A couple of fixes to the API.

includes/api_functions.php

@@ -59,8 +59,13 @@ function get_function_args($main_request)
 
 function get_query_port($server_xml, $server_port)
 {
-	if( $server_xml->query_port and $server_xml->query_port['type'] == "add" )
-		return $server_port + $server_xml->query_port;
+	if ($server_xml->query_port)
+	{
+		if ($server_xml->query_port['type'] == 'add')
+			return $server_port + $server_xml->query_port;
+		if ($server_xml->query_port['type'] == 'subtract')
+			return $server_port - $server_xml->query_port;
+	}
 	return $server_port;
 }
 

ogp_api.php

@@ -1498,7 +1498,7 @@ function api_addonsmanager()
 		else
 		{
 			$status = "342";
-			$message = "Addon installation failed, file download could not be started.($retval)";
+			$message = "Addon installation failed, file download could not be started.";
 		}
 	}