/*

 * Copyright (c) 2008, 2013, 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.

 *

 * 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.

 */

import java.io.File;

import java.io.FileOutputStream;

import java.io.IOException;

import java.security.Security;

import javax.security.auth.callback.Callback;

import javax.security.auth.callback.CallbackHandler;

import javax.security.auth.callback.NameCallback;

import javax.security.auth.callback.PasswordCallback;

import sun.security.krb5.Config;

/**

 * This class starts a simple KDC with one realm, several typical principal

 * names, generates delete-on-exit krb5.conf and keytab files, and setup

 * system properties for them. There's also a helper method to generate a

 * JAAS login config file that can be used for JAAS or JGSS apps.

 * <p>

 * Just call this line to start everything:

 * <pre>

 * new OneKDC(null).writeJaasConf();

 * </pre>

 */

public class OneKDC extends KDC {

    public static final String USER = "dummy";

    public static final char[] PASS = "bogus".toCharArray();

    public static final String USER2 = "foo";

    public static final char[] PASS2 = "bar".toCharArray();

    public static final String KRB5_CONF = "localkdc-krb5.conf";

    public static final String KTAB = "localkdc.ktab";

    public static final String JAAS_CONF = "localkdc-jaas.conf";

    public static final String REALM = "RABBIT.HOLE";

    public static String SERVER = "server/host." + REALM.toLowerCase();

    public static String BACKEND = "backend/host." + REALM.toLowerCase();

    public static String KDCHOST = "kdc." + REALM.toLowerCase();

    /**

     * Creates the KDC and starts it.

     * @param etype Encryption type, null if not specified

     * @throws java.lang.Exception if there's anything wrong

     */

    public OneKDC(String etype) throws Exception {

        super(REALM, KDCHOST, 0, true);

        addPrincipal(USER, PASS);

        addPrincipal(USER2, PASS2);

        addPrincipalRandKey("krbtgt/" + REALM);

        addPrincipalRandKey(SERVER);

        addPrincipalRandKey(BACKEND);

        String extraConfig = "";

        if (etype != null) {

            extraConfig += "default_tkt_enctypes=" + etype

                    + "\ndefault_tgs_enctypes=" + etype;

            if (etype.startsWith("des")) {

                extraConfig += "\nallow_weak_crypto = true";

            }

        }

        KDC.saveConfig(KRB5_CONF, this,

                "forwardable = true",

                "default_keytab_name = " + KTAB,

                extraConfig);

        System.setProperty("java.security.krb5.conf", KRB5_CONF);

        // Whatever krb5.conf had been loaded before, we reload ours now.

        Config.refresh();

        writeKtab(KTAB);

        Security.setProperty("auth.login.defaultCallbackHandler",

                "OneKDC$CallbackForClient");

    }

    /**

     * Writes a JAAS login config file, which contains as many as useful

     * entries, including JGSS style initiator/acceptor and normal JAAS

     * entries with names using existing OneKDC principals.

     * @throws java.lang.Exception if anything goes wrong

     */

    public void writeJAASConf() throws IOException {

        System.setProperty("java.security.auth.login.config", JAAS_CONF);

        File f = new File(JAAS_CONF);

        FileOutputStream fos = new FileOutputStream(f);

        fos.write((

                "com.sun.security.jgss.krb5.initiate {\n" +

                "    com.sun.security.auth.module.Krb5LoginModule required;\n};\n" +

                "com.sun.security.jgss.krb5.accept {\n" +

                "    com.sun.security.auth.module.Krb5LoginModule required\n" +

                "    principal=\"*\"\n" +

                "    useKeyTab=true\n" +

                "    isInitiator=false\n" +

                "    storeKey=true;\n};\n" +

                "client {\n" +

                "    com.sun.security.auth.module.Krb5LoginModule required;\n};\n" +

                "server {\n" +

                "    com.sun.security.auth.module.Krb5LoginModule required\n" +

                "    principal=\"" + SERVER + "\"\n" +

                "    useKeyTab=true\n" +

                "    storeKey=true;\n};\n" +

                "backend {\n" +

                "    com.sun.security.auth.module.Krb5LoginModule required\n" +

                "    principal=\"" + BACKEND + "\"\n" +

                "    useKeyTab=true\n" +

                "    storeKey=true\n" +

                "    isInitiator=false;\n};\n"

                ).getBytes());

        fos.close();

    }

    /**

     * The default callback handler for JAAS login. Note that this handler is

     * hard coded to provide only info for USER1. If you need to provide info

     * for another principal, please use Context.fromUserPass() instead.

     */

    public static class CallbackForClient implements CallbackHandler {

        public void handle(Callback[] callbacks) {

            String user = OneKDC.USER;

            char[] pass = OneKDC.PASS;

            for (Callback callback : callbacks) {

                if (callback instanceof NameCallback) {

                    System.out.println("Callback for name: " + user);

                    ((NameCallback) callback).setName(user);

                }

                if (callback instanceof PasswordCallback) {

                    System.out.println("Callback for pass: "

                            + new String(pass));

                    ((PasswordCallback) callback).setPassword(pass);

                }

            }

        }

    }

}