feat: start vnc server if not started yet

backend/.env.example

@@ -9,3 +9,4 @@ PC_MAC_ADDR=
 TERMINAL_SHELL=
 FILE_DIRS="/some/path;/another/path"
 VNC_PORT=5901
+VNC_START_CMD=vncserver :1

backend/lib/vnc.ts

@@ -0,0 +1,38 @@
+import type { WebSocket } from "ws";
+import { websockify } from "./websockify";
+import net from "node:net";
+import { spawn } from "node:child_process";
+
+const VNC_PORT = parseInt(process.env.VNC_PORT || "") || 5901;
+const VNC_START_CMD = process.env.VNC_START_CMD;
+
+export const createVNCSession = async (ws: WebSocket) => {
+  const isVncStarted = await isPortOpen(VNC_PORT);
+
+  // VNC is not started, start it.
+  if (!isVncStarted && VNC_START_CMD) {
+    const cmd = VNC_START_CMD.split(" ");
+    const child = spawn(cmd[0], cmd.slice(1));
+
+    await new Promise((resolve) => {
+      child.on("close", () => resolve(null));
+    });
+  }
+
+  websockify(ws, "localhost", VNC_PORT);
+};
+
+async function isPortOpen(port: number) {
+  return new Promise((resolve) => {
+    const tester = net
+      .createServer()
+      .once("error", function (err: any) {
+        resolve(err.code === "EADDRINUSE");
+      })
+      .once("listening", function () {
+        tester.close();
+        resolve(false);
+      })
+      .listen(port);
+  });
+}

backend/websocket.ts

@@ -1,9 +1,7 @@
 import { WebSocketServer } from "ws";
 import { verifyToken } from "./lib/jwt";
 import { createTerminalSession } from "./lib/terminal";
-import { websockify } from "./lib/websockify";
+import { createVNCSession } from "./lib/vnc";
-
-const VNC_PORT = parseInt(process.env.VNC_PORT || "") || 5901;
 
 const createWsServer = (server: any) => {
   const wss = new WebSocketServer({ server: server as never });
@@ -25,7 +23,7 @@ const createWsServer = (server: any) => {
     }
 
     if (url.pathname === "/vnc") {
-      websockify(ws, "localhost", VNC_PORT);
+      createVNCSession(ws);
     }
 
     ws.on("error", console.error);