From 1c1a67fd93530b9d16538ab2897c3911d3b16574 Mon Sep 17 00:00:00 2001
From: Guus Sliepen <guus@tinc-vpn.org>
Date: Tue, 17 Feb 2009 14:43:05 +0100
Subject: [PATCH] Handle neighbor solicitation requests without link layer
addresses.
Apparently FreeBSD likes to send out neighbor solicitation requests, even on a
tun interface where this is completely pointless. These requests do not have an
option header containing a link layer address, so the proxy-neighborsol code
was treating these requests as invalid. We now handle such requests, and send
back equally pointless replies, also without a link layer address. This seems
to satisfy FreeBSD.
---
src/route.c | 38 +++++++++++++++++++++++++++-----------
1 file changed, 27 insertions(+), 11 deletions(-)
diff --git a/src/route.c b/src/route.c
index c458ea4f..52b538b1 100644
--- a/src/route.c
+++ b/src/route.c
@@ -521,6 +521,7 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
struct nd_opt_hdr opt;
subnet_t *subnet;
uint16_t checksum;
+ bool has_opt;
struct {
struct in6_addr ip6_src; /* source address */
@@ -531,9 +532,11 @@ static void route_neighborsol(node_t *source, vpn_packet_t *packet)
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);
return;
@@ -543,7 +546,8 @@ 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 */
@@ -553,7 +557,7 @@ 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) {
+ (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;
}
@@ -562,15 +566,20 @@ 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);
+ }
if(checksum) {
ifdebug(TRAFFIC) logger(LOG_WARNING, _("Cannot route packet: checksum error for neighbor solicitation request"));
@@ -608,7 +617,8 @@ 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;
@@ -619,15 +629,20 @@ 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;
@@ -635,7 +650,8 @@ 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);
}
--
2.39.5