Fix API Rate Limit Exhaustion in Meteor

Meteor's DDP (Distributed Data Protocol) is built for speed and reactivity, but its default state is 'open season' for attackers. Without explicit rate limiting, any client can spam methods or subscriptions to exhaust server resources, trigger expensive DB lookups, or brute-force sensitive endpoints. To stop resource exhaustion, we leverage the 'ddp-rate-limiter' to intercept and throttle incoming DDP messages before they hit the execution queue.

The Vulnerable Pattern

Meteor.methods({
  'user.updateProfile': function(data) {
    // VULNERABLE: This method can be called thousands of times per second
    // from a single client, leading to DB lockups or compute exhaustion.
    check(data, Object);
    return Profiles.update({ userId: this.userId }, { $set: data });
  }
});

The Secure Implementation

The secure implementation utilizes the 'ddp-rate-limiter' package to create a gatekeeper for high-risk methods. By calling `DDPRateLimiter.addRule`, we define a matcher that identifies the 'user.updateProfile' method and tracks the number of calls per `connectionId`. If a client exceeds 5 requests within a 2-second window, the server automatically rejects the request with a 'too-many-requests' error. This prevents automated scripts from flooding the Meteor event loop and ensures your application remains responsive for legitimate users.

import { DDPRateLimiter } from 'meteor/ddp-rate-limiter';
// Define the methods we want to protect
const THROTTLED_METHODS = [‘user.updateProfile’];
if (Meteor.isServer) {
// Apply rule: 5 calls every 2000ms per connection
DDPRateLimiter.addRule({
name(name) {
return THROTTLED_METHODS.includes(name);
},
// Throttle based on connection ID to stop specific attackers
connectionId() {
return true;
}
}, 5, 2000);
}
Meteor.methods({
‘user.updateProfile’: function(data) {
check(this.userId, String);
check(data, Object);
return Profiles.update({ userId: this.userId }, { $set: data });
}
});