rate-limiter.js•3.87 kB
/**
* Rate Limiter Module
* Prevents abuse through request throttling
*/
export class RateLimiter {
constructor(options = {}) {
this.limits = {
perMinute: options.perMinute || 60,
perHour: options.perHour || 500,
perDay: options.perDay || 5000
};
this.counters = {
perMinute: new Map(),
perHour: new Map(),
perDay: new Map()
};
// Cleanup intervals
setInterval(() => this.cleanup('perMinute'), 60 * 1000);
setInterval(() => this.cleanup('perHour'), 60 * 60 * 1000);
setInterval(() => this.cleanup('perDay'), 24 * 60 * 60 * 1000);
}
/**
* Check if request is allowed
* @param {string} identifier - Client identifier (token, IP, etc.)
* @returns {object} - { allowed: boolean, retryAfter: number|null }
*/
checkLimit(identifier) {
const now = Date.now();
// Check each time window
for (const [window, limit] of Object.entries(this.limits)) {
const counter = this.counters[window];
const key = `${identifier}:${this.getWindowKey(now, window)}`;
const count = counter.get(key) || 0;
if (count >= limit) {
return {
allowed: false,
retryAfter: this.getRetryAfter(window, now),
limit,
window
};
}
}
// Increment counters
this.increment(identifier, now);
return { allowed: true };
}
/**
* Increment request counters
*/
increment(identifier, now = Date.now()) {
for (const window of Object.keys(this.limits)) {
const counter = this.counters[window];
const key = `${identifier}:${this.getWindowKey(now, window)}`;
counter.set(key, (counter.get(key) || 0) + 1);
}
}
/**
* Get window key for timestamp
*/
getWindowKey(timestamp, window) {
const date = new Date(timestamp);
switch (window) {
case 'perMinute':
case 'minute':
return `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}-${date.getHours()}-${date.getMinutes()}`;
case 'perHour':
case 'hour':
return `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}-${date.getHours()}`;
case 'perDay':
case 'day':
return `${date.getFullYear()}-${date.getMonth()}-${date.getDate()}`;
default:
return timestamp;
}
}
/**
* Calculate retry-after seconds
*/
getRetryAfter(window, now) {
const date = new Date(now);
switch (window) {
case 'perMinute':
case 'minute':
return 60 - date.getSeconds();
case 'perHour':
case 'hour':
return (60 - date.getMinutes()) * 60 - date.getSeconds();
case 'perDay':
case 'day':
return (24 - date.getHours()) * 3600 - date.getMinutes() * 60 - date.getSeconds();
default:
return 60;
}
}
/**
* Cleanup old counters
*/
cleanup(window) {
const counter = this.counters[window];
const now = Date.now();
const currentKey = this.getWindowKey(now, window);
for (const key of counter.keys()) {
if (!key.endsWith(currentKey)) {
counter.delete(key);
}
}
}
/**
* Get usage statistics
*/
getStats(identifier) {
const now = Date.now();
const stats = {};
for (const [window, limit] of Object.entries(this.limits)) {
const counter = this.counters[window];
const key = `${identifier}:${this.getWindowKey(now, window)}`;
const count = counter.get(key) || 0;
stats[window] = {
used: count,
limit,
remaining: Math.max(0, limit - count),
percentage: Math.round((count / limit) * 100)
};
}
return stats;
}
}
// Singleton instance
export const rateLimiter = new RateLimiter({
perMinute: 60, // 60 requests per minute
perHour: 500, // 500 requests per hour
perDay: 5000 // 5000 requests per day
});