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 1.1.2.73 2003/12/20 21:25:17 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 type, 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(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
 235                 icmp.icmp_nextmtu = htons(packet->len - ether_size);
 236
 237         if(oldlen >= IP_MSS - ip_size - icmp_size)
 238                 oldlen = IP_MSS - ip_size - icmp_size;
 239
 240         /* Copy first part of original contents to ICMP message */
 241
 242         memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
 243
 244         /* Fill in IPv4 header */
 245
 246         ip.ip_v = 4;
 247         ip.ip_hl = ip_size / 4;
 248         ip.ip_tos = 0;
 249         ip.ip_len = htons(ip_size + icmp_size + oldlen);
 250         ip.ip_id = 0;
 251         ip.ip_off = 0;
 252         ip.ip_ttl = 255;
 253         ip.ip_p = IPPROTO_ICMP;
 254         ip.ip_sum = 0;
 255         ip.ip_src = ip_dst;
 256         ip.ip_dst = ip_src;
 257
 258         ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
 259
 260         /* Fill in ICMP header */
 261
 262         icmp.icmp_type = type;
 263         icmp.icmp_code = code;
 264         icmp.icmp_cksum = 0;
 265
 266         icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
 267         icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
 268
 269         /* Copy structs on stack back to packet */
 270
 271         memcpy(packet->data + ether_size, &ip, ip_size);
 272         memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
 273
 274         packet->len = ether_size + ip_size + icmp_size + oldlen;
 275
 276         send_packet(source, packet);
 277 }
 278
 279 static __inline__ void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
 280 {
 281         subnet_t *subnet;
 282
 283         cp();
 284
 285         subnet = lookup_subnet_ipv4((ipv4_t *) &packet->data[30]);
 286
 287         if(!subnet) {
 288                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d"),
 289                                 source->name, source->hostname,
 290                                 packet->data[30],
 291                                 packet->data[31],
 292                                 packet->data[32],
 293                                 packet->data[33]);
 294
 295                 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
 296                 return;
 297         }
 298
 299         if(subnet->owner == source) {
 300                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
 301                 return;
 302         }
 303
 304         if(!subnet->owner->status.reachable)
 305                 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
 306
 307         if(subnet->owner->options & OPTION_PMTU_DISCOVERY && packet->len > subnet->owner->mtu && subnet->owner != myself) {
 308                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Packet for %s (%s) length %d larger than MTU %d"), subnet->owner->name, subnet->owner->hostname, packet->len, subnet->owner->mtu);
 309                 packet->len = subnet->owner->mtu;
 310                 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
 311                 return;
 312         }
 313
 314         if(priorityinheritance)
 315                 packet->priority = packet->data[15];
 316
 317         send_packet(subnet->owner, packet);
 318 }
 319
 320 static __inline__ void route_ipv4(node_t *source, vpn_packet_t *packet)
 321 {
 322         cp();
 323
 324         if(!checklength(source, packet, ether_size + ip_size))
 325                 return;
 326
 327         route_ipv4_unicast(source, packet);
 328 }
 329
 330 /* RFC 2463 */
 331
 332 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code)
 333 {
 334         struct ip6_hdr ip6;
 335         struct icmp6_hdr icmp6 = {0};
 336         uint16_t checksum;
 337
 338         struct {
 339                 struct in6_addr ip6_src;        /* source address */
 340                 struct in6_addr ip6_dst;        /* destination address */
 341                 uint32_t length;
 342                 uint32_t next;
 343         } pseudo;
 344
 345         if(ratelimit(3))
 346                 return;
 347
 348         cp();
 349
 350         /* Copy headers from packet to structs on the stack */
 351
 352         memcpy(&ip6, packet->data + ether_size, ip6_size);
 353
 354         /* Remember original source and destination */
 355
 356         pseudo.ip6_src = ip6.ip6_dst;
 357         pseudo.ip6_dst = ip6.ip6_src;
 358
 359         pseudo.length = packet->len - ether_size;
 360
 361         if(type == ICMP6_PACKET_TOO_BIG)
 362                 icmp6.icmp6_mtu = htonl(pseudo.length);
 363
 364         if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
 365                 pseudo.length = IP_MSS - ip6_size - icmp6_size;
 366
 367         /* Copy first part of original contents to ICMP message */
 368
 369         memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
 370
 371         /* Fill in IPv6 header */
 372
 373         ip6.ip6_flow = htonl(0x60000000UL);
 374         ip6.ip6_plen = htons(icmp6_size + pseudo.length);
 375         ip6.ip6_nxt = IPPROTO_ICMPV6;
 376         ip6.ip6_hlim = 255;
 377         ip6.ip6_src = pseudo.ip6_src;
 378         ip6.ip6_dst = pseudo.ip6_dst;
 379
 380         /* Fill in ICMP header */
 381
 382         icmp6.icmp6_type = type;
 383         icmp6.icmp6_code = code;
 384         icmp6.icmp6_cksum = 0;
 385
 386         /* Create pseudo header */
 387
 388         pseudo.length = htonl(icmp6_size + pseudo.length);
 389         pseudo.next = htonl(IPPROTO_ICMPV6);
 390
 391         /* Generate checksum */
 392
 393         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 394         checksum = inet_checksum(&icmp6, icmp6_size, checksum);
 395         checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
 396
 397         icmp6.icmp6_cksum = checksum;
 398
 399         /* Copy structs on stack back to packet */
 400
 401         memcpy(packet->data + ether_size, &ip6, ip6_size);
 402         memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size);
 403
 404         packet->len = ether_size + ip6_size + ntohl(pseudo.length);
 405
 406         send_packet(source, packet);
 407 }
 408
 409 static __inline__ void route_ipv6_unicast(node_t *source, vpn_packet_t *packet)
 410 {
 411         subnet_t *subnet;
 412
 413         cp();
 414
 415         subnet = lookup_subnet_ipv6((ipv6_t *) &packet->data[38]);
 416
 417         if(!subnet) {
 418                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
 419                                 source->name, source->hostname,
 420                                 ntohs(*(uint16_t *) &packet->data[38]),
 421                                 ntohs(*(uint16_t *) &packet->data[40]),
 422                                 ntohs(*(uint16_t *) &packet->data[42]),
 423                                 ntohs(*(uint16_t *) &packet->data[44]),
 424                                 ntohs(*(uint16_t *) &packet->data[46]),
 425                                 ntohs(*(uint16_t *) &packet->data[48]),
 426                                 ntohs(*(uint16_t *) &packet->data[50]),
 427                                 ntohs(*(uint16_t *) &packet->data[52]));
 428
 429                 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
 430                 return;
 431         }
 432
 433         if(subnet->owner == source) {
 434                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
 435                 return;
 436         }
 437
 438         if(!subnet->owner->status.reachable)
 439                 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
 440
 441         if(subnet->owner->options & OPTION_PMTU_DISCOVERY && packet->len > subnet->owner->mtu && subnet->owner != myself) {
 442                 ifdebug(TRAFFIC) logger(LOG_INFO, _("Packet for %s (%s) length %d larger than MTU %d"), subnet->owner->name, subnet->owner->hostname, packet->len, subnet->owner->mtu);
 443                 packet->len = subnet->owner->mtu;
 444                 route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
 445                 return;
 446         }
 447
 448         send_packet(subnet->owner, packet);
 449 }
 450
 451 /* RFC 2461 */
 452
 453 static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 454 {
 455         struct ip6_hdr ip6;
 456         struct nd_neighbor_solicit ns;
 457         struct nd_opt_hdr opt;
 458         subnet_t *subnet;
 459         uint16_t checksum;
 460
 461         struct {
 462                 struct in6_addr ip6_src;        /* source address */
 463                 struct in6_addr ip6_dst;        /* destination address */
 464                 uint32_t length;
 465                 uint32_t next;
 466         } pseudo;
 467
 468         cp();
 469
 470         if(!checklength(source, packet, ether_size + ip6_size + ns_size + opt_size + ETH_ALEN))
 471                 return;
 472
 473         if(source != myself) {
 474                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got neighbor solicitation request from %s (%s) while in router mode!"), source->name, source->hostname);
 475                 return;
 476         }
 477
 478         /* Copy headers from packet to structs on the stack */
 479
 480         memcpy(&ip6, packet->data + ether_size, ip6_size);
 481         memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
 482         memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
 483
 484         /* First, snatch the source address from the neighbor solicitation packet */
 485
 486         if(overwrite_mac)
 487                 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
 488
 489         /* Check if this is a valid neighbor solicitation request */
 490
 491         if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
 492            opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR) {
 493                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type neighbor solicitation request"));
 494                 return;
 495         }
 496
 497         /* Create pseudo header */
 498
 499         pseudo.ip6_src = ip6.ip6_src;
 500         pseudo.ip6_dst = ip6.ip6_dst;
 501         pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 502         pseudo.next = htonl(IPPROTO_ICMPV6);
 503
 504         /* Generate checksum */
 505
 506         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 507         checksum = inet_checksum(&ns, ns_size, checksum);
 508         checksum = inet_checksum(&opt, opt_size, checksum);
 509         checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 510
 511         if(checksum) {
 512                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
 513                 return;
 514         }
 515
 516         /* Check if the IPv6 address exists on the VPN */
 517
 518         subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
 519
 520         if(!subnet) {
 521                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
 522                                    ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
 523                                    ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
 524                                    ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
 525                                    ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
 526                                    ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
 527                                    ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
 528                                    ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
 529                                    ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
 530
 531                 return;
 532         }
 533
 534         /* Check if it is for our own subnet */
 535
 536         if(subnet->owner == myself)
 537                 return;                                 /* silently ignore */
 538
 539         /* Create neighbor advertation reply */
 540
 541         memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN);        /* copy destination address */
 542         packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
 543
 544         ip6.ip6_dst = ip6.ip6_src;                      /* swap destination and source protocoll address */
 545         ip6.ip6_src = ns.nd_ns_target;
 546
 547         memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN);   /* add fake source hard addr */
 548
 549         ns.nd_ns_cksum = 0;
 550         ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
 551         ns.nd_ns_reserved = htonl(0x40000000UL);        /* Set solicited flag */
 552         opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
 553
 554         /* Create pseudo header */
 555
 556         pseudo.ip6_src = ip6.ip6_src;
 557         pseudo.ip6_dst = ip6.ip6_dst;
 558         pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 559         pseudo.next = htonl(IPPROTO_ICMPV6);
 560
 561         /* Generate checksum */
 562
 563         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 564         checksum = inet_checksum(&ns, ns_size, checksum);
 565         checksum = inet_checksum(&opt, opt_size, checksum);
 566         checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 567
 568         ns.nd_ns_hdr.icmp6_cksum = checksum;
 569
 570         /* Copy structs on stack back to packet */
 571
 572         memcpy(packet->data + ether_size, &ip6, ip6_size);
 573         memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
 574         memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
 575
 576         send_packet(source, packet);
 577 }
 578
 579 static __inline__ void route_ipv6(node_t *source, vpn_packet_t *packet)
 580 {
 581         cp();
 582
 583         if(!checklength(source, packet, ether_size + ip6_size))
 584                 return;
 585
 586         if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
 587                 route_neighborsol(source, packet);
 588                 return;
 589         }
 590
 591         route_ipv6_unicast(source, packet);
 592 }
 593
 594 /* RFC 826 */
 595
 596 static void route_arp(node_t *source, vpn_packet_t *packet)
 597 {
 598         struct ether_arp arp;
 599         subnet_t *subnet;
 600         struct in_addr addr;
 601
 602         cp();
 603
 604         if(!checklength(source, packet, ether_size + arp_size))
 605                 return;
 606
 607         if(source != myself) {
 608                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got ARP request from %s (%s) while in router mode!"), source->name, source->hostname);
 609                 return;
 610         }
 611
 612         /* First, snatch the source address from the ARP packet */
 613
 614         if(overwrite_mac)
 615                 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
 616
 617         /* Copy headers from packet to structs on the stack */
 618
 619         memcpy(&arp, packet->data + ether_size, arp_size);
 620
 621         /* Check if this is a valid ARP request */
 622
 623         if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
 624            arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
 625                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type ARP request"));
 626                 return;
 627         }
 628
 629         /* Check if the IPv4 address exists on the VPN */
 630
 631         subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
 632
 633         if(!subnet) {
 634                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"),
 635                                    arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
 636                                    arp.arp_tpa[3]);
 637                 return;
 638         }
 639
 640         /* Check if it is for our own subnet */
 641
 642         if(subnet->owner == myself)
 643                 return;                                 /* silently ignore */
 644
 645         memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN);        /* copy destination address */
 646         packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
 647
 648         memcpy(&addr, arp.arp_tpa, sizeof(addr));       /* save protocol addr */
 649         memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */
 650         memcpy(arp.arp_spa, &addr, sizeof(addr));       /* ... */
 651
 652         memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN);     /* set target hard/proto addr */
 653         memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
 654         arp.arp_op = htons(ARPOP_REPLY);
 655
 656         /* Copy structs on stack back to packet */
 657
 658         memcpy(packet->data + ether_size, &arp, arp_size);
 659
 660         send_packet(source, packet);
 661 }
 662
 663 void route(node_t *source, vpn_packet_t *packet)
 664 {
 665         cp();
 666
 667         if(!checklength(source, packet, ether_size))
 668                 return;
 669
 670         switch (routing_mode) {
 671                 case RMODE_ROUTER:
 672                         {
 673                                 uint16_t type;
 674
 675                                 type = ntohs(*((uint16_t *)(&packet->data[12])));
 676                                 switch (type) {
 677                                         case ETH_P_ARP:
 678                                                 route_arp(source, packet);
 679                                                 break;
 680
 681                                         case ETH_P_IP:
 682                                                 route_ipv4(source, packet);
 683                                                 break;
 684
 685                                         case ETH_P_IPV6:
 686                                                 route_ipv6(source, packet);
 687                                                 break;
 688
 689                                         default:
 690                                                 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown type %hx"), source->name, source->hostname, type);
 691                                                 break;
 692                                 }
 693                         }
 694                         break;
 695
 696                 case RMODE_SWITCH:
 697                         route_mac(source, packet);
 698                         break;
 699
 700                 case RMODE_HUB:
 701                         broadcast_packet(source, packet);
 702                         break;
 703         }
 704 }