Implement AutoConnect

client/src/main/kotlin/org/hso/texturesyncclient/controller/net/AutoConnect.kt

@@ -0,0 +1,48 @@
+package org.hso.texturesyncclient.controller.net
+
+import java.io.IOException
+import java.lang.Exception
+import java.net.DatagramPacket
+import java.net.DatagramSocket
+import java.net.InetAddress
+
+class AutoConnect {
+    private constructor() {}
+
+    companion object {
+        @Throws(IOException::class)
+        fun search_server(mulicastAddr: String = "ff02::dd42:c0fe", port: Int = 10796, timeoutMs : Int = 4000): Connection {
+            val sock = DatagramSocket()
+            try {
+                sock.soTimeout = timeoutMs
+
+                val bytes = "TextureSync".toByteArray()
+
+                sock.send(
+                    DatagramPacket(
+                        bytes,
+                        0,
+                        bytes.size,
+                        InetAddress.getByName(mulicastAddr),
+                        port
+                    )
+                )
+
+                // Response is PortNum in BE
+                val portData = ByteArray(2)
+                val response = DatagramPacket(portData, portData.size)
+
+                sock.receive(response)
+
+                // 2-Byte BE to Port Number
+                val port = (portData[0].toInt().shl(8)).or(portData[1].toInt())
+
+                return Connection(response.address, port)
+            } catch ( e : Exception) {
+                throw e
+            } finally {
+                sock.close()
+            }
+        }
+    }
+}