internal static bool IsUserInAdminGroup()

in Lib/Utils/Elevation.cs [24:134]
83 lines of code
14 McCabe index (conditional complexity)

        internal static bool IsUserInAdminGroup()
        {
            bool fInAdminGroup = false;
            SafeTokenHandle? hToken = null;
            SafeTokenHandle? hTokenToCheck = null;
            IntPtr pElevationType = IntPtr.Zero;
            IntPtr pLinkedToken = IntPtr.Zero;
            int cbSize = 0;

            try
            {
                // Open the access token of the current process for query and duplicate.
                if (!NativeMethods.OpenProcessToken(Process.GetCurrentProcess().Handle,
                    NativeMethods.TOKEN_QUERY | NativeMethods.TOKEN_DUPLICATE, out hToken))
                {
                    throw new Win32Exception();
                }

                // Determine whether system is running Windows Vista or later operating systems (major version
                // >= 6) because they support linked tokens, but previous versions (major version < 6) do not.
                if (Environment.OSVersion.Version.Major >= 6)
                {
                    // Running Windows Vista or later (major version >= 6). Determine token type: limited,
                    // elevated, or default.

                    // Allocate a buffer for the elevation type information.
                    cbSize = sizeof(TOKEN_ELEVATION_TYPE);
                    pElevationType = Marshal.AllocHGlobal(cbSize);
                    if (pElevationType == IntPtr.Zero)
                    {
                        throw new Win32Exception();
                    }

                    // Retrieve token elevation type information.
                    if (!NativeMethods.GetTokenInformation(hToken,
                        TOKEN_INFORMATION_CLASS.TokenElevationType, pElevationType,
                        cbSize, out cbSize))
                    {
                        throw new Win32Exception();
                    }

                    // Marshal the TOKEN_ELEVATION_TYPE enum from native to .NET.
                    TOKEN_ELEVATION_TYPE elevType = (TOKEN_ELEVATION_TYPE)
                        Marshal.ReadInt32(pElevationType);

                    // If limited, get the linked elevated token for further check.
                    if (elevType == TOKEN_ELEVATION_TYPE.TokenElevationTypeLimited)
                    {
                        // Allocate a buffer for the linked token.
                        cbSize = IntPtr.Size;
                        pLinkedToken = Marshal.AllocHGlobal(cbSize);
                        if (pLinkedToken == IntPtr.Zero)
                        {
                            throw new Win32Exception();
                        }

                        // Get the linked token.
                        if (!NativeMethods.GetTokenInformation(hToken,
                            TOKEN_INFORMATION_CLASS.TokenLinkedToken, pLinkedToken,
                            cbSize, out cbSize))
                        {
                            throw new Win32Exception();
                        }

                        // Marshal the linked token value from native to .NET.
                        IntPtr hLinkedToken = Marshal.ReadIntPtr(pLinkedToken);
                        hTokenToCheck = new SafeTokenHandle(hLinkedToken);
                    }
                }

                // CheckTokenMembership requires an impersonation token. If we just got a linked token, it
                // already is an impersonation token. If we did not get a linked token, duplicate the original
                // into an impersonation token for CheckTokenMembership.
                if (hTokenToCheck == null)
                {
                    if (!NativeMethods.DuplicateToken(hToken,
                        SECURITY_IMPERSONATION_LEVEL.SecurityIdentification,
                        out hTokenToCheck))
                    {
                        throw new Win32Exception();
                    }
                }

                // Check if the token to be checked contains admin SID.
                using WindowsIdentity id = new WindowsIdentity(hTokenToCheck.DangerousGetHandle());
                WindowsPrincipal principal = new WindowsPrincipal(id);
                fInAdminGroup = principal.IsInRole(WindowsBuiltInRole.Administrator);
            }
            finally
            {
                // Centralized cleanup for all allocated resources.
                if (hToken != null)
                {
                    hToken.Close();
                }
                if (hTokenToCheck != null)
                {
                    hTokenToCheck.Close();
                }
                if (pElevationType != IntPtr.Zero)
                {
                    Marshal.FreeHGlobal(pElevationType);
                }
                if (pLinkedToken != IntPtr.Zero)
                {
                    Marshal.FreeHGlobal(pLinkedToken);
                }
            }

            return fInAdminGroup;
        }