feat: add rate limits to import/export

backend/src/api/rateLimits.ts

@@ -0,0 +1,18 @@
+import { Request, Response } from "express";
+import { error } from "./responses";
+
+const lastRequestsByKey: Map<string, number> = new Map();
+
+export function rateLimit(getKey: (req: Request) => string, limitMs: number, message = "Rate limited") {
+  return async (req: Request, res: Response, next) => {
+    const key = getKey(req);
+    if (lastRequestsByKey.has(key)) {
+      if (lastRequestsByKey.get(key)! > Date.now() - limitMs) {
+        return error(res, message, 429);
+      }
+    }
+
+    lastRequestsByKey.set(key, Date.now());
+    next();
+  };
+}