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

   1 /*
   2     route.c -- routing
   3     Copyright (C) 2000-2005 Ivo Timmermans,
   4                   2000-2013 Guus Sliepen <guus@tinc-vpn.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 along
  17     with this program; if not, write to the Free Software Foundation, Inc.,
  18     51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21 #include "system.h"
  22
  23 #include "connection.h"
  24 #include "control_common.h"
  25 #include "ethernet.h"
  26 #include "ipv4.h"
  27 #include "ipv6.h"
  28 #include "logger.h"
  29 #include "meta.h"
  30 #include "net.h"
  31 #include "protocol.h"
  32 #include "route.h"
  33 #include "subnet.h"
  34 #include "utils.h"
  35
  36 rmode_t routing_mode = RMODE_ROUTER;
  37 fmode_t forwarding_mode = FMODE_INTERNAL;
  38 bmode_t broadcast_mode = BMODE_MST;
  39 bool decrement_ttl = false;
  40 bool directonly = false;
  41 bool priorityinheritance = false;
  42 int macexpire = 600;
  43 bool overwrite_mac = false;
  44 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
  45 bool pcap = false;
  46
  47 /* Sizes of various headers */
  48
  49 static const size_t ether_size = sizeof(struct ether_header);
  50 static const size_t arp_size = sizeof(struct ether_arp);
  51 static const size_t ip_size = sizeof(struct ip);
  52 static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip);
  53 static const size_t ip6_size = sizeof(struct ip6_hdr);
  54 static const size_t icmp6_size = sizeof(struct icmp6_hdr);
  55 static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
  56 static const size_t opt_size = sizeof(struct nd_opt_hdr);
  57
  58 #ifndef MAX
  59 #define MAX(a, b) ((a) > (b) ? (a) : (b))
  60 #endif
  61
  62 static timeout_t age_subnets_timeout;
  63
  64 /* RFC 1071 */
  65
  66 static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) {
  67         uint16_t *p = data;
  68         uint32_t checksum = prevsum ^ 0xFFFF;
  69
  70         while(len >= 2) {
  71                 checksum += *p++;
  72                 len -= 2;
  73         }
  74
  75         if(len) {
  76                 checksum += *(uint8_t *)p;
  77         }
  78
  79         while(checksum >> 16) {
  80                 checksum = (checksum & 0xFFFF) + (checksum >> 16);
  81         }
  82
  83         return ~checksum;
  84 }
  85
  86 static bool ratelimit(int frequency) {
  87         static time_t lasttime = 0;
  88         static int count = 0;
  89
  90         if(lasttime == now.tv_sec) {
  91                 if(count >= frequency) {
  92                         return true;
  93                 }
  94         } else {
  95                 lasttime = now.tv_sec;
  96                 count = 0;
  97         }
  98
  99         count++;
 100         return false;
 101 }
 102
 103 static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
 104         if(packet->len < length) {
 105                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got too short packet from %s (%s)", source->name, source->hostname);
 106                 return false;
 107         } else {
 108                 return true;
 109         }
 110 }
 111
 112 static void swap_mac_addresses(vpn_packet_t *packet) {
 113         mac_t tmp;
 114         memcpy(&tmp, &DATA(packet)[0], sizeof(tmp));
 115         memcpy(&DATA(packet)[0], &DATA(packet)[6], sizeof(tmp));
 116         memcpy(&DATA(packet)[6], &tmp, sizeof(tmp));
 117 }
 118
 119 /* RFC 792 */
 120
 121 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
 122         struct ip ip = {0};
 123         struct icmp icmp = {0};
 124
 125         struct in_addr ip_src;
 126         struct in_addr ip_dst;
 127         uint32_t oldlen;
 128
 129         if(ratelimit(3)) {
 130                 return;
 131         }
 132
 133         /* Swap Ethernet source and destination addresses */
 134
 135         swap_mac_addresses(packet);
 136
 137         /* Copy headers from packet into properly aligned structs on the stack */
 138
 139         memcpy(&ip, DATA(packet) + ether_size, ip_size);
 140
 141         /* Remember original source and destination */
 142
 143         ip_src = ip.ip_src;
 144         ip_dst = ip.ip_dst;
 145
 146         /* Try to reply with an IP address assigned to the local machine */
 147
 148         if(type == ICMP_TIME_EXCEEDED && code == ICMP_EXC_TTL) {
 149                 int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
 150
 151                 if(sockfd != -1) {
 152                         struct sockaddr_in addr;
 153                         memset(&addr, 0, sizeof(addr));
 154                         addr.sin_family = AF_INET;
 155                         addr.sin_addr = ip.ip_src;
 156
 157                         if(!connect(sockfd, (const struct sockaddr *) &addr, sizeof(addr))) {
 158                                 memset(&addr, 0, sizeof(addr));
 159                                 addr.sin_family = AF_INET;
 160                                 socklen_t addrlen = sizeof(addr);
 161
 162                                 if(!getsockname(sockfd, (struct sockaddr *) &addr, &addrlen) && addrlen <= sizeof(addr)) {
 163                                         ip_dst = addr.sin_addr;
 164                                 }
 165                         }
 166
 167                         close(sockfd);
 168                 }
 169         }
 170
 171         oldlen = packet->len - ether_size;
 172
 173         if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 174                 icmp.icmp_nextmtu = htons(packet->len - ether_size);
 175         }
 176
 177         if(oldlen >= IP_MSS - ip_size - icmp_size) {
 178                 oldlen = IP_MSS - ip_size - icmp_size;
 179         }
 180
 181         /* Copy first part of original contents to ICMP message */
 182
 183         memmove(DATA(packet) + ether_size + ip_size + icmp_size, DATA(packet) + ether_size, oldlen);
 184
 185         /* Fill in IPv4 header */
 186
 187         ip.ip_v = 4;
 188         ip.ip_hl = ip_size / 4;
 189         ip.ip_tos = 0;
 190         ip.ip_len = htons(ip_size + icmp_size + oldlen);
 191         ip.ip_id = 0;
 192         ip.ip_off = 0;
 193         ip.ip_ttl = 255;
 194         ip.ip_p = IPPROTO_ICMP;
 195         ip.ip_sum = 0;
 196         ip.ip_src = ip_dst;
 197         ip.ip_dst = ip_src;
 198
 199         ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
 200
 201         /* Fill in ICMP header */
 202
 203         icmp.icmp_type = type;
 204         icmp.icmp_code = code;
 205         icmp.icmp_cksum = 0;
 206
 207         icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
 208         icmp.icmp_cksum = inet_checksum(DATA(packet) + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
 209
 210         /* Copy structs on stack back to packet */
 211
 212         memcpy(DATA(packet) + ether_size, &ip, ip_size);
 213         memcpy(DATA(packet) + ether_size + ip_size, &icmp, icmp_size);
 214
 215         packet->len = ether_size + ip_size + icmp_size + oldlen;
 216
 217         send_packet(source, packet);
 218 }
 219
 220 /* RFC 2463 */
 221
 222 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
 223         struct ip6_hdr ip6;
 224         struct icmp6_hdr icmp6 = {0};
 225         uint16_t checksum;
 226
 227         struct {
 228                 struct in6_addr ip6_src;        /* source address */
 229                 struct in6_addr ip6_dst;        /* destination address */
 230                 uint32_t length;
 231                 uint32_t next;
 232         } pseudo;
 233
 234         if(ratelimit(3)) {
 235                 return;
 236         }
 237
 238         /* Swap Ethernet source and destination addresses */
 239
 240         swap_mac_addresses(packet);
 241
 242         /* Copy headers from packet to structs on the stack */
 243
 244         memcpy(&ip6, DATA(packet) + ether_size, ip6_size);
 245
 246         /* Remember original source and destination */
 247
 248         pseudo.ip6_src = ip6.ip6_dst;
 249         pseudo.ip6_dst = ip6.ip6_src;
 250
 251         /* Try to reply with an IP address assigned to the local machine */
 252
 253         if(type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT) {
 254                 int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
 255
 256                 if(sockfd != -1) {
 257                         struct sockaddr_in6 addr;
 258                         memset(&addr, 0, sizeof(addr));
 259                         addr.sin6_family = AF_INET6;
 260                         addr.sin6_addr = ip6.ip6_src;
 261
 262                         if(!connect(sockfd, (const struct sockaddr *) &addr, sizeof(addr))) {
 263                                 memset(&addr, 0, sizeof(addr));
 264                                 addr.sin6_family = AF_INET6;
 265                                 socklen_t addrlen = sizeof(addr);
 266
 267                                 if(!getsockname(sockfd, (struct sockaddr *) &addr, &addrlen) && addrlen <= sizeof(addr)) {
 268                                         pseudo.ip6_src = addr.sin6_addr;
 269                                 }
 270                         }
 271
 272                         close(sockfd);
 273                 }
 274         }
 275
 276         pseudo.length = packet->len - ether_size;
 277
 278         if(type == ICMP6_PACKET_TOO_BIG) {
 279                 icmp6.icmp6_mtu = htonl(pseudo.length);
 280         }
 281
 282         if(pseudo.length >= IP_MSS - ip6_size - icmp6_size) {
 283                 pseudo.length = IP_MSS - ip6_size - icmp6_size;
 284         }
 285
 286         /* Copy first part of original contents to ICMP message */
 287
 288         memmove(DATA(packet) + ether_size + ip6_size + icmp6_size, DATA(packet) + ether_size, pseudo.length);
 289
 290         /* Fill in IPv6 header */
 291
 292         ip6.ip6_flow = htonl(0x60000000UL);
 293         ip6.ip6_plen = htons(icmp6_size + pseudo.length);
 294         ip6.ip6_nxt = IPPROTO_ICMPV6;
 295         ip6.ip6_hlim = 255;
 296         ip6.ip6_src = pseudo.ip6_src;
 297         ip6.ip6_dst = pseudo.ip6_dst;
 298
 299         /* Fill in ICMP header */
 300
 301         icmp6.icmp6_type = type;
 302         icmp6.icmp6_code = code;
 303         icmp6.icmp6_cksum = 0;
 304
 305         /* Create pseudo header */
 306
 307         pseudo.length = htonl(icmp6_size + pseudo.length);
 308         pseudo.next = htonl(IPPROTO_ICMPV6);
 309
 310         /* Generate checksum */
 311
 312         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 313         checksum = inet_checksum(&icmp6, icmp6_size, checksum);
 314         checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
 315
 316         icmp6.icmp6_cksum = checksum;
 317
 318         /* Copy structs on stack back to packet */
 319
 320         memcpy(DATA(packet) + ether_size, &ip6, ip6_size);
 321         memcpy(DATA(packet) + ether_size + ip6_size, &icmp6, icmp6_size);
 322
 323         packet->len = ether_size + ip6_size + ntohl(pseudo.length);
 324
 325         send_packet(source, packet);
 326 }
 327
 328 static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet) {
 329         uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
 330         length_t ethlen = ether_size;
 331
 332         if(type == ETH_P_8021Q) {
 333                 type = DATA(packet)[16] << 8 | DATA(packet)[17];
 334                 ethlen += 4;
 335         }
 336
 337         switch(type) {
 338         case ETH_P_IP:
 339                 if(!checklength(source, packet, ethlen + ip_size)) {
 340                         return false;
 341                 }
 342
 343                 if(DATA(packet)[ethlen + 8] <= 1) {
 344                         if(DATA(packet)[ethlen + 11] != IPPROTO_ICMP || DATA(packet)[ethlen + 32] != ICMP_TIME_EXCEEDED) {
 345                                 route_ipv4_unreachable(source, packet, ethlen, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL);
 346                         }
 347
 348                         return false;
 349                 }
 350
 351                 uint16_t old = DATA(packet)[ethlen + 8] << 8 | DATA(packet)[ethlen + 9];
 352                 DATA(packet)[ethlen + 8]--;
 353                 uint16_t new = DATA(packet)[ethlen + 8] << 8 | DATA(packet)[ethlen + 9];
 354
 355                 uint32_t checksum = DATA(packet)[ethlen + 10] << 8 | DATA(packet)[ethlen + 11];
 356                 checksum += old + (~new & 0xFFFF);
 357
 358                 while(checksum >> 16) {
 359                         checksum = (checksum & 0xFFFF) + (checksum >> 16);
 360                 }
 361
 362                 DATA(packet)[ethlen + 10] = checksum >> 8;
 363                 DATA(packet)[ethlen + 11] = checksum & 0xff;
 364
 365                 return true;
 366
 367         case ETH_P_IPV6:
 368                 if(!checklength(source, packet, ethlen + ip6_size)) {
 369                         return false;
 370                 }
 371
 372                 if(DATA(packet)[ethlen + 7] <= 1) {
 373                         if(DATA(packet)[ethlen + 6] != IPPROTO_ICMPV6 || DATA(packet)[ethlen + 40] != ICMP6_TIME_EXCEEDED) {
 374                                 route_ipv6_unreachable(source, packet, ethlen, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT);
 375                         }
 376
 377                         return false;
 378                 }
 379
 380                 DATA(packet)[ethlen + 7]--;
 381
 382                 return true;
 383
 384         default:
 385                 return true;
 386         }
 387 }
 388
 389 static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
 390         if(!source || !via || !(via->options & OPTION_CLAMP_MSS)) {
 391                 return;
 392         }
 393
 394         uint16_t mtu = source->mtu;
 395
 396         if(via != myself && via->mtu < mtu) {
 397                 mtu = via->mtu;
 398         }
 399
 400         /* Find TCP header */
 401         int start = ether_size;
 402         uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
 403
 404         if(type == ETH_P_8021Q) {
 405                 start += 4;
 406                 type = DATA(packet)[16] << 8 | DATA(packet)[17];
 407         }
 408
 409         if(type == ETH_P_IP && DATA(packet)[start + 9] == 6) {
 410                 start += (DATA(packet)[start] & 0xf) * 4;
 411         } else if(type == ETH_P_IPV6 && DATA(packet)[start + 6] == 6) {
 412                 start += 40;
 413         } else {
 414                 return;
 415         }
 416
 417         if(packet->len <= start + 20) {
 418                 return;
 419         }
 420
 421         /* Use data offset field to calculate length of options field */
 422         int len = ((DATA(packet)[start + 12] >> 4) - 5) * 4;
 423
 424         if(packet->len < start + 20 + len) {
 425                 return;
 426         }
 427
 428         /* Search for MSS option header */
 429         for(int i = 0; i < len;) {
 430                 if(DATA(packet)[start + 20 + i] == 0) {
 431                         break;
 432                 }
 433
 434                 if(DATA(packet)[start + 20 + i] == 1) {
 435                         i++;
 436                         continue;
 437                 }
 438
 439                 if(i > len - 2 || i > len - DATA(packet)[start + 21 + i]) {
 440                         break;
 441                 }
 442
 443                 if(DATA(packet)[start + 20 + i] != 2) {
 444                         if(DATA(packet)[start + 21 + i] < 2) {
 445                                 break;
 446                         }
 447
 448                         i += DATA(packet)[start + 21 + i];
 449                         continue;
 450                 }
 451
 452                 if(DATA(packet)[start + 21] != 4) {
 453                         break;
 454                 }
 455
 456                 /* Found it */
 457                 uint16_t oldmss = DATA(packet)[start + 22 + i] << 8 | DATA(packet)[start + 23 + i];
 458                 uint16_t newmss = mtu - start - 20;
 459                 uint32_t csum = DATA(packet)[start + 16] << 8 | DATA(packet)[start + 17];
 460
 461                 if(oldmss <= newmss) {
 462                         break;
 463                 }
 464
 465                 logger(DEBUG_TRAFFIC, LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
 466
 467                 /* Update the MSS value and the checksum */
 468                 DATA(packet)[start + 22 + i] = newmss >> 8;
 469                 DATA(packet)[start + 23 + i] = newmss & 0xff;
 470                 csum ^= 0xffff;
 471                 csum += oldmss ^ 0xffff;
 472                 csum += newmss;
 473                 csum = (csum & 0xffff) + (csum >> 16);
 474                 csum += csum >> 16;
 475                 csum ^= 0xffff;
 476                 DATA(packet)[start + 16] = csum >> 8;
 477                 DATA(packet)[start + 17] = csum;
 478                 break;
 479         }
 480 }
 481
 482 static void age_subnets(void *data) {
 483         bool left = false;
 484
 485         for splay_each(subnet_t, s, myself->subnet_tree) {
 486                 if(s->expires && s->expires < now.tv_sec) {
 487                         if(debug_level >= DEBUG_TRAFFIC) {
 488                                 char netstr[MAXNETSTR];
 489
 490                                 if(net2str(netstr, sizeof(netstr), s)) {
 491                                         logger(DEBUG_TRAFFIC, LOG_INFO, "Subnet %s expired", netstr);
 492                                 }
 493                         }
 494
 495                         for list_each(connection_t, c, connection_list)
 496                                 if(c->edge) {
 497                                         send_del_subnet(c, s);
 498                                 }
 499
 500                         subnet_del(myself, s);
 501                 } else {
 502                         if(s->expires) {
 503                                 left = true;
 504                         }
 505                 }
 506         }
 507
 508         if(left)
 509                 timeout_set(&age_subnets_timeout, &(struct timeval) {
 510                 10, rand() % 100000
 511         });
 512 }
 513
 514 static void learn_mac(mac_t *address) {
 515         subnet_t *subnet = lookup_subnet_mac(myself, address);
 516
 517         /* If we don't know this MAC address yet, store it */
 518
 519         if(!subnet) {
 520                 logger(DEBUG_TRAFFIC, LOG_INFO, "Learned new MAC address %x:%x:%x:%x:%x:%x",
 521                        address->x[0], address->x[1], address->x[2], address->x[3],
 522                        address->x[4], address->x[5]);
 523
 524                 subnet = new_subnet();
 525                 subnet->type = SUBNET_MAC;
 526                 subnet->expires = now.tv_sec + macexpire;
 527                 subnet->net.mac.address = *address;
 528                 subnet->weight = 10;
 529                 subnet_add(myself, subnet);
 530                 subnet_update(myself, subnet, true);
 531
 532                 /* And tell all other tinc daemons it's our MAC */
 533
 534                 for list_each(connection_t, c, connection_list)
 535                         if(c->edge) {
 536                                 send_add_subnet(c, subnet);
 537                         }
 538
 539                 timeout_add(&age_subnets_timeout, age_subnets, NULL, &(struct timeval) {
 540                         10, rand() % 100000
 541                 });
 542         } else {
 543                 if(subnet->expires) {
 544                         subnet->expires = now.tv_sec + macexpire;
 545                 }
 546         }
 547 }
 548
 549 static void route_broadcast(node_t *source, vpn_packet_t *packet) {
 550         if(decrement_ttl && source != myself)
 551                 if(!do_decrement_ttl(source, packet)) {
 552                         return;
 553                 }
 554
 555         broadcast_packet(source, packet);
 556 }
 557
 558 /* RFC 791 */
 559
 560 static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t ether_size) {
 561         struct ip ip;
 562         vpn_packet_t fragment;
 563         int maxlen, todo;
 564         uint8_t *offset;
 565         uint16_t ip_off, origf;
 566
 567         memcpy(&ip, DATA(packet) + ether_size, ip_size);
 568         fragment.priority = packet->priority;
 569         fragment.offset = DEFAULT_PACKET_OFFSET;
 570
 571         if(ip.ip_hl != ip_size / 4) {
 572                 return;
 573         }
 574
 575         todo = ntohs(ip.ip_len) - ip_size;
 576
 577         if(ether_size + ip_size + todo != packet->len) {
 578                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Length of packet (%d) doesn't match length in IPv4 header (%d)", packet->len, (int)(ether_size + ip_size + todo));
 579                 return;
 580         }
 581
 582         logger(DEBUG_TRAFFIC, LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
 583
 584         offset = DATA(packet) + ether_size + ip_size;
 585         maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
 586         ip_off = ntohs(ip.ip_off);
 587         origf = ip_off & ~IP_OFFMASK;
 588         ip_off &= IP_OFFMASK;
 589
 590         while(todo) {
 591                 int len = todo > maxlen ? maxlen : todo;
 592                 memcpy(DATA(&fragment) + ether_size + ip_size, offset, len);
 593                 todo -= len;
 594                 offset += len;
 595
 596                 ip.ip_len = htons(ip_size + len);
 597                 ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
 598                 ip.ip_sum = 0;
 599                 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
 600                 memcpy(DATA(&fragment), DATA(packet), ether_size);
 601                 memcpy(DATA(&fragment) + ether_size, &ip, ip_size);
 602                 fragment.len = ether_size + ip_size + len;
 603
 604                 send_packet(dest, &fragment);
 605
 606                 ip_off += len / 8;
 607         }
 608 }
 609
 610 static void route_ipv4(node_t *source, vpn_packet_t *packet) {
 611         if(!checklength(source, packet, ether_size + ip_size)) {
 612                 return;
 613         }
 614
 615         subnet_t *subnet;
 616         node_t *via;
 617         ipv4_t dest;
 618
 619         memcpy(&dest, &DATA(packet)[30], sizeof(dest));
 620         subnet = lookup_subnet_ipv4(&dest);
 621
 622         if(!subnet) {
 623                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d",
 624                        source->name, source->hostname,
 625                        dest.x[0],
 626                        dest.x[1],
 627                        dest.x[2],
 628                        dest.x[3]);
 629
 630                 route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
 631                 return;
 632         }
 633
 634         if(!subnet->owner) {
 635                 route_broadcast(source, packet);
 636                 return;
 637         }
 638
 639         if(subnet->owner == source) {
 640                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
 641                 return;
 642         }
 643
 644         if(!subnet->owner->status.reachable) {
 645                 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
 646         }
 647
 648         if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself) {
 649                 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
 650         }
 651
 652         if(decrement_ttl && source != myself && subnet->owner != myself)
 653                 if(!do_decrement_ttl(source, packet)) {
 654                         return;
 655                 }
 656
 657         if(priorityinheritance) {
 658                 packet->priority = DATA(packet)[15];
 659         }
 660
 661         via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
 662
 663         if(via == source) {
 664                 logger(DEBUG_TRAFFIC, LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
 665                 return;
 666         }
 667
 668         if(directonly && subnet->owner != via) {
 669                 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
 670         }
 671
 672         if(via && packet->len > MAX(via->mtu, 590) && via != myself) {
 673                 logger(DEBUG_TRAFFIC, LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
 674
 675                 if(DATA(packet)[20] & 0x40) {
 676                         packet->len = MAX(via->mtu, 590);
 677                         route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
 678                 } else {
 679                         fragment_ipv4_packet(via, packet, ether_size);
 680                 }
 681
 682                 return;
 683         }
 684
 685         clamp_mss(source, via, packet);
 686
 687         send_packet(subnet->owner, packet);
 688 }
 689
 690 static void route_neighborsol(node_t *source, vpn_packet_t *packet);
 691
 692 static void route_ipv6(node_t *source, vpn_packet_t *packet) {
 693         if(!checklength(source, packet, ether_size + ip6_size)) {
 694                 return;
 695         }
 696
 697         if(DATA(packet)[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && DATA(packet)[54] == ND_NEIGHBOR_SOLICIT) {
 698                 route_neighborsol(source, packet);
 699                 return;
 700         }
 701
 702         subnet_t *subnet;
 703         node_t *via;
 704         ipv6_t dest;
 705
 706         memcpy(&dest, &DATA(packet)[38], sizeof(dest));
 707         subnet = lookup_subnet_ipv6(&dest);
 708
 709         if(!subnet) {
 710                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
 711                        source->name, source->hostname,
 712                        ntohs(dest.x[0]),
 713                        ntohs(dest.x[1]),
 714                        ntohs(dest.x[2]),
 715                        ntohs(dest.x[3]),
 716                        ntohs(dest.x[4]),
 717                        ntohs(dest.x[5]),
 718                        ntohs(dest.x[6]),
 719                        ntohs(dest.x[7]));
 720
 721                 route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
 722                 return;
 723         }
 724
 725         if(!subnet->owner) {
 726                 route_broadcast(source, packet);
 727                 return;
 728         }
 729
 730         if(subnet->owner == source) {
 731                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
 732                 return;
 733         }
 734
 735         if(!subnet->owner->status.reachable) {
 736                 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
 737         }
 738
 739         if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself) {
 740                 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
 741         }
 742
 743         if(decrement_ttl && source != myself && subnet->owner != myself)
 744                 if(!do_decrement_ttl(source, packet)) {
 745                         return;
 746                 }
 747
 748         if(priorityinheritance) {
 749                 packet->priority = ((DATA(packet)[14] & 0x0f) << 4) | (DATA(packet)[15] >> 4);
 750         }
 751
 752         via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
 753
 754         if(via == source) {
 755                 logger(DEBUG_TRAFFIC, LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
 756                 return;
 757         }
 758
 759         if(directonly && subnet->owner != via) {
 760                 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
 761         }
 762
 763         if(via && packet->len > MAX(via->mtu, 1294) && via != myself) {
 764                 logger(DEBUG_TRAFFIC, LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
 765                 packet->len = MAX(via->mtu, 1294);
 766                 route_ipv6_unreachable(source, packet, ether_size, ICMP6_PACKET_TOO_BIG, 0);
 767                 return;
 768         }
 769
 770         clamp_mss(source, via, packet);
 771
 772         send_packet(subnet->owner, packet);
 773 }
 774
 775 /* RFC 2461 */
 776
 777 static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
 778         struct ip6_hdr ip6;
 779         struct nd_neighbor_solicit ns;
 780         struct nd_opt_hdr opt;
 781         subnet_t *subnet;
 782         uint16_t checksum;
 783         bool has_opt;
 784
 785         struct {
 786                 struct in6_addr ip6_src;
 787                 struct in6_addr ip6_dst;
 788                 uint32_t length;
 789                 uint32_t next;
 790         } pseudo;
 791
 792         if(!checklength(source, packet, ether_size + ip6_size + ns_size)) {
 793                 return;
 794         }
 795
 796         has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
 797
 798         if(source != myself) {
 799                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname);
 800                 return;
 801         }
 802
 803         /* Copy headers from packet to structs on the stack */
 804
 805         memcpy(&ip6, DATA(packet) + ether_size, ip6_size);
 806         memcpy(&ns, DATA(packet) + ether_size + ip6_size, ns_size);
 807
 808         if(has_opt) {
 809                 memcpy(&opt, DATA(packet) + ether_size + ip6_size + ns_size, opt_size);
 810         }
 811
 812         /* First, snatch the source address from the neighbor solicitation packet */
 813
 814         if(overwrite_mac) {
 815                 memcpy(mymac.x, DATA(packet) + ETH_ALEN, ETH_ALEN);
 816         }
 817
 818         /* Check if this is a valid neighbor solicitation request */
 819
 820         if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
 821                         (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
 822                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request");
 823                 return;
 824         }
 825
 826         /* Create pseudo header */
 827
 828         pseudo.ip6_src = ip6.ip6_src;
 829         pseudo.ip6_dst = ip6.ip6_dst;
 830
 831         if(has_opt) {
 832                 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 833         } else {
 834                 pseudo.length = htonl(ns_size);
 835         }
 836
 837         pseudo.next = htonl(IPPROTO_ICMPV6);
 838
 839         /* Generate checksum */
 840
 841         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 842         checksum = inet_checksum(&ns, ns_size, checksum);
 843
 844         if(has_opt) {
 845                 checksum = inet_checksum(&opt, opt_size, checksum);
 846                 checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 847         }
 848
 849         if(checksum) {
 850                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request");
 851                 return;
 852         }
 853
 854         /* Check if the IPv6 address exists on the VPN */
 855
 856         subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
 857
 858         if(!subnet) {
 859                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
 860                        ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
 861                        ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
 862                        ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
 863                        ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
 864                        ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
 865                        ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
 866                        ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
 867                        ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
 868
 869                 return;
 870         }
 871
 872         /* Check if it is for our own subnet */
 873
 874         if(subnet->owner == myself) {
 875                 return;        /* silently ignore */
 876         }
 877
 878         if(decrement_ttl)
 879                 if(!do_decrement_ttl(source, packet)) {
 880                         return;
 881                 }
 882
 883         /* Create neighbor advertation reply */
 884
 885         memcpy(DATA(packet), DATA(packet) + ETH_ALEN, ETH_ALEN); /* copy destination address */
 886         DATA(packet)[ETH_ALEN * 2 - 1] ^= 0xFF;                  /* mangle source address so it looks like it's not from us */
 887
 888         ip6.ip6_dst = ip6.ip6_src;                               /* swap destination and source protocoll address */
 889         ip6.ip6_src = ns.nd_ns_target;
 890
 891         if(has_opt) {
 892                 memcpy(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, DATA(packet) + ETH_ALEN, ETH_ALEN);        /* add fake source hard addr */
 893         }
 894
 895         ns.nd_ns_cksum = 0;
 896         ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
 897         ns.nd_ns_reserved = htonl(0x40000000UL);                 /* Set solicited flag */
 898         opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
 899
 900         /* Create pseudo header */
 901
 902         pseudo.ip6_src = ip6.ip6_src;
 903         pseudo.ip6_dst = ip6.ip6_dst;
 904
 905         if(has_opt) {
 906                 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
 907         } else {
 908                 pseudo.length = htonl(ns_size);
 909         }
 910
 911         pseudo.next = htonl(IPPROTO_ICMPV6);
 912
 913         /* Generate checksum */
 914
 915         checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 916         checksum = inet_checksum(&ns, ns_size, checksum);
 917
 918         if(has_opt) {
 919                 checksum = inet_checksum(&opt, opt_size, checksum);
 920                 checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
 921         }
 922
 923         ns.nd_ns_hdr.icmp6_cksum = checksum;
 924
 925         /* Copy structs on stack back to packet */
 926
 927         memcpy(DATA(packet) + ether_size, &ip6, ip6_size);
 928         memcpy(DATA(packet) + ether_size + ip6_size, &ns, ns_size);
 929
 930         if(has_opt) {
 931                 memcpy(DATA(packet) + ether_size + ip6_size + ns_size, &opt, opt_size);
 932         }
 933
 934         send_packet(source, packet);
 935 }
 936
 937 /* RFC 826 */
 938
 939 static void route_arp(node_t *source, vpn_packet_t *packet) {
 940         struct ether_arp arp;
 941         subnet_t *subnet;
 942         struct in_addr addr;
 943
 944         if(!checklength(source, packet, ether_size + arp_size)) {
 945                 return;
 946         }
 947
 948         if(source != myself) {
 949                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname);
 950                 return;
 951         }
 952
 953         /* First, snatch the source address from the ARP packet */
 954
 955         if(overwrite_mac) {
 956                 memcpy(mymac.x, DATA(packet) + ETH_ALEN, ETH_ALEN);
 957         }
 958
 959         /* Copy headers from packet to structs on the stack */
 960
 961         memcpy(&arp, DATA(packet) + ether_size, arp_size);
 962
 963         /* Check if this is a valid ARP request */
 964
 965         if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
 966                         arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
 967                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: received unknown type ARP request");
 968                 return;
 969         }
 970
 971         /* Check if the IPv4 address exists on the VPN */
 972
 973         subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
 974
 975         if(!subnet) {
 976                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d",
 977                        arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
 978                        arp.arp_tpa[3]);
 979                 return;
 980         }
 981
 982         /* Check if it is for our own subnet */
 983
 984         if(subnet->owner == myself) {
 985                 return;        /* silently ignore */
 986         }
 987
 988         if(decrement_ttl)
 989                 if(!do_decrement_ttl(source, packet)) {
 990                         return;
 991                 }
 992
 993         memcpy(&addr, arp.arp_tpa, sizeof(addr));                 /* save protocol addr */
 994         memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr));           /* swap destination and source protocol address */
 995         memcpy(arp.arp_spa, &addr, sizeof(addr));                 /* ... */
 996
 997         memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN);              /* set target hard/proto addr */
 998         memcpy(arp.arp_sha, DATA(packet) + ETH_ALEN, ETH_ALEN);  /* set source hard/proto addr */
 999         arp.arp_sha[ETH_ALEN - 1] ^= 0xFF;                       /* for consistency with route_packet() */
1000         arp.arp_op = htons(ARPOP_REPLY);
1001
1002         /* Copy structs on stack back to packet */
1003
1004         memcpy(DATA(packet) + ether_size, &arp, arp_size);
1005
1006         send_packet(source, packet);
1007 }
1008
1009 static void route_mac(node_t *source, vpn_packet_t *packet) {
1010         subnet_t *subnet;
1011         mac_t dest;
1012
1013         /* Learn source address */
1014
1015         if(source == myself) {
1016                 mac_t src;
1017                 memcpy(&src, &DATA(packet)[6], sizeof(src));
1018                 learn_mac(&src);
1019         }
1020
1021         /* Lookup destination address */
1022
1023         memcpy(&dest, &DATA(packet)[0], sizeof(dest));
1024         subnet = lookup_subnet_mac(NULL, &dest);
1025
1026         if(!subnet || !subnet->owner) {
1027                 route_broadcast(source, packet);
1028                 return;
1029         }
1030
1031         if(subnet->owner == source) {
1032                 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
1033                 return;
1034         }
1035
1036         if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself) {
1037                 return;
1038         }
1039
1040         if(decrement_ttl && source != myself && subnet->owner != myself)
1041                 if(!do_decrement_ttl(source, packet)) {
1042                         return;
1043                 }
1044
1045         uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
1046
1047         if(priorityinheritance) {
1048                 if(type == ETH_P_IP && packet->len >= ether_size + ip_size) {
1049                         packet->priority = DATA(packet)[15];
1050                 } else if(type == ETH_P_IPV6 && packet->len >= ether_size + ip6_size) {
1051                         packet->priority = ((DATA(packet)[14] & 0x0f) << 4) | (DATA(packet)[15] >> 4);
1052                 }
1053         }
1054
1055         // Handle packets larger than PMTU
1056
1057         node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
1058
1059         if(directonly && subnet->owner != via) {
1060                 return;
1061         }
1062
1063         if(via && packet->len > via->mtu && via != myself) {
1064                 logger(DEBUG_TRAFFIC, LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
1065                 length_t ethlen = 14;
1066
1067                 if(type == ETH_P_8021Q) {
1068                         type = DATA(packet)[16] << 8 | DATA(packet)[17];
1069                         ethlen += 4;
1070                 }
1071
1072                 if(type == ETH_P_IP && packet->len > 576 + ethlen) {
1073                         if(DATA(packet)[6 + ethlen] & 0x40) {
1074                                 packet->len = via->mtu;
1075                                 route_ipv4_unreachable(source, packet, ethlen, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
1076                         } else {
1077                                 fragment_ipv4_packet(via, packet, ethlen);
1078                         }
1079
1080                         return;
1081                 } else if(type == ETH_P_IPV6 && packet->len > 1280 + ethlen) {
1082                         packet->len = via->mtu;
1083                         route_ipv6_unreachable(source, packet, ethlen, ICMP6_PACKET_TOO_BIG, 0);
1084                         return;
1085                 }
1086         }
1087
1088         clamp_mss(source, via, packet);
1089
1090         send_packet(subnet->owner, packet);
1091 }
1092
1093 static void send_pcap(vpn_packet_t *packet) {
1094         pcap = false;
1095
1096         for list_each(connection_t, c, connection_list) {
1097                 if(!c->status.pcap) {
1098                         continue;
1099                 }
1100
1101                 pcap = true;
1102                 int len = packet->len;
1103
1104                 if(c->outmaclength && c->outmaclength < len) {
1105                         len = c->outmaclength;
1106                 }
1107
1108                 if(send_request(c, "%d %d %d", CONTROL, REQ_PCAP, len)) {
1109                         send_meta(c, (char *)DATA(packet), len);
1110                 }
1111         }
1112 }
1113
1114 void route(node_t *source, vpn_packet_t *packet) {
1115         if(pcap) {
1116                 send_pcap(packet);
1117         }
1118
1119         if(forwarding_mode == FMODE_KERNEL && source != myself) {
1120                 send_packet(myself, packet);
1121                 return;
1122         }
1123
1124         if(!checklength(source, packet, ether_size)) {
1125                 return;
1126         }
1127
1128         uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
1129
1130         switch(routing_mode) {
1131         case RMODE_ROUTER:
1132                 switch(type) {
1133                 case ETH_P_ARP:
1134                         route_arp(source, packet);
1135                         break;
1136
1137                 case ETH_P_IP:
1138                         route_ipv4(source, packet);
1139                         break;
1140
1141                 case ETH_P_IPV6:
1142                         route_ipv6(source, packet);
1143                         break;
1144
1145                 default:
1146                         logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type);
1147                         break;
1148                 }
1149
1150                 break;
1151
1152         case RMODE_SWITCH:
1153                 route_mac(source, packet);
1154                 break;
1155
1156         case RMODE_HUB:
1157                 route_broadcast(source, packet);
1158                 break;
1159         }
1160 }