Re: [lwip-users]lwip and DHCP

[Kieran Mansley]

On Wed, 2009-09-23 at 14:52 +0200, Bob Brusa wrote:
> Hi
> Further to my problem report "problem with recent port of lwip" I have  
> found the that most probably there is something wrong with the checksum  
> calculation of the incoming DHCPoffer. From the debug-output I see that  
> lwip combines several fragments and then comes up with a checksum error.  
> It drops the packet and DHCP remains without success.
> 
> I attach the "erroneous" packet as seen by wireshark (txt-mode)  
> 090923_xx_1.out and an excerpt of the debug output of the lwip-stack  
> 090922_3.txt. As the name might make you think - the packages are not of  
> the same session. But the picture does not change.
> Can somebody guide me how to fix this problem? Just a few words where this  
> calculation in the code is done. Thanks and best regards.
>    Robert

Have you considered getting wireshark to validate the checksum?  In the
trace you provide you've got checksum validation disabled.

Kieran