ipaddress.py
authorStefan Israelsson Tampe <stefan.itampe@gmail.com>
Fri, 17 Aug 2018 13:05:37 +0000 (15:05 +0200)
committerStefan Israelsson Tampe <stefan.itampe@gmail.com>
Fri, 17 Aug 2018 13:05:37 +0000 (15:05 +0200)
modules/language/python/module/ipaddress.py [new file with mode: 0644]

diff --git a/modules/language/python/module/ipaddress.py b/modules/language/python/module/ipaddress.py
new file mode 100644 (file)
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+module(ipaddress)
+
+# 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.
+
+"""
+
+__version__ = '1.0'
+
+
+import functools
+
+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
+
+    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
+
+    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 address.to_bytes(4, 'big')
+    except 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 address.to_bytes(16, 'big')
+    except 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 = 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, (~number & (number-1)).bit_length())
+
+
+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),
+                    (last_int - first_int + 1).bit_length() - 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:
+
+    """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 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"
+            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 = ip_int.to_bytes(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) from None
+
+    @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__, (str(self),)
+
+
+@functools.total_ordering
+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, _BaseAddress):
+            return NotImplemented
+        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, int):
+            return NotImplemented
+        return self.__class__(int(self) + other)
+
+    def __sub__(self, other):
+        if not isinstance(other, int):
+            return NotImplemented
+        return self.__class__(int(self) - other)
+
+    def __repr__(self):
+        return '%s(%r)' % (self.__class__.__name__, str(self))
+
+    def __str__(self):
+        return 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,)
+
+
+@functools.total_ordering
+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__, 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 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 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, _BaseNetwork):
+            return NotImplemented
+        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.network_address >= self.network_address and
+                other.broadcast_address <= self.broadcast_address):
+            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.network_address >= s1.network_address and
+                other.broadcast_address <= s1.broadcast_address):
+                yield s2
+                s1, s2 = s1.subnets()
+            elif (other.network_address >= s2.network_address and
+                  other.broadcast_address <= s2.broadcast_address):
+                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 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)
+
+    @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:
+
+    """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 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, int):
+                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 int.from_bytes(map(cls._parse_octet, octets), 'big')
+        except ValueError as exc:
+            raise AddressValueError("%s in %r" % (exc, ip_str)) from None
+
+    @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(map(str, ip_int.to_bytes(4, 'big')))
+
+    def _is_valid_netmask(self, netmask):
+        """Verify that the netmask is valid.
+
+        Args:
+            netmask: A string, either a prefix or dotted decimal
+              netmask.
+
+        Returns:
+            A boolean, True if the prefix represents a valid IPv4
+            netmask.
+
+        """
+        mask = netmask.split('.')
+        if len(mask) == 4:
+            try:
+                for x in mask:
+                    if int(x) not in self._valid_mask_octets:
+                        return False
+            except ValueError:
+                # Found something that isn't an integer or isn't valid
+                return False
+            for idx, y in enumerate(mask):
+                if idx > 0 and y > mask[idx - 1]:
+                    return False
+            return True
+        try:
+            netmask = int(netmask)
+        except ValueError:
+            return False
+        return 0 <= netmask <= self._max_prefixlen
+
+    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 = 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, int):
+            self._check_int_address(address)
+            self._ip = address
+            return
+
+        # Constructing from a packed address
+        if isinstance(address, bytes):
+            self._check_packed_address(address, 4)
+            self._ip = int.from_bytes(address, 'big')
+            return
+
+        # Assume input argument to be string or any object representation
+        # which converts into a formatted IP string.
+        addr_str = 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
+    @functools.lru_cache()
+    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
+    @functools.lru_cache()
+    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, int)):
+            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, (int, 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
+    @functools.lru_cache()
+    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:
+    _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:
+
+    """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, int):
+                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)) from None
+            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 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)) from None
+
+    @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 = str(self.network_address)
+        elif isinstance(self, IPv6Interface):
+            ip_str = str(self.ip)
+        else:
+            ip_str = 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, int):
+            self._check_int_address(address)
+            self._ip = address
+            return
+
+        # Constructing from a packed address
+        if isinstance(address, bytes):
+            self._check_packed_address(address, 16)
+            self._ip = int.from_bytes(address, 'big')
+            return
+
+        # Assume input argument to be string or any object representation
+        # which converts into a formatted IP string.
+        addr_str = 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
+    @functools.lru_cache()
+    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, int)):
+            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, int)):
+            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 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:
+
+    _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