Only apply NatDNS if it´s an inline network

[fdurand]

Description

(REQUIRED)
Describe what the new code is used for.
ie: Allow PacketFence to trigger the coffee machine on wireless EAP 802.1X connection to brew a fresh espresso.

Impacts

pfdhcp

Delete branch after merge

YES

Checklist

• Document the feature
• Add unit tests
• Add acceptance tests (TestLink)

NEWS file entries

Bug Fixes

• Fixed ShuffleDNS logic (only apply to inline network)

[nqb]

This PR will fix following issue: in a cluster environment with dns_on_vip_only enabled, pfdhcp returns IP address of current server in cluster in place of VIP.

[nqb]

I wonder if we should backport that fix because it's has the potential to cause issues:

• before fix: DNS server was IP address of each cluster member
• after fix: DNS server will be VIP only

If somebody has put firewall rules which doesn't allow DNS requests on VIP, DNS inside registration VLAN will not work anymore.
I doubt that is the case because if you enabled dns_on_vip_only, I doesn't make sense to restrict DNS traffic to VIP.

[nqb]

@fdurand,

FYI, on a setup with L3 registration VLANs, it looks like nat_dns is enabled by default which mean for these setups, we already return DNS VIP in DHCP response.