[Starlingx-discuss] DHCP Related Patches

[Saul Wold]

On 10/04/2018 04:51 PM, Penney, Don wrote:
> Here's the original commit message for dhclient-restrict-interfaces-to-command-line.patch. There was an issue with leases expiring, causing interfaces to lose their IP addresses, which in turn caused various issues due to the loss of comms:
> 
> Author: Allain Legacy <allain.legacy at windriver.com>
> Date:   Tue Jan 5 14:36:47 2016 -0500
> 
>      dhclient: restrict interfaces to those on command line only
> 
>      By default, the dhclient process does not respect the list of interfaces
>      supplied at the command line.  It configures any interfaces found to be
>      specified in the config file.  Since we customize options for each interface in
>      our config file and run a separate dhclient process for each interface we end
>      up with multiple dhclient processes that each service all interfaces.  This is
>      undesirable because it is possible that a request is sent by process A but
>      received by process B.  This leads to lease expiry events even though a valid
>      request packet was returned by the server.
> 
So, a further question is why is the default behavior of having 1 
process managing all the interfaces a bad thing?  What problem were you 
trying to solve?  Again, the WHY behind the original change not just 
that dhclient has a undesirable behavior.  Why is there a 
dhclient/interface?

>      This change introduces a "--restrict-interfaces" option to the dhclient process
>      to force it to ignore all interfaces in config files other than those specified
>      at the command line.
> 
>      To activate this change our busybox version of ifup/ifdown has been modified to
>      pass the "--restrict-interfaces" to dhclient as well as to request that each
>      process use its own lease file to avoid file corruption.
> 
I think this dates to the OE version, as Centos does not have busybox, 
but the changes are in initscripts.

Thanks

Sau!
> 
> 
> -----Original Message-----
> From: Saul Wold [mailto:sgw at linux.intel.com]
> Sent: Thursday, October 04, 2018 6:02 PM
> To: Rowsell, Brent; starlingx-discuss at lists.starlingx.io
> Subject: [Starlingx-discuss] DHCP Related Patches
> 
> 
> HI Brent,
> 
> There are currently 6 DHCP related patches specifically to the client code.
> 
> We have already determined that 2 of those patches the NSUPDATE
> protection could be removed, 2 seem to be StarlingX spceific but
> replaced with a enter-hook scripts provided in another patch. 1 is a
> backport
> 
> 
> dhclient-disable-NSUPDATE.patch
> support-disable-nsupdate.patch
>    - Remove these 2
> dhclient-handle-wrs-install-uuid.patch
> dhclient-dhcp6-wrs-install-uuid.patch
>    - Can these be removed as the functionality is now added via the
> dhclient-enter-hooks script?
> 
> dhclient-ipv6-bind-to-interface.patch
>    - This is a backport, which will be available when CentOS updates to
> the newer version.
> 
> dhclient-ipv6-conditionally-set-hostname.patch
>    - Can this be moved to the dhclient-enter-hooks?
> 
> dhclient-restrict-interfaces-to-command-line.patch
>    - This seems to be adding functionality, in order to restrict the
> dhclient to only be active on one interface. There is no commit message
> for this one, or is there a way to refactor this?  Is this a bug in
> dhclient?  Was it ever filled or commented on in the DHCP mailing list?
> 
> 
> Thanks
>      Sau!
> 
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