001    /* PasswordCallback.java -- callback for passwords.
002       Copyright (C) 2003, Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    
039    package javax.security.auth.callback;
040    
041    import java.io.Serializable;
042    
043    /**
044     * Underlying security services instantiate and pass a <code>PasswordCallback</code>
045     * to the <code>handle()</code> method of a {@link CallbackHandler} to retrieve
046     * password information.
047     *
048     * @see CallbackHandler,
049     */
050    public class PasswordCallback implements Callback, Serializable
051    {
052    
053      // Constants and variables
054      // -------------------------------------------------------------------------
055    
056      /**
057       * @serial
058       * @since 1.4
059       */
060      private String prompt;
061    
062      /**
063       * @serial
064       * @since 1.4
065       */
066      private boolean echoOn;
067    
068      /**
069       * @serial
070       * @since 1.4
071       */
072      private char[] inputPassword;
073    
074      // Constructor(s)
075      // -------------------------------------------------------------------------
076    
077      /**
078       * Construct a <code>PasswordCallback</code> with a prompt and a boolean
079       * specifying whether the password should be displayed as it is being typed.
080       *
081       * @param prompt the prompt used to request the password.
082       * @param echoOn <code>true</code> if the password should be displayed as it
083       * is being typed.
084       * @throws IllegalArgumentException if <code>prompt</code> is <code>null</code>
085       * or if <code>prompt</code> has a length of <code>0</code>.
086       */
087      public PasswordCallback(String prompt, boolean echoOn)
088      {
089        super();
090    
091        setPrompt(prompt);
092        this.echoOn = echoOn;
093      }
094    
095      // Class methods
096      // -------------------------------------------------------------------------
097    
098      // Instance methods
099      // -------------------------------------------------------------------------
100    
101      /**
102       * Get the prompt.
103       *
104       * @return the prompt.
105       */
106      public String getPrompt()
107      {
108        return prompt;
109      }
110    
111      /**
112       * Return whether the password should be displayed as it is being typed.
113       *
114       * @return the whether the password should be displayed as it is being typed.
115       */
116      public boolean isEchoOn()
117      {
118        return echoOn;
119      }
120    
121      /**
122       * <p>Set the retrieved password.</p>
123       *
124       * <p>This method makes a copy of the input password before storing it.</p>
125       *
126       * @param password the retrieved password, which may be <code>null</code>.
127       * @see #getPassword()
128       */
129      public void setPassword(char[] password)
130      {
131        inputPassword = (password == null ? null : (char[]) password.clone());
132      }
133    
134      /**
135       * <p>Get the retrieved password.</p>
136       *
137       * <p>This method returns a copy of the retrieved password.</p>
138       *
139       * @return the retrieved password, which may be <code>null</code>.
140       * @see #setPassword(char[])
141       */
142      public char[] getPassword()
143      {
144        return (inputPassword == null ? null : (char[]) inputPassword.clone());
145      }
146    
147      /** Clear the retrieved password. */
148      public void clearPassword()
149      {
150        if (inputPassword != null)
151          {
152            for (int i = 0; i < inputPassword.length; i++)
153              {
154                inputPassword[i] = '\0';
155              }
156            inputPassword = null;
157          }
158      }
159    
160      private void setPrompt(String prompt) throws IllegalArgumentException
161      {
162        if ((prompt == null) || (prompt.length() == 0))
163          {
164            throw new IllegalArgumentException("invalid prompt");
165          }
166        this.prompt = prompt;
167      }
168    }