comment on v4mapped-api-harmful

[Pekka Savola <pekkas@netcore.fi>]

Hello,

Even though I'm sympathic to the cause, I, too, have started to believe 
it's too late now -- changing this would only add confusion.  We don't 
want even another different behaviour when binding addresses.

However, I believe the long-term goal should be separate INET6 and INET.  
The question is how to get there, and how quickly.

In particular,

o Do not intentionally use RFC2553 section 3.7 (IPv4 traffic on AF_INET6
  socket).  Implement server applications by using separate AF_INET and
  AF_INET6 listening sockets.  Explicitly set the IPV6_V6ONLY socket
  option to on, whenever the socket option is available on the system.

==> please provide some overview on the migration path (kernel/library, 
apps) from the current state to this.

Reversing the default value would appear to be totally unacceptable, 
because it'd break _all_ current apps.

Perhaps detecting the behaviour might be doable by some test macro..

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords