libp2p minimal streams

streampubsub.go

package main

import (
	"bufio"
	"context"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"os/signal"
	"sync"
	"syscall"
	"time"

	"github.com/libp2p/go-libp2p"
	connmgr "github.com/libp2p/go-libp2p-connmgr"
	"github.com/libp2p/go-libp2p-core/crypto"
	"github.com/libp2p/go-libp2p-core/host"
	"github.com/libp2p/go-libp2p-core/network"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-core/protocol"
	"github.com/libp2p/go-libp2p-core/routing"
	discovery "github.com/libp2p/go-libp2p-discovery"
	dht "github.com/libp2p/go-libp2p-kad-dht"
	libp2pquic "github.com/libp2p/go-libp2p-quic-transport"
)

const RendezvousString = "2d2yzgRJGsOVggRw"

var ProtocolID = protocol.ID(fmt.Sprintf("/%s/1.0.0", RendezvousString))

func handleStream(ctx context.Context, wg *sync.WaitGroup, stream network.Stream) {
	ctx, cancel := context.WithCancel(ctx)
	rw := bufio.NewReadWriter(bufio.NewReader(stream), bufio.NewWriter(stream))
	wg.Add(3)
	go func() {
		defer wg.Done()
		defer stream.Close()
		<-ctx.Done()
	}()
	go func() {
		defer wg.Done()
		defer cancel()
		for {
			str, err := rw.ReadString('\n')
			if err != nil {
				if !errors.Is(err, io.EOF) {
					log.Println("Stream read error:", err)
				}
				return
			}
			if str == "" {
				return
			} else if str != "\n" {
				log.Println("Stream read:", str)
			}
		}
	}()
	go func() {
		defer wg.Done()
		defer cancel()
		for {
			_, err := rw.WriteString("hello world\n")
			if err != nil {
				log.Println("Stream write error:", err)
				return
			}
			err = rw.Flush()
			if err != nil {
				log.Println("Stream flush error:", err)
				return
			}
			select {
			case <-time.After(2 * time.Second):
			case <-ctx.Done():
				return
			}
		}
	}()
}

func main() {
	log.SetFlags(log.LstdFlags | log.Lshortfile)

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()

	// Generate key pair for identity
	priv, _, err := crypto.GenerateKeyPair(crypto.Ed25519, -1)
	if err != nil {
		log.Println(err)
		return
	}

	bootstrapPeerAddrs := dht.GetDefaultBootstrapPeerAddrInfos()
	var dhtIpfs *dht.IpfsDHT
	h, err := libp2p.New(ctx,
		libp2p.DefaultListenAddrs,
		libp2p.DefaultTransports,
		libp2p.DefaultMuxers,
		libp2p.DefaultSecurity,
		libp2p.DefaultPeerstore,
		libp2p.DefaultEnableRelay,
		libp2p.Identity(priv),
		libp2p.ListenAddrStrings(
			"/ip4/0.0.0.0/udp/0/quic",
			"/ip6/::/udp/0/quic",
		),
		libp2p.Transport(libp2pquic.NewTransport),
		libp2p.DefaultStaticRelays(),
		libp2p.EnableAutoRelay(),
		libp2p.EnableNATService(),
		libp2p.NATPortMap(),
		libp2p.ConnectionManager(connmgr.NewConnManager(20, 40, time.Minute)),
		libp2p.Routing(func(h host.Host) (routing.PeerRouting, error) {
			var err error
			dhtIpfs, err = dht.New(ctx, h,
				dht.Mode(dht.ModeServer),
				dht.BootstrapPeers(bootstrapPeerAddrs...))
			return dhtIpfs, err
		}))
	if err != nil {
		log.Println(err)
		return
	}
	defer h.Close()
	log.Println("Host ID:", h.ID())
	log.Println("ListenAddresses:", h.Network().ListenAddresses())
	var wg sync.WaitGroup
	h.SetStreamHandler(ProtocolID, func(s network.Stream) {
		handleStream(ctx, &wg, s)
	})
	err = dhtIpfs.Bootstrap(ctx)
	if err != nil {
		log.Println(err)
		return
	}
	for _, peerAddr := range bootstrapPeerAddrs {
		wg.Add(1)
		go func(peerAddr peer.AddrInfo) {
			defer wg.Done()
			err := h.Connect(ctx, peerAddr)
			if err != nil {
				log.Println("Bootstrap connect error:", err, peerAddr)
			} else {
				log.Println("Bootstrap connect:", peerAddr)
			}
		}(peerAddr)
	}
	wg.Wait()
	routingDiscovery := discovery.NewRoutingDiscovery(dhtIpfs)

	log.Println("Advertising and finding peers...")

	wg.Add(1)
	go func() {
		defer wg.Done()

		for ctx.Err() == nil {
			_, err := routingDiscovery.Advertise(ctx, RendezvousString)
			if err != nil {
				if !errors.Is(err, context.DeadlineExceeded) {
					log.Println(err)
					return
				} else {
					log.Println("Advertise failed retrying...")
				}
			} else {
				break
			}
		}
		// see limit option
		peerAddrsChan, err := routingDiscovery.FindPeers(ctx, RendezvousString)
		if err != nil {
			log.Println(err)
			return
		}
		for {
			select {
			case peerAddr := <-peerAddrsChan:
				// most of the peers are empty!
				if (len(peerAddr.Addrs) == 0 && peerAddr.ID == "") || peerAddr.ID == h.ID() {
					continue
				}
				stream, err := h.NewStream(ctx, peerAddr.ID, ProtocolID)
				if err != nil {
					log.Println("Stream error:", err, peerAddr)
				} else {
					log.Println("Stream opened:", peerAddr)
					handleStream(ctx, &wg, stream)
				}
			case <-ctx.Done():
				return
			}
		}
	}()
	wg.Wait()
}