// dllmain.cpp : Définit le point d'entrée pour l'application DLL.
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <string>

/*
Function to patch

.text:00403B70                   ; void *__thiscall Class1::LogMessageWrapper(Class1 *this, void *message, size_t messageLength)
.text:00403B70                   Class1__LogMessageWrapper proc near     ; CODE XREF: CGbxGame__DestroyApp+58
.text:00403B70                                                           ; CGbxGame__DestroyApp+5F ...
.text:00403B70
.text:00403B70                   message         = dword ptr  4
.text:00403B70                   messageLength   = dword ptr  8
.text:00403B70
.text:00403B70 56                                push    esi
.text:00403B71 FF 74 24 0C                       push    [esp+4+messageLength]
.text:00403B75 8B F1                             mov     esi, ecx
.text:00403B77 FF 74 24 0C                       push    [esp+8+message] ; message
.text:00403B7B E8 D0 01 00 00                    call    Class1__LogMessage
.text:00403B80 8B C6                             mov     eax, esi
.text:00403B82 5E                                pop     esi
.text:00403B83 C2 08 00                          retn    8
*/

void __stdcall LogMessageWrapperHook(char* message, size_t message_length) {
	std::string content(message, message_length);
	std::cout << content;
}

__declspec(naked) void TrampolineLogJump()
{
	__asm
	{
		// Save registers
		PUSHAD

		PUSH [esp + 32 + 8 ] // PUSHAD + shift of 8
		PUSH [esp + 32 + 4 + 4 ] // PUSHAD + prev. PUSH + shift of 4

		// Call our hook
		CALL LogMessageWrapperHook

		// Restore registers
		POPAD

		// Overwrited instructions by the patch
		PUSH esi
		PUSH[esp + 0xC] // push [esp + 4 + messageLength]

		// Jump back to the function...
		PUSH 0x403b75
		RET
	}
}

__declspec(naked) void TrampolineLogCall()
{
	__asm
	{
		// Save registers
		PUSHAD

		PUSH[esp + 4 + 32 + 8] // Ret address + PUSHAD + shift of 8
		PUSH[esp + 4 + 32 + 4 + 4] // Ret address + PUSHAD + prev. PUSH + shift of 4

		// Call our hook
		CALL LogMessageWrapperHook

		// Restore registers
		POPAD

		// Overwrited instructions by the patch
		PUSH esi
		PUSH[esp + 0xC] // push [esp + 4 + messageLength]

		// Jump back to the function (8 as 4 + 4 for the 2 previous PUSH)
		RET
	}
}

void patchJump(unsigned char* addressToPatch) {
	// JMP INT32 --- char = 1 octet
	*addressToPatch = 0xE9;
	*(unsigned int*)(addressToPatch + 1) = (unsigned int)TrampolineLogJump - ((unsigned int)addressToPatch + 5);
	std::cout << "[OK]  Jump patch written." << std::endl;

	std::cout << "[INF] Patched function: 0x" << std::hex << (int)addressToPatch << std::endl;
	std::cout << "[INF] Trampoline function: 0x" << std::hex << ((int)TrampolineLogJump) << std::endl;
	std::cout << "[INF] Relative jump: 0x" << std::hex << *(unsigned int*)(addressToPatch + 1) << std::endl;
}

// DOES NOT WORK CURRENTLY
void patchCall(unsigned char* addressToPatch) {
	*addressToPatch = 0xE8;
	*(unsigned int*)(addressToPatch + 1) = (unsigned int)TrampolineLogCall - ((unsigned int)addressToPatch + 5);
	std::cout << "[OK]  Call patch written." << std::endl;

	std::cout << "[INF] Patched function: 0x" << std::hex << (int)addressToPatch << std::endl;
	std::cout << "[INF] Trampoline function: 0x" << std::hex << ((int)TrampolineLogCall) << std::endl;
	std::cout << "[INF] Relative jump: 0x" << std::hex << *(unsigned int*)(addressToPatch + 1) << std::endl;
}

void initDll() {
	AllocConsole();
	SetConsoleTitleA("Maniaplanet Observer");
	FILE* console;
	freopen_s(&console, "CONIN$", "r", stdin);
	freopen_s(&console, "CONOUT$", "w", stdout);
	freopen_s(&console, "CONOUT$", "w", stderr);

	std::cout << "[OK]  Observer.dll was successfully injected, time to patch now..." << std::endl;
	
	unsigned char* addressToPatch = (unsigned char *)0x403b70;
	DWORD oldProtection = 0;

	if (*addressToPatch != 0x56 || *(addressToPatch + 1) != 0xff) {
		std::cout << "[ERR] Did not found 0x56 0xff which are the searched opcodes..." << std::endl;
		return;
	}
	else {
		std::cout << "[OK]  Found the searched opcodes 0x56 0xff" << std::endl;
	}

	// Enable writing in memory
	if (!VirtualProtect(addressToPatch, 5, PAGE_EXECUTE_READWRITE, &oldProtection)) {
		std::cout << "[ERR] Failed to change VirtualProtect BEFORE writing memory" << std::endl;
		return;
	}
	else {
		std::cout << "[OK]  Successfully changed VirtualProtect BEFORE writing memory" << std::endl;
	}

	// Change the instruction by JMP Trampoline
	
	patchJump(addressToPatch);

	// Reprotect memory
	if (!VirtualProtect(addressToPatch, 5, oldProtection, &oldProtection)) {
		std::cout << "[ERR] Failed to change VirtualProtect AFTER writing memory" << std::endl;
		return;
	}
	else {
		std::cout << "[OK]  Successfully changed VirtualProtect AFTER writing memory" << std::endl;
	}
	
}

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
					 )
{
	switch (ul_reason_for_call)
	{
	case DLL_PROCESS_ATTACH:
		initDll();
		break;
	case DLL_THREAD_ATTACH:
	case DLL_THREAD_DETACH:
	case DLL_PROCESS_DETACH:
		break;
	}

	return TRUE;
}