[lwip-devel] [bug #25940] Regarding the Fragmentation issue in the ICMP packet.

[Arun]

URL:
  <http://savannah.nongnu.org/bugs/?25940>

                 Summary: Regarding the Fragmentation issue in the ICMP
packet.
                 Project: lwIP - A Lightweight TCP/IP stack
            Submitted by: arun_rh
            Submitted on: Fri 20 Mar 2009 03:45:28 PM GMT
                Category: None
                Severity: 3 - Normal
              Item Group: Faulty Behaviour
                  Status: None
                 Privacy: Public
             Assigned to: None
             Open/Closed: Open
         Discussion Lock: Any
         Planned Release: 
            lwIP version: 1.3.0

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Details:

Hello All, 
Currently I am working on the LWIP stack, which we have ported on to the
STR912 processor. 
Actually I am facing a strange problem of reassembling process of Fragmented
ICMP packet. 
My observation was the ping utility is failing at higher packet size (more
than 1472 ) say1500. 
But the same works if we send the ping command less than 1472. 
So I understand that when ever we send the ping command with more than 1472
bytes, it basically splits the packet into and the same Is reassembled on the
LWIP stack. I saw the sender sends the ping command with fragmented messages.


These fragmented messages are received on the STR912 that is our target where
the LWIP stack will be running. 

So the LWIP while in the process of reassembling it is going to some Assert
statement. Actually it is going to some assert statement in pbuf_header()
function in the pbuf.c file and the code is 

if (header_size_increment < 0){

    increment_magnitude = -header_size_increment;

    /* Check that we aren't going to move off the end of the pbuf */

    LWIP_ERROR("increment_magnitude <= p->len", (increment_magnitude <=
p->len), return 1;);

  }  

I have seen one of the mail asking the same question for the solution in
2006. So could u please suggest me whether the issue of reassembling process
and the fragmentation is fixed or not. Currently I am using the 1.0.3 version.
Does the LWIP stack is tested with the Ping utility with more than 10000 bytes
? 
 

Thanks 

With Regards

Arun Honnappa





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