* Re: IPv6: the same address can be added multiple times
2001-05-13 20:26 ` Pekka Savola
@ 2001-05-14 2:47 ` David S. Miller
2001-05-14 7:42 ` Kai Henningsen
2001-05-14 10:48 ` David Woodhouse
2001-05-14 18:21 ` kuznet
2 siblings, 1 reply; 7+ messages in thread
From: David S. Miller @ 2001-05-14 2:47 UTC (permalink / raw)
To: Pekka Savola; +Cc: kuznet, linux-kernel
Pekka Savola writes:
> But it still looks dirty. Also, it's easier to add it many times by
> mistake; IPv4 addresses do not allow this. And as you have to remove them
> N times too, this may create even more confusion.
There is this growing (think growing as in "fungus") set of thinking
that just because something can be misused, this is an argument
against it even existing.
I think this is wrong. I'm seeing it a lot, especially on this list,
and it's becomming a real concern at least to me.
Most of the time the argument goes like:
1: "Well, we allow this because you can do usefull things X Y and
Z as a result."
2: "Yeah, but this also lets you do stupid things like A B and
C."
translation: "It hurts when I do A B or C"
Most people know the appropriate response for the translation of
#2 ;-)
Later,
David S. Miller
davem@redhat.com
^ permalink raw reply [flat|nested] 7+ messages in thread* Re: IPv6: the same address can be added multiple times
2001-05-14 2:47 ` David S. Miller
@ 2001-05-14 7:42 ` Kai Henningsen
0 siblings, 0 replies; 7+ messages in thread
From: Kai Henningsen @ 2001-05-14 7:42 UTC (permalink / raw)
To: linux-kernel
davem@redhat.com (David S. Miller) wrote on 13.05.01 in <15103.18224.265350.877968@pizda.ninka.net>:
> Pekka Savola writes:
> > But it still looks dirty. Also, it's easier to add it many times by
> > mistake; IPv4 addresses do not allow this. And as you have to remove
> > them N times too, this may create even more confusion.
>
> There is this growing (think growing as in "fungus") set of thinking
> that just because something can be misused, this is an argument
> against it even existing.
But that does not seem to be the argument here. Rather, it is "I can
certainly see where this can cause harm, but I cannot see where it is
useful for anything at all, so why do we have it?".
> I think this is wrong. I'm seeing it a lot, especially on this list,
> and it's becomming a real concern at least to me.
>
> Most of the time the argument goes like:
>
> 1: "Well, we allow this because you can do usefull things X Y and
> Z as a result."
What is X, Y and Z in this particular case? Nobody seems to have said
that.
Incidentally, this thread is *very* similar to the "mount the exact same
FS several times on the exact same mountpoint" thing. I'd expect to get a
similar resolution (i.e., *don't* allow that).
MfG Kai
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: IPv6: the same address can be added multiple times
2001-05-13 20:26 ` Pekka Savola
2001-05-14 2:47 ` David S. Miller
@ 2001-05-14 10:48 ` David Woodhouse
2001-05-14 18:21 ` kuznet
2 siblings, 0 replies; 7+ messages in thread
From: David Woodhouse @ 2001-05-14 10:48 UTC (permalink / raw)
To: David S. Miller; +Cc: Pekka Savola, kuznet, linux-kernel
davem@redhat.com said:
> There is this growing (think growing as in "fungus") set of thinking
> that just because something can be misused, this is an argument
> against it even existing.
> I think this is wrong. I'm seeing it a lot, especially on this list,
> and it's becomming a real concern at least to me.
The removal of the perfectly sane get_module_symbol() and replacement with
a less useful function which looks stuff up in a dynamic table instead of a
static table built at link time is an example of this. Now I have horrible
link order dependencies in code which was previously relatively clean. It
sucks, and there was absolutely no reason for it.
The fact that it was done so late in 2.4-test without even a period of
marking the original sane version as deprecated made it even worse.
Thinks... if I violently abuse inter_module_crap() will it suffer the same
fate and can I replace it with get_module_symbol() again? :)
--
dwmw2
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: IPv6: the same address can be added multiple times
2001-05-13 20:26 ` Pekka Savola
2001-05-14 2:47 ` David S. Miller
2001-05-14 10:48 ` David Woodhouse
@ 2001-05-14 18:21 ` kuznet
2001-05-18 14:00 ` Pekka Savola
2 siblings, 1 reply; 7+ messages in thread
From: kuznet @ 2001-05-14 18:21 UTC (permalink / raw)
To: Pekka Savola; +Cc: linux-kernel
Hello!
> 2) no significant restrictions (==this)
When user asks to create some object, the only required thing
of any reasonable interface is to return an error when the object
is not added.
KAME's one is broken, ours is _one_ of right ones.
Another example of bad mistake is mine: I have made some crap with creating
tunnels: adding tunnel does not fail, when such tunnel already exists,
so that user has no idea, whether did it create tunnel (and should it
delete it) or someone another made this work. Note, that if we would
be able to create _duplicate_ tunnels on each new request (like IPv6 addresses),
this would be also right approach.
Alexey
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: IPv6: the same address can be added multiple times
2001-05-14 18:21 ` kuznet
@ 2001-05-18 14:00 ` Pekka Savola
0 siblings, 0 replies; 7+ messages in thread
From: Pekka Savola @ 2001-05-18 14:00 UTC (permalink / raw)
To: kuznet; +Cc: linux-kernel
On Mon, 14 May 2001 kuznet@ms2.inr.ac.ru wrote:
> Hello!
>
> > 2) no significant restrictions (==this)
>
> When user asks to create some object, the only required thing
> of any reasonable interface is to return an error when the object
> is not added.
Please don't get stuck on that -- It wasn't the point ;-).
I pointed out KAME (and this seems to apply to IPv4 stack too) because it
would not add the same address twice. The fact that it doesn't print out
an error message was just some wondering on the side; irrelevant from the
point of view discussed here (this duplicate error might have to special
cased in userland tools somehow though).
The command can be made print out the error message if that's what's
deemed important.
I guess BSD people have for some reason thought returning 0 on SIOCAIFADDR
for duplicates is ok. Or perhaps it's a bug. Investigating.
> KAME's one is broken, ours is _one_ of right ones.
I fail to see what the other right ones (ones that will actually add
an address too) are. But that's not important. :-)
Cc: please.
--
Pekka Savola "Tell me of difficulties surmounted,
Netcore Oy not those you stumble over and fall"
Systems. Networks. Security. -- Robert Jordan: A Crown of Swords
^ permalink raw reply [flat|nested] 7+ messages in thread