EtherGuard-VPN/tun/wintun/dll_fromfile_windows.go
Jason A. Donenfeld ca9edf1c63 wintun: do not load dll in init()
This prevents linking to wintun.dll until it's actually needed, which
should improve startup time.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2021-01-07 14:49:44 +01:00

55 lines
1.1 KiB
Go

// +build !load_wintun_from_rsrc
/* SPDX-License-Identifier: MIT
*
* Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
*/
package wintun
import (
"fmt"
"sync"
"sync/atomic"
"unsafe"
"golang.org/x/sys/windows"
)
type lazyDLL struct {
Name string
mu sync.Mutex
module windows.Handle
onLoad func(d *lazyDLL)
}
func (d *lazyDLL) Load() error {
if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&d.module))) != nil {
return nil
}
d.mu.Lock()
defer d.mu.Unlock()
if d.module != 0 {
return nil
}
const (
LOAD_LIBRARY_SEARCH_APPLICATION_DIR = 0x00000200
LOAD_LIBRARY_SEARCH_SYSTEM32 = 0x00000800
)
module, err := windows.LoadLibraryEx(d.Name, 0, LOAD_LIBRARY_SEARCH_APPLICATION_DIR|LOAD_LIBRARY_SEARCH_SYSTEM32)
if err != nil {
return fmt.Errorf("Unable to load library: %w", err)
}
atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&d.module)), unsafe.Pointer(module))
if d.onLoad != nil {
d.onLoad(d)
}
return nil
}
func (p *lazyProc) nameToAddr() (uintptr, error) {
return windows.GetProcAddress(p.dll.module, p.Name)
}