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<?php |
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declare(strict_types = 1); |
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namespace Zakirullin\Middlewares; |
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use Psr\Http\Server\MiddlewareInterface; |
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use Psr\Http\Server\RequestHandlerInterface; |
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use Psr\Http\Message\ServerRequestInterface; |
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use Psr\Http\Message\ResponseInterface; |
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use Middlewares\Utils\Factory; |
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class CSRF implements MiddlewareInterface |
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{ |
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/** |
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* @var callable |
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*/ |
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protected $getIdentityCallback; |
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/** |
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* @var string |
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*/ |
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protected $secret; |
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/** |
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* @var string |
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*/ |
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protected $attribute; |
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/** |
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* @var int |
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*/ |
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protected $ttl; |
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/** |
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* @var string |
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*/ |
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protected $algorithm; |
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protected const READ_METHODS = ['HEAD', 'GET', 'OPTIONS']; |
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protected const STATUS_ON_ERROR = 403; |
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protected const CERTIFICATE_SEPARATOR = ':'; |
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protected const ATTRIBUTE = 'csrf'; |
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protected const TTL = 60 * 20; |
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protected const ALGORITHM = 'ripemd160'; |
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/** |
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* @param callable $getIdentityCallback |
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* @param string $secret |
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* @param string $attribute |
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* @param int $ttl |
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* @param string $algorithm |
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*/ |
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public function __construct( |
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callable $getIdentityCallback, |
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string $secret, |
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string $attribute = self::ATTRIBUTE, |
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int $ttl = self::TTL, |
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string $algorithm = self::ALGORITHM |
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) { |
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$this->getIdentityCallback = $getIdentityCallback; |
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$this->secret = $secret; |
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$this->attribute = $attribute; |
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$this->ttl = $ttl; |
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$this->algorithm = $algorithm; |
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} |
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/** |
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* @param ServerRequestInterface $request |
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* @param RequestHandlerInterface $handler |
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* @return ResponseInterface |
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*/ |
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public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface |
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{ |
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$isWriteMethod = !in_array($request->getMethod(), static::READ_METHODS); |
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if ($isWriteMethod && !$this->isValid($request)) { |
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$response = Factory::createResponse(static::STATUS_ON_ERROR); |
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$response->getBody()->write('Invalid or missing CSRF token!'); |
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return $response; |
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} |
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$request = $this->add($request); |
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return $handler->handle($request); |
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} |
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/** |
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* @param ServerRequestInterface $request |
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* @return ServerRequestInterface $request |
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*/ |
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protected function add(ServerRequestInterface $request): ServerRequestInterface |
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{ |
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$identity = call_user_func($this->getIdentityCallback, $request); |
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if (!empty($identity)) { |
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$expireAt = time() + $this->ttl; |
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$certificate = $this->createCertificate($identity, $expireAt); |
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$signature = $this->signCertificate($certificate); |
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$signatureWithExpiration = implode(static::CERTIFICATE_SEPARATOR, [$expireAt, $signature]); |
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$request = $request->withAttribute($this->attribute, $signatureWithExpiration); |
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} |
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return $request; |
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} |
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/** |
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* @param ServerRequestInterface $request |
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* @return bool |
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*/ |
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protected function isValid(ServerRequestInterface $request): bool |
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{ |
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$token = trim($request->getParsedBody()[$this->attribute] ?? ''); |
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$parts = explode(static::CERTIFICATE_SEPARATOR, $token); |
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if (count($parts) > 1) { |
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list($expireAt, $signature) = explode(static::CERTIFICATE_SEPARATOR, $token); |
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$identity = call_user_func($this->getIdentityCallback, $request); |
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$certificate = $this->createCertificate($identity, (int)$expireAt); |
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$actualSignature = $this->signCertificate($certificate); |
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$isSignatureValid = hash_equals($actualSignature, $signature); |
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$isNotExpired = $expireAt > time(); |
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if ($isSignatureValid && $isNotExpired) { |
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return true; |
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} |
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} |
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return false; |
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} |
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/** |
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* @param string $identity |
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* @param int $expireAt |
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* @return string |
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*/ |
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protected function createCertificate(string $identity, int $expireAt): string |
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{ |
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return implode(static::CERTIFICATE_SEPARATOR, [$identity, $expireAt]); |
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} |
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/** |
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* @param string $certificate |
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* @return string |
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*/ |
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protected function signCertificate(string $certificate) |
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{ |
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return hash_hmac($this->algorithm, $certificate, $this->secret); |
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} |
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} |
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zakirullin /
csrf-middleware
