iptools.ipv4.validate_netmask() seems to be auto-filling 0's

[DarthOpto]

import iptools netmask = '255' valid = iptools.ipv4.validate_netmask(netmask)
This returns True. 255 is not a valid netmask. It seems that this is auto-filling the 0's to make it a full netmask. We were using this tool to check and see if our users are entering valid IP addresses, netmasks, and gateways. Since it is auto-filling if you only have the first octet and nothing else this is not a valid tool which we can use.

Also, we tried inputting '0.255.255.0' and this method returned True.

[bd808]

Right now it does autofill using the ip2network logic. It then asserts that all of the leftmost bits are 1 and the right most bits are 0. Your report about 0.255.255.0 led me to find a bug in that validation however. I wasn't ensuring that the bit string was fully expanded to 32 bits. That should be fixed by 285fe5c.

I looked around a bit for an RFC or other canonical documentation about what a "valid" netmask actually is and came up empty. @DarthOpto can you point me to some docs that you consider to be canonical?

[DarthOpto]

I am not sure about canonical documentation and I am sure that your implementation is correct. I simply wanted to point out that our use case was someone fat fingering a network mask and hitting ENTER instead of the period, they are right next to each other on the number pad, so it is possible. Returning True for only a 255 in my mind doesn't make a lot of sense. That being said thank you for correcting the other defect.

[jellonek]

255 is correct value, as is 65535 for example. Why do you think that this is not valid value?
It's unusable for netmasking, but still looks like correct representation of 32bit value which should be interpreted as valid net mask.

[DarthOpto]

We were using iptools for validating user input into a system as it was being setup to make sure that they were entering in a valid netmask. If the user does not enter in a valid netmask their system will have to be reconfigured. Our hope was that iptools would validate that the user had entered in a correct netmask. It does not. By auto-filling with 0's we cannot accurately validate whether or not a user has "fat-fingered" and possibly made a mistake when entering their netmask.

255 may be a valid value for short-hand notation, however simply checking whether or not the value entered is a valid netmask would seem to me to be better suited to not having it auto-fill with zeros.