Crate quiche

🥧 Savoury implementation of the QUIC transport protocol and HTTP/3.

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.

Connection setup

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)?;

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)?;
}

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);
        }
    }
}

HTTP/3

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.

Modules

h3	HTTP/3 wire protocol and QPACK implementation.

Structs

Config	Stores configuration shared between multiple connections.
Connection	A QUIC connection.
Header	A QUIC packet's header.
Stats	Statistics about the connection.
StreamIter	An iterator over QUIC streams.

Enums

Error	A QUIC error.
Shutdown	The stream's side to shutdown.
Type	QUIC packet type.

Constants

MAX_CONN_ID_LEN	The maximum length of a connection ID.
MIN_CLIENT_INITIAL_LEN	The minimum length of Initial packets sent by a client.
PROTOCOL_VERSION	The current QUIC wire version.

Functions

accept	Creates a new server-side connection.
connect	Creates a new client-side connection.
negotiate_version	Writes a version negotiation packet.
retry	Writes a stateless retry packet.
version_is_supported	Returns true if the given protocol version is supported.

Type Definitions

Result

A specialized Result type for quiche operations.