# UDPflow

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[![Released API docs](https://docs.rs/udpflow/badge.svg)](https://docs.rs/udpflow)

Stream API for tokio-udp.

## TCP-like UDP stream

```rust
use tokio::net::UdpSocket;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use udpflow::{UdpListener, UdpStreamLocal, UdpStreamRemote};
async fn server() {
    let addr = "127.0.0.1:5000".parse().unwrap();
    let listener = UdpListener::new(addr).unwrap();
    loop {
        let mut buf = vec![0u8; 0x2000];
        let (n, stream, addr) = listener.accept(&mut buf).await.unwrap();
        buf.truncate(n);
        tokio::spawn(handle(stream, buf));
    }
}

async fn handle(mut stream1: UdpStreamLocal, first_packet: Vec<u8>) {
    let local = "127.0.0.1:0".parse().unwrap();
    let remote = "127.0.0.1:10000".parse().unwrap();
    let mut stream2 = UdpStreamRemote::new(local, remote).await.unwrap();
    stream2.write_all(&first_packet).await.unwrap();
    let mut buf = vec![0u8; 256];
    stream1.read(&mut buf).await; stream2.write(&buf).await;
    stream2.read(&mut buf).await; stream1.write(&buf).await;
}
```

## Send/Recv framed data

```rust
use tokio::net::TcpStream;
use udpflow::UotStream;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
async {
    let stream = TcpStream::connect("127.0.0.1:8080").await.unwrap();
    let mut stream = UotStream::new(stream);
    let mut buf = vec![0u8; 256];
    // read a frame
    let n = stream.read(&mut buf).await.unwrap();
    // write a frame
    stream.write_all(&buf[..n]).await;
};
```

## UoT Specification

```plain
+------+----------+
| LEN  |   DATA   |
+------+----------+
|  2   | Variable |
+------+----------+
```

\*LEN is a 16-bit unsigned integer in big endian byte order.