IndexError: Index out of range error is observed for creating multiple networks with CIDR_v6

[Rohit Karajgi]

I am trying to run up a unit test that tries to create multiple (>1) networks having an IPv6 CIDR.
While doing so, it raises "IndexError: index out range for address range size!".
This specific use case is in module nova.network.manager, NetworkManager class's create_networks method.
Parameter values: num_networks = 2 (or more) and arbitrary value for cidr_v6 (say 2001:db8::/64)

Trunk Revision: 1370

Traceback (most recent call last):
  File "/home/rohit/nova/diablo/network_unittests/nova/tests/test_network.py", line 537, in test_create_networks_with_ipv6_multiple_networks
    vpn_start=9999)
  File "/home/rohit/nova/diablo/network_unittests/nova/network/manager.py", line 655, in create_networks
    cidr_v6 = '%s/%s' % (fixed_net_v6[start_v6],
  File "/usr/lib/pymodules/python2.6/netaddr/ip/__init__.py", line 917, in __getitem__
    raise IndexError('index out range for address range size!')
IndexError: index out range for address range size!

I think the list is trying to subscript a very large integer index.
line #624: network_size_v6 = 1 << 64 (which is equal to 18446744073709551616)

While calculating start_v6 = index * network_size_v6 , For index = 1 , start_v6 = 18446744073709551616
hence fixed_net_v6[start_v6] tries to access an out of range index, i.e fixed_net_v6[18446744073709551616]

[Jason Kölker (jason-koelker)]

This will be fixed with my new create_networks I'm working on for this other bug. It will use netaddr's built in subnetting/iterating.