60 lines
1.4 KiB
TypeScript
60 lines
1.4 KiB
TypeScript
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/**
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* Simple in-memory rate limiter using fixed window approach.
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* Tracks request counts per key (typically IP) within time windows.
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*
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* For production with multiple instances, replace with Redis-based solution.
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*/
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type RateLimitEntry = {
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count: number
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resetAt: number
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}
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const store = new Map<string, RateLimitEntry>()
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export type RateLimitResult = {
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success: boolean
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remaining: number
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resetAt: number
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}
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/**
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* Check rate limit for a given key.
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* @param key - Identifier (e.g., IP address)
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* @param limit - Max requests per window
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* @param windowMs - Window size in milliseconds
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*/
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export function checkRateLimit(
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key: string,
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limit: number,
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windowMs: number
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): RateLimitResult {
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const now = Date.now()
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const entry = store.get(key)
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if (!entry || now > entry.resetAt) {
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const resetAt = now + windowMs
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store.set(key, { count: 1, resetAt })
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return { success: true, remaining: limit - 1, resetAt }
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}
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if (entry.count >= limit) {
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return { success: false, remaining: 0, resetAt: entry.resetAt }
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}
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entry.count++
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return { success: true, remaining: limit - entry.count, resetAt: entry.resetAt }
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}
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// Clean up stale entries every 5 minutes to prevent memory leaks
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if (typeof setInterval !== 'undefined') {
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setInterval(() => {
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const now = Date.now()
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for (const [key, entry] of store) {
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if (now > entry.resetAt) {
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store.delete(key)
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}
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}
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}, 5 * 60 * 1000).unref?.()
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}
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