1 files changed, 140 insertions, 0 deletions
diff --git a/vendor/stripe/stripe-php/lib/WebhookSignature.php b/vendor/stripe/stripe-php/lib/WebhookSignature.php
new file mode 100644
index 0000000..46cbb28
--- /dev/null
+++ b/vendor/stripe/stripe-php/lib/WebhookSignature.php
@@ -0,0 +1,140 @@
+<?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);
+    }
+}