src/net_packet.c

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 Ivo Timmermans,
   4                   2000-2010 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 "list.h"
  47 #include "logger.h"
  48 #include "net.h"
  49 #include "netutl.h"
  50 #include "protocol.h"
  51 #include "process.h"
  52 #include "route.h"
  53 #include "utils.h"
  54 #include "xalloc.h"
  55
  56 int keylifetime = 0;
  57 int keyexpires = 0;
  58 #ifdef HAVE_LZO
  59 static char lzo_wrkmem[LZO1X_999_MEM_COMPRESS > LZO1X_1_MEM_COMPRESS ? LZO1X_999_MEM_COMPRESS : LZO1X_1_MEM_COMPRESS];
  60 #endif
  61
  62 static void send_udppacket(node_t *, vpn_packet_t *);
  63
  64 unsigned replaywin = 16;
  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 void send_mtu_probe(node_t *n) {
  74         vpn_packet_t packet;
  75         int len, i;
  76         int timeout = 1;
  77
  78         n->mtuprobes++;
  79         n->mtuevent = NULL;
  80
  81         if(!n->status.reachable || !n->status.validkey) {
  82                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
  83                 n->mtuprobes = 0;
  84                 return;
  85         }
  86
  87         if(n->mtuprobes > 32) {
  88                 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
  89                 n->mtuprobes = 1;
  90                 n->minmtu = 0;
  91                 n->maxmtu = MTU;
  92         }
  93
  94         if(n->mtuprobes >= 10 && !n->minmtu) {
  95                 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
  96                 n->mtuprobes = 0;
  97                 return;
  98         }
  99
 100         if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
 101                 if(n->minmtu > n->maxmtu)
 102                         n->minmtu = n->maxmtu;
 103                 else
 104                         n->maxmtu = n->minmtu;
 105                 n->mtu = n->minmtu;
 106                 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
 107                 n->mtuprobes = 31;
 108         }
 109
 110         if(n->mtuprobes == 31) {
 111                 timeout = pinginterval;
 112                 goto end;
 113         } else if(n->mtuprobes == 32) {
 114                 timeout = pingtimeout;
 115         }
 116
 117         for(i = 0; i < 3; i++) {
 118                 if(n->maxmtu <= n->minmtu)
 119                         len = n->maxmtu;
 120                 else
 121                         len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
 122
 123                 if(len < 64)
 124                         len = 64;
 125
 126                 memset(packet.data, 0, 14);
 127                 RAND_pseudo_bytes(packet.data + 14, len - 14);
 128                 packet.len = len;
 129                 packet.priority = 0;
 130
 131                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 132
 133                 send_udppacket(n, &packet);
 134         }
 135
 136 end:
 137         n->mtuevent = new_event();
 138         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 139         n->mtuevent->data = n;
 140         n->mtuevent->time = now + timeout;
 141         event_add(n->mtuevent);
 142 }
 143
 144 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 145         ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
 146
 147         if(!packet->data[0]) {
 148                 packet->data[0] = 1;
 149                 send_udppacket(n, packet);
 150         } else {
 151                 if(len > n->maxmtu)
 152                         len = n->maxmtu;
 153                 if(n->minmtu < len)
 154                         n->minmtu = len;
 155                 if(n->mtuprobes > 30)
 156                         n->mtuprobes = 30;
 157         }
 158 }
 159
 160 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 161         if(level == 0) {
 162                 memcpy(dest, source, len);
 163                 return len;
 164         } else if(level == 10) {
 165 #ifdef HAVE_LZO
 166                 lzo_uint lzolen = MAXSIZE;
 167                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 168                 return lzolen;
 169 #else
 170                 return -1;
 171 #endif
 172         } else if(level < 10) {
 173 #ifdef HAVE_ZLIB
 174                 unsigned long destlen = MAXSIZE;
 175                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 176                         return destlen;
 177                 else
 178 #endif
 179                         return -1;
 180         } else {
 181 #ifdef HAVE_LZO
 182                 lzo_uint lzolen = MAXSIZE;
 183                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 184                 return lzolen;
 185 #else
 186                 return -1;
 187 #endif
 188         }
 189
 190         return -1;
 191 }
 192
 193 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 194         if(level == 0) {
 195                 memcpy(dest, source, len);
 196                 return len;
 197         } else if(level > 9) {
 198 #ifdef HAVE_LZO
 199                 lzo_uint lzolen = MAXSIZE;
 200                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 201                         return lzolen;
 202                 else
 203 #endif
 204                         return -1;
 205         }
 206 #ifdef HAVE_ZLIB
 207         else {
 208                 unsigned long destlen = MAXSIZE;
 209                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 210                         return destlen;
 211                 else
 212                         return -1;
 213         }
 214 #endif
 215
 216         return -1;
 217 }
 218
 219 /* VPN packet I/O */
 220
 221 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 222         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
 223                            packet->len, n->name, n->hostname);
 224
 225         route(n, packet);
 226 }
 227
 228 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
 229         unsigned char hmac[EVP_MAX_MD_SIZE];
 230
 231         if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 232                 return false;
 233
 234         HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
 235
 236         return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
 237 }
 238
 239 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 240         vpn_packet_t pkt1, pkt2;
 241         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 242         int nextpkt = 0;
 243         vpn_packet_t *outpkt = pkt[0];
 244         int outlen, outpad;
 245         unsigned char hmac[EVP_MAX_MD_SIZE];
 246         int i;
 247
 248         if(!n->inkey) {
 249                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
 250                                         n->name, n->hostname);
 251                 return;
 252         }
 253
 254         /* Check packet length */
 255
 256         if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
 257                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
 258                                         n->name, n->hostname);
 259                 return;
 260         }
 261
 262         /* Check the message authentication code */
 263
 264         if(n->indigest && n->inmaclength) {
 265                 inpkt->len -= n->inmaclength;
 266                 HMAC(n->indigest, n->inkey, n->inkeylength,
 267                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 268
 269                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
 270                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
 271                                            n->name, n->hostname);
 272                         return;
 273                 }
 274         }
 275
 276         /* Decrypt the packet */
 277
 278         if(n->incipher) {
 279                 outpkt = pkt[nextpkt++];
 280
 281                 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
 282                                 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
 283                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 284                                 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 285                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
 286                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 287                         return;
 288                 }
 289
 290                 outpkt->len = outlen + outpad;
 291                 inpkt = outpkt;
 292         }
 293
 294         /* Check the sequence number */
 295
 296         inpkt->len -= sizeof(inpkt->seqno);
 297         inpkt->seqno = ntohl(inpkt->seqno);
 298
 299         if(replaywin) {
 300                 if(inpkt->seqno != n->received_seqno + 1) {
 301                         if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
 302                                 if(n->farfuture++ < replaywin >> 2) {
 303                                         logger(LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)",
 304                                                 n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture);
 305                                         return;
 306                                 }
 307                                 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
 308                                                 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 309                                 memset(n->late, 0, replaywin);
 310                         } else if (inpkt->seqno <= n->received_seqno) {
 311                                 if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
 312                                         logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
 313                                                 n->name, n->hostname, inpkt->seqno, n->received_seqno);
 314                                         return;
 315                                 }
 316                         } else {
 317                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 318                                         n->late[(i / 8) % replaywin] |= 1 << i % 8;
 319                         }
 320                 }
 321
 322                 n->farfuture = 0;
 323                 n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
 324         }
 325
 326         if(inpkt->seqno > n->received_seqno)
 327                 n->received_seqno = inpkt->seqno;
 328
 329         if(n->received_seqno > MAX_SEQNO)
 330                 keyexpires = 0;
 331
 332         /* Decompress the packet */
 333
 334         length_t origlen = inpkt->len;
 335
 336         if(n->incompression) {
 337                 outpkt = pkt[nextpkt++];
 338
 339                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 340                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
 341                                                  n->name, n->hostname);
 342                         return;
 343                 }
 344
 345                 inpkt = outpkt;
 346
 347                 origlen -= MTU/64 + 20;
 348         }
 349
 350         inpkt->priority = 0;
 351
 352         if(!inpkt->data[12] && !inpkt->data[13])
 353                 mtu_probe_h(n, inpkt, origlen);
 354         else
 355                 receive_packet(n, inpkt);
 356 }
 357
 358 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 359         vpn_packet_t outpkt;
 360
 361         outpkt.len = len;
 362         if(c->options & OPTION_TCPONLY)
 363                 outpkt.priority = 0;
 364         else
 365                 outpkt.priority = -1;
 366         memcpy(outpkt.data, buffer, len);
 367
 368         receive_packet(c->node, &outpkt);
 369 }
 370
 371 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 372         vpn_packet_t pkt1, pkt2;
 373         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 374         vpn_packet_t *inpkt = origpkt;
 375         int nextpkt = 0;
 376         vpn_packet_t *outpkt;
 377         int origlen;
 378         int outlen, outpad;
 379 #if defined(SOL_IP) && defined(IP_TOS)
 380         static int priority = 0;
 381 #endif
 382         int origpriority;
 383         int sock;
 384
 385         if(!n->status.reachable) {
 386                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
 387                 return;
 388         }
 389
 390         /* Make sure we have a valid key */
 391
 392         if(!n->status.validkey) {
 393                 ifdebug(TRAFFIC) logger(LOG_INFO,
 394                                    "No valid key known yet for %s (%s), forwarding via TCP",
 395                                    n->name, n->hostname);
 396
 397                 if(n->last_req_key + 10 < now) {
 398                         send_req_key(n);
 399                         n->last_req_key = now;
 400                 }
 401
 402                 send_tcppacket(n->nexthop->connection, origpkt);
 403
 404                 return;
 405         }
 406
 407         if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 408                 ifdebug(TRAFFIC) logger(LOG_INFO,
 409                                 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
 410                                 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 411
 412                 if(n != n->nexthop)
 413                         send_packet(n->nexthop, origpkt);
 414                 else
 415                         send_tcppacket(n->nexthop->connection, origpkt);
 416
 417                 return;
 418         }
 419
 420         origlen = inpkt->len;
 421         origpriority = inpkt->priority;
 422
 423         /* Compress the packet */
 424
 425         if(n->outcompression) {
 426                 outpkt = pkt[nextpkt++];
 427
 428                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 429                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
 430                                    n->name, n->hostname);
 431                         return;
 432                 }
 433
 434                 inpkt = outpkt;
 435         }
 436
 437         /* Add sequence number */
 438
 439         inpkt->seqno = htonl(++(n->sent_seqno));
 440         inpkt->len += sizeof(inpkt->seqno);
 441
 442         /* Encrypt the packet */
 443
 444         if(n->outcipher) {
 445                 outpkt = pkt[nextpkt++];
 446
 447                 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
 448                                 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
 449                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 450                                 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 451                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
 452                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 453                         goto end;
 454                 }
 455
 456                 outpkt->len = outlen + outpad;
 457                 inpkt = outpkt;
 458         }
 459
 460         /* Add the message authentication code */
 461
 462         if(n->outdigest && n->outmaclength) {
 463                 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
 464                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 465                 inpkt->len += n->outmaclength;
 466         }
 467
 468         /* Determine which socket we have to use */
 469
 470         for(sock = 0; sock < listen_sockets; sock++)
 471                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 472                         break;
 473
 474         if(sock >= listen_sockets)
 475                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 476
 477         /* Send the packet */
 478
 479 #if defined(SOL_IP) && defined(IP_TOS)
 480         if(priorityinheritance && origpriority != priority
 481            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 482                 priority = origpriority;
 483                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
 484                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 485                         logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 486         }
 487 #endif
 488
 489         if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
 490                 if(sockmsgsize(sockerrno)) {
 491                         if(n->maxmtu >= origlen)
 492                                 n->maxmtu = origlen - 1;
 493                         if(n->mtu >= origlen)
 494                                 n->mtu = origlen - 1;
 495                 } else
 496                         logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 497         }
 498
 499 end:
 500         origpkt->len = origlen;
 501 }
 502
 503 /*
 504   send a packet to the given vpn ip.
 505 */
 506 void send_packet(const node_t *n, vpn_packet_t *packet) {
 507         node_t *via;
 508
 509         if(n == myself) {
 510                 if(overwrite_mac)
 511                          memcpy(packet->data, mymac.x, ETH_ALEN);
 512                 write_packet(packet);
 513                 return;
 514         }
 515
 516         ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
 517                            packet->len, n->name, n->hostname);
 518
 519         if(!n->status.reachable) {
 520                 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 521                                    n->name, n->hostname);
 522                 return;
 523         }
 524
 525         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 526
 527         if(via != n)
 528                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
 529                            n->name, via->name, n->via->hostname);
 530
 531         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 532                 if(!send_tcppacket(via->connection, packet))
 533                         terminate_connection(via->connection, true);
 534         } else
 535                 send_udppacket(via, packet);
 536 }
 537
 538 /* Broadcast a packet using the minimum spanning tree */
 539
 540 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 541         avl_node_t *node;
 542         connection_t *c;
 543
 544         ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
 545                            packet->len, from->name, from->hostname);
 546
 547         if(from != myself) {
 548                 send_packet(myself, packet);
 549
 550                 // In TunnelServer mode, do not forward broadcast packets.
 551                 // The MST might not be valid and create loops.
 552                 if(tunnelserver)
 553                         return;
 554         }
 555
 556         for(node = connection_tree->head; node; node = node->next) {
 557                 c = node->data;
 558
 559                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 560                         send_packet(c->node, packet);
 561         }
 562 }
 563
 564 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 565         avl_node_t *node;
 566         edge_t *e;
 567         node_t *n = NULL;
 568         static time_t last_hard_try = 0;
 569
 570         for(node = edge_weight_tree->head; node; node = node->next) {
 571                 e = node->data;
 572
 573                 if(sockaddrcmp_noport(from, &e->address)) {
 574                         if(last_hard_try == now)
 575                                 continue;
 576                         last_hard_try = now;
 577                 }
 578
 579                 if(!n)
 580                         n = e->to;
 581
 582                 if(!try_mac(e->to, pkt))
 583                         continue;
 584
 585                 n = e->to;
 586                 break;
 587         }
 588
 589         return n;
 590 }
 591
 592 void handle_incoming_vpn_data(int sock) {
 593         vpn_packet_t pkt;
 594         char *hostname;
 595         sockaddr_t from;
 596         socklen_t fromlen = sizeof(from);
 597         node_t *n;
 598
 599         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 600
 601         if(pkt.len < 0) {
 602                 if(!sockwouldblock(sockerrno))
 603                         logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 604                 return;
 605         }
 606
 607         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 608
 609         n = lookup_node_udp(&from);
 610
 611         if(!n) {
 612                 n = try_harder(&from, &pkt);
 613                 if(n)
 614                         update_node_udp(n, &from);
 615                 else ifdebug(PROTOCOL) {
 616                         hostname = sockaddr2hostname(&from);
 617                         logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 618                         free(hostname);
 619                         return;
 620                 }
 621                 else
 622                         return;
 623         }
 624
 625         receive_udppacket(n, &pkt);
 626 }