netbird/client/ui/tray_watcher_linux.go

//go:build linux && !(linux && 386)

package main

// startStatusNotifierWatcher registers org.kde.StatusNotifierWatcher on the
// session D-Bus if no other process has already claimed it.
//
// Minimal window managers (Fluxbox, OpenBox, i3, etc.) do not ship a
// StatusNotifier watcher, so tray icons using libayatana-appindicator or
// the KDE/freedesktop StatusNotifier protocol silently fail.
//
// By owning the watcher name in-process we allow the Wails v3 built-in tray
// to register itself — no external daemon or package needed.
//
// When an XEmbed system tray is available (_NET_SYSTEM_TRAY_S0), we also
// start an in-process XEmbed host that bridges the SNI icon into the
// XEmbed tray (Fluxbox, IceWM, etc.).

import (
	"sync"
	"time"

	"github.com/godbus/dbus/v5"
	log "github.com/sirupsen/logrus"
)

const (
	watcherName  = "org.kde.StatusNotifierWatcher"
	watcherPath  = "/StatusNotifierWatcher"
	watcherIface = "org.kde.StatusNotifierWatcher"

	// watcherProbeInterval / watcherProbeTimeout bound how long we keep
	// re-probing for an XEmbed tray before giving up. The UI is commonly
	// autostarted *before* the panel/tray on minimal WMs, so a single probe
	// at startup would miss a tray that comes up a second or two later and
	// the icon would silently never appear. ~10s of polling covers a slow
	// panel launch while staying short enough that a headless / pure-Wayland
	// session (no XEmbed tray ever) winds down quickly.
	watcherProbeInterval = 500 * time.Millisecond
	watcherProbeTimeout  = 10 * time.Second
)

type statusNotifierWatcher struct {
	conn    *dbus.Conn
	items   []string
	hosts   map[string]*xembedHost
	hostsMu sync.Mutex
}

// RegisterStatusNotifierItem is the D-Bus method called by tray clients.
// The sender parameter is automatically injected by godbus with the caller's
// unique bus name (e.g. ":1.42"). It does not appear in the D-Bus signature.
func (w *statusNotifierWatcher) RegisterStatusNotifierItem(sender dbus.Sender, service string) *dbus.Error {
	for _, s := range w.items {
		if s == service {
			return nil
		}
	}
	w.items = append(w.items, service)
	log.Debugf("StatusNotifierWatcher: registered item %q from %s", service, sender)

	go w.tryStartXembedHost(string(sender), dbus.ObjectPath(service))
	return nil
}

// RegisterStatusNotifierHost is required by the protocol but unused here.
func (w *statusNotifierWatcher) RegisterStatusNotifierHost(service string) *dbus.Error {
	log.Debugf("StatusNotifierWatcher: host registered %q", service)
	return nil
}

// tryStartXembedHost attempts to create an XEmbed tray icon for the given
// SNI item. If no XEmbed tray manager is available, this is a no-op.
func (w *statusNotifierWatcher) tryStartXembedHost(busName string, objPath dbus.ObjectPath) {
	w.hostsMu.Lock()
	defer w.hostsMu.Unlock()

	if _, exists := w.hosts[busName]; exists {
		return
	}

	// Use a private session bus so our signal subscriptions don't
	// interfere with Wails' signal handler (which panics on unexpected signals).
	sessionConn, err := dbus.SessionBusPrivate()
	if err != nil {
		log.Debugf("StatusNotifierWatcher: cannot open private session bus for XEmbed host: %v", err)
		return
	}
	if err := sessionConn.Auth(nil); err != nil {
		log.Debugf("StatusNotifierWatcher: XEmbed host auth failed: %v", err)
		_ = sessionConn.Close()
		return
	}
	if err := sessionConn.Hello(); err != nil {
		log.Debugf("StatusNotifierWatcher: XEmbed host Hello failed: %v", err)
		_ = sessionConn.Close()
		return
	}

	host, err := newXembedHost(sessionConn, busName, objPath)
	if err != nil {
		log.Debugf("StatusNotifierWatcher: XEmbed host not started: %v", err)
		return
	}

	w.hosts[busName] = host
	go host.run()
	log.Infof("StatusNotifierWatcher: XEmbed tray icon created for %s", busName)
}

// startStatusNotifierWatcher claims org.kde.StatusNotifierWatcher on the
// session bus, but ONLY as a bridge to an XEmbed system tray on minimal WMs.
//
// The in-process watcher is a stub: its RegisterStatusNotifierItem only
// tracks items so it can mirror them into an XEmbed tray icon — it does
// NOT relay them to any other StatusNotifierHost. So if we claim the name
// on a desktop that has a real watcher/host (e.g. Hyprland + Waybar), every
// other tray app (Slack, etc.) registers into our dead-end watcher and its
// icon never reaches the real host. We won that name purely by starting
// first; a GetNameOwner check doesn't help against a login-order race.
//
// The correct discriminator is whether an XEmbed tray actually exists. If
// one does, we are the bridge of last resort and should claim the watcher.
// If not (pure Wayland, or any environment already running a real watcher),
// we have nothing to bridge and must stay off the bus entirely so the real
// watcher owns the name. Safe to call unconditionally.
//
// The XEmbed tray may come up *after* the UI (the panel and the autostarted
// app race at login), so we re-probe for a short grace period instead of
// deciding once at startup. The probing runs in a goroutine so it never
// blocks the caller's startup path.
func startStatusNotifierWatcher() {
	go func() {
		deadline := time.Now().Add(watcherProbeTimeout)
		for {
			if xembedTrayAvailable() {
				claimStatusNotifierWatcher()
				return
			}
			if time.Now().After(deadline) {
				log.Debugf("StatusNotifierWatcher: no XEmbed tray appeared within %s, leaving the watcher to the desktop", watcherProbeTimeout)
				return
			}
			time.Sleep(watcherProbeInterval)
		}
	}()
}

// claimStatusNotifierWatcher opens a private session-bus connection and takes
// ownership of org.kde.StatusNotifierWatcher, exporting the in-process stub
// watcher. The caller has already confirmed an XEmbed tray is present, so we
// genuinely have an item to bridge. The GetNameOwner / DoNotQueue guards still
// back off if a real watcher already holds the name.
func claimStatusNotifierWatcher() {
	conn, err := dbus.SessionBusPrivate()
	if err != nil {
		log.Debugf("StatusNotifierWatcher: cannot open private session bus: %v", err)
		return
	}
	if err := conn.Auth(nil); err != nil {
		log.Debugf("StatusNotifierWatcher: auth failed: %v", err)
		_ = conn.Close()
		return
	}
	if err := conn.Hello(); err != nil {
		log.Debugf("StatusNotifierWatcher: Hello failed: %v", err)
		_ = conn.Close()
		return
	}

	// Check whether another process already owns the watcher name.
	var owner string
	callErr := conn.BusObject().Call("org.freedesktop.DBus.GetNameOwner", 0, watcherName).Store(&owner)
	if callErr == nil && owner != "" {
		log.Debugf("StatusNotifierWatcher: already owned by %s, skipping", owner)
		_ = conn.Close()
		return
	}

	reply, err := conn.RequestName(watcherName, dbus.NameFlagDoNotQueue)
	if err != nil || reply != dbus.RequestNameReplyPrimaryOwner {
		log.Debugf("StatusNotifierWatcher: could not claim name (reply=%v err=%v)", reply, err)
		_ = conn.Close()
		return
	}

	w := &statusNotifierWatcher{
		conn:  conn,
		hosts: make(map[string]*xembedHost),
	}
	if err := conn.ExportAll(w, dbus.ObjectPath(watcherPath), watcherIface); err != nil {
		log.Errorf("StatusNotifierWatcher: export failed: %v", err)
		_ = conn.Close()
		return
	}

	log.Infof("StatusNotifierWatcher: active on session bus (enables tray on minimal WMs)")
	// Connection intentionally kept open for the lifetime of the process.
}