X-Git-Url: https://git.librecmc.org/?p=oweals%2Ftinc.git;a=blobdiff_plain;f=src%2Froute.c;h=a1254d80832491ee947e505c2c2050a9cd33e0fa;hp=6d391cdf4a232fab65f7108ced4c84655b1e9007;hb=a588f6febeca13edd038d78e42efb8aa9f16a444;hpb=5a1406adefd8b51981af0da5ac0ebec830eb43b4

diff --git a/src/route.c b/src/route.c
index 6d391cd..a1254d8 100644
--- a/src/route.c
+++ b/src/route.c
@@ -1,7 +1,7 @@
 /*
     route.c -- routing
-    Copyright (C) 2000-2003 Ivo Timmermans <ivo@o2w.nl>,
-                  2000-2003 Guus Sliepen <guus@sliepen.eu.org>
+    Copyright (C) 2000-2005 Ivo Timmermans,
+                  2000-2014 Guus Sliepen <guus@tinc-vpn.org>
 
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
@@ -13,31 +13,13 @@
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
 
-    You should have received a copy of the GNU General Public License
-    along with this program; if not, write to the Free Software
-    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
-
-    $Id: route.c,v 1.1.2.70 2003/12/12 19:52:25 guus Exp $
+    You should have received a copy of the GNU General Public License along
+    with this program; if not, write to the Free Software Foundation, Inc.,
+    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
 #include "system.h"
 
-#ifdef HAVE_NET_ETHERNET_H
-#include <net/ethernet.h>
-#endif
-#ifdef HAVE_NET_IF_ARP_H
-#include <net/if_arp.h>
-#endif
-#ifdef HAVE_NETINET_IP_ICMP_H
-#include <netinet/ip_icmp.h>
-#endif
-#ifdef HAVE_NETINET_ICMP6_H
-#include <netinet/icmp6.h>
-#endif
-#ifdef HAVE_NETINET_IF_ETHER_H
-#include <netinet/if_ether.h>
-#endif
-
 #include "avl_tree.h"
 #include "connection.h"
 #include "ethernet.h"
@@ -51,9 +33,12 @@
 #include "utils.h"
 
 rmode_t routing_mode = RMODE_ROUTER;
+fmode_t forwarding_mode = FMODE_INTERNAL;
+bmode_t broadcast_mode = BMODE_MST;
+bool decrement_ttl = false;
+bool directonly = false;
 bool priorityinheritance = false;
 int macexpire = 600;
-int multicastexpire = 375;
 bool overwrite_mac = false;
 mac_t mymac = {{0xFE, 0xFD, 0, 0, 0, 0}};
 
@@ -68,10 +53,13 @@ static const size_t icmp6_size = sizeof(struct icmp6_hdr);
 static const size_t ns_size = sizeof(struct nd_neighbor_solicit);
 static const size_t opt_size = sizeof(struct nd_opt_hdr);
 
+#ifndef MAX
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
 /* RFC 1071 */
 
-static uint16_t inet_checksum(void *data, int len, uint16_t prevsum)
-{
+static uint16_t inet_checksum(void *data, int len, uint16_t prevsum) {
 	uint16_t *p = data;
 	uint32_t checksum = prevsum ^ 0xFFFF;
 
@@ -94,38 +82,122 @@ static bool ratelimit(int frequency) {
 	static int count = 0;
 	
 	if(lasttime == now) {
-		if(++count > frequency)
+		if(count >= frequency)
 			return true;
 	} else {
 		lasttime = now;
 		count = 0;
 	}
 
+	count++;
 	return false;
 }
 
 static bool checklength(node_t *source, vpn_packet_t *packet, length_t length) {
 	if(packet->len < length) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got too short packet from %s (%s)"), source->name, source->hostname);
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Got too short packet from %s (%s)", source->name, source->hostname);
 		return false;
 	} else
 		return true;
 }
+
+static void clamp_mss(const node_t *source, const node_t *via, vpn_packet_t *packet) {
+	if(!source || !via || !(via->options & OPTION_CLAMP_MSS))
+		return;
+
+	uint16_t mtu = source->mtu;
+	if(via != myself && via->mtu < mtu)
+		mtu = via->mtu;
+
+	/* Find TCP header */
+	int start = ether_size;
+	uint16_t type = packet->data[12] << 8 | packet->data[13];
+
+	if(type == ETH_P_8021Q) {
+		start += 4;
+		type = packet->data[16] << 8 | packet->data[17];
+	}
+
+	if(type == ETH_P_IP && packet->data[start + 9] == 6)
+		start += (packet->data[start] & 0xf) * 4;
+	else if(type == ETH_P_IPV6 && packet->data[start + 6] == 6)
+		start += 40;
+	else
+		return;
+
+	if(packet->len <= start + 20)
+		return;
+
+	/* Use data offset field to calculate length of options field */
+	int len = ((packet->data[start + 12] >> 4) - 5) * 4;
+
+	if(packet->len < start + 20 + len)
+		return;
+
+	/* Search for MSS option header */
+	for(int i = 0; i < len;) {
+		if(packet->data[start + 20 + i] == 0)
+			break;
+
+		if(packet->data[start + 20 + i] == 1) {
+			i++;
+			continue;
+		}
+
+		if(i > len - 2 || i > len - packet->data[start + 21 + i])
+			break;
+
+		if(packet->data[start + 20 + i] != 2) {
+			if(packet->data[start + 21 + i] < 2)
+				break;
+			i += packet->data[start + 21 + i];
+			continue;
+		}
+
+		if(packet->data[start + 21] != 4)
+			break;
+
+		/* Found it */
+		uint16_t oldmss = packet->data[start + 22 + i] << 8 | packet->data[start + 23 + i];
+		uint16_t newmss = mtu - start - 20;
+		uint16_t csum = packet->data[start + 16] << 8 | packet->data[start + 17];
+
+		if(oldmss <= newmss)
+			break;
+		
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Clamping MSS of packet from %s to %s to %d", source->name, via->name, newmss);
+
+		/* Update the MSS value and the checksum */
+		packet->data[start + 22 + i] = newmss >> 8;
+		packet->data[start + 23 + i] = newmss & 0xff;
+		csum ^= 0xffff;
+		csum -= oldmss;
+		csum += newmss;
+		csum ^= 0xffff;
+		packet->data[start + 16] = csum >> 8;
+		packet->data[start + 17] = csum & 0xff;
+		break;
+	}
+}
+
+static void swap_mac_addresses(vpn_packet_t *packet) {
+	mac_t tmp;
+	memcpy(&tmp, &packet->data[0], sizeof tmp);
+	memcpy(&packet->data[0], &packet->data[6], sizeof tmp);
+	memcpy(&packet->data[6], &tmp, sizeof tmp);
+}
 	
-static void learn_mac(mac_t *address)
-{
+static void learn_mac(mac_t *address) {
 	subnet_t *subnet;
 	avl_node_t *node;
 	connection_t *c;
 
-	cp();
-
-	subnet = lookup_subnet_mac(address);
+	subnet = lookup_subnet_mac(myself, address);
 
 	/* If we don't know this MAC address yet, store it */
 
 	if(!subnet) {
-		ifdebug(TRAFFIC) logger(LOG_INFO, _("Learned new MAC address %hx:%hx:%hx:%hx:%hx:%hx"),
+		ifdebug(TRAFFIC) logger(LOG_INFO, "Learned new MAC address %x:%x:%x:%x:%x:%x",
 				   address->x[0], address->x[1], address->x[2], address->x[3],
 				   address->x[4], address->x[5]);
 
@@ -133,7 +205,9 @@ static void learn_mac(mac_t *address)
 		subnet->type = SUBNET_MAC;
 		subnet->expires = now + macexpire;
 		subnet->net.mac.address = *address;
+		subnet->weight = 10;
 		subnet_add(myself, subnet);
+		subnet_update(myself, subnet, true);
 
 		/* And tell all other tinc daemons it's our MAC */
 
@@ -148,22 +222,19 @@ static void learn_mac(mac_t *address)
 		subnet->expires = now + macexpire;
 }
 
-void age_subnets(void)
-{
+void age_subnets(void) {
 	subnet_t *s;
 	connection_t *c;
 	avl_node_t *node, *next, *node2;
 
-	cp();
-
 	for(node = myself->subnet_tree->head; node; node = next) {
 		next = node->next;
 		s = node->data;
-		if(s->expires && s->expires < now) {
+		if(s->expires && s->expires <= now) {
 			ifdebug(TRAFFIC) {
 				char netstr[MAXNETSTR];
 				if(net2str(netstr, sizeof netstr, s))
-					logger(LOG_INFO, _("Subnet %s expired"), netstr);
+					logger(LOG_INFO, "Subnet %s expired", netstr);
 			}
 
 			for(node2 = connection_tree->head; node2; node2 = node2->next) {
@@ -172,43 +243,15 @@ void age_subnets(void)
 					send_del_subnet(c, s);
 			}
 
+			subnet_update(myself, s, false);
 			subnet_del(myself, s);
 		}
 	}
 }
 
-static void route_mac(node_t *source, vpn_packet_t *packet)
-{
-	subnet_t *subnet;
-
-	cp();
-
-	/* Learn source address */
-
-	if(source == myself)
-		learn_mac((mac_t *)(&packet->data[6]));
-
-	/* Lookup destination address */
-
-	subnet = lookup_subnet_mac((mac_t *)(&packet->data[0]));
-
-	if(!subnet) {
-		broadcast_packet(source, packet);
-		return;
-	}
-
-	if(subnet->owner == source) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
-		return;
-	}
-
-	send_packet(subnet->owner, packet);
-}
-
 /* RFC 792 */
 
-static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t code)
-{
+static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
 	struct ip ip = {0};
 	struct icmp icmp = {0};
 	
@@ -219,7 +262,9 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	if(ratelimit(3))
 		return;
 	
-	cp();
+	/* Swap Ethernet source and destination addresses */
+
+	swap_mac_addresses(packet);
 
 	/* Copy headers from packet into properly aligned structs on the stack */
 
@@ -232,6 +277,9 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 
 	oldlen = packet->len - ether_size;
 
+	if(type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED)
+		icmp.icmp_nextmtu = htons(packet->len - ether_size);
+
 	if(oldlen >= IP_MSS - ip_size - icmp_size)
 		oldlen = IP_MSS - ip_size - icmp_size;
 	
@@ -257,7 +305,7 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	
 	/* Fill in ICMP header */
 	
-	icmp.icmp_type = ICMP_DEST_UNREACH;
+	icmp.icmp_type = type;
 	icmp.icmp_code = code;
 	icmp.icmp_cksum = 0;
 	
@@ -270,65 +318,138 @@ static void route_ipv4_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	memcpy(packet->data + ether_size + ip_size, &icmp, icmp_size);
 	
 	packet->len = ether_size + ip_size + icmp_size + oldlen;
-	
+
 	send_packet(source, packet);
 }
 
-static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet)
-{
-	subnet_t *subnet;
+/* RFC 791 */
+
+static void fragment_ipv4_packet(node_t *dest, vpn_packet_t *packet, length_t ether_size) {
+	struct ip ip;
+	vpn_packet_t fragment;
+	int len, maxlen, todo;
+	uint8_t *offset;
+	uint16_t ip_off, origf;
+	
+	memcpy(&ip, packet->data + ether_size, ip_size);
+	fragment.priority = packet->priority;
+
+	if(ip.ip_hl != ip_size / 4)
+		return;
+	
+	todo = ntohs(ip.ip_len) - ip_size;
+
+	if(ether_size + ip_size + todo != packet->len) {
+		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));
+		return;
+	}
+
+	ifdebug(TRAFFIC) logger(LOG_INFO, "Fragmenting packet of %d bytes to %s (%s)", packet->len, dest->name, dest->hostname);
+
+	offset = packet->data + ether_size + ip_size;
+	maxlen = (dest->mtu - ether_size - ip_size) & ~0x7;
+	ip_off = ntohs(ip.ip_off);
+	origf = ip_off & ~IP_OFFMASK;
+	ip_off &= IP_OFFMASK;
+	
+	while(todo) {
+		len = todo > maxlen ? maxlen : todo;
+		memcpy(fragment.data + ether_size + ip_size, offset, len);
+		todo -= len;
+		offset += len;
+
+		ip.ip_len = htons(ip_size + len);
+		ip.ip_off = htons(ip_off | origf | (todo ? IP_MF : 0));
+		ip.ip_sum = 0;
+		ip.ip_sum = inet_checksum(&ip, ip_size, ~0);
+		memcpy(fragment.data, packet->data, ether_size);
+		memcpy(fragment.data + ether_size, &ip, ip_size);
+		fragment.len = ether_size + ip_size + len;
+
+		send_packet(dest, &fragment);
+
+		ip_off += len / 8;
+	}	
+}
 
-	cp();
+static void route_ipv4_unicast(node_t *source, vpn_packet_t *packet) {
+	subnet_t *subnet;
+	node_t *via;
+	ipv4_t dest;
 
-	subnet = lookup_subnet_ipv4((ipv4_t *) &packet->data[30]);
+	memcpy(&dest, &packet->data[30], sizeof dest);
+	subnet = lookup_subnet_ipv4(&dest);
 
 	if(!subnet) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d"),
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv4 destination address %d.%d.%d.%d",
 				source->name, source->hostname,
-				packet->data[30],
-				packet->data[31],
-				packet->data[32],
-				packet->data[33]);
+				dest.x[0],
+				dest.x[1],
+				dest.x[2],
+				dest.x[3]);
 
-		route_ipv4_unreachable(source, packet, ICMP_NET_UNKNOWN);
+		route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNKNOWN);
 		return;
 	}
 	
 	if(subnet->owner == source) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
 		return;
 	}
 
 	if(!subnet->owner->status.reachable)
-		route_ipv4_unreachable(source, packet, ICMP_NET_UNREACH);
+		return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_UNREACH);
+
+	if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
+		return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
 
 	if(priorityinheritance)
 		packet->priority = packet->data[15];
 
-	send_packet(subnet->owner, packet);
-}
+	via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
 
-static void route_ipv4(node_t *source, vpn_packet_t *packet)
-{
-	cp();
-
-	if(!checklength(source, packet, ether_size + ip_size))
+	if(via == source) {
+		ifdebug(TRAFFIC) logger(LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
 		return;
+	}
+	
+	if(directonly && subnet->owner != via)
+		return route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_NET_ANO);
+
+	if(via && packet->len > MAX(via->mtu, 590) && via != myself) {
+		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);
+		if(packet->data[20] & 0x40) {
+			packet->len = MAX(via->mtu, 590);
+			route_ipv4_unreachable(source, packet, ether_size, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
+		} else {
+			fragment_ipv4_packet(via, packet, ether_size);
+		}
 
-#if 0
-	if(packet->data[30] & 0xf0 == 0xe0) {
-		route_ipv4_multicast(source, packet);
 		return;
 	}
-#endif
 
-	route_ipv4_unicast(source, packet);
+	clamp_mss(source, via, packet);
+ 
+	send_packet(subnet->owner, packet);
+}
+
+static void route_ipv4(node_t *source, vpn_packet_t *packet) {
+	if(!checklength(source, packet, ether_size + ip_size))
+		return;
+
+	if(broadcast_mode && (((packet->data[30] & 0xf0) == 0xe0) || (
+			packet->data[30] == 255 &&
+			packet->data[31] == 255 &&
+			packet->data[32] == 255 &&
+			packet->data[33] == 255)))
+		broadcast_packet(source, packet);
+	else
+		route_ipv4_unicast(source, packet);
 }
 
 /* RFC 2463 */
 
-static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t code)
-{
+static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, length_t ether_size, uint8_t type, uint8_t code) {
 	struct ip6_hdr ip6;
 	struct icmp6_hdr icmp6 = {0};
 	uint16_t checksum;	
@@ -343,7 +464,9 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	if(ratelimit(3))
 		return;
 	
-	cp();
+	/* Swap Ethernet source and destination addresses */
+
+	swap_mac_addresses(packet);
 
 	/* Copy headers from packet to structs on the stack */
 
@@ -355,6 +478,9 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	pseudo.ip6_dst = ip6.ip6_src;
 
 	pseudo.length = packet->len - ether_size;
+
+	if(type == ICMP6_PACKET_TOO_BIG)
+		icmp6.icmp6_mtu = htonl(pseudo.length);
 	
 	if(pseudo.length >= IP_MSS - ip6_size - icmp6_size)
 		pseudo.length = IP_MSS - ip6_size - icmp6_size;
@@ -374,7 +500,7 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 
 	/* Fill in ICMP header */
 	
-	icmp6.icmp6_type = ICMP6_DST_UNREACH;
+	icmp6.icmp6_type = type;
 	icmp6.icmp6_code = code;
 	icmp6.icmp6_cksum = 0;
 
@@ -401,77 +527,72 @@ static void route_ipv6_unreachable(node_t *source, vpn_packet_t *packet, uint8_t
 	send_packet(source, packet);
 }
 
-static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet)
-{
+static void route_ipv6_unicast(node_t *source, vpn_packet_t *packet) {
 	subnet_t *subnet;
+	node_t *via;
+	ipv6_t dest;
 
-	cp();
-
-	subnet = lookup_subnet_ipv6((ipv6_t *) &packet->data[38]);
+	memcpy(&dest, &packet->data[38], sizeof dest);
+	subnet = lookup_subnet_ipv6(&dest);
 
 	if(!subnet) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown IPv6 destination address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
 				source->name, source->hostname,
-				ntohs(*(uint16_t *) &packet->data[38]),
-				ntohs(*(uint16_t *) &packet->data[40]),
-				ntohs(*(uint16_t *) &packet->data[42]),
-				ntohs(*(uint16_t *) &packet->data[44]),
-				ntohs(*(uint16_t *) &packet->data[46]),
-				ntohs(*(uint16_t *) &packet->data[48]),
-				ntohs(*(uint16_t *) &packet->data[50]),
-				ntohs(*(uint16_t *) &packet->data[52]));
-
-		route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH_ADDR);
+				ntohs(dest.x[0]),
+				ntohs(dest.x[1]),
+				ntohs(dest.x[2]),
+				ntohs(dest.x[3]),
+				ntohs(dest.x[4]),
+				ntohs(dest.x[5]),
+				ntohs(dest.x[6]),
+				ntohs(dest.x[7]));
+
+		route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADDR);
 		return;
 	}
 
 	if(subnet->owner == source) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Packet looping back to %s (%s)!"), source->name, source->hostname);
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
 		return;
 	}
 
 	if(!subnet->owner->status.reachable)
-		route_ipv6_unreachable(source, packet, ICMP6_DST_UNREACH_NOROUTE);
-	
-	send_packet(subnet->owner, packet);
-}
-
-#ifdef ENABLE_MULTICAST
-static void route_ipv6_multicast(node_t *source, vpn_packet_t *packet)
-{
-	avl_node_t *node;
-	subnet_t *subnet, search = {0};
+		return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_NOROUTE);
 
-	cp();
+	if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
+		return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
 
-	search.type = SUBNET_IPV6;
-	search.net.ipv6.address = *(ipv6_t *)(packet->data + ether_size + ip6_size + icmp6_size);
-	search.net.ipv6.prefixlength = 128;
-	search.owner = NULL;
-
-	ifdebug(TRAFFIC) logger(LOG_INFO, _("Multicasting packet of %d bytes from %s (%s)"), packet->len, source->name, source->hostname);
+	via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
+	
+	if(via == source) {
+		ifdebug(TRAFFIC) logger(LOG_ERR, "Routing loop for packet from %s (%s)!", source->name, source->hostname);
+		return;
+	}
+	
+	if(directonly && subnet->owner != via)
+		return route_ipv6_unreachable(source, packet, ether_size, ICMP6_DST_UNREACH, ICMP6_DST_UNREACH_ADMIN);
 
-	for(node = avl_search_closest_smaller_node(myself->subnet_tree, &search); node; node = node->next) {
-		subnet = node->data;
-		
-		if(subnet->type != SUBNET_IPV6 || memcmp(&subnet->net.ipv6.address, packet->data + ether_size + ip6_size + icmp6_size, sizeof(ipv6_t)))
-			break;
-		
-		if(subnet->owner != source)
-			send_packet(subnet->owner, packet);
+	if(via && packet->len > MAX(via->mtu, 1294) && via != myself) {
+		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);
+		packet->len = MAX(via->mtu, 1294);
+		route_ipv6_unreachable(source, packet, ether_size, ICMP6_PACKET_TOO_BIG, 0);
+		return;
 	}
+
+	clamp_mss(source, via, packet);
+ 
+	send_packet(subnet->owner, packet);
 }
-#endif
 
 /* RFC 2461 */
 
-static void route_neighborsol(node_t *source, vpn_packet_t *packet)
-{
+static void route_neighborsol(node_t *source, vpn_packet_t *packet) {
 	struct ip6_hdr ip6;
 	struct nd_neighbor_solicit ns;
 	struct nd_opt_hdr opt;
 	subnet_t *subnet;
 	uint16_t checksum;
+	bool has_opt;
 
 	struct {
 		struct in6_addr ip6_src;	/* source address */
@@ -480,13 +601,13 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 		uint32_t next;
 	} pseudo;
 
-	cp();
-
-	if(!checklength(source, packet, ether_size + ip6_size + ns_size + opt_size + ETH_ALEN))
+	if(!checklength(source, packet, ether_size + ip6_size + ns_size))
 		return;
 	
+	has_opt = packet->len >= ether_size + ip6_size + ns_size + opt_size + ETH_ALEN;
+	
 	if(source != myself) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got neighbor solicitation request from %s (%s) while in router mode!"), source->name, source->hostname);
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Got neighbor solicitation request from %s (%s) while in router mode!", source->name, source->hostname);
 		return;
 	}
 
@@ -494,7 +615,8 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 
 	memcpy(&ip6, packet->data + ether_size, ip6_size);
 	memcpy(&ns, packet->data + ether_size + ip6_size, ns_size);
-	memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
+	if(has_opt)
+		memcpy(&opt, packet->data + ether_size + ip6_size + ns_size, opt_size);
 
 	/* First, snatch the source address from the neighbor solicitation packet */
 
@@ -504,8 +626,8 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 	/* Check if this is a valid neighbor solicitation request */
 
 	if(ns.nd_ns_hdr.icmp6_type != ND_NEIGHBOR_SOLICIT ||
-	   opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type neighbor solicitation request"));
+	   (has_opt && opt.nd_opt_type != ND_OPT_SOURCE_LINKADDR)) {
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type neighbor solicitation request");
 		return;
 	}
 
@@ -513,18 +635,23 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 
 	pseudo.ip6_src = ip6.ip6_src;
 	pseudo.ip6_dst = ip6.ip6_dst;
-	pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
+	if(has_opt)
+		pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
+	else
+		pseudo.length = htonl(ns_size);
 	pseudo.next = htonl(IPPROTO_ICMPV6);
 
 	/* Generate checksum */
 
 	checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 	checksum = inet_checksum(&ns, ns_size, checksum);
-	checksum = inet_checksum(&opt, opt_size, checksum);
-	checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
+	if(has_opt) {
+		checksum = inet_checksum(&opt, opt_size, checksum);
+		checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
+	}
 
 	if(checksum) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: checksum error for neighbor solicitation request");
 		return;
 	}
 
@@ -533,7 +660,7 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 	subnet = lookup_subnet_ipv6((ipv6_t *) &ns.nd_ns_target);
 
 	if(!subnet) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: neighbor solicitation request for unknown address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx",
 				   ntohs(((uint16_t *) &ns.nd_ns_target)[0]),
 				   ntohs(((uint16_t *) &ns.nd_ns_target)[1]),
 				   ntohs(((uint16_t *) &ns.nd_ns_target)[2]),
@@ -559,7 +686,8 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 	ip6.ip6_dst = ip6.ip6_src;			/* swap destination and source protocoll address */
 	ip6.ip6_src = ns.nd_ns_target;
 
-	memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN);	/* add fake source hard addr */
+	if(has_opt)
+		memcpy(packet->data + ether_size + ip6_size + ns_size + opt_size, packet->data + ETH_ALEN, ETH_ALEN);	/* add fake source hard addr */
 
 	ns.nd_ns_cksum = 0;
 	ns.nd_ns_type = ND_NEIGHBOR_ADVERT;
@@ -570,15 +698,20 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 
 	pseudo.ip6_src = ip6.ip6_src;
 	pseudo.ip6_dst = ip6.ip6_dst;
-	pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
+	if(has_opt)
+		pseudo.length = htonl(ns_size + opt_size + ETH_ALEN);
+	else
+		pseudo.length = htonl(ns_size);
 	pseudo.next = htonl(IPPROTO_ICMPV6);
 
 	/* Generate checksum */
 
 	checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
 	checksum = inet_checksum(&ns, ns_size, checksum);
-	checksum = inet_checksum(&opt, opt_size, checksum);
-	checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
+	if(has_opt) {
+		checksum = inet_checksum(&opt, opt_size, checksum);
+		checksum = inet_checksum(packet->data + ether_size + ip6_size + ns_size + opt_size, ETH_ALEN, checksum);
+	}
 
 	ns.nd_ns_hdr.icmp6_cksum = checksum;
 
@@ -586,109 +719,13 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
 
 	memcpy(packet->data + ether_size, &ip6, ip6_size);
 	memcpy(packet->data + ether_size + ip6_size, &ns, ns_size);
-	memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
+	if(has_opt)
+		memcpy(packet->data + ether_size + ip6_size + ns_size, &opt, opt_size);
 
 	send_packet(source, packet);
 }
 
-/* RFC 2710 */
-
-#ifdef ENABLE_MULTICAST
-static void route_membershipreport(node_t *source, vpn_packet_t *packet)
-{
-	struct ip6_hdr ip6;
-	struct icmp6_hdr icmp6;
-	subnet_t *subnet, search = {0};
-	uint16_t checksum;
-
-	struct {
-		struct in6_addr ip6_src;	/* source address */
-		struct in6_addr ip6_dst;	/* destination address */
-		uint32_t length;
-		uint32_t next;
-	} pseudo;
-
-	cp();
-
-	if(!checklength(source, packet, ether_size + ip6_size + icmp6_size + sizeof(ipv6_t)))
-		return;
-	
-	if(source != myself) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got membership report from %s (%s) while in router mode!"), source->name, source->hostname);
-		return;
-	}
-
-	/* Copy headers from packet to structs on the stack */
-
-	memcpy(&ip6, packet->data + ether_size, ip6_size);
-	memcpy(&icmp6, packet->data + ether_size + ip6_size + 8, icmp6_size);
-
-	/* Create pseudo header */
-
-	pseudo.ip6_src = ip6.ip6_src;
-	pseudo.ip6_dst = ip6.ip6_dst;
-	pseudo.length = htonl(icmp6_size + sizeof(ipv6_t));
-	pseudo.next = htonl(IPPROTO_ICMPV6);
-
-	/* Generate checksum */
-
-	checksum = inet_checksum(&pseudo, sizeof(pseudo), ~0);
-	checksum = inet_checksum(&icmp6, icmp6_size, checksum);
-	checksum = inet_checksum(packet->data + ether_size + ip6_size + 8 + icmp6_size, sizeof(ipv6_t), checksum);
-
-	if(checksum) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for membership report"));
-		return;
-	}
-
-	/* Check if the IPv6 address exists on the VPN */
-
-	search.type = SUBNET_IPV6;
-	search.net.ipv6.address = *(ipv6_t *)(packet->data + ether_size + ip6_size + 8 + icmp6_size);
-	search.net.ipv6.prefixlength = 128;
-	search.owner = myself;
-
-	subnet = avl_search(myself->subnet_tree, &search);
-
-	if(!subnet) {
-		avl_node_t *node;
-		connection_t *c;
-
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Learned new IPv6 multicast address %hx:%hx:%hx:%hx:%hx:%hx:%hx:%hx"),
-				ntohs(*(uint16_t *) &packet->data[70]),
-				ntohs(*(uint16_t *) &packet->data[72]),
-				ntohs(*(uint16_t *) &packet->data[74]),
-				ntohs(*(uint16_t *) &packet->data[76]),
-				ntohs(*(uint16_t *) &packet->data[78]),
-				ntohs(*(uint16_t *) &packet->data[80]),
-				ntohs(*(uint16_t *) &packet->data[82]),
-				ntohs(*(uint16_t *) &packet->data[84]));
-
-		subnet = new_subnet();
-		subnet->type = SUBNET_IPV6;
-		subnet->net.ipv6.address = *(ipv6_t *)(packet->data + ether_size + ip6_size + 8 + icmp6_size);
-		subnet->net.ipv6.prefixlength = 128;
-		subnet->expires = now + multicastexpire;
-		subnet_add(myself, subnet);
-
-		/* And tell all other tinc daemons it's ours */
-
-		for(node = connection_tree->head; node; node = node->next) {
-			c = node->data;
-			if(c->status.active)
-				send_add_subnet(c, subnet);
-		}
-	}
-
-	if(subnet->expires)
-		subnet->expires = now + multicastexpire;
-}
-#endif
-
-static void route_ipv6(node_t *source, vpn_packet_t *packet)
-{
-	cp();
-
+static void route_ipv6(node_t *source, vpn_packet_t *packet) {
 	if(!checklength(source, packet, ether_size + ip6_size))
 		return;
 
@@ -697,38 +734,24 @@ static void route_ipv6(node_t *source, vpn_packet_t *packet)
 		return;
 	}
 
-#ifdef ENABLE_MULTICAST 
-	if(packet->data[20] == IPPROTO_HOPOPTS && checklength(source, packet, ether_size + ip6_size + 8)
-			&& packet->data[54] == IPPROTO_ICMPV6 && checklength(source, packet, ether_size + ip6_size + 8 + icmp6_size)
-			&& packet->data[62] == ICMP6_MEMBERSHIP_REPORT) {
-		route_membershipreport(source, packet);
-		return;
-	}
-	
-	if(packet->data[38] == 0xff && packet->data[39] & 0x0c) {
-		route_ipv6_multicast(source, packet);
-		return;
-	}
-#endif
-
-	route_ipv6_unicast(source, packet);
+	if(broadcast_mode && packet->data[38] == 255)
+		broadcast_packet(source, packet);
+	else
+		route_ipv6_unicast(source, packet);
 }
 
 /* RFC 826 */
 
-static void route_arp(node_t *source, vpn_packet_t *packet)
-{
+static void route_arp(node_t *source, vpn_packet_t *packet) {
 	struct ether_arp arp;
 	subnet_t *subnet;
 	struct in_addr addr;
 
-	cp();
-
 	if(!checklength(source, packet, ether_size + arp_size))
 		return;
 
 	if(source != myself) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Got ARP request from %s (%s) while in router mode!"), source->name, source->hostname);
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Got ARP request from %s (%s) while in router mode!", source->name, source->hostname);
 		return;
 	}
 
@@ -745,7 +768,7 @@ static void route_arp(node_t *source, vpn_packet_t *packet)
 
 	if(ntohs(arp.arp_hrd) != ARPHRD_ETHER || ntohs(arp.arp_pro) != ETH_P_IP ||
 	   arp.arp_hln != ETH_ALEN || arp.arp_pln != sizeof(addr) || ntohs(arp.arp_op) != ARPOP_REQUEST) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: received unknown type ARP request"));
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: received unknown type ARP request");
 		return;
 	}
 
@@ -754,7 +777,7 @@ static void route_arp(node_t *source, vpn_packet_t *packet)
 	subnet = lookup_subnet_ipv4((ipv4_t *) &arp.arp_tpa);
 
 	if(!subnet) {
-		ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: ARP request for unknown address %d.%d.%d.%d"),
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet: ARP request for unknown address %d.%d.%d.%d",
 				   arp.arp_tpa[0], arp.arp_tpa[1], arp.arp_tpa[2],
 				   arp.arp_tpa[3]);
 		return;
@@ -783,19 +806,147 @@ static void route_arp(node_t *source, vpn_packet_t *packet)
 	send_packet(source, packet);
 }
 
-void route(node_t *source, vpn_packet_t *packet)
-{
-	cp();
+static void route_mac(node_t *source, vpn_packet_t *packet) {
+	subnet_t *subnet;
+	mac_t dest;
+
+	/* Learn source address */
+
+	if(source == myself) {
+		mac_t src;
+		memcpy(&src, &packet->data[6], sizeof src);
+		learn_mac(&src);
+	}
+
+	/* Lookup destination address */
+
+	memcpy(&dest, &packet->data[0], sizeof dest);
+	subnet = lookup_subnet_mac(NULL, &dest);
+
+	if(!subnet) {
+		broadcast_packet(source, packet);
+		return;
+	}
+
+	if(subnet->owner == source) {
+		ifdebug(TRAFFIC) logger(LOG_WARNING, "Packet looping back to %s (%s)!", source->name, source->hostname);
+		return;
+	}
+
+	if(forwarding_mode == FMODE_OFF && source != myself && subnet->owner != myself)
+		return;
+
+	uint16_t type = packet->data[12] << 8 | packet->data[13];
+
+	if(priorityinheritance && type == ETH_P_IP && packet->len >= ether_size + ip_size)
+		packet->priority = packet->data[15];
+
+	// Handle packets larger than PMTU
+
+	node_t *via = (subnet->owner->via == myself) ? subnet->owner->nexthop : subnet->owner->via;
+
+	if(directonly && subnet->owner != via)
+		return;
+	
+	if(via && packet->len > via->mtu && via != myself) {
+		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);
+		length_t ethlen = 14;
+
+		if(type == ETH_P_8021Q) {
+			type = packet->data[16] << 8 | packet->data[17];
+			ethlen += 4;
+		}
+
+		if(type == ETH_P_IP && packet->len > 576 + ethlen) {
+			if(packet->data[6 + ethlen] & 0x40) {
+				packet->len = via->mtu;
+				route_ipv4_unreachable(source, packet, ethlen, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED);
+			} else {
+				fragment_ipv4_packet(via, packet, ethlen);
+			}
+			return;
+		} else if(type == ETH_P_IPV6 && packet->len > 1280 + ethlen) {
+			packet->len = via->mtu;
+			route_ipv6_unreachable(source, packet, ethlen, ICMP6_PACKET_TOO_BIG, 0);
+			return;
+		}
+	}
+
+	clamp_mss(source, via, packet);
+ 
+	send_packet(subnet->owner, packet);
+}
+
+static bool do_decrement_ttl(node_t *source, vpn_packet_t *packet) {
+	uint16_t type = packet->data[12] << 8 | packet->data[13];
+	length_t ethlen = ether_size;
+
+	if(type == ETH_P_8021Q) {
+		type = packet->data[16] << 8 | packet->data[17];
+		ethlen += 4;
+	}
+
+	switch (type) {
+		case ETH_P_IP:
+			if(!checklength(source, packet, ethlen + ip_size))
+				return false;
+
+			if(packet->data[ethlen + 8] <= 1) {
+				if(packet->data[ethlen + 11] != IPPROTO_ICMP || packet->data[ethlen + 32] != ICMP_TIME_EXCEEDED)
+					route_ipv4_unreachable(source, packet, ethlen, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL);
+				return false;
+			}
+
+			uint16_t old = packet->data[ethlen + 8] << 8 | packet->data[ethlen + 9];
+			packet->data[ethlen + 8]--;
+			uint16_t new = packet->data[ethlen + 8] << 8 | packet->data[ethlen + 9];
+
+			uint32_t checksum = packet->data[ethlen + 10] << 8 | packet->data[ethlen + 11];
+			checksum += old + (~new & 0xFFFF);
+			while(checksum >> 16)
+				checksum = (checksum & 0xFFFF) + (checksum >> 16);
+			packet->data[ethlen + 10] = checksum >> 8;
+			packet->data[ethlen + 11] = checksum & 0xff;
+
+			return true;
+
+		case ETH_P_IPV6:
+			if(!checklength(source, packet, ethlen + ip6_size))
+				return false;
+
+			if(packet->data[ethlen + 7] <= 1) {
+				if(packet->data[ethlen + 6] != IPPROTO_ICMPV6 || packet->data[ethlen + 40] != ICMP6_TIME_EXCEEDED)
+					route_ipv6_unreachable(source, packet, ethlen, ICMP6_TIME_EXCEEDED, ICMP6_TIME_EXCEED_TRANSIT);
+				return false;
+			}
+
+			packet->data[ethlen + 7]--;
+
+			return true;
+
+		default:
+			return true;
+	}
+}
+
+void route(node_t *source, vpn_packet_t *packet) {
+	if(forwarding_mode == FMODE_KERNEL && source != myself) {
+		send_packet(myself, packet);
+		return;
+	}
 
 	if(!checklength(source, packet, ether_size))
 		return;
 
+	if(decrement_ttl && source != myself)
+		if(!do_decrement_ttl(source, packet))
+			return;
+
 	switch (routing_mode) {
 		case RMODE_ROUTER:
 			{
-				uint16_t type;
+				uint16_t type = packet->data[12] << 8 | packet->data[13];
 
-				type = ntohs(*((uint16_t *)(&packet->data[12])));
 				switch (type) {
 					case ETH_P_ARP:
 						route_arp(source, packet);
@@ -810,7 +961,7 @@ void route(node_t *source, vpn_packet_t *packet)
 						break;
 
 					default:
-						ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet from %s (%s): unknown type %hx"), source->name, source->hostname, type);
+						ifdebug(TRAFFIC) logger(LOG_WARNING, "Cannot route packet from %s (%s): unknown type %hx", source->name, source->hostname, type);
 						break;
 				}
 			}