HTTP/3 (RFC 9114) and QPACK (RFC 9204) for Kotlin/Native over com.netonstream:quic. The first version replicates h3 0.0.8 (and h3-quinn for the QUIC adapter). Artifact com.netonstream:http3, package neton.http.h3. Common HTTP types (Request, Response, HeaderMap, ...) come from com.netonstream:http.

This repository was split out of http on 2026-09-29, with its history. Specification, deliberate differences from the reference (marked ⚖️) and the implementation record: SPEC.md.

Release coordinate: com.netonstream:http3:0.3.0, built against com.netonstream:http:0.3.0 and com.netonstream:quic:0.3.0 (tests: quic-testkit:0.3.0). 0.3.0 adds a request-head time limit for the server (H3_REQUEST_REJECTED both ways) and moves to http 0.3.0 and quic 0.3.0. 0.2.0 added requests over 0-RTT and RequestStream.isEarlyData(). Kotlin 2.4.20 (the build refuses anything lower), native targets shared by http and quic (no 32-bit Android).

• h3's tests ported (frames, QPACK static + literals with a zero-capacity dynamic table, connection and request tests), run on an in-memory QUIC double, on neton.quic with the TLS test double, and on neton.quic with real TLS 1.3.
• Interop over real TLS 1.3 in both directions with h3 0.0.8 + h3-quinn (its own examples and a peer on the same crates: GET, POST, 16 MiB bodies, 150 requests per connection, trailers, GOAWAY, close) and with aioquic 1.2.0 (GREASE on).
• h3spec 0.1.13: 49 / 49, including the five items the reference skips.
• ⚖️ GOAWAY rejects stream IDs greater than or equal to the GOAWAY ID (RFC 9114 §5.2; the reference uses >); the connection's one GREASE frame on a request stream follows the first head instead of preceding FIN (aioquic needs it).
• ⚖️ A server-side time limit for the request head (Builder.requestHeaderTimeout, default 10 s, 0 = none): a request stream whose HEADERS frame has not arrived in time is rejected both ways with H3_REQUEST_REJECTED.
• Not supported: server push, WebTransport, HTTP Datagrams, dynamic QPACK.
• Not yet: quiche / curl --http3 interop, loss and reordering runs over real TLS, performance comparison.

HTTP/3 (neton.http.h3) runs on a neton.quic connection whose TLS handshake negotiated ALPN "h3". The TLS configuration is neton.quic.proto's TLS 1.3 session (OpenSSL): the server gives its certificate chain and key, the client gives its trust anchors explicitly (there is no system trust store), and both offer ALPN_H3:

// Server
val tls = TlsServerConfig(Certificates.pem(chainPem), PrivateKey.pem(keyPem), alpnProtocols = listOf(ALPN_H3))
val endpoint = Endpoint.create(EndpointConfig.default(), ServerConfig.withCrypto(tls), bindUdp(address))
while (true) {
    val quic = endpoint.accept()?.await() ?: break
    launch {
        val conn = neton.http.h3.server.newConnection(quic.asH3())
        while (true) {
            val (request, stream) = conn.accept()?.resolveRequest() ?: break
            stream.use {   // close() releases the QUIC stream, as dropping it does in h3
                it.sendResponse(Response.builder().status(200).body(Unit))
                it.sendData(Bytes.copyOf("hello".encodeToByteArray()))
                it.finish()
            }
        }
    }
}

// Client
val tls = TlsClientConfig(trustAnchors = Certificates.pem(caPem), alpnProtocols = listOf(ALPN_H3))
val quic = clientEndpoint.connectWith(ClientConfig(tls), serverAddress, "example.com").await()
val (driver, sender) = neton.http.h3.client.newClient(quic.asH3())
launch { driver.run() }
val stream = sender.sendRequest(Request.get("https://example.com/").body(Unit))
stream.finish()
val response = stream.recvResponse()
while (true) stream.recvData() ?: break

Close each server RequestStream when done with it (use { }): it is h3's Drop. Until then a request whose body was not read to its end keeps its QUIC stream, and with it one of the client's stream credits (100 concurrent bidirectional streams by default), so a server that never closes them stops accepting requests on that connection.

A server certificate that does not chain to the client's trust anchors or does not match the server name fails the handshake, as does a peer without "h3". The KDoc of neton.http.h3.quic.ALPN_H3 has the details.

./gradlew :http3:macosArm64Test          # or linuxX64Test (NETON_IO_DRIVER=epoll|iouring)

Interop peers and scripts (h3 examples, an h3 peer, aioquic, h3spec): http3-interop/ (not published).