fix: unsigned payload being treated as string

Author: soberm

packages/core/__tests__/clients/middleware/signing/signer/signatureV4/utils/getHashedPayload.test.ts

@@ -2,6 +2,7 @@
 // SPDX-License-Identifier: Apache-2.0
 
 import { getHashedPayload } from '../../../../../../../src/clients/middleware/signing/signer/signatureV4/utils/getHashedPayload';
+import { UNSIGNED_PAYLOAD } from '../../../../../../../src/clients/middleware/signing/signer/signatureV4/constants';
 
 describe('getHashedPayload', () => {
 	test('returns empty hash if nullish', () => {
@@ -34,4 +35,10 @@ describe('getHashedPayload', () => {
 			expect(getHashedPayload(scalar as any)).toStrictEqual('UNSIGNED-PAYLOAD');
 		}
 	});
+
+	test('returns UNSIGNED_PAYLOAD constant without hashing when passed as body', () => {
+		expect(getHashedPayload(UNSIGNED_PAYLOAD as any)).toStrictEqual(
+			'UNSIGNED-PAYLOAD',
+		);
+	});
 });

packages/core/src/clients/middleware/signing/signer/signatureV4/utils/getHashedPayload.ts

@@ -34,7 +34,9 @@ export const getHashedPayload = (body: HttpRequest['body']): string => {
 };
 
 const isSourceData = (body: HttpRequest['body']): body is SourceData =>
-	typeof body === 'string' || ArrayBuffer.isView(body) || isArrayBuffer(body);
+	// Exclude UNSIGNED_PAYLOAD constant to prevent it from being hashed as a string
+	body !== UNSIGNED_PAYLOAD &&
+	(typeof body === 'string' || ArrayBuffer.isView(body) || isArrayBuffer(body));
 
 const isArrayBuffer = (arg: any): arg is ArrayBuffer =>
 	(typeof ArrayBuffer === 'function' && arg instanceof ArrayBuffer) ||