tinc-vpn.org Git - tinc/blob - src/net_packet.c

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2013 Guus Sliepen <guus@tinc-vpn.org>
   5                   2010      Timothy Redaelli <timothy@redaelli.eu>
   6                   2010      Brandon Black <blblack@gmail.com>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License along
  19     with this program; if not, write to the Free Software Foundation, Inc.,
  20     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  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 #ifdef HAVE_ZLIB
  32 #include <zlib.h>
  33 #endif
  34
  35 #ifdef HAVE_LZO
  36 #include LZO1X_H
  37 #endif
  38
  39 #include "avl_tree.h"
  40 #include "conf.h"
  41 #include "connection.h"
  42 #include "device.h"
  43 #include "ethernet.h"
  44 #include "event.h"
  45 #include "graph.h"
  46 #include "logger.h"
  47 #include "net.h"
  48 #include "netutl.h"
  49 #include "protocol.h"
  50 #include "process.h"
  51 #include "route.h"
  52 #include "utils.h"
  53 #include "xalloc.h"
  54
  55 int keylifetime = 0;
  56 int keyexpires = 0;
  57 #ifdef HAVE_LZO
  58 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  59 #endif
  60
  61 static void send_udppacket(node_t *, vpn_packet_t *);
  62
  63 unsigned replaywin = 16;
  64 bool localdiscovery = false;
  65
  66 #define MAX_SEQNO 1073741824
  67
  68 /* mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
  69    mtuprobes ==    31: sleep pinginterval seconds
  70    mtuprobes ==    32: send 1 burst, sleep pingtimeout second
  71    mtuprobes ==    33: no response from other side, restart PMTU discovery process
  72
  73    Probes are sent in batches of at least three, with random sizes between the
  74    lower and upper boundaries for the MTU thus far discovered.
  75
  76    After the initial discovery, a fourth packet is added to each batch with a
  77    size larger than the currently known PMTU, to test if the PMTU has increased.
  78
  79    In case local discovery is enabled, another packet is added to each batch,
  80    which will be broadcast to the local network.
  81
  82 */
  83
  84 void send_mtu_probe(node_t *n) {
  85         vpn_packet_t packet;
  86         int len, i;
  87         int timeout = 1;
  88
  89         n->mtuprobes++;
  90         n->mtuevent = NULL;
  91
  92         if(!n->status.reachable || !n->status.validkey) {
  93                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
  94                 n->mtuprobes = 0;
  95                 return;
  96         }
  97
  98         if(n->mtuprobes > 32) {
  99                 if(!n->minmtu) {
 100                         n->mtuprobes = 31;
 101                         timeout = pinginterval;
 102                         goto end;
 103                 }
 104
 105                 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
 106                 n->mtuprobes = 1;
 107                 n->minmtu = 0;
 108                 n->maxmtu = MTU;
 109         }
 110
 111         if(n->mtuprobes >= 10 && n->mtuprobes < 32 && !n->minmtu) {
 112                 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
 113                 n->mtuprobes = 31;
 114         }
 115
 116         if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
 117                 if(n->minmtu > n->maxmtu)
 118                         n->minmtu = n->maxmtu;
 119                 else
 120                         n->maxmtu = n->minmtu;
 121                 n->mtu = n->minmtu;
 122                 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
 123                 n->mtuprobes = 31;
 124         }
 125
 126         if(n->mtuprobes == 31) {
 127                 timeout = pinginterval;
 128                 goto end;
 129         } else if(n->mtuprobes == 32) {
 130                 timeout = pingtimeout;
 131         }
 132
 133         for(i = 0; i < 4 + localdiscovery; i++) {
 134                 if(i == 0) {
 135                         if(n->mtuprobes < 30 || n->maxmtu + 8 >= MTU)
 136                                 continue;
 137                         len = n->maxmtu + 8;
 138                 } else if(n->maxmtu <= n->minmtu) {
 139                         len = n->maxmtu;
 140                 } else {
 141                         len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
 142                 }
 143
 144                 if(len < 64)
 145                         len = 64;
 146
 147                 memset(packet.data, 0, 14);
 148                 RAND_pseudo_bytes(packet.data + 14, len - 14);
 149                 packet.len = len;
 150                 if(i >= 4 && n->mtuprobes <= 10)
 151                         packet.priority = -1;
 152                 else
 153                         packet.priority = 0;
 154
 155                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 156
 157                 send_udppacket(n, &packet);
 158         }
 159
 160 end:
 161         n->mtuevent = new_event();
 162         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 163         n->mtuevent->data = n;
 164         n->mtuevent->time = now + timeout;
 165         event_add(n->mtuevent);
 166 }
 167
 168 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 169         ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
 170
 171         if(!packet->data[0]) {
 172                 packet->data[0] = 1;
 173                 send_udppacket(n, packet);
 174         } else {
 175                 if(n->mtuprobes > 30) {
 176                         if (len == n->maxmtu + 8) {
 177                                 ifdebug(TRAFFIC) logger(LOG_INFO, "Increase in PMTU to %s (%s) detected, restarting PMTU discovery", n->name, n->hostname);
 178                                 n->maxmtu = MTU;
 179                                 n->mtuprobes = 10;
 180                                 return;
 181                         }
 182
 183                         if(n->minmtu)
 184                                 n->mtuprobes = 30;
 185                         else
 186                                 n->mtuprobes = 1;
 187                 }
 188
 189                 if(len > n->maxmtu)
 190                         len = n->maxmtu;
 191                 if(n->minmtu < len)
 192                         n->minmtu = len;
 193         }
 194 }
 195
 196 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 197         if(level == 0) {
 198                 memcpy(dest, source, len);
 199                 return len;
 200         } else if(level == 10) {
 201 #ifdef HAVE_LZO
 202                 lzo_uint lzolen = MAXSIZE;
 203                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 204                 return lzolen;
 205 #else
 206                 return -1;
 207 #endif
 208         } else if(level < 10) {
 209 #ifdef HAVE_ZLIB
 210                 unsigned long destlen = MAXSIZE;
 211                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 212                         return destlen;
 213                 else
 214 #endif
 215                         return -1;
 216         } else {
 217 #ifdef HAVE_LZO
 218                 lzo_uint lzolen = MAXSIZE;
 219                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 220                 return lzolen;
 221 #else
 222                 return -1;
 223 #endif
 224         }
 225
 226         return -1;
 227 }
 228
 229 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 230         if(level == 0) {
 231                 memcpy(dest, source, len);
 232                 return len;
 233         } else if(level > 9) {
 234 #ifdef HAVE_LZO
 235                 lzo_uint lzolen = MAXSIZE;
 236                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 237                         return lzolen;
 238                 else
 239 #endif
 240                         return -1;
 241         }
 242 #ifdef HAVE_ZLIB
 243         else {
 244                 unsigned long destlen = MAXSIZE;
 245                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 246                         return destlen;
 247                 else
 248                         return -1;
 249         }
 250 #endif
 251
 252         return -1;
 253 }
 254
 255 /* VPN packet I/O */
 256
 257 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 258         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
 259                            packet->len, n->name, n->hostname);
 260
 261         route(n, packet);
 262 }
 263
 264 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
 265         unsigned char hmac[EVP_MAX_MD_SIZE];
 266
 267         if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 268                 return false;
 269
 270         HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
 271
 272         return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
 273 }
 274
 275 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 276         vpn_packet_t pkt1, pkt2;
 277         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 278         int nextpkt = 0;
 279         vpn_packet_t *outpkt = pkt[0];
 280         int outlen, outpad;
 281         unsigned char hmac[EVP_MAX_MD_SIZE];
 282         int i;
 283
 284         if(!n->inkey) {
 285                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
 286                                         n->name, n->hostname);
 287                 return;
 288         }
 289
 290         /* Check packet length */
 291
 292         if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
 293                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
 294                                         n->name, n->hostname);
 295                 return;
 296         }
 297
 298         /* Check the message authentication code */
 299
 300         if(n->indigest && n->inmaclength) {
 301                 inpkt->len -= n->inmaclength;
 302                 HMAC(n->indigest, n->inkey, n->inkeylength,
 303                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 304
 305                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
 306                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
 307                                            n->name, n->hostname);
 308                         return;
 309                 }
 310         }
 311
 312         /* Decrypt the packet */
 313
 314         if(n->incipher) {
 315                 outpkt = pkt[nextpkt++];
 316
 317                 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
 318                                 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
 319                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 320                                 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 321                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
 322                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 323                         return;
 324                 }
 325
 326                 outpkt->len = outlen + outpad;
 327                 inpkt = outpkt;
 328         }
 329
 330         /* Check the sequence number */
 331
 332         inpkt->len -= sizeof(inpkt->seqno);
 333         inpkt->seqno = ntohl(inpkt->seqno);
 334
 335         if(replaywin) {
 336                 if(inpkt->seqno != n->received_seqno + 1) {
 337                         if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
 338                                 if(n->farfuture++ < replaywin >> 2) {
 339                                         logger(LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)",
 340                                                 n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture);
 341                                         return;
 342                                 }
 343                                 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
 344                                                 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 345                                 memset(n->late, 0, replaywin);
 346                         } else if (inpkt->seqno <= n->received_seqno) {
 347                                 if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
 348                                         logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
 349                                                 n->name, n->hostname, inpkt->seqno, n->received_seqno);
 350                                         return;
 351                                 }
 352                         } else {
 353                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 354                                         n->late[(i / 8) % replaywin] |= 1 << i % 8;
 355                         }
 356                 }
 357
 358                 n->farfuture = 0;
 359                 n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
 360         }
 361
 362         if(inpkt->seqno > n->received_seqno)
 363                 n->received_seqno = inpkt->seqno;
 364
 365         if(n->received_seqno > MAX_SEQNO)
 366                 keyexpires = 0;
 367
 368         /* Decompress the packet */
 369
 370         length_t origlen = inpkt->len;
 371
 372         if(n->incompression) {
 373                 outpkt = pkt[nextpkt++];
 374
 375                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 376                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
 377                                                  n->name, n->hostname);
 378                         return;
 379                 }
 380
 381                 inpkt = outpkt;
 382
 383                 origlen -= MTU/64 + 20;
 384         }
 385
 386         inpkt->priority = 0;
 387
 388         if(!inpkt->data[12] && !inpkt->data[13])
 389                 mtu_probe_h(n, inpkt, origlen);
 390         else
 391                 receive_packet(n, inpkt);
 392 }
 393
 394 void receive_tcppacket(connection_t *c, const char *buffer, int len) {
 395         vpn_packet_t outpkt;
 396
 397         outpkt.len = len;
 398         if(c->options & OPTION_TCPONLY)
 399                 outpkt.priority = 0;
 400         else
 401                 outpkt.priority = -1;
 402         memcpy(outpkt.data, buffer, len);
 403
 404         receive_packet(c->node, &outpkt);
 405 }
 406
 407 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 408         vpn_packet_t pkt1, pkt2;
 409         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 410         vpn_packet_t *inpkt = origpkt;
 411         int nextpkt = 0;
 412         vpn_packet_t *outpkt;
 413         int origlen;
 414         int outlen, outpad;
 415 #if defined(SOL_IP) && defined(IP_TOS)
 416         static int priority = 0;
 417 #endif
 418         int origpriority;
 419
 420         if(!n->status.reachable) {
 421                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
 422                 return;
 423         }
 424
 425         /* Make sure we have a valid key */
 426
 427         if(!n->status.validkey) {
 428                 ifdebug(TRAFFIC) logger(LOG_INFO,
 429                                    "No valid key known yet for %s (%s), forwarding via TCP",
 430                                    n->name, n->hostname);
 431
 432                 if(n->last_req_key + 10 <= now) {
 433                         send_req_key(n);
 434                         n->last_req_key = now;
 435                 }
 436
 437                 send_tcppacket(n->nexthop->connection, origpkt);
 438
 439                 return;
 440         }
 441
 442         if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 443                 ifdebug(TRAFFIC) logger(LOG_INFO,
 444                                 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
 445                                 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 446
 447                 if(n != n->nexthop)
 448                         send_packet(n->nexthop, origpkt);
 449                 else
 450                         send_tcppacket(n->nexthop->connection, origpkt);
 451
 452                 return;
 453         }
 454
 455         origlen = inpkt->len;
 456         origpriority = inpkt->priority;
 457
 458         /* Compress the packet */
 459
 460         if(n->outcompression) {
 461                 outpkt = pkt[nextpkt++];
 462
 463                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 464                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
 465                                    n->name, n->hostname);
 466                         return;
 467                 }
 468
 469                 inpkt = outpkt;
 470         }
 471
 472         /* Add sequence number */
 473
 474         inpkt->seqno = htonl(++(n->sent_seqno));
 475         inpkt->len += sizeof(inpkt->seqno);
 476
 477         /* Encrypt the packet */
 478
 479         if(n->outcipher) {
 480                 outpkt = pkt[nextpkt++];
 481
 482                 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
 483                                 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
 484                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 485                                 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 486                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
 487                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 488                         goto end;
 489                 }
 490
 491                 outpkt->len = outlen + outpad;
 492                 inpkt = outpkt;
 493         }
 494
 495         /* Add the message authentication code */
 496
 497         if(n->outdigest && n->outmaclength) {
 498                 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
 499                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 500                 inpkt->len += n->outmaclength;
 501         }
 502
 503         /* Determine which socket we have to use */
 504
 505         if(n->address.sa.sa_family != listen_socket[n->sock].sa.sa.sa_family) {
 506                 for(int sock = 0; sock < listen_sockets; sock++) {
 507                         if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family) {
 508                                 n->sock = sock;
 509                                 break;
 510                         }
 511                 }
 512         }
 513
 514         /* Send the packet */
 515
 516         struct sockaddr *sa;
 517         socklen_t sl;
 518         int sock;
 519         sockaddr_t broadcast;
 520
 521         /* Overloaded use of priority field: -1 means local broadcast */
 522
 523         if(origpriority == -1 && n->prevedge) {
 524                 sock = rand() % listen_sockets;
 525                 memset(&broadcast, 0, sizeof broadcast);
 526                 if(listen_socket[sock].sa.sa.sa_family == AF_INET6) {
 527                         broadcast.in6.sin6_family = AF_INET6;
 528                         broadcast.in6.sin6_addr.s6_addr[0x0] = 0xff;
 529                         broadcast.in6.sin6_addr.s6_addr[0x1] = 0x02;
 530                         broadcast.in6.sin6_addr.s6_addr[0xf] = 0x01;
 531                         broadcast.in6.sin6_port = n->prevedge->address.in.sin_port;
 532                         broadcast.in6.sin6_scope_id = listen_socket[sock].sa.in6.sin6_scope_id;
 533                 } else {
 534                         broadcast.in.sin_family = AF_INET;
 535                         broadcast.in.sin_addr.s_addr = -1;
 536                         broadcast.in.sin_port = n->prevedge->address.in.sin_port;
 537                 }
 538                 sa = &broadcast.sa;
 539                 sl = SALEN(broadcast.sa);
 540         } else {
 541                 if(origpriority == -1)
 542                         origpriority = 0;
 543
 544                 sa = &(n->address.sa);
 545                 sl = SALEN(n->address.sa);
 546                 sock = n->sock;
 547         }
 548
 549 #if defined(SOL_IP) && defined(IP_TOS)
 550         if(priorityinheritance && origpriority != priority
 551            && listen_socket[n->sock].sa.sa.sa_family == AF_INET) {
 552                 priority = origpriority;
 553                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
 554                 if(setsockopt(listen_socket[n->sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority))) /* SO_PRIORITY doesn't seem to work */
 555                         logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 556         }
 557 #endif
 558
 559         if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) {
 560                 if(sockmsgsize(sockerrno)) {
 561                         if(n->maxmtu >= origlen)
 562                                 n->maxmtu = origlen - 1;
 563                         if(n->mtu >= origlen)
 564                                 n->mtu = origlen - 1;
 565                 } else
 566                         ifdebug(TRAFFIC) logger(LOG_WARNING, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 567         }
 568
 569 end:
 570         origpkt->len = origlen;
 571 }
 572
 573 /*
 574   send a packet to the given vpn ip.
 575 */
 576 void send_packet(const node_t *n, vpn_packet_t *packet) {
 577         node_t *via;
 578
 579         if(n == myself) {
 580                 if(overwrite_mac)
 581                          memcpy(packet->data, mymac.x, ETH_ALEN);
 582                 devops.write(packet);
 583                 return;
 584         }
 585
 586         ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
 587                            packet->len, n->name, n->hostname);
 588
 589         if(!n->status.reachable) {
 590                 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 591                                    n->name, n->hostname);
 592                 return;
 593         }
 594
 595         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 596
 597         if(via != n)
 598                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
 599                            n->name, via->name, n->via->hostname);
 600
 601         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 602                 if(!send_tcppacket(via->connection, packet))
 603                         terminate_connection(via->connection, true);
 604         } else
 605                 send_udppacket(via, packet);
 606 }
 607
 608 /* Broadcast a packet using the minimum spanning tree */
 609
 610 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 611         avl_node_t *node;
 612         connection_t *c;
 613         node_t *n;
 614
 615         // Always give ourself a copy of the packet.
 616         if(from != myself)
 617                 send_packet(myself, packet);
 618
 619         // In TunnelServer mode, do not forward broadcast packets.
 620         // The MST might not be valid and create loops.
 621         if(tunnelserver || broadcast_mode == BMODE_NONE)
 622                 return;
 623
 624         ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
 625                            packet->len, from->name, from->hostname);
 626
 627         switch(broadcast_mode) {
 628                 // In MST mode, broadcast packets travel via the Minimum Spanning Tree.
 629                 // This guarantees all nodes receive the broadcast packet, and
 630                 // usually distributes the sending of broadcast packets over all nodes.
 631                 case BMODE_MST:
 632                         for(node = connection_tree->head; node; node = node->next) {
 633                                 c = node->data;
 634
 635                                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 636                                         send_packet(c->node, packet);
 637                         }
 638                         break;
 639
 640                 // In direct mode, we send copies to each node we know of.
 641                 // However, this only reaches nodes that can be reached in a single hop.
 642                 // We don't have enough information to forward broadcast packets in this case.
 643                 case BMODE_DIRECT:
 644                         if(from != myself)
 645                                 break;
 646
 647                         for(node = node_udp_tree->head; node; node = node->next) {
 648                                 n = node->data;
 649
 650                                 if(n->status.reachable && ((n->via == myself && n->nexthop == n) || n->via == n))
 651                                         send_packet(n, packet);
 652                         }
 653                         break;
 654
 655                 default:
 656                         break;
 657         }
 658 }
 659
 660 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 661         avl_node_t *node;
 662         edge_t *e;
 663         node_t *n = NULL;
 664         bool hard = false;
 665         static time_t last_hard_try = 0;
 666
 667         for(node = edge_weight_tree->head; node; node = node->next) {
 668                 e = node->data;
 669
 670                 if(e->to == myself)
 671                         continue;
 672
 673                 if(sockaddrcmp_noport(from, &e->address)) {
 674                         if(last_hard_try == now)
 675                                 continue;
 676                         hard = true;
 677                 }
 678
 679                 if(!try_mac(e->to, pkt))
 680                         continue;
 681
 682                 n = e->to;
 683                 break;
 684         }
 685
 686         if(hard)
 687                 last_hard_try = now;
 688
 689         last_hard_try = now;
 690         return n;
 691 }
 692
 693 void handle_incoming_vpn_data(int sock) {
 694         vpn_packet_t pkt;
 695         char *hostname;
 696         sockaddr_t from;
 697         socklen_t fromlen = sizeof(from);
 698         node_t *n;
 699
 700         pkt.len = recvfrom(listen_socket[sock].udp, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 701
 702         if(pkt.len < 0) {
 703                 if(!sockwouldblock(sockerrno))
 704                         logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 705                 return;
 706         }
 707
 708         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 709
 710         n = lookup_node_udp(&from);
 711
 712         if(!n) {
 713                 n = try_harder(&from, &pkt);
 714                 if(n)
 715                         update_node_udp(n, &from);
 716                 else ifdebug(PROTOCOL) {
 717                         hostname = sockaddr2hostname(&from);
 718                         logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 719                         free(hostname);
 720                         return;
 721                 }
 722                 else
 723                         return;
 724         }
 725
 726         n->sock = sock;
 727
 728         receive_udppacket(n, &pkt);
 729 }