package p2p import ( "bytes" "errors" "fmt" "math/rand" "reflect" "time" . "github.com/tendermint/go-common" "github.com/tendermint/go-wire" ) var pexErrInvalidMessage = errors.New("Invalid PEX message") const ( PexChannel = byte(0x00) ensurePeersPeriodSeconds = 30 minNumOutboundPeers = 10 maxPexMessageSize = 1048576 // 1MB ) /* PEXReactor handles PEX (peer exchange) and ensures that an adequate number of peers are connected to the switch. */ type PEXReactor struct { BaseReactor sw *Switch book *AddrBook } func NewPEXReactor(book *AddrBook) *PEXReactor { pexR := &PEXReactor{ book: book, } pexR.BaseReactor = *NewBaseReactor(log, "PEXReactor", pexR) return pexR } func (pexR *PEXReactor) OnStart() error { pexR.BaseReactor.OnStart() pexR.book.OnStart() go pexR.ensurePeersRoutine() return nil } func (pexR *PEXReactor) OnStop() { pexR.BaseReactor.OnStop() pexR.book.OnStop() } // Implements Reactor func (pexR *PEXReactor) GetChannels() []*ChannelDescriptor { return []*ChannelDescriptor{ &ChannelDescriptor{ ID: PexChannel, Priority: 1, SendQueueCapacity: 10, }, } } // Implements Reactor func (pexR *PEXReactor) AddPeer(peer *Peer) { // Add the peer to the address book netAddr, err := NewNetAddressString(peer.ListenAddr) if err != nil { // this should never happen log.Error("Error in AddPeer: invalid peer address", "addr", peer.ListenAddr, "error", err) return } if peer.IsOutbound() { if pexR.book.NeedMoreAddrs() { pexR.RequestPEX(peer) } } else { // For inbound connections, the peer is its own source // (For outbound peers, the address is already in the books) pexR.book.AddAddress(netAddr, netAddr) } } // Implements Reactor func (pexR *PEXReactor) RemovePeer(peer *Peer, reason interface{}) { // TODO } // Implements Reactor // Handles incoming PEX messages. func (pexR *PEXReactor) Receive(chID byte, src *Peer, msgBytes []byte) { // decode message _, msg, err := DecodeMessage(msgBytes) if err != nil { log.Warn("Error decoding message", "error", err) return } log.Notice("Received message", "msg", msg) switch msg := msg.(type) { case *pexRequestMessage: // src requested some peers. // TODO: prevent abuse. pexR.SendAddrs(src, pexR.book.GetSelection()) case *pexAddrsMessage: // We received some peer addresses from src. // TODO: prevent abuse. // (We don't want to get spammed with bad peers) srcAddr := src.Connection().RemoteAddress for _, addr := range msg.Addrs { if addr != nil { pexR.book.AddAddress(addr, srcAddr) } } default: log.Warn(Fmt("Unknown message type %v", reflect.TypeOf(msg))) } } // Asks peer for more addresses. func (pexR *PEXReactor) RequestPEX(peer *Peer) { peer.Send(PexChannel, struct{ PexMessage }{&pexRequestMessage{}}) } func (pexR *PEXReactor) SendAddrs(peer *Peer, addrs []*NetAddress) { peer.Send(PexChannel, struct{ PexMessage }{&pexAddrsMessage{Addrs: addrs}}) } // Ensures that sufficient peers are connected. (continuous) func (pexR *PEXReactor) ensurePeersRoutine() { // Randomize when routine starts time.Sleep(time.Duration(rand.Int63n(500*ensurePeersPeriodSeconds)) * time.Millisecond) // fire once immediately. pexR.ensurePeers() // fire periodically timer := NewRepeatTimer("pex", ensurePeersPeriodSeconds*time.Second) FOR_LOOP: for { select { case <-timer.Ch: pexR.ensurePeers() case <-pexR.Quit: break FOR_LOOP } } // Cleanup timer.Stop() } // Ensures that sufficient peers are connected. (once) func (pexR *PEXReactor) ensurePeers() { numOutPeers, _, numDialing := pexR.Switch.NumPeers() numToDial := minNumOutboundPeers - (numOutPeers + numDialing) log.Info("Ensure peers", "numOutPeers", numOutPeers, "numDialing", numDialing, "numToDial", numToDial) if numToDial <= 0 { return } toDial := NewCMap() // Try to pick numToDial addresses to dial. // TODO: improve logic. for i := 0; i < numToDial; i++ { newBias := MinInt(numOutPeers, 8)*10 + 10 var picked *NetAddress // Try to fetch a new peer 3 times. // This caps the maximum number of tries to 3 * numToDial. for j := 0; j < 3; j++ { try := pexR.book.PickAddress(newBias) if try == nil { break } alreadySelected := toDial.Has(try.IP.String()) alreadyDialing := pexR.Switch.IsDialing(try) alreadyConnected := pexR.Switch.Peers().Has(try.IP.String()) if alreadySelected || alreadyDialing || alreadyConnected { /* log.Info("Cannot dial address", "addr", try, "alreadySelected", alreadySelected, "alreadyDialing", alreadyDialing, "alreadyConnected", alreadyConnected) */ continue } else { log.Info("Will dial address", "addr", try) picked = try break } } if picked == nil { continue } toDial.Set(picked.IP.String(), picked) } // Dial picked addresses for _, item := range toDial.Values() { go func(picked *NetAddress) { _, err := pexR.Switch.DialPeerWithAddress(picked) if err != nil { pexR.book.MarkAttempt(picked) } }(item.(*NetAddress)) } // If we need more addresses, pick a random peer and ask for more. if pexR.book.NeedMoreAddrs() { if peers := pexR.Switch.Peers().List(); len(peers) > 0 { i := rand.Int() % len(peers) peer := peers[i] log.Info("No addresses to dial. Sending pexRequest to random peer", "peer", peer) pexR.RequestPEX(peer) } } } //----------------------------------------------------------------------------- // Messages const ( msgTypeRequest = byte(0x01) msgTypeAddrs = byte(0x02) ) type PexMessage interface{} var _ = wire.RegisterInterface( struct{ PexMessage }{}, wire.ConcreteType{&pexRequestMessage{}, msgTypeRequest}, wire.ConcreteType{&pexAddrsMessage{}, msgTypeAddrs}, ) func DecodeMessage(bz []byte) (msgType byte, msg PexMessage, err error) { msgType = bz[0] n := new(int) r := bytes.NewReader(bz) msg = wire.ReadBinary(struct{ PexMessage }{}, r, maxPexMessageSize, n, &err).(struct{ PexMessage }).PexMessage return } /* A pexRequestMessage requests additional peer addresses. */ type pexRequestMessage struct { } func (m *pexRequestMessage) String() string { return "[pexRequest]" } /* A message with announced peer addresses. */ type pexAddrsMessage struct { Addrs []*NetAddress } func (m *pexAddrsMessage) String() string { return fmt.Sprintf("[pexAddrs %v]", m.Addrs) }