In order to build the server, simply run cargo build. Then once the server has been compiled you can run the server using two different ways.
The first way allows you to run the server without specifying a port. The server will find an open port to run itself on and inform you of the port it picked.
$ ./target/debug/tftp_server_bin
Server created at address: V4(127.0.0.1:61204)
Getting None when receiving from server socket
In this example, the port number picked was 61204.
The second way allows you to choose an open port for the server to run on. You specify the port number as a command line argument when running the server.
$ ./target/debug/tftp_server_bin 61204
Getting None when receiving from server socket
If the port is already taken or there is an error using the port, the server will panic with an IoError.
$ ./target/debug/tftp_server_bin 20
thread 'main' panicked at 'Error creating server: IoError(Error { repr: Os { code: 13, message: "Permission denied" } })', ../src/libcore/result.rs:799
note: Run with `RUST_BACKTRACE=1` for a backtrace.