public unsafe void TestExternalVTableCallAfterVTablePointerIsHooked()
{
// HookedObjectVirtualFunctionTable only supports hooking objects
// where the vtable pointer is at [objectbaseadress]
// to test this, we create a pointer to our vtable.
// this serves as a fake object, which we can hook
nuint vTableOriginal = _nativeCalculator.VTable;
IntPtr fakeObject = new IntPtr(&vTableOriginal);
// We hook the vtable pointer(fakeObject), this changes the vtable pointer but does not hook any functions yet
// Checking if this corrupts anything is done in TestVTableHookExternalCallBeforeHook
var vTableHook = HookedObjectVirtualFunctionTable.FromObject(fakeObject.ToUnsigned(), Enum.GetNames(typeof(NativeCalculator.VTableFunctions)).Length);;
// We create a VirtualFunctionTable from our fakeObject
// Calling the functions should call our hooks
var vTable = VirtualFunctionTable.FromObject(fakeObject.ToUnsigned(), Enum.GetNames(typeof(NativeCalculator.VTableFunctions)).Length);
var addFunction = vTable.CreateWrapperFunction <NativeCalculator.AddFunction>((int)NativeCalculator.VTableFunctions.Add);
var subtractFunction = vTable.CreateWrapperFunction <NativeCalculator.SubtractFunction>((int)NativeCalculator.VTableFunctions.Subtract);
var multiplyFunction = vTable.CreateWrapperFunction <NativeCalculator.MultiplyFunction>((int)NativeCalculator.VTableFunctions.Multiply);
var divideFunction = vTable.CreateWrapperFunction <NativeCalculator.DivideFunction>((int)NativeCalculator.VTableFunctions.Divide);
// Test Calling after we hook the vtable pointer using an 'external' class (VirtualFunctionTable)
// This should not modify any results
for (int x = 1; x < 100; x++)
{
for (int y = 100; y > 0; y--)
{
int add = x + y;
int subtract = x - y;
int multiply = x * y;
int divide = x / y;
Assert.Equal(add, addFunction(x, y));
Assert.Equal(subtract, subtractFunction(x, y));
Assert.Equal(multiply, multiplyFunction(x, y));
Assert.Equal(divide, divideFunction(x, y));
}
}
}
public IVirtualFunctionTable VirtualFunctionTableFromObject(IntPtr objectAddress, int numberOfMethods) => VirtualFunctionTable.FromObject(objectAddress, numberOfMethods);
public unsafe void TestExternalVTableCallAfterFunctionHook()
{
int addHook(int a, int b)
{
return(_addHook.OriginalFunction(a, b) + 1);
}
int subHook(int a, int b)
{
return(_subHook.OriginalFunction(a, b) - 1);
}
int mulHook(int a, int b)
{
return(_multiplyHook.OriginalFunction(a, b) * 2);
}
int divHook(int a, int b)
{
return(_divideHook.OriginalFunction(a, b) * 2);
}
// HookedObjectVirtualFunctionTable only supports hooking objects
// where the vtable pointer is at [objectbaseadress]
// to test this, we create a pointer to our vtable.
// this serves as a fake object, which we can hook
IntPtr vTableOriginal = _nativeCalculator.VTable;
IntPtr fakeObject = new IntPtr(&vTableOriginal);
// We hook the vtable pointer(fakeObject), this changes the vtable pointer but does not hook any functions yet
// Checking if this corrupts anything is done in TestVTableCallsAfterHookingVTablePointer
var vTableHook = HookedObjectVirtualFunctionTable.FromObject(fakeObject, Enum.GetNames(typeof(NativeCalculator.VTableFunctions)).Length);;
_addHook = vTableHook.CreateFunctionHook <NativeCalculator.AddFunction>((int)NativeCalculator.VTableFunctions.Add, addHook).Activate();
_subHook = vTableHook.CreateFunctionHook <NativeCalculator.SubtractFunction>((int)NativeCalculator.VTableFunctions.Subtract, subHook).Activate();
_multiplyHook = vTableHook.CreateFunctionHook <NativeCalculator.MultiplyFunction>((int)NativeCalculator.VTableFunctions.Multiply, mulHook).Activate();
_divideHook = vTableHook.CreateFunctionHook <NativeCalculator.DivideFunction>((int)NativeCalculator.VTableFunctions.Divide, divHook).Activate();
// We create a VirtualFunctionTable from our fakeObject
// Calling the functions should call our hooks
var vTable = VirtualFunctionTable.FromObject(fakeObject, Enum.GetNames(typeof(NativeCalculator.VTableFunctions)).Length);
var addFunction = vTable.CreateWrapperFunction <NativeCalculator.AddFunction>((int)NativeCalculator.VTableFunctions.Add);
var subtractFunction = vTable.CreateWrapperFunction <NativeCalculator.SubtractFunction>((int)NativeCalculator.VTableFunctions.Subtract);
var multiplyFunction = vTable.CreateWrapperFunction <NativeCalculator.MultiplyFunction>((int)NativeCalculator.VTableFunctions.Multiply);
var divideFunction = vTable.CreateWrapperFunction <NativeCalculator.DivideFunction>((int)NativeCalculator.VTableFunctions.Divide);
// Test Calling after we hook the vtable function pointers using an 'external' class (VirtualFunctionTable)
// This should not modify any results
for (int x = 1; x < 100; x++)
{
for (int y = 100; y > 0; y--)
{
int add = (x + y) + 1;
int subtract = (x - y) - 1;
int multiply = (x * y) * 2;
int divide = (x / y) * 2;
Assert.Equal(add, addFunction(x, y));
Assert.Equal(subtract, subtractFunction(x, y));
Assert.Equal(multiply, multiplyFunction(x, y));
Assert.Equal(divide, divideFunction(x, y));
}
}
}