chore(middleware-flexible-checksums): perform checksum calculation and validation by default

[trivikr]

Issue

• Internal JS-5396
• Split from chore(middleware-flexible-checksums): use RequestChecksumCalculation and ResponseChecksumValidation #6492
• Should be rebased after chore(middleware-flexible-checksums): change default algorithm to CRC32 #6749 is merged

Description

Performs checksum calculation and validation by default based on values in RequestChecksumCalculation and ResponseChecksumValidation

Testing

Unit testing in CI

Verified that CRC32 checksums are computed by default

import { S3 } from "../aws-sdk-js-v3/clients/client-s3/dist-cjs/index.js";
import { NodeHttpHandler } from "../aws-sdk-js-v3/node_modules/@smithy/node-http-handler/dist-cjs/index.js";
import { equal } from "assert";

// Prints checksum headers for request and response.
class CustomHandler extends NodeHttpHandler {
  constructor() {
    super();
  }

  printChecksumHeaders(prefix, headers) {
    for (const [header, value] of Object.entries(headers)) {
      if (
        header.startsWith("x-amz-checksum-") ||
        header.startsWith("x-amz-sdk-checksum-")
      ) {
        console.log(`${prefix}['${header}']: '${value}'`);
      }
    }
  }

  async handle(request, options) {
    this.printChecksumHeaders("request", request.headers);
    const response = await super.handle(request, options);
    this.printChecksumHeaders("response", response.response.headers);
    return response;
  }
}

// WHEN_SUPPORTED is default.
const client = new S3({
  requestHandler: new CustomHandler(),
});
const Bucket = "test-flexible-checksums-v2"; // Replace with your test bucket name.
const Key = "hello-world.txt";
const Body = "Hello World"; // Replace with the content you want to test.

console.log("Put Object");
// ChecksumAlgorithm is not explicitly required to be specified.
await client.putObject({ Bucket, Key, Body });

console.log("\nGet Object");
// ChecksumMode is not explicitly required to be specified.
const response = await client.getObject({ Bucket, Key });

equal(Body, await response.Body.transformToString());

Output

Put Object
request['x-amz-sdk-checksum-algorithm']: 'CRC32'
request['x-amz-checksum-crc32']: 'ShexVg=='
response['x-amz-checksum-crc32']: 'ShexVg=='
response['x-amz-checksum-type']: 'FULL_OBJECT'

Get Object
request['x-amz-checksum-mode']: 'ENABLED'
response['x-amz-checksum-crc32']: 'ShexVg=='
response['x-amz-checksum-type']: 'FULL_OBJECT'

---

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[kuhe]

Add more tests in middleware-flexible-checksums.integ.spec.ts?

[trivikr]

Add more tests in middleware-flexible-checksums.integ.spec.ts?

The tests were added in clients/client-s3/test/unit/flexibleChecksums.spec.ts in prior diff.
However, the integration tests need to as close to the source code as possible - so generic tests were moved to middleware package in #6752

And the tests were added to updated file in d6af53c (#6750)