>  > The problem is that you cannot be sure that the mbuf does have MLEN/MHLEN
>  > at the address pointer to by mh_data (and thus returned by the mtod macro).
>  > The mh_data pointer might have been incremented beyond its initial value.
>  > Hell, it even might have been setup with an offset to allow later insertion
>  > of a header in front of the data placed into it initially.
> 
> Won't M_TRAILINGSPACE() give this to you?

Yes, looks so.  I was only speaking from memory :-/.
-- 
ws@TooLs.DE     (Wolfgang Solfrank, TooLs GmbH) 	+49-228-985800