fix(synology-chat): bound outgoing response deadlines (#110520)

Co-authored-by: Pick-cat <huang.ting3@xydigit.com>

extensions/synology-chat/src/client.loopback.test.ts

@@ -1,7 +1,7 @@
 import { once } from "node:events";
 import * as http from "node:http";
 import { afterEach, describe, expect, it, vi } from "vitest";
-import { resolveLegacyWebhookNameToChatUserId } from "./client.js";
+import { resolveLegacyWebhookNameToChatUserId, sendMessage } from "./client.js";
 
 const USER_LIST_RESPONSE_MAX_BYTES = 1 * 1024 * 1024;
 
@@ -149,4 +149,54 @@ describe("Synology Chat user_list loopback", () => {
     expect(elapsedMs).toBeGreaterThanOrEqual(timeoutMs - 50);
     expect(elapsedMs).toBeLessThan(timeoutMs + 1_500);
   });
+
+  it("bounds a dripping chatbot response with a wall-clock deadline", async () => {
+    let requestCount = 0;
+    server = http.createServer((_req, res) => {
+      requestCount += 1;
+      res.on("error", () => {});
+      res.writeHead(200, {
+        "Content-Type": "application/json",
+        "Transfer-Encoding": "chunked",
+      });
+      const dripTimer = setInterval(() => {
+        if (!res.writableEnded && !res.destroyed) {
+          res.write("x");
+        }
+      }, 20);
+      res.on("close", () => clearInterval(dripTimer));
+      res.write("x");
+    });
+    server.on("clientError", (_err, socket) => socket.destroy());
+    server.listen(0, "127.0.0.1");
+    await once(server, "listening");
+
+    const address = server.address();
+    if (!address || typeof address === "string") {
+      throw new Error("expected loopback server address");
+    }
+    const incomingUrl = `http://127.0.0.1:${address.port}/webapi/entry.cgi`;
+    const timeoutMs = 250;
+    const nativeSetTimeout = globalThis.setTimeout;
+    const timeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    timeoutSpy.mockImplementation(((
+      callback: (...args: unknown[]) => void,
+      delay?: number,
+      ...args: unknown[]
+    ) =>
+      nativeSetTimeout(
+        callback,
+        delay === 30_000 ? timeoutMs : delay,
+        ...args,
+      )) as typeof setTimeout);
+
+    const startedAt = performance.now();
+    await expect(sendMessage(incomingUrl, "hello")).resolves.toBe(false);
+    const elapsedMs = performance.now() - startedAt;
+
+    expect(requestCount).toBe(3);
+    expect(timeoutSpy).toHaveBeenCalledWith(expect.any(Function), 30_000);
+    expect(elapsedMs).toBeGreaterThanOrEqual(timeoutMs * 3 - 100);
+    expect(elapsedMs).toBeLessThan(3_500);
+  });
 });

extensions/synology-chat/src/client.ts

@@ -21,6 +21,8 @@ const MIN_SEND_INTERVAL_MS = 500;
 const USER_LIST_RESPONSE_MAX_BYTES = 1 * 1024 * 1024;
 /** Wall-clock budget for user_list fetch including response body. */
 const USER_LIST_REQUEST_TIMEOUT_MS = 15_000;
+/** Wall-clock budget for outgoing webhook requests including response body. */
+const POST_REQUEST_TIMEOUT_MS = 30_000;
 let lastSendTime = 0;
 let sendQueue: Promise<void> = Promise.resolve();
 
@@ -335,6 +337,24 @@ function parseNumericUserId(userId?: string | number): number | undefined {
 
 function doPost(url: string, body: string, allowInsecureSsl = false): Promise<boolean> {
   return new Promise((resolve, reject) => {
+    let settled = false;
+    let response: http.IncomingMessage | undefined;
+    let deadlineTimer: ReturnType<typeof setTimeout> | undefined;
+    const finish = (result: { ok?: boolean; error?: Error }) => {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      if (deadlineTimer !== undefined) {
+        clearTimeout(deadlineTimer);
+        deadlineTimer = undefined;
+      }
+      if (result.error) {
+        reject(result.error);
+        return;
+      }
+      resolve(result.ok === true);
+    };
     let parsedUrl: URL;
     try {
       parsedUrl = new URL(url);
@@ -352,24 +372,30 @@ function doPost(url: string, body: string, allowInsecureSsl = false): Promise<bo
           "Content-Type": "application/x-www-form-urlencoded",
           "Content-Length": Buffer.byteLength(body),
         },
-        timeout: 30_000,
         // Synology NAS may use self-signed certs on local network.
         // Set allowInsecureSsl: true in channel config to skip verification.
         rejectUnauthorized: !allowInsecureSsl,
       },
       (res) => {
+        response = res;
         res.on("end", () => {
-          resolve(res.statusCode === 200);
+          finish({ ok: res.statusCode === 200 });
         });
+        res.on("error", (error) => finish({ error }));
         res.resume();
       },
     );
 
-    req.on("error", reject);
-    req.on("timeout", () => {
+    req.on("error", (error) => finish({ error }));
+    // ClientRequest timeout is socket-idle based. Keep one absolute budget
+    // across connect, upload, and response drain so trickling bodies terminate.
+    deadlineTimer = setTimeout(() => {
+      const error = new Error("Request timeout");
+      finish({ error });
+      response?.destroy();
       req.destroy();
-      reject(new Error("Request timeout"));
-    });
+    }, POST_REQUEST_TIMEOUT_MS);
+    deadlineTimer.unref?.();
     req.write(body);
     req.end();
   });