CodeXchange: User Contributed Snippets

Shutdown, Restart, LogOff or Lock Workstation

Mark Brackett — Tue, 13 Dec 2005 12:49:11 GMT

Imports System
' Import used for DLLImport Attribute
Imports System.Runtime.InteropServices

Public Module Shutdown
	' Constants
	Private Const SE_PRIVILEGE_ENABLED As Integer = &H2
	Private Const TOKEN_QUERY As Integer = &H8
	Private Const TOKEN_ADJUST_PRIVILEGES As Integer = &H20
	Private Const SE_SHUTDOWN_NAME As String = "SeShutdownPrivilege"
	' Exit Windows Constants
	Private Const EWX_LOGOFF As Integer = &H0
	Private Const EWX_SHUTDOWN As Integer = &H1
	Private Const EWX_REBOOT As Integer = &H2
	Private Const EWX_FORCE As Integer = &H4
	Private Const EWX_POWEROFF As Integer = &H8
	Private Const EWX_FORCEIFHUNG As Integer = &H10

	'Structure
	 _
	Private Structure Luid
		Public Count As Integer
		Public Luid As Long
		Public Attr As Integer
	End Structure	'TokPriv1Luid

	' Lock Workstation
	 _
	Private Function LockWorkStation() As Boolean
	End Function

	' Get Current Processes
	 _
	Private Function GetCurrentProcess() As IntPtr
	End Function

	' Open Process Token
	 _
	Private Function OpenProcessToken(ByVal h As IntPtr, ByVal acc As Integer, ByRef phtok As IntPtr) As Boolean
	End Function

	' Look up Priviledge Value
	 _
	Private Function LookupPrivilegeValue(ByVal host As String, ByVal name As String, ByRef pluid As Long) As Boolean
	End Function

	' Adjust Token Priviledges
	 _
	Private Function AdjustTokenPrivileges(ByVal htok As IntPtr, ByVal disall As Boolean, ByRef newst As Luid, ByVal len As Integer, ByVal prev As IntPtr, ByVal relen As IntPtr) As Boolean
	End Function

	' Exit Windows
	 _
	Private Function ExitWindowsEx(ByVal flg As Integer, ByVal rea As Integer) As Boolean
	End Function

	' Exit Windows Sub
	Private Sub DoExitWindows(ByVal flg As Integer)
		Dim tp As Luid
		Dim hproc As IntPtr = GetCurrentProcess()
		Dim htok As IntPtr = IntPtr.Zero
		OpenProcessToken(hproc, TOKEN_ADJUST_PRIVILEGES Or TOKEN_QUERY, htok)
		tp.Count = 1
		tp.Luid = 0
		tp.Attr = SE_PRIVILEGE_ENABLED
		LookupPrivilegeValue(Nothing, SE_SHUTDOWN_NAME, tp.Luid)
		AdjustTokenPrivileges(htok, False, tp, 0, IntPtr.Zero, IntPtr.Zero)
		ExitWindowsEx(flg, 0)
	End Sub

	' Shutdown
	Public Sub Shutdown()
		DoExitWindows(EWX_SHUTDOWN)
	End Sub

	' Restart
	Public Sub Restart()
		DoExitWindows(EWX_REBOOT Or EWX_FORCE)
	End Sub

	' Log off
	Public Sub LogOff()
		DoExitWindows(EWX_LOGOFF)
	End Sub

	' Lock Workstation
	Public Sub LockTheComputer()
		LockWorkStation()
	End Sub
End Module

Test an Ip Address to see if it's contained in a subnet

Mark Brackett — Tue, 21 Feb 2006 09:44:16 GMT

	Public Function ContainsAddress(ByVal ip As Net.IPAddress) As Boolean
		' Could just use ip.Address, but it's marked as Obsolete
		Return ((BitConverter.ToInt32(HostAddress.GetAddressBytes, 0) And BitConverter.ToInt32(SubnetMask.GetAddressBytes, 0)) _
		 = (BitConverter.ToInt32(ip.GetAddressBytes, 0) And BitConverter.ToInt32(SubnetMask.GetAddressBytes, 0)))
	End Function

Cidr to a Netmask

Mark Brackett — Tue, 21 Feb 2006 09:43:35 GMT

	Public Shared Function CidrToNetmask(ByVal cidr As Integer) As Net.IPAddress
		If cidr < 0 OrElse cidr > 32 Then
			Throw New ArgumentException("cidr must be between 0 and 32")
		End If

		Dim s As String = String.Empty
		Dim post, remainder As Integer
		Dim divide As Double
		remainder = cidr Mod 8
		divide = cidr / 8

		Do While (divide > 0)
			s &= "255."
			divide -= 1
			post += 1
		Loop

		If remainder > 0 Then
			s &= ((0 Or CType(Math.Pow(2, (remainder - 1)), Integer)) << (8 - remainder)).ToString & "."
			post += 1
		End If

		Do While post < 4
			s &= "0."
			post += 1
		Loop

		If s.EndsWith("."c) Then
			Return Net.IPAddress.Parse(s.Substring(0, s.LastIndexOf("."c)))
		Else
			Return Net.IPAddress.Parse(s)
		End If
	End Function