* Support custom sanitization policy
Allowing the gitea administrator to configure sanitization policy allows
them to couple external renders and custom templates to support more
markup. In particular, the `pandoc` renderer allows generating KaTeX
annotations, wrapping them in `<span>` elements with class `math` and
either `inline` or `display` (depending on whether or not inline or
block mode was requested).
This iteration gives the administrator whitelisting powers; carefully
crafted regexes will thus let through only the desired attributes
necessary to support their custom markup.
Resolves: #9054
Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
* Document new sanitization configuration
- Adds basic documentation to app.ini.sample,
- Adds an example to the Configuration Cheat Sheet, and
- Adds extended information to External Renderers section.
Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
* Drop extraneous length check in newMarkupSanitizer(...)
Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
* Fix plural ELEMENT and ALLOW_ATTR in docs
These were left over from their initial names. Make them singular to
conform with the current expectations.
Signed-off-by: Alexander Scheel <alexander.m.scheel@gmail.com>
* restructure markup & markdown to prepare for multiple markup languages support
* adjust some functions between markdown and markup
* fix tests
* improve the comments
