callersupplied

Callersupplied refers to data or values provided by the caller of a function, API, or service rather than generated within the system. Because that data comes from external sources, it is typically treated as untrusted and may be malformed or malicious. Common sources include user input from forms, request bodies in web services, command-line arguments, and data received from other systems.

In API design and software development, callersupplied data must be validated and sanitized before use. Design patterns include input validation, type checks, length checks, and constraints; coupling with data models; using prepared statements for database queries; escaping outputs for contexts like HTML or SQL; and robust error handling. Treating such data carefully helps prevent errors and security vulnerabilities.

Handling strategies include fail-fast or fail-safe responses when data is invalid, applying defaults when appropriate, and using defensive coding practices to minimize risk. Explicit contracts, clear data schemas, and thorough documentation help downstream components understand what to expect from callersupplied data and how to process it correctly.

Related terms include user-supplied data and untrusted input. The concept is central to secure coding practices and is contrasted with provider-supplied or internally generated data.