SQL queries inside a C function?

Hi everyone,

How do I get the active connection handle from inside a C function linked as a PL/pgSQL function, like:

Datum pg_do_something(PG_FUNCTION_ARGS)
{
PGconn *conn = ....?
// now do some SELECTs / INSERTs
PG_RETURN_INT32(result);
}

Thanks,
Elliot