Responding to Sets and Queries in an Intermediate Driver

Because an NDIS intermediate driver is bound to an overlying NDIS driver, it can also receive queries and sets from its MiniportOidRequest function. In some cases, the intermediate driver just passes such requests through to the underlying miniport driver. Otherwise, it can respond to these queries and sets as appropriate to the medium that it exports at its upper edge. Note that an intermediate driver must always pass through any OID_PNP_Xxx requests that it receives from an overlying NDIS driver to the underlying miniport driver. NDIS 6.0 intermediate drivers can also cancel OID requests.

To forward a request down to the underlying drivers, an NDIS intermediate driver calls NdisAllocateCloneOidRequest to allocate a cloned NDIS_OID_REQUEST structure. The driver calls the NdisOidRequest function to send the request. When the request is complete, the driver must call the NdisFreeCloneOidRequest function to free the NDIS_OID_REQUEST structure.

To cancel an OID request, call the NdisCancelOidRequest function.

Typically, the general OIDs that an intermediate driver receives are the same or similar to those that the intermediate driver sends to the underlying miniport driver. The medium-specific OIDs that an intermediate driver receives are the type of the medium that the overlying driver requires.

If an intermediate driver itself processes the setting of an OID rather than passing the set request to an underlying miniport, it should validate the value to be set. If the intermediate driver determines that the value to be set is out of bounds, it should fail the set request.

Note  If an intermediate driver modifies the contents of TCP network data that it forwards down to an underlying miniport driver such that TCP offload functions cannot be performed on the network data, the intermediate driver should respond to OID_TCP_OFFLOAD_CURRENT_CONFIG queries with a status of NDIS_STATUS_NOT_SUPPORTED instead of passing the request down to the underlying miniport.

For additional information about responding to sets and queries in an intermediate driver, see Obtaining and Setting Miniport Driver Information and NDIS Support for WMI.