1 files changed, 87 insertions, 0 deletions
diff --git a/library/HTMLPurifier/AttrDef/CSS.php b/library/HTMLPurifier/AttrDef/CSS.php
new file mode 100644
index 000000000..953e70675
--- /dev/null
+++ b/library/HTMLPurifier/AttrDef/CSS.php
@@ -0,0 +1,87 @@
+<?php
+
+/**
+ * Validates the HTML attribute style, otherwise known as CSS.
+ * @note We don't implement the whole CSS specification, so it might be
+ *       difficult to reuse this component in the context of validating
+ *       actual stylesheet declarations.
+ * @note If we were really serious about validating the CSS, we would
+ *       tokenize the styles and then parse the tokens. Obviously, we
+ *       are not doing that. Doing that could seriously harm performance,
+ *       but would make these components a lot more viable for a CSS
+ *       filtering solution.
+ */
+class HTMLPurifier_AttrDef_CSS extends HTMLPurifier_AttrDef
+{
+
+    public function validate($css, $config, $context) {
+
+        $css = $this->parseCDATA($css);
+
+        $definition = $config->getCSSDefinition();
+
+        // we're going to break the spec and explode by semicolons.
+        // This is because semicolon rarely appears in escaped form
+        // Doing this is generally flaky but fast
+        // IT MIGHT APPEAR IN URIs, see HTMLPurifier_AttrDef_CSSURI
+        // for details
+
+        $declarations = explode(';', $css);
+        $propvalues = array();
+
+        /**
+         * Name of the current CSS property being validated.
+         */
+        $property = false;
+        $context->register('CurrentCSSProperty', $property);
+
+        foreach ($declarations as $declaration) {
+            if (!$declaration) continue;
+            if (!strpos($declaration, ':')) continue;
+            list($property, $value) = explode(':', $declaration, 2);
+            $property = trim($property);
+            $value    = trim($value);
+            $ok = false;
+            do {
+                if (isset($definition->info[$property])) {
+                    $ok = true;
+                    break;
+                }
+                if (ctype_lower($property)) break;
+                $property = strtolower($property);
+                if (isset($definition->info[$property])) {
+                    $ok = true;
+                    break;
+                }
+            } while(0);
+            if (!$ok) continue;
+            // inefficient call, since the validator will do this again
+            if (strtolower(trim($value)) !== 'inherit') {
+                // inherit works for everything (but only on the base property)
+                $result = $definition->info[$property]->validate(
+                    $value, $config, $context );
+            } else {
+                $result = 'inherit';
+            }
+            if ($result === false) continue;
+            $propvalues[$property] = $result;
+        }
+
+        $context->destroy('CurrentCSSProperty');
+
+        // procedure does not write the new CSS simultaneously, so it's
+        // slightly inefficient, but it's the only way of getting rid of
+        // duplicates. Perhaps config to optimize it, but not now.
+
+        $new_declarations = '';
+        foreach ($propvalues as $prop => $value) {
+            $new_declarations .= "$prop:$value;";
+        }
+
+        return $new_declarations ? $new_declarations : false;
+
+    }
+
+}
+
+// vim: et sw=4 sts=4