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|
//! A UDP client that just sends everything it gets via `stdio` in a single datagram, and then
//! waits for a reply.
//!
//! For the reasons of simplicity data from `stdio` is read until `EOF` in a blocking manner.
//!
//! You can test this out by running an echo server:
//!
//! ```
//! $ cargo run --example echo-udp -- 127.0.0.1:8080
//! ```
//!
//! and running the client in another terminal:
//!
//! ```
//! $ cargo run --example udp-client
//! ```
//!
//! You can optionally provide any custom endpoint address for the client:
//!
//! ```
//! $ cargo run --example udp-client -- 127.0.0.1:8080
//! ```
//!
//! Don't forget to pass `EOF` to the standard input of the client!
//!
//! Please mind that since the UDP protocol doesn't have any capabilities to detect a broken
//! connection the server needs to be run first, otherwise the client will block forever.
#![warn(rust_2018_idioms)]
use std::env;
use std::error::Error;
use std::io::{stdin, Read};
use std::net::SocketAddr;
use tokio::net::UdpSocket;
fn get_stdin_data() -> Result<Vec<u8>, Box<dyn std::error::Error>> {
let mut buf = Vec::new();
stdin().read_to_end(&mut buf)?;
Ok(buf)
}
#[tokio::main]
async fn main() -> Result<(), Box<dyn Error>> {
let remote_addr: SocketAddr = env::args()
.nth(1)
.unwrap_or_else(|| "127.0.0.1:8080".into())
.parse()?;
// We use port 0 to let the operating system allocate an available port for us.
let local_addr: SocketAddr = if remote_addr.is_ipv4() {
"0.0.0.0:0"
} else {
"[::]:0"
}
.parse()?;
let socket = UdpSocket::bind(local_addr).await?;
const MAX_DATAGRAM_SIZE: usize = 65_507;
socket.connect(&remote_addr).await?;
let data = get_stdin_data()?;
socket.send(&data).await?;
let mut data = vec![0u8; MAX_DATAGRAM_SIZE];
let len = socket.recv(&mut data).await?;
println!(
"Received {} bytes:\n{}",
len,
String::from_utf8_lossy(&data[..len])
);
Ok(())
}
|
