package main

import (
	"flag"
	"fmt"
	"io"
	"net"
	"os"
)

func main() {

	localAddr := flag.String("l", "192.168.122.1:3306", "local address we listen on")
	remoteAddr := flag.String("r", "127.0.0.1:3306", "remote address we proxy to")
	verbose := flag.Bool("v", false, "log connection")

	flag.Parse()

	local, err := net.Listen("tcp", *localAddr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "listening failed: %s \n", err.Error())
		os.Exit(-1)
	}
	for {
		conn, err := local.Accept()
		if err != nil {
			fmt.Fprintf(os.Stderr, "accepting failed: %s", err.Error())
			os.Exit(-1)
		}
		go forward(conn, *remoteAddr, *verbose)
	}
}

func forward(local net.Conn, remoteAddr string, verbose bool) {
	remote, err := net.Dial("tcp", remoteAddr)
	if err != nil {
		fmt.Fprintf(os.Stderr, "remote dial failed: %s\n", err.Error())
		return
	}
	go io.Copy(local, remote)
	go io.Copy(remote, local)

	if verbose {
		fmt.Println("message from: " + remoteAddr)
	}
}