Add darwin monitor

monitor_darwin.go

@@ -0,0 +1,171 @@
+package tun
+
+import (
+	"context"
+	"net"
+	"net/netip"
+	"os"
+	"sync"
+
+	"github.com/sagernet/sing/common"
+	E "github.com/sagernet/sing/common/exceptions"
+	"github.com/sagernet/sing/common/x/list"
+
+	"golang.org/x/net/route"
+	"golang.org/x/sys/unix"
+)
+
+type networkUpdateMonitor struct {
+	errorHandler E.Handler
+
+	access      sync.Mutex
+	callbacks   list.List[NetworkUpdateCallback]
+	routeSocket *os.File
+}
+
+func NewNetworkUpdateMonitor(errorHandler E.Handler) (NetworkUpdateMonitor, error) {
+	return &networkUpdateMonitor{
+		errorHandler: errorHandler,
+	}, nil
+}
+
+func (m *networkUpdateMonitor) RegisterCallback(callback NetworkUpdateCallback) *list.Element[NetworkUpdateCallback] {
+	m.access.Lock()
+	defer m.access.Unlock()
+	return m.callbacks.PushBack(callback)
+}
+
+func (m *networkUpdateMonitor) UnregisterCallback(element *list.Element[NetworkUpdateCallback]) {
+	m.access.Lock()
+	defer m.access.Unlock()
+	m.callbacks.Remove(element)
+}
+
+func (m *networkUpdateMonitor) emit() {
+	m.access.Lock()
+	callbacks := m.callbacks.Array()
+	m.access.Unlock()
+	for _, callback := range callbacks {
+		err := callback()
+		if err != nil {
+			m.errorHandler.NewError(context.Background(), err)
+		}
+	}
+}
+
+func (m *networkUpdateMonitor) Start() error {
+	routeSocket, err := unix.Socket(unix.AF_ROUTE, unix.SOCK_RAW, 0)
+	if err != nil {
+		return err
+	}
+	err = unix.SetNonblock(routeSocket, true)
+	if err != nil {
+		return err
+	}
+	m.routeSocket = os.NewFile(uintptr(routeSocket), "route")
+	go m.loopUpdate()
+	return nil
+}
+
+func (m *networkUpdateMonitor) loopUpdate() {
+	rawConn, err := m.routeSocket.SyscallConn()
+	if err != nil {
+		m.errorHandler.NewError(context.Background(), err)
+		return
+	}
+	for {
+		var innerErr error
+		err = rawConn.Read(func(fd uintptr) (done bool) {
+			var msg [2048]byte
+			_, innerErr = unix.Read(int(fd), msg[:])
+			return innerErr != unix.EWOULDBLOCK
+		})
+		if innerErr != nil {
+			err = innerErr
+		}
+		if err != nil {
+			break
+		}
+		m.emit()
+	}
+	if !E.IsClosed(err) {
+		m.errorHandler.NewError(context.Background(), err)
+	}
+}
+
+func (m *networkUpdateMonitor) Close() error {
+	return common.Close(common.PtrOrNil(m.routeSocket))
+}
+
+type defaultInterfaceMonitor struct {
+	defaultInterfaceName  string
+	defaultInterfaceIndex int
+	networkMonitor        NetworkUpdateMonitor
+	element               *list.Element[NetworkUpdateCallback]
+	callback              DefaultInterfaceUpdateCallback
+}
+
+func NewDefaultInterfaceMonitor(networkMonitor NetworkUpdateMonitor, callback DefaultInterfaceUpdateCallback) (DefaultInterfaceMonitor, error) {
+	return &defaultInterfaceMonitor{
+		networkMonitor: networkMonitor,
+		callback:       callback,
+	}, nil
+}
+
+func (m *defaultInterfaceMonitor) Start() error {
+	err := m.checkUpdate()
+	if err != nil {
+		return err
+	}
+	m.element = m.networkMonitor.RegisterCallback(m.checkUpdate)
+	return nil
+}
+
+func (m *defaultInterfaceMonitor) Close() error {
+	m.networkMonitor.UnregisterCallback(m.element)
+	return nil
+}
+
+func (m *defaultInterfaceMonitor) DefaultInterfaceName() string {
+	return m.defaultInterfaceName
+}
+
+func (m *defaultInterfaceMonitor) DefaultInterfaceIndex() int {
+	return m.defaultInterfaceIndex
+}
+
+func (m *defaultInterfaceMonitor) checkUpdate() error {
+	ribMessage, err := route.FetchRIB(unix.AF_UNSPEC, route.RIBTypeRoute, 0)
+	if err != nil {
+		return err
+	}
+	routeMessages, err := route.ParseRIB(route.RIBTypeRoute, ribMessage)
+	if err != nil {
+		return err
+	}
+	for _, rawRouteMessage := range routeMessages {
+		routeMessage := rawRouteMessage.(*route.RouteMessage)
+		if common.Any(common.FilterIsInstance(routeMessage.Addrs, func(it route.Addr) (*route.Inet4Addr, bool) {
+			addr, loaded := it.(*route.Inet4Addr)
+			return addr, loaded
+		}), func(addr *route.Inet4Addr) bool {
+			return addr.IP == netip.IPv4Unspecified().As4()
+		}) {
+			oldInterface := m.defaultInterfaceName
+			oldIndex := m.defaultInterfaceIndex
+
+			m.defaultInterfaceIndex = routeMessage.Index
+			defaultInterface, err := net.InterfaceByIndex(routeMessage.Index)
+			if err != nil {
+				return err
+			}
+			m.defaultInterfaceName = defaultInterface.Name
+			if oldInterface == m.defaultInterfaceName && oldIndex == m.defaultInterfaceIndex {
+				return nil
+			}
+			m.callback()
+			return nil
+		}
+	}
+	return ErrNoRoute
+}