Hpack Laravel Package

Getting Started

amphp/hpack is a low-level library for HTTP/2 header compression using HPACK (RFC 7541). It's primarily intended for use by HTTP/2 client/server implementations (e.g., amphp/http-server, amphp/http-client). To start:

• Install via composer require amphp/hpack
• Examine src/ for the two core classes: StaticTable (immutable header table) and DynamicTable (mutable, per-connection)
• Use Encoder and Decoder classes to compress/decompress header sets
• Minimal example:

  use function Amp\Http\Server\Encoder;
  use function Amp\Http\Server\Decoder;
  
  $encoder = new Encoder();
  $decoder = new Decoder();
  
  $headers = [[':method', 'GET'], [':path', '/']];  
  $encoded = $encoder->encode($headers); // returns binary string  
  $decoded = $decoder->decode($encoded); // returns original headers array  
  

Check examples/ for basic round-trip use and consult unit tests (tests/) for edge cases.

Implementation Patterns

• Stateful connections: Reuse Encoder/Decoder instances per-connection (HPACK is stateful due to dynamic table).
• Stream-agnostic: Works with raw binary strings—ideal for integration into async I/O (e.g., amphp/socket, ReactPHP).
• Integration with HTTP/2 stacks: Typically used upstream of framing logic (e.g., after header generation but before writing to the HTTP/2 data frame).
• Memory-conscious configs: Control dynamic table size via Decoder/Encoder constructors (defaults to 4096 bytes; reduce for memory-constrained environments).
• Testing: Pair with amphp/http2 to validate compliance via unit tests (e.g., RFC test vectors in tests/RfcTest.php).

Gotchas and Tips

• Not a standalone HTTP library: This is not a high-level tool—it requires careful orchestration with HTTP/2 frame layers. Misusing it (e.g., resetting dynamic table incorrectly) breaks compliance.
• Dynamic table size updates (RFC 7541 § 6.3): Encoder emits DynamicTableSizeUpdate frames implicitly, but Decoder must be fed all table size change notifications in order. Ensure your HTTP/2 frame handler forwards them correctly.
• Binary-safe decoding: decode() throws Amp\Http\Server\HttpException on malformed input—always wrap in try/catch. Errors often indicate out-of-sync dynamic tables.
• Performance: HPACK compression is CPU-light but allocation-heavy; reuse objects and avoid per-request instantiation in high-throughput services.
• Extensibility: Extend Encoder/Decoder to inject custom header handling (e.g., logging, sensitive header redaction), but do not modify static/dynamic table internals.
• Debugging: Enable HPACK_DEBUG (if compiled with debug symbols) or log raw binary before/after encoding—compare with Wireshark captures for discrepancies.