by a protocol, to detirmine if an address matches the net this address
is part of. This is needed by protocols for which netmasks
"just don't work", for example appletalk.
Also add the code in appletalk to make use of this new feature.
Thsi fixes one of the longest standing bugs in appletalk.
The inability to talk to machines to which the path is via a router
which is on a different net, but the same netrange, as your interface.
Protocols that do not supply this function (e.g. IP) should not be affected.
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
multicast group memberships. This is not actually operative
at the moment (a lot of other code still needs to be changed), but
this seemed like a useful reference point to check in so that
others (i.e. Bill Fenner) have fair warning of where we are going.
