tcp_echo.rs

use std::io::net::ip::SocketAddr;
use std::io::net::tcp::{TcpListener, TcpStream};
use std::io::{IoResult, Acceptor, Listener};

fn main() {
  let addr = from_str::<SocketAddr>("127.0.0.1:7123").unwrap();

  match TcpListener::bind(addr) {
    Err(e) => fail!("Unable to bind to {}: {}", addr, e),
    Ok(l) => listen(l),
  };
}

fn listen(listener: TcpListener) {
  match listener.listen() {
    Err(e) => fail!("Unable to listen: {}", e),
    Ok(mut a) => {
      println!("listening...");
      for stream in a.incoming() {
        handle_incoming(stream);
      }
    },
  };
}

fn handle_incoming(stream: IoResult<TcpStream>) {
  match stream {
    Err(e) => println!("Unable to listen: {}", e),
    Ok(s) => {
      spawn(proc () {
        handle_client(s);
      });
    },
  }
}

fn handle_client(mut stream: TcpStream) {
  let mut buf = [0, ..1024];
  loop {
    match stream.read(buf.as_mut_slice()) {
      Err(e) => fail!("error reading: {}", e),
      Ok(len) => {
        match stream.write(buf.slice(0, len)) {
          Err(e) => fail!("unable to echo: {}", e),
          Ok(_) => println!("echoed {:u} bytes", len)
        }
      },
    };
  }
}