3 Copyright (C) 2000-2005 Ivo Timmermans,
4 2000-2014 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 bmode_t broadcast_mode = BMODE_MST;
38 bool decrement_ttl = false;
39 bool directonly = false;
40 bool priorityinheritance = false;
42 bool overwrite_mac = false;
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 */
113 int start = ether_size;
114 uint16_t type = packet->data[12] << 8 | packet->data[13];
116 if(type == ETH_P_8021Q) {
118 type = packet->data[16] << 8 | packet->data[17];
121 if(type == ETH_P_IP && packet->data[start + 9] == 6)
122 start += (packet->data[start] & 0xf) * 4;
123 else if(type == ETH_P_IPV6 && packet->data[start + 6] == 6)
128 if(packet->len <= start + 20)
131 /* Use data offset field to calculate length of options field */
132 int len = ((packet->data[start + 12] >> 4) - 5) * 4;
134 if(packet->len < start + 20 + len)
137 /* Search for MSS option header */
138 for(int i = 0; i < len;) {
139 if(packet->data[start + 20 + i] == 0)
142 if(packet->data[start + 20 + i] == 1) {
147 if(i > len - 2 || i > len - packet->data[start + 21 + i])
150 if(packet->data[start + 20 + i] != 2) {
151 if(packet->data[start + 21 + i] < 2)
153 i += packet->data[start + 21 + i];
157 if(packet->data[start + 21] != 4)
161 uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
162 uint16_t newmss = mtu - start - 20;
163 uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
168 ifdebug(TRAFFIC) logger(LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
170 /* Update the MSS value and the checksum */
171 packet->data[start + 22 + i] = newmss >> 8;
172 packet->data[start + 23 + i] = newmss & 0xff;
177 packet->data[start + 16] = csum >> 8;
178 packet->data[start + 17] = csum & 0xff;
183 static void swap_mac_addresses(vpn_packet_t *packet) {
185 memcpy(&tmp, &packet->data[0], sizeof tmp);
186 memcpy(&packet->data[0], &packet->data[6], sizeof tmp);
187 memcpy(&packet->data[6], &tmp, sizeof tmp);
190 static void learn_mac(mac_t *address) {
195 subnet = lookup_subnet_mac(myself, address);
197 /* If we don't know this MAC address yet, store it */
200 ifdebug(TRAFFIC) logger(LOG_INFO, "Learned new MAC address %x:%x:%x:%x:%x:%x",
201 address->x[0], address->x[1], address->x[2], address->x[3],
202 address->x[4], address->x[5]);
204 subnet = new_subnet();
205 subnet->type = SUBNET_MAC;
206 subnet->expires = now + macexpire;
207 subnet->net.mac.address = *address;
209 subnet_add(myself, subnet);
210 subnet_update(myself, subnet, true);
212 /* And tell all other tinc daemons it's our MAC */
214 for(node = connection_tree->head; node; node = node->next) {
217 send_add_subnet(c, subnet);
222 subnet->expires = now + macexpire;
225 void age_subnets(void) {
228 avl_node_t *node, *next, *node2;
230 for(node = myself->subnet_tree->head; node; node = next) {
233 if(s->expires && s->expires <= now) {
235 char netstr[MAXNETSTR];
236 if(net2str(netstr, sizeof netstr, s))
237 logger(LOG_INFO, "Subnet %s expired", netstr);
240 for(node2 = connection_tree->head; node2; node2 = node2->next) {
243 send_del_subnet(c, s);
246 subnet_update(myself, s, false);
247 subnet_del(myself, s);
254 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
256 struct icmp icmp = {0};
258 struct in_addr ip_src;
259 struct in_addr ip_dst;
265 /* Swap Ethernet source and destination addresses */
267 swap_mac_addresses(packet);
269 /* Copy headers from packet into properly aligned structs on the stack */
271 memcpy(&ip, packet->data + ether_size, ip_size);
273 /* Remember original source and destination */
278 /* Try to reply with an IP address assigned to the local machine */
280 if (type == ICMP_TIME_EXCEEDED && code == ICMP_EXC_TTL) {
281 int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
283 struct sockaddr_in addr;
284 memset(&addr, 0, sizeof(addr));
285 addr.sin_family = AF_INET;
286 addr.sin_addr = ip.ip_src;
287 if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
288 memset(&addr, 0, sizeof(addr));
289 addr.sin_family = AF_INET;
290 socklen_t addrlen = sizeof(addr);
291 if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
292 ip_dst = addr.sin_addr;
299 oldlen = packet->len - ether_size;
301 if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
302 icmp.icmp_nextmtu = htons(packet->len - ether_size);
304 if(oldlen >= IP_MSS - ip_size - icmp_size)
305 oldlen = IP_MSS - ip_size - icmp_size;
307 /* Copy first part of original contents to ICMP message */
309 memmove(packet->data + ether_size + ip_size + icmp_size, packet->data + ether_size, oldlen);
311 /* Fill in IPv4 header */
314 ip.ip_hl = ip_size / 4;
316 ip.ip_len = htons(ip_size + icmp_size + oldlen);
320 ip.ip_p = IPPROTO_ICMP;
325 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
327 /* Fill in ICMP header */
329 icmp.icmp_type = type;
330 icmp.icmp_code = code;
333 icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
334 icmp.icmp_cksum = inet_checksum(packet->data + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
336 /* Copy structs on stack back to packet */
338 memcpy(packet->data + ether_size, &ip, ip_size);
339 memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
341 packet->len = ether_size + ip_size + icmp_size + oldlen;
343 send_packet(source, packet);
348 static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t ether_size) {
350 vpn_packet_t fragment;
351 int len, maxlen, todo;
353 uint16_t ip_off, origf;
355 memcpy(&ip, packet->data + ether_size, ip_size);
356 fragment.priority = packet->priority;
358 if(ip.ip_hl != ip_size / 4)
361 todo = ntohs(ip.ip_len) - ip_size;
363 if(ether_size + ip_size + todo != packet->len) {
364 ifdebug(TRAFFIC) logger(LOG_WARNING, "Length of packet (%d) doesn't match length in IPv4 header (%d)", packet->len, (int)(ether_size + ip_size + todo));
368 ifdebug(TRAFFIC) logger(LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
370 offset = packet->data + ether_size + ip_size;
371 maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
372 ip_off = ntohs(ip.ip_off);
373 origf = ip_off & ~IP_OFFMASK;
374 ip_off &= IP_OFFMASK;
377 len = todo > maxlen ? maxlen : todo;
378 memcpy(fragment.data + ether_size + ip_size, offset, len);
382 ip.ip_len = htons(ip_size + len);
383 ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
385 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
386 memcpy(fragment.data, packet->data, ether_size);
387 memcpy(fragment.data + ether_size, &ip, ip_size);
388 fragment.len = ether_size + ip_size + len;
390 send_packet(dest, &fragment);
396 static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
401 memcpy(&dest, &packet->data[30], sizeof dest);
402 subnet = lookup_subnet_ipv4(&dest);
405 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d",
406 source->name, source->hostname,
412 route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
416 if(subnet->owner == source) {
417 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
421 if(!subnet->owner->status.reachable)
422 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
424 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
425 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
427 if(priorityinheritance)
428 packet->priority = packet->data[15];
430 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
433 ifdebug(TRAFFIC) logger(LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
437 if(directonly && subnet->owner != via)
438 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
440 if(via && packet->len > MAX(via->mtu, 590) && via != myself) {
441 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);
442 if(packet->data[20] & 0x40) {
443 packet->len = MAX(via->mtu, 590);
444 route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
446 fragment_ipv4_packet(via, packet, ether_size);
452 clamp_mss(source, via, packet);
454 send_packet(subnet->owner, packet);
457 static void route_ipv4(node_t *source, vpn_packet_t *packet) {
458 if(!checklength(source, packet, ether_size + ip_size))
461 if(broadcast_mode && (((packet->data[30] & 0xf0) == 0xe0) || (
462 packet->data[30] == 255 &&
463 packet->data[31] == 255 &&
464 packet->data[32] == 255 &&
465 packet->data[33] == 255)))
466 broadcast_packet(source, packet);
468 route_ipv4_unicast(source, packet);
473 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
475 struct icmp6_hdr icmp6 = {0};
479 struct in6_addr ip6_src; /* source address */
480 struct in6_addr ip6_dst; /* destination address */
488 /* Swap Ethernet source and destination addresses */
490 swap_mac_addresses(packet);
492 /* Copy headers from packet to structs on the stack */
494 memcpy(&ip6, packet->data + ether_size, ip6_size);
496 /* Remember original source and destination */
498 pseudo.ip6_src = ip6.ip6_dst;
499 pseudo.ip6_dst = ip6.ip6_src;
501 /* Try to reply with an IP address assigned to the local machine */
503 if (type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT) {
504 int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
506 struct sockaddr_in6 addr;
507 memset(&addr, 0, sizeof(addr));
508 addr.sin6_family = AF_INET6;
509 addr.sin6_addr = ip6.ip6_src;
510 if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
511 memset(&addr, 0, sizeof(addr));
512 addr.sin6_family = AF_INET6;
513 socklen_t addrlen = sizeof(addr);
514 if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
515 pseudo.ip6_src = addr.sin6_addr;
522 pseudo.length = packet->len - ether_size;
524 if(type == ICMP6_PACKET_TOO_BIG)
525 icmp6.icmp6_mtu = htonl(pseudo.length);
527 if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
528 pseudo.length = IP_MSS - ip6_size - icmp6_size;
530 /* Copy first part of original contents to ICMP message */
532 memmove(packet->data + ether_size + ip6_size + icmp6_size, packet->data + ether_size, pseudo.length);
534 /* Fill in IPv6 header */
536 ip6.ip6_flow = htonl(0x60000000UL);
537 ip6.ip6_plen = htons(icmp6_size + pseudo.length);
538 ip6.ip6_nxt = IPPROTO_ICMPV6;
540 ip6.ip6_src = pseudo.ip6_src;
541 ip6.ip6_dst = pseudo.ip6_dst;
543 /* Fill in ICMP header */
545 icmp6.icmp6_type = type;
546 icmp6.icmp6_code = code;
547 icmp6.icmp6_cksum = 0;
549 /* Create pseudo header */
551 pseudo.length = htonl(icmp6_size + pseudo.length);
552 pseudo.next = htonl(IPPROTO_ICMPV6);
554 /* Generate checksum */
556 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
557 checksum = inet_checksum(&icmp6, icmp6_size, checksum);
558 checksum = inet_checksum(packet->data + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
560 icmp6.icmp6_cksum = checksum;
562 /* Copy structs on stack back to packet */
564 memcpy(packet->data + ether_size, &ip6, ip6_size);
565 memcpy(packet->data + ether_size + ip6_size, &icmp6, icmp6_size);
567 packet->len = ether_size + ip6_size + ntohl(pseudo.length);
569 send_packet(source, packet);
572 static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
577 memcpy(&dest, &packet->data[38], sizeof dest);
578 subnet = lookup_subnet_ipv6(&dest);
581 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
582 source->name, source->hostname,
592 route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
596 if(subnet->owner == source) {
597 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
601 if(!subnet->owner->status.reachable)
602 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
604 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
605 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
607 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
610 ifdebug(TRAFFIC) logger(LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
614 if(directonly && subnet->owner != via)
615 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
617 if(via && packet->len > MAX(via->mtu, 1294) && via != myself) {
618 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);
619 packet->len = MAX(via->mtu, 1294);
620 route_ipv6_unreachable(source, packet, ether_size, ICMP6_PACKET_TOO_BIG, 0);
624 clamp_mss(source, via, packet);
626 send_packet(subnet->owner, packet);
631 static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
633 struct nd_neighbor_solicit ns;
634 struct nd_opt_hdr opt;
640 struct in6_addr ip6_src; /* source address */
641 struct in6_addr ip6_dst; /* destination address */
646 if(!checklength(source, packet, ether_size + ip6_size + ns_size))
649 has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
651 if(source != myself) {
652 ifdebug(TRAFFIC) logger(LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname);
656 /* Copy headers from packet to structs on the stack */
658 memcpy(&ip6, packet->data + ether_size, ip6_size);
659 memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
661 memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
663 /* First, snatch the source address from the neighbor solicitation packet */
666 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
668 /* Check if this is a valid neighbor solicitation request */
670 if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
671 (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
672 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request");
676 /* Create pseudo header */
678 pseudo.ip6_src = ip6.ip6_src;
679 pseudo.ip6_dst = ip6.ip6_dst;
681 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
683 pseudo.length = htonl(ns_size);
684 pseudo.next = htonl(IPPROTO_ICMPV6);
686 /* Generate checksum */
688 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
689 checksum = inet_checksum(&ns, ns_size, checksum);
691 checksum = inet_checksum(&opt, opt_size, checksum);
692 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
696 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request");
700 /* Check if the IPv6 address exists on the VPN */
702 subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
705 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
706 ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
707 ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
708 ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
709 ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
710 ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
711 ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
712 ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
713 ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
718 /* Check if it is for our own subnet */
720 if(subnet->owner == myself)
721 return; /* silently ignore */
723 /* Create neighbor advertation reply */
725 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
726 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
728 ip6.ip6_dst = ip6.ip6_src; /* swap destination and source protocoll address */
729 ip6.ip6_src = ns.nd_ns_target;
732 memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
735 ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
736 ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */
737 opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
739 /* Create pseudo header */
741 pseudo.ip6_src = ip6.ip6_src;
742 pseudo.ip6_dst = ip6.ip6_dst;
744 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
746 pseudo.length = htonl(ns_size);
747 pseudo.next = htonl(IPPROTO_ICMPV6);
749 /* Generate checksum */
751 checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
752 checksum = inet_checksum(&ns, ns_size, checksum);
754 checksum = inet_checksum(&opt, opt_size, checksum);
755 checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
758 ns.nd_ns_hdr.icmp6_cksum = checksum;
760 /* Copy structs on stack back to packet */
762 memcpy(packet->data + ether_size, &ip6, ip6_size);
763 memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
765 memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
767 send_packet(source, packet);
770 static void route_ipv6(node_t *source, vpn_packet_t *packet) {
771 if(!checklength(source, packet, ether_size + ip6_size))
774 if(packet->data[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && packet->data[54] == ND_NEIGHBOR_SOLICIT) {
775 route_neighborsol(source, packet);
779 if(broadcast_mode && packet->data[38] == 255)
780 broadcast_packet(source, packet);
782 route_ipv6_unicast(source, packet);
787 static void route_arp(node_t *source, vpn_packet_t *packet) {
788 struct ether_arp arp;
792 if(!checklength(source, packet, ether_size + arp_size))
795 if(source != myself) {
796 ifdebug(TRAFFIC) logger(LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname);
800 /* First, snatch the source address from the ARP packet */
803 memcpy(mymac.x, packet->data + ETH_ALEN, ETH_ALEN);
805 /* Copy headers from packet to structs on the stack */
807 memcpy(&arp, packet->data + ether_size, arp_size);
809 /* Check if this is a valid ARP request */
811 if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
812 arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
813 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type ARP request");
817 /* Check if the IPv4 address exists on the VPN */
819 subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
822 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d",
823 arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
828 /* Check if it is for our own subnet */
830 if(subnet->owner == myself)
831 return; /* silently ignore */
833 memcpy(packet->data, packet->data + ETH_ALEN, ETH_ALEN); /* copy destination address */
834 packet->data[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
836 memcpy(&addr, arp.arp_tpa, sizeof(addr)); /* save protocol addr */
837 memcpy(arp.arp_tpa, arp.arp_spa, sizeof(addr)); /* swap destination and source protocol address */
838 memcpy(arp.arp_spa, &addr, sizeof(addr)); /* ... */
840 memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */
841 memcpy(arp.arp_sha, packet->data + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
842 arp.arp_op = htons(ARPOP_REPLY);
844 /* Copy structs on stack back to packet */
846 memcpy(packet->data + ether_size, &arp, arp_size);
848 send_packet(source, packet);
851 static void route_mac(node_t *source, vpn_packet_t *packet) {
855 /* Learn source address */
857 if(source == myself) {
859 memcpy(&src, &packet->data[6], sizeof src);
863 /* Lookup destination address */
865 memcpy(&dest, &packet->data[0], sizeof dest);
866 subnet = lookup_subnet_mac(NULL, &dest);
869 broadcast_packet(source, packet);
873 if(subnet->owner == source) {
874 ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
878 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
881 uint16_t type = packet->data[12] << 8 | packet->data[13];
883 if(priorityinheritance && type == ETH_P_IP && packet->len >= ether_size + ip_size)
884 packet->priority = packet->data[15];
886 // Handle packets larger than PMTU
888 node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
890 if(directonly && subnet->owner != via)
893 if(via && packet->len > via->mtu && via != myself) {
894 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);
895 length_t ethlen = 14;
897 if(type == ETH_P_8021Q) {
898 type = packet->data[16] << 8 | packet->data[17];
902 if(type == ETH_P_IP && packet->len > 576 + ethlen) {
903 if(packet->data[6 + ethlen] & 0x40) {
904 packet->len = via->mtu;
905 route_ipv4_unreachable(source, packet, ethlen, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
907 fragment_ipv4_packet(via, packet, ethlen);
910 } else if(type == ETH_P_IPV6 && packet->len > 1280 + ethlen) {
911 packet->len = via->mtu;
912 route_ipv6_unreachable(source, packet, ethlen, ICMP6_PACKET_TOO_BIG, 0);
917 clamp_mss(source, via, packet);
919 send_packet(subnet->owner, packet);
922 static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet) {
923 uint16_t type = packet->data[12] << 8 | packet->data[13];
924 length_t ethlen = ether_size;
926 if(type == ETH_P_8021Q) {
927 type = packet->data[16] << 8 | packet->data[17];
933 if(!checklength(source, packet, ethlen + ip_size))
936 if(packet->data[ethlen + 8] <= 1) {
937 if(packet->data[ethlen + 11] != IPPROTO_ICMP || packet->data[ethlen + 32] != ICMP_TIME_EXCEEDED)
938 route_ipv4_unreachable(source, packet, ethlen, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL);
942 uint16_t old = packet->data[ethlen + 8] << 8 | packet->data[ethlen + 9];
943 packet->data[ethlen + 8]--;
944 uint16_t new = packet->data[ethlen + 8] << 8 | packet->data[ethlen + 9];
946 uint32_t checksum = packet->data[ethlen + 10] << 8 | packet->data[ethlen + 11];
947 checksum += old + (~new & 0xFFFF);
948 while(checksum >> 16)
949 checksum = (checksum & 0xFFFF) + (checksum >> 16);
950 packet->data[ethlen + 10] = checksum >> 8;
951 packet->data[ethlen + 11] = checksum & 0xff;
956 if(!checklength(source, packet, ethlen + ip6_size))
959 if(packet->data[ethlen + 7] <= 1) {
960 if(packet->data[ethlen + 6] != IPPROTO_ICMPV6 || packet->data[ethlen + 40] != ICMP6_TIME_EXCEEDED)
961 route_ipv6_unreachable(source, packet, ethlen, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT);
965 packet->data[ethlen + 7]--;
974 void route(node_t *source, vpn_packet_t *packet) {
975 if(forwarding_mode == FMODE_KERNEL && source != myself) {
976 send_packet(myself, packet);
980 if(!checklength(source, packet, ether_size))
983 if(decrement_ttl && source != myself)
984 if(!do_decrement_ttl(source, packet))
987 switch (routing_mode) {
990 uint16_t type = packet->data[12] << 8 | packet->data[13];
994 route_arp(source, packet);
998 route_ipv4(source, packet);
1002 route_ipv6(source, packet);
1006 ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type);
1013 route_mac(source, packet);
1017 broadcast_packet(source, packet);