Hello everyone,

I am trying to write some code to check the AD password age during a user login and notify them of the 15 remaining days. I am using the ASP.Net code that I found on the Microsoft MSDN site and I managed to add a function that checks the if the account is set to change password at next login. The login and the change password at next login works great but I am having some problems with the check for the password age.

This is the VB.Net code for the DLL file:

Imports System
Imports System.Text
Imports System.Collections
Imports System.DirectoryServices
Imports System.DirectoryServices.AccountManagement
Imports System.Reflection 'Needed by the Password Expiration Class Only -Vince

Namespace FormsAuth
    Public Class LdapAuthentication

    Dim _path As String
    Dim _filterAttribute As String
    'Code added for the password expiration added by Vince
    Private _domain As DirectoryEntry
    Private _passwordAge As TimeSpan = TimeSpan.MinValue
    Const UF_DONT_EXPIRE_PASSWD As Integer = &H10000

    'Function added by Vince
    Public Sub New()

        Dim root As New DirectoryEntry("LDAP://rootDSE")

        root.AuthenticationType = AuthenticationTypes.Secure
        _domain = New DirectoryEntry("LDAP://" & root.Properties("defaultNamingContext")(0).ToString())
        _domain.AuthenticationType = AuthenticationTypes.Secure
    End Sub

    'Function added by Vince
    Public ReadOnly Property PasswordAge() As TimeSpan
        Get
            If _passwordAge = TimeSpan.MinValue Then

                Dim ldate As Long = LongFromLargeInteger(_domain.Properties("maxPwdAge")(0))

                _passwordAge = TimeSpan.FromTicks(ldate)
            End If

            Return _passwordAge
        End Get
    End Property

    Public Sub New(ByVal path As String)
        _path = path
    End Sub

    'Function added by Vince 
    Public Function DoesUserHaveToChangePassword(ByVal userName As String) As Boolean

        Dim ctx As PrincipalContext = New PrincipalContext(System.DirectoryServices.AccountManagement.ContextType.Domain)
        Dim up = UserPrincipal.FindByIdentity(ctx, userName)
        Return (Not up.LastPasswordSet.HasValue)
        'returns true if last password set has no value.

    End Function

    Public Function IsAuthenticated(ByVal domain As String, ByVal username As String, ByVal pwd As String) As Boolean

        Dim domainAndUsername As String = domain & "\" & username
        Dim entry As DirectoryEntry = New DirectoryEntry(_path, domainAndUsername, pwd)

        Try
            'Bind to the native AdsObject to force authentication.   
            Dim obj As Object = entry.NativeObject
            Dim search As DirectorySearcher = New DirectorySearcher(entry)

            search.Filter = "(SAMAccountName=" & username & ")"
            search.PropertiesToLoad.Add("cn")
            Dim result As SearchResult = search.FindOne()

            If (result Is Nothing) Then
                Return False
            End If

            'Update the new path to the user in the directory.
            _path = result.Path
            _filterAttribute = CType(result.Properties("cn")(0), String)

        Catch ex As Exception
            Throw New Exception("Error authenticating user. " & ex.Message)
        End Try

        Return True
    End Function

    Public Function GetGroups() As String
        Dim search As DirectorySearcher = New DirectorySearcher(_path)
        search.Filter = "(cn=" & _filterAttribute & ")"
        search.PropertiesToLoad.Add("memberOf")
        Dim groupNames As StringBuilder = New StringBuilder()

        Try
            Dim result As SearchResult = search.FindOne()
            Dim propertyCount As Integer = result.Properties("memberOf").Count

            Dim dn As String
            Dim equalsIndex, commaIndex

            Dim propertyCounter As Integer

            For propertyCounter = 0 To propertyCount - 1
                dn = CType(result.Properties("memberOf")(propertyCounter), String)

                equalsIndex = dn.IndexOf("=", 1)
                commaIndex = dn.IndexOf(",", 1)
                If (equalsIndex = -1) Then
                    Return Nothing
                End If

                groupNames.Append(dn.Substring((equalsIndex + 1), (commaIndex - equalsIndex) - 1))
                groupNames.Append("|")
            Next

        Catch ex As Exception
            Throw New Exception("Error obtaining group names. " & ex.Message)
        End Try

        Return groupNames.ToString()
    End Function

    'Function added by Vince 
    Public Function WhenExpires(ByVal username As String) As TimeSpan

        Dim ds As New DirectorySearcher(_domain)

        ds.Filter = [String].Format("(&(objectClass=user)(objectCategory=person)(sAMAccountName={0}))", username)

        Dim sr As SearchResult = FindOne(ds)
        Dim user As DirectoryEntry = sr.GetDirectoryEntry()
        Dim flags As Integer = CInt(user.Properties("userAccountControl").Value)

        If Convert.ToBoolean(flags And UF_DONT_EXPIRE_PASSWD) Then
            'password never expires
            Return TimeSpan.MaxValue
        End If

        'get when they last set their password
        Dim pwdLastSet As DateTime = DateTime.FromFileTime(LongFromLargeInteger(user.Properties("pwdLastSet").Value))

        ' return pwdLastSet.Add(PasswordAge).Subtract(DateTime.Now);
        If pwdLastSet.Subtract(PasswordAge).CompareTo(DateTime.Now) > 0 Then

            Return pwdLastSet.Subtract(PasswordAge).Subtract(DateTime.Now)
        Else
            Return TimeSpan.MinValue
            'already expired
        End If
    End Function

    'Function added by Vince 
    Private Function LongFromLargeInteger(ByVal largeInteger As Object) As Long

        Dim type As System.Type = largeInteger.[GetType]()
        Dim highPart As Integer = CInt(type.InvokeMember("HighPart", BindingFlags.GetProperty, Nothing, largeInteger, Nothing))
        Dim lowPart As Integer = CInt(type.InvokeMember("LowPart", BindingFlags.GetProperty, Nothing, largeInteger, Nothing))

        Return CLng(highPart) << 32 Or CUInt(lowPart)
    End Function

    'Function added by Vince 
    Private Function FindOne(ByVal searcher As DirectorySearcher) As SearchResult

        Dim sr As SearchResult = Nothing
        Dim src As SearchResultCollection = searcher.FindAll()

        If src.Count > 0 Then
            sr = src(0)
        End If

        src.Dispose()

        Return sr
    End Function

End Class
End Namespace

And this is the Login.aspx page:

sub Login_Click(sender as object,e as EventArgs)
        Dim adPath As String = "LDAP://DC=xxx,DC=com" 'Path to your LDAP directory server
        Dim adAuth As LdapAuthentication = New LdapAuthentication(adPath)

    Try
        If (True = adAuth.DoesUserHaveToChangePassword(txtUsername.Text)) Then
            Response.Redirect("passchange.htm")


        ElseIf (True = adAuth.IsAuthenticated(txtDomain.Text, txtUsername.Text, txtPassword.Text)) Then
            Dim groups As String = adAuth.GetGroups()

            'Create the ticket, and add the groups.
            Dim isCookiePersistent As Boolean = chkPersist.Checked
            Dim authTicket As FormsAuthenticationTicket = New FormsAuthenticationTicket(1, _
                 txtUsername.Text, DateTime.Now, DateTime.Now.AddMinutes(60), isCookiePersistent, groups)

            'Encrypt the ticket.
            Dim encryptedTicket As String = FormsAuthentication.Encrypt(authTicket)

            'Create a cookie, and then add the encrypted ticket to the cookie as data.
            Dim authCookie As HttpCookie = New HttpCookie(FormsAuthentication.FormsCookieName, encryptedTicket)

            If (isCookiePersistent = True) Then
                authCookie.Expires = authTicket.Expiration
            End If
            'Add the cookie to the outgoing cookies collection.
            Response.Cookies.Add(authCookie)

'Retrieve the password life
Dim t As TimeSpan = adAuth.WhenExpires(txtUsername.Text)

            'You can redirect now.
            If (passAge.Days = 90)  Then
               errorLabel.Text = "Your password will expire in " & DateTime.Now.Subtract(t)
   'errorLabel.Text = "This is"
               'System.Threading.Thread.Sleep(5000)
               Response.Redirect("http://somepage.aspx")

            Else

              Response.Redirect(FormsAuthentication.GetRedirectUrl(txtUsername.Text, False))

            End If

            Else
                errorLabel.Text = "Authentication did not succeed. Check user name and password."
            End If

    Catch ex As Exception
        errorLabel.Text = "Error authenticating. " & ex.Message
    End Try
End Sub

`

Every time I have this Dim t As TimeSpan = adAuth.WhenExpires(txtUsername.Text) enabled, I receive "Arithmetic operation resulted in an overflow." during the login and won't continue.

What am I doing wrong? How can I correct this? Please help!!

Thank you very much for any help in advance.

Vince