Fix ASGI callback parser EOF handling and header validation#3560
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Add security checks to PythonProtocol per RFC 9110/9112: - Reject duplicate Content-Length headers - Reject CL + TE combinations - Reject chunked in HTTP/1.0 - Reject stacked chunked encoding - Validate Transfer-Encoding values - Strict chunk size validation Add PROXY protocol v1/v2 support to callback parser. Add treq-based test infrastructure for ASGI parser.
Handle chunked encoding edge case where connection closes before final CRLF after zero-chunk. Skip WSGI-specific tests (casefold, underscore headers) that don't apply to ASGI.
Update minimum version requirement for the fast HTTP parser to 0.6.0 which includes the finish() method for EOF handling in chunked encoding.
pajod
reviewed
Mar 26, 2026
| # identity after chunked is invalid | ||
| if chunked: | ||
| raise InvalidHeader("Invalid Transfer-Encoding after chunked") | ||
| elif val_lower in (b'compress', b'deflate', b'gzip'): |
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Why accept compress/deflate/gzip?
The application has no way to reliably know which hop-by-hop headers have been processed, and which still alter the meaning of the body. Since Gunicorn does not (and arguably, should not) decode that, any (in practice, nonexisting) request with such encoding specified should be rejected with UnsupportedTransferCoding as well. See also #3368
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Summary
finish()method to PythonProtocol for EOF handling in chunked encodingfinish()support in fast parserChanges