Package org.opennms.netmgt.provision.support.ntp

Class NtpMessage

  • public class NtpMessage
extends java.lang.Object

    • Field Summary

      Fields 
      Modifier and Type Field Description
      byte leapIndicator
      This is a two-bit code warning of an impending leap second to be inserted/deleted in the last minute of the current day.
      byte mode
      This value indicates the mode, with values defined as follows: Mode Meaning ---- ------- 0 reserved 1 symmetric active 2 symmetric passive 3 client 4 server 5 broadcast 6 reserved for NTP control message 7 reserved for private use In unicast and anycast modes, the client sets this field to 3 (client) in the request and the server sets it to 4 (server) in the reply.
      double originateTimestamp
      This is the time at which the request departed the client for the server, in seconds since 00:00 1-Jan-1900.
      byte pollInterval
      This value indicates the maximum interval between successive messages, in seconds to the nearest power of two.
      byte precision
      This value indicates the precision of the local clock, in seconds to the nearest power of two.
      double receiveTimestamp
      This is the time at which the request arrived at the server, in seconds since 00:00 1-Jan-1900.
      byte[] referenceIdentifier
      This is a 4-byte array identifying the particular reference source.
      double referenceTimestamp
      This is the time at which the local clock was last set or corrected, in seconds since 00:00 1-Jan-1900.
      double rootDelay
      This value indicates the total roundtrip delay to the primary reference source, in seconds.
      double rootDispersion
      This value indicates the nominal error relative to the primary reference source, in seconds.
      short stratum
      This value indicates the stratum level of the local clock, with values defined as follows: Stratum Meaning ---------------------------------------------- 0 unspecified or unavailable 1 primary reference (e.g., radio clock) 2-15 secondary reference (via NTP or SNTP) 16-255 reserved
      double transmitTimestamp
      This is the time at which the reply departed the server for the client, in seconds since 00:00 1-Jan-1900.
      byte version
      This value indicates the NTP/SNTP version number.

    • Constructor Summary

      Constructors 
      Constructor Description
      NtpMessage()
      Constructs a new NtpMessage in client -> server mode, and sets the transmit timestamp to the current time.
      NtpMessage​(byte[] array)
      Constructs a new NtpMessage from an array of bytes.
      NtpMessage​(byte leapIndicator, byte version, byte mode, short stratum, byte pollInterval, byte precision, double rootDelay, double rootDispersion, byte[] referenceIdentifier, double referenceTimestamp, double originateTimestamp, double receiveTimestamp, double transmitTimestamp)
      Constructs a new NtpMessage

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static double decodeTimestamp​(byte[] array, int pointer)
      Will read 8 bytes of a message beginning at pointer and return it as a double, according to the NTP 64-bit timestamp format.
      static void encodeTimestamp​(byte[] array, int pointer, double timestamp)
      Encodes a timestamp in the specified position in the message
      static java.lang.String referenceIdentifierToString​(byte[] ref, short stratum, byte version)
      Returns a string representation of a reference identifier according to the rules set out in RFC 2030.
      static java.lang.String timestampToString​(double timestamp)
      Returns a timestamp (number of seconds since 00:00 1-Jan-1900) as a formatted date/time string.
      byte[] toByteArray()
      This method constructs the data bytes of a raw NTP packet.
      java.lang.String toString()
      Returns a string representation of a NtpMessage
      static short unsignedByteToShort​(byte b)
      Converts an unsigned byte to a short.

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    • Field Detail

      • leapIndicator

        public byte leapIndicator
        This is a two-bit code warning of an impending leap second to be inserted/deleted in the last minute of the current day. It's values may be as follows: Value Meaning ----- ------- 0 no warning 1 last minute has 61 seconds 2 last minute has 59 seconds) 3 alarm condition (clock not synchronized)

      • version

        public byte version
        This value indicates the NTP/SNTP version number. The version number is 3 for Version 3 (IPv4 only) and 4 for Version 4 (IPv4, IPv6 and OSI). If necessary to distinguish between IPv4, IPv6 and OSI, the encapsulating context must be inspected.

      • mode

        public byte mode
        This value indicates the mode, with values defined as follows: Mode Meaning ---- ------- 0 reserved 1 symmetric active 2 symmetric passive 3 client 4 server 5 broadcast 6 reserved for NTP control message 7 reserved for private use In unicast and anycast modes, the client sets this field to 3 (client) in the request and the server sets it to 4 (server) in the reply. In multicast mode, the server sets this field to 5 (broadcast).

      • stratum

        public short stratum
        This value indicates the stratum level of the local clock, with values defined as follows: Stratum Meaning ---------------------------------------------- 0 unspecified or unavailable 1 primary reference (e.g., radio clock) 2-15 secondary reference (via NTP or SNTP) 16-255 reserved

      • pollInterval

        public byte pollInterval
        This value indicates the maximum interval between successive messages, in seconds to the nearest power of two. The values that can appear in this field presently range from 4 (16 s) to 14 (16284 s); however, most applications use only the sub-range 6 (64 s) to 10 (1024 s).

      • precision

        public byte precision
        This value indicates the precision of the local clock, in seconds to the nearest power of two. The values that normally appear in this field\ range from -6 for mains-frequency clocks to -20 for microsecond clocks found in some workstations.

      • rootDelay

        public double rootDelay
        This value indicates the total roundtrip delay to the primary reference source, in seconds. Note that this variable can take on both positive and negative values, depending on the relative time and frequency offsets. The values that normally appear in this field range from negative values of a few milliseconds to positive values of several hundred milliseconds.

      • rootDispersion

        public double rootDispersion
        This value indicates the nominal error relative to the primary reference source, in seconds. The values that normally appear in this field range from 0 to several hundred milliseconds.

      • referenceIdentifier

        public byte[] referenceIdentifier
        This is a 4-byte array identifying the particular reference source. In the case of NTP Version 3 or Version 4 stratum-0 (unspecified) or stratum-1 (primary) servers, this is a four-character ASCII string, left justified and zero padded to 32 bits. In NTP Version 3 secondary servers, this is the 32-bit IPv4 address of the reference source. In NTP Version 4 secondary servers, this is the low order 32 bits of the latest transmit timestamp of the reference source. NTP primary (stratum 1) servers should set this field to a code identifying the external reference source according to the following list. If the external reference is one of those listed, the associated code should be used. Codes for sources not listed can be contrived as appropriate. Code External Reference Source ---- ------------------------- LOCL uncalibrated local clock used as a primary reference for a subnet without external means of synchronization PPS atomic clock or other pulse-per-second source individually calibrated to national standards ACTS NIST dialup modem service USNO USNO modem service PTB PTB (Germany) modem service TDF Allouis (France) Radio 164 kHz DCF Mainflingen (Germany) Radio 77.5 kHz MSF Rugby (UK) Radio 60 kHz WWV Ft. Collins (US) Radio 2.5, 5, 10, 15, 20 MHz WWVB Boulder (US) Radio 60 kHz WWVH Kaui Hawaii (US) Radio 2.5, 5, 10, 15 MHz CHU Ottawa (Canada) Radio 3330, 7335, 14670 kHz LORC LORAN-C radionavigation system OMEG OMEGA radionavigation system GPS Global Positioning Service GOES Geostationary Orbit Environment Satellite

      • referenceTimestamp

        public double referenceTimestamp
        This is the time at which the local clock was last set or corrected, in seconds since 00:00 1-Jan-1900.

      • originateTimestamp

        public double originateTimestamp
        This is the time at which the request departed the client for the server, in seconds since 00:00 1-Jan-1900.

      • receiveTimestamp

        public double receiveTimestamp
        This is the time at which the request arrived at the server, in seconds since 00:00 1-Jan-1900.

      • transmitTimestamp

        public double transmitTimestamp
        This is the time at which the reply departed the server for the client, in seconds since 00:00 1-Jan-1900.

    • Constructor Detail

      • NtpMessage

        public NtpMessage​(byte[] array)
        Constructs a new NtpMessage from an array of bytes.
        Parameters:
        array - an array of byte.

      • NtpMessage

        public NtpMessage​(byte leapIndicator,
                  byte version,
                  byte mode,
                  short stratum,
                  byte pollInterval,
                  byte precision,
                  double rootDelay,
                  double rootDispersion,
                  byte[] referenceIdentifier,
                  double referenceTimestamp,
                  double originateTimestamp,
                  double receiveTimestamp,
                  double transmitTimestamp)
        Constructs a new NtpMessage
        Parameters:
        leapIndicator - a byte.
        version - a byte.
        mode - a byte.
        stratum - a short.
        pollInterval - a byte.
        precision - a byte.
        rootDelay - a double.
        rootDispersion - a double.
        referenceIdentifier - an array of byte.
        referenceTimestamp - a double.
        originateTimestamp - a double.
        receiveTimestamp - a double.
        transmitTimestamp - a double.

      • NtpMessage

        public NtpMessage()
        Constructs a new NtpMessage in client -> server mode, and sets the transmit timestamp to the current time.

    • Method Detail

      • toByteArray

        public byte[] toByteArray()
        This method constructs the data bytes of a raw NTP packet.
        Returns:
        an array of byte.

      • toString

        public java.lang.String toString()
        Returns a string representation of a NtpMessage
        Overrides:
        toString in class java.lang.Object
        Returns:
        a String object.

      • unsignedByteToShort

        public static short unsignedByteToShort​(byte b)
        Converts an unsigned byte to a short. By default, Java assumes that a byte is signed.
        Parameters:
        b - a byte.
        Returns:
        a short.

      • decodeTimestamp

        public static double decodeTimestamp​(byte[] array,
                                     int pointer)
        Will read 8 bytes of a message beginning at pointer and return it as a double, according to the NTP 64-bit timestamp format.
        Parameters:
        array - an array of byte.
        pointer - a int.
        Returns:
        a double.

      • encodeTimestamp

        public static void encodeTimestamp​(byte[] array,
                                   int pointer,
                                   double timestamp)
        Encodes a timestamp in the specified position in the message
        Parameters:
        array - an array of byte.
        pointer - a int.
        timestamp - a double.

      • timestampToString

        public static java.lang.String timestampToString​(double timestamp)
        Returns a timestamp (number of seconds since 00:00 1-Jan-1900) as a formatted date/time string.
        Parameters:
        timestamp - a double.
        Returns:
        a String object.

      • referenceIdentifierToString

        public static java.lang.String referenceIdentifierToString​(byte[] ref,
                                                           short stratum,
                                                           byte version)
        Returns a string representation of a reference identifier according to the rules set out in RFC 2030.
        Parameters:
        ref - an array of byte.
        stratum - a short.
        version - a byte.
        Returns:
        a String object.