root / lib / network.py @ a5c198eb
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#
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# Copyright (C) 2011, 2012 Google Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301, USA.
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"""IP address pool management functions.
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"""
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import ipaddr |
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from bitarray import bitarray |
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from base64 import b64encode |
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from base64 import b64decode |
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from ganeti import errors |
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def _ComputeIpv4NumHosts(network_size): |
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"""Derives the number of hosts in an IPv4 network from the size.
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"""
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return 2 ** (32 - network_size) |
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IPV4_NETWORK_MIN_SIZE = 30
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# FIXME: This limit is for performance reasons. Remove when refactoring
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# for performance tuning was successful.
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IPV4_NETWORK_MAX_SIZE = 16
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IPV4_NETWORK_MIN_NUM_HOSTS = _ComputeIpv4NumHosts(IPV4_NETWORK_MIN_SIZE) |
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IPV4_NETWORK_MAX_NUM_HOSTS = _ComputeIpv4NumHosts(IPV4_NETWORK_MAX_SIZE) |
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class AddressPool(object): |
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"""Address pool class, wrapping an C{objects.Network} object.
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This class provides methods to manipulate address pools, backed by
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L{objects.Network} objects.
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"""
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FREE = bitarray("0")
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RESERVED = bitarray("1")
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def __init__(self, network): |
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"""Initialize a new IPv4 address pool from an L{objects.Network} object.
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@type network: L{objects.Network}
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@param network: the network object from which the pool will be generated
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"""
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self.network = None |
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self.gateway = None |
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self.network6 = None |
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self.gateway6 = None |
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self.net = network
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self.network = ipaddr.IPNetwork(self.net.network) |
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if self.network.numhosts > IPV4_NETWORK_MAX_NUM_HOSTS: |
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raise errors.AddressPoolError("A big network with %s host(s) is currently" |
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" not supported. please specify at most a"
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" /%s network" %
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(str(self.network.numhosts), |
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IPV4_NETWORK_MAX_SIZE)) |
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if self.network.numhosts < IPV4_NETWORK_MIN_NUM_HOSTS: |
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raise errors.AddressPoolError("A network with only %s host(s) is too" |
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" small, please specify at least a /%s"
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" network" %
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(str(self.network.numhosts), |
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IPV4_NETWORK_MIN_SIZE)) |
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if self.net.gateway: |
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self.gateway = ipaddr.IPAddress(self.net.gateway) |
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if self.net.network6: |
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self.network6 = ipaddr.IPv6Network(self.net.network6) |
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if self.net.gateway6: |
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self.gateway6 = ipaddr.IPv6Address(self.net.gateway6) |
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if self.net.reservations: |
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self.reservations = bitarray()
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# pylint: disable=E1103
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self.reservations.frombytes(b64decode(self.net.reservations)) |
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else:
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self.reservations = bitarray(self.network.numhosts) |
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# pylint: disable=E1103
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self.reservations.setall(False) |
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if self.net.ext_reservations: |
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self.ext_reservations = bitarray()
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# pylint: disable=E1103
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self.ext_reservations.frombytes(b64decode(self.net.ext_reservations)) |
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else:
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self.ext_reservations = bitarray(self.network.numhosts) |
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# pylint: disable=E1103
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self.ext_reservations.setall(False) |
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assert len(self.reservations) == self.network.numhosts |
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assert len(self.ext_reservations) == self.network.numhosts |
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def Contains(self, address): |
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if address is None: |
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return False |
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addr = ipaddr.IPAddress(address) |
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return addr in self.network |
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def _GetAddrIndex(self, address): |
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addr = ipaddr.IPAddress(address) |
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if not addr in self.network: |
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raise errors.AddressPoolError("%s does not contain %s" % |
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(self.network, addr))
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return int(addr) - int(self.network.network) |
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def Update(self): |
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"""Write address pools back to the network object.
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"""
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# pylint: disable=E1103
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self.net.ext_reservations = b64encode(self.ext_reservations.tobytes()) |
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self.net.reservations = b64encode(self.reservations.tobytes()) |
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def _Mark(self, address, value=True, external=False): |
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idx = self._GetAddrIndex(address)
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if external:
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self.ext_reservations[idx] = value
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else:
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self.reservations[idx] = value
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self.Update()
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def _GetSize(self): |
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return 2 ** (32 - self.network.prefixlen) |
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@property
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def all_reservations(self): |
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"""Return a combined map of internal and external reservations.
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"""
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return (self.reservations | self.ext_reservations) |
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def Validate(self): |
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assert len(self.reservations) == self._GetSize() |
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assert len(self.ext_reservations) == self._GetSize() |
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if self.gateway is not None: |
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assert self.gateway in self.network |
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if self.network6 and self.gateway6: |
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assert self.gateway6 in self.network6 or self.gateway6.is_link_local |
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return True |
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def IsFull(self): |
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"""Check whether the network is full.
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"""
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return self.all_reservations.all() |
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def GetReservedCount(self): |
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"""Get the count of reserved addresses.
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"""
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return self.all_reservations.count(True) |
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def GetFreeCount(self): |
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"""Get the count of unused addresses.
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"""
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return self.all_reservations.count(False) |
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def GetMap(self): |
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"""Return a textual representation of the network's occupation status.
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"""
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return self.all_reservations.to01().replace("1", "X").replace("0", ".") |
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def IsReserved(self, address, external=False): |
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"""Checks if the given IP is reserved.
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"""
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idx = self._GetAddrIndex(address)
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if external:
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return self.ext_reservations[idx] |
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else:
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return self.reservations[idx] |
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def Reserve(self, address, external=False): |
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"""Mark an address as used.
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"""
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if self.IsReserved(address, external): |
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if external:
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msg = "IP %s is already externally reserved" % address
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else:
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msg = "IP %s is already used by an instance" % address
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raise errors.AddressPoolError(msg)
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self._Mark(address, external=external)
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def Release(self, address, external=False): |
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"""Release a given address reservation.
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"""
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if not self.IsReserved(address, external): |
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if external:
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msg = "IP %s is not externally reserved" % address
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else:
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msg = "IP %s is not used by an instance" % address
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raise errors.AddressPoolError(msg)
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self._Mark(address, value=False, external=external) |
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def GetFreeAddress(self): |
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"""Returns the first available address.
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"""
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if self.IsFull(): |
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raise errors.AddressPoolError("%s is full" % self.network) |
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idx = self.all_reservations.index(False) |
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address = str(self.network[idx]) |
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self.Reserve(address)
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return address
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def GenerateFree(self): |
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"""Returns the first free address of the network.
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@raise errors.AddressPoolError: Pool is full
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"""
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idx = self.all_reservations.search(self.FREE, 1) |
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if idx:
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return str(self.network[idx[0]]) |
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else:
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raise errors.AddressPoolError("%s is full" % self.network) |
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def GetExternalReservations(self): |
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"""Returns a list of all externally reserved addresses.
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"""
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# pylint: disable=E1103
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idxs = self.ext_reservations.search(self.RESERVED) |
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return [str(self.network[idx]) for idx in idxs] |
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@classmethod
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def InitializeNetwork(cls, net): |
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"""Initialize an L{objects.Network} object.
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Reserve the network, broadcast and gateway IP addresses.
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"""
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obj = cls(net) |
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obj.Update() |
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for ip in [obj.network[0], obj.network[-1]]: |
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obj.Reserve(ip, external=True)
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if obj.net.gateway is not None: |
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obj.Reserve(obj.net.gateway, external=True)
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obj.Validate() |
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return obj
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