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

From: Andi Kleen (
Date: Mon Feb 26 2001 - 18:23:04 EST

Michael Peddemors <> writes:

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

Because it needs to be user visible for raw sockets (linux is exported to the user,
net isn't)

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

nope. they can be useful for the user.

> 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..

It is (see net/ipv4/ip_options:ip_options_compile())

> 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?

Using IP options is strongly deprecated because it causes a lot of switches/routers
to go from hardware into software switch mode (-> it kills your gigabit routers)

They are implemented, just only implicitely as an array index.

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