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<?php declare(strict_types=1); |
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namespace ncryptf; |
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use DateTime; |
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use ncryptf\Signature; |
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use ncryptf\Token; |
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final class Authorization |
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{ |
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/** |
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* The HMAC info parameter. Overwrite this class and redeclare to change. |
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*/ |
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const AUTH_INFO = 'HMAC|AuthenticationKey'; |
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/** |
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* The HMAC algorithm. Overwrite this class and redeclare to change. |
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*/ |
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const HMAC_ALGO = 'sha256'; |
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/** |
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* Token object containing the access token and initial key material |
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* |
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* @var Token |
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*/ |
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private $token; |
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/** |
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* 32 byte salt array |
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* |
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* @var string |
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*/ |
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private $salt; |
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/** |
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* RFC1123 representation of the date |
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* |
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* @var string |
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*/ |
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private $date; |
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/** |
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* The generated signature |
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* |
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* @var string |
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*/ |
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private $signature; |
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/** |
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* 32 byte HMAC |
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* |
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* @var string |
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*/ |
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private $hmac; |
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/** |
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* The header version to generate |
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* |
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* @var integer |
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*/ |
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private $version = 2; |
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/** |
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* Calculates the authorization header information |
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* |
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* @param string $httpMethod The HTTP method |
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* @param string $uri The full URI with query string parameters |
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* @param Token $token A token object containing the ikm, access token, and other authentication attributes |
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* @param DateTime $date The date |
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* @param array|string $payload Array representation of the payload |
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* @param integer $version The authorization version, by default this is 2 |
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* @param string $salt An optional fixed salt value |
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*/ |
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public function __construct(string $httpMethod, string $uri, Token $token, DateTime $date, $payload = '', int $version = 2, string $salt = null) |
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{ |
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$httpMethod = \strtoupper($httpMethod); |
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$this->salt = $salt ?? \random_bytes(32); |
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$this->signature = Signature::derive($httpMethod, $uri, $this->salt, $date, $payload, $version); |
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$hkdf = hash_hkdf(static::HMAC_ALGO, $token->ikm, 0, static::AUTH_INFO, $this->salt); |
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$this->hmac = \hash_hmac('sha256', $this->signature, \bin2hex($hkdf), true); |
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$this->version = $version; |
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$this->date = $date->format(\DateTime::RFC1123); |
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$this->token = $token; |
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} |
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/** |
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* Extracts the HMAC parameters from a header string |
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* |
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* @param string $hmacHeader |
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* @return array|boolean |
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*/ |
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public static function extractParamsFromHeaderString(string $hmacHeader = null) |
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{ |
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if ($hmacHeader !== null && preg_match('/^HMAC\s+(.*?)$/', $hmacHeader, $matches)) { |
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if (\strpos($matches[1], ',') !== false) { |
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$params = explode(',', trim($matches[1])); |
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if (count($params) !== 3) { |
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return false; |
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} |
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return [ |
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'access_token' => $params[0], |
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'hmac' => $params[1], |
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'salt' => $params[2], |
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'v' => 1, |
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'date' => null, |
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]; |
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} else { |
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$params = \json_decode(\base64_decode($matches[1]), true); |
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if (!isset($params['v']) || |
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!isset($params['access_token']) || |
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!isset($params['hmac']) || |
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!isset($params['salt']) || |
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!isset($params['v']) || |
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!isset($params['date']) |
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) { |
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return false; |
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} |
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return $params; |
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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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* Returns the signature string |
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* |
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* @return string |
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*/ |
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public function getSignatureString() : string |
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{ |
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return $this->signature; |
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} |
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/** |
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* Returns the generated HMAC |
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* |
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* @return string |
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*/ |
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public function getHMAC() : string |
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{ |
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return $this->hmac; |
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} |
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/** |
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* Returns the base64 encoded HMAC |
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* |
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* @return string |
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*/ |
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public function getEncodedHMAC() : string |
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{ |
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return \base64_encode($this->hmac); |
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} |
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/** |
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* Returns the base64 encoded salt |
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* |
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* @return string |
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*/ |
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public function getEncodedSalt() : string |
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{ |
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return \base64_encode($this->salt); |
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} |
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/** |
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* Returns an RFC1123 formatted date |
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* |
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* @return string |
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*/ |
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public function getDate() : string |
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{ |
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return $this->date; |
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} |
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/** |
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* Generates the versions HMAC header |
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* |
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* @return string |
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*/ |
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public function getHeader() : string |
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{ |
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$salt = $this->getEncodedSalt(); |
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$hmac = $this->getEncodedHMAC(); |
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if ($this->version === 2) { |
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$data = \base64_encode(\json_encode([ |
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'access_token' => $this->token->accessToken, |
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'date' => $this->date, |
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'hmac' => $hmac, |
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'salt' => $salt, |
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'v' => 2 |
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])); |
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return "HMAC {$data}"; |
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} |
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// The version 1 HMAC is returned by default |
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return "HMAC {$this->token->accessToken},{$hmac},{$salt}"; |
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} |
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/** |
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* Validates a provided HMAC against an auth object and a drift |
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* |
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* @param string $hmac byte[] HMAC |
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* @param self $auth Authorization object |
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* @param integer $driftAllowance |
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* @return boolean |
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*/ |
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public function verify(string $hmac, self $auth, int $driftAllowance = 90) : bool |
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{ |
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$drift = $this->getTimeDrift($auth->getDate()); |
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if ($drift === null || $drift >= $driftAllowance) { |
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return false; |
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} |
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try { |
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if (\sodium_memcmp($hmac, $auth->getHMAC()) === 0) { |
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return true; |
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} |
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} catch (\SodiumException $e) { |
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return false; |
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} |
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return false; |
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} |
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/** |
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* Calculates the time difference between now and the provided date |
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* |
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* @param string $date |
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* @return int|boolean |
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*/ |
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private function getTimeDrift(string $date) :? int |
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{ |
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$now = new \DateTime(); |
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$now->format(\DateTime::RFC1123); |
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try { |
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$realDate = new DateTime($date); |
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} catch (\Exception $e) { |
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return null; |
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} |
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return (int)\abs($now->getTimestamp() - $realDate->getTimestamp()); |
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} |
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} |
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