3 Copyright (C) 2000-2005 Ivo Timmermans,
4 2000-2013 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.
23 #include "connection.h"
24 #include "control_common.h"
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;
43 bool overwrite_mac = false;
44 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
47 /* Sizes of various headers */
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);
59 #define MAX(a, b) ((a) > (b) ? (a) : (b))
62 static timeout_t age_subnets_timeout;
66 static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) {
68 uint32_t checksum = prevsum ^ 0xFFFF;
76 checksum += *(uint8_t *)p;
79 checksum = (checksum & 0xFFFF) + (checksum >> 16);
84 static bool ratelimit(int frequency) {
85 static time_t lasttime = 0;
88 if(lasttime == now.tv_sec) {
89 if(count >= frequency)
92 lasttime = now.tv_sec;
100 static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
101 if(packet->len < length) {
102 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got too short packet from %s (%s)", source->name, source->hostname);
108 static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
109 if(!source || !via || !(via->options & OPTION_CLAMP_MSS))
112 uint16_t mtu = source->mtu;
113 if(via != myself && via->mtu < mtu)
116 /* Find TCP header */
117 int start = ether_size;
118 uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
120 if(type == ETH_P_8021Q) {
122 type = DATA(packet)[16] << 8 | DATA(packet)[17];
125 if(type == ETH_P_IP && DATA(packet)[start + 9] == 6)
126 start += (DATA(packet)[start] & 0xf) * 4;
127 else if(type == ETH_P_IPV6 && DATA(packet)[start + 6] == 6)
132 if(packet->len <= start + 20)
135 /* Use data offset field to calculate length of options field */
136 int len = ((DATA(packet)[start + 12] >> 4) - 5) * 4;
138 if(packet->len < start + 20 + len)
141 /* Search for MSS option header */
142 for(int i = 0; i < len;) {
143 if(DATA(packet)[start + 20 + i] == 0)
146 if(DATA(packet)[start + 20 + i] == 1) {
151 if(i > len - 2 || i > len - DATA(packet)[start + 21 + i])
154 if(DATA(packet)[start + 20 + i] != 2) {
155 if(DATA(packet)[start + 21 + i] < 2)
157 i += DATA(packet)[start + 21 + i];
161 if(DATA(packet)[start + 21] != 4)
165 uint16_t oldmss = DATA(packet)[start + 22 + i] << 8 | DATA(packet)[start + 23 + i];
166 uint16_t newmss = mtu - start - 20;
167 uint32_t csum = DATA(packet)[start + 16] << 8 | DATA(packet)[start + 17];
172 logger(DEBUG_TRAFFIC, LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
174 /* Update the MSS value and the checksum */
175 DATA(packet)[start + 22 + i] = newmss >> 8;
176 DATA(packet)[start + 23 + i] = newmss & 0xff;
178 csum += oldmss ^ 0xffff;
180 csum = (csum & 0xffff) + (csum >> 16);
183 DATA(packet)[start + 16] = csum >> 8;
184 DATA(packet)[start + 17] = csum;
189 static void swap_mac_addresses(vpn_packet_t *packet) {
191 memcpy(&tmp, &DATA(packet)[0], sizeof tmp);
192 memcpy(&DATA(packet)[0], &DATA(packet)[6], sizeof tmp);
193 memcpy(&DATA(packet)[6], &tmp, sizeof tmp);
196 static void age_subnets(void *data) {
199 for splay_each(subnet_t, s, myself->subnet_tree) {
200 if(s->expires && s->expires < now.tv_sec) {
201 if(debug_level >= DEBUG_TRAFFIC) {
202 char netstr[MAXNETSTR];
203 if(net2str(netstr, sizeof netstr, s))
204 logger(DEBUG_TRAFFIC, LOG_INFO, "Subnet %s expired", netstr);
207 for list_each(connection_t, c, connection_list)
209 send_del_subnet(c, s);
211 subnet_del(myself, s);
219 timeout_set(&age_subnets_timeout, &(struct timeval){10, rand() % 100000});
222 static void learn_mac(mac_t *address) {
223 subnet_t *subnet = lookup_subnet_mac(myself, address);
225 /* If we don't know this MAC address yet, store it */
228 logger(DEBUG_TRAFFIC, LOG_INFO, "Learned new MAC address %x:%x:%x:%x:%x:%x",
229 address->x[0], address->x[1], address->x[2], address->x[3],
230 address->x[4], address->x[5]);
232 subnet = new_subnet();
233 subnet->type = SUBNET_MAC;
234 subnet->expires = now.tv_sec + macexpire;
235 subnet->net.mac.address = *address;
237 subnet_add(myself, subnet);
238 subnet_update(myself, subnet, true);
240 /* And tell all other tinc daemons it's our MAC */
242 for list_each(connection_t, c, connection_list)
244 send_add_subnet(c, subnet);
246 timeout_add(&age_subnets_timeout, age_subnets, NULL, &(struct timeval){10, rand() % 100000});
249 subnet->expires = now.tv_sec + macexpire;
255 static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
257 struct icmp icmp = {0};
259 struct in_addr ip_src;
260 struct in_addr ip_dst;
266 /* Swap Ethernet source and destination addresses */
268 swap_mac_addresses(packet);
270 /* Copy headers from packet into properly aligned structs on the stack */
272 memcpy(&ip, DATA(packet) + ether_size, ip_size);
274 /* Remember original source and destination */
279 /* Try to reply with an IP address assigned to the local machine */
281 if (type == ICMP_TIME_EXCEEDED && code == ICMP_EXC_TTL) {
282 int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
284 struct sockaddr_in addr;
285 memset(&addr, 0, sizeof(addr));
286 addr.sin_family = AF_INET;
287 addr.sin_addr = ip.ip_src;
288 if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
289 memset(&addr, 0, sizeof(addr));
290 addr.sin_family = AF_INET;
291 socklen_t addrlen = sizeof(addr);
292 if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
293 ip_dst = addr.sin_addr;
300 oldlen = packet->len - ether_size;
302 if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
303 icmp.icmp_nextmtu = htons(packet->len - ether_size);
305 if(oldlen >= IP_MSS - ip_size - icmp_size)
306 oldlen = IP_MSS - ip_size - icmp_size;
308 /* Copy first part of original contents to ICMP message */
310 memmove(DATA(packet) + ether_size + ip_size + icmp_size, DATA(packet) + ether_size, oldlen);
312 /* Fill in IPv4 header */
315 ip.ip_hl = ip_size / 4;
317 ip.ip_len = htons(ip_size + icmp_size + oldlen);
321 ip.ip_p = IPPROTO_ICMP;
326 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
328 /* Fill in ICMP header */
330 icmp.icmp_type = type;
331 icmp.icmp_code = code;
334 icmp.icmp_cksum = inet_checksum(&icmp, icmp_size, ~0);
335 icmp.icmp_cksum = inet_checksum(DATA(packet) + ether_size + ip_size + icmp_size, oldlen, icmp.icmp_cksum);
337 /* Copy structs on stack back to packet */
339 memcpy(DATA(packet) + ether_size, &ip, ip_size);
340 memcpy(DATA(packet) + ether_size + ip_size, &icmp, icmp_size);
342 packet->len = ether_size + ip_size + icmp_size + oldlen;
344 send_packet(source, packet);
349 static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t ether_size) {
351 vpn_packet_t fragment;
352 int len, maxlen, todo;
354 uint16_t ip_off, origf;
356 memcpy(&ip, DATA(packet) + ether_size, ip_size);
357 fragment.priority = packet->priority;
358 fragment.offset = DEFAULT_PACKET_OFFSET;
360 if(ip.ip_hl != ip_size / 4)
363 todo = ntohs(ip.ip_len) - ip_size;
365 if(ether_size + ip_size + todo != packet->len) {
366 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));
370 logger(DEBUG_TRAFFIC, LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
372 offset = DATA(packet) + ether_size + ip_size;
373 maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
374 ip_off = ntohs(ip.ip_off);
375 origf = ip_off & ~IP_OFFMASK;
376 ip_off &= IP_OFFMASK;
379 len = todo > maxlen ? maxlen : todo;
380 memcpy(DATA(&fragment) + ether_size + ip_size, offset, len);
384 ip.ip_len = htons(ip_size + len);
385 ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
387 ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
388 memcpy(DATA(&fragment), DATA(packet), ether_size);
389 memcpy(DATA(&fragment) + ether_size, &ip, ip_size);
390 fragment.len = ether_size + ip_size + len;
392 send_packet(dest, &fragment);
398 static void route_ipv4(node_t *source, vpn_packet_t *packet) {
399 if(!checklength(source, packet, ether_size + ip_size))
406 memcpy(&dest, &DATA(packet)[30], sizeof dest);
407 subnet = lookup_subnet_ipv4(&dest);
410 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d",
411 source->name, source->hostname,
417 route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
421 if (!subnet->owner) {
422 broadcast_packet(source, packet);
426 if(subnet->owner == source) {
427 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
431 if(!subnet->owner->status.reachable)
432 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
434 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
435 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
437 if(priorityinheritance)
438 packet->priority = DATA(packet)[15];
440 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
443 logger(DEBUG_TRAFFIC, LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
447 if(directonly && subnet->owner != via)
448 return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
450 if(via && packet->len > MAX(via->mtu, 590) && via != myself) {
451 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);
452 if(DATA(packet)[20] & 0x40) {
453 packet->len = MAX(via->mtu, 590);
454 route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
456 fragment_ipv4_packet(via, packet, ether_size);
462 clamp_mss(source, via, packet);
464 send_packet(subnet->owner, packet);
469 static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
471 struct icmp6_hdr icmp6 = {0};
475 struct in6_addr ip6_src; /* source address */
476 struct in6_addr ip6_dst; /* destination address */
484 /* Swap Ethernet source and destination addresses */
486 swap_mac_addresses(packet);
488 /* Copy headers from packet to structs on the stack */
490 memcpy(&ip6, DATA(packet) + ether_size, ip6_size);
492 /* Remember original source and destination */
494 pseudo.ip6_src = ip6.ip6_dst;
495 pseudo.ip6_dst = ip6.ip6_src;
497 /* Try to reply with an IP address assigned to the local machine */
499 if (type == ICMP6_TIME_EXCEEDED && code == ICMP6_TIME_EXCEED_TRANSIT) {
500 int sockfd = socket(AF_INET6, SOCK_DGRAM, 0);
502 struct sockaddr_in6 addr;
503 memset(&addr, 0, sizeof(addr));
504 addr.sin6_family = AF_INET6;
505 addr.sin6_addr = ip6.ip6_src;
506 if (!connect(sockfd, (const struct sockaddr*) &addr, sizeof(addr))) {
507 memset(&addr, 0, sizeof(addr));
508 addr.sin6_family = AF_INET6;
509 socklen_t addrlen = sizeof(addr);
510 if (!getsockname(sockfd, (struct sockaddr*) &addr, &addrlen) && addrlen <= sizeof(addr)) {
511 pseudo.ip6_src = addr.sin6_addr;
518 pseudo.length = packet->len - ether_size;
520 if(type == ICMP6_PACKET_TOO_BIG)
521 icmp6.icmp6_mtu = htonl(pseudo.length);
523 if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
524 pseudo.length = IP_MSS - ip6_size - icmp6_size;
526 /* Copy first part of original contents to ICMP message */
528 memmove(DATA(packet) + ether_size + ip6_size + icmp6_size, DATA(packet) + ether_size, pseudo.length);
530 /* Fill in IPv6 header */
532 ip6.ip6_flow = htonl(0x60000000UL);
533 ip6.ip6_plen = htons(icmp6_size + pseudo.length);
534 ip6.ip6_nxt = IPPROTO_ICMPV6;
536 ip6.ip6_src = pseudo.ip6_src;
537 ip6.ip6_dst = pseudo.ip6_dst;
539 /* Fill in ICMP header */
541 icmp6.icmp6_type = type;
542 icmp6.icmp6_code = code;
543 icmp6.icmp6_cksum = 0;
545 /* Create pseudo header */
547 pseudo.length = htonl(icmp6_size + pseudo.length);
548 pseudo.next = htonl(IPPROTO_ICMPV6);
550 /* Generate checksum */
552 checksum = inet_checksum(&pseudo, sizeof pseudo, ~0);
553 checksum = inet_checksum(&icmp6, icmp6_size, checksum);
554 checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + icmp6_size, ntohl(pseudo.length) - icmp6_size, checksum);
556 icmp6.icmp6_cksum = checksum;
558 /* Copy structs on stack back to packet */
560 memcpy(DATA(packet) + ether_size, &ip6, ip6_size);
561 memcpy(DATA(packet) + ether_size + ip6_size, &icmp6, icmp6_size);
563 packet->len = ether_size + ip6_size + ntohl(pseudo.length);
565 send_packet(source, packet);
568 static void route_neighborsol(node_t *source, vpn_packet_t *packet);
570 static void route_ipv6(node_t *source, vpn_packet_t *packet) {
571 if(!checklength(source, packet, ether_size + ip6_size))
574 if(DATA(packet)[20] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + icmp6_size) && DATA(packet)[54] == ND_NEIGHBOR_SOLICIT) {
575 route_neighborsol(source, packet);
583 memcpy(&dest, &DATA(packet)[38], sizeof dest);
584 subnet = lookup_subnet_ipv6(&dest);
587 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
588 source->name, source->hostname,
598 route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
602 if (!subnet->owner) {
603 broadcast_packet(source, packet);
607 if(subnet->owner == source) {
608 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
612 if(!subnet->owner->status.reachable)
613 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
615 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
616 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
618 via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
621 logger(DEBUG_TRAFFIC, LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
625 if(directonly && subnet->owner != via)
626 return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
628 if(via && packet->len > MAX(via->mtu, 1294) && via != myself) {
629 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);
630 packet->len = MAX(via->mtu, 1294);
631 route_ipv6_unreachable(source, packet, ether_size, ICMP6_PACKET_TOO_BIG, 0);
635 clamp_mss(source, via, packet);
637 send_packet(subnet->owner, packet);
642 static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
644 struct nd_neighbor_solicit ns;
645 struct nd_opt_hdr opt;
651 struct in6_addr ip6_src;
652 struct in6_addr ip6_dst;
657 if(!checklength(source, packet, ether_size + ip6_size + ns_size))
660 has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
662 if(source != myself) {
663 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname);
667 /* Copy headers from packet to structs on the stack */
669 memcpy(&ip6, DATA(packet) + ether_size, ip6_size);
670 memcpy(&ns, DATA(packet) + ether_size + ip6_size, ns_size);
672 memcpy(&opt, DATA(packet) + ether_size + ip6_size + ns_size, opt_size);
674 /* First, snatch the source address from the neighbor solicitation packet */
677 memcpy(mymac.x, DATA(packet) + ETH_ALEN, ETH_ALEN);
679 /* Check if this is a valid neighbor solicitation request */
681 if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
682 (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
683 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request");
687 /* Create pseudo header */
689 pseudo.ip6_src = ip6.ip6_src;
690 pseudo.ip6_dst = ip6.ip6_dst;
692 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
694 pseudo.length = htonl(ns_size);
695 pseudo.next = htonl(IPPROTO_ICMPV6);
697 /* Generate checksum */
699 checksum = inet_checksum(&pseudo, sizeof pseudo, ~0);
700 checksum = inet_checksum(&ns, ns_size, checksum);
702 checksum = inet_checksum(&opt, opt_size, checksum);
703 checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
707 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request");
711 /* Check if the IPv6 address exists on the VPN */
713 subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
716 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
717 ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
718 ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
719 ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
720 ntohs(((uint16_t *) &ns.nd_ns_target)[3]),
721 ntohs(((uint16_t *) &ns.nd_ns_target)[4]),
722 ntohs(((uint16_t *) &ns.nd_ns_target)[5]),
723 ntohs(((uint16_t *) &ns.nd_ns_target)[6]),
724 ntohs(((uint16_t *) &ns.nd_ns_target)[7]));
729 /* Check if it is for our own subnet */
731 if(subnet->owner == myself)
732 return; /* silently ignore */
734 /* Create neighbor advertation reply */
736 memcpy(DATA(packet), DATA(packet) + ETH_ALEN, ETH_ALEN); /* copy destination address */
737 DATA(packet)[ETH_ALEN * 2 - 1] ^= 0xFF; /* mangle source address so it looks like it's not from us */
739 ip6.ip6_dst = ip6.ip6_src; /* swap destination and source protocoll address */
740 ip6.ip6_src = ns.nd_ns_target;
743 memcpy(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, DATA(packet) + ETH_ALEN, ETH_ALEN); /* add fake source hard addr */
746 ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
747 ns.nd_ns_reserved = htonl(0x40000000UL); /* Set solicited flag */
748 opt.nd_opt_type = ND_OPT_TARGET_LINKADDR;
750 /* Create pseudo header */
752 pseudo.ip6_src = ip6.ip6_src;
753 pseudo.ip6_dst = ip6.ip6_dst;
755 pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
757 pseudo.length = htonl(ns_size);
758 pseudo.next = htonl(IPPROTO_ICMPV6);
760 /* Generate checksum */
762 checksum = inet_checksum(&pseudo, sizeof pseudo, ~0);
763 checksum = inet_checksum(&ns, ns_size, checksum);
765 checksum = inet_checksum(&opt, opt_size, checksum);
766 checksum = inet_checksum(DATA(packet) + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
769 ns.nd_ns_hdr.icmp6_cksum = checksum;
771 /* Copy structs on stack back to packet */
773 memcpy(DATA(packet) + ether_size, &ip6, ip6_size);
774 memcpy(DATA(packet) + ether_size + ip6_size, &ns, ns_size);
776 memcpy(DATA(packet) + ether_size + ip6_size + ns_size, &opt, opt_size);
778 send_packet(source, packet);
783 static void route_arp(node_t *source, vpn_packet_t *packet) {
784 struct ether_arp arp;
788 if(!checklength(source, packet, ether_size + arp_size))
791 if(source != myself) {
792 logger(DEBUG_TRAFFIC, LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname);
796 /* First, snatch the source address from the ARP packet */
799 memcpy(mymac.x, DATA(packet) + ETH_ALEN, ETH_ALEN);
801 /* Copy headers from packet to structs on the stack */
803 memcpy(&arp, DATA(packet) + ether_size, arp_size);
805 /* Check if this is a valid ARP request */
807 if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
808 arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof addr || ntohs(arp.arp_op) != ARPOP_REQUEST) {
809 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: received unknown type ARP request");
813 /* Check if the IPv4 address exists on the VPN */
815 subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
818 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d",
819 arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
824 /* Check if it is for our own subnet */
826 if(subnet->owner == myself)
827 return; /* silently ignore */
829 memcpy(&addr, arp.arp_tpa, sizeof addr); /* save protocol addr */
830 memcpy(arp.arp_tpa, arp.arp_spa, sizeof addr); /* swap destination and source protocol address */
831 memcpy(arp.arp_spa, &addr, sizeof addr); /* ... */
833 memcpy(arp.arp_tha, arp.arp_sha, ETH_ALEN); /* set target hard/proto addr */
834 memcpy(arp.arp_sha, DATA(packet) + ETH_ALEN, ETH_ALEN); /* set source hard/proto addr */
835 arp.arp_sha[ETH_ALEN - 1] ^= 0xFF; /* for consistency with route_packet() */
836 arp.arp_op = htons(ARPOP_REPLY);
838 /* Copy structs on stack back to packet */
840 memcpy(DATA(packet) + ether_size, &arp, arp_size);
842 send_packet(source, packet);
845 static void route_mac(node_t *source, vpn_packet_t *packet) {
849 /* Learn source address */
851 if(source == myself) {
853 memcpy(&src, &DATA(packet)[6], sizeof src);
857 /* Lookup destination address */
859 memcpy(&dest, &DATA(packet)[0], sizeof dest);
860 subnet = lookup_subnet_mac(NULL, &dest);
862 if(!subnet || !subnet->owner) {
863 broadcast_packet(source, packet);
867 if(subnet->owner == source) {
868 logger(DEBUG_TRAFFIC, LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
872 if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
875 uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
877 if(priorityinheritance && type == ETH_P_IP && packet->len >= ether_size + ip_size)
878 packet->priority = DATA(packet)[15];
880 // Handle packets larger than PMTU
882 node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
884 if(directonly && subnet->owner != via)
887 if(via && packet->len > via->mtu && via != myself) {
888 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);
889 length_t ethlen = 14;
891 if(type == ETH_P_8021Q) {
892 type = DATA(packet)[16] << 8 | DATA(packet)[17];
896 if(type == ETH_P_IP && packet->len > 576 + ethlen) {
897 if(DATA(packet)[6 + ethlen] & 0x40) {
898 packet->len = via->mtu;
899 route_ipv4_unreachable(source, packet, ethlen, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
901 fragment_ipv4_packet(via, packet, ethlen);
904 } else if(type == ETH_P_IPV6 && packet->len > 1280 + ethlen) {
905 packet->len = via->mtu;
906 route_ipv6_unreachable(source, packet, ethlen, ICMP6_PACKET_TOO_BIG, 0);
911 clamp_mss(source, via, packet);
913 send_packet(subnet->owner, packet);
916 static void send_pcap(vpn_packet_t *packet) {
919 for list_each(connection_t, c, connection_list) {
924 int len = packet->len;
925 if(c->outmaclength && c->outmaclength < len)
926 len = c->outmaclength;
928 if(send_request(c, "%d %d %d", CONTROL, REQ_PCAP, len))
929 send_meta(c, (char *)DATA(packet), len);
933 static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet) {
934 uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
935 length_t ethlen = ether_size;
937 if(type == ETH_P_8021Q) {
938 type = DATA(packet)[16] << 8 | DATA(packet)[17];
944 if(!checklength(source, packet, ethlen + ip_size))
947 if(DATA(packet)[ethlen + 8] <= 1) {
948 if(DATA(packet)[ethlen + 11] != IPPROTO_ICMP || DATA(packet)[ethlen + 32] != ICMP_TIME_EXCEEDED)
949 route_ipv4_unreachable(source, packet, ethlen, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL);
953 uint16_t old = DATA(packet)[ethlen + 8] << 8 | DATA(packet)[ethlen + 9];
954 DATA(packet)[ethlen + 8]--;
955 uint16_t new = DATA(packet)[ethlen + 8] << 8 | DATA(packet)[ethlen + 9];
957 uint32_t checksum = DATA(packet)[ethlen + 10] << 8 | DATA(packet)[ethlen + 11];
958 checksum += old + (~new & 0xFFFF);
959 while(checksum >> 16)
960 checksum = (checksum & 0xFFFF) + (checksum >> 16);
961 DATA(packet)[ethlen + 10] = checksum >> 8;
962 DATA(packet)[ethlen + 11] = checksum & 0xff;
967 if(!checklength(source, packet, ethlen + ip6_size))
970 if(DATA(packet)[ethlen + 7] <= 1) {
971 if(DATA(packet)[ethlen + 6] != IPPROTO_ICMPV6 || DATA(packet)[ethlen + 40] != ICMP6_TIME_EXCEEDED)
972 route_ipv6_unreachable(source, packet, ethlen, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT);
976 DATA(packet)[ethlen + 7]--;
985 void route(node_t *source, vpn_packet_t *packet) {
989 if(forwarding_mode == FMODE_KERNEL && source != myself) {
990 send_packet(myself, packet);
994 if(!checklength(source, packet, ether_size))
997 if(decrement_ttl && source != myself)
998 if(!do_decrement_ttl(source, packet))
1001 uint16_t type = DATA(packet)[12] << 8 | DATA(packet)[13];
1003 switch (routing_mode) {
1007 route_arp(source, packet);
1011 route_ipv4(source, packet);
1015 route_ipv6(source, packet);
1019 logger(DEBUG_TRAFFIC, LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type);
1025 route_mac(source, packet);
1029 broadcast_packet(source, packet);