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Assertions are generally unsuitable for server programs or embedded systems in deployment. A failed assertion can lead to a denial-of-service (DoS) attack if triggered by a malicious user. In such situations, a soft failure mode, such as writing to a log file and rejecting the request, is more appropriate.

Noncompliant Code Example

This noncompliant code example uses the assert statement to verify that input was available:

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Because input availability depends on the user and can be exhausted at any point during program execution, a robust program must be prepared to gracefully handle and recover from the unavailability of input. However, using the assert statement to verify that some significant input was available is inappropriate because it might lead to an abrupt termination of the process, resulting in a denial of service.

Compliant Solution

This compliant solution demonstrates the recommended way to detect and handle unavailability of input:

BufferedReader br;

// Set up the BufferedReader br

String line;

// ...

line = br.readLine();

if (line == null) {
  // Handle error
}

Applicability

Assertions are a valuable diagnostic tool for finding and eliminating software defects that may result in vulnerabilities. The absence of assertions, however, does not mean that code is bug-free.

In general, the misuse of the assert statement for runtime checking rather than checking for logical errors cannot be detected automatically.

Bibliography

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