[Click] Problem with Queue element

[Eddie Kohler]

Ian,

I think this must be a bug in your element; perhaps it requires an IP header 
annotation (by referring to p->ip_header()).  The CheckIPHeader element sets 
that annotation; if you don't set it, it's null.

Eddie

I.E.Pearce-02 at student.lboro.ac.uk wrote:
> Hi Eddie,
> 
> Thanks a lot for the help. That seems to have fixed my problem.
> 
> I was wondering if you could tell me why the below configuration returns a
> segmentation fault. I have on purposely made the Queue length small so
> there will be packet drops. When I run this config I get the below results.
> 
> ok:   40 | 45000028 00000000 401177c3 01000001 02000002 13691369
> ok:   40 | 45000028 00000000 401177c3 01000001 02000002 13691369
> ok:   40 | 45000028 00000000 401177c3 01000001 02000002 13691369
> ok:   40 | 45000028 00000000 401177c3 01000001 02000002 13691369
> Segmentation fault
> 
> But when I remove the Strip and CheckIPHeader elements this segmentation
> fault does not occur. Also if I only use one source and send the same
> amount of packets the segmentation fault does not occur. I have not changed
> these elements in any way. Do you have any idea why this is happening??
> 
> 
> require(sample);
> 
> q1 :: Queue(10)
> 
> InfiniteSource(DATA \<00 00 c0 ae 67 ef  00 00 00 00 00
> 00  08 00 45 00 00 28  00 00 00 00  40 11 77 c3  01 00 00 01
> 02 00 00 02  13 69 13 69  00 14 d6 41  55 44 50 20
> 70 61 63 6b  65 74 21 0a>, LIMIT 10, STOP true)
>         ->Strip(14)
>         ->CheckIPHeader()
>         ->q1
> 
> InfiniteSource(DATA \<00 00 c0 ae 67 ef  00 00 00 00 00
> 00  08 00 45 00 00 28  00 00 00 00  40 11 77 c3  01 00 00 01
> 02 00 00 02  13 69 13 69  00 14 d6 41  55 44 50 20
> 70 61 63 6b  65 74 21 0a>, LIMIT 10, STOP true)
>         ->Strip(14)
>         ->CheckIPHeader()
>         ->q1
> 
> InfiniteSource(DATA \<00 00 c0 ae 67 ef  00 00 00 00 00
> 00  08 00 45 00 00 28  00 00 00 00  40 11 77 c3  01 00 00 01
> 02 00 00 02  13 69 13 69  00 14 d6 41  55 44 50 20
> 70 61 63 6b  65 74 21 0a>, LIMIT 10, STOP true)
>         ->Strip(14)
>         ->CheckIPHeader()
>         ->q1
> 
> q1->Print(ok)->Discard;
>