/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
/*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
*/
/*
* $Id: TransformService.java 1203738 2011-11-18 16:47:00Z mullan $
*/
package javax.xml.crypto.dsig;
import java.security.InvalidAlgorithmParameterException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;
import java.util.*;
import javax.xml.crypto.MarshalException;
import javax.xml.crypto.XMLStructure;
import javax.xml.crypto.XMLCryptoContext;
import javax.xml.crypto.dsig.spec.TransformParameterSpec;
/**
* A Service Provider Interface for transform and canonicalization algorithms.
*
* <p>Each instance of <code>TransformService</code> supports a specific
* transform or canonicalization algorithm and XML mechanism type. To create a
* <code>TransformService</code>, call one of the static
* {@link #getInstance getInstance} methods, passing in the algorithm URI and
* XML mechanism type desired, for example:
*
* <blockquote><code>
* TransformService ts = TransformService.getInstance(Transform.XPATH2, "DOM");
* </code></blockquote>
*
* <p><code>TransformService</code> implementations are registered and loaded
* using the {@link java.security.Provider} mechanism. Each
* <code>TransformService</code> service provider implementation should include
* a <code>MechanismType</code> service attribute that identifies the XML
* mechanism type that it supports. If the attribute is not specified,
* "DOM" is assumed. For example, a service provider that supports the
* XPath Filter 2 Transform and DOM mechanism would be specified in the
* <code>Provider</code> subclass as:
* <pre>
* put("TransformService." + Transform.XPATH2,
* "org.example.XPath2TransformService");
* put("TransformService." + Transform.XPATH2 + " MechanismType", "DOM");
* </pre>
* <code>TransformService</code> implementations that support the DOM
* mechanism type must abide by the DOM interoperability requirements defined
* in the
* <a href="../../../../overview-summary.html#DOM Mechanism Requirements">DOM
* Mechanism Requirements</a> section of the API overview. See the
* <a href="../../../../overview-summary.html#Service Provider">Service
* Providers</a> section of the API overview for a list of standard mechanism
* types.
* <p>
* Once a <code>TransformService</code> has been created, it can be used
* to process <code>Transform</code> or <code>CanonicalizationMethod</code>
* objects. If the <code>Transform</code> or <code>CanonicalizationMethod</code>
* exists in XML form (for example, when validating an existing
* <code>XMLSignature</code>), the {@link #init(XMLStructure, XMLCryptoContext)}
* method must be first called to initialize the transform and provide document
* context (even if there are no parameters). Alternatively, if the
* <code>Transform</code> or <code>CanonicalizationMethod</code> is being
* created from scratch, the {@link #init(TransformParameterSpec)} method
* is called to initialize the transform with parameters and the
* {@link #marshalParams marshalParams} method is called to marshal the
* parameters to XML and provide the transform with document context. Finally,
* the {@link #transform transform} method is called to perform the
* transformation.
* <p>
* <b>Concurrent Access</b>
* <p>The static methods of this class are guaranteed to be thread-safe.
* Multiple threads may concurrently invoke the static methods defined in this
* class with no ill effects.
*
* <p>However, this is not true for the non-static methods defined by this
* class. Unless otherwise documented by a specific provider, threads that
* need to access a single <code>TransformService</code> instance
* concurrently should synchronize amongst themselves and provide the
* necessary locking. Multiple threads each manipulating a different
* <code>TransformService</code> instance need not synchronize.
*
* @author Sean Mullan
* @author JSR 105 Expert Group
*/
public abstract class TransformService implements Transform {
private String algorithm;
private String mechanism;
private Provider provider;
/**
* Default constructor, for invocation by subclasses.
*/
protected TransformService() {}
/**
* Returns a <code>TransformService</code> that supports the specified
* algorithm URI (ex: {@link Transform#XPATH2}) and mechanism type
* (ex: DOM).
*
* <p>This method uses the standard JCA provider lookup mechanism to
* locate and instantiate a <code>TransformService</code> implementation
* of the desired algorithm and <code>MechanismType</code> service
* attribute. It traverses the list of registered security
* <code>Provider</code>s, starting with the most preferred
* <code>Provider</code>. A new <code>TransformService</code> object
* from the first <code>Provider</code> that supports the specified
* algorithm and mechanism type is returned.
*
* <p> Note that the list of registered providers may be retrieved via
* the {@link Security#getProviders() Security.getProviders()} method.
*
* @param algorithm the URI of the algorithm
* @param mechanismType the type of the XML processing mechanism and
* representation
* @return a new <code>TransformService</code>
* @throws NullPointerException if <code>algorithm</code> or
* <code>mechanismType</code> is <code>null</code>
* @throws NoSuchAlgorithmException if no <code>Provider</code> supports a
* <code>TransformService</code> implementation for the specified
* algorithm and mechanism type
* @see Provider
*/
public static TransformService getInstance
(String algorithm, String mechanismType)
throws NoSuchAlgorithmException {
if (mechanismType == null || algorithm == null) {
throw new NullPointerException();
}
return findInstance(algorithm, mechanismType, null);
}
/**
* Returns a <code>TransformService</code> that supports the specified
* algorithm URI (ex: {@link Transform#XPATH2}) and mechanism type
* (ex: DOM) as supplied by the specified provider. Note that the specified
* <code>Provider</code> object does not have to be registered in the
* provider list.
*
* @param algorithm the URI of the algorithm
* @param mechanismType the type of the XML processing mechanism and
* representation
* @param provider the <code>Provider</code> object
* @return a new <code>TransformService</code>
* @throws NullPointerException if <code>provider</code>,
* <code>algorithm</code>, or <code>mechanismType</code> is
* <code>null</code>
* @throws NoSuchAlgorithmException if a <code>TransformService</code>
* implementation for the specified algorithm and mechanism type is not
* available from the specified <code>Provider</code> object
* @see Provider
*/
public static TransformService getInstance
(String algorithm, String mechanismType, Provider provider)
throws NoSuchAlgorithmException {
if (mechanismType == null || algorithm == null || provider == null) {
throw new NullPointerException();
}
return findInstance(algorithm, mechanismType, provider);
}
/**
* Returns a <code>TransformService</code> that supports the specified
* algorithm URI (ex: {@link Transform#XPATH2}) and mechanism type
* (ex: DOM) as supplied by the specified provider. The specified provider
* must be registered in the security provider list.
*
* <p>Note that the list of registered providers may be retrieved via
* the {@link Security#getProviders() Security.getProviders()} method.
*
* @param algorithm the URI of the algorithm
* @param mechanismType the type of the XML processing mechanism and
* representation
* @param provider the string name of the provider
* @return a new <code>TransformService</code>
* @throws NoSuchProviderException if the specified provider is not
* registered in the security provider list
* @throws NullPointerException if <code>provider</code>,
* <code>mechanismType</code>, or <code>algorithm</code> is
* <code>null</code>
* @throws NoSuchAlgorithmException if a <code>TransformService</code>
* implementation for the specified algorithm and mechanism type is not
* available from the specified provider
* @see Provider
*/
public static TransformService getInstance
(String algorithm, String mechanismType, String provider)
throws NoSuchAlgorithmException, NoSuchProviderException {
if (mechanismType == null || algorithm == null || provider == null) {
throw new NullPointerException();
}
Provider prov = Security.getProvider(provider);
if (prov == null) {
throw new NoSuchProviderException("cannot find provider named "
+ provider);
}
return findInstance(algorithm, mechanismType, prov);
}
private static TransformService findInstance(String algorithm,
String mechanismType, Provider provider)
throws NoSuchAlgorithmException {
if (provider == null) {
provider = getProvider("TransformService", algorithm,
mechanismType);
}
Provider.Service ps = provider.getService("TransformService",
algorithm);
if (ps == null) {
throw new NoSuchAlgorithmException("no such algorithm: " +
algorithm + " for provider " +
provider.getName());
}
TransformService ts = (TransformService)ps.newInstance(null);
ts.algorithm = algorithm;
ts.mechanism = mechanismType;
ts.provider = provider;
return ts;
}
private static Provider getProvider(String engine, String alg, String mech)
throws NoSuchAlgorithmException
{
Map<String, String> map = new HashMap<String, String>();
map.put(engine + "." + alg, "");
map.put(engine + "." + alg + " " + "MechanismType", mech);
Provider[] providers = Security.getProviders(map);
if (providers == null) {
if (mech.equals("DOM")) {
// look for providers without MechanismType specified
map.clear();
map.put(engine + "." + alg, "");
providers = Security.getProviders(map);
if (providers != null)
return providers[0];
}
throw new NoSuchAlgorithmException("Algorithm type " + alg +
" not available");
}
return providers[0];
}
/**
* Returns the mechanism type supported by this <code>TransformService</code>.
*
* @return the mechanism type
*/
public final String getMechanismType() {
return mechanism;
}
/**
* Returns the URI of the algorithm supported by this
* <code>TransformService</code>.
*
* @return the algorithm URI
*/
public final String getAlgorithm() {
return algorithm;
}
/**
* Returns the provider of this <code>TransformService</code>.
*
* @return the provider
*/
public final Provider getProvider() {
return provider;
}
/**
* Initializes this <code>TransformService</code> with the specified
* parameters.
*
* <p>If the parameters exist in XML form, the
* {@link #init(XMLStructure, XMLCryptoContext)} method should be used to
* initialize the <code>TransformService</code>.
*
* @param params the algorithm parameters (may be <code>null</code> if
* not required or optional)
* @throws InvalidAlgorithmParameterException if the specified parameters
* are invalid for this algorithm
*/
public abstract void init(TransformParameterSpec params)
throws InvalidAlgorithmParameterException;
/**
* Marshals the algorithm-specific parameters. If there are no parameters
* to be marshalled, this method returns without throwing an exception.
*
* @param parent a mechanism-specific structure containing the parent
* node that the marshalled parameters should be appended to
* @param context the <code>XMLCryptoContext</code> containing
* additional context (may be <code>null</code> if not applicable)
* @throws ClassCastException if the type of <code>parent</code> or
* <code>context</code> is not compatible with this
* <code>TransformService</code>
* @throws NullPointerException if <code>parent</code> is <code>null</code>
* @throws MarshalException if the parameters cannot be marshalled
*/
public abstract void marshalParams
(XMLStructure parent, XMLCryptoContext context)
throws MarshalException;
/**
* Initializes this <code>TransformService</code> with the specified
* parameters and document context.
*
* @param parent a mechanism-specific structure containing the parent
* structure
* @param context the <code>XMLCryptoContext</code> containing
* additional context (may be <code>null</code> if not applicable)
* @throws ClassCastException if the type of <code>parent</code> or
* <code>context</code> is not compatible with this
* <code>TransformService</code>
* @throws NullPointerException if <code>parent</code> is <code>null</code>
* @throws InvalidAlgorithmParameterException if the specified parameters
* are invalid for this algorithm
*/
public abstract void init(XMLStructure parent, XMLCryptoContext context)
throws InvalidAlgorithmParameterException;
}