3 Copyright (C) 2000-2005 Ivo Timmermans,
4 2000-2009 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
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
26 #include "connection.h"
37 rmode_t routing_mode = RMODE_ROUTER;
38 bool priorityinheritance = false;
40 bool overwrite_mac = false;
41 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
43 /* Sizes of various headers */
45 static const size_t ether_size = sizeof(struct ether_header);
46 static const size_t arp_size = sizeof(struct ether_arp);
47 static const size_t ip_size = sizeof(struct ip);
48 static const size_t icmp_size = sizeof(struct icmp) - sizeof(struct ip);
49 static const size_t ip6_size = sizeof(struct ip6_hdr);
50 static const size_t icmp6_size = sizeof(struct icmp6_hdr);
51 static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
52 static const size_t opt_size = sizeof(struct nd_opt_hdr);
56 static uint16_t inet_checksum(void *data, int len, uint16_t prevsum)
59 uint32_t checksum = prevsum ^ 0xFFFF;
67 checksum += *(uint8_t *)p;
70 checksum = (checksum & 0xFFFF) + (checksum >> 16);
75 static bool ratelimit(int frequency) {
76 static time_t lasttime = 0;
80 if(++count > frequency)
90 static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
91 if(packet->len < length) {
92 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got too short packet from %s (%s)"), source->name, source->hostname);
98 static void swap_mac_addresses(vpn_packet_t *packet) {
100 memcpy(&tmp, &packet->data[0], sizeof tmp);
101 memcpy(&packet->data[0], &packet->data[6], sizeof tmp);
102 memcpy(&packet->data[6], &tmp, sizeof tmp);
105 static void learn_mac(mac_t *address)
113 subnet = lookup_subnet_mac(address);
115 /* If we don't know this MAC address yet, store it */
118 ifdebug(TRAFFIC) logger(LOG_INFO, _("Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx"),
119 address->x[0], address->x[1], address->x[2], address->x[3],
120 address->x[4], address->x[5]);
122 subnet = new_subnet();
123 subnet->type = SUBNET_MAC;
124 subnet->expires = now + macexpire;
125 subnet->net.mac.address = *address;
126 subnet_add(myself, subnet);
128 /* And tell all other tinc daemons it's our MAC */
130 for(node = connection_tree->head; node; node = node->next) {
133 send_add_subnet(c, subnet);
138 subnet->expires = now + macexpire;
141 void age_subnets(void)
145 avl_node_t *node, *next, *node2;
149 for(node = myself->subnet_tree->head; node; node = next) {
152 if(s->expires && s->expires < now) {
154 char netstr[MAXNETSTR];
155 if(net2str(netstr, sizeof netstr, s))
156 logger(LOG_INFO, _("Subnet %s expired"), netstr);
159 for(node2 = connection_tree->head; node2; node2 = node2->next) {
162 send_del_subnet(c, s);
165 subnet_del(myself, s);
172 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code)
175 struct icmp icmp = {0};
177 struct in_addr ip_src;
178 struct in_addr ip_dst;
186 /* Swap Ethernet source and destination addresses */
188 swap_mac_addresses(packet);
190 /* Copy headers from packet into properly aligned structs on the stack */
192 memcpy(&ip, packet->data + ether_size, ip_size);
194 /* Remember original source and destination */
199 oldlen = packet->len - ether_size;
201 if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
202 icmp.icmp_nextmtu = htons(packet->len - ether_size);
204 if(oldlen >= IP_MSS - ip_size - icmp_size)
205 oldlen = IP_MSS - ip_size - icmp_size;
207 /* Copy first part of original contents to ICMP message */
209 memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
211 /* Fill in IPv4 header */
214 ip.ip_hl = ip_size / 4;
216 ip.ip_len = htons(ip_size + icmp_size + oldlen);
220 ip.ip_p = IPPROTO_ICMP;
225 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
227 /* Fill in ICMP header */
229 icmp.icmp_type = type;
230 icmp.icmp_code = code;
233 icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
234 icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
236 /* Copy structs on stack back to packet */
238 memcpy(packet->data + ether_size, &ip, ip_size);
239 memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
241 packet->len = ether_size + ip_size + icmp_size + oldlen;
243 send_packet(source, packet);
248 static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet) {
250 vpn_packet_t fragment;
251 int len, maxlen, todo;
253 uint16_t ip_off, origf;
257 memcpy(&ip, packet->data + ether_size, ip_size);
258 fragment.priority = packet->priority;
260 if(ip.ip_hl != ip_size / 4)
263 todo = ntohs(ip.ip_len) - ip_size;
265 if(ether_size + ip_size + todo != packet->len) {
266 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Length of packet (%d) doesn't match length in IPv4 header (%zd)"), packet->len, ether_size + ip_size + todo);
270 ifdebug(TRAFFIC) logger(LOG_INFO, _("Fragmenting packet of %d bytes to %s (%s)"), packet->len, dest->name, dest->hostname);
272 offset = packet->data + ether_size + ip_size;
273 maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
274 ip_off = ntohs(ip.ip_off);
275 origf = ip_off & ~IP_OFFMASK;
276 ip_off &= IP_OFFMASK;
279 len = todo > maxlen ? maxlen : todo;
280 memcpy(fragment.data + ether_size + ip_size, offset, len);
284 ip.ip_len = htons(ip_size + len);
285 ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
287 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
288 memcpy(fragment.data, packet->data, ether_size);
289 memcpy(fragment.data + ether_size, &ip, ip_size);
290 fragment.len = ether_size + ip_size + len;
292 send_packet(dest, &fragment);
298 static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
306 memcpy(&dest, &packet->data[30], sizeof dest);
307 subnet = lookup_subnet_ipv4(&dest);
310 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d"),
311 source->name, source->hostname,
317 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
321 if(subnet->owner == source) {
322 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
326 if(!subnet->owner->status.reachable)
327 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
329 if(priorityinheritance)
330 packet->priority = packet->data[15];
332 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
334 if(via && packet->len > via->mtu && via != myself) {
335 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);
336 if(packet->data[20] & 0x40) {
337 packet->len = via->mtu;
338 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
340 fragment_ipv4_packet(via, packet);
346 send_packet(subnet->owner, packet);
349 static void route_ipv4(node_t *source, vpn_packet_t *packet)
353 if(!checklength(source, packet, ether_size + ip_size))
356 if(((packet->data[30] & 0xf0) == 0xe0) || (
357 packet->data[30] == 255 &&
358 packet->data[31] == 255 &&
359 packet->data[32] == 255 &&
360 packet->data[33] == 255))
361 broadcast_packet(source, packet);
363 route_ipv4_unicast(source, packet);
368 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t type, uint8_t code)
371 struct icmp6_hdr icmp6 = {0};
375 struct in6_addr ip6_src; /* source address */
376 struct in6_addr ip6_dst; /* destination address */
386 /* Swap Ethernet source and destination addresses */
388 swap_mac_addresses(packet);
390 /* Copy headers from packet to structs on the stack */
392 memcpy(&ip6, packet->data + ether_size, ip6_size);
394 /* Remember original source and destination */
396 pseudo.ip6_src = ip6.ip6_dst;
397 pseudo.ip6_dst = ip6.ip6_src;
399 pseudo.length = packet->len - ether_size;
401 if(type == ICMP6_PACKET_TOO_BIG)
402 icmp6.icmp6_mtu = htonl(pseudo.length);
404 if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
405 pseudo.length = IP_MSS - ip6_size - icmp6_size;
407 /* Copy first part of original contents to ICMP message */
409 memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
411 /* Fill in IPv6 header */
413 ip6.ip6_flow = htonl(0x60000000UL);
414 ip6.ip6_plen = htons(icmp6_size + pseudo.length);
415 ip6.ip6_nxt = IPPROTO_ICMPV6;
417 ip6.ip6_src = pseudo.ip6_src;
418 ip6.ip6_dst = pseudo.ip6_dst;
420 /* Fill in ICMP header */
422 icmp6.icmp6_type = type;
423 icmp6.icmp6_code = code;
424 icmp6.icmp6_cksum = 0;
426 /* Create pseudo header */
428 pseudo.length = htonl(icmp6_size + pseudo.length);
429 pseudo.next = htonl(IPPROTO_ICMPV6);
431 /* Generate checksum */
433 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
434 checksum = inet_checksum(&icmp6, icmp6_size, checksum);
435 checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
437 icmp6.icmp6_cksum = checksum;
439 /* Copy structs on stack back to packet */
441 memcpy(packet->data + ether_size, &ip6, ip6_size);
442 memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size);
444 packet->len = ether_size + ip6_size + ntohl(pseudo.length);
446 send_packet(source, packet);
449 static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet)
457 memcpy(&dest, &packet->data[38], sizeof dest);
458 subnet = lookup_subnet_ipv6(&dest);
461 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
462 source->name, source->hostname,
472 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
476 if(subnet->owner == source) {
477 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
481 if(!subnet->owner->status.reachable)
482 route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
484 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
486 if(via && packet->len > via->mtu && via != myself) {
487 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);
488 packet->len = via->mtu;
489 route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
493 send_packet(subnet->owner, packet);
498 static void route_neighborsol(node_t *source, vpn_packet_t *packet)
501 struct nd_neighbor_solicit ns;
502 struct nd_opt_hdr opt;
508 struct in6_addr ip6_src; /* source address */
509 struct in6_addr ip6_dst; /* destination address */
516 if(!checklength(source, packet, ether_size + ip6_size + ns_size))
519 has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
521 if(source != myself) {
522 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got neighbor solicitation request from %s (%s) while in router mode!"), source->name, source->hostname);
526 /* Copy headers from packet to structs on the stack */
528 memcpy(&ip6, packet->data + ether_size, ip6_size);
529 memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
531 memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
533 /* First, snatch the source address from the neighbor solicitation packet */
536 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
538 /* Check if this is a valid neighbor solicitation request */
540 if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
541 (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
542 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type neighbor solicitation request"));
546 /* Create pseudo header */
548 pseudo.ip6_src = ip6.ip6_src;
549 pseudo.ip6_dst = ip6.ip6_dst;
551 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
553 pseudo.length = htonl(ns_size);
554 pseudo.next = htonl(IPPROTO_ICMPV6);
556 /* Generate checksum */
558 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
559 checksum = inet_checksum(&ns, ns_size, checksum);
561 checksum = inet_checksum(&opt, opt_size, checksum);
562 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
566 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
570 /* Check if the IPv6 address exists on the VPN */
572 subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
575 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
576 ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
577 ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
578 ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
579 ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
580 ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
581 ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
582 ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
583 ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
588 /* Check if it is for our own subnet */
590 if(subnet->owner == myself)
591 return; /* silently ignore */
593 /* Create neighbor advertation reply */
595 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
596 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
598 ip6.ip6_dst = ip6.ip6_src; /* swap destination and source protocoll address */
599 ip6.ip6_src = ns.nd_ns_target;
602 memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
605 ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
606 ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */
607 opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
609 /* Create pseudo header */
611 pseudo.ip6_src = ip6.ip6_src;
612 pseudo.ip6_dst = ip6.ip6_dst;
614 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
616 pseudo.length = htonl(ns_size);
617 pseudo.next = htonl(IPPROTO_ICMPV6);
619 /* Generate checksum */
621 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
622 checksum = inet_checksum(&ns, ns_size, checksum);
624 checksum = inet_checksum(&opt, opt_size, checksum);
625 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
628 ns.nd_ns_hdr.icmp6_cksum = checksum;
630 /* Copy structs on stack back to packet */
632 memcpy(packet->data + ether_size, &ip6, ip6_size);
633 memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
635 memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
637 send_packet(source, packet);
640 static void route_ipv6(node_t *source, vpn_packet_t *packet)
644 if(!checklength(source, packet, ether_size + ip6_size))
647 if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
648 route_neighborsol(source, packet);
652 if(packet->data[38] == 255)
653 broadcast_packet(source, packet);
655 route_ipv6_unicast(source, packet);
660 static void route_arp(node_t *source, vpn_packet_t *packet)
662 struct ether_arp arp;
668 if(!checklength(source, packet, ether_size + arp_size))
671 if(source != myself) {
672 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got ARP request from %s (%s) while in router mode!"), source->name, source->hostname);
676 /* First, snatch the source address from the ARP packet */
679 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
681 /* Copy headers from packet to structs on the stack */
683 memcpy(&arp, packet->data + ether_size, arp_size);
685 /* Check if this is a valid ARP request */
687 if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
688 arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
689 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type ARP request"));
693 /* Check if the IPv4 address exists on the VPN */
695 subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
698 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"),
699 arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
704 /* Check if it is for our own subnet */
706 if(subnet->owner == myself)
707 return; /* silently ignore */
709 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
710 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
712 memcpy(&addr, arp.arp_tpa, sizeof(addr)); /* save protocol addr */
713 memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */
714 memcpy(arp.arp_spa, &addr, sizeof(addr)); /* ... */
716 memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */
717 memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
718 arp.arp_op = htons(ARPOP_REPLY);
720 /* Copy structs on stack back to packet */
722 memcpy(packet->data + ether_size, &arp, arp_size);
724 send_packet(source, packet);
727 static void route_mac(node_t *source, vpn_packet_t *packet)
735 /* Learn source address */
737 if(source == myself) {
739 memcpy(&src, &packet->data[6], sizeof src);
743 /* Lookup destination address */
745 memcpy(&dest, &packet->data[0], sizeof dest);
746 subnet = lookup_subnet_mac(&dest);
749 broadcast_packet(source, packet);
753 if(subnet->owner == source) {
754 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
758 // Handle packets larger than PMTU
760 node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
762 if(via && packet->len > via->mtu && via != myself) {
763 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);
764 uint16_t type = packet->data[12] << 8 | packet->data[13];
765 if(type == ETH_P_IP) {
766 if(packet->data[20] & 0x40) {
767 packet->len = via->mtu;
768 route_ipv4_unreachable(source, packet, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
770 fragment_ipv4_packet(via, packet);
772 } else if(type == ETH_P_IPV6) {
773 packet->len = via->mtu;
774 route_ipv6_unreachable(source, packet, ICMP6_PACKET_TOO_BIG, 0);
776 ifdebug(TRAFFIC) logger(LOG_INFO, _("Large packet of unhandled type %hx dropped"), type);
781 send_packet(subnet->owner, packet);
785 void route(node_t *source, vpn_packet_t *packet)
789 if(!checklength(source, packet, ether_size))
792 switch (routing_mode) {
795 uint16_t type = packet->data[12] << 8 | packet->data[13];
799 route_arp(source, packet);
803 route_ipv4(source, packet);
807 route_ipv6(source, packet);
811 ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown type %hx"), source->name, source->hostname, type);
818 route_mac(source, packet);
822 broadcast_packet(source, packet);