tehmaze/ipcalc — pull request #12 by mattbennett (2012-06-12 11:13:07+00:00)
Title: Address/mask hex/octet checks exclude the top and bottom of the range

IPv6 address/mask hextets can contain 0x0 and 0xffff
IPv4 address/mask octets can contain 0 and 255

Twinshadow's Pull Request only fixes the problem for one of these cases.