修复md导入问题

src/lib/rate-limit.ts

@@ -0,0 +1,59 @@
+// 简单的内存速率限制器（基于 IP）
+
+interface RateLimitEntry {
+    count: number;
+    resetAt: number;
+}
+
+const store = new Map<string, RateLimitEntry>();
+
+// 定期清理过期条目，防止内存泄漏
+const CLEANUP_INTERVAL_MS = 5 * 60 * 1000; // 5 分钟
+setInterval(() => {
+    const now = Date.now();
+    for (const [key, entry] of store) {
+        if (now >= entry.resetAt) {
+            store.delete(key);
+        }
+    }
+}, CLEANUP_INTERVAL_MS);
+
+/**
+ * 检查请求是否超过速率限制
+ * @param key 限制键（通常是 IP 地址）
+ * @param maxAttempts 窗口期内最大尝试次数
+ * @param windowMs 窗口期（毫秒）
+ * @returns 如果超限返回 true，否则返回 false
+ */
+export function isRateLimited(
+    key: string,
+    maxAttempts: number = 5,
+    windowMs: number = 60 * 1000
+): boolean {
+    const now = Date.now();
+    const entry = store.get(key);
+
+    if (!entry || now >= entry.resetAt) {
+        store.set(key, { count: 1, resetAt: now + windowMs });
+        return false;
+    }
+
+    entry.count += 1;
+    return entry.count > maxAttempts;
+}
+
+/**
+ * 从 Request 对象中提取客户端 IP
+ */
+export function getClientIp(req: Request): string {
+    // 常见的代理头
+    const forwarded = req.headers.get("x-forwarded-for");
+    if (forwarded) {
+        return forwarded.split(",")[0].trim();
+    }
+    const realIp = req.headers.get("x-real-ip");
+    if (realIp) {
+        return realIp.trim();
+    }
+    return "unknown";
+}