[lwip-users] Socket-Interface: Problem receiving segmented data of HTTP POST requests.

[Ostendorf, Rainer]

Hi everybody,

i am quite new to LwIP and currently trying to use it for a webserver 
application running on an AVR32 UC3A Board with FreeRTOS (similar to Atmel 
EVK1100 Eva-Board).

Based on the example provided by Atmel i managed to write a webserver for 
accessing files on a SD-Card. That server uses the socket interface of LwIP and 
works fine so far.

For a firmware update functionality, i now wanted to add support for HTTP POST 
requests, containing a file as MIME multipart.

Now the following problem occurs: After establishing the socket 
(SYN,SYN+ACK,ACK), the webbrowser sends the first request containing the HTTP 
header of the POST-request to my webserver (Lenght: 1024). 

That packet gets acked and the webbrowser sends the next packet containing 1024 
bytes payload. 

This second packet then ist answered with FIN,ACK, so the connection is closed 
by the webserver, before the data is transmitted completely.

As i am not that familiar with LwIP so far, i have no idea what could be the 
reason for this behavior. Maybe the IP stack ran out of buffer space after 
receiving 2x1024 Bytes? I tried increasing some defines in lwipopts.h, but that 
resulted in no different behavior.

Attached you find a wirshark pcap dump of the POST request. What further 
information would be helpful for getting this solved?

Any help would be greatly appreciated,
Rainer

wiresharkdump.pcap
Description: wiresharkdump.pcap