fix(auth): harden Windows storage bridge

backend/src/auth/windows-auth-storage.ts

@@ -1,5 +1,6 @@
 import { spawn } from "node:child_process";
 import { win32 } from "node:path";
+import type { Readable, Writable } from "node:stream";
 import { z } from "zod";
 
 const PROTOCOL_VERSION = 1;
@@ -46,11 +47,29 @@ export interface WindowsAuthStorageInvocationResult {
   stderr: Buffer;
 }
 
+interface WindowsAuthStorageChild {
+  readonly stdin: Writable | null;
+  readonly stdout: Readable | null;
+  readonly stderr: Readable | null;
+  kill(signal?: NodeJS.Signals | number): boolean;
+  on(event: "error", listener: (error: Error) => void): this;
+  once(event: "error", listener: (error: Error) => void): this;
+  once(event: "close", listener: (code: number | null, signal: NodeJS.Signals | null) => void): this;
+}
+
+type WindowsAuthStorageSpawn = (
+  executable: string,
+  args: readonly string[],
+  options: { shell: false; windowsHide: true; stdio: ["pipe", "pipe", "pipe"]; env: NodeJS.ProcessEnv },
+) => WindowsAuthStorageChild;
+
 export interface WindowsAuthStorageBridgeOptions {
   /** Test-only transport seam. Production always uses the no-shell child-process invocation. */
   invoke?: (invocation: WindowsAuthStorageInvocation) => Promise<WindowsAuthStorageInvocationResult>;
   /** Optional configured tht path. Defaults to THT_BIN, then the safe bare command `tht`. */
   thtExecutable?: string;
+  /** Test-only child-launch seam; production uses the fixed no-shell Node child-process launcher. */
+  spawnChild?: WindowsAuthStorageSpawn;
 }
 
 const responseSchema = z.strictObject({
@@ -141,65 +160,111 @@ function environmentForBridge(): NodeJS.ProcessEnv {
   };
 }
 
-async function invokeTht(invocation: WindowsAuthStorageInvocation): Promise<WindowsAuthStorageInvocationResult> {
+const spawnTht: WindowsAuthStorageSpawn = (executable, args, options) => spawn(executable, [...args], options);
+
+async function invokeTht(
+  invocation: WindowsAuthStorageInvocation,
+  spawnChild: WindowsAuthStorageSpawn = spawnTht,
+): Promise<WindowsAuthStorageInvocationResult> {
   return new Promise((resolve, reject) => {
     let settled = false;
+    let closeSeen = false;
+    let aborted = false;
+    let closeCode: number | null = null;
+    let closeSignal: NodeJS.Signals | null = null;
     let timeout: NodeJS.Timeout | undefined;
     const stdout: Buffer[] = [];
     const stderr: Buffer[] = [];
     let stdoutBytes = 0;
     let stderrBytes = 0;
+    let child: WindowsAuthStorageChild | undefined;
     const settle = (callback: () => void): void => {
       if (settled) return;
       settled = true;
       if (timeout !== undefined) clearTimeout(timeout);
       callback();
     };
-    let child: ReturnType<typeof spawn>;
+    const stopStream = (stream: Writable | Readable | null | undefined): void => {
+      try { stream?.destroy(); } catch { /* abort is already fail-closed */ }
+    };
+    const finishAfterClose = (): void => {
+      if (!closeSeen || settled) return;
+      if (aborted || typeof closeCode !== "number" || !Number.isInteger(closeCode) || closeSignal !== null) {
+        settle(() => reject(invalid()));
+        return;
+      }
+      const code = closeCode;
+      settle(() => resolve({
+        code,
+        stdout: Buffer.concat(stdout),
+        stderr: Buffer.concat(stderr),
+      }));
+    };
+    const abort = (): void => {
+      if (aborted || settled) return;
+      aborted = true;
+      if (timeout !== undefined) clearTimeout(timeout);
+      if (child !== undefined) {
+        stopStream(child.stdin);
+        stopStream(child.stdout);
+        stopStream(child.stderr);
+        try { child.kill(); } catch { /* the close handler still owns settlement */ }
+      }
+      finishAfterClose();
+    };
     try {
-      child = spawn(invocation.executable, [...invocation.args], {
+      child = spawnChild(invocation.executable, invocation.args, {
         shell: false,
         windowsHide: true,
         stdio: ["pipe", "pipe", "pipe"],
         env: environmentForBridge(),
       });
     } catch {
-      reject(invalid());
+      settle(() => reject(invalid()));
       return;
     }
+    child.once("close", (code, signal) => {
+      closeSeen = true;
+      closeCode = code;
+      closeSignal = signal;
+      if (code === null || signal !== null) aborted = true;
+      finishAfterClose();
+    });
+    child.on("error", abort);
     if (!child.stdin || !child.stdout || !child.stderr) {
-      try { child.kill(); } catch { /* unavailable child streams fail closed */ }
-      reject(invalid());
+      abort();
       return;
     }
     const stdin = child.stdin;
     const stdoutStream = child.stdout;
     const stderrStream = child.stderr;
     timeout = setTimeout(() => {
-      try { child.kill(); } catch { /* child failure is converted below */ }
-      settle(() => reject(invalid()));
+      abort();
     }, invocation.timeoutMs);
-    child.once("error", () => settle(() => reject(invalid())));
     stdoutStream.on("data", (chunk: Buffer) => {
+      if (aborted) return;
       stdoutBytes += chunk.length;
       if (stdoutBytes > MAX_RESPONSE_BYTES) {
-        try { child.kill(); } catch { /* child failure is converted below */ }
-        settle(() => reject(invalid()));
+        abort();
         return;
       }
       stdout.push(Buffer.from(chunk));
     });
     stderrStream.on("data", (chunk: Buffer) => {
+      if (aborted) return;
       stderrBytes += chunk.length;
-      if (stderrBytes <= MAX_RESPONSE_BYTES) stderr.push(Buffer.from(chunk));
+      if (stderrBytes > MAX_RESPONSE_BYTES) {
+        abort();
+        return;
+      }
+      stderr.push(Buffer.from(chunk));
     });
-    child.once("close", (code) => settle(() => resolve({
-      code: code ?? -1,
-      stdout: Buffer.concat(stdout),
-      stderr: Buffer.concat(stderr),
-    })));
-    stdin.once("error", () => settle(() => reject(invalid())));
-    stdin.end(invocation.input);
+    stdin.once("error", abort);
+    try {
+      stdin.end(invocation.input);
+    } catch {
+      abort();
+    }
   });
 }
 
@@ -214,7 +279,7 @@ function contentFrom(response: BridgeResponse, maximum: number): Buffer | undefi
 
 export function createWindowsAuthStorageBridge(options: WindowsAuthStorageBridgeOptions = {}): WindowsAuthStorageBridge {
   const executable = safeThtExecutable(options.thtExecutable);
-  const invoke = options.invoke ?? invokeTht;
+  const invoke = options.invoke ?? ((invocation: WindowsAuthStorageInvocation) => invokeTht(invocation, options.spawnChild));
   const request = async (value: BridgeRequest): Promise<BridgeResponse> => {
     try {
       const response = await invoke({

backend/test/auth-session-store.test.ts

@@ -59,6 +59,7 @@ import {
   type AuthSessionStore,
   type SessionCreateInput,
 } from "../src/auth/session-store.js";
+import { createWindowsAuthStorageBridge } from "../src/auth/windows-auth-storage.js";
 
 const roots: string[] = [];
 const base = new Date("2030-01-02T03:04:05.000Z");
@@ -579,6 +580,65 @@ describe("file-backed auth session store", () => {
     }
   });
 
+  test("prunes nonempty Windows directories through the Go lower-camel list DTO", async () => {
+    const records = new Map<string, Buffer>();
+    const key = (directory: string, entry: string) => `${directory}/${entry}`;
+    const response = (value: Record<string, unknown>) => ({
+      code: 0,
+      stdout: Buffer.from(`${JSON.stringify({ version: 1, ok: true, ...value })}\n`),
+      stderr: Buffer.alloc(0),
+    });
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async ({ input }) => {
+        const request = JSON.parse(input.toString("utf8")) as {
+          operation: string;
+          directory: "sessions" | "oidc";
+          filename?: string;
+          contentBase64?: string;
+        };
+        const entry = request.filename === undefined ? undefined : key(request.directory, request.filename);
+        switch (request.operation) {
+          case "create":
+            if (entry === undefined || request.contentBase64 === undefined || records.has(entry)) return response({ created: false });
+            records.set(entry, Buffer.from(request.contentBase64, "base64"));
+            return response({ created: true });
+          case "read":
+            return entry === undefined || !records.has(entry)
+              ? response({})
+              : response({ found: true, contentBase64: records.get(entry)?.toString("base64") });
+          case "remove":
+            return response({ removed: entry !== undefined && records.delete(entry) });
+          case "list":
+            return response({
+              // Raw lower-camel entry objects, exactly as authstorage's Go response emits them.
+              entries: [...records.keys()]
+                .filter((value) => value.startsWith(`${request.directory}/`))
+                .map((value) => ({ name: value.slice(request.directory.length + 1), modifiedUnixMs: base.getTime() })),
+            });
+          default:
+            throw new Error("unexpected bridge operation");
+        }
+      },
+    });
+    const originalPlatform = Object.getOwnPropertyDescriptor(process, "platform");
+    if (!originalPlatform) throw new Error("platform descriptor unavailable");
+    Object.defineProperty(process, "platform", { configurable: true, value: "win32" });
+    try {
+      const store = createFileAuthSessionStore("C:\\ProgramData\\ThothII\\auth", {
+        currentAuthConfigRevision: () => revision,
+        findLocalUser: async () => validLocalUser,
+      }, { windowsStorageBridge: bridge });
+      await create(store, { idleTtlMs: 60_000, absoluteTtlMs: 60_000 });
+      await store.createOidcState({ nonce: "n".repeat(43), codeVerifier: "v".repeat(43), returnTo: "/" }, base);
+
+      await expect(store.prune(new Date(base.getTime() + 11 * 60_000))).resolves.toBe(2);
+      expect(records).toHaveLength(0);
+    } finally {
+      Object.defineProperty(process, "platform", originalPlatform);
+    }
+  });
+
   test("revokes on config, local-user, revision, enabled, or role mismatch before returning", async () => {
     const storageRoot = root();
     let currentRevision = revision;

backend/test/windows-auth-storage.test.ts

@@ -1,9 +1,31 @@
-import { describe, expect, test } from "vitest";
+import { EventEmitter } from "node:events";
+import { PassThrough } from "node:stream";
+import { describe, expect, test, vi } from "vitest";
 import { createWindowsAuthStorageBridge } from "../src/auth/windows-auth-storage.js";
 
 const root = "C:\\ProgramData\\ThothII\\auth";
 const filename = "a".repeat(64) + ".json";
 
+class FakeBridgeChild extends EventEmitter {
+  readonly stdin = new PassThrough();
+  readonly stdout = new PassThrough();
+  readonly stderr = new PassThrough();
+  readonly kill = vi.fn(() => true);
+
+  close(code = 0, signal: NodeJS.Signals | null = null): void {
+    this.emit("close", code, signal);
+  }
+}
+
+function bridgeForChild(child: FakeBridgeChild) {
+  const spawnChild = vi.fn(() => child);
+  const bridge = createWindowsAuthStorageBridge({
+    thtExecutable: "C:\\tht.exe",
+    spawnChild,
+  } as never);
+  return { bridge, spawnChild };
+}
+
 describe("Windows auth-storage bridge", () => {
   test("uses hidden tht argv and sends record bytes only over bounded stdin", async () => {
     const calls: Array<{ executable: string; args: readonly string[]; input: Buffer; timeoutMs: number }> = [];
@@ -71,4 +93,100 @@ describe("Windows auth-storage bridge", () => {
     expect(() => createWindowsAuthStorageBridge({ thtExecutable: "tht.exe && unexpected" }))
       .toThrow("auth_session_store_invalid");
   });
+
+  test("parses the lower-camel list DTO emitted by the Go helper for a nonempty directory", async () => {
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      invoke: async () => ({
+        code: 0,
+        // This is the raw JSON object emitted by authstorage.response after Go's DTO encoding.
+        stdout: Buffer.from(`{"version":1,"ok":true,"entries":[{"name":"${filename}","modifiedUnixMs":1893456245000}]}\n`),
+        stderr: Buffer.alloc(0),
+      }),
+    });
+
+    await expect(bridge.list(root, "oidc")).resolves.toEqual([
+      { name: filename, modifiedUnixMs: 1_893_456_245_000 },
+    ]);
+  });
+
+  test("aborts a stdin-closed looping helper on timeout and waits for close", async () => {
+    vi.useFakeTimers();
+    const child = new FakeBridgeChild();
+    const { bridge, spawnChild } = bridgeForChild(child);
+    const pending = bridge.list(root, "sessions");
+    const outcome = pending.then(() => "resolved", () => "rejected");
+    try {
+      await vi.advanceTimersByTimeAsync(5_000);
+      expect(spawnChild).toHaveBeenCalledOnce();
+      expect(child.kill).toHaveBeenCalledOnce();
+      expect(child.stdin.destroyed).toBe(true);
+      await expect(Promise.race([outcome, Promise.resolve("pending")])).resolves.toBe("pending");
+
+      child.close();
+      await expect(outcome).resolves.toBe("rejected");
+    } finally {
+      child.close();
+      vi.useRealTimers();
+    }
+  });
+
+  test.each(["stdout", "stderr"] as const)("aborts a %s-flooding helper and waits for close", async (stream) => {
+    const child = new FakeBridgeChild();
+    const { bridge, spawnChild } = bridgeForChild(child);
+    const pending = bridge.list(root, "sessions");
+    const outcome = pending.then(() => "resolved", () => "rejected");
+    await Promise.resolve();
+    expect(spawnChild).toHaveBeenCalledOnce();
+
+    child[stream].write(Buffer.alloc(64 * 1024 + 1));
+    await Promise.resolve();
+    expect(child.kill).toHaveBeenCalledOnce();
+    expect(child.stdin.destroyed).toBe(true);
+    await expect(Promise.race([outcome, Promise.resolve("pending")])).resolves.toBe("pending");
+
+    child.close();
+    await expect(outcome).resolves.toBe("rejected");
+  });
+
+  test("aborts a helper when its stdin errors and waits for termination", async () => {
+    const child = new FakeBridgeChild();
+    const { bridge, spawnChild } = bridgeForChild(child);
+    const stdinErrored = new Promise<void>((resolve) => child.stdin.once("error", () => resolve()));
+    child.stdin.once("finish", () => child.stdin.destroy(new Error("stdin failure")));
+    const pending = bridge.list(root, "sessions");
+    const outcome = pending.then(() => "resolved", () => "rejected");
+    await Promise.resolve();
+    expect(spawnChild).toHaveBeenCalledOnce();
+
+    await stdinErrored;
+    expect(child.kill).toHaveBeenCalledOnce();
+    child.close();
+    await expect(outcome).resolves.toBe("rejected");
+  });
+
+  test("aborts an errored child exactly once and waits for its close event", async () => {
+    const child = new FakeBridgeChild();
+    const { bridge, spawnChild } = bridgeForChild(child);
+    const pending = bridge.list(root, "sessions");
+    const outcome = pending.then(() => "resolved", () => "rejected");
+    await Promise.resolve();
+    expect(spawnChild).toHaveBeenCalledOnce();
+
+    child.emit("error", new Error("helper error"));
+    child.emit("error", new Error("duplicate helper error"));
+    expect(child.kill).toHaveBeenCalledOnce();
+    await expect(Promise.race([outcome, Promise.resolve("pending")])).resolves.toBe("pending");
+    child.close();
+    await expect(outcome).resolves.toBe("rejected");
+  });
+
+  test("fails closed when launching the helper throws before a child exists", async () => {
+    const bridge = createWindowsAuthStorageBridge({
+      thtExecutable: "C:\\tht.exe",
+      spawnChild: () => { throw new Error("launch detail must not escape"); },
+    });
+
+    await expect(bridge.list(root, "sessions")).rejects.toThrow("auth_session_store_invalid");
+  });
 });