#include <Windows.h>
#include <stdio.h>
#include <detours.h>

#include "MemoryUtils.h"

#pragma comment(lib, "detours.lib")

#define VAC_LOADLIBRARY_FORCE_SIGNATURE "\x74\x47\x6A\x01\x6A"
#define LOGFILE_A "C:\\Users\\Username\\Desktop\\vaclog.txt"

typedef HMODULE(WINAPI* LoadLibraryExW_t)(
    LPCWSTR,
    HANDLE,
    DWORD
);

LoadLibraryExW_t originalLoadLibrary;
FILE* log;
HMODULE self;

VOID WriteLog(const char* data) {
    log = fopen(LOGFILE_A, "a");
    fwrite(data, strlen(data), 1, log);
    fclose(log);
}

HMODULE WINAPI HookedLoadLibrary(LPCWSTR lpLibFileName, HANDLE  hFile, DWORD dwFlags) {

    HMODULE loadedModule = originalLoadLibrary(lpLibFileName, hFile, dwFlags);

    if (GetProcAddress(loadedModule, "_runfunc@20")) {

        WriteLog("[*] Blocking VAC loader thread ...\n");
        SuspendThread(GetCurrentThread());

        return 0;
    }

    return loadedModule;
}

VOID PatchVACLoader() {

    Module steamService;
    GetModule("SteamService.dll", &steamService);

    DWORD foundAddress = SearchForSignature(
        steamService.base,
        (unsigned char*)VAC_LOADLIBRARY_FORCE_SIGNATURE,
        5,
        steamService.size
    );

    DWORD oldProtection = 0;

    VirtualProtect((LPVOID)foundAddress, 1, PAGE_EXECUTE_READWRITE, &oldProtection);
    *(BYTE*)foundAddress = 0xEB;
    VirtualProtect((LPVOID)foundAddress, 1, oldProtection, &oldProtection);


}

VOID HookLoadLibrary() {
    DetourTransactionBegin();
    DetourUpdateThread(GetCurrentThread());

    HMODULE kernel = GetModuleHandleA("kernel32.dll");

    originalLoadLibrary =
        (LoadLibraryExW_t)GetProcAddress(kernel, "LoadLibraryExW");

    DetourAttach(&(PVOID&)originalLoadLibrary, HookedLoadLibrary);

    DetourTransactionCommit();
}

BOOL WINAPI DllMain(
    _In_ HINSTANCE hinstDLL,
    _In_ DWORD     fdwReason,
    _In_ LPVOID    lpvReserved
) {

    if (fdwReason != DLL_PROCESS_ATTACH) {
        return TRUE;
    }

    self = hinstDLL;

    log = fopen(LOGFILE_A, "w");
    fwrite("[*] Starting VacBlocker v0.1\n", strlen("[*] Starting VacBlocker v0.1\n") , 1, log);
    fclose(log);

    WriteLog("[*] Hooking LoadLibraryW ...\n");
    HookLoadLibrary();

    WriteLog("[*] Patching SteamService.dll ...\n");
    PatchVACLoader();

    fclose(log);

    return TRUE;
}