UTILISATION DE L'API SENDMESSAGE ENTRE DEUX APPLICATIONS VB.NET

Client
======

Imports System.Runtime.InteropServices

Public Class MyWinForm

    Enum AllocationType
        Commit = &H1000
        Reserve = &H2000
        Decommit = &H4000
        Release = &H8000
        Reset = &H80000
        Physical = &H400000
        TopDown = &H100000
        WriteWatch = &H200000
        LargePages = &H20000000
    End Enum

    Enum MemoryProtection
        Execute = &H10
        ExecuteRead = &H20
        ExecuteReadWrite = &H40
        ExecuteWriteCopy = &H80
        NoAccess = &H1
        ReadOnlyFlag = &H2
        ReadWrite = &H4
        WriteCopy = &H8
        GuardModifierFlag = &H100
        NoCacheModifierFlag = &H200
        WriteCombineModifierFlag = &H400
    End Enum

    ' Win32 déclarations

    Declare Function SendMessage Lib "user32.dll" Alias "SendMessageA" _
        (ByVal hWnd As IntPtr, ByVal wCmd As Integer, _
        ByVal wParam As IntPtr, ByVal lParam As IntPtr) As IntPtr

    Declare Function WriteProcessMemory Lib "kernel32.dll" _
        (ByVal hProcess As IntPtr, ByVal lpBaseAddress As IntPtr, _
        ByVal lpBuffer As IntPtr, ByVal nSize As Integer, _
        ByVal lpNumberOfBytesWritten As IntPtr) As IntPtr

    Declare Function VirtualAllocEx Lib "kernel32.dll" _
        (ByVal hProcess As IntPtr, ByVal lpAddress As IntPtr, _
        ByVal dwSize As UInteger, ByVal flAllocationType As AllocationType, _
        ByVal flProtect As MemoryProtection) As IntPtr

    Private Structure MyStructure
        Dim ddd As Double
        Dim sss As IntPtr   ' For Ansi String
        Dim iii As Integer
    End Structure

    Private Const TARGET_WINDOW_TITLE As String = "MyWindow"    ' For example !

    Private Sub btnStructureBySendMessage_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles btnStructureBySendMessage.Click

        Try

            Dim local_processes() As Process = Process.GetProcesses()

            If local_processes.Length > 0 Then
                For Each p As Process In local_processes
                    If p.MainWindowTitle = TARGET_WINDOW_TITLE Then

                        Dim my_struct As MyStructure
                        my_struct.ddd = 100.28  ' For example !
                        my_struct.iii = 258955  ' For example !

                        Dim ansi_str As String = "hello world !"
                        Dim ansi_len As Integer = Marshal.SizeOf("c"c) * ansi_str.Length

                        Dim str_ptr As IntPtr = VirtualAllocEx(p.Handle, IntPtr.Zero, _
                            CUInt(ansi_len), _
                            AllocationType.Commit, MemoryProtection.ReadWrite)

                        my_struct.sss = str_ptr

                        Dim tmp_str_ptr As IntPtr = Marshal.StringToHGlobalAnsi(ansi_str)

                        WriteProcessMemory(p.Handle, str_ptr, tmp_str_ptr, ansi_len, IntPtr.Zero)
                        Marshal.FreeHGlobal(tmp_str_ptr)

                        Dim tmp_struct_ptr As IntPtr = Marshal.AllocHGlobal(Marshal.SizeOf(my_struct))
                        Marshal.StructureToPtr(my_struct, tmp_struct_ptr, True)

                        Dim my_struct_ptr As IntPtr = VirtualAllocEx(p.Handle, IntPtr.Zero, _
                            CUInt(Marshal.SizeOf(GetType(MyStructure))), _
                            AllocationType.Commit, MemoryProtection.ReadWrite)

                        WriteProcessMemory(p.Handle, my_struct_ptr, tmp_struct_ptr, _
                            Marshal.SizeOf(my_struct), IntPtr.Zero)
                        Marshal.FreeHGlobal(tmp_struct_ptr)

                        Dim w_param As New IntPtr(15)   ' For example !

                        Dim sm_res As IntPtr = _
                            SendMessage(p.MainWindowHandle, 100355, w_param, my_struct_ptr)

                        Exit For
                    End If
                Next
            End If

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

    Private Sub btnSendAnsiString_Click(ByVal sender As System.Object, _
        ByVal e As System.EventArgs) Handles btnSendAnsiString.Click

        Try

            Dim local_processes() As Process = Process.GetProcesses()

            If local_processes.Length > 0 Then
                For Each p As Process In local_processes
                    If p.MainWindowTitle = TARGET_WINDOW_TITLE Then

                        Dim ansi_str As String = "look at this my friends ..."  ' For example !
                        Dim ansi_len As Integer = Marshal.SizeOf("c"c) * ansi_str.Length

                        Dim str_ptr As IntPtr = VirtualAllocEx(p.Handle, IntPtr.Zero, _
                            CUInt(ansi_len), _
                            AllocationType.Commit, MemoryProtection.ReadWrite)

                        Dim tmp_str_ptr As IntPtr = Marshal.StringToHGlobalAnsi(ansi_str)

                        WriteProcessMemory(p.Handle, str_ptr, tmp_str_ptr, ansi_len, IntPtr.Zero)
                        Marshal.FreeHGlobal(tmp_str_ptr)

                        Dim w_param As New IntPtr(255)  ' For example !

                        Dim sm_res As IntPtr = _
                            SendMessage(p.MainWindowHandle, 100255, w_param, str_ptr)

                        Exit For
                    End If
                Next
            End If

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub
End Class


serveur
=======

Public Class frmAccueil

    Private Structure MyStructure
        Dim ddd As Double
        Dim sss As IntPtr   ' For Ansi String
        Dim iii As Integer
    End Structure

    Protected Overrides Sub WndProc(ByRef m As Message)

        Select Case (m.Msg)
            Case 100255 ' A String should be sent

                ' First thing : we get the integer value stored in wParam
                Dim i As Integer = m.WParam.ToInt32

                Console.WriteLine("wParam is : '" + i.ToString + "'")

                ' Second thing : lParam pointer must be converted to ansi String
                Dim ansi_str As String = Marshal.PtrToStringAnsi(m.LParam)

                Console.WriteLine("lParam is : '" + ansi_str + "'")

            Case 100355 ' A Structure should be sent

                ' First thing : we get the integer value stored in wParam
                Dim i As Integer = m.WParam.ToInt32

                Console.WriteLine("wParam is : " + i.ToString)

                ' Second thing : lParam pointer must be converted to structure
                Dim o As Object = Marshal.PtrToStructure(m.LParam, GetType(MyStructure))
                Dim my_struct As MyStructure = CType(o, MyStructure)

                ' Third thing : 'sss' field of structure must be converted to ansi String
                Dim ansi_sss As String = Marshal.PtrToStringAnsi(my_struct.sss)

                Console.WriteLine("lParam is : ddd='" + my_struct.ddd.ToString + "'" _
                    + " sss='" + ansi_sss.ToString + "'" _
                    + " iii='" + my_struct.iii.ToString + "'")

        End Select

        MyBase.WndProc(m)   ' very important !

    End Sub
End Class