tree 68465614493c6c3dd1632e14f36bed5edcc4d0d2
parent 102a4cdacb0a6d8c8c3c97e10bedbb66000ac5dc
author Johnathan Mantey <johnathanx.mantey@intel.com> 1712171157 -0700
committer Ed Tanous <ed@tanous.net> 1714759077 +0000

Delete IPv4 default gateway when deleting an IPv4 static address

The Redfish schema for creating static IPv4 addresses requires the IP
address, the netmask, and a gateway IP address. There's an issue
inherent with this method. A network interface is only permitted a
single IPv4 default gateway. If more than one IPv4 static address is
assigned to the NIC each entry is processed, and potentially
conflicting default gateways may be assigned. The last entry processed
assigns the IPv4 default gateway. This behavior will cause unexpected
results. It is necessary to prevent assigning mismatched default
gateway values.

The IPv4 address removal process requires additional work also. The
default gateway value is left in place even after the final static
IPv4 address is removed. It is necessary to perform an additional
action to clear the gateway address. Without explicit removal the
network is left in a condition that may prevent IP traffic from being
able to be sent from the BMC. This even in the event that the NIC is
actively being managed via DHCPv4.

Tested:
Disabled DHCPv4 on a secondary NIC (eth1)
Assigned a static IPv4 address.
Inspected the systemd-networkd config file in order to confirm the
Gateway entry is added. This is done to be explicitly sure the
network.config file has the Gateway entry.
Sent a Redfish PATCH command to delete the static IPv4 address.
Confirmed that the systemd-networkd config file no longer contained a
Gateway entry. This is done to be explicitly sure the network.config
file no longer contains the Gateway entry.
Created a PATCH containing multiple IPv4 static addresses all with
different Gateway values. Confirmed an error is returned when a
mismatch occurs in the Gateway values.
Assigned a new static address, and then restored DHCPv4.
Confirmed that the default gateway entry in the config file is removed.
Submitted a delete request for the remaining static IPv4 address that
is now orphaned by re-enabling DHCPv4. This removed the static IPv4
address.

Change-Id: Ia12cf2a38ba86266ce71dc28475b0d07b7e09ebc
Signed-off-by: Johnathan Mantey <johnathanx.mantey@intel.com>