Add logging for symmetric reply send path

magicbind.go

@@ -286,6 +286,12 @@ func (b *MagicBind) Send(bufs [][]byte, ep conn.Endpoint) error {
 		dm := b.disco
 		b.mu.Unlock()
 		if dm != nil {
+			wgType := byte(0)
+			if len(bufs) > 0 && len(bufs[0]) >= 4 {
+				wgType = bufs[0][0]
+			}
+			b.logf("magicbind: send WG type=%d via symmetric reply to %s (peer %s)",
+				wgType, me.lastRecv, me.dstKey.ShortString())
 			for _, buf := range bufs {
 				dm.SendUDP(me.lastRecv, buf)
 			}