File	Doc	Category	Size	Date	Package
NtpV3Impl.java	API Doc	Apache Commons NET 1.4.1 API	16295	Sat Dec 03 10:05:48 GMT 2005	org.apache.commons.net.ntp

NtpV3Impl

• java.lang.Object

Fields Summary
private static final int	MODE_INDEX
private static final int	MODE_SHIFT
private static final int	VERSION_INDEX
private static final int	VERSION_SHIFT
private static final int	LI_INDEX
private static final int	LI_SHIFT
private static final int	STRATUM_INDEX
private static final int	POLL_INDEX
private static final int	PRECISION_INDEX
private static final int	ROOT_DELAY_INDEX
private static final int	ROOT_DISPERSION_INDEX
private static final int	REFERENCE_ID_INDEX
private static final int	REFERENCE_TIMESTAMP_INDEX
private static final int	ORIGINATE_TIMESTAMP_INDEX
private static final int	RECEIVE_TIMESTAMP_INDEX
private static final int	TRANSMIT_TIMESTAMP_INDEX
private static final int	KEY_IDENTIFIER_INDEX
private static final int	MESSAGE_DIGEST
private byte[]	buf
private DatagramPacket	dp

Constructors Summary
public NtpV3Impl() Creates a new instance of NtpV3Impl

Methods Summary
public java.net.DatagramPacket	getDatagramPacket() Returns the datagram packet with the NTP details already filled in. return a datagram packet. if (dp == null) synchronized(this) { if (dp == null) { dp = new DatagramPacket(buf, buf.length); dp.setPort(NTP_PORT); } } return dp;
private int	getInt(int index) return 4 bytes as 32-bit int int i = ui(buf[index]) << 24 | ui(buf[index + 1]) << 16 | ui(buf[index + 2]) << 8 | ui(buf[index + 3]); return i;
public int	getLeapIndicator() 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. return (ui(buf[LI_INDEX]) >> LI_SHIFT) & 0x3;
private long	getLong(int index) Get Long value represented by bits starting at specified index. return 8 bytes as 64-bit long 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;
public int	getMode() 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. return (ui(buf[MODE_INDEX]) >> MODE_SHIFT) & 0x7;
public java.lang.String	getModeName() Return human-readable name of message mode type as described in RFC 1305. return mode name as string. return NtpUtils.getModeName(getMode());
public TimeStamp	getOriginateTimeStamp() Returns the originate time as defined in RFC-1305. return the originate time. Never returns null. return getTimestamp(ORIGINATE_TIMESTAMP_INDEX);
public int	getPoll() 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. return (int) (buf[POLL_INDEX]);
public int	getPrecision() 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. return (int) buf[PRECISION_INDEX];
public TimeStamp	getReceiveTimeStamp() Returns receive timestamp as defined in RFC-1305. return the receive time. Never returns null. return getTimestamp(RECEIVE_TIMESTAMP_INDEX);
public int	getReferenceId() 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. return getInt(REFERENCE_ID_INDEX);
public java.lang.String	getReferenceIdString() 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. 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();
public TimeStamp	getReferenceTimeStamp() Returns the reference time as defined in RFC-1305. return the reference time as TimeStamp object. Never returns null. return getTimestamp(REFERENCE_TIMESTAMP_INDEX);
public int	getRootDelay() 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. return getInt(ROOT_DELAY_INDEX);
public double	getRootDelayInMillisDouble() 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 double l = getRootDelay(); return l / 65.536;
public int	getRootDispersion() Returns root dispersion as defined in RFC-1305. return root dispersion. return getInt(ROOT_DISPERSION_INDEX);
public long	getRootDispersionInMillis() Returns root dispersion (as defined in RFC-1305) in milliseconds. return root dispersion in milliseconds long l = getRootDispersion(); return (l * 1000) / 65536L;
public double	getRootDispersionInMillisDouble() Returns root dispersion (as defined in RFC-1305) in milliseconds as double precision value. return root dispersion in milliseconds double l = getRootDispersion(); return l / 65.536;
public int	getStratum() 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. return ui(buf[STRATUM_INDEX]);
private TimeStamp	getTimestamp(int index) Get NTP Timestamp at specified starting index. param index index into data array return TimeStamp object for 64 bits starting at index return new TimeStamp(getLong(index));
public TimeStamp	getTransmitTimeStamp() Returns the transmit timestamp as defined in RFC-1305. return the transmit timestamp as defined in RFC-1305. Never returns a null object. return getTimestamp(TRANSMIT_TIMESTAMP_INDEX);
public java.lang.String	getType() 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". return "NTP";
public int	getVersion() Returns NTP version number as defined in RFC-1305. return NTP version number. return (ui(buf[VERSION_INDEX]) >> VERSION_SHIFT) & 0x7;
private java.lang.String	idAsHex() return Integer.toHexString(getReferenceId());
private java.lang.String	idAsIPAddress() Returns Reference id as dotted IP address. return refId as IP address string. 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 java.lang.String	idAsString() String id = ""; for (int i = 0; i <= 3; i++) { char c = (char) buf[REFERENCE_ID_INDEX + i]; if (c == 0) break; // 0-terminated string id = id + c; } return id;
public void	setDatagramPacket(java.net.DatagramPacket srcDp) Set the contents of this object from source datagram packet. param srcDp source DatagramPacket to copy contents from. byte[] incomingBuf = srcDp.getData(); int len = srcDp.getLength(); if (len > buf.length) len = buf.length; System.arraycopy(incomingBuf, 0, buf, 0, len);
public void	setLeapIndicator(int li) Set leap indicator as defined in RFC-1305. param li leap indicator. buf[LI_INDEX] = (byte) (buf[LI_INDEX] & 0x3F | ((li & 0x3) << LI_SHIFT));
public void	setMode(int mode) Set mode as defined in RFC-1305. param mode buf[MODE_INDEX] = (byte) (buf[MODE_INDEX] & 0xF8 | mode & 0x7);
public void	setOriginateTimeStamp(TimeStamp ts) Set originate timestamp given NTP TimeStamp object. If ts is null then zero time is used. param ts NTP timestamp setTimestamp(ORIGINATE_TIMESTAMP_INDEX, ts);
public void	setPoll(int poll) Set poll interval as defined in RFC-1305. param poll poll interval. buf[POLL_INDEX] = (byte) (poll & 0xFF);
public void	setPrecision(int precision) Set precision as defined in RFC-1305. param precision buf[PRECISION_INDEX] = (byte) (precision & 0xFF);
public void	setReceiveTimeStamp(TimeStamp ts) Set receive timestamp given NTP TimeStamp object. If ts is null then zero time is used. param ts timestamp setTimestamp(RECEIVE_TIMESTAMP_INDEX, ts);
public void	setReferenceId(int refId) Set reference clock identifier field with 32-bit unsigned integer value. See RFC-1305 for description. param refId reference clock identifier. for (int i = 3; i >= 0; i--) { buf[REFERENCE_ID_INDEX + i] = (byte) (refId & 0xff); refId >>>= 8; // shift right one-byte }
public void	setReferenceTime(TimeStamp ts) Set Reference time with NTP timestamp. If ts is null then zero time is used. param ts NTP timestamp setTimestamp(REFERENCE_TIMESTAMP_INDEX, ts);
public void	setStratum(int stratum) Set stratum level as defined in RFC-1305. param stratum stratum level. buf[STRATUM_INDEX] = (byte) (stratum & 0xFF);
private void	setTimestamp(int index, TimeStamp t) Sets the NTP timestamp at the given array index. param index index into the byte array. param t TimeStamp. 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....
public void	setTransmitTime(TimeStamp ts) Set transmit time with NTP timestamp. If ts is null then zero time is used. param ts NTP timestamp setTimestamp(TRANSMIT_TIMESTAMP_INDEX, ts);
public void	setVersion(int version) Set NTP version as defined in RFC-1305. param version NTP version. buf[VERSION_INDEX] = (byte) (buf[VERSION_INDEX] & 0xC7 | ((version & 0x7) << VERSION_SHIFT));
public java.lang.String	toString() Returns details of NTP packet as a string. return details of NTP packet as a string. return "[" + "version:" + getVersion() + ", mode:" + getMode() + ", poll:" + getPoll() + ", precision:" + getPrecision() + ", delay:" + getRootDelay() + ", dispersion(ms):" + getRootDispersionInMillisDouble() + ", id:" + getReferenceIdString() + ", xmitTime:" + getTransmitTimeStamp().toDateString() + " ]";
protected static final int	ui(byte b) Convert byte to unsigned integer. Java only has signed types so we have to do more work to get unsigned ops. param b return unsigned int value of byte int i = b & 0xFF; return i;
protected static final long	ul(byte b) Convert byte to unsigned long. Java only has signed types so we have to do more work to get unsigned ops param b return unsigned long value of byte long i = b & 0xFF; return i;