active directory - How to read "uSNChanged" property using C#

Question

I want to get the last modified or created attributes via the uSNChanged value in ActiveDirectory using C# ... I was also trying to find the max value of uSNChanged, can you help me to find out the solution? Thanks

Answer 1

There are two ways to retrieve the uSNChanged property via .NET:

1. Include a reference to a COM library: "Active DS Type Library", then you need to use the IADsLargeInterger to retrieve the value and finally convert it to a long. For example:

   IADsLargeInteger li_ad = (IADsLargeInteger)oUser.Properties["USNChanged"].Value;
   long l_uChanged = GetLongFromLargeInteger( li_ad );
   
   static long GetLongFromLargeInteger(  IADsLargeInteger  Li )
   {
       long retval = Li.HighPart;
       retval <<=32;
       retval |=(uint)Li.LowPart;
       return retval;
   }
   

2. Translate the values only using C#. Thanks to Simon Gilbee, we have this option:

    long usnChanged = ConvertADSLargeIntegerToInt64(oUser.Properties["USNChanged"].Value);
   
    public static Int64 ConvertADSLargeIntegerToInt64(object adsLargeInteger)
    {
      var highPart = (Int32)adsLargeInteger.GetType().InvokeMember("HighPart", System.Reflection.BindingFlags.GetProperty, null, adsLargeInteger, null);
      var lowPart  = (Int32)adsLargeInteger.GetType().InvokeMember("LowPart",  System.Reflection.BindingFlags.GetProperty, null, adsLargeInteger, null);
      return highPart * ((Int64)UInt32.MaxValue + 1) + lowPart;
    }
   

I highly recommend you go with Option #2 to avoid problems with the legacy ActiveDs library and won't need answers off this list.