How to fix API Rate Limit Exhaustion
in Dart Frog
Executive Summary
Rate limit exhaustion in Dart Frog is a critical vulnerability that allows attackers to perform Denial of Service (DoS) attacks, brute-force credentials, or scrape sensitive data without resistance. Because Dart Frog is a minimalist framework, it does not provide built-in throttling. Failing to implement a middleware-based governor means your application's event loop and downstream resources (like databases) are at the mercy of any automated script.
The Vulnerable Pattern
// routes/api/data.dart import 'package:dart_frog/dart_frog.dart';
// VULNERABLE: No request tracking or throttling. // An attacker can call this endpoint 10,000 times per second. Response onRequest(RequestContext context) { return Response.json(body: {‘status’: ‘success’, ‘data’: ‘sensitive_info’}); }
The Secure Implementation
The secure implementation utilizes a functional middleware to intercept incoming requests before they reach the route handler. It identifies the client via their remote IP address and maintains a sliding window of request timestamps. If the count exceeds the defined threshold (100 requests/minute), the middleware short-circuits the request and returns an HTTP 429 'Too Many Requests' status code. For high-traffic production environments, replace the in-memory Map with a distributed store like Redis to ensure state consistency across multiple instances and prevent memory exhaustion on the application server.
// middleware/rate_limiter.dart import 'package:dart_frog/dart_frog.dart';// Simple in-memory store. For production, use Redis. final Map<String, List
> _history = {}; const _limit = 100; const _window = Duration(minutes: 1); Handler rateLimiter(Handler handler) { return (context) async { final ip = context.request.connectionInfo.remoteAddress.address; final now = DateTime.now();
// Cleanup old entries and check limit final timestamps = (_history[ip] ?? []).where((t) => t.isAfter(now.subtract(_window))).toList(); if (timestamps.length >= _limit) { return Response(statusCode: 429, body: 'Rate limit exceeded. Try again later.'); } timestamps.add(now); _history[ip] = timestamps; return handler(context);}; }
// _middleware.dart Handler buildInternalMiddleware(Handler handler) { return handler.use(rateLimiter); }
Your Dart Frog API
might be exposed to API Rate Limit Exhaustion
74% of Dart Frog apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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