ReactPHP Cors Middleware

This middleware implements Cross-origin resource sharing for ReactPHP. This repository got mainly inspired by tuupola/cors-middleware. Additional configuration ideas got taken from barryvdh/laravel-cors and nelmio/NelmioCorsBundle. The internal heavy lifting is done by neomerx/cors-psr7 library.

Install

To install via Composer, use the command below, it will automatically detect the latest version and bind it with ^.

composer require christoph-kluge/reactphp-http-cors-middleware

This middleware will detect CORS requests and will intercept the request if there is something invalid.

Usage

$server = new Server([
    new CorsMiddleware(),
    function (ServerRequestInterface $request, callable $next) {
        return new Response(200, ['Content-Type' => 'text/html'], 'We test CORS');
    },
]);

Configuration

The defaults for this middleware are mainly taken from enable-cors.org.

Available configuration options

Thanks to expressjs/cors#configuring-cors. As I took most configuration descriptions from there.

• server_url: can be used to set enable strict Host header checks to avoid malicious use of our server. (default: null)
• response_code: can be used to set the HTTP-StatusCode on a successful OPTIONS / Pre-Flight-Request (default: 204)
• allow_credentials: Configures the Access-Control-Allow-Credentials CORS header. Expects an boolean (ex: true // to set the header)
• allow_origin: Configures the Access-Control-Allow-Origin CORS header. Expects an array (ex: ['http://example.net', 'https://example.net']).
• allow_origin_callback: Will set allow_origin to an empty array [] and use the callback on a per-request base. The first parameter is an instance of ParsedUrlInterface and the callback is expected to return an boolean.
• allow_methods: Configures the Access-Control-Allow-Methods CORS header. Expects an array (ex: ['GET', 'PUT', 'POST']).
• allow_headers: Configures the Access-Control-Allow-Headers CORS header. Expects an array (ex: ['Content-Type', 'Authorization']).
• expose_headers: Configures the Access-Control-Expose-Headers CORS header. Expects an array (ex: ['Content-Range', 'X-Content-Range']).
• max_age: Configures the Access-Control-Max-Age CORS header. Expects an integer representing seconds (ex: 1728000 // 20 days)

Default Settings (Allow All CORS Requests)

$settings = [
    'allow_credentials' => true,
    'allow_origin'      => ['*'],
    'allow_methods'     => ['GET', 'POST', 'PUT', 'DELETE', 'HEAD', 'OPTIONS'],
    'allow_headers'     => ['DNT','X-Custom-Header','Keep-Alive','User-Agent','X-Requested-With','If-Modified-Since','Cache-Control','Content-Type','Content-Range','Range'],
    'expose_headers'    => ['DNT','X-Custom-Header','Keep-Alive','User-Agent','X-Requested-With','If-Modified-Since','Cache-Control','Content-Type','Content-Range','Range'],
    'max_age'           => 60 * 60 * 24 * 20, // preflight request is valid for 20 days
];

Allow specific origins (Origin requires scheme, host and optionally port)

$server = new Server([
    new CorsMiddleware([
        'allow_origin' => [
            'http://www.example.net',
            'https://www.example.net',
            'http://www.example.net:8443',
        ],
    ]),
]);

Allow origins on a per-request base (callback)

$server = new Server([
    new CorsMiddleware([
        'allow_origin'          => [],
        'allow_origin_callback' => function(ParsedUrlInterface $origin) {
            // do some evaluation magic with origin ..
            return true;
        },
    ]),
]);

Use custom response code on pre-flight requests

Some legacy browsers choke on 204. Thanks to expressjs/cors#configuring-cors for that.

$server = new Server([
    new CorsMiddleware([
        'response_code' => 200,
    ]),
]);

Use strict host checking

The default handling of this middleware will allow any "Host"-header. This means that you can use your server with any hostname you want. This might be a desired behavior but allows also the misuse of your server.

To prevent such a behavior there is a server_url option which will enable strict host checking. In this scenario the server will return a 403 with the body Origin not allowed.

$server = new Server([
    new CorsMiddleware([
        'server_url' => 'http://api.example.net:8080'
    ]),
]);

License

The MIT License (MIT)

Copyright (c) 2017 Christoph Kluge

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.