110 lines
3.9 KiB
Python
110 lines
3.9 KiB
Python
#
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# Licensed under the Apache License, Version 2.0 (the "License"); you may
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# not use this file except in compliance with the License. You may obtain
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# a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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# License for the specific language governing permissions and limitations
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# under the License.
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import collections
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import random as random_module
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import string
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import six
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# NOTE(pas-ha) Heat officially supports only POSIX::Linux platform
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# where os.urandom() and random.SystemRandom() are available
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random = random_module.SystemRandom()
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CHARACTER_CLASSES = (
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LETTERS_DIGITS, LETTERS, LOWERCASE, UPPERCASE,
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DIGITS, HEXDIGITS, OCTDIGITS,
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) = (
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'lettersdigits', 'letters', 'lowercase', 'uppercase',
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'digits', 'hexdigits', 'octdigits',
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)
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_char_class_members = {
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LETTERS_DIGITS: string.ascii_letters + string.digits,
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LETTERS: string.ascii_letters,
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LOWERCASE: string.ascii_lowercase,
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UPPERCASE: string.ascii_uppercase,
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DIGITS: string.digits,
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HEXDIGITS: string.digits + 'ABCDEF',
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OCTDIGITS: string.octdigits,
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}
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CharClass = collections.namedtuple('CharClass',
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('allowed_chars', 'min_count'))
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def named_char_class(char_class, min_count=0):
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"""Return a predefined character class.
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The result of this function can be passed to :func:`generate_password` as
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one of the character classes to use in generating a password.
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:param char_class: Any of the character classes named in
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:const:`CHARACTER_CLASSES`
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:param min_count: The minimum number of members of this class to appear in
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a generated password
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"""
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assert char_class in CHARACTER_CLASSES
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return CharClass(frozenset(_char_class_members[char_class]), min_count)
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def special_char_class(allowed_chars, min_count=0):
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"""Return a character class containing custom characters.
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The result of this function can be passed to :func:`generate_password` as
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one of the character classes to use in generating a password.
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:param allowed_chars: Iterable of the characters in the character class
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:param min_count: The minimum number of members of this class to appear in
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a generated password
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"""
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return CharClass(frozenset(allowed_chars), min_count)
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def generate_password(length, char_classes):
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"""Generate a random password.
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The password will be of the specified length, and comprised of characters
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from the specified character classes, which can be generated using the
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:func:`named_char_class` and :func:`special_char_class` functions. Where
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a minimum count is specified in the character class, at least that number
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of characters in the resulting password are guaranteed to be from that
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character class.
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:param length: The length of the password to generate, in characters
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:param char_classes: Iterable over classes of characters from which to
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generate a password
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"""
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char_buffer = six.StringIO()
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all_allowed_chars = set()
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# Add the minimum number of chars from each char class
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for char_class in char_classes:
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all_allowed_chars |= char_class.allowed_chars
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allowed_chars = tuple(char_class.allowed_chars)
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for i in six.moves.xrange(char_class.min_count):
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char_buffer.write(random.choice(allowed_chars))
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# Fill up rest with random chars from provided classes
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combined_chars = tuple(all_allowed_chars)
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for i in six.moves.xrange(max(0, length - char_buffer.tell())):
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char_buffer.write(random.choice(combined_chars))
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# Shuffle string
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selected_chars = char_buffer.getvalue()
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char_buffer.close()
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return ''.join(random.sample(selected_chars, length))
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