clamp roundTripTime

protocol.c

@@ -852,6 +852,7 @@ enet_protocol_handle_acknowledge (ENetHost * host, ENetEvent * event, ENetPeer *
       return 0;
 
     roundTripTime = ENET_TIME_DIFFERENCE (host -> serviceTime, receivedSentTime);
+    roundTripTime = ENET_MAX (roundTripTime, 1);
 
     enet_peer_throttle (peer, roundTripTime);