 249
 250         if(!inpkt->data[12] && !inpkt->data[13])
 251                 mtu_probe_h(n, inpkt);
 252         else
 253                 receive_packet(n, inpkt);
 254 }
 255
 256 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 257         vpn_packet_t outpkt;
 258
 259         cp();
 260
 261         outpkt.len = len;
 262         if(c->options & OPTION_TCPONLY)
 263                 outpkt.priority = 0;
 264         else
 265                 outpkt.priority = -1;
 266         memcpy(outpkt.data, buffer, len);
 267
 268         receive_packet(c->node, &outpkt);
 269 }
 270
 271 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 272         vpn_packet_t pkt1, pkt2;
 273         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 274         vpn_packet_t *inpkt = origpkt;
 275         int nextpkt = 0;
 276         vpn_packet_t *outpkt;
 277         int origlen;
 278         size_t outlen;
 279         static int priority = 0;
 280         int origpriority;
 281         int sock;
 282
 283         cp();
 284
 285         /* Make sure we have a valid key */
 286
 287         if(!n->status.validkey) {
 288                 ifdebug(TRAFFIC) logger(LOG_INFO,
 289                                    _("No valid key known yet for %s (%s), forwarding via TCP"),
 290                                    n->name, n->hostname);
 291
 292                 if(!n->status.waitingforkey)
 293                         send_req_key(n->nexthop->connection, myself, n);
 294
 295                 n->status.waitingforkey = true;
 296
 297                 send_tcppacket(n->nexthop->connection, origpkt);
 298
 299                 return;
 300         }
 301
 302         if(!n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 303                 ifdebug(TRAFFIC) logger(LOG_INFO,
 304                                 _("No minimum MTU established yet for %s (%s), forwarding via TCP"),
 305                                 n->name, n->hostname);
 306
 307                 send_tcppacket(n->nexthop->connection, origpkt);
 308         }
 309
 310         origlen = inpkt->len;
 311         origpriority = inpkt->priority;
 312
 313         /* Compress the packet */
 314
 315         if(n->compression) {
 316                 outpkt = pkt[nextpkt++];
 317
 318                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 319                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 320                                    n->name, n->hostname);
 321                         return;
 322                 }
 323
 324                 inpkt = outpkt;
 325         }
 326
 327         /* Add sequence number */
 328
 329         inpkt->seqno = htonl(++(n->sent_seqno));
 330         inpkt->len += sizeof inpkt->seqno;
 331
 332         /* Encrypt the packet */
 333
 334         if(cipher_active(&n->cipher)) {
 335                 outpkt = pkt[nextpkt++];
 336                 outlen = MAXSIZE;
 337
 338                 if(!cipher_encrypt(&n->cipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 339                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s)"), n->name, n->hostname);
 340                         goto end;
 341                 }
 342
 343                 outpkt->len = outlen;
 344                 inpkt = outpkt;
 345         }
 346
 347         /* Add the message authentication code */
 348
 349         if(digest_active(&n->digest)) {
 350                 digest_create(&n->digest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len);
 351                 inpkt->len += digest_length(&n->digest);
 352         }
 353
 354         /* Determine which socket we have to use */
 355
 356         for(sock = 0; sock < listen_sockets; sock++)
 357                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 358                         break;
 359
 360         if(sock >= listen_sockets)
 361                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 362
 363         /* Send the packet */
 364
 365 #if defined(SOL_IP) && defined(IP_TOS)
 366         if(priorityinheritance && origpriority != priority
 367            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 368                 priority = origpriority;
 369                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 370                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority))     /* SO_PRIORITY doesn't seem to work */
 371                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 372         }
 373 #endif
 374
 375         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 376                 if(errno == EMSGSIZE) {
 377                         if(n->maxmtu >= origlen)
 378                                 n->maxmtu = origlen - 1;
 379                         if(n->mtu >= origlen)
 380                                 n->mtu = origlen - 1;
 381                 } else
 382                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 383         }
 384
 385 end:
 386         origpkt->len = origlen;
 387 }
 388
 389 /*
 390   send a packet to the given vpn ip.
 391 */
 392 void send_packet(const node_t *n, vpn_packet_t *packet) {
 393         node_t *via;
 394
 395         cp();
 396
 397         if(n == myself) {
 398                 if(overwrite_mac)
 399                          memcpy(packet->data, mymac.x, ETH_ALEN);
 400                 write_packet(packet);
 401                 return;
 402         }
 403
 404         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 405                            packet->len, n->name, n->hostname);
 406
 407         if(!n->status.reachable) {
 408                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 409                                    n->name, n->hostname);
 410                 return;
 411         }
 412
 413         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 414
 415         if(via != n)
 416                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending packet to %s via %s (%s)"),
 417                            n->name, via->name, n->via->hostname);
 418
 419         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 420                 if(!send_tcppacket(via->connection, packet))
 421                         terminate_connection(via->connection, true);
 422         } else
 423                 send_udppacket(via, packet);
 424 }
 425
 426 /* Broadcast a packet using the minimum spanning tree */
 427
 428 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 429         splay_node_t *node;
 430         connection_t *c;
 431
 432         cp();
 433
 434         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 435                            packet->len, from->name, from->hostname);
 436
 437         if(from != myself)
 438                 send_packet(myself, packet);
 439
 440         for(node = connection_tree->head; node; node = node->next) {
 441                 c = node->data;
 442
 443                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 444                         send_packet(c->node, packet);
 445         }
 446 }
 447
 448 void handle_incoming_vpn_data(int sock, short events, void *data)
 449 {
 450         vpn_packet_t pkt;
 451         char *hostname;
 452         sockaddr_t from;
 453         socklen_t fromlen = sizeof from;
 454         node_t *n;
 455
 456         cp();
 457
 458         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 459
 460         if(pkt.len < 0) {
 461                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 462                 return;
 463         }
 464
 465         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 466
 467         n = lookup_node_udp(&from);
 468
 469         if(!n) {
 470                 hostname = sockaddr2hostname(&from);
 471                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 472                            hostname);
 473                 free(hostname);
 474                 return;
 475         }
 476
 477         receive_udppacket(n, &pkt);
 478 }
 479
 480 void handle_device_data(int sock, short events, void *data) {
 481         vpn_packet_t packet;
 482
 483         if(read_packet(&packet))
 484                 route(myself, &packet);
 485 }