Re: [UPDATE] zerocopy.. While working on ip.h stuff

From: David S. Miller (
Date: Mon Feb 26 2001 - 18:25:26 EST

Michael Peddemors writes:
> A few things.. why is ip.h not part of the linux/include/net rather than
> linux/include/linux hierachy?

Exported to older userlands...

> Defined items that are not used anywhere in the source..
> Can any of them be deleted now?
> <see below>

So what, userland makes use of them :-)

> Also, I was looking into some RFC 1812 stuff. (Thanks for nothing Dave :) and
> was looking at where it mentions that a router MUST implement the End
> of Option List option.. Havent' figured out where that is implememented yet..

egrep "IPOPT_END" net/ipv4/ip_options.c

You just aren't looking hard enough.

> Also was trying to figure out some things.
> I want to create a new ip_option for use in some DOS protection experiments.
> I have a whole 40 bytes (+/-) to share... Now although I don't see anything
> explicitly prohibiting the use of unused IP Header option space, I know that
> it really was designed for use by the sending parties, and not routers in
> between.. Has anyone seen any RFC that explicitly says I MUST NOT?

Not to my knowledge. Routers already change the time to live field,
so I see no reason why they can't do smart things with special IP
options either (besides efficiency concerns :-).

David S. Miller
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This archive was generated by hypermail 2b29 : Wed Feb 28 2001 - 21:00:12 EST