/// <summary>
/// Get DateTime from NTP Server
/// Based on:
/// http://weblogs.asp.net/mschwarz/archive/2008/03/09/wrong-datetime-on-net-micro-framework-devices.aspx
/// </summary>
/// <param name="timeServer">Time Server (NTP) address</param>
/// <param name="timeZoneOffset">Difference in hours from UTC</param>
/// <returns>Local NTP Time</returns>
private static DateTime GetNtpTime(String timeServer, int timeZoneOffset)
{
try
{
DebugUtils.Print(DebugLevel.INFO, "Searching for time server dns endpoint...");
// Find endpoint for TimeServer
var ep = new IPEndPoint(Dns.GetHostEntry(timeServer).AddressList[0], 123);
// Make send/receive buffer
var ntpData = new byte[48];
DebugUtils.Print(DebugLevel.INFO, "Trying to connect to time server...");
// Connect to TimeServer
using (var s = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp))
{
// Set 10s send/receive timeout and connect
s.SendTimeout = s.ReceiveTimeout = 10000; // 10,000 ms
s.Connect(ep);
// Set protocol version
ntpData[0] = 0x1B;
// Send Request
s.Send(ntpData);
// Receive Time
s.Receive(ntpData);
// Close the socket
s.Close();
DebugUtils.Print(DebugLevel.INFO, "Time data successfully received.");
}
const byte offsetTransmitTime = 40;
ulong intpart = 0;
ulong fractpart = 0;
for (var i = 0; i <= 3; i++)
{
intpart = (intpart << 8) | ntpData[offsetTransmitTime + i];
}
for (var i = 4; i <= 7; i++)
{
fractpart = (fractpart << 8) | ntpData[offsetTransmitTime + i];
}
ulong milliseconds = (intpart * 1000 + (fractpart * 1000) / 0x100000000L);
var timeSpan = TimeSpan.FromTicks((long)milliseconds * TimeSpan.TicksPerMillisecond);
var dateTime = new DateTime(1900, 1, 1);
dateTime += timeSpan;
var offsetAmount = new TimeSpan(timeZoneOffset, 0, 0);
var networkDateTime = (dateTime + offsetAmount);
return(networkDateTime);
}
catch (Exception)
{
DebugUtils.Print(DebugLevel.WARNING, "Failed to connect to time server.");
return(DateTime.MinValue);
}
}