fix(mattermost): reject oversized success text bodies

Alix-007 · Alix-007 · commit 3161c88e967d · 2026-06-26T14:07:08.000+08:00
diff --git a/extensions/mattermost/src/mattermost/client.test.ts b/extensions/mattermost/src/mattermost/client.test.ts
@@ -244,6 +244,25 @@ describe("createMattermostClient", () => {
     expect(release).toHaveBeenCalledTimes(1);
   });
 
+  it("rejects oversized guarded Mattermost success text bodies instead of truncating", async () => {
+    const release = vi.fn(async () => {});
+    const tracked = cancelTrackedResponse(`${"plain success ".repeat(7000)}tail`, {
+      status: 200,
+      headers: { "content-type": "text/plain" },
+    });
+    fetchWithSsrFGuardMock.mockResolvedValueOnce({ response: tracked.response, release });
+    const client = createMattermostClient({
+      baseUrl: "https://chat.example.com",
+      botToken: "test-token",
+    });
+
+    await expect(client.request("/users/me")).rejects.toThrow(
+      "Mattermost API /users/me: text response exceeds 65536 bytes",
+    );
+    expect(tracked.wasCanceled()).toBe(true);
+    expect(release).toHaveBeenCalledTimes(1);
+  });
+
   it("releases guarded Mattermost responses when upstream body reads fail", async () => {
     const release = vi.fn(async () => {});
     const stream = new ReadableStream<Uint8Array>({
diff --git a/extensions/mattermost/src/mattermost/client.ts b/extensions/mattermost/src/mattermost/client.ts
@@ -4,6 +4,7 @@ import {
   readProviderJsonResponse,
   readResponseTextLimited,
 } from "openclaw/plugin-sdk/provider-http";
+import { readResponseWithLimit } from "openclaw/plugin-sdk/response-limit-runtime";
 import { sleep } from "openclaw/plugin-sdk/runtime-env";
 import {
   fetchWithSsrFGuard,
@@ -94,6 +95,14 @@ function buildMattermostApiUrl(baseUrl: string, path: string): string {
   return `${normalized}/api/v4${suffix}`;
 }
 
+async function readMattermostSuccessText(res: Response, path: string): Promise<string> {
+  const bytes = await readResponseWithLimit(res, MATTERMOST_TEXT_RESPONSE_LIMIT_BYTES, {
+    onOverflow: ({ maxBytes }) =>
+      new Error(`Mattermost API ${path}: text response exceeds ${maxBytes} bytes`),
+  });
+  return new TextDecoder().decode(bytes);
+}
+
 export async function readMattermostError(res: Response): Promise<string> {
   const contentType = res.headers.get("content-type") ?? "";
   if (!res.body) {
@@ -226,7 +235,7 @@ export function createMattermostClient(params: {
     if (contentType.includes("application/json")) {
       return await readProviderJsonResponse<T>(res, `Mattermost API ${path}`);
     }
-    return (await readResponseTextLimited(res, MATTERMOST_TEXT_RESPONSE_LIMIT_BYTES)) as T;
+    return (await readMattermostSuccessText(res, path)) as T;
   };
 
   return { baseUrl, apiBaseUrl, token, request, fetchImpl };
