Created Rest module

module/Rest/src/Middleware/CrossDomainMiddleware.php

@@ -0,0 +1,52 @@
+<?php
+namespace Shlinkio\Shlink\Rest\Middleware;
+
+use Psr\Http\Message\ResponseInterface as Response;
+use Psr\Http\Message\ServerRequestInterface as Request;
+use Zend\Stratigility\MiddlewareInterface;
+
+class CrossDomainMiddleware implements MiddlewareInterface
+{
+    /**
+     * Process an incoming request and/or response.
+     *
+     * Accepts a server-side request and a response instance, and does
+     * something with them.
+     *
+     * If the response is not complete and/or further processing would not
+     * interfere with the work done in the middleware, or if the middleware
+     * wants to delegate to another process, it can use the `$out` callable
+     * if present.
+     *
+     * If the middleware does not return a value, execution of the current
+     * request is considered complete, and the response instance provided will
+     * be considered the response to return.
+     *
+     * Alternately, the middleware may return a response instance.
+     *
+     * Often, middleware will `return $out();`, with the assumption that a
+     * later middleware will return a response.
+     *
+     * @param Request $request
+     * @param Response $response
+     * @param null|callable $out
+     * @return null|Response
+     */
+    public function __invoke(Request $request, Response $response, callable $out = null)
+    {
+        /** @var Response $response */
+        $response = $out($request, $response);
+
+        if (strtolower($request->getMethod()) === 'options') {
+            $response = $response->withHeader('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE, OPTIONS')
+                                 ->withHeader('Access-Control-Max-Age', '1000')
+                                 ->withHeader(
+                                     // Allow all requested headers
+                                     'Access-Control-Allow-Headers',
+                                     $request->getHeaderLine('Access-Control-Request-Headers')
+                                 );
+        }
+
+        return $response->withHeader('Access-Control-Allow-Origin', '*');
+    }
+}