src/net_packet.c

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2016 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_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_constant_time(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;
 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_constant_time(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                                         ifdebug(TRAFFIC) 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                                 ifdebug(TRAFFIC) 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                                         ifdebug(TRAFFIC) 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         if(len > sizeof outpkt.data)
 398                 return;
 399
 400         outpkt.len = len;
 401         if(c->options & OPTION_TCPONLY)
 402                 outpkt.priority = 0;
 403         else
 404                 outpkt.priority = -1;
 405         memcpy(outpkt.data, buffer, len);
 406
 407         receive_packet(c->node, &outpkt);
 408 }
 409
 410 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 411         vpn_packet_t pkt1, pkt2;
 412         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 413         vpn_packet_t *inpkt = origpkt;
 414         int nextpkt = 0;
 415         vpn_packet_t *outpkt;
 416         int origlen;
 417         int outlen, outpad;
 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(priorityinheritance && origpriority != listen_socket[n->sock].priority) {
 550                 listen_socket[n->sock].priority = origpriority;
 551                 switch(listen_socket[n->sock].sa.sa.sa_family) {
 552 #if defined(SOL_IP) && defined(IP_TOS)
 553                 case AF_INET:
 554                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting IPv4 outgoing packet priority to %d", origpriority);
 555                         if(setsockopt(listen_socket[n->sock].udp, SOL_IP, IP_TOS, (void *)&origpriority, sizeof(origpriority))) /* SO_PRIORITY doesn't seem to work */
 556                                 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 557                         break;
 558 #endif
 559 #if defined(IPPROTO_IPV6) && defined(IPV6_TCLASS)
 560                 case AF_INET6:
 561                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting IPv6 outgoing packet priority to %d", origpriority);
 562                         if(setsockopt(listen_socket[n->sock].udp, IPPROTO_IPV6, IPV6_TCLASS, (void *)&origpriority, sizeof(origpriority)))
 563                                 logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 564                         break;
 565 #endif
 566                 default:
 567                         break;
 568                 }
 569         }
 570
 571         if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, sa, sl) < 0 && !sockwouldblock(sockerrno)) {
 572                 if(sockmsgsize(sockerrno)) {
 573                         if(n->maxmtu >= origlen)
 574                                 n->maxmtu = origlen - 1;
 575                         if(n->mtu >= origlen)
 576                                 n->mtu = origlen - 1;
 577                 } else
 578                         ifdebug(TRAFFIC) logger(LOG_WARNING, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 579         }
 580
 581 end:
 582         origpkt->len = origlen;
 583 }
 584
 585 /*
 586   send a packet to the given vpn ip.
 587 */
 588 void send_packet(const node_t *n, vpn_packet_t *packet) {
 589         node_t *via;
 590
 591         if(n == myself) {
 592                 if(overwrite_mac)
 593                          memcpy(packet->data, mymac.x, ETH_ALEN);
 594                 devops.write(packet);
 595                 return;
 596         }
 597
 598         ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
 599                            packet->len, n->name, n->hostname);
 600
 601         if(!n->status.reachable) {
 602                 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 603                                    n->name, n->hostname);
 604                 return;
 605         }
 606
 607         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 608
 609         if(via != n)
 610                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
 611                            n->name, via->name, n->via->hostname);
 612
 613         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 614                 if(!send_tcppacket(via->connection, packet))
 615                         terminate_connection(via->connection, true);
 616         } else
 617                 send_udppacket(via, packet);
 618 }
 619
 620 /* Broadcast a packet using the minimum spanning tree */
 621
 622 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 623         avl_node_t *node;
 624         connection_t *c;
 625         node_t *n;
 626
 627         // Always give ourself a copy of the packet.
 628         if(from != myself)
 629                 send_packet(myself, packet);
 630
 631         // In TunnelServer mode, do not forward broadcast packets.
 632         // The MST might not be valid and create loops.
 633         if(tunnelserver || broadcast_mode == BMODE_NONE)
 634                 return;
 635
 636         ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
 637                            packet->len, from->name, from->hostname);
 638
 639         switch(broadcast_mode) {
 640                 // In MST mode, broadcast packets travel via the Minimum Spanning Tree.
 641                 // This guarantees all nodes receive the broadcast packet, and
 642                 // usually distributes the sending of broadcast packets over all nodes.
 643                 case BMODE_MST:
 644                         for(node = connection_tree->head; node; node = node->next) {
 645                                 c = node->data;
 646
 647                                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 648                                         send_packet(c->node, packet);
 649                         }
 650                         break;
 651
 652                 // In direct mode, we send copies to each node we know of.
 653                 // However, this only reaches nodes that can be reached in a single hop.
 654                 // We don't have enough information to forward broadcast packets in this case.
 655                 case BMODE_DIRECT:
 656                         if(from != myself)
 657                                 break;
 658
 659                         for(node = node_udp_tree->head; node; node = node->next) {
 660                                 n = node->data;
 661
 662                                 if(n->status.reachable && n != myself && ((n->via == myself && n->nexthop == n) || n->via == n))
 663                                         send_packet(n, packet);
 664                         }
 665                         break;
 666
 667                 default:
 668                         break;
 669         }
 670 }
 671
 672 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 673         avl_node_t *node;
 674         edge_t *e;
 675         node_t *n = NULL;
 676         static time_t last_hard_try = 0;
 677
 678         for(node = edge_weight_tree->head; node; node = node->next) {
 679                 e = node->data;
 680
 681                 if(e->to == myself)
 682                         continue;
 683
 684                 if(last_hard_try == now && sockaddrcmp_noport(from, &e->address))
 685                         continue;
 686
 687                 if(!try_mac(e->to, pkt))
 688                         continue;
 689
 690                 n = e->to;
 691                 break;
 692         }
 693
 694         last_hard_try = now;
 695         return n;
 696 }
 697
 698 void handle_incoming_vpn_data(int sock) {
 699         vpn_packet_t pkt;
 700         char *hostname;
 701         sockaddr_t from;
 702         socklen_t fromlen = sizeof(from);
 703         node_t *n;
 704
 705         pkt.len = recvfrom(listen_socket[sock].udp, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 706
 707         if(pkt.len < 0) {
 708                 if(!sockwouldblock(sockerrno))
 709                         logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 710                 return;
 711         }
 712
 713         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 714
 715         n = lookup_node_udp(&from);
 716
 717         if(!n) {
 718                 n = try_harder(&from, &pkt);
 719                 if(n)
 720                         update_node_udp(n, &from);
 721                 else ifdebug(PROTOCOL) {
 722                         hostname = sockaddr2hostname(&from);
 723                         logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 724                         free(hostname);
 725                         return;
 726                 }
 727                 else
 728                         return;
 729         }
 730
 731         n->sock = sock;
 732
 733         receive_udppacket(n, &pkt);
 734 }