org.apache.xml.security.utils.resolver.implementations.ResolverXPointer Maven / Gradle / Ivy

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Apache XML Security for Java supports XML-Signature Syntax and Processing, W3C Recommendation 12 February 2002, and XML Encryption Syntax and Processing, W3C Recommendation 10 December 2002. As of version 1.4, the library supports the standard Java API JSR-105: XML Digital Signature APIs.
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/**
 * 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.
 */
package org.apache.xml.security.utils.resolver.implementations;

import org.apache.xml.security.signature.XMLSignatureInput;
import org.apache.xml.security.utils.XMLUtils;
import org.apache.xml.security.utils.resolver.ResourceResolverContext;
import org.apache.xml.security.utils.resolver.ResourceResolverException;
import org.apache.xml.security.utils.resolver.ResourceResolverSpi;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;

/**
 * Handles barename XPointer Reference URIs.
 * 

 * To retain comments while selecting an element by an identifier ID,
 * use the following full XPointer: URI='#xpointer(id('ID'))'.
 * 

 * To retain comments while selecting the entire document,
 * use the following full XPointer: URI='#xpointer(/)'.
 * This XPointer contains a simple XPath expression that includes
 * the root node, which the second to last step above replaces with all
 * nodes of the parse tree (all descendants, plus all attributes,
 * plus all namespaces nodes).
 *
 * @author $Author: coheigea $
 */
public class ResolverXPointer extends ResourceResolverSpi {

    private static org.slf4j.Logger log =
        org.slf4j.LoggerFactory.getLogger(ResolverXPointer.class);
    
    private static final String XP = "#xpointer(id(";
    private static final int XP_LENGTH = XP.length();

    @Override
    public boolean engineIsThreadSafe() {
        return true;
    }
    
    /**
     * @inheritDoc
     */
    @Override
    public XMLSignatureInput engineResolveURI(ResourceResolverContext context)
        throws ResourceResolverException {

        Node resultNode = null;
        Document doc = context.attr.getOwnerElement().getOwnerDocument();

        if (isXPointerSlash(context.uriToResolve)) {
            resultNode = doc;
        } else if (isXPointerId(context.uriToResolve)) {
            String id = getXPointerId(context.uriToResolve);
            resultNode = doc.getElementById(id);
            
            if (context.secureValidation) {
                Element start = context.attr.getOwnerDocument().getDocumentElement();
                if (!XMLUtils.protectAgainstWrappingAttack(start, id)) {
                    Object exArgs[] = { id };
                    throw new ResourceResolverException(
                        "signature.Verification.MultipleIDs", exArgs, context.uriToResolve, context.baseUri
                    );
                }
            }

            if (resultNode == null) {
                Object exArgs[] = { id };

                throw new ResourceResolverException(
                    "signature.Verification.MissingID", exArgs, context.uriToResolve, context.baseUri
                );
            }
        }

        XMLSignatureInput result = new XMLSignatureInput(resultNode);
        result.setSecureValidation(context.secureValidation);

        result.setMIMEType("text/xml");
        if (context.baseUri != null && context.baseUri.length() > 0) {
            result.setSourceURI(context.baseUri.concat(context.uriToResolve));      
        } else {
            result.setSourceURI(context.uriToResolve);      
        }

        return result;
    }

    /**
     * @inheritDoc
     */
    public boolean engineCanResolveURI(ResourceResolverContext context) {
        if (context.uriToResolve == null) {
            return false;
        }
        if (isXPointerSlash(context.uriToResolve) || isXPointerId(context.uriToResolve)) {
            return true;
        }

        return false;
    }

    /**
     * Method isXPointerSlash
     *
     * @param uri
     * @return true if begins with xpointer
     */
    private static boolean isXPointerSlash(String uri) {
        if (uri.equals("#xpointer(/)")) {
            return true;
        }

        return false;
    }

    /**
     * Method isXPointerId
     *
     * @param uri
     * @return whether it has an xpointer id
     */
    private static boolean isXPointerId(String uri) {
        if (uri.startsWith(XP) && uri.endsWith("))")) {
            String idPlusDelim = uri.substring(XP_LENGTH, uri.length() - 2);

            int idLen = idPlusDelim.length() -1;
            if (idPlusDelim.charAt(0) == '"' && idPlusDelim.charAt(idLen) == '"' 
                || idPlusDelim.charAt(0) == '\'' && idPlusDelim.charAt(idLen) == '\'') {
                if (log.isDebugEnabled()) {
                    log.debug("Id = " + idPlusDelim.substring(1, idLen));
                }
                return true;
            }
        }

        return false;
    }

    /**
     * Method getXPointerId
     *
     * @param uri
     * @return xpointerId to search.
     */
    private static String getXPointerId(String uri) {
        if (uri.startsWith(XP) && uri.endsWith("))")) {
            String idPlusDelim = uri.substring(XP_LENGTH,uri.length() - 2);
            
            int idLen = idPlusDelim.length() -1;
            if (idPlusDelim.charAt(0) == '"' && idPlusDelim.charAt(idLen) == '"' 
                || idPlusDelim.charAt(0) == '\'' && idPlusDelim.charAt(idLen) == '\'') {
                return idPlusDelim.substring(1, idLen);
            }
        }

        return null;
    }
}