/*
* A C# SNTP Client
*
* Copyright (C)2001-2003 Valer BOCAN <vbocan@dataman.ro>
* All Rights Reserved
*
* You may download the latest version from http://www.dataman.ro
* Last modified: September 20, 2003
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, and/or sell copies of the Software, and to permit persons
* to whom the Software is furnished to do so, provided that the above
* copyright notice(s) and this permission notice appear in all copies of
* the Software and that both the above copyright notice(s) and this
* permission notice appear in supporting documentation.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT
* OF THIRD PARTY RIGHTS. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
* HOLDERS INCLUDED IN THIS NOTICE BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
* INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Disclaimer
* ----------
* Although reasonable care has been taken to ensure the correctness of this
* implementation, this code should never be used in any application without
* proper verification and testing. I disclaim all liability and responsibility
* to any person or entity with respect to any loss or damage caused, or alleged
* to be caused, directly or indirectly, by the use of this SNTPClient class.
*
* Comments, bugs and suggestions are welcome.
*
* Update history:
* September 20, 2003
* - Renamed the class from NTPClient to SNTPClient.
* - Fixed the RoundTripDelay and LocalClockOffset properties.
* Thanks go to DNH <dnharris@csrlink.net>.
* - Fixed the PollInterval property.
* Thanks go to Jim Hollenhorst <hollenho@attbi.com>.
* - Changed the ReceptionTimestamp variable to DestinationTimestamp to follow the standard
* more closely.
* - Precision property is now shown is seconds rather than milliseconds in the
* ToString method.
*
* May 28, 2002
* - Fixed a bug in the Precision property and the SetTime function.
* Thanks go to Jim Hollenhorst <hollenho@attbi.com>.
*
* March 14, 2001
* - First public release.
*/
namespace InternetTime
{
using System;
using System.Net;
using System.Net.Sockets;
using System.Runtime.InteropServices;
// Leap indicator field values
public enum _LeapIndicator
{
NoWarning, // 0 - No warning
LastMinute61, // 1 - Last minute has 61 seconds
LastMinute59, // 2 - Last minute has 59 seconds
Alarm // 3 - Alarm condition (clock not synchronized)
}
//Mode field values
public enum _Mode
{
SymmetricActive, // 1 - Symmetric active
SymmetricPassive, // 2 - Symmetric pasive
Client, // 3 - Client
Server, // 4 - Server
Broadcast, // 5 - Broadcast
Unknown // 0, 6, 7 - Reserved
}
// Stratum field values
public enum _Stratum
{
Unspecified, // 0 - unspecified or unavailable
PrimaryReference, // 1 - primary reference (e.g. radio-clock)
SecondaryReference, // 2-15 - secondary reference (via NTP or SNTP)
Reserved // 16-255 - reserved
}
/// <summary>
/// SNTPClient is a C# class designed to connect to time servers on the Internet and
/// fetch the current date and time. Optionally, it may update the time of the local system.
/// The implementation of the protocol is based on the RFC 2030.
///
/// Public class members:
///
/// LeapIndicator - Warns of an impending leap second to be inserted/deleted in the last
/// minute of the current day. (See the _LeapIndicator enum)
///
/// VersionNumber - Version number of the protocol (3 or 4).
///
/// Mode - Returns mode. (See the _Mode enum)
///
/// Stratum - Stratum of the clock. (See the _Stratum enum)
///
/// PollInterval - Maximum interval between successive messages
///
/// Precision - Precision of the clock
///
/// RootDelay - Round trip time to the primary reference source.
///
/// RootDispersion - Nominal error relative to the primary reference source.
///
/// ReferenceID - Reference identifier (either a 4 character string or an IP address).
///
/// ReferenceTimestamp - The time at which the clock was last set or corrected.
///
/// OriginateTimestamp - The time at which the request departed the client for the server.
///
/// ReceiveTimestamp - The time at which the request arrived at the server.
///
/// Transmit Timestamp - The time at which the reply departed the server for client.
///
/// RoundTripDelay - The time between the departure of request and arrival of reply.
///
/// LocalClockOffset - The offset of the local clock relative to the primary reference
/// source.
///
/// Initialize - Sets up data structure and prepares for connection.
///
/// Connect - Connects to the time server and populates the data structure.
/// It can also update the system time.
///
/// IsResponseValid - Returns true if received data is valid and if comes from
/// a NTP-compliant time server.
///
/// ToString - Returns a string representation of the object.
///
/// -----------------------------------------------------------------------------
/// Structure of the standard NTP header (as described in RFC 2030)
/// 1 2 3
/// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// |LI | VN |Mode | Stratum | Poll | Precision |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Root Delay |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Root Dispersion |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Reference Identifier |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | |
/// | Reference Timestamp (64) |
/// | |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | |
/// | Originate Timestamp (64) |
/// | |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | |
/// | Receive Timestamp (64) |
/// | |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | |
/// | Transmit Timestamp (64) |
/// | |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Key Identifier (optional) (32) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | |
/// | |
/// | Message Digest (optional) (128) |
/// | |
/// | |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
///
/// -----------------------------------------------------------------------------
///
/// SNTP Timestamp Format (as described in RFC 2030)
/// 1 2 3
/// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Seconds |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/// | Seconds Fraction (0-padded) |
/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
///
/// </summary>
public class SNTPClient
{
// SNTP Data Structure Length
private const byte SNTPDataLength = 48;
// SNTP Data Structure (as described in RFC 2030)
byte []SNTPData = new byte[SNTPDataLength];
// Offset constants for timestamps in the data structure
private const byte offReferenceID = 12;
private const byte offReferenceTimestamp = 16;
private const byte offOriginateTimestamp = 24;
private const byte offReceiveTimestamp = 32;
private const byte offTransmitTimestamp = 40;
// Leap Indicator
public _LeapIndicator LeapIndicator
{
get
{
// Isolate the two most significant bits
byte val = (byte)(SNTPData[0] >> 6);
switch(val)
{
case 0: return _LeapIndicator.NoWarning;
case 1: return _LeapIndicator.LastMinute61;
case 2: return _LeapIndicator.LastMinute59;
case 3: goto default;
default:
return _LeapIndicator.Alarm;
}
}
}
// Version Number
public byte VersionNumber
{
get
{
// Isolate bits 3 - 5
byte val = (byte)((SNTPData[0] & 0x38) >> 3);
return val;
}
}
// Mode
public _Mode Mode
{
get
{
// Isolate bits 0 - 3
byte val = (byte)(SNTPData[0] & 0x7);
switch(val)
{
case 0: goto default;
case 6: goto default;
case 7: goto default;
default:
return _Mode.Unknown;
case 1:
return _Mode.SymmetricActive;
case 2:
return _Mode.SymmetricPassive;
case 3:
return _Mode.Client;
case 4:
return _Mode.Server;
case 5:
return _Mode.Broadcast;
}
}
}
// Stratum
public _Stratum Stratum
{
get
{
byte val = (byte)SNTPData[1];
if(val == 0) return _Stratum.Unspecified;
else
if(val == 1) return _Stratum.PrimaryReference;
else
if(val <= 15) return _Stratum.SecondaryReference;
else
return _Stratum.Reserved;
}
}
// Poll Interval (in seconds)
public uint PollInterval
{
get
{
// Thanks to Jim Hollenhorst <hollenho@attbi.com>
return (uint)(Math.Pow(2, (sbyte)SNTPData[2]));
}
}
// Precision (in seconds)
public double Precision
{
get
{
// Thanks to Jim Hollenhorst <hollenho@attbi.com>
return (Math.Pow(2, (sbyte)SNTPData[3]));
}
}
// Root Delay (in milliseconds)
public double RootDelay
{
get
{
int temp = 0;
temp = 256 * (256 * (256 * SNTPData[4] + SNTPData[5]) + SNTPData[6]) + SNTPData[7];
return 1000 * (((double)temp) / 0x10000);
}
}
// Root Dispersion (in milliseconds)
public double RootDispersion
{
get
{
int temp = 0;
temp = 256 * (256 * (256 * SNTPData[8] + SNTPData[9]) + SNTPData[10]) + SNTPData[11];
return 1000 * (((double)temp) / 0x10000);
}
}
// Reference Identifier
public string ReferenceID
{
get
{
string val = "";
switch(Stratum)
{
case _Stratum.Unspecified:
goto case _Stratum.PrimaryReference;
case _Stratum.PrimaryReference:
val += (char)SNTPData[offReferenceID + 0];
val += (char)SNTPData[offReferenceID + 1];
val += (char)SNTPData[offReferenceID + 2];
val += (char)SNTPData[offReferenceID + 3];
break;
case _Stratum.SecondaryReference:
switch(VersionNumber)
{
case 3: // Version 3, Reference ID is an IPv4 address
string Address = SNTPData[offReferenceID + 0].ToString() + "." +
SNTPData[offReferenceID + 1].ToString() + "." +
SNTPData[offReferenceID + 2].ToString() + "." +
SNTPData[offReferenceID + 3].ToString();
try
{
IPHostEntry Host = Dns.GetHostEntry(Address);
val = Host.HostName + " (" + Address + ")";
}
catch(Exception)
{
val = "N/A";
}
break;
case 4: // Version 4, Reference ID is the timestamp of last update
DateTime time = ComputeDate(GetMilliSeconds(offReferenceID));
// Take care of the time zone
TimeSpan offspan = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
val = (time + offspan).ToString();
break;
default:
val = "N/A";
break;
}
break;
}
return val;
}
}
// Reference Timestamp
public DateTime ReferenceTimestamp
{
get
{
DateTime time = ComputeDate(GetMilliSeconds(offReferenceTimestamp));
// Take care of the time zone
TimeSpan offspan = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
return time + offspan;
}
}
// Originate Timestamp (T1)
public DateTime OriginateTimestamp
{
get
{
return ComputeDate(GetMilliSeconds(offOriginateTimestamp));
}
}
// Receive Timestamp (T2)
public DateTime ReceiveTimestamp
{
get
{
DateTime time = ComputeDate(GetMilliSeconds(offReceiveTimestamp));
// Take care of the time zone
TimeSpan offspan = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
return time + offspan;
}
}
// Transmit Timestamp (T3)
public DateTime TransmitTimestamp
{
get
{
DateTime time = ComputeDate(GetMilliSeconds(offTransmitTimestamp));
// Take care of the time zone
TimeSpan offspan = TimeZone.CurrentTimeZone.GetUtcOffset(DateTime.Now);
return time + offspan;
}
set
{
SetDate(offTransmitTimestamp, value);
}
}
// Destination Timestamp (T4)
public DateTime DestinationTimestamp;
// Round trip delay (in milliseconds)
public int RoundTripDelay
{
get
{
// Thanks to DNH <dnharris@csrlink.net>
TimeSpan span = (DestinationTimestamp - OriginateTimestamp) - (ReceiveTimestamp - TransmitTimestamp);
return (int)span.TotalMilliseconds;
}
}
// Local clock offset (in milliseconds)
public int LocalClockOffset
{
get
{
// Thanks to DNH <dnharris@csrlink.net>
TimeSpan span = (ReceiveTimestamp - OriginateTimestamp) + (TransmitTimestamp - DestinationTimestamp);
return (int)(span.TotalMilliseconds / 2);
}
}
// Compute date, given the number of milliseconds since January 1, 1900
private DateTime ComputeDate(ulong milliseconds)
{
TimeSpan span = TimeSpan.FromMilliseconds((double)milliseconds);
DateTime time = new DateTime(1900, 1, 1);
time += span;
return time;
}
// Compute the number of milliseconds, given the offset of a 8-byte array
private ulong GetMilliSeconds(byte offset)
{
ulong intpart = 0, fractpart = 0;
for(int i = 0; i <= 3; i++)
{
intpart = 256 * intpart + SNTPData[offset + i];
}
for(int i = 4; i<=7; i++)
{
fractpart = 256 * fractpart + SNTPData[offset + i];
}
ulong milliseconds = intpart * 1000 + (fractpart * 1000) / 0x100000000L;
return milliseconds;
}
// Compute the 8-byte array, given the date
private void SetDate(byte offset, DateTime date)
{
ulong intpart = 0, fractpart = 0;
DateTime StartOfCentury = new DateTime(1900, 1, 1, 0, 0, 0); // January 1, 1900 12:00 AM
ulong milliseconds = (ulong)(date - StartOfCentury).TotalMilliseconds;
intpart = milliseconds / 1000;
fractpart=((milliseconds % 1000) * 0x100000000L) / 1000;
ulong temp = intpart;
for(int i = 3; i >= 0; i--)
{
SNTPData[offset + i] = (byte) (temp % 256);
temp = temp / 256;
}
temp = fractpart;
for(int i = 7; i >=4; i--)
{
SNTPData[offset + i] = (byte) (temp % 256);
temp = temp / 256;
}
}
// Initialize the NTPClient data
private void Initialize()
{
// Set version number to 4 and Mode to 3 (client)
SNTPData[0] = 0x1B;
// Initialize all other fields with 0
for(int i = 1; i < 48; i++)
{
SNTPData[i] = 0;
}
// Initialize the transmit timestamp
TransmitTimestamp = DateTime.Now;
}
public SNTPClient(string host)
{
TimeServer = host;
}
// Connect to the time server and update system time
public void Connect(bool UpdateSystemTime)
{
try {
// Resolve server address
IPHostEntry hostadd = Dns.GetHostEntry(TimeServer);
IPEndPoint EPhost = new IPEndPoint(hostadd.AddressList[0], 123);
//Connect the time server
UdpClient TimeSocket = new UdpClient();
TimeSocket.Connect(EPhost);
// Initialize data structure
Initialize();
TimeSocket.Send(SNTPData, SNTPData.Length);
SNTPData = TimeSocket.Receive(ref EPhost);
if(!IsResponseValid())
{
throw new Exception("Invalid response from " + TimeServer);
}
DestinationTimestamp = DateTime.Now;
} catch(SocketException e)
{
throw new Exception(e.Message);
}
// Update system time
if(UpdateSystemTime)
{
SetTime();
}
}
// Check if the response from server is valid
public bool IsResponseValid()
{
if(SNTPData.Length < SNTPDataLength || Mode != _Mode.Server)
{
return false;
}
else
{
return true;
}
}
// Converts the object to string
public override string ToString()
{
string str;
str = "Leap Indicator: ";
switch(LeapIndicator)
{
case _LeapIndicator.NoWarning:
str += "No warning";
break;
case _LeapIndicator.LastMinute61:
str += "Last minute has 61 seconds";
break;
case _LeapIndicator.LastMinute59:
str += "Last minute has 59 seconds";
break;
case _LeapIndicator.Alarm:
str += "Alarm Condition (clock not synchronized)";
break;
}
str += "\r\nVersion number: " + VersionNumber.ToString() + "\r\n";
str += "Mode: ";
switch(Mode)
{
case _Mode.Unknown:
str += "Unknown";
break;
case _Mode.SymmetricActive:
str += "Symmetric Active";
break;
case _Mode.SymmetricPassive:
str += "Symmetric Pasive";
break;
case _Mode.Client:
str += "Client";
break;
case _Mode.Server:
str += "Server";
break;
case _Mode.Broadcast:
str += "Broadcast";
break;
}
str += "\r\nStratum: ";
switch(Stratum)
{
case _Stratum.Unspecified:
case _Stratum.Reserved:
str += "Unspecified";
break;
case _Stratum.PrimaryReference:
str += "Primary Reference";
break;
case _Stratum.SecondaryReference:
str += "Secondary Reference";
break;
}
str += "\r\nLocal time: " + TransmitTimestamp.ToString();
str += "\r\nPrecision: " + Precision.ToString() + " s";
str += "\r\nPoll Interval: " + PollInterval.ToString() + " s";
str += "\r\nReference ID: " + ReferenceID.ToString();
str += "\r\nRoot Delay: " + RootDelay.ToString() + " ms";
str += "\r\nRoot Dispersion: " + RootDispersion.ToString() + " ms";
str += "\r\nRound Trip Delay: " + RoundTripDelay.ToString() + " ms";
str += "\r\nLocal Clock Offset: " + LocalClockOffset.ToString() + " ms";
str += "\r\n";
return str;
}
// SYSTEMTIME structure used by SetSystemTime
[StructLayoutAttribute(LayoutKind.Sequential)]
private struct SYSTEMTIME
{
public short year;
public short month;
public short dayOfWeek;
public short day;
public short hour;
public short minute;
public short second;
public short milliseconds;
}
[DllImport("kernel32.dll")]
static extern bool SetLocalTime(ref SYSTEMTIME time);
// Set system time according to transmit timestamp
private void SetTime()
{
SYSTEMTIME st;
// Thanks to Jim Hollenhorst <hollenho@attbi.com>
DateTime trts = DateTime.Now.AddMilliseconds(LocalClockOffset);
st.year = (short)trts.Year;
st.month = (short)trts.Month;
st.dayOfWeek = (short)trts.DayOfWeek;
st.day = (short)trts.Day;
st.hour = (short)trts.Hour;
st.minute = (short)trts.Minute;
st.second = (short)trts.Second;
st.milliseconds = (short)trts.Millisecond;
SetLocalTime(ref st);
}
// The URL of the time server we're connecting to
private string TimeServer;
}
}