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<?php |
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namespace Schnittstabil\Csrf\TokenService; |
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use Base64Url\Base64Url; |
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/** |
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* A TokenValidator. |
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*/ |
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class TokenValidator |
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{ |
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protected $sign; |
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protected $base64url; |
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/** |
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* Create a new TokenValidator. |
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* |
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* @param callable $sign Callable used for generating the token signatures |
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*/ |
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public function __construct(callable $sign) |
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{ |
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$this->sign = $sign; |
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$this->base64url = new Base64Url(); |
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} |
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/** |
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* Determine constraint violations of a CSRF token. |
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* |
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* @param string $nonce Value used to associate a client session |
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* @param string $token The token to validate |
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* @param int $now The current time, defaults to `time()` |
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* @param int $leeway The leeway in seconds |
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* |
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* @return InvalidArgumentException[] Constraint violations; if $token is valid, an empty array |
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*/ |
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public function __invoke($nonce, $token, $now = null, $leeway = 0) |
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{ |
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$parseResult = $this->parse($token); |
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if ($violations = $parseResult->violations) { |
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return $violations; |
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} |
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return $this->validatePayload($nonce, $parseResult->payload, $now, $leeway); |
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} |
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/** |
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* Parse a CSRF token. |
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* |
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* @param string $token The token to parse |
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* |
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* @return \stdClass Parse result containing payload and constraint violations |
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*/ |
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protected function parse($token) |
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{ |
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$result = new \stdClass(); |
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$result->violations = []; |
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$result->payload = null; |
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$segments = explode('.', $token); |
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if (count($segments) !== 2) { |
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$result->violations[] = new \InvalidArgumentException('Wrong number of segments'); |
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return $result; |
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} |
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list($payloadBase64, $signature) = $segments; |
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$sign = $this->sign; |
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if ($signature !== $sign($payloadBase64)) { |
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$result->violations[] = new \InvalidArgumentException('Signature verification failed'); |
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} |
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$result->payload = json_decode($this->base64url->decode($payloadBase64)); |
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if (!($result->payload instanceof \stdClass)) { |
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$result->violations[] = new \InvalidArgumentException('Invalid payload encoding'); |
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} |
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return $result; |
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} |
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/** |
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* Validate the payload of a CSRF token. |
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* |
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* @param string $nonce Value used to associate a client session |
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* @param \stdClass $payload The token payload to validate |
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* @param int $now The current time, defaults to `time()` |
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* @param int $leeway The leeway in seconds |
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* |
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* @return InvalidArgumentException[] Constraint violations; if $payload is valid, an empty array |
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*/ |
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protected function validatePayload($nonce, \stdClass $payload, $now = null, $leeway = 0) |
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{ |
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$now = $now ?: time(); |
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$violations = []; |
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View Code Duplication |
if ($payload->exp + $leeway <= $now) { |
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$exp = date(\DateTime::ISO8601, $payload->exp); |
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$violations[] = new \InvalidArgumentException('Token already expired at '.$exp); |
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} |
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View Code Duplication |
if ($now + $leeway < $payload->iat) { |
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$issuedAt = date(\DateTime::ISO8601, $payload->iat); |
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$violations[] = new \InvalidArgumentException('Cannot handle token prior to '.$issuedAt); |
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} |
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if ($payload->nonce !== $nonce) { |
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$violations[] = new \InvalidArgumentException('Nonce mismatch'); |
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} |
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return $violations; |
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} |
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} |
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