To: None <>
From: Dan Aberg <>
List: tech-net
Date: 03/23/2000 21:49:38
Hi All!

The macro M_LEADINGSPACE only returns the amount of unused
space at the beginning of an mbuf if the data is not in a
cluster. If it is, the macro always returns 0. This is to
prevent trashing someone else's data when the cluster is

But the macro M_TRAILINGSPACE returns the amount of unused
space at the end of the mbuf even if the data is in a
cluster. Is this really correct?

I'm actually having problems with trashed ICMP packets
when I add my own headers and trailers using M_TRAILINGSPACE.
It works if I add a new mbuf, but not when I use the
space M_TRAILINGSPACE tells me I have.

By the way, I'm using NetBSD 1.4.1 (i386).