[systemd-devel] [PATCH] sd-dhcp-client: Sets broadcast flag to 1

[Camilo Aguilar]

It makes total sense. I can provide that patch in addition if you like,
But, can we merge this change for now so we can fix
https://github.com/coreos/bugs/issues/12 and create a new issue to make it
more robust?


On Wed, May 28, 2014 at 7:03 PM, Tom Gundersen <teg at jklm.no> wrote:

> On Wed, May 28, 2014 at 7:43 PM, Camilo Aguilar
> <camilo.aguilar at gmail.com> wrote:
> > In systems running on hypervisors this flag needs to be set ON, so
> offers can reach
> > the virtual machines.
> >
> > For more information please refer to this thread in CoreOS:
> https://github.com/coreos/bugs/issues/12
> >
> > Signed-off-by: Camilo Aguilar <camilo.aguilar at gmail.com>
> > ---
> >  src/libsystemd-network/sd-dhcp-client.c | 9 +++++++++
> >  1 file changed, 9 insertions(+)
> >
> > diff --git a/src/libsystemd-network/sd-dhcp-client.c
> b/src/libsystemd-network/sd-dhcp-client.c
> > index 0300a6b..8f54906 100644
> > --- a/src/libsystemd-network/sd-dhcp-client.c
> > +++ b/src/libsystemd-network/sd-dhcp-client.c
> > @@ -286,6 +286,15 @@ static int client_message_init(sd_dhcp_client
> *client, DHCPPacket **ret,
> >             refuse to issue an DHCP lease if 'secs' is set to zero */
> >          packet->dhcp.secs = htobe16(client->secs);
> >
> > +        /* RFC2132 section 4.1
> > +           A client that cannot receive unicast IP datagrams until its
> protocol
> > +           software has been configured with an IP address SHOULD set
> the
> > +           BROADCAST bit in the 'flags' field to 1 in any DHCPDISCOVER
> or
> > +           DHCPREQUEST messages that client sends.  The BROADCAST bit
> will
> > +           provide a hint to the DHCP server and BOOTP relay agent to
> broadcast
> > +           any messages to the client on the client's subnet. */
> > +        packet->dhcp.flags = htobe16(0x8000);
>
> Hm, most clients can and should use unicast, so we should definitely
> not request broadcast unconditionally. If there really is a situation
> where we need broadcast, we should detect that and only request
> broadcast in this case.
>
> Does that make sense?
>
> Cheers,
>
> Tom
>
> >          /* RFC2132 section 4.1.1:
> >             The client MUST include its hardware address in the ’chaddr’
> field, if
> >             necessary for delivery of DHCP reply messages.
> > --
> > 1.8.5.2 (Apple Git-48)
> >
> >
> > _______________________________________________
> > systemd-devel mailing list
> > systemd-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/systemd-devel
> >
>



-- 
*Camilo Aguilar*
Software Engineer
http://github.com/c4milo
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