PROTOCOL_CM_OPEN_AF callback function (ndis.h)

Article
01/18/2023

The ProtocolCmOpenAf function is required. This function allocates per-open resources for a call manager to interact with a connection-oriented NDIS client that is opening the address family.

Note You must declare the function by using the PROTOCOL_CM_OPEN_AF type. For more information, see the following Examples section.

Syntax

PROTOCOL_CM_OPEN_AF ProtocolCmOpenAf;

NDIS_STATUS ProtocolCmOpenAf(
  [in]  NDIS_HANDLE CallMgrBindingContext,
  [in]  PCO_ADDRESS_FAMILY AddressFamily,
  [in]  NDIS_HANDLE NdisAfHandle,
  [out] PNDIS_HANDLE CallMgrAfContext
)
{...}

Parameters

[in] CallMgrBindingContext

For a non-integrated call manager, CallMgrBindingContext specifies the handle to a call manager-allocated context area in which the call managers maintains its per-binding state information. The call manager supplied this handle when it called NdisOpenAdapterEx.

For an integrated call manager (MCM), CallMgrBindingContext specifies the handle to a miniport-allocated context area in which the miniport maintains its per-adapter state information. The miniport supplied this handle in its NdisMSetAttributesEx call (for 5.x drivers) or its NdisMSetMiniportAttributes call (for 6.x drivers).

[in] AddressFamily

Specifies the address family that a client is opening. This address family was registered by the call manager when it called NdisCmRegisterAddressFamilyEx.

[in] NdisAfHandle

Specifies a handle, supplied by NDIS, that uniquely identifies this address family instance. This handle is opaque to the call manager and reserved for system use.

[out] CallMgrAfContext

Specifies the handle to a call manager-supplied context area in which the call manager maintains state about this open of an address family it provides.

Return value

ProtocolCmOpenAf returns the status of its operation(s) as one of the following:

Return code	Description
NDIS_STATUS_SUCCESS	Indicates that the call manager has successfully allocated and initialized any resources necessary to accept requests from the client to this address family.
NDIS_STATUS_PENDING	Indicates that the requested operation is being handled asynchronously. The call manager must call NdisCmOpenAddressFamilyComplete when it has completed all its open-AF operations to indicate to NDIS (and the client) that the operation(s) has been completed.
NDIS_STATUS_RESOURCES	Indicates that the call manager could not complete its necessary operation(s) because of a lack of available system resources, such as memory.
NDIS_STATUS_XXX	Indicates that the call manager could not set itself into a state where it can accept requests from the client to operate on this address family. This could be an error status propagated from another NDIS library function or any error status determined appropriate by the driver writer.

Remarks

ProtocolCmOpenAf performs any required allocations of dynamic resources and structures that the call manager writer deems necessary to perform operations on behalf of the client that is opening an instance of this address family. Such resources include, but are not limited to, memory buffers, data structures, events, and other such similar resources. A call manager should also initialize any relevant per-open data before returning control to NDIS.

When a call manager has allocated its per-open state area, the address of the state area should be set in the CallMgrAfContext handle before returning control to NDIS. To do this, dereference CallMgrAfContext and store a pointer to the data area as the value of the handle. For example:

*CallMgrAfContext = SomeBuffer;

If ProtocolCmOpenAf cannot allocate the per-open resources it needs to carry out subsequent requests on behalf of the client opening this address family, it should free all resources that it allocated for the open and return control to the NDIS with NDIS_STATUS_RESOURCES.

If ProtocolCmOpenAf has completed its required operations and the CM is ready to accept requests from the client, ProtocolCmOpenAf should return control as quickly as possible with a status of NDIS_STATUS_SUCCESS.

Examples

To define a ProtocolCmOpenAf function, you must first provide a function declaration that identifies the type of function you're defining. Windows provides a set of function types for drivers. Declaring a function using the function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

For example, to define a ProtocolCmOpenAf function that is named "MyCmOpenAf", use the PROTOCOL_CM_OPEN_AF type as shown in this code example:

PROTOCOL_CM_OPEN_AF MyCmOpenAf;

Then, implement your function as follows:

_Use_decl_annotations_
NDIS_STATUS
 MyCmOpenAf(
    NDIS_HANDLE  CallMgrBindingContext,
    PCO_ADDRESS_FAMILY  AddressFamily,
    NDIS_HANDLE  NdisAfHandle,
    PNDIS_HANDLE  CallMgrAfContext
    )
  {...}

The PROTOCOL_CM_OPEN_AF function type is defined in the Ndis.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the Use_decl_annotations annotation to your function definition. The Use_decl_annotations annotation ensures that the annotations that are applied to the PROTOCOL_CM_OPEN_AF function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for NDIS Drivers.

For information about Use_decl_annotations, see Annotating Function Behavior.

Requirements

Requirement	Value
Minimum supported client	Supported for NDIS 6.0 and NDIS 5.1 drivers (see ProtocolCmOpenAf (NDIS 5.1)) in Windows Vista. Supported for NDIS 5.1 drivers (see ProtocolCmOpenAf (NDIS 5.1)) in Windows XP.
Target Platform	Windows
Header	ndis.h (include Ndis.h)
IRQL	<= DISPATCH_LEVEL

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