[py] refactor HtmlOnlyHandler in webserver.py to support JSON content

[navin772]

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Description

The current HtmlOnlyHandler does not takes into account various other content types like JSON and results into errors.

This PR add a new ExtendedHandlerthat can help with these types and also enable CORS for GET, POST methods.

Motivation

I was trying out FedCM implementation for python and cannot get the POST methods to work with the SimpleWebServer() due to CORS origin errors and JSON type not supported in the earlier HtmlOnlyHandler. The added ExtendedHandler will help with running the FedCM tests.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have read the contributing document.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.

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PR Type

enhancement

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Description

• Replaced the HtmlOnlyHandler with ExtendedHandler to handle various content types including JSON.
• Implemented CORS support by adding appropriate headers for GET, POST, and OPTIONS methods.
• Enhanced the do_GET method to dynamically serve HTML pages and support different file types based on extensions.
• Rewrote the do_POST method for better clarity and efficiency, including improved handling of file uploads.

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Changes walkthrough 📝

	Relevant files
Enhancement	webserver.py Enhance HTTP handler to support JSON and CORS                        py/test/selenium/webdriver/common/webserver.py Replaced HtmlOnlyHandler with ExtendedHandler to support more content types. Added CORS support for GET, POST, and OPTIONS methods. Enhanced do_GET method to serve JSON and other file types. Rewrote do_POST method for improved clarity and efficiency. +50/-43

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[qodo-merge-pro]

PR Reviewer Guide 🔍

Here are some key observations to aid the review process:

⏱️ Estimated effort to review: 3 🔵🔵🔵⚪⚪

🧪 No relevant tests

🔒 Security concerns Potential file exposure: The new implementation in the do_GET method allows serving any file type from the server's file system. This could potentially expose sensitive files if proper access controls are not in place. The code should be reviewed to ensure that only intended files and directories are accessible.

⚡ Recommended focus areas for review Error Handling The new implementation might not handle all error cases properly. For example, the file reading operation is not wrapped in a try-except block, which could lead to unhandled exceptions. Security Concern The new implementation allows serving any file type, which could potentially lead to serving sensitive files if not properly restricted. Performance Issue The new implementation reads the entire file content into memory before sending it. For large files, this could lead to high memory usage and potential out-of-memory errors.

[qodo-merge-pro]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Score
Possible issue	Add a check for the existence of required headers to prevent potential exceptions Consider adding a check for the existence of the 'content-length' header before attempting to access it. This can prevent potential KeyError exceptions if the header is missing. py/test/selenium/webdriver/common/webserver.py [112] -remaining_bytes = int(self.headers["content-length"]) +content_length = self.headers.get("content-length") +if content_length is None: + self.send_error(400, "Missing Content-Length header") + return +remaining_bytes = int(content_length) Apply this suggestion Suggestion importance[1-10]: 8 Why: The suggestion to check for the existence of the 'content-length' header is valuable as it prevents potential KeyError exceptions, improving the robustness and reliability of the code when handling POST requests.	8
Enhancement	Use a dictionary to map file extensions to content types for improved maintainability and scalability Consider using a dictionary to map file extensions to content types instead of using multiple if-else statements. This approach is more scalable and easier to maintain. py/test/selenium/webdriver/common/webserver.py [93-98] -if file_extension == ".json": - content_type = "application/json" -elif file_extension == ".html": - content_type = "text/html" -else: - content_type = "application/octet-stream" +content_types = { + ".json": "application/json", + ".html": "text/html" +} +content_type = content_types.get(file_extension, "application/octet-stream") Apply this suggestion Suggestion importance[1-10]: 7 Why: The suggestion to use a dictionary for mapping file extensions to content types enhances code readability and maintainability. It simplifies the addition of new content types in the future, making the code more scalable.	7

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[AutomatedTester]

There seems to be quite a bit of code duplication between the new code and the existing code. Let's refactor it

[navin772]

@AutomatedTester Initially, I tried to modify the HtmlOnlyHandler so that it can work for other use cases, but some tests were failing (refer to the previous commit).

What do you suggest? Having 2 handlers or just one?

[navin772]

Refactored the code into one class to handle JSON type