/*

 * Copyright (c) 2000, 2009, 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 sun.security.krb5.internal.Krb5;

import sun.security.util.*;

import java.io.IOException;

import java.util.StringTokenizer;

import java.util.Vector;

import java.util.Stack;

import java.util.EmptyStackException;

import sun.security.krb5.internal.util.KerberosString;

/**

 * Implements the ASN.1 Realm type.

 *

 * <xmp>

 * Realm ::= GeneralString

 * </xmp>

 */

public class Realm implements Cloneable {

    private String realm;

    private static boolean DEBUG = Krb5.DEBUG;

    private Realm() {

    }

    public Realm(String name) throws RealmException {

        realm = parseRealm(name);

    }

    public Object clone() {

        Realm new_realm = new Realm();

        if (realm != null) {

            new_realm.realm = new String(realm);

        }

        return new_realm;

    }

    public boolean equals(Object obj) {

        if (this == obj) {

            return true;

        }

        if (!(obj instanceof Realm)) {

            return false;

        }

        Realm that = (Realm)obj;

        if (this.realm != null && that.realm != null ) {

            return this.realm.equals(that.realm);

        } else {

            return (this.realm == null && that.realm == null);

        }

    }

    public int hashCode() {

        int result = 17 ;

        if( realm != null ) {

            result = 37 * result + realm.hashCode();

        }

        return result;

    }

    /**

     * Constructs a Realm object.

     * @param encoding a Der-encoded data.

     * @exception Asn1Exception if an error occurs while decoding an ASN1 encoded data.

     * @exception IOException if an I/O error occurs while reading encoded data.

     * @exception RealmException if an error occurs while parsing a Realm object.

     */

    public Realm(DerValue encoding)

        throws Asn1Exception, RealmException, IOException {

        if (encoding == null) {

            throw new IllegalArgumentException("encoding can not be null");

        }

        realm = new KerberosString(encoding).toString();

        if (realm == null || realm.length() == 0)

            throw new RealmException(Krb5.REALM_NULL);

        if (!isValidRealmString(realm))

            throw new RealmException(Krb5.REALM_ILLCHAR);

    }

    public String toString() {

        return realm;

    }

    public static String parseRealmAtSeparator(String name)

        throws RealmException {

        if (name == null) {

            throw new IllegalArgumentException

                ("null input name is not allowed");

        }

        String temp = new String(name);

        String result = null;

        int i = 0;

        while (i < temp.length()) {

            if (temp.charAt(i) == PrincipalName.NAME_REALM_SEPARATOR) {

                if (i == 0 || temp.charAt(i - 1) != '\\') {

                    if (i + 1 < temp.length())

                        result = temp.substring(i + 1, temp.length());

                    break;

                }

            }

            i++;

        }

        if (result != null) {

            if (result.length() == 0)

                throw new RealmException(Krb5.REALM_NULL);

            if (!isValidRealmString(result))

                throw new RealmException(Krb5.REALM_ILLCHAR);

        }

        return result;

    }

    public static String parseRealmComponent(String name) {

        if (name == null) {

            throw new IllegalArgumentException

                ("null input name is not allowed");

        }

        String temp = new String(name);

        String result = null;

        int i = 0;

        while (i < temp.length()) {

            if (temp.charAt(i) == PrincipalName.REALM_COMPONENT_SEPARATOR) {

                if (i == 0 || temp.charAt(i - 1) != '\\') {

                    if (i + 1 < temp.length())

                        result = temp.substring(i + 1, temp.length());

                    break;

                }

            }

            i++;

        }

        return result;

    }

    protected static String parseRealm(String name) throws RealmException {

        String result = parseRealmAtSeparator(name);

        if (result == null)

            result = name;

        if (result == null || result.length() == 0)

            throw new RealmException(Krb5.REALM_NULL);

        if (!isValidRealmString(result))

            throw new RealmException(Krb5.REALM_ILLCHAR);

        return result;

    }

    // This is protected because the definition of a realm

    // string is fixed

    protected static boolean isValidRealmString(String name) {

        if (name == null)

            return false;

        if (name.length() == 0)

            return false;

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

            if (name.charAt(i) == '/' ||

                name.charAt(i) == ':' ||

                name.charAt(i) == '\0') {

                return false;

            }

        }

        return true;

    }

    /**

     * Encodes a Realm object.

     * @return the byte array of encoded KrbCredInfo object.

     * @exception Asn1Exception if an error occurs while decoding an ASN1 encoded data.

     * @exception IOException if an I/O error occurs while reading encoded data.

     *

     */

    public byte[] asn1Encode() throws Asn1Exception, IOException {

        DerOutputStream out = new DerOutputStream();

        out.putDerValue(new KerberosString(this.realm).toDerValue());

        return out.toByteArray();

    }

    /**

     * Parse (unmarshal) a realm from a DER input stream.  This form

     * parsing might be used when expanding a value which is part of

     * a constructed sequence and uses explicitly tagged type.

     *

     * @exception Asn1Exception on error.

     * @param data the Der input stream value, which contains one or more marshaled value.

     * @param explicitTag tag number.

     * @param optional indicate if this data field is optional

     * @return an instance of Realm.

     *

     */

    public static Realm parse(DerInputStream data, byte explicitTag, boolean optional) throws Asn1Exception, IOException, RealmException {

        if ((optional) && (((byte)data.peekByte() & (byte)0x1F) != explicitTag)) {

            return null;

        }

        DerValue der = data.getDerValue();

        if (explicitTag != (der.getTag() & (byte)0x1F))  {

            throw new Asn1Exception(Krb5.ASN1_BAD_ID);

        } else {

            DerValue subDer = der.getData().getDerValue();

            return new Realm(subDer);

        }

    }

    /*

     * First leg of realms parsing. Used by getRealmsList.

     */

    private static String[] doInitialParse(String cRealm, String sRealm)

        throws KrbException {

            if (cRealm == null || sRealm == null){

                throw new KrbException(Krb5.API_INVALID_ARG);

            }

            if (DEBUG) {

                System.out.println(">>> Realm doInitialParse: cRealm=["

                                   + cRealm + "], sRealm=[" +sRealm + "]");

            }

            if (cRealm.equals(sRealm)) {

                String[] retList = null;

                retList = new String[1];

                retList[0] = new String(cRealm);

                if (DEBUG) {

                    System.out.println(">>> Realm doInitialParse: "

                                       + retList[0]);

                }

                return retList;

            }

            return null;

        }

    /**

     * Returns an array of realms that may be traversed to obtain

     * a TGT from the initiating realm cRealm to the target realm

     * sRealm.

     * <br>

     * There may be an arbitrary number of intermediate realms

     * between cRealm and sRealm. The realms may be organized

     * organized hierarchically, or the paths between them may be

     * specified in the [capaths] stanza of the caller's

     * Kerberos configuration file. The configuration file is consulted

     * first. Then a hirarchical organization is assumed if no realms

     * are found in the configuration file.

     * <br>

     * The returned list, if not null, contains cRealm as the first

     * entry. sRealm is not included unless it is mistakenly listed

     * in the configuration file as an intermediary realm.

     *

     * @param cRealm the initiating realm

     * @param sRealm the target realm

     * @returns array of realms

     * @thows KrbException

     */

    public static String[] getRealmsList(String cRealm, String sRealm)

        throws KrbException {

            String[] retList = doInitialParse(cRealm, sRealm);

            if (retList != null && retList.length != 0) {

                return retList;

            }

            /*

             * Try [capaths].

             */

            retList = parseCapaths(cRealm, sRealm);

            if (retList != null && retList.length != 0) {

                return retList;

            }

            /*

             * Now assume the realms are organized hierarchically.

             */

            retList = parseHierarchy(cRealm, sRealm);

            return retList;

        }

    /**

     * Parses the [capaths] stanza of the configuration file

     * for a list of realms to traverse

     * to obtain credentials from the initiating realm cRealm to

     * the target realm sRealm.

     * @param cRealm the initiating realm

     * @param sRealm the target realm

     * @returns array of realms

     * @ throws KrbException

     */

    /*

     * parseCapaths works for a capaths organized such that

     * for a given client realm C there is a tag C that

     * contains subtags Ci ... Cn that completely define intermediate

     * realms from C to target T. For example:

     *

     * [capaths]

     *    TIVOLI.COM = {

     *        IBM.COM = IBM_LDAPCENTRAL.COM MOONLITE.ORG

     *        IBM_LDAPCENTRAL.COM = LDAPCENTRAL.NET

     *        LDAPCENTRAL.NET = .

     *    }

     *

     * The tag TIVOLI.COM contains subtags IBM.COM, IBM_LDAPCENTRAL.COM

     * and LDAPCENTRAL.NET that completely define the path from TIVOLI.COM

     * to IBM.COM (TIVOLI.COM->LADAPCENTRAL.NET->IBM_LDAPCENTRAL.COM->IBM

     * or TIVOLI.COM->MOONLITE.ORG->IBM.COM).

     *

     * A direct path is assumed for an intermediary whose entry is not

     * "closed" by a "." In the above example, TIVOLI.COM is assumed

     * to have a direct path to MOONLITE.ORG and MOONLITE.COM

     * in turn to IBM.COM.

     */

    private static String[] parseCapaths(String cRealm, String sRealm) throws KrbException {

        String[] retList = null;

        Config cfg = null;

        try {

            cfg = Config.getInstance();

        } catch (Exception exc) {

            if (DEBUG) {

                System.out.println ("Configuration information can not be " +

                                    "obtained " + exc.getMessage());

            }

            return null;

        }

        String intermediaries = cfg.getDefault(sRealm, cRealm);

        if (intermediaries == null) {

            if (DEBUG) {

                System.out.println(">>> Realm parseCapaths: no cfg entry");

            }

            return null;

        }

        String tempTarget = null, tempRealm = null;

        Stack<String> iStack = new Stack<String> ();

        /*

         * I don't expect any more than a handful of intermediaries.

         */

        Vector<String> tempList = new Vector<String> (8, 8);

        /*

         * The initiator at first location.

         */

        tempList.add(cRealm);

        int count = 0; // For debug only

        if (DEBUG) {

            tempTarget = sRealm;

        }

        out: do {

            if (DEBUG) {

                count++;

                System.out.println(">>> Realm parseCapaths: loop " +

                                   count + ": target=" + tempTarget);

            }

            if (intermediaries != null &&

                !intermediaries.equals(PrincipalName.REALM_COMPONENT_SEPARATOR_STR))

            {

                if (DEBUG) {

                    System.out.println(">>> Realm parseCapaths: loop " +

                                       count + ": intermediaries=[" +

                                       intermediaries + "]");

                }

                /*

                 * We have one or more space-separated intermediary realms.

                 * Stack them. A null is always added between intermedies of

                 * different targets. When this null is popped, it means none

                 * of the intermedies for this target is useful (because of

                 * infinite loop), the target is then removed from the partial

                 * tempList, and the next possible intermediary is tried.

                 */

                iStack.push(null);

                String[] ints = intermediaries.split("\\s+");

                for (int i = ints.length-1; i>=0; i--)

                {

                    tempRealm = ints[i];

                    if (tempRealm.equals(PrincipalName.REALM_COMPONENT_SEPARATOR_STR)) {

                        break out;

                    }

                    if (!tempList.contains(tempRealm)) {

                        iStack.push(tempRealm);

                        if (DEBUG) {

                            System.out.println(">>> Realm parseCapaths: loop " +

                                               count +

                                               ": pushed realm on to stack: " +

                                               tempRealm);

                        }

                    } else if (DEBUG) {

                        System.out.println(">>> Realm parseCapaths: loop " +

                                           count +

                                           ": ignoring realm: [" +

                                           tempRealm + "]");

                    }

                }

            } else {

                if (DEBUG) {

                    System.out.println(">>> Realm parseCapaths: loop " +

                                       count +

                                       ": no intermediaries");

                }

                break;

            }

            /*

             * Get next intermediary realm from the stack

             */

            try {

                while ((tempTarget = iStack.pop()) == null) {

                    tempList.removeElementAt(tempList.size()-1);

                    if (DEBUG) {

                        System.out.println(">>> Realm parseCapaths: backtrack, remove tail");

                    }

                }

            } catch (EmptyStackException exc) {

                tempTarget = null;

            }

            if (tempTarget == null) {

                /*

                 * No more intermediaries. We're done.

                 */

                break;

            }

            tempList.add(tempTarget);

            if (DEBUG) {

                System.out.println(">>> Realm parseCapaths: loop " + count +

                                   ": added intermediary to list: " +

                                   tempTarget);

            }

            intermediaries = cfg.getDefault(tempTarget, cRealm);

        } while (true);

        retList = new String[tempList.size()];

        try {

            retList = tempList.toArray(retList);

        } catch (ArrayStoreException exc) {

            retList = null;

        }

        if (DEBUG && retList != null) {

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

                System.out.println(">>> Realm parseCapaths [" + i +

                                   "]=" + retList[i]);

            }

        }

        return retList;

    }

    /**

     * Build a list of realm that can be traversed

     * to obtain credentials from the initiating realm cRealm

     * for a service in the target realm sRealm.

     * @param cRealm the initiating realm

     * @param sRealm the target realm

     * @returns array of realms

     * @throws KrbException

     */

    private static String[] parseHierarchy(String cRealm, String sRealm)

        throws KrbException

    {

        String[] retList = null;

        // Parse the components and determine common part, if any.

        String[] cComponents = null;

        String[] sComponents = null;

        StringTokenizer strTok =

        new StringTokenizer(cRealm,

                            PrincipalName.REALM_COMPONENT_SEPARATOR_STR);

        // Parse cRealm

        int cCount = strTok.countTokens();

        cComponents = new String[cCount];

        for (cCount = 0; strTok.hasMoreTokens(); cCount++) {

            cComponents[cCount] = strTok.nextToken();

        }

        if (DEBUG) {

            System.out.println(">>> Realm parseHierarchy: cRealm has " +

                               cCount + " components:");

            int j = 0;

            while (j < cCount) {

                System.out.println(">>> Realm parseHierarchy: " +

                                   "cComponents["+j+"]=" + cComponents[j++]);