add some debug output

index.php

@@ -48,6 +48,11 @@ if (isset($_GET['secret']) && $_GET['secret'] === REGISTRATION_PASSWORD) {
     ];
     $content['mac'] = hash_hmac('sha1', $content['nonce']."\0".$content['username']."\0".$content['password']."\0".$content['admin'], REGISTRATION_SHARED_SECRET);
 
+    # debug
+    echo '<!--';
+    var_dump($content);
+    echo '-->';
+
     $ch = curl_init();
     curl_setopt($ch, CURLOPT_URL, SYNAPSE_URL.'/_synapse/admin/v1/register');
     curl_setopt($ch, CURLOPT_POST, true);