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.

A live QUIC server based on quiche is available at https://quic.tech:4433/, and an HTTP/3 one at https://quic.tech:8443/, that can 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.

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

let config = quiche::Config::new(quiche::PROTOCOL_VERSION)?;

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)?;

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

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;
        },
    };
}

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();
}

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)?;
}

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.
    for stream_id in conn.readable() {
        // 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);
        }
    }
}

The quiche HTTP/3 module provides a high level API for sending and receiving HTTP requests and responses on top of the QUIC transport protocol.

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).

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.

quiche requires Rust 1.39 or later to build. The latest stable Rust release can be installed using rustup.

Once the Rust build environment is setup, the quiche source code can be fetched using git:

 $ git clone --recursive https://github.com/cloudflare/quiche

and then built using cargo:

 $ cargo build --examples

cargo can also be used to run the testsuite:

 $ cargo test

Note that BoringSSL, which is 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, go and perl commands to be available during the build process. On Windows you also need NASM. The official BoringSSL documentation has more details.

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

To build quiche for Android, you need the following:

• Install the Android NDK (13b or higher), using Android Studio or directly.
• Set ANDROID_NDK_HOME environment variable to NDK path, e.g.

 $ export ANDROID_NDK_HOME=/usr/local/share/android-ndk

• Install the Rust toolchain for Android architectures needed:

 $ rustup target add aarch64-linux-android arm-linux-androideabi armv7-linux-androideabi i686-linux-android x86_64-linux-android

Note that the minimum API level is 21 for all target architectures.

Depending on the NDK version used, you can take one of the following procedures:

For NDK version 19 or higher (21 recommended), you can build in a simpler way using cargo-ndk. You need to install cargo-ndk first.

 $ cargo install cargo-ndk

You can build the quiche library using the following procedure. Note that --target and --android-platform are mandatory.

 $ cargo ndk --target aarch64-linux-android --android-platform 21 -- build

See build_android_ndk19.sh for more information.

Note that building with NDK version 18 appears to be broken.

If you need to use NDK version < 18 (gcc), you can build quiche in the following way.

To prepare the cross-compiling toolchain, run the following command:

 $ tools/setup_android.sh

It will create a standalone toolchain for arm64/arm/x86 architectures under the $TOOLCHAIN_DIR/arch directory. If you didn't set TOOLCHAIN_DIR environment variable, the current directory will be used.

After it run successfully, run the following script to build libquiche:

 $ tools/build_android.sh --features ndk-old-gcc

It will build binaries for aarch64, armv7 and i686. You can pass parameters to this script for cargo build. For example if you want to build a release binary with verbose logs, do the following:

 $ tools/build_android.sh --features ndk-old-gcc --release -vv

To build quiche for iOS, you need the following:

• Install Xcode command-line tools. You can install them with Xcode or with the following command:

 $ xcode-select --install

• Install the Rust toolchain for iOS architectures:

 $ rustup target add aarch64-apple-ios armv7-apple-ios armv7s-apple-ios x86_64-apple-ios i386-apple-ios

• Install cargo-lipo:

 $ cargo install cargo-lipo

To build libquiche, run the following command:

 $ cargo lipo

or

 $ cargo lipo --release

Copyright (C) 2018-2019, Cloudflare, Inc.

See COPYING for the license.