Fetching Server configured port from C Module

Hi There,
I'm having a bit of an issue finding a C function to fetch the
configured server port from a C module.

We have written a C module to allow for remote clients to call a function
to run pg_dump/pg_restore remotely but create files locally on the db
server.

Currently it works fine if the client connects through a network socket as
we're using inet_server_port to get the port to pass onto pg_dump/restore.
But if the client is connected through a unix socket (actually a remote
client connecting to pgbouncer which is connecting to postgres though the
unix socket) inet_server_port is null. I've looked for a function that we
can use to get the configured server port but haven't had any luck.

I could hard code the port in the module when we build it but it would be
nice to be able to change the configured postgres port and not have to
rebuild the module.

Anyone have any suggestions?

I've posted the code for our backup module here:

http://pastebin.com/wQ6VidWn