Support for Hole punching (#233)

* support for forced direct connections.

dial_sync.go

@@ -96,13 +96,13 @@ func (ad *activeDial) start(ctx context.Context) {
 	ad.cancel()
 }
 
-func (ds *DialSync) getActiveDial(p peer.ID) *activeDial {
+func (ds *DialSync) getActiveDial(ctx context.Context, p peer.ID) *activeDial {
 	ds.dialsLk.Lock()
 	defer ds.dialsLk.Unlock()
 
 	actd, ok := ds.dials[p]
 	if !ok {
-		adctx, cancel := context.WithCancel(context.Background())
+		adctx, cancel := context.WithCancel(ctx)
 		actd = &activeDial{
 			id:     p,
 			cancel: cancel,
@@ -123,7 +123,7 @@ func (ds *DialSync) getActiveDial(p peer.ID) *activeDial {
 // DialLock initiates a dial to the given peer if there are none in progress
 // then waits for the dial to that peer to complete.
 func (ds *DialSync) DialLock(ctx context.Context, p peer.ID) (*Conn, error) {
-	return ds.getActiveDial(p).wait(ctx)
+	return ds.getActiveDial(ctx, p).wait(ctx)
 }
 
 // CancelDial cancels all in-progress dials to the given peer.

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/jbenet/goprocess v0.1.4
 	github.com/libp2p/go-addr-util v0.0.2
 	github.com/libp2p/go-conn-security-multistream v0.2.1
-	github.com/libp2p/go-libp2p-core v0.8.2
+	github.com/libp2p/go-libp2p-core v0.8.3
 	github.com/libp2p/go-libp2p-loggables v0.1.0
 	github.com/libp2p/go-libp2p-peerstore v0.2.6
 	github.com/libp2p/go-libp2p-quic-transport v0.10.0

go.sum

@@ -194,6 +194,8 @@ github.com/libp2p/go-libp2p-core v0.8.0/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJB
 github.com/libp2p/go-libp2p-core v0.8.1/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
 github.com/libp2p/go-libp2p-core v0.8.2 h1:/eaSZACWftJZYm07S0nRxdI84v1hSmgnCXrGOvJdpNQ=
 github.com/libp2p/go-libp2p-core v0.8.2/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
+github.com/libp2p/go-libp2p-core v0.8.3 h1:BZTReEF6o8g/n4DwxTyeFannOeae35Xy0TD+mES3CNE=
+github.com/libp2p/go-libp2p-core v0.8.3/go.mod h1:FfewUH/YpvWbEB+ZY9AQRQ4TAD8sJBt/G1rVvhz5XT8=
 github.com/libp2p/go-libp2p-loggables v0.1.0 h1:h3w8QFfCt2UJl/0/NW4K829HX/0S4KD31PQ7m8UXXO8=
 github.com/libp2p/go-libp2p-loggables v0.1.0/go.mod h1:EyumB2Y6PrYjr55Q3/tiJ/o3xoDasoRYM7nOzEpoa90=
 github.com/libp2p/go-libp2p-mplex v0.2.1/go.mod h1:SC99Rxs8Vuzrf/6WhmH41kNn13TiYdAWNYHrwImKLnE=

swarm.go

@@ -341,6 +341,7 @@ func (s *Swarm) NewStream(ctx context.Context, p peer.ID) (network.Stream, error
 	// a non-closed connection.
 	dials := 0
 	for {
+		// will prefer direct connections over relayed connections for opening streams
 		c := s.bestConnToPeer(p)
 		if c == nil {
 			if nodial, _ := network.GetNoDial(ctx); nodial {
@@ -392,9 +393,10 @@ func (s *Swarm) ConnsToPeer(p peer.ID) []network.Conn {
 
 // bestConnToPeer returns the best connection to peer.
 func (s *Swarm) bestConnToPeer(p peer.ID) *Conn {
-	// Selects the best connection we have to the peer.
-	// TODO: Prefer some transports over others. Currently, we just select
-	// the newest non-closed connection with the most streams.
+
+	// TODO: Prefer some transports over others.
+	// For now, prefers direct connections over Relayed connections.
+	// For tie-breaking, select the newest non-closed connection with the most streams.
 	s.conns.RLock()
 	defer s.conns.RUnlock()
 
@@ -409,15 +411,25 @@ func (s *Swarm) bestConnToPeer(p peer.ID) *Conn {
 		cLen := len(c.streams.m)
 		c.streams.Unlock()
 
-		if cLen >= bestLen {
+		// We will never prefer a Relayed connection over a direct connection.
+		if isDirectConn(best) && !isDirectConn(c) {
+			continue
+		}
+
+		// 1. Always prefer a direct connection over a relayed connection.
+		// 2. If both conns are direct or relayed, pick the one with as many or more streams.
+		if (!isDirectConn(best) && isDirectConn(c)) || (cLen >= bestLen) {
 			best = c
 			bestLen = cLen
 		}
-
 	}
 	return best
 }
 
+func isDirectConn(c *Conn) bool {
+	return c != nil && !c.conn.Transport().Proxy()
+}
+
 // Connectedness returns our "connectedness" state with the given peer.
 //
 // To check if we have an open connection, use `s.Connectedness(p) ==

swarm_dial.go

@@ -251,9 +251,14 @@ func (s *Swarm) dialPeer(ctx context.Context, p peer.ID) (*Conn, error) {
 
 	defer log.EventBegin(ctx, "swarmDialAttemptSync", p).Done()
 
-	// check if we already have an open connection first
 	conn := s.bestConnToPeer(p)
-	if conn != nil {
+	forceDirect, _ := network.GetForceDirectDial(ctx)
+	if forceDirect {
+		if isDirectConn(conn) {
+			return conn, nil
+		}
+	} else if conn != nil {
+		// check if we already have an open connection first
 		return conn, nil
 	}
 
@@ -287,8 +292,13 @@ func (s *Swarm) doDial(ctx context.Context, p peer.ID) (*Conn, error) {
 	// Short circuit.
 	// By the time we take the dial lock, we may already *have* a connection
 	// to the peer.
+	forceDirect, _ := network.GetForceDirectDial(ctx)
 	c := s.bestConnToPeer(p)
-	if c != nil {
+	if forceDirect {
+		if isDirectConn(c) {
+			return c, nil
+		}
+	} else if c != nil {
 		return c, nil
 	}
 
@@ -301,12 +311,17 @@ func (s *Swarm) doDial(ctx context.Context, p peer.ID) (*Conn, error) {
 	conn, err := s.dial(ctx, p)
 	if err != nil {
 		conn = s.bestConnToPeer(p)
-		if conn != nil {
+		if forceDirect {
+			if isDirectConn(conn) {
+				log.Debugf("ignoring dial error because we already have a direct connection: %s", err)
+				return conn, nil
+			}
+		} else if conn != nil {
 			// Hm? What error?
 			// Could have canceled the dial because we received a
 			// connection or some other random reason.
 			// Just ignore the error and return the connection.
-			log.Debugf("ignoring dial error because we have a connection: %s", err)
+			log.Debugf("ignoring dial error because we already have a connection: %s", err)
 			return conn, nil
 		}
 
@@ -321,6 +336,11 @@ func (s *Swarm) canDial(addr ma.Multiaddr) bool {
 	return t != nil && t.CanDial(addr)
 }
 
+func (s *Swarm) nonProxyAddr(addr ma.Multiaddr) bool {
+	t := s.TransportForDialing(addr)
+	return !t.Proxy()
+}
+
 // ranks addresses in descending order of preference for dialing
 // Private UDP > Public UDP > Private TCP > Public TCP > UDP Relay server > TCP Relay server
 func (s *Swarm) rankAddrs(addrs []ma.Multiaddr) []ma.Multiaddr {
@@ -362,6 +382,7 @@ func (s *Swarm) rankAddrs(addrs []ma.Multiaddr) []ma.Multiaddr {
 
 // dial is the actual swarm's dial logic, gated by Dial.
 func (s *Swarm) dial(ctx context.Context, p peer.ID) (*Conn, error) {
+	forceDirect, _ := network.GetForceDirectDial(ctx)
 	var logdial = lgbl.Dial("swarm", s.LocalPeer(), p, nil, nil)
 	if p == s.local {
 		log.Event(ctx, "swarmDialDoDialSelf", logdial)
@@ -383,20 +404,25 @@ func (s *Swarm) dial(ctx context.Context, p peer.ID) (*Conn, error) {
 		return nil, &DialError{Peer: p, Cause: ErrNoAddresses}
 	}
 	goodAddrs := s.filterKnownUndialables(p, peerAddrs)
+	if forceDirect {
+		goodAddrs = addrutil.FilterAddrs(goodAddrs, s.nonProxyAddr)
+	}
 	if len(goodAddrs) == 0 {
 		return nil, &DialError{Peer: p, Cause: ErrNoGoodAddresses}
 	}
 
-	/////// Check backoff andnRank addresses
-	var nonBackoff bool
-	for _, a := range goodAddrs {
-		// skip addresses in back-off
-		if !s.backf.Backoff(p, a) {
-			nonBackoff = true
+	if !forceDirect {
+		/////// Check backoff andnRank addresses
+		var nonBackoff bool
+		for _, a := range goodAddrs {
+			// skip addresses in back-off
+			if !s.backf.Backoff(p, a) {
+				nonBackoff = true
+			}
+		}
+		if !nonBackoff {
+			return nil, ErrDialBackoff
 		}
-	}
-	if !nonBackoff {
-		return nil, ErrDialBackoff
 	}
 
 	connC, dialErr := s.dialAddrs(ctx, p, s.rankAddrs(goodAddrs))