[lwip-users] tcp receive queue size at socket layer...

[Frédéric BERNON]

Hi group,

In my device, I use lwip 1.1.1 (updated with last CVS release) with several 
sockets. One of them is a TCP socket sending large packets. This socket 
exchange datas with its peer, using a protocol like "server send a packet, 
client send a packet, server send a packet, etc...". The server (lwip) doesn't 
really need the client's packets. So I only do "n" recv()- in one time - after 
"n" send() - to reduce potential recv() delays. But it seems that I "block" the 
stack if "n" is too big : no ping answer, even other udp tasks don't reply to 
my requests, etc...

Can you confirm me that one socket which don't do any recv() - but packets are 
send to this socket - can "consume" all internals packets/memory/resources and 
so, can block other sockets (or do a deny of service like with ICMP)? If it's 
true (and with what I know about lwip, I'm sure at 90% it's true), is there any 
feature or patch (with socket layer) to give a limit to socket receive queue 
size (to drop input packets when this queue is "full")? 

With Microsoft winsock, it's possible to give a limit to recv queue size with 
SO_RCVBUF option. Is anyone already implement something like that?

Thank you about your ideas...

And Happy Halloween !!!!
 
  
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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 
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