package org.apache.commons.net.ntp;
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import java.net.DatagramPacket;

Implementation of NtpV3Packet with methods converting Java objects to/from
the Network Time Protocol (NTP) data message header format described in RFC-1305.
Version:
$Revision: 1741829 $/***
 * Implementation of NtpV3Packet with methods converting Java objects to/from
 * the Network Time Protocol (NTP) data message header format described in RFC-1305.
 *
 * @version $Revision: 1741829 $
 */
public class NtpV3Impl implements NtpV3Packet
{

    private static final int MODE_INDEX = 0;
    private static final int MODE_SHIFT = 0;

    private static final int VERSION_INDEX = 0;
    private static final int VERSION_SHIFT = 3;

    private static final int LI_INDEX = 0;
    private static final int LI_SHIFT = 6;

    private static final int STRATUM_INDEX = 1;
    private static final int POLL_INDEX = 2;
    private static final int PRECISION_INDEX = 3;

    private static final int ROOT_DELAY_INDEX = 4;
    private static final int ROOT_DISPERSION_INDEX = 8;
    private static final int REFERENCE_ID_INDEX = 12;

    private static final int REFERENCE_TIMESTAMP_INDEX = 16;
    private static final int ORIGINATE_TIMESTAMP_INDEX = 24;
    private static final int RECEIVE_TIMESTAMP_INDEX = 32;
    private static final int TRANSMIT_TIMESTAMP_INDEX = 40;

//    private static final int KEY_IDENTIFIER_INDEX = 48;
//    private static final int MESSAGE_DIGEST = 54; /* len 16 bytes */

    private final byte[] buf = new byte[48];

    private volatile DatagramPacket dp;

    
Creates a new instance of NtpV3Impl /** Creates a new instance of NtpV3Impl */
    public NtpV3Impl()
    {
    }

    
Returns mode as defined in RFC-1305 which is a 3-bit integer
whose value is indicated by the MODE_xxx parameters.
Returns:
mode as defined in RFC-1305./***
     * Returns mode as defined in RFC-1305 which is a 3-bit integer
     * whose value is indicated by the MODE_xxx parameters.
     *
     * @return mode as defined in RFC-1305.
     */
    @Override
    public int getMode()
    {
        return (ui(buf[MODE_INDEX]) >> MODE_SHIFT) & 0x7;
    }

    
Return human-readable name of message mode type as described in
RFC 1305.
Returns:
mode name as string./***
     * Return human-readable name of message mode type as described in
     * RFC 1305.
     * @return mode name as string.
     */
    @Override
    public String getModeName()
    {
        return NtpUtils.getModeName(getMode());
    }

    
Set mode as defined in RFC-1305.
Params:
mode – the mode to set/***
     * Set mode as defined in RFC-1305.
     *
     * @param mode the mode to set
     */
    @Override
    public void setMode(int mode)
    {
        buf[MODE_INDEX] = (byte) (buf[MODE_INDEX] & 0xF8 | mode & 0x7);
    }

    
Returns leap indicator as defined in RFC-1305 which is a two-bit code:
 0=no warning
 1=last minute has 61 seconds
 2=last minute has 59 seconds
 3=alarm condition (clock not synchronized)
Returns:
leap indicator as defined in RFC-1305./***
     * Returns leap indicator as defined in RFC-1305 which is a two-bit code:
     *  0=no warning
     *  1=last minute has 61 seconds
     *  2=last minute has 59 seconds
     *  3=alarm condition (clock not synchronized)
     *
     * @return leap indicator as defined in RFC-1305.
     */
    @Override
    public int getLeapIndicator()
    {
        return (ui(buf[LI_INDEX]) >> LI_SHIFT) & 0x3;
    }

    
Set leap indicator as defined in RFC-1305.
Params:
li – leap indicator./***
     * Set leap indicator as defined in RFC-1305.
     *
     * @param li leap indicator.
     */
    @Override
    public void setLeapIndicator(int li)
    {
        buf[LI_INDEX] = (byte) (buf[LI_INDEX] & 0x3F | ((li & 0x3) << LI_SHIFT));
    }

    
Returns poll interval as defined in RFC-1305, which is an eight-bit
signed integer indicating the maximum interval between successive
messages, in seconds to the nearest power of two (e.g. value of six
indicates an interval of 64 seconds. The values that can appear in
this field range from NTP_MINPOLL to NTP_MAXPOLL inclusive.
Returns:
poll interval as defined in RFC-1305./***
     * Returns poll interval as defined in RFC-1305, which is an eight-bit
     * signed integer indicating the maximum interval between successive
     * messages, in seconds to the nearest power of two (e.g. value of six
     * indicates an interval of 64 seconds. The values that can appear in
     * this field range from NTP_MINPOLL to NTP_MAXPOLL inclusive.
     *
     * @return poll interval as defined in RFC-1305.
     */
    @Override
    public int getPoll()
    {
        return buf[POLL_INDEX];
    }

    
Set poll interval as defined in RFC-1305.
Params:
poll – poll interval./***
     * Set poll interval as defined in RFC-1305.
     *
     * @param poll poll interval.
     */
    @Override
    public void setPoll(int poll)
    {
        buf[POLL_INDEX] = (byte) (poll & 0xFF);
    }

    
Returns precision as defined in RFC-1305 encoded as an 8-bit signed
integer (seconds to nearest power of two).
Values normally range from -6 to -20.
Returns:
precision as defined in RFC-1305./***
     * Returns precision as defined in RFC-1305 encoded as an 8-bit signed
     * integer (seconds to nearest power of two).
     * Values normally range from -6 to -20.
     *
     * @return precision as defined in RFC-1305.
     */
    @Override
    public int getPrecision()
    {
        return buf[PRECISION_INDEX];
    }

    
Set precision as defined in RFC-1305.
Params:
precision – the precision to set
Since:
3.4/***
     * Set precision as defined in RFC-1305.
     * @param precision the precision to set
     * @since 3.4
     */
    @Override
    public void setPrecision(int precision)
    {
        buf[PRECISION_INDEX] = (byte) (precision & 0xFF);
    }

    
Returns NTP version number as defined in RFC-1305.
Returns:
NTP version number./***
     * Returns NTP version number as defined in RFC-1305.
     *
     * @return NTP version number.
     */
    @Override
    public int getVersion()
    {
        return (ui(buf[VERSION_INDEX]) >> VERSION_SHIFT) & 0x7;
    }

    
Set NTP version as defined in RFC-1305.
Params:
version – NTP version./***
     * Set NTP version as defined in RFC-1305.
     *
     * @param version NTP version.
     */
    @Override
    public void setVersion(int version)
    {
        buf[VERSION_INDEX] = (byte) (buf[VERSION_INDEX] & 0xC7 | ((version & 0x7) << VERSION_SHIFT));
    }

    
Returns Stratum as defined in RFC-1305, which indicates the stratum level
of the local clock, with values defined as follows: 0=unspecified,
1=primary ref clock, and all others a secondary reference (via NTP).
Returns:
Stratum level as defined in RFC-1305./***
     * Returns Stratum as defined in RFC-1305, which indicates the stratum level
     * of the local clock, with values defined as follows: 0=unspecified,
     * 1=primary ref clock, and all others a secondary reference (via NTP).
     *
     * @return Stratum level as defined in RFC-1305.
     */
    @Override
    public int getStratum()
    {
        return ui(buf[STRATUM_INDEX]);
    }

    
Set stratum level as defined in RFC-1305.
Params:
stratum – stratum level./***
     * Set stratum level as defined in RFC-1305.
     *
     * @param stratum stratum level.
     */
    @Override
    public void setStratum(int stratum)
    {
        buf[STRATUM_INDEX] = (byte) (stratum & 0xFF);
    }

    
Return root delay as defined in RFC-1305, which is the total roundtrip delay
to the primary reference source, in seconds. Values can take positive and
negative values, depending on clock precision and skew.
Returns:
root delay as defined in RFC-1305./***
     * Return root delay as defined in RFC-1305, which is the total roundtrip delay
     * to the primary reference source, in seconds. Values can take positive and
     * negative values, depending on clock precision and skew.
     *
     * @return root delay as defined in RFC-1305.
     */
    @Override
    public int getRootDelay()
    {
        return getInt(ROOT_DELAY_INDEX);
    }

    
Set root delay as defined in RFC-1305.
Params:
delay – root delay
Since:
3.4/***
     * Set root delay as defined in RFC-1305.
     *
     * @param delay root delay
     * @since 3.4
     */
    @Override
    public void setRootDelay(int delay)
    {
        setInt(ROOT_DELAY_INDEX, delay);
    }

    
Return root delay as defined in RFC-1305 in milliseconds, which is
the total roundtrip delay to the primary reference source, in
seconds. Values can take positive and negative values, depending
on clock precision and skew.
Returns:
root delay in milliseconds/**
     * Return root delay as defined in RFC-1305 in milliseconds, which is
     * the total roundtrip delay to the primary reference source, in
     * seconds. Values can take positive and negative values, depending
     * on clock precision and skew.
     *
     * @return root delay in milliseconds
     */
    @Override
    public double getRootDelayInMillisDouble()
    {
        double l = getRootDelay();
        return l / 65.536;
    }

    
Returns root dispersion as defined in RFC-1305.
Returns:
root dispersion./***
     * Returns root dispersion as defined in RFC-1305.
     * @return root dispersion.
     */
    @Override
    public int getRootDispersion()
    {
        return getInt(ROOT_DISPERSION_INDEX);
    }

    
Set root dispersion as defined in RFC-1305.
Params:
dispersion – root dispersion
Since:
3.4/***
     * Set root dispersion as defined in RFC-1305.
     *
     * @param dispersion root dispersion
     * @since 3.4
     */
    @Override
    public void setRootDispersion(int dispersion)
    {
        setInt(ROOT_DISPERSION_INDEX, dispersion);
    }

    
Returns root dispersion (as defined in RFC-1305) in milliseconds.
Returns:
root dispersion in milliseconds/***
     * Returns root dispersion (as defined in RFC-1305) in milliseconds.
     *
     * @return root dispersion in milliseconds
     */
    @Override
    public long getRootDispersionInMillis()
    {
        long l = getRootDispersion();
        return (l * 1000) / 65536L;
    }

    
Returns root dispersion (as defined in RFC-1305) in milliseconds
as double precision value.
Returns:
root dispersion in milliseconds/***
     * Returns root dispersion (as defined in RFC-1305) in milliseconds
     * as double precision value.
     *
     * @return root dispersion in milliseconds
     */
    @Override
    public double getRootDispersionInMillisDouble()
    {
        double l = getRootDispersion();
        return l / 65.536;
    }

    
Set reference clock identifier field with 32-bit unsigned integer value.
See RFC-1305 for description.
Params:
refId – reference clock identifier./***
     * Set reference clock identifier field with 32-bit unsigned integer value.
     * See RFC-1305 for description.
     *
     * @param refId reference clock identifier.
     */
    @Override
    public void setReferenceId(int refId)
    {
        setInt(REFERENCE_ID_INDEX, refId);
    }

    
Returns the reference id as defined in RFC-1305, which is
a 32-bit integer whose value is dependent on several criteria.
Returns:
the reference id as defined in RFC-1305./***
     * Returns the reference id as defined in RFC-1305, which is
     * a 32-bit integer whose value is dependent on several criteria.
     *
     * @return the reference id as defined in RFC-1305.
     */
    @Override
    public int getReferenceId()
    {
        return getInt(REFERENCE_ID_INDEX);
    }

    
Returns the reference id string. String cannot be null but
value is dependent on the version of the NTP spec supported
and stratum level. Value can be an empty string, clock type string,
IP address, or a hex string.
Returns:
the reference id string./***
     * Returns the reference id string. String cannot be null but
     * value is dependent on the version of the NTP spec supported
     * and stratum level. Value can be an empty string, clock type string,
     * IP address, or a hex string.
     *
     * @return the reference id string.
     */
    @Override
    public String getReferenceIdString()
    {
        int version = getVersion();
        int stratum = getStratum();
        if (version == VERSION_3 || version == VERSION_4) {
            if (stratum == 0 || stratum == 1) {
                return idAsString(); // 4-character ASCII string (e.g. GPS, USNO)
            }
            // in NTPv4 servers this is latest transmit timestamp of ref source
            if (version == VERSION_4) {
                return idAsHex();
            }
        }

        // Stratum 2 and higher this is a four-octet IPv4 address
        // of the primary reference host.
        if (stratum >= 2) {
            return idAsIPAddress();
        }
        return idAsHex();
    }

    
Returns Reference id as dotted IP address.
Returns:
refId as IP address string./***
     * Returns Reference id as dotted IP address.
     * @return refId as IP address string.
     */
    private String idAsIPAddress()
    {
        return ui(buf[REFERENCE_ID_INDEX]) + "." +
                ui(buf[REFERENCE_ID_INDEX + 1]) + "." +
                ui(buf[REFERENCE_ID_INDEX + 2]) + "." +
                ui(buf[REFERENCE_ID_INDEX + 3]);
    }

    private String idAsString()
    {
        StringBuilder id = new StringBuilder();
        for (int i = 0; i <= 3; i++) {
            char c = (char) buf[REFERENCE_ID_INDEX + i];
            if (c == 0) {  // 0-terminated string
                break;
            }
            id.append(c);
        }
        return id.toString();
    }

    private String idAsHex()
    {
        return Integer.toHexString(getReferenceId());
    }

    
Returns the transmit timestamp as defined in RFC-1305.
Returns:
the transmit timestamp as defined in RFC-1305.
Never returns a null object./***
     * Returns the transmit timestamp as defined in RFC-1305.
     *
     * @return the transmit timestamp as defined in RFC-1305.
     * Never returns a null object.
     */
    @Override
    public TimeStamp getTransmitTimeStamp()
    {
        return getTimestamp(TRANSMIT_TIMESTAMP_INDEX);
    }

    
Set transmit time with NTP timestamp.
If ts is null then zero time is used.
Params:
ts – NTP timestamp/***
     * Set transmit time with NTP timestamp.
     * If <code>ts</code> is null then zero time is used.
     *
     * @param ts NTP timestamp
     */
    @Override
    public void setTransmitTime(TimeStamp ts)
    {
        setTimestamp(TRANSMIT_TIMESTAMP_INDEX, ts);
    }

    
Set originate timestamp given NTP TimeStamp object.
If ts is null then zero time is used.
Params:
ts – NTP timestamp/***
     * Set originate timestamp given NTP TimeStamp object.
     * If <code>ts</code> is null then zero time is used.
     *
     * @param ts NTP timestamp
     */
    @Override
    public void setOriginateTimeStamp(TimeStamp ts)
    {
        setTimestamp(ORIGINATE_TIMESTAMP_INDEX, ts);
    }

    
Returns the originate time as defined in RFC-1305.
Returns:
the originate time.
Never returns null./***
     * Returns the originate time as defined in RFC-1305.
     *
     * @return the originate time.
     * Never returns null.
     */
    @Override
    public TimeStamp getOriginateTimeStamp()
    {
        return getTimestamp(ORIGINATE_TIMESTAMP_INDEX);
    }

    
Returns the reference time as defined in RFC-1305.
Returns:
the reference time as TimeStamp object.
Never returns null./***
     * Returns the reference time as defined in RFC-1305.
     *
     * @return the reference time as <code>TimeStamp</code> object.
     * Never returns null.
     */
    @Override
    public TimeStamp getReferenceTimeStamp()
    {
        return getTimestamp(REFERENCE_TIMESTAMP_INDEX);
    }

    
Set Reference time with NTP timestamp. If ts is null
then zero time is used.
Params:
ts – NTP timestamp/***
     * Set Reference time with NTP timestamp. If <code>ts</code> is null
     * then zero time is used.
     *
     * @param ts NTP timestamp
     */
    @Override
    public void setReferenceTime(TimeStamp ts)
    {
        setTimestamp(REFERENCE_TIMESTAMP_INDEX, ts);
    }

    
Returns receive timestamp as defined in RFC-1305.
Returns:
the receive time.
Never returns null./***
     * Returns receive timestamp as defined in RFC-1305.
     *
     * @return the receive time.
     * Never returns null.
     */
    @Override
    public TimeStamp getReceiveTimeStamp()
    {
        return getTimestamp(RECEIVE_TIMESTAMP_INDEX);
    }

    
Set receive timestamp given NTP TimeStamp object.
If ts is null then zero time is used.
Params:
ts – timestamp/***
     * Set receive timestamp given NTP TimeStamp object.
     * If <code>ts</code> is null then zero time is used.
     *
     * @param ts timestamp
     */
    @Override
    public void setReceiveTimeStamp(TimeStamp ts)
    {
        setTimestamp(RECEIVE_TIMESTAMP_INDEX, ts);
    }

    
Return type of time packet. The values (e.g. NTP, TIME, ICMP, ...)
correspond to the protocol used to obtain the timing information.
Returns:
packet type string identifier which in this case is "NTP"./***
     * Return type of time packet. The values (e.g. NTP, TIME, ICMP, ...)
     * correspond to the protocol used to obtain the timing information.
     *
     * @return packet type string identifier which in this case is "NTP".
     */
    @Override
    public String getType()
    {
        return "NTP";
    }

    
Returns:
4 bytes as 32-bit int/***
     * @return 4 bytes as 32-bit int
     */
    private int getInt(int index)
    {
        int i = ui(buf[index]) << 24 |
                ui(buf[index + 1]) << 16 |
                ui(buf[index + 2]) << 8 |
                ui(buf[index + 3]);

        return i;
    }

    
Set integer value at index position.
Params:
idx – index position
value – 32-bit int value/***
     * Set integer value at index position.
     *
     * @param idx index position
     * @param value 32-bit int value
     */
    private void setInt(int idx, int value)
    {
        for (int i=3; i >= 0; i--) {
            buf[idx + i] = (byte) (value & 0xff);
            value >>>= 8; // shift right one-byte
        }
    }

    
Get NTP Timestamp at specified starting index.
Params:
index – index into data array
Returns:
TimeStamp object for 64 bits starting at index/**
     * Get NTP Timestamp at specified starting index.
     *
     * @param index index into data array
     * @return TimeStamp object for 64 bits starting at index
     */
    private TimeStamp getTimestamp(int index)
    {
        return new TimeStamp(getLong(index));
    }

    
Get Long value represented by bits starting at specified index.
Returns:
8 bytes as 64-bit long/***
     * Get Long value represented by bits starting at specified index.
     *
     * @return 8 bytes as 64-bit long
     */
    private long getLong(int index)
    {
        long i = ul(buf[index]) << 56 |
                ul(buf[index + 1]) << 48 |
                ul(buf[index + 2]) << 40 |
                ul(buf[index + 3]) << 32 |
                ul(buf[index + 4]) << 24 |
                ul(buf[index + 5]) << 16 |
                ul(buf[index + 6]) << 8 |
                ul(buf[index + 7]);
        return i;
    }

    
Sets the NTP timestamp at the given array index.
Params:
index – index into the byte array.
t – TimeStamp./***
     * Sets the NTP timestamp at the given array index.
     *
     * @param index index into the byte array.
     * @param t TimeStamp.
     */
    private void setTimestamp(int index, TimeStamp t)
    {
        long ntpTime = (t == null) ? 0 : t.ntpValue();
        // copy 64-bits from Long value into 8 x 8-bit bytes of array
        // one byte at a time shifting 8-bits for each position.
        for (int i = 7; i >= 0; i--) {
            buf[index + i] = (byte) (ntpTime & 0xFF);
            ntpTime >>>= 8; // shift to next byte
        }
        // buf[index] |= 0x80;  // only set if 1900 baseline....
    }

    
Returns the datagram packet with the NTP details already filled in.
Returns:
a datagram packet./***
     * Returns the datagram packet with the NTP details already filled in.
     *
     * @return a datagram packet.
     */
    @Override
    public synchronized DatagramPacket getDatagramPacket()
    {
        if (dp == null) {
            dp = new DatagramPacket(buf, buf.length);
            dp.setPort(NTP_PORT);
        }
        return dp;
    }

    
Set the contents of this object from source datagram packet.
Params:
srcDp – source DatagramPacket to copy contents from, never null.
Throws:
IllegalArgumentException – if srcDp is null or byte length is less than minimum length of 48 bytes/***
     * Set the contents of this object from source datagram packet.
     *
     * @param srcDp source DatagramPacket to copy contents from, never null.
     * @throws IllegalArgumentException if srcDp is null or byte length is less than minimum length of 48 bytes
     */
    @Override
    public void setDatagramPacket(DatagramPacket srcDp)
    {
        if (srcDp == null || srcDp.getLength() < buf.length) {
            throw new IllegalArgumentException();
        }
        byte[] incomingBuf = srcDp.getData();
        int len = srcDp.getLength();
        if (len > buf.length) {
            len = buf.length;
        }
        System.arraycopy(incomingBuf, 0, buf, 0, len);
        DatagramPacket dp = getDatagramPacket();
        dp.setAddress(srcDp.getAddress());
        int port = srcDp.getPort();
        dp.setPort(port > 0 ? port : NTP_PORT);
        dp.setData(buf);
    }

    
Compares this object against the specified object.
The result is true if and only if the argument is
not null and is a NtpV3Impl object that
contains the same values as this object.
Params:
obj –   the object to compare with.
Returns:
 true if the objects are the same;
         false otherwise.
Since:
3.4/***
     * Compares this object against the specified object.
     * The result is <code>true</code> if and only if the argument is
     * not <code>null</code> and is a <code>NtpV3Impl</code> object that
     * contains the same values as this object.
     *
     * @param   obj   the object to compare with.
     * @return  <code>true</code> if the objects are the same;
     *          <code>false</code> otherwise.
     * @since 3.4
     */
    @Override
    public boolean equals(Object obj)
    {
        if (this == obj) {
            return true;
        }
        if (obj == null || getClass() != obj.getClass()) {
            return false;
        }
        NtpV3Impl other = (NtpV3Impl) obj;
        return java.util.Arrays.equals(buf, other.buf);
    }

    
Computes a hashcode for this object. The result is the exclusive
OR of the values of this object stored as a byte array.
Returns:
 a hash code value for this object.
Since:
3.4/***
     * Computes a hashcode for this object. The result is the exclusive
     * OR of the values of this object stored as a byte array.
     *
     * @return  a hash code value for this object.
     * @since 3.4
     */
    @Override
    public int hashCode()
    {
        return java.util.Arrays.hashCode(buf);
    }

    
Convert byte to unsigned integer.
Java only has signed types so we have to do
more work to get unsigned ops.
Params:
b – input byte
Returns:
unsigned int value of byte/***
     * Convert byte to unsigned integer.
     * Java only has signed types so we have to do
     * more work to get unsigned ops.
     *
     * @param b input byte
     * @return unsigned int value of byte
     */
    protected static final int ui(byte b)
    {
        int i = b & 0xFF;
        return i;
    }

    
Convert byte to unsigned long.
Java only has signed types so we have to do
more work to get unsigned ops
Params:
b – input byte
Returns:
unsigned long value of byte/***
     * Convert byte to unsigned long.
     * Java only has signed types so we have to do
     * more work to get unsigned ops
     *
     * @param b input byte
     * @return unsigned long value of byte
     */
    protected static final long ul(byte b)
    {
        long i = b & 0xFF;
        return i;
    }

    
Returns details of NTP packet as a string.
Returns:
details of NTP packet as a string./***
     * Returns details of NTP packet as a string.
     *
     * @return details of NTP packet as a string.
     */
    @Override
    public String toString()
    {
        return "[" +
                "version:" + getVersion() +
                ", mode:" + getMode() +
                ", poll:" + getPoll() +
                ", precision:" + getPrecision() +
                ", delay:" + getRootDelay() +
                ", dispersion(ms):" + getRootDispersionInMillisDouble() +
                ", id:" + getReferenceIdString() +
                ", xmitTime:" + getTransmitTimeStamp().toDateString() +
                " ]";
    }

}