PROTOCOL_CM_DROP_PARTY callback function (ndis.h)

The ProtocolCmDropParty function is required. NDIS calls ProtocolCmDropParty to request that the call manager remove a party from an existing multipoint call.

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



NDIS_STATUS ProtocolCmDropParty(
  [in]           NDIS_HANDLE CallMgrPartyContext,
  [in, optional] PVOID CloseData,
  [in, optional] UINT Size


[in] CallMgrPartyContext

Specifies the handle to a call manager-allocated context area in which the call manager maintains its per-party state. This handle was provided to NDIS in the call managers ProtocolCmAddParty function.

[in, optional] CloseData

Pointer to a buffer containing connection-oriented client-specific data that should be sent across the connection before the party is dropped. This parameter is NULL if the underlying network medium does not support transfers of data when closing a connection.

[in, optional] Size

Specifies the length, in bytes, of the buffer at CloseData, zero if CloseData is NULL.

Return value

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

Return code Description
Indicates that the call manager has successfully dropped the party, sent any close data, and free the resources that were allocated for its context area.
Indicates that the call manager will complete the request to drop the party asynchronously. The call manager must call NdisCmDropPartyComplete when all processing has been finished to notify NDIS and the requesting actor that the party has been dropped.
Indicates that CloseData was specified to the call manager, but the media type does not support sending data concurrent with connection termination.


ProtocolCmDropParty communicates with network control devices or other media-specific agents, as necessary for its media, to drop a party from an existing multipoint call. If the call manager is required to communicated with network control agents (such as, a networking switch) it should use a virtual connection to the network control agents that it established in its ProtocolBindAdapterEx function.

If CloseData is non-NULL and sending data at connection termination is supported by its media type, the call manager should transmit the data specified at CloseData before completing termination. If sending data concurrent with connection termination is not supported by the media type, the call manager should return control with NDIS_STATUS_INVALID_DATA.

Call managers must also free any per-party resources that it allocated and stored at CallMgrPartyContext . In addition, the call manager must free the buffer stored CallMgrPartyContext itself. Failure to do so will result in a memory leak condition.


To define a ProtocolCmDropParty 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 ProtocolCmDropParty function that is named "MyCmDropParty", use the PROTOCOL_CM_DROP_PARTY type as shown in this code example:


Then, implement your function as follows:

    NDIS_HANDLE  CallMgrPartyContext,
    PVOID  CloseData,
    UINT  Size

The PROTOCOL_CM_DROP_PARTY 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_DROP_PARTY 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.


Minimum supported client Supported for NDIS 6.0 and NDIS 5.1 drivers (see ProtocolCmDropParty (NDIS 5.1)) in Windows Vista. Supported for NDIS 5.1 drivers (see ProtocolCmDropParty (NDIS 5.1)) in Windows XP.
Target Platform Windows
Header ndis.h (include Ndis.h)

See also