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eclipse-threadx / netxduo

Eclipse ThreadX - NetXDuo is an advanced, industrial-grade TCP/IP network stack designed specifically for deeply embedded real-time and IoT applications
https://github.com/eclipse-threadx/rtos-docs/blob/main/rtos-docs/netx-duo/index.md
MIT License
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TCP Fast retransmission due to faulty DUPACK counting #4

Closed MathieuBordere closed 4 years ago

MathieuBordere commented 4 years ago

https://github.com/azure-rtos/netxduo/blob/35a977685463af4b756d5396b9bcb73f33eae9ff/common/src/nx_tcp_socket_state_ack_check.c#L232-L235

If I'm not mistaken the socket_ptr -> nx_tcp_socket_duplicated_ack_received is also increased on segments that contain data, from my understanding a 'real' DUPACK is a pure ACK packet that does not contain data, socket_ptr -> nx_tcp_socket_duplicated_ack_received should therefore only be increased if the segment contains no data. We have observed this behaviour where NetX initiates a fast retransmit without the receiver explicitly signaling packet loss by sending DUPACKs.

yuxin-azrtos commented 4 years ago

@MathieuBordere Thank you for sharing the finding with us. We reviewed the code and I am able to confirm that is an issue in the TCP logic. I have forwarded this information to the NetX team for further analysis the issue and fix it. Feel free to re-open this ticket if you have additional information.

MathieuBordere commented 4 years ago

Is there a way to keep me posted when a fix is issued, or should I seek support through my employer who owns a ThreadX & NetX license?