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      1 /*
      2  *  Licensed to the Apache Software Foundation (ASF) under one or more
      3  *  contributor license agreements.  See the NOTICE file distributed with
      4  *  this work for additional information regarding copyright ownership.
      5  *  The ASF licenses this file to You under the Apache License, Version 2.0
      6  *  (the "License"); you may not use this file except in compliance with
      7  *  the License.  You may obtain a copy of the License at
      8  *
      9  *     http://www.apache.org/licenses/LICENSE-2.0
     10  *
     11  *  Unless required by applicable law or agreed to in writing, software
     12  *  distributed under the License is distributed on an "AS IS" BASIS,
     13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14  *  See the License for the specific language governing permissions and
     15  *  limitations under the License.
     16  */
     17 
     18 package javax.security.auth.callback;
     19 
     20 import java.io.Serializable;
     21 import java.util.Arrays;
     22 
     23 /**
     24  * Used in conjunction with a {@link CallbackHandler} to retrieve a password
     25  * when needed.
     26  */
     27 public class PasswordCallback implements Callback, Serializable {
     28 
     29     private static final long serialVersionUID = 2267422647454909926L;
     30 
     31     private String prompt;
     32 
     33     boolean echoOn;
     34 
     35     private char[] inputPassword;
     36 
     37     private void setPrompt(String prompt) throws IllegalArgumentException {
     38         if (prompt == null || prompt.length() == 0) {
     39             throw new IllegalArgumentException("Invalid prompt");
     40         }
     41         this.prompt = prompt;
     42     }
     43 
     44     /**
     45      * Creates a new {@code PasswordCallback} instance.
     46      *
     47      * @param prompt
     48      *            the message that should be displayed to the user
     49      * @param echoOn
     50      *            determines whether the user input should be echoed
     51      */
     52     public PasswordCallback(String prompt, boolean echoOn) {
     53         setPrompt(prompt);
     54         this.echoOn = echoOn;
     55     }
     56 
     57     /**
     58      * Returns the prompt that was specified when creating this {@code
     59      * PasswordCallback}
     60      *
     61      * @return the prompt
     62      */
     63     public String getPrompt() {
     64         return prompt;
     65     }
     66 
     67     /**
     68      * Queries whether this {@code PasswordCallback} expects user input to be
     69      * echoed, which is specified during the creation of the object.
     70      *
     71      * @return {@code true} if (and only if) user input should be echoed
     72      */
     73     public boolean isEchoOn() {
     74         return echoOn;
     75     }
     76 
     77     /**
     78      * Sets the password. The {@link CallbackHandler} that performs the actual
     79      * provisioning or input of the password needs to call this method to hand
     80      * back the password to the security service that requested it.
     81      *
     82      * @param password
     83      *            the password. A copy of this is stored, so subsequent changes
     84      *            to the input array do not affect the {@code PasswordCallback}.
     85      */
     86     public void setPassword(char[] password) {
     87         if (password == null) {
     88             this.inputPassword = password;
     89         } else {
     90             inputPassword = new char[password.length];
     91             System.arraycopy(password, 0, inputPassword, 0, inputPassword.length);
     92         }
     93     }
     94 
     95     /**
     96      * Returns the password. The security service that needs the password
     97      * usually calls this method once the {@link CallbackHandler} has finished
     98      * its work.
     99      *
    100      * @return the password. A copy of the internal password is created and
    101      *         returned, so subsequent changes to the internal password do not
    102      *         affect the result.
    103      */
    104     public char[] getPassword() {
    105         if (inputPassword != null) {
    106             char[] tmp = new char[inputPassword.length];
    107             System.arraycopy(inputPassword, 0, tmp, 0, tmp.length);
    108             return tmp;
    109         }
    110         return null;
    111     }
    112 
    113     /**
    114      * Clears the password stored in this {@code PasswordCallback}.
    115      */
    116     public void clearPassword() {
    117         if (inputPassword != null) {
    118             Arrays.fill(inputPassword, '\u0000');
    119         }
    120     }
    121 }
    122