MDL-9151 HTML Purifier cleaning support - enable switch is in experimental section

MDL-9435 Reviewved url cleaning in redirect()

lib/htmlpurifier/HTMLPurifier/AttrDef/HTML/Pixels.php

@@ -0,0 +1,37 @@
+<?php
+
+require_once 'HTMLPurifier/AttrDef.php';
+
+/**
+ * Validates an integer representation of pixels according to the HTML spec.
+ */
+class HTMLPurifier_AttrDef_HTML_Pixels extends HTMLPurifier_AttrDef
+{
+    
+    function validate($string, $config, &$context) {
+        
+        $string = trim($string);
+        if ($string === '0') return $string;
+        if ($string === '')  return false;
+        $length = strlen($string);
+        if (substr($string, $length - 2) == 'px') {
+            $string = substr($string, 0, $length - 2);
+        }
+        if (!is_numeric($string)) return false;
+        $int = (int) $string;
+        
+        if ($int < 0) return '0';
+        
+        // upper-bound value, extremely high values can
+        // crash operating systems, see <http://ha.ckers.org/imagecrash.html>
+        // WARNING, above link WILL crash you if you're using Windows
+        
+        if ($int > 1200) return '1200';
+        
+        return (string) $int;
+        
+    }
+    
+}
+
+?>