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<?php |
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declare(strict_types=1); |
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namespace TheCodingMachine\Middlewares; |
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use Interop\Http\ServerMiddleware\DelegateInterface; |
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use Interop\Http\ServerMiddleware\MiddlewareInterface; |
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use Psr\Http\Message\ResponseInterface; |
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use Psr\Http\Message\ServerRequestInterface; |
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use TheCodingMachine\Middlewares\SafeRequests\IsSafeHttpRequestInterface; |
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/** |
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* This class will check that all POST/PUT/DELETE... requests and verify that the "Origin" of the request is your own website. |
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*/ |
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final class CsrfHeaderCheckMiddleware implements MiddlewareInterface |
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{ |
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/** |
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* @var IsSafeHttpRequestInterface |
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*/ |
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private $isSafeHttpRequest; |
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public function __construct(IsSafeHttpRequestInterface $isSafeHttpRequest) |
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{ |
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$this->isSafeHttpRequest = $isSafeHttpRequest; |
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} |
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/** |
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* Process an incoming server request and return a response, optionally delegating |
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* to the next middleware component to create the response. |
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* |
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* @param ServerRequestInterface $request |
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* @param DelegateInterface $delegate |
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* @return ResponseInterface |
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* @throws CsrfHeaderCheckMiddlewareException |
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*/ |
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public function process(ServerRequestInterface $request, DelegateInterface $delegate) |
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{ |
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$isSafeHttpRequest = $this->isSafeHttpRequest; |
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if (!$isSafeHttpRequest($request)) { |
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$source = $this->getSourceOrigin($request); |
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$target = $this->getTargetOrigin($request); |
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if ($source !== $target) { |
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throw new CsrfHeaderCheckMiddlewareException('Potential CSRF attack stopped. Source origin and target origin do not match.'); |
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} |
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} |
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return $delegate->process($request); |
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} |
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private function getSourceOrigin(ServerRequestInterface $request): string |
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{ |
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$source = $this->getHeaderLine($request, 'ORIGIN'); |
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if (null !== $source) { |
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return parse_url($source, PHP_URL_HOST); |
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} |
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$referrer = $this->getHeaderLine($request, 'REFERER'); |
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if (null === $referrer) { |
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throw new CsrfHeaderCheckMiddlewareException('Could not find neither the ORIGIN header nor the REFERER header in the HTTP request.'); |
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} |
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return parse_url($referrer, PHP_URL_HOST); |
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} |
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private function getTargetOrigin(ServerRequestInterface $request): string |
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{ |
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$host = $this->getHeaderLine($request, 'X-FORWARDED-HOST'); |
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if (null === $host) { |
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$host = $this->getHeaderLine($request, 'HOST'); |
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} |
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if (null === $host) { |
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throw new CsrfHeaderCheckMiddlewareException('Could not find the HOST header in the HTTP request.'); |
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} |
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return $this->removePortFromHost($host); |
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} |
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private function removePortFromHost(string $host) |
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{ |
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return parse_url('http://'.$host, PHP_URL_HOST); |
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} |
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/** |
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* Returns the header, throws an exception if the header is specified more that one in the request. |
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* Returns null if nothing found. |
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* |
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* @param ServerRequestInterface $request |
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* @param string $header |
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* @return string|null |
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* @throws CsrfHeaderCheckMiddlewareException |
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*/ |
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private function getHeaderLine(ServerRequestInterface $request, string $header) |
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{ |
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$values = $request->getHeader($header); |
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if (count($values) > 1) { |
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throw new CsrfHeaderCheckMiddlewareException("Unexpected request: more than one $header header sent."); |
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} |
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if (count($values) === 1) { |
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return $values[0]; |
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} |
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return null; |
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} |
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} |
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thecodingmachine /
csrf-header-check-middleware
