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6.3 KiB

package p2p
import (
"bytes"
"errors"
"fmt"
"math/rand"
"reflect"
"time"
. "github.com/tendermint/go-common"
wire "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.Start()
go pexR.ensurePeersRoutine()
return nil
}
func (pexR *PEXReactor) OnStop() {
pexR.BaseReactor.OnStop()
pexR.book.Stop()
}
// 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, false)
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)
}