package network import ( "context" "errors" "fmt" "net" "strconv" "sync" "time" "github.com/nspcc-dev/neo-go/pkg/io" "github.com/nspcc-dev/neo-go/pkg/network/capability" "github.com/nspcc-dev/neo-go/pkg/network/payload" "go.uber.org/atomic" ) type handShakeStage uint8 const ( versionSent handShakeStage = 1 << iota versionReceived verAckSent verAckReceived requestQueueSize = 32 p2pMsgQueueSize = 16 hpRequestQueueSize = 4 incomingQueueSize = 1 // Each message can be up to 32MB in size. ) 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 // pre-handshake non-canonical connection address. addr string lock sync.RWMutex finale sync.Once handShake handShakeStage isFullNode bool done chan struct{} sendQ chan []byte p2pSendQ chan []byte hpSendQ chan []byte incoming chan *Message // track outstanding getaddr requests. getAddrSent atomic.Int32 // number of sent pings. pingSent int pingTimer *time.Timer } // NewTCPPeer returns a TCPPeer structure based on the given connection. func NewTCPPeer(conn net.Conn, addr string, s *Server) *TCPPeer { return &TCPPeer{ conn: conn, server: s, addr: addr, done: make(chan struct{}), sendQ: make(chan []byte, requestQueueSize), p2pSendQ: make(chan []byte, p2pMsgQueueSize), hpSendQ: make(chan []byte, hpRequestQueueSize), incoming: make(chan *Message, incomingQueueSize), } } // putPacketIntoQueue puts the given message into the given queue if // the peer has done handshaking using the given context. func (p *TCPPeer) putPacketIntoQueue(ctx context.Context, queue chan<- []byte, msg []byte) error { if !p.Handshaked() { return errStateMismatch } select { case queue <- msg: case <-p.done: return errGone case <-ctx.Done(): return ctx.Err() } return nil } // BroadcastPacket implements the Peer interface. func (p *TCPPeer) BroadcastPacket(ctx context.Context, msg []byte) error { return p.putPacketIntoQueue(ctx, p.sendQ, msg) } // BroadcastHPPacket implements the Peer interface. It the peer is not yet // handshaked it's a noop. func (p *TCPPeer) BroadcastHPPacket(ctx context.Context, msg []byte) error { return p.putPacketIntoQueue(ctx, p.hpSendQ, msg) } // putMessageIntoQueue serializes the 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(context.Background(), queue, b) } // EnqueueP2PMessage implements the Peer interface. func (p *TCPPeer) EnqueueP2PMessage(msg *Message) error { return p.putMsgIntoQueue(p.p2pSendQ, msg) } // EnqueueHPMessage implements the Peer interface. func (p *TCPPeer) EnqueueHPMessage(msg *Message) error { return p.putMsgIntoQueue(p.hpSendQ, msg) } // EnqueueP2PPacket implements the Peer interface. func (p *TCPPeer) EnqueueP2PPacket(b []byte) error { return p.putPacketIntoQueue(context.Background(), p.p2pSendQ, b) } // EnqueueHPPacket implements the Peer interface. func (p *TCPPeer) EnqueueHPPacket(b []byte) error { return p.putPacketIntoQueue(context.Background(), p.hpSendQ, b) } 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 a new peer setup. func (p *TCPPeer) handleConn() { var err error p.server.register <- p go p.handleQueues() go p.handleIncoming() // 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{StateRootInHeader: p.server.config.StateRootInHeader} err = msg.Decode(r) if errors.Is(err, payload.ErrTooManyHeaders) { p.server.log.Warn("not all headers were processed") r.Err = nil } else if err != nil { break } p.incoming <- msg } } p.Disconnect(err) close(p.incoming) } func (p *TCPPeer) handleIncoming() { var err error for msg := range p.incoming { err = p.server.handleMessage(p, msg) if err != nil { if p.Handshaked() { err = fmt.Errorf("handling %s message: %w", 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 var writeTimeout = p.server.TimePerBlock 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.SetWriteDeadline(time.Now().Add(writeTimeout)) if err != nil { break } _, 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.handshake <- p err = p.server.requestBlocksOrHeaders(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 than ours. err = p.server.requestBlocksOrHeaders(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.handshaked() } // handshaked is internal unlocked version of Handshaked(). func (p *TCPPeer) handshaked() bool { return p.handShake == (verAckReceived | verAckSent | versionReceived | versionSent) } // IsFullNode returns whether the node has full capability or TCP/WS only. func (p *TCPPeer) IsFullNode() bool { p.lock.RLock() defer p.lock.RUnlock() return p.handshaked() && p.isFullNode } // SendVersion checks for the handshake state and sends a message to the peer. func (p *TCPPeer) SendVersion() error { msg, err := p.server.getVersionMsg(p.conn.LocalAddr()) if err != nil { return err } 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 for _, cap := range version.Capabilities { if cap.Type == capability.FullNode { p.isFullNode = true p.lastBlockIndex = cap.Data.(*capability.Node).StartHeight break } } 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 } // ConnectionAddr implements the Peer interface. func (p *TCPPeer) ConnectionAddr() string { if p.addr != "" { return p.addr } return p.conn.RemoteAddr().String() } // 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() } var port uint16 for _, cap := range p.version.Capabilities { if cap.Type == capability.TCPServer { port = cap.Data.(*capability.Server).Port } } if port == 0 { return p.RemoteAddr() } addrString := net.JoinHostPort(host, strconv.Itoa(int(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 the last block index. func (p *TCPPeer) LastBlockIndex() uint32 { p.lock.RLock() defer p.lock.RUnlock() return p.lastBlockIndex } // SetPingTimer adds an outgoing ping to the counter and sets a PingTimeout timer // that will shut the connection down in case of no response. func (p *TCPPeer) SetPingTimer() { p.lock.Lock() p.pingSent++ if p.pingTimer == nil { p.pingTimer = time.AfterFunc(p.server.PingTimeout, func() { p.Disconnect(errPingPong) }) } p.lock.Unlock() } // HandlePing handles a ping message received from the peer. func (p *TCPPeer) HandlePing(ping *payload.Ping) error { p.lock.Lock() defer p.lock.Unlock() p.lastBlockIndex = ping.LastBlockIndex return nil } // HandlePong handles a pong message received from the peer and does an 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 } // AddGetAddrSent increments internal outstanding getaddr requests counter. Then, // the peer can only send one addr reply per getaddr request. func (p *TCPPeer) AddGetAddrSent() { p.getAddrSent.Inc() } // CanProcessAddr decrements internal outstanding getaddr requests counter and // answers whether the addr command from the peer can be safely processed. func (p *TCPPeer) CanProcessAddr() bool { v := p.getAddrSent.Dec() return v >= 0 }