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<?php |
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declare(strict_types=1); |
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namespace SamIT\Yii2\UrlSigner; |
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use yii\base\Component; |
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use yii\base\InvalidConfigException; |
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use yii\helpers\StringHelper; |
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class UrlSigner extends Component |
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{ |
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/** |
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* @var string The name of the URL param for the HMAC |
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*/ |
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public $hmacParam = 'hmac'; |
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/** |
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* @var string The name of the URL param for the parameters |
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*/ |
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public $paramsParam = 'params'; |
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/** |
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* @var string The name of the URL param for the expiration date time |
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*/ |
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public $expirationParam = 'expires'; |
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/** |
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* Note that expiration dates cannot be disabled. If you really need to you can set a longer duration for the links. |
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* @var \DateInterval The default interval for link validity (default: 1 week) |
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*/ |
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private $_defaultExpirationInterval; |
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/** |
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* Stores the current timestamp, primarily used for testing. |
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* @var int |
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*/ |
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private $_currentTimestamp; |
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/** |
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* @var string |
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*/ |
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public $secret; |
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public function init(): void |
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{ |
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parent::init(); |
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if (!isset($this->_defaultExpirationInterval)) { |
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$this->setDefaultExpirationInterval('P7D'); |
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} |
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if (empty($this->secret) |
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|| empty($this->hmacParam) |
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|| empty($this->paramsParam) |
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|| empty($this->expirationParam) |
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) { |
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throw new InvalidConfigException('The following configuration params are required: secret, hmacParam, paramsParam and expirationParam'); |
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} |
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} |
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public function setDefaultExpirationInterval(string $interval): void |
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{ |
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$this->_defaultExpirationInterval = new \DateInterval($interval); |
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} |
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public function setCurrentTimestamp(?int $time): void |
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{ |
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$this->_currentTimestamp = $time; |
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} |
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/** |
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* Calculates the HMAC for a URL. |
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**/ |
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public function calculateHMAC( |
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array $params, |
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string $route |
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): string { |
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if (isset($params[0])) { |
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unset($params[0]); |
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} |
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\ksort($params); |
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$hash = \hash_hmac('sha256', |
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\trim($route, '/') . '|' . \implode('#', $params), |
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$this->secret, |
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true |
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); |
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return $this->urlEncode($hash); |
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} |
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/** |
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* This adds an HMAC to a list of query params. |
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* If |
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* @param array $queryParams List of query parameters |
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* @param bool $allowAddition Whether to allow extra parameters to be added. |
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* @throws \Exception |
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* @return void |
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*/ |
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public function signParams( |
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array &$queryParams, |
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$allowAddition = true, |
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?\DateTimeInterface $expiration = null |
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): void { |
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if (isset($queryParams[$this->hmacParam])) { |
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throw new \RuntimeException("HMAC param is already present"); |
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} |
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$route = $queryParams[0]; |
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if (\strncmp($route, '/', 1) !== 0) { |
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throw new \RuntimeException("Route must be absolute (start with /)"); |
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} |
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$this->addExpiration($queryParams, $expiration); |
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if ($allowAddition) { |
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$this->addParamKeys($queryParams); |
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} |
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$queryParams[$this->hmacParam] = $this->calculateHMAC($queryParams, $route); |
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} |
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/** |
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* Adds the expiration param if needed. |
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*/ |
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private function addExpiration(array &$params, ?\DateTimeInterface $expiration = null): void |
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{ |
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if (!empty($this->expirationParam)) { |
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if (!isset($expiration)) { |
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$expiration = (new \DateTime('@' . $this->time()))->add($this->_defaultExpirationInterval); |
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} |
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$params[$this->expirationParam] = $expiration->getTimestamp(); |
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} |
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} |
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private function time(): int |
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{ |
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return $this->_currentTimestamp ?? \time(); |
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} |
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private function checkExpiration(array $params): bool |
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{ |
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// Check expiration date. |
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return !isset($params[$this->expirationParam]) || $params[$this->expirationParam] > $this->time(); |
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} |
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/** |
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* Adds the keys of all params to the param array so it is included for signing. |
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* @param array $params |
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*/ |
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private function addParamKeys(array &$params): void |
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{ |
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$keys = \array_keys($params); |
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if ($keys[0] === 0) { |
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unset($keys[0]); |
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} |
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$params[$this->paramsParam] = \implode(',', $keys); |
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} |
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/** |
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* Extracts the signed params from an array of params. |
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* @param array $params |
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* @return array |
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*/ |
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private function getSignedParams(array $params): array |
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{ |
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if (empty($params[$this->paramsParam])) { |
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// HMAC itself is never signed. |
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unset($params[$this->hmacParam]); |
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return $params; |
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} |
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$signedParams = []; |
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$signedParams[$this->paramsParam] = $params[$this->paramsParam]; |
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foreach(\explode(',', $params[$this->paramsParam]) as $signedParam) { |
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$signedParams[$signedParam] = $params[$signedParam] ?? null; |
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} |
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return $signedParams; |
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} |
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/** |
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* Verifies the params for a specific route. |
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* Checks that the HMAC is present and valid. |
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* Checks that the HMAC is not expired. |
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* @param array $params |
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* @throws \Exception |
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* @return bool |
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*/ |
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public function verify(array $params, string $route):bool |
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{ |
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if (!isset($params[$this->hmacParam])) { |
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return false; |
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} |
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$hmac = $params[$this->hmacParam]; |
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$signedParams = $this->getSignedParams($params); |
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$calculated = $this->calculateHMAC($signedParams, $route); |
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if (!\hash_equals($calculated, $hmac)) { |
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return false; |
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} |
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return $this->checkExpiration($params); |
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} |
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private function urlEncode(string $bytes): string |
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{ |
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return \trim(StringHelper::base64UrlEncode($bytes), '='); |
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} |
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} |
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