c#得到局域网共享剩余空间

[DllImport( " kernel32.dll ")]
         private  static  extern  bool GetDiskFreeSpaceEx(
         string lpDirectoryName,  out  ulong lpFreeBytesAvailable,  out  ulong lpTotalNumberOfBytes,  out  ulong lpTotalNumberOfFreeBytes);

         ///   <summary>
         ///  取得磁盘剩余空间
         ///   </summary>
         ///   <param name="driveDirectoryName"> 驱动器名 </param>
         ///   <returns> 剩余空间 </returns>
         private  ulong GetFreeSpace( string driveDirectoryName)
        {
             ulong freeBytesAvailable, totalNumberOfBytes, totalNumberOfFreeBytes;
            GetDiskFreeSpaceEx(driveDirectoryName,  out freeBytesAvailable,  out totalNumberOfBytes,  out totalNumberOfFreeBytes);
             return freeBytesAvailable;
        }

ulong u = GetFreeSpace(@"\\10.222.1.1\shares");

MessageBox.Show(u.ToString());

网上找了下只能用API得到剩余空间大小, DriveInfo类只支持本地驱动器, 不支持UNC路径.