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

   1 /*
   2     net_packet.c -- Handles in- and outgoing VPN packets
   3     Copyright (C) 1998-2005 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 #define MAX_SEQNO 1073741824
  64
  65 // mtuprobes == 1..30: initial discovery, send bursts with 1 second interval
  66 // mtuprobes ==    31: sleep pinginterval seconds
  67 // mtuprobes ==    32: send 1 burst, sleep pingtimeout second
  68 // mtuprobes ==    33: no response from other side, restart PMTU discovery process
  69
  70 void send_mtu_probe(node_t *n) {
  71         vpn_packet_t packet;
  72         int len, i;
  73         int timeout = 1;
  74
  75         n->mtuprobes++;
  76         n->mtuevent = NULL;
  77
  78         if(!n->status.reachable || !n->status.validkey) {
  79                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send MTU probe to unreachable or rekeying node %s (%s)", n->name, n->hostname);
  80                 n->mtuprobes = 0;
  81                 return;
  82         }
  83
  84         if(n->mtuprobes > 32) {
  85                 ifdebug(TRAFFIC) logger(LOG_INFO, "%s (%s) did not respond to UDP ping, restarting PMTU discovery", n->name, n->hostname);
  86                 n->mtuprobes = 1;
  87                 n->minmtu = 0;
  88                 n->maxmtu = MTU;
  89         }
  90
  91         if(n->mtuprobes >= 10 && !n->minmtu) {
  92                 ifdebug(TRAFFIC) logger(LOG_INFO, "No response to MTU probes from %s (%s)", n->name, n->hostname);
  93                 n->mtuprobes = 0;
  94                 return;
  95         }
  96
  97         if(n->mtuprobes == 30 || (n->mtuprobes < 30 && n->minmtu >= n->maxmtu)) {
  98                 if(n->minmtu > n->maxmtu)
  99                         n->minmtu = n->maxmtu;
 100                 else
 101                         n->maxmtu = n->minmtu;
 102                 n->mtu = n->minmtu;
 103                 ifdebug(TRAFFIC) logger(LOG_INFO, "Fixing MTU of %s (%s) to %d after %d probes", n->name, n->hostname, n->mtu, n->mtuprobes);
 104                 n->mtuprobes = 31;
 105         }
 106
 107         if(n->mtuprobes == 31) {
 108                 timeout = pinginterval;
 109                 goto end;
 110         } else if(n->mtuprobes == 32) {
 111                 timeout = pingtimeout;
 112         }
 113
 114         for(i = 0; i < 3; i++) {
 115                 if(n->maxmtu <= n->minmtu)
 116                         len = n->maxmtu;
 117                 else
 118                         len = n->minmtu + 1 + rand() % (n->maxmtu - n->minmtu);
 119
 120                 if(len < 64)
 121                         len = 64;
 122
 123                 memset(packet.data, 0, 14);
 124                 RAND_pseudo_bytes(packet.data + 14, len - 14);
 125                 packet.len = len;
 126                 packet.priority = 0;
 127
 128                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending MTU probe length %d to %s (%s)", len, n->name, n->hostname);
 129
 130                 send_udppacket(n, &packet);
 131         }
 132
 133 end:
 134         n->mtuevent = new_event();
 135         n->mtuevent->handler = (event_handler_t)send_mtu_probe;
 136         n->mtuevent->data = n;
 137         n->mtuevent->time = now + timeout;
 138         event_add(n->mtuevent);
 139 }
 140
 141 void mtu_probe_h(node_t *n, vpn_packet_t *packet, length_t len) {
 142         ifdebug(TRAFFIC) logger(LOG_INFO, "Got MTU probe length %d from %s (%s)", packet->len, n->name, n->hostname);
 143
 144         if(!packet->data[0]) {
 145                 packet->data[0] = 1;
 146                 send_udppacket(n, packet);
 147         } else {
 148                 if(len > n->maxmtu)
 149                         len = n->maxmtu;
 150                 if(n->minmtu < len)
 151                         n->minmtu = len;
 152                 if(n->mtuprobes > 30)
 153                         n->mtuprobes = 30;
 154         }
 155 }
 156
 157 static length_t compress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 158         if(level == 0) {
 159                 memcpy(dest, source, len);
 160                 return len;
 161         } else if(level == 10) {
 162 #ifdef HAVE_LZO
 163                 lzo_uint lzolen = MAXSIZE;
 164                 lzo1x_1_compress(source, len, dest, &lzolen, lzo_wrkmem);
 165                 return lzolen;
 166 #else
 167                 return -1;
 168 #endif
 169         } else if(level < 10) {
 170 #ifdef HAVE_ZLIB
 171                 unsigned long destlen = MAXSIZE;
 172                 if(compress2(dest, &destlen, source, len, level) == Z_OK)
 173                         return destlen;
 174                 else
 175 #endif
 176                         return -1;
 177         } else {
 178 #ifdef HAVE_LZO
 179                 lzo_uint lzolen = MAXSIZE;
 180                 lzo1x_999_compress(source, len, dest, &lzolen, lzo_wrkmem);
 181                 return lzolen;
 182 #else
 183                 return -1;
 184 #endif
 185         }
 186
 187         return -1;
 188 }
 189
 190 static length_t uncompress_packet(uint8_t *dest, const uint8_t *source, length_t len, int level) {
 191         if(level == 0) {
 192                 memcpy(dest, source, len);
 193                 return len;
 194         } else if(level > 9) {
 195 #ifdef HAVE_LZO
 196                 lzo_uint lzolen = MAXSIZE;
 197                 if(lzo1x_decompress_safe(source, len, dest, &lzolen, NULL) == LZO_E_OK)
 198                         return lzolen;
 199                 else
 200 #endif
 201                         return -1;
 202         }
 203 #ifdef HAVE_ZLIB
 204         else {
 205                 unsigned long destlen = MAXSIZE;
 206                 if(uncompress(dest, &destlen, source, len) == Z_OK)
 207                         return destlen;
 208                 else
 209                         return -1;
 210         }
 211 #endif
 212
 213         return -1;
 214 }
 215
 216 /* VPN packet I/O */
 217
 218 static void receive_packet(node_t *n, vpn_packet_t *packet) {
 219         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Received packet of %d bytes from %s (%s)",
 220                            packet->len, n->name, n->hostname);
 221
 222         route(n, packet);
 223 }
 224
 225 static bool try_mac(const node_t *n, const vpn_packet_t *inpkt) {
 226         unsigned char hmac[EVP_MAX_MD_SIZE];
 227
 228         if(!n->indigest || !n->inmaclength || !n->inkey || inpkt->len < sizeof inpkt->seqno + n->inmaclength)
 229                 return false;
 230
 231         HMAC(n->indigest, n->inkey, n->inkeylength, (unsigned char *) &inpkt->seqno, inpkt->len - n->inmaclength, (unsigned char *)hmac, NULL);
 232
 233         return !memcmp(hmac, (char *) &inpkt->seqno + inpkt->len - n->inmaclength, n->inmaclength);
 234 }
 235
 236 static void receive_udppacket(node_t *n, vpn_packet_t *inpkt) {
 237         vpn_packet_t pkt1, pkt2;
 238         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 239         int nextpkt = 0;
 240         vpn_packet_t *outpkt = pkt[0];
 241         int outlen, outpad;
 242         unsigned char hmac[EVP_MAX_MD_SIZE];
 243         int i;
 244
 245         if(!n->inkey) {
 246                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got packet from %s (%s) but he hasn't got our key yet",
 247                                         n->name, n->hostname);
 248                 return;
 249         }
 250
 251         /* Check packet length */
 252
 253         if(inpkt->len < sizeof(inpkt->seqno) + n->inmaclength) {
 254                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got too short packet from %s (%s)",
 255                                         n->name, n->hostname);
 256                 return;
 257         }
 258
 259         /* Check the message authentication code */
 260
 261         if(n->indigest && n->inmaclength) {
 262                 inpkt->len -= n->inmaclength;
 263                 HMAC(n->indigest, n->inkey, n->inkeylength,
 264                          (unsigned char *) &inpkt->seqno, inpkt->len, (unsigned char *)hmac, NULL);
 265
 266                 if(memcmp(hmac, (char *) &inpkt->seqno + inpkt->len, n->inmaclength)) {
 267                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Got unauthenticated packet from %s (%s)",
 268                                            n->name, n->hostname);
 269                         return;
 270                 }
 271         }
 272
 273         /* Decrypt the packet */
 274
 275         if(n->incipher) {
 276                 outpkt = pkt[nextpkt++];
 277
 278                 if(!EVP_DecryptInit_ex(&n->inctx, NULL, NULL, NULL, NULL)
 279                                 || !EVP_DecryptUpdate(&n->inctx, (unsigned char *) &outpkt->seqno, &outlen,
 280                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 281                                 || !EVP_DecryptFinal_ex(&n->inctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 282                         ifdebug(TRAFFIC) logger(LOG_DEBUG, "Error decrypting packet from %s (%s): %s",
 283                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 284                         return;
 285                 }
 286
 287                 outpkt->len = outlen + outpad;
 288                 inpkt = outpkt;
 289         }
 290
 291         /* Check the sequence number */
 292
 293         inpkt->len -= sizeof(inpkt->seqno);
 294         inpkt->seqno = ntohl(inpkt->seqno);
 295
 296         if(inpkt->seqno != n->received_seqno + 1) {
 297                 if(inpkt->seqno >= n->received_seqno + sizeof(n->late) * 8) {
 298                         logger(LOG_WARNING, "Lost %d packets from %s (%s)",
 299                                            inpkt->seqno - n->received_seqno - 1, n->name, n->hostname);
 300
 301                         memset(n->late, 0, sizeof(n->late));
 302                 } else if (inpkt->seqno <= n->received_seqno) {
 303                         if((n->received_seqno >= sizeof(n->late) * 8 && inpkt->seqno <= n->received_seqno - sizeof(n->late) * 8) || !(n->late[(inpkt->seqno / 8) % sizeof(n->late)] & (1 << inpkt->seqno % 8))) {
 304                                 logger(LOG_WARNING, "Got late or replayed packet from %s (%s), seqno %d, last received %d",
 305                                            n->name, n->hostname, inpkt->seqno, n->received_seqno);
 306                                 return;
 307                         }
 308                 } else {
 309                         for(i = n->received_seqno + 1; i < inpkt->seqno; i++)
 310                                 n->late[(i / 8) % sizeof(n->late)] |= 1 << i % 8;
 311                 }
 312         }
 313
 314         n->late[(inpkt->seqno / 8) % sizeof(n->late)] &= ~(1 << inpkt->seqno % 8);
 315
 316         if(inpkt->seqno > n->received_seqno)
 317                 n->received_seqno = inpkt->seqno;
 318
 319         if(n->received_seqno > MAX_SEQNO)
 320                 keyexpires = 0;
 321
 322         /* Decompress the packet */
 323
 324         length_t origlen = inpkt->len;
 325
 326         if(n->incompression) {
 327                 outpkt = pkt[nextpkt++];
 328
 329                 if((outpkt->len = uncompress_packet(outpkt->data, inpkt->data, inpkt->len, n->incompression)) < 0) {
 330                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while uncompressing packet from %s (%s)",
 331                                                  n->name, n->hostname);
 332                         return;
 333                 }
 334
 335                 inpkt = outpkt;
 336
 337                 origlen -= MTU/64 + 20;
 338         }
 339
 340         inpkt->priority = 0;
 341
 342         if(!inpkt->data[12] && !inpkt->data[13])
 343                 mtu_probe_h(n, inpkt, origlen);
 344         else
 345                 receive_packet(n, inpkt);
 346 }
 347
 348 void receive_tcppacket(connection_t *c, char *buffer, int len) {
 349         vpn_packet_t outpkt;
 350
 351         outpkt.len = len;
 352         if(c->options & OPTION_TCPONLY)
 353                 outpkt.priority = 0;
 354         else
 355                 outpkt.priority = -1;
 356         memcpy(outpkt.data, buffer, len);
 357
 358         receive_packet(c->node, &outpkt);
 359 }
 360
 361 static void send_udppacket(node_t *n, vpn_packet_t *origpkt) {
 362         vpn_packet_t pkt1, pkt2;
 363         vpn_packet_t *pkt[] = { &pkt1, &pkt2, &pkt1, &pkt2 };
 364         vpn_packet_t *inpkt = origpkt;
 365         int nextpkt = 0;
 366         vpn_packet_t *outpkt;
 367         int origlen;
 368         int outlen, outpad;
 369 #if defined(SOL_IP) && defined(IP_TOS)
 370         static int priority = 0;
 371 #endif
 372         int origpriority;
 373         int sock;
 374
 375         if(!n->status.reachable) {
 376                 ifdebug(TRAFFIC) logger(LOG_INFO, "Trying to send UDP packet to unreachable node %s (%s)", n->name, n->hostname);
 377                 return;
 378         }
 379
 380         /* Make sure we have a valid key */
 381
 382         if(!n->status.validkey) {
 383                 ifdebug(TRAFFIC) logger(LOG_INFO,
 384                                    "No valid key known yet for %s (%s), forwarding via TCP",
 385                                    n->name, n->hostname);
 386
 387                 if(n->last_req_key + 10 < now) {
 388                         send_req_key(n);
 389                         n->last_req_key = now;
 390                 }
 391
 392                 send_tcppacket(n->nexthop->connection, origpkt);
 393
 394                 return;
 395         }
 396
 397         if(n->options & OPTION_PMTU_DISCOVERY && inpkt->len > n->minmtu && (inpkt->data[12] | inpkt->data[13])) {
 398                 ifdebug(TRAFFIC) logger(LOG_INFO,
 399                                 "Packet for %s (%s) larger than minimum MTU, forwarding via %s",
 400                                 n->name, n->hostname, n != n->nexthop ? n->nexthop->name : "TCP");
 401
 402                 if(n != n->nexthop)
 403                         send_packet(n->nexthop, origpkt);
 404                 else
 405                         send_tcppacket(n->nexthop->connection, origpkt);
 406
 407                 return;
 408         }
 409
 410         origlen = inpkt->len;
 411         origpriority = inpkt->priority;
 412
 413         /* Compress the packet */
 414
 415         if(n->outcompression) {
 416                 outpkt = pkt[nextpkt++];
 417
 418                 if((outpkt->len = compress_packet(outpkt->data, inpkt->data, inpkt->len, n->outcompression)) < 0) {
 419                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while compressing packet to %s (%s)",
 420                                    n->name, n->hostname);
 421                         return;
 422                 }
 423
 424                 inpkt = outpkt;
 425         }
 426
 427         /* Add sequence number */
 428
 429         inpkt->seqno = htonl(++(n->sent_seqno));
 430         inpkt->len += sizeof(inpkt->seqno);
 431
 432         /* Encrypt the packet */
 433
 434         if(n->outcipher) {
 435                 outpkt = pkt[nextpkt++];
 436
 437                 if(!EVP_EncryptInit_ex(&n->outctx, NULL, NULL, NULL, NULL)
 438                                 || !EVP_EncryptUpdate(&n->outctx, (unsigned char *) &outpkt->seqno, &outlen,
 439                                         (unsigned char *) &inpkt->seqno, inpkt->len)
 440                                 || !EVP_EncryptFinal_ex(&n->outctx, (unsigned char *) &outpkt->seqno + outlen, &outpad)) {
 441                         ifdebug(TRAFFIC) logger(LOG_ERR, "Error while encrypting packet to %s (%s): %s",
 442                                                 n->name, n->hostname, ERR_error_string(ERR_get_error(), NULL));
 443                         goto end;
 444                 }
 445
 446                 outpkt->len = outlen + outpad;
 447                 inpkt = outpkt;
 448         }
 449
 450         /* Add the message authentication code */
 451
 452         if(n->outdigest && n->outmaclength) {
 453                 HMAC(n->outdigest, n->outkey, n->outkeylength, (unsigned char *) &inpkt->seqno,
 454                          inpkt->len, (unsigned char *) &inpkt->seqno + inpkt->len, NULL);
 455                 inpkt->len += n->outmaclength;
 456         }
 457
 458         /* Determine which socket we have to use */
 459
 460         for(sock = 0; sock < listen_sockets; sock++)
 461                 if(n->address.sa.sa_family == listen_socket[sock].sa.sa.sa_family)
 462                         break;
 463
 464         if(sock >= listen_sockets)
 465                 sock = 0;                               /* If none is available, just use the first and hope for the best. */
 466
 467         /* Send the packet */
 468
 469 #if defined(SOL_IP) && defined(IP_TOS)
 470         if(priorityinheritance && origpriority != priority
 471            && listen_socket[sock].sa.sa.sa_family == AF_INET) {
 472                 priority = origpriority;
 473                 ifdebug(TRAFFIC) logger(LOG_DEBUG, "Setting outgoing packet priority to %d", priority);
 474                 if(setsockopt(listen_socket[sock].udp, SOL_IP, IP_TOS, &priority, sizeof(priority)))    /* SO_PRIORITY doesn't seem to work */
 475                         logger(LOG_ERR, "System call `%s' failed: %s", "setsockopt", strerror(errno));
 476         }
 477 #endif
 478
 479         if(sendto(listen_socket[sock].udp, (char *) &inpkt->seqno, inpkt->len, 0, &(n->address.sa), SALEN(n->address.sa)) < 0 && !sockwouldblock(sockerrno)) {
 480                 if(sockmsgsize(sockerrno)) {
 481                         if(n->maxmtu >= origlen)
 482                                 n->maxmtu = origlen - 1;
 483                         if(n->mtu >= origlen)
 484                                 n->mtu = origlen - 1;
 485                 } else
 486                         logger(LOG_ERR, "Error sending packet to %s (%s): %s", n->name, n->hostname, sockstrerror(sockerrno));
 487         }
 488
 489 end:
 490         origpkt->len = origlen;
 491 }
 492
 493 /*
 494   send a packet to the given vpn ip.
 495 */
 496 void send_packet(const node_t *n, vpn_packet_t *packet) {
 497         node_t *via;
 498
 499         if(n == myself) {
 500                 if(overwrite_mac)
 501                          memcpy(packet->data, mymac.x, ETH_ALEN);
 502                 write_packet(packet);
 503                 return;
 504         }
 505
 506         ifdebug(TRAFFIC) logger(LOG_ERR, "Sending packet of %d bytes to %s (%s)",
 507                            packet->len, n->name, n->hostname);
 508
 509         if(!n->status.reachable) {
 510                 ifdebug(TRAFFIC) logger(LOG_INFO, "Node %s (%s) is not reachable",
 511                                    n->name, n->hostname);
 512                 return;
 513         }
 514
 515         via = (packet->priority == -1 || n->via == myself) ? n->nexthop : n->via;
 516
 517         if(via != n)
 518                 ifdebug(TRAFFIC) logger(LOG_INFO, "Sending packet to %s via %s (%s)",
 519                            n->name, via->name, n->via->hostname);
 520
 521         if(packet->priority == -1 || ((myself->options | via->options) & OPTION_TCPONLY)) {
 522                 if(!send_tcppacket(via->connection, packet))
 523                         terminate_connection(via->connection, true);
 524         } else
 525                 send_udppacket(via, packet);
 526 }
 527
 528 /* Broadcast a packet using the minimum spanning tree */
 529
 530 void broadcast_packet(const node_t *from, vpn_packet_t *packet) {
 531         avl_node_t *node;
 532         connection_t *c;
 533
 534         ifdebug(TRAFFIC) logger(LOG_INFO, "Broadcasting packet of %d bytes from %s (%s)",
 535                            packet->len, from->name, from->hostname);
 536
 537         if(from != myself) {
 538                 send_packet(myself, packet);
 539
 540                 // In TunnelServer mode, do not forward broadcast packets.
 541                 // The MST might not be valid and create loops.
 542                 if(tunnelserver)
 543                         return;
 544         }
 545
 546         for(node = connection_tree->head; node; node = node->next) {
 547                 c = node->data;
 548
 549                 if(c->status.active && c->status.mst && c != from->nexthop->connection)
 550                         send_packet(c->node, packet);
 551         }
 552 }
 553
 554 static node_t *try_harder(const sockaddr_t *from, const vpn_packet_t *pkt) {
 555         avl_node_t *node;
 556         edge_t *e;
 557         node_t *n = NULL;
 558         static time_t last_hard_try = 0;
 559
 560         for(node = edge_weight_tree->head; node; node = node->next) {
 561                 e = node->data;
 562
 563                 if(sockaddrcmp_noport(from, &e->address)) {
 564                         if(last_hard_try == now)
 565                                 continue;
 566                         last_hard_try = now;
 567                 }
 568
 569                 if(!n)
 570                         n = e->to;
 571
 572                 if(!try_mac(e->to, pkt))
 573                         continue;
 574
 575                 n = e->to;
 576                 break;
 577         }
 578
 579         return n;
 580 }
 581
 582 void handle_incoming_vpn_data(int sock) {
 583         vpn_packet_t pkt;
 584         char *hostname;
 585         sockaddr_t from;
 586         socklen_t fromlen = sizeof(from);
 587         node_t *n;
 588
 589         pkt.len = recvfrom(sock, (char *) &pkt.seqno, MAXSIZE, 0, &from.sa, &fromlen);
 590
 591         if(pkt.len < 0) {
 592                 if(!sockwouldblock(sockerrno))
 593                         logger(LOG_ERR, "Receiving packet failed: %s", sockstrerror(sockerrno));
 594                 return;
 595         }
 596
 597         sockaddrunmap(&from);           /* Some braindead IPv6 implementations do stupid things. */
 598
 599         n = lookup_node_udp(&from);
 600
 601         if(!n) {
 602                 n = try_harder(&from, &pkt);
 603                 if(n)
 604                         update_node_udp(n, &from);
 605                 else ifdebug(PROTOCOL) {
 606                         hostname = sockaddr2hostname(&from);
 607                         logger(LOG_WARNING, "Received UDP packet from unknown source %s", hostname);
 608                         free(hostname);
 609                         return;
 610                 }
 611                 else
 612                         return;
 613         }
 614
 615         receive_udppacket(n, &pkt);
 616 }