Add fallback dialer

Previously we were unable to dial on a given transport if there were no
listener addresses defined for that. This meant that most people couldnt
use utp (as they had no utp listener transport to dial from).

dial_test.go

@@ -18,6 +18,61 @@ import (
 	ma "gx/ipfs/QmcobAGsCjYt5DXoq9et9L8yR8er7o7Cu3DTvpaq12jYSz/go-multiaddr"
 )
 
+func closeSwarms(swarms []*Swarm) {
+	for _, s := range swarms {
+		s.Close()
+	}
+}
+
+func TestBasicDial(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+
+	swarms := makeSwarms(ctx, t, 2)
+	defer closeSwarms(swarms)
+	s1 := swarms[0]
+	s2 := swarms[1]
+
+	s1.peers.AddAddrs(s2.local, s2.ListenAddresses(), peer.PermanentAddrTTL)
+
+	c, err := s1.Dial(ctx, s2.local)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s, err := c.NewStream()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s.Close()
+}
+
+func TestDialWithNoListeners(t *testing.T) {
+	t.Parallel()
+	ctx := context.Background()
+
+	s1 := makeDialOnlySwarm(ctx, t)
+
+	swarms := makeSwarms(ctx, t, 1)
+	defer closeSwarms(swarms)
+	s2 := swarms[0]
+
+	s1.peers.AddAddrs(s2.local, s2.ListenAddresses(), peer.PermanentAddrTTL)
+
+	c, err := s1.Dial(ctx, s2.local)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s, err := c.NewStream()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	s.Close()
+}
+
 func acceptAndHang(l net.Listener) {
 	conns := make([]net.Conn, 0, 10)
 	for {

swarm_test.go

@@ -24,31 +24,48 @@ func EchoStreamHandler(stream inet.Stream) {
 
 		// pull out the ipfs conn
 		c := stream.Conn()
-		log.Infof("%s ponging to %s", c.LocalPeer(), c.RemotePeer())
+		log.Errorf("%s ponging to %s", c.LocalPeer(), c.RemotePeer())
 
 		buf := make([]byte, 4)
 
 		for {
 			if _, err := stream.Read(buf); err != nil {
 				if err != io.EOF {
-					log.Info("ping receive error:", err)
+					log.Error("ping receive error:", err)
 				}
 				return
 			}
 
 			if !bytes.Equal(buf, []byte("ping")) {
-				log.Infof("ping receive error: ping != %s %v", buf, buf)
+				log.Errorf("ping receive error: ping != %s %v", buf, buf)
 				return
 			}
 
 			if _, err := stream.Write([]byte("pong")); err != nil {
-				log.Info("pond send error:", err)
+				log.Error("pond send error:", err)
 				return
 			}
 		}
 	}()
 }
 
+func makeDialOnlySwarm(ctx context.Context, t *testing.T) *Swarm {
+	id := testutil.RandIdentityOrFatal(t)
+
+	peerstore := peer.NewPeerstore()
+	peerstore.AddPubKey(id.ID(), id.PublicKey())
+	peerstore.AddPrivKey(id.ID(), id.PrivateKey())
+
+	swarm, err := NewSwarm(ctx, nil, id.ID(), peerstore, metrics.NewBandwidthCounter())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	swarm.SetStreamHandler(EchoStreamHandler)
+
+	return swarm
+}
+
 func makeSwarms(ctx context.Context, t *testing.T, num int) []*Swarm {
 	swarms := make([]*Swarm, 0, num)