Add windows support

internal/wintun/dll_windows.go

@@ -0,0 +1,98 @@
+/* SPDX-License-Identifier: MIT
+ *
+ * Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
+ */
+
+package wintun
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"unsafe"
+
+	"github.com/sagernet/sing-tun/internal/wintun/memmod"
+
+	"golang.org/x/sys/windows"
+)
+
+func (d *lazyDLL) NewProc(name string) *lazyProc {
+	return &lazyProc{dll: d, Name: name}
+}
+
+type lazyProc struct {
+	Name string
+	mu   sync.Mutex
+	dll  *lazyDLL
+	addr uintptr
+}
+
+func (p *lazyProc) Find() error {
+	if atomic.LoadPointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr))) != nil {
+		return nil
+	}
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	if p.addr != 0 {
+		return nil
+	}
+
+	err := p.dll.Load()
+	if err != nil {
+		return fmt.Errorf("error loading DLL: %s, MODULE: %s, error: %w", p.dll.Name, p.Name, err)
+	}
+	addr, err := p.nameToAddr()
+	if err != nil {
+		return fmt.Errorf("error getting %s address: %w", p.Name, err)
+	}
+
+	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&p.addr)), unsafe.Pointer(addr))
+	return nil
+}
+
+func (p *lazyProc) Addr() uintptr {
+	err := p.Find()
+	if err != nil {
+		panic(err)
+	}
+	return p.addr
+}
+
+func (p *lazyProc) Load() error {
+	return p.dll.Load()
+}
+
+type lazyDLL struct {
+	Name   string
+	Base   windows.Handle
+	mu     sync.Mutex
+	module *memmod.Module
+}
+
+func newLazyDLL(name string) *lazyDLL {
+	return &lazyDLL{Name: name}
+}
+
+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 != nil {
+		return nil
+	}
+
+	module, err := memmod.LoadLibrary(dllContent)
+	if err != nil {
+		return fmt.Errorf("unable to load library: %w", err)
+	}
+	d.Base = windows.Handle(module.BaseAddr())
+
+	atomic.StorePointer((*unsafe.Pointer)(unsafe.Pointer(&d.module)), unsafe.Pointer(module))
+	return nil
+}
+
+func (p *lazyProc) nameToAddr() (uintptr, error) {
+	return p.dll.module.ProcAddressByName(p.Name)
+}