Repository: cloud-custodian/cloud-custodian

Issue:
core - remove vendored ipaddress
we dropped python 2.7 support so we can defer to the sdlib module. i recall there being some oddities here so it may require some additional checking on changelog for that module in stdlib as well constructing some wrappers.


Discussion:

Resolving patch:
diff --git a/c7n/filters/core.py b/c7n/filters/core.py
--- a/c7n/filters/core.py
+++ b/c7n/filters/core.py
@@ -20,6 +20,7 @@
 import datetime
 from datetime import timedelta
 import fnmatch
+import ipaddress
 import logging
 import operator
 import re
@@ -32,7 +33,6 @@
 import jmespath
 import six
 
-from c7n import ipaddress
 from c7n.exceptions import PolicyValidationError
 from c7n.executor import ThreadPoolExecutor
 from c7n.registry import PluginRegistry
diff --git a/c7n/ipaddress.py b/c7n/ipaddress.py
deleted file mode 100644
--- a/c7n/ipaddress.py
+++ /dev/null
@@ -1,2430 +0,0 @@
-# Copyright 2007 Google Inc.
-#  Licensed to PSF under a Contributor Agreement.
-
-"""A fast, lightweight IPv4/IPv6 manipulation library in Python.
-
-This library is used to create/poke/manipulate IPv4 and IPv6 addresses
-and networks.
-
---------- NOTE ----------------------------------------------------------------
-
-Vendored in to ensure compatibility between Python 2 and 3. The version shipped
-in the Python 3 stdlib is not backwards compatible to Python 2, which causes
-issues when publishing 2.7 lambdas from 3.
-
-Source: https://raw.githubusercontent.com/phihag/ipaddress/v1.0.18/ipaddress.py
-
---------- END NOTE ------------------------------------------------------------
-
-"""
-
-from __future__ import unicode_literals
-
-
-import itertools
-import struct
-
-__version__ = '1.0.19'
-
-# Compatibility functions
-_compat_int_types = (int,)
-try:
-    _compat_int_types = (int, long)
-except NameError:
-    pass
-try:
-    _compat_str = unicode
-except NameError:
-    _compat_str = str
-    assert bytes != str
-if b'\0'[0] == 0:  # Python 3 semantics
-    def _compat_bytes_to_byte_vals(byt):
-        return byt
-else:
-    def _compat_bytes_to_byte_vals(byt):
-        return [struct.unpack(b'!B', b)[0] for b in byt]
-try:
-    _compat_int_from_byte_vals = int.from_bytes
-except AttributeError:
-    def _compat_int_from_byte_vals(bytvals, endianess):
-        assert endianess == 'big'
-        res = 0
-        for bv in bytvals:
-            assert isinstance(bv, _compat_int_types)
-            res = (res << 8) + bv
-        return res
-
-
-def _compat_to_bytes(intval, length, endianess):
-    assert isinstance(intval, _compat_int_types)
-    assert endianess == 'big'
-    if length == 4:
-        if intval < 0 or intval >= 2 ** 32:
-            raise struct.error("integer out of range for 'I' format code")
-        return struct.pack(b'!I', intval)
-    elif length == 16:
-        if intval < 0 or intval >= 2 ** 128:
-            raise struct.error("integer out of range for 'QQ' format code")
-        return struct.pack(b'!QQ', intval >> 64, intval & 0xffffffffffffffff)
-    else:
-        raise NotImplementedError()
-
-
-if hasattr(int, 'bit_length'):
-    # Not int.bit_length , since that won't work in 2.7 where long exists
-    def _compat_bit_length(i):
-        return i.bit_length()
-else:
-    def _compat_bit_length(i):
-        for res in itertools.count():
-            if i >> res == 0:
-                return res
-
-
-def _compat_range(start, end, step=1):
-    assert step > 0
-    i = start
-    while i < end:
-        yield i
-        i += step
-
-
-class _TotalOrderingMixin(object):
-    __slots__ = ()
-
-    # Helper that derives the other comparison operations from
-    # __lt__ and __eq__
-    # We avoid functools.total_ordering because it doesn't handle
-    # NotImplemented correctly yet (http://bugs.python.org/issue10042)
-    def __eq__(self, other):
-        raise NotImplementedError
-
-    def __ne__(self, other):
-        equal = self.__eq__(other)
-        if equal is NotImplemented:
-            return NotImplemented
-        return not equal
-
-    def __lt__(self, other):
-        raise NotImplementedError
-
-    def __le__(self, other):
-        less = self.__lt__(other)
-        if less is NotImplemented or not less:
-            return self.__eq__(other)
-        return less
-
-    def __gt__(self, other):
-        less = self.__lt__(other)
-        if less is NotImplemented:
-            return NotImplemented
-        equal = self.__eq__(other)
-        if equal is NotImplemented:
-            return NotImplemented
-        return not (less or equal)
-
-    def __ge__(self, other):
-        less = self.__lt__(other)
-        if less is NotImplemented:
-            return NotImplemented
-        return not less
-
-
-IPV4LENGTH = 32
-IPV6LENGTH = 128
-
-
-class AddressValueError(ValueError):
-    """A Value Error related to the address."""
-
-
-class NetmaskValueError(ValueError):
-    """A Value Error related to the netmask."""
-
-
-def ip_address(address):
-    """Take an IP string/int and return an object of the correct type.
-
-    Args:
-        address: A string or integer, the IP address.  Either IPv4 or
-          IPv6 addresses may be supplied; integers less than 2**32 will
-          be considered to be IPv4 by default.
-
-    Returns:
-        An IPv4Address or IPv6Address object.
-
-    Raises:
-        ValueError: if the *address* passed isn't either a v4 or a v6
-          address
-
-    """
-    try:
-        return IPv4Address(address)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    try:
-        return IPv6Address(address)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    if isinstance(address, bytes):
-        raise AddressValueError(
-            '%r does not appear to be an IPv4 or IPv6 address. '
-            'Did you pass in a bytes (str in Python 2) instead of'
-            ' a unicode object?' % address)
-
-    raise ValueError('%r does not appear to be an IPv4 or IPv6 address' %
-                     address)
-
-
-def ip_network(address, strict=True):
-    """Take an IP string/int and return an object of the correct type.
-
-    Args:
-        address: A string or integer, the IP network.  Either IPv4 or
-          IPv6 networks may be supplied; integers less than 2**32 will
-          be considered to be IPv4 by default.
-
-    Returns:
-        An IPv4Network or IPv6Network object.
-
-    Raises:
-        ValueError: if the string passed isn't either a v4 or a v6
-          address. Or if the network has host bits set.
-
-    """
-    try:
-        return IPv4Network(address, strict)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    try:
-        return IPv6Network(address, strict)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    if isinstance(address, bytes):
-        raise AddressValueError(
-            '%r does not appear to be an IPv4 or IPv6 network. '
-            'Did you pass in a bytes (str in Python 2) instead of'
-            ' a unicode object?' % address)
-
-    raise ValueError('%r does not appear to be an IPv4 or IPv6 network' %
-                     address)
-
-
-def ip_interface(address):
-    """Take an IP string/int and return an object of the correct type.
-
-    Args:
-        address: A string or integer, the IP address.  Either IPv4 or
-          IPv6 addresses may be supplied; integers less than 2**32 will
-          be considered to be IPv4 by default.
-
-    Returns:
-        An IPv4Interface or IPv6Interface object.
-
-    Raises:
-        ValueError: if the string passed isn't either a v4 or a v6
-          address.
-
-    Notes:
-        The IPv?Interface classes describe an Address on a particular
-        Network, so they're basically a combination of both the Address
-        and Network classes.
-
-    """
-    try:
-        return IPv4Interface(address)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    try:
-        return IPv6Interface(address)
-    except (AddressValueError, NetmaskValueError):
-        pass
-
-    raise ValueError('%r does not appear to be an IPv4 or IPv6 interface' %
-                     address)
-
-
-def v4_int_to_packed(address):
-    """Represent an address as 4 packed bytes in network (big-endian) order.
-
-    Args:
-        address: An integer representation of an IPv4 IP address.
-
-    Returns:
-        The integer address packed as 4 bytes in network (big-endian) order.
-
-    Raises:
-        ValueError: If the integer is negative or too large to be an
-          IPv4 IP address.
-
-    """
-    try:
-        return _compat_to_bytes(address, 4, 'big')
-    except (struct.error, OverflowError):
-        raise ValueError("Address negative or too large for IPv4")
-
-
-def v6_int_to_packed(address):
-    """Represent an address as 16 packed bytes in network (big-endian) order.
-
-    Args:
-        address: An integer representation of an IPv6 IP address.
-
-    Returns:
-        The integer address packed as 16 bytes in network (big-endian) order.
-
-    """
-    try:
-        return _compat_to_bytes(address, 16, 'big')
-    except (struct.error, OverflowError):
-        raise ValueError("Address negative or too large for IPv6")
-
-
-def _split_optional_netmask(address):
-    """Helper to split the netmask and raise AddressValueError if needed"""
-    addr = _compat_str(address).split('/')
-    if len(addr) > 2:
-        raise AddressValueError("Only one '/' permitted in %r" % address)
-    return addr
-
-
-def _find_address_range(addresses):
-    """Find a sequence of sorted deduplicated IPv#Address.
-
-    Args:
-        addresses: a list of IPv#Address objects.
-
-    Yields:
-        A tuple containing the first and last IP addresses in the sequence.
-
-    """
-    it = iter(addresses)
-    first = last = next(it)
-    for ip in it:
-        if ip._ip != last._ip + 1:
-            yield first, last
-            first = ip
-        last = ip
-    yield first, last
-
-
-def _count_righthand_zero_bits(number, bits):
-    """Count the number of zero bits on the right hand side.
-
-    Args:
-        number: an integer.
-        bits: maximum number of bits to count.
-
-    Returns:
-        The number of zero bits on the right hand side of the number.
-
-    """
-    if number == 0:
-        return bits
-    return min(bits, _compat_bit_length(~number & (number - 1)))
-
-
-def summarize_address_range(first, last):
-    """Summarize a network range given the first and last IP addresses.
-
-    Example:
-        >>> list(summarize_address_range(IPv4Address('192.0.2.0'),
-        ...                              IPv4Address('192.0.2.130')))
-        ...                                #doctest: +NORMALIZE_WHITESPACE
-        [IPv4Network('192.0.2.0/25'), IPv4Network('192.0.2.128/31'),
-         IPv4Network('192.0.2.130/32')]
-
-    Args:
-        first: the first IPv4Address or IPv6Address in the range.
-        last: the last IPv4Address or IPv6Address in the range.
-
-    Returns:
-        An iterator of the summarized IPv(4|6) network objects.
-
-    Raise:
-        TypeError:
-            If the first and last objects are not IP addresses.
-            If the first and last objects are not the same version.
-        ValueError:
-            If the last object is not greater than the first.
-            If the version of the first address is not 4 or 6.
-
-    """
-    if (not (isinstance(first, _BaseAddress) and
-             isinstance(last, _BaseAddress))):
-        raise TypeError('first and last must be IP addresses, not networks')
-    if first.version != last.version:
-        raise TypeError("%s and %s are not of the same version" % (
-                        first, last))
-    if first > last:
-        raise ValueError('last IP address must be greater than first')
-
-    if first.version == 4:
-        ip = IPv4Network
-    elif first.version == 6:
-        ip = IPv6Network
-    else:
-        raise ValueError('unknown IP version')
-
-    ip_bits = first._max_prefixlen
-    first_int = first._ip
-    last_int = last._ip
-    while first_int <= last_int:
-        nbits = min(_count_righthand_zero_bits(first_int, ip_bits),
-                    _compat_bit_length(last_int - first_int + 1) - 1)
-        net = ip((first_int, ip_bits - nbits))
-        yield net
-        first_int += 1 << nbits
-        if first_int - 1 == ip._ALL_ONES:
-            break
-
-
-def _collapse_addresses_internal(addresses):
-    """Loops through the addresses, collapsing concurrent netblocks.
-
-    Example:
-
-        ip1 = IPv4Network('192.0.2.0/26')
-        ip2 = IPv4Network('192.0.2.64/26')
-        ip3 = IPv4Network('192.0.2.128/26')
-        ip4 = IPv4Network('192.0.2.192/26')
-
-        _collapse_addresses_internal([ip1, ip2, ip3, ip4]) ->
-          [IPv4Network('192.0.2.0/24')]
-
-        This shouldn't be called directly; it is called via
-          collapse_addresses([]).
-
-    Args:
-        addresses: A list of IPv4Network's or IPv6Network's
-
-    Returns:
-        A list of IPv4Network's or IPv6Network's depending on what we were
-        passed.
-
-    """
-    # First merge
-    to_merge = list(addresses)
-    subnets = {}
-    while to_merge:
-        net = to_merge.pop()
-        supernet = net.supernet()
-        existing = subnets.get(supernet)
-        if existing is None:
-            subnets[supernet] = net
-        elif existing != net:
-            # Merge consecutive subnets
-            del subnets[supernet]
-            to_merge.append(supernet)
-    # Then iterate over resulting networks, skipping subsumed subnets
-    last = None
-    for net in sorted(subnets.values()):
-        if last is not None:
-            # Since they are sorted,
-            # last.network_address <= net.network_address is a given.
-            if last.broadcast_address >= net.broadcast_address:
-                continue
-        yield net
-        last = net
-
-
-def collapse_addresses(addresses):
-    """Collapse a list of IP objects.
-
-    Example:
-        collapse_addresses([IPv4Network('192.0.2.0/25'),
-                            IPv4Network('192.0.2.128/25')]) ->
-                           [IPv4Network('192.0.2.0/24')]
-
-    Args:
-        addresses: An iterator of IPv4Network or IPv6Network objects.
-
-    Returns:
-        An iterator of the collapsed IPv(4|6)Network objects.
-
-    Raises:
-        TypeError: If passed a list of mixed version objects.
-
-    """
-    addrs = []
-    ips = []
-    nets = []
-
-    # split IP addresses and networks
-    for ip in addresses:
-        if isinstance(ip, _BaseAddress):
-            if ips and ips[-1]._version != ip._version:
-                raise TypeError("%s and %s are not of the same version" % (
-                                ip, ips[-1]))
-            ips.append(ip)
-        elif ip._prefixlen == ip._max_prefixlen:
-            if ips and ips[-1]._version != ip._version:
-                raise TypeError("%s and %s are not of the same version" % (
-                                ip, ips[-1]))
-            try:
-                ips.append(ip.ip)
-            except AttributeError:
-                ips.append(ip.network_address)
-        else:
-            if nets and nets[-1]._version != ip._version:
-                raise TypeError("%s and %s are not of the same version" % (
-                                ip, nets[-1]))
-            nets.append(ip)
-
-    # sort and dedup
-    ips = sorted(set(ips))
-
-    # find consecutive address ranges in the sorted sequence and summarize them
-    if ips:
-        for first, last in _find_address_range(ips):
-            addrs.extend(summarize_address_range(first, last))
-
-    return _collapse_addresses_internal(addrs + nets)
-
-
-def get_mixed_type_key(obj):
-    """Return a key suitable for sorting between networks and addresses.
-
-    Address and Network objects are not sortable by default; they're
-    fundamentally different so the expression
-
-        IPv4Address('192.0.2.0') <= IPv4Network('192.0.2.0/24')
-
-    doesn't make any sense.  There are some times however, where you may wish
-    to have ipaddress sort these for you anyway. If you need to do this, you
-    can use this function as the key= argument to sorted().
-
-    Args:
-      obj: either a Network or Address object.
-    Returns:
-      appropriate key.
-
-    """
-    if isinstance(obj, _BaseNetwork):
-        return obj._get_networks_key()
-    elif isinstance(obj, _BaseAddress):
-        return obj._get_address_key()
-    return NotImplemented
-
-
-class _IPAddressBase(_TotalOrderingMixin):
-
-    """The mother class."""
-
-    __slots__ = ()
-
-    @property
-    def exploded(self):
-        """Return the longhand version of the IP address as a string."""
-        return self._explode_shorthand_ip_string()
-
-    @property
-    def compressed(self):
-        """Return the shorthand version of the IP address as a string."""
-        return _compat_str(self)
-
-    @property
-    def reverse_pointer(self):
-        """The name of the reverse DNS pointer for the IP address, e.g.:
-            >>> ipaddress.ip_address("127.0.0.1").reverse_pointer
-            '1.0.0.127.in-addr.arpa'
-            >>> ipaddress.ip_address("2001:db8::1").reverse_pointer
-            '1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa'
-
-        """
-        return self._reverse_pointer()
-
-    @property
-    def version(self):
-        msg = '%200s has no version specified' % (type(self),)
-        raise NotImplementedError(msg)
-
-    def _check_int_address(self, address):
-        if address < 0:
-            msg = "%d (< 0) is not permitted as an IPv%d address"
-            raise AddressValueError(msg % (address, self._version))
-        if address > self._ALL_ONES:
-            msg = "%d (>= 2**%d) is not permitted as an IPv%d address"
-            raise AddressValueError(msg % (address, self._max_prefixlen,
-                                           self._version))
-
-    def _check_packed_address(self, address, expected_len):
-        address_len = len(address)
-        if address_len != expected_len:
-            msg = (
-                '%r (len %d != %d) is not permitted as an IPv%d address. '
-                'Did you pass in a bytes (str in Python 2) instead of'
-                ' a unicode object?')
-            raise AddressValueError(msg % (address, address_len,
-                                           expected_len, self._version))
-
-    @classmethod
-    def _ip_int_from_prefix(cls, prefixlen):
-        """Turn the prefix length into a bitwise netmask
-
-        Args:
-            prefixlen: An integer, the prefix length.
-
-        Returns:
-            An integer.
-
-        """
-        return cls._ALL_ONES ^ (cls._ALL_ONES >> prefixlen)
-
-    @classmethod
-    def _prefix_from_ip_int(cls, ip_int):
-        """Return prefix length from the bitwise netmask.
-
-        Args:
-            ip_int: An integer, the netmask in expanded bitwise format
-
-        Returns:
-            An integer, the prefix length.
-
-        Raises:
-            ValueError: If the input intermingles zeroes & ones
-        """
-        trailing_zeroes = _count_righthand_zero_bits(ip_int,
-                                                     cls._max_prefixlen)
-        prefixlen = cls._max_prefixlen - trailing_zeroes
-        leading_ones = ip_int >> trailing_zeroes
-        all_ones = (1 << prefixlen) - 1
-        if leading_ones != all_ones:
-            byteslen = cls._max_prefixlen // 8
-            details = _compat_to_bytes(ip_int, byteslen, 'big')
-            msg = 'Netmask pattern %r mixes zeroes & ones'
-            raise ValueError(msg % details)
-        return prefixlen
-
-    @classmethod
-    def _report_invalid_netmask(cls, netmask_str):
-        msg = '%r is not a valid netmask' % netmask_str
-        raise NetmaskValueError(msg)
-
-    @classmethod
-    def _prefix_from_prefix_string(cls, prefixlen_str):
-        """Return prefix length from a numeric string
-
-        Args:
-            prefixlen_str: The string to be converted
-
-        Returns:
-            An integer, the prefix length.
-
-        Raises:
-            NetmaskValueError: If the input is not a valid netmask
-        """
-        # int allows a leading +/- as well as surrounding whitespace,
-        # so we ensure that isn't the case
-        if not _BaseV4._DECIMAL_DIGITS.issuperset(prefixlen_str):
-            cls._report_invalid_netmask(prefixlen_str)
-        try:
-            prefixlen = int(prefixlen_str)
-        except ValueError:
-            cls._report_invalid_netmask(prefixlen_str)
-        if not (0 <= prefixlen <= cls._max_prefixlen):
-            cls._report_invalid_netmask(prefixlen_str)
-        return prefixlen
-
-    @classmethod
-    def _prefix_from_ip_string(cls, ip_str):
-        """Turn a netmask/hostmask string into a prefix length
-
-        Args:
-            ip_str: The netmask/hostmask to be converted
-
-        Returns:
-            An integer, the prefix length.
-
-        Raises:
-            NetmaskValueError: If the input is not a valid netmask/hostmask
-        """
-        # Parse the netmask/hostmask like an IP address.
-        try:
-            ip_int = cls._ip_int_from_string(ip_str)
-        except AddressValueError:
-            cls._report_invalid_netmask(ip_str)
-
-        # Try matching a netmask (this would be /1*0*/ as a bitwise regexp).
-        # Note that the two ambiguous cases (all-ones and all-zeroes) are
-        # treated as netmasks.
-        try:
-            return cls._prefix_from_ip_int(ip_int)
-        except ValueError:
-            pass
-
-        # Invert the bits, and try matching a /0+1+/ hostmask instead.
-        ip_int ^= cls._ALL_ONES
-        try:
-            return cls._prefix_from_ip_int(ip_int)
-        except ValueError:
-            cls._report_invalid_netmask(ip_str)
-
-    def __reduce__(self):
-        return self.__class__, (_compat_str(self),)
-
-
-class _BaseAddress(_IPAddressBase):
-
-    """A generic IP object.
-
-    This IP class contains the version independent methods which are
-    used by single IP addresses.
-    """
-
-    __slots__ = ()
-
-    def __int__(self):
-        return self._ip
-
-    def __eq__(self, other):
-        try:
-            return (self._ip == other._ip and
-                    self._version == other._version)
-        except AttributeError:
-            return NotImplemented
-
-    def __lt__(self, other):
-        if not isinstance(other, _IPAddressBase):
-            return NotImplemented
-        if not isinstance(other, _BaseAddress):
-            raise TypeError('%s and %s are not of the same type' % (
-                self, other))
-        if self._version != other._version:
-            raise TypeError('%s and %s are not of the same version' % (
-                self, other))
-        if self._ip != other._ip:
-            return self._ip < other._ip
-        return False
-
-    # Shorthand for Integer addition and subtraction. This is not
-    # meant to ever support addition/subtraction of addresses.
-    def __add__(self, other):
-        if not isinstance(other, _compat_int_types):
-            return NotImplemented
-        return self.__class__(int(self) + other)
-
-    def __sub__(self, other):
-        if not isinstance(other, _compat_int_types):
-            return NotImplemented
-        return self.__class__(int(self) - other)
-
-    def __repr__(self):
-        return '%s(%r)' % (self.__class__.__name__, _compat_str(self))
-
-    def __str__(self):
-        return _compat_str(self._string_from_ip_int(self._ip))
-
-    def __hash__(self):
-        return hash(hex(int(self._ip)))
-
-    def _get_address_key(self):
-        return (self._version, self)
-
-    def __reduce__(self):
-        return self.__class__, (self._ip,)
-
-
-class _BaseNetwork(_IPAddressBase):
-
-    """A generic IP network object.
-
-    This IP class contains the version independent methods which are
-    used by networks.
-
-    """
-    def __init__(self, address):
-        self._cache = {}
-
-    def __repr__(self):
-        return '%s(%r)' % (self.__class__.__name__, _compat_str(self))
-
-    def __str__(self):
-        return '%s/%d' % (self.network_address, self.prefixlen)
-
-    def hosts(self):
-        """Generate Iterator over usable hosts in a network.
-
-        This is like __iter__ except it doesn't return the network
-        or broadcast addresses.
-
-        """
-        network = int(self.network_address)
-        broadcast = int(self.broadcast_address)
-        for x in _compat_range(network + 1, broadcast):
-            yield self._address_class(x)
-
-    def __iter__(self):
-        network = int(self.network_address)
-        broadcast = int(self.broadcast_address)
-        for x in _compat_range(network, broadcast + 1):
-            yield self._address_class(x)
-
-    def __getitem__(self, n):
-        network = int(self.network_address)
-        broadcast = int(self.broadcast_address)
-        if n >= 0:
-            if network + n > broadcast:
-                raise IndexError('address out of range')
-            return self._address_class(network + n)
-        else:
-            n += 1
-            if broadcast + n < network:
-                raise IndexError('address out of range')
-            return self._address_class(broadcast + n)
-
-    def __lt__(self, other):
-        if not isinstance(other, _IPAddressBase):
-            return NotImplemented
-        if not isinstance(other, _BaseNetwork):
-            raise TypeError('%s and %s are not of the same type' % (
-                            self, other))
-        if self._version != other._version:
-            raise TypeError('%s and %s are not of the same version' % (
-                            self, other))
-        if self.network_address != other.network_address:
-            return self.network_address < other.network_address
-        if self.netmask != other.netmask:
-            return self.netmask < other.netmask
-        return False
-
-    def __eq__(self, other):
-        try:
-            return (self._version == other._version and
-                    self.network_address == other.network_address and
-                    int(self.netmask) == int(other.netmask))
-        except AttributeError:
-            return NotImplemented
-
-    def __hash__(self):
-        return hash(int(self.network_address) ^ int(self.netmask))
-
-    def __contains__(self, other):
-        # always false if one is v4 and the other is v6.
-        if self._version != other._version:
-            return False
-        # dealing with another network.
-        if isinstance(other, _BaseNetwork):
-            return False
-        # dealing with another address
-        else:
-            # address
-            return (int(self.network_address) <= int(other._ip) <=
-                    int(self.broadcast_address))
-
-    def overlaps(self, other):
-        """Tell if self is partly contained in other."""
-        return self.network_address in other or (
-            self.broadcast_address in other or (
-                other.network_address in self or (
-                    other.broadcast_address in self)))
-
-    @property
-    def broadcast_address(self):
-        x = self._cache.get('broadcast_address')
-        if x is None:
-            x = self._address_class(int(self.network_address) |
-                                    int(self.hostmask))
-            self._cache['broadcast_address'] = x
-        return x
-
-    @property
-    def hostmask(self):
-        x = self._cache.get('hostmask')
-        if x is None:
-            x = self._address_class(int(self.netmask) ^ self._ALL_ONES)
-            self._cache['hostmask'] = x
-        return x
-
-    @property
-    def with_prefixlen(self):
-        return '%s/%d' % (self.network_address, self._prefixlen)
-
-    @property
-    def with_netmask(self):
-        return '%s/%s' % (self.network_address, self.netmask)
-
-    @property
-    def with_hostmask(self):
-        return '%s/%s' % (self.network_address, self.hostmask)
-
-    @property
-    def num_addresses(self):
-        """Number of hosts in the current subnet."""
-        return int(self.broadcast_address) - int(self.network_address) + 1
-
-    @property
-    def _address_class(self):
-        # Returning bare address objects (rather than interfaces) allows for
-        # more consistent behaviour across the network address, broadcast
-        # address and individual host addresses.
-        msg = '%200s has no associated address class' % (type(self),)
-        raise NotImplementedError(msg)
-
-    @property
-    def prefixlen(self):
-        return self._prefixlen
-
-    def address_exclude(self, other):
-        """Remove an address from a larger block.
-
-        For example:
-
-            addr1 = ip_network('192.0.2.0/28')
-            addr2 = ip_network('192.0.2.1/32')
-            list(addr1.address_exclude(addr2)) =
-                [IPv4Network('192.0.2.0/32'), IPv4Network('192.0.2.2/31'),
-                 IPv4Network('192.0.2.4/30'), IPv4Network('192.0.2.8/29')]
-
-        or IPv6:
-
-            addr1 = ip_network('2001:db8::1/32')
-            addr2 = ip_network('2001:db8::1/128')
-            list(addr1.address_exclude(addr2)) =
-                [ip_network('2001:db8::1/128'),
-                 ip_network('2001:db8::2/127'),
-                 ip_network('2001:db8::4/126'),
-                 ip_network('2001:db8::8/125'),
-                 ...
-                 ip_network('2001:db8:8000::/33')]
-
-        Args:
-            other: An IPv4Network or IPv6Network object of the same type.
-
-        Returns:
-            An iterator of the IPv(4|6)Network objects which is self
-            minus other.
-
-        Raises:
-            TypeError: If self and other are of differing address
-              versions, or if other is not a network object.
-            ValueError: If other is not completely contained by self.
-
-        """
-        if not self._version == other._version:
-            raise TypeError("%s and %s are not of the same version" % (
-                            self, other))
-
-        if not isinstance(other, _BaseNetwork):
-            raise TypeError("%s is not a network object" % other)
-
-        if not other.subnet_of(self):
-            raise ValueError('%s not contained in %s' % (other, self))
-        if other == self:
-            return
-
-        # Make sure we're comparing the network of other.
-        other = other.__class__('%s/%s' % (other.network_address,
-                                           other.prefixlen))
-
-        s1, s2 = self.subnets()
-        while s1 != other and s2 != other:
-            if other.subnet_of(s1):
-                yield s2
-                s1, s2 = s1.subnets()
-            elif other.subnet_of(s2):
-                yield s1
-                s1, s2 = s2.subnets()
-            else:
-                # If we got here, there's a bug somewhere.
-                raise AssertionError('Error performing exclusion: '
-                                     's1: %s s2: %s other: %s' %
-                                     (s1, s2, other))
-        if s1 == other:
-            yield s2
-        elif s2 == other:
-            yield s1
-        else:
-            # If we got here, there's a bug somewhere.
-            raise AssertionError('Error performing exclusion: '
-                                 's1: %s s2: %s other: %s' %
-                                 (s1, s2, other))
-
-    def compare_networks(self, other):
-        """Compare two IP objects.
-
-        This is only concerned about the comparison of the integer
-        representation of the network addresses.  This means that the
-        host bits aren't considered at all in this method.  If you want
-        to compare host bits, you can easily enough do a
-        'HostA._ip < HostB._ip'
-
-        Args:
-            other: An IP object.
-
-        Returns:
-            If the IP versions of self and other are the same, returns:
-
-            -1 if self < other:
-              eg: IPv4Network('192.0.2.0/25') < IPv4Network('192.0.2.128/25')
-              IPv6Network('2001:db8::1000/124') <
-                  IPv6Network('2001:db8::2000/124')
-            0 if self == other
-              eg: IPv4Network('192.0.2.0/24') == IPv4Network('192.0.2.0/24')
-              IPv6Network('2001:db8::1000/124') ==
-                  IPv6Network('2001:db8::1000/124')
-            1 if self > other
-              eg: IPv4Network('192.0.2.128/25') > IPv4Network('192.0.2.0/25')
-                  IPv6Network('2001:db8::2000/124') >
-                      IPv6Network('2001:db8::1000/124')
-
-          Raises:
-              TypeError if the IP versions are different.
-
-        """
-        # does this need to raise a ValueError?
-        if self._version != other._version:
-            raise TypeError('%s and %s are not of the same type' % (
-                            self, other))
-        # self._version == other._version below here:
-        if self.network_address < other.network_address:
-            return -1
-        if self.network_address > other.network_address:
-            return 1
-        # self.network_address == other.network_address below here:
-        if self.netmask < other.netmask:
-            return -1
-        if self.netmask > other.netmask:
-            return 1
-        return 0
-
-    def _get_networks_key(self):
-        """Network-only key function.
-
-        Returns an object that identifies this address' network and
-        netmask. This function is a suitable "key" argument for sorted()
-        and list.sort().
-
-        """
-        return (self._version, self.network_address, self.netmask)
-
-    def subnets(self, prefixlen_diff=1, new_prefix=None):
-        """The subnets which join to make the current subnet.
-
-        In the case that self contains only one IP
-        (self._prefixlen == 32 for IPv4 or self._prefixlen == 128
-        for IPv6), yield an iterator with just ourself.
-
-        Args:
-            prefixlen_diff: An integer, the amount the prefix length
-              should be increased by. This should not be set if
-              new_prefix is also set.
-            new_prefix: The desired new prefix length. This must be a
-              larger number (smaller prefix) than the existing prefix.
-              This should not be set if prefixlen_diff is also set.
-
-        Returns:
-            An iterator of IPv(4|6) objects.
-
-        Raises:
-            ValueError: The prefixlen_diff is too small or too large.
-                OR
-            prefixlen_diff and new_prefix are both set or new_prefix
-              is a smaller number than the current prefix (smaller
-              number means a larger network)
-
-        """
-        if self._prefixlen == self._max_prefixlen:
-            yield self
-            return
-
-        if new_prefix is not None:
-            if new_prefix < self._prefixlen:
-                raise ValueError('new prefix must be longer')
-            if prefixlen_diff != 1:
-                raise ValueError('cannot set prefixlen_diff and new_prefix')
-            prefixlen_diff = new_prefix - self._prefixlen
-
-        if prefixlen_diff < 0:
-            raise ValueError('prefix length diff must be > 0')
-        new_prefixlen = self._prefixlen + prefixlen_diff
-
-        if new_prefixlen > self._max_prefixlen:
-            raise ValueError(
-                'prefix length diff %d is invalid for netblock %s' % (
-                    new_prefixlen, self))
-
-        start = int(self.network_address)
-        end = int(self.broadcast_address) + 1
-        step = (int(self.hostmask) + 1) >> prefixlen_diff
-        for new_addr in _compat_range(start, end, step):
-            current = self.__class__((new_addr, new_prefixlen))
-            yield current
-
-    def supernet(self, prefixlen_diff=1, new_prefix=None):
-        """The supernet containing the current network.
-
-        Args:
-            prefixlen_diff: An integer, the amount the prefix length of
-              the network should be decreased by.  For example, given a
-              /24 network and a prefixlen_diff of 3, a supernet with a
-              /21 netmask is returned.
-
-        Returns:
-            An IPv4 network object.
-
-        Raises:
-            ValueError: If self.prefixlen - prefixlen_diff < 0. I.e., you have
-              a negative prefix length.
-                OR
-            If prefixlen_diff and new_prefix are both set or new_prefix is a
-              larger number than the current prefix (larger number means a
-              smaller network)
-
-        """
-        if self._prefixlen == 0:
-            return self
-
-        if new_prefix is not None:
-            if new_prefix > self._prefixlen:
-                raise ValueError('new prefix must be shorter')
-            if prefixlen_diff != 1:
-                raise ValueError('cannot set prefixlen_diff and new_prefix')
-            prefixlen_diff = self._prefixlen - new_prefix
-
-        new_prefixlen = self.prefixlen - prefixlen_diff
-        if new_prefixlen < 0:
-            raise ValueError(
-                'current prefixlen is %d, cannot have a prefixlen_diff of %d' %
-                (self.prefixlen, prefixlen_diff))
-        return self.__class__((
-            int(self.network_address) & (int(self.netmask) << prefixlen_diff),
-            new_prefixlen))
-
-    @property
-    def is_multicast(self):
-        """Test if the address is reserved for multicast use.
-
-        Returns:
-            A boolean, True if the address is a multicast address.
-            See RFC 2373 2.7 for details.
-
-        """
-        return (self.network_address.is_multicast and
-                self.broadcast_address.is_multicast)
-
-    @staticmethod
-    def _is_subnet_of(a, b):
-        try:
-            # Always false if one is v4 and the other is v6.
-            if a._version != b._version:
-                raise TypeError(
-                    "%s and %s are not of the same version" % (a, b))
-            return (b.network_address <= a.network_address and
-                    b.broadcast_address >= a.broadcast_address)
-        except AttributeError:
-            raise TypeError("Unable to test subnet containment "
-                            "between %s and %s" % (a, b))
-
-    def subnet_of(self, other):
-        """Return True if this network is a subnet of other."""
-        return self._is_subnet_of(self, other)
-
-    def supernet_of(self, other):
-        """Return True if this network is a supernet of other."""
-        return self._is_subnet_of(other, self)
-
-    @property
-    def is_reserved(self):
-        """Test if the address is otherwise IETF reserved.
-
-        Returns:
-            A boolean, True if the address is within one of the
-            reserved IPv6 Network ranges.
-
-        """
-        return (self.network_address.is_reserved and
-                self.broadcast_address.is_reserved)
-
-    @property
-    def is_link_local(self):
-        """Test if the address is reserved for link-local.
-
-        Returns:
-            A boolean, True if the address is reserved per RFC 4291.
-
-        """
-        return (self.network_address.is_link_local and
-                self.broadcast_address.is_link_local)
-
-    @property
-    def is_private(self):
-        """Test if this address is allocated for private networks.
-
-        Returns:
-            A boolean, True if the address is reserved per
-            iana-ipv4-special-registry or iana-ipv6-special-registry.
-
-        """
-        return (self.network_address.is_private and
-                self.broadcast_address.is_private)
-
-    @property
-    def is_global(self):
-        """Test if this address is allocated for public networks.
-
-        Returns:
-            A boolean, True if the address is not reserved per
-            iana-ipv4-special-registry or iana-ipv6-special-registry.
-
-        """
-        return not self.is_private
-
-    @property
-    def is_unspecified(self):
-        """Test if the address is unspecified.
-
-        Returns:
-            A boolean, True if this is the unspecified address as defined in
-            RFC 2373 2.5.2.
-
-        """
-        return (self.network_address.is_unspecified and
-                self.broadcast_address.is_unspecified)
-
-    @property
-    def is_loopback(self):
-        """Test if the address is a loopback address.
-
-        Returns:
-            A boolean, True if the address is a loopback address as defined in
-            RFC 2373 2.5.3.
-
-        """
-        return (self.network_address.is_loopback and
-                self.broadcast_address.is_loopback)
-
-
-class _BaseV4(object):
-
-    """Base IPv4 object.
-
-    The following methods are used by IPv4 objects in both single IP
-    addresses and networks.
-
-    """
-
-    __slots__ = ()
-    _version = 4
-    # Equivalent to 255.255.255.255 or 32 bits of 1's.
-    _ALL_ONES = (2 ** IPV4LENGTH) - 1
-    _DECIMAL_DIGITS = frozenset('0123456789')
-
-    # the valid octets for host and netmasks. only useful for IPv4.
-    _valid_mask_octets = frozenset([255, 254, 252, 248, 240, 224, 192, 128, 0])
-
-    _max_prefixlen = IPV4LENGTH
-    # There are only a handful of valid v4 netmasks, so we cache them all
-    # when constructed (see _make_netmask()).
-    _netmask_cache = {}
-
-    def _explode_shorthand_ip_string(self):
-        return _compat_str(self)
-
-    @classmethod
-    def _make_netmask(cls, arg):
-        """Make a (netmask, prefix_len) tuple from the given argument.
-
-        Argument can be:
-        - an integer (the prefix length)
-        - a string representing the prefix length (e.g. "24")
-        - a string representing the prefix netmask (e.g. "255.255.255.0")
-        """
-        if arg not in cls._netmask_cache:
-            if isinstance(arg, _compat_int_types):
-                prefixlen = arg
-            else:
-                try:
-                    # Check for a netmask in prefix length form
-                    prefixlen = cls._prefix_from_prefix_string(arg)
-                except NetmaskValueError:
-                    # Check for a netmask or hostmask in dotted-quad form.
-                    # This may raise NetmaskValueError.
-                    prefixlen = cls._prefix_from_ip_string(arg)
-            netmask = IPv4Address(cls._ip_int_from_prefix(prefixlen))
-            cls._netmask_cache[arg] = netmask, prefixlen
-        return cls._netmask_cache[arg]
-
-    @classmethod
-    def _ip_int_from_string(cls, ip_str):
-        """Turn the given IP string into an integer for comparison.
-
-        Args:
-            ip_str: A string, the IP ip_str.
-
-        Returns:
-            The IP ip_str as an integer.
-
-        Raises:
-            AddressValueError: if ip_str isn't a valid IPv4 Address.
-
-        """
-        if not ip_str:
-            raise AddressValueError('Address cannot be empty')
-
-        octets = ip_str.split('.')
-        if len(octets) != 4:
-            raise AddressValueError("Expected 4 octets in %r" % ip_str)
-
-        try:
-            return _compat_int_from_byte_vals(
-                map(cls._parse_octet, octets), 'big')
-        except ValueError as exc:
-            raise AddressValueError("%s in %r" % (exc, ip_str))
-
-    @classmethod
-    def _parse_octet(cls, octet_str):
-        """Convert a decimal octet into an integer.
-
-        Args:
-            octet_str: A string, the number to parse.
-
-        Returns:
-            The octet as an integer.
-
-        Raises:
-            ValueError: if the octet isn't strictly a decimal from [0..255].
-
-        """
-        if not octet_str:
-            raise ValueError("Empty octet not permitted")
-        # Whitelist the characters, since int() allows a lot of bizarre stuff.
-        if not cls._DECIMAL_DIGITS.issuperset(octet_str):
-            msg = "Only decimal digits permitted in %r"
-            raise ValueError(msg % octet_str)
-        # We do the length check second, since the invalid character error
-        # is likely to be more informative for the user
-        if len(octet_str) > 3:
-            msg = "At most 3 characters permitted in %r"
-            raise ValueError(msg % octet_str)
-        # Convert to integer (we know digits are legal)
-        octet_int = int(octet_str, 10)
-        # Any octets that look like they *might* be written in octal,
-        # and which don't look exactly the same in both octal and
-        # decimal are rejected as ambiguous
-        if octet_int > 7 and octet_str[0] == '0':
-            msg = "Ambiguous (octal/decimal) value in %r not permitted"
-            raise ValueError(msg % octet_str)
-        if octet_int > 255:
-            raise ValueError("Octet %d (> 255) not permitted" % octet_int)
-        return octet_int
-
-    @classmethod
-    def _string_from_ip_int(cls, ip_int):
-        """Turns a 32-bit integer into dotted decimal notation.
-
-        Args:
-            ip_int: An integer, the IP address.
-
-        Returns:
-            The IP address as a string in dotted decimal notation.
-
-        """
-        return '.'.join(_compat_str(struct.unpack(b'!B', b)[0]
-                                    if isinstance(b, bytes)
-                                    else b)
-                        for b in _compat_to_bytes(ip_int, 4, 'big'))
-
-    def _is_hostmask(self, ip_str):
-        """Test if the IP string is a hostmask (rather than a netmask).
-
-        Args:
-            ip_str: A string, the potential hostmask.
-
-        Returns:
-            A boolean, True if the IP string is a hostmask.
-
-        """
-        bits = ip_str.split('.')
-        try:
-            parts = [x for x in map(int, bits) if x in self._valid_mask_octets]
-        except ValueError:
-            return False
-        if len(parts) != len(bits):
-            return False
-        if parts[0] < parts[-1]:
-            return True
-        return False
-
-    def _reverse_pointer(self):
-        """Return the reverse DNS pointer name for the IPv4 address.
-
-        This implements the method described in RFC1035 3.5.
-
-        """
-        reverse_octets = _compat_str(self).split('.')[::-1]
-        return '.'.join(reverse_octets) + '.in-addr.arpa'
-
-    @property
-    def max_prefixlen(self):
-        return self._max_prefixlen
-
-    @property
-    def version(self):
-        return self._version
-
-
-class IPv4Address(_BaseV4, _BaseAddress):
-
-    """Represent and manipulate single IPv4 Addresses."""
-
-    __slots__ = ('_ip', '__weakref__')
-
-    def __init__(self, address):
-
-        """
-        Args:
-            address: A string or integer representing the IP
-
-              Additionally, an integer can be passed, so
-              IPv4Address('192.0.2.1') == IPv4Address(3221225985).
-              or, more generally
-              IPv4Address(int(IPv4Address('192.0.2.1'))) ==
-                IPv4Address('192.0.2.1')
-
-        Raises:
-            AddressValueError: If ipaddress isn't a valid IPv4 address.
-
-        """
-        # Efficient constructor from integer.
-        if isinstance(address, _compat_int_types):
-            self._check_int_address(address)
-            self._ip = address
-            return
-
-        # Constructing from a packed address
-        if isinstance(address, bytes):
-            self._check_packed_address(address, 4)
-            bvs = _compat_bytes_to_byte_vals(address)
-            self._ip = _compat_int_from_byte_vals(bvs, 'big')
-            return
-
-        # Assume input argument to be string or any object representation
-        # which converts into a formatted IP string.
-        addr_str = _compat_str(address)
-        if '/' in addr_str:
-            raise AddressValueError("Unexpected '/' in %r" % address)
-        self._ip = self._ip_int_from_string(addr_str)
-
-    @property
-    def packed(self):
-        """The binary representation of this address."""
-        return v4_int_to_packed(self._ip)
-
-    @property
-    def is_reserved(self):
-        """Test if the address is otherwise IETF reserved.
-
-         Returns:
-             A boolean, True if the address is within the
-             reserved IPv4 Network range.
-
-        """
-        return self in self._constants._reserved_network
-
-    @property
-    def is_private(self):
-        """Test if this address is allocated for private networks.
-
-        Returns:
-            A boolean, True if the address is reserved per
-            iana-ipv4-special-registry.
-
-        """
-        return any(self in net for net in self._constants._private_networks)
-
-    @property
-    def is_global(self):
-        return (
-            self not in self._constants._public_network and
-            not self.is_private)
-
-    @property
-    def is_multicast(self):
-        """Test if the address is reserved for multicast use.
-
-        Returns:
-            A boolean, True if the address is multicast.
-            See RFC 3171 for details.
-
-        """
-        return self in self._constants._multicast_network
-
-    @property
-    def is_unspecified(self):
-        """Test if the address is unspecified.
-
-        Returns:
-            A boolean, True if this is the unspecified address as defined in
-            RFC 5735 3.
-
-        """
-        return self == self._constants._unspecified_address
-
-    @property
-    def is_loopback(self):
-        """Test if the address is a loopback address.
-
-        Returns:
-            A boolean, True if the address is a loopback per RFC 3330.
-
-        """
-        return self in self._constants._loopback_network
-
-    @property
-    def is_link_local(self):
-        """Test if the address is reserved for link-local.
-
-        Returns:
-            A boolean, True if the address is link-local per RFC 3927.
-
-        """
-        return self in self._constants._linklocal_network
-
-
-class IPv4Interface(IPv4Address):
-
-    def __init__(self, address):
-        if isinstance(address, (bytes, _compat_int_types)):
-            IPv4Address.__init__(self, address)
-            self.network = IPv4Network(self._ip)
-            self._prefixlen = self._max_prefixlen
-            return
-
-        if isinstance(address, tuple):
-            IPv4Address.__init__(self, address[0])
-            if len(address) > 1:
-                self._prefixlen = int(address[1])
-            else:
-                self._prefixlen = self._max_prefixlen
-
-            self.network = IPv4Network(address, strict=False)
-            self.netmask = self.network.netmask
-            self.hostmask = self.network.hostmask
-            return
-
-        addr = _split_optional_netmask(address)
-        IPv4Address.__init__(self, addr[0])
-
-        self.network = IPv4Network(address, strict=False)
-        self._prefixlen = self.network._prefixlen
-
-        self.netmask = self.network.netmask
-        self.hostmask = self.network.hostmask
-
-    def __str__(self):
-        return '%s/%d' % (self._string_from_ip_int(self._ip),
-                          self.network.prefixlen)
-
-    def __eq__(self, other):
-        address_equal = IPv4Address.__eq__(self, other)
-        if not address_equal or address_equal is NotImplemented:
-            return address_equal
-        try:
-            return self.network == other.network
-        except AttributeError:
-            # An interface with an associated network is NOT the
-            # same as an unassociated address. That's why the hash
-            # takes the extra info into account.
-            return False
-
-    def __lt__(self, other):
-        address_less = IPv4Address.__lt__(self, other)
-        if address_less is NotImplemented:
-            return NotImplemented
-        try:
-            return (self.network < other.network or
-                    self.network == other.network and address_less)
-        except AttributeError:
-            # We *do* allow addresses and interfaces to be sorted. The
-            # unassociated address is considered less than all interfaces.
-            return False
-
-    def __hash__(self):
-        return self._ip ^ self._prefixlen ^ int(self.network.network_address)
-
-    __reduce__ = _IPAddressBase.__reduce__
-
-    @property
-    def ip(self):
-        return IPv4Address(self._ip)
-
-    @property
-    def with_prefixlen(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self._prefixlen)
-
-    @property
-    def with_netmask(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self.netmask)
-
-    @property
-    def with_hostmask(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self.hostmask)
-
-
-class IPv4Network(_BaseV4, _BaseNetwork):
-
-    """This class represents and manipulates 32-bit IPv4 network + addresses..
-
-    Attributes: [examples for IPv4Network('192.0.2.0/27')]
-        .network_address: IPv4Address('192.0.2.0')
-        .hostmask: IPv4Address('0.0.0.31')
-        .broadcast_address: IPv4Address('192.0.2.32')
-        .netmask: IPv4Address('255.255.255.224')
-        .prefixlen: 27
-
-    """
-    # Class to use when creating address objects
-    _address_class = IPv4Address
-
-    def __init__(self, address, strict=True):
-
-        """Instantiate a new IPv4 network object.
-
-        Args:
-            address: A string or integer representing the IP [& network].
-              '192.0.2.0/24'
-              '192.0.2.0/255.255.255.0'
-              '192.0.0.2/0.0.0.255'
-              are all functionally the same in IPv4. Similarly,
-              '192.0.2.1'
-              '192.0.2.1/255.255.255.255'
-              '192.0.2.1/32'
-              are also functionally equivalent. That is to say, failing to
-              provide a subnetmask will create an object with a mask of /32.
-
-              If the mask (portion after the / in the argument) is given in
-              dotted quad form, it is treated as a netmask if it starts with a
-              non-zero field (e.g. /255.0.0.0 == /8) and as a hostmask if it
-              starts with a zero field (e.g. 0.255.255.255 == /8), with the
-              single exception of an all-zero mask which is treated as a
-              netmask == /0. If no mask is given, a default of /32 is used.
-
-              Additionally, an integer can be passed, so
-              IPv4Network('192.0.2.1') == IPv4Network(3221225985)
-              or, more generally
-              IPv4Interface(int(IPv4Interface('192.0.2.1'))) ==
-                IPv4Interface('192.0.2.1')
-
-        Raises:
-            AddressValueError: If ipaddress isn't a valid IPv4 address.
-            NetmaskValueError: If the netmask isn't valid for
-              an IPv4 address.
-            ValueError: If strict is True and a network address is not
-              supplied.
-
-        """
-        _BaseNetwork.__init__(self, address)
-
-        # Constructing from a packed address or integer
-        if isinstance(address, (_compat_int_types, bytes)):
-            self.network_address = IPv4Address(address)
-            self.netmask, self._prefixlen = self._make_netmask(
-                self._max_prefixlen)
-            # fixme: address/network test here.
-            return
-
-        if isinstance(address, tuple):
-            if len(address) > 1:
-                arg = address[1]
-            else:
-                # We weren't given an address[1]
-                arg = self._max_prefixlen
-            self.network_address = IPv4Address(address[0])
-            self.netmask, self._prefixlen = self._make_netmask(arg)
-            packed = int(self.network_address)
-            if packed & int(self.netmask) != packed:
-                if strict:
-                    raise ValueError('%s has host bits set' % self)
-                else:
-                    self.network_address = IPv4Address(packed &
-                                                       int(self.netmask))
-            return
-
-        # Assume input argument to be string or any object representation
-        # which converts into a formatted IP prefix string.
-        addr = _split_optional_netmask(address)
-        self.network_address = IPv4Address(self._ip_int_from_string(addr[0]))
-
-        if len(addr) == 2:
-            arg = addr[1]
-        else:
-            arg = self._max_prefixlen
-        self.netmask, self._prefixlen = self._make_netmask(arg)
-
-        if strict:
-            if (IPv4Address(int(self.network_address) & int(self.netmask)) !=
-                    self.network_address):
-                raise ValueError('%s has host bits set' % self)
-        self.network_address = IPv4Address(int(self.network_address) &
-                                           int(self.netmask))
-
-        if self._prefixlen == (self._max_prefixlen - 1):
-            self.hosts = self.__iter__
-
-    @property
-    def is_global(self):
-        """Test if this address is allocated for public networks.
-
-        Returns:
-            A boolean, True if the address is not reserved per
-            iana-ipv4-special-registry.
-
-        """
-        return (not (self.network_address in IPv4Network('100.64.0.0/10') and
-                self.broadcast_address in IPv4Network('100.64.0.0/10')) and
-                not self.is_private)
-
-
-class _IPv4Constants(object):
-
-    _linklocal_network = IPv4Network('169.254.0.0/16')
-
-    _loopback_network = IPv4Network('127.0.0.0/8')
-
-    _multicast_network = IPv4Network('224.0.0.0/4')
-
-    _public_network = IPv4Network('100.64.0.0/10')
-
-    _private_networks = [
-        IPv4Network('0.0.0.0/8'),
-        IPv4Network('10.0.0.0/8'),
-        IPv4Network('127.0.0.0/8'),
-        IPv4Network('169.254.0.0/16'),
-        IPv4Network('172.16.0.0/12'),
-        IPv4Network('192.0.0.0/29'),
-        IPv4Network('192.0.0.170/31'),
-        IPv4Network('192.0.2.0/24'),
-        IPv4Network('192.168.0.0/16'),
-        IPv4Network('198.18.0.0/15'),
-        IPv4Network('198.51.100.0/24'),
-        IPv4Network('203.0.113.0/24'),
-        IPv4Network('240.0.0.0/4'),
-        IPv4Network('255.255.255.255/32'),
-    ]
-
-    _reserved_network = IPv4Network('240.0.0.0/4')
-
-    _unspecified_address = IPv4Address('0.0.0.0')
-
-
-IPv4Address._constants = _IPv4Constants
-
-
-class _BaseV6(object):
-
-    """Base IPv6 object.
-
-    The following methods are used by IPv6 objects in both single IP
-    addresses and networks.
-
-    """
-
-    __slots__ = ()
-    _version = 6
-    _ALL_ONES = (2 ** IPV6LENGTH) - 1
-    _HEXTET_COUNT = 8
-    _HEX_DIGITS = frozenset('0123456789ABCDEFabcdef')
-    _max_prefixlen = IPV6LENGTH
-
-    # There are only a bunch of valid v6 netmasks, so we cache them all
-    # when constructed (see _make_netmask()).
-    _netmask_cache = {}
-
-    @classmethod
-    def _make_netmask(cls, arg):
-        """Make a (netmask, prefix_len) tuple from the given argument.
-
-        Argument can be:
-        - an integer (the prefix length)
-        - a string representing the prefix length (e.g. "24")
-        - a string representing the prefix netmask (e.g. "255.255.255.0")
-        """
-        if arg not in cls._netmask_cache:
-            if isinstance(arg, _compat_int_types):
-                prefixlen = arg
-            else:
-                prefixlen = cls._prefix_from_prefix_string(arg)
-            netmask = IPv6Address(cls._ip_int_from_prefix(prefixlen))
-            cls._netmask_cache[arg] = netmask, prefixlen
-        return cls._netmask_cache[arg]
-
-    @classmethod
-    def _ip_int_from_string(cls, ip_str):
-        """Turn an IPv6 ip_str into an integer.
-
-        Args:
-            ip_str: A string, the IPv6 ip_str.
-
-        Returns:
-            An int, the IPv6 address
-
-        Raises:
-            AddressValueError: if ip_str isn't a valid IPv6 Address.
-
-        """
-        if not ip_str:
-            raise AddressValueError('Address cannot be empty')
-
-        parts = ip_str.split(':')
-
-        # An IPv6 address needs at least 2 colons (3 parts).
-        _min_parts = 3
-        if len(parts) < _min_parts:
-            msg = "At least %d parts expected in %r" % (_min_parts, ip_str)
-            raise AddressValueError(msg)
-
-        # If the address has an IPv4-style suffix, convert it to hexadecimal.
-        if '.' in parts[-1]:
-            try:
-                ipv4_int = IPv4Address(parts.pop())._ip
-            except AddressValueError as exc:
-                raise AddressValueError("%s in %r" % (exc, ip_str))
-            parts.append('%x' % ((ipv4_int >> 16) & 0xFFFF))
-            parts.append('%x' % (ipv4_int & 0xFFFF))
-
-        # An IPv6 address can't have more than 8 colons (9 parts).
-        # The extra colon comes from using the "::" notation for a single
-        # leading or trailing zero part.
-        _max_parts = cls._HEXTET_COUNT + 1
-        if len(parts) > _max_parts:
-            msg = "At most %d colons permitted in %r" % (
-                _max_parts - 1, ip_str)
-            raise AddressValueError(msg)
-
-        # Disregarding the endpoints, find '::' with nothing in between.
-        # This indicates that a run of zeroes has been skipped.
-        skip_index = None
-        for i in _compat_range(1, len(parts) - 1):
-            if not parts[i]:
-                if skip_index is not None:
-                    # Can't have more than one '::'
-                    msg = "At most one '::' permitted in %r" % ip_str
-                    raise AddressValueError(msg)
-                skip_index = i
-
-        # parts_hi is the number of parts to copy from above/before the '::'
-        # parts_lo is the number of parts to copy from below/after the '::'
-        if skip_index is not None:
-            # If we found a '::', then check if it also covers the endpoints.
-            parts_hi = skip_index
-            parts_lo = len(parts) - skip_index - 1
-            if not parts[0]:
-                parts_hi -= 1
-                if parts_hi:
-                    msg = "Leading ':' only permitted as part of '::' in %r"
-                    raise AddressValueError(msg % ip_str)  # ^: requires ^::
-            if not parts[-1]:
-                parts_lo -= 1
-                if parts_lo:
-                    msg = "Trailing ':' only permitted as part of '::' in %r"
-                    raise AddressValueError(msg % ip_str)  # :$ requires ::$
-            parts_skipped = cls._HEXTET_COUNT - (parts_hi + parts_lo)
-            if parts_skipped < 1:
-                msg = "Expected at most %d other parts with '::' in %r"
-                raise AddressValueError(msg % (cls._HEXTET_COUNT - 1, ip_str))
-        else:
-            # Otherwise, allocate the entire address to parts_hi.  The
-            # endpoints could still be empty, but _parse_hextet() will check
-            # for that.
-            if len(parts) != cls._HEXTET_COUNT:
-                msg = "Exactly %d parts expected without '::' in %r"
-                raise AddressValueError(msg % (cls._HEXTET_COUNT, ip_str))
-            if not parts[0]:
-                msg = "Leading ':' only permitted as part of '::' in %r"
-                raise AddressValueError(msg % ip_str)  # ^: requires ^::
-            if not parts[-1]:
-                msg = "Trailing ':' only permitted as part of '::' in %r"
-                raise AddressValueError(msg % ip_str)  # :$ requires ::$
-            parts_hi = len(parts)
-            parts_lo = 0
-            parts_skipped = 0
-
-        try:
-            # Now, parse the hextets into a 128-bit integer.
-            ip_int = 0
-            for i in range(parts_hi):
-                ip_int <<= 16
-                ip_int |= cls._parse_hextet(parts[i])
-            ip_int <<= 16 * parts_skipped
-            for i in range(-parts_lo, 0):
-                ip_int <<= 16
-                ip_int |= cls._parse_hextet(parts[i])
-            return ip_int
-        except ValueError as exc:
-            raise AddressValueError("%s in %r" % (exc, ip_str))
-
-    @classmethod
-    def _parse_hextet(cls, hextet_str):
-        """Convert an IPv6 hextet string into an integer.
-
-        Args:
-            hextet_str: A string, the number to parse.
-
-        Returns:
-            The hextet as an integer.
-
-        Raises:
-            ValueError: if the input isn't strictly a hex number from
-              [0..FFFF].
-
-        """
-        # Whitelist the characters, since int() allows a lot of bizarre stuff.
-        if not cls._HEX_DIGITS.issuperset(hextet_str):
-            raise ValueError("Only hex digits permitted in %r" % hextet_str)
-        # We do the length check second, since the invalid character error
-        # is likely to be more informative for the user
-        if len(hextet_str) > 4:
-            msg = "At most 4 characters permitted in %r"
-            raise ValueError(msg % hextet_str)
-        # Length check means we can skip checking the integer value
-        return int(hextet_str, 16)
-
-    @classmethod
-    def _compress_hextets(cls, hextets):
-        """Compresses a list of hextets.
-
-        Compresses a list of strings, replacing the longest continuous
-        sequence of "0" in the list with "" and adding empty strings at
-        the beginning or at the end of the string such that subsequently
-        calling ":".join(hextets) will produce the compressed version of
-        the IPv6 address.
-
-        Args:
-            hextets: A list of strings, the hextets to compress.
-
-        Returns:
-            A list of strings.
-
-        """
-        best_doublecolon_start = -1
-        best_doublecolon_len = 0
-        doublecolon_start = -1
-        doublecolon_len = 0
-        for index, hextet in enumerate(hextets):
-            if hextet == '0':
-                doublecolon_len += 1
-                if doublecolon_start == -1:
-                    # Start of a sequence of zeros.
-                    doublecolon_start = index
-                if doublecolon_len > best_doublecolon_len:
-                    # This is the longest sequence of zeros so far.
-                    best_doublecolon_len = doublecolon_len
-                    best_doublecolon_start = doublecolon_start
-            else:
-                doublecolon_len = 0
-                doublecolon_start = -1
-
-        if best_doublecolon_len > 1:
-            best_doublecolon_end = (best_doublecolon_start +
-                                    best_doublecolon_len)
-            # For zeros at the end of the address.
-            if best_doublecolon_end == len(hextets):
-                hextets += ['']
-            hextets[best_doublecolon_start:best_doublecolon_end] = ['']
-            # For zeros at the beginning of the address.
-            if best_doublecolon_start == 0:
-                hextets = [''] + hextets
-
-        return hextets
-
-    @classmethod
-    def _string_from_ip_int(cls, ip_int=None):
-        """Turns a 128-bit integer into hexadecimal notation.
-
-        Args:
-            ip_int: An integer, the IP address.
-
-        Returns:
-            A string, the hexadecimal representation of the address.
-
-        Raises:
-            ValueError: The address is bigger than 128 bits of all ones.
-
-        """
-        if ip_int is None:
-            ip_int = int(cls._ip)
-
-        if ip_int > cls._ALL_ONES:
-            raise ValueError('IPv6 address is too large')
-
-        hex_str = '%032x' % ip_int
-        hextets = ['%x' % int(hex_str[x:x + 4], 16) for x in range(0, 32, 4)]
-
-        hextets = cls._compress_hextets(hextets)
-        return ':'.join(hextets)
-
-    def _explode_shorthand_ip_string(self):
-        """Expand a shortened IPv6 address.
-
-        Args:
-            ip_str: A string, the IPv6 address.
-
-        Returns:
-            A string, the expanded IPv6 address.
-
-        """
-        if isinstance(self, IPv6Network):
-            ip_str = _compat_str(self.network_address)
-        elif isinstance(self, IPv6Interface):
-            ip_str = _compat_str(self.ip)
-        else:
-            ip_str = _compat_str(self)
-
-        ip_int = self._ip_int_from_string(ip_str)
-        hex_str = '%032x' % ip_int
-        parts = [hex_str[x:x + 4] for x in range(0, 32, 4)]
-        if isinstance(self, (_BaseNetwork, IPv6Interface)):
-            return '%s/%d' % (':'.join(parts), self._prefixlen)
-        return ':'.join(parts)
-
-    def _reverse_pointer(self):
-        """Return the reverse DNS pointer name for the IPv6 address.
-
-        This implements the method described in RFC3596 2.5.
-
-        """
-        reverse_chars = self.exploded[::-1].replace(':', '')
-        return '.'.join(reverse_chars) + '.ip6.arpa'
-
-    @property
-    def max_prefixlen(self):
-        return self._max_prefixlen
-
-    @property
-    def version(self):
-        return self._version
-
-
-class IPv6Address(_BaseV6, _BaseAddress):
-
-    """Represent and manipulate single IPv6 Addresses."""
-
-    __slots__ = ('_ip', '__weakref__')
-
-    def __init__(self, address):
-        """Instantiate a new IPv6 address object.
-
-        Args:
-            address: A string or integer representing the IP
-
-              Additionally, an integer can be passed, so
-              IPv6Address('2001:db8::') ==
-                IPv6Address(42540766411282592856903984951653826560)
-              or, more generally
-              IPv6Address(int(IPv6Address('2001:db8::'))) ==
-                IPv6Address('2001:db8::')
-
-        Raises:
-            AddressValueError: If address isn't a valid IPv6 address.
-
-        """
-        # Efficient constructor from integer.
-        if isinstance(address, _compat_int_types):
-            self._check_int_address(address)
-            self._ip = address
-            return
-
-        # Constructing from a packed address
-        if isinstance(address, bytes):
-            self._check_packed_address(address, 16)
-            bvs = _compat_bytes_to_byte_vals(address)
-            self._ip = _compat_int_from_byte_vals(bvs, 'big')
-            return
-
-        # Assume input argument to be string or any object representation
-        # which converts into a formatted IP string.
-        addr_str = _compat_str(address)
-        if '/' in addr_str:
-            raise AddressValueError("Unexpected '/' in %r" % address)
-        self._ip = self._ip_int_from_string(addr_str)
-
-    @property
-    def packed(self):
-        """The binary representation of this address."""
-        return v6_int_to_packed(self._ip)
-
-    @property
-    def is_multicast(self):
-        """Test if the address is reserved for multicast use.
-
-        Returns:
-            A boolean, True if the address is a multicast address.
-            See RFC 2373 2.7 for details.
-
-        """
-        return self in self._constants._multicast_network
-
-    @property
-    def is_reserved(self):
-        """Test if the address is otherwise IETF reserved.
-
-        Returns:
-            A boolean, True if the address is within one of the
-            reserved IPv6 Network ranges.
-
-        """
-        return any(self in x for x in self._constants._reserved_networks)
-
-    @property
-    def is_link_local(self):
-        """Test if the address is reserved for link-local.
-
-        Returns:
-            A boolean, True if the address is reserved per RFC 4291.
-
-        """
-        return self in self._constants._linklocal_network
-
-    @property
-    def is_site_local(self):
-        """Test if the address is reserved for site-local.
-
-        Note that the site-local address space has been deprecated by RFC 3879.
-        Use is_private to test if this address is in the space of unique local
-        addresses as defined by RFC 4193.
-
-        Returns:
-            A boolean, True if the address is reserved per RFC 3513 2.5.6.
-
-        """
-        return self in self._constants._sitelocal_network
-
-    @property
-    def is_private(self):
-        """Test if this address is allocated for private networks.
-
-        Returns:
-            A boolean, True if the address is reserved per
-            iana-ipv6-special-registry.
-
-        """
-        return any(self in net for net in self._constants._private_networks)
-
-    @property
-    def is_global(self):
-        """Test if this address is allocated for public networks.
-
-        Returns:
-            A boolean, true if the address is not reserved per
-            iana-ipv6-special-registry.
-
-        """
-        return not self.is_private
-
-    @property
-    def is_unspecified(self):
-        """Test if the address is unspecified.
-
-        Returns:
-            A boolean, True if this is the unspecified address as defined in
-            RFC 2373 2.5.2.
-
-        """
-        return self._ip == 0
-
-    @property
-    def is_loopback(self):
-        """Test if the address is a loopback address.
-
-        Returns:
-            A boolean, True if the address is a loopback address as defined in
-            RFC 2373 2.5.3.
-
-        """
-        return self._ip == 1
-
-    @property
-    def ipv4_mapped(self):
-        """Return the IPv4 mapped address.
-
-        Returns:
-            If the IPv6 address is a v4 mapped address, return the
-            IPv4 mapped address. Return None otherwise.
-
-        """
-        if (self._ip >> 32) != 0xFFFF:
-            return None
-        return IPv4Address(self._ip & 0xFFFFFFFF)
-
-    @property
-    def teredo(self):
-        """Tuple of embedded teredo IPs.
-
-        Returns:
-            Tuple of the (server, client) IPs or None if the address
-            doesn't appear to be a teredo address (doesn't start with
-            2001::/32)
-
-        """
-        if (self._ip >> 96) != 0x20010000:
-            return None
-        return (IPv4Address((self._ip >> 64) & 0xFFFFFFFF),
-                IPv4Address(~self._ip & 0xFFFFFFFF))
-
-    @property
-    def sixtofour(self):
-        """Return the IPv4 6to4 embedded address.
-
-        Returns:
-            The IPv4 6to4-embedded address if present or None if the
-            address doesn't appear to contain a 6to4 embedded address.
-
-        """
-        if (self._ip >> 112) != 0x2002:
-            return None
-        return IPv4Address((self._ip >> 80) & 0xFFFFFFFF)
-
-
-class IPv6Interface(IPv6Address):
-
-    def __init__(self, address):
-        if isinstance(address, (bytes, _compat_int_types)):
-            IPv6Address.__init__(self, address)
-            self.network = IPv6Network(self._ip)
-            self._prefixlen = self._max_prefixlen
-            return
-        if isinstance(address, tuple):
-            IPv6Address.__init__(self, address[0])
-            if len(address) > 1:
-                self._prefixlen = int(address[1])
-            else:
-                self._prefixlen = self._max_prefixlen
-            self.network = IPv6Network(address, strict=False)
-            self.netmask = self.network.netmask
-            self.hostmask = self.network.hostmask
-            return
-
-        addr = _split_optional_netmask(address)
-        IPv6Address.__init__(self, addr[0])
-        self.network = IPv6Network(address, strict=False)
-        self.netmask = self.network.netmask
-        self._prefixlen = self.network._prefixlen
-        self.hostmask = self.network.hostmask
-
-    def __str__(self):
-        return '%s/%d' % (self._string_from_ip_int(self._ip),
-                          self.network.prefixlen)
-
-    def __eq__(self, other):
-        address_equal = IPv6Address.__eq__(self, other)
-        if not address_equal or address_equal is NotImplemented:
-            return address_equal
-        try:
-            return self.network == other.network
-        except AttributeError:
-            # An interface with an associated network is NOT the
-            # same as an unassociated address. That's why the hash
-            # takes the extra info into account.
-            return False
-
-    def __lt__(self, other):
-        address_less = IPv6Address.__lt__(self, other)
-        if address_less is NotImplemented:
-            return NotImplemented
-        try:
-            return (self.network < other.network or
-                    self.network == other.network and address_less)
-        except AttributeError:
-            # We *do* allow addresses and interfaces to be sorted. The
-            # unassociated address is considered less than all interfaces.
-            return False
-
-    def __hash__(self):
-        return self._ip ^ self._prefixlen ^ int(self.network.network_address)
-
-    __reduce__ = _IPAddressBase.__reduce__
-
-    @property
-    def ip(self):
-        return IPv6Address(self._ip)
-
-    @property
-    def with_prefixlen(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self._prefixlen)
-
-    @property
-    def with_netmask(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self.netmask)
-
-    @property
-    def with_hostmask(self):
-        return '%s/%s' % (self._string_from_ip_int(self._ip),
-                          self.hostmask)
-
-    @property
-    def is_unspecified(self):
-        return self._ip == 0 and self.network.is_unspecified
-
-    @property
-    def is_loopback(self):
-        return self._ip == 1 and self.network.is_loopback
-
-
-class IPv6Network(_BaseV6, _BaseNetwork):
-
-    """This class represents and manipulates 128-bit IPv6 networks.
-
-    Attributes: [examples for IPv6('2001:db8::1000/124')]
-        .network_address: IPv6Address('2001:db8::1000')
-        .hostmask: IPv6Address('::f')
-        .broadcast_address: IPv6Address('2001:db8::100f')
-        .netmask: IPv6Address('ffff:ffff:ffff:ffff:ffff:ffff:ffff:fff0')
-        .prefixlen: 124
-
-    """
-
-    # Class to use when creating address objects
-    _address_class = IPv6Address
-
-    def __init__(self, address, strict=True):
-        """Instantiate a new IPv6 Network object.
-
-        Args:
-            address: A string or integer representing the IPv6 network or the
-              IP and prefix/netmask.
-              '2001:db8::/128'
-              '2001:db8:0000:0000:0000:0000:0000:0000/128'
-              '2001:db8::'
-              are all functionally the same in IPv6.  That is to say,
-              failing to provide a subnetmask will create an object with
-              a mask of /128.
-
-              Additionally, an integer can be passed, so
-              IPv6Network('2001:db8::') ==
-                IPv6Network(42540766411282592856903984951653826560)
-              or, more generally
-              IPv6Network(int(IPv6Network('2001:db8::'))) ==
-                IPv6Network('2001:db8::')
-
-            strict: A boolean. If true, ensure that we have been passed
-              A true network address, eg, 2001:db8::1000/124 and not an
-              IP address on a network, eg, 2001:db8::1/124.
-
-        Raises:
-            AddressValueError: If address isn't a valid IPv6 address.
-            NetmaskValueError: If the netmask isn't valid for
-              an IPv6 address.
-            ValueError: If strict was True and a network address was not
-              supplied.
-
-        """
-        _BaseNetwork.__init__(self, address)
-
-        # Efficient constructor from integer or packed address
-        if isinstance(address, (bytes, _compat_int_types)):
-            self.network_address = IPv6Address(address)
-            self.netmask, self._prefixlen = self._make_netmask(
-                self._max_prefixlen)
-            return
-
-        if isinstance(address, tuple):
-            if len(address) > 1:
-                arg = address[1]
-            else:
-                arg = self._max_prefixlen
-            self.netmask, self._prefixlen = self._make_netmask(arg)
-            self.network_address = IPv6Address(address[0])
-            packed = int(self.network_address)
-            if packed & int(self.netmask) != packed:
-                if strict:
-                    raise ValueError('%s has host bits set' % self)
-                else:
-                    self.network_address = IPv6Address(packed &
-                                                       int(self.netmask))
-            return
-
-        # Assume input argument to be string or any object representation
-        # which converts into a formatted IP prefix string.
-        addr = _split_optional_netmask(address)
-
-        self.network_address = IPv6Address(self._ip_int_from_string(addr[0]))
-
-        if len(addr) == 2:
-            arg = addr[1]
-        else:
-            arg = self._max_prefixlen
-        self.netmask, self._prefixlen = self._make_netmask(arg)
-
-        if strict:
-            if (IPv6Address(int(self.network_address) & int(self.netmask)) !=
-                    self.network_address):
-                raise ValueError('%s has host bits set' % self)
-        self.network_address = IPv6Address(int(self.network_address) &
-                                           int(self.netmask))
-
-        if self._prefixlen == (self._max_prefixlen - 1):
-            self.hosts = self.__iter__
-
-    def hosts(self):
-        """Generate Iterator over usable hosts in a network.
-
-          This is like __iter__ except it doesn't return the
-          Subnet-Router anycast address.
-
-        """
-        network = int(self.network_address)
-        broadcast = int(self.broadcast_address)
-        for x in _compat_range(network + 1, broadcast + 1):
-            yield self._address_class(x)
-
-    @property
-    def is_site_local(self):
-        """Test if the address is reserved for site-local.
-
-        Note that the site-local address space has been deprecated by RFC 3879.
-        Use is_private to test if this address is in the space of unique local
-        addresses as defined by RFC 4193.
-
-        Returns:
-            A boolean, True if the address is reserved per RFC 3513 2.5.6.
-
-        """
-        return (self.network_address.is_site_local and
-                self.broadcast_address.is_site_local)
-
-
-class _IPv6Constants(object):
-
-    _linklocal_network = IPv6Network('fe80::/10')
-
-    _multicast_network = IPv6Network('ff00::/8')
-
-    _private_networks = [
-        IPv6Network('::1/128'),
-        IPv6Network('::/128'),
-        IPv6Network('::ffff:0:0/96'),
-        IPv6Network('100::/64'),
-        IPv6Network('2001::/23'),
-        IPv6Network('2001:2::/48'),
-        IPv6Network('2001:db8::/32'),
-        IPv6Network('2001:10::/28'),
-        IPv6Network('fc00::/7'),
-        IPv6Network('fe80::/10'),
-    ]
-
-    _reserved_networks = [
-        IPv6Network('::/8'), IPv6Network('100::/8'),
-        IPv6Network('200::/7'), IPv6Network('400::/6'),
-        IPv6Network('800::/5'), IPv6Network('1000::/4'),
-        IPv6Network('4000::/3'), IPv6Network('6000::/3'),
-        IPv6Network('8000::/3'), IPv6Network('A000::/3'),
-        IPv6Network('C000::/3'), IPv6Network('E000::/4'),
-        IPv6Network('F000::/5'), IPv6Network('F800::/6'),
-        IPv6Network('FE00::/9'),
-    ]
-
-    _sitelocal_network = IPv6Network('fec0::/10')
-
-
-IPv6Address._constants = _IPv6Constants
diff --git a/c7n/utils.py b/c7n/utils.py
--- a/c7n/utils.py
+++ b/c7n/utils.py
@@ -18,6 +18,7 @@
 from datetime import datetime, timedelta
 import json
 import itertools
+import ipaddress
 import logging
 import os
 import random
@@ -30,7 +31,7 @@
 from six.moves.urllib import parse as urlparse
 from six.moves.urllib.request import getproxies
 
-from c7n import ipaddress, config
+from c7n import config
 from c7n.exceptions import ClientError, PolicyValidationError
 
 # Try to play nice in a serverless environment, where we don't require yaml
@@ -438,6 +439,23 @@ def __contains__(self, other):
             return self.supernet_of(other)
         return super(IPv4Network, self).__contains__(other)
 
+    if (sys.version_info.major == 3 and sys.version_info.minor <= 6):  # pragma: no cover
+        @staticmethod
+        def _is_subnet_of(a, b):
+            try:
+                # Always false if one is v4 and the other is v6.
+                if a._version != b._version:
+                    raise TypeError(f"{a} and {b} are not of the same version")
+                return (b.network_address <= a.network_address and
+                        b.broadcast_address >= a.broadcast_address)
+            except AttributeError:
+                raise TypeError(f"Unable to test subnet containment "
+                                f"between {a} and {b}")
+
+        def supernet_of(self, other):
+            """Return True if this network is a supernet of other."""
+            return self._is_subnet_of(other, self)
+
 
 def reformat_schema(model):
     """ Reformat schema to be in a more displayable format. """


Test patch:
diff --git a/tests/test_utils.py b/tests/test_utils.py
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -14,6 +14,7 @@
 from __future__ import absolute_import, division, print_function, unicode_literals
 
 import json
+import ipaddress
 import os
 import sys
 import tempfile
@@ -24,7 +25,7 @@
 from dateutil.parser import parse as parse_date
 import mock
 
-from c7n import ipaddress, utils
+from c7n import utils
 from c7n.config import Config
 from .common import BaseTest