fix(auth): prevent race condition on user creation with DB-level uniqueness #159
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Previously, we checked for existing email and username before user creation. This opened a race condition where simultaneous requests could bypass checks and insert conflicting records. Now we rely on Prisma's unique constraints and remove the manual pre-checks. If a duplicate is attempted, we catch the P2002 error and return proper validation. This also reduces DB queries from 3 to 1, improving performance and atomicity.
Micro-Learning Topic: Race condition (Detected by phrase)Matched on "race condition"A race condition is a flaw that produces an unexpected result when the timing of actions impact other actions. Try a challenge in Secure Code Warrior |
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Description:
This PR fixes a race condition that could occur when two users tried to register simultaneously with the same email or username.
Previously, we manually checked for existing emails and usernames before creating a user using the
checkUserUniquenessfunction, which allowed a brief window where concurrent requests could bypass these checks and attempt duplicates. Although the database’s unique constraints prevented actual duplicate records, the application did not handle the resulting errors properly because user creation was not wrapped in a try-catch block. This led to unhandled errors without clear validation feedback.Now, we have removed the
checkUserUniquenessfunction and rely on Prisma’s built-in unique constraints at the database level to enforce uniqueness atomically. The user creation logic is wrapped in a try-catch block that catches Prisma’sP2002error and returns clean, detailed validation messages when duplicates are attempted.Benefits: