# Stack/Cors

Library and middleware enabling cross-origin resource sharing for your
http-{foundation,kernel} using application. It attempts to implement the
[W3C Recommendation] for cross-origin resource sharing.

[W3C Recommendation]: http://www.w3.org/TR/cors/

Build status: ![.github/workflows/run-tests.yml](https://github.com/asm89/stack-cors/workflows/.github/workflows/run-tests.yml/badge.svg)

## Installation

Require `asm89/stack-cors` using composer.

## Usage

This package can be used as a library or as [stack middleware].

[stack middleware]: http://stackphp.com/

### Options

| Option                 | Description                                                | Default value |
|------------------------|------------------------------------------------------------|---------------|
| `allowedMethods`         | Matches the request method.                                | `[]`          |
| `allowedOrigins`         | Matches the request origin.                                | `[]`          |
| `allowedOriginsPatterns` | Matches the request origin with `preg_match`.              | `[]`          |
| `allowedHeaders`         | Sets the Access-Control-Allow-Headers response header.     | `[]`          |
| `exposedHeaders`         | Sets the Access-Control-Expose-Headers response header.    | `false`       |
| `maxAge`                 | Sets the Access-Control-Max-Age response header.<br/>Set to `null` to omit the header/use browser default.           | `0`       |
| `supportsCredentials`    | Sets the Access-Control-Allow-Credentials header.          | `false`       |

The _allowedMethods_ and _allowedHeaders_ options are case-insensitive.

You don't need to provide both _allowedOrigins_ and _allowedOriginsPatterns_. If one of the strings passed matches, it is considered a valid origin.

If `['*']` is provided to _allowedMethods_, _allowedOrigins_ or _allowedHeaders_ all methods / origins / headers are allowed.

If _supportsCredentials_ is `true`, you must [explicitly set](https://fetch.spec.whatwg.org/#cors-protocol-and-credentials) `allowedHeaders` for any headers which are not CORS safelisted.

### Example: using the library

```php
<?php

use Asm89\Stack\CorsService;

$cors = new CorsService([
    'allowedHeaders'         => ['x-allowed-header', 'x-other-allowed-header'],
    'allowedMethods'         => ['DELETE', 'GET', 'POST', 'PUT'],
    'allowedOrigins'         => ['http://localhost'],
    'allowedOriginsPatterns' => ['/localhost:\d/'],
    'exposedHeaders'         => false,
    'maxAge'                 => 600,
    'supportsCredentials'    => true,
]);

$cors->addActualRequestHeaders(Response $response, $origin);
$cors->handlePreflightRequest(Request $request);
$cors->isActualRequestAllowed(Request $request);
$cors->isCorsRequest(Request $request);
$cors->isPreflightRequest(Request $request);
```

## Example: using the stack middleware

```php
<?php

use Asm89\Stack\Cors;

$app = new Cors($app, [
    // you can use ['*'] to allow any headers
    'allowedHeaders'      => ['x-allowed-header', 'x-other-allowed-header'],
    // you can use ['*'] to allow any methods
    'allowedMethods'      => ['DELETE', 'GET', 'POST', 'PUT'],
    // you can use ['*'] to allow requests from any origin
    'allowedOrigins'      => ['localhost'],
    // you can enter regexes that are matched to the origin request header
    'allowedOriginsPatterns' => ['/localhost:\d/'],
    'exposedHeaders'      => false,
    'maxAge'              => 600,
    'supportsCredentials' => false,
]);
```