tuupola/branca-middleware

PSR-7 and PSR-15 Branca Authentication Middleware

0.6.0 2019-04-11 16:46 UTC

README

Latest Version Software License Build Status Coverage

This middleware implements Branca token authentication. Branca is similar to JWT but more secure and has smaller token size. The middleware can be used with any framework using PSR-7 or PSR-15 style middlewares. It has been tested with Slim Framework and Zend Expressive.

You might also be interested in reading Branca as an Alternative to JWT?

This middleware does not implement OAuth authorization server nor does it provide ways to generate, issue or store the authentication tokens. It only parses and authenticates a token when passed via header or cookie.

Install

Install latest version using composer.

$ composer require tuupola/branca-middleware

If using Apache add the following to the .htaccess file. Otherwise PHP wont have access to Authorization: Bearer header.

RewriteRule .* - [env=HTTP_AUTHORIZATION:%{HTTP:Authorization}]

Usage

Configuration options are passed as an array. The only mandatory parameter is 32 byte secret which is used for authenticating and encrypting the token.

For simplicity's sake examples show secret hardcoded in code. In real life you should store it somewhere else. Good option is environment variable. You can use dotenv or something similar for development. Examples assume you are using Slim Framework.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

An example where your secret is stored as an environment variable:

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => getenv("BRANCA_SECRET")
]));

When a request is made, the middleware tries to validate and decode the token. If a token is not found or there is an error when validating and decoding it, the server will respond with 401 Unauthorized.

Validation errors are triggered when the token has been tampered with or optionally if the token has expired.

Optional parameters

Path

The optional path parameter allows you to specify the protected part of your website. It can be either a string or an array. You do not need to specify each URL. Instead think of path setting as a folder. In the example below everything starting with /api will be authenticated. If you do not define path all routes will be protected.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "path" => "/api", /* or ["/api", "/admin"] */
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Ignore

With optional ignore parameter you can make exceptions to path parameter. In the example below everything starting with /api and /admin will be authenticated with the exception of /api/token and /admin/ping which will not be authenticated.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "path" => ["/api", "/admin"],
    "ignore" => ["/api/token", "/admin/ping"],
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

TTL

Branca tokens have a creation timestamp embedded in the header. You can control how old token your application accepts with the ttl parameter.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "ttl" => 3600, /* 60 minutes */
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Header

By default middleware tries to find the token from Authorization header. You can change header name using the header parameter.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "header" => "X-Token",
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Regexp

By default the middleware assumes the value of the header is in Bearer <token> format. You can change this behaviour with regexp parameter. For example if you have custom header such as X-Token: <token> you should pass both header and regexp parameters.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "header" => "X-Token",
    "regexp" => "/(.*)/",
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Cookie

If token is not found from neither environment or header, the middleware tries to find it from cookie named token. You can change cookie name using cookie parameter.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "cookie" => "nekot",
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Logger

The optional logger parameter allows you to pass in a PSR-3 compatible logger to help with debugging or other application logging needs.

use Monolog\Logger;
use Monolog\Handler\RotatingFileHandler;

$app = new Slim\App;

$logger = new Logger("slim");
$rotating = new RotatingFileHandler(__DIR__ . "/logs/slim.log", 0, Logger::DEBUG);
$logger->pushHandler($rotating);

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "path" => "/api",
    "logger" => $logger,
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Before

Before funcion is called only when authentication succeeds but before the next incoming middleware is called. You can use this to alter the request before passing it to the next incoming middleware in the stack. If it returns anything else than Psr\Http\Message\RequestInterface the return value will be ignored.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => "supersecretkeyyoushouldnotcommit",
    "before" => function ($request, $arguments) {
        return $request->withAttribute("test", "test");
    }
]));

After

After function is called only when authentication succeeds and after the incoming middleware stack has been called. You can use this to alter the response before passing it next outgoing middleware in the stack. If it returns anything else than Psr\Http\Message\ResponseInterface the return value will be ignored.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => "supersecretkeyyoushouldnotcommit",
    "after" => function ($response, $arguments) {
        return $response->withHeader("X-Brawndo", "plants crave");
    }
]));

Error

Error is called when authentication fails. It receives last error message in arguments. You can use this for example to return JSON formatted error responses.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => "supersecretkeyyoushouldnotcommit",
    "error" => function ($request, $response, $arguments) {
        $data["status"] = "error";
        $data["message"] = $arguments["message"];
        return $response
            ->withHeader("Content-Type", "application/json")
            ->write(json_encode($data, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT));
    }
]));

Rules

The optional rules parameter allows you to pass in rules which define whether the request should be authenticated or not. A rule is a callable which receives the request as parameter. If any of the rules returns boolean false the request will not be authenticated.

By default middleware configuration looks like this. All paths are authenticated with all request methods except OPTIONS.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "rules" => [
        new Tuupola\Middleware\BrancaAuthentication\RequestPathRule([
            "path" => "/",
            "ignore" => []
        ]),
        new Tuupola\Middleware\BrancaAuthentication\RequestMethodRule([
            "ignore" => ["OPTIONS"]
        ])
    ]
]));

RequestPathRule contains both a path parameter and a ignore parameter. Latter contains paths which should not be authenticated. RequestMethodRule contains ignore parameter of request methods which also should not be authenticated. Think of ignore as a whitelist.

99% of the cases you do not need to use the rules parameter. It is only provided for special cases when defaults do not suffice.

Security

Branca tokens are essentially passwords. You should treat them as such and you should always use HTTPS. If the middleware detects insecure usage over HTTP it will throw a RuntimeException. This rule is relaxed for requests on localhost. To allow insecure usage you must enable it manually by setting secure to false.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secure" => false,
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Alternatively you can list your development host to have relaxed security.

$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secure" => true,
    "relaxed" => ["localhost", "dev.example.com"],
    "secret" => "supersecretkeyyoushouldnotcommit"
]));

Authorization

By default middleware only authenticates. This is not very interesting by itself. Beauty of Branca is that you can pass extra data in the token. This data can include for example scope which can be used for authorization.

It is up to you to implement how token data is stored or possible authorization implemented.

Let assume you have JSON encoded payload which includes requested scope and uid. Using the before callback you can inject the unencoded payload to the request object.

[
    "uid" => 123,
    "scope" => ["read", "write", "delete"]
]
$app->add(new Tuupola\Middleware\BrancaAuthentication([
    "secret" => "supersecretkeyyoushouldnotcommit",
    "before" => function ($request, $arguments) {
        $payload = json_decode($arguments["payload"], true);
        return $request->withAttribute("token", $payload);
    }
]));

$app->delete("/item/{id}", function ($request, $response, $arguments) {
    if (in_array("delete", $request->token->scope)) {
        /* Code for deleting item */
    } else {
        /* No scope so respond with 401 Unauthorized */
        return $response->withStatus(401);
    }
});

Testing

You can run tests either manually or automatically on every code change. Automatic tests require entr to work.

$ make test
$ brew install entr
$ make watch

Contributing

Please see CONTRIBUTING for details.

Security

If you discover any security related issues, please email tuupola@appelsiini.net instead of using the issue tracker.

License

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