Add echo back in for test

src/main.go

@@ -1,12 +1,14 @@
 package main
 
 import (
+	"bufio"
 	"context"
 	"fmt"
 	"log"
 
 	"github.com/libp2p/go-libp2p"
 	"github.com/libp2p/go-libp2p-core/host"
+	"github.com/libp2p/go-libp2p-core/network"
 	relayv1 "github.com/libp2p/go-libp2p/p2p/protocol/circuitv1/relay"
 	libp2pquic "github.com/libp2p/go-libp2p/p2p/transport/quic"
 	"github.com/libp2p/go-libp2p/p2p/transport/tcp"
@@ -54,6 +56,28 @@ func run() {
 		return
 	}
 
+	h1.SetStreamHandler("/echo/1.0.0", func(s network.Stream) {
+		log.Println("listener received new stream")
+
+		// Read whatever comes in and print it out
+		// from https://github.com/libp2p/go-libp2p/blob/621eafcecde611b27bbb42dda4b8bbc97b66e907/examples/echo/main.go#L197
+		if err := func(s network.Stream) error {
+			buf := bufio.NewReader(s)
+			str, err := buf.ReadString('\n')
+			if err != nil {
+				log.Printf("error reading stream: %v\n", err)
+				return err
+			}
+			log.Printf("read: %s", str)
+			_, err = s.Write([]byte(str))
+			return err
+		}(s); err != nil {
+			log.Println(err)
+			s.Reset()
+		} else {
+			s.Close()
+		}
+	})
 	fullAddr := func(ha host.Host) string {
 		// Build host multiaddress
 		hostAddr, _ := ma.NewMultiaddr(fmt.Sprintf("/p2p/%s", ha.ID().Pretty()))