130 lines
3.0 KiB
Go
130 lines
3.0 KiB
Go
package torrent
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import (
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"fmt"
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"time"
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"github.com/anacrolix/log"
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pp "github.com/anacrolix/torrent/peer_protocol"
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)
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const (
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pexRetryDelay = 10 * time.Second
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pexInterval = 1 * time.Minute
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)
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// per-connection PEX state
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type pexConnState struct {
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enabled bool
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xid pp.ExtensionNumber
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seq int
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timer *time.Timer
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gate chan struct{}
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readyfn func()
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torrent *Torrent
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Listed bool
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info log.Logger
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dbg log.Logger
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}
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func (s *pexConnState) IsEnabled() bool {
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return s.enabled
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}
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// Init is called from the reader goroutine upon the extended handshake completion
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func (s *pexConnState) Init(c *PeerConn) {
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xid, ok := c.PeerExtensionIDs[pp.ExtensionNamePex]
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if !ok || xid == 0 || c.t.cl.config.DisablePEX {
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return
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}
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s.xid = xid
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s.seq = 0
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s.torrent = c.t
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s.info = c.t.cl.logger.WithDefaultLevel(log.Info)
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s.dbg = c.logger.WithDefaultLevel(log.Debug)
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s.readyfn = c.tickleWriter
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s.gate = make(chan struct{}, 1)
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s.timer = time.AfterFunc(0, func() {
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s.gate <- struct{}{}
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s.readyfn() // wake up the writer
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})
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s.enabled = true
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}
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// schedule next PEX message
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func (s *pexConnState) sched(delay time.Duration) {
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s.timer.Reset(delay)
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}
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// generate next PEX message for the peer; returns nil if nothing yet to send
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func (s *pexConnState) genmsg() *pp.PexMsg {
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tx, seq := s.torrent.pex.Genmsg(s.seq)
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if tx.Len() == 0 {
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return nil
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}
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s.seq = seq
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return &tx
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}
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// Share is called from the writer goroutine if when it is woken up with the write buffers empty
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// Returns whether there's more room on the send buffer to write to.
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func (s *pexConnState) Share(postfn messageWriter) bool {
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select {
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case <-s.gate:
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if tx := s.genmsg(); tx != nil {
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s.dbg.Print("sending PEX message: ", tx)
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flow := postfn(tx.Message(s.xid))
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s.sched(pexInterval)
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return flow
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} else {
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// no PEX to send this time - try again shortly
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s.sched(pexRetryDelay)
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}
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default:
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}
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return true
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}
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// Recv is called from the reader goroutine
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func (s *pexConnState) Recv(payload []byte) error {
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if !s.torrent.wantPeers() {
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s.dbg.Printf("peer reserve ok, incoming PEX discarded")
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return nil
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}
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if time.Now().Before(s.torrent.pex.rest) {
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s.dbg.Printf("in cooldown period, incoming PEX discarded")
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return nil
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}
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rx, err := pp.LoadPexMsg(payload)
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if err != nil {
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return fmt.Errorf("error unmarshalling PEX message: %s", err)
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}
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s.dbg.Print("incoming PEX message: ", rx)
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torrent.Add("pex added peers received", int64(len(rx.Added)))
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torrent.Add("pex added6 peers received", int64(len(rx.Added6)))
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var peers peerInfos
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peers.AppendFromPex(rx.Added6, rx.Added6Flags)
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peers.AppendFromPex(rx.Added, rx.AddedFlags)
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s.dbg.Printf("adding %d peers from PEX", len(peers))
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if len(peers) > 0 {
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s.torrent.pex.rest = time.Now().Add(pexInterval)
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s.torrent.addPeers(peers)
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}
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// one day we may also want to:
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// - check if the peer is not flooding us with PEX updates
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// - handle drops somehow
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// - detect malicious peers
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return nil
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}
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func (s *pexConnState) Close() {
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if s.timer != nil {
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s.timer.Stop()
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}
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}
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