dhcp.pm fix

[po1vo]

dhcp.pm claimed to not add ip address of a node, overlapping with dhcp dynamic range, but added anyway

[gurevichmark]

@po1vo Thank you for the contribution.
Can you please post how this problem can be recreated ?

[po1vo]

1. Pick an IP from a network dynamic dhcp range.
2. Pick a node and set the node's hosts.ip to the IP from the first step.
3. Do makedhcp node and see a message:

"The ip address $ip of node $node overlaps with the DHCP dynamic range specified in networks table, will not add this ip address into dhcpd.leases file."

But the address is added to dhcpd.leases anyway

[samveen]

This has the potential to break existing installations of xCAT (especially badly designed ones, like my early efforts) . A release note/warning in the next version would be a good idea if this is merged.

[gurevichmark]

@samveen Can you elaborate under which conditions this PR will be a problem ?

[samveen]

The potential break comes in the differing expectations:

• The user expects that the assigned IP is statically assigned to the node, as the node has the value set in hosts.ip .
• The cluster expects that the node IP should not be in the dynamic range.

I prefer that the node configuration should override the cluster expectation, as it is viewable and thus expected configuration.

Without such a static lease, in the case of a node reboot/restart, the node may not get the same IP, which is potentially disastrous from the cluster's perspective.