Reintroduce torrent-wide PEX throttling

https://github.com/anacrolix/torrent/discussions/836

diff --git a/pex.go b/pex.go
index 4770f3d3bbf7f1804d66f33b8c230207092d9a3c..a0a5f49f5babfb54a2ca11b532d7a017babf4bb8 100644 (file)
--- a/pex.go
+++ b/pex.go
@@ -4,6 +4,7 @@ import (
        "net"
        "net/netip"
        "sync"
+       "time"
 
        pp "github.com/anacrolix/torrent/peer_protocol"
 )
@@ -144,8 +145,11 @@ func (me *pexMsgFactory) PexMsg() *pp.PexMsg {
 // Per-torrent PEX state
 type pexState struct {
        sync.RWMutex
-       tail *pexEvent     // event feed list
-       hold []pexEvent    // delayed drops
+       tail *pexEvent  // event feed list
+       hold []pexEvent // delayed drops
+       // Torrent-wide cooldown deadline on inbound. This exists to prevent PEX from drowning out other
+       // peer address sources, until that is fixed.
+       rest time.Time
        nc   int           // net number of alive conns
        msg0 pexMsgFactory // initial message
 }
@@ -157,6 +161,7 @@ func (s *pexState) Reset() {
        s.tail = nil
        s.hold = nil
        s.nc = 0
+       s.rest = time.Time{}
        s.msg0 = pexMsgFactory{}
 }
 

diff --git a/pexconn.go b/pexconn.go
index 2f7e7df08d110eae7c5a15d28ba4a45c43323680..9254f5e1876c15ceff293d9f37c687d004d73b5c 100644 (file)
--- a/pexconn.go
+++ b/pexconn.go
@@ -143,9 +143,17 @@ func (s *pexConnState) Recv(payload []byte) error {
        var peers peerInfos
        peers.AppendFromPex(rx.Added6, rx.Added6Flags)
        peers.AppendFromPex(rx.Added, rx.AddedFlags)
+       if time.Now().Before(s.torrent.pex.rest) {
+               s.dbg.Printf("in cooldown period, incoming PEX discarded")
+               return nil
+       }
        added := s.torrent.addPeers(peers)
        s.dbg.Printf("got %v peers over pex, added %v", len(peers), added)
 
+       if len(peers) > 0 {
+               s.torrent.pex.rest = time.Now().Add(pexInterval)
+       }
+
        // one day we may also want to:
        // - handle drops somehow
        // - detect malicious peers