/*

 * Copyright (c) 2000, 2011, 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.

 */

/*

 *

 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.

 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.

 */

package sun.security.krb5;

import java.io.File;

import java.io.FileInputStream;

import java.util.Hashtable;

import java.util.Vector;

import java.util.ArrayList;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.io.IOException;

import java.util.Enumeration;

import java.util.StringTokenizer;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.util.List;

import sun.net.dns.ResolverConfiguration;

import sun.security.krb5.internal.crypto.EType;

import sun.security.krb5.internal.Krb5;

/**

 * This class maintains key-value pairs of Kerberos configurable constants

 * from configuration file or from user specified system properties.

 */

public class Config {

    /*

     * Only allow a single instance of Config.

     */

    private static Config singleton = null;

    /*

     * Hashtable used to store configuration infomation.

     */

    private Hashtable<String,Object> stanzaTable;

    private static boolean DEBUG = sun.security.krb5.internal.Krb5.DEBUG;

    // these are used for hexdecimal calculation.

    private static final int BASE16_0 = 1;

    private static final int BASE16_1 = 16;

    private static final int BASE16_2 = 16 * 16;

    private static final int BASE16_3 = 16 * 16 * 16;

    /**

     * Specified by system properties. Must be both null or non-null.

     */

    private final String defaultRealm;

    private final String defaultKDC;

    // used for native interface

    private static native String getWindowsDirectory(boolean isSystem);

    /**

     * Gets an instance of Config class. One and only one instance (the

     * singleton) is returned.

     *

     * @exception KrbException if error occurs when constructing a Config

     * instance. Possible causes would be either of java.security.krb5.realm or

     * java.security.krb5.kdc not specified, error reading configuration file.

     */

    public static synchronized Config getInstance() throws KrbException {

        if (singleton == null) {

            singleton = new Config();

        }

        return singleton;

    }

    /**

     * Refresh and reload the Configuration. This could involve,

     * for example reading the Configuration file again or getting

     * the java.security.krb5.* system properties again.

     *

     * @exception KrbException if error occurs when constructing a Config

     * instance. Possible causes would be either of java.security.krb5.realm or

     * java.security.krb5.kdc not specified, error reading configuration file.

     */

    public static synchronized void refresh() throws KrbException {

        singleton = new Config();

        KdcComm.initStatic();

    }

    /**

     * Private constructor - can not be instantiated externally.

     */

    private Config() throws KrbException {

        /*

         * If either one system property is specified, we throw exception.

         */

        String tmp =

            java.security.AccessController.doPrivileged(

                new sun.security.action.GetPropertyAction

                    ("java.security.krb5.kdc"));

        if (tmp != null) {

            // The user can specify a list of kdc hosts separated by ":"

            defaultKDC = tmp.replace(':', ' ');

        } else {

            defaultKDC = null;

        }

        defaultRealm =

            java.security.AccessController.doPrivileged(

                new sun.security.action.GetPropertyAction

                    ("java.security.krb5.realm"));

        if ((defaultKDC == null && defaultRealm != null) ||

            (defaultRealm == null && defaultKDC != null)) {

            throw new KrbException

                ("System property java.security.krb5.kdc and " +

                 "java.security.krb5.realm both must be set or " +

                 "neither must be set.");

        }

        // Always read the Kerberos configuration file

        try {

            Vector<String> configFile;

            configFile = loadConfigFile();

            stanzaTable = parseStanzaTable(configFile);

        } catch (IOException ioe) {

            // No krb5.conf, no problem. We'll use DNS or system property etc.

        }

    }

    /**

     * Gets the default int value for the specified name.

     * @param name the name.

     * @return the default Integer, null is returned if no such name and

     * value are found in configuration file, or error occurs when parsing

     * string to integer.

     */

    public int getDefaultIntValue(String name) {

        String result = null;

        int value = Integer.MIN_VALUE;

        result = getDefault(name);

        if (result != null) {

            try {

                value = parseIntValue(result);

            } catch (NumberFormatException e) {

                if (DEBUG) {

                    System.out.println("Exception in getting value of " +

                                       name + " " +

                                       e.getMessage());

                    System.out.println("Setting " + name +

                                       " to minimum value");

                }

                value = Integer.MIN_VALUE;

            }

        }

        return value;

    }

    /**

     * Gets the default int value for the specified name in the specified

     * section. <br>This method is quicker by using section name as the

     * search key.

     * @param name the name.

     * @param sectio the name string of the section.

     * @return the default Integer, null is returned if no such name and

     * value are found in configuration file, or error occurs when parsing

     * string to integer.

     */

    public int getDefaultIntValue(String name, String section) {

        String result = null;

        int value = Integer.MIN_VALUE;

        result = getDefault(name, section);

        if (result != null) {

            try {

                value = parseIntValue(result);

            } catch (NumberFormatException e) {

                if (DEBUG) {

                    System.out.println("Exception in getting value of " +

                                       name +" in section " +

                                       section + " "  + e.getMessage());

                    System.out.println("Setting " + name +

                                       " to minimum value");

                }

                value = Integer.MIN_VALUE;

            }

        }

        return value;

    }

    /**

     * Gets the default string value for the specified name.

     * @param name the name.

     * @return the default value, null is returned if it cannot be found.

     */

    public String getDefault(String name) {

        if (stanzaTable == null) {

            return null;

        } else {

            return getDefault(name, stanzaTable);

        }

    }

    /**

     * This method does the real job to recursively search through the

     * stanzaTable.

     * @param k the key string.

     * @param t stanzaTable or sub hashtable within it.

     * @return the value found in config file, returns null if no value

     * matched with the key is found.

     */

        String result = null;

        String key;

        if (stanzaTable != null) {

                Object ob = t.get(key);

                if (ob instanceof Hashtable) {

                    if (result != null) {

                        return result;

                    }

                } else if (key.equalsIgnoreCase(k)) {

                    if (ob instanceof String) {

                        return (String)(t.get(key));

                    } else if (ob instanceof Vector) {

                        result = "";

                        int length = ((Vector)ob).size();

                        for (int i = 0; i < length; i++) {

                            if (i == length -1) {

                                result +=

                                    (String)(((Vector)ob).elementAt(i));

                            } else {

                                result +=

                                    (String)(((Vector)ob).elementAt(i)) + " ";

                            }

                        }

                        return result;

                    }

                }

            }

        }

        return result;

    }

    /**

     * Gets the default string value for the specified name in the

     * specified section.

     * <br>This method is quicker by using the section name as the search key.

     * @param name the name.

     * @param section the name of the section.

     * @return the default value, null is returned if it cannot be found.

     */

    public String getDefault(String name, String section) {

        String stanzaName;

        String result = null;

        if (stanzaTable != null) {

                if (stanzaName.equalsIgnoreCase(section)) {

                    if (subTable.containsKey(name)) {

                        return (String)(subTable.get(name));

                    }

                } else if (subTable.containsKey(section)) {

                    Object ob = subTable.get(section);

                    if (ob instanceof Hashtable) {

                        if (temp.containsKey(name)) {

                            Object object = temp.get(name);

                            if (object instanceof Vector) {

                                result = "";

                                int length = ((Vector)object).size();

                                for (int i = 0; i < length; i++) {

                                    if (i == length - 1)  {

                                        result +=

                                        (String)(((Vector)object).elementAt(i));

                                    } else {

                                        result +=

                                        (String)(((Vector)object).elementAt(i))

                                                + " ";

                                    }

                                }

                            } else {

                                result = (String)object;

                            }

                        }

                    }

                }

            }

        }

        return result;

    }

    /**

     * Gets the default boolean value for the specified name.

     * @param name the name.

     * @return the default boolean value, false is returned if it cannot be

     * found.

     */

    public boolean getDefaultBooleanValue(String name) {

        String val = null;

        if (stanzaTable == null) {

            val = null;

        } else {

            val = getDefault(name, stanzaTable);

        }

        if (val != null && val.equalsIgnoreCase("true")) {

            return true;

        } else {

            return false;

        }

    }

    /**

     * Gets the default boolean value for the specified name in the

     * specified section.

     * <br>This method is quicker by using the section name as the search key.

     * @param name the name.

     * @param section the name of the section.

     * @return the default boolean value, false is returned if it cannot be

     * found.

     */

    public boolean getDefaultBooleanValue(String name, String section) {

        String val = getDefault(name, section);

        if (val != null && val.equalsIgnoreCase("true")) {

            return true;

        } else {

            return false;

        }

    }

    /**

     * Parses a string to an integer. The convertible strings include the

     * string representations of positive integers, negative integers, and

     * hex decimal integers.  Valid inputs are, e.g., -1234, +1234,

     * 0x40000.

     *

     * @param input the String to be converted to an Integer.

     * @return an numeric value represented by the string

     * @exception NumberFormationException if the String does not contain a

     * parsable integer.

     */

    private int parseIntValue(String input) throws NumberFormatException {

        int value = 0;

        if (input.startsWith("+")) {

            String temp = input.substring(1);

            return Integer.parseInt(temp);

        } else if (input.startsWith("0x")) {

            String temp = input.substring(2);

            char[] chars = temp.toCharArray();

            if (chars.length > 8) {

                throw new NumberFormatException();

            } else {

                for (int i = 0; i < chars.length; i++) {

                    int index = chars.length - i - 1;

                    switch (chars[i]) {

                    case '0':

                        value += 0;

                        break;

                    case '1':

                        value += 1 * getBase(index);

                        break;

                    case '2':

                        value += 2 * getBase(index);

                        break;

                    case '3':

                        value += 3 * getBase(index);

                        break;

                    case '4':

                        value += 4 * getBase(index);

                        break;

                    case '5':

                        value += 5 * getBase(index);

                        break;

                    case '6':

                        value += 6 * getBase(index);

                        break;

                    case '7':

                        value += 7 * getBase(index);

                        break;

                    case '8':

                        value += 8 * getBase(index);

                        break;

                    case '9':

                        value += 9 * getBase(index);

                        break;

                    case 'a':

                    case 'A':

                        value += 10 * getBase(index);

                        break;

                    case 'b':

                    case 'B':

                        value += 11 * getBase(index);

                        break;

                    case 'c':

                    case 'C':

                        value += 12 * getBase(index);

                        break;

                    case 'd':

                    case 'D':

                        value += 13 * getBase(index);

                        break;

                    case 'e':

                    case 'E':

                        value += 14 * getBase(index);

                        break;

                    case 'f':

                    case 'F':

                        value += 15 * getBase(index);

                        break;

                    default:

                        throw new NumberFormatException("Invalid numerical format");

                    }

                }

            }

            if (value < 0) {

                throw new NumberFormatException("Data overflow.");

            }

        } else {

            value = Integer.parseInt(input);

        }

        return value;

    }

    private int getBase(int i) {

        int result = 16;

        switch (i) {

        case 0:

            result = BASE16_0;

            break;

        case 1:

            result = BASE16_1;

            break;

        case 2:

            result = BASE16_2;

            break;

        case 3:

            result = BASE16_3;

            break;

        default:

            for (int j = 1; j < i; j++) {

                result *= 16;

            }

        }

        return result;

    }

    /**

     * Finds the matching value in the hashtable.

     */

    private String find(String key1, String key2) {

        String result;

        if ((stanzaTable != null) &&

            ((result = (String)

                (((Hashtable)(stanzaTable.get(key1))).get(key2))) != null)) {

            return result;

        } else {

            return "";

        }

    }

    /**

     * Reads name/value pairs to the memory from the configuration

     * file. The default location of the configuration file is in java home

     * directory.

     *

     * Configuration file contains information about the default realm,

     * ticket parameters, location of the KDC and the admin server for

     * known realms, etc. The file is divided into sections. Each section

     * contains one or more name/value pairs with one pair per line. A

     * typical file would be:

     * [libdefaults]

     *          default_realm = EXAMPLE.COM

     *          default_tgs_enctypes = des-cbc-md5

     *          default_tkt_enctypes = des-cbc-md5

     * [realms]

     *          EXAMPLE.COM = {

     *                  kdc = kerberos.example.com

     *                  kdc = kerberos-1.example.com

     *                  admin_server = kerberos.example.com

     *                  }

     *          SAMPLE_COM = {

     *                  kdc = orange.sample.com

     *                  admin_server = orange.sample.com

     *                  }