Merge pull request #120 from vapor-community/signature-helper

Add signature verification helper to Request

Sources/Stripe/Stripe+Extensions.swift

@@ -38,3 +38,40 @@ extension Request {
         }
     }
 }
+
+extension StripeClient {
+    /// Verifies a Stripe signature for a given `Request`. This automatically looks for the header in the headers of the request and the body.
+    /// - Parameters:
+    ///     - req: The `Request` object to check header and body for
+    ///     - secret: The webhook secret used to verify the signature
+    ///     - tolerance: In seconds the time difference tolerance to prevent replay attacks: Default 300 seconds
+    /// - Throws: `StripeSignatureError`
+    public static func verifySignature(for req: Request, secret: String, tolerance: Double = 300) throws {
+        guard let header = req.headers.first(name: "Stripe-Signature") else {
+            throw StripeSignatureError.unableToParseHeader
+        }
+
+        guard let data = req.body.data else {
+            throw StripeSignatureError.noMatchingSignatureFound
+        }
+
+        try StripeClient.verifySignature(payload: Data(data.readableBytesView), header: header, secret: secret, tolerance: tolerance)
+    }
+}
+
+extension StripeSignatureError: AbortError {
+    public var reason: String {
+        switch self {
+        case .noMatchingSignatureFound:
+            return "No matching signature was found"
+        case .timestampNotTolerated:
+            return "Timestamp was not tolerated"
+        case .unableToParseHeader:
+            return "Unable to parse Stripe-Signature header"
+        }
+    }
+
+    public var status: HTTPResponseStatus {
+        .badRequest
+    }
+}