Use 'Expires' header to time-limit URLs

Author: markuscolourbox

source/image-handler/image-request.ts

@@ -41,6 +41,7 @@ export class ImageRequest {
       imageRequestInfo = { ...imageRequestInfo, ...originalImage };
 
       imageRequestInfo.headers = this.parseImageHeaders(event, imageRequestInfo.requestType);
+      this.validateRequestExpires(imageRequestInfo);
 
       // If the original image is SVG file and it has any edits but no output format, change the format to WebP.
       if (imageRequestInfo.contentType === 'image/svg+xml' && imageRequestInfo.edits && Object.keys(imageRequestInfo.edits).length > 0 && !imageRequestInfo.edits.toFormat) {
@@ -443,4 +444,29 @@ export class ImageRequest {
       }
     }
   }
+
+  private validateRequestExpires(requestInfo: ImageRequestInfo): void {
+    try {
+      const expires = requestInfo.headers?.expires;
+      if (expires !== undefined) {
+        const parsedDate = new Date(expires);
+        if (isNaN(parsedDate.getTime())) {
+          throw new ImageHandlerError(StatusCodes.BAD_REQUEST, 'ImageRequestExpiryFormat', 'Request has invalid expiry date.');
+        }
+        const now = new Date();
+        if (now > parsedDate) {
+          throw new ImageHandlerError(StatusCodes.FORBIDDEN, 'ImageRequestExpired', 'Request has expired.');
+        }
+      }
+    } catch (error) {
+      if (error.code === 'ImageRequestExpired') {
+        throw error;
+      }
+      if (error.code === 'ImageRequestExpiryFormat') {
+        throw error;
+      }
+      console.error('Error occurred while checking expiry.', error);
+      throw new ImageHandlerError(StatusCodes.INTERNAL_SERVER_ERROR, 'ExpiryDateCheckFailure', 'Expiry date check failed.');
+    }
+  }
 }

source/image-handler/test/image-request.spec.ts

@@ -853,6 +853,46 @@ describe('setup()', () => {
       expect(imageRequestInfo).toEqual(expectedResult);
     });
   });
+
+  describe('011/expiryDate', () => {
+    it.each([
+      {
+        path: '/eyJidWNrZXQiOiJ0ZXN0IiwicmVxdWVzdFR5cGUiOiJEZWZhdWx0Iiwia2V5IjoidGVzdC5wbmciLCJoZWFkZXJzIjp7ImV4cGlyZXMiOiJUaHUsIDAxIEphbiAxOTcwIDAwOjAwOjAwIEdNVCJ9fQ==',
+        error: {
+          code: 'ImageRequestExpired',
+          message: 'Request has expired.',
+          status: StatusCodes.FORBIDDEN,
+        },
+      },
+      {
+        path: '/eyJidWNrZXQiOiJ0ZXN0IiwicmVxdWVzdFR5cGUiOiJEZWZhdWx0Iiwia2V5IjoidGVzdC5wbmciLCJoZWFkZXJzIjp7ImV4cGlyZXMiOiJpbnZhbGlkS2V5In19',
+        error: {
+          code: 'ImageRequestExpiryFormat',
+          message: 'Request has invalid expiry date.',
+          status: StatusCodes.BAD_REQUEST,
+        }
+      }
+    ])("Should throw an error when $error.message", (async ({ path, error: expectedError }) => {
+      // Arrange
+      const event = {
+        path,
+      };
+      // Mock
+      mockAwsS3.getObject.mockImplementationOnce(() => ({
+        promise() {
+          return Promise.resolve({ Body: Buffer.from('SampleImageContent\n') });
+        }
+      }));
+      // Act
+      const imageRequest = new ImageRequest(s3Client, secretProvider);
+      try {
+        await imageRequest.setup(event);
+      } catch (error) {
+        // Assert
+        expect(error).toMatchObject(expectedError);
+      }
+    }));
+  });
 });
 
 describe('getOriginalImage()', () => {