enable TCP keepalives

tcp.go

@@ -33,6 +33,20 @@ func tryLinger(conn net.Conn, sec int) {
 	}
 }
 
+func tryKeepAlive(conn net.Conn, keepAlive bool) {
+	type canKeepAlive interface {
+		SetKeepAlive(bool) error
+	}
+
+	var _ canKeepAlive = &net.TCPConn{}
+
+	if keepALiveConn, ok := conn.(canKeepAlive); ok {
+		if err := keepALiveConn.SetKeepAlive(keepAlive); err != nil {
+			log.Warnf("Failed to enable TCP keepalive: %s", err)
+		}
+	}
+}
+
 type lingerListener struct {
 	manet.Listener
 	sec int
@@ -44,6 +58,7 @@ func (ll *lingerListener) Accept() (manet.Conn, error) {
 		return nil, err
 	}
 	tryLinger(c, ll.sec)
+	tryKeepAlive(c, true)
 	return c, nil
 }
 
@@ -106,6 +121,7 @@ func (t *TcpTransport) Dial(ctx context.Context, raddr ma.Multiaddr, p peer.ID)
 	// linger is 0, connections are _reset_ instead of closed with a FIN.
 	// This means we can immediately reuse the 5-tuple and reconnect.
 	tryLinger(conn, 0)
+	tryKeepAlive(conn, true)
 	return t.Upgrader.UpgradeOutbound(ctx, t, conn, p)
 }