390 lines
12 KiB
Python
390 lines
12 KiB
Python
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# SPDX-License-Identifier: 0BSD
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# Copyright 2021 Alexander Kozhevnikov <mentalisttraceur@gmail.com>
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"""Like ``ipaddress``, but for hardware identifiers such as MAC addresses."""
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__all__ = (
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'HWAddress',
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'OUI',
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'CDI32', 'CDI40',
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'MAC',
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'EUI48', 'EUI60', 'EUI64',
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'parse',
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)
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__version__ = '2.0.2'
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from functools import total_ordering as _total_ordering
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_HEX_DIGITS = "0123456789ABCDEFabcdef"
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def _name(obj):
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return type(obj).__name__
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def _class_names_in_proper_english(classes):
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class_names = [cls.__name__ for cls in classes]
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number_of_classes = len(classes)
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if number_of_classes < 2:
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return class_names[0]
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elif number_of_classes == 2:
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return ' or '.join(class_names)
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else:
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class_names[-1] = 'or ' + class_names[-1]
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return ', '.join(class_names)
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def _type_error(value, *classes):
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class_names = _class_names_in_proper_english(classes)
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return TypeError(repr(value) + ' has wrong type for ' + class_names)
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def _value_error(value, error, *classes):
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class_names = _class_names_in_proper_english(classes)
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return ValueError(repr(value) + ' ' + error + ' ' + class_names)
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@_total_ordering
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class HWAddress:
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"""Base class for hardware addresses.
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Can be subclassed to create new address types
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by just defining a couple class attribures.
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Attributes:
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size: An integer defined by each subclass to specify the size
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(in bits) of the hardware address.
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formats: A sequence of format strings defined by each subclass
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to specify what formats the class can parse. The first
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format string is also used for ``repr`` and ``str`` output.
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Each "x" in each format string stands for one hexadecimal
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digit. All other characters are literal. For example, for
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MAC addresses, the format strings are "xx-xx-xx-xx-xx-xx",
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"xx:xx:xx:xx:xx:xx", "xxxx.xxxx.xxxx", and "xxxxxxxxxxxx".
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"""
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__slots__ = ('_address', '__weakref__')
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formats = ()
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def __init__(self, address):
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"""Initialize the hardware address object with the address given.
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Arguments:
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address: An ``int``, ``bytes``, or ``str`` representation of
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the address, or another instance of an address which is
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either the same class, a subclass, or a superclass. If a
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string, the ``formats`` attribute of the class is used
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to parse it. If a byte string, it is read in big-endian.
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If an integer, its value bytes in big-endian are used as
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the address bytes.
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Raises:
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TypeError: If ``address`` is not one of the valid types.
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ValueError: If ``address`` is a string but does not match
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one of the formats, if ``address`` is a byte string
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but does not match the size, or if ``address`` is an
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integer with a value that is negative or too big.
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"""
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if isinstance(address, int):
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overflow = 1 << type(self).size
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if address >= overflow:
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raise _value_error(address, 'is too big for', type(self))
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if address < 0:
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raise ValueError('hardware address cannot be negative')
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self._address = address
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elif isinstance(address, bytes):
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length = len(address)
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size_in_bytes = (type(self).size + 7) >> 3
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if length != size_in_bytes:
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raise _value_error(address, 'has wrong length for', type(self))
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offset = (8 - type(self).size) & 7
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self._address = int.from_bytes(address, 'big') >> offset
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elif isinstance(address, str) and len(type(self).formats):
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self._address, _ = _parse(address, type(self))
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# Subclass being "cast" to superclass:
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elif isinstance(address, type(self)):
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self._address = int(address)
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# Superclass being "cast" to subclass:
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elif (isinstance(address, HWAddress)
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and isinstance(self, type(address))):
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self._address = int(address)
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else:
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raise _type_error(address, type(self))
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def __repr__(self):
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"""Represent the hardware address as an unambiguous string."""
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try:
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address = repr(str(self))
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except TypeError:
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address = _hex(int(self), type(self).size)
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return _name(self) + '(' + address + ')'
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def __str__(self):
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"""Get the canonical human-readable string of this hardware address."""
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formats = type(self).formats
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if not len(formats):
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raise TypeError(_name(self) + ' has no string format')
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result = []
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offset = (4 - type(self).size) & 3
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unconsumed_address_value = int(self) << offset
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for character in reversed(formats[0]):
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if character == 'x':
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nibble = unconsumed_address_value & 0xf
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result.append(_HEX_DIGITS[nibble])
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unconsumed_address_value >>= 4
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else:
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result.append(character)
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return ''.join(reversed(result))
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def __bytes__(self):
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"""Get the big-endian byte string of this hardware address."""
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offset = (8 - type(self).size) & 7
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size_in_bytes = (type(self).size + 7) >> 3
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return (int(self) << offset).to_bytes(size_in_bytes, 'big')
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def __int__(self):
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"""Get the raw integer value of this hardware address."""
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return self._address
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def __eq__(self, other):
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"""Check if this hardware address is equal to another.
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Hardware addresses are equal if they are instances of the
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same class, and their raw bit strings are the same.
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"""
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if not isinstance(other, HWAddress):
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return NotImplemented
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return type(self) == type(other) and int(self) == int(other)
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def __lt__(self, other):
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"""Check if this hardware address is before another.
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Hardware addresses are sorted by their raw bit strings,
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regardless of the exact hardware address class or size.
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For example: ``OUI('00-00-00') < CDI32('00-00-00-00')``,
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and they both are less than ``OUI('00-00-01')``.
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This order intuitively groups address prefixes like OUIs
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with (and just in front of) addresses like MAC addresses
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which have that prefix when sorting a list of them.
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"""
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if not isinstance(other, HWAddress):
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return NotImplemented
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class1 = type(self)
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class2 = type(other)
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size1 = class1.size
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size2 = class2.size
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bits1 = int(self)
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bits2 = int(other)
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if size1 > size2:
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bits2 <<= size1 - size2
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else:
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bits1 <<= size2 - size1
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return (bits1, size1, id(class1)) < (bits2, size2, id(class2))
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def __hash__(self):
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"""Get the hash of this hardware address."""
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return hash((type(self), int(self)))
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def _hex(integer, bits):
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# Like the built-in function ``hex`` but pads the
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# output to ``bits`` worth of hex characters.
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#
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# Examples:
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# (integer=5, bits=32) -> '0x00000005'
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# (integer=0x1234, bits=32) -> '0x00001234'
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# (integer=0x1234, bits=16) -> '0x1234'
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return '0x' + hex((1 << (bits+3)) | integer)[3:]
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class OUI(HWAddress):
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"""Organizationally Unique Identifier."""
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__slots__ = ()
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size = 24
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formats = (
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'xx-xx-xx',
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'xx:xx:xx',
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'xxxxxx',
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)
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class _StartsWithOUI(HWAddress):
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__slots__ = ()
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@property
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def oui(self):
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"""Get the OUI part of this hardware address."""
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return OUI(int(self) >> (type(self).size - OUI.size))
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class CDI32(_StartsWithOUI):
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"""32-bit Context Dependent Identifier (CDI-32)."""
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__slots__ = ()
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size = 32
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formats = (
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'xx-xx-xx-xx',
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'xx:xx:xx:xx',
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'xxxxxxxx',
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)
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class CDI40(_StartsWithOUI):
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"""40-bit Context Dependent Identifier (CDI-40)."""
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__slots__ = ()
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size = 40
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formats = (
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'xx-xx-xx-xx-xx',
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'xx:xx:xx:xx:xx',
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'xxxxxxxxxx',
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)
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class EUI48(_StartsWithOUI):
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"""48-Bit Extended Unique Identifier (EUI-48).
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EUI-48 is also the modern official name for what
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many people are used to calling a "MAC address".
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"""
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__slots__ = ()
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size = 48
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formats = (
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'xx-xx-xx-xx-xx-xx',
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'xx:xx:xx:xx:xx:xx',
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'xxxx.xxxx.xxxx',
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'xxxxxxxxxxxx',
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)
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MAC = EUI48
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class EUI60(_StartsWithOUI):
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"""60-Bit Extended Unique Identifier (EUI-60)."""
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__slots__ = ()
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size = 60
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formats = (
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'x.x.x.x.x.x.x.x.x.x.x.x.x.x.x',
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'xx-xx-xx.x.x.x.x.x.x.x.x.x',
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'xxxxxxxxxxxxxxx',
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)
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class EUI64(_StartsWithOUI):
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"""64-Bit Extended Unique Identifier (EUI-64)."""
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__slots__ = ()
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size = 64
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formats = (
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'xx-xx-xx-xx-xx-xx-xx-xx',
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'xx:xx:xx:xx:xx:xx:xx:xx',
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'xxxx.xxxx.xxxx.xxxx',
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'xxxxxxxxxxxxxxxx',
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)
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def parse(value, *classes):
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"""Try parsing a value as several hardware address classes at once.
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This lets you just write
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address = macaddress.parse(user_input, EUI64, EUI48, ...)
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instead of all of this:
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try:
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address = macaddress.EUI64(user_input)
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except ValueError:
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try:
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address = macaddress.EUI48(user_input)
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except ValueError:
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...
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Arguments:
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value: The value to parse as a hardware address. Either a
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string, byte string, or an instance of one of the classes.
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*classes: HWAddress subclasses to try to parse the string as.
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If the input address could parse as more than one of the
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classes, it is parsed as the first one.
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Returns:
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HWAddress: The parsed hardware address if the value argument
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was a string or byte string, or the value argument itself
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if it was already an instance of one of the classes.
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Raises:
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TypeError: If the value is not one of the valid types,
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or if no classes were passed in.
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ValueError: If the value could not be parsed as any
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of the given classes.
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"""
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if not classes:
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raise TypeError('parse() requires at least one class argument')
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if isinstance(value, str):
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address, cls = _parse(value, *classes)
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return cls(address)
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elif isinstance(value, bytes):
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max_size = len(value) * 8
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min_size = max_size - 7
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for cls in classes:
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if min_size <= cls.size <= max_size:
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return cls(value)
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raise _value_error(value, 'has wrong length for', *classes)
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elif isinstance(value, classes):
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return value
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raise _type_error(value, *classes)
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def _parse(string, *classes):
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length = len(string)
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if length < 1:
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raise ValueError('hardware address cannot be an empty string')
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candidates = {}
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for cls in classes:
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for format_ in cls.formats:
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if len(format_) == length:
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candidates.setdefault(format_, cls)
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candidates = sorted(candidates.items())
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address = 0
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start = 0
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end = len(candidates)
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for index in range(length):
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character = string[index]
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if character in _HEX_DIGITS:
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address <<= 4
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address += int(character, 16)
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character = 'x'
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elif character == 'x':
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character = ''
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while start < end and candidates[start][0][index] < character:
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start += 1
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while start < end and candidates[end - 1][0][index] > character:
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end -= 1
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if start >= end:
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raise _value_error(string, 'cannot be parsed as', *classes)
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_, cls = candidates[start]
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offset = (4 - cls.size) & 3
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address >>= offset
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return address, cls
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