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265 lines
5.6 KiB
265 lines
5.6 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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"io"
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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 := decodeMessage(msgBytes)
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log.Info("requestRoutine received %v", msg)
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switch 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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addrs := pexR.book.GetSelection()
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msg := &pexRddrsMessage{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 *pexRddrsMessage:
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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.RemoteAddress()
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for _, addr := range msg.(*pexRddrsMessage).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, &pexRddrsMessage{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(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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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; i < 3; j++ {
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picked = pexR.book.PickAddress(newBias)
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if picked == nil {
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return
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}
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if toDial.Has(picked.String()) ||
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pexR.sw.IsDialing(picked) ||
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pexR.sw.Peers().Has(picked.String()) {
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continue
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} else {
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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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)
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// TODO: check for unnecessary extra bytes at the end.
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func decodeMessage(bz []byte) (msg interface{}) {
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var n int64
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var err error
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// log.Debug("decoding msg bytes: %X", bz)
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switch bz[0] {
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case msgTypeRequest:
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return &pexRequestMessage{}
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case msgTypeAddrs:
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return readPexAddrsMessage(bytes.NewReader(bz[1:]), &n, &err)
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default:
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return nil
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}
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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) WriteTo(w io.Writer) (n int64, err error) {
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WriteByte(w, msgTypeRequest, &n, &err)
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return
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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 pexRddrsMessage struct {
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Addrs []*NetAddress
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}
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func readPexAddrsMessage(r io.Reader, n *int64, err *error) *pexRddrsMessage {
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numAddrs := int(ReadUInt32(r, n, err))
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addrs := []*NetAddress{}
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for i := 0; i < numAddrs; i++ {
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addr := ReadNetAddress(r, n, err)
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addrs = append(addrs, addr)
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}
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return &pexRddrsMessage{
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Addrs: addrs,
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}
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}
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func (m *pexRddrsMessage) WriteTo(w io.Writer) (n int64, err error) {
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WriteByte(w, msgTypeAddrs, &n, &err)
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WriteUInt32(w, uint32(len(m.Addrs)), &n, &err)
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for _, addr := range m.Addrs {
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WriteBinary(w, addr, &n, &err)
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}
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return
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}
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func (m *pexRddrsMessage) String() string {
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return fmt.Sprintf("[pexRddrs %v]", m.Addrs)
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}
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