- wrap mappedaddr block by #ifdef INET for IPv6-only kernel in future.
- rejects IPv6 packet toward IPv4-mapped address if its source address is not an IPv4-mapped IPv6 address, since the converted IPv4 packets would have an unexpected IPv4 source address.
- when V6ONLY socket option is set, discard packets destined to a v4/ipv4 mapped ipv6 address.
- have PULLDOWN_TEST codepath.
- get rid of in6_mcmatch().
Obtained from: KAME