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IServerSecurity (Windows Embedded CE 6.0)

1/6/2010

This interface is used by a server to help authenticate the client and to manage impersonation of the client.

When a client calls a server, the server can call CoGetCallContext to get a pointer to the IServerSecurity interface implemented on the call context object for the current method call. This pointer can be used to call an IServerSecurity method that allows the server to check the client's authentication or to impersonate the client.

The pointer to the instance of IServerSecurity returned by CoGetCallContext is automatically deleted when the server sends the reply back to the client. Therefore, the IServerSecurity object is valid only for the duration of the call. The IServerSecurity pointer must be released when it is no longer needed.

When to Implement

The stub management code in the system provides an implementation of IServerSecurity for objects by default as part of each incoming call, so typically you would not implement this interface.

You can choose to implement IServerSecurity on the custom stubs of objects that support custom marshaling to maintain a consistent programming model for their objects.

Before dispatching an arriving call, custom marshalers call CoSwitchCallContext, specifying a new context object (which must implement IServerSecurity). The original call context must be restored after the server object sends a reply.

When to Use

The methods of the IServerSecurity interface are called by a server object to examine the security settings of a particular call between a client and the server object (QueryBlanket) or to impersonate the client (ImpersonateClient and RevertToSelf).

A server impersonates a client by running in the client's security context, which allows the server to test the privilege level of the calling client and to access resources (such as files) as the client.

For more information about how impersonation works, see Impersonation and Cloaking.

The information obtained through IServerSecurity also allows an object to perform security checks in addition to the automatic ACL checks COM performs. For example, an application may want to allow time of day access to some objects or have a different ACL for each method on an object.

IServerSecurity methods can be called only before the remote procedure call completes.

Methods in Vtable Order

IUnknown method Description

QueryInterface

Returns pointers to supported interfaces.

AddRef

Increments the reference count.

Release

Decrements the reference count.

Method Description

QueryBlanket

Called by the server to find out about the client that invoked one of its methods.

ImpersonateClient

Allows a server to impersonate a client for the duration of a call.

RevertToSelf

Restores the authentication information on a thread.

IsImpersonating

Indicates whether the server is currently impersonating the client.

Remarks

To determine whether the platform supports this interface, see Determining Supported COM APIs.

Requirements

Header objidl.h, objidl.idl
Library ole32.lib, uuid.lib
Windows Embedded CE Windows CE 3.0 and later

See Also

Reference

COM Interfaces
CoGetCallContext