Slim Framework CSRF Protection

This repository contains a Slim Framework CSRF protection middleware. CSRF protection applies to all unsafe HTTP requests (POST, PUT, DELETE, PATCH).

You can fetch the latest CSRF token's name and value from the Request object with its getAttribute() method. By default, the CSRF token's name is stored in the csrf_name attribute, and the CSRF token's value is stored in the csrf_value attribute.

Install

Via Composer

$ composer require slim/csrf

Requires Slim 3.0.0 or newer.

Usage

In most cases you want to register Slim\Csrf for all routes, however, as it is middleware, you can also register it for a subset of routes.

Register for all routes

// Start PHP session
session_start();

$app = new \Slim\App();

// Register with container
$container = $app->getContainer();
$container['csrf'] = function ($c) {
    return new \Slim\Csrf\Guard;
};

// Register middleware for all routes
// If you are implementing per-route checks you must not add this
$app->add($container->get('csrf'));

$app->get('/foo', function ($req, $res, $args) {
    // CSRF token name and value
    $nameKey = $this->csrf->getTokenNameKey();
    $valueKey = $this->csrf->getTokenValueKey();
    $name = $req->getAttribute($nameKey);
    $value = $req->getAttribute($valueKey);

    // Render HTML form which POSTs to /bar with two hidden input fields for the
    // name and value:
    // <input type="hidden" name="<?= $nameKey ?>" value="<?= $name ?>">
    // <input type="hidden" name="<?= $valueKey ?>" value="<?= $value ?>">
});

$app->post('/bar', function ($req, $res, $args) {
    // CSRF protection successful if you reached
    // this far.
});

$app->run();

Register per route

// Start PHP session
session_start();

$app = new \Slim\App();

// Register with container
$container = $app->getContainer();
$container['csrf'] = function ($c) {
    return new \Slim\Csrf\Guard;
};

$app->get('/api/myEndPoint',function ($req, $res, $args) {
    $nameKey = $this->csrf->getTokenNameKey();
    $valueKey = $this->csrf->getTokenValueKey();
    $name = $req->getAttribute($nameKey);
    $value = $req->getAttribute($valueKey);

    $tokenArray = [
        $nameKey => $name,
        $valueKey => $value
    ]
    
    return $response->write(json_encode($tokenArray));
})->addMiddleware($container->get('csrf');

$app->post('/api/myEndPoint',function ($req, $res, $args) {
    //Do my Things Securely!
})->addMiddleware($container->get('csrf'));

$app->run();

Handling validation failure

By default, Slim\Csrf\Guard will return a Response with a 400 status code and a simple plain text error message.

To override this, provide a callable as the third parameter to the constructor or via setFailureCallable(). This callable has the same signature as middleware: function($request, $response, $next) and must return a Response.

For example:

$container['csrf'] = function ($c) {
    $guard = new \Slim\Csrf\Guard();
    $guard->setFailureCallable(function ($request, $response, $next) {
        $request = $request->withAttribute("csrf_status", false);
        return $next($request, $response);
    });
    return $guard;
};

In this example, an attribute is set on the request object that can then be checked in subsequent middleware or the route callable using:

if (false === $request->getAttribute('csrf_status')) {
    // display suitable error here
} else {
    // successfully passed CSRF check
}

Testing

$ phpunit

Contributing

Please see CONTRIBUTING for details.

Security

If you discover any security related issues, please email security@slimframework.com instead of using the issue tracker.

Credits

License

The MIT License (MIT). Please see License File for more information.

dopesong/Slim-Csrf