static void ip6_link_failure(struct sk_buff *skb)
{
struct rt6_info *rt;
icmpv6_send(skb, ICMPV6_DEST_UNREACH, ICMPV6_ADDR_UNREACH, 0, skb->dev);
rt = (struct rt6_info *) skb->dst;
if (rt) {
if (rt->rt6i_flags&RTF_CACHE) {
dst_set_expires(&rt->u.dst, 0);
rt->rt6i_flags |= RTF_EXPIRES;
} else if (rt->rt6i_node && (rt->rt6i_flags & RTF_DEFAULT))
rt->rt6i_node->fn_sernum = -1;
}
}
/*
* The decnet standards don't impose a particular minimum mtu, what they
* do insist on is that the routing layer accepts a datagram of at least
* 230 bytes long. Here we have to subtract the routing header length from
* 230 to get the minimum acceptable mtu. If there is no neighbour, then we
* assume the worst and use a long header size.
*
* We update both the mtu and the advertised mss (i.e. the segment size we
* advertise to the other end).
*/
static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu)
{
u32 min_mtu = 230;
struct dn_dev *dn = dst->neighbour ?
(struct dn_dev *)dst->neighbour->dev->dn_ptr : NULL;
if (dn && dn->use_long == 0)
min_mtu -= 6;
else
min_mtu -= 21;
if (dst->metrics[RTAX_MTU-1] > mtu && mtu >= min_mtu) {
if (!(dst_metric_locked(dst, RTAX_MTU))) {
dst->metrics[RTAX_MTU-1] = mtu;
dst_set_expires(dst, dn_rt_mtu_expires);
}
if (!(dst_metric_locked(dst, RTAX_ADVMSS))) {
u32 mss = mtu - DN_MAX_NSP_DATA_HEADER;
if (dst->metrics[RTAX_ADVMSS-1] > mss)
dst->metrics[RTAX_ADVMSS-1] = mss;
}
}
}
void rt6_pmtu_discovery(struct in6_addr *daddr, struct in6_addr *saddr,
struct net_device *dev, u32 pmtu)
{
struct rt6_info *rt, *nrt;
if (pmtu < IPV6_MIN_MTU) {
if (net_ratelimit())
printk(KERN_DEBUG "rt6_pmtu_discovery: invalid MTU value %d\n",
pmtu);
/* According to RFC1981, the PMTU is set to the IPv6 minimum
link MTU if the node receives a Packet Too Big message
reporting next-hop MTU that is less than the IPv6 minimum MTU.
*/
pmtu = IPV6_MIN_MTU;
}
rt = rt6_lookup(daddr, saddr, dev->ifindex, 0);
if (rt == NULL)
return;
if (pmtu >= rt->u.dst.pmtu)
goto out;
/* New mtu received -> path was valid.
They are sent only in response to data packets,
so that this nexthop apparently is reachable. --ANK
*/
dst_confirm(&rt->u.dst);
/* Host route. If it is static, it would be better
not to override it, but add new one, so that
when cache entry will expire old pmtu
would return automatically.
*/
if (rt->rt6i_flags & RTF_CACHE) {
rt->u.dst.pmtu = pmtu;
dst_set_expires(&rt->u.dst, ip6_rt_mtu_expires);
rt->rt6i_flags |= RTF_MODIFIED|RTF_EXPIRES;
goto out;
}
/* Network route.
Two cases are possible:
1. It is connected route. Action: COW
2. It is gatewayed route or NONEXTHOP route. Action: clone it.
*/
if (!rt->rt6i_nexthop && !(rt->rt6i_flags & RTF_NONEXTHOP)) {
nrt = rt6_cow(rt, daddr, saddr);
if (!nrt->u.dst.error) {
nrt->u.dst.pmtu = pmtu;
/* According to RFC 1981, detecting PMTU increase shouldn't be
happened within 5 mins, the recommended timer is 10 mins.
Here this route expiration time is set to ip6_rt_mtu_expires
which is 10 mins. After 10 mins the decreased pmtu is expired
and detecting PMTU increase will be automatically happened.
*/
dst_set_expires(&nrt->u.dst, ip6_rt_mtu_expires);
nrt->rt6i_flags |= RTF_DYNAMIC|RTF_EXPIRES;
dst_release(&nrt->u.dst);
}
} else {
nrt = ip6_rt_copy(rt);
if (nrt == NULL)
goto out;
ipv6_addr_copy(&nrt->rt6i_dst.addr, daddr);
nrt->rt6i_dst.plen = 128;
nrt->u.dst.flags |= DST_HOST;
nrt->rt6i_nexthop = neigh_clone(rt->rt6i_nexthop);
dst_set_expires(&nrt->u.dst, ip6_rt_mtu_expires);
nrt->rt6i_flags |= RTF_DYNAMIC|RTF_CACHE|RTF_EXPIRES;
nrt->u.dst.pmtu = pmtu;
rt6_ins(nrt, NULL);
}
out:
dst_release(&rt->u.dst);
}