Commit befffe90 authored Dec 12, 2006 by Brian Haley Committed by David S. Miller Dec 13, 2006

[IPV6]: Fix IPV6_UNICAST_HOPS getsockopt().



> Relevant standard (RFC 3493) notes:
>
>    The IPV6_UNICAST_HOPS option may be used with getsockopt() to
>    determine the hop limit value that the system will use for subsequent
>    unicast packets sent via that socket.
>
> I don't reckon -1 could be the hop limit value.

-1 means un-initialized.

> IMHO, the value from
> case 1 (if socket is connected to some destination), otherwise case 2
> (if bound to a scope interface) or ultimately the default hop limit
> ought to be returned instead, as it will be most often correct, while
> the current behavior is always wrong, unless setsockopt() has been used
> first. I don't if some people may think doing a route lookup in
> getsockopt might be overly expensive, but at least the two other cases
> should be ok, particularly the last one.

The following patch seems to work for me, but this code has behaved this
way for a while, so don't know if it will break any existing apps.

Signed-off-by: Brian Haley <brian.haley@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 832e3ca6

net/ipv6/ipv6_sockglue.c

+19 −4

Original line number	Diff line number	Diff line
		@@ -978,12 +978,27 @@ static int do_ipv6_getsockopt(struct sock *sk, int level, int optname,
		break;

		case IPV6_UNICAST_HOPS:
		val = np->hop_limit;
		break;

		case IPV6_MULTICAST_HOPS:
		{
		struct dst_entry *dst;

		if (optname == IPV6_UNICAST_HOPS)
		val = np->hop_limit;
		else
		val = np->mcast_hops;

		dst = sk_dst_get(sk);
		if (dst) {
		if (val < 0)
		val = dst_metric(dst, RTAX_HOPLIMIT);
		if (val < 0)
		val = ipv6_get_hoplimit(dst->dev);
		dst_release(dst);
		}
		if (val < 0)
		val = ipv6_devconf.hop_limit;
		break;
		}

		case IPV6_MULTICAST_LOOP:
		val = np->mc_loop;