detail

proxy/tun/handler.go

@@ -125,7 +125,8 @@ func (t *Handler) Start() error {
 				errors.LogInfo(context.Background(), "[tun] falied to set interface > iface == nil")
 				return errors.New("iface not found")
 			}
-			return c.Control(func(fd uintptr) {
+			var controlErr, sockErr error
+			controlErr = c.Control(func(fd uintptr) {
 				addrPort, _ := netip.ParseAddrPort(address)
 				// skip loopback
 				if addrPort.Addr().IsLoopback() || strings.HasPrefix(strings.ToLower(address), "localhost:") {
@@ -133,9 +134,13 @@ func (t *Handler) Start() error {
 				}
 				err := setinterface(network, address, fd, iface)
 				if err != nil {
-					errors.LogInfoInner(context.Background(), err, "[tun] falied to set interface")
+					sockErr = errors.New("[tun] falied to set interface").Base(err)
 				}
 			})
+			if sockErr != nil {
+				return sockErr
+			}
+			return controlErr
 		})
 	}
 

transport/internet/sockopt.go

@@ -28,3 +28,22 @@ func (v *SocketConfig) ParseTFOValue() int {
 	}
 	return tfo
 }
+
+// Dial should fail on bind errors, return this to indicate such errors.
+type BindError struct {
+	err error
+}
+
+func (e *BindError) Unwrap() error {
+	return e.err
+}
+
+func (e *BindError) Error() string {
+	return "failed to bind to interface: " + e.err.Error()
+}
+
+func NewBindError(err error) *BindError {
+	return &BindError{
+		err: err,
+	}
+}

transport/internet/sockopt_darwin.go

@@ -136,15 +136,15 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 	if config.Interface != "" {
 		iface, err := net.InterfaceByName(config.Interface)
 		if err != nil {
-			return errors.New("failed to get interface ", config.Interface).Base(err)
+			return NewBindError(errors.New("failed to get interface ", config.Interface).Base(err))
 		}
 		if network == "tcp6" || network == "udp6" {
 			if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IPV6, unix.IPV6_BOUND_IF, iface.Index); err != nil {
-				return errors.New("failed to set IPV6_BOUND_IF").Base(err)
+				return NewBindError(errors.New("failed to set IPV6_BOUND_IF").Base(err))
 			}
 		} else {
 			if err := unix.SetsockoptInt(int(fd), unix.IPPROTO_IP, unix.IP_BOUND_IF, iface.Index); err != nil {
-				return errors.New("failed to set IP_BOUND_IF").Base(err)
+				return NewBindError(errors.New("failed to set IP_BOUND_IF").Base(err))
 			}
 		}
 	}

transport/internet/sockopt_linux.go

@@ -22,7 +22,7 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 
 	if config.Interface != "" {
 		if err := syscall.BindToDevice(int(fd), config.Interface); err != nil {
-			return errors.New("failed to set Interface").Base(err)
+			return NewBindError(errors.New("failed to set Interface").Base(err))
 		}
 	}
 

transport/internet/sockopt_windows.go

@@ -35,7 +35,7 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 	if config.Interface != "" {
 		inf, err := net.InterfaceByName(config.Interface)
 		if err != nil {
-			return errors.New("failed to find the interface").Base(err)
+			return NewBindError(errors.New("failed to find the interface").Base(err))
 		}
 		// easy way to check if the address is ipv4
 		isV4 := strings.Contains(address, ".")
@@ -47,20 +47,20 @@ func applyOutboundSocketOptions(network string, address string, fd uintptr, conf
 			binary.BigEndian.PutUint32(bytes[:], uint32(inf.Index))
 			idx := *(*uint32)(unsafe.Pointer(&bytes[0]))
 			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IP, IP_UNICAST_IF, int(idx)); err != nil {
-				return errors.New("failed to set IP_UNICAST_IF").Base(err)
+				return NewBindError(errors.New("failed to set IP_UNICAST_IF").Base(err))
 			}
 			if ip := net.ParseIP(host); ip != nil && ip.IsMulticast() && isUDPSocket(network) {
 				if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IP, syscall.IP_MULTICAST_IF, int(idx)); err != nil {
-					return errors.New("failed to set IP_MULTICAST_IF").Base(err)
+					return NewBindError(errors.New("failed to set IP_MULTICAST_IF").Base(err))
 				}
 			}
 		} else {
 			if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IPV6, IPV6_UNICAST_IF, inf.Index); err != nil {
-				return errors.New("failed to set IPV6_UNICAST_IF").Base(err)
+				return NewBindError(errors.New("failed to set IPV6_UNICAST_IF").Base(err))
 			}
 			if ip := net.ParseIP(host); ip != nil && ip.IsMulticast() && isUDPSocket(network) {
 				if err := syscall.SetsockoptInt(syscall.Handle(fd), syscall.IPPROTO_IPV6, syscall.IPV6_MULTICAST_IF, inf.Index); err != nil {
-					return errors.New("failed to set IPV6_MULTICAST_IF").Base(err)
+					return NewBindError(errors.New("failed to set IPV6_MULTICAST_IF").Base(err))
 				}
 			}
 		}

transport/internet/system_dialer.go

@@ -68,19 +68,27 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 			}
 		}
 		var lc net.ListenConfig
-		lc.Control = func(network, address string, c syscall.RawConn) error {
-			for _, ctl := range Controllers {
-				if err := ctl(network, address, c); err != nil {
-					errors.LogInfoInner(ctx, err, "failed to apply external controller")
-				}
-			}
-			return c.Control(func(fd uintptr) {
-				if sockopt != nil {
-					if err := applyOutboundSocketOptions(network, destAddr.String(), fd, sockopt); err != nil {
-						errors.LogInfo(ctx, err, "failed to apply socket options")
+		if sockopt != nil || len(Controllers) > 0 {
+			lc.Control = func(network, address string, c syscall.RawConn) error {
+				for _, ctl := range Controllers {
+					if err := ctl(network, address, c); err != nil {
+						return errors.New("failed to apply external controller").Base(err)
 					}
 				}
-			})
+				if sockopt != nil {
+					var sockErr, controlErr error
+					controlErr = c.Control(func(fd uintptr) {
+						if sockErr = applyOutboundSocketOptions(network, destAddr.String(), fd, sockopt); sockErr != nil {
+							errors.LogInfoInner(ctx, sockErr, "failed to apply socket options")
+						}
+					})
+					if _, ok := sockErr.(*BindError); ok {
+						return sockErr
+					}
+					return controlErr
+				}
+				return nil
+			}
 		}
 		packetConn, err := lc.ListenPacket(ctx, srcAddr.Network(), srcAddr.String())
 		if err != nil {
@@ -128,16 +136,22 @@ func (d *DefaultSystemDialer) Dial(ctx context.Context, src net.Address, dest ne
 		dialer.Control = func(network, address string, c syscall.RawConn) error {
 			for _, ctl := range Controllers {
 				if err := ctl(network, address, c); err != nil {
-					errors.LogInfoInner(ctx, err, "failed to apply external controller")
+					return errors.New("failed to apply external controller").Base(err)
 				}
 			}
-			return c.Control(func(fd uintptr) {
-				if sockopt != nil {
-					if err := applyOutboundSocketOptions(network, address, fd, sockopt); err != nil {
-						errors.LogInfoInner(ctx, err, "failed to apply socket options")
+			if sockopt != nil {
+				var sockErr, controlErr error
+				controlErr = c.Control(func(fd uintptr) {
+					if sockErr = applyOutboundSocketOptions(network, address, fd, sockopt); sockErr != nil {
+						errors.LogInfoInner(ctx, sockErr, "failed to apply socket options")
 					}
+				})
+				if _, ok := sockErr.(*BindError); ok {
+					return sockErr
 				}
-			})
+				return controlErr
+			}
+			return nil
 		}
 	}