Proxy Protocol Checker

main.go

package main

import (
	"flag"
	"io"
	"log"
	"net"
	"os"

	"github.com/armon/go-proxyproto"
)

func cp(conn net.Conn) {
	defer conn.Close()
	if _, err := io.Copy(os.Stdout, conn); err != nil {
            log.Print(err)
        }
}

func main() {
	useProxyProto := flag.Bool("proxy", false, "enable Proxy Protocol")
	flag.Parse()

	host := flag.Arg(0)
	ln, err := net.Listen("tcp", host)
	if err != nil {
		log.Fatal(err)
	}

	if *useProxyProto {
		ln = &proxyproto.Listener{ln}
	}

	for {
		conn, err := ln.Accept()
		if err != nil {
			log.Print(err)
			continue
		}
		remote := conn.RemoteAddr()
		log.Printf("remote: %s", remote)
		go cp(conn)
	}
}