Use Buffer.from().toString() instead of atob() to decode task payload

[CodingDoug]

Fixes problem decoding task payload (#8836)

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[gemini-code-assist]

Summary of Changes

Hello @CodingDoug, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request resolves a critical issue in the tasks emulator where task payloads were not being decoded correctly. By switching from the less robust atob() function to Node.js's Buffer.from().toString() method, the emulator can now reliably parse base64 encoded task bodies, ensuring proper task execution and data integrity.

Highlights

• Task Payload Decoding Fix: The method for decoding base64 encoded httpRequest.body within task payloads in src/emulator/tasksEmulator.ts has been updated.
• Improved Decoding Robustness: Replaced the atob() function with Buffer.from(..., "base64").toString("utf-8") to ensure more reliable and correct handling of various character encodings in task payloads, addressing a known decoding issue.

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[gemini-code-assist]

Code Review

This pull request correctly replaces the use of atob() with the more robust Buffer.from().toString() for decoding base64 task payloads. This is a good improvement for correctness and compatibility with Node.js environments.

I've added one suggestion to improve error handling around the decoding and parsing logic. This will make the emulator more resilient to invalid inputs by preventing unhandled exceptions.

[gemini-code-assist]

While this change to use Buffer.from is a great improvement, the surrounding logic is still vulnerable to unhandled exceptions. If req.body.task.httpRequest.body is not a valid base64 string, or if the decoded string is not valid JSON, JSON.parse will throw an error.

This will likely be caught by Express's default error handler and result in a 500 Internal Server Error response. This is not ideal for what is essentially a client-side error (invalid input).

It would be more robust to wrap this operation in a try...catch block and explicitly return a 400 Bad Request response.

For example, you could modify the code around this line to be:

      try {
        req.body.task.httpRequest.body = JSON.parse(
          Buffer.from(req.body.task.httpRequest.body, "base64").toString("utf-8")
        );
      } catch (e: any) {
        this.logger.log("WARN", `Failed to parse task body: ${e.message}`);
        return res.status(400).send("Invalid task body: not a valid base64-encoded JSON object.");
      }

      const task = req.body.task as Task;
      // ... rest of the handler