?1?//???
?2?//?NDIS_PACKET結構的定義??
?3?//???
?4?typedef?struct?_NDIS_PACKET??
?5?{??
?6?NDIS_PACKET_PRIVATE?Private;??
?7?//這個其實是一個鏈表結構,Private.Head指向第一個鏈表,Private.Tail指向最后一個??
?8?//以下有關于這個結構的解釋??
?9?
10?union??
11?{??
12?struct?//?For?Connection-less?miniports???
13?{??
14?UCHAR?MiniportReserved[2*sizeof(PVOID)];??
15?UCHAR?WrapperReserved[2*sizeof(PVOID)];??
16?};??
17?
18?struct??
19?{??
20?//???
21?//?For?de-serialized?miniports.?And?by?implication?conn-oriented?miniports.???
22?//?This?is?for?the?send-path?only.?Packets?indicated?will?use?WrapperReserved???
23?//?instead?of?WrapperReservedEx???
24?//???
25?UCHAR?MiniportReservedEx[3*sizeof(PVOID)];??
26?UCHAR?WrapperReservedEx[sizeof(PVOID)];??
27?};??
28?
29?struct??
30?{??
31?UCHAR?MacReserved[4*sizeof(PVOID)];??
32?};??
33?};??
34?
35?ULONG_PTR?Reserved[2];?//?For?compatibility?with?Win95???
36?UCHAR?ProtocolReserved[1];??
37?
38?}?NDIS_PACKET,?*PNDIS_PACKET,?**PPNDIS_PACKET;??
39?
40?//?NDIS_PACKET_PRIVATE?的定義??
41?typedef?struct?_NDIS_PACKET_PRIVATE??
42?{??
43?UINT?PhysicalCount;?//?number?of?physical?pages?in?packet.???
44?UINT?TotalLength;?//?Total?amount?of?data?in?the?packet.???
45?PNDIS_BUFFER?Head;?//?鏈表指針,指向第一個?
46?PNDIS_BUFFER?Tail;?//?鏈表指針,指向最后一個??
47?
48?//?if?Head?is?NULL?the?chain?is?empty;?Tail?doesn\'t?have?to?be?NULL?also???
49?
50?PNDIS_PACKET_POOL?Pool;?//?so?we?know?where?to?free?it?back?to???
51?UINT?Count;??
52?ULONG?Flags;??
53?BOOLEAN?ValidCounts;??
54?UCHAR?NdisPacketFlags;?//?See?fPACKET_xxx?bits?below???
55?USHORT?NdisPacketOobOffset;??
56?}?NDIS_PACKET_PRIVATE,?*?PNDIS_PACKET_PRIVATE;??
57?
58?//NDIS_BUFFER定義?其實就是一個內存描述符
59?
60?typedef?struct?_NDIS_BUFFER?{??
61?struct?_NDIS_BUFFER?*Next;?//指向下一個節點的指針
62?PVOID?VirtualAddress;??????//指向報文首地址
63?PNDIS_BUFFER_POOL?Pool;??
64?UINT?Length;???????????????//報文數據長度
65?UINT?Signature;??
66?}?NDIS_BUFFER,?*?PNDIS_BUFFER;??
注釋寫的很清楚了??那么他們的關系還是不清楚的話看看附圖
?
好了??這樣一來我們的思路大概清楚了??NDIS_PACKET只不過是一個關于NDIS_BUFFER鏈表的結構??在NDIS_PACKET中的成
員Private中有指向第一個NDIS_BUFFER的指針和指向最后一個NDIS_BUFFER的指針??分別是Private.Head
和Private.Tail? ???而NDIS_BUFFER中就記錄了我們數據包的地址和下一個NDIS_BUFFER的地址?
?操作有很多種方法? ?由于這些結構體本來對我們是不透明的? ?
所以最安全的方法是用MS提供的一系列函數來操作NDIS_PACKET和NDIS_BUFFER??
? ? 還是拿個例子好說話吧
?1?NDIS_STATUS?status?;
?2?????PNDIS_BUFFER?NdisBuffer?;
?3?????UINT?TotalPacketLength?=?0?,?copysize?=?0?,?DataOffset?=?0?,?PhysicalBufferCount??,??BufferCount???;
?4?????PUCHAR?mybuffer?=?NULL?,tembuffer?=?NULL?;??
?5?
?6?//假設這個是在PtReceive等函數中得到的PACKET
?7?NdisQueryPacket(packet?????????????????????//我們先得到第一個NDISBUFFER?的指針???
?8?????????,?&PhysicalBufferCount??????????????
?9?????????,?&BufferCount???????????????????????????
10?????????,&NdisBuffer???????????????????????????????//NdisBuffer就是指向鏈表頭
11?????????,?&TotalPacketLength
12?????????);
13?/*
14?其實也可以不用那么麻煩?直接??NdisBuffer?=?packet->Private.Head?;就可以取得第一個BUFFER了
15?*/
16?
17?????status?=?NdisAllocateMemory(?&mybuffer,?2048,?0,?HighestAcceptableMax?);??//分配我們自己的內存塊
18?
19?????if(?status?!=?NDIS_STATUS_SUCCESS?)
20?????????return?NDIS_STATUS_FAILURE?;
21?
22?????NdisZeroMemory(?mybuffer,?2048?)?;
23?
24?????NdisQueryBufferSafe(??//取得NDIS_BUFFER描述符中數據的首地址和大小
25?????????????????????????????????NdisBuffer,
26?????????????????????????????????&tembuffer,
27?????????????????????????????????©size,
28?????????????????????????????????NormalPagePriority
29?????);??
30??????
31?????????//將數據復制到我們的內存中
32?????NdisMoveMemory(mybuffer,?tembuffer,?copysize)?;
33?
34?????DataOffset?=?copysize?;
35?
36?????while(1)
37?????{
38?????????/*
39?????????????????也可以這樣操作而不用NdisGetNextBuffer
40?????????if(NdisBuffer->Next?==?packet->Private.Tail?)
41?????????????break?;
42?
43?????????NdisBuffer?=?NdisBuffer->Next?;
44?
45?????????if(pmdl?==?NULL?)
46????????????break?;
47????????????*/
48?????????//獲得下一個NDIS_BUFFER的的指針
49?????NdisGetNextBuffer(NdisBuffer?,?&NdisBuffer?)?;
50?????????如果指針是NULL??那么表示到鏈表尾了
51?????if(?NdisBuffer?==?NULL?)
52?????????break?;
53?
54?????NdisQueryBufferSafe(
55?????????????????????????????????NdisBuffer,
56?????????????????????????????????&tembuffer,
57?????????????????????????????????©size,
58?????????????????????????????????NormalPagePriority
59?????????????????????????????????)?;
60?
61?????NdisMoveMemory(?mybuffer?+?DataOffset?,?tembuffer,?copysize)?;
62?
63?????DataOffset?+=?copysize??;
64?
65?????}
66?
67?//OK??我們要的數據就全部都在我們申請的內存mybuffer?數據大小為DataOffset
???
?