From 059e632d0afcdc03457a430716f74f12ee41407e Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Mon, 20 Apr 2020 17:16:28 +0700
Subject: [PATCH 1/2] add command line client and server

---
 cmd/client/main.go | 69 ++++++++++++++++++++++++++++++++++++++++
 cmd/server/main.go | 79 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 148 insertions(+)
 create mode 100644 cmd/client/main.go
 create mode 100644 cmd/server/main.go

diff --git a/cmd/client/main.go b/cmd/client/main.go
new file mode 100644
index 0000000..8d391c9
--- /dev/null
+++ b/cmd/client/main.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+	"context"
+	"crypto/rand"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+
+	ic "github.com/libp2p/go-libp2p-core/crypto"
+	peer "github.com/libp2p/go-libp2p-core/peer"
+	libp2pquic "github.com/libp2p/go-libp2p-quic-transport"
+	ma "github.com/multiformats/go-multiaddr"
+)
+
+func main() {
+	if len(os.Args) != 3 {
+		fmt.Printf("Usage: ./main <multiaddr> <peer id>")
+		return
+	}
+	if err := run(os.Args[1], os.Args[2]); err != nil {
+		log.Fatalf(err.Error())
+	}
+}
+
+func run(raddr string, p string) error {
+	peerID, err := peer.Decode(p)
+	if err != nil {
+		return err
+	}
+	addr, err := ma.NewMultiaddr(raddr)
+	if err != nil {
+		return err
+	}
+	priv, _, err := ic.GenerateECDSAKeyPair(rand.Reader)
+	if err != nil {
+		return err
+	}
+
+	t, err := libp2pquic.NewTransport(priv, nil, nil)
+	if err != nil {
+		return err
+	}
+
+	log.Printf("Dialing %s\n", addr.String())
+	conn, err := t.Dial(context.Background(), addr, peerID)
+	if err != nil {
+		return err
+	}
+	str, err := conn.OpenStream()
+	if err != nil {
+		return err
+	}
+	const msg = "Hello world!"
+	log.Printf("Sending: %s\n", msg)
+	if _, err := str.Write([]byte(msg)); err != nil {
+		return err
+	}
+	if err := str.Close(); err != nil {
+		return err
+	}
+	data, err := ioutil.ReadAll(str)
+	if err != nil {
+		return err
+	}
+	log.Printf("Received: %s\n", data)
+	return conn.Close()
+}
diff --git a/cmd/server/main.go b/cmd/server/main.go
new file mode 100644
index 0000000..68eda3d
--- /dev/null
+++ b/cmd/server/main.go
@@ -0,0 +1,79 @@
+package main
+
+import (
+	"crypto/rand"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+
+	ic "github.com/libp2p/go-libp2p-core/crypto"
+	"github.com/libp2p/go-libp2p-core/peer"
+	tpt "github.com/libp2p/go-libp2p-core/transport"
+	libp2pquic "github.com/libp2p/go-libp2p-quic-transport"
+	ma "github.com/multiformats/go-multiaddr"
+)
+
+func main() {
+	if len(os.Args) != 2 {
+		fmt.Printf("Usage: ./main <port>")
+		return
+	}
+	if err := run(os.Args[1]); err != nil {
+		log.Fatalf(err.Error())
+	}
+}
+
+func run(port string) error {
+	addr, err := ma.NewMultiaddr(fmt.Sprintf("/ip4/0.0.0.0/udp/%s/quic", port))
+	if err != nil {
+		return err
+	}
+	priv, _, err := ic.GenerateECDSAKeyPair(rand.Reader)
+	if err != nil {
+		return err
+	}
+	peerID, err := peer.IDFromPrivateKey(priv)
+	if err != nil {
+		return err
+	}
+
+	t, err := libp2pquic.NewTransport(priv, nil, nil)
+	if err != nil {
+		return err
+	}
+
+	ln, err := t.Listen(addr)
+	if err != nil {
+		return err
+	}
+	fmt.Printf("Listening. Now run: go run cmd/client/main.go %s %s\n", ln.Multiaddr(), peerID)
+	for {
+		conn, err := ln.Accept()
+		if err != nil {
+			return err
+		}
+		log.Printf("Accepted new connection from %s (%s)\n", conn.RemotePeer(), conn.RemoteMultiaddr())
+		go func() {
+			if err := handleConn(conn); err != nil {
+				log.Printf("handling conn failed: %s", err.Error())
+			}
+		}()
+	}
+}
+
+func handleConn(conn tpt.CapableConn) error {
+	str, err := conn.AcceptStream()
+	if err != nil {
+		return err
+	}
+	data, err := ioutil.ReadAll(str)
+	if err != nil {
+		return err
+	}
+	log.Printf("Received: %s\n", data)
+	if _, err := str.Write([]byte(data)); err != nil {
+		return err
+	}
+	return str.Close()
+}

From 487efa43c8d595993f1b697e5bd1223e98d56015 Mon Sep 17 00:00:00 2001
From: Marten Seemann <martenseemann@gmail.com>
Date: Tue, 21 Apr 2020 10:20:35 +0700
Subject: [PATCH 2/2] apply @Stebalien's suggestions from code review

Co-Authored-By: Steven Allen <steven@stebalien.com>
---
 cmd/client/main.go | 2 +-
 cmd/server/main.go | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/cmd/client/main.go b/cmd/client/main.go
index 8d391c9..37ede0c 100644
--- a/cmd/client/main.go
+++ b/cmd/client/main.go
@@ -16,7 +16,7 @@ import (
 
 func main() {
 	if len(os.Args) != 3 {
-		fmt.Printf("Usage: ./main <multiaddr> <peer id>")
+		fmt.Printf("Usage: %s <multiaddr> <peer id>", os.Args[0])
 		return
 	}
 	if err := run(os.Args[1], os.Args[2]); err != nil {
diff --git a/cmd/server/main.go b/cmd/server/main.go
index 68eda3d..3a5fe24 100644
--- a/cmd/server/main.go
+++ b/cmd/server/main.go
@@ -16,7 +16,7 @@ import (
 
 func main() {
 	if len(os.Args) != 2 {
-		fmt.Printf("Usage: ./main <port>")
+		fmt.Printf("Usage: %s <port>", os.Args[0])
 		return
 	}
 	if err := run(os.Args[1]); err != nil {