System: Configuration: History - when omitting the backup filename (c…

…ontaining a timestamp), offer the latest one found based on filename. Since backup filenames contain a timestamp, `array_reverse(glob())` should provide the latest first.

PR: #6996

Endpoint without explicit filename for this host :  https://xxx.xxx.xxx.xxx/api/core/backup/download/this

(cherry picked from commit 0227baf)
(cherry picked from commit 7ee772a)

src/opnsense/mvc/app/controllers/OPNsense/Core/Api/BackupController.php

@@ -183,14 +183,14 @@ public function revertBackupAction($backup)
     }
 
     /**
-     * download specified backup
+     * download specified backup, when left empty the latest is offered
      */
-    public function downloadAction($host, $backup)
+    public function downloadAction($host, $backup = null)
     {
         $providers = $this->providers();
         if (!empty($providers[$host])) {
-            foreach (glob($providers[$host]['dirname'] . "/config-*.xml") as $filename) {
-                if ($backup == basename($filename)) {
+            foreach (array_reverse(glob($providers[$host]['dirname'] . "/config-*.xml")) as $filename) {
+                if (empty($backup) || $backup == basename($filename)) {
                     $payload = @simplexml_load_file($filename);
                     $hostname = '';
                     if ($payload !== false && isset($payload->system) && isset($payload->system->hostname)) {