How Does the Nonreentrant Modifier Implement the CEI Principle?
The nonReentrant modifier implements the CEI principle by using a mutex lock (a state variable). At the start of the function (Checks), it verifies the lock is not set.
It then sets the lock (Effects). The function's logic, including the external call (Interaction), executes.
Crucially, the lock is only released at the end of the function. This ensures that any re-entry attempt will find the lock set and revert, enforcing the order of operations.
Glossar
Nonreentrant Modifier
Vulnerability ⎊ A nonreentrant modifier, within the context of smart contract security in cryptocurrency, addresses a specific class of attack where a malicious actor exploits recursive calls to alter contract state unexpectedly.
Cei Principle
Principle ⎊ The Cei Principle, standing for Checks-Effects-Interactions, is a fundamental security design pattern in smart contract development, particularly crucial for decentralized finance applications.
Mutex Lock
Mechanism ⎊ A mutex lock, or mutual exclusion mechanism, is a programming construct designed to prevent concurrent access to shared resources within a smart contract.