p2p: fix conn leak. part of #2046

CHANGELOG.md

@@ -10,7 +10,11 @@ BUG FIXES
     - (#2049) Fix OOM attack by returning error on negative input
     - Fix result length to have max 20 (instead of 21) block metas
 - [rpc] Validate height is non-negative in `/abci_query`
-- [Gopkg] Fix versions in the toml
+- [consensus] (#2050) Include evidence in proposal block parts (previously evidence was
+  not being included in blocks!)
+- [p2p] (#2046) Close rejected inbound connections so file descriptor doesn't
+  leak
+- [Gopkg] (#2053) Fix versions in the toml
 
 ## 0.22.5
 

p2p/listener.go

@@ -151,7 +151,7 @@ func (l *DefaultListener) OnStop() {
 	l.listener.Close() // nolint: errcheck
 }
 
-// Accept connections and pass on the channel
+// Accept connections and pass on the channel.
 func (l *DefaultListener) listenRoutine() {
 	for {
 		conn, err := l.listener.Accept()
@@ -178,6 +178,8 @@ func (l *DefaultListener) listenRoutine() {
 
 // Connections returns a channel of inbound connections.
 // It gets closed when the listener closes.
+// It is the callers responsibility to close any connections received
+// over this channel.
 func (l *DefaultListener) Connections() <-chan net.Conn {
 	return l.connections
 }

p2p/switch.go

@@ -496,6 +496,7 @@ func (sw *Switch) listenerRoutine(l Listener) {
 		maxPeers := sw.config.MaxNumPeers - DefaultMinNumOutboundPeers
 		if maxPeers <= sw.peers.Size() {
 			sw.Logger.Info("Ignoring inbound connection: already have enough peers", "address", inConn.RemoteAddr().String(), "numPeers", sw.peers.Size(), "max", maxPeers)
+			inConn.Close()
 			continue
 		}
 
@@ -510,6 +511,7 @@ func (sw *Switch) listenerRoutine(l Listener) {
 	// cleanup
 }
 
+// closes conn if err is returned
 func (sw *Switch) addInboundPeerWithConfig(
 	conn net.Conn,
 	config *config.P2PConfig,