Ndis中如何处理接收到数据?

int CheckRecvBuffer(IN OUT PVOID HeaderBuffer,
IN UINT HeaderBufferSize,
IN PVOID LookAheadBuffer,
IN UINT LookaheadBufferSize,
IN UINT PacketSize)
{
PETHERNET_FRAME pEthernetFrame = 0;
WORD ethernetFrameType = 0;
PIP_HEADER pIpHeader = 0;
UINT ipHeaderLen = 0;
PVOID pIpData = NULL;

if(HeaderBuffer &&
(HeaderBufferSize >= ETHERNET_FRAME_LENGTH))
{
pEthernetFrame = (PETHERNET_FRAME)HeaderBuffer;
ethernetFrameType = ntohs(pEthernetFrame -> FrameType);


if(ETHERNET_FRAME_TYPE_TCPIP == ethernetFrameType
&& LookaheadBufferSize > IP_HEADER_LENGTH && LookAheadBuffer != NULL)
{
pIpHeader = (PIP_HEADER)LookAheadBuffer;
ipHeaderLen = GET_IP_HEADER_LENGTH(pIpHeader->VersionAndHeaderLength);
if(LookaheadBufferSize - ipHeaderLen > 0)
{
pIpData = (PVOID)((BYTE*)LookAheadBuffer + ipHeaderLen);
changeIpData(pIpData,pIpHeader->Protocol);
}
                                else // 有可能出现该情况吗?出现了又如何去做呢?
}
}
   return XF_SUCCESS;
}
我仅想得到ip报头后tcp数据报头第一个字节数据, 是否有LookaheadBufferSize <= IP_HEADER_LEN  的情况? 还是永远LookaheadBufferSize > IP_HEADER_LEN?

[编辑 -  6/13/05 by  cyliu]

[编辑 -  6/13/05 by  cyliu]

LookaheadBufferSize > IP_HEADER_LEN

1000M/100M/10M这种自适应的网卡有什么特殊处理吗?

在ReceiveHandler涵数中,
if (LookaheadBufferSize < PacketSize) 会调用TransferDataHandler,在TransferDataHandler中获得Packet是否不在包含ReceiveHandler接收到的数据,如Frame头,IP头等,仅是ReceiveHandler没有接收完的剩余数据?

为什么会出现LookaheadBufferSize < PacketSize情况呢?