Detailed Description

HPACK header compression for HTTP/2 (RFC 7541).

HPACK encodes an HTTP header list into a compact byte block and back. It combines a fixed static table (61 common header entries), a per-connection FIFO dynamic table, prefix-integer and length-prefixed string coding, and a canonical Huffman code (RFC 7541 Appendix B) for string literals. All tables are generated verbatim from the RFC.

This codec is pure and host-tested (against the RFC 7541 Appendix C worked examples). The decoder resolves indexed fields, literals (with / without / never indexed), and dynamic-table size updates, maintaining the dynamic table with FIFO eviction. The encoder (server side) uses static-table indexing and literal-without-indexing with Huffman-coded strings, so it needs no dynamic-table state of its own. Zero heap; the dynamic table is a fixed byte ring.

Author: Douglas Quigg (dstroy0)

Date: 2026

Definition in file hpack.h.