Source for gnu.javax.crypto.sasl.AuthInfo

   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:   private static final ArrayList factories = new ArrayList();
  60:   static
  61:     {
  62:       IAuthInfoProviderFactory ours = new AuthInfoProviderFactory();
  63:       // if SASL_AUTH_INFO_PROVIDER_PKGS is defined then parse it
  64:       String clazz;
  65:       String pkgs = System.getProperty(Registry.SASL_AUTH_INFO_PROVIDER_PKGS,
  66:                                        null);
  67:       if (pkgs != null)
  68:         {
  69:           for (StringTokenizer st = new StringTokenizer(pkgs, "|"); st.hasMoreTokens();)
  70:             {
  71:               clazz = st.nextToken().trim();
  72:               if (! "gnu.javax.crypto.sasl".equals(clazz))
  73:                 {
  74:                   clazz += ".AuthInfoProviderFactory";
  75:                   try
  76:                     {
  77:                       IAuthInfoProviderFactory factory =
  78:                           (IAuthInfoProviderFactory) Class.forName(clazz).newInstance();
  79:                       factories.add(factory);
  80:                     }
  81:                   catch (ClassCastException ignored)
  82:                     {
  83:                     }
  84:                   catch (ClassNotFoundException ignored)
  85:                     {
  86:                     }
  87:                   catch (InstantiationException ignored)
  88:                     {
  89:                     }
  90:                   catch (IllegalAccessException ignored)
  91:                     {
  92:                     }
  93:                 }
  94:             }
  95:         }
  96:       // always add ours last; unless it's already there
  97:       if (!factories.contains(ours))
  98:         factories.add(ours);
  99:     }
 100: 
 101:   /** Trivial constructor to enforce Singleton pattern. */
 102:   private AuthInfo()
 103:   {
 104:     super();
 105:   }
 106: 
 107:   /**
 108:    * A convenience method to return the authentication information provider for
 109:    * a designated SASL mechnanism. It goes through all the installed provider
 110:    * factories, one at a time, and attempts to return a new instance of the
 111:    * provider for the designated mechanism. It stops at the first factory
 112:    * returning a non-null provider.
 113:    *
 114:    * @param mechanism the name of a SASL mechanism.
 115:    * @return an implementation that provides {@link IAuthInfoProvider} for that
 116:    *         mechanism; or <code>null</code> if none found.
 117:    */
 118:   public static IAuthInfoProvider getProvider(String mechanism)
 119:   {
 120:     for (Iterator it = factories.iterator(); it.hasNext();)
 121:       {
 122:         IAuthInfoProviderFactory factory = (IAuthInfoProviderFactory) it.next();
 123:         IAuthInfoProvider result = factory.getInstance(mechanism);
 124:         if (result != null)
 125:           return result;
 126:       }
 127:     return null;
 128:   }
 129: }