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236 lines
4.9 KiB
236 lines
4.9 KiB
package p2p
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import (
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"bytes"
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"errors"
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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 = "PEX"
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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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PeerManager 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 PeerManager struct {
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sw *Switch
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book *AddrBook
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quit chan struct{}
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started uint32
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stopped uint32
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}
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func NewPeerManager(sw *Switch, book *AddrBook) *PeerManager {
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pm := &PeerManager{
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sw: sw,
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book: book,
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quit: make(chan struct{}),
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}
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return pm
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}
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func (pm *PeerManager) Start() {
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if atomic.CompareAndSwapUint32(&pm.started, 0, 1) {
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log.Info("Starting peerManager")
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go pm.ensurePeersHandler()
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go pm.pexHandler()
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}
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}
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func (pm *PeerManager) Stop() {
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if atomic.CompareAndSwapUint32(&pm.stopped, 0, 1) {
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log.Info("Stopping peerManager")
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close(pm.quit)
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}
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}
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// Ensures that sufficient peers are connected. (continuous)
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func (pm *PeerManager) ensurePeersHandler() {
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// fire once immediately.
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pm.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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pm.ensurePeers()
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case <-pm.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 (pm *PeerManager) ensurePeers() {
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numOutPeers, _, numDialing := pm.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 = pm.book.PickAddress(newBias)
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if picked == nil {
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log.Debug("Empty addrbook.")
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return
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}
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if toDial.Has(picked.String()) ||
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pm.sw.IsDialing(picked) ||
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pm.sw.Peers().Has(picked) {
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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 := pm.sw.DialPeerWithAddress(picked)
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if err != nil {
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pm.book.MarkAttempt(picked)
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}
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}()
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}
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}
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// Handles incoming Pex messages.
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func (pm *PeerManager) pexHandler() {
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for {
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inPkt := pm.sw.Receive(PexCh) // {Peer, Time, Packet}
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if inPkt == nil {
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// Client has stopped
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break
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}
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// decode message
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msg := decodeMessage(inPkt.Bytes)
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log.Info("pexHandler received %v", msg)
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switch msg.(type) {
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case *PexRequestMessage:
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// inPkt.Peer requested some peers.
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// TODO: prevent abuse.
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addrs := pm.book.GetSelection()
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response := &PexAddrsMessage{Addrs: addrs}
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pkt := NewPacket(PexCh, response)
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queued := inPkt.Peer.TrySend(pkt)
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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 inPkt.Peer.
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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 := inPkt.Peer.RemoteAddress()
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for _, addr := range msg.(*PexAddrsMessage).Addrs {
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pm.book.AddAddress(addr, srcAddr)
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}
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default:
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// Bad peer.
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pm.sw.StopPeerForError(inPkt.Peer, pexErrInvalidMessage)
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}
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}
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// Cleanup
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}
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//-----------------------------------------------------------------------------
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/* Messages */
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const (
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pexTypeUnknown = Byte(0x00)
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pexTypeRequest = Byte(0x01)
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pexTypeAddrs = 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 ByteSlice) (msg Message) {
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log.Debug("decoding msg bytes: %X", bz)
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switch Byte(bz[0]) {
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case pexTypeRequest:
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return &PexRequestMessage{}
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case pexTypeAddrs:
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return readPexAddrsMessage(bytes.NewReader(bz[1:]))
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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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// TODO: define NewPexRequestPacket instead?
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func NewPexRequestMessage() *PexRequestMessage {
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return &PexRequestMessage{}
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}
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func (m *PexRequestMessage) WriteTo(w io.Writer) (n int64, err error) {
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n, err = WriteOnto(pexTypeRequest, w, n, err)
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return
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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 readPexAddrsMessage(r io.Reader) *PexAddrsMessage {
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numAddrs := int(ReadUInt32(r))
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addrs := []*NetAddress{}
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for i := 0; i < numAddrs; i++ {
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addr := ReadNetAddress(r)
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addrs = append(addrs, addr)
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}
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return &PexAddrsMessage{
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Addrs: addrs,
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}
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}
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func (m *PexAddrsMessage) WriteTo(w io.Writer) (n int64, err error) {
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n, err = WriteOnto(pexTypeAddrs, w, n, err)
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n, err = WriteOnto(UInt32(len(m.Addrs)), w, n, err)
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for _, addr := range m.Addrs {
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n, err = WriteOnto(addr, w, n, err)
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}
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return
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}
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