NdisAllocateNetBuffer - NtDoc
Native API online documentation, based on the System Informer
(formerly Process Hacker) phnt
headers
// nblapi.h
NDIS_EXPORTED_ROUTINE NET_BUFFER * NdisAllocateNetBuffer(
[in] NDIS_HANDLE PoolHandle,
[in, optional] MDL *MdlChain,
[in] ULONG DataOffset,
[in] SIZE_T DataLength
);
View the official Windows Driver Kit DDI referenceNo description available.
Call the NdisAllocateNetBuffer function to allocate and initialize a NET_BUFFER structure from a NET_BUFFER structure pool.
PoolHandle [in]A NET_BUFFER structure pool handle that was previously returned from a call to NdisAllocateNetBufferPool.
MdlChain [in, optional]A pointer to an MDL chain that NDIS uses to initialize the new NET_BUFFER structure. MdlChain can be NULL.
DataOffset [in]The initial offset, in bytes, from the start of the buffer to the start of the used data space in the MDL chain. Data space ahead of this offset is unused data space. Therefore, this value also represents the initial amount of available backfill space in the MDL chain. If MdlChain is NULL, DataOffset must be 0.
DataLength [in]The length of the used data space, in bytes, in the MDL chain. If MdlChain is NULL, DataLength must be 0.
NdisAllocateNetBuffer returns a pointer to the NET_BUFFER structure that NDIS allocated. If the allocation was unsuccessful, this pointer is NULL.
Call NdisFreeNetBuffer to free a NET_BUFFER structure that was allocated from a NET_BUFFER structure pool.
Note NET_BUFFER and NET_BUFFER_LIST structures must be allocated from an NDIS buffer pool. A driver must not allocate and initialize a NET_BUFFER or NET_BUFFER_LIST structure from its private memory pool or the stack.
The preallocated NET_BUFFER can be reused by reinitializing it with another MDL chain when it owns NET_BUFFER, but the DataOffset, DataLength, CurrentMdl, and CurrentMdlOffset fields in NET_BUFFER must be consistent with the new MDL chain.
For example, if the original MDL chain contains X DataLength and Y DataOffset, and CurrentMdl starts with the second MDL (M) in the original MDL chain, CurrentMdlOffset is Z. The MdlChain field in NET_BUFFER_DATA then needs to point to a new MDL chain that contains X' DataLength and Y' DataOffset. If CurrentMdl starts with the third MDL (M') in the new MDL chain, CurrentMdlOffset is Z', and the following macros need to be used to set fields in NET_BUFFER:
NET_BUFFER_FIRST_MDL(_NB) = New MDL chain;
NET_BUFFER_DATA_LENGTH(_NB) = X';
NET_BUFFER_DATA_OFFSET(_NB) = Y';
NET_BUFFER_CURRENT_MDL(_NB) = M';
NET_BUFFER_CURRENT_MDL_OFFSET(_NB) = Z';