sending ICMP redirects for multiple on-interface nets

["Jonathan A. Kollasch" <jakllsch%kollasch.net@localhost>]

Since 1.1.1.1, ip_forward() has only sent ICMP redirects when the
destination address is in the same subnet as a (random?) address
on the interface.  ip_input.c:1385

I have multiple subnets on the same interface, and redirects are not
generated for traffic to another same-interface subnet.

Is this check even needed?  Or do we need to iterate through all the
IPv4 networks on the interface checking for a match?

        Jonathan Kollasch