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

   1 /*
   2     route.c -- routing
   3     Copyright (C) 2000-2003 Ivo Timmermans <ivo@o2w.nl>,
   4                   2000-2003 Guus Sliepen <guus@sliepen.eu.org>
   5
   6     This program is free software; you can redistribute it and/or modify
   7     it under the terms of the GNU General Public License as published by
   8     the Free Software Foundation; either version 2 of the License, or
   9     (at your option) any later version.
  10
  11     This program is distributed in the hope that it will be useful,
  12     but WITHOUT ANY WARRANTY; without even the implied warranty of
  13     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14     GNU General Public License for more details.
  15
  16     You should have received a copy of the GNU General Public License
  17     along with this program; if not, write to the Free Software
  18     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19
  20     $Id: route.c,v 1.1.2.71 2003/12/13 21:50:26 guus Exp $
  21 */
  22
  23 #include "system.h"
  24
  25 #ifdef HAVE_NET_ETHERNET_H
  26 #include <net/ethernet.h>
  27 #endif
  28 #ifdef HAVE_NET_IF_ARP_H
  29 #include <net/if_arp.h>
  30 #endif
  31 #ifdef HAVE_NETINET_IP_ICMP_H
  32 #include <netinet/ip_icmp.h>
  33 #endif
  34 #ifdef HAVE_NETINET_ICMP6_H
  35 #include <netinet/icmp6.h>
  36 #endif
  37 #ifdef HAVE_NETINET_IF_ETHER_H
  38 #include <netinet/if_ether.h>
  39 #endif
  40
  41 #include "avl_tree.h"
  42 #include "connection.h"
  43 #include "ethernet.h"
  44 #include "ipv4.h"
  45 #include "ipv6.h"
  46 #include "logger.h"
  47 #include "net.h"
  48 #include "protocol.h"
  49 #include "route.h"
  50 #include "subnet.h"
  51 #include "utils.h"
  52
  53 rmode_t routing_mode = RMODE_ROUTER;
  54 bool priorityinheritance = false;
  55 int macexpire = 600;
  56 bool overwrite_mac = false;
  57 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
  58
  59 /* Sizes of various headers */
  60
  61 static const size_t ether_size = sizeof(struct ether_header);
  62 static const size_t arp_size = sizeof(struct ether_arp);
  63 static const size_t ip_size = sizeof(struct ip);
  64 static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip);
  65 static const size_t ip6_size = sizeof(struct ip6_hdr);
  66 static const size_t icmp6_size = sizeof(struct icmp6_hdr);
  67 static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
  68 static const size_t opt_size = sizeof(struct nd_opt_hdr);
  69
  70 /* RFC 1071 */
  71
  72 static __inline__ uint16_t inet_checksum(void *data, int len, uint16_t prevsum)
  73 {
  74         uint16_t *p = data;
  75         uint32_t checksum = prevsum ^ 0xFFFF;
  76
  77         while(len >= 2) {
  78                 checksum += *p++;
  79                 len -= 2;
  80         }
  81
  82         if(len)
  83                 checksum += *(uint8_t *)p;
  84
  85         while(checksum >> 16)
  86                 checksum = (checksum & 0xFFFF) + (checksum >> 16);
  87
  88         return ~checksum;
  89 }
  90
  91 static __inline__ bool ratelimit(int frequency) {
  92         static time_t lasttime = 0;
  93         static int count = 0;
  94
  95         if(lasttime == now) {
  96                 if(++count > frequency)
  97                         return true;
  98         } else {
  99                 lasttime = now;
 100                 count = 0;
 101         }
 102
 103         return false;
 104 }
 105
 106 static __inline__ bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
 107         if(packet->len < length) {
 108                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got too short packet from %s (%s)"), source->name, source->hostname);
 109                 return false;
 110         } else
 111                 return true;
 112 }
 113
 114 static __inline__ void learn_mac(mac_t *address)
 115 {
 116         subnet_t *subnet;
 117         avl_node_t *node;
 118         connection_t *c;
 119
 120         cp();
 121
 122         subnet = lookup_subnet_mac(address);
 123
 124         /* If we don't know this MAC address yet, store it */
 125
 126         if(!subnet) {
 127                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx"),
 128                                    address->x[0], address->x[1], address->x[2], address->x[3],
 129                                    address->x[4], address->x[5]);
 130
 131                 subnet = new_subnet();
 132                 subnet->type = SUBNET_MAC;
 133                 subnet->expires = now + macexpire;
 134                 subnet->net.mac.address = *address;
 135                 subnet_add(myself, subnet);
 136
 137                 /* And tell all other tinc daemons it's our MAC */
 138
 139                 for(node = connection_tree->head; node; node = node->next) {
 140                         c = node->data;
 141                         if(c->status.active)
 142                                 send_add_subnet(c, subnet);
 143                 }
 144         }
 145
 146         if(subnet->expires)
 147                 subnet->expires = now + macexpire;
 148 }
 149
 150 void age_subnets(void)
 151 {
 152         subnet_t *s;
 153         connection_t *c;
 154         avl_node_t *node, *next, *node2;
 155
 156         cp();
 157
 158         for(node = myself->subnet_tree->head; node; node = next) {
 159                 next = node->next;
 160                 s = node->data;
 161                 if(s->expires && s->expires < now) {
 162                         ifdebug(TRAFFIC) {
 163                                 char netstr[MAXNETSTR];
 164                                 if(net2str(netstr, sizeof netstr, s))
 165                                         logger(LOG_INFO, _("Subnet %s expired"), netstr);
 166                         }
 167
 168                         for(node2 = connection_tree->head; node2; node2 = node2->next) {
 169                                 c = node2->data;
 170                                 if(c->status.active)
 171                                         send_del_subnet(c, s);
 172                         }
 173
 174                         subnet_del(myself, s);
 175                 }
 176         }
 177 }
 178
 179 static __inline__ void route_mac(node_t *source, vpn_packet_t *packet)
 180 {
 181         subnet_t *subnet;
 182
 183         cp();
 184
 185         /* Learn source address */
 186
 187         if(source == myself)
 188                 learn_mac((mac_t *)(&packet->data[6]));
 189
 190         /* Lookup destination address */
 191
 192         subnet = lookup_subnet_mac((mac_t *)(&packet->data[0]));
 193
 194         if(!subnet) {
 195                 broadcast_packet(source, packet);
 196                 return;
 197         }
 198
 199         if(subnet->owner == source) {
 200                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
 201                 return;
 202         }
 203
 204         send_packet(subnet->owner, packet);
 205 }
 206
 207 /* RFC 792 */
 208
 209 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t code)
 210 {
 211         struct ip ip = {0};
 212         struct icmp icmp = {0};
 213
 214         struct in_addr ip_src;
 215         struct in_addr ip_dst;
 216         uint32_t oldlen;
 217
 218         if(ratelimit(3))
 219                 return;
 220
 221         cp();
 222
 223         /* Copy headers from packet into properly aligned structs on the stack */
 224
 225         memcpy(&ip, packet->data + ether_size, ip_size);
 226
 227         /* Remember original source and destination */
 228
 229         ip_src = ip.ip_src;
 230         ip_dst = ip.ip_dst;
 231
 232         oldlen = packet->len - ether_size;
 233
 234         if(oldlen >= IP_MSS - ip_size - icmp_size)
 235                 oldlen = IP_MSS - ip_size - icmp_size;
 236
 237         /* Copy first part of original contents to ICMP message */
 238
 239         memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
 240
 241         /* Fill in IPv4 header */
 242
 243         ip.ip_v = 4;
 244         ip.ip_hl = ip_size / 4;
 245         ip.ip_tos = 0;
 246         ip.ip_len = htons(ip_size + icmp_size + oldlen);
 247         ip.ip_id = 0;
 248         ip.ip_off = 0;
 249         ip.ip_ttl = 255;
 250         ip.ip_p = IPPROTO_ICMP;
 251         ip.ip_sum = 0;
 252         ip.ip_src = ip_dst;
 253         ip.ip_dst = ip_src;
 254
 255         ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
 256
 257         /* Fill in ICMP header */
 258
 259         icmp.icmp_type = ICMP_DEST_UNREACH;
 260         icmp.icmp_code = code;
 261         icmp.icmp_cksum = 0;
 262
 263         icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
 264         icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
 265
 266         /* Copy structs on stack back to packet */
 267
 268         memcpy(packet->data + ether_size, &ip, ip_size);
 269         memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
 270
 271         packet->len = ether_size + ip_size + icmp_size + oldlen;
 272
 273         send_packet(source, packet);
 274 }
 275
 276 static __inline__ void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
 277 {
 278         subnet_t *subnet;
 279
 280         cp();
 281
 282         subnet = lookup_subnet_ipv4((ipv4_t *) &packet->data[30]);
 283
 284         if(!subnet) {
 285                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d"),
 286                                 source->name, source->hostname,
 287                                 packet->data[30],
 288                                 packet->data[31],
 289                                 packet->data[32],
 290                                 packet->data[33]);
 291
 292                 route_ipv4_unreachable(source, packet, ICMP_NET_UNKNOWN);
 293                 return;
 294         }
 295
 296         if(subnet->owner == source) {
 297                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
 298                 return;
 299         }
 300
 301         if(!subnet->owner->status.reachable)
 302                 route_ipv4_unreachable(source, packet, ICMP_NET_UNREACH);
 303
 304         if(priorityinheritance)
 305                 packet->priority = packet->data[15];
 306
 307         send_packet(subnet->owner, packet);
 308 }
 309
 310 static __inline__ void route_ipv4(node_t *source, vpn_packet_t *packet)
 311 {
 312         cp();
 313
 314         if(!checklength(source, packet, ether_size + ip_size))
 315                 return;
 316
 317         route_ipv4_unicast(source, packet);
 318 }
 319
 320 /* RFC 2463 */
 321
 322 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t code)
 323 {
 324         struct ip6_hdr ip6;
 325         struct icmp6_hdr icmp6 = {0};
 326         uint16_t checksum;
 327
 328         struct {
 329                 struct in6_addr ip6_src;        /* source address */
 330                 struct in6_addr ip6_dst;        /* destination address */
 331                 uint32_t length;
 332                 uint32_t next;
 333         } pseudo;
 334
 335         if(ratelimit(3))
 336                 return;
 337
 338         cp();
 339
 340         /* Copy headers from packet to structs on the stack */
 341
 342         memcpy(&ip6, packet->data + ether_size, ip6_size);
 343
 344         /* Remember original source and destination */
 345
 346         pseudo.ip6_src = ip6.ip6_dst;
 347         pseudo.ip6_dst = ip6.ip6_src;
 348
 349         pseudo.length = packet->len - ether_size;
 350
 351         if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
 352                 pseudo.length = IP_MSS - ip6_size - icmp6_size;
 353
 354         /* Copy first part of original contents to ICMP message */
 355
 356         memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
 357
 358         /* Fill in IPv6 header */
 359
 360         ip6.ip6_flow = htonl(0x60000000UL);
 361         ip6.ip6_plen = htons(icmp6_size + pseudo.length);
 362         ip6.ip6_nxt = IPPROTO_ICMPV6;
 363         ip6.ip6_hlim = 255;
 364         ip6.ip6_src = pseudo.ip6_src;
 365         ip6.ip6_dst = pseudo.ip6_dst;
 366
 367         /* Fill in ICMP header */
 368
 369         icmp6.icmp6_type = ICMP6_DST_UNREACH;
 370         icmp6.icmp6_code = code;
 371         icmp6.icmp6_cksum = 0;
 372
 373         /* Create pseudo header */
 374
 375         pseudo.length = htonl(icmp6_size + pseudo.length);
 376         pseudo.next = htonl(IPPROTO_ICMPV6);
 377
 378         /* Generate checksum */
 379
 380         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 381         checksum = inet_checksum(&icmp6, icmp6_size, checksum);
 382         checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
 383
 384         icmp6.icmp6_cksum = checksum;
 385
 386         /* Copy structs on stack back to packet */
 387
 388         memcpy(packet->data + ether_size, &ip6, ip6_size);
 389         memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size);
 390
 391         packet->len = ether_size + ip6_size + ntohl(pseudo.length);
 392
 393         send_packet(source, packet);
 394 }
 395
 396 static __inline__ void route_ipv6_unicast(node_t *source, vpn_packet_t *packet)
 397 {
 398         subnet_t *subnet;
 399
 400         cp();
 401
 402         subnet = lookup_subnet_ipv6((ipv6_t *) &packet->data[38]);
 403
 404         if(!subnet) {
 405                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
 406                                 source->name, source->hostname,
 407                                 ntohs(*(uint16_t *) &packet->data[38]),
 408                                 ntohs(*(uint16_t *) &packet->data[40]),
 409                                 ntohs(*(uint16_t *) &packet->data[42]),
 410                                 ntohs(*(uint16_t *) &packet->data[44]),
 411                                 ntohs(*(uint16_t *) &packet->data[46]),
 412                                 ntohs(*(uint16_t *) &packet->data[48]),
 413                                 ntohs(*(uint16_t *) &packet->data[50]),
 414                                 ntohs(*(uint16_t *) &packet->data[52]));
 415
 416                 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH_ADDR);
 417                 return;
 418         }
 419
 420         if(subnet->owner == source) {
 421                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
 422                 return;
 423         }
 424
 425         if(!subnet->owner->status.reachable)
 426                 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH_NOROUTE);
 427
 428         send_packet(subnet->owner, packet);
 429 }
 430
 431 /* RFC 2461 */
 432
 433 static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 434 {
 435         struct ip6_hdr ip6;
 436         struct nd_neighbor_solicit ns;
 437         struct nd_opt_hdr opt;
 438         subnet_t *subnet;
 439         uint16_t checksum;
 440
 441         struct {
 442                 struct in6_addr ip6_src;        /* source address */
 443                 struct in6_addr ip6_dst;        /* destination address */
 444                 uint32_t length;
 445                 uint32_t next;
 446         } pseudo;
 447
 448         cp();
 449
 450         if(!checklength(source, packet, ether_size + ip6_size + ns_size + opt_size + ETH_ALEN))
 451                 return;
 452
 453         if(source != myself) {
 454                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got neighbor solicitation request from %s (%s) while in router mode!"), source->name, source->hostname);
 455                 return;
 456         }
 457
 458         /* Copy headers from packet to structs on the stack */
 459
 460         memcpy(&ip6, packet->data + ether_size, ip6_size);
 461         memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
 462         memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
 463
 464         /* First, snatch the source address from the neighbor solicitation packet */
 465
 466         if(overwrite_mac)
 467                 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
 468
 469         /* Check if this is a valid neighbor solicitation request */
 470
 471         if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
 472            opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR) {
 473                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type neighbor solicitation request"));
 474                 return;
 475         }
 476
 477         /* Create pseudo header */
 478
 479         pseudo.ip6_src = ip6.ip6_src;
 480         pseudo.ip6_dst = ip6.ip6_dst;
 481         pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 482         pseudo.next = htonl(IPPROTO_ICMPV6);
 483
 484         /* Generate checksum */
 485
 486         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 487         checksum = inet_checksum(&ns, ns_size, checksum);
 488         checksum = inet_checksum(&opt, opt_size, checksum);
 489         checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 490
 491         if(checksum) {
 492                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
 493                 return;
 494         }
 495
 496         /* Check if the IPv6 address exists on the VPN */
 497
 498         subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
 499
 500         if(!subnet) {
 501                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
 502                                    ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
 503                                    ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
 504                                    ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
 505                                    ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
 506                                    ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
 507                                    ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
 508                                    ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
 509                                    ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
 510
 511                 return;
 512         }
 513
 514         /* Check if it is for our own subnet */
 515
 516         if(subnet->owner == myself)
 517                 return;                                 /* silently ignore */
 518
 519         /* Create neighbor advertation reply */
 520
 521         memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN);        /* copy destination address */
 522         packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
 523
 524         ip6.ip6_dst = ip6.ip6_src;                      /* swap destination and source protocoll address */
 525         ip6.ip6_src = ns.nd_ns_target;
 526
 527         memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN);   /* add fake source hard addr */
 528
 529         ns.nd_ns_cksum = 0;
 530         ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
 531         ns.nd_ns_reserved = htonl(0x40000000UL);        /* Set solicited flag */
 532         opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
 533
 534         /* Create pseudo header */
 535
 536         pseudo.ip6_src = ip6.ip6_src;
 537         pseudo.ip6_dst = ip6.ip6_dst;
 538         pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 539         pseudo.next = htonl(IPPROTO_ICMPV6);
 540
 541         /* Generate checksum */
 542
 543         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 544         checksum = inet_checksum(&ns, ns_size, checksum);
 545         checksum = inet_checksum(&opt, opt_size, checksum);
 546         checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 547
 548         ns.nd_ns_hdr.icmp6_cksum = checksum;
 549
 550         /* Copy structs on stack back to packet */
 551
 552         memcpy(packet->data + ether_size, &ip6, ip6_size);
 553         memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
 554         memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
 555
 556         send_packet(source, packet);
 557 }
 558
 559 static __inline__ void route_ipv6(node_t *source, vpn_packet_t *packet)
 560 {
 561         cp();
 562
 563         if(!checklength(source, packet, ether_size + ip6_size))
 564                 return;
 565
 566         if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
 567                 route_neighborsol(source, packet);
 568                 return;
 569         }
 570
 571         route_ipv6_unicast(source, packet);
 572 }
 573
 574 /* RFC 826 */
 575
 576 static void route_arp(node_t *source, vpn_packet_t *packet)
 577 {
 578         struct ether_arp arp;
 579         subnet_t *subnet;
 580         struct in_addr addr;
 581
 582         cp();
 583
 584         if(!checklength(source, packet, ether_size + arp_size))
 585                 return;
 586
 587         if(source != myself) {
 588                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got ARP request from %s (%s) while in router mode!"), source->name, source->hostname);
 589                 return;
 590         }
 591
 592         /* First, snatch the source address from the ARP packet */
 593
 594         if(overwrite_mac)
 595                 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
 596
 597         /* Copy headers from packet to structs on the stack */
 598
 599         memcpy(&arp, packet->data + ether_size, arp_size);
 600
 601         /* Check if this is a valid ARP request */
 602
 603         if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
 604            arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
 605                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type ARP request"));
 606                 return;
 607         }
 608
 609         /* Check if the IPv4 address exists on the VPN */
 610
 611         subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
 612
 613         if(!subnet) {
 614                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"),
 615                                    arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
 616                                    arp.arp_tpa[3]);
 617                 return;
 618         }
 619
 620         /* Check if it is for our own subnet */
 621
 622         if(subnet->owner == myself)
 623                 return;                                 /* silently ignore */
 624
 625         memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN);        /* copy destination address */
 626         packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
 627
 628         memcpy(&addr, arp.arp_tpa, sizeof(addr));       /* save protocol addr */
 629         memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */
 630         memcpy(arp.arp_spa, &addr, sizeof(addr));       /* ... */
 631
 632         memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN);     /* set target hard/proto addr */
 633         memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
 634         arp.arp_op = htons(ARPOP_REPLY);
 635
 636         /* Copy structs on stack back to packet */
 637
 638         memcpy(packet->data + ether_size, &arp, arp_size);
 639
 640         send_packet(source, packet);
 641 }
 642
 643 void route(node_t *source, vpn_packet_t *packet)
 644 {
 645         cp();
 646
 647         if(!checklength(source, packet, ether_size))
 648                 return;
 649
 650         switch (routing_mode) {
 651                 case RMODE_ROUTER:
 652                         {
 653                                 uint16_t type;
 654
 655                                 type = ntohs(*((uint16_t *)(&packet->data[12])));
 656                                 switch (type) {
 657                                         case ETH_P_ARP:
 658                                                 route_arp(source, packet);
 659                                                 break;
 660
 661                                         case ETH_P_IP:
 662                                                 route_ipv4(source, packet);
 663                                                 break;
 664
 665                                         case ETH_P_IPV6:
 666                                                 route_ipv6(source, packet);
 667                                                 break;
 668
 669                                         default:
 670                                                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown type %hx"), source->name, source->hostname, type);
 671                                                 break;
 672                                 }
 673                         }
 674                         break;
 675
 676                 case RMODE_SWITCH:
 677                         route_mac(source, packet);
 678                         break;
 679
 680                 case RMODE_HUB:
 681                         broadcast_packet(source, packet);
 682                         break;
 683         }
 684 }