1 files changed, 119 insertions, 31 deletions

diff --git a/p2p/server.go b/p2p/server.go
index 922df55ba..90e92dc05 100644
--- a/p2p/server.go
+++ b/p2p/server.go
@@ -40,11 +40,10 @@ const (
 	refreshPeersInterval    = 30 * time.Second
 	staticPeerCheckInterval = 15 * time.Second
 
-	// Maximum number of concurrently handshaking inbound connections.
-	maxAcceptConns = 50
-
-	// Maximum number of concurrently dialing outbound connections.
-	maxActiveDialTasks = 16
+	// Connectivity defaults.
+	maxActiveDialTasks     = 16
+	defaultMaxPendingPeers = 50
+	defaultDialRatio       = 3
 
 	// Maximum time allowed for reading a complete message.
 	// This is effectively the amount of time a connection can be idle.
@@ -70,6 +69,11 @@ type Config struct {
 	// Zero defaults to preset values.
 	MaxPendingPeers int `toml:",omitempty"`
 
+	// DialRatio controls the ratio of inbound to dialed connections.
+	// Example: a DialRatio of 2 allows 1/2 of connections to be dialed.
+	// Setting DialRatio to zero defaults it to 3.
+	DialRatio int `toml:",omitempty"`
+
 	// NoDiscovery can be used to disable the peer discovery mechanism.
 	// Disabling is useful for protocol debugging (manual topology).
 	NoDiscovery bool
@@ -78,9 +82,6 @@ type Config struct {
 	// protocol should be started or not.
 	DiscoveryV5 bool `toml:",omitempty"`
 
-	// Listener address for the V5 discovery protocol UDP traffic.
-	DiscoveryV5Addr string `toml:",omitempty"`
-
 	// Name sets the node name of this server.
 	// Use common.MakeName to create a name that follows existing conventions.
 	Name string `toml:"-"`
@@ -141,7 +142,7 @@ type Config struct {
 	EnableMsgEvents bool
 
 	// Logger is a custom logger to use with the p2p.Server.
-	Logger log.Logger
+	Logger log.Logger `toml:",omitempty"`
 }
 
 // Server manages all peer connections.
@@ -354,6 +355,32 @@ func (srv *Server) Stop() {
 	srv.loopWG.Wait()
 }
 
+// sharedUDPConn implements a shared connection. Write sends messages to the underlying connection while read returns
+// messages that were found unprocessable and sent to the unhandled channel by the primary listener.
+type sharedUDPConn struct {
+	*net.UDPConn
+	unhandled chan discover.ReadPacket
+}
+
+// ReadFromUDP implements discv5.conn
+func (s *sharedUDPConn) ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error) {
+	packet, ok := <-s.unhandled
+	if !ok {
+		return 0, nil, fmt.Errorf("Connection was closed")
+	}
+	l := len(packet.Data)
+	if l > len(b) {
+		l = len(b)
+	}
+	copy(b[:l], packet.Data[:l])
+	return l, packet.Addr, nil
+}
+
+// Close implements discv5.conn
+func (s *sharedUDPConn) Close() error {
+	return nil
+}
+
 // Start starts running the server.
 // Servers can not be re-used after stopping.
 func (srv *Server) Start() (err error) {
@@ -388,20 +415,66 @@ func (srv *Server) Start() (err error) {
 	srv.peerOp = make(chan peerOpFunc)
 	srv.peerOpDone = make(chan struct{})
 
-	// node table
-	if !srv.NoDiscovery {
-		ntab, err := discover.ListenUDP(srv.PrivateKey, srv.ListenAddr, srv.NAT, srv.NodeDatabase, srv.NetRestrict)
+	var (
+		conn      *net.UDPConn
+		sconn     *sharedUDPConn
+		realaddr  *net.UDPAddr
+		unhandled chan discover.ReadPacket
+	)
+
+	if !srv.NoDiscovery || srv.DiscoveryV5 {
+		addr, err := net.ResolveUDPAddr("udp", srv.ListenAddr)
 		if err != nil {
 			return err
 		}
-		if err := ntab.SetFallbackNodes(srv.BootstrapNodes); err != nil {
+		conn, err = net.ListenUDP("udp", addr)
+		if err != nil {
+			return err
+		}
+		realaddr = conn.LocalAddr().(*net.UDPAddr)
+		if srv.NAT != nil {
+			if !realaddr.IP.IsLoopback() {
+				go nat.Map(srv.NAT, srv.quit, "udp", realaddr.Port, realaddr.Port, "ethereum discovery")
+			}
+			// TODO: react to external IP changes over time.
+			if ext, err := srv.NAT.ExternalIP(); err == nil {
+				realaddr = &net.UDPAddr{IP: ext, Port: realaddr.Port}
+			}
+		}
+	}
+
+	if !srv.NoDiscovery && srv.DiscoveryV5 {
+		unhandled = make(chan discover.ReadPacket, 100)
+		sconn = &sharedUDPConn{conn, unhandled}
+	}
+
+	// node table
+	if !srv.NoDiscovery {
+		cfg := discover.Config{
+			PrivateKey:   srv.PrivateKey,
+			AnnounceAddr: realaddr,
+			NodeDBPath:   srv.NodeDatabase,
+			NetRestrict:  srv.NetRestrict,
+			Bootnodes:    srv.BootstrapNodes,
+			Unhandled:    unhandled,
+		}
+		ntab, err := discover.ListenUDP(conn, cfg)
+		if err != nil {
 			return err
 		}
 		srv.ntab = ntab
 	}
 
 	if srv.DiscoveryV5 {
-		ntab, err := discv5.ListenUDP(srv.PrivateKey, srv.DiscoveryV5Addr, srv.NAT, "", srv.NetRestrict) //srv.NodeDatabase)
+		var (
+			ntab *discv5.Network
+			err  error
+		)
+		if sconn != nil {
+			ntab, err = discv5.ListenUDP(srv.PrivateKey, sconn, realaddr, "", srv.NetRestrict) //srv.NodeDatabase)
+		} else {
+			ntab, err = discv5.ListenUDP(srv.PrivateKey, conn, realaddr, "", srv.NetRestrict) //srv.NodeDatabase)
+		}
 		if err != nil {
 			return err
 		}
@@ -411,10 +484,7 @@ func (srv *Server) Start() (err error) {
 		srv.DiscV5 = ntab
 	}
 
-	dynPeers := (srv.MaxPeers + 1) / 2
-	if srv.NoDiscovery {
-		dynPeers = 0
-	}
+	dynPeers := srv.maxDialedConns()
 	dialer := newDialState(srv.StaticNodes, srv.BootstrapNodes, srv.ntab, dynPeers, srv.NetRestrict)
 
 	// handshake
@@ -471,6 +541,7 @@ func (srv *Server) run(dialstate dialer) {
 	defer srv.loopWG.Done()
 	var (
 		peers        = make(map[discover.NodeID]*Peer)
+		inboundCount = 0
 		trusted      = make(map[discover.NodeID]bool, len(srv.TrustedNodes))
 		taskdone     = make(chan task, maxActiveDialTasks)
 		runningTasks []task
@@ -556,14 +627,14 @@ running:
 			}
 			// TODO: track in-progress inbound node IDs (pre-Peer) to avoid dialing them.
 			select {
-			case c.cont <- srv.encHandshakeChecks(peers, c):
+			case c.cont <- srv.encHandshakeChecks(peers, inboundCount, c):
 			case <-srv.quit:
 				break running
 			}
 		case c := <-srv.addpeer:
 			// At this point the connection is past the protocol handshake.
 			// Its capabilities are known and the remote identity is verified.
-			err := srv.protoHandshakeChecks(peers, c)
+			err := srv.protoHandshakeChecks(peers, inboundCount, c)
 			if err == nil {
 				// The handshakes are done and it passed all checks.
 				p := newPeer(c, srv.Protocols)
@@ -574,8 +645,11 @@ running:
 				}
 				name := truncateName(c.name)
 				srv.log.Debug("Adding p2p peer", "name", name, "addr", c.fd.RemoteAddr(), "peers", len(peers)+1)
-				peers[c.id] = p
 				go srv.runPeer(p)
+				peers[c.id] = p
+				if p.Inbound() {
+					inboundCount++
+				}
 			}
 			// The dialer logic relies on the assumption that
 			// dial tasks complete after the peer has been added or
@@ -590,6 +664,9 @@ running:
 			d := common.PrettyDuration(mclock.Now() - pd.created)
 			pd.log.Debug("Removing p2p peer", "duration", d, "peers", len(peers)-1, "req", pd.requested, "err", pd.err)
 			delete(peers, pd.ID())
+			if pd.Inbound() {
+				inboundCount--
+			}
 		}
 	}
 
@@ -616,20 +693,22 @@ running:
 	}
 }
 
-func (srv *Server) protoHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn) error {
+func (srv *Server) protoHandshakeChecks(peers map[discover.NodeID]*Peer, inboundCount int, c *conn) error {
 	// Drop connections with no matching protocols.
 	if len(srv.Protocols) > 0 && countMatchingProtocols(srv.Protocols, c.caps) == 0 {
 		return DiscUselessPeer
 	}
 	// Repeat the encryption handshake checks because the
 	// peer set might have changed between the handshakes.
-	return srv.encHandshakeChecks(peers, c)
+	return srv.encHandshakeChecks(peers, inboundCount, c)
 }
 
-func (srv *Server) encHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn) error {
+func (srv *Server) encHandshakeChecks(peers map[discover.NodeID]*Peer, inboundCount int, c *conn) error {
 	switch {
 	case !c.is(trustedConn|staticDialedConn) && len(peers) >= srv.MaxPeers:
 		return DiscTooManyPeers
+	case !c.is(trustedConn) && c.is(inboundConn) && inboundCount >= srv.maxInboundConns():
+		return DiscTooManyPeers
 	case peers[c.id] != nil:
 		return DiscAlreadyConnected
 	case c.id == srv.Self().ID:
@@ -639,6 +718,21 @@ func (srv *Server) encHandshakeChecks(peers map[discover.NodeID]*Peer, c *conn)
 	}
 }
 
+func (srv *Server) maxInboundConns() int {
+	return srv.MaxPeers - srv.maxDialedConns()
+}
+
+func (srv *Server) maxDialedConns() int {
+	if srv.NoDiscovery || srv.NoDial {
+		return 0
+	}
+	r := srv.DialRatio
+	if r == 0 {
+		r = defaultDialRatio
+	}
+	return srv.MaxPeers / r
+}
+
 type tempError interface {
 	Temporary() bool
 }
@@ -649,10 +743,7 @@ func (srv *Server) listenLoop() {
 	defer srv.loopWG.Done()
 	srv.log.Info("RLPx listener up", "self", srv.makeSelf(srv.listener, srv.ntab))
 
-	// This channel acts as a semaphore limiting
-	// active inbound connections that are lingering pre-handshake.
-	// If all slots are taken, no further connections are accepted.
-	tokens := maxAcceptConns
+	tokens := defaultMaxPendingPeers
 	if srv.MaxPendingPeers > 0 {
 		tokens = srv.MaxPendingPeers
 	}
@@ -693,9 +784,6 @@ func (srv *Server) listenLoop() {
 
 		fd = newMeteredConn(fd, true)
 		srv.log.Trace("Accepted connection", "addr", fd.RemoteAddr())
-
-		// Spawn the handler. It will give the slot back when the connection
-		// has been established.
 		go func() {
 			srv.SetupConn(fd, inboundConn, nil)
 			slots <- struct{}{}