ASP.NET 4 in VB 2010 : The Security Controls

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The basic membership features are a remarkable time-saver. They allow you to concentrate on programming your web application, without worrying about managing security and crafting the perfect database or user information. Instead, you can use the higher-level Membership and MembershipUser classes to do everything you need.

However, the ASP.NET membership feature doesn't stop there. Not only does the Membership class simplify common security tasks, it also standardizes them. As a result, other components and controls can use the Membership class to integrate themselves with the ASP.NET security model, without worrying about the specifics of each web application. You can find the best example of this new flexibility in ASP.NET's security controls. These controls interact with the membership provider using the methods of the Membership and MembershipUser classes to implement common bits of user interfaces such as a login page, a set of user creation controls, and a password recovery wizard.

Table 1 lists all the ASP.NET security controls that work with membership. In Visual Studio, you can find these controls in the Login section of the Toolbox.

Table 1. Security Controls
LoginDisplays the familiar user name and password text boxes, with a login button.
LoginStatusShows a login button, if the user isn't already logged in, that redirects the user to the configured login page. Otherwise, it displays a sign-out button. You can choose the test used for the login and sign-out buttons, but that's about it.
LoginNameDisplays the user name of the logged-in user.
LoginViewDisplays different content depending on whether the user is logged in. You can even use this control to show different content for different groups of users, or roles.
PasswordRecoveryAllows the user to request a password via e-mail or reset it. Typically, the user must supply the answer to the security question to get the password.
ChangePasswordAllows the user to set a new password (as long as the user can supply the current password).
CreateUserWizardAllows a user to create a new record, complete with e-mail address and a password question and answer.

There is a simple way and a complex way to use most of these controls. At their simplest, you merely drop the control on a page, without writing a line of code. (You saw this approach with the CreateUserWizard control at the beginning of this chapter.) You can also modify properties, handle events, and even create templates to customize these controls.

In the following sections, you'll take a closer look at the Login, PasswordRecovery, and CreateUserWizard controls. And later, in the "Role-Based Security" section, you'll put the LoginView control to work to show different content to users in different roles.

1. The Login Control

So far, the secure websites you've seen have used handmade login pages. In many websites this is what you'll want—after all, it gives you complete control to adjust the user interface exactly the way you want it. However, a login page is standard, so it makes sense for ASP.NET to give developers some extra shortcuts that can save them work.

Along these lines, ASP.NET includes a Login control that pairs a user name and a password text box with a login button. The Login control also adds a few features:

  • It includes validator controls that prevent the page from being posted back until a user name and password have been entered. These validators use client-side validation if it's supported by the browser (with the help of a bit of JavaScript) and server-side validation.

  • It automatically handles the signing in and redirection process when the user logs in successfully. If invalid login credentials are entered, it shows an error message.

  • It provides a Remember Me check box that, if selected, stores a persistent cookie that remains indefinitely on the user's computer; therefore, the user doesn't need to log back in at the beginning of each visit.

In other words, if the basic Login control is right for your needs (it gives the user interface you want), you won't need to write a line of code.

To try this, drop the Login control onto a new page. Make sure this page is named Login.aspx so it's used as the default login page for forms authentication (or edit the <forms> tag to choose a different login page, as explained in the previous chapter). Then, run the page. You'll see the basic interface shown in Figure 1.

Figure 1. The Login control and a failed login attempt

Although the Login control takes care of the login process for you automatically, you can step in with your own custom code. To do so, you must react to one of the Login control events, as listed in Table 2.

Table 2. Events of the Login Control
LoggingInRaised before the user is authenticated.
LoggedInRaised after the user has been authenticated by the control.
LoginErrorRaised when the login attempt fails (for example, if the user enters the wrong password).
AuthenticateRaised to authenticate the user. If you handle this event, it's up to you to supply the login code—the Login control won't perform any action.

The LoggingIn, LoggedIn, and LoginError events are primarily useful if you want to update other controls to display certain information based on the login process. For example, after the first login failure, you might choose to show a link that redirects the user to a password retrieval page:

Protected Sub Login1_LoginError(ByVal sender As Object,
ByVal e As EventArgs) Handles Login1.LoginError

lblStatus.Text = "Have you forgotten your password?"
lnkRedirectToPasswordRetrieval.Visible = True
End Sub

The Authenticate event is the most important event. It allows you to write your own authentication logic, as you did in the previous chapter. This is typically useful in two situations. First, you might want to supplement the default checking in the Login control with other requirements (for example, prevent any users from logging in at specific times of day, allow users to log in only if they've entered information in another control, and so on). The other reason you might handle the Authenticate event is if you aren't using the membership provider at all. In this case, you can still use the Login control, as long as you provide the authentication logic.

In the Authenticate event handler, you can check the user name and password using the UserName and Password properties of the Login control. You then set the Authenticated property of the AuthenticateEventArgs to True or False. If True, the LoggedIn event is raised next, and then the user is redirected to the Login.DestinationPageUrl (or the original page the user came from if the DestinationPageUrl property is not set). If you set Authenticated to False, the LoginError event is raised next, and the control displays the error message defined by the Login.FailureText property.

Here's an event handler for the Authenticated event that uses the membership classes directly:

Protected Sub Login1_Authenticate(ByVal sender As Object, _
ByVal e As AuthenticateEventArgs) Handles Login1.Authenticate

If Membership.ValidateUser(Login1.UserName, Login1.Password) Then
e.Authenticated = True
e.Authenticated = False
End If
End Sub

That covers everything you need to know about interacting with the Login control, but you can tweak many properties to configure the appearance of the Login control. There's even an Auto Format link you can choose from the Properties window (or the smart tag) to give the Login control a face-lift with a single click.

The most powerful formatting properties for the Login control are style properties, which allow you to tweak fonts, coloring, and alignment for individual parts of the control. You've already seen styles at work with several other controls, including the Calendar  and the GridView , and they work in the same way with the security controls. Table 3 details the style properties of the Login control.

Table 3. Style Properties of the Login Control
TitleTextStyleDefines a style for the title text of the Login control.
LabelStyleDefines the style for the Username and Password labels.
TextBoxStyleDefines the style for the user name and password text boxes.
LoginButtonStyleDefines the style for the login button.
FailureTextStyleDefines the style for the text displayed if the login attempt fails.
CheckBoxStyleDefines the style properties for the Remember Me check box.
ValidatorTextStyleDefines styles for RequiredFieldValidator controls that validate the user name and password information. These style properties tweak how the error text looks. (By default, the error text is simply an asterisk that appears next to the empty text box.)
HyperLinkStyleConfigures all the links that the Login control shows. This includes the links that let you create a new user record, retrieve a password, and so on. These links appear only if you've set the CreateUserUrl and PasswordRecoveryUrl properties.
InstructionTextStyleFormats the Login.InstructionText, which is help instruction text you can add under the Login control. By default, the Login control has no instruction text.

Of course, styles aren't the only feature you can change in the Login control. You can adjust several properties to change the text it uses and to add links. For example, the following tag for the Login control adjusts the formatting and uses the CreateUserUrl and PasswordRecoveryUrl properties to add links to a page for registering a new user and another for recovering a lost password. (Obviously, you'll need to create both of these pages in order for the links to work.)

<asp:Login ID="Login1" runat="server" BackColor="#EFF3FB" BorderColor="#B5C7DE"
BorderPadding="4" BorderStyle="Solid" BorderWidth="1px" Font-Names="Verdana"
ForeColor="#333333" Height="256px" Width="368px"
CreateUserText="Register for the first time"
PasswordRecoveryText="Forgot your password?"
"Please enter your username and password for logging into the system.">

<TitleTextStyle BackColor="#507CD1" Font-Bold="True" Font-Size="Large"
ForeColor="White" Height="35px" />
<InstructionTextStyle Font-Italic="True" ForeColor="Black" />
<LoginButtonStyle BackColor="White" BorderColor="#507CD1"

BorderStyle="Solid" BorderWidth="1px" Font-Names="Verdana"
ForeColor="#284E98" />


Figure 2 shows the revamped Login control. Table 4 explains the other properties of the Login control.

Figure 2. A formatted Login control

Table 4. Useful Properties of the Login Control
TitleTextThe text that's displayed in the heading of the control.
InstructionTextThe text that's displayed just below the heading but above the login controls. By default, the Login control has no instruction text.
FailureTextThe text that's displayed when a login attempt fails.
UserNameLabelTextThe text that's displayed before the user name text box.
PasswordLabelTextThe text that's displayed before the password text box.
UsernameRequiredErrorMessageThe error message that's shown by the RequiredFieldValidator if the user doesn't type in a user name. By default, this is simply an asterisk (*).
PasswordRequiredError MessageThe error message that's shown by the RequiredFieldValidator if the user doesn't type in a password. By default, this is simply an asterisk (*).
LoginButtonTextThe text displayed for the login button.
LoginButtonTypeThe type of button control that's used as the login button. It can be displayed as Link, Button, or Image.
LoginButtonImageUrlThe URL that points to the image you want to display for the login button. You must set the LoginButtonStyle property to Image to use this property.
DestinationPageUrlThe page to which the user is redirected if the login attempt is successful. This property is blank by default, which means the Login control uses the forms infrastructure and redirects the user to the originally requested page (or to the defaultUrl configured in web.config file).
DisplayRememberMeDetermines whether the Remember Me check box will be shown. You may want to remove this option to ensure stricter security, so malicious users can't gain access to your website through another user's computer.
RememberMeSetSets the default value for the Remember Me check box. By default, this option is set to False, which means the check box is not checked initially.
VisibleWhenLoggedInIf set to False, the Login control automatically hides itself if the user is already logged in. If set to True (the default), the Login control is displayed even if the user is already logged in.
CreateUserUrlSupplies a URL to a user registration page. This property is used in conjunction with the CreateUserText.
CreateUserTextSets the text for a link to the user registration page. If this text is not supplied, this link is not displayed in the Login control.
CreateUserIconUrlSupplies a URL to an image that will be displayed alongside the CreateUserText for the user registration link.
HelpPageUrlSupplies a URL to a page with help information.
HelpPageTextSets the text for the link to the help page. If this text is not supplied, this link is not displayed in the Login control.
HelpPageIconUrlSupplies a URL to an image that will be displayed alongside the HelpPageText for the help page link.
PasswordRecoveryUrlSupplies a URL to a password recovery page.
PasswordRecoveryTextSets the text for the link to the password recovery page. If this text is not supplied, this link is not displayed in the Login control.
PasswordRecoveryIcon UrlSupplies a URL to an image that will be displayed alongside the PasswordRecoveryText for the password recovery page link.

To round out the example in Figure 20-8, you must create the Register.aspx and PasswordRecovery.aspx pages. In the next sections, you'll learn how you can do this easily using two more of the ASP.NET security controls.

2. The CreateUserWizard Control

You already used the CreateUserWizard control to create a basic user record at the beginning of this chapter. Now that you've seen the flexibility of the Login control, it should come as no surprise to learn that you have just as many options for tweaking the appearance and behavior of the CreateUserWizard control.

The CreateUserWizard control operates in two steps. The first step collects the user information that's needed to generate the user record. The second step displays a confirmation message once the account is created.

Overall, the CreateUserWizard provides a dizzying number of properties you can adjust. However, it helps to understand that really only three types of properties exist:

Style properties that format just a section of the control:

For example, TitleTextStyle configures how the text heading is formatted.

Properties that set the text for the control:

For example, you can configure each label, the success text, and the messages shown under different error conditions. You can also retrieve or set the values in each text box.

Properties that hide or show a part of the control:

For example, you can use DisplaySideBar, DisplayCancelButton, and RequireEmail to show or hide the sidebar, cancel button, and e-mail text box, respectively.

The CreateUserWizard control also provides a familiar set of events, including CreatingUser, CreatedUser, and CreateUserError. Once again, these events are handy for synchronizing other controls on the page or for overriding the user creation process if you decide not to use the membership features.

By default, newly created users are automatically logged in. You can change this behavior by setting the CreateUserWizard.LoginCreatedUser property to False. You can also set the ContinueDestinationPageUrl property to set the URL where the user should be redirected once the new record is created.

As a result, you can add as many extra steps as you want, just as you can with the Wizard control. These steps might perform other tasks, such as signing the user up to receive a regular newsletter. However, the actual user creation process must always take place in a single step.

For example, consider the markup for the basic CreateUserWizard:

<asp:CreateUserWizard ID="CreateUserWizard1" runat="server">
<asp:CreateUserWizardStep runat="server">
<asp:CompleteWizardStep runat="server">

Essentially, the CreateUserWizard is a Wizard control that supports two specialized step types: a CreateUserWizardStep where the user information is collected and the user record is created, and a CompleteWizardStep where the confirmation message is shown.

The following example shows how you can add an ordinary WizardStep into this sequence. In this case, the extra step simply provides some additional options for the newly created user (namely, the choice to subscribe to automatic e-mail newsletters).

<asp:CreateUserWizard ID="CreateUserWizard1" runat="server"
DisplaySideBar="True" ... >
<asp:CreateUserWizardStep runat="server" Title="Create User">

<asp:WizardStep runat="server" Title="Subscribe">
Would you like to sign up for the following newsletters?<br />
<br />
<asp:CheckBoxList ID="chkSubscription" runat="server">
<asp:ListItem>MSN Today</asp:ListItem>
<asp:ListItem>VB Planet</asp:ListItem>
<asp:ListItem>The High-Tech Herald</asp:ListItem>

<asp:CompleteWizardStep runat="server">

Figure 3 shows the first two steps. Notice that the sidebar appears (because the CreateUserWizard.DisplaySidebar property is set to True) to show the order of steps.

Figure 3. A CreateUserWizard with a custom step

It's still up to you to take the appropriate action in your code by reacting to one of the CreateUserWizard events. In this case, you use the FinishButtonClick event, because it occurs on the last step before the completion message. If you place your step earlier in the sequence, you'll need to react to NextButtonClick. In the current example, you might want to add this information to the user's profile table. You'll learn how to use profiles in the next chapter.

For complete layout and formatting power, you can convert one of the CreateUserWizard steps into a template. You're then free to rearrange the existing content and add new controls and HTML content. However, be careful not to remove any of the required elements. The CreateUserWizard will throw an exception if you try to use it but you're missing one of the required text boxes for account information.

The easiest way to convert a step into a template is to use the smart tag links. First, select the CreateUserControl on the design surface of your web page in Visual Studio. Next, click the arrow icon that appears next to the top-right corner to show the smart tag. Then, select the Customize Create User Step link or the Customize Complete Step link, depending on which step you want to modify. ASP.NET will then insert the controls into a template in the CreateUserWizard control tag.

For example, imagine you want to show the options the user selected in your custom step in the final summary. In this case, you might want to add a new Label control, as shown here:

<asp:CompleteWizardStep ID="CompleteWizardStep1" runat="server">
<table border="0" style="...">
<td align="center" colspan="2" style="...">
Your account has been successfully created.<br /><br />

You subscribed to:
<asp:Label ID="lblSubscriptionList" runat="server">
<td align="right" colspan="2">
<asp:Button ID="ContinueButton" runat="server"
BackColor="White" BorderColor="#507CD1"
BorderStyle="Solid" BorderWidth="1px"
CausesValidation="False" CommandName="Continue"
Font-Names="Verdana" ForeColor="#284E98" Text="Continue"
ValidationGroup="CreateUserWizard1" />

Now, when the user moves to the last step, you can fill in the label with the information from the CheckBoxList control. However, because the Label and CheckBoxList controls are placed inside a template, you can't access them directly by name. Instead, you need to extract them from the CreateUserWizard control. To get the label, you need to access the complete step, grab the first control it contains (which is the content template), and then use the FindControl() method to search for the label. To get the CheckBoxList, you perform a similar operation, except you can use the FindControl() method of the CreateWizardControl itself, which searches all ordinary steps.

Here's the code that performs this task:

Protected Sub CreateUserWizard1_FinishButtonClick(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.WizardNavigationEventArgs) _
Handles CreateUserWizard1.FinishButtonClick

Dim lbl As Label
lbl = CType(CreateUserWizard1.CompleteStep.Controls(0).FindControl( _
"lblSubscriptionList"), Label)
Dim chk As CheckBox
chk = CType(CreateUserWizard1.FindControl("chkSubscription"), CheckBox)

Dim selection As String = ""
For Each item As ListItem in chk.Items
If item.Selected Then
selection &= "<br />" & item.Text
End If
lbl.Text = selection
End Sub

Figure 4 shows the final step.

Figure 4. Enhancing the complete step with extra content

3. The PasswordRecovery Control

The PasswordRecovery control comes in handy when users forget their passwords. It allows them to retrieve their password using a short wizard.

The PasswordRecovery control leads the user through three steps. First, it requests the user name. Next, it shows the security question and requests the answer (unless you've set the requiresQuestionAndAnswer setting to false in the web.config file, in which case the PasswordRecovery control skips this step altogether). Finally, the PasswordRecovery control sends an e-mail to the user's e-mail address. If you use a password format of Encrypted or Clear , the e-mail contains the original password. If you are using the default password format Hashed, a new random password is generated, and that password is sent in the e-mail. Either way, the last step shows a confirmation message informing you that the e-mail was sent. Figure 5 shows the PasswordRecovery control in action.

Figure 5. Requesting a password

For the PasswordRecovery control to do its work, your computer must have a correctly configured SMTP server, and the user must have an e-mail address in the user record.


You can configure your SMTP server by selecting the PasswordRecovery control and choosing Administer Website from the smart tag. Then, choose the Application tab, and click the Configure SMTP E-mail Settings link.

If your application doesn't meet these two requirements—you can't send e-mail messages, or users aren't guaranteed to have an e-mail address—you can display the new password directly in the page. The easiest approach is to handle the PasswordRecovery.SendingMail event. First, set the MailMessageEventArgs.Cancel property to True to prevent the message from being sent. Next, you can retrieve the message content from the MailMessageEventArgs.Message object and display it on the page. Here's an example:

Protected Sub PasswordRecovery1_SendingMail(ByVal sender As Object, _
ByVal e As System.Web.UI.WebControls.MailMessageEventArgs) _
Handles PasswordRecovery1.SendingMail

e.Cancel = True
PasswordRecovery1.SuccessText = e.Message.Body
End Sub

When you use this event handler, you'll see a final step like the one shown in Figure 6.

Figure 6. Displaying the retrieved or regenerated password

Of course, for complete flexibility you can create your own page that resets passwords. You just need to use the methods of the Membership and MembershipUser classes described earlier.

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