PInvoke WIN32 and .NET

The WIN32 API has been around for quite sometime and has a large number of 'calls' and 'mechanisms' that have not yet been ported over to the .NET world. There are also still quite a few valuable WIN32 libraries/exports that have yet to be 'upgraded'. When integration is needed with existing WIN32 applications or APIs from a .NET application the unmanaged WIN32 DLL exports can be accessed using Platform Invoke (also referred to as PInvoke or P/Invoke). I am in the process of moving pieces of code to use the .NET framework. One of the first pieces on my list was the About Box class that I use in my personal applications. This base About Box class I created and use through out most (if not all) of my personal applications. The setting of a few properties has the About Box up and running for a new application in moments. In this About Box class I use the GlobalMemoryStatus function to display virtual and physical memory information. In order to still use this function in my new and 'improved' .NET About Box I needed to use PInvoke.


using System.Runtime.InteropServices;

// define the structure
public struct _MEMORYSTATUS //
public uint dwLength;
public uint dwMemoryLoad;
public uint dwTotalPhys;
public uint dwAvailPhys;
public uint dwTotalPageFile;
public uint dwAvailPageFile;
public uint dwTotalVirtual;
public uint dwAvailVirtual;

[DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
public static extern void GlobalMemoryStatus(out _MEMORYSTATUS memorystatus);

// for simplicity of demonstration
_MEMORYSTATUS memorystatus = new _MEMORYSTATUS();
GlobalMemoryStatus(out memorystatus);
ulong totalVirtualMemory = memorystatus.dwTotalVirtual;
ulong availablePhysicalMemory = memorystatus.dwAvailPhys;
ulong availableVirtualMemory = memorystatus.dwAvailVirtual;
ulong totalPhysicalMemory = memorystatus.dwTotalPhys;


Imports System.Runtime.InteropServices

Public Structure _MEMORYSTATUS
Dim dwLength As Integer
Dim dwMemoryLoad As Integer
Dim dwTotalPhys As Integer
Dim dwAvailPhys
As Integer
Dim dwTotalPageFile As Integer
Dim dwAvailPageFile As Integer
Dim dwTotalVirtual As Integer
Dim dwAvailVirtual As Integer
End Structure

'In VB.NET there are two ways to call this

' Public Shared Sub _
' GlobalMemoryStatus1(ByVal memorystatus As _MEMORYSTATUS)
'End Sub

Declare Auto Sub GlobalMemoryStatus Lib "kernel32" (ByRef lpBuffer As _MEMORYSTATUS)

Dim memorystatus As New _MEMORYSTATUS

Dim totalVirtualMemory As Integer = memorystatus.dwTotalVirtual
Dim availablePhysicalMemory As Integer = memorystatus.dwAvailPhys
Dim availableVirtualMemory As Integer = memorystatus.dwAvailVirtual
Dim totalPhysicalMemory As Integer = memorystatus.dwTotalPhys

Side Note: After having problems with Windows Live Writer after I 'upgraded' to the 'new' Blogger I published this blog entry using Google Docs & Spreadsheets. Curiosity got the best of me and I wanted to see how it worked.

ASP.NET upload a file HtmlInputFile Control

When developing a web application it often may be necessary to allow a user to ‘send’ (upload) a file. With HtmlInputFile control the this seemingly complicated task is much easier than one would expect. The HtmlInputFile control is not listed in the toolbox by default but can be easily added using HTML in your page. In order to use the HtmlInputFile control the following form code must be added to your .aspx page:

<form id="Form1" method="post" runat="server" enctype="multipart/form-data">

<input id="btnSelectFile" type="file" runat="server" style="Z-INDEX: 101; LEFT: 24px; WIDTH: 470px; POSITION: absolute; TOP: 48px; HEIGHT: 22px" size="59">

<asp:Label id="lblStatus" style="Z-INDEX: 103; LEFT: 176px; POSITION: absolute; TOP: 88px" runat="server" Width="224px">Status:</asp:Label>
<asp:Button id="btnUpload" style="Z-INDEX: 102; LEFT: 96px; POSITION: absolute; TOP: 88px" runat="server" Text="Upload"></asp:Button>

The size and position of the controls can be what ever you desire. Once the HtmlInputFile code is added you can visually design its size and position. In the above code I have also included a label for the displaying of status information and a button that will actually execute the code for the uploading of the file selected with the HtmlInputFile.
The code to upload the file is simple:

' Root Data path
‘ ensure the proper permissions are set on this folder default is the ASP.NET account
Const ROOTPATH = "C:\Data\"

Private Sub btnUpload_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnUpload.Click

Dim filename As String

' Extract the selected filename
filename = System.IO.Path.GetFileName(btnSelectFile.PostedFile.FileName)

' Set the label to display where the file will be saved – this could also be used to display the file size uploaded
lblStatus.Text = "Status: " & ROOTPATH & filename

' Save the file
btnSelectFile.PostedFile.SaveAs(ROOTPATH & filename)

' This calls a procedure that I had created that will display the contents of a directory in a table

End Sub

Private Sub ListDirectory()

Dim currentdir As New DirectoryInfo(ROOTPATH)
Dim files As FileInfo
Dim tr As TableRow
Dim tcFile As TableCell
Dim tcSize As TableCell

For Each files In currentdir.GetFiles()
tr = New TableRow
tcFile = New TableCell
tcSize = New TableCell
tcFile.Text = files.Name
tcSize.HorizontalAlign = HorizontalAlign.Right
tcSize.Text = FormatNumber(files.Length, 0, TriState.False, TriState.True, TriState.True)

End Sub

In reviewing the previous code sample one can see how easy it is to upload a file through a web application.

More Hash - Part I

Yesterday I discussed using the System.Security.Cryptography Namespace to compute the hash value of files. Hash values of files can be used to quickly compare two files to see if they are identical. Due to the irreversible nature of Hash values, they are useful in password situations. For example, if you have an application that requires authentication you can compute the hash of a user's password and store that information. When it comes time to authenticate the user you can compare the hash value of the entered password with the stored hash value. This eliminates the storage of the actual password value, which could lead to well, problems. I had put together an application that compares the hash values of two files or strings to determine if the data is identical. This application can also be used to generate hash values. This application used the MD5, SHA1, SHA256, SHA384 and SHA512 classes. The hash values are displayed in Hexadecimal notation. If you're interested in just the application it can be downloaded here. Here is the VB.NET source. I will post the Delphi source later.

Imports System.IO
Imports System.Security.Cryptography
Imports System.Text

Public Class frmMain
Enum HashType
End Enum

Private Sub GroupCompare_CheckedChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles radFiles.CheckedChanged, radStrings.CheckedChanged
Select Case CType(sender, Control).Tag
Case "Files"
lblValue1.Text = "File 1:"
lblValue2.Text = "File 2:"
txtValue1.ReadOnly = True
txtValue2.ReadOnly = True
btnValue1.Visible = True
btnValue2.Visible = True
Case "Strings"
lblValue1.Text = "String 1:"
lblValue2.Text = "String 2:"
txtValue1.ReadOnly = False
txtValue2.ReadOnly = False
btnValue1.Visible = False
btnValue2.Visible = False
End Select
End Sub

Private Sub txt_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) _
Handles txtValue1.TextChanged, txtValue2.TextChanged, _
txtResults1.TextChanged, txtResults2.TextChanged

ToolTip1.SetToolTip(CType(sender, Control), CType(sender, Control).Text)

End Sub

Private Sub btnFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnValue1.Click, btnValue2.Click
If ofdFiles.ShowDialog Then
Select Case CType(sender, Button).Tag
Case 0
txtValue1.Text = ofdFiles.FileName
Case 1
txtValue2.Text = ofdFiles.FileName
End Select
End If
End Sub

Private Sub ClearForm()
txtValue1.Text = ""
txtValue2.Text = ""
txtResults1.Text = ""
txtResults2.Text = ""
End Sub

Private Sub btnCompare_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCompare.Click
Dim myCursor As Cursor
Dim hasht As hashtype

myCursor = Cursor
Cursor = Cursors.WaitCursor
radMD5.Checked Then
hasht = hashtype.MD5
End If
radSHA1.Checked Then
hasht = hashtype.SHA1
End If
radSHA256.Checked Then
hasht = hashtype.SHA256
End If
radSHA384.Checked Then
hasht = hashtype.SHA384
End If
radSHA512.Checked Then
hasht = hashtype.SHA512
End If

If radFiles.Checked Then
txtResults1.Text = GetFileHash(txtValue1.Text, hasht)
txtResults2.Text = GetFileHash(txtValue2.Text, hasht)
ElseIf radStrings.Checked Then
txtResults1.Text = GetStringHash(txtValue1.Text, hasht)
txtResults2.Text = GetStringHash(txtValue2.Text, hasht)
End If

If (String.Compare(txtResults1.Text, txtResults2.Text) = 0) Then
picResult.Image = ImageList1.Images(1)
picResult.Image = ImageList1.Images(0)
End If
Catch ex As Exception
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)
Cursor = myCursor
End Try
End Sub

Private Function GetFileHash(ByVal filename As String, ByVal hasht As hashtype) As String
Dim oFileStream As System.IO.FileStream
Dim lBytes As Long

filename "" Then
Dim instance As New FileInfo(filename)
oFileStream = instance.OpenRead()
lBytes = oFileStream.Length
Dim filecontents(lBytes) As Byte
oFileStream.Read(filecontents, 0, lBytes)

Return GetHash(filecontents, hasht)
End If
Catch ex As Exception
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)
Return ""
End Try

End Function

Private Function GetStringHash(ByVal input As String, ByVal hasht As hashtype) As String

Return GetHash(Encoding.Default.GetBytes(input), hasht)

End Function

Public Function GetHash(ByRef contents As Byte(), ByVal hasht As hashtype) As String
Dim result() As Byte

Select Case hasht
Case hashtype.MD5
Dim MD5 As MD5 = MD5.Create
result = MD5.ComputeHash(contents)
Case hashtype.SHA1
Dim sha1M As New SHA1Managed
result = sha1M.ComputeHash(contents)
Case hashtype.SHA256
Dim sha256M As New SHA256Managed
result = sha256M.ComputeHash(contents)
Case hashtype.SHA384
Dim sha384M As New SHA384Managed
result = sha384M.ComputeHash(contents)
Case hashtype.SHA512
Dim sha512M As New SHA512Managed
result = sha512M.ComputeHash(contents)
End Select

Return GetByteString(result)
End Function

Public Function GetByteString(ByVal data As Byte())
Dim sBuilder As New StringBuilder()
Dim i As Integer

For i = 0 To data.Length - 1
Next i
Return sBuilder.ToString()
End Function
End Class

Is it a Hash Brown?

It has been one crazy semester (I think the lack of activity can vouch for that). I've come up to the surface and see that a lot of the landscape has changed, take the emergence of CodeGear for example. I am hoping this is a breathe of new life that can revitalize the Delphi community and not just a last ditch effort (personally I think the BDS IDE is far better for development than VS). I am optimistic about the whole thing and hope they endure the 'rebirth process'.

As I was submerged in my own little world for a period of time, I had the need to calculate the Hash value for files. This actually turned out to server two purposes. The first being the verification of a file as original (intact) by comparing the hash value of the current and original file. Second, it turned out to be a fast way of identifying identical files. Often times a CRC is used to calculate a checksum, however I opted to make use of the System.Security.Cryptography Namespace. This Namespace has a number of useful hash functions including SHA1, SHA256 and SHA512. Surprisingly (or not) these are relatively easy to use and eliminate the need to formulate the algorithm on your own. Here it is in a couple of worlds:


System.Security.Cryptography, System.IO;

procedure frmMain.ClearForm;
txtSHA1.Text:= '';
txtSHA256.Text:= '';
txtSHA512.Text:= '';

procedure frmMain.txtFileName_TextChanged(sender: System.Object; e: System.EventArgs);

procedure frmMain.btnCalculate_Click(sender: System.Object; e: System.EventArgs);
myCursor: System.Windows.Forms.Cursor;
oFileStream: FileStream;
lBytes: int64;
instance: FileInfo;
filecontents: Array of Byte;
result: Array of Byte;
SHA1M: SHA1Managed;
SHA256M: SHA256Managed;
SHA512M: SHA512Managed;

myCursor:= Cursor;
Cursor:= Cursors.WaitCursor;
if not
(txtFileName.Text='') then

instance:= FileInfo.Create(txtFileName.Text);
oFileStream:= instance.OpenRead;
lBytes:= oFileStream.Length;

SHA1M:= SHA1Managed.Create;
result:= SHA1M.ComputeHash(filecontents);
txtSHA1.Text:= Convert.ToBase64String(result);

SHA256M:= SHA256Managed.Create;
result:= SHA256M.ComputeHash(filecontents);
txtSHA256.Text:= Convert.ToBase64String(result);

SHA512M:= SHA512Managed.Create;
result:= SHA512M.ComputeHash(filecontents);
txtSHA512.Text:= Convert.ToBase64String(result);

ErrorProvider1.SetError(btnFile,'Select a filename');

on e: exception do
MessageBox.Show(e.Message, e.Source, MessageBoxButtons.OK,

Cursor:= myCursor;

procedure frmMain.btnFile_Click(sender: System.Object; e: System.EventArgs);
if (ofdFileName.ShowDialog = System.Windows.Forms.DialogResult.OK) then
txtFileName.Text:= ofdFileName.FileName;


Imports System.Security.Cryptography
Imports System.IO

Public Class frmMain

Private Sub btnFile_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFile.Click
If ofdFileName.ShowDialog Then
txtFileName.Text = ofdFileName.FileName
End If
End Sub

Private Sub txtFileName_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles txtFileName.TextChanged
ToolTip1.SetToolTip(txtFileName, txtFileName.Text)
End Sub

Private Sub ClearForm()
txtSHA1.Text = ""
txtSHA256.Text = ""
txtSHA512.Text = ""
End Sub

Private Sub btnCalculate_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCalculate.Click
Dim myCursor As Cursor
Dim oFileStream As System.IO.FileStream
Dim lBytes As Long
Dim result() As Byte

myCursor = Cursor
Cursor = Cursors.WaitCursor

If Not (txtFileName.Text = "") Then
ErrorProvider1.Clear() 'Introduced .NET 2.0

Dim instance As New FileInfo(txtFileName.Text)
oFileStream = instance.OpenRead()
lBytes = oFileStream.Length
Dim filecontents(lBytes) As Byte
oFileStream.Read(filecontents, 0, lBytes)

Dim sha1M As New SHA1Managed
result = sha1M.ComputeHash(filecontents)
txtSHA1.Text = Convert.ToBase64String(result)

Dim sha256M As New SHA256Managed
result = sha256M.ComputeHash(filecontents)
txtSHA256.Text = Convert.ToBase64String(result)

Dim sha512M As New SHA512Managed
result = sha512M.ComputeHash(filecontents)
txtSHA512.Text = Convert.ToBase64String(result)
ErrorProvider1.SetError(btnFile, "Select a filename")
End If

Catch ex As Exception
MessageBox.Show(ex.Message, ex.Source, MessageBoxButtons.OK, MessageBoxIcon.Error)

Cursor = myCursor
End Try
End Sub

End Class

This is another post done with Live Writer, I think it is pretty 'groovy'.

Adapter Information Round 2

In an earlier post getting local adapter information via the Internet Protocol Helper (IP Helper) was discussed. The .NET Framework version 2.0 has the System.Net.NetworkInformation namespace that provides access to this information. For this sample I used VB.NET, however I will try some 'blogged' tricks to see if I can get this working in BDS® 2006 and see how it all works out.

Imports System.Net.NetworkInformation
Imports System.Net

Public Sub RetrieveLocalAdapterInformation(ByVal text As TextBox)
Dim interfaces As NetworkInterface() 'NIC
Dim netInterface As NetworkInterface ' adapter
Dim properties As IPInterfaceProperties
Dim address As PhysicalAddress
Dim ip As IPAddress
Dim ipinfo As IPAddressInformation


If NetworkInterface.GetIsNetworkAvailable Then
interfaces = NetworkInterface.GetAllNetworkInterfaces

If interfaces.GetLength(0) > 0 Then
For Each netInterface In interfaces
properties = netInterface.GetIPProperties

text.AppendText(netInterface.Name & vbCrLf)
text.AppendText("Id: " & netInterface.Id.ToString & vbCrLf)
address = netInterface.GetPhysicalAddress
text.AppendText("MAC Address: " & (Microsoft.VisualBasic.IIf(address.ToString = String.Empty, "None", address.ToString)) & vbCrLf)
For Each ipinfo In properties.UnicastAddresses
text.AppendText("IP: " & ipinfo.Address.ToString & vbCrLf)
For Each ip In properties.DhcpServerAddresses
text.AppendText("DHCP Server: " & ip.ToString & vbCrLf)
For Each ip In properties.DnsAddresses
text.AppendText("DNS Server: " & ip.ToString & vbCrLf)
text.AppendText("Type: " & netInterface.NetworkInterfaceType.ToString & vbCrLf)
text.AppendText("Operational Status: " & netInterface.OperationalStatus.ToString & vbCrLf)
text.AppendText("Speed: " & netInterface.Speed.ToString("N") & " bytes" & vbCrLf)

' XP Only
'text.AppendText("Receive Only: " & netInterface.IsReceiveOnly.ToString & vbCrLf)

' XP Only
'text.AppendText("Support Multicast: " & netInterface.SupportsMulticast.ToString & vbCrLf)

text.AppendText("Support IPv4: " & netInterface.Supports(NetworkInterfaceComponent.IPv4).ToString & vbCrLf)
text.AppendText("Support IPv6: " & netInterface.Supports(NetworkInterfaceComponent.IPv6).ToString & vbCrLf)
text.AppendText("DnsSuffix: " & properties.DnsSuffix.ToString & vbCrLf)
text.AppendText("" & vbCrLf)
End If
End If
End Sub

Reading Stuff

Information in this document subject to change without notice.
All Software source code published is for demonstration and knowledge sharing purposes only. The Code is supplied "as is" without warranty as to result, performance or merchantability. Use at your own risk.
The opinions expressed herein are the opinions of the author and do not reflect those of any other entity.