Golang - net.Conn infinite loop on the same message - sockets

Question

I'm pretty news in Golang and only use sockets in this langage for 2days. However, I'm not sure to understand something. I know in C, I used select() to know who wrote etc, but here, no one is writing until one send a message. After this message sent, my dialTCP uses it endlessly.
I think I missunderstood something about close() but I'm not sure it comes from here.. there is my code:
package dial
import (
"errors"
"encoding/json"
m "models"
"net"
"net/http"
"time"
"server"
)
type DialTCP struct {}
// tcpKeepAliveListener sets TCP keep-alive timeouts on accepted
// connections. It's used by ListenAndServe and ListenAndServeTLS so
// dead TCP connections (e.g. closing laptop mid-download) eventually
// go away.
type tcpKeepAliveListener struct {
*net.TCPListener
}
func (ln tcpKeepAliveListener) Accept() (c net.Conn, err error) {
tc, err := ln.AcceptTCP()
if err != nil {
return
}
tc.SetKeepAlive(true)
tc.SetKeepAlivePeriod(3 * time.Minute)
return tc, nil
}
func (dialTCP *DialTCP) ListenAndServe(addr string) error {
ln, err := net.Listen("tcp", addr)
if err != nil {
return err
}
return dialTCP.Serve(tcpKeepAliveListener{ln.(*net.TCPListener)})
}
func (dialTCP *DialTCP) Serve(l net.Listener) error {
defer l.Close()
for {
conn, e := l.Accept()
if e != nil {
return e
}
// you want to create server_conn here with buffers, channels and stuff
// to use async thread safe read/write from it
go dialTCP.serve_conn(conn)
}
}
func (dialTCP *DialTCP) serve_conn(conn net.Conn) error {
// var buf [512]byte
dec := json.NewDecoder(conn)
//read 1st message he sent, should be token to connect
var auth m.DialAuthentication
dec.Decode(&auth)
user := m.User{
UUID: auth.UUID,
}
ok, sb := server.IsConnected(user)
if ok == false {
json.NewEncoder(conn).Encode(sb)
return errors.New("User isn't connected.")
} else {
user.Conn = conn
}
//defer conn.Close()
var message m.DialMessageContainer
for {
dec.Decode(&message)
switch message.Type {
case ".....":
/* ....(message, user)
case "....":
....(message, user)
// case "...":*/
default:
json.NewEncoder(conn).Encode(m.StatusBack{Description: "Bad entry.", StatusId: http.StatusNotAcceptable})
}
//defer conn.Close()
}
}
I think everything is good before serv_conn(), but the error should comes from inside the for. I tried lot of things, but this for{} in Golang... Why does it have not any params/var such as C/C++/C#/Java?
for (int i = 0; i < 10; i++) {}
I'm lost about the closing of the Conn as well, so I continue to read tutorial, post and doc about how to use it.. Days pass whitout find anything