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271 lines
6.0 KiB
271 lines
6.0 KiB
package p2p
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import (
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"bytes"
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"errors"
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"fmt"
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"sync/atomic"
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"time"
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"github.com/tendermint/tendermint/binary"
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. "github.com/tendermint/tendermint/common"
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)
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var pexErrInvalidMessage = errors.New("Invalid PEX message")
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const (
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PexCh = byte(0x00)
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ensurePeersPeriodSeconds = 30
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minNumOutboundPeers = 10
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maxNumPeers = 50
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)
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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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*/
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type PEXReactor struct {
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sw *Switch
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quit chan struct{}
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started uint32
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stopped uint32
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book *AddrBook
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}
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func NewPEXReactor(book *AddrBook) *PEXReactor {
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pexR := &PEXReactor{
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quit: make(chan struct{}),
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book: book,
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}
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return pexR
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}
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// Implements Reactor
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func (pexR *PEXReactor) Start(sw *Switch) {
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if atomic.CompareAndSwapUint32(&pexR.started, 0, 1) {
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log.Info("Starting PEXReactor")
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pexR.sw = sw
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go pexR.ensurePeersRoutine()
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}
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}
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// Implements Reactor
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func (pexR *PEXReactor) Stop() {
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if atomic.CompareAndSwapUint32(&pexR.stopped, 0, 1) {
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log.Info("Stopping PEXReactor")
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close(pexR.quit)
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}
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}
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// Implements Reactor
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func (pexR *PEXReactor) GetChannels() []*ChannelDescriptor {
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return []*ChannelDescriptor{
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&ChannelDescriptor{
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Id: PexCh,
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Priority: 1,
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},
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}
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}
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// Implements Reactor
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func (pexR *PEXReactor) AddPeer(peer *Peer) {
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if peer.IsOutbound() {
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pexR.SendAddrs(peer, pexR.book.OurAddresses())
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if pexR.book.NeedMoreAddrs() {
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pexR.RequestPEX(peer)
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}
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}
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}
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// Implements Reactor
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func (pexR *PEXReactor) RemovePeer(peer *Peer, reason interface{}) {
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// TODO
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}
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// Implements Reactor
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// Handles incoming PEX messages.
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func (pexR *PEXReactor) Receive(chId byte, src *Peer, msgBytes []byte) {
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// decode message
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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.Info("Received message", "msg", msg)
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switch msg.(type) {
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case *pexHandshakeMessage:
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chainId := msg.(*pexHandshakeMessage).ChainId
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if chainId != pexR.sw.chainId {
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err := fmt.Sprintf("Peer is on a different chain/network. Got %s, expected %s", chainId, pexR.sw.chainId)
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pexR.sw.StopPeerForError(src, err)
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}
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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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addrs := pexR.book.GetSelection()
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msg := &pexAddrsMessage{Addrs: addrs}
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queued := src.TrySend(PexCh, msg)
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if !queued {
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// ignore
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}
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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.(*pexAddrsMessage).Addrs {
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pexR.book.AddAddress(addr, srcAddr)
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}
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default:
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// Ignore unknown message.
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}
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}
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// Asks peer for more addresses.
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func (pexR *PEXReactor) RequestPEX(peer *Peer) {
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peer.TrySend(PexCh, &pexRequestMessage{})
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}
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func (pexR *PEXReactor) SendAddrs(peer *Peer, addrs []*NetAddress) {
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peer.Send(PexCh, &pexAddrsMessage{Addrs: addrs})
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}
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// Ensures that sufficient peers are connected. (continuous)
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func (pexR *PEXReactor) ensurePeersRoutine() {
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// fire once immediately.
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pexR.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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pexR.ensurePeers()
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case <-pexR.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 (pexR *PEXReactor) ensurePeers() {
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numOutPeers, _, numDialing := pexR.sw.NumPeers()
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numToDial := minNumOutboundPeers - (numOutPeers + numDialing)
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log.Debug("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 := pexR.book.PickAddress(newBias)
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if try == nil {
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break
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}
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if toDial.Has(try.String()) ||
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pexR.sw.IsDialing(try) ||
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pexR.sw.Peers().Has(try.String()) {
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continue
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} else {
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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.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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picked := item.(*NetAddress)
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go func() {
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_, err := pexR.sw.DialPeerWithAddress(picked)
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if err != nil {
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pexR.book.MarkAttempt(picked)
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}
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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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msgTypeUnknown = byte(0x00)
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msgTypeRequest = byte(0x01)
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msgTypeAddrs = byte(0x02)
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msgTypeHandshake = byte(0x03)
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)
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// TODO: check for unnecessary extra bytes at the end.
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func DecodeMessage(bz []byte) (msg interface{}, err error) {
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n := new(int64)
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msgType := bz[0]
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r := bytes.NewReader(bz)
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// log.Debug(Fmt("decoding msg bytes: %X", bz))
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switch msgType {
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case msgTypeHandshake:
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msg = binary.ReadBinary(&pexHandshakeMessage{}, r, n, &err)
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case msgTypeRequest:
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msg = &pexRequestMessage{}
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case msgTypeAddrs:
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msg = binary.ReadBinary(&pexAddrsMessage{}, r, n, &err)
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default:
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msg = nil
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}
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return
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}
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/*
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A pexHandshakeMessage contains the peer's chainId
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*/
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type pexHandshakeMessage struct {
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ChainId string
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}
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func (m *pexHandshakeMessage) TypeByte() byte { return msgTypeHandshake }
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func (m *pexHandshakeMessage) String() string {
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return "[pexHandshake]"
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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) TypeByte() byte { return msgTypeRequest }
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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) TypeByte() byte { return msgTypeAddrs }
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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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