subnet CIDR validation broken for non-root CIDRs again

[Jay Bryant]

Earlier this month a fix was released to allow non-root CIDRs to be entered. The fix was for bug 1188845. It was approved and merged. Now, however, the functionality has been reversed by commit 53a66b299f18a7184972502b43441a5ad7b050fd (bug 1195974) which checks the input earlier in the path and rejects anything but the root CIDR.

I am unable to find documentation that says you cannot use a non-root (I.E. X.X.X.254) IP to specify a subnet. With an IP and subnet mask it is possible to create a network and determine the root for the subnet.

[yong sheng gong (gongysh)]

Do u have the case where the subnet is non-root?

[Jay Bryant (jsbryant)]

Yong Sheng,

As I put in bug 118845, we have a customer that uses a non-root CIDR frequently. They are sent an IP address and they want to create a new subnet or that IP. The address sent in is not always the root. What they had done in scripting in the past was to just use the IP they were sent, I.E. 10.0.2.10/24 with the CIDR to create the subnet.

I had gotten this working and approved earlier in the month but now the change you committed nullifies that change.

[ZhiQiang Fan (aji-zqfan)]

i suggest that for a certain change, you'd better write good enough test code, this can avoid unexpected refactor or later change, since they will not pass the unittest for your case

[Armando Migliaccio (armando-migliaccio)]

Jay, it looks like bug 118845 is erroneously referenced in this report. Could you provide the right one?

[James Carey (jecarey)]

Correct reference is https://bugs.launchpad.net/neutron/+bug/1188845

[James Carey (jecarey)]

I saw that you took this. I have a user that is running into this asking me about it. Do you have some info on how you are planning to solve this you could share with me?

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/81137

[Kevin Benton (kevinbenton)]

I think it's valid for a user to put whatever they want in the masked portion of a CIDR. This becomes particularly useful if you are dealing with small boundary subnets that don't end with nice decimal zeros.

I don't see the advantage of putting the user through the pain of performing the masking operation when neutron is already doing it using the netaddr library. :-)

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/81137
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=39c04fdc2c94b8ee48600f3148c5f850645b7c4e
Submitter: Jenkins
Branch: master

commit 39c04fdc2c94b8ee48600f3148c5f850645b7c4e
Author: Kevin Benton <email address hidden>
Date: Mon Mar 17 17:06:46 2014 -0700

    Allow CIDRs with non-zero masked portions

    Allow users to specify CIDRs with bits other
    than zeros in the masked portion of the subnet.
    e.g. 192.168.1.5/24 is accepted and converted
    to 192.168.1.0/24.

    Closes-Bug: #1204173
    Change-Id: I7ddff41e6988feb6e2a87e40a4d99db7174415b1