DNSLookup


1   package org.jacorb.orb.dns;
2   
3   /*
4    *        JacORB  - a free Java ORB
5    *
6    *   Copyright (C) 1997-2004 Gerald Brose.
7    *
8    *   This library is free software; you can redistribute it and/or
9    *   modify it under the terms of the GNU Library General Public
10   *   License as published by the Free Software Foundation; either
11   *   version 2 of the License, or (at your option) any later version.
12   *
13   *   This library is distributed in the hope that it will be useful,
14   *   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
16   *   Library General Public License for more details.
17   *
18   *   You should have received a copy of the GNU Library General Public
19   *   License along with this library; if not, write to the Free
20   *   Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21   */
22  
23  import java.net.InetAddress  ;
24  
25  import org.jacorb.util.ObjectUtil;
26  
27  import org.apache.avalon.framework.configuration.*;
28  import org.apache.avalon.framework.logger.Logger;
29  
30  public class DNSLookup  
31      implements Configurable
32  {
33      private  DNSLookupDelegate delegate = null;
34      private  boolean enabled = false;
35  
36      public void configure(Configuration configuration)
37          throws ConfigurationException
38      {        
39          enabled = configuration.getAttribute("jacorb.dns.enable","off").equals("on");
40          if (enabled)
41          {
42              delegate = 
43                  new JdkDelegateImpl(((org.jacorb.config.Configuration)configuration).getNamedLogger("org.jacorb.dns"));
44          }
45      }
46  
47      /**
48       * Returns true if this is a post-1.4 DNS implementation.
49       */
50      private static boolean jdk_DNS_Usable()
51      {
52          try
53          {
54              java.lang.reflect.Method   m = java.net.InetAddress  .class.getMethod
55              (
56                  "getCanonicalHostName",
57                  new Class  [] {}
58              );
59              return m != null;
60          }
61          catch (NoSuchMethodException   ex)
62          {
63              return false;
64          }
65      }
66  
67      public String   inverseLookup(String   ip)
68      {
69          return ((delegate == null) ? null : delegate.inverseLookup(ip));
70      }
71  
72      public String   inverseLookup(InetAddress   addr)
73      {
74          return ((delegate == null) ? null : delegate.inverseLookup(addr));
75      }
76              
77  } // DNSLookup
78
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