Re: making DUID work .. was [Dnsmasq-discuss]

[Gene Czarcinski <gene czarc net>]

On 02/12/2013 10:53 AM, Gene Czarcinski wrote:
> On 02/12/2013 10:13 AM, Gene Czarcinski wrote:
> > On 02/12/2013 09:23 AM, Gene Czarcinski wrote:
> > > On 02/11/2013 04:51 PM, Dan Williams wrote:
> > > > On Mon, 2013-02-11 at 16:42 -0500, Gene Czarcinski wrote:
> > > > > On 02/11/2013 04:06 PM, Dan Williams wrote:
> > > > >
> > > > > > Fedora 17 and 18, until 0.9.7.997, left the DUID behavior up to
> > > > > > dhcleint, which appears to generate a default DUID itself; but the
> > > > > > NetworkManager code will honor that existing DUID if it finds it 
> > > > > > in the
> > > > > > interface+connection specific lease file [1].  If NM does *not*, 
> > > > > > please
> > > > > > let me know and we'll fix that bug.
> > > > > It is *not*.
> > > > >
> > > > > I assume that NM is suppose to be examining the lease file before
> > > > > dhclient starts because it sure looks like it is dhclient that is
> > > > > creating the default.
> > > > >
> > > > > I have a real-hardware system that I can reboot or whatever so if you
> > > > > need me to test something, just tell me.  I know that it is
> > > > > frustrating on both sides if I say there is a problem and you cannot
> > > > > reproduce it.
> > > > >
> > > > > If you need to see the configuration file, then I should probably 
> > > > > open
> > > > > a bugzilla report and file it there.
> > > > >
> > > > > BTW, I tried putting the default-duid in /etc/dhclient.leases and 
> > > > > also
> > > > > in /var/lib/dhclient.leases and the only thing that seems to work
> > > > > is /var/lib/NetworkManager/dhclient6-<whatever>.lease
> > > > You want one of dhclient*6*.leases, in this priority order:
> > > >
> > > > SYSCONFDIR "/dhclient6.leases",
> > > > LOCALSTATEDIR "/lib/dhcp/dhclient6.leases",
> > > > LOCALSTATEDIR "/lib/dhclient/dhclient6.leases",
> > > >
> > > > or the interface+connection-specific leasefile, eg:
> > > >
> > > > /var/lib/dhclient/dhclient6-cc98bcbe-ef64-4db7-9b46-b12ca02172e6-wlan12.lease 
> > > When I saw the above, hand slaps forehead ... of course it should be 
> > > dhclient6.leases and not dhclient.leases.
> > >
> > > So I changed it in both /etc/dhclient6.leases and 
> > > /var/lib/dhclient/dhcleit6.leases but it still did not work. Only 
> > > replacing the interface+connection-specific leasefile with the one 
> > > line file specifying the default-duid works. However, I cannot see 
> > > that as a NM problem and will need to investigate dhclient.
> > OK, so I took a look at the dhclient code and it only looks for one 
> > dhclient6 lease file.  It is either the default 
> > /var/lib/dhclient/dhclient6.leases or what is specified by the -SF 
> > command line argument such as done by NetworkManager.
> >
> > NetworkManager could create a new NM file such as /etc/default-duid 
> > that, if present, was use for the initial dhclient6-...lease file but 
> > dhclient will do nothing to help.
> >
> > From my perspective, for NetworkManager to do something like this 
> > would be useful because it could be set during the install process 
> > and the system would be configured properly from first boot.
> >
> > Would the NM project be receptive to a patch which implemented 
> > something like that?
> No need for a new patch!  Just need to make the code that is there 
> work.  It appears to me that in dhclient.c nm_dhcp_dhclient_init() is 
> defined but never called by anything.  Therefore, priv->def_leasefile 
> is NULL and get_duid() does not access any of the alternate locations 
> to get the default-duid value.
>
> I will see what kind of patch I can com up with.  I am also moving 
> this thread over to the Network Manager mailing list.
I have figured out what was incorrect (mainly that the lease file was 
not being saved) and will pretty up things before I support the patch.  
This patch fixes things so that if the specific lease file is missing or 
does not have a valid default-duid AND if a default-duid is specified in 
/etc/dhclient6.leases, /var/lib/dhcp/dhclient6.leases or 
/var/lib//dhclient/dhclient6.leases, then the default-duid will be 
written out the the lease file.

That fixes one thing.  The other is a puzzling problem.  If none of the 
above files exists, then a duid-UUID is suppose to be generated.  BUT, 
in the logs a get the message that the /etc/machine-id could not be parsed.

I don't know about other systems but all of mine have a /etc/machine-id 
consisting of a string of 32 hex digits representing 16 bytes.  From the 
man-page for uuid_parse I get:

The  uuid_parse  function converts the UUID string given by in into the
binary representation.   The  input  UUID  is  a  string  of  the form
1b4e28ba-2fa1-11d2-883f-b9a761bde3fb      (in      printf(3) format
"%08x-%04x-%04x-%04x-%012x", 36 bytes plus the trailing '\0')

And from the dbus-uuidgen man-page:

Note  that  the D-Bus UUID has no relationship to RFC 4122 and does not
generate UUIDs compatible with that spec.

Comments?

Gene