Fix discovery and connection issues on Windows

Author: 1RandomDev

XTOOL_PROTOCOL.md

@@ -290,6 +290,8 @@ $ echo '{"requestId":123456}' | socat - UDP-DATAGRAM:255.255.255.255:20000,broad
 }
 ```
 
+After receiving the UDP request on port 20000, the device will first try to reply on TCP port 20001 and only then send the same response on UDP port 20000. If TCP port 20001 is blocked by a firewall the device will wait until the connections timed out before using UDP, creating a 20 second delay.
+
 
 #### GCODE
 Incomplete right now.

main/device-controller.js

@@ -67,7 +67,7 @@ module.exports.connect = async (address, callback, config_) => {
             lastHeartbeat = Date.now();
             heartbeatTimer = setInterval(() => {
                 websocket.ping();
-                if(lastHeartbeat + 4100 < Date.now()) {
+                if(lastHeartbeat + 6100 < Date.now()) {
                     wsCallback('err:TIMEOUT');
                     console.log('Connection to device timed out.');
                     websocket.terminate();

main/discovery.js

@@ -1,31 +1,44 @@
 const dgram = require('dgram');
+const net = require('net');
 
 const DISCOVERY_PORT = 20000;
+const DISCOVERY_TCP_PORT = 20001;
 
 module.exports.scanDevices = () => {
     return new Promise(resolve => {
         const requestId = Date.now();
         const devices = [];
-        const socket = dgram.createSocket('udp4');
-
-        socket.on('listening', () => {
-            socket.setBroadcast(true);
-            socket.send(JSON.stringify({requestId}), DISCOVERY_PORT, '255.255.255.255');
-            console.log('Starting device scan.');
-        });
-
-        socket.on('message', (message, remote) => {
+        const handleResponse = message => {
             try {
                 message = JSON.parse(message);
                 if(message.requestId == requestId && !!message.ip && !!message.name) {
+                    if(devices.find(dev => dev.ip == message.ip)) return;
                     delete message.requestId;
                     devices.push(message);
                     console.log('Discovered device: '+JSON.stringify(message));
                 }
             } catch(e) {}
+        };
+        const socket = dgram.createSocket('udp4');
+
+        // Request
+        socket.on('listening', () => {
+            socket.setBroadcast(true);
+            socket.send(JSON.stringify({requestId}), DISCOVERY_PORT, '255.255.255.255');
+            console.log('Starting device scan.');
+        });
+
+        // UDP Response
+        socket.on('message', handleResponse);
+
+        // TCP Response
+        const tcpServer = net.createServer(socket => {
+            socket.on('data', handleResponse);
         });
+        tcpServer.listen(DISCOVERY_TCP_PORT);
 
         setTimeout(() => {
+            tcpServer.close();
             socket.close();
             resolve(devices);
         }, 2000);