tokio_quiche/quic/

mod.rs

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//! `async`-ified QUIC connections powered by [quiche].
//!
//! Hooking up a [quiche::Connection] to [tokio]'s executor and IO primitives
//! requires an [`ApplicationOverQuic`] to control the connection. The
//! application exposes a small number of callbacks which are executed whenever
//! there is work to do with the connection.
//!
//! The primary entrypoints to set up a connection are [`listen`][listen] for
//! servers and [`connect`] for clients.
//! [`listen_with_capabilities`](crate::listen_with_capabilities)
//! and [`connect_with_config`] exist for scenarios that require more in-depth
//! configuration. Lastly, the [`raw`] submodule allows users to take full
//! control over connection creation and its ingress path.
//!
//! # QUIC Connection Internals
//!
//! ![QUIC Worker Setup](https://github.com/cloudflare/quiche/blob/master/tokio-quiche/docs/worker.png?raw=true)
//!
//! *Note: Internal details are subject to change between minor versions.*
//!
//! tokio-quiche conceptually separates a network socket into a `recv` half and
//! a `send` half. The `recv` half can only sensibly be used by one async task
//! at a time, while many tasks can `send` packets on the socket concurrently.
//! Thus, we spawn a dedicated `InboundPacketRouter` task for each socket which
//! becomes the sole owner of the socket's `recv` half. It decodes the QUIC
//! header in each packet, looks up the destination connection ID (DCID), and
//! forwards the packet to the connection's `IoWorker` task.
//!
//! If the packet initiates a new connection, it is passed to an
//! `InitialPacketHandler` with logic for either the client- or server-side
//! connection setup. The purple `ConnectionAcceptor` depicted above is the
//! server-side implementation. It optionally validates the client's IP
//! address with a `RETRY` packet before packaging the nascent connection into
//! an [`InitialQuicConnection`][iqc] and sending it to the
//! [`QuicConnectionStream`] returned by [`listen`][listen].
//!
//! At this point the caller of [`listen`][listen] has control of the
//! [`InitialQuicConnection`][iqc] (`IQC`). Now an `IoWorker` task needs to be
//! spawned to continue driving the connection. This is possible with
//! `IQC::handshake` or `IQC::start` (see the [`InitialQuicConnection`][iqc]
//! docs). Client-side connections use the same infrastructure (except for the
//! `InitialPacketHandler`), but [`connect`] immediately consumes the
//! [`QuicConnectionStream`] and calls `IQC::start`.
//!
//! `IoWorker` is responsible for feeding inbound packets into the underlying
//! [`quiche::Connection`], executing the [`ApplicationOverQuic`] callbacks, and
//! flushing outbound packets to the network via the socket's shared `send`
//! half. It loops through these operations in the order shown above, yielding
//! only when sending packets and on `wait_for_data` calls. New inbound packets
//! or a timeout can also restart the loop while `wait_for_data` is pending.
//! This continues until the connection is closed or the [`ApplicationOverQuic`]
//! returns an error.
//!
//! [listen]: crate::listen
//! [iqc]: crate::InitialQuicConnection

use std::sync::Arc;
use std::time::Duration;

use datagram_socket::DatagramSocketRecv;
use datagram_socket::DatagramSocketSend;
use foundations::telemetry::log;
use qlog::writer::make_qlog_writer_from_path;
use qlog::writer::qlog_file_name;

use crate::http3::settings::Http3Settings;
use crate::metrics::DefaultMetrics;
use crate::metrics::Metrics;
use crate::settings::Config;
use crate::socket::QuicListener;
use crate::socket::Socket;
use crate::ClientH3Controller;
use crate::ClientH3Driver;
use crate::ConnectionParams;
use crate::QuicConnectionStream;
use crate::QuicResult;
use crate::QuicResultExt;

mod addr_validation_token;
pub(crate) mod connection;
mod dscp;
mod hooks;
mod io;
pub mod raw;
mod router;

use self::connection::ApplicationOverQuic;
use self::connection::ConnectionIdGenerator as _;
use self::connection::QuicConnection;
use self::router::acceptor::ConnectionAcceptor;
use self::router::acceptor::ConnectionAcceptorConfig;
use self::router::connector::ClientConnector;
use self::router::InboundPacketRouter;

pub use self::connection::ConnectionShutdownBehaviour;
pub use self::connection::HandshakeError;
pub use self::connection::HandshakeInfo;
pub use self::connection::Incoming;
pub use self::connection::QuicCommand;
pub use self::connection::QuicConnectionStats;
pub use self::connection::SimpleConnectionIdGenerator;
pub use self::dscp::Dscp;
pub use self::dscp::DscpHandle;
pub use self::hooks::ConnectionHook;

/// Alias of [quiche::Connection] used internally by the crate.
pub type QuicheConnection = quiche::Connection<crate::buf_factory::BufFactory>;

/// Connects to an HTTP/3 server using `socket` and the default client
/// configuration.
///
/// This function always uses the [`ApplicationOverQuic`] provided in
/// [`http3::driver`](crate::http3::driver) and returns a corresponding
/// [ClientH3Controller]. To specify a different implementation or customize the
/// configuration, use [`connect_with_config`].
///
/// # Note
/// tokio-quiche currently only supports one client connection per socket.
/// Sharing a socket among multiple connections will lead to lost packets as
/// both connections try to read from the shared socket.
pub async fn connect<Tx, Rx, S>(
    socket: S, host: Option<&str>,
) -> QuicResult<(QuicConnection, ClientH3Controller)>
where
    Tx: DatagramSocketSend + Send + 'static,
    Rx: DatagramSocketRecv + Unpin + 'static,
    S: TryInto<Socket<Tx, Rx>>,
    S::Error: std::error::Error + Send + Sync + 'static,
{
    // Don't apply_max_capabilities(): some NICs don't support GSO
    let socket: Socket<Tx, Rx> = socket.try_into()?;

    let (h3_driver, h3_controller) =
        ClientH3Driver::new(Http3Settings::default());
    let mut params = ConnectionParams::default();
    params.settings.max_idle_timeout = Some(Duration::from_secs(30));

    Ok((
        connect_with_config(socket, host, &params, h3_driver).await?,
        h3_controller,
    ))
}

/// Connects to a QUIC server using `socket` and the provided
/// [`ApplicationOverQuic`].
///
/// When the future resolves, the connection has completed its handshake and
/// `app` is running in the worker task. In case the handshake failed, we close
/// the connection automatically and the future will resolve with an error.
///
/// # Note
/// tokio-quiche currently only supports one client connection per socket.
/// Sharing a socket among multiple connections will lead to lost packets as
/// both connections try to read from the shared socket.
pub async fn connect_with_config<Tx, Rx, App>(
    socket: Socket<Tx, Rx>, host: Option<&str>, params: &ConnectionParams<'_>,
    app: App,
) -> QuicResult<QuicConnection>
where
    Tx: DatagramSocketSend + Send + 'static,
    Rx: DatagramSocketRecv + Unpin + 'static,
    App: ApplicationOverQuic,
{
    let mut client_config = Config::new(params, socket.capabilities)?;
    let scid = SimpleConnectionIdGenerator.new_connection_id();

    #[cfg(feature = "custom-client-dcid")]
    let mut quiche_conn = if let Some(dcid) = &params.dcid {
        quiche::connect_with_dcid_and_buffer_factory(
            host,
            &scid,
            dcid,
            socket.local_addr,
            socket.peer_addr,
            client_config.as_mut(),
        )?
    } else {
        quiche::connect_with_buffer_factory(
            host,
            &scid,
            socket.local_addr,
            socket.peer_addr,
            client_config.as_mut(),
        )?
    };

    #[cfg(not(feature = "custom-client-dcid"))]
    let mut quiche_conn = quiche::connect_with_buffer_factory(
        host,
        &scid,
        socket.local_addr,
        socket.peer_addr,
        client_config.as_mut(),
    )?;

    #[cfg(feature = "custom-client-dcid")]
    log::info!("created unestablished quiche::Connection"; "scid" => ?scid, "provided_dcid" => ?params.dcid);
    #[cfg(not(feature = "custom-client-dcid"))]
    log::info!("created unestablished quiche::Connection"; "scid" => ?scid);

    if let Some(session) = &params.session {
        quiche_conn.set_session(session).map_err(|error| {
            log::error!("application provided an invalid session"; "error"=>?error);
            quiche::Error::CryptoFail
        })?;
    }

    // Set the qlog writer here instead of in the `ClientConnector` to avoid
    // missing logs from early in the connection
    if let Some(qlog_dir) = &client_config.qlog_dir {
        log::info!("setting up qlogs"; "qlog_dir"=>qlog_dir);
        let id = format!("{:?}", scid);
        let path = std::path::Path::new(qlog_dir)
            .join(qlog_file_name(&id, client_config.qlog_compression));
        if let Ok(writer) =
            make_qlog_writer_from_path(&path, client_config.qlog_compression)
        {
            quiche_conn.set_qlog(
                writer,
                "tokio-quiche qlog".to_string(),
                format!("tokio-quiche qlog id={id}"),
            );
        }
    }

    // Set the keylog file here for the same reason
    if let Some(keylog_file) = &client_config.keylog_file {
        log::info!("setting up keylog file");
        if let Ok(keylog_clone) = keylog_file.try_clone() {
            quiche_conn.set_keylog(Box::new(keylog_clone));
        }
    }

    let socket_tx = Arc::new(socket.send);
    let socket_rx = socket.recv;

    let (router, mut quic_connection_stream) = InboundPacketRouter::new(
        client_config,
        Arc::clone(&socket_tx),
        socket_rx,
        socket.local_addr,
        ClientConnector::new(socket_tx, Box::new(quiche_conn)),
        DefaultMetrics,
    );

    // drive the packet router:
    tokio::spawn(async move {
        match router.await {
            Ok(()) => {
                log::debug!("incoming packet router finished");
            },
            Err(error) => {
                log::error!("incoming packet router failed"; "error"=>error);
            },
        }
    });

    Ok(quic_connection_stream
        .recv()
        .await
        .ok_or("unable to establish connection")??
        .start(app))
}

pub(crate) fn start_listener<M>(
    socket: QuicListener, params: &ConnectionParams, metrics: M,
) -> std::io::Result<QuicConnectionStream<M>>
where
    M: Metrics,
{
    #[cfg(unix)]
    assert!(
        datagram_socket::is_nonblocking(&socket).unwrap_or_default(),
        "O_NONBLOCK should be set for the listening socket"
    );

    let config = Config::new(params, socket.capabilities).into_io()?;

    let local_addr = socket.socket.local_addr()?;
    let socket_tx = Arc::new(socket.socket);
    let socket_rx = Arc::clone(&socket_tx);

    let acceptor = ConnectionAcceptor::new(
        ConnectionAcceptorConfig {
            disable_client_ip_validation: config.disable_client_ip_validation,
            enable_per_connection_dscp: params.enable_per_connection_dscp,
            qlog_dir: config.qlog_dir.clone(),
            qlog_compression: config.qlog_compression,
            keylog_file: config
                .keylog_file
                .as_ref()
                .and_then(|f| f.try_clone().ok()),
            #[cfg(target_os = "linux")]
            with_pktinfo: if local_addr.is_ipv4() {
                config.has_ippktinfo
            } else {
                config.has_ipv6pktinfo
            },
        },
        Arc::clone(&socket_tx),
        Default::default(),
        socket.cid_generator,
        metrics.clone(),
    );

    let (socket_driver, accept_stream) = InboundPacketRouter::new(
        config,
        socket_tx,
        socket_rx,
        local_addr,
        acceptor,
        metrics.clone(),
    );

    crate::metrics::tokio_task::spawn("quic_udp_listener", metrics, async move {
        match socket_driver.await {
            Ok(()) => {
                log::trace!("incoming packet router finished");
            },
            Err(error) => {
                log::error!("incoming packet router failed"; "error"=>error);
            },
        }
    });
    Ok(QuicConnectionStream::new(accept_stream))
}