Install How to install HTML Purifier HTML Purifier is designed to run out of the box, so actually using the library is extremely easy. (Although... if you were looking for a step-by-step installation GUI, you've downloaded the wrong software!) While the impatient can get going immediately with some of the sample code at the bottom of this library, it's well worth performing some basic sanity checks to get the most out of this library. --------------------------------------------------------------------------- 1. Compatibility HTML Purifier works in both PHP 4 and PHP 5, and is actively tested from PHP 4.3.7 and up (see tests/multitest.php for specific versions). It has no core dependencies with other libraries. PHP 4 support will be deprecated on December 31, 2007, at which time only essential security fixes will be issued for the PHP 4 version until August 8, 2008. These optional extensions can enhance the capabilities of HTML Purifier: * iconv : Converts text to and from non-UTF-8 encodings * tidy : Used for pretty-printing HTML --------------------------------------------------------------------------- 2. Reconnaissance A big plus of HTML Purifier is its inerrant support of standards, so your web-pages should be standards-compliant. (They should also use semantic markup, but that's another issue altogether, one HTML Purifier cannot fix without reading your mind.) HTML Purifier can process these doctypes: * XHTML 1.0 Transitional (default) * XHTML 1.0 Strict * HTML 4.01 Transitional * HTML 4.01 Strict * XHTML 1.1 ...and these character encodings: * UTF-8 (default) * Any encoding iconv supports (with crippled internationalization support) These defaults reflect what my choices where be if I were authoring an HTML document, however, what you choose depends on the nature of your codebase. If you don't know what doctype you are using, you can determine the doctype from this identifier at the top of your source code: ...and the character encoding from this code: If the character encoding declaration is missing, STOP NOW, and read 'docs/enduser-utf8.html' (web accessible at http://htmlpurifier.org/docs/enduser-utf8.html). In fact, even if it is present, read this document anyway, as most websites specify character encoding incorrectly. --------------------------------------------------------------------------- 3. Including the library The procedure is quite simple: require_once '/path/to/library/HTMLPurifier.auto.php'; I recommend only including HTML Purifier when you need it, because that call represents the inclusion of a lot of PHP files which constitute the bulk of HTML Purifier's memory usage. If you don't like your include_path to be fiddled around with, simply set HTML Purifier's library/ directory to the include path yourself and then: require_once 'HTMLPurifier.php'; Only the contents in the library/ folder are necessary, so you can remove everything else when using HTML Purifier in a production environment. --------------------------------------------------------------------------- 4. Configuration HTML Purifier is designed to run out-of-the-box, but occasionally HTML Purifier needs to be told what to do. If you answered no to any of these questions, read on, otherwise, you can skip to the next section (or, if you're into configuring things just for the heck of it, skip to 4.3). * Am I using UTF-8? * Am I using XHTML 1.0 Transitional? If you answered no to any of these questions, instantiate a configuration object and read on: $config = HTMLPurifier_Config::createDefault(); 4.1. Setting a different character encoding You really shouldn't use any other encoding except UTF-8, especially if you plan to support multilingual websites (read section three for more details). However, switching to UTF-8 is not always immediately feasible, so we can adapt. HTML Purifier uses iconv to support other character encodings, as such, any encoding that iconv supports HTML Purifier supports with this code: $config->set('Core', 'Encoding', /* put your encoding here */); An example usage for Latin-1 websites (the most common encoding for English websites): $config->set('Core', 'Encoding', 'ISO-8859-1'); Note that HTML Purifier's support for non-Unicode encodings is crippled by the fact that any character not supported by that encoding will be silently dropped, EVEN if it is ampersand escaped. If you want to work around this, you are welcome to read docs/enduser-utf8.html for a fix, but please be cognizant of the issues the "solution" creates (for this reason, I do not include the solution in this document). 4.2. Setting a different doctype For those of you using HTML 4.01 Transitional, you can disable XHTML output like this: $config->set('HTML', 'Doctype', 'HTML 4.01 Transitional'); Other supported doctypes include: * HTML 4.01 Strict * HTML 4.01 Transitional * XHTML 1.0 Strict * XHTML 1.0 Transitional * XHTML 1.1 4.3. Other settings There are more configuration directives which can be read about here: They're a bit boring, but they can help out for those of you who like to exert maximum control over your code. Some of the more interesting ones are configurable at the demo and are well worth looking into for your own system. For example, you can fine tune allowed elements and attributes, convert relative URLs to absolute ones, and even autoparagraph input text! These are, respectively, %HTML.Allowed, %URI.MakeAbsolute and %URI.Base, and %AutoFormat.AutoParagraph. The %Namespace.Directive naming convention translates to: $config->set('Namespace', 'Directive', $value); E.g. $config->set('HTML', 'Allowed', 'p,b,a[href],i'); $config->set('URI', 'Base', 'http://www.example.com'); $config->set('URI', 'MakeAbsolute', true); $config->set('AutoFormat', 'AutoParagraph', true); --------------------------------------------------------------------------- 5. Caching HTML Purifier generates some cache files (generally one or two) to speed up its execution. For maximum performance, make sure that library/HTMLPurifier/DefinitionCache/Serializer is writeable by the webserver. If you are in the library/ folder of HTML Purifier, you can set the appropriate permissions using: chmod -R 0755 HTMLPurifier/DefinitionCache/Serializer If the above command doesn't work, you may need to assign write permissions to all. This may be necessary if your webserver runs as nobody, but is not recommended since it means any other user can write files in the directory. Use: chmod -R 0777 HTMLPurifier/DefinitionCache/Serializer You can also chmod files via your FTP client; this option is usually accessible by right clicking the corresponding directory and then selecting "chmod" or "file permissions". Starting with 2.0.1, HTML Purifier will generate friendly error messages that will tell you exactly what you have to chmod the directory to, if in doubt, follow its advice. If you are unable or unwilling to give write permissions to the cache directory, you can either disable the cache (and suffer a performance hit): $config->set('Core', 'DefinitionCache', null); Or move the cache directory somewhere else (no trailing slash): $config->set('Cache', 'SerializerPath', '/home/user/absolute/path'); --------------------------------------------------------------------------- 6. Using the code The interface is mind-numbingly simple: $purifier = new HTMLPurifier(); $clean_html = $purifier->purify( $dirty_html ); ...or, if you're using the configuration object: $purifier = new HTMLPurifier($config); $clean_html = $purifier->purify( $dirty_html ); That's it! For more examples, check out docs/examples/ (they aren't very different though). Also, docs/enduser-slow.html gives advice on what to do if HTML Purifier is slowing down your application. --------------------------------------------------------------------------- 7. Quick install First, make sure library/HTMLPurifier/DefinitionCache/Serializer is writable by the webserver (see Section 5: Caching above for details). If your website is in UTF-8 and XHTML Transitional, use this code: purify($dirty_html); ?> If your website is in a different encoding or doctype, use this code: set('Core', 'Encoding', 'ISO-8859-1'); // replace with your encoding $config->set('HTML', 'Doctype', 'HTML 4.01 Transitional'); // replace with your doctype $purifier = new HTMLPurifier($config); $clean_html = $purifier->purify($dirty_html); ?>