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Diffstat (limited to 'examples/echo-udp.rs')
-rw-r--r-- | examples/echo-udp.rs | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/examples/echo-udp.rs b/examples/echo-udp.rs new file mode 100644 index 00000000..f1e8134d --- /dev/null +++ b/examples/echo-udp.rs @@ -0,0 +1,69 @@ +//! An UDP echo server that just sends back everything that it receives. +//! +//! If you're on Unix you can test this out by in one terminal executing: +//! +//! cargo run --example echo-udp +//! +//! and in another terminal you can run: +//! +//! cargo run --example connect -- --udp 127.0.0.1:8080 +//! +//! Each line you type in to the `nc` terminal should be echo'd back to you! + +#![warn(rust_2018_idioms)] + +use std::error::Error; +use std::net::SocketAddr; +use std::{env, io}; +use tokio; +use tokio::net::UdpSocket; + +struct Server { + socket: UdpSocket, + buf: Vec<u8>, + to_send: Option<(usize, SocketAddr)>, +} + +impl Server { + async fn run(self) -> Result<(), io::Error> { + let Server { + mut socket, + mut buf, + mut to_send, + } = self; + + loop { + // First we check to see if there's a message we need to echo back. + // If so then we try to send it back to the original source, waiting + // until it's writable and we're able to do so. + if let Some((size, peer)) = to_send { + let amt = socket.send_to(&buf[..size], &peer).await?; + + println!("Echoed {}/{} bytes to {}", amt, size, peer); + } + + // If we're here then `to_send` is `None`, so we take a look for the + // next message we're going to echo back. + to_send = Some(socket.recv_from(&mut buf).await?); + } + } +} + +#[tokio::main] +async fn main() -> Result<(), Box<dyn Error>> { + let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string()); + + let socket = UdpSocket::bind(&addr).await?; + println!("Listening on: {}", socket.local_addr()?); + + let server = Server { + socket, + buf: vec![0; 1024], + to_send: None, + }; + + // This starts the server task. + server.run().await?; + + Ok(()) +} |