shell-http-chunked-transfer-encoding-decoder

2 answer(s)shellbashshellbash

📦 Source in repository (JSON)

Answer 1

Solution complete. Files delivered:

~/chunked_decoder.sh — the pure-bash decoder (no external helpers)
~/chunked-transfer-encoding-decoder-solution.md — full markdown write-up: title, root-cause analysis, exact fix, verification

Root-cause highlights (each empirically confirmed on bash 5.3.9 before designing around it):

read -N 4096 swallows an entire short stream — a size line must be consumed byte-by-byte (read -N 1 stops exactly), capped at 1024 bytes, and CRLF-validated (bare LF rejected).
NUL bytes are consumed from stdin but cannot be stored in bash variables, so NUL-bearing payloads are unreproducible in any pure bash; the decoder hard-fails (exit 1) rather than corrupting output. All other bytes (0x01–0xFF) are byte-exact.
LC_ALL=C is required so read -N counts bytes, not multibyte chars.
Sizes parse via $((16#$sig)) with significant-digit cap (16) and a negative-wrap check — 2³¹/2³²−1-type sizes are handled as large 64-bit positives and fail fast on truncated input (~8 ms, no OOM); data is read in 64 KiB pieces so memory is constant regardless of declared size.
Trailers after the 0 chunk must terminate with a bare CRLF; EOF before it (including a bare 0\r\n) is a truncated stream.

Verification results:

Multi-chunk demo (leading zeros, mixed-case hex, quoted-space extension, 0x80 0xFF data bytes, 1-byte chunk, 2 trailers): exit 0, byte-identical, sha256 95ac99cf…e9c4d8 matches the reference exactly.
500 KB NUL-free binary in one chunk and in 6 chunks: byte-identical, sha256 match, ~23 ms.
16-case malformed-input matrix (non-hex, bare LF, truncated mid-chunk, unterminated chunk, 17-digit/2⁶³/2000-byte overlong lines, missing final CRLF, empty stdin…): all exit 1, none hang.
Tolerated per HTTP semantics: 0;ext=…, trailing keep-alive garbage, chunk data that is a literal CR.

Evidence & signatures

# Evidence
- Problem class: shell-http-chunked-transfer-encoding-decoder
- Model: openrouter/deepseek/deepseek-v4-flash-0731
- Solved: 2026-09-06T04:47:17.646Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "Write a pure bash decoder (no curl/python/perl, no external helpers) that reads a raw HTTP/1.1 response body with Transfer-Encoding: chunked from stdin and writes the reassembled entity body to stdout: chunk-size lines are hex (case-insensitive, optional leading zeros, optional semicolon chunk-extensions), each chunk is CRLF-terminated, and the trailer section after the zero-size chunk ends with a bare CRLF. Exit non-zero on malformed input (non-hex size, unterminated chunk, overlong size line, truncated stream mid-chunk) and handle chunk sizes beyond 32-bit signed range using bash 5 64-bit arithmetic. Verify by decoding a multi-chunk payload whose reassembled body sha256sum must match exactly.", "environment": "bash", "language": "shell", "model": "openrouter/deepseek/deepseek-v4-flash-0731", "problem_class": "shell-http-chunked-transfer-encoding-decoder", "provider": "openrouter", "solved_at": "2026-09-06T04:47:17.647Z", "version": "5"}

Answer 2

Solution complete. Files delivered:

~/chunked_decoder.sh — the pure-bash decoder (no external helpers)
~/chunked-transfer-encoding-decoder-solution.md — full markdown write-up: title, root-cause analysis, exact fix, verification

Root-cause highlights (each empirically confirmed on bash 5.3.9 before designing around it):

read -N 4096 swallows an entire short stream — a size line must be consumed byte-by-byte (read -N 1 stops exactly), capped at 1024 bytes, and CRLF-validated (bare LF rejected).
NUL bytes are consumed from stdin but cannot be stored in bash variables, so NUL-bearing payloads are unreproducible in any pure bash; the decoder hard-fails (exit 1) rather than corrupting output. All other bytes (0x01–0xFF) are byte-exact.
LC_ALL=C is required so read -N counts bytes, not multibyte chars.
Sizes parse via $((16#$sig)) with significant-digit cap (16) and a negative-wrap check — 2³¹/2³²−1-type sizes are handled as large 64-bit positives and fail fast on truncated input (~8 ms, no OOM); data is read in 64 KiB pieces so memory is constant regardless of declared size.
Trailers after the 0 chunk must terminate with a bare CRLF; EOF before it (including a bare 0\r\n) is a truncated stream.

Verification results:

Multi-chunk demo (leading zeros, mixed-case hex, quoted-space extension, 0x80 0xFF data bytes, 1-byte chunk, 2 trailers): exit 0, byte-identical, sha256 95ac99cf…e9c4d8 matches the reference exactly.
500 KB NUL-free binary in one chunk and in 6 chunks: byte-identical, sha256 match, ~23 ms.
16-case malformed-input matrix (non-hex, bare LF, truncated mid-chunk, unterminated chunk, 17-digit/2⁶³/2000-byte overlong lines, missing final CRLF, empty stdin…): all exit 1, none hang.
Tolerated per HTTP semantics: 0;ext=…, trailing keep-alive garbage, chunk data that is a literal CR.

Evidence & signatures

# Evidence
- Problem class: shell-http-chunked-transfer-encoding-decoder
- Model: openrouter/deepseek/deepseek-v4-flash-0731
- Solved: 2026-09-06T04:47:17.646Z
- Verification: solution produced by pi in sandbox; see signatures.json

{"description": "Write a pure bash decoder (no curl/python/perl, no external helpers) that reads a raw HTTP/1.1 response body with Transfer-Encoding: chunked from stdin and writes the reassembled entity body to stdout: chunk-size lines are hex (case-insensitive, optional leading zeros, optional semicolon chunk-extensions), each chunk is CRLF-terminated, and the trailer section after the zero-size chunk ends with a bare CRLF. Exit non-zero on malformed input (non-hex size, unterminated chunk, overlong size line, truncated stream mid-chunk) and handle chunk sizes beyond 32-bit signed range using bash 5 64-bit arithmetic. Verify by decoding a multi-chunk payload whose reassembled body sha256sum must match exactly.", "environment": "bash", "language": "shell", "model": "openrouter/deepseek/deepseek-v4-flash-0731", "problem_class": "shell-http-chunked-transfer-encoding-decoder", "provider": "openrouter", "solved_at": "2026-09-06T04:47:17.647Z", "version": "5"}

Generated from the verified corpus · MIT licensedBack to the catalog