fix run, add connection check

utils/socket.go

@@ -1,17 +1,21 @@
 package utils
 
 import (
+	"io"
 	"log"
 	"net"
+	"time"
 )
 
 const ServerType = "tcp"
 
 var ServerRunning = false
 var client net.Conn
+var server net.Listener
 
 func Listen(address string) {
-	server, err := net.Listen(ServerType, address)
+	var err error
+	server, err = net.Listen(ServerType, address)
 	if err != nil {
 		log.Fatal("error in create server ", err)
 	}
@@ -25,14 +29,22 @@ func Listen(address string) {
 		}
 		if client == nil {
 			client = conn
+			log.Println("client connected ", client.RemoteAddr())
+
 		} else {
 			log.Println("client already connected, close")
+			client.Close()
+			client = nil
 			conn.Close()
 		}
+		if IsClientConnected() {
+			connCheck()
+		}
+		time.Sleep(2 * time.Second)
 	}
 }
 
-func Write(data string) {
+func WriteToClient(data string) error {
 	defer func() {
 		client.Close()
 		client = nil
@@ -43,4 +55,29 @@ func Write(data string) {
 		client.Close()
 		client = nil
 	}
+	return err
+}
+
+func connCheck() bool {
+	_, err := client.Read(make([]byte, 0))
+	if err != nil && err != io.EOF {
+		// this connection is invalid
+		log.Println("conn closed....", err)
+		client = nil
+		return false
+	}
+	return true
+}
+
+func IsClientConnected() bool {
+	return client != nil
+}
+
+func StopSocketServer() {
+	if IsClientConnected() {
+		client.Close()
+	}
+	if server != nil {
+		server.Close()
+	}
 }