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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,
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package com.sun.org.apache.xml.internal.security.keys.keyresolver.implementations;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.security.PublicKey;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;

import javax.xml.XMLConstants;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import com.sun.org.apache.xml.internal.security.c14n.CanonicalizationException;
import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;
import com.sun.org.apache.xml.internal.security.keys.content.RetrievalMethod;
import com.sun.org.apache.xml.internal.security.keys.content.x509.XMLX509Certificate;
import com.sun.org.apache.xml.internal.security.keys.keyresolver.KeyResolver;
import com.sun.org.apache.xml.internal.security.keys.keyresolver.KeyResolverException;
import com.sun.org.apache.xml.internal.security.keys.keyresolver.KeyResolverSpi;
import com.sun.org.apache.xml.internal.security.keys.storage.StorageResolver;
import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;
import com.sun.org.apache.xml.internal.security.transforms.Transforms;
import com.sun.org.apache.xml.internal.security.utils.Constants;
import com.sun.org.apache.xml.internal.security.utils.XMLUtils;
import com.sun.org.apache.xml.internal.security.utils.resolver.ResourceResolver;
import org.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.xml.sax.SAXException;

The RetrievalMethodResolver can retrieve public keys and certificates from
other locations. The location is specified using the ds:RetrievalMethod
element which points to the location. This includes the handling of raw
(binary) X.509 certificate which are not encapsulated in an XML structure.
If the retrieval process encounters an element which the
RetrievalMethodResolver cannot handle itself, resolving of the extracted
element is delegated back to the KeyResolver mechanism.
Author:
$Author: raul $ modified by Dave Garcia/**
 * The RetrievalMethodResolver can retrieve public keys and certificates from
 * other locations. The location is specified using the ds:RetrievalMethod
 * element which points to the location. This includes the handling of raw
 * (binary) X.509 certificate which are not encapsulated in an XML structure.
 * If the retrieval process encounters an element which the
 * RetrievalMethodResolver cannot handle itself, resolving of the extracted
 * element is delegated back to the KeyResolver mechanism.
 *
 * @author $Author: raul $ modified by Dave Garcia
 */
public class RetrievalMethodResolver extends KeyResolverSpi {

    
logging logging facility /** {@link org.apache.commons.logging} logging facility */
    private static java.util.logging.Logger log =
        java.util.logging.Logger.getLogger(RetrievalMethodResolver.class.getName());

    
Method engineResolvePublicKey
Params:
element – 
baseURI – 
storage – 
@inheritDoc
/**
     * Method engineResolvePublicKey
     * @inheritDoc
     * @param element
     * @param baseURI
     * @param storage
     */
    public PublicKey engineLookupAndResolvePublicKey(
           Element element, String baseURI, StorageResolver storage
    ) {
        if (!XMLUtils.elementIsInSignatureSpace(element, Constants._TAG_RETRIEVALMETHOD)) {
            return null;
        }

        try {
            // Create a retrieval method over the given element
            RetrievalMethod rm = new RetrievalMethod(element, baseURI);
            String type = rm.getType();
            XMLSignatureInput resource = resolveInput(rm, baseURI, secureValidation);
            if (RetrievalMethod.TYPE_RAWX509.equals(type)) {
                // a raw certificate, direct parsing is done!
                X509Certificate cert = getRawCertificate(resource);
                if (cert != null) {
                    return cert.getPublicKey();
                }
                return null;
             }
             Element e = obtainReferenceElement(resource);

             // Check to make sure that the reference is not to another RetrievalMethod
             // which points to this element
             if (XMLUtils.elementIsInSignatureSpace(e, Constants._TAG_RETRIEVALMETHOD)) {
                 if (secureValidation) {
                     String error = "Error: It is forbidden to have one RetrievalMethod "
                         + "point to another with secure validation";
                     if (log.isLoggable(java.util.logging.Level.FINE)) {
                         log.log(java.util.logging.Level.FINE, error);
                     }
                     return null;
                 }
                 RetrievalMethod rm2 = new RetrievalMethod(e, baseURI);
                 XMLSignatureInput resource2 = resolveInput(rm2, baseURI, secureValidation);
                 Element e2 = obtainReferenceElement(resource2);
                 if (e2 == element) {
                     if (log.isLoggable(java.util.logging.Level.FINE)) {
                         log.log(java.util.logging.Level.FINE, "Error: Can't have RetrievalMethods pointing to each other");
                     }
                     return null;
                 }
             }

             return resolveKey(e, baseURI, storage);
         } catch (XMLSecurityException ex) {
             if (log.isLoggable(java.util.logging.Level.FINE)) {
                 log.log(java.util.logging.Level.FINE, "XMLSecurityException", ex);
             }
         } catch (CertificateException ex) {
             if (log.isLoggable(java.util.logging.Level.FINE)) {
                 log.log(java.util.logging.Level.FINE, "CertificateException", ex);
             }
         } catch (IOException ex) {
             if (log.isLoggable(java.util.logging.Level.FINE)) {
                 log.log(java.util.logging.Level.FINE, "IOException", ex);
             }
         } catch (ParserConfigurationException e) {
             if (log.isLoggable(java.util.logging.Level.FINE)) {
                 log.log(java.util.logging.Level.FINE, "ParserConfigurationException", e);
             }
         } catch (SAXException e) {
             if (log.isLoggable(java.util.logging.Level.FINE)) {
                 log.log(java.util.logging.Level.FINE, "SAXException", e);
             }
         }
         return null;
    }

    
Method engineResolveX509Certificate
Params:
element – 
baseURI – 
storage – 
@inheritDoc
/**
     * Method engineResolveX509Certificate
     * @inheritDoc
     * @param element
     * @param baseURI
     * @param storage
     */
    public X509Certificate engineLookupResolveX509Certificate(
        Element element, String baseURI, StorageResolver storage) {
        if (!XMLUtils.elementIsInSignatureSpace(element, Constants._TAG_RETRIEVALMETHOD)) {
             return null;
        }

        try {
            RetrievalMethod rm = new RetrievalMethod(element, baseURI);
            String type = rm.getType();
            XMLSignatureInput resource = resolveInput(rm, baseURI, secureValidation);
            if (RetrievalMethod.TYPE_RAWX509.equals(type)) {
                return getRawCertificate(resource);
            }

            Element e = obtainReferenceElement(resource);

            // Check to make sure that the reference is not to another RetrievalMethod
            // which points to this element
            if (XMLUtils.elementIsInSignatureSpace(e, Constants._TAG_RETRIEVALMETHOD)) {
                if (secureValidation) {
                    String error = "Error: It is forbidden to have one RetrievalMethod "
                        + "point to another with secure validation";
                    if (log.isLoggable(java.util.logging.Level.FINE)) {
                        log.log(java.util.logging.Level.FINE, error);
                    }
                    return null;
                }
                RetrievalMethod rm2 = new RetrievalMethod(e, baseURI);
                XMLSignatureInput resource2 = resolveInput(rm2, baseURI, secureValidation);
                Element e2 = obtainReferenceElement(resource2);
                if (e2 == element) {
                    if (log.isLoggable(java.util.logging.Level.FINE)) {
                        log.log(java.util.logging.Level.FINE, "Error: Can't have RetrievalMethods pointing to each other");
                    }
                    return null;
                }
            }

            return resolveCertificate(e, baseURI, storage);
        } catch (XMLSecurityException ex) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "XMLSecurityException", ex);
            }
        } catch (CertificateException ex) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "CertificateException", ex);
            }
        } catch (IOException ex) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "IOException", ex);
            }
        } catch (ParserConfigurationException e) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "ParserConfigurationException", e);
            }
        } catch (SAXException e) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "SAXException", e);
            }
        }
        return null;
    }

    
Retrieves a x509Certificate from the given information
Params:
e – 
baseURI – 
storage – 
Throws:
KeyResolverException – 
Returns:
/**
     * Retrieves a x509Certificate from the given information
     * @param e
     * @param baseURI
     * @param storage
     * @return
     * @throws KeyResolverException
     */
    private static X509Certificate resolveCertificate(
        Element e, String baseURI, StorageResolver storage
    ) throws KeyResolverException {
        if (log.isLoggable(java.util.logging.Level.FINE)) {
            log.log(java.util.logging.Level.FINE, "Now we have a {" + e.getNamespaceURI() + "}"
                + e.getLocalName() + " Element");
        }
        // An element has been provided
        if (e != null) {
            return KeyResolver.getX509Certificate(e, baseURI, storage);
        }
        return null;
    }

    
Retrieves a PublicKey from the given information
Params:
e – 
baseURI – 
storage – 
Throws:
KeyResolverException – 
Returns:
/**
     * Retrieves a PublicKey from the given information
     * @param e
     * @param baseURI
     * @param storage
     * @return
     * @throws KeyResolverException
     */
    private static PublicKey resolveKey(
        Element e, String baseURI, StorageResolver storage
    ) throws KeyResolverException {
        if (log.isLoggable(java.util.logging.Level.FINE)) {
            log.log(java.util.logging.Level.FINE, "Now we have a {" + e.getNamespaceURI() + "}"
                + e.getLocalName() + " Element");
        }
        // An element has been provided
        if (e != null) {
            return KeyResolver.getPublicKey(e, baseURI, storage);
        }
        return null;
    }

    private static Element obtainReferenceElement(XMLSignatureInput resource)
        throws CanonicalizationException, ParserConfigurationException,
        IOException, SAXException, KeyResolverException {
        Element e;
        if (resource.isElement()){
            e = (Element) resource.getSubNode();
        } else if (resource.isNodeSet()) {
            // Retrieved resource is a nodeSet
            e = getDocumentElement(resource.getNodeSet());
        } else {
            // Retrieved resource is an inputStream
            byte inputBytes[] = resource.getBytes();
            e = getDocFromBytes(inputBytes);
            // otherwise, we parse the resource, create an Element and delegate
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "we have to parse " + inputBytes.length + " bytes");
            }
        }
        return e;
    }

    private static X509Certificate getRawCertificate(XMLSignatureInput resource)
        throws CanonicalizationException, IOException, CertificateException {
        byte inputBytes[] = resource.getBytes();
        // if the resource stores a raw certificate, we have to handle it
        CertificateFactory certFact =
            CertificateFactory.getInstance(XMLX509Certificate.JCA_CERT_ID);
        X509Certificate cert = (X509Certificate)
            certFact.generateCertificate(new ByteArrayInputStream(inputBytes));
        return cert;
    }

    
Resolves the input from the given retrieval method
Throws:
XMLSecurityException – 
Returns:
/**
     * Resolves the input from the given retrieval method
     * @return
     * @throws XMLSecurityException
     */
    private static XMLSignatureInput resolveInput(
        RetrievalMethod rm, String baseURI, boolean secureValidation
    ) throws XMLSecurityException {
        Attr uri = rm.getURIAttr();
        // Apply the transforms
        Transforms transforms = rm.getTransforms();
        ResourceResolver resRes = ResourceResolver.getInstance(uri, baseURI, secureValidation);
        XMLSignatureInput resource = resRes.resolve(uri, baseURI, secureValidation);
        if (transforms != null) {
            if (log.isLoggable(java.util.logging.Level.FINE)) {
                log.log(java.util.logging.Level.FINE, "We have Transforms");
            }
            resource = transforms.performTransforms(resource);
        }
        return resource;
    }

    
Parses a byte array and returns the parsed Element.
Params:
bytes – 
Throws:
KeyResolverException – if something goes wrong
Returns:
the Document Element after parsing bytes/**
     * Parses a byte array and returns the parsed Element.
     *
     * @param bytes
     * @return the Document Element after parsing bytes
     * @throws KeyResolverException if something goes wrong
     */
    private static Element getDocFromBytes(byte[] bytes) throws KeyResolverException {
        try {
            DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
            dbf.setNamespaceAware(true);
            dbf.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);
            DocumentBuilder db = dbf.newDocumentBuilder();
            Document doc = db.parse(new ByteArrayInputStream(bytes));
            return doc.getDocumentElement();
        } catch (SAXException ex) {
            throw new KeyResolverException("empty", ex);
        } catch (IOException ex) {
            throw new KeyResolverException("empty", ex);
        } catch (ParserConfigurationException ex) {
            throw new KeyResolverException("empty", ex);
        }
    }

    
Method engineResolveSecretKey
Params:
element – 
baseURI – 
storage – 
@inheritDoc
/**
     * Method engineResolveSecretKey
     * @inheritDoc
     * @param element
     * @param baseURI
     * @param storage
     */
    public javax.crypto.SecretKey engineLookupAndResolveSecretKey(
        Element element, String baseURI, StorageResolver storage
    ) {
        return null;
    }

    private static Element getDocumentElement(Set<Node> set) {
        Iterator<Node> it = set.iterator();
        Element e = null;
        while (it.hasNext()) {
            Node currentNode = it.next();
            if (currentNode != null && Node.ELEMENT_NODE == currentNode.getNodeType()) {
                e = (Element) currentNode;
                break;
            }
        }
        List<Node> parents = new ArrayList<Node>();

        // Obtain all the parents of the elemnt
        while (e != null) {
            parents.add(e);
            Node n = e.getParentNode();
            if (n == null || Node.ELEMENT_NODE != n.getNodeType()) {
                break;
            }
            e = (Element) n;
        }
        // Visit them in reverse order.
        ListIterator<Node> it2 = parents.listIterator(parents.size()-1);
        Element ele = null;
        while (it2.hasPrevious()) {
            ele = (Element) it2.previous();
            if (set.contains(ele)) {
                return ele;
            }
        }
        return null;
    }
}