如何退出Docker Remote API Exec Stream？

When I get a stream from Docker Remote API like this:

// Exec exec command
func (d *Docker) ExecStart(host, id string) (net.Conn) {
    config := map[string]interface{}{
        "Detach": false,
        "Tty":    true,
    }

    buf, _ := json.Marshal(config)

    conn, _ := net.Dial("tcp", host)
    conn.Write([]byte("POST /exec/" + id + "/start HTTP/1.1
"))
    conn.Write([]byte("Host:
"))
    conn.Write([]byte("Connection: Upgrade
"))
    conn.Write([]byte("Content-Type: application/json
"))
    conn.Write([]byte("Upgrade: tcp
"))
    conn.Write([]byte("Content-Length: " + fmt.Sprintf("%d", len(buf)) + "
"))
    conn.Write([]byte("
"))
    conn.Write(buf)
    return conn
}

After that, I disconnect the conn, but when I use curl /exec/id/json to get the status of result, the sh still running. So I want to know the best way to close the sh, even in vi mode. thx :)