Avoid booleans, always

TL;DR: Replace boolean security flags in APIs with separate, more secure endpoints.

Problems

• Overly simplistic security model
• Lack of granular control
• Potential for misuse
• Reduced traceability
• Difficult maintenance

Solutions

1. Create separate endpoints
2. Implement granular permissions
3. Enhance logging capabilities
4. Deal with code duplication

Refactorings

Context

Many APIs (like WhatsApp) use boolean flags to toggle security features.

An API might have a secure parameter that enables additional security checks when set to true.

While this approach seems simple, it introduces several problems.

You sacrifice granular control, make the API more prone to misuse, and reduce your ability to track and audit security-related actions.

Instead of relying on boolean flags, you should create separate endpoints for different security levels.

This is a special case of the Remove IF Refactoring.

This approach allows for more precise control, better traceability, and easier maintenance.

Sample Code

Wrong

{
  "message": {
    "imageMessage": {
      "url": "https://mmg.whatsapp.net/v/art_vanderley.jpg",
      "mimetype": "image/jpeg",
      "fileSha256": "mJh9DKj34ao9Ph7cBm/CwKurgjbyMTFHJeo=",
      "fileLength": 24601,
      "height": 2048,
      "width": 1536
    },
    "viewOnce": true
  },
  "type": "notify"
}

Right

# Instead of a single endpoint with a boolean flag:
def send_message(content, view_once = False):
    # Process message based on view_once flag
    pass

# Create separate endpoints:
def send_regular_message(content):
    # Process regular message
    pass

def send_view_once_message(content):
    # Process view once message with enhanced security
    pass

Detection

• [x]Semi-Automatic

We can instruct our linters to warn us for boolean flags.

Exceptions

• Real Business Booleans (There are just a few ones)

• Security

Level

• [x]Intermediate

AI Generation

AI code generators might create this smell if instructed to add security options to existing APIs.

They often chose the simplest solution, leading to boolean flags for security features.

AI Detection

AI-powered code analysis tools can detect this smell with specific instructions.

You can train them to flag APIs that use boolean parameters for security-related functionality and suggest creating separate endpoints instead.

Try Them!

Remember: AI Assistants make lots of mistakes

Conclusion

Creating distinct endpoints for different security levels improves your API's clarity, security, and maintainability.

This approach allows for better access control and more detailed logging.

It also reduces the risk of accidentally processing sensitive data without proper security measures. Remember, when it comes to security, explicit is better than implicit.

Relations

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-xiii

https://hackernoon.com/how-to-find-the-stinky-parts-of-your-code-part-ii-o96s3wl4

More Info

Disclaimer

Code Smells are my opinion.

Credits

Photo by Juan Gomez on Unsplash

Complexity is the worst enemy of security, and our systems are getting more complex all the time.

Bruce Schneier

This article is part of the CodeSmell Series.

How to Find the Stinky Parts of your Code