Querying for Bluetooth interfaces
The Bluetooth driver stack exposes the following interfaces that profile drivers can use to interact with Bluetooth devices.
| Interface | Description |
|---|---|
| GUID_BTHDDI_SDP_NODE_INTERFACE | Profile drivers query for the GUID_BTHDDI_SDP_NODE_INTERFACE to obtain pointers to functions that allow them to create Service Discovery Protocol (SDP) records. This interface corresponds to the BTHDDI_SDP_NODE_INTERFACE structure. |
| GUID_BTHDDI_SDP_PARSE_INTERFACE | Profile drivers query for the GUID_BTHDDI_SDP_PARSE_INTERFACE to obtain pointers to functions that allow them to parse SDP records. This interface corresponds to the BTHDDI_SDP_PARSE_INTERFACE structure. |
| GUID_BTHDDI_PROFILE_DRIVER_INTERFACE | Profile drivers query for the BTHDDI_PROFILE_DRIVER_INTERFACE to obtain pointers to functions that allow them to create, allocate, reuse, and free BRBs. This interface corresponds to the BTH_PROFILE_DRIVER_INTERFACE structure. |
To obtain any of these interfaces, a profile driver must first build and send an IRP_MN_QUERY_INTERFACE IRP to the Bluetooth driver stack.
The following procedure is the general process to obtain one of these interfaces.
To query for an interface
- Allocate and initialize an IRP.
- Allocate and initialize an instance of the interface.
- Specify the major and minor function codes to query for the interface.
- Specify the interface to query for.
- Pass the IRP down the driver stack to be processed.
The following pseudocode example demonstrates how to set up an IRP_MN_QUERY_INTERFACE IRP to query the Bluetooth driver stack for the GUID_BTHDDI_PROFILE_DRIVER_INTERFACE. For readability, the example does not demonstrate error handling.
#include <bthddi.h>
...
// Define a custom pool tag to identify your profile driver's dynamic memory allocations. You should change this tag to easily identify your driver's allocations from other drivers.
#define PROFILE_DRIVER_POOL_TAG '_htB'
PIRP Irp;
Irp = IoAllocateIrp( DeviceExtension->ParentDeviceObject->StackSize, FALSE );
PBTH_PROFILE_DRIVER_INTERFACE BthInterface; // Define storage for an instance of the BTH_PROFILE_DRIVER_INTERFACE structure
BthInterface = ExAllocatePoolWithTag( NonPagedPool, sizeof( BTH_PROFILE_DRIVER_INTERFACE ), PROFILE_DRIVER_POOL_TAG );
// Zero the memory associated with the structure
RtlZeroMemory( BthInterface, sizeof( BTH_PROFILE_DRIVER_INTERFACE ) );
// Set up the next IRP stack location
PIO_STACK_LOCATION NextIrpStack;
NextIrpStack = IoGetNextIrpStackLocation( Irp );
NextIrpStack->MajorFunction = IRP_MJ_PNP;
NextIrpStack->MinorFunction = IRP_MN_QUERY_INTERFACE;
NextIrpStack->Parameters.QueryInterface.InterfaceType = (LPGUID) &GUID_BTHDDI_PROFILE_DRIVER_INTERFACE;
NextIrpStack->Parameters.QueryInterface.Size = sizeof( BTH_PROFILE_DRIVER_INTERFACE );
NextIrpStack->Parameters.QueryInterface.Version = BTHDDI_PROFILE_DRIVER_INTERFACE_VERSION_FOR_QI;
NextIrpStack->Parameters.QueryInterface.Interface = (PINTERFACE) BthInterface;
NextIrpStack->Parameters.QueryInterface.InterfaceSpecificData = NULL;
// Pass the IRP down the driver stack
NTSTATUS Status;
Status = IoCallDriver( DeviceExtension->NextLowerDriver, Irp );
If the IRP returns successfully, the profile driver can then access and use the function pointers that are contained in the interface.