sockaddr_in (port,addr_string)
pack_sockaddr_in (port, addr_string)
Takes a port number and a four-byte addr_string (as returned by inet_aton) and
returns the socket address structure including those arguments packed with the AF_INET
argument.
This structure is normally what you need for the arguments in bind, connect,
and send, and is also returned by getpeername, getsockname, and recv.