/// <summary>
/// The evaluation implementation in the pseudo-code described in the specification.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <param name="rules">The policies that must be evaluated.</param>
/// <returns>The final decission for the combination of the rule evaluation.</returns>
public Decision Evaluate( EvaluationContext context, RuleCollection rules )
{
var decision = Decision.Indeterminate;
context.Trace( "Evaluating rules..." );
context.AddIndent();
try
{
foreach( Rule rule in rules )
{
decision = rule.Evaluate( context );
context.TraceContextValues();
if( decision == Decision.Deny )
{
decision = Decision.Deny;
return decision;
}
if( decision == Decision.Permit )
{
decision = Decision.Permit;
return decision;
}
if( decision == Decision.NotApplicable )
{
continue;
}
if( decision == Decision.Indeterminate )
{
decision = Decision.Indeterminate;
return decision;
}
}
return Decision.NotApplicable;
}
finally
{
context.Trace( "Rule combination algorithm: {0}", decision.ToString() );
context.RemoveIndent();
}
}
/// <summary>
/// Evaluate the context document using a specified policy
/// </summary>
/// <param name="policyDocument">The policy instance</param>
/// <param name="contextDocument">The context document instance</param>
/// <returns>The response document</returns>
public ctx.ResponseElement Evaluate(pol.PolicyDocument policyDocument, ctx.ContextDocument contextDocument)
{
if (policyDocument == null) throw new ArgumentNullException("policyDocument");
if (contextDocument == null) throw new ArgumentNullException("contextDocument");
var context = new EvaluationContext(this, policyDocument, contextDocument);
context.Trace("Start evaluation");
context.AddIndent();
// Check if both documents are valid
if (!policyDocument.IsValidDocument || !contextDocument.IsValidDocument)
{
// If a validation error was found a response is created with the syntax error message
var response =
new ctx.ResponseElement(
new[] {
new ctx.ResultElement(
null,
Decision.Indeterminate,
new ctx.StatusElement(
new ctx.StatusCodeElement(Consts.ContextSchema.StatusCodes.SyntaxError, null, policyDocument.Version ),
null,
null, policyDocument.Version ),
null, policyDocument.Version ) },
policyDocument.Version);
return response;
}
// Create a new response
contextDocument.Response = new ctx.ResponseElement((ctx.ResultElement[])null, policyDocument.Version);
try
{
// Create the evaluable policy intance
IMatchEvaluable policy = null;
if (policyDocument.PolicySet != null)
{
policy = new PolicySet(this, (pol.PolicySetElement)policyDocument.PolicySet);
}
else if (policyDocument.Policy != null)
{
policy = new Policy((pol.PolicyElement)policyDocument.Policy);
}
// Evaluate the policy or policy set
if (policy != null)
{
// Creates the evaluable policy set
if (policy.AllResources.Count == 0)
{
policy.AllResources.Add("");
}
string requestedResourceString = String.Empty;
Uri requestedResource = null;
foreach (ctx.ResourceElement resource in contextDocument.Request.Resources)
{
// Keep the requested resource
if (resource.IsHierarchical)
{
foreach (ctx.AttributeElement attribute in resource.Attributes)
{
if (attribute.AttributeId == Consts.ContextSchema.ResourceElement.ResourceId)
{
if (context.PolicyDocument.Version == XacmlVersion.Version10 ||
context.PolicyDocument.Version == XacmlVersion.Version11)
{
requestedResourceString = attribute.AttributeValues[0].Contents;
}
else
{
if (attribute.AttributeValues.Count > 1)
{
throw new NotSupportedException("resources contains a bag of values");
}
requestedResourceString = attribute.AttributeValues[0].Contents;
}
}
}
if (!string.IsNullOrEmpty(requestedResourceString))
{
requestedResource = new Uri(requestedResourceString);
}
}
// Iterate through the policy resources evaluating each resource in the context document request
foreach (string resourceName in policy.AllResources)
{
bool mustEvaluate = false;
if (resource.IsHierarchical)
{
//Validate if the resource is hierarchically desdendant or children
//of the requested resource
Uri policyResource = new Uri(resourceName);
Debug.Assert(requestedResource != null, "requestedResource != null");
if (!(mustEvaluate = requestedResource.Equals(policyResource)))
{
// Perform the hierarchical evaluation
if (resource.ResourceScopeValue == ctx.ResourceScope.Children)
{
mustEvaluate = typ.AnyUri.IsChildrenOf(requestedResource, policyResource);
}
else if (resource.ResourceScopeValue == ctx.ResourceScope.Descendants)
{
mustEvaluate = typ.AnyUri.IsDescendantOf(requestedResource, policyResource);
}
}
if (mustEvaluate)
{
foreach (ctx.AttributeElementReadWrite attribute in context.CurrentResource.Attributes)
{
if (attribute.AttributeId == Consts.ContextSchema.ResourceElement.ResourceId)
{
attribute.AttributeValues[0].Contents = resourceName;
break;
}
}
}
}
else
{
context.CurrentResource = resource;
mustEvaluate = true;
}
if (mustEvaluate)
{
// Evaluates the policy set
Decision decision = policy.Evaluate(context);
// Create a status code using the policy execution state
ctx.StatusCodeElement scode;
if (context.IsMissingAttribute)
{
scode = new ctx.StatusCodeElement(
Consts.ContextSchema.StatusCodes.MissingAttribute, null, policyDocument.Version);
}
else if (context.ProcessingError)
{
scode = new ctx.StatusCodeElement(
Consts.ContextSchema.StatusCodes.ProcessingError, null, policyDocument.Version);
}
else
{
scode = new ctx.StatusCodeElement(
Consts.ContextSchema.StatusCodes.Ok, null, policyDocument.Version);
}
//Stop the iteration if there is not a hierarchical request
if (!resource.IsHierarchical)
{
// Ussually when a single resource is requested the ResourceId is not specified in the result
var oblig = policy as IObligationsContainer;
contextDocument.Response.Results.Add(
new ctx.ResultElement("", decision,
new ctx.StatusElement(scode, "", "", policyDocument.Version), oblig.Obligations, policyDocument.Version));
break;
}
else
{
// Adding a resource for each requested resource, using the resourceName as the resourceId of the result
var oblig = policy as IObligationsContainer;
contextDocument.Response.Results.Add(
new ctx.ResultElement(resourceName, decision,
new ctx.StatusElement(scode, "", "", policyDocument.Version), oblig.Obligations, policyDocument.Version));
}
} // if( mustEvaluate )
} // foreach( string resourceName in policy.AllResources )
}
} //if( policy != null )
}
catch (EvaluationException e)
{
// If a validation error was found a response is created with the syntax error message
contextDocument.Response =
new ctx.ResponseElement(
new ctx.ResultElement[] {
new ctx.ResultElement(
null,
Decision.Indeterminate,
new ctx.StatusElement(
new ctx.StatusCodeElement(Consts.ContextSchema.StatusCodes.ProcessingError, null, policyDocument.Version ),
e.Message,
e.StackTrace, policyDocument.Version ),
null, policyDocument.Version ) },
policyDocument.Version);
}
return contextDocument.Response;
}
/// <summary>
/// Evaluates the rule contents.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>A decission for this evalauation.</returns>
public Decision Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
context.Trace("Evaluating rule: {0}", _rule.Description);
context.AddIndent();
context.CurrentRule = this;
try
{
// Validate the Target element
TargetEvaluationValue targetEvaluation = Match(context);
// If the target matches the conditions ar evaluated
EvaluationValue conditionEvaluation = EvaluationValue.True;
if (_rule.HasCondition)
{
// Evaluate the condition
conditionEvaluation = _condition.Evaluate(context);
}
else
{
context.Trace("Rule does not have a condition");
}
// Decite the final rule evaluation value
if (targetEvaluation == TargetEvaluationValue.Indeterminate || conditionEvaluation.IsIndeterminate)
{
_evaluationValue = Decision.Indeterminate;
}
else if (targetEvaluation == TargetEvaluationValue.Match && conditionEvaluation.BoolValue)
{
_evaluationValue = ((_rule.Effect == Effect.Permit) ? Decision.Permit : Decision.Deny);
}
else if ((targetEvaluation == TargetEvaluationValue.NoMatch) ||
(targetEvaluation == TargetEvaluationValue.Match && !conditionEvaluation.BoolValue))
{
_evaluationValue = Decision.NotApplicable;
}
// Return the value
context.Trace("Rule: {0}", _evaluationValue);
return _evaluationValue;
}
finally
{
context.RemoveIndent();
context.CurrentRule = null;
}
}
/// <summary>
/// Verifies if the rule target matches
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The result of the Match process.</returns>
public TargetEvaluationValue Match(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
TargetEvaluationValue targetEvaluationValue = TargetEvaluationValue.Indeterminate;
context.Trace("Evaluating rule target");
context.AddIndent();
try
{
// Evaluate the policy target
targetEvaluationValue = TargetEvaluationValue.Match;
if (_target != null)
{
targetEvaluationValue = _target.Evaluate(context);
context.TraceContextValues();
}
return targetEvaluationValue;
}
finally
{
context.RemoveIndent();
context.Trace("Target: {0}", targetEvaluationValue);
}
}
/// <summary>
/// The evaluation implementation in the pseudo-code described in the specification.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <param name="rules">The policies that must be evaluated.</param>
/// <returns>The final decission for the combination of the rule evaluation.</returns>
public Decision Evaluate(EvaluationContext context, RuleCollection rules)
{
if (context == null) throw new ArgumentNullException("context");
if (rules == null) throw new ArgumentNullException("rules");
var decision = Decision.Indeterminate;
bool atLeastOneError = false;
bool potentialPermit = false;
bool atLeastOneDeny = false;
context.Trace("Evaluating rules...");
context.AddIndent();
try
{
foreach (Rule rule in rules)
{
decision = rule.Evaluate(context);
context.TraceContextValues();
if (decision == Decision.Deny)
{
atLeastOneDeny = true;
continue;
}
if (decision == Decision.Permit)
{
decision = Decision.Permit;
return decision;
}
if (decision == Decision.NotApplicable)
{
continue;
}
if (decision == Decision.Indeterminate)
{
atLeastOneError = true;
if (rule.RuleDefinition.Effect == Effect.Permit)
{
potentialPermit = true;
}
continue;
}
}
if (potentialPermit)
{
decision = Decision.Indeterminate;
return decision;
}
if (atLeastOneDeny)
{
decision = Decision.Deny;
return decision;
}
if (atLeastOneError)
{
decision = Decision.Indeterminate;
return decision;
}
decision = Decision.NotApplicable;
return decision;
}
finally
{
context.Trace("Rule combination algorithm: {0}", decision.ToString());
context.RemoveIndent();
}
}
/// <summary>
/// This method overrides the ApplyBase method in order to provide extra validations
/// required in the condition evaluation, for example the final return value should be a
/// boolean value.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The EvaluationValue with the results of the condition evaluation.</returns>
public override EvaluationValue Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
EvaluationValue evaluationValue = null;
context.Trace("Evaluating condition...");
context.AddIndent();
try
{
// Get the function instance
IFunction function = EvaluationEngine.GetFunction(ApplyDefinition.FunctionId);
if (function == null)
{
context.Trace("ERR: function not found {0}", ApplyDefinition.FunctionId);
context.ProcessingError = true;
return EvaluationValue.Indeterminate;
}
// Validates the function return value
if (function.Returns == null)
{
context.Trace("The function '{0}' does not defines it's return value", ApplyDefinition.FunctionId);
evaluationValue = EvaluationValue.Indeterminate;
context.ProcessingError = true;
}
else if (function.Returns != DataTypeDescriptor.Boolean)
{
context.Trace("Function does not return Boolean a value");
evaluationValue = EvaluationValue.Indeterminate;
context.ProcessingError = true;
}
else
{
// Call the ApplyBase method to perform the evaluation.
evaluationValue = base.Evaluate(context);
}
// Validate the results of the evaluation
if (evaluationValue.IsIndeterminate)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return evaluationValue;
}
if (!(evaluationValue.Value is bool))
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return EvaluationValue.Indeterminate;
}
if (evaluationValue.BoolValue)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return EvaluationValue.True;
}
else
{
// If the evaluation was false, validate if there was a missin attribute during
// evaluation and return an Indeterminate, otherwise return the False value.
if (context.IsMissingAttribute)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return EvaluationValue.Indeterminate;
}
else
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return EvaluationValue.False;
}
}
}
finally
{
context.TraceContextValues();
context.RemoveIndent();
context.Trace("Condition: {0}", evaluationValue == null ? string.Empty : evaluationValue.ToString());
}
}
/// <summary>
/// THe argument processing method resolves all the attribute designators, attribute
/// selectors. If there is an internal Apply it will be evaulated within this method.
/// </summary>
/// <remarks>All the processed arguments are converted into an IFunctionParameter instance
/// because this is the only value that can be used to call a function.</remarks>
/// <param name="context">The evaluation context instance.</param>
/// <param name="arguments">The arguments to process.</param>
/// <returns>A list of arguments ready to be used by a function.</returns>
private FunctionParameterCollection ProcessArguments(EvaluationContext context, ExpressionCollection arguments)
{
context.Trace("Processing arguments");
context.AddIndent();
// Create a list to return the processed values.
var processedArguments = new FunctionParameterCollection();
// Iterate through the arguments, the IExpressionType is a mark interface
foreach (IExpression arg in arguments)
{
var apply = arg as ApplyElement;
if (apply != null)
{
context.Trace("Nested apply");
// There is a nested apply un this policy a new Apply will be created and also
// evaluated. It's return value will be used as the processed argument.
var childApply = new Apply(apply);
// Evaluate the Apply
EvaluationValue retVal = childApply.Evaluate(context);
context.TraceContextValues();
// If the results were Indeterminate the Indeterminate value will be placed in
// the processed arguments, later another method will validate the parameters
// and cancel the evaluation propperly.
if (!retVal.IsIndeterminate)
{
if (!context.IsMissingAttribute)
{
processedArguments.Add(retVal);
}
}
else
{
processedArguments.Add(retVal);
}
}
else
{
var write = arg as FunctionElementReadWrite;
if (write != null)
{
// Search for the function and place it in the processed arguments.
var functionId = new FunctionElement(write.FunctionId, write.SchemaVersion);
context.Trace("Function {0}", functionId.FunctionId);
IFunction function = EvaluationEngine.GetFunction(functionId.FunctionId);
if (function == null)
{
context.Trace("ERR: function not found {0}", _applyBase.FunctionId);
context.ProcessingError = true;
processedArguments.Add(EvaluationValue.Indeterminate);
}
else
{
processedArguments.Add(function);
}
}
else if (arg is VariableReferenceElement)
{
var variableRef = arg as VariableReferenceElement;
var variableDef = context.CurrentPolicy.VariableDefinition[variableRef.VariableId] as VariableDefinition;
context.TraceContextValues();
Debug.Assert(variableDef != null, "variableDef != null");
processedArguments.Add(!variableDef.IsEvaluated ? variableDef.Evaluate(context) : variableDef.Value);
}
else
{
var readWrite = arg as AttributeValueElementReadWrite;
if (readWrite != null)
{
// The AttributeValue does not need to be processed
context.Trace("Attribute value {0}", arg.ToString());
processedArguments.Add(new AttributeValueElement(readWrite.DataType, readWrite.Contents, readWrite.SchemaVersion));
}
else
{
var des = arg as AttributeDesignatorBase;
if (des != null)
{
// Resolve the AttributeDesignator using the EvaluationEngine public methods.
context.Trace("Processing attribute designator: {0}", arg.ToString());
var attrDes = des;
BagValue bag = EvaluationEngine.Resolve(context, attrDes);
// If the attribute was not resolved by the EvaluationEngine search the
// attribute in the context document, also using the EvaluationEngine public
// methods.
if (bag.BagSize == 0)
{
if (arg is SubjectAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding subject attribute designator: {0}", attrib.ToString());
bag.Add(attrib);
break;
}
}
else if (arg is ResourceAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding resource attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
else if (arg is ActionAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding action attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
else if (arg is EnvironmentAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding environment attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
}
// If the argument was not found and the attribute must be present this is
// a MissingAttribute situation so set the flag. Otherwise add the attribute
// to the processed arguments.
if (bag.BagSize == 0 && attrDes.MustBePresent)
{
context.Trace("Attribute is missing");
context.IsMissingAttribute = true;
context.AddMissingAttribute(attrDes);
}
else
{
processedArguments.Add(bag);
}
}
else
{
var @base = arg as AttributeSelectorElement;
if (@base != null)
{
// Resolve the XPath query using the EvaluationEngine public methods.
context.Trace("Attribute selector");
try
{
BagValue bag = EvaluationEngine.Resolve(context, @base);
if (bag.Elements.Count == 0 && @base.MustBePresent)
{
context.Trace("Attribute is missing");
context.IsMissingAttribute = true;
context.AddMissingAttribute(@base);
}
else
{
processedArguments.Add(bag);
}
}
catch (EvaluationException e)
{
context.Trace("ERR: {0}", e.Message);
processedArguments.Add(EvaluationValue.Indeterminate);
context.ProcessingError = true;
}
}
}
}
}
}
}
context.RemoveIndent();
return processedArguments;
}
/// <summary>
/// Process the match result.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <param name="targetEvaluationValue">The match evaluation result.</param>
private void ProcessTargetEvaluationValue(EvaluationContext context, TargetEvaluationValue targetEvaluationValue)
{
if (targetEvaluationValue == TargetEvaluationValue.Match)
{
try
{
context.Trace("Evaluating policies...");
context.AddIndent();
context.Trace("Policy combination algorithm: {0}", _policySet.PolicyCombiningAlgorithm);
// Evaluate all policies and apply rule combination
IPolicyCombiningAlgorithm pca = EvaluationEngine.CreatePolicyCombiningAlgorithm(_policySet.PolicyCombiningAlgorithm);
if (pca == null)
{
throw new EvaluationException("the policy combining algorithm does not exists."); //TODO: resources
}
_evaluationValue = pca.Evaluate(context, _policies);
// Update the flags for general evaluation status.
context.TraceContextValues();
context.Trace("Policy combination algorithm: {0}", _evaluationValue.ToString());
}
finally
{
context.RemoveIndent();
}
}
else if (targetEvaluationValue == TargetEvaluationValue.NoMatch)
{
_evaluationValue = Decision.NotApplicable;
}
else if (targetEvaluationValue == TargetEvaluationValue.Indeterminate)
{
_evaluationValue = Decision.Indeterminate;
}
}
/// <summary>
/// Evaluates the policy.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The decission result for this policy.</returns>
public Decision Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
context.Trace("Evaluating policy: {0}", _policy.Description);
context.AddIndent();
context.CurrentPolicy = this;
try
{
// Evaluate the variables
if (this._policy.SchemaVersion == XacmlVersion.Version20)
{
if (_variables == null)
{
context.Trace("Evaluating variables...");
_variables = new Hashtable();
foreach (pol.VariableDefinitionElement variableDef in _policy.VariableDefinitions.Values)
{
var variable = new VariableDefinition(variableDef);
_variables.Add(variableDef.Id, variable);
}
}
}
// Matches the target.
TargetEvaluationValue targetEvaluationValue = Match(context);
// If the target matches.
if (targetEvaluationValue == TargetEvaluationValue.Match)
{
context.Trace("Rule combination algorithm: {0}", _policy.RuleCombiningAlgorithm);
// Evaluate all rules and apply rule combination
IRuleCombiningAlgorithm rca = EvaluationEngine.CreateRuleCombiningAlgorithm(_policy.RuleCombiningAlgorithm);
_evaluationValue = rca.Evaluate(context, _rules);
}
else if (targetEvaluationValue == TargetEvaluationValue.NoMatch)
{
_evaluationValue = Decision.NotApplicable;
}
else if (targetEvaluationValue == TargetEvaluationValue.Indeterminate)
{
_evaluationValue = Decision.Indeterminate;
}
context.Trace("Policy: {0}", _evaluationValue);
// Copy all the obligations.
_obligations = new pol.ObligationCollection();
if (_evaluationValue != Decision.Indeterminate &&
_evaluationValue != Decision.NotApplicable &&
_policy.Obligations != null && _policy.Obligations.Count != 0)
{
foreach (pol.ObligationElement obl in _policy.Obligations)
{
if ((obl.FulfillOn == pol.Effect.Deny && _evaluationValue == Decision.Deny) ||
(obl.FulfillOn == pol.Effect.Permit && _evaluationValue == Decision.Permit))
{
context.Trace("Adding obligation: {0} ", obl.ObligationId);
_obligations.Add(obl);
}
}
}
return _evaluationValue;
}
finally
{
context.RemoveIndent();
context.CurrentPolicy = null;
}
}
/// <summary>
/// Evaluates the policy set.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The decission result for this policy set.</returns>
public Decision Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
context.Trace("Evaluating policySet: {0}", _policySet.Description);
context.CurrentPolicySet = this;
try
{
context.Trace("Evaluating Target...");
context.AddIndent();
// Evaluate the policy target
TargetEvaluationValue targetEvaluationValue = Match(context);
context.RemoveIndent();
context.Trace("Target: {0}", targetEvaluationValue);
ProcessTargetEvaluationValue(context, targetEvaluationValue);
context.Trace("PolicySet: {0}", _evaluationValue);
// If the policy evaluated to Deny or Permit add the obligations depending on its fulfill value.
ProcessObligations(context);
return _evaluationValue;
}
finally
{
context.CurrentPolicySet = null;
}
}
/// <summary>
/// Matches this target instance using the context document.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The results of the evaluation of this target.</returns>
public TargetEvaluationValue Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
// Set the default value.
_evaluationValue = TargetEvaluationValue.NoMatch;
// Resource
context.Trace("Evaluating Resource...");
context.AddIndent();
TargetEvaluationValue resourceEval = _resources.Evaluate(context, context.CurrentResource);
context.TraceContextValues();
context.Trace("Target item result: {0}", resourceEval);
context.RemoveIndent();
// Action
context.Trace("Evaluating Action...");
context.AddIndent();
TargetEvaluationValue actionEval = _actions.Evaluate(context, context.ContextDocument.Request.Action);
context.TraceContextValues();
context.Trace("Target item result: {0}", actionEval);
context.RemoveIndent();
context.Trace("Evaluating Subjects...");
context.AddIndent();
if (actionEval == TargetEvaluationValue.Match && resourceEval == TargetEvaluationValue.Match)
{
// Subjects
foreach (ctx.SubjectElement ctxSubject in context.ContextDocument.Request.Subjects)
{
context.Trace("Evaluating Subject: {0}", ctxSubject.SubjectCategory);
// Subject
TargetEvaluationValue subjectEval = _subjects.Evaluate(context, ctxSubject);
context.TraceContextValues();
if (subjectEval == TargetEvaluationValue.Indeterminate)
{
_evaluationValue = TargetEvaluationValue.Indeterminate;
}
else if (subjectEval == TargetEvaluationValue.Match)
{
_evaluationValue = TargetEvaluationValue.Match;
context.RemoveIndent();
context.Trace("Target item result: {0}", _evaluationValue);
return _evaluationValue;
}
}
context.RemoveIndent();
context.Trace("Target item result: {0}", _evaluationValue);
return _evaluationValue;
}
else
{
context.Trace("Actions or Resources does not Match so Subjects will not be evaluated");
if (resourceEval == TargetEvaluationValue.Indeterminate || actionEval == TargetEvaluationValue.Indeterminate)
{
context.RemoveIndent();
return TargetEvaluationValue.Indeterminate;
}
else
{
context.RemoveIndent();
return TargetEvaluationValue.NoMatch;
}
}
}
/// <summary>
/// This method overrides the ApplyBase method in order to provide extra validations
/// required in the condition evaluation, for example the final return value should be a
/// boolean value.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The EvaluationValue with the results of the condition evaluation.</returns>
public override EvaluationValue Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
context.Trace("Evaluating condition");
context.AddIndent();
try
{
// Iterate through the arguments, the IExpressionType is a mark interface
foreach (IExpression arg in ApplyDefinition.Arguments)
{
if (arg is ApplyElement)
{
context.Trace("Apply within condition.");
// There is a nested apply un this policy a new Apply will be created and also
// evaluated. It's return value will be used as the processed argument.
var childApply = new Apply((ApplyElement)arg);
// Evaluate the Apply
EvaluationValue retVal = childApply.Evaluate(context);
return retVal;
}
else if (arg is FunctionElementReadWrite)
{
throw new NotImplementedException("FunctionElement"); //TODO:
}
else if (arg is VariableReferenceElement)
{
var variableRef = arg as VariableReferenceElement;
var variableDef = context.CurrentPolicy.VariableDefinition[variableRef.VariableId] as VariableDefinition;
Debug.Assert(variableDef != null, "variableDef != null");
if (!variableDef.IsEvaluated)
{
return variableDef.Evaluate(context);
}
else
{
return variableDef.Value;
}
}
else if (arg is AttributeValueElementReadWrite)
{
// The AttributeValue does not need to be processed
context.Trace("Attribute value {0}", arg.ToString());
var attributeValue = new AttributeValueElement(((AttributeValueElementReadWrite)arg).DataType, ((AttributeValueElementReadWrite)arg).Contents, ((AttributeValueElementReadWrite)arg).SchemaVersion);
return new EvaluationValue(
attributeValue.GetTypedValue(attributeValue.GetType(context), 0),
attributeValue.GetType(context));
}
else if (arg is AttributeDesignatorBase)
{
// Returning an empty bag, since the condition is not supposed to work with a bag
context.Trace("Processing attribute designator: {0}", arg.ToString());
var attrDes = (AttributeDesignatorBase)arg;
var bag = new BagValue(EvaluationEngine.GetDataType(attrDes.DataType));
return new EvaluationValue(bag, bag.GetType(context));
}
else if (arg is AttributeSelectorElement)
{
// Returning an empty bag, since the condition is not supposed to work with a bag
context.Trace("Attribute selector");
var attrSel = (AttributeSelectorElement)arg;
var bag = new BagValue(EvaluationEngine.GetDataType(attrSel.DataType));
return new EvaluationValue(bag, bag.GetType(context));
}
}
throw new NotSupportedException("internal error");
}
finally
{
context.TraceContextValues();
context.RemoveIndent();
}
}
/// <summary>
/// This method overrides the ApplyBase method in order to provide extra validations
/// required in the condition evaluation, for example the final return value should be a
/// boolean value.
/// </summary>
/// <param name="context">The evaluation context instance.</param>
/// <returns>The EvaluationValue with the results of the condition evaluation.</returns>
public override EvaluationValue Evaluate(EvaluationContext context)
{
if (context == null)
{
throw new ArgumentNullException("context");
}
EvaluationValue evaluationValue = null;
context.Trace("Evaluating condition...");
context.AddIndent();
try
{
// Get the function instance
IFunction function = EvaluationEngine.GetFunction(ApplyDefinition.FunctionId);
if (function == null)
{
context.Trace("ERR: function not found {0}", ApplyDefinition.FunctionId);
context.ProcessingError = true;
return(EvaluationValue.Indeterminate);
}
// Validates the function return value
if (function.Returns == null)
{
context.Trace("The function '{0}' does not defines it's return value", ApplyDefinition.FunctionId);
evaluationValue = EvaluationValue.Indeterminate;
context.ProcessingError = true;
}
else if (function.Returns != DataTypeDescriptor.Boolean)
{
context.Trace("Function does not return Boolean a value");
evaluationValue = EvaluationValue.Indeterminate;
context.ProcessingError = true;
}
else
{
// Call the ApplyBase method to perform the evaluation.
evaluationValue = base.Evaluate(context);
}
// Validate the results of the evaluation
if (evaluationValue.IsIndeterminate)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return(evaluationValue);
}
if (!(evaluationValue.Value is bool))
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return(EvaluationValue.Indeterminate);
}
if (evaluationValue.BoolValue)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return(EvaluationValue.True);
}
else
{
// If the evaluation was false, validate if there was a missin attribute during
// evaluation and return an Indeterminate, otherwise return the False value.
if (context.IsMissingAttribute)
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return(EvaluationValue.Indeterminate);
}
else
{
context.Trace("condition evaluated into {0}", evaluationValue.ToString());
return(EvaluationValue.False);
}
}
}
finally
{
context.TraceContextValues();
context.RemoveIndent();
context.Trace("Condition: {0}", evaluationValue == null ? string.Empty : evaluationValue.ToString());
}
}
/// <summary>
/// Evaluates the variable into a value.
/// </summary>
/// <param name="context">The contex of the evaluation.</param>
/// <returns>The value of the function.</returns>
public EvaluationValue Evaluate(EvaluationContext context)
{
if (context == null) throw new ArgumentNullException("context");
context.Trace("Evaluating variable");
context.AddIndent();
try
{
if (_variableDefinition.Expression is ApplyElement)
{
context.Trace("Apply within condition.");
// There is a nested apply un this policy a new Apply will be created and also
// evaluated. It's return value will be used as the processed argument.
Apply childApply = new Apply((ApplyElement)_variableDefinition.Expression);
// Evaluate the Apply
_value = childApply.Evaluate(context);
context.TraceContextValues();
return _value;
}
else if (_variableDefinition.Expression is FunctionElement)
{
throw new NotImplementedException("FunctionElement"); //TODO:
}
else if (_variableDefinition.Expression is VariableReferenceElement)
{
var variableRef = _variableDefinition.Expression as VariableReferenceElement;
var variableDef = context.CurrentPolicy.VariableDefinition[variableRef.VariableId] as VariableDefinition;
context.TraceContextValues();
if (!variableDef.IsEvaluated)
{
return variableDef.Evaluate(context);
}
else
{
return variableDef.Value;
}
}
else if (_variableDefinition.Expression is AttributeValueElementReadWrite)
{
// The AttributeValue does not need to be processed
context.Trace("Attribute value {0}", _variableDefinition.Expression.ToString());
var att = (AttributeValueElementReadWrite)_variableDefinition.Expression;
var attributeValue = new AttributeValueElement(att.DataType, att.Contents, att.SchemaVersion);
_value = new EvaluationValue(
attributeValue.GetTypedValue(attributeValue.GetType(context), 0),
attributeValue.GetType(context));
return _value;
}
else if (_variableDefinition.Expression is AttributeDesignatorBase)
{
// Resolve the AttributeDesignator using the EvaluationEngine public methods.
context.Trace("Processing attribute designator: {0}", _variableDefinition.Expression.ToString());
var attrDes = (AttributeDesignatorBase)_variableDefinition.Expression;
BagValue bag = EvaluationEngine.Resolve(context, attrDes);
// If the attribute was not resolved by the EvaluationEngine search the
// attribute in the context document, also using the EvaluationEngine public
// methods.
if (bag.BagSize == 0)
{
if (_variableDefinition.Expression is SubjectAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding subject attribute designator: {0}", attrib.ToString());
bag.Add(attrib);
}
}
else if (_variableDefinition.Expression is ResourceAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding resource attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
else if (_variableDefinition.Expression is ActionAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding action attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
else if (_variableDefinition.Expression is EnvironmentAttributeDesignatorElement)
{
ctx.AttributeElement attrib = EvaluationEngine.GetAttribute(context, attrDes);
if (attrib != null)
{
context.Trace("Adding environment attribute designator {0}", attrib.ToString());
bag.Add(attrib);
}
}
}
// If the argument was not found and the attribute must be present this is
// a MissingAttribute situation so set the flag. Otherwise add the attribute
// to the processed arguments.
if (bag.BagSize == 0 && attrDes.MustBePresent)
{
context.Trace("Attribute is missing");
context.IsMissingAttribute = true;
context.AddMissingAttribute(attrDes);
_value = EvaluationValue.Indeterminate;
}
else
{
_value = new EvaluationValue(bag, bag.GetType(context));
}
return _value;
}
else if (_variableDefinition.Expression is AttributeSelectorElement)
{
// Resolve the XPath query using the EvaluationEngine public methods.
context.Trace("Attribute selector");
try
{
var attributeSelector = (AttributeSelectorElement)_variableDefinition.Expression;
BagValue bag = EvaluationEngine.Resolve(context, attributeSelector);
if (bag.Elements.Count == 0 && attributeSelector.MustBePresent)
{
context.Trace("Attribute is missing");
context.IsMissingAttribute = true;
context.AddMissingAttribute(attributeSelector);
_value = EvaluationValue.Indeterminate;
}
else
{
_value = new EvaluationValue(bag, bag.GetType(context));
}
}
catch (EvaluationException e)
{
context.Trace("ERR: {0}", e.Message);
context.ProcessingError = true;
_value = EvaluationValue.Indeterminate;
}
return _value;
}
throw new NotSupportedException("internal error");
}
finally
{
_isEvaluated = true;
context.RemoveIndent();
}
}
