07-body-decoder.md

Body Decoder

Scope

The body decoder handles framing only.

Included:

• fixed-length byte accounting
• chunked decode
• trailer consumption control

Excluded:

• transport reads
• hidden buffering
• content-coding decode
• application payload interpretation

Decoder Surface

API	Purpose
ihtp_fixed_decoder_init()	initialize fixed-length accounting
ihtp_decode_fixed()	advance fixed-length decode state
ihtp_chunked_decoder_t	chunked decode state
ihtp_decode_chunked()	decode chunked body bytes in place

Chunked Decoder Contract

• Reuse one ihtp_chunked_decoder_t across calls.
• The decoder rewrites the caller buffer in place.
• *bufsz becomes the retained payload size in the current slice.
• total_decoded counts payload bytes only.
• A non-negative return value means completion and equals the number of trailing bytes after the terminal chunk processing path.

Trailer Ownership

consume_trailer	Effect
true	decoder consumes trailer fields through the terminating empty line
false	decoder leaves trailer bytes for the consumer

Trailing bytes remain in the caller buffer immediately after the decoded payload prefix.

Fixed-Length Decoder Contract

• ihtp_fixed_decoder_init() sets the expected payload length.
• ihtp_decode_fixed() is accounting only.
• remaining decreases monotonically.
• total_decoded increases monotonically.
• Passing more bytes than remaining is an error.

Ownership Rules

• Input bytes are caller-owned.
• Decoded payload bytes remain in caller-owned memory.
• Decoder state stores counters and phase only.

Decode Sequence

sequenceDiagram
    participant C as Caller
    participant S as Semantics
    participant D as Decoder

    C->>S: parsed headers
    S-->>C: body mode
    C->>D: body bytes
    D-->>C: payload bytes
    D-->>C: trailing bytes

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