We develope local vpn service. which developes own TCP network stack.
While network stack pushing packets into NEPacketTunnelFlow, we found some very odd behavior from apps.
Huge Window size
The window size that recived from app seems very huge, unlike other OS(like Android, Windows)
Calculated window size that we recived from Safari was almsot 2MBs
Dropped Packets
For unknown reasons, the app is dropping packets even we didn't sent over (even less than half) window size.
event the packet we sent over the window size. but app still does not emit any Zero-Windows. just dropping packets and sending dup-ACK
Have any ideas from this issues?
The testing environment was
iOS Version : 13.1.3
Device : IPhone XS Max
