fix(config): Allow SASL method as default hash

This allows to use SASL as default hash before filling SASL settings.
This means it can be selected from setup as well.
The admin won’t be able to save if he selects SASL as default hash but
 does not fill SASL settings.

closes #5589

plugins/config/class_configInLdap.inc

@@ -455,6 +455,9 @@ class configInLdap extends simplePlugin
     /* Password methods */
     $methods = passwordMethod::get_available_methods();
     $methods = $methods['name'];
+    if (!in_array('sasl', $methods)) {
+      $methods[] = 'sasl';
+    }
     $attributesInfo['password']['attrs'][0]->setChoices($methods);
 
     $groupsAndRoles = array_merge(
@@ -569,6 +572,15 @@ class configInLdap extends simplePlugin
     return $this->dn;
   }
 
+  function check()
+  {
+    $messages = parent::check();
+    if (($this->fdPasswordDefaultHash == 'sasl') && ($this->fdSaslRealm == '') && ($this->fdSaslExop == '')) {
+      $messages[] = _('You need to fill saslRealm or saslExop in the configuration screen in order to use SASL');
+    }
+    return $messages;
+  }
+
   static function get_themes()
   {
     $themesdir  = '../ihtml/themes/';