network/config: redesign ping timeout handling a bit

1) Make timeout a timeout, don't do magic ping counts.
2) Drop additional timer from the main peer's protocol loop, create it
   dynamically and make it disconnect the peer.
3) Don't expose the ping counter to the outside, handle more logic inside the
   Peer.

Relates to #430.

config/protocol.mainnet.yml

@@ -50,8 +50,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 100
   AttemptConnPeers: 20
   MinPeers: 5

config/protocol.privnet.docker.four.yml

@@ -41,8 +41,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 3

config/protocol.privnet.docker.one.yml

@@ -41,8 +41,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 3

config/protocol.privnet.docker.single.yml

@@ -35,8 +35,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 0

config/protocol.privnet.docker.three.yml

@@ -41,8 +41,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 3

config/protocol.privnet.docker.two.yml

@@ -41,8 +41,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 3

config/protocol.privnet.yml

@@ -41,8 +41,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 10
   AttemptConnPeers: 5
   MinPeers: 3

config/protocol.testnet.yml

@@ -50,8 +50,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 100
   AttemptConnPeers: 20
   MinPeers: 5

config/protocol.unit_testnet.yml

@@ -40,8 +40,8 @@ ApplicationConfiguration:
   Relay: true
   DialTimeout: 3
   ProtoTickInterval: 2
-  PingInterval: 60
-  PingTimeout: 60
+  PingInterval: 30
+  PingTimeout: 90
   MaxPeers: 50
   AttemptConnPeers: 5
   MinPeers: 1

pkg/network/helper_test.go

@@ -160,7 +160,7 @@ type localPeer struct {
 	handshaked     bool
 	t              *testing.T
 	messageHandler func(t *testing.T, msg *Message)
-	pingSent int
+	pingSent       int
 }
 
 func newLocalPeer(t *testing.T) *localPeer {
@@ -206,9 +206,6 @@ func (p *localPeer) Version() *payload.Version {
 func (p *localPeer) LastBlockIndex() uint32 {
 	return p.lastBlockIndex
 }
-func (p *localPeer) UpdateLastBlockIndex(newIndex uint32) {
-	p.lastBlockIndex = newIndex
-}
 func (p *localPeer) HandleVersion(v *payload.Version) error {
 	p.version = v
 	return nil
@@ -225,11 +222,14 @@ func (p *localPeer) HandleVersionAck() error {
 	p.handshaked = true
 	return nil
 }
-func (p *localPeer) GetPingSent() int {
-	return p.pingSent
+func (p *localPeer) SendPing() error {
+	p.pingSent++
+	return nil
 }
-func (p *localPeer) UpdatePingSent(newValue int) {
-	p.pingSent = newValue
+func (p *localPeer) HandlePong(pong *payload.Ping) error {
+	p.lastBlockIndex = pong.LastBlockIndex
+	p.pingSent--
+	return nil
 }
 
 func (p *localPeer) Handshaked() bool {

pkg/network/peer.go

@@ -36,8 +36,12 @@ type Peer interface {
 	EnqueueHPPacket([]byte) error
 	Version() *payload.Version
 	LastBlockIndex() uint32
-	UpdateLastBlockIndex(lbIndex uint32)
 	Handshaked() bool
+
+	// SendPing enqueues a ping message to be sent to the peer and does
+	// appropriate protocol handling like timeouts and outstanding pings
+	// management.
+	SendPing() error
 	SendVersion(*Message) error
 	SendVersionAck(*Message) error
 	// StartProtocol is a goroutine to be run after the handshake. It
@@ -45,6 +49,7 @@ type Peer interface {
 	StartProtocol()
 	HandleVersion(*payload.Version) error
 	HandleVersionAck() error
-	GetPingSent() int
-	UpdatePingSent(int)
+
+	// HandlePong checks pong contents against Peer's state and updates it.
+	HandlePong(pong *payload.Ping) error
 }

pkg/network/server.go

@@ -29,7 +29,6 @@ const (
 	maxBlockBatch           = 200
 	maxAddrsToSend          = 200
 	minPoolCount            = 30
-	defaultPingLimit        = 4
 )
 
 var (
@@ -373,12 +372,10 @@ func (s *Server) handlePing(p Peer, ping *payload.Ping) error {
 
 // handlePing processes pong request.
 func (s *Server) handlePong(p Peer, pong *payload.Ping) error {
-	pingSent := p.GetPingSent()
-	if pingSent == 0 {
-		return errors.New("pong message wasn't expected")
+	err := p.HandlePong(pong)
+	if err != nil {
+		return err
 	}
-	p.UpdatePingSent(pingSent - 1)
-	p.UpdateLastBlockIndex(pong.LastBlockIndex)
 	if s.chain.HeaderHeight() < pong.LastBlockIndex {
 		return s.requestHeaders(p)
 	}

pkg/network/tcp_peer.go

@@ -25,7 +25,9 @@ const (
 )
 
 var (
-	errStateMismatch = errors.New("tried to send protocol message before handshake completed")
+	errStateMismatch  = errors.New("tried to send protocol message before handshake completed")
+	errPingPong       = errors.New("ping/pong timeout")
+	errUnexpectedPong = errors.New("pong message wasn't expected")
 )
 
 // TCPPeer represents a connected remote node in the
@@ -51,7 +53,8 @@ type TCPPeer struct {
 	wg sync.WaitGroup
 
 	// number of sent pings.
-	pingSent int
+	pingSent  int
+	pingTimer *time.Timer
 }
 
 // NewTCPPeer returns a TCPPeer structure based on the given connection.
@@ -191,7 +194,6 @@ func (p *TCPPeer) StartProtocol() {
 	}
 
 	timer := time.NewTimer(p.server.ProtoTickInterval)
-	pingTimer := time.NewTimer(p.server.PingTimeout)
 	for {
 		select {
 		case <-p.done:
@@ -210,20 +212,12 @@ func (p *TCPPeer) StartProtocol() {
 			} else {
 				diff := time.Now().UTC().Unix() - p.server.getLastBlockTime()
 				if diff > int64(p.server.PingInterval/time.Second) {
-					p.UpdatePingSent(p.GetPingSent() + 1)
-					err = p.EnqueueMessage(NewMessage(p.server.Net, CMDPing, payload.NewPing(p.server.id, p.server.chain.HeaderHeight())))
+					err = p.SendPing()
 				}
 			}
 			if err == nil {
 				timer.Reset(p.server.ProtoTickInterval)
 			}
-		case <-pingTimer.C:
-			if p.GetPingSent() > defaultPingLimit {
-				err = errors.New("ping/pong timeout")
-			} else {
-				pingTimer.Reset(p.server.PingTimeout)
-				p.UpdatePingSent(0)
-			}
 		}
 		if err != nil {
 			timer.Stop()
@@ -350,23 +344,33 @@ func (p *TCPPeer) LastBlockIndex() uint32 {
 	return p.lastBlockIndex
 }
 
-// UpdateLastBlockIndex updates last block index.
-func (p *TCPPeer) UpdateLastBlockIndex(newIndex uint32) {
+// SendPing sends a ping message to the peer and does appropriate accounting of
+// outstanding pings and timeouts.
+func (p *TCPPeer) SendPing() error {
 	p.lock.Lock()
-	defer p.lock.Unlock()
-	p.lastBlockIndex = newIndex
+	p.pingSent++
+	if p.pingTimer == nil {
+		p.pingTimer = time.AfterFunc(p.server.PingTimeout, func() {
+			p.Disconnect(errPingPong)
+		})
+	}
+	p.lock.Unlock()
+	return p.EnqueueMessage(NewMessage(p.server.Net, CMDPing, payload.NewPing(p.server.id, p.server.chain.HeaderHeight())))
 }
 
-// GetPingSent returns flag whether ping was sent or not.
-func (p *TCPPeer) GetPingSent() int {
-	p.lock.RLock()
-	defer p.lock.RUnlock()
-	return p.pingSent
-}
-
-// UpdatePingSent updates pingSent value.
-func (p *TCPPeer) UpdatePingSent(newValue int) {
+// HandlePong handles a pong message received from the peer and does appropriate
+// accounting of outstanding pings and timeouts.
+func (p *TCPPeer) HandlePong(pong *payload.Ping) error {
 	p.lock.Lock()
 	defer p.lock.Unlock()
-	p.pingSent = newValue
+	if p.pingTimer != nil && !p.pingTimer.Stop() {
+		return errPingPong
+	}
+	p.pingTimer = nil
+	p.pingSent--
+	if p.pingSent < 0 {
+		return errUnexpectedPong
+	}
+	p.lastBlockIndex = pong.LastBlockIndex
+	return nil
 }