[Bug 1564077] Re: ipaddr.IPv4Network object miscalculates network addresses

[Scott Kitterman]

Note: ipaddr is no longer developed separately upstream.  It was the
basis for the ipaddress module included in python3.3 and later.  It
would be useful to see if this issue is present there as well and if it
is, forwarding it python upstream.

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Title:
  ipaddr.IPv4Network object miscalculates network addresses

Status in python-ipaddr package in Ubuntu:
  Confirmed

Bug description:
  When using the IPv4Network.Supernet() call, the resulting address is
  calculated incorrectly. Instead of presenting the all-zeros address in
  the host part, the first bit of the host part is kept as it was,
  causing an incorrect address to be displayed. This only appears to be
  a display issue, the network objects behave as they should (at least
  for the equality operator).

  The following python program can be used to see the issue.

  from sys import argv
  import ipaddr

  ip1 = ipaddr.IPv4Network(argv[1])
  ip2 = ipaddr.IPv4Network(argv[2])

  
  print "Testing ", str(ip1), str(ip2)
  while ip1 != ip2:
  	print ip1,ip2
  	ip1 = ip1.Supernet()
  	ip2 = ip2.Supernet()

  print "Ending ", ip2

  This program takes two addresses and attempts to find the network in
  common, using the Supernet call to locate it. However, below is the
  output of the program.

  $ python ipaddr-bug-test.py 10.53.45.24 10.53.45.255
  Testing  10.53.45.24/32 10.53.45.255/32
  10.53.45.24/32 10.53.45.255/32
  10.53.45.24/31 10.53.45.255/31
  10.53.45.24/30 10.53.45.254/30
  10.53.45.24/29 10.53.45.252/29
  10.53.45.24/28 10.53.45.248/28
  10.53.45.16/27 10.53.45.240/27
  10.53.45.0/26 10.53.45.224/26
  10.53.45.0/25 10.53.45.192/25
  Ending  10.53.45.128/24

  Note how the program correctly shows the /32 addresses, but when
  getting the supernet for the second address, it mistakenly shows
  10.53.45.255/31 when the correct value should have been
  10.53.45.254/31. The same happens in all the stages, and is very
  obvious when doing the computation on a broadcast address. Finally,
  the address is constructed with the wrong network address.

  As for system data, here goes all the data indicated in the submission
  instructions:

  $ lsb_release -rd
  Description:	Ubuntu 14.04.4 LTS
  Release:	14.04

  $ apt-cache policy python-ipaddr
  python-ipaddr:
    Installed: 2.1.10-1
    Candidate: 2.1.10-1
    Version table:
   *** 2.1.10-1 0
          500 http://ar.archive.ubuntu.com/ubuntu/ trusty/main amd64 Packages
          100 /var/lib/dpkg/status

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: python-ipaddr 2.1.10-1
  ProcVersionSignature: Ubuntu 3.19.0-51.58~14.04.1-generic 3.19.8-ckt13
  Uname: Linux 3.19.0-51-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.19
  Architecture: amd64
  CurrentDesktop: XFCE
  Date: Wed Mar 30 17:17:20 2016
  EcryptfsInUse: Yes
  InstallationDate: Installed on 2016-02-29 (29 days ago)
  InstallationMedia: Xubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
  PackageArchitecture: all
  SourcePackage: python-ipaddr
  UpgradeStatus: No upgrade log present (probably fresh install)

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