-
- /*
- * Functions used to protect against Cross-Site Request Forgery
- * The security token has to base on at least one value that an attacker can't know - here it's the session ID and the private key.
- * In this implementation, a security token is reusable (if the user submits a form, goes back and resubmits the form, maybe with small changes;
- * or if the security token is used for ajax-calls that happen several times), but only valid for a certain amout of time (3hours).
- * The "typename" seperates the security tokens of different types of forms. This could be relevant in the following case:
- * A security token is used to protekt a link from CSRF (e.g. the "delete this profile"-link).
- * If the new page contains by any chance external elements, then the used security token is exposed by the referrer.
- * Actually, important actions should not be triggered by Links / GET-Requests at all, but somethimes they still are,
- * so this mechanism brings in some damage control (the attacker would be able to forge a request to a form of this type, but not to forms of other types).
- */
- public static function get_form_security_token($typename = '')
- {
- $a = get_app();
-
- $timestamp = time();
- $sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $timestamp . $typename);
-
- return $timestamp . '.' . $sec_hash;
- }
-
- public static function check_form_security_token($typename = '', $formname = 'form_security_token')
- {
- $hash = null;
-
- if (!empty($_REQUEST[$formname])) {
- /// @TODO Careful, not secured!
- $hash = $_REQUEST[$formname];
- }
-
- if (!empty($_SERVER['HTTP_X_CSRF_TOKEN'])) {
- /// @TODO Careful, not secured!
- $hash = $_SERVER['HTTP_X_CSRF_TOKEN'];
- }
-
- if (empty($hash)) {
- return false;
- }
-
- $max_livetime = 10800; // 3 hours
-
- $a = get_app();
-
- $x = explode('.', $hash);
- if (time() > (IntVal($x[0]) + $max_livetime)) {
- return false;
- }
-
- $sec_hash = hash('whirlpool', $a->user['guid'] . $a->user['prvkey'] . session_id() . $x[0] . $typename);
-
- return ($sec_hash == $x[1]);
- }
-
- private static function check_form_security_std_err_msg()
- {
- return L10n::t("The form security token was not correct. This probably happened because the form has been opened for too long \x28>3 hours\x29 before submitting it.") . EOL;
- }
-
- public static function check_form_security_token_redirectOnErr($err_redirect, $typename = '', $formname = 'form_security_token')
- {
- if (!check_form_security_token($typename, $formname)) {
- $a = get_app();
- logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
- logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
- notice(check_form_security_std_err_msg());
- goaway(System::baseUrl() . $err_redirect);
- }
- }
-
- public static function check_form_security_token_ForbiddenOnErr($typename = '', $formname = 'form_security_token')
- {
- if (!check_form_security_token($typename, $formname)) {
- $a = get_app();
- logger('check_form_security_token failed: user ' . $a->user['guid'] . ' - form element ' . $typename);
- logger('check_form_security_token failed: _REQUEST data: ' . print_r($_REQUEST, true), LOGGER_DATA);
- header('HTTP/1.1 403 Forbidden');
- killme();
- }
- }