iat SetCursorPos & GetCursorPos hook

#include "Include.h"

#define PtrFromRva(base, rva) (((PBYTE)base) + rva)

void PatchIAT ( HMODULE Module, PSTR ImportedModuleName, PSTR ImportedProcName, PVOID AlternateProc, PVOID* OldProc = 0 )
{
    if ( !Module )
        return;

    PIMAGE_DOS_HEADER           DosHeader = (PIMAGE_DOS_HEADER)Module;
    PIMAGE_NT_HEADERS           NtHeader;
    PIMAGE_IMPORT_DESCRIPTOR    ImportDescriptor;
    UINT                        Index;

    NtHeader = (PIMAGE_NT_HEADERS)PtrFromRva(DosHeader, DosHeader->e_lfanew);

    char msg[8192];

    if ( NtHeader->Signature != IMAGE_NT_SIGNATURE )
        return;

    ImportDescriptor = (PIMAGE_IMPORT_DESCRIPTOR)PtrFromRva(DosHeader, NtHeader->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress);

    for ( Index = 0; ImportDescriptor[Index].Characteristics != 0; Index++ )
    {
        PSTR DllName = (PSTR)PtrFromRva(DosHeader, ImportDescriptor[Index].Name);

        if ( !DllName )
            continue;

        if ( strcmp ( DllName, ImportedModuleName ) == 0 )
        {
            PIMAGE_THUNK_DATA Thunk;
            PIMAGE_THUNK_DATA OrigThunk;

            if ( !ImportDescriptor[Index].FirstThunk || !ImportDescriptor[Index].OriginalFirstThunk )
                return;

            Thunk = (PIMAGE_THUNK_DATA)PtrFromRva(DosHeader, ImportDescriptor[Index].FirstThunk);

            OrigThunk = (PIMAGE_THUNK_DATA)PtrFromRva(DosHeader, ImportDescriptor[Index].OriginalFirstThunk);

            for ( ; OrigThunk->u1.Function != 0; OrigThunk++, Thunk++ )
            {
                if ( OrigThunk->u1.Ordinal & IMAGE_ORDINAL_FLAG )
                    continue;

                PIMAGE_IMPORT_BY_NAME Import = (PIMAGE_IMPORT_BY_NAME)PtrFromRva(DosHeader, OrigThunk->u1.AddressOfData);

                if ( strcmp ( ImportedProcName, (const char*)Import->Name ) == 0 )
                {
                    DWORD Junk;

                    MEMORY_BASIC_INFORMATION MemoryInfo;

                    VirtualQuery ( Thunk, &MemoryInfo, sizeof(MEMORY_BASIC_INFORMATION) );

                    VirtualProtect ( MemoryInfo.BaseAddress, MemoryInfo.RegionSize, PAGE_EXECUTE_READWRITE, &MemoryInfo.Protect );

                    if ( OldProc )
                        *OldProc = (PVOID)Thunk->u1.Function;

                    Thunk->u1.Function = (ULONG)AlternateProc;

                    VirtualProtect ( MemoryInfo.BaseAddress, MemoryInfo.RegionSize, MemoryInfo.Protect, &Junk );

                    return;
                }
            }
        }
    }
}

bool EnableMouseHook = false;

typedef BOOL (WINAPI* SetCursorPosFn)( int X, int Y );
typedef BOOL (WINAPI* GetCursorPosFn)( LPPOINT lpPoint );

SetCursorPosFn oSetCursorPos = 0;
GetCursorPosFn oGetCursorPos = 0;

BOOL WINAPI Hooked_SetCursorPos ( int X, int Y )
{
    if ( EnableMouseHook )
        return TRUE;

    return oSetCursorPos ( X, Y );
}

BOOL WINAPI Hooked_GetCursorPos ( LPPOINT lpPoint )
{
    if ( EnableMouseHook )
    {
        lpPoint->x = 1680 / 2;
        lpPoint->y = 1050 / 2;

        return TRUE;
    }

    return oGetCursorPos ( lpPoint );
}

void InstallHook ()
{
    MODULEENTRY32 me32 = { 0 };

    me32.dwSize = sizeof(MODULEENTRY32);

    HANDLE Snapshot = CreateToolhelp32Snapshot ( TH32CS_SNAPMODULE, GetCurrentProcessId () );

    if ( !Snapshot )
    {
        OutputDebugStringA ( "snapshot failed!\n" );
        return;
    }

    if ( !Module32First ( Snapshot, &me32 ) )
    {
        OutputDebugStringA ( "module32first failed!\n" );
        CloseHandle ( Snapshot );
        return;
    }

    do
    {
        HMODULE Module = me32.hModule;

        PatchIAT ( Module, "USER32.dll", "SetCursorPos", &Hooked_SetCursorPos );
        PatchIAT ( Module, "USER32.dll", "GetCursorPos", &Hooked_GetCursorPos );
    }
    while ( Module32Next ( Snapshot, &me32 ) );

    CloseHandle ( Snapshot );
}

void ShutdownHook ()
{
    MODULEENTRY32 me32 = { 0 };

    me32.dwSize = sizeof(MODULEENTRY32);

    HANDLE Snapshot = CreateToolhelp32Snapshot ( TH32CS_SNAPMODULE, GetCurrentProcessId () );

    if ( !Snapshot )
    {
        OutputDebugStringA ( "snapshot failed!\n" );
        return;
    }

    if ( !Module32First ( Snapshot, &me32 ) )
    {
        OutputDebugStringA ( "module32first failed!\n" );
        CloseHandle ( Snapshot );
        return;
    }

    do
    {
        HMODULE Module = me32.hModule;

        PatchIAT ( Module, "USER32.dll", "SetCursorPos", (PVOID)oSetCursorPos );
        PatchIAT ( Module, "USER32.dll", "GetCursorPos", (PVOID)oGetCursorPos );
    }
    while ( Module32Next ( Snapshot, &me32 ) );

    CloseHandle ( Snapshot );
}

void InitThread ( HMODULE hModule )
{
    oSetCursorPos = (SetCursorPosFn) GetProcAddress ( GetModuleHandleA ( "user32.dll" ), "SetCursorPos" );
    oGetCursorPos = (GetCursorPosFn) GetProcAddress ( GetModuleHandleA ( "user32.dll" ), "GetCursorPos" );

    InstallHook ();

    while ( !GetAsyncKeyState ( VK_F11 ) )
    {
        Sleep ( 100 );

        if ( GetAsyncKeyState ( VK_INSERT ) & 1 )
            EnableMouseHook = !EnableMouseHook;
    }

    ShutdownHook ();
    FreeLibraryAndExitThread ( hModule, 0 );
}

BOOL WINAPI DllMain ( HMODULE hModule, DWORD dwReason, LPVOID lpReserved )
{
    if ( dwReason == DLL_PROCESS_ATTACH )
    {
        DisableThreadLibraryCalls ( hModule );

        CreateThread ( 0, 0, (LPTHREAD_START_ROUTINE)InitThread, hModule, 0, 0 );
    }
    else if ( dwReason == DLL_PROCESS_DETACH )
    {
        ShutdownHook ();
    }

    return TRUE;
}