274 lines
8.1 KiB
Python
274 lines
8.1 KiB
Python
|
#-----------------------------------------------------------------------------
|
||
|
|
# Copyright (c) 2008-2012, David P. D. Moss. All rights reserved.
|
||
|
|
#
|
||
|
|
# Released under the BSD license. See the LICENSE file for details.
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
"""
|
||
|
|
Shared logic for various address types.
|
||
|
|
"""
|
||
|
|
import re as _re
|
||
|
|
|
||
|
|
from netaddr.compat import _range
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def bytes_to_bits():
|
||
|
|
"""
|
||
|
|
:return: A 256 element list containing 8-bit binary digit strings. The
|
||
|
|
list index value is equivalent to its bit string value.
|
||
|
|
"""
|
||
|
|
lookup = []
|
||
|
|
bits_per_byte = _range(7, -1, -1)
|
||
|
|
for num in range(256):
|
||
|
|
bits = 8 * [None]
|
||
|
|
for i in bits_per_byte:
|
||
|
|
bits[i] = '01'[num & 1]
|
||
|
|
num >>= 1
|
||
|
|
lookup.append(''.join(bits))
|
||
|
|
return lookup
|
||
|
|
|
||
|
|
#: A lookup table of 8-bit integer values to their binary digit bit strings.
|
||
|
|
BYTES_TO_BITS = bytes_to_bits()
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def valid_words(words, word_size, num_words):
|
||
|
|
"""
|
||
|
|
:param words: A sequence of unsigned integer word values.
|
||
|
|
|
||
|
|
:param word_size: Width (in bits) of each unsigned integer word value.
|
||
|
|
|
||
|
|
:param num_words: Number of unsigned integer words expected.
|
||
|
|
|
||
|
|
:return: ``True`` if word sequence is valid for this address type,
|
||
|
|
``False`` otherwise.
|
||
|
|
"""
|
||
|
|
if not hasattr(words, '__iter__'):
|
||
|
|
return False
|
||
|
|
|
||
|
|
if len(words) != num_words:
|
||
|
|
return False
|
||
|
|
|
||
|
|
max_word = 2 ** word_size - 1
|
||
|
|
|
||
|
|
for i in words:
|
||
|
|
if not 0 <= i <= max_word:
|
||
|
|
return False
|
||
|
|
|
||
|
|
return True
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def int_to_words(int_val, word_size, num_words):
|
||
|
|
"""
|
||
|
|
:param int_val: Unsigned integer to be divided into words of equal size.
|
||
|
|
|
||
|
|
:param word_size: Width (in bits) of each unsigned integer word value.
|
||
|
|
|
||
|
|
:param num_words: Number of unsigned integer words expected.
|
||
|
|
|
||
|
|
:return: A tuple contain unsigned integer word values split according
|
||
|
|
to provided arguments.
|
||
|
|
"""
|
||
|
|
max_int = 2 ** (num_words * word_size) - 1
|
||
|
|
|
||
|
|
if not 0 <= int_val <= max_int:
|
||
|
|
raise IndexError('integer out of bounds: %r!' % hex(int_val))
|
||
|
|
|
||
|
|
max_word = 2 ** word_size - 1
|
||
|
|
|
||
|
|
words = []
|
||
|
|
for _ in range(num_words):
|
||
|
|
word = int_val & max_word
|
||
|
|
words.append(int(word))
|
||
|
|
int_val >>= word_size
|
||
|
|
|
||
|
|
return tuple(reversed(words))
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def words_to_int(words, word_size, num_words):
|
||
|
|
"""
|
||
|
|
:param words: A sequence of unsigned integer word values.
|
||
|
|
|
||
|
|
:param word_size: Width (in bits) of each unsigned integer word value.
|
||
|
|
|
||
|
|
:param num_words: Number of unsigned integer words expected.
|
||
|
|
|
||
|
|
:return: An unsigned integer that is equivalent to value represented
|
||
|
|
by word sequence.
|
||
|
|
"""
|
||
|
|
if not valid_words(words, word_size, num_words):
|
||
|
|
raise ValueError('invalid integer word sequence: %r!' % words)
|
||
|
|
|
||
|
|
int_val = 0
|
||
|
|
for i, num in enumerate(reversed(words)):
|
||
|
|
word = num
|
||
|
|
word = word << word_size * i
|
||
|
|
int_val = int_val | word
|
||
|
|
|
||
|
|
return int_val
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def valid_bits(bits, width, word_sep=''):
|
||
|
|
"""
|
||
|
|
:param bits: A network address in a delimited binary string format.
|
||
|
|
|
||
|
|
:param width: Maximum width (in bits) of a network address (excluding
|
||
|
|
delimiters).
|
||
|
|
|
||
|
|
:param word_sep: (optional) character or string used to delimit word
|
||
|
|
groups (default: '', no separator).
|
||
|
|
|
||
|
|
:return: ``True`` if network address is valid, ``False`` otherwise.
|
||
|
|
"""
|
||
|
|
if not hasattr(bits, 'replace'):
|
||
|
|
return False
|
||
|
|
|
||
|
|
if word_sep != '':
|
||
|
|
bits = bits.replace(word_sep, '')
|
||
|
|
|
||
|
|
if len(bits) != width:
|
||
|
|
return False
|
||
|
|
|
||
|
|
max_int = 2 ** width - 1
|
||
|
|
|
||
|
|
try:
|
||
|
|
if 0 <= int(bits, 2) <= max_int:
|
||
|
|
return True
|
||
|
|
except ValueError:
|
||
|
|
pass
|
||
|
|
|
||
|
|
return False
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def bits_to_int(bits, width, word_sep=''):
|
||
|
|
"""
|
||
|
|
:param bits: A network address in a delimited binary string format.
|
||
|
|
|
||
|
|
:param width: Maximum width (in bits) of a network address (excluding
|
||
|
|
delimiters).
|
||
|
|
|
||
|
|
:param word_sep: (optional) character or string used to delimit word
|
||
|
|
groups (default: '', no separator).
|
||
|
|
|
||
|
|
:return: An unsigned integer that is equivalent to value represented
|
||
|
|
by network address in readable binary form.
|
||
|
|
"""
|
||
|
|
if not valid_bits(bits, width, word_sep):
|
||
|
|
raise ValueError('invalid readable binary string: %r!' % bits)
|
||
|
|
|
||
|
|
if word_sep != '':
|
||
|
|
bits = bits.replace(word_sep, '')
|
||
|
|
|
||
|
|
return int(bits, 2)
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def int_to_bits(int_val, word_size, num_words, word_sep=''):
|
||
|
|
"""
|
||
|
|
:param int_val: An unsigned integer.
|
||
|
|
|
||
|
|
:param word_size: Width (in bits) of each unsigned integer word value.
|
||
|
|
|
||
|
|
:param num_words: Number of unsigned integer words expected.
|
||
|
|
|
||
|
|
:param word_sep: (optional) character or string used to delimit word
|
||
|
|
groups (default: '', no separator).
|
||
|
|
|
||
|
|
:return: A network address in a delimited binary string format that is
|
||
|
|
equivalent in value to unsigned integer.
|
||
|
|
"""
|
||
|
|
bit_words = []
|
||
|
|
|
||
|
|
for word in int_to_words(int_val, word_size, num_words):
|
||
|
|
bits = []
|
||
|
|
while word:
|
||
|
|
bits.append(BYTES_TO_BITS[word & 255])
|
||
|
|
word >>= 8
|
||
|
|
bits.reverse()
|
||
|
|
bit_str = ''.join(bits) or '0' * word_size
|
||
|
|
bits = ('0' * word_size + bit_str)[-word_size:]
|
||
|
|
bit_words.append(bits)
|
||
|
|
|
||
|
|
if word_sep is not '':
|
||
|
|
# Check custom separator.
|
||
|
|
if not hasattr(word_sep, 'join'):
|
||
|
|
raise ValueError('word separator is not a string: %r!' % word_sep)
|
||
|
|
|
||
|
|
return word_sep.join(bit_words)
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def valid_bin(bin_val, width):
|
||
|
|
"""
|
||
|
|
:param bin_val: A network address in Python's binary representation format
|
||
|
|
('0bxxx').
|
||
|
|
|
||
|
|
:param width: Maximum width (in bits) of a network address (excluding
|
||
|
|
delimiters).
|
||
|
|
|
||
|
|
:return: ``True`` if network address is valid, ``False`` otherwise.
|
||
|
|
"""
|
||
|
|
if not hasattr(bin_val, 'startswith'):
|
||
|
|
return False
|
||
|
|
|
||
|
|
if not bin_val.startswith('0b'):
|
||
|
|
return False
|
||
|
|
|
||
|
|
bin_val = bin_val.replace('0b', '')
|
||
|
|
|
||
|
|
if len(bin_val) > width:
|
||
|
|
return False
|
||
|
|
|
||
|
|
max_int = 2 ** width - 1
|
||
|
|
|
||
|
|
try:
|
||
|
|
if 0 <= int(bin_val, 2) <= max_int:
|
||
|
|
return True
|
||
|
|
except ValueError:
|
||
|
|
pass
|
||
|
|
|
||
|
|
return False
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def int_to_bin(int_val, width):
|
||
|
|
"""
|
||
|
|
:param int_val: An unsigned integer.
|
||
|
|
|
||
|
|
:param width: Maximum allowed width (in bits) of a unsigned integer.
|
||
|
|
|
||
|
|
:return: Equivalent string value in Python's binary representation format
|
||
|
|
('0bxxx').
|
||
|
|
"""
|
||
|
|
bin_tokens = []
|
||
|
|
|
||
|
|
try:
|
||
|
|
# Python 2.6.x and upwards.
|
||
|
|
bin_val = bin(int_val)
|
||
|
|
except NameError:
|
||
|
|
# Python 2.4.x and 2.5.x
|
||
|
|
i = int_val
|
||
|
|
while i > 0:
|
||
|
|
word = i & 0xff
|
||
|
|
bin_tokens.append(BYTES_TO_BITS[word])
|
||
|
|
i >>= 8
|
||
|
|
|
||
|
|
bin_tokens.reverse()
|
||
|
|
bin_val = '0b' + _re.sub(r'^[0]+([01]+)$', r'\1', ''.join(bin_tokens))
|
||
|
|
|
||
|
|
if len(bin_val[2:]) > width:
|
||
|
|
raise IndexError('binary string out of bounds: %s!' % bin_val)
|
||
|
|
|
||
|
|
return bin_val
|
||
|
|
|
||
|
|
#-----------------------------------------------------------------------------
|
||
|
|
def bin_to_int(bin_val, width):
|
||
|
|
"""
|
||
|
|
:param bin_val: A string containing an unsigned integer in Python's binary
|
||
|
|
representation format ('0bxxx').
|
||
|
|
|
||
|
|
:param width: Maximum allowed width (in bits) of a unsigned integer.
|
||
|
|
|
||
|
|
:return: An unsigned integer that is equivalent to value represented
|
||
|
|
by Python binary string format.
|
||
|
|
"""
|
||
|
|
if not valid_bin(bin_val, width):
|
||
|
|
raise ValueError('not a valid Python binary string: %r!' % bin_val)
|
||
|
|
|
||
|
|
return int(bin_val.replace('0b', ''), 2)
|