libjava/classpath/gnu/javax/crypto/sasl/AuthInfo.java

   1 /* AuthInfo.java --
   2    Copyright (C) 2003, 2006 Free Software Foundation, Inc.
   3
   4 This file is a part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2 of the License, or (at
   9 your option) any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; if not, write to the Free Software
  18 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301
  19 USA
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version.  */
  37
  38
  39 package gnu.javax.crypto.sasl;
  40
  41 import gnu.java.security.Registry;
  42
  43 import java.util.ArrayList;
  44 import java.util.Iterator;
  45 import java.util.StringTokenizer;
  46
  47 /**
  48  * A static class for creating {@link IAuthInfoProvider} providers. It
  49  * transparently locates and uses any provider instances, based on the value
  50  * assigned to the System property with the key
  51  * <code>gnu.crypto.sasl.auth.info.provider.pkgs</code>. If more than one is
  52  * specified they SHOULD be separated with a vertical bar character. Please note
  53  * that the GNU provider is always added last to the list, disregarding whether
  54  * it was mentioned or not in the value of that property, or if it that property
  55  * was not defined.
  56  */
  57 public class AuthInfo
  58 {
  59
  60   // Constants and variables
  61   // -------------------------------------------------------------------------
  62
  63   private static final ArrayList factories = new ArrayList();
  64   static
  65     {
  66       IAuthInfoProviderFactory ours = new AuthInfoProviderFactory();
  67       // if SASL_AUTH_INFO_PROVIDER_PKGS is defined then parse it
  68       String clazz;
  69       String pkgs = System.getProperty(Registry.SASL_AUTH_INFO_PROVIDER_PKGS,
  70                                        null);
  71       if (pkgs != null)
  72         {
  73           for (StringTokenizer st = new StringTokenizer(pkgs, "|"); st.hasMoreTokens();)
  74             {
  75               clazz = st.nextToken();
  76               if (!"gnu.crypto.sasl".equals(clazz))
  77                 {
  78                   clazz += ".AuthInfoProviderFactory";
  79                   try
  80                     {
  81                       IAuthInfoProviderFactory factory = (IAuthInfoProviderFactory) Class.forName(
  82                                                                                                   clazz).newInstance();
  83                       factories.add(factory);
  84                     }
  85                   catch (ClassCastException ignored)
  86                     {
  87                     }
  88                   catch (ClassNotFoundException ignored)
  89                     {
  90                     }
  91                   catch (InstantiationException ignored)
  92                     {
  93                     }
  94                   catch (IllegalAccessException ignored)
  95                     {
  96                     }
  97                 }
  98             }
  99         }
 100       // always add ours last; unless it's already there
 101       if (!factories.contains(ours))
 102         {
 103           factories.add(ours);
 104         }
 105     }
 106
 107   // Constructor(s)
 108   // -------------------------------------------------------------------------
 109
 110   /** Trivial constructor to enforce Singleton pattern. */
 111   private AuthInfo()
 112   {
 113     super();
 114   }
 115
 116   // Class methods
 117   // -------------------------------------------------------------------------
 118
 119   /**
 120    * A convenience method to return the authentication information provider
 121    * for a designated SASL mechnanism. It goes through all the installed
 122    * provider factories, one at a time, and attempts to return a new instance
 123    * of the provider for the designated mechanism. It stops at the first
 124    * factory returning a non-null provider.
 125    *
 126    * @param mechanism the name of a SASL mechanism.
 127    * @return an implementation that provides {@link IAuthInfoProvider} for that
 128    * mechanism; or <code>null</code> if none found.
 129    */
 130   public static IAuthInfoProvider getProvider(String mechanism)
 131   {
 132     for (Iterator it = factories.iterator(); it.hasNext();)
 133       {
 134         IAuthInfoProviderFactory factory = (IAuthInfoProviderFactory) it.next();
 135         IAuthInfoProvider result = factory.getInstance(mechanism);
 136         if (result != null)
 137           {
 138             return result;
 139           }
 140       }
 141     return null;
 142   }
 143 }