89 lines
2.7 KiB
TypeScript
89 lines
2.7 KiB
TypeScript
import { headers } from "next/headers";
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import { redis } from "@/lib/redis";
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/**
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* Fixed-window rate limiter with optional Redis backend. Falls back to in-process
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* Map when Redis is unavailable or unconfigured — fine for single-server deployments.
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*
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* Periodic cleanup runs every 5 minutes to keep the in-process map bounded.
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*/
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type Bucket = { count: number; resetAt: number };
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const buckets = new Map<string, Bucket>();
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export interface RateLimitResult {
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ok: boolean;
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/** Seconds until the window resets (0 when allowed). */
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retryAfter: number;
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}
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const CLEANUP_INTERVAL_MS = 300_000;
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const MAX_BUCKETS = 10_000;
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let lastCleanup = Date.now();
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function cleanup(): void {
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const now = Date.now();
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if (now - lastCleanup < CLEANUP_INTERVAL_MS) return;
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lastCleanup = now;
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if (buckets.size <= MAX_BUCKETS) {
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for (const [k, b] of buckets) if (now >= b.resetAt) buckets.delete(k);
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} else {
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for (const [k, b] of buckets) if (now >= b.resetAt) buckets.delete(k);
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if (buckets.size > MAX_BUCKETS) {
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const sorted = [...buckets.entries()].sort((a, b) => a[1].resetAt - b[1].resetAt);
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const toRemove = Math.floor(sorted.length * 0.2);
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for (let i = 0; i < toRemove; i++)
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// eslint-disable-next-line security/detect-object-injection -- numeric array index
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buckets.delete(sorted[i][0]);
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}
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}
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}
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export async function rateLimit(key: string, limit: number, windowMs: number): Promise<RateLimitResult> {
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const now = Date.now();
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if (redis) {
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try {
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const windowKey = `ratelimit:${key}`;
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const current = await redis.incr(windowKey);
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if (current === 1) await redis.pexpire(windowKey, windowMs);
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const ttl = current === 1 ? windowMs : Math.max(0, await redis.pttl(windowKey));
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if (current > limit) {
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return { ok: false, retryAfter: Math.ceil(ttl / 1000) };
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}
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return { ok: true, retryAfter: 0 };
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} catch {
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// Redis unavailable — fall through to in-memory
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}
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}
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cleanup();
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const bucket = buckets.get(key);
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if (!bucket || now >= bucket.resetAt) {
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buckets.set(key, { count: 1, resetAt: now + windowMs });
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return { ok: true, retryAfter: 0 };
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}
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if (bucket.count >= limit) {
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return { ok: false, retryAfter: Math.max(1, Math.ceil((bucket.resetAt - now) / 1000)) };
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}
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bucket.count += 1;
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return { ok: true, retryAfter: 0 };
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}
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/** Best-effort client IP from the proxy headers our edge proxy forwards. */
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export async function clientIp(): Promise<string> {
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try {
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const h = await headers();
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return (
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h.get("x-real-client-ip") ??
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h.get("cf-connecting-ip") ??
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h.get("x-forwarded-for")?.split(",")[0]?.trim() ??
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h.get("x-real-ip") ??
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"0.0.0.0"
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);
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} catch {
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return "0.0.0.0";
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}
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}
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