DeflateBuffer: skip RFC 1950 header sniff on empty chunks#13050
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HrachShah wants to merge 2 commits into
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DeflateBuffer: skip RFC 1950 header sniff on empty chunks#13050HrachShah wants to merge 2 commits into
HrachShah wants to merge 2 commits into
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feed_data(b"") is used by the chunked-transfer decoder to resume a paused stream (see HttpRequestParser._post_parse and HttpResponseParser around the eof/length branches). When a deflate stream had not yet started decoding, the very first such resume would read chunk[0] to sniff the CM bits of the zlib header and raise IndexError on the empty input. Issue aio-libs#12994. Guard the sniff with a leading truthy check on chunk so an empty chunk falls through to decompress_sync(b""), which is a no-op and returns the same data_available flag the caller's resume loop already uses to decide whether to retry. No exception, no spurious bytes pushed downstream, no infinite loop. Add test_empty_chunk_is_noop covering the pre-decode IndexError case plus a follow-up real-data round-trip to prove the decoder is still usable afterwards. Add CHANGES/12994.bugfix.rst.
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #13050 +/- ##
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Coverage 98.96% 98.96%
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Branches 2499 2500 +1
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Fixes #12994.
DeflateBuffer.feed_data(b"")raisedIndexErrorbecause the CM-byte sniff at the start of the method readchunk[0]on the empty input. The chunked-transfer decoder uses emptyfeed_datacalls to resume a paused decompressor (seeHttpRequestParser._post_parseandHttpResponseParseraround the eof/length branches), and on a deflate stream that had not yet started decoding, the very first such resume hit the empty-chunk branch and crashed.Guard the CM-byte sniff with a leading truthy check on
chunkso an empty chunk falls through todecompress_sync(b""), which is already a no-op. The resume loop'sself.decompressor.data_availableflag still drives termination, so no infinite loop is introduced.python3 -m pytest tests/test_http_parser.py -k deflatepasses 88 tests (was 87); the newtest_empty_chunk_is_noopregression test fails on the pre-fix code and passes with the fix.