Set time programmatically using C#

Question

What is the best way to set the time on a remote machine remotely? The machine is running Windows XP and is receiving the new time through a web service call. The goal is

Answer 1

This is the Win32 API call for setting system time:

[StructLayout(LayoutKind.Sequential)] 
public struct SYSTEMTIME { 
 public short wYear; 
 public short wMonth; 
 public short wDayOfWeek; 
 public short wDay; 
 public short wHour; 
 public short wMinute; 
 public short wSecond; 
 public short wMilliseconds; 
 } 
 [DllImport("kernel32.dll", SetLastError=true)] 
public static extern bool SetSystemTime(ref SYSTEMTIME theDateTime ); 

I'm not exactly sure how you would get the security worked out such that you could execute that function on the client, though.

You can get a lot more detail on setting system time at PInvoke.

Answer 2

Here's the routine I have been using for years to read the DateTime value off our our SQL Server (using file time), convert it to a SYSTEMTIME that is set on the PC.

This works for PCs and Windows Mobile devices.

It can be called anytime you happen to be calling your SQL Server.

public class TimeTool {

  private static readonly DateTime NODATE = new DateTime(1900, 1, 1);

#if PocketPC
  [DllImport("coredll.dll")]
#else
  [DllImport("kernel32.dll")]
#endif
  static extern bool SetLocalTime([In] ref SYSTEMTIME lpLocalTime);

  public struct SYSTEMTIME {
    public short Year, Month, DayOfWeek, Day, Hour, Minute, Second, Millisecond;
    /// <summary>
    /// Convert form System.DateTime
    /// </summary>
    /// <param name="time">Creates System Time from this variable</param>
    public void FromDateTime(DateTime time) {
      Year = (short)time.Year;
      Month = (short)time.Month;
      DayOfWeek = (short)time.DayOfWeek;
      Day = (short)time.Day;
      Hour = (short)time.Hour;
      Minute = (short)time.Minute;
      Second = (short)time.Second;
      Millisecond = (short)time.Millisecond;
    }

    public DateTime ToDateTime() {
      return new DateTime(Year, Month, Day, Hour, Minute, Second, Millisecond);
    }

    public static DateTime ToDateTime(SYSTEMTIME time) {
      return time.ToDateTime();
    }
  }

  // read SQL Time and set time on device
  public static int SyncWithSqlTime(System.Data.SqlClient.SqlConnection con) {
    SYSTEMTIME systemTime = new SYSTEMTIME();
    DateTime sqlTime = NODATE;
    string sql = "SELECT GETDATE() AS [CurrentDateTime]";
    using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sql, con)) {
      try {
        cmd.Connection.Open();
        System.Data.SqlClient.SqlDataReader r = cmd.ExecuteReader();
        while (r.Read()) {
          if (!r.IsDBNull(0)) {
            sqlTime = (DateTime)r[0];
          }
        }
      } catch (Exception) {
        return -1;
      }
    }
    if (sqlTime != NODATE) {
      systemTime.FromDateTime(sqlTime); // Convert to SYSTEMTIME
      if (SetLocalTime(ref systemTime)) { //Call Win32 API to set time
        return 1;
      }
    }
    return 0;
  }

}

Answer 3

The way to query a network machine for it's system time is NetRemoteTOD.

Here's code to do it in Delphi (a usage example is posted below).

Since it relies on Windows API calls, it shouldn't be too different in C#.

unit TimeHandler;

interface

type
  TTimeHandler = class
  private
    FServerName : widestring;
  public
    constructor Create(servername : widestring);
    function RemoteSystemTime : TDateTime;
    procedure SetLocalSystemTime(settotime : TDateTime);
  end;

implementation

uses
  Windows, SysUtils, Messages;

function NetRemoteTOD(ServerName :PWideChar; var buffer :pointer) : integer; stdcall; external 'netapi32.dll';
function NetApiBufferFree(buffer : Pointer) : integer; stdcall; external 'netapi32.dll';

type
  //See MSDN documentation on the TIME_OF_DAY_INFO structure.
  PTime_Of_Day_Info = ^TTime_Of_Day_Info;
  TTime_Of_Day_Info = record
    ElapsedDate : integer;
    Milliseconds : integer;
    Hours : integer;
    Minutes : integer;
    Seconds : integer;
    HundredthsOfSeconds : integer;
    TimeZone : LongInt;
    TimeInterval : integer;
    Day : integer;
    Month : integer;
    Year : integer;
    DayOfWeek : integer;
  end;

constructor TTimeHandler.Create(servername: widestring);
begin
  inherited Create;
  FServerName := servername;
end;

function TTimeHandler.RemoteSystemTime: TDateTime;
var
  Buffer : pointer;
  Rek : PTime_Of_Day_Info;
  DateOnly, TimeOnly : TDateTime;
  timezone : integer;
begin
  //if the call is successful...
  if 0 = NetRemoteTOD(PWideChar(FServerName),Buffer) then begin
    //store the time of day info in our special buffer structure
    Rek := PTime_Of_Day_Info(Buffer);

    //windows time is in GMT, so we adjust for our current time zone
    if Rek.TimeZone <> -1 then
      timezone := Rek.TimeZone div 60
    else
      timezone := 0;

    //decode the date from integers into TDateTimes
    //assume zero milliseconds
    try
      DateOnly := EncodeDate(Rek.Year,Rek.Month,Rek.Day);
      TimeOnly := EncodeTime(Rek.Hours,Rek.Minutes,Rek.Seconds,0);
    except on e : exception do
      raise Exception.Create(
                             'Date retrieved from server, but it was invalid!' +
                             #13#10 +
                             e.Message
                            );
    end;

    //translate the time into a TDateTime
    //apply any time zone adjustment and return the result
    Result := DateOnly + TimeOnly - (timezone / 24);
  end  //if call was successful
  else begin
    raise Exception.Create('Time retrieval failed from "'+FServerName+'"');
  end;

  //free the data structure we created
  NetApiBufferFree(Buffer);
end;

procedure TTimeHandler.SetLocalSystemTime(settotime: TDateTime);
var
  SystemTime : TSystemTime;
begin
  DateTimeToSystemTime(settotime,SystemTime);
  SetLocalTime(SystemTime);
  //tell windows that the time changed
  PostMessage(HWND_BROADCAST,WM_TIMECHANGE,0,0);
end;

And here is the usage example:

procedure TfrmMain.SynchLocalTimeWithServer;
var
  tod : TTimeHandler;
begin
  tod := TTimeHandler.Create(cboServerName.Text);
  try
    tod.SetLocalSystemTime(tod.RemoteSystemTime);
  finally
    FreeAndNil(tod);
  end;  //try-finally
end;

Answer 4

You could also probably do this in a batch file using some combination of

TIME

to set the time, and

net time \\server_name

to retrieve the time from a server.

Answer 5

I would use Windows built-in internet time abilities. You can set up a time server on your server, have it get time from a 2nd-tier timeserver, and have all your client machines get time from it.

I've been down the application-setting-system-time road before.