| /* CallbackHandler.java -- base interface for callback handlers. |
| Copyright (C) 2003, Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package javax.security.auth.callback; |
| |
| import java.io.IOException; |
| |
| /** |
| * <p>An application implements a <code>CallbackHandler</code> and passes it to |
| * underlying security services so that they may interact with the application |
| * to retrieve specific authentication data, such as usernames and passwords, or |
| * to display certain information, such as error and warning messages.</p> |
| * |
| * <p><code>CallbackHandler</code>s are implemented in an application-dependent |
| * fashion. For example, implementations for an application with a graphical |
| * user interface (GUI) may pop up windows to prompt for requested information |
| * or to display error messages. An implementation may also choose to obtain |
| * requested information from an alternate source without asking the end user.</p> |
| * |
| * <p>Underlying security services make requests for different types of |
| * information by passing individual Callbacks to the <code>CallbackHandler</code>. |
| * The <code>CallbackHandler</code> implementation decides how to retrieve and |
| * display information depending on the {@link Callback}s passed to it. For |
| * example, if the underlying service needs a username and password to |
| * authenticate a user, it uses a {@link NameCallback} and |
| * {@link PasswordCallback}. The <code>CallbackHandler</code> can then choose |
| * to prompt for a username and password serially, or to prompt for both in a |
| * single window.</p> |
| * |
| * <p>A default <code>CallbackHandler</code> class implementation may be |
| * specified in the <code>auth.login.defaultCallbackHandler</code> security |
| * property. The security property can be set in the Java security properties |
| * file located in the file named |
| * <code><JAVA_HOME>/lib/security/java.security</code>, where |
| * <code><JAVA_HOME></code> refers to the directory where the SDK was |
| * installed.</p> |
| * |
| * <p>If the security property is set to the fully qualified name of a |
| * <code>CallbackHandler</code> implementation class, then a |
| * <code>LoginContext</code>will load the specified <code>CallbackHandler</code> |
| * and pass it to the underlying <code>LoginModules</code>. The |
| * <code>LoginContext</code> only loads the default handler if one was not |
| * provided.</p> |
| * |
| * <p>All default handler implementations must provide a public zero-argument |
| * constructor.</p> |
| * |
| */ |
| public interface CallbackHandler |
| { |
| |
| /** |
| * <p>Retrieve or display the information requested in the provided |
| * {@link Callback}s.</p> |
| * |
| * <p>The <code>handle()</code> method implementation checks the instance(s) |
| * of the {@link Callback} object(s) passed in to retrieve or display the |
| * requested information. The following example is provided to help |
| * demonstrate what an <code>handle()</code> method implementation might look |
| * like. This example code is for guidance only. Many details, including |
| * proper error handling, are left out for simplicity.</p> |
| * |
| * <pre> |
| *public void handle(Callback[] callbacks) |
| *throws IOException, UnsupportedCallbackException { |
| * for (int i = 0; i < callbacks.length; i++) { |
| * if (callbacks[i] instanceof TextOutputCallback) { |
| * // display the message according to the specified type |
| * TextOutputCallback toc = (TextOutputCallback)callbacks[i]; |
| * switch (toc.getMessageType()) { |
| * case TextOutputCallback.INFORMATION: |
| * System.out.println(toc.getMessage()); |
| * break; |
| * case TextOutputCallback.ERROR: |
| * System.out.println("ERROR: " + toc.getMessage()); |
| * break; |
| * case TextOutputCallback.WARNING: |
| * System.out.println("WARNING: " + toc.getMessage()); |
| * break; |
| * default: |
| * throw new IOException("Unsupported message type: " |
| * + toc.getMessageType()); |
| * } |
| * } else if (callbacks[i] instanceof NameCallback) { |
| * // prompt the user for a username |
| * NameCallback nc = (NameCallback)callbacks[i]; |
| * // ignore the provided defaultName |
| * System.err.print(nc.getPrompt()); |
| * System.err.flush(); |
| * nc.setName((new BufferedReader( |
| * new InputStreamReader(System.in))).readLine()); |
| * } else if (callbacks[i] instanceof PasswordCallback) { |
| * // prompt the user for sensitive information |
| * PasswordCallback pc = (PasswordCallback)callbacks[i]; |
| * System.err.print(pc.getPrompt()); |
| * System.err.flush(); |
| * pc.setPassword(readPassword(System.in)); |
| * } else { |
| * throw new UnsupportedCallbackException( |
| * callbacks[i], "Unrecognized Callback"); |
| * } |
| * } |
| *} |
| * |
| * // Reads user password from given input stream. |
| *private char[] readPassword(InputStream in) throws IOException { |
| * // insert code to read a user password from the input stream |
| *} |
| * </pre> |
| * |
| * @param callbacks an array of {@link Callback} objects provided by an |
| * underlying security service which contains the information requested to |
| * be retrieved or displayed. |
| * @throws IOException if an input or output error occurs. |
| * @throws UnsupportedCallbackException if the implementation of this method |
| * does not support one or more of the Callbacks specified in the |
| * <code>callbacks</code> parameter. |
| */ |
| void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException; |
| } |
