[lwip-devel] [bug #50914] TCP server don't update the ack num

[shilei yu]

URL:
  <http://savannah.nongnu.org/bugs/?50914>

                 Summary: TCP server don't update the ack num
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: kyliuxing
            Submitted on: Tue May  2 11:58:33 2017
                Category: TCP
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: None
            lwIP version: 2.0.0

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Details:

I met a issue when made TCP test. I built a TCP server on PC and make my
device to connect it, they sent data to each other.
>From the capture of PC(TCP server), firstly, device send seq 6825983(len 1447
,line 4139), PC ack 6827430, but device may be not receive the ack, so device
retransmit seq 6825983(len 1457), the len is larger. then the PC still ack
6827430 and the lwip stack retransmit 6825983(len 1457 ,line 4155), until
reached max retry times.
Why the PC won't ack the added 10 bytes?
Once the PC's ack num is between seq and seq+len, lwip stack will retransmit
the whole segment, but PC won't update the ack num.
The attachment is uart_log of device(client) and wireshark cpature of
PC(server), you can refer the line 4139 and line 4155 in
Wireshark_server.pcap.
by the way, i'm not sure of my lwip version, but the file CHANGELOG include 
"2016-07-27: Simon Goldschmidt * opt.h, timeouts.h/.c: added
LWIP_TIMERS_CUSTOM to override the default implementation of timeouts"
Thank you!



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File Attachments:


-------------------------------------------------------
Date: Tue May  2 11:58:33 2017  Name: UART_client.log  Size: 2MB   By:
kyliuxing
uart_log of device(client) and wireshark cpature of PC(server)
<http://savannah.nongnu.org/bugs/download.php?file_id=40555>
-------------------------------------------------------
Date: Tue May  2 11:58:33 2017  Name: Wireshark_server.pcap  Size: 2MB   By:
kyliuxing
uart_log of device(client) and wireshark cpature of PC(server)
<http://savannah.nongnu.org/bugs/download.php?file_id=40556>

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