Fix port knocking before SSH connect (#1013)

src/backend/ssh/terminal-port-knocking.test.ts

@@ -0,0 +1,57 @@
+import { EventEmitter } from "events";
+import { describe, expect, it, vi } from "vitest";
+import { performPortKnocking } from "./terminal-auth-helpers.js";
+
+class FakeTcpSocket extends EventEmitter {
+  readonly connect = vi.fn();
+  readonly destroy = vi.fn();
+}
+
+describe("performPortKnocking", () => {
+  it("continues through TCP knock errors", async () => {
+    const first = new FakeTcpSocket();
+    const second = new FakeTcpSocket();
+    const wait = vi.fn().mockResolvedValue(undefined);
+
+    const knocking = performPortKnocking(
+      "192.0.2.10",
+      [
+        { port: 1111, protocol: "tcp", delay: 10 },
+        { port: 2222, protocol: "tcp", delay: 0 },
+      ],
+      {
+        createTcpSocket: vi
+          .fn()
+          .mockReturnValueOnce(first)
+          .mockReturnValueOnce(second),
+        wait,
+      },
+    );
+
+    first.emit("error", new Error("closed"));
+    await Promise.resolve();
+    second.emit("connect");
+    await knocking;
+
+    expect(first.connect).toHaveBeenCalledWith(1111, "192.0.2.10");
+    expect(second.connect).toHaveBeenCalledWith(2222, "192.0.2.10");
+    expect(first.destroy).toHaveBeenCalled();
+    expect(second.destroy).toHaveBeenCalled();
+    expect(wait).toHaveBeenCalledWith(10);
+  });
+
+  it("times out TCP knocks that are silently dropped", async () => {
+    const socket = new FakeTcpSocket();
+    const wait = vi.fn().mockResolvedValue(undefined);
+
+    await performPortKnocking("192.0.2.10", [{ port: 1111, delay: 0 }], {
+      createTcpSocket: () => socket as never,
+      tcpTimeoutMs: 1,
+      wait,
+    });
+
+    expect(socket.connect).toHaveBeenCalledWith(1111, "192.0.2.10");
+    expect(socket.destroy).toHaveBeenCalled();
+    expect(wait).not.toHaveBeenCalled();
+  });
+});