package main

import (
  "net"
  "os"
  "fmt"
)

func main()  {
  service := ":1201"
  tcpAddr, err := net.ResolveTCPAddr("tcp4", service)
  checkError(err)

  listener, err := net.ListenTCP("tcp", tcpAddr)
  checkError(err)

  for {
    conn, err := listener.Accept()
    if err != nil {
      continue
    }

    go handleClient(conn)
  }
}

func handleClient(conn net.Conn) {
  // close connection on exit
  defer conn.Close()

  var buf [512]byte

  for {
    // read up to 512 bytes
    n, err := conn.Read(buf[0:])
    if err != nil {
      return
    }

    // write the n bytes read
    _, err2 := conn.Write(buf[0:n])
    if err2 != nil {
      return
    }
  }
}

func checkError(err error) {
  if err != nil {
    fmt.Fprintf(os.Stderr, "Fatal error: %s", err.Error())
    os.Exit(1)
  }
}