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68 lines
2.7 KiB
Plaintext
68 lines
2.7 KiB
Plaintext
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Filter Levels
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When one size *does not* fit all
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The more I think about it, the less sense it makes for maintaining one huge
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monolithic HTMLDefinition class. There's simply so much variation that
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could go into this definition: the set of HTML good for blog entries is
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definitely too large for HTML that would be allowed in blog comments. Going
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from Transitional to Strict requires changes to the definition.
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However, allowing users to specify their own whitelists was an idea I
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rejected from the start. Simply put, the typical programmer is too lazy
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to actually go through the trouble of investigating which tags, attributes
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and properties to allow. HTMLDefinition makes a big part of what HTMLPurifier
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is.
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The idea, then, is to setup fundamentally different set of definitions, which
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can further be customized using simpler configuration options.
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Here are some fuzzy levels you could set:
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1. Comments - Wordpress recommends a, abbr, acronym, b, blockquote, cite,
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code, em, i, strike, strong; however, you could get away with only a, b and
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i; also having p and pre tags would be helpful.
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2. Pages - As permissive as possible without allowing XSS. No protection
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against bad design sense, unfortunantely. Suitable for wiki and page
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environments.
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3. Lint - Accept everything in the spec, a Tidy wannabe.
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I've also decomposed tags into risk levels. An asterisk indicates that no one
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really uses that tag, tilde indicates it's deprecated.
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1 - blockquote, code, em, i, p, tt / strong, sub, sup
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1* - abbr, acronym, bdo, cite, dfn, kbd, q, samp
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2 - b, br, del, div, pre, span / ins, s, strike ~ u
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3 - h2, h3, h4, h5, h6 ~ center
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4 - h1, big ~ font
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5 - a
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7 - area, map
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Lists - dd, dl, dt, li, ol, ul ~ menu, dir
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Tables - caption, table, td, th, tr / col, colgroup, tbody, tfoot, thead
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Forms - fieldset, form, input, lable, legend, optgroup, option, select, textarea
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XSS - noscript, object, script ~ applet
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Meta - base, basefont, body, head, html, link, meta, style, title
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Frames - frame, frameset, iframe
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And tag specific notes:
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a - general problems involving linkspam
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b - too much bold is bad, typographically speaking bold is discouraged
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br - often misused
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center - CSS, usually no legit use
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del - only useful in editing context
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div - little meaning in certain contexts i.e. blog comment
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h1 - usually no legit use, as header is already set by application
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h* - not needed in blog comments
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hr - usually not necessary in blog comments
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img - could be extremely undesirable if linking to external pics
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pre - could use formatting, only useful in code contexts
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q - very little support
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s - transform into span with styling or del?
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small - technically presentational
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span - depends on attribute allowances
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sub, sup - specialized
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u - little legit use, prefer class with text-decoration
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