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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# Copyright (c) 2017 Cisco and/or its affiliates.
#
# 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.
#
from socket import inet_pton, inet_ntop, AF_INET6
from struct import unpack, pack
from abc import ABCMeta
class NotEnoughAddresses(Exception):
pass
class Prefix(metaclass=ABCMeta):
def __init__(self, ip_address, prefix_size=None):
if not prefix_size:
ip_address, prefix_size = ip_address.split('/')
prefix_size = int(prefix_size)
if isinstance(ip_address, str):
ip_address = self.aton(ip_address)
self.ip_address = ip_address
self.prefix_size = prefix_size
self._range = self.limits()
def __contains__(self, obj):
#it can be an IP as a integer
if isinstance(obj, int):
obj = type(self)(obj, self.MAX_PREFIX_SIZE)
#Or it's an IP string
if isinstance(obj, str):
#It's a prefix as 'IP/prefix'
if '/' in obj:
split_obj = obj.split('/')
obj = type(self)(split_obj[0], int(split_obj[1]))
else:
obj = type(self)(obj, self.MAX_PREFIX_SIZE)
return self._contains_prefix(obj)
def _contains_prefix(self, prefix):
assert isinstance(prefix, type(self))
return (prefix.prefix_size >= self.prefix_size and
prefix.ip_address >= self.first_prefix_address() and
prefix.ip_address <= self.last_prefix_address())
#Returns the first address of a prefix
def first_prefix_address(self):
return self.ip_address & (self.MASK << (self.MAX_PREFIX_SIZE-self.prefix_size))
def last_prefix_address(self):
return self.ip_address | (self.MASK >> self.prefix_size)
def limits(self):
return self.first_prefix_address(), self.last_prefix_address()
def __str__(self):
return "{}/{}".format(self.ntoa(self.first_prefix_address()), self.prefix_size)
def __eq__(self, other):
return (self.first_prefix_address() == other.first_prefix_address() and
self.prefix_size == other.prefix_size)
def __hash__(self):
return hash(str(self))
def __iter__(self):
for i in range(self._range[0], self._range[1]+1):
yield self.ntoa(i)
class Inet4Prefix(Prefix):
MASK = 0xffffffff
MAX_PREFIX_SIZE = 32
@classmethod
def aton(cls, address):
ret = 0
components = address.split('.')
for comp in components:
ret = (ret << 8) + int(comp)
return ret
@classmethod
def ntoa(cls, address):
components = []
for _ in range(0,4):
components.insert(0,'{}'.format(address % 256))
address = address >> 8
return '.'.join(components)
class Inet6Prefix(Prefix):
MASK = 0xffffffffffffffff
MAX_PREFIX_SIZE = 64
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
self._range = self.limits(True)
@classmethod
def aton (cls, address, with_suffix=False):
ret, suffix = unpack(">QQ", inet_pton(AF_INET6, address))
if with_suffix:
ret = (ret << 64) | suffix
return ret
@classmethod
def ntoa (cls, address, with_suffix=False):
ret = None
if with_suffix:
ret = inet_ntop(AF_INET6, pack(">QQ", address >> 64, address & ((1 << 64) -1)))
else:
ret = inet_ntop(AF_INET6, pack(">QQ", address, 0))
return ret
def limits(self, with_suffix=False):
ret = super().limits()
if with_suffix:
ret = ret[0] << 64, ret[1] << 64 | self.MASK
return ret
def __iter__(self):
for i in range(*self._range):
yield self.ntoa(i, True)
###### PREFIX TREE ######
class PrefixTree:
def __init__(self, prefix):
self.prefix = prefix
self.prefix_cls = type(prefix)
self.left = None
self.right = None
#When the full prefix is assigned
self.full = False
def find_prefix(self, prefix_size):
ret, lret, rret = [None]*3
if prefix_size > self.prefix.prefix_size and not self.full:
if self.left is None:
lret = self.prefix_cls(self.prefix.first_prefix_address(), self.prefix.prefix_size+1)
else:
lret = self.left.find_prefix(prefix_size)
if self.right is None:
rret = self.prefix_cls(self.prefix.last_prefix_address(), self.prefix.prefix_size+1)
else:
rret = self.right.find_prefix(prefix_size)
#Now we look for the longer prefix to assign
if not lret or (rret and rret.prefix_size > lret.prefix_size):
ret = rret
else:
ret = lret
return ret
def assign_prefix(self, prefix):
assert prefix in self.prefix
if prefix.prefix_size > self.prefix.prefix_size:
#Existing prefix on the left
lp = self.prefix_cls(self.prefix.first_prefix_address(), self.prefix.prefix_size+1)
#It's on the left branch
if prefix in lp:
if not self.left:
self.left = PrefixTree(lp)
self.left.assign_prefix(prefix)
#It's on the right branch
else:
rp = self.prefix_cls(self.prefix.last_prefix_address(), self.prefix.prefix_size+1)
if not self.right:
self.right = PrefixTree(rp)
self.right.assign_prefix(prefix)
elif self.prefix == prefix:
self.full = True
else:
raise RuntimeError("And you may ask yourself, well, how did I get here?")
def get_prefix(self, prefix_size):
ret = self.find_prefix(prefix_size)
if not ret:
raise NotEnoughAddresses
#find_prefix returns the size of the largest available prefix in our space
#not necessarily the one we asked for
ret.prefix_size = prefix_size
self.assign_prefix(ret)
return ret
def get_assigned_prefixes(self):
ret = []
if not self.right and not self.left and self.full:
ret.append(self.prefix)
else:
if self.right:
ret.extend(self.right.get_assigned_prefixes())
if self.left:
ret.extend(self.left.get_assigned_prefixes())
return ret
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