package network import ( "crypto/rand" "encoding/binary" "errors" "fmt" "net" "strconv" "sync" "time" "github.com/CityOfZion/neo-go/pkg/consensus" "github.com/CityOfZion/neo-go/pkg/core" "github.com/CityOfZion/neo-go/pkg/core/block" "github.com/CityOfZion/neo-go/pkg/core/transaction" "github.com/CityOfZion/neo-go/pkg/network/payload" "github.com/CityOfZion/neo-go/pkg/util" "go.uber.org/atomic" "go.uber.org/zap" ) const ( // peer numbers are arbitrary at the moment. defaultMinPeers = 5 defaultAttemptConnPeers = 20 defaultMaxPeers = 100 maxBlockBatch = 200 maxAddrsToSend = 200 minPoolCount = 30 ) var ( errAlreadyConnected = errors.New("already connected") errIdenticalID = errors.New("identical node id") errInvalidHandshake = errors.New("invalid handshake") errInvalidNetwork = errors.New("invalid network") errMaxPeers = errors.New("max peers reached") errServerShutdown = errors.New("server shutdown") errInvalidInvType = errors.New("invalid inventory type") errInvalidHashStart = errors.New("invalid requested HashStart") ) type ( // Server represents the local Node in the network. Its transport could // be of any kind. Server struct { // ServerConfig holds the Server configuration. ServerConfig // id also known as the nonce of the server. id uint32 transport Transporter discovery Discoverer chain core.Blockchainer bQueue *blockQueue consensus consensus.Service lock sync.RWMutex peers map[Peer]bool register chan Peer unregister chan peerDrop quit chan struct{} consensusStarted *atomic.Bool log *zap.Logger } peerDrop struct { peer Peer reason error } ) func randomID() uint32 { buf := make([]byte, 4) _, _ = rand.Read(buf) return binary.BigEndian.Uint32(buf) } // NewServer returns a new Server, initialized with the given configuration. func NewServer(config ServerConfig, chain core.Blockchainer, log *zap.Logger) (*Server, error) { if log == nil { return nil, errors.New("logger is a required parameter") } s := &Server{ ServerConfig: config, chain: chain, id: randomID(), quit: make(chan struct{}), register: make(chan Peer), unregister: make(chan peerDrop), peers: make(map[Peer]bool), consensusStarted: atomic.NewBool(false), log: log, } s.bQueue = newBlockQueue(maxBlockBatch, chain, log, func(b *block.Block) { if s.consensusStarted.Load() { s.consensus.OnNewBlock() } else { s.tryStartConsensus() } s.relayBlock(b) }) srv, err := consensus.NewService(consensus.Config{ Logger: log, Broadcast: s.handleNewPayload, RelayBlock: s.relayBlock, Chain: chain, RequestTx: s.requestTx, Wallet: config.Wallet, TimePerBlock: config.TimePerBlock, }) if err != nil { return nil, err } s.consensus = srv if s.MinPeers < 0 { s.log.Info("bad MinPeers configured, using the default value", zap.Int("configured", s.MinPeers), zap.Int("actual", defaultMinPeers)) s.MinPeers = defaultMinPeers } if s.MaxPeers <= 0 { s.log.Info("bad MaxPeers configured, using the default value", zap.Int("configured", s.MaxPeers), zap.Int("actual", defaultMaxPeers)) s.MaxPeers = defaultMaxPeers } if s.AttemptConnPeers <= 0 { s.log.Info("bad AttemptConnPeers configured, using the default value", zap.Int("configured", s.AttemptConnPeers), zap.Int("actual", defaultAttemptConnPeers)) s.AttemptConnPeers = defaultAttemptConnPeers } s.transport = NewTCPTransport(s, fmt.Sprintf("%s:%d", config.Address, config.Port), s.log) s.discovery = NewDefaultDiscovery( s.DialTimeout, s.transport, ) return s, nil } // MkMsg creates a new message based on the server configured network and given // parameters. func (s *Server) MkMsg(cmd CommandType, p payload.Payload) *Message { return NewMessage(s.Net, cmd, p) } // ID returns the servers ID. func (s *Server) ID() uint32 { return s.id } // Start will start the server and its underlying transport. func (s *Server) Start(errChan chan error) { s.log.Info("node started", zap.Uint32("blockHeight", s.chain.BlockHeight()), zap.Uint32("headerHeight", s.chain.HeaderHeight())) s.tryStartConsensus() s.discovery.BackFill(s.Seeds...) go s.bQueue.run() go s.transport.Accept() setServerAndNodeVersions(s.UserAgent, strconv.FormatUint(uint64(s.id), 10)) s.run() } // Shutdown disconnects all peers and stops listening. func (s *Server) Shutdown() { s.log.Info("shutting down server", zap.Int("peers", s.PeerCount())) s.bQueue.discard() close(s.quit) } // UnconnectedPeers returns a list of peers that are in the discovery peer list // but are not connected to the server. func (s *Server) UnconnectedPeers() []string { return s.discovery.UnconnectedPeers() } // BadPeers returns a list of peers the are flagged as "bad" peers. func (s *Server) BadPeers() []string { return s.discovery.BadPeers() } // ConnectedPeers returns a list of currently connected peers. func (s *Server) ConnectedPeers() []string { s.lock.RLock() defer s.lock.RUnlock() peers := make([]string, 0, len(s.peers)) for k := range s.peers { peers = append(peers, k.PeerAddr().String()) } return peers } // run is a goroutine that starts another goroutine to manage protocol specifics // while itself dealing with peers management (handling connects/disconnects). func (s *Server) run() { go s.runProto() for { if s.PeerCount() < s.MinPeers { s.discovery.RequestRemote(s.AttemptConnPeers) } if s.discovery.PoolCount() < minPoolCount { s.broadcastHPMessage(s.MkMsg(CMDGetAddr, payload.NewNullPayload())) } select { case <-s.quit: s.transport.Close() for p := range s.peers { p.Disconnect(errServerShutdown) } return case p := <-s.register: s.lock.Lock() s.peers[p] = true s.lock.Unlock() peerCount := s.PeerCount() s.log.Info("new peer connected", zap.Stringer("addr", p.RemoteAddr()), zap.Int("peerCount", peerCount)) if peerCount > s.MaxPeers { s.lock.RLock() // Pick a random peer and drop connection to it. for peer := range s.peers { peer.Disconnect(errMaxPeers) break } s.lock.RUnlock() } updatePeersConnectedMetric(s.PeerCount()) case drop := <-s.unregister: s.lock.Lock() if s.peers[drop.peer] { delete(s.peers, drop.peer) s.lock.Unlock() s.log.Warn("peer disconnected", zap.Stringer("addr", drop.peer.RemoteAddr()), zap.String("reason", drop.reason.Error()), zap.Int("peerCount", s.PeerCount())) addr := drop.peer.PeerAddr().String() if drop.reason == errIdenticalID { s.discovery.RegisterBadAddr(addr) } else if drop.reason != errAlreadyConnected { s.discovery.UnregisterConnectedAddr(addr) s.discovery.BackFill(addr) } updatePeersConnectedMetric(s.PeerCount()) } else { // else the peer is already gone, which can happen // because we have two goroutines sending signals here s.lock.Unlock() } } } } // runProto is a goroutine that manages server-wide protocol events. func (s *Server) runProto() { pingTimer := time.NewTimer(s.PingInterval) for { prevHeight := s.chain.BlockHeight() select { case <-s.quit: return case <-pingTimer.C: if s.chain.BlockHeight() == prevHeight { // Get a copy of s.peers to avoid holding a lock while sending. for peer := range s.Peers() { _ = peer.SendPing(s.MkMsg(CMDPing, payload.NewPing(s.id, s.chain.HeaderHeight()))) } } pingTimer.Reset(s.PingInterval) } } } func (s *Server) tryStartConsensus() { if s.Wallet == nil || s.consensusStarted.Load() { return } if s.IsInSync() { s.log.Info("node reached synchronized state, starting consensus") if s.consensusStarted.CAS(false, true) { s.consensus.Start() } } } // Peers returns the current list of peers connected to // the server. func (s *Server) Peers() map[Peer]bool { s.lock.RLock() defer s.lock.RUnlock() peers := make(map[Peer]bool, len(s.peers)) for k, v := range s.peers { peers[k] = v } return peers } // PeerCount returns the number of current connected peers. func (s *Server) PeerCount() int { s.lock.RLock() defer s.lock.RUnlock() return len(s.peers) } // HandshakedPeersCount returns the number of connected peers // which have already performed handshake. func (s *Server) HandshakedPeersCount() int { s.lock.RLock() defer s.lock.RUnlock() var count int for p := range s.peers { if p.Handshaked() { count++ } } return count } // getVersionMsg returns current version message. func (s *Server) getVersionMsg() *Message { payload := payload.NewVersion( s.id, s.Port, s.UserAgent, s.chain.BlockHeight(), s.Relay, ) return s.MkMsg(CMDVersion, payload) } // IsInSync answers the question of whether the server is in sync with the // network or not (at least how the server itself sees it). The server operates // with the data that it has, the number of peers (that has to be more than // minimum number) and height of these peers (our chain has to be not lower // than 2/3 of our peers have). Ideally we would check for the highest of the // peers, but the problem is that they can lie to us and send whatever height // they want to. func (s *Server) IsInSync() bool { var peersNumber int var notHigher int if s.MinPeers == 0 { return true } ourLastBlock := s.chain.BlockHeight() s.lock.RLock() for p := range s.peers { if p.Handshaked() { peersNumber++ if ourLastBlock >= p.LastBlockIndex() { notHigher++ } } } s.lock.RUnlock() // Checking bQueue would also be nice, but it can be filled with garbage // easily at the moment. return peersNumber >= s.MinPeers && (3*notHigher > 2*peersNumber) // && s.bQueue.length() == 0 } // When a peer sends out his version we reply with verack after validating // the version. func (s *Server) handleVersionCmd(p Peer, version *payload.Version) error { err := p.HandleVersion(version) if err != nil { return err } if s.id == version.Nonce { return errIdenticalID } peerAddr := p.PeerAddr().String() s.discovery.RegisterConnectedAddr(peerAddr) s.lock.RLock() for peer := range s.peers { if p == peer { continue } ver := peer.Version() // Already connected, drop this connection. if ver != nil && ver.Nonce == version.Nonce && peer.PeerAddr().String() == peerAddr { s.lock.RUnlock() return errAlreadyConnected } } s.lock.RUnlock() return p.SendVersionAck(s.MkMsg(CMDVerack, nil)) } // handleHeadersCmd processes the headers received from its peer. // If the headerHeight of the blockchain still smaller then the peer // the server will request more headers. // This method could best be called in a separate routine. func (s *Server) handleHeadersCmd(p Peer, headers *payload.Headers) { if err := s.chain.AddHeaders(headers.Hdrs...); err != nil { s.log.Warn("failed processing headers", zap.Error(err)) return } // The peer will respond with a maximum of 2000 headers in one batch. // We will ask one more batch here if needed. Eventually we will get synced // due to the startProtocol routine that will ask headers every protoTick. if s.chain.HeaderHeight() < p.LastBlockIndex() { s.requestHeaders(p) } } // handleBlockCmd processes the received block received from its peer. func (s *Server) handleBlockCmd(p Peer, block *block.Block) error { return s.bQueue.putBlock(block) } // handlePing processes ping request. func (s *Server) handlePing(p Peer, ping *payload.Ping) error { return p.EnqueueP2PMessage(s.MkMsg(CMDPong, payload.NewPing(s.chain.BlockHeight(), s.id))) } // handlePing processes pong request. func (s *Server) handlePong(p Peer, pong *payload.Ping) error { err := p.HandlePong(pong) if err != nil { return err } if s.chain.HeaderHeight() < pong.LastBlockIndex { return s.requestHeaders(p) } return nil } // handleInvCmd processes the received inventory. func (s *Server) handleInvCmd(p Peer, inv *payload.Inventory) error { reqHashes := make([]util.Uint256, 0) var typExists = map[payload.InventoryType]func(util.Uint256) bool{ payload.TXType: s.chain.HasTransaction, payload.BlockType: s.chain.HasBlock, payload.ConsensusType: func(h util.Uint256) bool { cp := s.consensus.GetPayload(h) return cp != nil }, } if exists := typExists[inv.Type]; exists != nil { for _, hash := range inv.Hashes { if !exists(hash) { reqHashes = append(reqHashes, hash) } } } if len(reqHashes) > 0 { msg := s.MkMsg(CMDGetData, payload.NewInventory(inv.Type, reqHashes)) pkt, err := msg.Bytes() if err != nil { return err } if inv.Type == payload.ConsensusType { return p.EnqueueHPPacket(pkt) } return p.EnqueueP2PPacket(pkt) } return nil } // handleInvCmd processes the received inventory. func (s *Server) handleGetDataCmd(p Peer, inv *payload.Inventory) error { for _, hash := range inv.Hashes { var msg *Message switch inv.Type { case payload.TXType: tx, _, err := s.chain.GetTransaction(hash) if err == nil { msg = s.MkMsg(CMDTX, tx) } case payload.BlockType: b, err := s.chain.GetBlock(hash) if err == nil { msg = s.MkMsg(CMDBlock, b) } case payload.ConsensusType: if cp := s.consensus.GetPayload(hash); cp != nil { msg = s.MkMsg(CMDConsensus, cp) } } if msg != nil { pkt, err := msg.Bytes() if err == nil { if inv.Type == payload.ConsensusType { err = p.EnqueueHPPacket(pkt) } else { err = p.EnqueueP2PPacket(pkt) } } if err != nil { return err } } } return nil } // handleGetBlocksCmd processes the getblocks request. func (s *Server) handleGetBlocksCmd(p Peer, gb *payload.GetBlocks) error { if len(gb.HashStart) < 1 { return errInvalidHashStart } startHash := gb.HashStart[0] if startHash.Equals(gb.HashStop) { return nil } start, err := s.chain.GetHeader(startHash) if err != nil { return err } blockHashes := make([]util.Uint256, 0) for i := start.Index + 1; i < start.Index+1+payload.MaxHashesCount; i++ { hash := s.chain.GetHeaderHash(int(i)) if hash.Equals(util.Uint256{}) || hash.Equals(gb.HashStop) { break } blockHashes = append(blockHashes, hash) } if len(blockHashes) == 0 { return nil } payload := payload.NewInventory(payload.BlockType, blockHashes) msg := s.MkMsg(CMDInv, payload) return p.EnqueueP2PMessage(msg) } // handleGetHeadersCmd processes the getheaders request. func (s *Server) handleGetHeadersCmd(p Peer, gh *payload.GetBlocks) error { if len(gh.HashStart) < 1 { return errInvalidHashStart } startHash := gh.HashStart[0] start, err := s.chain.GetHeader(startHash) if err != nil { return err } resp := payload.Headers{} resp.Hdrs = make([]*block.Header, 0, payload.MaxHeadersAllowed) for i := start.Index + 1; i < start.Index+1+payload.MaxHeadersAllowed; i++ { hash := s.chain.GetHeaderHash(int(i)) if hash.Equals(util.Uint256{}) || hash.Equals(gh.HashStop) { break } header, err := s.chain.GetHeader(hash) if err != nil { break } resp.Hdrs = append(resp.Hdrs, header) } if len(resp.Hdrs) == 0 { return nil } msg := s.MkMsg(CMDHeaders, &resp) return p.EnqueueP2PMessage(msg) } // handleConsensusCmd processes received consensus payload. // It never returns an error. func (s *Server) handleConsensusCmd(cp *consensus.Payload) error { s.consensus.OnPayload(cp) return nil } // handleTxCmd processes received transaction. // It never returns an error. func (s *Server) handleTxCmd(tx *transaction.Transaction) error { // It's OK for it to fail for various reasons like tx already existing // in the pool. if s.verifyAndPoolTX(tx) == RelaySucceed { s.consensus.OnTransaction(tx) go s.broadcastTX(tx) } return nil } // handleAddrCmd will process received addresses. func (s *Server) handleAddrCmd(p Peer, addrs *payload.AddressList) error { for _, a := range addrs.Addrs { s.discovery.BackFill(a.IPPortString()) } return nil } // handleGetAddrCmd sends to the peer some good addresses that we know of. func (s *Server) handleGetAddrCmd(p Peer) error { addrs := s.discovery.GoodPeers() if len(addrs) > maxAddrsToSend { addrs = addrs[:maxAddrsToSend] } alist := payload.NewAddressList(len(addrs)) ts := time.Now() for i, addr := range addrs { // we know it's a good address, so it can't fail netaddr, _ := net.ResolveTCPAddr("tcp", addr) alist.Addrs[i] = payload.NewAddressAndTime(netaddr, ts) } return p.EnqueueP2PMessage(s.MkMsg(CMDAddr, alist)) } // requestHeaders sends a getheaders message to the peer. // The peer will respond with headers op to a count of 2000. func (s *Server) requestHeaders(p Peer) error { start := []util.Uint256{s.chain.CurrentHeaderHash()} payload := payload.NewGetBlocks(start, util.Uint256{}) return p.EnqueueP2PMessage(s.MkMsg(CMDGetHeaders, payload)) } // requestBlocks sends a getdata message to the peer // to sync up in blocks. A maximum of maxBlockBatch will // send at once. func (s *Server) requestBlocks(p Peer) error { var ( hashes []util.Uint256 hashStart = s.chain.BlockHeight() + 1 headerHeight = s.chain.HeaderHeight() ) for hashStart <= headerHeight && len(hashes) < maxBlockBatch { hash := s.chain.GetHeaderHash(int(hashStart)) hashes = append(hashes, hash) hashStart++ } if len(hashes) > 0 { payload := payload.NewInventory(payload.BlockType, hashes) return p.EnqueueP2PMessage(s.MkMsg(CMDGetData, payload)) } else if s.chain.HeaderHeight() < p.LastBlockIndex() { return s.requestHeaders(p) } return nil } // handleMessage processes the given message. func (s *Server) handleMessage(peer Peer, msg *Message) error { s.log.Debug("got msg", zap.Stringer("addr", peer.RemoteAddr()), zap.String("type", string(msg.CommandType()))) // Make sure both server and peer are operating on // the same network. if msg.Magic != s.Net { return errInvalidNetwork } if peer.Handshaked() { if inv, ok := msg.Payload.(*payload.Inventory); ok { if !inv.Type.Valid() || len(inv.Hashes) == 0 { return errInvalidInvType } } switch msg.CommandType() { case CMDAddr: addrs := msg.Payload.(*payload.AddressList) return s.handleAddrCmd(peer, addrs) case CMDGetAddr: // it has no payload return s.handleGetAddrCmd(peer) case CMDGetBlocks: gb := msg.Payload.(*payload.GetBlocks) return s.handleGetBlocksCmd(peer, gb) case CMDGetData: inv := msg.Payload.(*payload.Inventory) return s.handleGetDataCmd(peer, inv) case CMDGetHeaders: gh := msg.Payload.(*payload.GetBlocks) return s.handleGetHeadersCmd(peer, gh) case CMDHeaders: headers := msg.Payload.(*payload.Headers) go s.handleHeadersCmd(peer, headers) case CMDInv: inventory := msg.Payload.(*payload.Inventory) return s.handleInvCmd(peer, inventory) case CMDBlock: block := msg.Payload.(*block.Block) return s.handleBlockCmd(peer, block) case CMDConsensus: cp := msg.Payload.(*consensus.Payload) return s.handleConsensusCmd(cp) case CMDTX: tx := msg.Payload.(*transaction.Transaction) return s.handleTxCmd(tx) case CMDPing: ping := msg.Payload.(*payload.Ping) return s.handlePing(peer, ping) case CMDPong: pong := msg.Payload.(*payload.Ping) return s.handlePong(peer, pong) case CMDVersion, CMDVerack: return fmt.Errorf("received '%s' after the handshake", msg.CommandType()) } } else { switch msg.CommandType() { case CMDVersion: version := msg.Payload.(*payload.Version) return s.handleVersionCmd(peer, version) case CMDVerack: err := peer.HandleVersionAck() if err != nil { return err } go peer.StartProtocol() s.tryStartConsensus() default: return fmt.Errorf("received '%s' during handshake", msg.CommandType()) } } return nil } func (s *Server) handleNewPayload(p *consensus.Payload) { msg := s.MkMsg(CMDInv, payload.NewInventory(payload.ConsensusType, []util.Uint256{p.Hash()})) // It's high priority because it directly affects consensus process, // even though it's just an inv. s.broadcastHPMessage(msg) } func (s *Server) requestTx(hashes ...util.Uint256) { if len(hashes) == 0 { return } msg := s.MkMsg(CMDGetData, payload.NewInventory(payload.TXType, hashes)) // It's high priority because it directly affects consensus process, // even though it's getdata. s.broadcastHPMessage(msg) } // iteratePeersWithSendMsg sends given message to all peers using two functions // passed, one is to send the message and the other is to filtrate peers (the // peer is considered invalid if it returns false). func (s *Server) iteratePeersWithSendMsg(msg *Message, send func(Peer, []byte) error, peerOK func(Peer) bool) { pkt, err := msg.Bytes() if err != nil { return } // Get a copy of s.peers to avoid holding a lock while sending. for peer := range s.Peers() { if peerOK != nil && !peerOK(peer) { continue } // Who cares about these messages anyway? _ = send(peer, pkt) } } // broadcastMessage sends the message to all available peers. func (s *Server) broadcastMessage(msg *Message) { s.iteratePeersWithSendMsg(msg, Peer.EnqueuePacket, nil) } // broadcastHPMessage sends the high-priority message to all available peers. func (s *Server) broadcastHPMessage(msg *Message) { s.iteratePeersWithSendMsg(msg, Peer.EnqueueHPPacket, nil) } // relayBlock tells all the other connected nodes about the given block. func (s *Server) relayBlock(b *block.Block) { msg := s.MkMsg(CMDInv, payload.NewInventory(payload.BlockType, []util.Uint256{b.Hash()})) // Filter out nodes that are more current (avoid spamming the network // during initial sync). s.iteratePeersWithSendMsg(msg, Peer.EnqueuePacket, func(p Peer) bool { return p.Handshaked() && p.LastBlockIndex() < b.Index }) } // verifyAndPoolTX verifies the TX and adds it to the local mempool. func (s *Server) verifyAndPoolTX(t *transaction.Transaction) RelayReason { if t.Type == transaction.MinerType { return RelayInvalid } if err := s.chain.PoolTx(t); err != nil { switch err { case core.ErrAlreadyExists: return RelayAlreadyExists case core.ErrOOM: return RelayOutOfMemory case core.ErrPolicy: return RelayPolicyFail default: return RelayInvalid } } return RelaySucceed } // RelayTxn a new transaction to the local node and the connected peers. // Reference: the method OnRelay in C#: https://github.com/neo-project/neo/blob/master/neo/Network/P2P/LocalNode.cs#L159 func (s *Server) RelayTxn(t *transaction.Transaction) RelayReason { ret := s.verifyAndPoolTX(t) if ret == RelaySucceed { s.broadcastTX(t) } return ret } // broadcastTX broadcasts an inventory message about new transaction. func (s *Server) broadcastTX(t *transaction.Transaction) { msg := s.MkMsg(CMDInv, payload.NewInventory(payload.TXType, []util.Uint256{t.Hash()})) // We need to filter out non-relaying nodes, so plain broadcast // functions don't fit here. s.iteratePeersWithSendMsg(msg, Peer.EnqueuePacket, func(p Peer) bool { return p.Handshaked() && p.Version().Relay }) }