Standard DLL Injector

[Cartman.]

#define DEFAULT_DLL_NAME                "gamereversal.dll"
#define WIN32_LEAN_AND_MEAN
#include 

// struct with data needed for remote thread.
typedef struct i_data
{
        HINSTANCE       (__stdcall *LoadLibrary)( LPCTSTR lpLibFileName );      
        VOID            (__stdcall *ExitThread)( DWORD dwExitCode );
        VOID            (__stdcall *ExitProcess)( UINT uExitCode );
        int                     (__stdcall *MessageBox)( HWND hWnd, LPCTSTR lpText,     LPCTSTR lpCaption, UINT uType  );
        char            Error[128];
        char            DllName[MAX_PATH];
}i_data;


__inline DWORD __stdcall InjectDll( i_data *i_data )
{
        if( !i_data->LoadLibrary( i_data->DllName ) )
        {
                i_data->MessageBox( NULL, i_data->Error, i_data->Error, NULL );
                i_data->ExitProcess(0);
        }
        i_data->ExitThread(0);
        return 0;
}
__inline void EndInjectDll( void ){ return; }


int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow   )
{
        static PROCESS_INFORMATION      ProcessInformation;
        static STARTUPINFO                      StartupInfo;
        HANDLE                                          hProcess = 0;
        HANDLE                                          hThread = 0;
        i_data                                          idata;
        LPVOID                                          ridata;
        LPVOID                                          rInjectDll;
        DWORD                                           tid;
        char                                            szDll[MAX_PATH];

        if( !CreateProcess(     
                                        NULL,
                                        "<>",
                                        NULL,
                                        NULL,
                                        NULL,
                                        CREATE_SUSPENDED,
                                        NULL,
                                        NULL,
                                        &StartupInfo,
                                        &ProcessInformation ) )
        {
                MessageBox( NULL, "Can't kick start the application", "www.gamereversal.com", NULL );
                return 0;
        }

        hProcess = OpenProcess( PROCESS_ALL_ACCESS, FALSE, ProcessInformation.dwProcessId );

        GetCurrentDirectory( sizeof szDll, szDll );
        wsprintf( szDll, "%s%s", szDll, DEFAULT_DLL_NAME );

        // fill structure with the needed data we gonna pass to remote thread.
        lstrlen( lpCmdLine ) ? lstrcpy( idata.DllName, lpCmdLine ) : lstrcpy( idata.DllName, szDll );
        lstrcpy( idata.Error, "Can't find dll. You can specify the dll name as command line (with no quote marks and full path)." );
        idata.ExitThread = ExitThread;
        idata.ExitProcess = ExitProcess;
        idata.LoadLibrary = LoadLibraryA;
        idata.MessageBox = MessageBoxA;

        // allocate memory on remote process for the thread and the structure.
        ridata  = VirtualAllocEx( hProcess, NULL, sizeof idata, MEM_COMMIT, PAGE_EXECUTE_READWRITE );
        rInjectDll      = VirtualAllocEx( hProcess, NULL, (unsigned int)((unsigned int)EndInjectDll-(unsigned int)InjectDll), MEM_COMMIT, PAGE_EXECUTE_READWRITE );

        if( ridata && rInjectDll )
        {
                // copy data to remote process.
                if( WriteProcessMemory( hProcess, ridata, &idata, sizeof idata, NULL ) && 
                    WriteProcessMemory( hProcess, rInjectDll, InjectDll, (unsigned int)((unsigned int)EndInjectDll-(unsigned int)InjectDll), NULL ) )
                {
                        // create thread on remote process.
                        hThread = CreateRemoteThread( hProcess, 
                                                                                  NULL,
                                                                                  0,
                                                                                  (LPTHREAD_START_ROUTINE)rInjectDll,
                                                                                  ridata,
                                                                                  0,
                                                                                  &tid );
                }
                if( hThread )
                {
                        // wait for remote thread to finish.
                        WaitForSingleObject( hThread, INFINITE );
                        // resume main process thread.
                        ResumeThread( ProcessInformation.hThread );
                        CloseHandle( hThread );
                }
                // free memory allocated on remote process.
                VirtualFreeEx( hProcess, ridata, 0, MEM_RELEASE  ); 
                VirtualFreeEx( hProcess, rInjectDll, 0, MEM_RELEASE      );
        }
        CloseHandle( hProcess );
        return 0;
}