1  import functools
       2  import hashlib
       3  import unittest
       4  
       5  try:
       6      import _hashlib
       7  except ImportError:
       8      _hashlib = None
       9  
      10  
      11  def requires_hashdigest(digestname, openssl=None, usedforsecurity=True):
      12      """Decorator raising SkipTest if a hashing algorithm is not available
      13  
      14      The hashing algorithm could be missing or blocked by a strict crypto
      15      policy.
      16  
      17      If 'openssl' is True, then the decorator checks that OpenSSL provides
      18      the algorithm. Otherwise the check falls back to built-in
      19      implementations. The usedforsecurity flag is passed to the constructor.
      20  
      21      ValueError: [digital envelope routines: EVP_DigestInit_ex] disabled for FIPS
      22      ValueError: unsupported hash type md4
      23      """
      24      def decorator(func_or_class):
      25          if isinstance(func_or_class, type):
      26              setUpClass = func_or_class.__dict__.get('setUpClass')
      27              if setUpClass is None:
      28                  def setUpClass(cls):
      29                      super(func_or_class, cls).setUpClass()
      30                  setUpClass.__qualname__ = func_or_class.__qualname__ + '.setUpClass'
      31                  setUpClass.__module__ = func_or_class.__module__
      32              else:
      33                  setUpClass = setUpClass.__func__
      34              setUpClass = classmethod(decorator(setUpClass))
      35              func_or_class.setUpClass = setUpClass
      36              return func_or_class
      37  
      38          @functools.wraps(func_or_class)
      39          def wrapper(*args, **kwargs):
      40              try:
      41                  if openssl and _hashlib is not None:
      42                      _hashlib.new(digestname, usedforsecurity=usedforsecurity)
      43                  else:
      44                      hashlib.new(digestname, usedforsecurity=usedforsecurity)
      45              except ValueError:
      46                  raise unittest.SkipTest(
      47                      f"hash digest '{digestname}' is not available."
      48                  )
      49              return func_or_class(*args, **kwargs)
      50          return wrapper
      51      return decorator