DnsPermissionAttribute Class
Specifies permission to request information from Domain Name Servers.
For a list of all members of this type, see DnsPermissionAttribute Members.
System.Object
System.Attribute
System.Security.Permissions.SecurityAttribute
System.Security.Permissions.CodeAccessSecurityAttribute
System.Net.DnsPermissionAttribute
[Visual Basic] <AttributeUsage(AttributeTargets.Assembly Or AttributeTargets.Class _ Or AttributeTargets.Struct Or AttributeTargets.Constructor Or _ AttributeTargets.Method)> <Serializable> NotInheritable Public Class DnsPermissionAttribute Inherits CodeAccessSecurityAttribute [C#] [AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method)] [Serializable] public sealed class DnsPermissionAttribute : CodeAccessSecurityAttribute [C++] [AttributeUsage(AttributeTargets::Assembly | AttributeTargets::Class | AttributeTargets::Struct | AttributeTargets::Constructor | AttributeTargets::Method)] [Serializable] public __gc __sealed class DnsPermissionAttribute : public CodeAccessSecurityAttribute [JScript] public AttributeUsage(AttributeTargets.Assembly | AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Constructor | AttributeTargets.Method) Serializable class DnsPermissionAttribute extends CodeAccessSecurityAttribute
Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
Remarks
The security information declared by DnsPermissionAttribute is stored in the metadata of the attribute target, which is the class to which the DnsPermissionAttribute is applied. The system then accesses this information at run-time. The SecurityAction passed to the constructor determines the allowable DNS targets.
These security attributes are used only for Declarative Security. For Imperative Security, use the corresponding DnsPermission class.
Security access is either fully restricted, or fully unrestricted. Set the Unrestricted property to true to grant access, or false for no access. Set this property as a named parameter.
For more information about using attributes, see Extending Metadata Using Attributes.
Example
[Visual Basic, C#, C++] The following example uses DnsPermissionAttribute to apply declarative security to a custom class.
[Visual Basic] ' Uses the DnsPermissionAttribute to restrict access only to those who have permission. <DnsPermission(SecurityAction.Demand, Unrestricted := true)> _ Public Class MyClass1 Public Shared Function GetIPAddress() As IPAddress Dim ipAddress As IPAddress = Dns.Resolve("localhost").AddressList(0) Return ipAddress End Function 'GetIPAddress Public Shared Sub Main() Try ' Grants Access. Console.WriteLine(("Access granted" + ControlChars.NewLine + " The local host IP Address is :" + MyClass1.GetIPAddress().ToString())) ' Denies Access. Catch securityException As SecurityException Console.WriteLine("Access denied") Console.WriteLine(securityException.ToString()) End Try [C#] //Uses the DnsPermissionAttribute to restrict access only to those who have permission. [DnsPermission(SecurityAction.Demand, Unrestricted = true)] public class MyClass{ public static IPAddress GetIPAddress(){ IPAddress ipAddress = Dns.Resolve("localhost").AddressList[0]; return ipAddress; } public static void Main(){ try{ //Grants Access. Console.WriteLine(" Access granted\n The local host IP Address is :" + MyClass.GetIPAddress().ToString()); } // Denies Access. catch(SecurityException securityException){ Console.WriteLine("Access denied"); Console.WriteLine(securityException.ToString()); } [C++] //Uses the DnsPermissionAttribute to restrict access only to those who have permission. [DnsPermission(SecurityAction::Demand, Unrestricted = true)] public __gc class MyClass{ public: static IPAddress* GetIPAddress(){ IPAddress* ipAddress = Dns::Resolve(S"localhost")->AddressList[0]; return ipAddress; } }; int main(){ try{ //Grants Access. Console::WriteLine(S" Access granted\n The local host IP Address is :{0}", MyClass::GetIPAddress()); } // Denies Access. catch(SecurityException* securityException){ Console::WriteLine(S"Access denied"); Console::WriteLine(securityException->ToString()); } }
[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button
in the upper-left corner of the page.
Requirements
Namespace: System.Net
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
Assembly: System (in System.dll)
See Also
DnsPermissionAttribute Members | System.Net Namespace | CodeAccessSecurityAttribute