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Diffstat (limited to 'libjava/javax/security/auth/callback/CallbackHandler.java')
| -rw-r--r-- | libjava/javax/security/auth/callback/CallbackHandler.java | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/libjava/javax/security/auth/callback/CallbackHandler.java b/libjava/javax/security/auth/callback/CallbackHandler.java new file mode 100644 index 0000000..289999c --- /dev/null +++ b/libjava/javax/security/auth/callback/CallbackHandler.java @@ -0,0 +1,156 @@ +/* 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> + * + * @version $Revision: 1.1 $ + */ +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; +} |