[lwip-users] unsent_oversize mismatch vs. unexpected RST

[Jan Menzel]

Hi All!
        Currently I'm trying to finalize a data logger application based on
LwIP 1.4.1 and FreeRTOS 8.1.2 on LPC1768 with NXPs lpc17xx_40xx_emac as
low-level driver. Everything runs smooth so far with one exception: if
the logger has collected a larger amount of data and tries to stream it,
the "unsent_oversize mismatch" assert from tcp_out.c line 444 hits. I've
googled around and found, that this is a know problem with a related
bug-report and a fix in the current git master. So I pulled the git
master and integrated it. This seems to solves the "unsent_oversize
mismatch" issue, but raises occasional RST packets. According to
wireshark the stack occasionally sends out a RST packet followed by a
series of retransmissions, which are obviously not answered by the other
end.
        Can anyone please advice how this can be handled?
        In the postings and discussions related to the "unsent_oversize
mismatch" bug reports changing the TCP_OVERSIZE define was suggested.
I've tried this, but unfortunately everything except the default breaks
my application. I can't connect because the TLS handshake does not
finish and without no data is send. This is likely not a LwIP related
issue. (I'm using PolarSSL which interfaces LwIPs socket layer. Some
packets are exchanged but the key exchange does not finish)

        Best regards
                Jan