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FormatterServices.CheckTypeSecurity Method

Determines whether the specified Type can be deserialized with the TypeFilterLevel property set to Low.

Namespace:  System.Runtime.Serialization
Assembly:  mscorlib (in mscorlib.dll)
public static void CheckTypeSecurity(
	Type t,
	TypeFilterLevel securityLevel
)

Parameters

t
Type: System.Type

The Type to check for the ability to deserialize.

securityLevel
Type: System.Runtime.Serialization.Formatters.TypeFilterLevel

The TypeFilterLevel property value.

ExceptionCondition
SecurityException

The t parameter is an advanced type and cannot be deserialized when the TypeFilterLevel property is set to Low.

Use this method to determine whether a specified type can be deserialized when the TypeFilterLevel property is set to Low.

.NET Framework remoting provides two levels of automatic deserialization, Low and Full. Low helps protect against deserialization attacks by deserializing only the types associated with the most basic remoting functionality. The Full deserialization level supports automatic deserialization of all types that remoting supports in all situations. For more information about the.NET Framework remoting types that Low and Full support, see [<topic://cpconAutomaticDeserializationInNETRemoting>].

This example shows how to use the FormatterServices class to serialize or deserialize an object where the base class does not implement ISerializable but the derived class does.

using System;
using System.IO;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Formatters;
using System.Runtime.Serialization.Formatters.Binary;
using System.Reflection;
using System.Security.Permissions;


// Person is a serializable base class.
[Serializable]
public class Person
{
    private String title;

    public Person(String title)
    {
        this.title = title;
    }

    public override String ToString()
    {
        return String.Format("{0}", title);
    }
}

// Employee is a serializable class derived from Person.
[Serializable]
public class Employee : Person
{
    private String title;

    public Employee(String title) : base("Person")
    {
        this.title = title;
    }

    public override String ToString()
    {
        return String.Format("{0} -> {1}", title, base.ToString());
    }
}

// Manager is a serializable and ISerializable class derived from Employee.
[Serializable]
public class Manager : Employee, ISerializable
{
    private String title;

    public Manager() : base("Employee") 
    {
        this.title = "Manager";
    }

    [SecurityPermission(SecurityAction.Demand, SerializationFormatter = true)]
    public void GetObjectData(SerializationInfo info, StreamingContext context)
    {

        // Serialize the desired values for this class.
        info.AddValue("title", title);

        // Get the set of serializable members for the class and base classes.
        Type thisType = this.GetType();
        MemberInfo[] mi = FormatterServices.GetSerializableMembers(thisType, context);

        // Serialize the base class's fields to the info object. 
        for (Int32 i = 0; i < mi.Length; i++)
        {
            // Do not serialize fields for this class. 
            if (mi[i].DeclaringType == thisType) continue;

            // Skip this field if it is marked NonSerialized. 
            if (Attribute.IsDefined(mi[i], typeof(NonSerializedAttribute))) continue;

            // Get the value of this field and add it to the SerializationInfo object.
            info.AddValue(mi[i].Name, ((FieldInfo) mi[i]).GetValue(this));
        }

        // Call the method below to see the contents of the SerializationInfo object.
        DisplaySerializationInfo(info);
    }

    private void DisplaySerializationInfo(SerializationInfo info)
    {
        SerializationInfoEnumerator e = info.GetEnumerator();
        Console.WriteLine("Values in the SerializationInfo:");
        while (e.MoveNext())
        {
            Console.WriteLine("Name={0}, ObjectType={1}, Value={2}", e.Name, e.ObjectType, e.Value);
        }
    }

    [SecurityPermissionAttribute(SecurityAction.Demand, Flags=SecurityPermissionFlag.SerializationFormatter)]
    protected Manager(SerializationInfo info, StreamingContext context) : base(null)
    {

        // Get the set of serializable members for the class and base classes.
        Type thisType = this.GetType();
        MemberInfo[] mi = FormatterServices.GetSerializableMembers(thisType, context);

        // Deserialize the base class's fields from the info object. 
        for (Int32 i = 0; i < mi.Length; i++)
        {
            // Do not deserialize fields for this class. 
            if (mi[i].DeclaringType == thisType) continue;

            // For easier coding, treat the member as a FieldInfo object
            FieldInfo fi = (FieldInfo) mi[i];

            // Skip this field if it is marked NonSerialized. 
            if (Attribute.IsDefined(mi[i], typeof(NonSerializedAttribute))) continue;

            // Get the value of this field from the SerializationInfo object.
            fi.SetValue(this, info.GetValue(fi.Name, fi.FieldType));
        }

        // Deserialize the values that were serialized for this class.
        title = info.GetString("title");
    }

    public override String ToString()
    {
        return String.Format("{0} -> {1}", title, base.ToString());
    }
}


public sealed class App
{
    public static void Main()
    {
        Run();
    }

    public static void Run()
    {
        using (Stream stream = new MemoryStream())
	{
            IFormatter formatter = new BinaryFormatter();
            Manager m = new Manager();
            Console.WriteLine(m.ToString());
            formatter.Serialize(stream, m);

            stream.Position = 0;
            m = (Manager) formatter.Deserialize(stream);
            Console.WriteLine(m.ToString());
        }
    }
}
// This code produces the following output. 
// 
//  Manager -> Employee -> Person 
//  Values in the SerializaitonInfo: 
//  Name=title, ObjectType=System.String, Value=Manager 
//  Name=Employee+title, ObjectType=System.String, Value=Employee 
//  Name=Person+title, ObjectType=System.String, Value=Person 
//  Manager -> Employee -> Person

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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