Stringify sanitized HTML as HTML (not XML)#3575
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tillprochaska merged 1 commit intodevelopfrom Jan 25, 2024
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The `etree.ElementTree.tostring` method stringifies as valid XML by default. While XML allows self-closing tags by default, only some tags can be self-closing in HTML. This causes problems when rendering the sanitized HTML. Consider this example: ```html <noscript><script src="proxy.php?url=..."></script></noscript> <h1>Page title</h1> <p>Some text</p> ``` When converting the sanitized element tree to XML, this would result in something like this: ```html <noscript /> <h1>Page title</h1> <p>Some text</p> ``` `noscript` is not a valid void element which results in browsers treating all following elements as children of the `noscript` tag, parsing the HTML into an effective DOM structure like this: ```html <noscript> <h1>Page title</h1> <p>Some text</p> </noscript> ``` As a result the actual page contents are hidden when rendered in a browser (if JavaScript is enabled).
stchris
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Jan 25, 2024
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Brilliant investigation, thanks for documenting this in detail! And for fixing it, of course!
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This fixes a bug where Aleph doesn’t correctly preview HTML pages (see #3334).
The
etree.ElementTree.tostringmethod stringifies as valid XML by default. While XML allows self-closing tags by default, only some tags can be self-closing in HTML.This causes problems when rendering the sanitized HTML. Consider this example:
When converting the sanitized element tree to XML, this would result in something like this:
noscriptis not a valid void element which results in browsers treating all following elements as children of thenoscripttag, parsing the HTML into an effective DOM structure like this:As a result the actual page contents are hidden when rendered in a browser (if JavaScript is enabled).