/*
Copyright 2016 Peter Repukat - FlatspotSoftware

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include "EnforceBindings.h"
#include <vector>

//stuff for finding the function as well as the injected code
//should probably be moved somewhere else
DWORD address = NULL;
DWORD JMPBack;
int32_t currentBindings;
const int32_t desktopBindingsID = 413080; //desktop_config appid
const int32_t bigPictureBindingsID = 413090; //big_picture_config appid
const int32_t steamChordBindingsID = 443510; //steam_chord_config appid
int32_t enforceBindingsID = 413080;


std::string originalBytes_V0 = "\x8B\x45\x0c\x57\x8B\x7D\x08\x3D\x76\xC4\x06\x00"; //original assembly code of steamclient.dll that we want to hook (V0)
/* == 
mov eax, dword ptr ss : [ebp + 0xc]						//appId of bindings to be switched gets moved into eax register
push edi												//part of original steam code
mov edi, dword ptr ss : [ebp + 0x8]						//part of original steam code
cmp eax, 0x6C476										//part of original steam code - checks if bindings to be set are steamchord bindings
*/
std::string mask_V0 = "xxxxxxxxxxxx";											   //mask for searching 


std::string originalBytes_V1 = "\x8B\x45\x0C\x3D\x76\xC4\x06\x00"; //original assembly code of steamclient.dll that we want to hook (V1)
/* ==
mov eax,dword ptr ss:[ebp + 0xC]	//appId of bindings to be switched gets moved into eax register
cmp eax,6C476						//part of original steam code - checks if bindings to be set are steamchord bindings
*/
std::string mask_V1 = "xxxxxxxx";											   //mask for searching 




std::string originalBytes_V2 = "\x8B\x4D\x0C\x53\x8D\x9f\x2a\x03\x00\x00\x8D\x1C\x9E\x81\xF9\x76\xc4\x06\x00"; //original assembly code of steamclient.dll that we want to hook (V2)
/* ==
mov ecx,dword ptr ss:[ebp+C]			//appId of bindings to be switched gets moved into ecx register
push ebx								//part of original steam code
lea ebx,dword ptr ds:[edi+32A]			//part of original steam code
lea ebx,dword ptr ds:[esi+ebx*4]		//part of original steam code
cmp ecx,6C476							//part of original steam code - checks if bindings to be set are steamchord bindings
 */
std::string mask_V2 = "xxxxxxxxxxxxxxxxxxx";											   //mask for searching 
int32_t sigLen_V2 = 19;

std::string originalBytes_V3 = "\x8D\x8e\x38\x0c\x00\x00\x8B\x45\x0C"; //original assembly code of steamclient.dll that we want to hook (V2)
/* ==
lea ecx,dword ptr ds:[esi+C38]			 //part of original steam code
mov eax,dword ptr ss:[ebp+C]			//appId of bindings to be switched gets moved into ecx register
 */
std::string mask_V3 = "xxxxxxxxx";											   //mask for searching 

std::string originalBytes_V4 = "\x8B\x45\x0C\x89\x45\xF4\x8D\x45\xF0\x50\x89\x7D\xF0"; //original assembly code of steamclient.dll that we want to hook (V2)
/* == 
mov eax,dword ptr ss:[ebp+C]									//appId of bindings to be switched gets moved into eax register
mov dword ptr ss:[ebp-C],eax
lea eax,dword ptr ss:[ebp-10]
push eax
mov dword ptr ss:[ebp-10],edi
*/
std::string mask_V4 = "xxxxxxxxxxxxx";											   //mask for searching 

int patchversion = 0;

std::vector<std::string> masks = { 
	mask_V0,
	mask_V1,
	mask_V2,
	mask_V3,
	mask_V4 
};

std::vector<std::string> sig_bytes = { 
	originalBytes_V0,
	originalBytes_V1,
	originalBytes_V2,
	originalBytes_V3,
	originalBytes_V4
};


//////////////////////////////////  CODE  ///////////////////////////////////////////

__declspec(naked) void enforceBindingsHookFn_V0()
{
	__asm
	{
		mov eax, dword ptr ss : [ebp + 0xc]						//part of original steam code - appId of bindings to be switched gets moved into eax register
		mov currentBindings, eax								//move into "currentBindings" variable
	}

	if (currentBindings != desktopBindingsID					//if the current bindings aren't desktop, big picture, or steam-chord bindings
		&& currentBindings != bigPictureBindingsID				//they have to be our game bindings
		&& currentBindings != steamChordBindingsID)				//we can grab them here, because bindings switch right after we have injected and the target changes focused window
	{
		enforceBindingsID = currentBindings;
	}

	if (currentBindings == desktopBindingsID)					//if steam wants to set desktop-bindings
	{
		__asm
		{
			mov eax, enforceBindingsID							//move appid of bindings to enforce into eax register
		}
	}

	__asm
	{
		push edi												//part of original steam code
		mov edi, dword ptr ss : [ebp + 0x8]						//part of original steam code
		cmp eax, 0x6C476										//part of original steam code - checks if bindings to be set are steamchord bindings
		jmp[JMPBack]											//jump back and continiue with original steam function 
	}															//note: zero flag doesn't get altered by jmp instruction, previous compare still works fine
}
//\\\


__declspec(naked) void enforceBindingsHookFn_V1()
{
	__asm
	{
		mov eax, dword ptr ss : [ebp + 0xc]						//part of original steam code - appId of bindings to be switched gets moved into eax register
		mov currentBindings, eax								//move into "currentBindings" variable
	}

	if (currentBindings != desktopBindingsID					//if the current bindings aren't desktop, big picture, or steam-chord bindings
		&& currentBindings != bigPictureBindingsID				//they have to be our game bindings
		&& currentBindings != steamChordBindingsID)				//we can grab them here, because bindings switch right after we have injected and the target changes focused window
	{
		enforceBindingsID = currentBindings;
	}

	if (currentBindings == desktopBindingsID)					//if steam wants to set desktop-bindings
	{
		__asm
		{
			mov eax, enforceBindingsID							//move appid of bindings to enforce into eax register
		}
	}

	__asm
	{
		cmp eax, 0x6C476										//part of original steam code - checks if bindings to be set are steamchord bindings
		jmp[JMPBack]											//jump back and continiue with original steam function 
	}															//note: zero flag doesn't get altered by jmp instruction, previous compare still works fine
}
//\\\

__declspec(naked) void enforceBindingsHookFn_V2()
{
	__asm
	{
		mov ecx, dword ptr ss : [ebp + 0xc]						//part of original steam code - appId of bindings to be switched gets moved into eax register
		mov currentBindings, ecx								//move into "currentBindings" variable
	}

	if (currentBindings != desktopBindingsID					//if the current bindings aren't desktop, big picture, or steam-chord bindings
		&& currentBindings != bigPictureBindingsID				//they have to be our game bindings
		&& currentBindings != steamChordBindingsID)				//we can grab them here, because bindings switch right after we have injected and the target changes focused window
	{
		enforceBindingsID = currentBindings;
	}

	if (currentBindings == desktopBindingsID)					//if steam wants to set desktop-bindings
	{
		__asm
		{
			mov ecx, enforceBindingsID							//move appid of bindings to enforce into eax register
		}
	}

	__asm
	{
		push ebx												//part of original steam code
		lea ebx, dword ptr ds : [edi + 0x32A]					//part of original steam code
		lea ebx, dword ptr ds : [esi + ebx * 0x4]				//part of original steam code
		cmp ecx, 0x6C476										//part of original steam code - checks if bindings to be set are steamchord bindings
		jmp[JMPBack]											//jump back and continiue with original steam function 
	}															//note: zero flag doesn't get altered by jmp instruction, previous compare still works fine
}
//\\\

__declspec(naked) void enforceBindingsHookFn_V3()
{
	__asm
	{
		lea ecx, dword ptr ds : [esi + 0xC38]
		mov eax, dword ptr ss : [ebp + 0xC]						//part of original steam code - appId of bindings to be switched gets moved into eax register
		mov currentBindings, eax								//move into "currentBindings" variable
	}

	if (currentBindings != desktopBindingsID					//if the current bindings aren't desktop, big picture, or steam-chord bindings
		&& currentBindings != bigPictureBindingsID				//they have to be our game bindings
		&& currentBindings != steamChordBindingsID)				//we can grab them here, because bindings switch right after we have injected and the target changes focused window
	{
		enforceBindingsID = currentBindings;
	}

	if (currentBindings == desktopBindingsID)					//if steam wants to set desktop-bindings
	{
		__asm
		{
			mov eax, enforceBindingsID							//move appid of bindings to enforce into eax register
		}
	}

	__asm
	{
		jmp[JMPBack]											//jump back and continiue with original steam function 
	}															
}
//\\\


__declspec(naked) void enforceBindingsHookFn_V4()
{
	__asm
	{
		mov eax, dword ptr ss : [ebp+0xC]					 //appId of bindings to be switched gets moved into ecx register
		mov currentBindings, eax								//move into "currentBindings" variable
	}

	if (currentBindings != desktopBindingsID					//if the current bindings aren't desktop, big picture, or steam-chord bindings
		&& currentBindings != bigPictureBindingsID				//they have to be our game bindings
		&& currentBindings != steamChordBindingsID)				//we can grab them here, because bindings switch right after we have injected and the target changes focused window
	{
		enforceBindingsID = currentBindings;
	}

	if (currentBindings == desktopBindingsID)					//if steam wants to set desktop-bindings
	{
		__asm
		{
			mov eax, enforceBindingsID							//move appid of bindings to enforce into ecx register
		}
	}

	__asm
	{
		mov dword ptr ss : [ebp - 0xC], eax
		lea eax, dword ptr ss : [ebp - 0x10]
		push eax
		mov dword ptr ss : [ebp - 0x10], edi
		jmp[JMPBack]											//jump back and continiue with original steam function 
	}
}
//\\\

std::vector<void(*)()> hook_funs = {
	enforceBindingsHookFn_V0,
	enforceBindingsHookFn_V1,
	enforceBindingsHookFn_V2,
	enforceBindingsHookFn_V3,
	enforceBindingsHookFn_V4,
};


void EnforceBindings::patchBytes()
{
	for (int i = 0; i < sig_bytes.size(); i++)
	{
		address = FindPattern("steamclient.dll", sig_bytes[i].c_str(), masks[i].c_str());
		if (address != NULL)
		{
			patchversion = i;
			JMPBack = address + sig_bytes[i].length();
			PlaceJMP((BYTE*)address, (DWORD)hook_funs[i], sig_bytes[i].length());
			return;
		}
	}
}

void EnforceBindings::Unpatch()
{
	if (address != NULL)
	{
		RestoreBytes((BYTE*)address, (BYTE*)sig_bytes[patchversion].c_str(), sig_bytes[patchversion].length());
	}
}


//places a jmp instruction to a __declspec(naked) function on a given adress
//nops the rest of bytes to don't break any instructions
//part of patched code may has to be executed in the hook function
void EnforceBindings::PlaceJMP(BYTE * Address, DWORD jumpTo, DWORD lenght)	
{
	DWORD dwOldProtect, dwBkup, dwReloadAddr;
	VirtualProtect(Address, lenght, PAGE_EXECUTE_READWRITE, &dwOldProtect);	
	dwReloadAddr = (jumpTo - (DWORD)Address) - 5;								//5 == lenght of jump instruction (1byte + 4byte address)
	*Address = 0xE9; //jmp instrcution
	*((DWORD*)(Address + 0x1)) = dwReloadAddr;

	for (DWORD x = 5; x < lenght; x++)
		*(Address + x) = 0x90;							//nop the rest

	VirtualProtect(Address, lenght, dwOldProtect, &dwBkup);
}

void EnforceBindings::RestoreBytes(BYTE * Address, BYTE * original, DWORD lenght)
{
	DWORD dwOldProtect, dwBkup, dwReloadAddr;
	VirtualProtect(Address, lenght, PAGE_EXECUTE_READWRITE, &dwOldProtect);		


	for (DWORD x = 0; x < lenght; x++)
	{
		*(Address + x) = *(original + x);
	}

	VirtualProtect(Address, lenght, dwOldProtect, &dwBkup);
}

MODULEINFO EnforceBindings::GetModInfo(char * szModule)
{
	MODULEINFO ret = { NULL };
	HMODULE mod = GetModuleHandleA(szModule);

	if (mod != 0)
		GetModuleInformation(GetCurrentProcess(), mod, &ret, sizeof(MODULEINFO));
	return ret;
}

//returns memory address of given pattern ind given module
DWORD EnforceBindings::FindPattern(char * module, const char * pattern, const char * mask)
{
	MODULEINFO mInfo = GetModInfo(module);
	DWORD baseAddr = (DWORD)mInfo.lpBaseOfDll;
	DWORD size = mInfo.SizeOfImage;

	DWORD patLenght = strlen(mask);

	for (DWORD i = 0; i < size - patLenght; i++)	//bad for loop btw...
	{
		bool found = true;
		for (DWORD j = 0; j < patLenght; j++)
			found &= mask[j] == '?' || pattern[j] == *(char*)(baseAddr + j + i);

		if (found)
			return baseAddr + i;

	}

	return NULL;
}