Validate if fixed_ip given for port isn't the same as subnet's gateway_ip

[Slawek Kaplonski]

Currently when new port is created with fixed_ip given, neutron is not validating if that fixed_ip address isn't the same as subnet's gateway IP. That may cause problems, like e.g.:

$ openstack subnet show <subnet-id>
| allocation_pools | 10.0.0.2-10.0.0.254
| cidr | 10.0.0.0/24
| enable_dhcp | True
...
| gateway_ip | 10.0.0.1

$ nova boot --flavor test --image test --nic net-id=<network-id>,v4-fixed-ip=10.0.0.1 test-vm1

The instance will be created successfully, but after that, network communication issue could be happened since the gateway ip conflict.

So Neutron should forbid creation of the port with gateway's ip address if it is not router's port (device_owner isn't set for one of the router device owners).

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/803334

[Oleg Bondarev (obondarev)]

May it be some valid use case, where one would like to handle subnet gateway on a VM (VNF)?

[OpenStack Infra (hudson-openstack)]

Change abandoned by "Slawek Kaplonski <email address hidden>" on branch: master
Review: https://review.opendev.org/c/openstack/neutron/+/803334
Reason: After thinking more about it and after talking with Rodolfo, I think it is valid use case to set subnet's gateway on the vm e.g. to filter/log/monitor traffic going from all other vms in network. So this patch is not needed at all. Thx Oleg and Rodolfo for review and help with that.

[Slawek Kaplonski (slaweq)]

After thinking more about it and after talking with Rodolfo, I think it is valid use case to set subnet's gateway on the vm e.g. to filter/log/monitor traffic going from all other vms in network. So this patch is not needed at all. Thx Oleg and Rodolfo for review and help with that.