Go port fowarding

portfoward.go

package main

import (
  "os"
	"bufio"
	"fmt"
	"log"
	"net"
)

const DEBUG = false
const BIND_PORT = "6666"
const BIND_HOST = "0.0.0.0"
const FORWARD_PORT = "6667"
const FORWARD_HOST = "irc.dot.org.es"


// Server ...
type Server struct {
	host string
	port string
}

// Client ...
type Client struct {
	conn net.Conn
}

// Config ...
type Config struct {
	Host string
	Port string
}

// New ...
func New(config *Config) *Server {
	return &Server{
		host: config.Host,
		port: config.Port,
	}
}

// Run ...
func (server *Server) Run() {
	listener, err := net.Listen("tcp", fmt.Sprintf("%s:%s", server.host, server.port))
	if err != nil {
		log.Fatal(err)
	}
	defer listener.Close()

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

		client := &Client{
			conn: conn,
		}
		go client.handleRequest()
	}
}

func foward_client(bind_conn net.Conn) net.Conn {
  tcpAddr, err := net.ResolveTCPAddr("tcp", FORWARD_HOST + ":" + FORWARD_PORT)
  if err != nil {
      println("ResolveTCPAddr failed:", err.Error())
      os.Exit(1)
  }

  conn, err := net.DialTCP("tcp", nil, tcpAddr)
  if err != nil {
      println("Dial failed:", err.Error())
      os.Exit(1)
  }

  go func(){
    for {
      reader := bufio.NewReader(conn)
      for {
        message, err := reader.ReadString('\n')
        if err != nil {
          println("Write to server failed:", err.Error())
          bind_conn.Close()
          return
        }
        if (DEBUG) {
          fmt.Printf("Server message: %s", string(message))
        }
        bind_conn.Write([]byte(message + "\n"))
      }
    }
  }()
  return conn
}

func (client *Client) handleRequest() {
  server_conn := foward_client(client.conn)
  defer server_conn.Close()

	reader := bufio.NewReader(client.conn)
	for {
		message, err := reader.ReadString('\n')
		if err != nil {
			client.conn.Close()
			return
		}
    if (DEBUG) {
      fmt.Printf("Message incoming: %s", string(message))
    }
		server_conn.Write([]byte(message + "\n"))
	}
}

func main() {
  server := New(&Config{
    Host: BIND_HOST,
    Port: BIND_PORT,
  })
  server.Run()
}