LeonHartley / websocket-gateway

WebSocket to TCP proxy written in Rust

websocket-gateway

WebSocket to TCP proxy written in Rust.

Built to enable web-based WebSocket connections on pre-existing TCP-based game servers. Works for a specific use-case, may be useful for other things too.

Built for fun. :)

Implementation

The proxy is built using tungstenite and tokio-tungstenite for inbound WebSocket connections and uses a raw async Tokio TcpStream for the TCP outbound client. The actual proxy stream is an implementation of a futures::Stream which outputs events for both TCP and WebSocket streams such as Read, and Closed.

This enables us to efficiently poll a single future and also keeps the stream simple, we can just listen to all events in a single block of code:

while let Some(event) = proxy_stream.next().await {
    match event {
        ProxyEvent::WebSocketRead(buffer) => {
            debug!("received from websocket, len: {}", buffer.len());
            tcp_sender.send(buffer).await;
        }

        ProxyEvent::TcpRead(buffer) => {
            debug!("received from tcp, len: {}", buffer.len());
            ws_sender.send(Message::Binary(buffer)).await;
        }

        ProxyEvent::TcpClosed => {
            debug!("tcp closed");
            ws_sender.close().await;
            break;
        }

        ProxyEvent::WebSocketClosed => {
            debug!("websocket closed");
            tcp_sender.close().await;
            break;
        }
    }
}