WoW WotLK 3.3.5 - WoWSilicon Mouse Drift Fix

cursorwarp.c

/* 

cursorwarp.c
i686 PE DLL, inject with WoWSilicon mod manager 

build with
brew install mingw-w64
i686-w64-mingw32-gcc -shared -O2 -o cursorwarp.dll cursorwarp.c

*/
#define WIN32_LEAN_AND_MEAN
#include <windows.h>

static BOOL (WINAPI *pSetCursorPos)(int, int);
static int  (WINAPI *pShowCursor)(BOOL);
static BOOL pending_show;

static int WINAPI HookShowCursor(BOOL show) {
    if (show) { pending_show = TRUE; return 0; }
    pending_show = FALSE;
    return pShowCursor(FALSE);
}

static BOOL WINAPI HookSetCursorPos(int x, int y) {
    BOOL ok = pSetCursorPos(x, y);
    if (pending_show) { pending_show = FALSE; pShowCursor(TRUE); }
    return ok;
}

static void PatchIAT(HMODULE mod, const char *dll, const char *name, void *hook) {
    BYTE *base = (BYTE *)mod;
    IMAGE_NT_HEADERS *nt = (IMAGE_NT_HEADERS *)(base + ((IMAGE_DOS_HEADER *)base)->e_lfanew);
    IMAGE_IMPORT_DESCRIPTOR *imp = (IMAGE_IMPORT_DESCRIPTOR *)(base +
        nt->OptionalHeader.DataDirectory[IMAGE_DIRECTORY_ENTRY_IMPORT].VirtualAddress);
    for (; imp->Name; imp++) {
        if (lstrcmpiA((char *)(base + imp->Name), dll)) continue;
        IMAGE_THUNK_DATA *th = (IMAGE_THUNK_DATA *)(base + imp->FirstThunk);
        IMAGE_THUNK_DATA *oth = (IMAGE_THUNK_DATA *)(base + imp->OriginalFirstThunk);
        for (; oth->u1.AddressOfData; ++th, ++oth) {
            if (oth->u1.Ordinal & IMAGE_ORDINAL_FLAG) continue;
            IMAGE_IMPORT_BY_NAME *n = (IMAGE_IMPORT_BY_NAME *)(base + oth->u1.AddressOfData);
            if (lstrcmpA((char *)n->Name, name)) continue;
            DWORD old;
            VirtualProtect(&th->u1.Function, 4, PAGE_EXECUTE_READWRITE, &old);
            th->u1.Function = (DWORD)hook;
            VirtualProtect(&th->u1.Function, 4, old, &old);
            return;
        }
    }
}

BOOL WINAPI DllMain(HINSTANCE h, DWORD r, LPVOID p) {
    if (r == DLL_PROCESS_ATTACH) {
        HMODULE u = GetModuleHandleA("user32.dll");
        pSetCursorPos = (void *)GetProcAddress(u, "SetCursorPos");
        pShowCursor   = (void *)GetProcAddress(u, "ShowCursor");
        HMODULE wow = GetModuleHandleA(NULL);
        PatchIAT(wow, "user32.dll", "SetCursorPos", HookSetCursorPos);
        PatchIAT(wow, "user32.dll", "ShowCursor",   HookShowCursor);
    }
    return TRUE;
}