birt upc-a

birt upc-a

birt upc-a

birt barcode maximo, birt barcode plugin, birt code 128, birt code 39, birt data matrix, birt gs1 128, birt ean 13, birt pdf 417, birt qr code, birt upc-a

You can also disable request validation for an entire web application by modifying the web.config file. Add or set the validateRequest attribute of the <pages> element, as shown here: <configuration> <system.web> <!-- Other settings omitted. --> <pages validateRequest="false" /> </system.web> </configuration> Now, consider what happens if you attempt to display the user-supplied value in a label with this code: Protected Sub cmdSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdSubmit.Click lblInfo.Text = "You entered: " + txtInput.Text End Sub If a malicious user enters the text <script>alert('Script Injection');</script>, the returned web page will execute the script, as shown in Figure 34-8.

The HTML input controls allow for user interaction. These include the familiar graphical widgets, including check boxes, text boxes, buttons, and list boxes. All of these controls are generated with the <input> tag. The type attribute indicates the type of input control, as in <input type="text"> (a text box), <input type="submit"> (a submit button), and <input type="file"> (controls for uploading a file). Server-side input controls derive from HtmlInputControl, which adds the properties shown in Table 4-5. Table 4-5. HtmlInputControl Properties

Keep in mind that the script in a script injection attack is always executed on the client end. However, this doesn t mean it s limited to a single user. In many situations, user-supplied data is stored in a location such as a database and can be viewed by other users. For example, if a user supplies a script block for a business name when adding a business to a registry, another user who requests a full list of all businesses in the registry will be affected. To prevent a script injection attack from happening when request validation is turned off, you need to explicitly encode the content before you display it using the Server object, as described earlier in this chapter. Here s a rewritten version of the Button.Click event handler that isn t susceptible to script injection attacks: Protected Sub cmdSubmit_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdSubmit.Click lblInfo.Text = "You entered: " + Server.HtmlEncode(txtInput.Text) End Sub Figure 34-9 shows the result of an attempted script injection attack on this page.

GetSchema()

Gets the unique identifier name for the HtmlInputControl. Gets the type of an HtmlInputControl. For example, if this property is set to text, the HtmlInputControl is a text box for data entry. Gets or sets the value associated with an input control. The value associated with a control depends on the type of control. For example, in a text box this property contains the text entered in the control. For buttons, this defines the text on the button.

JavaScript plays an important role in many advanced web controls. In an ideal world, the web-page developer never needs to worry about JavaScript. Instead, web-page developers would program with neat object-oriented controls that render the JavaScript they need to optimize their appearance and their performance. This gives you the best of both worlds object-oriented programming on the server and the client-side frills of JavaScript. You can create any number of controls with JavaScript and the HTML document model. Common examples include rich menus, specialized trees, and advanced grids, many of which are available (some for free) at Microsoft s http://www.asp.net community site. In the following sections, you ll consider two custom controls that use JavaScript a pop-up window generator and a rollover button.

12 discussed the XmlReader and XmlWriter classes in detail. Using them is quite straightforward. Here s an example of a custom class that handles its own XML generation: public class EmployeeDetailsCustom : IXmlSerializable { public int ID; public string FirstName; public string LastName; const string ns = "http://www.apress.com/ProASP.NET/CustomEmployeeDetails"; void IXmlSerializable.WriteXml(XmlWriter w) { w.WriteStartElement("Employee", ns); w.WriteStartElement("Name", ns); w.WriteElementString("First", ns, FirstName); w.WriteElementString("Last", ns, LastName); w.WriteEndElement(); w.WriteElementString("ID", ns, ID.ToString()); w.WriteEndElement(); } void IXmlSerializable.ReadXml(XmlReader r) { r.MoveToContent(); r.ReadStartElement("Employee"); r.ReadStartElement("Name"); FirstName = r.ReadElementString("First", ns); LastName = r.ReadElementString("Last", ns); r.ReadEndElement(); r.MoveToContent(); ID = Int32.Parse(r.ReadElementString("ID", ns)); reader.ReadEndElement(); }

Table 4-6 lists all the available HTML server controls and the specific properties and events that each one adds to the base class. As noted earlier, the declaration of HTML server controls on the page is the same as what you use for normal static HTML tags, with the addition of the