NDK_FN_GET_CONNECTION_DATA callback function

The NdkGetConnectionData (NDK_FN_GET_CONNECTION_DATA) function gets read limit values and the private data sent by the peer.



NTSTATUS NdkGetConnectionData(
  _In_      NDK_CONNECTOR                                                             *pNdkConnector,
  _Out_opt_ ULONG                                                                     *pInboundReadLimit,
  _Out_opt_ ULONG                                                                     *pOutboundReadLimit,
            _Out_writes_bytes_to_opt_(*pPrivateDataLength, *pPrivateDataLength) PVOID pPrivateData,
            _Inout_ ULONG                                                             *pPrivateDataLength
{ ... }


pNdkConnector [in]

A pointer to an NDK connector object (NDK_CONNECTOR).

pInboundReadLimit [out, optional]

The maximum number of incoming in-progress read operations to allow on the QP is returned in this location.

pOutboundReadLimit [out, optional]

The maximum number of outgoing in-progress read operations to allow on the QP is returned in this location.


A pointer to private data that is returned.


The length, in bytes, of the private data that is provided in the pPrivateData parameter.

Note  The output value does not indicate the actual length of private data stored in the buffer. NDK consumers must negotiate the format and length of the actual private data. For more information about private data, see the Remarks section.

Return value

The NdkGetConnectionData function returns one of the following NTSTATUS codes.

Return codeDescription

The operation completed successfully.


The value in the *pPrivateDataLength parameter specified a buffer size that was too small to hold the connection private data. *pPrivateDataLength is updated with the required size.

Other status codes

An error occurred.



The NdkGetConnectionData function gets the private data sent by the peer with connect, accept, or reject requests and the effective inbound and outbound read limit values. These values are derived from the local and remote peers' requested values and the provider's maximum limits.

To access the private data and the effective inbound read limit (IRD) and outbound read limit (ORD) values from the active side, an NDK consumer can call NdkGetConnectionData for a connector object that was passed to the NDK_FN_CONNECT_EVENT_CALLBACK function.

To access the private data and effective IRD and ORD values from the passive side, the consumer can call NdkGetConnectionData for a connector object for which NDK_FN_CONNECT or NDK_FN_CONNECT_WITH_SHARED_ENDPOINT completed successfully An NDK consumer will not call this function after it calls the NDK_FN_ACCEPT function on the passive side or the NDK_FN_COMPLETE_CONNECT function on the active side.

If the pPrivateData parameter is NULL and *pPrivateDataLength is zero, an NDK provider must return STATUS_SUCCESS and store the required private data buffer size (RDS) in *pPrivateDataLength.

Note  The required private data buffer size (RDS) does not indicate that the peer has sent that much private data. The NDK consumer must, on both ends, have a common scheme to allow the receiving end to determine if there is any private data or not in the private data buffer. The RDS might be different for each connection.

If pPrivateData is NULL and *pPrivateDataLength is greater than zero, this is an invalid request. A consumer must never do this.

If pPrivateData is not NULL, the provider must copy the private data to the buffer at pPrivateData up to the smaller of *pPrivateDataLength or RDS in bytes.

If *pPrivateDataLength is greater than or equal to RDS, the provider must return STATUS_SUCCESS. Otherwise, the provider must return STATUS_BUFFER_TOO_SMALL. In both cases, the provider must store the RDS in *pPrivateDataLength before returning.


Minimum supported client

None supported

Minimum supported server

Windows Server 2012


Supported in NDIS 6.30 and later.


Ndkpi.h (include Ndkpi.h)



See also




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