The svcudp_create() function shall
create a UDP/IP-based RPC service transport, and return
a pointer to its descriptor. The transport is associated
with the socket sock, which may be
RPC_ANYSOCK, in which case a new socket shall
be created. If the socket is not bound to a local UDP port, then
svcudp_create() shall bind it to an arbitrary port.
If svcudp_create() returns successfully, then the
xp_sock field in the result shall be the
transport's socket descriptor, and the
field shall be the transport's port number.
Upon successful completion, svcudp_create() shall return a pointer to a RPC service transport; otherwise, a null pointer shall be returned.