On Mon, Jan 24, 2005 at 09:50:05AM -0800, Matthew Dillon wrote:
> From my read of the code, the 'eh = mtod(...)' is necessary, but
> most of the time the returned 'm' will be the same as the passed 'm'
> so I am not surprised that you did not see any difference.
The eh = mtod() is necessary, because the ether header might not actually be
part of the passed in header. Because ether_ifpw_chk changes that by
prepending the header, it is necessary to update the pointer in the caller.
Joerg