filter - How can I allow HTML in a whitelist with PHP

Question

I know there is a lot of discussion for years on best methods of filtering data with PHP but I would like to go the whitelist approach in my current project.

I only want a user to be able to use the following HTML

<b>bold</b>
<i>italics</i>
<u>underline</u>
<s>strikethrough</s>
<big>Big size</big >
<small>Small size</small>

Hyperlink <a href="http://www.site.com">website</a>

A Bulleted List:
<ul>
<li>One Item</li>
<li>Another Item</li>
</ul>

An Ordered List:
<ol>
<li> First Item</li>
<li> Second Item</li>
</ol>

<blockquote>Because it is indented</blockquote>

<h1>Heading 1</h1>
<h2>Heading 2</h2>
<h3>Heading 3</h3>

Can anyone show me the best method of doing this for performance in PHP? I have only in the past allowed all html minus certain codes

Answer 1

I believe the HTML Purifier Library will work nicely:

http://htmlpurifier.org/

HTML Purifier is a standards-compliant HTML filter library written in PHP. HTML Purifier will not only remove all malicious code (better known as XSS) with a thoroughly audited, secure yet permissive whitelist, it will also make sure your documents are standards compliant, something only achievable with a comprehensive knowledge of W3C's specifications. Tired of using BBCode due to the current landscape of deficient or insecure HTML filters? Have a WYSIWYG editor but never been able to use it? Looking for high-quality, standards-compliant, open-source components for that application you're building? HTML Purifier is for you!