elixir-mint / hpax / 18a42a5e469c409d13fdfb0f3f44715de8e5af22-PR-26

96%

main: 96%

Pull #26

github

Use empty binary, not nil, for static table entries with no default value

HPAX.Table's @static_table stored `nil` as the value for the many
static entries that have no default (RFC 7541, Appendix A - e.g.
:authority, host, user-agent). Decoding a plain Indexed Header Field
Representation (section 6.1) against one of these entries - fully
legal per the RFC, and something real HTTP/2 clients (and h2spec) do
- returned that literal `nil` as the header value, silently violating
this module's own documented contract that decoded values are always
binaries (HPAX.header_value() :: binary()).

Any caller relying on that contract (e.g. calling byte_size/1 on
every decoded value) would crash on such a request. This also meant
the encoder could never emit a compact single-byte indexed reference
when asked to encode one of these headers with a literal empty-string
value, since the {:full, index} match required by lookup_by_header/3
was guarded with `is_binary(value)` and so never fired for the
nil-valued entries.

Storing "" instead of nil fixes both: decoded values are always
binaries as documented, and encoding a header whose value happens to
be "" for one of these names now correctly compresses to one byte.

1 of 1 new or added line in 1 file covered. (100.0%)

163 of 170 relevant lines covered (95.88%)

3838.77 hits per line