tele-recv/utils/socket.go

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) {
	var err error
	server, err = net.Listen(ServerType, address)
	if err != nil {
		log.Fatal("error in create server ", err)
	}
	defer server.Close()
	log.Println("listen on ", address)
	for ServerRunning {
		conn, err := server.Accept()
		if err != nil {
			ServerRunning = false
			log.Fatalln("error in create connection ", err)
		}
		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 WriteToClient(data string) error {
	_, err := client.Write([]byte(data + "\r\n"))
	if err != nil {
		log.Println("error in write data to client socket ", err)
		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()
	}
}