DEVELOPER MODE v0.2: Dev T-Shirts, SCTV, Creator | incl. SOURCE for HOOKING NATIVES

#include "stdafx.h"

#define MAX_HOOKS 1000

typedef struct _HOOK_INFO
{
	ULONG_PTR Function;
	ULONG_PTR Hook;
	ULONG_PTR OrigBytes;
} HOOK_INFO, *PHOOK_INFO;

HOOK_INFO HookInfo[MAX_HOOKS];
UINT NumberOfHooks = 0;
bool hookFailed = false;
BYTE *pOrigBytesBuffer = NULL; 



HOOK_INFO *GetHookInfoFromFunction(ULONG_PTR OriginalFunction)
{
	if (NumberOfHooks == 0)
		return NULL;

	for (UINT x = 0; x < NumberOfHooks; x++)
	{
		if (HookInfo[x].Function == OriginalFunction)
			return &HookInfo[x];
	}

	return NULL;
}

void WriteJump(void *pAddress, ULONG_PTR JumpTo)
{
	// be extra safe and overwrite memory with a single memcpy
	BYTE *pJumpInstructionBuffer = (BYTE *)malloc(14);
	BYTE *pCur = pJumpInstructionBuffer;

	*pCur = 0xff;		// jmp [rip+addr]
	*(++pCur) = 0x25;
	*((DWORD *) ++pCur) = 0; // addr = 0
	pCur += sizeof(DWORD);
	*((ULONG_PTR *)pCur) = JumpTo;

	DWORD dwOldProtect = 0;
	VirtualProtect(pAddress, 14, PAGE_EXECUTE_READWRITE, &dwOldProtect);

	memcpy(pAddress, pJumpInstructionBuffer, 14);
	
	DWORD dwBuf = 0; 
	VirtualProtect(pAddress, 14, dwOldProtect, &dwBuf);

	free(pJumpInstructionBuffer);
}

void *BackupOrigBytes(ULONG_PTR originalFunction)
{
	if (pOrigBytesBuffer == NULL) {
		pOrigBytesBuffer = (BYTE *)malloc(MAX_HOOKS * 14);
	}

	VOID *pOrigBytes = (VOID *)&pOrigBytesBuffer[NumberOfHooks * 14];

	memcpy(&pOrigBytesBuffer[NumberOfHooks * 14], (void *)originalFunction, 14);

	return pOrigBytes;
}

bool hookNative(UINT64 hash, ULONG_PTR hookFunction = NULL)
{
	auto originalFunction = GetNativeHandler(hash);

	if (originalFunction == 0) {
		hookFailed = true;
		return false;
	}

	HOOK_INFO *hinfo = GetHookInfoFromFunction((ULONG_PTR) originalFunction);

	if (hinfo) {
		WriteJump(originalFunction, hinfo->Hook);
	}
	else
	{
		if (NumberOfHooks == (MAX_HOOKS - 1))
			return false;

		VOID *pOrigBytes = BackupOrigBytes((ULONG_PTR)originalFunction);

		HookInfo[NumberOfHooks].Function = (ULONG_PTR)originalFunction;
		HookInfo[NumberOfHooks].OrigBytes = (ULONG_PTR)pOrigBytes;
		HookInfo[NumberOfHooks].Hook = hookFunction;

		NumberOfHooks++;

		WriteJump(originalFunction, hookFunction);
	}

	return true;
}

void unhookNative(UINT64 hash) {
	auto originalFunction = GetNativeHandler(hash);

	HOOK_INFO *hinfo = GetHookInfoFromFunction((ULONG_PTR)originalFunction);

	DWORD dwOldProtect = 0;

	VirtualProtect(originalFunction, 14, PAGE_EXECUTE_READWRITE, &dwOldProtect);

	memcpy((void *)hinfo->Function, (void *)hinfo->OrigBytes, 14);

	DWORD dwBuf = 0;
	VirtualProtect(originalFunction, 14, dwOldProtect, &dwBuf);
}

void* __cdecl MY_IS_DLC_PRESENT(NativeContext *cxt)
{
	Hash DlcHash = cxt->GetArgument<Hash>(0);

	if (DlcHash == 2532323046) { // DEV
		// game game requested dev dlc -> return true;
		cxt->SetResult(0, true);
		return cxt;
	}

	// restore original function
	unhookNative(0x2D6859674806FDCE); 
	
	// get result of original function
	BOOL result = DLC2::IS_DLC_PRESENT(cxt->GetArgument<Hash>(0)); 
	cxt->SetResult(0, result);

	// hook us up again
	hookNative(0x2D6859674806FDCE);

	return cxt;
}

bool AttemptHookNatives() {
	static DWORD64 dwThreadCollectionPtr = 0;

	if (!dwThreadCollectionPtr) {
		// scan for GTA Thread Pool
		dwThreadCollectionPtr = Pattern::Scan(g_MainModuleInfo, "48 8B 05 ? ? ? ? 8B CA 4C 8B 0C C8 45 39 51 08");
	}

	if (   !dwThreadCollectionPtr
		|| !Pattern::Scan(g_MainModuleInfo, "76 61 49 8B 7A 40 48 8D 0D") // scan for Native Registration Table
	) {
		// too early. GetNativeHandler would log a fatal error and exit the process
		return false;
	}

	hookFailed = false;

	hookNative(0x2D6859674806FDCE, (ULONG_PTR)&MY_IS_DLC_PRESENT);
	// add more hooks here

	return !hookFailed;
}

DWORD WINAPI lpHookNatives(LPVOID lpParam) {
	while (!AttemptHookNatives()) {
		Sleep(100);
	}

	return 0;
}

void SpawnHookNatives() {
	CreateThread(0, 0, lpHookNatives, 0, 0, 0);
}