Fix #1528: add macro expansion for @rx operator #1536
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try to use macro expansion on @rx argument before matching. If after expansion argument changed, make new Regex from the macro-expanded argument and use that for matching. Fixes owasp-modsecurity#1528
Added method checkIfMacroExpansionPossible() called by Rx
constructor to check if "%{...}" construct is present in regex.
If not, Rx::evaluate should not try macro expansion on regex
before matching.
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Hey @zimmerle @victorhora - any reasons this PR is still not merged? Just wondering due to related issue reported here: Thanks! |
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Hi @defanator, It is in my queue to review. In particular I am interested to understand if there is memory corruption in |
zimmerle
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zimmerle
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Hi @asterite3, Thank you for the patch! It is already merge. Notice however that I have removed the optimization, as it demands further investigation. |
zimmerle
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Dec 29, 2017
This reverts commit fa7973a.
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There is a problem that macro expansion in regex of
@rxoperator does not work (see #1528).This pull request adds a code that tries macro expansion on regex before matching, and, if regex text changed after expansion, create new Regex object from it and use that for matching.
Also, add an optimization: in Rx constructor, check if macro expansion is possible at all for regex (
%{...}present in it), cache the result of this check (save it in a boolean field of Rx object) and try macro expansion before matching only if check was positive. This should avoid macro expansion attempts + string compares for most regexes (at least, for most regexes in OWASP CRS).Also, add a regression test.
Fixes #1528