Source Code for Module ndg.xacml.core.context.pdp

  1  """NDG XACML Policy Decision Point type definition 
  2   
  3  NERC DataGrid 
  4  """ 
  5  __author__ = "P J Kershaw" 
  6  __date__ = "25/02/10" 
  7  __copyright__ = "(C) 2010 Science and Technology Facilities Council" 
  8  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
  9  __license__ = "BSD - see LICENSE file in top-level directory" 
 10  __contact__ = "Philip.Kershaw@stfc.ac.uk" 
 11  __revision__ = "$Id: pdp.py 7955 2011-12-21 18:29:45Z rwilkinson $" 
 12  import logging 
 13  log = logging.getLogger(__name__) 
 14   
 15  from ndg.xacml.core.context.pdpinterface import PDPInterface 
 16  from ndg.xacml.core.policybase import PolicyBase 
 17  from ndg.xacml.finder.defaultfinder import getDefaultPolicyFinder 
 18   
 19   
 20 -class PDP(PDPInterface): 
 21      """A XACML Policy Decision Point implementation.  It supports the use of a  
 22      single policy but not policy sets 
 23       
 24      @ivar __policy: policy object for PDP to use to apply access control 
 25      decisions 
 26      @type policy: ndg.xacml.core.policy.Policy / None 
 27      """ 
 28      __slots__ = ('__policy',) 
 29       
 30 -    def __init__(self, policy=None): 
 31          """ 
 32          @param policy: policy object for PDP to use to apply access control 
 33          decisions, may be omitted. 
 34          @type policy: ndg.xacml.core.policy.Policy / None 
 35          """ 
 36          self.__policy = None 
 37          if policy is not None: 
 38              self.policy = policy 
 39           
 40      @classmethod 
 41 -    def fromPolicySource(cls, source, readerFactory, finder=None): 
 42          """Create a new PDP instance with a given policy 
 43          @param source: source for policy 
 44          @type source: type (dependent on the reader set, it could be for example 
 45          a file path string, file object, XML element instance) 
 46          @param readerFactory: reader factory returns the reader to use to read  
 47          this policy 
 48          @type readerFactory: ndg.xacml.parsers.AbstractReader derived type 
 49          @param finder: policy finder 
 50          @type finder: ndg.xacml.finder.PolicyFinderBase subclass 
 51          """            
 52          pdp = cls() 
 53          if not finder: 
 54              # Set a default policy finder. 
 55              finder = getDefaultPolicyFinder(source) 
 56          pdp.setPolicyFromSource(source, readerFactory, finder) 
 57          return pdp 
 58       
 59 -    def setPolicyFromSource(self, source, readerFactory, finder): 
 60          """initialise PDP with the given policy 
 61          @param source: source for policy 
 62          @type source: type (dependent on the reader set, it could be for example 
 63          a file path string, file object, XML element instance) 
 64          @param readerFactory: reader factory returns the reader to use to read  
 65          this policy 
 66          @type readerFactory: ndg.xacml.parsers.AbstractReader derived type 
 67          @param finder: policy finder 
 68          @type finder: ndg.xacml.finder.PolicyFinderBase subclass 
 69          """            
 70          self.policy = PolicyBase.fromSource(source, readerFactory, finder) 
 71           
 72      @property 
 73 -    def policy(self): 
 74          """Get policy 
 75          @return: policy object for PDP to use to apply access control decisions 
 76          @rtype: ndg.xacml.core.policy.Policy 
 77          """ 
 78          return self.__policy 
 79       
 80      @policy.setter 
 81 -    def policy(self, value): 
 82          '''Set policy 
 83          @param value: policy object for PDP to use to apply access control  
 84          decisions 
 85          @type value: ndg.xacml.core.policy.Policy 
 86          ''' 
 87          if not isinstance(value, PolicyBase): 
 88              raise TypeError('Expecting %r derived type for "policy" input; got ' 
 89                              '%r instead' % (PolicyBase, type(value))) 
 90          self.__policy = value 
 91                                           
 92 -    def evaluate(self, request): 
 93          """Make an access control decision for the given request based on the 
 94          single policy provided 
 95           
 96          @param request: XACML request context 
 97          @type request: ndg.xacml.core.context.request.Request 
 98          @return: XACML response instance 
 99          @rtype: ndg.xacml.core.context.response.Response 
100          """ 
101          response = self.policy.evaluateResponse(request) 
102           
103          return response 
104