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/* * Copyright (c) 2009, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package sun.security.ssl; import java.security.AccessControlContext;import java.security.AccessController;import java.security.Permission;import java.security.Principal;import java.security.PrivilegedAction;import javax.crypto.SecretKey;import javax.security.auth.Subject;import javax.security.auth.login.LoginException; /** * A helper class for Kerberos APIs. */public final class Krb5Helper {     private Krb5Helper() { }     // loads Krb5Proxy implementation class if available    private static final String IMPL_CLASS =        "sun.security.ssl.krb5.Krb5ProxyImpl";     private static final Krb5Proxy proxy =        AccessController.doPrivileged(new PrivilegedAction<Krb5Proxy>() {            public Krb5Proxy run() {                try {                    Class<?> c = Class.forName(IMPL_CLASS, true, null);                    return (Krb5Proxy)c.newInstance();                } catch (ClassNotFoundException cnf) {                    return null;                } catch (InstantiationException e) {                    throw new AssertionError(e);                } catch (IllegalAccessException e) {                    throw new AssertionError(e);                }            }});     /**     * Returns true if Kerberos is available.     */    public static boolean isAvailable() {        return proxy != null;    }     private static void ensureAvailable() {        if (proxy == null)            throw new AssertionError("Kerberos should have been available");    }     /**     * Returns the Subject associated with client-side of the SSL socket.     */    public static Subject getClientSubject(AccessControlContext acc)            throws LoginException {        ensureAvailable();        return proxy.getClientSubject(acc);    }     /**     * Returns the Subject associated with server-side of the SSL socket.     */    public static Subject getServerSubject(AccessControlContext acc)            throws LoginException {        ensureAvailable();        return proxy.getServerSubject(acc);    }     /**     * Returns the KerberosKeys for the default server-side principal.     */    public static SecretKey[] getServerKeys(AccessControlContext acc)            throws LoginException {        ensureAvailable();        return proxy.getServerKeys(acc);    }     /**     * Returns the server-side principal name associated with the KerberosKey.     */    public static String getServerPrincipalName(SecretKey kerberosKey) {        ensureAvailable();        return proxy.getServerPrincipalName(kerberosKey);    }     /**     * Returns the hostname embedded in the principal name.     */    public static String getPrincipalHostName(Principal principal) {        ensureAvailable();        return proxy.getPrincipalHostName(principal);    }     /**     * Returns a ServicePermission for the principal name and action.     */    public static Permission getServicePermission(String principalName,            String action) {        ensureAvailable();        return proxy.getServicePermission(principalName, action);    }}