Fix some issues when ldap_get_entries returns false (librenms#18090)

Author: murrant

LibreNMS/Authentication/LdapAuthorizer.php

@@ -183,6 +183,10 @@ public function getUser($user_id): false|array
 
         $search = ldap_search($connection, trim(LibrenmsConfig::get('auth_ldap_suffix'), ','), $filter);
         $entries = ldap_get_entries($connection, $search);
+        if (! $entries) {
+            return false;
+        }
+
         foreach ($entries as $entry) {
             $user = $this->ldapToUser($entry);
             if ($user['user_id'] != $user_id) {
@@ -262,7 +266,12 @@ protected function setAuthLdapSuffixOu($username): bool
         $base_dn = preg_replace('/,ou=[^,]+,/', ',', LibrenmsConfig::get('auth_ldap_suffix'));
         $base_dn = trim($base_dn, ',');
         $search = ldap_search($connection, $base_dn, $filter);
-        foreach (ldap_get_entries($connection, $search) as $entry) {
+        $results = ldap_get_entries($connection, $search);
+        if (! $results) {
+            return false;
+        }
+
+        foreach ($results as $entry) {
             if (isset($entry['uid'][0]) && $entry['uid'][0] == $username) {
                 preg_match('~,ou=([^,]+),~', $entry['dn'], $matches);
                 $user_ou = $matches[1] ?? '';
@@ -305,7 +314,7 @@ protected function getLdapConnection($skip_bind = false)
      * @param  array  $entry  ldap entry array
      * @return array
      */
-    private function ldapToUser($entry): array
+    private function ldapToUser(array $entry): array
     {
         $uid_attr = strtolower(LibrenmsConfig::get('auth_ldap_uid_attribute', 'uidnumber'));