add an example server and client

example/README.md

+# TLS handshake example
+
+Run
+```bash
+go run example/server/main.go
+```

example/client/main.go

+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"net"
+	"time"
+
+	ic "github.com/libp2p/go-libp2p-crypto"
+	peer "github.com/libp2p/go-libp2p-peer"
+	libp2ptls "github.com/libp2p/go-libp2p-tls"
+)
+
+func main() {
+	if err := startClient(); err != nil {
+		panic(err)
+	}
+}
+
+func startClient() error {
+	port := flag.Int("p", 5533, "port")
+	peerIDString := flag.String("id", "", "peer ID")
+	flag.Parse()
+
+	peerID, err := peer.IDB58Decode(*peerIDString)
+	if err != nil {
+		return err
+	}
+
+	priv, _, err := ic.GenerateECDSAKeyPair(rand.Reader)
+	if err != nil {
+		return err
+	}
+	id, err := peer.IDFromPrivateKey(priv)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Generated new peer with an ECDSA key. Peer ID: %s\n", id.Pretty())
+	tp, err := libp2ptls.New(priv)
+	if err != nil {
+		return err
+	}
+
+	remoteAddr := fmt.Sprintf("localhost:%d", *port)
+	fmt.Printf("Dialing %s\n", remoteAddr)
+	conn, err := net.Dial("tcp", remoteAddr)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Dialed raw connection to %s\n", conn.RemoteAddr())
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	sconn, err := tp.SecureOutbound(ctx, conn, peerID)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Authenticated server: %s\n", sconn.RemotePeer().Pretty())
+	data, err := ioutil.ReadAll(sconn)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Received message from server: %s\n", string(data))
+	return nil
+}

example/server/main.go

+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"flag"
+	"fmt"
+	"net"
+	"time"
+
+	ic "github.com/libp2p/go-libp2p-crypto"
+	peer "github.com/libp2p/go-libp2p-peer"
+	libp2ptls "github.com/libp2p/go-libp2p-tls"
+)
+
+func main() {
+	if err := startServer(); err != nil {
+		panic(err)
+	}
+}
+
+func startServer() error {
+	port := flag.Int("p", 5533, "port")
+	flag.Parse()
+
+	priv, _, err := ic.GenerateECDSAKeyPair(rand.Reader)
+	if err != nil {
+		return err
+	}
+	id, err := peer.IDFromPrivateKey(priv)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Generated new peer with an ECDSA key. Peer ID: %s\n", id.Pretty())
+	tp, err := libp2ptls.New(priv)
+	if err != nil {
+		return err
+	}
+
+	ln, err := net.Listen("tcp", fmt.Sprintf("localhost:%d", *port))
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Listening for new connections on %s\n", ln.Addr())
+	fmt.Printf("Now run the following command in a separate terminal:\n")
+	fmt.Printf("\tgo run example/client/main.go -p %d -id %s\n", *port, id.Pretty())
+
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			return err
+		}
+		fmt.Printf("Accepted raw connection from %s\n", conn.RemoteAddr())
+		go func() {
+			if err := handleConn(tp, conn); err != nil {
+				fmt.Printf("Error handling connection from %s: %s\n", conn.RemoteAddr(), err)
+			}
+		}()
+	}
+}
+
+func handleConn(tp *libp2ptls.Transport, conn net.Conn) error {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	sconn, err := tp.SecureInbound(ctx, conn)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Authenticated client: %s\n", sconn.RemotePeer().Pretty())
+	fmt.Fprintf(sconn, "Hello client!")
+	fmt.Printf("Closing connection to %s\n", conn.RemoteAddr())
+	return sconn.Close()
+}