network.py 5.81 KB
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#
#

# Copyright (C) 2011 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.


"""Ip address pool management functions.

"""

import ipaddr

from bitarray import bitarray

from ganeti import errors

class AddressPool(object):
  """Address pool class, wrapping an objects.Network object

  This class provides methods to manipulate address pools, backed by
  L{objects.Network} objects.

  """
  def __init__(self, network):
    """Initialize a new IPv4 address pool from an objects.Network object

    @type network: L{objects.Network}
    @param network: the network object from which the pool will be generated

    """
    self.network = None
    self.gateway = None
    self.network6 = None
    self.gateway6 = None

    self.net = network

    self.network = ipaddr.IPNetwork(self.net.network)
    if self.net.gateway:
      self.gateway = ipaddr.IPAddress(self.net.gateway)

    if self.net.network6:
      self.network6 = ipaddr.IPv6Network(self.net.network6)
    if self.net.gateway6:
      self.gateway6 = ipaddr.IPv6Address(self.net.gateway6)

    if self.net.reservations:
      self.reservations = bitarray(self.net.reservations)
    else:
      self.reservations = bitarray(self.network.numhosts)
      self.reservations.setall(False)

    if self.net.ext_reservations:
      self.ext_reservations = bitarray(self.net.ext_reservations)
    else:
      self.ext_reservations = bitarray(self.network.numhosts)
      self.ext_reservations.setall(False)

    assert len(self.reservations) == self.network.numhosts
    assert len(self.ext_reservations) == self.network.numhosts

  def _Contains(self, address):
    if address is None:
      return False
    addr = ipaddr.IPAddress(address)

    return addr in self.network

  def _GetAddrIndex(self, address):
    addr = ipaddr.IPAddress(address)

    if not addr in self.network:
      raise errors.AddressPoolError("%s does not contain %s" %
                                    (self.network, addr))

    return int(addr) - int(self.network.network)

  def _Update(self):
    """Write address pools back to the network object"""
    self.net.ext_reservations = self.ext_reservations.to01()
    self.net.reservations = self.reservations.to01()

  def _Mark(self, address, value=True, external=False):
    idx = self._GetAddrIndex(address)
    if external:
      self.ext_reservations[idx] = value
    else:
      self.reservations[idx] = value
    self._Update()

  def _GetSize(self):
    return 2**(32 - self.network.prefixlen)

  @property
  def all_reservations(self):
    """Return a combined map of internal + external reservations."""
    return (self.reservations | self.ext_reservations)

  def Validate(self):
    assert self.net.family == 4
    assert len(self.reservations) == self._GetSize()
    assert len(self.ext_reservations) == self._GetSize()
    assert not (self.reservations & self.ext_reservations).any()

    if self.gateway is not None:
      assert self.net.family == self.gateway.version
      assert self.gateway in self.network

    if self.network6 and self.gateway6:
      assert self.gateway6 in self.network6

    return True

  def IsFull(self):
    """Check whether the network is full"""
    return self.all_reservations.all()

  def GetReservedCount(self):
    """Get the count of reserved addresses"""
    return self.all_reservations.count(True)

  def GetFreeCount(self):
    """Get the count of unused addresses"""
    return self.all_reservations.count(False)

  def GetMap(self):
    """Return a textual representation of the network's occupation status."""
    return self.all_reservations.to01().replace("1", "X").replace("0", ".")

  def IsReserved(self, address):
    """Checks if the given IP is reserved"""
    idx = self._GetAddrIndex(address)
    return self.all_reservations[idx]

  def Reserve(self, address, external=False):
    """Mark an address as used."""
    if self.IsReserved(address):
      raise errors.AddressPoolError("%s is already reserved" % address)
    self._Mark(address, external=external)

  def Release(self, address, external=False):
    """Release a given address reservation."""
    self._Mark(address, value=False, external=external)

  def GetFreeAddress(self):
    """Returns the first available address."""
    if self.IsFull():
      raise errors.AddressPoolError("%s is full" % self.network)

    idx = self.all_reservations.index(False)
    address = str(self.network[idx])
    self.Reserve(address)
    return address

  def GenerateFree(self):
    """A generator for free addresses."""
    def _iter_free():
      for idx in self.all_reservations.search("0", 64):
        yield str(self.network[idx])

    return _iter_free().next

  def GetExternalReservations(self):
    """Returns a list of all externally reserved addresses"""
    idxs = self.ext_reservations.search("1")
    return [str(self.network[idx]) for idx in idxs]

  @classmethod
  def InitializeNetwork(cls, net):
    """Initialize an L{objects.Network} object

    Reserve the network, broadcast and gateway IPs

    """
    obj = cls(net)
    obj._Update()
    for ip in [obj.network[0], obj.network[-1]]:
      obj.Reserve(ip, external=True)
    if obj.net.gateway is not None:
      obj.Reserve(obj.net.gateway, external=True)
    obj.Validate()
    return obj