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gh-150751: validate http.client Content-Length and chunk-size - #150752
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RFC 9112 defines Content-Length as 1*DIGIT and chunk-size as 1*HEXDIG, but int() also accepts a sign, underscores, surrounding whitespace and an 0x prefix, so malformed framing values were parsed instead of rejected.
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gentle ping |
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This PR is stale because it has been open for 90 days with no activity. |
| # RFC 9112: Content-Length = 1*DIGIT and chunk-size = 1*HEXDIG. int() is more | ||
| # permissive (it accepts a leading sign, underscores, surrounding whitespace | ||
| # and, in base 16, an "0x" prefix and non-ASCII digits), so the body-framing | ||
| # values are matched against the grammar before being passed to int(). |
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This is too verbose.
(There have been suggestions to extend what int() accepts. We'll not go over comments like this if that happens.)
| # RFC 9112: Content-Length = 1*DIGIT and chunk-size = 1*HEXDIG. int() is more | |
| # permissive (it accepts a leading sign, underscores, surrounding whitespace | |
| # and, in base 16, an "0x" prefix and non-ASCII digits), so the body-framing | |
| # values are matched against the grammar before being passed to int(). | |
| # RFC 9112: Content-Length = 1*DIGIT and chunk-size = 1*HEXDIG. | |
| # int() is more permissive, so we match against the grammar before calling it. |
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Applied your wording. Fair point that the enumeration would go stale if int() is extended, and the grammar reference is the part that actually needs to be there.
| i = line.find(b";") | ||
| if i >= 0: | ||
| line = line[:i] # strip chunk-extensions | ||
| line = line.strip() |
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| line = line.strip() | |
| line = line.rstrip() |
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Done. rstrip() is the better fit, since leading whitespace isn't in the grammar either and should fail the match rather than get trimmed away first. I've added 5 to test_malformed_chunk_size so that case stays covered.
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Thank you! |
encukou
added
needs backport to 3.14
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Thanks @metsw24-max for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.15. |
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Thanks @metsw24-max for the PR, and @encukou for merging it 🌮🎉.. I'm working now to backport this PR to: 3.14. |
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GH-159020 is a backport of this pull request to the 3.14 branch. |
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GH-159021 is a backport of this pull request to the 3.15 branch. |
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needs backport to 3.15
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Noticed
beginand_read_next_chunk_sizederive the response body framing fromint(length)andint(line, 16), butintalso accepts a leading sign, underscores, surrounding whitespace and an0xprefix that RFC 9112 forbids forContent-Length(1DIGIT) andchunk-size(1HEXDIG). So+5,5_0or a negative chunk size parse cleanly here while a strict front end frames the response differently. This matches both tokens against the grammar before converting.