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