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 1.1.2.45 2003/12/20 19:47:52 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         for(i = 0; i < 3; i++) {
  69                 if(n->mtuprobes >= 100 || n->probedmtu >= n->mtu) {
  70                         n->mtu = n->probedmtu;
  71                         ifdebug(TRAFFIC) logger(LOG_INFO, _("Fixing MTU of %s (%s) to %d after %d probes"), n->name, n->hostname, n->mtu, n->mtuprobes);
  72                         return;
  73                 }
  74
  75                 len = n->probedmtu + 1 + random() % (n->mtu - n->probedmtu);
  76                 if(len < 64)
  77                         len = 64;
  78
  79                 memset(packet.data, 0, 14);
  80                 RAND_pseudo_bytes(packet.data + 14, len - 14);
  81                 packet.len = len;
  82
  83                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Sending MTU probe length %d to %s (%s)"), len, n->name, n->hostname);
  84
  85                 send_udppacket(n, &packet);
  86         }
  87
  88         n->mtuevent = xmalloc(sizeof(*n->mtuevent));
  89         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
  90         n->mtuevent->data = n;
  91         n->mtuevent->time = now + 1;
  92         event_add(n->mtuevent);
  93 }
  94
  95 void mtu_probe_h(node_t *n, vpn_packet_t *packet) {
  96         ifdebug(TRAFFIC) logger(LOG_INFO, _("Got MTU probe length %d from %s (%s)"), packet->len, n->name, n->hostname);
  97
  98         if(!packet->data[0]) {
  99                 packet->data[0] = 1;
 100                 send_packet(n, packet);
 101         } else {
 102                 if(n->probedmtu < packet->len)
 103                         n->probedmtu = packet->len;
 104         }
 105 }
 106
 107 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 108 {
 109         if(level == 10) {
 110                 lzo_uint lzolen = MAXSIZE;
 111                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 112                 return lzolen;
 113         } else if(level < 10) {
 114                 unsigned long destlen = MAXSIZE;
 115                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 116                         return destlen;
 117                 else
 118                         return -1;
 119         } else {
 120                 lzo_uint lzolen = MAXSIZE;
 121                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 122                 return lzolen;
 123         }
 124
 125         return -1;
 126 }
 127
 128 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level)
 129 {
 130         if(level > 9) {
 131                 lzo_uint lzolen = MAXSIZE;
 132                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 133                         return lzolen;
 134                 else
 135                         return -1;
 136         } else {
 137                 unsigned long destlen = MAXSIZE;
 138                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 139                         return destlen;
 140                 else
 141                         return -1;
 142         }
 143
 144         return -1;
 145 }
 146
 147 /* VPN packet I/O */
 148
 149 static void receive_packet(node_t *n, vpn_packet_t *packet)
 150 {
 151         cp();
 152
 153         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Received packet of %d bytes from %s (%s)"),
 154                            packet->len, n->name, n->hostname);
 155
 156         route(n, packet);
 157 }
 158
 159 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt)
 160 {
 161         vpn_packet_t pkt1, pkt2;
 162         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 163         int nextpkt = 0;
 164         vpn_packet_t *outpkt = pkt[0];
 165         int outlen, outpad;
 166         char hmac[EVP_MAX_MD_SIZE];
 167         int i;
 168
 169         cp();
 170
 171         /* Check packet length */
 172
 173         if(inpkt->len < sizeof(inpkt->seqno) + myself->maclength) {
 174                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got too short packet from %s (%s)"),
 175                                         n->name, n->hostname);
 176                 return;
 177         }
 178
 179         /* Check the message authentication code */
 180
 181         if(myself->digest && myself->maclength) {
 182                 inpkt->len -= myself->maclength;
 183                 HMAC(myself->digest, myself->key, myself->keylength,
 184                          (char *) &inpkt->seqno, inpkt->len, hmac, NULL);
 185
 186                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, myself->maclength)) {
 187                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Got unauthenticated packet from %s (%s)"),
 188                                            n->name, n->hostname);
 189                         return;
 190                 }
 191         }
 192
 193         /* Decrypt the packet */
 194
 195         if(myself->cipher) {
 196                 outpkt = pkt[nextpkt++];
 197
 198                 if(!EVP_DecryptInit_ex(&packet_ctx, NULL, NULL, NULL, NULL)
 199                                 || !EVP_DecryptUpdate(&packet_ctx, (char *) &outpkt->seqno, &outlen,
 200                                         (char *) &inpkt->seqno, inpkt->len)
 201                                 || !EVP_DecryptFinal_ex(&packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 202                         ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Error decrypting packet from %s (%s): %s"),
 203                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 204                         return;
 205                 }
 206
 207                 outpkt->len = outlen + outpad;
 208                 inpkt = outpkt;
 209         }
 210
 211         /* Check the sequence number */
 212
 213         inpkt->len -= sizeof(inpkt->seqno);
 214         inpkt->seqno = ntohl(inpkt->seqno);
 215
 216         if(inpkt->seqno != n->received_seqno + 1) {
 217                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 218                         logger(LOG_WARNING, _("Lost %d packets from %s (%s)"),
 219                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 220
 221                         memset(n->late, 0, sizeof(n->late));
 222                 } else if (inpkt->seqno <= n->received_seqno) {
 223                         if(inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8 || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 224                                 logger(LOG_WARNING, _("Got late or replayed packet from %s (%s), seqno %d, last received %d"),
 225                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 226                         } else
 227                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 228                                         n->late[(inpkt->seqno / 8) % sizeof(n->late)] |= 1 << i % 8;
 229                 }
 230         }
 231
 232         n->received_seqno = inpkt->seqno;
 233         n->late[(n->received_seqno / 8) % sizeof(n->late)] &= ~(1 << n->received_seqno % 8);
 234
 235         if(n->received_seqno > MAX_SEQNO)
 236                 keyexpires = 0;
 237
 238         /* Decompress the packet */
 239
 240         if(myself->compression) {
 241                 outpkt = pkt[nextpkt++];
 242
 243                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, myself->compression)) < 0) {
 244                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while uncompressing packet from %s (%s)"),
 245                                                  n->name, n->hostname);
 246                         return;
 247                 }
 248
 249                 inpkt = outpkt;
 250         }
 251
 252         if(n->connection)
 253                 n->connection->last_ping_time = now;
 254
 255         if(!inpkt->data[12] && !inpkt->data[13])
 256                 mtu_probe_h(n, inpkt);
 257         else
 258                 receive_packet(n, inpkt);
 259 }
 260
 261 void receive_tcppacket(connection_t *c, char *buffer, int len)
 262 {
 263         vpn_packet_t outpkt;
 264
 265         cp();
 266
 267         outpkt.len = len;
 268         memcpy(outpkt.data, buffer, len);
 269
 270         receive_packet(c->node, &outpkt);
 271 }
 272
 273 static void send_udppacket(node_t *n, vpn_packet_t *inpkt)
 274 {
 275         vpn_packet_t pkt1, pkt2;
 276         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 277         int nextpkt = 0;
 278         vpn_packet_t *outpkt;
 279         int origlen;
 280         int outlen, outpad;
 281         vpn_packet_t *copy;
 282         static int priority = 0;
 283         int origpriority;
 284         int sock;
 285
 286         cp();
 287
 288         /* Make sure we have a valid key */
 289
 290         if(!n->status.validkey) {
 291                 ifdebug(TRAFFIC) logger(LOG_INFO,
 292                                    _("No valid key known yet for %s (%s), queueing packet"),
 293                                    n->name, n->hostname);
 294
 295                 /* Since packet is on the stack of handle_tap_input(), we have to make a copy of it first. */
 296
 297                 *(copy = xmalloc(sizeof(*copy))) = *inpkt;
 298
 299                 list_insert_tail(n->queue, copy);
 300
 301                 if(n->queue->count > MAXQUEUELENGTH)
 302                         list_delete_head(n->queue);
 303
 304                 if(!n->status.waitingforkey)
 305                         send_req_key(n->nexthop->connection, myself, n);
 306
 307                 n->status.waitingforkey = true;
 308
 309                 return;
 310         }
 311
 312         origlen = inpkt->len;
 313         origpriority = inpkt->priority;
 314
 315         /* Compress the packet */
 316
 317         if(n->compression) {
 318                 outpkt = pkt[nextpkt++];
 319
 320                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->compression)) < 0) {
 321                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while compressing packet to %s (%s)"),
 322                                    n->name, n->hostname);
 323                         return;
 324                 }
 325
 326                 inpkt = outpkt;
 327         }
 328
 329         /* Add sequence number */
 330
 331         inpkt->seqno = htonl(++(n->sent_seqno));
 332         inpkt->len += sizeof(inpkt->seqno);
 333
 334         /* Encrypt the packet */
 335
 336         if(n->cipher) {
 337                 outpkt = pkt[nextpkt++];
 338
 339                 if(!EVP_EncryptInit_ex(&n->packet_ctx, NULL, NULL, NULL, NULL)
 340                                 || !EVP_EncryptUpdate(&n->packet_ctx, (char *) &outpkt->seqno, &outlen,
 341                                         (char *) &inpkt->seqno, inpkt->len)
 342                                 || !EVP_EncryptFinal_ex(&n->packet_ctx, (char *) &outpkt->seqno + outlen, &outpad)) {
 343                         ifdebug(TRAFFIC) logger(LOG_ERR, _("Error while encrypting packet to %s (%s): %s"),
 344                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 345                         return;
 346                 }
 347
 348                 outpkt->len = outlen + outpad;
 349                 inpkt = outpkt;
 350         }
 351
 352         /* Add the message authentication code */
 353
 354         if(n->digest && n->maclength) {
 355                 HMAC(n->digest, n->key, n->keylength, (char *) &inpkt->seqno,
 356                          inpkt->len, (char *) &inpkt->seqno + inpkt->len, &outlen);
 357                 inpkt->len += n->maclength;
 358         }
 359
 360         /* Determine which socket we have to use */
 361
 362         for(sock = 0; sock < listen_sockets; sock++)
 363                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 364                         break;
 365
 366         if(sock >= listen_sockets)
 367                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 368
 369         /* Send the packet */
 370
 371 #if defined(SOL_IP) && defined(IP_TOS)
 372         if(priorityinheritance && origpriority != priority
 373            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 374                 priority = origpriority;
 375                 ifdebug(TRAFFIC) logger(LOG_DEBUG, _("Setting outgoing packet priority to %d"), priority);
 376                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 377                         logger(LOG_ERR, _("System call `%s' failed: %s"), "setsockopt", strerror(errno));
 378         }
 379 #endif
 380
 381         if((sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa))) < 0) {
 382                 logger(LOG_ERR, _("Error sending packet to %s (%s): %s"), n->name, n->hostname, strerror(errno));
 383                 if(errno == EMSGSIZE) {
 384                         if(n->mtu >= origlen)
 385                                 n->mtu = origlen - 1;
 386                 }
 387                 return;
 388         }
 389
 390         inpkt->len = origlen;
 391 }
 392
 393 /*
 394   send a packet to the given vpn ip.
 395 */
 396 void send_packet(const node_t *n, vpn_packet_t *packet)
 397 {
 398         node_t *via;
 399
 400         cp();
 401
 402         if(n == myself) {
 403                 write_packet(packet);
 404                 return;
 405         }
 406
 407         ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet of %d bytes to %s (%s)"),
 408                            packet->len, n->name, n->hostname);
 409
 410         if(!n->status.reachable) {
 411                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Node %s (%s) is not reachable"),
 412                                    n->name, n->hostname);
 413                 return;
 414         }
 415
 416         via = (n->via == myself) ? n->nexthop : n->via;
 417
 418         if(via != n)
 419                 ifdebug(TRAFFIC) logger(LOG_ERR, _("Sending packet to %s via %s (%s)"),
 420                            n->name, via->name, n->via->hostname);
 421
 422         if((myself->options | via->options) & OPTION_TCPONLY) {
 423                 if(!send_tcppacket(via->connection, packet))
 424                         terminate_connection(via->connection, true);
 425         } else
 426                 send_udppacket(via, packet);
 427 }
 428
 429 /* Broadcast a packet using the minimum spanning tree */
 430
 431 void broadcast_packet(const node_t *from, vpn_packet_t *packet)
 432 {
 433         avl_node_t *node;
 434         connection_t *c;
 435
 436         cp();
 437
 438         ifdebug(TRAFFIC) logger(LOG_INFO, _("Broadcasting packet of %d bytes from %s (%s)"),
 439                            packet->len, from->name, from->hostname);
 440
 441         for(node = connection_tree->head; node; node = node->next) {
 442                 c = node->data;
 443
 444                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 445                         send_packet(c->node, packet);
 446         }
 447 }
 448
 449 void flush_queue(node_t *n)
 450 {
 451         list_node_t *node, *next;
 452
 453         cp();
 454
 455         ifdebug(TRAFFIC) logger(LOG_INFO, _("Flushing queue for %s (%s)"), n->name, n->hostname);
 456
 457         for(node = n->queue->head; node; node = next) {
 458                 next = node->next;
 459                 send_udppacket(n, node->data);
 460                 list_delete_node(n->queue, node);
 461         }
 462 }
 463
 464 void handle_incoming_vpn_data(int sock)
 465 {
 466         vpn_packet_t pkt;
 467         char *hostname;
 468         sockaddr_t from;
 469         socklen_t fromlen = sizeof(from);
 470         node_t *n;
 471
 472         cp();
 473
 474         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 475
 476         if(pkt.len < 0) {
 477                 logger(LOG_ERR, _("Receiving packet failed: %s"), strerror(errno));
 478                 return;
 479         }
 480
 481         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 482
 483         n = lookup_node_udp(&from);
 484
 485         if(!n) {
 486                 hostname = sockaddr2hostname(&from);
 487                 logger(LOG_WARNING, _("Received UDP packet from unknown source %s"),
 488                            hostname);
 489                 free(hostname);
 490                 return;
 491         }
 492
 493         receive_udppacket(n, &pkt);
 494 }