iaik.ixsil.algorithms

Class TransformImplXPath2

java.lang.Object

iaik.ixsil.algorithms.Algorithm

iaik.ixsil.algorithms.Transform

iaik.ixsil.algorithms.TransformImplXPath2

public class TransformImplXPath2
extends Transform

Provides an transform implementation of the XPath Filter 2.0, as it has been specified in XML-Signature XPath Filter 2.0.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
protected class	TransformImplXPath2.NSDeclaration Auxilary class representing a XML namespace declaration structure.
protected class	TransformImplXPath2.XPathFilter Auxiliary class representing an XPath filter of this transform.

Field Summary

Fields

Modifier and Type	Field and Description
protected java.util.ArrayList	currentNodeAncestors_ The ancestors of the current node being processed by this transform.
protected static java.lang.String	DEFAULT_ALGORITHM_URI_ The default algorithm URI for this algorithm implementation.
protected static java.lang.String	FILTER_ATTRIBUTE_NAME_ The name of the filter attribute in the parameter element of this transform.
static int	FILTER_MODE_INTERSECT_ Filter mode "set intersection".
static int	FILTER_MODE_SUBTRACT_ Filter mode "set subtraction".
static int	FILTER_MODE_UNION_ Filter mode "set union".
static java.lang.String[]	FILTER_MODE_VALUES_ The possible values for the filter mode attribute of the XPath filter parameter element.
protected static java.lang.String	NAMESPACE_PREFIX_ The namespace prefix to be used in the XPath parameter element.
protected static java.lang.String	NAMESPACE_URI_ The namespace URI used for the transform's XPath parameter element.
protected static java.lang.String	PARAMETER_ELEMENT_NAME_ The name of the parameter element for this transform.
protected java.util.List	xPathFilters_ The list of XPath filters of this transform.

Fields inherited from class iaik.ixsil.algorithms.Transform

inputNodeSet_, inputOctetStream_, inputURI_

Fields inherited from class iaik.ixsil.algorithms.Algorithm

uri_

Constructor Summary

Constructors

Constructor and Description
TransformImplXPath2() Standard constructor.

Method Summary

Modifier and Type	Method and Description
protected boolean	addToFilterNodeList(org.w3c.dom.Node node) Tests if the specified node has to be added to the filter result node set.
void	addXPathFilter(java.lang.String xPath, int mode, java.util.Map nSDeclarations) Adds an XPath filter to the sequence of filters which are computed in order to get the filter node set.
protected void	checkBackingDOM(java.lang.String xPath, org.w3c.dom.Element xPath2ParamElem) In case that the specified xPath expression contains the here() function, checks if the input node set is backed by the same DOM instance as the specified DOM representation of the XPath Filter 2 parameter element.
protected int	getLastUnionFilterSetSExpandedPos(org.w3c.dom.Node node) Determines the position of the last union filter, whose expanded set S contains the specified node.
org.w3c.dom.NodeList	getXPath2Elements() Gets the DOM elements of the XPath elements of this transform.
protected boolean	isInAllSubsequentIntersectFilterSetSExpanded(int startFilterPos, org.w3c.dom.Node node) Tests if the specifed node is contained in the expanded set S of all intersect filters having a position greater or equal to startFilterPos.
protected boolean	isInFilterResultSetSExpanded(int filterPos, org.w3c.dom.Node node) Tests if the specified node is in the expanded set S of the filter with the specified position.
protected boolean	isInNoSubsequentSubtractFilterSetSExpanded(int startFilterPos, org.w3c.dom.Node node) Tests if the specified node is not contained in the expanded set S of any subtract filter having a position greater or equal to startFilterPos.
protected java.util.HashSet	nodeList2HashSet(org.w3c.dom.NodeList nodeList) Generates a hash set from the specified node list
protected void	setAsParent(org.w3c.dom.Node node) Adapts the specified ancestor list in a way that the specified node is the parent.
void	setParameters(org.w3c.dom.Element transformElement) Sets the parameters for this XPath Filter 2.0 transform implementation.
org.w3c.dom.Element	toElement(org.w3c.dom.Document signatureDOMDoc) Returns the DOM element representation of the transform.
java.lang.Object	transform() Computes the transform result for the previously specified input.

Methods inherited from class iaik.ixsil.algorithms.Transform

distributeNSDeclarations, setInput, setInput, skipStylesheetElem, withdrawDistributedNSDeclarations

Methods inherited from class iaik.ixsil.algorithms.Algorithm

getURI, setURI

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FILTER_MODE_INTERSECT_

public static final int FILTER_MODE_INTERSECT_

Filter mode "set intersection".

See Also:

Constant Field Values

FILTER_MODE_SUBTRACT_

public static final int FILTER_MODE_SUBTRACT_

Filter mode "set subtraction".

See Also:

Constant Field Values

FILTER_MODE_UNION_

public static final int FILTER_MODE_UNION_

Filter mode "set union".

See Also:

Constant Field Values

FILTER_MODE_VALUES_

public static final java.lang.String[] FILTER_MODE_VALUES_

The possible values for the filter mode attribute of the XPath filter parameter element.

DEFAULT_ALGORITHM_URI_

protected static final java.lang.String DEFAULT_ALGORITHM_URI_

The default algorithm URI for this algorithm implementation.

See Also:

Constant Field Values

NAMESPACE_URI_

protected static final java.lang.String NAMESPACE_URI_

The namespace URI used for the transform's XPath parameter element.

See Also:

Constant Field Values

NAMESPACE_PREFIX_

protected static final java.lang.String NAMESPACE_PREFIX_

The namespace prefix to be used in the XPath parameter element.

See Also:

Constant Field Values

PARAMETER_ELEMENT_NAME_

protected static final java.lang.String PARAMETER_ELEMENT_NAME_

The name of the parameter element for this transform.

See Also:

Constant Field Values

FILTER_ATTRIBUTE_NAME_

protected static final java.lang.String FILTER_ATTRIBUTE_NAME_

The name of the filter attribute in the parameter element of this transform.

See Also:

Constant Field Values

xPathFilters_

protected java.util.List xPathFilters_

The list of XPath filters of this transform.

currentNodeAncestors_

protected java.util.ArrayList currentNodeAncestors_

The ancestors of the current node being processed by this transform.

Constructor Detail

TransformImplXPath2

public TransformImplXPath2()

Standard constructor. Sets the default value for the algorithm URI to http://www.w3.org/2002/06/xmldsig-filter2.

Method Detail

setParameters

public void setParameters(org.w3c.dom.Element transformElement)
                   throws AlgorithmException

Sets the parameters for this XPath Filter 2.0 transform implementation. A XPath Filter 2.0 transform contains a sequence of explicit XPath parameter elements representing the XPath filters the transform is composed of. Each parameter element contains an XPath expression to be processed as its character data and an attribute named Filter, providing the operation mode of the filter (one of intersect, subtract, or union. The namespace attributes in scope for each parameter element will be used as the namespace context at evaluation of the XPath expression the parameter element contains.

Overrides:

setParameters in class Algorithm

Parameters:

transformElement - The DOM element representation of the transform, as it will be found by IXSIL in the XML signature.

Throws:

AlgorithmException - if no XPath parameter element can be found, or if an XPath parameter element does not contain any character data, or if setting the parameter fails for any other reason.

addXPathFilter

public void addXPathFilter(java.lang.String xPath,
                           int mode,
                           java.util.Map nSDeclarations)

Adds an XPath filter to the sequence of filters which are computed in order to get the filter node set.

Parameters:

xPath - The XPath expression of the filter. Must not be null or an empty string.

mode - The mode of the filter (see FILTER_MODE_INTERSECT_, FILTER_MODE_SUBTRACT_ and FILTER_MODE_UNION_).

nSDeclarations - A map of namespace declarations which are used as additonal part of the space context at evaluation of this filter's XPath expression. If a namespace prefix is used in this filter's XPath expression which is not in scope for the XPath element representing this XPath filter, it must be present in this set. The key of an entry in this map must be a valid namespace prefix String, the corresponding value must be the associated namespace URI. The map may be null.

getXPath2Elements

public org.w3c.dom.NodeList getXPath2Elements()

Gets the DOM elements of the XPath elements of this transform.

Returns:

The DOM elements of the XPath elements. All items in this list are DOM Element objects.

toElement

public org.w3c.dom.Element toElement(org.w3c.dom.Document signatureDOMDoc)
                              throws AlgorithmException

Returns the DOM element representation of the transform. Used by IXSIL to incorporate the transform into the XML representation of the signature.

Specified by:

toElement in class Algorithm

Parameters:

signatureDOMDoc - The DOM document which should be used to create necessary DOM nodes.

Returns:

the DOM element representation of the transform.

Throws:

AlgorithmException - if no identifying URI has been specified for this transform, or if no transform parameters (see addXPathFilter(java.lang.String, int, java.util.Map) have been specified.

transform

public java.lang.Object transform()
                           throws AlgorithmException

Computes the transform result for the previously specified input. If the input has been specified as an octet stream, the octet stream is interpreted as physical representation of a well-formed XML document, parsed and converted to a XPath node set which contains all nodes of the document. The XPath node set is transformed into the result according to the XPath Filter 2.0 specification (see description of this class).

Specified by:

transform in class Transform

Returns:

the result of the transformation process as XPath node set.

Throws:

AlgorithmException - if no input has been set previously, or if no parameters have been set previously, or if converting a input octet stream into a XPath node set input fails, or if performing the transform fails for any reason.

getLastUnionFilterSetSExpandedPos

protected int getLastUnionFilterSetSExpandedPos(org.w3c.dom.Node node)

Determines the position of the last union filter, whose expanded set S contains the specified node.

Parameters:

node - The node to be tested.

Returns:

the position of the last union filter, or -1 of no such filter exists.

isInAllSubsequentIntersectFilterSetSExpanded

protected boolean isInAllSubsequentIntersectFilterSetSExpanded(int startFilterPos,
                                                               org.w3c.dom.Node node)

Tests if the specifed node is contained in the expanded set S of all intersect filters having a position greater or equal to startFilterPos.

Parameters:

startFilterPos - The filter position at which to start this test.

node - The node to be tested.

Returns:

true if and only if the specified node is contained in all intersect filters as specified above, or if there are no intersect filters.

isInNoSubsequentSubtractFilterSetSExpanded

protected boolean isInNoSubsequentSubtractFilterSetSExpanded(int startFilterPos,
                                                             org.w3c.dom.Node node)

Tests if the specified node is not contained in the expanded set S of any subtract filter having a position greater or equal to startFilterPos.

Parameters:

startFilterPos - The filter position at which to start this test.

node - The node to be tested.

Returns:

true if and only if the specified node is not contained in any intersect filters as specified above, or if there are no subtract filters.

isInFilterResultSetSExpanded

protected boolean isInFilterResultSetSExpanded(int filterPos,
                                               org.w3c.dom.Node node)

Tests if the specified node is in the expanded set S of the filter with the specified position.

Parameters:

filterPos - The position of the filter whose set S should be investigated.

node - The node to be tested.

Returns:

true if and only if the specified node is in the expanded set S of the specified filter.

setAsParent

protected void setAsParent(org.w3c.dom.Node node)

Adapts the specified ancestor list in a way that the specified node is the parent.

Parameters:

node - The new parent.

addToFilterNodeList

protected boolean addToFilterNodeList(org.w3c.dom.Node node)

Tests if the specified node has to be added to the filter result node set.

Parameters:

node - The node to be tested.

Returns:

true if and only if the node has to be added to the filter result node set.

nodeList2HashSet

protected java.util.HashSet nodeList2HashSet(org.w3c.dom.NodeList nodeList)

Generates a hash set from the specified node list

Parameters:

nodeList - The original node list.

Returns:

a hash set generated from the specified node list.

checkBackingDOM

protected void checkBackingDOM(java.lang.String xPath,
                               org.w3c.dom.Element xPath2ParamElem)
                        throws AlgorithmException

In case that the specified xPath expression contains the here() function, checks if the input node set is backed by the same DOM instance as the specified DOM representation of the XPath Filter 2 parameter element. If not, throws an exception to inform the user that this is a malformed transform configuration.

Parameters:

xPath - The xPath expression.

xPath2ParamElem - The XPath Filter 2 parameter element.

Throws:

AlgorithmException - if the condition specified above is not met.