Re: [ovs-discuss] OVN DHCP implementation ignores broadcast bit

Alex Jones Thu, 06 Jul 2017 07:29:44 -0700

Hi Numan,

It doesn't matter to me. You know the code better than I do! Do you want me to post the patch, and you can improve it?

My patch does modify pinctrl_handle_put_dhcp_opts() currently.

Alex

On 07/04/2017 11:39 PM, Numan Siddique wrote:

NOTICE: This email was received from an EXTERNAL sender

On Tue, Jul 4, 2017 at 5:48 PM, Alin Serdean <[email protected]> wrote:

Hi Alex,

You can send it to [email protected] or create a new pull request via github.

Thanks,

Alin.

From: ovs-discuss-bounces@openvswitch.org [mailto:ovs-discuss-bounces@openvswitch.org] On Behalf Of Alex Jones
Sent: Tuesday, July 4, 2017 4:00 AM
To: [email protected]
Subject: [ovs-discuss] OVN DHCP implementation ignores broadcast bit

Hi All,

I have OVN up and running (version 2.7), and it is working well except for one case. We have a VM which uses its own IP stack and does not accept unicast DHCP offers. After examining the OVN code, I found that it currently doesn't support the broadcast bit if set by the client.

I didn't see any bugs regarding this, so I did a patch myself. The patch modifies put_dhcp_options to return 2 if the broadcast bit was set in the DISCOVER/REQUEST, and 1 if not set (both indicate success). Then I modified the current logical flow to check if the return code is 1, then execute the current logical flow. I added a new logical flow to handle the broadcast bit set case. If the return value from put_dhcp_options is 2, the new flow is executed which sets the dest MAC and dest IP to broadcast.

I'd like to submit this. Do I just post it here?

Alex

The other simpler approach could be to set "ip4.dst and eth.dst" to broadcast addresses if broadcast bit is set, giaddr and ciaddr is 0 (as per the RFC - https://www.ietf.org/rfc/rfc2131.txt) in the function "pinctrl_handle_put_dhcp_opts" (in ovn/controller/pinctrl.c) and modify ovn-northd.c to not set the eth.dst and ip4.dst fields in the S_SWITCH_IN_DHCP_RESPONSE pipeline.

Probably we should also set ip4.dst to giaddr (to support dhcp relay) if it is set.

Thanks

Numan

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Re: [ovs-discuss] OVN DHCP implementation ignores broadcast bit

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