01_IPv6-Basic-Support.diff

01_IPv6-Basic-Support.diff

This patch provides an algorithm which, given a hostname and a numeric port identifier,
will look up all matching IPv4/IPv6 addresses and either bind it (for passive sockets)
or connect to it (for active sockets).

Certain socket options need to be set before a connection is established. Since in
paraslash the demand for such options is not very big at this time, the only present
case (setting SO_REUSEADDR on passive sockets) has been integrated into the main loop.

A more sophisticated variant for setting pre-connection socket options exists and is
available as part of the DCCP library. The current solution is extensible, i.e. if one
wants to later add more options, the alternative (more sophisticated approach) can be
used. But for now, that would just have meant code bloat.

The subsequent patches in this set will step by step replace the old infrastructure
with the use of this algorithm.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>