    001package org.apache.commons.net.ntp;
    002/*
    003 * Licensed to the Apache Software Foundation (ASF) under one or more
    004 * contributor license agreements.  See the NOTICE file distributed with
    005 * this work for additional information regarding copyright ownership.
    006 * The ASF licenses this file to You under the Apache License, Version 2.0
    007 * (the "License"); you may not use this file except in compliance with
    008 * the License.  You may obtain a copy of the License at
    009 *
    010 *      http://www.apache.org/licenses/LICENSE-2.0
    011 *
    012 * Unless required by applicable law or agreed to in writing, software
    013 * distributed under the License is distributed on an "AS IS" BASIS,
    014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    015 * See the License for the specific language governing permissions and
    016 * limitations under the License.
    017 */
    018
    019
    020
    021import java.text.DateFormat;
    022import java.text.SimpleDateFormat;
    023import java.util.Date;
    024import java.util.Locale;
    025import java.util.TimeZone;
    026
    027/***
    028 * TimeStamp class represents the Network Time Protocol (NTP) timestamp
    029 * as defined in RFC-1305 and SNTP (RFC-2030). It is represented as a
    030 * 64-bit unsigned fixed-point number in seconds relative to 0-hour on 1-January-1900.
    031 * The 32-bit low-order bits are the fractional seconds whose precision is
    032 * about 200 picoseconds. Assumes overflow date when date passes MAX_LONG
    033 * and reverts back to 0 is 2036 and not 1900. Test for most significant
    034 * bit: if MSB=0 then 2036 basis is used otherwise 1900 if MSB=1.
    035 * <p>
    036 * Methods exist to convert NTP timestamps to and from the equivalent Java date
    037 * representation, which is the number of milliseconds since the standard base
    038 * time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.
    039 * </p>
    040 *
    041 * @author Jason Mathews, MITRE Corp
    042 * @version $Revision: 1489361 $
    043 * @see java.util.Date
    044 */
    045public class TimeStamp implements java.io.Serializable, Comparable<TimeStamp>
    046{
    047    private static final long serialVersionUID = 8139806907588338737L;
    048
    049    /**
    050     * baseline NTP time if bit-0=0 -> 7-Feb-2036 @ 06:28:16 UTC
    051     */
    052    protected static final long msb0baseTime = 2085978496000L;
    053
    054    /**
    055     *  baseline NTP time if bit-0=1 -> 1-Jan-1900 @ 01:00:00 UTC
    056     */
    057    protected static final long msb1baseTime = -2208988800000L;
    058
    059    /**
    060     * Default NTP date string format. E.g. Fri, Sep 12 2003 21:06:23.860.
    061     * See <code>java.text.SimpleDateFormat</code> for code descriptions.
    062     */
    063    public final static String NTP_DATE_FORMAT = "EEE, MMM dd yyyy HH:mm:ss.SSS";
    064
    065    /**
    066     * NTP timestamp value: 64-bit unsigned fixed-point number as defined in RFC-1305
    067     * with high-order 32 bits the seconds field and the low-order 32-bits the
    068     * fractional field.
    069     */
    070    private final long ntpTime;
    071
    072    private DateFormat simpleFormatter;
    073    private DateFormat utcFormatter;
    074
    075    // initialization of static time bases
    076    /*
    077    static {
    078        TimeZone utcZone = TimeZone.getTimeZone("UTC");
    079        Calendar calendar = Calendar.getInstance(utcZone);
    080        calendar.set(1900, Calendar.JANUARY, 1, 0, 0, 0);
    081        calendar.set(Calendar.MILLISECOND, 0);
    082        msb1baseTime = calendar.getTime().getTime();
    083        calendar.set(2036, Calendar.FEBRUARY, 7, 6, 28, 16);
    084        calendar.set(Calendar.MILLISECOND, 0);
    085        msb0baseTime = calendar.getTime().getTime();
    086    }
    087    */
    088
    089    /***
    090     * Constructs a newly allocated NTP timestamp object
    091     * that represents the native 64-bit long argument.
    092     */
    093    public TimeStamp(long ntpTime)
    094    {
    095        this.ntpTime = ntpTime;
    096    }
    097
    098    /***
    099     * Constructs a newly allocated NTP timestamp object
    100     * that represents the value represented by the string
    101     * in hexdecimal form (e.g. "c1a089bd.fc904f6d").
    102     *
    103     * @throws NumberFormatException - if the string does not contain a parsable timestamp.
    104     */
    105    public TimeStamp(String s) throws NumberFormatException
    106    {
    107        ntpTime = decodeNtpHexString(s);
    108    }
    109
    110    /***
    111     * Constructs a newly allocated NTP timestamp object
    112     * that represents the Java Date argument.
    113     *
    114     * @param d - the Date to be represented by the Timestamp object.
    115     */
    116    public TimeStamp(Date d)
    117    {
    118        ntpTime = (d == null) ? 0 : toNtpTime(d.getTime());
    119    }
    120
    121    /***
    122     * Returns the value of this Timestamp as a long value.
    123     *
    124     * @return the 64-bit long value represented by this object.
    125     */
    126    public long ntpValue()
    127    {
    128        return ntpTime;
    129    }
    130
    131    /***
    132     * Returns high-order 32-bits representing the seconds of this NTP timestamp.
    133     *
    134     * @return seconds represented by this NTP timestamp.
    135     */
    136    public long getSeconds()
    137    {
    138        return (ntpTime >>> 32) & 0xffffffffL;
    139    }
    140
    141    /***
    142     * Returns low-order 32-bits representing the fractional seconds.
    143     *
    144     * @return fractional seconds represented by this NTP timestamp.
    145     */
    146    public long getFraction()
    147    {
    148        return ntpTime & 0xffffffffL;
    149    }
    150
    151    /***
    152     * Convert NTP timestamp to Java standard time.
    153     *
    154     * @return NTP Timestamp in Java time
    155     */
    156    public long getTime()
    157    {
    158        return getTime(ntpTime);
    159    }
    160
    161    /***
    162     * Convert NTP timestamp to Java Date object.
    163     *
    164     * @return NTP Timestamp in Java Date
    165     */
    166    public Date getDate()
    167    {
    168        long time = getTime(ntpTime);
    169        return new Date(time);
    170    }
    171
    172    /***
    173     * Convert 64-bit NTP timestamp to Java standard time.
    174     *
    175     * Note that java time (milliseconds) by definition has less precision
    176     * then NTP time (picoseconds) so converting NTP timestamp to java time and back
    177     * to NTP timestamp loses precision. For example, Tue, Dec 17 2002 09:07:24.810 EST
    178     * is represented by a single Java-based time value of f22cd1fc8a, but its
    179     * NTP equivalent are all values ranging from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.
    180     *
    181     * @param ntpTimeValue
    182     * @return the number of milliseconds since January 1, 1970, 00:00:00 GMT
    183     * represented by this NTP timestamp value.
    184     */
    185    public static long getTime(long ntpTimeValue)
    186    {
    187        long seconds = (ntpTimeValue >>> 32) & 0xffffffffL;     // high-order 32-bits
    188        long fraction = ntpTimeValue & 0xffffffffL;             // low-order 32-bits
    189
    190        // Use round-off on fractional part to preserve going to lower precision
    191        fraction = Math.round(1000D * fraction / 0x100000000L);
    192
    193        /*
    194         * If the most significant bit (MSB) on the seconds field is set we use
    195         * a different time base. The following text is a quote from RFC-2030 (SNTP v4):
    196         *
    197         *  If bit 0 is set, the UTC time is in the range 1968-2036 and UTC time
    198         *  is reckoned from 0h 0m 0s UTC on 1 January 1900. If bit 0 is not set,
    199         *  the time is in the range 2036-2104 and UTC time is reckoned from
    200         *  6h 28m 16s UTC on 7 February 2036.
    201         */
    202        long msb = seconds & 0x80000000L;
    203        if (msb == 0) {
    204            // use base: 7-Feb-2036 @ 06:28:16 UTC
    205            return msb0baseTime + (seconds * 1000) + fraction;
    206        } else {
    207            // use base: 1-Jan-1900 @ 01:00:00 UTC
    208            return msb1baseTime + (seconds * 1000) + fraction;
    209        }
    210    }
    211
    212    /***
    213     * Helper method to convert Java time to NTP timestamp object.
    214     * Note that Java time (milliseconds) by definition has less precision
    215     * then NTP time (picoseconds) so converting Ntptime to Javatime and back
    216     * to Ntptime loses precision. For example, Tue, Dec 17 2002 09:07:24.810
    217     * is represented by a single Java-based time value of f22cd1fc8a, but its
    218     * NTP equivalent are all values from c1a9ae1c.cf5c28f5 to c1a9ae1c.cf9db22c.
    219     * @param   date   the milliseconds since January 1, 1970, 00:00:00 GMT.
    220     * @return NTP timestamp object at the specified date.
    221     */
    222    public static TimeStamp getNtpTime(long date)
    223    {
    224        return new TimeStamp(toNtpTime(date));
    225    }
    226
    227    /***
    228     * Constructs a NTP timestamp object and initializes it so that
    229     * it represents the time at which it was allocated, measured to the
    230     * nearest millisecond.
    231     * @return NTP timestamp object set to the current time.
    232     * @see     java.lang.System#currentTimeMillis()
    233     */
    234    public static TimeStamp getCurrentTime()
    235    {
    236        return getNtpTime(System.currentTimeMillis());
    237    }
    238
    239    /***
    240     * Convert NTP timestamp hexstring (e.g. "c1a089bd.fc904f6d") to the NTP
    241     * 64-bit unsigned fixed-point number.
    242     *
    243     * @return NTP 64-bit timestamp value.
    244     * @throws NumberFormatException - if the string does not contain a parsable timestamp.
    245     */
    246    protected static long decodeNtpHexString(String s)
    247            throws NumberFormatException
    248    {
    249        if (s == null) {
    250            throw new NumberFormatException("null");
    251        }
    252        int ind = s.indexOf('.');
    253        if (ind == -1) {
    254            if (s.length() == 0) {
    255                return 0;
    256            }
    257            return Long.parseLong(s, 16) << 32; // no decimal
    258        }
    259
    260        return Long.parseLong(s.substring(0, ind), 16) << 32 |
    261                Long.parseLong(s.substring(ind + 1), 16);
    262    }
    263
    264    /***
    265     * Parses the string argument as a NTP hexidecimal timestamp representation string
    266     * (e.g. "c1a089bd.fc904f6d").
    267     *
    268     * @param s - hexstring.
    269     * @return the Timestamp represented by the argument in hexidecimal.
    270     * @throws NumberFormatException - if the string does not contain a parsable timestamp.
    271     */
    272    public static TimeStamp parseNtpString(String s)
    273            throws NumberFormatException
    274    {
    275        return new TimeStamp(decodeNtpHexString(s));
    276    }
    277
    278    /***
    279     * Converts Java time to 64-bit NTP time representation.
    280     *
    281     * @param t Java time
    282     * @return NTP timestamp representation of Java time value.
    283     */
    284    protected static long toNtpTime(long t)
    285    {
    286        boolean useBase1 = t < msb0baseTime;    // time < Feb-2036
    287        long baseTime;
    288        if (useBase1) {
    289            baseTime = t - msb1baseTime; // dates <= Feb-2036
    290        } else {
    291            // if base0 needed for dates >= Feb-2036
    292            baseTime = t - msb0baseTime;
    293        }
    294
    295        long seconds = baseTime / 1000;
    296        long fraction = ((baseTime % 1000) * 0x100000000L) / 1000;
    297
    298        if (useBase1) {
    299            seconds |= 0x80000000L; // set high-order bit if msb1baseTime 1900 used
    300        }
    301
    302        long time = seconds << 32 | fraction;
    303        return time;
    304    }
    305
    306    /***
    307     * Computes a hashcode for this Timestamp. The result is the exclusive
    308     * OR of the two halves of the primitive <code>long</code> value
    309     * represented by this <code>TimeStamp</code> object. That is, the hashcode
    310     * is the value of the expression:
    311     * <blockquote><pre>
    312     * (int)(this.ntpValue()^(this.ntpValue() >>> 32))
    313     * </pre></blockquote>
    314     *
    315     * @return  a hash code value for this object.
    316     */
    317    @Override
    318    public int hashCode()
    319    {
    320        return (int) (ntpTime ^ (ntpTime >>> 32));
    321    }
    322
    323    /***
    324     * Compares this object against the specified object.
    325     * The result is <code>true</code> if and only if the argument is
    326     * not <code>null</code> and is a <code>Long</code> object that
    327     * contains the same <code>long</code> value as this object.
    328     *
    329     * @param   obj   the object to compare with.
    330     * @return  <code>true</code> if the objects are the same;
    331     *          <code>false</code> otherwise.
    332     */
    333    @Override
    334    public boolean equals(Object obj)
    335    {
    336        if (obj instanceof TimeStamp) {
    337            return ntpTime == ((TimeStamp) obj).ntpValue();
    338        }
    339        return false;
    340    }
    341
    342    /***
    343     * Converts this <code>TimeStamp</code> object to a <code>String</code>.
    344     * The NTP timestamp 64-bit long value is represented as hex string with
    345     * seconds separated by fractional seconds by a decimal point;
    346     * e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986
    347     *
    348     * @return NTP timestamp 64-bit long value as hex string with seconds
    349     * separated by fractional seconds.
    350     */
    351    @Override
    352    public String toString()
    353    {
    354        return toString(ntpTime);
    355    }
    356
    357    /***
    358     * Left-pad 8-character hex string with 0's
    359     *
    360     * @param buf - StringBuilder which is appended with leading 0's.
    361     * @param l - a long.
    362     */
    363    private static void appendHexString(StringBuilder buf, long l)
    364    {
    365        String s = Long.toHexString(l);
    366        for (int i = s.length(); i < 8; i++) {
    367            buf.append('0');
    368        }
    369        buf.append(s);
    370    }
    371
    372    /***
    373     * Converts 64-bit NTP timestamp value to a <code>String</code>.
    374     * The NTP timestamp value is represented as hex string with
    375     * seconds separated by fractional seconds by a decimal point;
    376     * e.g. c1a089bd.fc904f6d <=> Tue, Dec 10 2002 10:41:49.986
    377     *
    378     * @return NTP timestamp 64-bit long value as hex string with seconds
    379     * separated by fractional seconds.
    380     */
    381    public static String toString(long ntpTime)
    382    {
    383        StringBuilder buf = new StringBuilder();
    384        // high-order second bits (32..63) as hexstring
    385        appendHexString(buf, (ntpTime >>> 32) & 0xffffffffL);
    386
    387        // low-order fractional seconds bits (0..31) as hexstring
    388        buf.append('.');
    389        appendHexString(buf, ntpTime & 0xffffffffL);
    390
    391        return buf.toString();
    392    }
    393
    394    /***
    395     * Converts this <code>TimeStamp</code> object to a <code>String</code>
    396     * of the form:
    397     * <blockquote><pre>
    398     * EEE, MMM dd yyyy HH:mm:ss.SSS</pre></blockquote>
    399     * See java.text.SimpleDataFormat for code descriptions.
    400     *
    401     * @return  a string representation of this date.
    402     */
    403    public String toDateString()
    404    {
    405        if (simpleFormatter == null) {
    406            simpleFormatter = new SimpleDateFormat(NTP_DATE_FORMAT, Locale.US);
    407            simpleFormatter.setTimeZone(TimeZone.getDefault());
    408        }
    409        Date ntpDate = getDate();
    410        return simpleFormatter.format(ntpDate);
    411    }
    412
    413    /***
    414     * Converts this <code>TimeStamp</code> object to a <code>String</code>
    415     * of the form:
    416     * <blockquote><pre>
    417     * EEE, MMM dd yyyy HH:mm:ss.SSS UTC</pre></blockquote>
    418     * See java.text.SimpleDataFormat for code descriptions.
    419     *
    420     * @return  a string representation of this date in UTC.
    421     */
    422    public String toUTCString()
    423    {
    424        if (utcFormatter == null) {
    425            utcFormatter = new SimpleDateFormat(NTP_DATE_FORMAT + " 'UTC'",
    426                    Locale.US);
    427            utcFormatter.setTimeZone(TimeZone.getTimeZone("UTC"));
    428        }
    429        Date ntpDate = getDate();
    430        return utcFormatter.format(ntpDate);
    431    }
    432
    433    /***
    434     * Compares two Timestamps numerically.
    435     *
    436     * @param   anotherTimeStamp - the <code>TimeStamp</code> to be compared.
    437     * @return  the value <code>0</code> if the argument TimeStamp is equal to
    438     *          this TimeStamp; a value less than <code>0</code> if this TimeStamp
    439     *          is numerically less than the TimeStamp argument; and a
    440     *          value greater than <code>0</code> if this TimeStamp is
    441     *          numerically greater than the TimeStamp argument
    442     *          (signed comparison).
    443     */
    444//    @Override
    445    public int compareTo(TimeStamp anotherTimeStamp)
    446    {
    447        long thisVal = this.ntpTime;
    448        long anotherVal = anotherTimeStamp.ntpTime;
    449        return (thisVal < anotherVal ? -1 : (thisVal == anotherVal ? 0 : 1));
    450    }
    451
    452}