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                   2000-2010 Guus Sliepen <guus@tinc-vpn.org>
   5                   2010      Timothy Redaelli <timothy@redaelli.eu>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License along
  18     with this program; if not, write to the Free Software Foundation, Inc.,
  19     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  20 */
  21
  22 #include "system.h"
  23
  24 #include <openssl/rand.h>
  25 #include <openssl/err.h>
  26 #include <openssl/evp.h>
  27 #include <openssl/pem.h>
  28 #include <openssl/hmac.h>
  29
  30 #ifdef HAVE_ZLIB
  31 #include <zlib.h>
  32 #endif
  33
  34 #ifdef HAVE_LZO
  35 #include LZO1X_H
  36 #endif
  37
  38 #include "avl_tree.h"
  39 #include "conf.h"
  40 #include "connection.h"
  41 #include "device.h"
  42 #include "ethernet.h"
  43 #include "event.h"
  44 #include "graph.h"
  45 #include "list.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
  65 #define MAX_SEQNO 1073741824
  66
  67 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
  68 // mtuprobes ==    31: sleep pinginterval seconds
  69 // mtuprobes ==    32: send 1 burst, sleep pingtimeout second
  70 // mtuprobes ==    33: no response from other side, restart PMTU discovery process
  71
  72 void send_mtu_probe(node_t *n) {
  73         vpn_packet_t packet;
  74         int len, i;
  75         int timeout = 1;
  76
  77         n->mtuprobes++;
  78         n->mtuevent = NULL;
  79
  80         if(!n->status.reachable || !n->status.validkey) {
  81                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
  82                 n->mtuprobes = 0;
  83                 return;
  84         }
  85
  86         if(n->mtuprobes > 32) {
  87                 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
  88                 n->mtuprobes = 1;
  89                 n->minmtu = 0;
  90                 n->maxmtu = MTU;
  91         }
  92
  93         if(n->mtuprobes >= 10 && !n->minmtu) {
  94                 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
  95                 n->mtuprobes = 0;
  96                 return;
  97         }
  98
  99         if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
 100                 if(n->minmtu > n->maxmtu)
 101                         n->minmtu = n->maxmtu;
 102                 else
 103                         n->maxmtu = n->minmtu;
 104                 n->mtu = n->minmtu;
 105                 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
 106                 n->mtuprobes = 31;
 107         }
 108
 109         if(n->mtuprobes == 31) {
 110                 timeout = pinginterval;
 111                 goto end;
 112         } else if(n->mtuprobes == 32) {
 113                 timeout = pingtimeout;
 114         }
 115
 116         for(i = 0; i < 3; i++) {
 117                 if(n->maxmtu <= n->minmtu)
 118                         len = n->maxmtu;
 119                 else
 120                         len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
 121
 122                 if(len < 64)
 123                         len = 64;
 124
 125                 memset(packet.data, 0, 14);
 126                 RAND_pseudo_bytes(packet.data + 14, len - 14);
 127                 packet.len = len;
 128                 packet.priority = 0;
 129
 130                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 131
 132                 send_udppacket(n, &packet);
 133         }
 134
 135 end:
 136         n->mtuevent = new_event();
 137         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 138         n->mtuevent->data = n;
 139         n->mtuevent->time = now + timeout;
 140         event_add(n->mtuevent);
 141 }
 142
 143 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 144         ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
 145
 146         if(!packet->data[0]) {
 147                 packet->data[0] = 1;
 148                 send_udppacket(n, packet);
 149         } else {
 150                 if(len > n->maxmtu)
 151                         len = n->maxmtu;
 152                 if(n->minmtu < len)
 153                         n->minmtu = len;
 154                 if(n->mtuprobes > 30)
 155                         n->mtuprobes = 30;
 156         }
 157 }
 158
 159 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 160         if(level == 0) {
 161                 memcpy(dest, source, len);
 162                 return len;
 163         } else if(level == 10) {
 164 #ifdef HAVE_LZO
 165                 lzo_uint lzolen = MAXSIZE;
 166                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 167                 return lzolen;
 168 #else
 169                 return -1;
 170 #endif
 171         } else if(level < 10) {
 172 #ifdef HAVE_ZLIB
 173                 unsigned long destlen = MAXSIZE;
 174                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 175                         return destlen;
 176                 else
 177 #endif
 178                         return -1;
 179         } else {
 180 #ifdef HAVE_LZO
 181                 lzo_uint lzolen = MAXSIZE;
 182                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 183                 return lzolen;
 184 #else
 185                 return -1;
 186 #endif
 187         }
 188
 189         return -1;
 190 }
 191
 192 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 193         if(level == 0) {
 194                 memcpy(dest, source, len);
 195                 return len;
 196         } else if(level > 9) {
 197 #ifdef HAVE_LZO
 198                 lzo_uint lzolen = MAXSIZE;
 199                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 200                         return lzolen;
 201                 else
 202 #endif
 203                         return -1;
 204         }
 205 #ifdef HAVE_ZLIB
 206         else {
 207                 unsigned long destlen = MAXSIZE;
 208                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 209                         return destlen;
 210                 else
 211                         return -1;
 212         }
 213 #endif
 214
 215         return -1;
 216 }
 217
 218 /* VPN packet I/O */
 219
 220 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 221         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
 222                            packet->len, n->name, n->hostname);
 223
 224         route(n, packet);
 225 }
 226
 227 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
 228         unsigned char hmac[EVP_MAX_MD_SIZE];
 229
 230         if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 231                 return false;
 232
 233         HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
 234
 235         return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
 236 }
 237
 238 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 239         vpn_packet_t pkt1, pkt2;
 240         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 241         int nextpkt = 0;
 242         vpn_packet_t *outpkt = pkt[0];
 243         int outlen, outpad;
 244         unsigned char hmac[EVP_MAX_MD_SIZE];
 245         int i;
 246
 247         if(!n->inkey) {
 248                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
 249                                         n->name, n->hostname);
 250                 return;
 251         }
 252
 253         /* Check packet length */
 254
 255         if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
 256                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
 257                                         n->name, n->hostname);
 258                 return;
 259         }
 260
 261         /* Check the message authentication code */
 262
 263         if(n->indigest && n->inmaclength) {
 264                 inpkt->len -= n->inmaclength;
 265                 HMAC(n->indigest, n->inkey, n->inkeylength,
 266                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 267
 268                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
 269                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
 270                                            n->name, n->hostname);
 271                         return;
 272                 }
 273         }
 274
 275         /* Decrypt the packet */
 276
 277         if(n->incipher) {
 278                 outpkt = pkt[nextpkt++];
 279
 280                 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
 281                                 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
 282                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 283                                 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 284                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
 285                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 286                         return;
 287                 }
 288
 289                 outpkt->len = outlen + outpad;
 290                 inpkt = outpkt;
 291         }
 292
 293         /* Check the sequence number */
 294
 295         inpkt->len -= sizeof(inpkt->seqno);
 296         inpkt->seqno = ntohl(inpkt->seqno);
 297
 298         if(replaywin) {
 299                 if(inpkt->seqno != n->received_seqno + 1) {
 300                         if(inpkt->seqno >= n->received_seqno + replaywin * 8) {
 301                                 if(n->farfuture++ < replaywin >> 2) {
 302                                         logger(LOG_WARNING, "Packet from %s (%s) is %d seqs in the future, dropped (%u)",
 303                                                 n->name, n->hostname, inpkt->seqno - n->received_seqno - 1, n->farfuture);
 304                                         return;
 305                                 }
 306                                 logger(LOG_WARNING, "Lost %d packets from %s (%s)",
 307                                                 inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 308                                 memset(n->late, 0, replaywin);
 309                         } else if (inpkt->seqno <= n->received_seqno) {
 310                                 if((n->received_seqno >= replaywin * 8 && inpkt->seqno <= n->received_seqno - replaywin * 8) || !(n->late[(inpkt->seqno / 8) % replaywin] & (1 << inpkt->seqno % 8))) {
 311                                         logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
 312                                                 n->name, n->hostname, inpkt->seqno, n->received_seqno);
 313                                         return;
 314                                 }
 315                         } else {
 316                                 for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 317                                         n->late[(i / 8) % replaywin] |= 1 << i % 8;
 318                         }
 319                 }
 320
 321                 n->farfuture = 0;
 322                 n->late[(inpkt->seqno / 8) % replaywin] &= ~(1 << inpkt->seqno % 8);
 323         }
 324
 325         if(inpkt->seqno > n->received_seqno)
 326                 n->received_seqno = inpkt->seqno;
 327
 328         if(n->received_seqno > MAX_SEQNO)
 329                 keyexpires = 0;
 330
 331         /* Decompress the packet */
 332
 333         length_t origlen = inpkt->len;
 334
 335         if(n->incompression) {
 336                 outpkt = pkt[nextpkt++];
 337
 338                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 339                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
 340                                                  n->name, n->hostname);
 341                         return;
 342                 }
 343
 344                 inpkt = outpkt;
 345
 346                 origlen -= MTU/64 + 20;
 347         }
 348
 349         inpkt->priority = 0;
 350
 351         if(!inpkt->data[12] && !inpkt->data[13])
 352                 mtu_probe_h(n, inpkt, origlen);
 353         else
 354                 receive_packet(n, inpkt);
 355 }
 356
 357 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 358         vpn_packet_t outpkt;
 359
 360         outpkt.len = len;
 361         if(c->options & OPTION_TCPONLY)
 362                 outpkt.priority = 0;
 363         else
 364                 outpkt.priority = -1;
 365         memcpy(outpkt.data, buffer, len);
 366
 367         receive_packet(c->node, &outpkt);
 368 }
 369
 370 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 371         vpn_packet_t pkt1, pkt2;
 372         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 373         vpn_packet_t *inpkt = origpkt;
 374         int nextpkt = 0;
 375         vpn_packet_t *outpkt;
 376         int origlen;
 377         int outlen, outpad;
 378 #if defined(SOL_IP) && defined(IP_TOS)
 379         static int priority = 0;
 380 #endif
 381         int origpriority;
 382         int sock;
 383
 384         if(!n->status.reachable) {
 385                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
 386                 return;
 387         }
 388
 389         /* Make sure we have a valid key */
 390
 391         if(!n->status.validkey) {
 392                 ifdebug(TRAFFIC) logger(LOG_INFO,
 393                                    "No valid key known yet for %s (%s), forwarding via TCP",
 394                                    n->name, n->hostname);
 395
 396                 if(n->last_req_key + 10 < now) {
 397                         send_req_key(n);
 398                         n->last_req_key = now;
 399                 }
 400
 401                 send_tcppacket(n->nexthop->connection, origpkt);
 402
 403                 return;
 404         }
 405
 406         if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 407                 ifdebug(TRAFFIC) logger(LOG_INFO,
 408                                 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
 409                                 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 410
 411                 if(n != n->nexthop)
 412                         send_packet(n->nexthop, origpkt);
 413                 else
 414                         send_tcppacket(n->nexthop->connection, origpkt);
 415
 416                 return;
 417         }
 418
 419         origlen = inpkt->len;
 420         origpriority = inpkt->priority;
 421
 422         /* Compress the packet */
 423
 424         if(n->outcompression) {
 425                 outpkt = pkt[nextpkt++];
 426
 427                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 428                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
 429                                    n->name, n->hostname);
 430                         return;
 431                 }
 432
 433                 inpkt = outpkt;
 434         }
 435
 436         /* Add sequence number */
 437
 438         inpkt->seqno = htonl(++(n->sent_seqno));
 439         inpkt->len += sizeof(inpkt->seqno);
 440
 441         /* Encrypt the packet */
 442
 443         if(n->outcipher) {
 444                 outpkt = pkt[nextpkt++];
 445
 446                 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
 447                                 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
 448                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 449                                 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 450                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
 451                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 452                         goto end;
 453                 }
 454
 455                 outpkt->len = outlen + outpad;
 456                 inpkt = outpkt;
 457         }
 458
 459         /* Add the message authentication code */
 460
 461         if(n->outdigest && n->outmaclength) {
 462                 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
 463                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 464                 inpkt->len += n->outmaclength;
 465         }
 466
 467         /* Determine which socket we have to use */
 468
 469         for(sock = 0; sock < listen_sockets; sock++)
 470                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 471                         break;
 472
 473         if(sock >= listen_sockets)
 474                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 475
 476         /* Send the packet */
 477
 478 #if defined(SOL_IP) && defined(IP_TOS)
 479         if(priorityinheritance && origpriority != priority
 480            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 481                 priority = origpriority;
 482                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
 483                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 484                         logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 485         }
 486 #endif
 487
 488         if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
 489                 if(sockmsgsize(sockerrno)) {
 490                         if(n->maxmtu >= origlen)
 491                                 n->maxmtu = origlen - 1;
 492                         if(n->mtu >= origlen)
 493                                 n->mtu = origlen - 1;
 494                 } else
 495                         logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 496         }
 497
 498 end:
 499         origpkt->len = origlen;
 500 }
 501
 502 /*
 503   send a packet to the given vpn ip.
 504 */
 505 void send_packet(const node_t *n, vpn_packet_t *packet) {
 506         node_t *via;
 507
 508         if(n == myself) {
 509                 if(overwrite_mac)
 510                          memcpy(packet->data, mymac.x, ETH_ALEN);
 511                 write_packet(packet);
 512                 return;
 513         }
 514
 515         ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
 516                            packet->len, n->name, n->hostname);
 517
 518         if(!n->status.reachable) {
 519                 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 520                                    n->name, n->hostname);
 521                 return;
 522         }
 523
 524         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 525
 526         if(via != n)
 527                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
 528                            n->name, via->name, n->via->hostname);
 529
 530         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 531                 if(!send_tcppacket(via->connection, packet))
 532                         terminate_connection(via->connection, true);
 533         } else
 534                 send_udppacket(via, packet);
 535 }
 536
 537 /* Broadcast a packet using the minimum spanning tree */
 538
 539 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 540         avl_node_t *node;
 541         connection_t *c;
 542
 543         ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
 544                            packet->len, from->name, from->hostname);
 545
 546         if(from != myself) {
 547                 send_packet(myself, packet);
 548
 549                 // In TunnelServer mode, do not forward broadcast packets.
 550                 // The MST might not be valid and create loops.
 551                 if(tunnelserver)
 552                         return;
 553         }
 554
 555         for(node = connection_tree->head; node; node = node->next) {
 556                 c = node->data;
 557
 558                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 559                         send_packet(c->node, packet);
 560         }
 561 }
 562
 563 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 564         avl_node_t *node;
 565         edge_t *e;
 566         node_t *n = NULL;
 567         static time_t last_hard_try = 0;
 568
 569         for(node = edge_weight_tree->head; node; node = node->next) {
 570                 e = node->data;
 571
 572                 if(sockaddrcmp_noport(from, &e->address)) {
 573                         if(last_hard_try == now)
 574                                 continue;
 575                         last_hard_try = now;
 576                 }
 577
 578                 if(!n)
 579                         n = e->to;
 580
 581                 if(!try_mac(e->to, pkt))
 582                         continue;
 583
 584                 n = e->to;
 585                 break;
 586         }
 587
 588         return n;
 589 }
 590
 591 void handle_incoming_vpn_data(int sock) {
 592         vpn_packet_t pkt;
 593         char *hostname;
 594         sockaddr_t from;
 595         socklen_t fromlen = sizeof(from);
 596         node_t *n;
 597
 598         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 599
 600         if(pkt.len < 0) {
 601                 if(!sockwouldblock(sockerrno))
 602                         logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 603                 return;
 604         }
 605
 606         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 607
 608         n = lookup_node_udp(&from);
 609
 610         if(!n) {
 611                 n = try_harder(&from, &pkt);
 612                 if(n)
 613                         update_node_udp(n, &from);
 614                 else ifdebug(PROTOCOL) {
 615                         hostname = sockaddr2hostname(&from);
 616                         logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 617                         free(hostname);
 618                         return;
 619                 }
 620                 else
 621                         return;
 622         }
 623
 624         receive_udppacket(n, &pkt);
 625 }