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1   /**
2    * This file Copyright (c) 2017-2018 Magnolia International
3    * Ltd.  (http://www.magnolia-cms.com). All rights reserved.
4    *
5    *
6    * This file is dual-licensed under both the Magnolia
7    * Network Agreement and the GNU General Public License.
8    * You may elect to use one or the other of these licenses.
9    *
10   * This file is distributed in the hope that it will be
11   * useful, but AS-IS and WITHOUT ANY WARRANTY; without even the
12   * implied warranty of MERCHANTABILITY or FITNESS FOR A
13   * PARTICULAR PURPOSE, TITLE, or NONINFRINGEMENT.
14   * Redistribution, except as permitted by whichever of the GPL
15   * or MNA you select, is prohibited.
16   *
17   * 1. For the GPL license (GPL), you can redistribute and/or
18   * modify this file under the terms of the GNU General
19   * Public License, Version 3, as published by the Free Software
20   * Foundation.  You should have received a copy of the GNU
21   * General Public License, Version 3 along with this program;
22   * if not, write to the Free Software Foundation, Inc., 51
23   * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
24   *
25   * 2. For the Magnolia Network Agreement (MNA), this file
26   * and the accompanying materials are made available under the
27   * terms of the MNA which accompanies this distribution, and
28   * is available at http://www.magnolia-cms.com/mna.html
29   *
30   * Any modifications to this file must keep this entire header
31   * intact.
32   *
33   */
34  package info.magnolia.importexport.filters;
35  
36  import static com.google.common.collect.Sets.newHashSet;
37  
38  import java.util.Set;
39  
40  import org.xml.sax.Attributes;
41  import org.xml.sax.SAXException;
42  import org.xml.sax.helpers.AttributesImpl;
43  import org.xml.sax.helpers.XMLFilterImpl;
44  
45  /**
46   * This filter allows skipping "unwanted" name spaces, by giving an explicit white-list of allowed namespaces.
47   *
48   * <p>This is particularly useful for JCR exports, as we don't want to pollute bootstrap files,
49   * which could in turn pollute the namespace registries of other instances, or cause conflicts there.<br>
50   * Magnolia's JCR export typically white-lists only <code>sv</code> and <code>xsi</code> namespaces.
51   *
52   * @see <a href="https://jira.magnolia-cms.com/browse/MAGNOLIA-2960">MAGNOLIA-2960</a>
53   * @see <a href="https://jira.magnolia-cms.com/browse/MAGNOLIA-7022">MAGNOLIA-7022</a>
54   */
55  public class NamespaceFilter extends XMLFilterImpl {
56      private final Set<String> whitelistedNamespaces;
57  
58      public NamespaceFilter(String... whitelistedNamespaces) {
59          this.whitelistedNamespaces = newHashSet(whitelistedNamespaces);
60      }
61  
62      private boolean inSkippedNs;
63  
64      @Override
65      public void startPrefixMapping(String prefix, String uri) throws SAXException {
66          if (whitelistedNamespaces.contains(prefix)) {
67              super.startPrefixMapping(prefix, uri);
68          } else {
69              inSkippedNs = true;
70          }
71      }
72  
73      @Override
74      public void endPrefixMapping(String prefix) throws SAXException {
75          if (!inSkippedNs) {
76              super.endPrefixMapping(prefix);
77          }
78          inSkippedNs = false;
79      }
80  
81      /**
82       * org.apache.jackrabbit.commons.xml.ToXmlContentHandler does not honour the prefix mapping
83       * thus exclusions need to be handled here.
84       */
85      @Override
86      public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
87          AttributesImpl filteredAttributes = new AttributesImpl();
88          for (int i = 0; i < attributes.getLength(); i++) {
89              String attUri = attributes.getURI(i);
90              String attLocalName = attributes.getLocalName(i);
91              if (!"http://www.w3.org/2000/xmlns/".equals(attUri) || whitelistedNamespaces.contains(attLocalName)) {
92                  filteredAttributes.addAttribute(attUri, attLocalName, attributes.getQName(i), attributes.getType(i), attributes.getValue(i));
93              }
94          }
95          super.startElement(uri, localName, qName, filteredAttributes);
96      }
97  }