INADDR_ANY doesn't seem to be defined anywhere in Rust land. In C, to bind a socket in a client in preparation for sending, you'd bind to INADDR_ANY, let it bind to some or all available interfaces, and go from there. INADDR_ANY is just the zero IP address.
So I tried
let mut socket = UdpSocket("0")?;
That yields an "Invalid socket address" error. What's the "Any" address in Rust?