Package dns :: Module hash |
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# Source Code for Module dns.hash

     1  # Copyright (C) 2010 Nominum, Inc.
     2  #
     3  # Permission to use, copy, modify, and distribute this software and its
     4  # documentation for any purpose with or without fee is hereby granted,
     5  # provided that the above copyright notice and this permission notice
     6  # appear in all copies.
     7  #
     8  # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
     9  # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
    10  # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
    11  # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
    12  # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
    13  # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
    14  # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
    15
    16  """Hashing backwards compatibility wrapper"""
    17
    18  import sys
    19
    20  _hashes = None
    21
    22 -def _need_later_python(alg):
    23      def func(*args, **kwargs):
    24          raise NotImplementedError("TSIG algorithm " + alg +
    25                                    " requires Python 2.5.2 or later")
    26      return func
    27
    28 -def _setup():
    29      global _hashes
    30      _hashes = {}
    31      try:
    32          import hashlib
    33          _hashes['MD5'] = hashlib.md5
    34          _hashes['SHA1'] = hashlib.sha1
    35          _hashes['SHA224'] = hashlib.sha224
    36          _hashes['SHA256'] = hashlib.sha256
    37          if sys.hexversion >= 0x02050200:
    38              _hashes['SHA384'] = hashlib.sha384
    39              _hashes['SHA512'] = hashlib.sha512
    40          else:
    41              _hashes['SHA384'] = _need_later_python('SHA384')
    42              _hashes['SHA512'] = _need_later_python('SHA512')
    43
    44          if sys.hexversion < 0x02050000:
    45              # hashlib doesn't conform to PEP 247: API for
    46              # Cryptographic Hash Functions, which hmac before python
    47              # 2.5 requires, so add the necessary items.
    48              class HashlibWrapper:
    49                  def __init__(self, basehash):
    50                      self.basehash = basehash
    51                      self.digest_size = self.basehash().digest_size
    52
    53                  def new(self, *args, **kwargs):
    54                      return self.basehash(*args, **kwargs)
    55
    56              for name in _hashes:
    57                  _hashes[name] = HashlibWrapper(_hashes[name])
    58
    59      except ImportError:
    60          import md5, sha
    61          _hashes['MD5'] =  md5
    62          _hashes['SHA1'] = sha
    63
    64 -def get(algorithm):
    65      if _hashes is None:
    66          _setup()
    67      return _hashes[algorithm.upper()]
    68