fix(@aws-amplify/core): Support clock skew (#4844)

* fix(@aws-amplify/core): AWS.config.systemClockOffset for signing requests

* Add Util/Date to support new Date() with clock offset

* Add tests for Utils.Date

* Signer users Util.Date

* Remove unused "date" for mocking

* Rename Date to DateUtils to allow "import { DateUtils }"

* Reference DateUtils directly vs. Utils.DateUtils

* Move DateUtils.test.ts so that core can build

* Add annotation to clockOffset for documentation & intellisense

* Fix test path

* Improve JSDoc

Co-authored-by: Thiago Hirata <hirata@devcase.com.br>
Co-authored-by: Sam Martinez  <sammartinez19@gmail.com>

packages/core/__tests__/DateUtils-test.ts

@@ -0,0 +1,37 @@
+import { DateUtils } from '../src/Util/DateUtils';
+
+// Mock Date (https://github.com/facebook/jest/issues/2234#issuecomment-308121037)
+const staticDate = new Date('2020-01-01');
+// @ts-ignore Type 'typeof Date' is not assignable to type 'DateConstructor'.
+Date = class extends Date {
+	// @ts-ignore Constructors for derived classes must contain a 'super' call.ts(2377)
+	constructor() {
+		return staticDate;
+	}
+};
+
+describe('Date', () => {
+	describe('getDateWithClockOffset()', () => {
+		it('should return a new Date()', () => {
+			expect(DateUtils.getDateWithClockOffset()).toEqual(new Date());
+		});
+	});
+
+	describe('getClockOffset()', () => {
+		it('should default to 0', () => {
+			expect(DateUtils.getClockOffset()).toEqual(0);
+		});
+	});
+
+	describe('with setClockOffset()', () => {
+		beforeAll(() => {
+			DateUtils.setClockOffset(1000);
+		});
+
+		describe('getDate()', () => {
+			expect(DateUtils.getDateWithClockOffset()).toEqual(
+				new Date(new Date().getTime() + 1000)
+			);
+		});
+	});
+});

packages/core/__tests__/Signer-test.ts

@@ -20,13 +20,14 @@ jest.mock('../src/Facet', () => {
 		};
 		return { update };
 	};
+
 	return {
 		AWS: ret,
 	};
 });
 
 import Signer from '../src/Signer';
-import AWS from '../src';
+import { DateUtils } from '../src';
 
 describe('Signer test', () => {
 	describe('sign test', () => {
@@ -45,6 +46,8 @@ describe('Signer test', () => {
 				.spyOn(Date.prototype, 'toISOString')
 				.mockReturnValueOnce('0');
 
+			const getDateSpy = jest.spyOn(DateUtils, 'getDateWithClockOffset');
+
 			const res = {
 				headers: {
 					Authorization:
@@ -56,6 +59,7 @@ describe('Signer test', () => {
 				url: url,
 			};
 			expect(Signer.sign(request, access_info)).toEqual(res);
+			expect(getDateSpy).toHaveBeenCalledTimes(1);
 
 			spyon.mockClear();
 		});

packages/core/src/Signer.ts

@@ -12,6 +12,7 @@
  */
 
 import { ConsoleLogger as Logger } from './Logger';
+import { DateUtils } from './Util';
 import { AWS } from './Facet';
 
 const logger = new Logger('Signer'),
@@ -299,7 +300,7 @@ export default class Signer {
 		request.headers = request.headers || {};
 
 		// datetime string and date string
-		const dt = new Date(),
+		const dt = DateUtils.getDateWithClockOffset(),
 			dt_str = dt.toISOString().replace(/[:\-]|\.\d{3}/g, ''),
 			d_str = dt_str.substr(0, 8);
 
@@ -370,7 +371,9 @@ export default class Signer {
 		const body: any =
 			typeof urlOrRequest === 'object' ? urlOrRequest.body : undefined;
 
-		const now = new Date().toISOString().replace(/[:\-]|\.\d{3}/g, '');
+		const now = DateUtils.getDateWithClockOffset()
+			.toISOString()
+			.replace(/[:\-]|\.\d{3}/g, '');
 		const today = now.substr(0, 8);
 		// Intentionally discarding search
 		const { search, ...parsedUrl } = url.parse(urlToSign, true, true);

packages/core/src/Util/DateUtils.ts

@@ -0,0 +1,35 @@
+/**
+ * Date & time utility functions to abstract the `aws-sdk` away from users.
+ * (v2 => v3 modularization is a breaking change)
+ *
+ * @see https://github.com/aws/aws-sdk-js/blob/6edf586dcc1de7fe8fbfbbd9a0d2b1847921e6e1/lib/util.js#L262
+ */
+
+export const DateUtils = {
+	/**
+	 * Milliseconds to offset the date to compensate for clock skew between device & services
+	 */
+	clockOffset: 0,
+
+	getDateWithClockOffset() {
+		if (DateUtils.clockOffset) {
+			return new Date(new Date().getTime() + DateUtils.clockOffset);
+		} else {
+			return new Date();
+		}
+	},
+
+	/**
+	 * @returns {number} Clock offset in milliseconds
+	 */
+	getClockOffset() {
+		return DateUtils.clockOffset;
+	},
+
+	/**
+	 * @param {number} offset Clock offset in milliseconds
+	 */
+	setClockOffset(offset: number) {
+		DateUtils.clockOffset = offset;
+	},
+};

packages/core/src/Util/index.ts

@@ -1,3 +1,4 @@
 export * from './Retry';
 export { default as Mutex } from './Mutex';
 export { default as Reachability } from './Reachability';
+export * from './DateUtils';