TCP Client in Rust

tcp_client.rs

#![allow(unused_variables)]
#![allow(unused_imports)]

use std::env;
use std::process;
use std::thread;
use std::io::{self, Read, Write, Error};
use std::net::TcpStream;
use std::net::TcpListener;

type Port = u16;

struct Program {
	name: String
}

impl Program {
	fn new(name: String) -> Program {
		Program { name: name }
	}

	fn usage(&self) {
		println!("usage: {} HOST PORT",self.name);
	}

	fn print_error(&self,mesg: String) {
		writeln!(io::stderr(),"{}: error: {}",self.name,mesg);
	}

	fn print_fail(&self,mesg: String) -> ! {
		self.print_error(mesg);
		self.fail();
	}

	fn exit(&self,status: i32) -> ! { process::exit(status); }
	fn fail(&self) -> ! { self.exit(-1); }
}

fn main() {
	let mut args = env::args();
	let program = Program::new(
		args.next().unwrap_or("test".to_string())
	);

	let host = args.next().unwrap_or_else(|| {
		program.usage();
		program.fail();
	});

	let port = args.next().unwrap_or_else(|| {
		program.usage();
		program.fail();
	}).parse::<Port>().unwrap_or_else(|error| {
		program.print_error(format!("invalid port number: {}",error));
		program.usage();
		program.fail();
	});

	let mut stream = TcpStream::connect(
		(host.as_str(), port)
	).unwrap_or_else(|error|
		program.print_fail(error.to_string())
	);
	let mut input_stream = stream.try_clone().unwrap();

	let handler = thread::spawn(move || {
		let mut client_buffer = [0u8; 1024];

		loop {
			match input_stream.read(&mut client_buffer) {
				Ok(n) => {
					if n == 0 {
						program.exit(0);
					}
					else
					{
						io::stdout().write(&client_buffer).unwrap();
						io::stdout().flush().unwrap();
					}
				},
				Err(error) => program.print_fail(error.to_string()),
			}
		}
	});

	let output_stream = &mut stream;
	let mut user_buffer = String::new();

	loop {
		io::stdin().read_line(&mut user_buffer).unwrap();

		output_stream.write(user_buffer.as_bytes()).unwrap();
		output_stream.flush().unwrap();
	}
}