HTTP/2 Frame Parser

A dependency-free Java 17 library for parsing HTTP/2 frames and decoding HPACK header blocks. It supports every frame type defined by RFC 9113, preserves unknown extension frames, validates the HTTP/2 client preface, and implements stateful RFC 7541 HPACK decoding, frame-aware header assembly, and offline snapshot and restore support. Decoded blocks provide cached pseudo-fields and case-insensitive lookup for arbitrary header names. HPACK decoding is capture-analysis friendly by default: unavailable dynamic-table references are skipped and reported so processing can continue when a capture starts mid-connection. Parser and HPACK resource defaults are also sized for captures that missed the peer's SETTINGS frames.

The single JAR exposes frame APIs under dev.darcro.http2.frame and HPACK APIs under dev.darcro.http2.hpack.

import dev.darcro.http2.frame.DataFrame;
import dev.darcro.http2.frame.Http2Frame;
import dev.darcro.http2.frame.Http2FrameParser;

Http2Frame frame = new Http2FrameParser().parse(wireBytes);

if (frame instanceof DataFrame data) {
    byte[] content = data.data().toByteArray();
}

Documentation

• Simple usage guide — installation, frame parsing, preface validation, and basic HPACK decoding.
• Advanced configuration guide — limits, negotiated settings, state management, zero-copy behavior, and error handling.
• Developer guide — architecture, protocol invariants, tests, maintenance workflows, and extension points.

Requirements

• Java 17 or newer
• Maven 3.8 or newer for building from source

Build and run the complete test suite with:

mvn clean verify

The project has no runtime dependencies.

GitHub Packages

Tagged releases are published to GitHub Packages by the Maven workflow. A tag named v0.1.0 publishes artifact version 0.1.0.

Consumers can add the package repository and dependency:

<repository>
    <id>github</id>
    <url>https://maven.pkg.github.com/darcro/http2</url>
</repository>

<dependency>
    <groupId>dev.darcro.http2</groupId>
    <artifactId>http2-parser</artifactId>
    <version>0.1.0</version>
</dependency>

GitHub Packages may require Maven credentials depending on package visibility.