yawc

Yet another websocket crate. But a fast, secure, and RFC-compliant WebSocket implementation for Rust with advanced compression support.

Features

Full RFC 6455 Compliance: Complete implementation of the WebSocket protocol
Secure by Default: Built-in TLS support with rustls
Advanced Compression: Support for permessage-deflate (RFC 7692)
Zero-Copy Design: Efficient frame processing with minimal allocations
Automatic Frame Management: Handles control frames and fragmentation
Autobahn Test Suite: Passes all test cases for both client and server modes
WebAssembly Support: Works seamlessly in WASM environments for browser-based applications

Usage

Add this to your Cargo.toml:

[dependencies]
yawc = "0.2"

Client Example

use futures::SinkExt;
use futures::StreamExt;
use yawc::{frame::FrameView, frame::OpCode, Options, Result, WebSocket};

#[tokio::main]
async fn main() -> Result<()> {
    // Connect with default options
    let mut ws = WebSocket::connect("wss://echo.websocket.org".parse()?).await?;

    // Send and receive messages
    ws.send(FrameView::text("Hello WebSocket!")).await?;

    while let Some(frame) = ws.next().await {
        match frame.opcode {
            OpCode::Text => println!("Received: {}", std::str::from_utf8(&frame.payload).unwrap()),
            OpCode::Binary => println!("Received binary: {} bytes", frame.payload.len()),
            _ => {} // Handle control frames automatically
        }
    }

    Ok(())
}

[dependencies]
yawc = { version = "0.2" }
futures = { version = "0.3", default-features = false, features = ["std"] }
tokio = { version = "1", features = ["rt", "rt-multi-thread", "macros"] }

Server Example

use hyper::{Request, Response, body::Incoming};
use futures::StreamExt;
use futures::SinkExt;
use bytes::Bytes;
use http_body_util::Empty;
use yawc::{WebSocket, Result};

async fn handle_upgrade(req: Request<Incoming>) -> Result<Response<Empty<Bytes>>> {
    // Upgrade the connection
    let (response, upfn) = WebSocket::upgrade(req)?;

    // Handle the WebSocket connection in a separate task
    tokio::spawn(async move {
        let mut ws = upfn.await.expect("upgrade");

        while let Some(frame) = ws.next().await {
            // Echo the received frames back to the client
            let _ = ws.send(frame).await;
        }
    });

    Ok(response)
}

#[tokio::main]
async fn main() {
    // configure the server
}

[dependencies]
yawc = {version = "0.2", features = ["reqwest"] }
futures = { version = "0.3.31", default-features = false, features = ["std"] }
tokio = { version = "1.41.1", features = ["rt", "rt-multi-thread", "macros"] }
hyper = { version = "1.5.0", features = ["http1", "server"] }
http-body-util = "0.1.2"
bytes = "1.8.0"

The examples directory contains several documented and runnable examples showcasing advanced WebSocket functionality. You can find a particularly comprehensive example in the axum_proxy implementation, which demonstrates:

Building a WebSocket broadcast server that efficiently relays messages between multiple connected clients
Creating a reverse proxy that transparently forwards WebSocket connections to upstream servers
Proper connection lifecycle management and error handling Integration with the Axum web framework for robust HTTP request handling
Advanced usage patterns like connection pooling and message filtering

These examples serve as practical reference implementations for common WebSocket architectural patterns and best practices using yawc.

Feature Flags

reqwest: Use reqwest as the HTTP client
axum: Enable integration with the Axum web framework
logging: Enable debug logging for connection events
zlib: Enable advanced compression options with zlib (not recommended unless you know what you are doing)

Axum Server Example

use axum::{
    routing::get,
    Router,
};
use yawc::{IncomingUpgrade, Options};

async fn websocket_handler(ws: IncomingUpgrade) -> axum::response::Response {
    let options = Options::default()
        .with_compression_level(CompressionLevel::default())
        .with_utf8();

    let (response, ws) = ws.upgrade(options).unwrap();

    // Handle the WebSocket connection in a separate task
    tokio::spawn(async move {
        if let Ok(mut ws) = ws.await {
            while let Ok(frame) = ws.next_frame().await {
                // Echo the received frames back to the client
                let _ = ws.send(frame).await;
            }
        }
    });

    response
}

#[tokio::main]
async fn main() {
    let app = Router::new()
        .route("/ws", get(websocket_handler));

    let listener = tokio::net::TcpListener::bind("0.0.0.0:3000").await.unwrap();
    axum::serve(listener, app).await.unwrap();
}

To use the Axum integration, add this to your Cargo.toml:

[dependencies]
yawc = { version = "0.2", features = ["axum"] }
axum = "0.7"

Advanced Features

Compression Control

Fine-tune compression settings for optimal performance:

use yawc::{Options, DeflateOptions, CompressionLevel};

let options = Options::default()
    .with_compression_level(CompressionLevel::default())
    .server_no_context_takeover()  // Optimize memory usage
    .with_client_max_window_bits(11);  // Control compression window (requires zlib feature)

Split Streams

Split the WebSocket for independent reading and writing:

let (mut write, mut read) = ws.split();

// Read and write concurrently
tokio::join!(
    async move { while let Some(frame) = read.next().await { /* ... */ } },
    async move { write.send(FrameView::text("Hello")).await? }
);

Custom Frame Handling

Process frames manually when needed:

match frame.opcode {
    OpCode::Ping => {
        // Automatic pong responses
        println!("Received ping");
    }
    OpCode::Close => {
        // Handle close frames
        let code = u16::from_be_bytes(frame.payload[0..2].try_into()?);
        println!("Connection closing with code: {}", code);
    }
    _ => { /* Handle data frames */ }
}

Performance Considerations

Uses zero-copy frame processing where possible
Efficient handling of fragmented messages
Configurable compression levels for bandwidth/CPU tradeoffs
Memory-efficient compression contexts

Safety and Security

Maximum payload size limits (configurable, default 2MB)
Automatic masking of client frames
Optional UTF-8 validation for text frames
Protection against memory exhaustion attacks
TLS support for secure connections

Motivation

While several WebSocket libraries exist for Rust's async ecosystem, none of them provide the full combination of features needed for high-performance, production-ready applications while maintaining a simple API. Existing libraries lack proper full-duplex stream support, zero-copy operations, or compression capabilities - or implement these features with complex, difficult-to-use APIs. Additionally, most libraries require significant codebase changes to support WebAssembly, whereas yawc maintains compatibility across platforms without forcing developers to rewrite their code. This library aims to provide all these critical features with an ergonomic interface that makes WebSocket development straightforward and efficient across native and WASM environments.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes, please open an issue first to discuss what you would like to change.

License

This project is licensed under the GNU Lesser General Public License v3.0 (LGPL-3.0). Under the terms of this license, you may use, modify, and distribute the code as part of a larger work without requiring the entire work to be licensed under the LGPL. However, any modifications to the library itself must be made available under the LGPL. For more details, see (LICENSE or https://www.gnu.org/licenses/lgpl-3.0.en.html)

About us

Infinite Field is a high-frequency trading firm. We build ultra-low-latency systems for execution at scale. Performance is everything.

We prioritize practical solutions over theory. If something works and delivers results, that’s what matters. Performance is always the goal, and every piece of code is written with efficiency and longevity in mind.

If you specialize in performance-critical software, understand systems down to the bare metal, and know how to optimize x64 assembly, we’d love to hear from you.

Explore career opportunities

Acknowledgments

Special thanks to:

The Tungstenite project for inspiration on close codes
The fastwebsockets project which served as inspiration and source for many implementations
The Autobahn test suite for protocol compliance verification

yawc 0.2.1