py-libp2p/tests_interop/go_pkgs/examples/echo/main.go

package main

import (
	"bufio"
	"context"
	"flag"
	"fmt"
	"io/ioutil"
	"log"

	utils "interop/utils"

	"github.com/libp2p/go-libp2p-core/network"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-core/peerstore"

	golog "github.com/ipfs/go-log"
	ma "github.com/multiformats/go-multiaddr"
	gologging "github.com/whyrusleeping/go-logging"
)

func main() {
	// LibP2P code uses golog to log messages. They log with different
	// string IDs (i.e. "swarm"). We can control the verbosity level for
	// all loggers with:
	golog.SetAllLoggers(gologging.DEBUG) // Change to DEBUG for extra info

	// Parse options from the command line
	listenF := flag.Int("l", 0, "wait for incoming connections")
	target := flag.String("d", "", "target peer to dial")
	insecure := flag.Bool("insecure", false, "use an unencrypted connection")
	seed := flag.Int64("seed", 0, "set random seed for id generation")
	flag.Parse()

	if *listenF == 0 {
		log.Fatal("Please provide a port to bind on with -l")
	}

	// Make a host that listens on the given multiaddress
	ha, err := utils.MakeBasicHost(*listenF, *insecure, *seed)
	if err != nil {
		log.Fatal(err)
	}

	// Set a stream handler on host A. /echo/1.0.0 is
	// a user-defined protocol name.
	ha.SetStreamHandler("/echo/1.0.0", func(s network.Stream) {
		log.Println("Got a new stream!")
		if err := doEcho(s); err != nil {
			log.Println(err)
			s.Reset()
		} else {
			s.Close()
		}
	})

	if *target == "" {
		log.Println("listening for connections")
		select {} // hang forever
	}
	/**** This is where the listener code ends ****/

	// The following code extracts target's the peer ID from the
	// given multiaddress
	ipfsaddr, err := ma.NewMultiaddr(*target)
	if err != nil {
		log.Fatalln(err)
	}

	pid, err := ipfsaddr.ValueForProtocol(ma.P_IPFS)
	if err != nil {
		log.Fatalln(err)
	}

	peerid, err := peer.IDB58Decode(pid)
	if err != nil {
		log.Fatalln(err)
	}

	// Decapsulate the /ipfs/<peerID> part from the target
	// /ip4/<a.b.c.d>/ipfs/<peer> becomes /ip4/<a.b.c.d>
	targetPeerAddr, _ := ma.NewMultiaddr(
		fmt.Sprintf("/ipfs/%s", peer.IDB58Encode(peerid)))
	targetAddr := ipfsaddr.Decapsulate(targetPeerAddr)
	log.Println("!@# targetAddr=", targetAddr)

	// We have a peer ID and a targetAddr so we add it to the peerstore
	// so LibP2P knows how to contact it
	ha.Peerstore().AddAddr(peerid, targetAddr, peerstore.PermanentAddrTTL)

	log.Println("!@# ipfsaddr=", ipfsaddr)
	pinfo, err := peer.AddrInfoFromP2pAddr(ipfsaddr)
	if err != nil {
		log.Fatalf("failed to parse %v to pinfo\n", ipfsaddr)
	}

	err = ha.Connect(context.Background(), *pinfo)
	if err != nil {
		panic(err)
	}

	log.Println("connect with peer", *pinfo)

	// make a new stream from host B to host A
	// it should be handled on host A by the handler we set above because
	// we use the same /echo/1.0.0 protocol
	s, err := ha.NewStream(context.Background(), peerid, "/echo/1.0.0")
	if err != nil {
		log.Fatalln(err)
	}

	log.Println("opened stream")

	_, err = s.Write([]byte("Hello, world!\n"))
	if err != nil {
		log.Fatalln(err)
	}

	out, err := ioutil.ReadAll(s)
	if err != nil {
		log.Fatalln(err)
	}

	log.Printf("read reply: %q\n", out)
}

// doEcho reads a line of data a stream and writes it back
func doEcho(s network.Stream) error {
	buf := bufio.NewReader(s)
	str, err := buf.ReadString('\n')
	if err != nil {
		return err
	}

	log.Printf("read: %s\n", str)
	_, err = s.Write([]byte(str))
	return err
}