Avoid undocumented methods: CAST Software Issues

In enterprise software development, especially with CAST software, undocumented methods can seriously impact code maintenance and security. These methods lack comments or documentation, making their purpose and behavior unclear, which can lead to hidden functionality, security risks, and challenges in code analysis.
 

Impact of Undocumented Methods
Undocumented methods can introduce a variety of risks and complications into a codebase:
 

• Obscured Functionality: In large or legacy codebases, undocumented methods can turn into confusing black boxes, making it hard for developers to understand or use them properly. This issue is worse in environments with multiple teams, as it increases the risk of misusing the methods.
   

• Security Vulnerabilities: Without proper documentation, these methods might hide security flaws. For instance, a method handling sensitive data or interacting with external systems could lack necessary security measures, leading to potential data breaches or unauthorized access.
   

• Static Analysis Limitations: CAST software relies on code structure and metadata to perform static analysis effectively. When methods are undocumented, the tool may struggle to interpret their purpose or detect potential security flaws, resulting in gaps in analysis and missed vulnerabilities.

CAST Software’s Approach to Undocumented Methods
CAST software addresses the issue of undocumented methods with specific rules and functionalities. According to CAST's guidelines:
 

• Description: The tool identifies all methods that lack documentation. This includes methods across various programming languages and frameworks such as SAP, C#, C/C++, JEE, PowerBuilder, VB.NET, and Visual Basic. In particular, CAST checks for documentation in constructors, destructors, and ABAP event methods. For C#, it excludes getters and setters if the properties or indexers they belong to are documented.
   

• Rationale: The primary rationale for identifying undocumented methods is to improve code maintainability. Proper documentation ensures that code is easier to understand, review, and maintain. This rule in CAST ensures that there are comments within the artifact, which helps maintain clarity and reduces the likelihood of introducing errors or vulnerabilities during future modifications.
   

• Remediation: The remediation process for this issue is straightforward—developers should add comments to method implementations to explain their goals and how they work. This practice not only improves maintainability but also helps in identifying and mitigating potential security issues more effectively.

Code Examples Illustrating the Risks of Undocumented Methods
Here are some examples to illustrate the potential risks of undocumented methods:
 

Example 1: Unclear Method Purpose

public int processUserData(int userId) {
    // ... some processing logic ...
    int result = calculateSomething(userId);
    // ... more processing ...
    return result;
}

This Java method lacks documentation about what "processing" entails. Without this information, it is difficult for developers to understand the method’s purpose or the implications of changes made to it, which could lead to misuse or errors.

Example 2: Potential Security Flaw in Undocumented Method

public string GetEncryptedPassword(string username) {
    // This method retrieves an encrypted password from the database
    // But there is no documentation explaining the encryption method used or any security checks
    string encryptedPassword = Database.Retrieve("SELECT password FROM Users WHERE username = '" + username + "'");
    return encryptedPassword;
}

This C# method retrieves a password from a database but lacks documentation on the encryption method used or whether proper security checks (like input sanitization) are in place. This omission could hide serious vulnerabilities, such as susceptibility to SQL injection attacks.
 

Example 3: Hidden Side Effects

def update_user_profile(user_id, profile_data):
    user = database.get_user(user_id)
    user.update(profile_data)
    send_email(user.email, "Your profile was updated.")
    # No documentation about the email sending side effect

In this Python example, the method updates a user's profile but also sends an email notification as a side effect. Without documentation, this behavior could lead to unexpected outcomes, such as sending unnecessary emails during batch updates or tests.
 

Leveraging CAST to Identify and Remediate Undocumented Methods
To address the issue of undocumented methods, CAST provides several mechanisms:
 

Custom Code Scanning Rules: CAST allows for the creation of custom rules to flag methods that lack comments or sufficient documentation. For example, a rule can be set up to flag any method that does not have a summary comment or lacks documentation for its parameters and return values.
 

Example Custom Rule in CAST:
 

<Rule>
    <Id>UNM001</Id>
    <Name>Undocumented Method Detection</Name>
    <Description>Flag methods with missing documentation.</Description>
    <Severity>Warning</Severity>
    <Target>Method</Target>
    <Condition>
        <![CDATA[
        !element.HasComment() || !element.HasDocumentation()
        ]]>
    </Condition>
</Rule>

Highlighting and Metrics: CAST can highlight undocumented methods directly in the code editor or in reports, making it easier to identify and address these issues. Developers can also create metrics to track the percentage of undocumented methods, providing a quantitative measure of code documentation quality.
 

**Dependency Analysis: **CAST’s dependency analysis allows developers to track the influence of undocumented methods across the codebase, identifying potential security risks and impacts on other components.
 

**Integration with CI/CD Pipelines: **CAST can be integrated into CI/CD pipelines to automatically detect undocumented methods during builds, ensuring these issues are caught early and don't introduce new vulnerabilities.
 

Example Integration Command:
 

cast-cli analyze --target=myApplication --rules=UNM001 --output=report.xml

 
Best Practices for Documenting Methods
To prevent problems with undocumented methods, consider these best practices:

 
Document Intent and Behavior: Each method should include a brief overview of its purpose, its role in the application, and its intended function.
 
Example Documentation:

def calculate_discount(price, discount_rate):
    """
    Calculate the discounted price given an initial price and a discount rate.


    Args:
        price (float): The initial price of the product.
        discount_rate (float): The discount rate to apply, as a decimal (e.g., 0.2 for 20%).


    Returns:
        float: The final price after the discount has been applied.
    """
    return price * (1 - discount_rate)

 
Define Inputs, Outputs, and Exceptions: Clearly describe the method’s input parameters, return values, and any exceptions it might throw to ensure its usage is fully understood.

 
Example in Java:

/**
 * Retrieves the user's profile data from the database.
 *
 * @param userId The unique identifier of the user.
 * @return A UserProfile object containing the user's data.
 * @throws UserNotFoundException if no user with the given ID exists.
 */
public UserProfile getUserProfile(int userId) throws UserNotFoundException {
    // Method implementation
}

 
Document Side Effects and Preconditions: If a method has side effects or preconditions, these should be explicitly documented to avoid misunderstandings and unintended use.
 
Example in C#:

/// <summary>
/// Updates the user's email address and sends a confirmation email.
/// </summary>
/// <param name="userId">The ID of the user.</param>
/// <param name="newEmail">The new email address to set for the user.</param>
/// <remarks>
/// This method modifies the user's email in the database and sends a confirmation email to the new address.
/// </remarks>
public void UpdateEmail(int userId, string newEmail) {
    // Update logic
    SendConfirmationEmail(newEmail);
}

Following these practices and using CAST's tools to find and fix undocumented methods can greatly minimize the risks they pose, helping keep the codebase secure, maintainable, and aligned with best practices.