1821033 - [DNR] Restrict syntax of regexFilter and adjust MAX_NUMBER_OF_REGEX_RULES

Status: NEW

(WebExtensions :: Request Handling, task, P3)

Description

[Rob Wu [:robwu]]

In bug 1745760, I introduced a prototype of the regexFilter condition matcher, that internally uses the default RegExp implementation in JavaScript. This was chosen because there was no clear definition on what a regexFilter should look like (https://bugzilla.mozilla.org/show_bug.cgi?id=1745760#c1).

To minimize the impact on memory usage or evaluation performance, we should reject patterns that are inefficient. The purpose of this bug is to figure out which patterns have to be restricted or supported, and to enforce that in the regexFilter condition and the isRegexSupported method.

As we do that, we may also bump the number of supported regular expression rules (MAX_NUMBER_OF_REGEX_RULES, currently 1000).