package p2p import ( "fmt" "math" "math/rand" "net" "sync" "time" cfg "github.com/tendermint/tendermint/config" "github.com/tendermint/tendermint/p2p/conn" cmn "github.com/tendermint/tmlibs/common" ) const ( // wait a random amount of time from this interval // before dialing peers or reconnecting to help prevent DoS dialRandomizerIntervalMilliseconds = 3000 // repeatedly try to reconnect for a few minutes // ie. 5 * 20 = 100s reconnectAttempts = 20 reconnectInterval = 5 * time.Second // then move into exponential backoff mode for ~1day // ie. 3**10 = 16hrs reconnectBackOffAttempts = 10 reconnectBackOffBaseSeconds = 3 ) //----------------------------------------------------------------------------- // An AddrBook represents an address book from the pex package, which is used // to store peer addresses. type AddrBook interface { AddAddress(addr *NetAddress, src *NetAddress) error AddOurAddress(*NetAddress) OurAddress(*NetAddress) bool MarkGood(*NetAddress) RemoveAddress(*NetAddress) HasAddress(*NetAddress) bool Save() } //----------------------------------------------------------------------------- // Switch handles peer connections and exposes an API to receive incoming messages // on `Reactors`. Each `Reactor` is responsible for handling incoming messages of one // or more `Channels`. So while sending outgoing messages is typically performed on the peer, // incoming messages are received on the reactor. type Switch struct { cmn.BaseService config *cfg.P2PConfig peerConfig *PeerConfig listeners []Listener reactors map[string]Reactor chDescs []*conn.ChannelDescriptor reactorsByCh map[byte]Reactor peers *PeerSet dialing *cmn.CMap nodeInfo NodeInfo // our node info nodeKey *NodeKey // our node privkey addrBook AddrBook filterConnByAddr func(net.Addr) error filterConnByID func(ID) error rng *rand.Rand // seed for randomizing dial times and orders } // NewSwitch creates a new Switch with the given config. func NewSwitch(config *cfg.P2PConfig) *Switch { sw := &Switch{ config: config, peerConfig: DefaultPeerConfig(), reactors: make(map[string]Reactor), chDescs: make([]*conn.ChannelDescriptor, 0), reactorsByCh: make(map[byte]Reactor), peers: NewPeerSet(), dialing: cmn.NewCMap(), } // Ensure we have a completely undeterministic PRNG. cmd.RandInt64() draws // from a seed that's initialized with OS entropy on process start. sw.rng = rand.New(rand.NewSource(cmn.RandInt64())) // TODO: collapse the peerConfig into the config ? sw.peerConfig.MConfig.FlushThrottle = time.Duration(config.FlushThrottleTimeout) * time.Millisecond sw.peerConfig.MConfig.SendRate = config.SendRate sw.peerConfig.MConfig.RecvRate = config.RecvRate sw.peerConfig.MConfig.MaxPacketMsgPayloadSize = config.MaxPacketMsgPayloadSize sw.peerConfig.AuthEnc = config.AuthEnc sw.BaseService = *cmn.NewBaseService(nil, "P2P Switch", sw) return sw } //--------------------------------------------------------------------- // Switch setup // AddReactor adds the given reactor to the switch. // NOTE: Not goroutine safe. func (sw *Switch) AddReactor(name string, reactor Reactor) Reactor { // Validate the reactor. // No two reactors can share the same channel. reactorChannels := reactor.GetChannels() for _, chDesc := range reactorChannels { chID := chDesc.ID if sw.reactorsByCh[chID] != nil { cmn.PanicSanity(fmt.Sprintf("Channel %X has multiple reactors %v & %v", chID, sw.reactorsByCh[chID], reactor)) } sw.chDescs = append(sw.chDescs, chDesc) sw.reactorsByCh[chID] = reactor } sw.reactors[name] = reactor reactor.SetSwitch(sw) return reactor } // Reactors returns a map of reactors registered on the switch. // NOTE: Not goroutine safe. func (sw *Switch) Reactors() map[string]Reactor { return sw.reactors } // Reactor returns the reactor with the given name. // NOTE: Not goroutine safe. func (sw *Switch) Reactor(name string) Reactor { return sw.reactors[name] } // AddListener adds the given listener to the switch for listening to incoming peer connections. // NOTE: Not goroutine safe. func (sw *Switch) AddListener(l Listener) { sw.listeners = append(sw.listeners, l) } // Listeners returns the list of listeners the switch listens on. // NOTE: Not goroutine safe. func (sw *Switch) Listeners() []Listener { return sw.listeners } // IsListening returns true if the switch has at least one listener. // NOTE: Not goroutine safe. func (sw *Switch) IsListening() bool { return len(sw.listeners) > 0 } // SetNodeInfo sets the switch's NodeInfo for checking compatibility and handshaking with other nodes. // NOTE: Not goroutine safe. func (sw *Switch) SetNodeInfo(nodeInfo NodeInfo) { sw.nodeInfo = nodeInfo } // NodeInfo returns the switch's NodeInfo. // NOTE: Not goroutine safe. func (sw *Switch) NodeInfo() NodeInfo { return sw.nodeInfo } // SetNodeKey sets the switch's private key for authenticated encryption. // NOTE: Not goroutine safe. func (sw *Switch) SetNodeKey(nodeKey *NodeKey) { sw.nodeKey = nodeKey } //--------------------------------------------------------------------- // Service start/stop // OnStart implements BaseService. It starts all the reactors, peers, and listeners. func (sw *Switch) OnStart() error { // Start reactors for _, reactor := range sw.reactors { err := reactor.Start() if err != nil { return cmn.ErrorWrap(err, "failed to start %v", reactor) } } // Start listeners for _, listener := range sw.listeners { go sw.listenerRoutine(listener) } return nil } // OnStop implements BaseService. It stops all listeners, peers, and reactors. func (sw *Switch) OnStop() { // Stop listeners for _, listener := range sw.listeners { listener.Stop() } sw.listeners = nil // Stop peers for _, peer := range sw.peers.List() { peer.Stop() sw.peers.Remove(peer) } // Stop reactors sw.Logger.Debug("Switch: Stopping reactors") for _, reactor := range sw.reactors { reactor.Stop() } } //--------------------------------------------------------------------- // Peers // Broadcast runs a go routine for each attempted send, which will block trying // to send for defaultSendTimeoutSeconds. Returns a channel which receives // success values for each attempted send (false if times out). Channel will be // closed once msg bytes are sent to all peers (or time out). // // NOTE: Broadcast uses goroutines, so order of broadcast may not be preserved. func (sw *Switch) Broadcast(chID byte, msgBytes []byte) chan bool { successChan := make(chan bool, len(sw.peers.List())) sw.Logger.Debug("Broadcast", "channel", chID, "msgBytes", fmt.Sprintf("%X", msgBytes)) var wg sync.WaitGroup for _, peer := range sw.peers.List() { wg.Add(1) go func(peer Peer) { defer wg.Done() success := peer.Send(chID, msgBytes) successChan <- success }(peer) } go func() { wg.Wait() close(successChan) }() return successChan } // NumPeers returns the count of outbound/inbound and outbound-dialing peers. func (sw *Switch) NumPeers() (outbound, inbound, dialing int) { peers := sw.peers.List() for _, peer := range peers { if peer.IsOutbound() { outbound++ } else { inbound++ } } dialing = sw.dialing.Size() return } // Peers returns the set of peers that are connected to the switch. func (sw *Switch) Peers() IPeerSet { return sw.peers } // StopPeerForError disconnects from a peer due to external error. // If the peer is persistent, it will attempt to reconnect. // TODO: make record depending on reason. func (sw *Switch) StopPeerForError(peer Peer, reason interface{}) { sw.Logger.Error("Stopping peer for error", "peer", peer, "err", reason) sw.stopAndRemovePeer(peer, reason) if peer.IsPersistent() { go sw.reconnectToPeer(peer) } } // StopPeerGracefully disconnects from a peer gracefully. // TODO: handle graceful disconnects. func (sw *Switch) StopPeerGracefully(peer Peer) { sw.Logger.Info("Stopping peer gracefully") sw.stopAndRemovePeer(peer, nil) } func (sw *Switch) stopAndRemovePeer(peer Peer, reason interface{}) { sw.peers.Remove(peer) peer.Stop() for _, reactor := range sw.reactors { reactor.RemovePeer(peer, reason) } } // reconnectToPeer tries to reconnect to the peer, first repeatedly // with a fixed interval, then with exponential backoff. // If no success after all that, it stops trying, and leaves it // to the PEX/Addrbook to find the peer again func (sw *Switch) reconnectToPeer(peer Peer) { // NOTE this will connect to the self reported address, // not necessarily the original we dialed netAddr := peer.NodeInfo().NetAddress() start := time.Now() sw.Logger.Info("Reconnecting to peer", "peer", peer) for i := 0; i < reconnectAttempts; i++ { if !sw.IsRunning() { return } err := sw.DialPeerWithAddress(netAddr, true) if err != nil { sw.Logger.Info("Error reconnecting to peer. Trying again", "tries", i, "err", err, "peer", peer) // sleep a set amount sw.randomSleep(reconnectInterval) continue } else { return } } sw.Logger.Error("Failed to reconnect to peer. Beginning exponential backoff", "peer", peer, "elapsed", time.Since(start)) for i := 0; i < reconnectBackOffAttempts; i++ { if !sw.IsRunning() { return } // sleep an exponentially increasing amount sleepIntervalSeconds := math.Pow(reconnectBackOffBaseSeconds, float64(i)) sw.randomSleep(time.Duration(sleepIntervalSeconds) * time.Second) err := sw.DialPeerWithAddress(netAddr, true) if err == nil { return // success } sw.Logger.Info("Error reconnecting to peer. Trying again", "tries", i, "err", err, "peer", peer) } sw.Logger.Error("Failed to reconnect to peer. Giving up", "peer", peer, "elapsed", time.Since(start)) } // SetAddrBook allows to set address book on Switch. func (sw *Switch) SetAddrBook(addrBook AddrBook) { sw.addrBook = addrBook } // MarkPeerAsGood marks the given peer as good when it did something useful // like contributed to consensus. func (sw *Switch) MarkPeerAsGood(peer Peer) { if sw.addrBook != nil { sw.addrBook.MarkGood(peer.NodeInfo().NetAddress()) } } //--------------------------------------------------------------------- // Dialing // IsDialing returns true if the switch is currently dialing the given ID. func (sw *Switch) IsDialing(id ID) bool { return sw.dialing.Has(string(id)) } // DialPeersAsync dials a list of peers asynchronously in random order (optionally, making them persistent). func (sw *Switch) DialPeersAsync(addrBook AddrBook, peers []string, persistent bool) error { netAddrs, errs := NewNetAddressStrings(peers) // only log errors, dial correct addresses for _, err := range errs { sw.Logger.Error("Error in peer's address", "err", err) } ourAddr := sw.nodeInfo.NetAddress() // TODO: move this out of here ? if addrBook != nil { // add peers to `addrBook` for _, netAddr := range netAddrs { // do not add our address or ID if !netAddr.Same(ourAddr) { addrBook.AddAddress(netAddr, ourAddr) } } // Persist some peers to disk right away. // NOTE: integration tests depend on this addrBook.Save() } // permute the list, dial them in random order. perm := sw.rng.Perm(len(netAddrs)) for i := 0; i < len(perm); i++ { go func(i int) { j := perm[i] // do not dial ourselves if netAddrs[j].Same(ourAddr) { return } sw.randomSleep(0) err := sw.DialPeerWithAddress(netAddrs[j], persistent) if err != nil { sw.Logger.Error("Error dialing peer", "err", err) } }(i) } return nil } // DialPeerWithAddress dials the given peer and runs sw.addPeer if it connects and authenticates successfully. // If `persistent == true`, the switch will always try to reconnect to this peer if the connection ever fails. func (sw *Switch) DialPeerWithAddress(addr *NetAddress, persistent bool) error { sw.dialing.Set(string(addr.ID), addr) defer sw.dialing.Delete(string(addr.ID)) return sw.addOutboundPeerWithConfig(addr, sw.peerConfig, persistent) } // sleep for interval plus some random amount of ms on [0, dialRandomizerIntervalMilliseconds] func (sw *Switch) randomSleep(interval time.Duration) { r := time.Duration(sw.rng.Int63n(dialRandomizerIntervalMilliseconds)) * time.Millisecond time.Sleep(r + interval) } //------------------------------------------------------------------------------------ // Connection filtering // FilterConnByAddr returns an error if connecting to the given address is forbidden. func (sw *Switch) FilterConnByAddr(addr net.Addr) error { if sw.filterConnByAddr != nil { return sw.filterConnByAddr(addr) } return nil } // FilterConnByID returns an error if connecting to the given peer ID is forbidden. func (sw *Switch) FilterConnByID(id ID) error { if sw.filterConnByID != nil { return sw.filterConnByID(id) } return nil } // SetAddrFilter sets the function for filtering connections by address. func (sw *Switch) SetAddrFilter(f func(net.Addr) error) { sw.filterConnByAddr = f } // SetIDFilter sets the function for filtering connections by peer ID. func (sw *Switch) SetIDFilter(f func(ID) error) { sw.filterConnByID = f } //------------------------------------------------------------------------------------ func (sw *Switch) listenerRoutine(l Listener) { for { inConn, ok := <-l.Connections() if !ok { break } // ignore connection if we already have enough maxPeers := sw.config.MaxNumPeers if maxPeers <= sw.peers.Size() { sw.Logger.Info("Ignoring inbound connection: already have enough peers", "address", inConn.RemoteAddr().String(), "numPeers", sw.peers.Size(), "max", maxPeers) continue } // New inbound connection! err := sw.addInboundPeerWithConfig(inConn, sw.peerConfig) if err != nil { sw.Logger.Info("Ignoring inbound connection: error while adding peer", "address", inConn.RemoteAddr().String(), "err", err) continue } } // cleanup } func (sw *Switch) addInboundPeerWithConfig(conn net.Conn, config *PeerConfig) error { peerConn, err := newInboundPeerConn(conn, config, sw.nodeKey.PrivKey) if err != nil { conn.Close() // peer is nil return err } if err = sw.addPeer(peerConn); err != nil { peerConn.CloseConn() return err } return nil } // dial the peer; make secret connection; authenticate against the dialed ID; // add the peer. func (sw *Switch) addOutboundPeerWithConfig(addr *NetAddress, config *PeerConfig, persistent bool) error { sw.Logger.Info("Dialing peer", "address", addr) peerConn, err := newOutboundPeerConn(addr, config, persistent, sw.nodeKey.PrivKey) if err != nil { sw.Logger.Error("Failed to dial peer", "address", addr, "err", err) return err } if err := sw.addPeer(peerConn); err != nil { sw.Logger.Error("Failed to add peer", "address", addr, "err", err) peerConn.CloseConn() return err } return nil } // addPeer performs the Tendermint P2P handshake with a peer // that already has a SecretConnection. If all goes well, // it starts the peer and adds it to the switch. // NOTE: This performs a blocking handshake before the peer is added. // NOTE: If error is returned, caller is responsible for calling peer.CloseConn() func (sw *Switch) addPeer(pc peerConn) error { addr := pc.conn.RemoteAddr() if err := sw.FilterConnByAddr(addr); err != nil { return err } // NOTE: if AuthEnc==false, we don't have a peerID until after the handshake. // If AuthEnc==true then we already know the ID and could do the checks first before the handshake, // but it's simple to just deal with both cases the same after the handshake. // Exchange NodeInfo on the conn peerNodeInfo, err := pc.HandshakeTimeout(sw.nodeInfo, time.Duration(sw.peerConfig.HandshakeTimeout*time.Second)) if err != nil { return err } peerID := peerNodeInfo.ID() // ensure connection key matches self reported key if pc.config.AuthEnc { connID := pc.ID() if peerID != connID { return fmt.Errorf("nodeInfo.ID() (%v) doesn't match conn.ID() (%v)", peerID, connID) } } // Validate the peers nodeInfo if err := peerNodeInfo.Validate(); err != nil { return err } // Avoid self if sw.nodeKey.ID() == peerID { addr := peerNodeInfo.NetAddress() // remove the given address from the address book if we're added it earlier sw.addrBook.RemoveAddress(addr) // add the given address to the address book to avoid dialing ourselves // again this is our public address sw.addrBook.AddOurAddress(addr) return ErrSwitchConnectToSelf } // Avoid duplicate if sw.peers.Has(peerID) { return ErrSwitchDuplicatePeer } // Filter peer against ID white list if err := sw.FilterConnByID(peerID); err != nil { return err } // Check version, chain id if err := sw.nodeInfo.CompatibleWith(peerNodeInfo); err != nil { return err } peer := newPeer(pc, peerNodeInfo, sw.reactorsByCh, sw.chDescs, sw.StopPeerForError) peer.SetLogger(sw.Logger.With("peer", addr)) peer.Logger.Info("Successful handshake with peer", "peerNodeInfo", peerNodeInfo) // All good. Start peer if sw.IsRunning() { if err = sw.startInitPeer(peer); err != nil { return err } } // Add the peer to .peers. // We start it first so that a peer in the list is safe to Stop. // It should not err since we already checked peers.Has(). if err := sw.peers.Add(peer); err != nil { return err } sw.Logger.Info("Added peer", "peer", peer) return nil } func (sw *Switch) startInitPeer(peer *peer) error { err := peer.Start() // spawn send/recv routines if err != nil { // Should never happen sw.Logger.Error("Error starting peer", "peer", peer, "err", err) return err } for _, reactor := range sw.reactors { reactor.AddPeer(peer) } return nil }