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                   2000-2006 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
  87                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
  88
  89                 send_udppacket(n, &packet);
  90         }
  91
  92         event_add(&n->mtuevent, &(struct timeval){1, 0});
  93 }
  94
  95 void send_mtu_probe(node_t *n) {
  96         if(!timeout_initialized(&n->mtuevent))
  97                 timeout_set(&n->mtuevent, send_mtu_probe_handler, n);
  98         send_mtu_probe_handler(0, 0, n);
  99 }
 100
 101 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
 102         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
 103
 104         if(!packet->data[0]) {
 105                 packet->data[0] = 1;
 106                 send_packet(n, packet);
 107         } else {
 108                 if(n->minmtu < packet->len)
 109                         n->minmtu = packet->len;
 110         }
 111 }
 112
 113 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 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         if(level > 9) {
 135                 lzo_uint lzolen = MAXSIZE;
 136                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 137                         return lzolen;
 138                 else
 139                         return -1;
 140         } else {
 141                 unsigned long destlen = MAXSIZE;
 142                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 143                         return destlen;
 144                 else
 145                         return -1;
 146         }
 147
 148         return -1;
 149 }
 150
 151 /* VPN packet I/O */
 152
 153 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 154         cp();
 155
 156         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 157                            packet->len, n->name, n->hostname);
 158
 159         route(n, packet);
 160 }
 161
 162 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 163         vpn_packet_t pkt1, pkt2;
 164         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 165         int nextpkt = 0;
 166         vpn_packet_t *outpkt = pkt[0];
 167         size_t outlen;
 168         int i;
 169
 170         cp();
 171
 172         /* Check packet length */
 173
 174         if(inpkt->len < sizeof inpkt->seqno + digest_length(&myself->digest)) {
 175                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 176                                         n->name, n->hostname);
 177                 return;
 178         }
 179
 180         /* Check the message authentication code */
 181
 182         if(digest_active(&myself->digest) && !digest_verify(&myself->digest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len)) {
 183                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"), n->name, n->hostname);
 184                 return;
 185         }
 186
 187         /* Decrypt the packet */
 188
 189         if(cipher_active(&myself->cipher)) {
 190                 outpkt = pkt[nextpkt++];
 191                 outlen = MAXSIZE;
 192
 193                 if(!cipher_decrypt(&myself->cipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 194                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s)"), n->name, n->hostname);
 195                         return;
 196                 }
 197
 198                 outpkt->len = outlen;
 199                 inpkt = outpkt;
 200         }
 201
 202         /* Check the sequence number */
 203
 204         inpkt->len -= sizeof inpkt->seqno;
 205         inpkt->seqno = ntohl(inpkt->seqno);
 206
 207         if(inpkt->seqno != n->received_seqno + 1) {
 208                 if(inpkt->seqno >= n->received_seqno + sizeof n->late * 8) {
 209                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 210                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 211
 212                         memset(n->late, 0, sizeof n->late);
 213                 } else if (inpkt->seqno <= n->received_seqno) {
 214                         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))) {
 215                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 216                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 217                                 return;
 218                         }
 219                 } else {
 220                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 221                                 n->late[(i / 8) % sizeof n->late] |= 1 << i % 8;
 222                 }
 223         }
 224
 225         n->late[(inpkt->seqno / 8) % sizeof n->late] &= ~(1 << inpkt->seqno % 8);
 226
 227         if(inpkt->seqno > n->received_seqno)
 228                 n->received_seqno = inpkt->seqno;
 229
 230         if(n->received_seqno > MAX_SEQNO)
 231                 regenerate_key();
 232
 233         /* Decompress the packet */
 234
 235         if(myself->compression) {
 236                 outpkt = pkt[nextpkt++];
 237
 238                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 239                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 240                                                  n->name, n->hostname);
 241                         return;
 242                 }
 243
 244                 inpkt = outpkt;
 245         }
 246
 247         if(!inpkt->data[12] && !inpkt->data[13])
 248                 mtu_probe_h(n, inpkt);
 249         else
 250                 receive_packet(n, inpkt);
 251 }
 252
 253 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 254         vpn_packet_t outpkt;
 255
 256         cp();
 257
 258         outpkt.len = len;
 259         memcpy(outpkt.data, buffer, len);
 260
 261         receive_packet(c->node, &outpkt);
 262 }
 263
 264 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 265         vpn_packet_t pkt1, pkt2;
 266         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 267         vpn_packet_t *inpkt = origpkt;
 268         int nextpkt = 0;
 269         vpn_packet_t *outpkt;
 270         int origlen;
 271         size_t outlen;
 272         vpn_packet_t *copy;
 273         static int priority = 0;
 274         int origpriority;
 275         int sock;
 276
 277         cp();
 278
 279         /* Make sure we have a valid key */
 280
 281         if(!n->status.validkey) {
 282                 ifdebug(TRAFFIC) logger(LOG_INFO,
 283                                    _("No valid key known yet for %s (%s), queueing packet"),
 284                                    n->name, n->hostname);
 285
 286                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 287
 288                 *(copy = xmalloc(sizeof *copy)) = *inpkt;
 289
 290                 list_insert_tail(n->queue, copy);
 291
 292                 if(n->queue->count > MAXQUEUELENGTH)
 293                         list_delete_head(n->queue);
 294
 295                 if(!n->status.waitingforkey)
 296                         send_req_key(n->nexthop->connection, myself, n);
 297
 298                 n->status.waitingforkey = true;
 299
 300                 return;
 301         }
 302
 303         origlen = inpkt->len;
 304         origpriority = inpkt->priority;
 305
 306         /* Compress the packet */
 307
 308         if(n->compression) {
 309                 outpkt = pkt[nextpkt++];
 310
 311                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 312                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 313                                    n->name, n->hostname);
 314                         return;
 315                 }
 316
 317                 inpkt = outpkt;
 318         }
 319
 320         /* Add sequence number */
 321
 322         inpkt->seqno = htonl(++(n->sent_seqno));
 323         inpkt->len += sizeof inpkt->seqno;
 324
 325         /* Encrypt the packet */
 326
 327         if(cipher_active(&n->cipher)) {
 328                 outpkt = pkt[nextpkt++];
 329                 outlen = MAXSIZE;
 330
 331                 if(!cipher_encrypt(&n->cipher, &inpkt->seqno, inpkt->len, &outpkt->seqno, &outlen, true)) {
 332                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s)"), n->name, n->hostname);
 333                         goto end;
 334                 }
 335
 336                 outpkt->len = outlen;
 337                 inpkt = outpkt;
 338         }
 339
 340         /* Add the message authentication code */
 341
 342         if(digest_active(&n->digest)) {
 343                 digest_create(&n->digest, &inpkt->seqno, inpkt->len, &inpkt->seqno + inpkt->len);
 344                 inpkt->len += digest_length(&n->digest);
 345         }
 346
 347         /* Determine which socket we have to use */
 348
 349         for(sock = 0; sock < listen_sockets; sock++)
 350                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 351                         break;
 352
 353         if(sock >= listen_sockets)
 354                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 355
 356         /* Send the packet */
 357
 358 #if defined(SOL_IP) && defined(IP_TOS)
 359         if(priorityinheritance && origpriority != priority
 360            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 361                 priority = origpriority;
 362                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 363                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof priority))     /* SO_PRIORITY doesn't seem to work */
 364                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 365         }
 366 #endif
 367
 368         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 369                 if(errno == EMSGSIZE) {
 370                         if(n->maxmtu >= origlen)
 371                                 n->maxmtu = origlen - 1;
 372                         if(n->mtu >= origlen)
 373                                 n->mtu = origlen - 1;
 374                 } else
 375                         logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 376         }
 377
 378 end:
 379         origpkt->len = origlen;
 380 }
 381
 382 /*
 383   send a packet to the given vpn ip.
 384 */
 385 void send_packet(const node_t *n, vpn_packet_t *packet) {
 386         node_t *via;
 387
 388         cp();
 389
 390         if(n == myself) {
 391                 if(overwrite_mac)
 392                          memcpy(packet->data, mymac.x, ETH_ALEN);
 393                 write_packet(packet);
 394                 return;
 395         }
 396
 397         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 398                            packet->len, n->name, n->hostname);
 399
 400         if(!n->status.reachable) {
 401                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 402                                    n->name, n->hostname);
 403                 return;
 404         }
 405
 406         via = (n->via == myself) ? n->nexthop : n->via;
 407
 408         if(via != n)
 409                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 410                            n->name, via->name, n->via->hostname);
 411
 412         if((myself->options | via->options) & OPTION_TCPONLY) {
 413                 if(!send_tcppacket(via->connection, packet))
 414                         terminate_connection(via->connection, true);
 415         } else
 416                 send_udppacket(via, packet);
 417 }
 418
 419 /* Broadcast a packet using the minimum spanning tree */
 420
 421 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 422         splay_node_t *node;
 423         connection_t *c;
 424
 425         cp();
 426
 427         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 428                            packet->len, from->name, from->hostname);
 429
 430         if(from != myself)
 431                 send_packet(myself, packet);
 432
 433         for(node = connection_tree->head; node; node = node->next) {
 434                 c = node->data;
 435
 436                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 437                         send_packet(c->node, packet);
 438         }
 439 }
 440
 441 void flush_queue(node_t *n) {
 442         list_node_t *node, *next;
 443
 444         cp();
 445
 446         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 447
 448         for(node = n->queue->head; node; node = next) {
 449                 next = node->next;
 450                 send_udppacket(n, node->data);
 451                 list_delete_node(n->queue, node);
 452         }
 453 }
 454
 455 void handle_incoming_vpn_data(int sock, short events, void *data) {
 456         vpn_packet_t pkt;
 457         char *hostname;
 458         sockaddr_t from;
 459         socklen_t fromlen = sizeof from;
 460         node_t *n;
 461
 462         cp();
 463
 464         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 465
 466         if(pkt.len < 0) {
 467                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 468                 return;
 469         }
 470
 471         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 472
 473         n = lookup_node_udp(&from);
 474
 475         if(!n) {
 476                 hostname = sockaddr2hostname(&from);
 477                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 478                            hostname);
 479                 free(hostname);
 480                 return;
 481         }
 482
 483         receive_udppacket(n, &pkt);
 484 }
 485
 486 void handle_device_data(int sock, short events, void *data) {
 487         vpn_packet_t packet;
 488
 489         if(read_packet(&packet))
 490                 route(myself, &packet);
 491 }