WireGuard outbound: Keep the device when its setup fails (#7151)

https://github.com/XTLS/Xray-core/pull/7151#issuecomment-6186150131

Fixes https://github.com/XTLS/Xray-core/pull/7151#issuecomment-6190189547

---------

Co-authored-by: LjhAUMEM <llnu14702@gmail.com>

proxy/wireguard/bind.go

@@ -16,8 +16,9 @@ import (
 )
 
 type bind struct {
+	ctx         context.Context
 	resolveFunc func(host string) (net.IP, error)
-	listenFunc  func() (net.PacketConn, error)
+	listenFunc  func(ctx context.Context) (net.PacketConn, error)
 	downFunc    func() error
 	reserved    []byte
 
@@ -26,6 +27,12 @@ type bind struct {
 	mu      sync.Mutex
 }
 
+func (b *bind) SetCtx(ctx context.Context) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	b.ctx = ctx
+}
+
 func (b *bind) Open(port uint16) (fns []conn.ReceiveFunc, actualPort uint16, err error) {
 	b.mu.Lock()
 	defer b.mu.Unlock()
@@ -34,7 +41,7 @@ func (b *bind) Open(port uint16) (fns []conn.ReceiveFunc, actualPort uint16, err
 		return nil, 0, conn.ErrBindAlreadyOpen
 	}
 
-	c, err := b.listenFunc()
+	c, err := b.listenFunc(b.ctx)
 	if err != nil {
 		return nil, 0, err
 	}
@@ -52,12 +59,9 @@ func (b *bind) Open(port uint16) (fns []conn.ReceiveFunc, actualPort uint16, err
 						case <-ch:
 						default:
 							errors.LogErrorInner(context.Background(), err, "unexpected closed")
-							b.mu.Lock()
-							downFunc := b.downFunc
-							b.mu.Unlock()
-							if downFunc != nil {
+							if b.downFunc != nil {
 								go func() {
-									common.Must(downFunc())
+									common.Must(b.downFunc())
 								}()
 							}
 						}
@@ -79,13 +83,6 @@ func (b *bind) Open(port uint16) (fns []conn.ReceiveFunc, actualPort uint16, err
 	}, uint16(c.LocalAddr().(*net.UDPAddr).Port), nil
 }
 
-// setDownFunc sets downFunc after the device is created, since the device may already be using the bind.
-func (b *bind) setDownFunc(f func() error) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
-	b.downFunc = f
-}
-
 func (b *bind) Close() error {
 	b.mu.Lock()
 	defer b.mu.Unlock()