[lwip-users] Re: [lwip] Handling fragmented IP packets

[Adam Dunkels]

Hi Vishy!

On Saturday 09 February 2002 14.30, you wrote:
>  As I have written already that I have to handle the fragmented IP
> packets.
>      As I have understood each packet will be held in pbuf struct, and
>      payload will be
>      pointing to the packet. When a fragmented ip packet arrives, the
>      ehternet layer will
>      allocate a pbuf as usual and pass it to ip layer. In ip_input(), I
> want
>      to assemble all the
>      fragments and make one single ip packet. As the fragmented IP
> packets
>      will be small
>      can I use pbuf_realloc() to assemble fragmented ip packets.
>      Will this work out.
>      Please let me know that am making sence, and correct me if am
> wrong.

It isn't possible to just use pbuf_realloc() to reassemble IP fragments. It 
requires some parsing a IP header fields and buffering of incoming IP 
fragments. There is a rudimentary implementation of IP reassembly in the 
current CVS version (in the file src/core/ipv4/ip.c) that you might look at.

/adam
-- 
Adam Dunkels <address@hidden>
http://www.sics.se/~adam
[This message was sent through the lwip discussion list.]