Peer-to-peer DHTTP/3 transport over QUIC, implemented in Rust.

• Peer-to-Peer: Extends HTTP3(RFC9114) to DHTTP/3, allowing both sides of the connection to initiate and handle HTTP3 requests (achieved by disabling server push).
• Asynchronous I/O: Built on the Rust asynchronous ecosystem, providing high-performance I/O processing capabilities.
• Zero-Copy: Achieves full-link zero-copy from the QUIC layer to the application layer.
• Multipath QUIC: Integrates the dquic implementation, featuring efficient transmission, robust authentication capabilities, and high extensibility.
• Hyper / Tower Compatibility (feature hyper, enabled by default): Provides a single-file h3x::hyper facade for hyper-facing integrations. The facade exposes TowerService, HyperService, request execution errors, upgrade/takeover helpers, Extended CONNECT helpers, and protocol extension helpers. Lower-level hyper adapters also remain available from their semantic owners: dhttp::message::hyper, endpoint::hyper, qpack::field::hyper, and extended_connect::hyper.
• RPC / IPC (features rpc and ipc, experimental): Optional remoc integration for remote trait calls (RTC) over QUIC connections, with optional IPC transport support. Consumers must select exactly one remoc/default-codec-* feature; h3x tests use the bincode codec through a dev-dependency.
• Extended CONNECT: Supports Extended CONNECT (RFC9220) for protocol tunneling over HTTP/3.
• Future Extensions: Plans to support extensions such as WebTransport over HTTP/3 (Draft).

Examples

⚠️ Currently, h3x is in the early stages of development, and the API may undergo significant changes.

h3x includes dquic as its built-in QUIC backend (feature dquic, enabled by default). Wrap a QuicEndpoint in an H3Endpoint to get HTTP/3 client and server semantics on top of QUIC.

use bytes::Bytes;
use h3x::{dquic::QuicEndpoint, endpoint::H3Endpoint};
use http_body_util::{BodyExt, Empty};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let endpoint = H3Endpoint::new(QuicEndpoint::new().await);

    let connection = endpoint.connect("example.com:4433".parse()?).await?;
    let request = http::Request::get("https://example.com:4433/hello")
        .body(Empty::<Bytes>::new())?;
    let response = connection.execute_hyper_request(request).await?;
    assert_eq!(response.status(), http::StatusCode::OK);
    let body = response.into_body().collect().await?.to_bytes();
    println!("{}", String::from_utf8_lossy(&body));
    Ok(())
}

use std::sync::Arc;
use axum::{Router as AxumRouter, routing::get};
use h3x::{
    dquic::{Identity, Name, QuicEndpoint},
    endpoint::H3Endpoint,
    hyper::TowerService,
};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let identity = Arc::new(Identity {
        name: "localhost".parse()?,
        certs: todo!("load your certificate chain"),
        key: todo!("load your private key"),
        ocsp: Arc::new(None),
    });
    let endpoint = H3Endpoint::new(
        QuicEndpoint::builder()
            .identity(identity)
            .bind(Arc::new(vec!["127.0.0.1:4433".parse()?]))
            .build().await,
    );

    let router = AxumRouter::new().route("/hello", get(|| async { "Hello, World!" }));
    let service = TowerService(router.into_service());
    endpoint.listen(service).await?;
    Ok(())
}

Hyper / Tower Integration

h3x provides adapters to bridge the Tower / hyper service ecosystem into DHTTP/3, available under the hyper feature (enabled by default).

• TowerService(S) — wraps a tower::Service (e.g. an axum Router)
• HyperService(S) — wraps a hyper::service::Service

API note: h3x cannot construct hyper's internal types directly, so the h3x::hyper module provides its own alternatives:

• h3x::hyper::upgrade — stream takeover for Extended CONNECT tunnels (instead of hyper::upgrade)
• h3x::hyper::ext::Protocol — protocol indication in CONNECT requests (instead of hyper::ext::Protocol)

use std::sync::Arc;
use axum::{Router as AxumRouter, routing::get};
use h3x::{
    dquic::{Identity, Name, QuicEndpoint},
    endpoint::H3Endpoint,
    hyper::TowerService,
};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let router = AxumRouter::new()
        .route("/hello", get(|| async { "Hello from DHTTP/3!" }));
    let service = TowerService(router.into_service());

    let identity = Arc::new(Identity {
        name: "localhost".parse()?,
        certs: todo!("load your certificate chain"),
        key: todo!("load your private key"),
        ocsp: Arc::new(None),
    });
    H3Endpoint::new(
        QuicEndpoint::builder()
            .identity(identity)
            .bind(Arc::new(vec!["127.0.0.1:4433".parse()?]))
            .build().await,
    )
    .listen(service)
    .await?;
    Ok(())
}

use bytes::Bytes;
use h3x::{dquic::QuicEndpoint, endpoint::H3Endpoint};
use http_body_util::{BodyExt, Empty};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let endpoint = H3Endpoint::new(QuicEndpoint::new().await);

    let connection = endpoint.connect("example.com:4433".parse()?).await?;
    let request = http::Request::get("https://example.com:4433/hello")
        .body(Empty::<Bytes>::new())?;
    let response = connection.execute_hyper_request(request).await?;
    assert_eq!(response.status(), http::StatusCode::OK);
    let body = response.into_body().collect().await?.to_bytes();
    println!("{}", String::from_utf8_lossy(&body));
    Ok(())
}

Testing and Coverage

h3x uses one canonical test entrypoint for local development and CI:

cargo test --all-features --all-targets

All feature-gated paths, including rpc, ipc, webtransport, dquic, and hyper, must compile and test through that command. The dev-dependency on remoc selects the bincode default codec for tests so rpc/ipc can compile under --all-features.

Documentation is checked with warnings denied for all non-rpc/ipc features:

RUSTDOCFLAGS="-D warnings" cargo doc --no-deps --no-default-features --features dquic,hyper,serde,testing,webtransport

Coverage uses cargo-llvm-cov directly:

cargo llvm-cov clean
mkdir -p target/llvm-cov
cargo llvm-cov \
  --all-features \
  --all-targets \
  --summary-only \
  --json \
  --output-path target/llvm-cov/coverage.json \
  --fail-under-lines 62 \
  --fail-under-functions 56 \
  --fail-under-regions 64
cargo llvm-cov report --lcov --output-path target/llvm-cov/lcov.info
cargo llvm-cov report --html --output-dir target/llvm-cov

The HTML report entrypoint is:

target/llvm-cov/html/index.html

The initial coverage gate preserves the current baseline. Raise the gate only in commits that add meaningful tests or remove dead code.