3 Copyright (C) 2000-2005 Ivo Timmermans,
4 2000-2010 Guus Sliepen <guus@tinc-vpn.org>
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.
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.
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.
24 #include "connection.h"
35 rmode_t routing_mode = RMODE_ROUTER;
36 fmode_t forwarding_mode = FMODE_INTERNAL;
37 bool decrement_ttl = true;
38 bool directonly = false;
39 bool priorityinheritance = false;
41 bool overwrite_mac = false;
42 bool broadcast = true;
43 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
45 /* Sizes of various headers */
47 static const size_t ether_size = sizeof(struct ether_header);
48 static const size_t arp_size = sizeof(struct ether_arp);
49 static const size_t ip_size = sizeof(struct ip);
50 static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip);
51 static const size_t ip6_size = sizeof(struct ip6_hdr);
52 static const size_t icmp6_size = sizeof(struct icmp6_hdr);
53 static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
54 static const size_t opt_size = sizeof(struct nd_opt_hdr);
57 #define MAX(a, b) ((a) > (b) ? (a) : (b))
62 static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) {
64 uint32_t checksum = prevsum ^ 0xFFFF;
72 checksum += *(uint8_t *)p;
75 checksum = (checksum & 0xFFFF) + (checksum >> 16);
80 static bool ratelimit(int frequency) {
81 static time_t lasttime = 0;
85 if(count >= frequency)
96 static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
97 if(packet->len < length) {
98 ifdebug(TRAFFIC) logger(LOG_WARNING, "Got too short packet from %s (%s)", source->name, source->hostname);
104 static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
105 if(!source || !via || !(via->options & OPTION_CLAMP_MSS))
108 uint16_t mtu = source->mtu;
109 if(via != myself && via->mtu < mtu)
112 /* Find TCP header */
114 uint16_t type = packet->data[12] << 8 | packet->data[13];
116 if(type == ETH_P_IP && packet->data[23] == 6)
117 start = 14 + (packet->data[14] & 0xf) * 4;
118 else if(type == ETH_P_IPV6 && packet->data[20] == 6)
121 if(!start || packet->len <= start + 20)
124 /* Use data offset field to calculate length of options field */
125 int len = ((packet->data[start + 12] >> 4) - 5) * 4;
127 if(packet->len < start + 20 + len)
130 /* Search for MSS option header */
131 for(int i = 0; i < len;) {
132 if(packet->data[start + 20 + i] == 0)
135 if(packet->data[start + 20 + i] == 1) {
140 if(i > len - 2 || i > len - packet->data[start + 21 + i])
143 if(packet->data[start + 20 + i] != 2) {
144 if(packet->data[start + 21 + i] < 2)
146 i += packet->data[start + 21 + i];
150 if(packet->data[start + 21] != 4)
154 uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
155 uint16_t newmss = mtu - start - 20;
156 uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
161 ifdebug(TRAFFIC) logger(LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
163 /* Update the MSS value and the checksum */
164 packet->data[start + 22 + i] = newmss >> 8;
165 packet->data[start + 23 + i] = newmss & 0xff;
170 packet->data[start + 16] = csum >> 8;
171 packet->data[start + 17] = csum & 0xff;
176 static void swap_mac_addresses(vpn_packet_t *packet) {
178 memcpy(&tmp, &packet->data[0], sizeof tmp);
179 memcpy(&packet->data[0], &packet->data[6], sizeof tmp);
180 memcpy(&packet->data[6], &tmp, sizeof tmp);
183 static void learn_mac(mac_t *address) {
188 subnet = lookup_subnet_mac(myself, address);
190 /* If we don't know this MAC address yet, store it */
193 ifdebug(TRAFFIC) logger(LOG_INFO, "Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx",
194 address->x[0], address->x[1], address->x[2], address->x[3],
195 address->x[4], address->x[5]);
197 subnet = new_subnet();
198 subnet->type = SUBNET_MAC;
199 subnet->expires = now + macexpire;
200 subnet->net.mac.address = *address;
202 subnet_add(myself, subnet);
203 subnet_update(myself, subnet, true);
205 /* And tell all other tinc daemons it's our MAC */
207 for(node = connection_tree->head; node; node = node->next) {
210 send_add_subnet(c, subnet);
215 subnet->expires = now + macexpire;
218 void age_subnets(void) {
221 avl_node_t *node, *next, *node2;
223 for(node = myself->subnet_tree->head; node; node = next) {
226 if(s->expires && s->expires <= now) {
228 char netstr[MAXNETSTR];
229 if(net2str(netstr, sizeof netstr, s))
230 logger(LOG_INFO, "Subnet %s expired", netstr);
233 for(node2 = connection_tree->head; node2; node2 = node2->next) {
236 send_del_subnet(c, s);
239 subnet_update(myself, s, false);
240 subnet_del(myself, s);
247 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code) {
249 struct icmp icmp = {0};
251 struct in_addr ip_src;
252 struct in_addr ip_dst;
258 /* Swap Ethernet source and destination addresses */
260 swap_mac_addresses(packet);
262 /* Copy headers from packet into properly aligned structs on the stack */
264 memcpy(&ip, packet->data + ether_size, ip_size);
266 /* Remember original source and destination */
271 oldlen = packet->len - ether_size;
273 if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
274 icmp.icmp_nextmtu = htons(packet->len - ether_size);
276 if(oldlen >= IP_MSS - ip_size - icmp_size)
277 oldlen = IP_MSS - ip_size - icmp_size;
279 /* Copy first part of original contents to ICMP message */
281 memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
283 /* Fill in IPv4 header */
286 ip.ip_hl = ip_size / 4;
288 ip.ip_len = htons(ip_size + icmp_size + oldlen);
292 ip.ip_p = IPPROTO_ICMP;
297 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
299 /* Fill in ICMP header */
301 icmp.icmp_type = type;
302 icmp.icmp_code = code;
305 icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
306 icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
308 /* Copy structs on stack back to packet */
310 memcpy(packet->data + ether_size, &ip, ip_size);
311 memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
313 packet->len = ether_size + ip_size + icmp_size + oldlen;
315 send_packet(source, packet);
320 static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet) {
322 vpn_packet_t fragment;
323 int len, maxlen, todo;
325 uint16_t ip_off, origf;
327 memcpy(&ip, packet->data + ether_size, ip_size);
328 fragment.priority = packet->priority;
330 if(ip.ip_hl != ip_size / 4)
333 todo = ntohs(ip.ip_len) - ip_size;
335 if(ether_size + ip_size + todo != packet->len) {
336 ifdebug(TRAFFIC) logger(LOG_WARNING, "Length of packet (%d) doesn't match length in IPv4 header (%zd)", packet->len, ether_size + ip_size + todo);
340 ifdebug(TRAFFIC) logger(LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
342 offset = packet->data + ether_size + ip_size;
343 maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
344 ip_off = ntohs(ip.ip_off);
345 origf = ip_off & ~IP_OFFMASK;
346 ip_off &= IP_OFFMASK;
349 len = todo > maxlen ? maxlen : todo;
350 memcpy(fragment.data + ether_size + ip_size, offset, len);
354 ip.ip_len = htons(ip_size + len);
355 ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
357 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
358 memcpy(fragment.data, packet->data, ether_size);
359 memcpy(fragment.data + ether_size, &ip, ip_size);
360 fragment.len = ether_size + ip_size + len;
362 send_packet(dest, &fragment);
368 static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
373 memcpy(&dest, &packet->data[30], sizeof dest);
374 subnet = lookup_subnet_ipv4(&dest);
377 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d",
378 source->name, source->hostname,
384 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
388 if(subnet->owner == source) {
389 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
393 if(!subnet->owner->status.reachable)
394 return route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
396 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
397 return route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_ANO);
399 if(priorityinheritance)
400 packet->priority = packet->data[15];
402 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
404 if(directonly && subnet->owner != via)
405 return route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_ANO);
407 if(via && packet->len > MAX(via->mtu, 590) && via != myself) {
408 ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
409 if(packet->data[20] & 0x40) {
410 packet->len = MAX(via->mtu, 590);
411 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
413 fragment_ipv4_packet(via, packet);
419 clamp_mss(source, via, packet);
421 send_packet(subnet->owner, packet);
424 static void route_ipv4(node_t *source, vpn_packet_t *packet) {
425 if(!checklength(source, packet, ether_size + ip_size))
428 if(broadcast && (((packet->data[30] & 0xf0) == 0xe0) || (
429 packet->data[30] == 255 &&
430 packet->data[31] == 255 &&
431 packet->data[32] == 255 &&
432 packet->data[33] == 255)))
433 broadcast_packet(source, packet);
435 route_ipv4_unicast(source, packet);
440 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code) {
442 struct icmp6_hdr icmp6 = {0};
446 struct in6_addr ip6_src; /* source address */
447 struct in6_addr ip6_dst; /* destination address */
455 /* Swap Ethernet source and destination addresses */
457 swap_mac_addresses(packet);
459 /* Copy headers from packet to structs on the stack */
461 memcpy(&ip6, packet->data + ether_size, ip6_size);
463 /* Remember original source and destination */
465 pseudo.ip6_src = ip6.ip6_dst;
466 pseudo.ip6_dst = ip6.ip6_src;
468 pseudo.length = packet->len - ether_size;
470 if(type == ICMP6_PACKET_TOO_BIG)
471 icmp6.icmp6_mtu = htonl(pseudo.length);
473 if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
474 pseudo.length = IP_MSS - ip6_size - icmp6_size;
476 /* Copy first part of original contents to ICMP message */
478 memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
480 /* Fill in IPv6 header */
482 ip6.ip6_flow = htonl(0x60000000UL);
483 ip6.ip6_plen = htons(icmp6_size + pseudo.length);
484 ip6.ip6_nxt = IPPROTO_ICMPV6;
486 ip6.ip6_src = pseudo.ip6_src;
487 ip6.ip6_dst = pseudo.ip6_dst;
489 /* Fill in ICMP header */
491 icmp6.icmp6_type = type;
492 icmp6.icmp6_code = code;
493 icmp6.icmp6_cksum = 0;
495 /* Create pseudo header */
497 pseudo.length = htonl(icmp6_size + pseudo.length);
498 pseudo.next = htonl(IPPROTO_ICMPV6);
500 /* Generate checksum */
502 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
503 checksum = inet_checksum(&icmp6, icmp6_size, checksum);
504 checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
506 icmp6.icmp6_cksum = checksum;
508 /* Copy structs on stack back to packet */
510 memcpy(packet->data + ether_size, &ip6, ip6_size);
511 memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size);
513 packet->len = ether_size + ip6_size + ntohl(pseudo.length);
515 send_packet(source, packet);
518 static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
523 memcpy(&dest, &packet->data[38], sizeof dest);
524 subnet = lookup_subnet_ipv6(&dest);
527 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
528 source->name, source->hostname,
538 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
542 if(subnet->owner == source) {
543 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
547 if(!subnet->owner->status.reachable)
548 return route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
550 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
551 return route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
553 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
555 if(directonly && subnet->owner != via)
556 return route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
558 if(via && packet->len > MAX(via->mtu, 1294) && via != myself) {
559 ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
560 packet->len = MAX(via->mtu, 1294);
561 route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
565 clamp_mss(source, via, packet);
567 send_packet(subnet->owner, packet);
572 static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
574 struct nd_neighbor_solicit ns;
575 struct nd_opt_hdr opt;
581 struct in6_addr ip6_src; /* source address */
582 struct in6_addr ip6_dst; /* destination address */
587 if(!checklength(source, packet, ether_size + ip6_size + ns_size))
590 has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
592 if(source != myself) {
593 ifdebug(TRAFFIC) logger(LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname);
597 /* Copy headers from packet to structs on the stack */
599 memcpy(&ip6, packet->data + ether_size, ip6_size);
600 memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
602 memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
604 /* First, snatch the source address from the neighbor solicitation packet */
607 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
609 /* Check if this is a valid neighbor solicitation request */
611 if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
612 (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
613 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request");
617 /* Create pseudo header */
619 pseudo.ip6_src = ip6.ip6_src;
620 pseudo.ip6_dst = ip6.ip6_dst;
622 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
624 pseudo.length = htonl(ns_size);
625 pseudo.next = htonl(IPPROTO_ICMPV6);
627 /* Generate checksum */
629 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
630 checksum = inet_checksum(&ns, ns_size, checksum);
632 checksum = inet_checksum(&opt, opt_size, checksum);
633 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
637 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request");
641 /* Check if the IPv6 address exists on the VPN */
643 subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
646 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
647 ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
648 ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
649 ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
650 ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
651 ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
652 ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
653 ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
654 ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
659 /* Check if it is for our own subnet */
661 if(subnet->owner == myself)
662 return; /* silently ignore */
664 /* Create neighbor advertation reply */
666 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
667 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
669 ip6.ip6_dst = ip6.ip6_src; /* swap destination and source protocoll address */
670 ip6.ip6_src = ns.nd_ns_target;
673 memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
676 ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
677 ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */
678 opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
680 /* Create pseudo header */
682 pseudo.ip6_src = ip6.ip6_src;
683 pseudo.ip6_dst = ip6.ip6_dst;
685 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
687 pseudo.length = htonl(ns_size);
688 pseudo.next = htonl(IPPROTO_ICMPV6);
690 /* Generate checksum */
692 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
693 checksum = inet_checksum(&ns, ns_size, checksum);
695 checksum = inet_checksum(&opt, opt_size, checksum);
696 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
699 ns.nd_ns_hdr.icmp6_cksum = checksum;
701 /* Copy structs on stack back to packet */
703 memcpy(packet->data + ether_size, &ip6, ip6_size);
704 memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
706 memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
708 send_packet(source, packet);
711 static void route_ipv6(node_t *source, vpn_packet_t *packet) {
712 if(!checklength(source, packet, ether_size + ip6_size))
715 if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
716 route_neighborsol(source, packet);
720 if(broadcast && packet->data[38] == 255)
721 broadcast_packet(source, packet);
723 route_ipv6_unicast(source, packet);
728 static void route_arp(node_t *source, vpn_packet_t *packet) {
729 struct ether_arp arp;
733 if(!checklength(source, packet, ether_size + arp_size))
736 if(source != myself) {
737 ifdebug(TRAFFIC) logger(LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname);
741 /* First, snatch the source address from the ARP packet */
744 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
746 /* Copy headers from packet to structs on the stack */
748 memcpy(&arp, packet->data + ether_size, arp_size);
750 /* Check if this is a valid ARP request */
752 if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
753 arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
754 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type ARP request");
758 /* Check if the IPv4 address exists on the VPN */
760 subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
763 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d",
764 arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
769 /* Check if it is for our own subnet */
771 if(subnet->owner == myself)
772 return; /* silently ignore */
774 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
775 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
777 memcpy(&addr, arp.arp_tpa, sizeof(addr)); /* save protocol addr */
778 memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */
779 memcpy(arp.arp_spa, &addr, sizeof(addr)); /* ... */
781 memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */
782 memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
783 arp.arp_op = htons(ARPOP_REPLY);
785 /* Copy structs on stack back to packet */
787 memcpy(packet->data + ether_size, &arp, arp_size);
789 send_packet(source, packet);
792 static void route_mac(node_t *source, vpn_packet_t *packet) {
796 /* Learn source address */
798 if(source == myself) {
800 memcpy(&src, &packet->data[6], sizeof src);
804 /* Lookup destination address */
806 memcpy(&dest, &packet->data[0], sizeof dest);
807 subnet = lookup_subnet_mac(NULL, &dest);
811 broadcast_packet(source, packet);
815 if(subnet->owner == source) {
816 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
820 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
823 // Handle packets larger than PMTU
825 node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
827 if(directonly && subnet->owner != via)
830 if(via && packet->len > via->mtu && via != myself) {
831 ifdebug(TRAFFIC) logger(LOG_INFO, "Packet for %s (%s) length %d larger than MTU %d", subnet->owner->name, subnet->owner->hostname, packet->len, via->mtu);
832 uint16_t type = packet->data[12] << 8 | packet->data[13];
833 if(type == ETH_P_IP && packet->len > 590) {
834 if(packet->data[20] & 0x40) {
835 packet->len = via->mtu;
836 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
838 fragment_ipv4_packet(via, packet);
841 } else if(type == ETH_P_IPV6 && packet->len > 1294) {
842 packet->len = via->mtu;
843 route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
848 clamp_mss(source, via, packet);
850 send_packet(subnet->owner, packet);
853 static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet) {
854 uint16_t type = packet->data[12] << 8 | packet->data[13];
858 if(!checklength(source, packet, 14 + 32))
861 if(packet->data[22] < 1) {
862 if(packet->data[25] != IPPROTO_ICMP || packet->data[46] != ICMP_TIME_EXCEEDED)
863 route_ipv4_unreachable(source, packet, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL);
867 uint16_t old = packet->data[22] << 8 | packet->data[23];
869 uint16_t new = packet->data[22] << 8 | packet->data[23];
871 uint32_t checksum = packet->data[24] << 8 | packet->data[25];
872 checksum += old + (~new & 0xFFFF);
873 while(checksum >> 16)
874 checksum = (checksum & 0xFFFF) + (checksum >> 16);
875 packet->data[24] = checksum >> 8;
876 packet->data[25] = checksum & 0xff;
881 if(!checklength(source, packet, 14 + 40))
884 if(packet->data[21] < 1) {
885 if(packet->data[20] != IPPROTO_ICMPV6 || packet->data[54] != ICMP6_TIME_EXCEEDED)
886 route_ipv6_unreachable(source, packet, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT);
899 void route(node_t *source, vpn_packet_t *packet) {
900 if(forwarding_mode == FMODE_KERNEL && source != myself) {
901 send_packet(myself, packet);
905 if(!checklength(source, packet, ether_size))
908 if(decrement_ttl && source != myself)
909 if(!do_decrement_ttl(source, packet))
912 switch (routing_mode) {
915 uint16_t type = packet->data[12] << 8 | packet->data[13];
919 route_arp(source, packet);
923 route_ipv4(source, packet);
927 route_ipv6(source, packet);
931 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type);
938 route_mac(source, packet);
942 broadcast_packet(source, packet);