package network import ( "errors" "fmt" "net" "strconv" "sync" "time" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/network/payload" "go.uber.org/zap" ) type handShakeStage uint8 const ( versionSent handShakeStage = 1 << iota versionReceived verAckSent verAckReceived requestQueueSize = 32 p2pMsgQueueSize = 16 hpRequestQueueSize = 4 ) var ( errGone = errors.New("the peer is gone already") 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 // network over TCP. type TCPPeer struct { // underlying TCP connection. conn net.Conn // The server this peer belongs to. server *Server // The version of the peer. version *payload.Version // Index of the last block. lastBlockIndex uint32 lock sync.RWMutex finale sync.Once handShake handShakeStage done chan struct{} sendQ chan []byte p2pSendQ chan []byte hpSendQ chan []byte wg sync.WaitGroup // number of sent pings. pingSent int pingTimer *time.Timer } // NewTCPPeer returns a TCPPeer structure based on the given connection. func NewTCPPeer(conn net.Conn, s *Server) *TCPPeer { return &TCPPeer{ conn: conn, server: s, done: make(chan struct{}), sendQ: make(chan []byte, requestQueueSize), p2pSendQ: make(chan []byte, p2pMsgQueueSize), hpSendQ: make(chan []byte, hpRequestQueueSize), } } // putPacketIntoQueue puts given message into the given queue if the peer has // done handshaking. func (p *TCPPeer) putPacketIntoQueue(queue chan<- []byte, msg []byte) error { if !p.Handshaked() { return errStateMismatch } select { case queue <- msg: case <-p.done: return errGone } return nil } // EnqueuePacket implements the Peer interface. func (p *TCPPeer) EnqueuePacket(msg []byte) error { return p.putPacketIntoQueue(p.sendQ, msg) } // putMessageIntoQueue serializes given Message and puts it into given queue if // the peer has done handshaking. func (p *TCPPeer) putMsgIntoQueue(queue chan<- []byte, msg *Message) error { b, err := msg.Bytes() if err != nil { return err } return p.putPacketIntoQueue(queue, b) } // EnqueueMessage is a temporary wrapper that sends a message via // EnqueuePacket if there is no error in serializing it. func (p *TCPPeer) EnqueueMessage(msg *Message) error { return p.putMsgIntoQueue(p.sendQ, msg) } // EnqueueP2PPacket implements the Peer interface. func (p *TCPPeer) EnqueueP2PPacket(msg []byte) error { return p.putPacketIntoQueue(p.p2pSendQ, msg) } // EnqueueP2PMessage implements the Peer interface. func (p *TCPPeer) EnqueueP2PMessage(msg *Message) error { return p.putMsgIntoQueue(p.p2pSendQ, msg) } // EnqueueHPPacket implements the Peer interface. It the peer is not yet // handshaked it's a noop. func (p *TCPPeer) EnqueueHPPacket(msg []byte) error { return p.putPacketIntoQueue(p.hpSendQ, msg) } func (p *TCPPeer) writeMsg(msg *Message) error { b, err := msg.Bytes() if err != nil { return err } _, err = p.conn.Write(b) return err } // handleConn handles the read side of the connection, it should be started as // a goroutine right after the new peer setup. func (p *TCPPeer) handleConn() { var err error p.server.register <- p go p.handleQueues() // When a new peer is connected we send out our version immediately. err = p.SendVersion() if err == nil { r := io.NewBinReaderFromIO(p.conn) for { msg := &Message{} err = msg.Decode(r) if err == payload.ErrTooManyHeaders { p.server.log.Warn("not all headers were processed") r.Err = nil } else if err != nil { break } if err = p.server.handleMessage(p, msg); err != nil { if p.Handshaked() { err = fmt.Errorf("handling %s message: %v", msg.Command.String(), err) } break } } } p.Disconnect(err) } // handleQueues is a goroutine that is started automatically to handle // send queues. func (p *TCPPeer) handleQueues() { var err error // p2psend queue shares its time with send queue in around // ((p2pSkipDivisor - 1) * 2 + 1)/1 ratio, ratio because the third // select can still choose p2psend over send. var p2pSkipCounter uint32 const p2pSkipDivisor = 4 for { var msg []byte // This one is to give priority to the hp queue select { case <-p.done: return case msg = <-p.hpSendQ: default: } // Skip this select every p2pSkipDivisor iteration. if msg == nil && p2pSkipCounter%p2pSkipDivisor != 0 { // Then look at the p2p queue. select { case <-p.done: return case msg = <-p.hpSendQ: case msg = <-p.p2pSendQ: default: } } // If there is no message in HP or P2P queues, block until one // appears in any of the queues. if msg == nil { select { case <-p.done: return case msg = <-p.hpSendQ: case msg = <-p.p2pSendQ: case msg = <-p.sendQ: } } _, err = p.conn.Write(msg) if err != nil { break } p2pSkipCounter++ } p.Disconnect(err) } // StartProtocol starts a long running background loop that interacts // every ProtoTickInterval with the peer. It's only good to run after the // handshake. func (p *TCPPeer) StartProtocol() { var err error p.server.log.Info("started protocol", zap.Stringer("addr", p.RemoteAddr()), zap.ByteString("userAgent", p.Version().UserAgent), zap.Uint32("startHeight", p.Version().StartHeight), zap.Uint32("id", p.Version().Nonce)) p.server.discovery.RegisterGoodAddr(p.PeerAddr().String()) if p.server.chain.HeaderHeight() < p.LastBlockIndex() { err = p.server.requestHeaders(p) if err != nil { p.Disconnect(err) return } } timer := time.NewTimer(p.server.ProtoTickInterval) for { select { case <-p.done: return case <-timer.C: // Try to sync in headers and block with the peer if his block height is higher then ours. if p.LastBlockIndex() > p.server.chain.BlockHeight() { err = p.server.requestBlocks(p) } if err == nil { timer.Reset(p.server.ProtoTickInterval) } } if err != nil { timer.Stop() p.Disconnect(err) return } } } // Handshaked returns status of the handshake, whether it's completed or not. func (p *TCPPeer) Handshaked() bool { p.lock.RLock() defer p.lock.RUnlock() return p.handShake == (verAckReceived | verAckSent | versionReceived | versionSent) } // SendVersion checks for the handshake state and sends a message to the peer. func (p *TCPPeer) SendVersion() error { msg := p.server.getVersionMsg() p.lock.Lock() defer p.lock.Unlock() if p.handShake&versionSent != 0 { return errors.New("invalid handshake: already sent Version") } err := p.writeMsg(msg) if err == nil { p.handShake |= versionSent } return err } // HandleVersion checks for the handshake state and version message contents. func (p *TCPPeer) HandleVersion(version *payload.Version) error { p.lock.Lock() defer p.lock.Unlock() if p.handShake&versionReceived != 0 { return errors.New("invalid handshake: already received Version") } p.version = version p.lastBlockIndex = version.StartHeight p.handShake |= versionReceived return nil } // SendVersionAck checks for the handshake state and sends a message to the peer. func (p *TCPPeer) SendVersionAck(msg *Message) error { p.lock.Lock() defer p.lock.Unlock() if p.handShake&versionReceived == 0 { return errors.New("invalid handshake: tried to send VersionAck, but no version received yet") } if p.handShake&versionSent == 0 { return errors.New("invalid handshake: tried to send VersionAck, but didn't send Version yet") } if p.handShake&verAckSent != 0 { return errors.New("invalid handshake: already sent VersionAck") } err := p.writeMsg(msg) if err == nil { p.handShake |= verAckSent } return err } // HandleVersionAck checks handshake sequence correctness when VerAck message // is received. func (p *TCPPeer) HandleVersionAck() error { p.lock.Lock() defer p.lock.Unlock() if p.handShake&versionSent == 0 { return errors.New("invalid handshake: received VersionAck, but no version sent yet") } if p.handShake&versionReceived == 0 { return errors.New("invalid handshake: received VersionAck, but no version received yet") } if p.handShake&verAckReceived != 0 { return errors.New("invalid handshake: already received VersionAck") } p.handShake |= verAckReceived return nil } // RemoteAddr implements the Peer interface. func (p *TCPPeer) RemoteAddr() net.Addr { return p.conn.RemoteAddr() } // PeerAddr implements the Peer interface. func (p *TCPPeer) PeerAddr() net.Addr { remote := p.conn.RemoteAddr() // The network can be non-tcp in unit tests. if p.version == nil || remote.Network() != "tcp" { return p.RemoteAddr() } host, _, err := net.SplitHostPort(remote.String()) if err != nil { return p.RemoteAddr() } addrString := net.JoinHostPort(host, strconv.Itoa(int(p.version.Port))) tcpAddr, err := net.ResolveTCPAddr("tcp", addrString) if err != nil { return p.RemoteAddr() } return tcpAddr } // Disconnect will fill the peer's done channel with the given error. func (p *TCPPeer) Disconnect(err error) { p.finale.Do(func() { close(p.done) p.conn.Close() p.server.unregister <- peerDrop{p, err} }) } // Version implements the Peer interface. func (p *TCPPeer) Version() *payload.Version { return p.version } // LastBlockIndex returns last block index. func (p *TCPPeer) LastBlockIndex() uint32 { p.lock.RLock() defer p.lock.RUnlock() return p.lastBlockIndex } // SendPing sends a ping message to the peer and does appropriate accounting of // outstanding pings and timeouts. func (p *TCPPeer) SendPing(msg *Message) error { if !p.Handshaked() { return errStateMismatch } p.lock.Lock() p.pingSent++ if p.pingTimer == nil { p.pingTimer = time.AfterFunc(p.server.PingTimeout, func() { p.Disconnect(errPingPong) }) } p.lock.Unlock() return p.EnqueueMessage(msg) } // 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() 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 }