Left4Dead 2 C++ Internal DLL Hack

#include <Windows.h>
#include <iostream>
#include <tlhelp32.h>
#include <Psapi.h>

using namespace std;

char module[] = "server.dll";
char sig[] = "\x89\x37\x5F\xB8\x00\x00\x00\x00";
char mask[] = "xxxx????";
char nopOppCode[] = "\x90\x90\x90";

MODULEINFO GetModuleInfo(char *szModule)
{
	MODULEINFO modinfo{ 0 };
	HMODULE hModule = GetModuleHandle(szModule);
	if (hModule == 0)
		return modinfo;
	GetModuleInformation(GetCurrentProcess(), hModule, &modinfo, sizeof(MODULEINFO));
	return modinfo;
}

void WriteToMemory(uintptr_t addressToWrite, char* valueToWrite, int byteNum)
{
	unsigned long OldProtection;
	VirtualProtect((LPVOID)(addressToWrite), byteNum, PAGE_EXECUTE_READWRITE, &OldProtection);
	memcpy((LPVOID)addressToWrite, valueToWrite, byteNum);
	VirtualProtect((LPVOID)(addressToWrite), byteNum, OldProtection, NULL);
}


DWORD FindPattern(char *module, char *pattern, char *mask)
{
	MODULEINFO mInfo = GetModuleInfo(module);
	DWORD base = (DWORD)mInfo.lpBaseOfDll;
	DWORD size = (DWORD)mInfo.SizeOfImage;

	DWORD patternLength = (DWORD)strlen(mask);

	for (DWORD i = 0; i < size - patternLength; i++)
	{
		bool found = true;
		for (DWORD j = 0; j < patternLength; j++)
		{
			found &= mask[j] == '?' || pattern[j] == *(char*)(base + i + j);
		}
		if (found)
		{
			return base + i;
		}
	}

	return NULL;
}


void startDLL()
{
	DWORD foundAddy = FindPattern(module, sig, mask);
	WriteToMemory(foundAddy, nopOppCode, 1);
}

BOOL WINAPI DllMain(
	HINSTANCE hinstDLL,
	DWORD fwdReason,
	LPVOID lpReserved)
{
	switch (fwdReason)
	{
	case DLL_PROCESS_ATTACH:
		MessageBoxA(NULL, "Good to Go", "", 0);
		startDLL();
		break;
	}
	return TRUE;
}