discovery: swap mdns lib for grandcat/zeroconf

p2p/discovery/mdns.go

@@ -10,13 +10,13 @@ import (
 	"sync"
 	"time"
 
+	mdns "github.com/grandcat/zeroconf"
 	logging "github.com/ipfs/go-log"
 	"github.com/libp2p/go-libp2p-host"
 	"github.com/libp2p/go-libp2p-peer"
 	pstore "github.com/libp2p/go-libp2p-peerstore"
 	ma "github.com/multiformats/go-multiaddr"
 	manet "github.com/multiformats/go-multiaddr-net"
-	"github.com/whyrusleeping/mdns"
 )
 
 var log = logging.Logger("mdns")
@@ -35,7 +35,7 @@ type Notifee interface {
 
 type mdnsService struct {
 	server  *mdns.Server
-	service *mdns.MDNSService
+	service *mdns.Resolver
 	host    host.Host
 	tag     string
 
@@ -44,62 +44,76 @@ type mdnsService struct {
 	interval time.Duration
 }
 
-func getDialableListenAddrs(ph host.Host) ([]*net.TCPAddr, error) {
-	var out []*net.TCPAddr
-	for _, addr := range ph.Addrs() {
+// Tries to pick the best port.
+func getBestPort(addrs []ma.Multiaddr) (int, error) {
+	var best *net.TCPAddr
+	for _, addr := range addrs {
 		na, err := manet.ToNetAddr(addr)
 		if err != nil {
 			continue
 		}
 		tcp, ok := na.(*net.TCPAddr)
-		if ok {
-			out = append(out, tcp)
+		if !ok {
+			continue
+		}
+		// Don't bother with multicast and
+		if tcp.IP.IsMulticast() {
+			continue
+		}
+		// We don't yet support link-local
+		if tcp.IP.IsLinkLocalUnicast() {
+			continue
+		}
+		// Unspecified listeners are *always* the best choice.
+		if tcp.IP.IsUnspecified() {
+			return tcp.Port, nil
+		}
+		// If we don't have a best choice, use this addr.
+		if best == nil {
+			best = tcp
+			continue
+		}
+		// If the best choice is a loopback address, replace it.
+		if best.IP.IsLoopback() {
+			best = tcp
 		}
 	}
-	if len(out) == 0 {
-		return nil, errors.New("failed to find good external addr from peerhost")
+	if best == nil {
+		return 0, errors.New("failed to find good external addr from peerhost")
 	}
-	return out, nil
+	return best.Port, nil
 }
 
 func NewMdnsService(ctx context.Context, peerhost host.Host, interval time.Duration, serviceTag string) (Service, error) {
 
 	// TODO: dont let mdns use logging...
 	golog.SetOutput(ioutil.Discard)
 
-	var ipaddrs []net.IP
-	port := 4001
-
-	addrs, err := getDialableListenAddrs(peerhost)
+	port, err := getBestPort(peerhost.Network().ListenAddresses())
 	if err != nil {
-		log.Warning(err)
-	} else {
-		port = addrs[0].Port
-		for _, a := range addrs {
-			ipaddrs = append(ipaddrs, a.IP)
-		}
+		return nil, err
 	}
-
 	myid := peerhost.ID().Pretty()
 
 	info := []string{myid}
 	if serviceTag == "" {
 		serviceTag = ServiceTag
 	}
-	service, err := mdns.NewMDNSService(myid, serviceTag, "", "", port, ipaddrs, info)
+
+	resolver, err := mdns.NewResolver(nil)
 	if err != nil {
-		return nil, err
+		log.Error("Failed to initialize resolver:", err)
 	}
 
 	// Create the mDNS server, defer shutdown
-	server, err := mdns.NewServer(&mdns.Config{Zone: service})
+	server, err := mdns.Register(myid, serviceTag, "", port, info, nil)
 	if err != nil {
 		return nil, err
 	}
 
 	s := &mdnsService{
 		server:   server,
-		service:  service,
+		service:  resolver,
 		host:     peerhost,
 		interval: interval,
 		tag:      serviceTag,
@@ -111,34 +125,32 @@ func NewMdnsService(ctx context.Context, peerhost host.Host, interval time.Durat
 }
 
 func (m *mdnsService) Close() error {
-	return m.server.Shutdown()
+	m.server.Shutdown()
+	// grandcat/zerconf swallows error, satisfy interface
+	return nil
 }
 
 func (m *mdnsService) pollForEntries(ctx context.Context) {
-
 	ticker := time.NewTicker(m.interval)
 	for {
 		//execute mdns query right away at method call and then with every tick
 		entriesCh := make(chan *mdns.ServiceEntry, 16)
-		go func() {
-			for entry := range entriesCh {
+		go func(results <-chan *mdns.ServiceEntry) {
+			for entry := range results {
 				m.handleEntry(entry)
 			}
-		}()
+		}(entriesCh)
 
 		log.Debug("starting mdns query")
-		qp := &mdns.QueryParam{
-			Domain:  "local",
-			Entries: entriesCh,
-			Service: m.tag,
-			Timeout: time.Second * 5,
-		}
 
-		err := mdns.Query(qp)
-		if err != nil {
+		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+		defer cancel()
+
+		if err := m.service.Browse(ctx, m.tag, "local", entriesCh); err != nil {
 			log.Error("mdns lookup error: ", err)
 		}
 		close(entriesCh)
+
 		log.Debug("mdns query complete")
 
 		select {
@@ -152,8 +164,12 @@ func (m *mdnsService) pollForEntries(ctx context.Context) {
 }
 
 func (m *mdnsService) handleEntry(e *mdns.ServiceEntry) {
-	log.Debugf("Handling MDNS entry: %s:%d %s", e.AddrV4, e.Port, e.Info)
-	mpeer, err := peer.IDB58Decode(e.Info)
+	if len(e.Text) != 1 {
+		log.Warningf("Expected exactly one TXT record, got: %v", e.Text)
+		return
+	}
+	// pull out the txt
+	mpeer, err := peer.IDB58Decode(e.Text[0])
 	if err != nil {
 		log.Warning("Error parsing peer ID from mdns entry: ", err)
 		return
@@ -164,18 +180,23 @@ func (m *mdnsService) handleEntry(e *mdns.ServiceEntry) {
 		return
 	}
 
-	maddr, err := manet.FromNetAddr(&net.TCPAddr{
-		IP:   e.AddrV4,
-		Port: e.Port,
-	})
-	if err != nil {
-		log.Warning("Error parsing multiaddr from mdns entry: ", err)
-		return
-	}
+	addrs := make([]net.IP, len(e.AddrIPv4)+len(e.AddrIPv6))
+	copy(addrs, e.AddrIPv4)
+	copy(addrs[len(e.AddrIPv4):], e.AddrIPv6)
+
+	var pi pstore.PeerInfo
+	for _, ip := range addrs {
+		log.Debugf("Handling MDNS entry: %s:%d %s", ip, e.Port, e.Text[0])
 
-	pi := pstore.PeerInfo{
-		ID:    mpeer,
-		Addrs: []ma.Multiaddr{maddr},
+		maddr, err := manet.FromNetAddr(&net.TCPAddr{
+			IP:   ip,
+			Port: e.Port,
+		})
+		if err != nil {
+			log.Errorf("error creating multiaddr from mdns entry (%s:%d): %s", ip, e.Port, err)
+			return
+		}
+		pi.Addrs = append(pi.Addrs, maddr)
 	}
 
 	m.lk.Lock()

p2p/discovery/mdns_test.go

@@ -8,9 +8,9 @@ import (
 	bhost "github.com/libp2p/go-libp2p/p2p/host/basic"
 
 	host "github.com/libp2p/go-libp2p-host"
-	swarmt "github.com/libp2p/go-libp2p-swarm/testing"
-
 	pstore "github.com/libp2p/go-libp2p-peerstore"
+	swarmt "github.com/libp2p/go-libp2p-swarm/testing"
+	ma "github.com/multiformats/go-multiaddr"
 )
 
 type DiscoveryNotifee struct {
@@ -21,6 +21,51 @@ func (n *DiscoveryNotifee) HandlePeerFound(pi pstore.PeerInfo) {
 	n.h.Connect(context.Background(), pi)
 }
 
+func TestGetBestPort(t *testing.T) {
+	port, err := getBestPort([]ma.Multiaddr{ma.StringCast("/ip4/1.2.3.4/tcp/2222"), ma.StringCast("/ip4/0.0.0.0/tcp/1234")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if port != 1234 {
+		t.Errorf("expected port 1234, got port %d", port)
+	}
+
+	port, err = getBestPort([]ma.Multiaddr{ma.StringCast("/ip4/127.0.0.1/tcp/2222"), ma.StringCast("/ip4/0.0.0.0/tcp/1234")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if port != 1234 {
+		t.Errorf("expected port 1234, got port %d", port)
+	}
+
+	port, err = getBestPort([]ma.Multiaddr{ma.StringCast("/ip4/1.2.3.4/tcp/2222"), ma.StringCast("/ip4/127.0.0.1/tcp/1234")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if port != 2222 {
+		t.Errorf("expected port 2222, got port %d", port)
+	}
+	port, err = getBestPort([]ma.Multiaddr{ma.StringCast("/ip4/127.0.0.1/tcp/1234"), ma.StringCast("/ip4/1.2.3.4/tcp/2222")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if port != 2222 {
+		t.Errorf("expected port 2222, got port %d", port)
+	}
+	port, err = getBestPort([]ma.Multiaddr{ma.StringCast("/ip4/127.0.0.1/tcp/1234")})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if port != 1234 {
+		t.Errorf("expected port 1234, got port %d", port)
+	}
+
+	_, err = getBestPort([]ma.Multiaddr{})
+	if err == nil {
+		t.Fatal("expected error")
+	}
+}
+
 func TestMdnsDiscovery(t *testing.T) {
 	//TODO: re-enable when the new lib will get integrated
 	t.Skip("TestMdnsDiscovery fails randomly with current lib")

package.json

@@ -13,11 +13,6 @@
       "name": "go-semver",
       "version": "0.0.0"
     },
-    {
-      "hash": "QmNeRzgrSpwbMU7VKLRyfvbqf1nRrAiQ7fEXaBxWGT5Ygr",
-      "name": "mdns",
-      "version": "0.1.3"
-    },
     {
       "hash": "QmPdKqUcHGFdeSpvjVoaTRPPstGif9GBZb5Q56RVw9o69A",
       "name": "go-ipfs-util",
@@ -249,6 +244,12 @@
       "hash": "QmSSeQqc5QeuefkaM6JFV5tSF9knLUkXKVhW1eYRiqe72W",
       "name": "uuid",
       "version": "0.1.0"
+    },
+    {
+      "author": "grandcat",
+      "hash": "QmWrJTtJCQ6kCCTtLBM82Cx9h52QMQ5hcbrsePFuRSHuWC",
+      "name": "zeroconf",
+      "version": "0.2.1"
     }
   ],
   "gxVersion": "0.4.0",