/*
 * 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
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 *
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 * 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,
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/*
 *
 *  (C) Copyright IBM Corp. 1999 All Rights Reserved.
 *  Copyright 1997 The Open Group Research Institute.  All rights reserved.
 */

package sun.security.krb5.internal;

import sun.security.krb5.Asn1Exception;
import sun.security.krb5.Config;
import sun.security.krb5.KrbException;
import sun.security.util.DerInputStream;
import sun.security.util.DerOutputStream;
import sun.security.util.DerValue;

import java.io.IOException;
import java.util.Calendar;
import java.util.Date;
import java.util.TimeZone;

Implements the ASN.1 KerberosTime type. This is an immutable class.

KerberosTime    ::= GeneralizedTime -- with no fractional seconds

The timestamps used in Kerberos are encoded as GeneralizedTimes. A
KerberosTime value shall not include any fractional portions of the
seconds.  As required by the DER, it further shall not include any
separators, and it shall specify the UTC time zone (Z).

This definition reflects the Network Working Group RFC 4120
specification available at

http://www.ietf.org/rfc/rfc4120.txt.
The implementation also includes the microseconds info so that the
same class can be used as a precise timestamp in Authenticator etc.
/**
 * Implements the ASN.1 KerberosTime type. This is an immutable class.
 *
 * <xmp>
 * KerberosTime    ::= GeneralizedTime -- with no fractional seconds
 * </xmp>
 *
 * The timestamps used in Kerberos are encoded as GeneralizedTimes. A
 * KerberosTime value shall not include any fractional portions of the
 * seconds.  As required by the DER, it further shall not include any
 * separators, and it shall specify the UTC time zone (Z).
 *
 * <p>
 * This definition reflects the Network Working Group RFC 4120
 * specification available at
 * <a href="http://www.ietf.org/rfc/rfc4120.txt">
 * http://www.ietf.org/rfc/rfc4120.txt</a>.
 *
 * The implementation also includes the microseconds info so that the
 * same class can be used as a precise timestamp in Authenticator etc.
 */

public class KerberosTime {

    private final long kerberosTime; // milliseconds since epoch, Date.getTime()
    private final int  microSeconds; // last 3 digits of the real microsecond

    // The time when this class is loaded. Used in setNow()
    private static long initMilli = System.currentTimeMillis();
    private static long initMicro = System.nanoTime() / 1000;

    private static boolean DEBUG = Krb5.DEBUG;

    // Do not make this public. It's a little confusing that micro
    // is only the last 3 digits of microsecond.
    private KerberosTime(long time, int micro) {
        kerberosTime = time;
        microSeconds = micro;
    }

    
Creates a KerberosTime object from milliseconds since epoch.
/**
     * Creates a KerberosTime object from milliseconds since epoch.
     */
    public KerberosTime(long time) {
        this(time, 0);
    }

    // This constructor is used in the native code
    // src/windows/native/sun/security/krb5/NativeCreds.c
    public KerberosTime(String time) throws Asn1Exception {
        this(toKerberosTime(time), 0);
    }

    private static long toKerberosTime(String time) throws Asn1Exception {
        // ASN.1 GeneralizedTime format:

        // "19700101000000Z"
        //  |   | | | | | |
        //  0   4 6 8 | | |
        //           10 | |
        //             12 |
        //               14

        if (time.length() != 15)
            throw new Asn1Exception(Krb5.ASN1_BAD_TIMEFORMAT);
        if (time.charAt(14) != 'Z')
            throw new Asn1Exception(Krb5.ASN1_BAD_TIMEFORMAT);
        int year = Integer.parseInt(time.substring(0, 4));
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
        calendar.clear(); // so that millisecond is zero
        calendar.set(year,
                     Integer.parseInt(time.substring(4, 6)) - 1,
                     Integer.parseInt(time.substring(6, 8)),
                     Integer.parseInt(time.substring(8, 10)),
                     Integer.parseInt(time.substring(10, 12)),
                     Integer.parseInt(time.substring(12, 14)));
        return calendar.getTimeInMillis();
    }

    
Creates a KerberosTime object from a Date object.
/**
     * Creates a KerberosTime object from a Date object.
     */
    public KerberosTime(Date time) {
        this(time.getTime(), 0);
    }

    
Creates a KerberosTime object for now. It uses System.nanoTime()
to get a more precise time than "new Date()".
/**
     * Creates a KerberosTime object for now. It uses System.nanoTime()
     * to get a more precise time than "new Date()".
     */
    public static KerberosTime now() {
        long newMilli = System.currentTimeMillis();
        long newMicro = System.nanoTime() / 1000;
        long microElapsed = newMicro - initMicro;
        long calcMilli = initMilli + microElapsed/1000;
        if (calcMilli - newMilli > 100 || newMilli - calcMilli > 100) {
            if (DEBUG) {
                System.out.println("System time adjusted");
            }
            initMilli = newMilli;
            initMicro = newMicro;
            return new KerberosTime(newMilli, 0);
        } else {
            return new KerberosTime(calcMilli, (int)(microElapsed % 1000));
        }
    }

    
Returns a string representation of KerberosTime object.
Returns:
a string representation of this object./**
     * Returns a string representation of KerberosTime object.
     * @return a string representation of this object.
     */
    public String toGeneralizedTimeString() {
        Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
        calendar.clear();

        calendar.setTimeInMillis(kerberosTime);
        return String.format("%04d%02d%02d%02d%02d%02dZ",
                calendar.get(Calendar.YEAR),
                calendar.get(Calendar.MONTH) + 1,
                calendar.get(Calendar.DAY_OF_MONTH),
                calendar.get(Calendar.HOUR_OF_DAY),
                calendar.get(Calendar.MINUTE),
                calendar.get(Calendar.SECOND));
    }

    
Encodes this object to a byte array.
Throws:
Asn1Exception – if an error occurs while decoding an ASN1 encoded data.
IOException – if an I/O error occurs while reading encoded data.
Returns:
a byte array of encoded data./**
     * Encodes this object to a byte array.
     * @return a byte array of 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.
     */
    public byte[] asn1Encode() throws Asn1Exception, IOException {
        DerOutputStream out = new DerOutputStream();
        out.putGeneralizedTime(this.toDate());
        return out.toByteArray();
    }

    public long getTime() {
        return kerberosTime;
    }

    public Date toDate() {
        return new Date(kerberosTime);
    }

    public int getMicroSeconds() {
        Long temp_long = new Long((kerberosTime % 1000L) * 1000L);
        return temp_long.intValue() + microSeconds;
    }

    
Returns a new KerberosTime object with the original seconds
and the given microseconds.
/**
     * Returns a new KerberosTime object with the original seconds
     * and the given microseconds.
     */
    public KerberosTime withMicroSeconds(int usec) {
        return new KerberosTime(
                kerberosTime - kerberosTime%1000L + usec/1000L,
                usec%1000);
    }

    private boolean inClockSkew(int clockSkew) {
        return java.lang.Math.abs(kerberosTime - System.currentTimeMillis())
                <= clockSkew * 1000L;
    }

    public boolean inClockSkew() {
        return inClockSkew(getDefaultSkew());
    }

    public boolean greaterThanWRTClockSkew(KerberosTime time, int clockSkew) {
        if ((kerberosTime - time.kerberosTime) > clockSkew * 1000L)
            return true;
        return false;
    }

    public boolean greaterThanWRTClockSkew(KerberosTime time) {
        return greaterThanWRTClockSkew(time, getDefaultSkew());
    }

    public boolean greaterThan(KerberosTime time) {
        return kerberosTime > time.kerberosTime ||
            kerberosTime == time.kerberosTime &&
                    microSeconds > time.microSeconds;
    }

    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }

        if (!(obj instanceof KerberosTime)) {
            return false;
        }

        return kerberosTime == ((KerberosTime)obj).kerberosTime &&
                microSeconds == ((KerberosTime)obj).microSeconds;
    }

    public int hashCode() {
        int result = 37 * 17 + (int)(kerberosTime ^ (kerberosTime >>> 32));
        return result * 17 + microSeconds;
    }

    public boolean isZero() {
        return kerberosTime == 0 && microSeconds == 0;
    }

    public int getSeconds() {
        Long temp_long = new Long(kerberosTime / 1000L);
        return temp_long.intValue();
    }

    
Parse (unmarshal) a kerberostime 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.
Params:
data – the Der input stream value, which contains
            one or more marshaled value.
explicitTag – tag number.
optional – indicates if this data field is optional
Throws:
Asn1Exception – on error.
Returns:
an instance of KerberosTime./**
     * Parse (unmarshal) a kerberostime 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 indicates if this data field is optional
     * @return an instance of KerberosTime.
     *
     */
    public static KerberosTime parse(
            DerInputStream data, byte explicitTag, boolean optional)
            throws Asn1Exception, IOException {
        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();
            Date temp = subDer.getGeneralizedTime();
            return new KerberosTime(temp.getTime(), 0);
        }
    }

    public static int getDefaultSkew() {
        int tdiff = Krb5.DEFAULT_ALLOWABLE_CLOCKSKEW;
        try {
            if ((tdiff = Config.getInstance().getIntValue(
                    "libdefaults", "clockskew"))
                        == Integer.MIN_VALUE) {   //value is not defined
                tdiff = Krb5.DEFAULT_ALLOWABLE_CLOCKSKEW;
            }
        } catch (KrbException e) {
            if (DEBUG) {
                System.out.println("Exception in getting clockskew from " +
                                   "Configuration " +
                                   "using default value " +
                                   e.getMessage());
            }
        }
        return tdiff;
    }

    public String toString() {
        return toGeneralizedTimeString();
    }
}