BindToTypePolicy.QueryNonTrustedTypeValidation Event

Allows you to validate blacklisted and “unknown” types.

Namespace: DevExpress.Utils

Assembly: DevExpress.Data.v23.2.dll

NuGet Package: DevExpress.Data

Declaration

C#

public static event BindToTypePolicy.WeakEventHandler<BindToTypePolicy.QueryNonTrustedTypeValidationEventArgs> QueryNonTrustedTypeValidation

VB.NET

Public Shared Event QueryNonTrustedTypeValidation As BindToTypePolicy.WeakEventHandler(Of BindToTypePolicy.QueryNonTrustedTypeValidationEventArgs)

Event Data

The QueryNonTrustedTypeValidation event's data class is BindToTypePolicy.QueryNonTrustedTypeValidationEventArgs. The following properties provide information specific to this event:

Property	Description
AssemblyName	Gets the assembly name. Inherited from BindToTypePolicy.BindToTypeBaseQueryArgs.
AssemblyQualifiedTypeName	Gets the assembly-qualified name of the type, which includes the name of the assembly from which this Type object is being loaded.
Cancel	Gets or sets a value indicating whether the event should be canceled. Inherited from CancelEventArgs.
IsKnownType	Gets whether the type is whitelisted (the type is safe). Inherited from BindToTypePolicy.BindToTypeBaseQueryArgs.
IsKnownTypeDescendant	Gets whether the type derives from the “safe” type.
IsMalformedOrCorrupted	Gets whether the type is malformed (invalid).
IsUnsafe	Gets whether the type is unsafe.
QueryLevel	This member supports the internal infrastructure and is not intended to be used directly from your code. Inherited from BindToTypePolicy.BindToTypeBaseQueryArgs.
TypeName	Gets the type name.

The event data class exposes the following methods:

Method	Description
DoNotTrustThisType()	Specifies that the custom (“unknown”) type is “unsafe” and throws a security warning.
TrustThisType(Boolean)	Specifies that the custom (“unknown”) type is “safe” and suppresses a security warning.

Remarks

Note

The BindToTypePolicy does not fire the QueryNonTrustedTypeValidation event to allowed/trusted types.

DevExpress controls generate a security warning if an untrusted type is detected during deserialization. The QueryNonTrustedTypeValidation event allows you to validate custom types and trust custom types based on a condition (to suppress security warnings).

Use the e.TrustThisType() or e.DoNotTrustThisType method to specify whether or not to trust a custom type (throw a security warning).

Use the following event parameters to identify whether the loaded type is “safe”:

• e.IsUnsafe
• e.IsMalformedOrCorrupted
• e.IsKnownTypeDescendant

Read the following topic for more information and examples: Safe Deserialization.

Example

The following example validates custom data types:

C#

using System;
using System.Windows.Forms;

namespace DXApplication {
    internal static class Program {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main() {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            DevExpress.Utils.BindToTypePolicy.QueryNonTrustedTypeValidation += BindToTypePolicy_QueryNonTrustedTypeValidation;
            Application.Run(new Form1());
        }
        private static void BindToTypePolicy_QueryNonTrustedTypeValidation(object sender, DevExpress.Utils.BindToTypePolicy.QueryNonTrustedTypeValidationEventArgs e) {
            if (e.IsUnsafe)
                throw new MyAppLicationSecurityException(e.AssemblyQualifiedTypeName);
            if (e.AssemblyName == typeof(Program).Assembly.FullName)
                e.TrustThisType();
            if (e.TypeName == "ObsoleteJsonDataSource")
                e.DoNotTrustThisType();
        }
    }
}

VB.NET

Imports System
Imports System.Windows.Forms

Namespace DXApplication
    Friend Module Program
        ''' <summary>
        ''' The main entry point for the application.
        ''' </summary>
        <STAThread>
        Sub Main()
            Application.EnableVisualStyles()
            Application.SetCompatibleTextRenderingDefault(False)
            AddHandler DevExpress.Utils.BindToTypePolicy.QueryNonTrustedTypeValidation, AddressOf BindToTypePolicy_QueryNonTrustedTypeValidation
            Application.Run(New Form1())
        End Sub
        Private Sub BindToTypePolicy_QueryNonTrustedTypeValidation(ByVal sender As Object, ByVal e As DevExpress.Utils.BindToTypePolicy.QueryNonTrustedTypeValidationEventArgs)
            If e.IsUnsafe Then
                Throw New MyAppLicationSecurityException(e.AssemblyQualifiedTypeName)
            End If
            If e.AssemblyName = GetType(Program).Assembly.FullName Then
                e.TrustThisType()
            End If
            If e.TypeName = "ObsoleteJsonDataSource" Then
                e.DoNotTrustThisType()
            End If
        End Sub
    End Module
End Namespace