Date: Tue, 07 Feb 2012 15:47:08 +0100 From: Dirk Engling <erdgeist@erdgeist.org> To: Hiroki Sato <hrs@FreeBSD.org> Cc: freebsd-rc@FreeBSD.org Subject: Re: Proposal ipv6_addrs_common Message-ID: <4F31396C.2060507@erdgeist.org> In-Reply-To: <20120207.170255.161251905285915806.hrs@allbsd.org> References: <4F304F54.4020802@FreeBSD.org> <20120207.072925.1861639312875773760.hrs@allbsd.org> <4F3088C8.9090505@erdgeist.org> <20120207.170255.161251905285915806.hrs@allbsd.org>
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On 07.02.12 09:02, Hiroki Sato wrote:
> Ah, I see. This looks good. I will give it a try and investigate
> corner cases.
I did not want to put the burden of implementation on you. I'm doing
shell scripting for a living and can surely help with that. I just
need some directions, pitfalls that have been found earlier and that I
should avoid.
> This is because it is unclear that which address family will be
> used to recognize an address without AF keyword. In most cases
> network-related utilities/scripts assume IPv4 by default and
> require a modifier or option for the others. It works, but
> sometimes it requires a complex and inconsistent address handling
> in utilities/scripts. Appending AF keyword burdens users a bit
> but simplifies multiple address family support in more consistent
> manner.
So to put that in the grand perspective, the ifconfig_IF_aliases knob
is solely to configure additional aliases to the interface as opposed
to the ifconfig_IF knob which can contain other more complex
parameters to pass to ifconfig? Do we need to handle more cases than
plain ipv4, hex ipv4, plain ipv6 addresses, ipv6 mapped v4 and hostnames?
- From the ifconfig's man page I take at least "ether", "ipx" and
"atalk". It does not make sense to support re-setting link level
addresses in the ifconfig_IF_aliases knob. For the atalk address
family ifconfig recognises "range" modifiers that work like netmasks,
but it looks not very common to configure additional atalk address to
a single interface. Maybe someone with IPX knowledge can comment if we
need to take special care.
To sum it up: the handler for the ifconfig_IF_aliases knob should just
pass each space separated value to
ifconfig $IF $v (-)alias
, unless
a) it is prefixed with any of the address family names know to
ifconfig, in that case the family should be remembered and next value
be parsed and passed to
ifconfig $IF $family $v (-)alias
b) it matches RANGE.RANGE.RANGE.RANGE(/\d{1-2})? for RANGE in
\d{1-3}(-\d{1-3})? with at least one dash.
In that case it is expanded and each expansion passed to
ifconfig $IF $family $expansion/$mask (-)alias
with mask set to 32 after the first address in each subnet. For an
address family already specified we could check for conflicts here or
leave that to ifconfig.
c) it matches *-*:*:*(/\d{3})?, *:*-*:*(/\d{3})?, *:*:*-*(/\d{3})?
(So we're sure not to interfere with link level addresses.) In that
case it is expanded and each expansion passed to
ifconfig $IF inet6 $expansion/$mask (-)alias
here we should check for collision of the address family. Also I am
not sure if you have to alter the netmask.
d) it matches ::ffff:RANGE.RANGE.RANGE.RANGE(/\d{1-2})? with at
least one dash.
In that case it is expanded and each expansion passed to
ifconfig $IF inet6 $expansion/$mask (-)alias
with mask reset 128 after the first address in each subnet.
Done ;)
erdgeist
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