fastwebsockets

Documentation | Benchmarks

fastwebsockets is a fast WebSocket protocol implementation.

Passes the Autobahn|TestSuite1 and fuzzed with LLVM's libfuzzer.

You can use it as a raw websocket frame parser and deal with spec compliance yourself, or you can use it as a full-fledged websocket client/server.

use fastwebsockets::{Frame, OpCode, WebSocket};

async fn handle_client(
  mut socket: TcpStream,
) -> Result {
  handshake(&mut socket).await?;

  let mut ws = WebSocket::after_handshake(socket);
  ws.set_writev(true);
  ws.set_auto_close(true);
  ws.set_auto_pong(true);

  loop {
    let frame = ws.read_frame().await?;

    match frame {
      OpCode::Close => break,
      OpCode::Text | OpCode::Binary => {
        let frame = Frame::new(true, frame.opcode, None, frame.payload);
        ws.write_frame(frame).await?;
      }
    }
  }

  Ok(())
}

Fragmentation

By default, fastwebsockets will give the application raw frames with FIN set. Other crates like tungstenite which will give you a single message with all the frames concatenated.

For concanated frames, use FragmentCollector:

let mut ws = WebSocket::after_handshake(socket);
let mut ws = FragmentCollector::new(ws);

let incoming = ws.read_frame().await?;
// Always returns full messages
assert!(incoming.fin);

permessage-deflate is not supported yet.

HTTP Upgrade

Enable the upgrade feature to do server-side upgrades and client-side handshakes.

This feature is powered by hyper.

use fastwebsockets::upgrade;
use hyper::{Request, body::{Incoming, Bytes}, Response};
use http_body_util::Empty;
use anyhow::Result;

async fn server_upgrade(
  mut req: Request,
) -> Result> {
  let (response, fut) = upgrade::upgrade(&mut req)?;

  tokio::spawn(async move {
    if let Err(e) = handle_client(fut).await {
      eprintln!("Error in websocket connection: {}", e);
    }
  });

  Ok(response)
}

Use the handshake module for client-side handshakes.

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Usage with Axum

Enable the Axum integration with features = ["upgrade", "with_axum"] in Cargo.toml.

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