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Re: [lwip-users] ACK missing after SYN, strange high Ack Num
From: |
Indan Zupancic |
Subject: |
Re: [lwip-users] ACK missing after SYN, strange high Ack Num |
Date: |
Tue, 07 Jun 2022 16:52:49 +0200 |
User-agent: |
Roundcube Webmail/1.3.16 |
Hello Jochen,
On 2022-06-07 15:55, Jochen Strohbeck wrote:
In Wireshark I see that after the data transfer the client sends out
FIN+ACK and the http server responds only with ACK, no further FIN sent
out by the server.
This is normal if the server hasn't sent all data yet. I would expect
it to send more data and to set FIN on the last packet. If it doesn't
then it's a bug in the server.
Is this considered a 'half closed connection'?
Yes.
Do you think the server also close the connection too in order to avoid
the RST on a 'pending connection'?
If the client is starting a new connection while it didn't receive
a FIN for the previous connection yet, then I'd say that's a bug in
the network stack on the client side.
The problem is that the client application gets an CONNECTION_TIMEOUT
error if RST happens.
How to distinguish the 'RST on pending connection' from a 'server
unreachable' error?
Use a better OS? (I assume you meant 'Connection timed out' error.)
Look, if you OS resets a connection and forgets about it, and then
re-used
the port for a new connection, that will get reset and it better
silently
retry with a different random port instead of bothering the application
with a bogus error.
Just retry in your application on CONNECTION_TIMEOUT errors and it
should
work, there's not much else you can do. If there's a real timeout the
user
would have gotten impatient way before it triggered, otherwise they want
to keep trying.
Greetings,
Indan
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Jochen Strohbeck, 2022/06/01
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Indan Zupancic, 2022/06/01
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Jochen Strohbeck, 2022/06/01
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Indan Zupancic, 2022/06/01
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Jochen Strohbeck, 2022/06/02
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Indan Zupancic, 2022/06/02
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num, Jochen Strohbeck, 2022/06/07
- Re: [lwip-users] ACK missing after SYN, strange high Ack Num,
Indan Zupancic <=