Some times,we need too hook some function to do something that's not so easy to do with normally add somecode.A solution is to hook focused functions and interface.Here is a template hook class maybe help your work easier,which complie with vs2005.It midify the jmp table to replace the function,maybe not properly for other compliers.
class HookPfn
{
struct make_writeable
{
void* p;
MEMORY_BASIC_INFORMATION mbi_thunk;
make_writeable(void* _p):p(_p)
{
VirtualQuery(p, &mbi_thunk, sizeof(MEMORY_BASIC_INFORMATION));
VirtualProtect(mbi_thunk.BaseAddress, mbi_thunk.RegionSize, PAGE_READWRITE, &mbi_thunk.Protect);
}
~make_writeable()
{
VirtualProtect(mbi_thunk.BaseAddress, mbi_thunk.RegionSize, mbi_thunk.Protect,&mbi_thunk.Protect);
}
};
public:
template<class F>
void restore(F pfn,unsigned long handle)
{
void* p;
__asm mov eax,[pfn]
__asm mov dword ptr[p],eax
make_writeable write(p);
__asm push ecx
__asm mov eax,pfn
__asm inc eax
__asm mov ecx,handle
__asm mov dword ptr[eax],ecx
__asm pop ecx
}
template<class F1,class F2>
unsigned long redirect(F1 pfn1,F2 pfn2)
{
//should use restrict object prevent F1 and F2 's arguments and type not same
void* p;
__asm mov eax,[pfn1]
__asm mov dword ptr[p],eax
make_writeable write(p);
unsigned long bas1,bas2,of1,of2,of;
__asm push ecx
__asm mov eax,pfn1
__asm mov bas1,eax
__asm inc eax
__asm mov ecx,dword ptr[eax]
__asm mov of1,ecx
__asm mov eax,pfn2
__asm mov bas2,eax
__asm inc eax
__asm mov ecx,dword ptr[eax]
__asm mov of2,ecx
of=(bas2-bas1+of2-of1)+of1;
__asm mov eax,pfn1
__asm inc eax
__asm mov ecx,of
__asm mov dword ptr[eax],ecx
__asm pop ecx
return of1;
}
};
class mmt
{
public:
void donothing()
{
}
void donothing(int)
{
}
void dosomething()
{
}
};
void fastcall(int a,int b)
{
}
void askcall(int,int)
{
}
It can be used as example:
int main()
{
HookMemberFunction sh;
unsigned long hd=sh.redirect(&fastcall,&askcall);//test api
fastcall(0,0);//two function
askcall(0,0);
sh.restore(&fastcall,hd);
askcall(0,0);
fastcall(0,0);
//test overlay functions(donothing)
typedef void (mmt::*sp)(void);
sp p1=&mmt::dosomething;
sp p2=&mmt::donothing;
hd=sh.redirect(p1,p2);
mmt mt;//a class
mt.donothing();
mt.dosomething();
sh.restore(p1,hd);
mt.donothing();
mt.dosomething();
}
Although it can be work right,addtionly we may be use it not properly.Youcan add some strict class to prevent bad use of it by check if the argument and return type is strictly same.,if you need it.