quiche is an implementation of the QUIC transport protocol and HTTP/3 as specified by the IETF. It provides a low level API for processing QUIC packets and handling connection state. The application is responsible for providing I/O (e.g. sockets handling) as well as an event loop with support for timers.

Note that it is very experimental and unstable software, and many features are still in development. Refer to the Status section to see what is currently implemented.

A live QUIC server based on quiche is available at https://quic.tech:4433/ to be used for experimentation.

For more information on how quiche came about and some insights into its design you can read a post on Cloudflare's (where this library is used in production) blog that goes into some more detail.

Getting Started

Connection setup

The first step in establishing a QUIC connection using quiche is creating a configuration object:

let config = quiche::Config::new(quiche::VERSION_DRAFT18).unwrap();

This is shared among multiple connections and can be used to configure a QUIC endpoint.

On the client-side the connect() utility function can be used to create a new connection, while accept() is for servers:

// Client connection.
let conn = quiche::connect(Some(&server_name), &scid, &mut config).unwrap();

// Server connection.
let conn = quiche::accept(&scid, None, &mut config).unwrap();

Handling incoming packets

Using the connection's recv() method the application can process incoming packets that belong to that connection from the network:

loop {
    let read = socket.recv(&mut buf).unwrap();

    let read = match conn.recv(&mut buf[..read]) {
        Ok(v) => v,

        Err(quiche::Error::Done) => {
            // Done reading.
            break;
        },

        Err(e) => {
            // An error occurred, handle it.
            break;
        },
    };
}

Generating outgoing packets

Outgoing packet are generated using the connection's send() method instead:

loop {
    let write = match conn.send(&mut out) {
        Ok(v) => v,

        Err(quiche::Error::Done) => {
            // Done writing.
            break;
        },

        Err(e) => {
            // An error occurred, handle it.
            break;
        },
    };

    socket.send(&out[..write]).unwrap();
}

When packets are sent, the application is responsible for maintaining a timer to react to time-based connection events. The timer expiration can be obtained using the connection's timeout() method.

let timeout = conn.timeout();

The application is responsible for providing a timer implementation, which can be specific to the operating system or networking framework used. When a timer expires, the connection's on_timeout() method should be called, after which additional packets might need to be sent on the network:

// Timeout expired, handle it.
conn.on_timeout();

// Send more packets as needed after timeout.
loop {
    let write = match conn.send(&mut out) {
        Ok(v) => v,

        Err(quiche::Error::Done) => {
            // Done writing.
            break;
        },

        Err(e) => {
            // An error occurred, handle it.
            break;
        },
    };

    socket.send(&out[..write]).unwrap();
}

Sending and receiving stream data

After some back and forth, the connection will complete its handshake and will be ready for sending or receiving application data.

Data can be sent on a stream by using the stream_send() method:

if conn.is_established() {
    // Handshake completed, send some data on stream 0.
    conn.stream_send(0, b"hello", true).unwrap();
}

The application can check whether there are any readable streams by using the connection's readable() method, which returns an iterator over all the streams that have outstanding data to read.

The stream_recv() method can then be used to retrieve the application data from the readable stream:

if conn.is_established() {
    // Iterate over readable streams.
    let streams: Vec<u64> = conn.readable().collect();

    for stream_id in streams {
        // Stream is readable, read until there's no more data.
        while let Ok((read, fin)) = conn.stream_recv(stream_id, &mut buf) {
            println!("Got {} bytes on stream {}", read, stream_id);
        }
    }
}

Have a look at the examples/ directory for more complete examples on how to use the quiche API, including examples on how to use quiche in C/C++ applications (see below for more information).

Calling quiche from C/C++

quiche exposes a thin C API on top of the Rust API that can be used to more easily integrate quiche into C/C++ applications (as well as in other languages that allow calling C APIs via some form of FFI). The C API follows the same design of the Rust one, modulo the constraints imposed by the C language itself.

When running cargo build, a static library called libquiche.a will be built automatically alongside the Rust one. This is fully stand-alone and can be linked directly into C/C++ applications.

Building

The first step after cloning the git repo is updating the git submodules:

 $ git submodule update --init

You can now build quiche using cargo:

 $ cargo build --examples

As well as run its tests:

 $ cargo test

Note that BoringSSL, used to implement QUIC's cryptographic handshake based on TLS, needs to be built and linked to quiche. This is done automatically when building quiche using cargo, but requires the cmake and go commands to be available during the build process.

In alternative you can use your own custom build of BoringSSL by configuring the BoringSSL directory with the QUICHE_BSSL_PATH environment variable:

 $ QUICHE_BSSL_PATH="/path/to/boringssl" cargo build --examples

Copyright

Copyright (C) 2018, Cloudflare, Inc.

Copyright (C) 2018, Alessandro Ghedini

See COPYING for the license.