Add Linux WI-FI state support

Support monitoring WIFI state on Linux through:
- NetworkManager (D-Bus)
- IWD (D-Bus)
- wpa_supplicant (control socket)
- ConnMan (D-Bus)

common/settings/wifi_linux_iwd.go

@@ -0,0 +1,188 @@
+package settings
+
+import (
+	"context"
+	"strings"
+	"time"
+
+	"github.com/sagernet/sing-box/adapter"
+
+	"github.com/godbus/dbus/v5"
+)
+
+type iwdMonitor struct {
+	conn       *dbus.Conn
+	callback   func(adapter.WIFIState)
+	cancel     context.CancelFunc
+	signalChan chan *dbus.Signal
+}
+
+func newIWDMonitor(callback func(adapter.WIFIState)) (WIFIMonitor, error) {
+	conn, err := dbus.ConnectSystemBus()
+	if err != nil {
+		return nil, err
+	}
+	iwdObj := conn.Object("net.connman.iwd", "/")
+	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
+	defer cancel()
+	call := iwdObj.CallWithContext(ctx, "org.freedesktop.DBus.ObjectManager.GetManagedObjects", 0)
+	if call.Err != nil {
+		conn.Close()
+		return nil, call.Err
+	}
+	return &iwdMonitor{conn: conn, callback: callback}, nil
+}
+
+func (m *iwdMonitor) ReadWIFIState() adapter.WIFIState {
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	iwdObj := m.conn.Object("net.connman.iwd", "/")
+	var objects map[dbus.ObjectPath]map[string]map[string]dbus.Variant
+	err := iwdObj.CallWithContext(ctx, "org.freedesktop.DBus.ObjectManager.GetManagedObjects", 0).Store(&objects)
+	if err != nil {
+		return adapter.WIFIState{}
+	}
+
+	for _, interfaces := range objects {
+		stationProps, hasStation := interfaces["net.connman.iwd.Station"]
+		if !hasStation {
+			continue
+		}
+
+		stateVariant, hasState := stationProps["State"]
+		if !hasState {
+			continue
+		}
+		state, ok := stateVariant.Value().(string)
+		if !ok || state != "connected" {
+			continue
+		}
+
+		connectedNetworkVariant, hasNetwork := stationProps["ConnectedNetwork"]
+		if !hasNetwork {
+			continue
+		}
+		networkPath, ok := connectedNetworkVariant.Value().(dbus.ObjectPath)
+		if !ok || networkPath == "/" {
+			continue
+		}
+
+		networkInterfaces, hasNetworkPath := objects[networkPath]
+		if !hasNetworkPath {
+			continue
+		}
+
+		networkProps, hasNetworkInterface := networkInterfaces["net.connman.iwd.Network"]
+		if !hasNetworkInterface {
+			continue
+		}
+
+		nameVariant, hasName := networkProps["Name"]
+		if !hasName {
+			continue
+		}
+		ssid, ok := nameVariant.Value().(string)
+		if !ok {
+			continue
+		}
+
+		connectedBSSVariant, hasBSS := stationProps["ConnectedAccessPoint"]
+		if !hasBSS {
+			return adapter.WIFIState{SSID: ssid}
+		}
+		bssPath, ok := connectedBSSVariant.Value().(dbus.ObjectPath)
+		if !ok || bssPath == "/" {
+			return adapter.WIFIState{SSID: ssid}
+		}
+
+		bssInterfaces, hasBSSPath := objects[bssPath]
+		if !hasBSSPath {
+			return adapter.WIFIState{SSID: ssid}
+		}
+
+		bssProps, hasBSSInterface := bssInterfaces["net.connman.iwd.BasicServiceSet"]
+		if !hasBSSInterface {
+			return adapter.WIFIState{SSID: ssid}
+		}
+
+		addressVariant, hasAddress := bssProps["Address"]
+		if !hasAddress {
+			return adapter.WIFIState{SSID: ssid}
+		}
+		bssid, ok := addressVariant.Value().(string)
+		if !ok {
+			return adapter.WIFIState{SSID: ssid}
+		}
+
+		return adapter.WIFIState{
+			SSID:  ssid,
+			BSSID: strings.ToUpper(strings.ReplaceAll(bssid, ":", "")),
+		}
+	}
+
+	return adapter.WIFIState{}
+}
+
+func (m *iwdMonitor) Start() error {
+	if m.callback == nil {
+		return nil
+	}
+	ctx, cancel := context.WithCancel(context.Background())
+	m.cancel = cancel
+
+	m.signalChan = make(chan *dbus.Signal, 10)
+	m.conn.Signal(m.signalChan)
+
+	err := m.conn.AddMatchSignal(
+		dbus.WithMatchInterface("org.freedesktop.DBus.Properties"),
+		dbus.WithMatchSender("net.connman.iwd"),
+	)
+	if err != nil {
+		return err
+	}
+
+	state := m.ReadWIFIState()
+	go m.monitorSignals(ctx, m.signalChan, state)
+	m.callback(state)
+
+	return nil
+}
+
+func (m *iwdMonitor) monitorSignals(ctx context.Context, signalChan chan *dbus.Signal, lastState adapter.WIFIState) {
+	for {
+		select {
+		case <-ctx.Done():
+			return
+		case signal, ok := <-signalChan:
+			if !ok {
+				return
+			}
+			if signal.Name == "org.freedesktop.DBus.Properties.PropertiesChanged" {
+				state := m.ReadWIFIState()
+				if state != lastState {
+					lastState = state
+					m.callback(state)
+				}
+			}
+		}
+	}
+}
+
+func (m *iwdMonitor) Close() error {
+	if m.cancel != nil {
+		m.cancel()
+	}
+	if m.signalChan != nil {
+		m.conn.RemoveSignal(m.signalChan)
+		close(m.signalChan)
+	}
+	if m.conn != nil {
+		m.conn.RemoveMatchSignal(
+			dbus.WithMatchInterface("org.freedesktop.DBus.Properties"),
+			dbus.WithMatchSender("net.connman.iwd"),
+		)
+		return m.conn.Close()
+	}
+	return nil
+}