Proxy Protocol support for Go net.Conn

Regular Go net doesn't support Proxy Protocol when being load balanced with this option enabled. This makes you loose the original remote address and will report the load balancer's address instead on net.Conn.RemoteAddr(). This package adds allows you to create net.Conn objects that know how to understand Proxy Protocol.

You can read more about this in my Proxy Protocol: what is it and how to use it with Go article.

Usage

In your server, you can do the following:

ln, err := net.Listen("tcp", *addr)
if err != nil {
	log.Fatal(err)
}

for {
	cn, err := ln.Accept()
	if err != nil {
		log.Println("ln.Accept():", err)
		continue
	}

	pcn, err := viaproxy.Wrap(cn)
	if err != nil {
		log.Println("Wrap():", err)
		continue
	}

	log.Printf("remote address is: %v", pcn.RemoteAddr())
	log.Printf("local address is: %v", pcn.LocalAddr())
	log.Printf("proxy address is: %v", pcn.ProxyAddr())
	pcn.Close()
}

Given that one can forget about this, you can also do the following:

ln, err := viaproxy.Listen("tcp", *addr)
if err != nil {
	log.Fatal(err)
}

for {
	cn, err := ln.Accept()
	if err != nil {
		log.Println("ln.Accept():", err)
		continue
	}

	// The connection should be safe to be converted to a *viaproxy.Conn
	// structure.
	pcn := conn.(*viaproxy.Conn)
	log.Printf("remote address is: %v", pcn.RemoteAddr())
	log.Printf("local address is: %v", pcn.LocalAddr())
	log.Printf("proxy address is: %v", pcn.ProxyAddr())
	pcn.Close()
}

In this case, Accept returns a generic net.Conn object. If you want to directly use a Conn object (which satisfies the net.Conn interface), you can use AcceptFromProxy instead:

ln, err := viaproxy.Listen("tcp", *addr)
if err != nil {
	log.Fatal(err)
}

for {
	cn, err := ln.AcceptFromProxy()
	if err != nil {
		log.Println("ln.Accept():", err)
		continue
	}

	// The connection should be safe to be converted to a *viaproxy.Conn
	// structure.
	log.Printf("remote address is: %v", cn.RemoteAddr())
	log.Printf("local address is: %v", cn.LocalAddr())
	log.Printf("proxy address is: %v", cn.ProxyAddr())
	cn.Close()
}

Caveats

• Only works with TCP connections.
• Both endpoints of the connection must be compatible with proxy protocol.

License

See LICENSE.