To disable Nagle algorithm at socket layer, call:
int iValue = 1;
setsockopt( hSocket, IPPROTO_TCP, TCP_NODELAY, (char*)&iValue,
sizeof(iValue));
On your socket
====================================
Frédéric BERNON HYMATOM SA Chef de projet informatique Microsoft Certified
Professional Tél. : +33 (0)4-67-87-61-10 Fax. : +33 (0)4-67-70-85-44 Email
: address@hidden Web Site : http://www.hymatom.fr
====================================
P Avant d'imprimer, penser à l'environnement
-----Message d'origine-----
De : Winformatik Info [mailto:address@hidden Envoyé : mercredi 22
août 2007 11:49
À : Frédéric BERNON
Objet : Re: RE : [lwip-users] Problem with socket send()
Hi Frederic
Your suggestion with the nagle algorithm... I do not understand this right
now. Could you please explain this in a few words (or better a short
example). Thank you.
Your right.. The example (in pseudo code) is wrong it should be (It was
very late last night ;-) ):
send(SmtpState.iSocket, "abcdefgh", 8, 0); // Send_0
send(SmtpState.iSocket, "01234", 5, 0); // Send_1 send(SmtpState.iSocket,
"ABCDEF", 6, 0); // Send_2
I looks like:
"abdcdefgh01234 ABCDEF" instead of "abdcdefgh01234ABCDEF"
This does not mean a SPACE is send, it could be any other value (in the
range of byte). I used it only for the example.
BTW: I will also do so like Kieran suggested in his email. But give me
some time... because I 'm very busy on an other project.
Kind regards
Roland
Frédéric BERNON schrieb:
Hi,
Can you disable the nagle algorithm to be sure? (in this case, you should
also have 3 frames, but, if the problem is in segment concatenation, you
should got good datas)
About your sample, since you write :
send(SmtpState.iSocket, "012345", 5, 0); // Send_1
You should got "abdcdefgh01234ABCDEF" (without the "5"). Right?
====================================
Frédéric BERNON
HYMATOM SA Chef de projet informatique Microsoft Certified Professional
Tél. : +33 (0)4-67-87-61-10 Fax. : +33 (0)4-67-70-85-44 Email :
address@hidden Web Site : http://www.hymatom.fr
====================================
P Avant d'imprimer, penser à l'environnement
-----Message d'origine-----
De : address@hidden
[mailto:address@hidden De la
part de Winformatik Info Envoyé : mercredi 22 août 2007 10:15 À : Mailing
list for lwIP users Objet : [lwip-users] Problem with socket send()
Hi
I have written a SMTP client and used the socket programming. I did the
programming with an old version of lwIP (prior 1.20 but newer than
1.10... I think). With this version the SMTO client works like expected.
After switching to the latest CVS HEAD the SMTP client does not work well
any more.
The problem happens if the SMTP code calls 3 times the send() function,
one after another and only if any of the first two calls of send() is
called with a odd number of bytes to send, like (pseudo code):
send(SmtpState.iSocket, "abcdefgh", 8, 0); // Send_0
send(SmtpState.iSocket, "012345", 5, 0); // Send_1
send(SmtpState.iSocket, "ABCDEF", 6, 0); // Send_2
If the "Send_1" would be called with an even number of bytes the problem
does not occur.
After recording the frames with the Wireshark software. I found, that
the three calls of send() resulting in one frame which is send over the
Ethernet (I use a CS8900 Ethernet chip with 16Bit access). But the data
content of the this frame seems to be wrong. It looks like :
"abdcdefgh012345 ABCDEF" instead of "abdcdefgh012345ABCDEF"
It seems, that the different buffers (or the data inside) used by the
three send() calls are not merged the right way. I tracked down the
problem to the functions tcp_output() and tcp_output_segment(), but the
code is very difficult to understand.
BTW: If I insert a time-out (I use a RTOS) between the send() calls the
data is send correct, of course in separate frames.
I did verified the problem on to different architectures (a H8S and an
ARM7 Hardware; means a 16- and a 32-bit system). The problem is the same
on both systems.
Does somebody have an idea what's going wrong here ? Does somebody could
verify this behaviour ?
Thank you very much for any help.
Kind regards
Roland
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