Escape story fields and clean story HTML with HTML Purifier.

Add HTML Purifier 4.19.1. Stories are purified when they are saved and
when they are shown.

lib/htmlpurifier-4.19.1/library/HTMLPurifier/HTMLModule/SafeScripting.php

@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * A "safe" script module. No inline JS is allowed, and pointed to JS
+ * files must match whitelist.
+ */
+class HTMLPurifier_HTMLModule_SafeScripting extends HTMLPurifier_HTMLModule
+{
+    /**
+     * @type string
+     */
+    public $name = 'SafeScripting';
+
+    /**
+     * @param HTMLPurifier_Config $config
+     */
+    public function setup($config)
+    {
+        // These definitions are not intrinsically safe: the attribute transforms
+        // are a vital part of ensuring safety.
+
+        $allowed = $config->get('HTML.SafeScripting');
+        $script = $this->addElement(
+            'script',
+            'Inline',
+            'Optional:', // Not `Empty` to not allow to autoclose the <script /> tag @see https://www.w3.org/TR/html4/interact/scripts.html
+            null,
+            array(
+                // While technically not required by the spec, we're forcing
+                // it to this value.
+                'type' => 'Enum#text/javascript',
+                'src*' => new HTMLPurifier_AttrDef_Enum(array_keys($allowed), /*case sensitive*/ true)
+            )
+        );
+        $script->attr_transform_pre[] =
+        $script->attr_transform_post[] = new HTMLPurifier_AttrTransform_ScriptRequired();
+    }
+}
+
+// vim: et sw=4 sts=4