Other Advanced Topic on DLL

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Other Advanced Topic on DLL
????? http//debut.cis.nctu.edu.tw/ching
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????? Export name
MyDLL.def ??
__declspec(dllexport) ??

• ???? DLL ? .def ??????? export name

RVA ????
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LIBRARY MyDLL EXPORTS AddnewAdd
?? Addnew ????? Add
dumpbin /exports MyDLL.dll
MyDLL.def
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?? ordinal number
LIBRARY MyDLL EXPORTS AddnewAdd _at_12345
?? Addnew ? ordinal number 12345
MyDLL.def
??? _at_12345 ??
__declspec(dllexport) ??
DLL ???
MyDLL.def ??
dumpbin /exports MyDLL.dll
lib ???
dumpbin /exports MyDLL.lib
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??? exported ? name

• ? .def ???
• NONAME ??
• ??????? ordinal ???? function
• export name ???? .dll ??, ??? dll???
• PRIVATE ?? .def ? EXPORTS ? name ???? .lib ?

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????
Step 1
?? __declspec(dllexport) ??
ifdef MYLIBExport define MYLIBAPI extern
"C" //__declspec(dllexport) else define
MYLIBAPI extern "C" //__declspec(dllimport) endif
MYLIBAPI int g_nResult MYLIBAPI int Add(int
nLeft, int nRight)
MyDLL.h
Step 3
???? (dumpbin)
Step 2
?? NONAME ? PRIVATE ???
LIBRARY MyDLL EXPORTS AddnewAdd _at_12345 NONAME
DLL ???
lib ???
MyDLL.def
??
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?? name ?????

• ?? ordinal number

DLL ???
include ltwindows.hgt typedef int
(ADDPF)(int,int) int _tmain(int argc, _TCHAR
argv) HMODULE hModuleLoadLibrary("MyDLL.dll"
) ADDPF pf(ADDPF)GetProcAddress(hModule,(LPCSTR
)12345) int c(pf)(1,2) return 0
?? ordinal number ?? Function ?????
???????
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DLL Forward

• ???? DumpBin ? Kernel32.dll ????

??? forwarded ?????
?????????? HeapAlloc ,
??????? RtlAllocateHeap
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DLL Forward
2 forwarded
HeapAlloc()
RtlAllocateHeap()
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Kernel32.dll
NTDLL.dll
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???????? forwarded?
???, ????
????? function
??? name
pragma comment(linker, "/exportAddNewDLL.NewAdd
")
?DLL name
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??
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???? forwarded ???
int main( ) int dAdd(1,2) cout ltlt
d ltlt endl return 0
pragma comment(linker, \ "/exportAddNewDLL.
NewAdd") // ???? MYLIBAPI int Add(int nLeft, int
nRight) g_nResult nLeft nRight
return(g_nResult)
UseDLL.cpp
MyDLL
// ???? MYLIBAPI int NewAdd(int x, int y)
int sumxy10 return(sum)
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NewDLL
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??

• ?? NewDLL ?? NewDLL.dll ? NewDLL.lib
• ?? MyDLL ?? MyDLL.dll ? MyDLL.lib
• ?? UseDLL
• ?? MyDLL.lib ?????????
• ???, NewDLL.dll ? MyDLL.dll ???????????

UseDLL ? Linker Option
??????? Add symbol
????? Delay Loaded DLLs ???????Add ??
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????? name
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????
?? ??? Add ?? forward ? NewDLL??
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