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snaphatsnaphat
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Add implementation
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‎BetterRandom.bat‎

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@echo off
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setlocal enabledelayedexpansion
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REM BG EE: Baldur.exe
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REM BG2 EE: Baldur.exe
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REM IWD EE: Icewind.exe
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REM Torment EE: Torment.exe
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REM BG : BGMain2.exe
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REM BG2 : BGMain.exe
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REM IWD: IDMain.exe
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REM Torment: Torment.exe
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REM Check for original executables (BGMain2.exe is for BG and BGMain.exe is for BG2)
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if exist "BGMain2.exe" (set "TARGET_EXE=BGMain2.exe" & goto :next)
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if exist "BGMain.exe" (set "TARGET_EXE=BGMain.exe" & goto :next)
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if exist "IDMain.exe" (set "TARGET_EXE=IDMain.exe" & goto :next)
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if exist "Torment.exe" (set "TARGET_EXE=Torment.exe" & goto :next)
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REM Check for EE executables
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if exist "Baldur.exe" (set "TARGET_EXE=Baldur.exe" & goto :next)
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if exist "Baldur2.exe" (set "TARGET_EXE=Baldur2.exe" & goto :next)
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if exist "Icewind.exe" (set "TARGET_EXE=Icewind.exe" & goto :next)
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if exist "Torment.exe" (set "TARGET_EXE=Torment.exe" & goto :next)
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echo No matching executable found. Exiting...
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exit /b 1
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:next
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REM Check if the executable is 32-bit
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for /f %%G in ('powershell -NoProfile -Command "(get-content '%TARGET_EXE%' -totalcount 50) | select-string -Pattern 'PE..L' -Quiet"') do ( set "IS32EXE=%%G" )
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REM Check if the executable is 64-bit
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for /f %%G in ('powershell -NoProfile -Command "(get-content '%TARGET_EXE%' -totalcount 50) | select-string -Pattern 'PE..d' -Quiet"') do ( set "IS64EXE=%%G" )
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REM Check for 32-bit target executable
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if "%IS32EXE%"=="True" (
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set "DLL_NAME=BetterRandom_x86.dll"
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set "SETDLL=setdll_x86.exe"
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REM Additional actions for 32-bit executable...
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)
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REM Check for 64-bit target executable
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if "%IS64EXE%"=="True" (
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set "DLL_NAME=BetterRandom_x64.dll"
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set "SETDLL=setdll_x64.exe"
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REM Additional actions for 64-bit executable...
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)
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REM Prompt user for action
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echo 1. Add better random library to %TARGET_EXE%
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echo 2. Remove better random library from %TARGET_EXE%
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set /p "ACTION=Enter action number (1 or 2): "
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REM Process user's choice
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if "!ACTION!"=="1" (
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REM Inject the BetterRandom library using setdll.exe
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%SETDLL% /d:%DLL_NAME% %TARGET_EXE%
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) else if "!ACTION!"=="2" (
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REM Remove the BetterRandom libary using setdll.exe
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echo %SETDLL%
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%SETDLL% /r %TARGET_EXE%
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) else (
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echo Invalid action number. Exiting...
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)
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endlocal

‎BetterRandom.cpp‎

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#include <Windows.h>
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#include <detours.h>
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#include <random>
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#include <psapi.h>
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#include <winnt.h>
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#include <dbghelp.h>
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// Original function pointer
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typedef int(WINAPI *OriginalRandFunc)();
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// Pointer to the original rand() function
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OriginalRandFunc pOriginalRand = NULL;
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std::random_device rd; // Non-deterministic random number generator
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std::uniform_int_distribution<> dist(0, RAND_MAX); // Distribute results between 0 and RAND_MAX
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std::mt19937 gen(rd()); // Seed Mersenne Twister generator
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// Typedef for the original function
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typedef int (*OriginalFunc)(int);
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// Pointer to the original function
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OriginalFunc pOriginalFunction = nullptr;
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// Hooked function for rand()
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__declspec(dllexport) int WINAPI HookedRand()
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{
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// Call the custom implementation instead of the original function
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return dist(gen);
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}
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bool MatchPattern(const unsigned char* data, const unsigned char* pattern, int length)
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{
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for (int i = 0; i < length; ++i)
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{
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// Skip certain characters in the pattern
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if (pattern[i] == '.')
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continue;
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// If the characters don't match, return false
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if (data[i] != pattern[i])
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return false;
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}
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return true;
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}
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// Find the offset of a function within a module using a pattern
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LPBYTE FindFunctionOffset(HMODULE hModule, const unsigned char *pattern, int length)
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{
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// Get the base address of the module
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auto moduleBase = reinterpret_cast<DWORD_PTR>(hModule);
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// Get the module's PE header
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auto ntHeader = ImageNtHeader(hModule);
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if (!ntHeader)
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return 0; // Invalid PE header
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// Get the image section header
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auto sectionHeader = IMAGE_FIRST_SECTION(ntHeader);
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if (!sectionHeader)
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return 0; // Invalid section header
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// Search within the module's code section
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IMAGE_SECTION_HEADER *codeSectionHeader = nullptr;
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for (int i = 0; i < ntHeader->FileHeader.NumberOfSections; ++i)
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{
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if (sectionHeader->Characteristics & IMAGE_SCN_MEM_EXECUTE)
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{
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codeSectionHeader = sectionHeader;
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break;
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}
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sectionHeader++;
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}
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if (!codeSectionHeader)
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return 0x0; // Code section not found
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// Search for the pattern within the code section
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auto codeSectionMemory = reinterpret_cast<const unsigned char *>(moduleBase + codeSectionHeader->VirtualAddress);
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auto endAddress = codeSectionMemory + codeSectionHeader->Misc.VirtualSize - 2;
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for (; codeSectionMemory < endAddress; codeSectionMemory++)
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{
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if (MatchPattern(codeSectionMemory, pattern, length))
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// if (memcmp(codeSectionMemory, pattern, length) == 0)
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return (LPBYTE)codeSectionMemory;
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}
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// Pattern not found
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return 0x0;
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}
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// Function to initialize the hook
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void InitHook()
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{
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// Get the address of the target function
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auto hModule = GetModuleHandle(nullptr);
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LPBYTE pFunctionAddress = 0x0;
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// Find the offset of the target function using a specific pattern
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// Baldur's Gate EE, Baldur's Gate 2 EE, Icewind Dale EE,
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unsigned char pattern1[] = "\x48\x83..\xE8.......\xFD\x43\x03\x00";
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if (pFunctionAddress == 0x0)
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pFunctionAddress = FindFunctionOffset(hModule, pattern1, sizeof(pattern1) - 1);
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// Planescape EE
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unsigned char pattern2[] = "\xE8.......\xFD\x43\x03\x00";
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if (pFunctionAddress == 0x0)
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pFunctionAddress = FindFunctionOffset(hModule, pattern2, sizeof(pattern2) - 1);
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// Baldur's Gate, Baldur's Gate 2, Icewind Dale, Planescape Torment
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unsigned char pattern3[] = "\xE8....\x8B....\xFD\x43\x03\x00";
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if (pFunctionAddress == 0x0)
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pFunctionAddress = FindFunctionOffset(hModule, pattern3, sizeof(pattern3) - 1);
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if (pFunctionAddress == 0x0)
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{
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MessageBoxA(NULL, "original rand() method not found!", "betterrand.dll Error", MB_OK);
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throw("Error: original rand() method not found!");
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}
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SYSTEM_INFO systemInfo;
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GetSystemInfo(&systemInfo);
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auto baseAddress = systemInfo.lpMinimumApplicationAddress;
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auto scanSize = reinterpret_cast<SIZE_T>(systemInfo.lpMaximumApplicationAddress) - reinterpret_cast<SIZE_T>(systemInfo.lpMinimumApplicationAddress);
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// Get module info
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MODULEINFO modinfo = {NULL};
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GetModuleInformation(GetCurrentProcess(), hModule, &modinfo, sizeof(modinfo));
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// Create a trampoline for the original function
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auto pOriginalFunction = reinterpret_cast<OriginalRandFunc>(pFunctionAddress);
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// Detour the function with the custom implementation
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DetourTransactionBegin();
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DetourUpdateThread(GetCurrentThread());
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DetourAttach(&(PVOID &)pOriginalFunction, HookedRand);
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DetourTransactionCommit();
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}
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// Function to remove the hook
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void RemoveHook()
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{
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// Detach the hook
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DetourTransactionBegin();
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DetourUpdateThread(GetCurrentThread());
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DetourDetach(&(PVOID &)pOriginalRand, HookedRand);
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DetourTransactionCommit();
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}
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// Entry point of the DLL
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BOOL WINAPI DllMain(HINSTANCE hinst, DWORD dwReason, LPVOID reserved)
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{
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if (DetourIsHelperProcess())
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{
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return TRUE;
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}
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if (dwReason == DLL_PROCESS_ATTACH)
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{
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// Initialize the hook when the DLL is loaded
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InitHook();
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}
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else if (dwReason == DLL_PROCESS_DETACH)
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{
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// Remove the hook when the DLL is unloaded
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RemoveHook();
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}
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return TRUE;
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}

‎build.bat‎

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@echo off
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REM ===================================================================================================================
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REM Define the path to vswhere
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set "VSWHERE=C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe"
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REM Find the path to Visual Studio
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for /f "usebackq delims=" %%i in (`"%VSWHERE%" -latest -property installationPath`) do (
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set "VS_PATH=%%i"
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goto :SetEnvironment
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)
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:SetEnvironment
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REM Check if Visual Studio was found
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if "%VS_PATH%"=="" (
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echo Visual Studio not found.
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exit /b
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)
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REM Notify user
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echo Visual Studio found at %VS_PATH%
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REM ===================================================================================================================
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SETLOCAL
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REM Run the script to set up the environment variables
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call "%VS_PATH%\VC\Auxiliary\Build\vcvarsall.bat" x64
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REM Build detours
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cd Detours
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SET DETOURS_TARGET_PROCESSOR=X64
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nmake clean
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nmake
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cd ..
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rem Set compilation variables
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set INCLUDE_PATH="Detours\include"
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set LIB_PATH="Detours\lib.X64"
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set OUTPUT_FILE="BetterRandomom_x64.dll"
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set INPUT_FILE="BetterRandom.cpp"
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set LIB_FILES="detours.lib Dbghelp.lib user32.lib"
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rem Compile the code using cl.exe
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cl.exe /O2 /EHsc /LD /I "%INCLUDE_PATH%" /Fe:"%OUTPUT_FILE%" "%INPUT_FILE%" /link /LIBPATH:"%LIB_PATH%" "%LIB_FILES%"
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ENDLOCAl
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REM ===================================================================================================================
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SETLOCAL
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REM Run the script to set up the environment variables
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call "%VS_PATH%\VC\Auxiliary\Build\vcvarsall.bat" x86
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REM Build detours
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cd Detours
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SET DETOURS_TARGET_PROCESSOR=X86
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nmake clean
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nmake
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cd ..
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rem Set compilation variables
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set INCLUDE_PATH="Detours\include"
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set LIB_PATH="Detours\lib.X86"
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set OUTPUT_FILE="BetterRandom_x86.dll"
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set INPUT_FILE="BetterRandom.cpp"
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set LIB_FILES="detours.lib Dbghelp.lib user32.lib"
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rem Compile the code using cl.exe
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cl.exe /O2 /EHsc /LD /I "%INCLUDE_PATH%" /Fe:"%OUTPUT_FILE%" "%INPUT_FILE%" /link /LIBPATH:"%LIB_PATH%" "%LIB_FILES%"
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ENDLOCAL
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REM ===================================================================================================================
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REM Clear and create build directory
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rmdir /S /Q build
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mkdir build
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REM ===================================================================================================================
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REM Move final files into build directory
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cp Detours\LICENSE.md build\LICENSE.detours
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cp LICENSE build\LICENSE.BetterRandom
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cp README.md build
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cp BetterRandom.bat build
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cp Detours\bin.X64\setdll.exe build\setdll_x64.exe
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cp Detours\bin.X86\setdll.exe build\setdll_x86.exe
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mv BetterRandom_x64.dll build
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mv BetterRandom_x86.dll build
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REM ===================================================================================================================
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REM cleanup build intermediate files
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del BetterRandom_x64.exp
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del BetterRandom_x86.exp
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del BetterRandom_x64.lib
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del BetterRandom_x86.lib
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del BetterRandom.obj
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REM ===================================================================================================================
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REM Clean up Detours
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rmdir /S /Q Detours\bin.X64
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rmdir /S /Q Detours\bin.X86
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rmdir /S /Q Detours\lib.X64
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rmdir /S /Q Detours\bin.X86
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rmdir /S /Q Detours\include
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cd Detours
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SETLOCAL
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SET DETOURS_TARGET_PROCESSOR=X64
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call "%VS_PATH%\VC\Auxiliary\Build\vcvarsall.bat" x64
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nmake clean
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ENDLOCAl
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SETLOCAL
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SET DETOURS_TARGET_PROCESSOR=X86
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call "%VS_PATH%\VC\Auxiliary\Build\vcvarsall.bat" x86
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nmake clean
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ENDLOCAl
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cd ..

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