chore: skip checksums for x-amz-checksum-algorithm header

This reverts commit 9204de2.

Author: trivikr

packages/middleware-flexible-checksums/src/flexibleChecksumsMiddleware.spec.ts

@@ -174,39 +174,6 @@ describe(flexibleChecksumsMiddleware.name, () => {
       expect(stringHasher).toHaveBeenCalledWith(mockChecksumAlgorithmFunction, mockRequest.body);
       expect(mockBase64Encoder).toHaveBeenCalledWith(mockRawChecksum);
     });
-
-    it.each(["x-amz-checksum-algorithm", "X-AMZ-CHECKSUM-ALGORITHM"])(
-      "even if '%s' header is present",
-      async (headerName) => {
-        const mockRawChecksum = Buffer.from(mockChecksum);
-        const mockBase64Encoder = vi.fn().mockReturnValue(mockChecksum);
-        vi.mocked(stringHasher).mockResolvedValue(mockRawChecksum);
-        vi.mocked(hasHeader).mockReturnValue(false);
-
-        const handler = flexibleChecksumsMiddleware(
-          { ...mockConfig, base64Encoder: mockBase64Encoder },
-          mockMiddlewareConfig
-        )(mockNext, {});
-        const mockHeadersWithAlgoHeader = { ...mockHeaders, [headerName]: "mockHeaderValue" };
-        const mockArgsWithAlgoHeader = {
-          ...mockArgs,
-          request: { ...mockRequest, headers: mockHeadersWithAlgoHeader },
-        };
-        await handler(mockArgsWithAlgoHeader);
-
-        expect(hasHeader).toHaveBeenCalledTimes(1);
-        expect(mockNext).toHaveBeenCalledWith({
-          ...mockArgs,
-          request: {
-            ...mockRequest,
-            headers: { ...mockHeadersWithAlgoHeader, [mockChecksumLocationName]: mockChecksum },
-          },
-        });
-        expect(hasHeader).toHaveBeenCalledWith(mockChecksumLocationName, mockHeadersWithAlgoHeader);
-        expect(stringHasher).toHaveBeenCalledWith(mockChecksumAlgorithmFunction, mockRequest.body);
-        expect(mockBase64Encoder).toHaveBeenCalledWith(mockRawChecksum);
-      }
-    );
   });
 
   describe("set feature", () => {

packages/middleware-flexible-checksums/src/flexibleChecksumsMiddleware.ts

@@ -57,9 +57,8 @@ export const flexibleChecksumsMiddleware =
       return next(args);
     }
 
-    for (const originalHeader of Object.keys(args.request.headers)) {
-      const header = originalHeader.toLowerCase();
-      if (header.startsWith("x-amz-checksum-") && header !== "x-amz-checksum-algorithm") {
+    for (const header of Object.keys(args.request.headers)) {
+      if (header.toLowerCase().startsWith("x-amz-checksum-")) {
         return next(args);
       }
     }