一个API HOOK函数

Jikycc 2008-01-30 01:18:54

以下是一个在网上找的一个API HOOK函数，大侠们能帮我看看函数的参数是什么吗？

// HookAPI.cpp

// -----------------------------
// HOOKAPI - Matt Pietrek 1995
// -----------------------------

#include <windows.h>
#include "HookAPI.h"

// Macro for adding pointers/DWORDs together without C arithmetic interfering

#define MakePtr(cast, ptr, addValue) (cast)((DWORD)(ptr)+(DWORD)(addValue))

PROC HookAPIFunction(HMODULE hFromModule,
PSTR pszFunctionModule,
PSTR pszFunctionName,
PROC pfnNewProc)
{
PROC pfnOriginalProc;
PIMAGE_DOS_HEADER pDosHeader;
PIMAGE_NT_HEADERS pNTHeader;
PIMAGE_IMPORT_DESCRIPTOR pImportDesc;
PIMAGE_THUNK_DATA pThunk;

DWORD dwProtectionFlags;
DWORD dwScratch;

// Verify that a valid pfn was passed
if (IsBadCodePtr(pfnNewProc)) return 0;
// First, verify the the module and function names passed to use are valid
pfnOriginalProc = GetProcAddress(GetModuleHandle(pszFunctionModule), pszFunctionName);
if (!pfnOriginalProc) return 0;
pDosHeader = (PIMAGE_DOS_HEADER)hFromModule;
// Tests to make sure we're looking at a module image (the 'MZ' header)
if (IsBadReadPtr(pDosHeader, sizeof(IMAGE_DOS_HEADER))) return 0;
if (pDosHeader->e_magic != IMAGE_DOS_SIGNATURE) return 0;
// The MZ header has a pointer to the PE header
pNTHeader = MakePtr(PIMAGE_NT_HEADERS, pDosHeader, pDosHeader->e_lfanew);
// More tests to make sure we're looking at a "PE" image
if (IsBadReadPtr(pNTHeader, sizeof(IMAGE_NT_HEADERS))) return 0;
if (pNTHeader->Signature != IMAGE_NT_SIGNATURE) return 0;
// We know have a valid pointer to the module's PE header.
// Now go get a pointer to its imports section
pImportDesc = MakePtr(PIMAGE_IMPORT_DESCRIPTOR, pDosHeader,
pNTHeader->OptionalHeader.
DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].
VirtualAddress);
// Bail out if the RVA of the imports section is 0 (it doesn't exist)
if (pImportDesc == (PIMAGE_IMPORT_DESCRIPTOR)pNTHeader) return 0;
// Iterate through the array of imported module descriptors, looking
// for the module whose name matches the pszFunctionModule parameter
while (pImportDesc->Name)
{
PSTR pszModName = MakePtr(PSTR, pDosHeader, pImportDesc->Name);
if (stricmp(pszModName, pszFunctionModule) == 0) break;
// Advance to next imported module descriptor
pImportDesc++;
}
// Bail out if we didn't find the import module descriptor for the
// specified module. pImportDesc->Name will be non-zero if we found it.
if (pImportDesc->Name == 0) return 0;
// Get a pointer to the found module's import address table (IAT)
pThunk = MakePtr(PIMAGE_THUNK_DATA, pDosHeader, pImportDesc->FirstThunk);
// Blast through the table of import addresses, looking for the one
// that matches the address we got back from GetProcAddress above.
while (pThunk->u1.Function)
{
if (pThunk->u1.Function == (PDWORD)pfnOriginalProc)
{
dwProtectionFlags = PAGE_READWRITE;
VirtualProtect(&pThunk->u1.Function, 4096, dwProtectionFlags, &dwScratch);
// We found it! Overwrite the original address with the
// address of the interception function. Return the original
// address to the caller so that they can chain on to it.
pThunk->u1.Function = (PDWORD)pfnNewProc;
return pfnOriginalProc;
}
// Advance to next imported function address
pThunk++;
}
// Function not found
return 0;
}

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