/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* Licensed 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.
*
*/
package org.apache.xml.security.transforms.implementations;
import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Iterator;
import java.util.Set;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import org.apache.xml.security.c14n.CanonicalizationException;
import org.apache.xml.security.c14n.InvalidCanonicalizerException;
import org.apache.xml.security.exceptions.Base64DecodingException;
import org.apache.xml.security.signature.XMLSignatureInput;
import org.apache.xml.security.transforms.TransformSpi;
import org.apache.xml.security.transforms.TransformationException;
import org.apache.xml.security.transforms.Transforms;
import org.apache.xml.security.utils.Base64;
import org.w3c.dom.Document;
import org.w3c.dom.Node;
import org.w3c.dom.Text;
import org.w3c.dom.traversal.DocumentTraversal;
import org.w3c.dom.traversal.NodeFilter;
import org.w3c.dom.traversal.TreeWalker;
import org.xml.sax.SAXException;
/**
* Implements the <CODE>http://www.w3.org/2000/09/xmldsig#base64</CODE> decoding
* transform.
*
* <p>The normative specification for base64 decoding transforms is
* <A HREF="http://www.w3.org/TR/2001/CR-xmldsig-core-20010419/#ref-MIME">[MIME]</A>.
* The base64 Transform element has no content. The input
* is decoded by the algorithms. This transform is useful if an
* application needs to sign the raw data associated with the encoded
* content of an element. </p>
*
* <p>This transform requires an octet stream for input.
* If an XPath node-set (or sufficiently functional alternative) is
* given as input, then it is converted to an octet stream by
* performing operations logically equivalent to 1) applying an XPath
* transform with expression self::text(), then 2) taking the string-value
* of the node-set. Thus, if an XML element is identified by a barename
* XPointer in the Reference URI, and its content consists solely of base64
* encoded character data, then this transform automatically strips away the
* start and end tags of the identified element and any of its descendant
* elements as well as any descendant comments and processing instructions.
* The output of this transform is an octet stream.</p>
*
* @author Christian Geuer-Pollmann
* @see org.apache.xml.security.utils.Base64
*/
public class TransformBase64Decode extends TransformSpi {
/** Field implementedTransformURI */
public static final String implementedTransformURI =
Transforms.TRANSFORM_BASE64_DECODE;
/**
* Method engineGetURI
*
*
*/
protected String engineGetURI() {
return TransformBase64Decode.implementedTransformURI;
}
//J-
public boolean wantsOctetStream () { return true; }
public boolean wantsNodeSet () { return true; }
public boolean returnsOctetStream () { return true; }
public boolean returnsNodeSet () { return false; }
//J+
/**
* Method enginePerformTransform
*
* @param input
*
* @throws CanonicalizationException
* @throws IOException
* @throws InvalidCanonicalizerException
* @throws TransformationException
*/
protected XMLSignatureInput enginePerformTransform(XMLSignatureInput input)
throws IOException, CanonicalizationException,
TransformationException, InvalidCanonicalizerException {
try {
if (input.isOctetStream() || isTextNodeSet(input.getNodeSet())) {
try {
byte[] base64Bytes = input.getBytes();
byte[] decodedBytes = Base64.decode(base64Bytes);
return new XMLSignatureInput(
new ByteArrayInputStream(decodedBytes));
} catch (Base64DecodingException ex) {
throw new TransformationException("empty", ex);
}
} else {
try {
Document doc =
DocumentBuilderFactory.newInstance().newDocumentBuilder().parse(
input.getOctetStream());
DocumentTraversal dt = ((DocumentTraversal) doc);
Node rootNode = (Node) doc;
// we accept all nodes
NodeFilter nodefilter = new AlwaysAcceptNodeFilter();
TreeWalker treewalker = dt.createTreeWalker(rootNode,
NodeFilter.SHOW_ALL,
nodefilter, true);
StringBuffer sb = new StringBuffer();
process(treewalker, sb);
byte[] decodedBytes = Base64.decode(sb.toString());
return new XMLSignatureInput(
new ByteArrayInputStream(decodedBytes));
} catch (ParserConfigurationException e) {
throw new TransformationException("c14n.Canonicalizer.Exception",
e);
} catch (SAXException e) {
throw new TransformationException("SAX exception", e);
} catch (Base64DecodingException ex) {
throw new TransformationException("empty", ex);
}
}
} catch (ParserConfigurationException e) {
throw new TransformationException("c14n.Canonicalizer.Exception",
e);
} catch (SAXException e) {
throw new TransformationException("SAX exception", e);
}
}
/**
* Method process
*
* @param treewalker
* @param sb
*/
private void process(TreeWalker treewalker, StringBuffer sb) {
Node currentNode = treewalker.getCurrentNode();
if (currentNode.getNodeType() == Node.TEXT_NODE) {
sb.append(((Text) currentNode).getData());
}
for (Node node1 = treewalker.firstChild(); node1 != null;
node1 = treewalker.nextSibling()) {
process(treewalker, sb);
}
treewalker.setCurrentNode(currentNode);
}
/**
* Method to take a set of nodes and check whether any are "non-text"
*/
private boolean isTextNodeSet(Set s) {
boolean isText = true;
Iterator it = s.iterator();
while (it.hasNext() && isText) {
Node n = (Node) it.next();
if (n.getNodeType() != Node.TEXT_NODE)
isText = false;
}
return isText;
}
/**
* This {@link NodeFilter} always returns <code>true</code>
*
* @author Christian Geuer-Pollmann
*/
public class AlwaysAcceptNodeFilter implements NodeFilter {
/**
* Method acceptNode
*
* @param n
*
*/
public short acceptNode(Node n) {
return NodeFilter.FILTER_ACCEPT;
}
}
}