framework/filters/Cors.php
<?php
/**
* @link https://www.yiiframework.com/
* @copyright Copyright (c) 2008 Yii Software LLC
* @license https://www.yiiframework.com/license/
*/
namespace yii\filters;
use Yii;
use yii\base\ActionFilter;
use yii\base\InvalidConfigException;
use yii\web\Request;
use yii\web\Response;
/**
* Cors filter implements [Cross Origin Resource Sharing](https://en.wikipedia.org/wiki/Cross-origin_resource_sharing).
*
* Make sure to read carefully what CORS does and does not. CORS do not secure your API,
* but allow the developer to grant access to third party code (ajax calls from external domain).
*
* You may use CORS filter by attaching it as a behavior to a controller or module, like the following,
*
* ```php
* public function behaviors()
* {
* return [
* 'corsFilter' => [
* 'class' => \yii\filters\Cors::class,
* ],
* ];
* }
* ```
*
* The CORS filter can be specialized to restrict parameters, like this,
* [MDN CORS Information](https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS)
*
* ```php
* public function behaviors()
* {
* return [
* 'corsFilter' => [
* 'class' => \yii\filters\Cors::class,
* 'cors' => [
* // restrict access to
* 'Origin' => ['http://www.myserver.com', 'https://www.myserver.com'],
* // Allow only POST and PUT methods
* 'Access-Control-Request-Method' => ['POST', 'PUT'],
* // Allow only headers 'X-Wsse'
* 'Access-Control-Request-Headers' => ['X-Wsse'],
* // Allow credentials (cookies, authorization headers, etc.) to be exposed to the browser
* 'Access-Control-Allow-Credentials' => true,
* // Allow OPTIONS caching
* 'Access-Control-Max-Age' => 3600,
* // Allow the X-Pagination-Current-Page header to be exposed to the browser.
* 'Access-Control-Expose-Headers' => ['X-Pagination-Current-Page'],
* ],
*
* ],
* ];
* }
* ```
*
* For more information on how to add the CORS filter to a controller, see
* the [Guide on REST controllers](guide:rest-controllers#cors).
*
* @author Philippe Gaultier <pgaultier@gmail.com>
* @since 2.0
*/
class Cors extends ActionFilter
{
/**
* @var Request|null the current request. If not set, the `request` application component will be used.
*/
public $request;
/**
* @var Response|null the response to be sent. If not set, the `response` application component will be used.
*/
public $response;
/**
* @var array define specific CORS rules for specific actions
*/
public $actions = [];
/**
* @var array Basic headers handled for the CORS requests.
*/
public $cors = [
'Origin' => ['*'],
'Access-Control-Request-Method' => ['GET', 'POST', 'PUT', 'PATCH', 'DELETE', 'HEAD', 'OPTIONS'],
'Access-Control-Request-Headers' => ['*'],
'Access-Control-Allow-Credentials' => null,
'Access-Control-Max-Age' => 86400,
'Access-Control-Expose-Headers' => [],
];
/**
* {@inheritdoc}
*/
public function beforeAction($action)
{
$this->request = $this->request ?: Yii::$app->getRequest();
$this->response = $this->response ?: Yii::$app->getResponse();
$this->overrideDefaultSettings($action);
$requestCorsHeaders = $this->extractHeaders();
$responseCorsHeaders = $this->prepareHeaders($requestCorsHeaders);
$this->addCorsHeaders($this->response, $responseCorsHeaders);
if ($this->request->isOptions && $this->request->headers->has('Access-Control-Request-Method')) {
// it is CORS preflight request, respond with 200 OK without further processing
$this->response->setStatusCode(200);
return false;
}
return true;
}
/**
* Override settings for specific action.
* @param \yii\base\Action $action the action settings to override
*/
public function overrideDefaultSettings($action)
{
if (isset($this->actions[$action->id])) {
$actionParams = $this->actions[$action->id];
$actionParamsKeys = array_keys($actionParams);
foreach ($this->cors as $headerField => $headerValue) {
if (in_array($headerField, $actionParamsKeys)) {
$this->cors[$headerField] = $actionParams[$headerField];
}
}
}
}
/**
* Extract CORS headers from the request.
* @return array CORS headers to handle
*/
public function extractHeaders()
{
$headers = [];
foreach (array_keys($this->cors) as $headerField) {
$serverField = $this->headerizeToPhp($headerField);
$headerData = isset($_SERVER[$serverField]) ? $_SERVER[$serverField] : null;
if ($headerData !== null) {
$headers[$headerField] = $headerData;
}
}
return $headers;
}
/**
* For each CORS headers create the specific response.
* @param array $requestHeaders CORS headers we have detected
* @return array CORS headers ready to be sent
*/
public function prepareHeaders($requestHeaders)
{
$responseHeaders = [];
// handle Origin
if (isset($requestHeaders['Origin'], $this->cors['Origin'])) {
if (in_array($requestHeaders['Origin'], $this->cors['Origin'], true)) {
$responseHeaders['Access-Control-Allow-Origin'] = $requestHeaders['Origin'];
}
if (in_array('*', $this->cors['Origin'], true)) {
// Per CORS standard (https://fetch.spec.whatwg.org), wildcard origins shouldn't be used together with credentials
if (isset($this->cors['Access-Control-Allow-Credentials']) && $this->cors['Access-Control-Allow-Credentials']) {
if (YII_DEBUG) {
throw new InvalidConfigException("Allowing credentials for wildcard origins is insecure. Please specify more restrictive origins or set 'credentials' to false in your CORS configuration.");
} else {
Yii::error("Allowing credentials for wildcard origins is insecure. Please specify more restrictive origins or set 'credentials' to false in your CORS configuration.", __METHOD__);
}
} else {
$responseHeaders['Access-Control-Allow-Origin'] = '*';
}
}
}
$this->prepareAllowHeaders('Headers', $requestHeaders, $responseHeaders);
if (isset($requestHeaders['Access-Control-Request-Method'])) {
$responseHeaders['Access-Control-Allow-Methods'] = implode(', ', $this->cors['Access-Control-Request-Method']);
}
if (isset($this->cors['Access-Control-Allow-Credentials'])) {
$responseHeaders['Access-Control-Allow-Credentials'] = $this->cors['Access-Control-Allow-Credentials'] ? 'true' : 'false';
}
if (isset($this->cors['Access-Control-Max-Age']) && $this->request->getIsOptions()) {
$responseHeaders['Access-Control-Max-Age'] = $this->cors['Access-Control-Max-Age'];
}
if (isset($this->cors['Access-Control-Expose-Headers'])) {
$responseHeaders['Access-Control-Expose-Headers'] = implode(', ', $this->cors['Access-Control-Expose-Headers']);
}
if (isset($this->cors['Access-Control-Allow-Headers'])) {
$responseHeaders['Access-Control-Allow-Headers'] = implode(', ', $this->cors['Access-Control-Allow-Headers']);
}
return $responseHeaders;
}
/**
* Handle classic CORS request to avoid duplicate code.
* @param string $type the kind of headers we would handle
* @param array $requestHeaders CORS headers request by client
* @param array $responseHeaders CORS response headers sent to the client
*/
protected function prepareAllowHeaders($type, $requestHeaders, &$responseHeaders)
{
$requestHeaderField = 'Access-Control-Request-' . $type;
$responseHeaderField = 'Access-Control-Allow-' . $type;
if (!isset($requestHeaders[$requestHeaderField], $this->cors[$requestHeaderField])) {
return;
}
if (in_array('*', $this->cors[$requestHeaderField])) {
$responseHeaders[$responseHeaderField] = $this->headerize($requestHeaders[$requestHeaderField]);
} else {
$requestedData = preg_split('/[\\s,]+/', $requestHeaders[$requestHeaderField], -1, PREG_SPLIT_NO_EMPTY);
$acceptedData = array_uintersect($requestedData, $this->cors[$requestHeaderField], 'strcasecmp');
if (!empty($acceptedData)) {
$responseHeaders[$responseHeaderField] = implode(', ', $acceptedData);
}
}
}
/**
* Adds the CORS headers to the response.
* @param Response $response
* @param array $headers CORS headers which have been computed
*/
public function addCorsHeaders($response, $headers)
{
if (empty($headers) === false) {
$responseHeaders = $response->getHeaders();
foreach ($headers as $field => $value) {
$responseHeaders->set($field, $value);
}
}
}
/**
* Convert any string (including php headers with HTTP prefix) to header format.
*
* Example:
* - X-PINGOTHER -> X-Pingother
* - X_PINGOTHER -> X-Pingother
* @param string $string string to convert
* @return string the result in "header" format
*/
protected function headerize($string)
{
$headers = preg_split('/[\\s,]+/', $string, -1, PREG_SPLIT_NO_EMPTY);
$headers = array_map(function ($element) {
return str_replace(' ', '-', ucwords(strtolower(str_replace(['_', '-'], [' ', ' '], $element))));
}, $headers);
return implode(', ', $headers);
}
/**
* Convert any string (including php headers with HTTP prefix) to header format.
*
* Example:
* - X-Pingother -> HTTP_X_PINGOTHER
* - X PINGOTHER -> HTTP_X_PINGOTHER
* @param string $string string to convert
* @return string the result in "php $_SERVER header" format
*/
protected function headerizeToPhp($string)
{
return 'HTTP_' . strtoupper(str_replace([' ', '-'], ['_', '_'], $string));
}
}