In some email I received from Wolfgang Solfrank, they wrote:
> 
> > My concern is that if fragments arrive out of order and/or overlap
> > it won't defragment them correctly.
> > 
> > The (what seems to me to be) a significant problem is that if the
> > first fragment queued isn't the first fragment and nothing can ever
> > be inserted in front of the first fragment received (without deque'ing
> > the queue and reque'ing it).
> 
> What makes you think that there is a problem with inserting a fragment
> before the first one already in the queue? Should work perfectly well, as
> far as I can see. The only somewhat tricky part is the overlaying of
> ipq_next, ipq_rev and ipf_next, ipf_prev resp.
> 
> If you have any additional questions, feel free to ask.

It's ok, I discussed this with Chris only to realise that I didn't realise
the list head wasn't an actual fragment %-)  doh!

darren