aggregator2: allow the user to specify the MIME type of the response.

modules/aggregator2/www/get.php

 <?php
 
 if (!isset($_REQUEST['id'])) {
-	throw new SimpleSAML_Error_BadRequest('Missing required id-parameter.');
+    throw new SimpleSAML_Error_BadRequest('Missing required parameter "id".');
 }
-$id = (string)$_REQUEST['id'];
+$id = (string) $_REQUEST['id'];
 
 $aggregator = sspmod_aggregator2_Aggregator::getAggregator($id);
 $xml = $aggregator->getMetadata();
 
-header('Content-Type: application/samlmetadata+xml');
+$mimetype = 'application/samlmetadata+xml';
+$allowedmimetypes = array(
+    'text/plain',
+    'application/samlmetadata-xml',
+    'application/xml',
+);
+
+if (isset($_GET['mimetype']) && in_array($_GET['mimetype'], $allowedmimetypes)) {
+    $mimetype = $_GET['mimetype'];
+}
+
+if ($mimetype === 'text/plain') {
+    $xml = SimpleSAML_Utilities::formatXMLString($xml);
+}
+
+header('Content-Type: '.$mimetype);
 header('Content-Length: ' . strlen($xml));
 
 /*
@@ -17,4 +32,4 @@ header('Content-Length: ' . strlen($xml));
  */
 header('Content-Disposition: filename='.$id.'.xml');
 
-echo($xml);
+echo $xml;