[PATCH v2] dhcp6c: DHCPv6 client

Leonid Lisovskiy lly.dev at gmail.com
Mon Nov 7 18:01:42 UTC 2011


On Mon, Nov 7, 2011 at 7:10 PM, Denys Vlasenko <vda.linux at googlemail.com> wrote:
>
>> One upstream(listen) interface - yes. But simplification to single
>> downstream (IA, PD) interface seems to be bad idea.
>
> Can you elaborate why is it a bad idea?

Of course, yes. For a example, take linux(busybox)-based CPE -
router/gateway/access point. It has at least two interfaces - WAN &
LAN. In case of DHCPv6 used by ISP to provide IPv6 access, we have to:

1) assign address(IA) on WAN interface
2) assing prefix(PD) on LAN interface

Thus, we must support two interfaces, at least.


>> Unfortunately, a few ISP's provide multi-server DHCP setups. Most of
>> them are buggy, but they are exists  :(
>> For example - Beeline ISP, Ekaterinburg, Russia.
>
> If "always select very first received server reply" doesn't work for them,
> then their installation is broken IMO.

Yes, you are absolutely right, but in some places it is monopoly ISP
:( And customers claims go to trash can - "windows works" it is
typical answer.


> Here is a compilable code I just dropped into git:
>
> http://git.busybox.net/busybox/commit/?id=9ba75048c0099ed90b9a64cb7bb57bf12be93528
>
> It's a moderately scary hack, but it builds and
> even sends dhcpv6-looking packets with correct UDP checksum! ;)
>
> d6_dhcpc.c file is basically a hacked copy of dhcpc.c -
> I retained the same logic we use in udhcpc.
>
> I deleted all logic which exports $envvars for now. I plan to add it back
> after I add code which parses dhcpv6 options returned by server.
>
> After the applet will reach the stage where it actually works
> in a simple setup (say, successfully sets IPv6 address + routing + DNS),
> then we can take a good look at possibilities to commonalize
> some bits in udhcpc and udhcpc6.
>
> Can you take a look at the code?
> Is basing future work on it ok with you?

Will do this ASAP. Will write you after I done it.


Regards,
   Leonid


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