text: #!/usr/bin/python
  #
  # Copyright 2007 Google Inc.
  #  Licensed to PSF under a Contributor Agreement.
  #
  # Licensed under the Apache License, Version 2.0 (the "License");
  # you may not use this file except in compliance with the License.
  # You may obtain a copy of the License at
  #
  #      http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
  # implied. See the License for the specific language governing
  # permissions and limitations under the License.
  
  """A fast, lightweight IPv4/IPv6 manipulation library in Python.
  
  This library is used to create/poke/manipulate IPv4 and IPv6 addresses
  and networks.
  
  """
  
  __version__ = '2.2.0'
  
  import struct
  import sys
  
  if sys.version_info > (3,):
      long = int
      xrange = range
  
  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 IPAddress(address, version=None):
      """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.
          version: An Integer, 4 or 6. If set, don't try to automatically
            determine what the IP address type is. important for things
            like IPAddress(1), which could be IPv4, '0.0.0.1',  or IPv6,
            '::1'.
  
      Returns:
          An IPv4Address or IPv6Address object.
  
      Raises:
          ValueError: if the string passed isn't either a v4 or a v6
            address.
  
      """
      if version:
          if version == 4:
              return IPv4Address(address)
          elif version == 6:
              return IPv6Address(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 IPNetwork(address, version=None, strict=False):
      """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.
          version: An Integer, if set, don't try to automatically
            determine what the IP address type is. important for things
            like IPNetwork(1), which could be IPv4, '0.0.0.1/32', or IPv6,
            '::1/128'.
  
      Returns:
          An IPv4Network or IPv6Network object.
  
      Raises:
          ValueError: if the string passed isn't either a v4 or a v6
            address. Or if a strict network was requested and a strict
            network wasn't given.
  
      """
      if version:
          if version == 4:
              return IPv4Network(address, strict)
          elif version == 6:
              return IPv6Network(address, strict)
  
      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 v4_int_to_packed(address):
      """The binary representation of this address.
  
      Args:
          address: An integer representation of an IPv4 IP address.
  
      Returns:
          The binary representation of this address.
  
      Raises:
          ValueError: If the integer is too large to be an IPv4 IP
            address.
      """
      if address > _BaseV4._ALL_ONES:
          raise ValueError('Address too large for IPv4')
      return Bytes(struct.pack('!I', address))
  
  
  def v6_int_to_packed(address):
      """The binary representation of this address.
  
      Args:
          address: An integer representation of an IPv6 IP address.
  
      Returns:
          The binary representation of this address.
      """
      return Bytes(struct.pack('!QQ', address >> 64, address & (2**64 - 1)))
  
  
  def _find_address_range(addresses):
      """Find a sequence of addresses.
  
      Args:
          addresses: a list of IPv4 or IPv6 addresses.
  
      Returns:
          A tuple containing the first and last IP addresses in the sequence,
          and the index of the last IP address in the sequence.
  
      """
      first = last = addresses[0]
      last_index = 0
      for ip in addresses[1:]:
          if ip._ip == last._ip + 1:
              last = ip
              last_index += 1
          else:
              break
      return (first, last, last_index)
  
  def _get_prefix_length(number1, number2, bits):
      """Get the number of leading bits that are same for two numbers.
  
      Args:
          number1: an integer.
          number2: another integer.
          bits: the maximum number of bits to compare.
  
      Returns:
          The number of leading bits that are the same for two numbers.
  
      """
      for i in range(bits):
          if number1 >> i == number2 >> i:
              return bits - i
      return 0
  
  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
      for i in range(bits):
          if (number >> i) % 2:
              return i
  
  def summarize_address_range(first, last):
      """Summarize a network range given the first and last IP addresses.
  
      Example:
          >>> summarize_address_range(IPv4Address('1.1.1.0'),
              IPv4Address('1.1.1.130'))
          [IPv4Network('1.1.1.0/25'), IPv4Network('1.1.1.128/31'),
          IPv4Network('1.1.1.130/32')]
  
      Args:
          first: the first IPv4Address or IPv6Address in the range.
          last: the last IPv4Address or IPv6Address in the range.
  
      Returns:
          The address range collapsed to a list of IPv4Network's or
          IPv6Network's.
  
      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 is not 4 or 6.
  
      """
      if not (isinstance(first, _BaseIP) and isinstance(last, _BaseIP)):
          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" % (
                  str(first), str(last)))
      if first > last:
          raise ValueError('last IP address must be greater than first')
  
      networks = []
  
      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 = _count_righthand_zero_bits(first_int, ip_bits)
          current = None
          while nbits >= 0:
              addend = 2**nbits - 1
              current = first_int + addend
              nbits -= 1
              if current <= last_int:
                  break
          prefix = _get_prefix_length(first_int, current, ip_bits)
          net = ip('%s/%d' % (str(first), prefix))
          networks.append(net)
          if current == ip._ALL_ONES:
              break
          first_int = current + 1
          first = IPAddress(first_int, version=first._version)
      return networks
  
  def _collapse_address_list_recursive(addresses):
      """Loops through the addresses, collapsing concurrent netblocks.
  
      Example:
  
          ip1 = IPv4Network('1.1.0.0/24')
          ip2 = IPv4Network('1.1.1.0/24')
          ip3 = IPv4Network('1.1.2.0/24')
          ip4 = IPv4Network('1.1.3.0/24')
          ip5 = IPv4Network('1.1.4.0/24')
          ip6 = IPv4Network('1.1.0.1/22')
  
          _collapse_address_list_recursive([ip1, ip2, ip3, ip4, ip5, ip6]) ->
            [IPv4Network('1.1.0.0/22'), IPv4Network('1.1.4.0/24')]
  
          This shouldn't be called directly; it is called via
            collapse_address_list([]).
  
      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.
  
      """
      ret_array = []
      optimized = False
  
      for cur_addr in addresses:
          if not ret_array:
              ret_array.append(cur_addr)
              continue
          if cur_addr in ret_array[-1]:
              optimized = True
          elif cur_addr == ret_array[-1].supernet().subnet()[1]:
              ret_array.append(ret_array.pop().supernet())
              optimized = True
          else:
              ret_array.append(cur_addr)
  
      if optimized:
          return _collapse_address_list_recursive(ret_array)
  
      return ret_array
  
  
  def collapse_address_list(addresses):
      """Collapse a list of IP objects.
  
      Example:
          collapse_address_list([IPv4('1.1.0.0/24'), IPv4('1.1.1.0/24')]) ->
            [IPv4('1.1.0.0/23')]
  
      Args:
          addresses: A list of IPv4Network or IPv6Network objects.
  
      Returns:
          A list of IPv4Network or IPv6Network objects depending on what we
          were passed.
  
      Raises:
          TypeError: If passed a list of mixed version objects.
  
      """
      i = 0
      addrs = []
      ips = []
      nets = []
  
      # split IP addresses and networks
      for ip in addresses:
          if isinstance(ip, _BaseIP):
              if ips and ips[-1]._version != ip._version:
                  raise TypeError("%s and %s are not of the same version" % (
                          str(ip), str(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" % (
                          str(ip), str(ips[-1])))
              ips.append(ip.ip)
          else:
              if nets and nets[-1]._version != ip._version:
                  raise TypeError("%s and %s are not of the same version" % (
                          str(ip), str(nets[-1])))
              nets.append(ip)
  
      # sort and dedup
      ips = sorted(set(ips))
      nets = sorted(set(nets))
  
      while i < len(ips):
          (first, last, last_index) = _find_address_range(ips[i:])
          i += last_index + 1
          addrs.extend(summarize_address_range(first, last))
  
      return _collapse_address_list_recursive(sorted(
          addrs + nets, key=_BaseNet._get_networks_key))
  
  # backwards compatibility
  CollapseAddrList = collapse_address_list
  
  # We need to distinguish between the string and packed-bytes representations
  # of an IP address.  For example, b'0::1' is the IPv4 address 48.58.58.49,
  # while '0::1' is an IPv6 address.
  #
  # In Python 3, the native 'bytes' type already provides this functionality,
  # so we use it directly.  For earlier implementations where bytes is not a
  # distinct type, we create a subclass of str to serve as a tag.
  #
  # Usage example (Python 2):
  #   ip = ipaddr.IPAddress(ipaddr.Bytes('xxxx'))
  #
  # Usage example (Python 3):
  #   ip = ipaddr.IPAddress(b'xxxx')
  try:
      if bytes is str:
          raise TypeError("bytes is not a distinct type")
      Bytes = bytes
  except (NameError, TypeError):
      class Bytes(str):
          def __repr__(self):
              return 'Bytes(%s)' % str.__repr__(self)
  
  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('1.1.1.1') <= IPv4Network('1.1.1.1/24')
  
      doesn't make any sense.  There are some times however, where you may wish
      to have ipaddr 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, _BaseNet):
          return obj._get_networks_key()
      elif isinstance(obj, _BaseIP):
          return obj._get_address_key()
      return NotImplemented
  
  class _IPAddrBase(object):
  
      """The mother class."""
  
      def __index__(self):
          return self._ip
  
      def __int__(self):
          return self._ip
  
      def __hex__(self):
          return hex(self._ip)
  
      @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)
  
  
  class _BaseIP(_IPAddrBase):
  
      """A generic IP object.
  
      This IP class contains the version independent methods which are
      used by single IP addresses.
  
      """
  
      def __eq__(self, other):
          try:
              return (self._ip == other._ip
                      and self._version == other._version)
          except AttributeError:
              return NotImplemented
  
      def __ne__(self, other):
          eq = self.__eq__(other)
          if eq is NotImplemented:
              return NotImplemented
          return not eq
  
      def __le__(self, other):
          gt = self.__gt__(other)
          if gt is NotImplemented:
              return NotImplemented
          return not gt
  
      def __ge__(self, other):
          lt = self.__lt__(other)
          if lt is NotImplemented:
              return NotImplemented
          return not lt
  
      def __lt__(self, other):
          if self._version != other._version:
              raise TypeError('%s and %s are not of the same version' % (
                      str(self), str(other)))
          if not isinstance(other, _BaseIP):
              raise TypeError('%s and %s are not of the same type' % (
                      str(self), str(other)))
          if self._ip != other._ip:
              return self._ip < other._ip
          return False
  
      def __gt__(self, other):
          if self._version != other._version:
              raise TypeError('%s and %s are not of the same version' % (
                      str(self), str(other)))
          if not isinstance(other, _BaseIP):
              raise TypeError('%s and %s are not of the same type' % (
                      str(self), str(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 IPAddress(int(self) + other, version=self._version)
  
      def __sub__(self, other):
          if not isinstance(other, int):
              return NotImplemented
          return IPAddress(int(self) - other, version=self._version)
  
      def __repr__(self):
          return '%s(%r)' % (self.__class__.__name__, str(self))
  
      def __str__(self):
          return  '%s' % self._string_from_ip_int(self._ip)
  
      def __hash__(self):
          return hash(hex(long(self._ip)))
  
      def _get_address_key(self):
          return (self._version, self)
  
      @property
      def version(self):
          raise NotImplementedError('BaseIP has no version')
  
  
  class _BaseNet(_IPAddrBase):
  
      """A generic IP 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 iterhosts(self):
          """Generate Iterator over usable hosts in a network.
  
             This is like __iter__ except it doesn't return the network
             or broadcast addresses.
  
          """
          cur = int(self.network) + 1
          bcast = int(self.broadcast) - 1
          while cur <= bcast:
              cur += 1
              yield IPAddress(cur - 1, version=self._version)
  
      def __iter__(self):
          cur = int(self.network)
          bcast = int(self.broadcast)
          while cur <= bcast:
              cur += 1
              yield IPAddress(cur - 1, version=self._version)
  
      def __getitem__(self, n):
          network = int(self.network)
          broadcast = int(self.broadcast)
          if n >= 0:
              if network + n > broadcast:
                  raise IndexError
              return IPAddress(network + n, version=self._version)
          else:
              n += 1
              if broadcast + n < network:
                  raise IndexError
              return IPAddress(broadcast + n, version=self._version)
  
      def __lt__(self, other):
          if self._version != other._version:
              raise TypeError('%s and %s are not of the same version' % (
                      str(self), str(other)))
          if not isinstance(other, _BaseNet):
              raise TypeError('%s and %s are not of the same type' % (
                      str(self), str(other)))
          if self.network != other.network:
              return self.network < other.network
          if self.netmask != other.netmask:
              return self.netmask < other.netmask
          return False
  
      def __gt__(self, other):
          if self._version != other._version:
              raise TypeError('%s and %s are not of the same version' % (
                      str(self), str(other)))
          if not isinstance(other, _BaseNet):
              raise TypeError('%s and %s are not of the same type' % (
                      str(self), str(other)))
          if self.network != other.network:
              return self.network > other.network
          if self.netmask != other.netmask:
              return self.netmask > other.netmask
          return False
  
      def __le__(self, other):
          gt = self.__gt__(other)
          if gt is NotImplemented:
              return NotImplemented
          return not gt
  
      def __ge__(self, other):
          lt = self.__lt__(other)
          if lt is NotImplemented:
              return NotImplemented
          return not lt
  
      def __eq__(self, other):
          try:
              return (self._version == other._version
                      and self.network == other.network
                      and int(self.netmask) == int(other.netmask))
          except AttributeError:
              if isinstance(other, _BaseIP):
                  return (self._version == other._version
                          and self._ip == other._ip)
  
      def __ne__(self, other):
          eq = self.__eq__(other)
          if eq is NotImplemented:
              return NotImplemented
          return not eq
  
      def __str__(self):
          return  '%s/%s' % (str(self.ip),
                             str(self._prefixlen))
  
      def __hash__(self):
          return hash(int(self.network) ^ 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, _BaseNet):
              return (self.network <= other.network and
                      self.broadcast >= other.broadcast)
          # dealing with another address
          else:
              return (int(self.network) <= int(other._ip) <=
                      int(self.broadcast))
  
      def overlaps(self, other):
          """Tell if self is partly contained in other."""
          return self.network in other or self.broadcast in other or (
              other.network in self or other.broadcast in self)
  
      @property
      def network(self):
          x = self._cache.get('network')
          if x is None:
              x = IPAddress(self._ip & int(self.netmask), version=self._version)
              self._cache['network'] = x
          return x
  
      @property
      def broadcast(self):
          x = self._cache.get('broadcast')
          if x is None:
              x = IPAddress(self._ip | int(self.hostmask), version=self._version)
              self._cache['broadcast'] = x
          return x
  
      @property
      def hostmask(self):
          x = self._cache.get('hostmask')
          if x is None:
              x = IPAddress(int(self.netmask) ^ self._ALL_ONES,
                            version=self._version)
              self._cache['hostmask'] = x
          return x
  
      @property
      def with_prefixlen(self):
          return '%s/%d' % (str(self.ip), self._prefixlen)
  
      @property
      def with_netmask(self):
          return '%s/%s' % (str(self.ip), str(self.netmask))
  
      @property
      def with_hostmask(self):
          return '%s/%s' % (str(self.ip), str(self.hostmask))
  
      @property
      def numhosts(self):
          """Number of hosts in the current subnet."""
          return int(self.broadcast) - int(self.network) + 1
  
      @property
      def version(self):
          raise NotImplementedError('BaseNet has no version')
  
      @property
      def prefixlen(self):
          return self._prefixlen
  
      def address_exclude(self, other):
          """Remove an address from a larger block.
  
          For example:
  
              addr1 = IPNetwork('10.1.1.0/24')
              addr2 = IPNetwork('10.1.1.0/26')
              addr1.address_exclude(addr2) =
                  [IPNetwork('10.1.1.64/26'), IPNetwork('10.1.1.128/25')]
  
          or IPv6:
  
              addr1 = IPNetwork('::1/32')
              addr2 = IPNetwork('::1/128')
              addr1.address_exclude(addr2) = [IPNetwork('::0/128'),
                  IPNetwork('::2/127'),
                  IPNetwork('::4/126'),
                  IPNetwork('::8/125'),
                  ...
                  IPNetwork('0:0:8000::/33')]
  
          Args:
              other: An IPvXNetwork object of the same type.
  
          Returns:
              A sorted list of IPvXNetwork objects addresses which is self
              minus other.
  
          Raises:
              TypeError: If self and other are of difffering 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" % (
                  str(self), str(other)))
  
          if not isinstance(other, _BaseNet):
              raise TypeError("%s is not a network object" % str(other))
  
          if other not in self:
              raise ValueError('%s not contained in %s' % (str(other),
                                                           str(self)))
          if other == self:
              return []
  
          ret_addrs = []
  
          # Make sure we're comparing the network of other.
          other = IPNetwork('%s/%s' % (str(other.network), str(other.prefixlen)),
                     version=other._version)
  
          s1, s2 = self.subnet()
          while s1 != other and s2 != other:
              if other in s1:
                  ret_addrs.append(s2)
                  s1, s2 = s1.subnet()
              elif other in s2:
                  ret_addrs.append(s1)
                  s1, s2 = s2.subnet()
              else:
                  # If we got here, there's a bug somewhere.
                  assert True == False, ('Error performing exclusion: '
                                         's1: %s s2: %s other: %s' %
                                         (str(s1), str(s2), str(other)))
          if s1 == other:
              ret_addrs.append(s2)
          elif s2 == other:
              ret_addrs.append(s1)
          else:
              # If we got here, there's a bug somewhere.
              assert True == False, ('Error performing exclusion: '
                                     's1: %s s2: %s other: %s' %
                                     (str(s1), str(s2), str(other)))
  
          return sorted(ret_addrs, key=_BaseNet._get_networks_key)
  
      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: IPv4('1.1.1.0/24') < IPv4('1.1.2.0/24')
                IPv6('1080::200C:417A') < IPv6('1080::200B:417B')
              0 if self == other
                eg: IPv4('1.1.1.1/24') == IPv4('1.1.1.2/24')
                IPv6('1080::200C:417A/96') == IPv6('1080::200C:417B/96')
              1 if self > other
                eg: IPv4('1.1.1.0/24') > IPv4('1.1.0.0/24')
                IPv6('1080::1:200C:417A/112') >
                IPv6('1080::0:200C:417A/112')
  
              If the IP versions of self and other are different, returns:
  
              -1 if self._version < other._version
                eg: IPv4('10.0.0.1/24') < IPv6('::1/128')
              1 if self._version > other._version
                eg: IPv6('::1/128') > IPv4('255.255.255.0/24')
  
          """
          if self._version < other._version:
              return -1
          if self._version > other._version:
              return 1
          # self._version == other._version below here:
          if self.network < other.network:
              return -1
          if self.network > other.network:
              return 1
          # self.network == other.network below here:
          if self.netmask < other.netmask:
              return -1
          if self.netmask > other.netmask:
              return 1
          # self.network == other.network and self.netmask == other.netmask
          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, self.netmask)
  
      def _ip_int_from_prefix(self, prefixlen):
          """Turn the prefix length into a bitwise netmask.
  
          Args:
              prefixlen: An integer, the prefix length.
  
          Returns:
              An integer.
  
          """
          return self._ALL_ONES ^ (self._ALL_ONES >> prefixlen)
  
      def _prefix_from_ip_int(self, ip_int):
          """Return prefix length from a bitwise netmask.
  
          Args:
              ip_int: An integer, the netmask in expanded bitwise format.
  
          Returns:
              An integer, the prefix length.
  
          Raises:
              NetmaskValueError: If the input is not a valid netmask.
  
          """
          prefixlen = self._max_prefixlen
          while prefixlen:
              if ip_int & 1:
                  break
              ip_int >>= 1
              prefixlen -= 1
  
          if ip_int == (1 << prefixlen) - 1:
              return prefixlen
          else:
              raise NetmaskValueError('Bit pattern does not match /1*0*/')
  
      def _prefix_from_prefix_int(self, prefixlen):
          """Validate and return a prefix length integer.
  
          Args:
              prefixlen: An integer containing the prefix length.
  
          Returns:
              The input, possibly converted from long to int.
  
          Raises:
              NetmaskValueError: If the input is not an integer, or out of range.
          """
          if not isinstance(prefixlen, (int, long)):
              raise NetmaskValueError('%r is not an integer' % prefixlen)
          prefixlen = int(prefixlen)
          if not (0 <= prefixlen <= self._max_prefixlen):
              raise NetmaskValueError('%d is not a valid prefix length' %
                                      prefixlen)
          return prefixlen
  
      def _prefix_from_prefix_string(self, prefixlen_str):
          """Turn a prefix length string into an integer.
  
          Args:
              prefixlen_str: A decimal string containing the prefix length.
  
          Returns:
              The prefix length as an integer.
  
          Raises:
              NetmaskValueError: If the input is malformed or out of range.
  
          """
          try:
              if not _BaseV4._DECIMAL_DIGITS.issuperset(prefixlen_str):
                  raise ValueError
              prefixlen = int(prefixlen_str)
          except ValueError:
              raise NetmaskValueError('%s is not a valid prefix length' %
                                      prefixlen_str)
          return self._prefix_from_prefix_int(prefixlen)
  
      def _prefix_from_ip_string(self, ip_str):
          """Turn a netmask/hostmask string into a prefix length.
  
          Args:
              ip_str: A netmask or hostmask, formatted as an IP address.
  
          Returns:
              The prefix length as an integer.
  
          Raises:
              NetmaskValueError: If the input is not a netmask or hostmask.
  
          """
          # Parse the netmask/hostmask like an IP address.
          try:
              ip_int = self._ip_int_from_string(ip_str)
          except AddressValueError:
              raise NetmaskValueError('%s is not a valid 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 self._prefix_from_ip_int(ip_int)
          except NetmaskValueError:
              pass
  
          # Invert the bits, and try matching a /0+1+/ hostmask instead.
          ip_int ^= self._ALL_ONES
          try:
              return self._prefix_from_ip_int(ip_int)
          except NetmaskValueError:
              raise NetmaskValueError('%s is not a valid netmask' % ip_str)
  
      def iter_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), return a list 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, str(self)))
  
          first = IPNetwork('%s/%s' % (str(self.network),
                                       str(self._prefixlen + prefixlen_diff)),
                           version=self._version)
  
          yield first
          current = first
          while True:
              broadcast = current.broadcast
              if broadcast == self.broadcast:
                  return
              new_addr = IPAddress(int(broadcast) + 1, version=self._version)
              current = IPNetwork('%s/%s' % (str(new_addr), str(new_prefixlen)),
                                  version=self._version)
  
              yield current
  
      def masked(self):
          """Return the network object with the host bits masked out."""
          return IPNetwork('%s/%d' % (self.network, self._prefixlen),
                           version=self._version)
  
      def subnet(self, prefixlen_diff=1, new_prefix=None):
          """Return a list of subnets, rather than an iterator."""
          return list(self.iter_subnets(prefixlen_diff, new_prefix))
  
      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
  
  
          if self.prefixlen - prefixlen_diff < 0:
              raise ValueError(
                  'current prefixlen is %d, cannot have a prefixlen_diff of %d' %
                  (self.prefixlen, prefixlen_diff))
          return IPNetwork('%s/%s' % (str(self.network),
                                      str(self.prefixlen - prefixlen_diff)),
                           version=self._version)
  
      # backwards compatibility
      Subnet = subnet
      Supernet = supernet
      AddressExclude = address_exclude
      CompareNetworks = compare_networks
      Contains = __contains__
  
  
  class _BaseV4(object):
  
      """Base IPv4 object.
  
      The following methods are used by IPv4 objects in both single IP
      addresses and networks.
  
      """
  
      # Equivalent to 255.255.255.255 or 32 bits of 1's.
      _ALL_ONES = (2**IPV4LENGTH) - 1
      _DECIMAL_DIGITS = frozenset('0123456789')
  
      def __init__(self, address):
          self._version = 4
          self._max_prefixlen = IPV4LENGTH
  
      def _explode_shorthand_ip_string(self):
          return str(self)
  
      def _ip_int_from_string(self, 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.
  
          """
          octets = ip_str.split('.')
          if len(octets) != 4:
              raise AddressValueError(ip_str)
  
          packed_ip = 0
          for oc in octets:
              try:
                  packed_ip = (packed_ip << 8) | self._parse_octet(oc)
              except ValueError:
                  raise AddressValueError(ip_str)
          return packed_ip
  
      def _parse_octet(self, 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].
  
          """
          # Whitelist the characters, since int() allows a lot of bizarre stuff.
          if not self._DECIMAL_DIGITS.issuperset(octet_str):
              raise ValueError
          octet_int = int(octet_str, 10)
          # Disallow leading zeroes, because no clear standard exists on
          # whether these should be interpreted as decimal or octal.
          if octet_int > 255 or (octet_str[0] == '0' and len(octet_str) > 1):
              raise ValueError
          return octet_int
  
      def _string_from_ip_int(self, 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.
  
          """
          octets = []
          for _ in xrange(4):
              octets.insert(0, str(ip_int & 0xFF))
              ip_int >>= 8
          return '.'.join(octets)
  
      @property
      def max_prefixlen(self):
          return self._max_prefixlen
  
      @property
      def packed(self):
          """The binary representation of this address."""
          return v4_int_to_packed(self._ip)
  
      @property
      def version(self):
          return self._version
  
      @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 IPv4Network('240.0.0.0/4')
  
      @property
      def is_private(self):
          """Test if this address is allocated for private networks.
  
          Returns:
              A boolean, True if the address is reserved per RFC 1918.
  
          """
          return (self in IPv4Network('10.0.0.0/8') or
                  self in IPv4Network('172.16.0.0/12') or
                  self in IPv4Network('192.168.0.0/16'))
  
      @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 IPv4Network('224.0.0.0/4')
  
      @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 in IPv4Network('0.0.0.0')
  
      @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 IPv4Network('127.0.0.0/8')
  
      @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 IPv4Network('169.254.0.0/16')
  
  
  class IPv4Address(_BaseV4, _BaseIP):
  
      """Represent and manipulate single IPv4 Addresses."""
  
      def __init__(self, address):
  
          """
          Args:
              address: A string or integer representing the IP
                '192.168.1.1'
  
                Additionally, an integer can be passed, so
                IPv4Address('192.168.1.1') == IPv4Address(3232235777).
                or, more generally
                IPv4Address(int(IPv4Address('192.168.1.1'))) ==
                  IPv4Address('192.168.1.1')
  
          Raises:
              AddressValueError: If ipaddr isn't a valid IPv4 address.
  
          """
          _BaseV4.__init__(self, address)
  
          # Efficient copy constructor.
          if isinstance(address, IPv4Address):
              self._ip = address._ip
              return
  
          # Efficient constructor from integer.
          if isinstance(address, (int, long)):
              self._ip = address
              if address < 0 or address > self._ALL_ONES:
                  raise AddressValueError(address)
              return
  
          # Constructing from a packed address
          if isinstance(address, Bytes):
              try:
                  self._ip, = struct.unpack('!I', address)
              except struct.error:
                  raise AddressValueError(address)  # Wrong length.
              return
  
          # Assume input argument to be string or any object representation
          # which converts into a formatted IP string.
          addr_str = str(address)
          self._ip = self._ip_int_from_string(addr_str)
  
  
  class IPv4Network(_BaseV4, _BaseNet):
  
      """This class represents and manipulates 32-bit IPv4 networks.
  
      Attributes: [examples for IPv4Network('1.2.3.4/27')]
          ._ip: 16909060
          .ip: IPv4Address('1.2.3.4')
          .network: IPv4Address('1.2.3.0')
          .hostmask: IPv4Address('0.0.0.31')
          .broadcast: IPv4Address('1.2.3.31')
          .netmask: IPv4Address('255.255.255.224')
          .prefixlen: 27
  
      """
  
      def __init__(self, address, strict=False):
          """Instantiate a new IPv4 network object.
  
          Args:
              address: The IPv4 network as a string, 2-tuple, or any format
                supported by the IPv4Address constructor.
  
                Strings typically use CIDR format, such as '192.0.2.0/24'.
                If a dotted-quad is provided after the '/', it is treated as
                a netmask if it starts with a nonzero bit (e.g. 255.0.0.0 == /8)
                or a hostmask if it starts with a zero bit
                (e.g. /0.0.0.255 == /8), with the single exception of an all-zero
                mask which is treated as /0.
  
                The 2-tuple format consists of an (ip, prefixlen), where ip is any
                format recognized by the IPv4Address constructor, and prefixlen is
                an integer from 0 through 32.
  
                A plain IPv4 address (in any format) will be forwarded to the
                IPv4Address constructor, with an implied prefixlen of 32.
  
                For example, the following inputs are equivalent:
                  IPv4Network('192.0.2.1/32')
                  IPv4Network('192.0.2.1/255.255.255.255')
                  IPv4Network('192.0.2.1')
                  IPv4Network(0xc0000201)
                  IPv4Network(IPv4Address('192.0.2.1'))
                  IPv4Network(('192.0.2.1', 32))
                  IPv4Network((0xc0000201, 32))
                  IPv4Network((IPv4Address('192.0.2.1'), 32))
  
              strict: A boolean. If true, ensure that we have been passed
                A true network address, eg, 192.168.1.0/24 and not an
                IP address on a network, eg, 192.168.1.1/24.
  
          Raises:
              AddressValueError: If ipaddr isn't a valid IPv4 address.
              NetmaskValueError: If the netmask isn't valid for
                an IPv4 address.
              ValueError: If strict was True and a network address was not
                supplied.
  
          """
          _BaseNet.__init__(self, address)
          _BaseV4.__init__(self, address)
  
          # Constructing from a single IP address.
          if isinstance(address, (int, long, Bytes, IPv4Address)):
              self.ip = IPv4Address(address)
              self._ip = self.ip._ip
              self._prefixlen = self._max_prefixlen
              self.netmask = IPv4Address(self._ALL_ONES)
              return
  
          # Constructing from an (ip, prefixlen) tuple.
          if isinstance(address, tuple):
              try:
                  ip, prefixlen = address
              except ValueError:
                  raise AddressValueError(address)
              self.ip = IPv4Address(ip)
              self._ip = self.ip._ip
              self._prefixlen = self._prefix_from_prefix_int(prefixlen)
  
          else:
              # Assume input argument to be string or any object representation
              # which converts into a formatted IP prefix string.
              addr = str(address).split('/')
  
              if len(addr) > 2:
                  raise AddressValueError(address)
  
              self._ip = self._ip_int_from_string(addr[0])
              self.ip = IPv4Address(self._ip)
  
              if len(addr) == 2:
                  try:
                      # Check for a netmask in prefix length form.
                      self._prefixlen = self._prefix_from_prefix_string(addr[1])
                  except NetmaskValueError:
                      # Check for a netmask or hostmask in dotted-quad form.
                      # This may raise NetmaskValueError.
                      self._prefixlen = self._prefix_from_ip_string(addr[1])
              else:
                  self._prefixlen = self._max_prefixlen
  
          self.netmask = IPv4Address(self._ip_int_from_prefix(self._prefixlen))
  
          if strict:
              if self.ip != self.network:
                  raise ValueError('%s has host bits set' % self.ip)
          if self._prefixlen == (self._max_prefixlen - 1):
              self.iterhosts = self.__iter__
  
      # backwards compatibility
      IsRFC1918 = lambda self: self.is_private
      IsMulticast = lambda self: self.is_multicast
      IsLoopback = lambda self: self.is_loopback
      IsLinkLocal = lambda self: self.is_link_local
  
  
  class _BaseV6(object):
  
      """Base IPv6 object.
  
      The following methods are used by IPv6 objects in both single IP
      addresses and networks.
  
      """
  
      _ALL_ONES = (2**IPV6LENGTH) - 1
      _HEXTET_COUNT = 8
      _HEX_DIGITS = frozenset('0123456789ABCDEFabcdef')
  
      def __init__(self, address):
          self._version = 6
          self._max_prefixlen = IPV6LENGTH
  
      def _ip_int_from_string(self, ip_str):
          """Turn an IPv6 ip_str into an integer.
  
          Args:
              ip_str: A string, the IPv6 ip_str.
  
          Returns:
              A long, the IPv6 ip_str.
  
          Raises:
              AddressValueError: if ip_str isn't a valid IPv6 Address.
  
          """
          parts = ip_str.split(':')
  
          # An IPv6 address needs at least 2 colons (3 parts).
          if len(parts) < 3:
              raise AddressValueError(ip_str)
  
          # If the address has an IPv4-style suffix, convert it to hexadecimal.
          if '.' in parts[-1]:
              ipv4_int = IPv4Address(parts.pop())._ip
              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).
          if len(parts) > self._HEXTET_COUNT + 1:
              raise AddressValueError(ip_str)
  
          # Disregarding the endpoints, find '::' with nothing in between.
          # This indicates that a run of zeroes has been skipped.
          try:
              skip_index, = (
                  [i for i in xrange(1, len(parts) - 1) if not parts[i]] or
                  [None])
          except ValueError:
              # Can't have more than one '::'
              raise AddressValueError(ip_str)
  
          # 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:
                      raise AddressValueError(ip_str)  # ^: requires ^::
              if not parts[-1]:
                  parts_lo -= 1
                  if parts_lo:
                      raise AddressValueError(ip_str)  # :$ requires ::$
              parts_skipped = self._HEXTET_COUNT - (parts_hi + parts_lo)
              if parts_skipped < 1:
                  raise AddressValueError(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) != self._HEXTET_COUNT:
                  raise AddressValueError(ip_str)
              parts_hi = len(parts)
              parts_lo = 0
              parts_skipped = 0
  
          try:
              # Now, parse the hextets into a 128-bit integer.
              ip_int = long(0)
              for i in xrange(parts_hi):
                  ip_int <<= 16
                  ip_int |= self._parse_hextet(parts[i])
              ip_int <<= 16 * parts_skipped
              for i in xrange(-parts_lo, 0):
                  ip_int <<= 16
                  ip_int |= self._parse_hextet(parts[i])
              return ip_int
          except ValueError:
              raise AddressValueError(ip_str)
  
      def _parse_hextet(self, 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 self._HEX_DIGITS.issuperset(hextet_str):
              raise ValueError
          if len(hextet_str) > 4:
            raise ValueError
          hextet_int = int(hextet_str, 16)
          if hextet_int > 0xFFFF:
              raise ValueError
          return hextet_int
  
      def _compress_hextets(self, 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 in range(len(hextets)):
              if hextets[index] == '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
  
      def _string_from_ip_int(self, 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 not ip_int and ip_int != 0:
              ip_int = int(self._ip)
  
          if ip_int > self._ALL_ONES:
              raise ValueError('IPv6 address is too large')
  
          hex_str = '%032x' % ip_int
          hextets = []
          for x in range(0, 32, 4):
              hextets.append('%x' % int(hex_str[x:x+4], 16))
  
          hextets = self._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, _BaseNet):
              ip_str = str(self.ip)
          else:
              ip_str = str(self)
  
          ip_int = self._ip_int_from_string(ip_str)
          parts = []
          for i in xrange(self._HEXTET_COUNT):
              parts.append('%04x' % (ip_int & 0xFFFF))
              ip_int >>= 16
          parts.reverse()
          if isinstance(self, _BaseNet):
              return '%s/%d' % (':'.join(parts), self.prefixlen)
          return ':'.join(parts)
  
      @property
      def max_prefixlen(self):
          return self._max_prefixlen
  
      @property
      def packed(self):
          """The binary representation of this address."""
          return v6_int_to_packed(self._ip)
  
      @property
      def version(self):
          return self._version
  
      @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 IPv6Network('ff00::/8')
  
      @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 in IPv6Network('::/8') or
                  self in IPv6Network('100::/8') or
                  self in IPv6Network('200::/7') or
                  self in IPv6Network('400::/6') or
                  self in IPv6Network('800::/5') or
                  self in IPv6Network('1000::/4') or
                  self in IPv6Network('4000::/3') or
                  self in IPv6Network('6000::/3') or
                  self in IPv6Network('8000::/3') or
                  self in IPv6Network('A000::/3') or
                  self in IPv6Network('C000::/3') or
                  self in IPv6Network('E000::/4') or
                  self in IPv6Network('F000::/5') or
                  self in IPv6Network('F800::/6') or
                  self in IPv6Network('FE00::/9'))
  
      @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 and getattr(self, '_prefixlen', 128) == 128
  
      @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 and getattr(self, '_prefixlen', 128) == 128
  
      @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 IPv6Network('fe80::/10')
  
      @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 IPv6Network('fec0::/10')
  
      @property
      def is_private(self):
          """Test if this address is allocated for private networks.
  
          Returns:
              A boolean, True if the address is reserved per RFC 4193.
  
          """
          return self in IPv6Network('fc00::/7')
  
      @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 IPv6Address(_BaseV6, _BaseIP):
  
      """Represent and manipulate single IPv6 Addresses.
      """
  
      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('2001:4860::') ==
                  IPv6Address(42541956101370907050197289607612071936L).
                or, more generally
                IPv6Address(IPv6Address('2001:4860::')._ip) ==
                  IPv6Address('2001:4860::')
  
          Raises:
              AddressValueError: If address isn't a valid IPv6 address.
  
          """
          _BaseV6.__init__(self, address)
  
          # Efficient copy constructor.
          if isinstance(address, IPv6Address):
              self._ip = address._ip
              return
  
          # Efficient constructor from integer.
          if isinstance(address, (int, long)):
              self._ip = address
              if address < 0 or address > self._ALL_ONES:
                  raise AddressValueError(address)
              return
  
          # Constructing from a packed address
          if isinstance(address, Bytes):
              try:
                  hi, lo = struct.unpack('!QQ', address)
              except struct.error:
                  raise AddressValueError(address)  # Wrong length.
              self._ip = (hi << 64) | lo
              return
  
          # Assume input argument to be string or any object representation
          # which converts into a formatted IP string.
          addr_str = str(address)
          self._ip = self._ip_int_from_string(addr_str)
  
  
  class IPv6Network(_BaseV6, _BaseNet):
  
      """This class represents and manipulates 128-bit IPv6 networks.
  
      Attributes: [examples for IPv6('2001:658:22A:CAFE:200::1/64')]
          .ip: IPv6Address('2001:658:22a:cafe:200::1')
          .network: IPv6Address('2001:658:22a:cafe::')
          .hostmask: IPv6Address('::ffff:ffff:ffff:ffff')
          .broadcast: IPv6Address('2001:658:22a:cafe:ffff:ffff:ffff:ffff')
          .netmask: IPv6Address('ffff:ffff:ffff:ffff::')
          .prefixlen: 64
  
      """
  
  
      def __init__(self, address, strict=False):
          """Instantiate a new IPv6 network object.
  
          Args:
              address: The IPv6 network as a string, 2-tuple, or any format
                supported by the IPv6Address constructor.
  
                Strings should be in CIDR format, such as '2001:db8::/32'.
  
                The 2-tuple format consists of an (ip, prefixlen), where ip is any
                format recognized by the IPv6Address constructor, and prefixlen is
                an integer from 0 through 128.
  
                A plain IPv6 address (in any format) will be forwarded to the
                IPv6Address constructor, with an implied prefixlen of 128.
  
                For example, the following inputs are equivalent:
                  IPv6Network('2001:db8::/128')
                  IPv6Network('2001:db8:0:0:0:0:0:0/128')
                  IPv6Network('2001:db8::')
                  IPv6Network(0x20010db8 << 96)
                  IPv6Network(IPv6Address('2001:db8::'))
                  IPv6Network(('2001:db8::', 128))
                  IPv6Network((0x20010db8 << 96, 128))
                  IPv6Network((IPv6Address('2001:db8::'), 128))
  
              strict: A boolean. If true, ensure that we have been passed
                A true network address, eg, 2001:db8::/32 and not an
                IP address on a network, eg, 2001:db8::1/32.
  
          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.
  
          """
          _BaseNet.__init__(self, address)
          _BaseV6.__init__(self, address)
  
          # Constructing from a single IP address.
          if isinstance(address, (int, long, Bytes, IPv6Address)):
              self.ip = IPv6Address(address)
              self._ip = self.ip._ip
              self._prefixlen = self._max_prefixlen
              self.netmask = IPv6Address(self._ALL_ONES)
              return
  
          # Constructing from an (ip, prefixlen) tuple.
          if isinstance(address, tuple):
              try:
                  ip, prefixlen = address
              except ValueError:
                  raise AddressValueError(address)
              self.ip = IPv6Address(ip)
              self._ip = self.ip._ip
              self._prefixlen = self._prefix_from_prefix_int(prefixlen)
  
          else:
              # Assume input argument to be string or any object representation
              # which converts into a formatted IP prefix string.
              addr = str(address).split('/')
  
              if len(addr) > 2:
                  raise AddressValueError(address)
  
              self._ip = self._ip_int_from_string(addr[0])
              self.ip = IPv6Address(self._ip)
  
              if len(addr) == 2:
                  # This may raise NetmaskValueError
                  self._prefixlen = self._prefix_from_prefix_string(addr[1])
              else:
                  self._prefixlen = self._max_prefixlen
  
          self.netmask = IPv6Address(self._ip_int_from_prefix(self._prefixlen))
  
          if strict:
              if self.ip != self.network:
                  raise ValueError('%s has host bits set' %
                                   self.ip)
          if self._prefixlen == (self._max_prefixlen - 1):
              self.iterhosts = self.__iter__
  
      @property
      def with_netmask(self):
          return self.with_prefixlen
  