port_range.PortRange.parse_range() - Code Metrics - Inspection of "Add default isort config." - scaleway/port-range - Measure and Improve Code Quality continuously with Scrutinizer

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created 2016-12-14 19:28 UTC

port_range.PortRange.parse_range() D

↳ Parent: PortRange

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cc	10
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loc	22
rs	4.5957

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# -*- coding: utf-8 -*-
#
# Copyright (c) 2014-2015 Scaleway and Contributors. All Rights Reserved.
#                         Kevin Deldycke <[email protected]>
#                         Gilles Dartiguelongue <[email protected]>
#
# Licensed under the BSD 2-Clause License (the "License"); you may not use this
# file except in compliance with the License. You may obtain a copy of the
# License at http://opensource.org/licenses/BSD-2-Clause

""" Port range utilities and helpers.
"""

from __future__ import (absolute_import, division, print_function,
                        unicode_literals)

import math

try:
    basestring
except NameError:  # pragma: no cover
    basestring = (str, bytes)  # pylint: disable=C0103

try:
    from itertools import imap as iter_map
except ImportError:  # pragma: no cover
    iter_map = map


__version__ = '1.0.6'


class PortRange(object):
    """ Port range with support of a CIDR-like (binary) notation.

    In strict mode (disabled by default) we'll enforce the following rules:
        * port base must be a power of two (offsets not allowed);
        * port CIDR should not produce overflowing upper bound.

    This mode can be disabled on object creation.
    """
    # Separators constants
    CIDR_SEP = '/'
    RANGE_SEP = '-'

    # Max port lenght, in bits
    port_lenght = 16
    # Max port range integer values
    port_min = 1
    port_max = (2 ** port_lenght) - 1

    # Base values on which all other properties are computed.
    port_from = None
    port_to = None

    def __init__(self, port_range, strict=False):
        """ Set up class with a port_from and port_to integer. """
        self.port_from, self.port_to = self.parse(port_range, strict=strict)

    def parse(self, port_range, strict=False):
        """ Parse and normalize port range string into a port range. """
        if isinstance(port_range, basestring) and self.CIDR_SEP in port_range:
            base, prefix = self.parse_cidr(port_range, strict)
            port_from, port_to = self._cidr_to_range(base, prefix)
        else:
            port_from, port_to = self.parse_range(port_range)
        if not port_from or not port_to:
            raise ValueError("Invalid ports.")
        # Check upper bound
        if strict:
            # Disallow overflowing upper bound
            if port_to > self.port_max:
                raise ValueError("Overflowing upper bound.")
        else:
            # Cap upper bound
            port_to = port_to if port_to < self.port_max else self.port_max
        return port_from, port_to

    def parse_cidr(self, port_range, strict=False):
        """ Split a string and extract port base and CIDR prefix.

        Always returns a list of 2 integers. Defaults to None.
        """
        # Separate base and prefix
        elements = list(iter_map(int, port_range.split(self.CIDR_SEP, 2)))
        elements += [None, None]
        base, prefix = elements[:2]
        # Normalize prefix value
        if prefix is None:
            prefix = self.port_lenght
        # Validates base and prefix values
        if not base or base < self.port_min or base > self.port_max:
            raise ValueError("Invalid port base.")
        if not prefix or prefix < 1 or prefix > self.port_lenght:
            raise ValueError("Invalid CIDR-like prefix.")
        # Enable rigorous rules
        if strict:
            # Disallow offsets
            if prefix != self.port_lenght and not self._is_power_of_two(base):
                raise ValueError("Port base is not a power of Two.")
        return base, prefix

    def parse_range(self, port_range):
        """ Normalize port range to a sorted list of no more than 2 integers.

        Excludes None values while parsing.
        """
        if isinstance(port_range, basestring):
            port_range = port_range.split(self.RANGE_SEP, 2)
        if not isinstance(port_range, (set, list, tuple)):
            port_range = [port_range]
        port_range = [int(port)
                      for port in port_range
                      if port and int(port)][:2]
        port_range.sort()
        # Fill out missing slots by None values
        port_range += [None] * (2 - len(port_range))
        port_from, port_to = port_range
        if not port_from or port_from < self.port_min or \
                port_from > self.port_max:
            raise ValueError("Invalid port range lower bound.")
        if not port_to:
            port_to = port_from
        return port_from, port_to

    def __repr__(self):
        """ Print all components of the range. """
        return '{}(port_from={}, port_to={}, base={}, offset={}, prefix={}, ' \
            'mask={})'.format(self.__class__.__name__, self.port_from,
                              self.port_to, self.base, self.offset,
                              self.prefix, self.mask)

    def __str__(self):
        """ Returns the most appropriate string representation. """
        if self.is_single_port:
            return str(self.port_from)
        try:
            return self.cidr_string
        except ValueError:
            return self.range_string

    @property
    def cidr_string(self):
        """ Returns a clean CIDR-like notation if possible. """
        if not self.is_cidr:
            raise ValueError(
                "Range can't be rendered using a CIDR-like notation.")
        return '{}{}{}'.format(self.base, self.CIDR_SEP, self.prefix)

    @property
    def range_string(self):
        """ Returns a clean range notation. """
        return '{}{}{}'.format(self.port_from, self.RANGE_SEP, self.port_to)

    @classmethod
    def _is_power_of_two(cls, value):
        """ Helper to check if a value is a power of 2. """
        return math.log(value, 2) % 1 == 0

    @classmethod
    def _nearest_power_of_two(cls, value):
        """ Returns nearsest power of 2. """
        return int(2 ** math.floor(math.log(value, 2)))

    @classmethod
    def _mask(cls, prefix):
        """ Compute the mask. """
        return cls.port_lenght - prefix

    @classmethod
    def _raw_upper_bound(cls, base, prefix):
        """ Compute a raw upper bound. """
        return base + (2 ** cls._mask(prefix)) - 1

    @classmethod
    def _cidr_to_range(cls, base, prefix):
        """ Transform a CIDR-like notation into a port range. """
        port_from = base
        port_to = cls._raw_upper_bound(base, prefix)
        return port_from, port_to

    @property
    def bounds(self):
        """ Returns lower and upper bounds of the port range. """
        return self.port_from, self.port_to

    @property
    def base(self):
        """ Alias to port_from, used as a starting point for CIDR notation. """
        return self.port_from

    @property
    def offset(self):
        """ Port base offset from its nearest power of two. """
        return self.base - self._nearest_power_of_two(self.base)

    @property
    def prefix(self):
        """ A power-of-two delta means a valid CIDR-like prefix. """
        # Check that range delta is a power of 2
        port_delta = self.port_to - self.port_from + 1
        if not self._is_power_of_two(port_delta):
            return None
        return self.port_lenght - int(math.log(port_delta, 2))

    @property
    def mask(self):
        """ Port range binary mask, based on CIDR-like prefix. """
        return self._mask(self.prefix) if self.prefix else None

    @property
    def cidr(self):
        """ Returns components of the CIDR-like notation. """
        return self.base, self.prefix

    @property
    def is_single_port(self):
        """ Is the range a single port ? """
        return True if self.port_from == self.port_to else False

    @property
    def is_cidr(self):
        """ Is the range can be expressed using a CIDR-like notation. """
        return True if self.prefix is not None else False


1			# -- coding: utf-8 --
2			#
3			# Copyright (c) 2014-2015 Scaleway and Contributors. All Rights Reserved.
4			# Kevin Deldycke <[email protected]>
5			# Gilles Dartiguelongue <[email protected]>
6			#
7			# Licensed under the BSD 2-Clause License (the "License"); you may not use this
8			# file except in compliance with the License. You may obtain a copy of the
9			# License at http://opensource.org/licenses/BSD-2-Clause
10
11			""" Port range utilities and helpers.
12			"""
13
14			from __future__ import (absolute_import, division, print_function,
15			unicode_literals)
16
17			import math
18
19			try:
20			basestring
21			except NameError: # pragma: no cover
22			basestring = (str, bytes) # pylint: disable=C0103
23
24			try:
25			from itertools import imap as iter_map
26			except ImportError: # pragma: no cover
27			iter_map = map
28
29
30			__version__ = '1.0.6'
31
32
33			class PortRange(object):
34			""" Port range with support of a CIDR-like (binary) notation.
35
36			In strict mode (disabled by default) we'll enforce the following rules:
37			* port base must be a power of two (offsets not allowed);
38			* port CIDR should not produce overflowing upper bound.
39
40			This mode can be disabled on object creation.
41			"""
42			# Separators constants
43			CIDR_SEP = '/'
44			RANGE_SEP = '-'
45
46			# Max port lenght, in bits
47			port_lenght = 16
48			# Max port range integer values
49			port_min = 1
50			port_max = (2 ** port_lenght) - 1
51
52			# Base values on which all other properties are computed.
53			port_from = None
54			port_to = None
55
56			def __init__(self, port_range, strict=False):
57			""" Set up class with a port_from and port_to integer. """
58			self.port_from, self.port_to = self.parse(port_range, strict=strict)
59
60			def parse(self, port_range, strict=False):
61			""" Parse and normalize port range string into a port range. """
62			if isinstance(port_range, basestring) and self.CIDR_SEP in port_range:
63			base, prefix = self.parse_cidr(port_range, strict)
64			port_from, port_to = self._cidr_to_range(base, prefix)
65			else:
66			port_from, port_to = self.parse_range(port_range)
67			if not port_from or not port_to:
68			raise ValueError("Invalid ports.")
69			# Check upper bound
70			if strict:
71			# Disallow overflowing upper bound
72			if port_to > self.port_max:
73			raise ValueError("Overflowing upper bound.")
74			else:
75			# Cap upper bound
76			port_to = port_to if port_to < self.port_max else self.port_max
77			return port_from, port_to
78
79			def parse_cidr(self, port_range, strict=False):
80			""" Split a string and extract port base and CIDR prefix.
81
82			Always returns a list of 2 integers. Defaults to None.
83			"""
84			# Separate base and prefix
85			elements = list(iter_map(int, port_range.split(self.CIDR_SEP, 2)))
86			elements += [None, None]
87			base, prefix = elements[:2]
88			# Normalize prefix value
89			if prefix is None:
90			prefix = self.port_lenght
91			# Validates base and prefix values
92			if not base or base < self.port_min or base > self.port_max:
93			raise ValueError("Invalid port base.")
94			if not prefix or prefix < 1 or prefix > self.port_lenght:
95			raise ValueError("Invalid CIDR-like prefix.")
96			# Enable rigorous rules
97			if strict:
98			# Disallow offsets
99			if prefix != self.port_lenght and not self._is_power_of_two(base):
100			raise ValueError("Port base is not a power of Two.")
101			return base, prefix
102
103			def parse_range(self, port_range):
104			""" Normalize port range to a sorted list of no more than 2 integers.
105
106			Excludes None values while parsing.
107			"""
108			if isinstance(port_range, basestring):
109			port_range = port_range.split(self.RANGE_SEP, 2)
110			if not isinstance(port_range, (set, list, tuple)):
111			port_range = [port_range]
112			port_range = [int(port)
113			for port in port_range
114			if port and int(port)][:2]
115			port_range.sort()
116			# Fill out missing slots by None values
117			port_range += [None] * (2 - len(port_range))
118			port_from, port_to = port_range
119			if not port_from or port_from < self.port_min or \
120			port_from > self.port_max:
121			raise ValueError("Invalid port range lower bound.")
122			if not port_to:
123			port_to = port_from
124			return port_from, port_to
125
126			def __repr__(self):
127			""" Print all components of the range. """
128			return '{}(port_from={}, port_to={}, base={}, offset={}, prefix={}, ' \
129			'mask={})'.format(self.__class__.__name__, self.port_from,
130			self.port_to, self.base, self.offset,
131			self.prefix, self.mask)
132
133			def __str__(self):
134			""" Returns the most appropriate string representation. """
135			if self.is_single_port:
136			return str(self.port_from)
137			try:
138			return self.cidr_string
139			except ValueError:
140			return self.range_string
141
142			@property
143			def cidr_string(self):
144			""" Returns a clean CIDR-like notation if possible. """
145			if not self.is_cidr:
146			raise ValueError(
147			"Range can't be rendered using a CIDR-like notation.")
148			return '{}{}{}'.format(self.base, self.CIDR_SEP, self.prefix)
149
150			@property
151			def range_string(self):
152			""" Returns a clean range notation. """
153			return '{}{}{}'.format(self.port_from, self.RANGE_SEP, self.port_to)
154
155			@classmethod
156			def _is_power_of_two(cls, value):
157			""" Helper to check if a value is a power of 2. """
158			return math.log(value, 2) % 1 == 0
159
160			@classmethod
161			def _nearest_power_of_two(cls, value):
162			""" Returns nearsest power of 2. """
163			return int(2 ** math.floor(math.log(value, 2)))
164
165			@classmethod
166			def _mask(cls, prefix):
167			""" Compute the mask. """
168			return cls.port_lenght - prefix
169
170			@classmethod
171			def _raw_upper_bound(cls, base, prefix):
172			""" Compute a raw upper bound. """
173			return base + (2 ** cls._mask(prefix)) - 1
174
175			@classmethod
176			def _cidr_to_range(cls, base, prefix):
177			""" Transform a CIDR-like notation into a port range. """
178			port_from = base
179			port_to = cls._raw_upper_bound(base, prefix)
180			return port_from, port_to
181
182			@property
183			def bounds(self):
184			""" Returns lower and upper bounds of the port range. """
185			return self.port_from, self.port_to
186
187			@property
188			def base(self):
189			""" Alias to port_from, used as a starting point for CIDR notation. """
190			return self.port_from
191
192			@property
193			def offset(self):
194			""" Port base offset from its nearest power of two. """
195			return self.base - self._nearest_power_of_two(self.base)
196
197			@property
198			def prefix(self):
199			""" A power-of-two delta means a valid CIDR-like prefix. """
200			# Check that range delta is a power of 2
201			port_delta = self.port_to - self.port_from + 1
202			if not self._is_power_of_two(port_delta):
203			return None
204			return self.port_lenght - int(math.log(port_delta, 2))
205
206			@property
207			def mask(self):
208			""" Port range binary mask, based on CIDR-like prefix. """
209			return self._mask(self.prefix) if self.prefix else None
210
211			@property
212			def cidr(self):
213			""" Returns components of the CIDR-like notation. """
214			return self.base, self.prefix
215
216			@property
217			def is_single_port(self):
218			""" Is the range a single port ? """
219			return True if self.port_from == self.port_to else False
220
221			@property
222			def is_cidr(self):
223			""" Is the range can be expressed using a CIDR-like notation. """
224			return True if self.prefix is not None else False
225

scaleway / port-range

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