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/AttrTransform/Border.php

@@ -0,0 +1,26 @@
+<?php
+
+/**
+ * Pre-transform that changes deprecated border attribute to CSS.
+ */
+class HTMLPurifier_AttrTransform_Border extends HTMLPurifier_AttrTransform
+{
+    /**
+     * @param array $attr
+     * @param HTMLPurifier_Config $config
+     * @param HTMLPurifier_Context $context
+     * @return array
+     */
+    public function transform($attr, $config, $context)
+    {
+        if (!isset($attr['border'])) {
+            return $attr;
+        }
+        $border_width = $this->confiscateAttr($attr, 'border');
+        // some validation should happen here
+        $this->prependCSS($attr, "border:{$border_width}px solid;");
+        return $attr;
+    }
+}
+
+// vim: et sw=4 sts=4