Jason Shuler's Tech Blog

Don’t listen to the internet – getting account information from active directory for the current user is simple and easy in Visual Basic .NET – particularly if you are using Framework 3.5.

You don’t need to do any stinking LDAP queries, or lookups, or credential passings – it’s all made simple using System.DirectoryServices.AccountManagement. Observe.

First, go to the references tab in project properties, click add reference, and find “System.DirectoryServices.AccountManagement” – no need to add “System.DirectoryServices”.

Now, in your application, add the following lines:

Dim currentADUser As System.DirectoryServices.AccountManagement.UserPrincipal
currentADUser = System.DirectoryServices.AccountManagement.UserPrincipal.Current

(It’s even simpler if you import the namespace)

Poof. That’s it! You are done.

currentADUser is a strongly typed object containing attributes for most of the active directory properties you need = such as display name, email address, primary group membership, exchange mailbox info, etc, etc.

Say you want to get the current user’s email address. You could do it like so (after the previous code):

Dim userEmail as string = currentADUser.EmailAddress

That’s it. 1 additional line.

How about a concrete example – here is the problem I wanted to solve. Send an email message from the current user for error reporting – Make sure to change the To: email address, and the smtp server name, and this should be a drop-in solution:

  Private Sub report_error(ByVal errorMessage As String)
    Dim currentADUser As System.DirectoryServices.AccountManagement.UserPrincipal
    currentADUser = System.DirectoryServices.AccountManagement.UserPrincipal.Current
    Dim mailClient As New System.Net.Mail.SmtpClient("smtpserver.company.local")
    mailClient.Send(currentADUser.DisplayName & " <" & currentADUser.EmailAddress & ">", _
                    "notifications@company.com", _
                    "ERROR REPORT: Application error for " & currentADUser.DisplayName, _
                    errorMessage)
  End Sub

Hope this helps!

If you have purchased a Virgin Mobile Broadband2Go pay as you go aircard (actually a novatell wireless ovation MC760), and find that the driver installation hangs on Windows 7, you will also find that the internet is little help.

The solution is to disable USB Selective Suspending until Virgin Mobile releases a driver version later than 2.02.04.002

http://shup.com/oqo/OQO%20Drivers/02+/2009.01.15/WWAN/Drivers/Novatel/Driver%20Installer%20Release%20Notes%20v2.02.04.002.pdf

Here is the link to the release notes for the OQO drivers – which are newer that either the Virgin Mobile or Novatel generic drivers.

You disable USB selective suspend from the advanced power settings screen.

The following is my description of how I figured out how to decode the D-Link settings file. If you don’t care how I figured it out, skip to the end for VB.Net code samples and an executable.

I have a DIR-628 wireless router that is having issues. There is a firmware update available, but my issue is not mentioned in the readme for the firmware.
Normally when I upgrade the firmware, I will dump out a settings file, perform the upgrade, reload the settings file, and rejoice in the time saved not having to reconfigure. This time, though, I think I would like to have a clean slate – but there are some options that include passwords I don’t recall offhand, so I figure I can just dump out the settings file, and take a look at it to get all that info…

Wrong. The settings file is binary gobbledeygook.
The default file name is gateway_settings.gws, and the file is about 175k.

I gave Google a thorough searching, and had no luck – it looks like other people are searching for GWS format, or GWS file, but there were no meaningful pages that I could find.
Next I downloaded trid_w32 – a neat little utility for identifying file types. I thought maybe it was compressed or something…
No dice.

So I decided to use the reverse engineering method – make some changes, and observe the result in the file.
I created a firewall rule named “AAAAAAAAAAAA”, and saved the settings; then renamed the rule to “BBBBBBBBBBBB”, and use a nice binary comparison tool (HexCmp in this case) to see what my changes did.

The A’s within the file had become “78 79 7A 7B 7C 7D 7E…” – they were shifted, but that offset increased by 1 for each character. This I can fix!

I then decoded the character before the first A – it was a “>”. Could it be? Could this file really be XML??
Worked backwards a couple more characters and had “name>AAAA…” – yes indeed! The decoded file will be XML!!

The next question was where to begin – what will be the shift of the first character? If the file is xml, I can be pretty sure the first character is a “<" - and this is the first character of the .gws file.

After much fooling around in VB.net, and battling with modulus math, I had the encoder formula:
encodedByte = (positionNbr + CharacterCode) mod 256

Decoding was a bit trickier, because as long as (position mod 256) + characterCode is less than 256, you can just subtract. If it is greater than 256, you have to work a bit harder. If I had more time, I bet there is a way to write a single formula to restore the character code, but I was able to do it with an IF statement.

Here is the VB.net function for decoding a byte array containing the .gws file

  Function decodeGWS(ByRef encodedGWS As Byte()) As String
    Dim chrMax As UInteger
    Dim decodedGWS As Char()
    chrMax = encodedGWS.GetUpperBound(0)
    ReDim decodedGWS(chrMax)

    For i As UInteger = 0 To chrMax
      If encodedGWS(i) < (i Mod 256) Then
        decodedGWS(i) = Chr((256 + encodedGWS(i)) - (i Mod 256))
      Else
        decodedGWS(i) = Chr(encodedGWS(i) - (i Mod 256))
      End If
    Next i

    Return decodedGWS
  End Function

And it works like a charm. The file is actually a great big XML containing all the available options.

Here is the little utility I wrote to decode the file:
GWS Decoder Utility

For completeness sake, I included encoder functionality, and I have verified that the output is identical to the original file when no changes are made to the xml file, but I really don’t know what would happen if you tried to make changes to the XML and load it back onto your router. If you want to try it, don’t come crying to me when your router gives up it’s magic smoke, or your house burns down.

Hopefully somebody finds this helpful!