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Direktori : /home2/selectio/public_html/a1tex.in/vendor/stripe/stripe-php/lib/ |
Current File : /home2/selectio/public_html/a1tex.in/vendor/stripe/stripe-php/lib/WebhookSignature.php |
<?php namespace Stripe; abstract class WebhookSignature { const EXPECTED_SCHEME = 'v1'; /** * Verifies the signature header sent by Stripe. Throws an * Exception\SignatureVerificationException exception if the verification fails for * any reason. * * @param string $payload the payload sent by Stripe * @param string $header the contents of the signature header sent by * Stripe * @param string $secret secret used to generate the signature * @param int $tolerance maximum difference allowed between the header's * timestamp and the current time * * @throws Exception\SignatureVerificationException if the verification fails * * @return bool */ public static function verifyHeader($payload, $header, $secret, $tolerance = null) { // Extract timestamp and signatures from header $timestamp = self::getTimestamp($header); $signatures = self::getSignatures($header, self::EXPECTED_SCHEME); if (-1 === $timestamp) { throw Exception\SignatureVerificationException::factory( 'Unable to extract timestamp and signatures from header', $payload, $header ); } if (empty($signatures)) { throw Exception\SignatureVerificationException::factory( 'No signatures found with expected scheme', $payload, $header ); } // Check if expected signature is found in list of signatures from // header $signedPayload = "{$timestamp}.{$payload}"; $expectedSignature = self::computeSignature($signedPayload, $secret); $signatureFound = false; foreach ($signatures as $signature) { if (Util\Util::secureCompare($expectedSignature, $signature)) { $signatureFound = true; break; } } if (!$signatureFound) { throw Exception\SignatureVerificationException::factory( 'No signatures found matching the expected signature for payload', $payload, $header ); } // Check if timestamp is within tolerance if (($tolerance > 0) && (\abs(\time() - $timestamp) > $tolerance)) { throw Exception\SignatureVerificationException::factory( 'Timestamp outside the tolerance zone', $payload, $header ); } return true; } /** * Extracts the timestamp in a signature header. * * @param string $header the signature header * * @return int the timestamp contained in the header, or -1 if no valid * timestamp is found */ private static function getTimestamp($header) { $items = \explode(',', $header); foreach ($items as $item) { $itemParts = \explode('=', $item, 2); if ('t' === $itemParts[0]) { if (!\is_numeric($itemParts[1])) { return -1; } return (int) ($itemParts[1]); } } return -1; } /** * Extracts the signatures matching a given scheme in a signature header. * * @param string $header the signature header * @param string $scheme the signature scheme to look for * * @return array the list of signatures matching the provided scheme */ private static function getSignatures($header, $scheme) { $signatures = []; $items = \explode(',', $header); foreach ($items as $item) { $itemParts = \explode('=', $item, 2); if (\trim($itemParts[0]) === $scheme) { $signatures[] = $itemParts[1]; } } return $signatures; } /** * Computes the signature for a given payload and secret. * * The current scheme used by Stripe ("v1") is HMAC/SHA-256. * * @param string $payload the payload to sign * @param string $secret the secret used to generate the signature * * @return string the signature as a string */ private static function computeSignature($payload, $secret) { return \hash_hmac('sha256', $payload, $secret); } }