Defensive Programming: What Every Programmer Should Know

Is the program you’re creating safe from any threats it might encounter? By “risks”, we mean potential program flaws and vulnerabilities. 

Programmers can build programs that are more immune to flaws and vulnerabilities by using the defensive programming technique. In addition, these programming best practices and habits will increase comprehension, consistency, and predictability. 

They are a collection of coding best practices that assist developers in identifying problems and avoiding their recurrence. By using defensive programming strategies, programmers can create new code without errors, saving time and money on debugging.

Defensive programming is crucial for software engineers because it can help them prevent coding errors, cut down on bugs, and improve the security of their programs. As a result, it is essential for software development. 

Software security issues can cause severe problems and application failures. Unfortunately, many people frequently put off thinking about security until it is too late. As a result, they might not be aware that there are easy steps they can take to design secure software from the beginning. 

Defensive programming enhances: 

• Code Quality 

• Code Comprehension 

• Code Predictability 

Code Quality 

Code quality is a metric used to assess an application’s coding effectiveness. Additionally, it gauges how well the program functions and complies with specifications. 

Even if an application is expertly designed, if it doesn’t function, it is of no use, and even if it works flawlessly but does not fulfill its purpose, it is still invalid. 

Code review, unit testing, static code analysis, and other tools and approaches to increasing the code quality should be used immediately when you begin developing your application or, at the very least, whenever you get the chance to rework the code. 

Code Comprehension 

A number of guidelines and best practices can be used to enhance code understanding. The following are some key things to keep in mind to enhance code understanding when you write the code: 

• Code should have a manageable number of classes and functions and be simple to read. 
• The purpose of code must be clear, should serve a single and obvious goal. The code must be simple enough that the other programmers should be able to understand its purpose with ease 
• The code must be straightforward. It can be difficult to manage complex code. 

Code Predictability 

The golden rule for writing predictable code is to constantly ask yourself, “What should happen if…”. Before you begin the slightest bit of logic from which you anticipate a result, consult your user, an SME, or yourself. 

What must we protect the code from?

Improper operations 

We must provide reliable data to our methods for them to execute their operation appropriately and generate legitimate results. Therefore, we protect our code from invalid operations by examining the arguments supplied to those methods and implementing unit testing for the operations. 

Inaccurate entry 

The output of the application must be accurate for the user to receive the desired outcomes. Therefore, we include proper user entry validation to protect our code from inaccurate entries. 

System errors 

When using software or an application, things can go wrong. For example, the user may lose connectivity while saving data, or an API call to retrieve data may fail unexpectedly. To guard against these errors, we create checks and control exceptions.  

For instance, before saving the data, we check that the network is accessible and raise an exception if the network is down. Following that, we safeguard the data locally until the network is operational. 

Other developers 

If a code is intricate, it might cause problems when refactored without a thorough understanding of its functions and effects.  

If our code is confusing and another developer doesn’t grasp our intentions, they can assume the wrong things about it and make unsuitable adjustments, making our code ineffective. We defend our code against future developers by writing clear, understandable code that is easy to read and understand. In addition, we write unit tests to ensure that future changes don’t adversely affect them. 

It can sometimes seem impossible to create original code amid a rapidly changing environment, legacy issues, time constraints, and continually evolving requirements. But defensive coding can be helpful. 

Types of Security Vulnerabilities That Defensive Programming Techniques Can Prevent 

Flaws seriously threaten any software system. Defensive programming approaches are one method for guarding against these vulnerabilities in your software system.  

They can stop a wide variety of security vulnerabilities. One kind is a security flaw in Java brought about by inadequate input validation and poor error handling. 

Another kind is a PHP security flaw brought on by failing to escape user input before sending it to a SQL database or other backend service, as well as a web application security flaw brought on by inadequate input validation and server-side code buffer overflows. 

For each vulnerability, you can employ different defensive coding strategies, such as using data validation and preventing concurrency issues. 

The following is a list the most prevalent security flaws in web apps, Java, C#, and PHP. 

• Injection 
• Authentication problems 
• Exposed sensitive data 
• External entities in XML (XXE) 
• Ineffective access control 
• Misconfigurations of security 
• Site-to-site scripting (XSS) 
• Vulnerable deserialization 
• Using components with known security holes 
• Inadequate logging and surveillance 

The Value of Data Handling Capability Testing and the Defense Function in Security Testing 

An essential step in the app testing process is the data handling test. It aids in ensuring that the app is capable of handling the volume of data that will be presented to it in a practical setting. 

One of the crucial components of any security testing procedure is defense. It guarantees that your software has a back entrance through which you can exit if something goes wrong. 

Conclusion: Defensive Coding Techniques for Creating Secure Applications

The initial step is to adhere to secure coding best practices. The second step is to utilize defensive programming strategies like input validation and error handling. Finally, it would be best to correct any security flaws in the code before releasing it for production.