Last active
October 5, 2019 13:58
-
-
Save arnissolle/5c2cecec33ce757cb07bb0b119f6bb20 to your computer and use it in GitHub Desktop.
CSRF Protection
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| <?php | |
| class CSRF | |
| { | |
| public static $salt = null; | |
| public static function getToken($force_renew_token = false) | |
| { | |
| if ($force_renew_token || !self::hasValidToken()) | |
| { | |
| self::renewToken(); | |
| } | |
| return $_SESSION['csrf']['token']; | |
| } | |
| public static function checkTokenValidity($untrusted_token = null, $allowed_methods = array('GET')) | |
| { | |
| if (in_array($_SERVER['REQUEST_METHOD'], $allowed_methods)) | |
| { | |
| return true; | |
| } | |
| if ( ! self::hasValidToken()) | |
| { | |
| return false; | |
| } | |
| $untrusted_token = ($untrusted_token ?: $_POST['csrf-token']) ?: $_SERVER['HTTP_CSRF_TOKEN']; | |
| $isValidToken = $untrusted_token === self::getToken(); | |
| return $isValidToken; | |
| } | |
| private static function hasValidToken() | |
| { | |
| if ( ! array_key_exists('csrf', $_SESSION)) | |
| { | |
| return false; | |
| } | |
| $hasToken = $_SESSION['csrf']['token']; | |
| $isNotExpired = time() < $_SESSION['csrf']['expires_at']; | |
| return $hasToken && $isNotExpired; | |
| } | |
| /** | |
| * @param int $lifetime: token lifetime in seconds | |
| */ | |
| private static function renewToken($lifetime = 3600) | |
| { | |
| $hash = sha1(uniqid(mt_rand()) . self::$salt); | |
| $token = base_convert($hash, 16, 36); | |
| $expires_at = time() + $lifetime; | |
| $_SESSION['csrf'] = array( | |
| 'token' => $token, | |
| 'expires_at' => $expires_at | |
| ); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment