[client] Implement dns routes for Android (#3989)

client/internal/routemanager/notifier/notifier_ios.go

@@ -0,0 +1,80 @@
+//go:build ios
+
+package notifier
+
+import (
+	"net/netip"
+	"slices"
+	"sort"
+	"strings"
+	"sync"
+
+	"github.com/netbirdio/netbird/client/internal/listener"
+	"github.com/netbirdio/netbird/route"
+)
+
+type Notifier struct {
+	currentPrefixes []string
+
+	listener    listener.NetworkChangeListener
+	listenerMux sync.Mutex
+}
+
+func NewNotifier() *Notifier {
+	return &Notifier{}
+}
+
+func (n *Notifier) SetListener(listener listener.NetworkChangeListener) {
+	n.listenerMux.Lock()
+	defer n.listenerMux.Unlock()
+	n.listener = listener
+}
+
+func (n *Notifier) SetInitialClientRoutes([]*route.Route, []*route.Route) {
+	// iOS doesn't care about initial routes
+}
+
+func (n *Notifier) OnNewRoutes(route.HAMap) {
+	// Not used on iOS
+}
+
+func (n *Notifier) OnNewPrefixes(prefixes []netip.Prefix) {
+	newNets := make([]string, 0)
+	for _, prefix := range prefixes {
+		newNets = append(newNets, prefix.String())
+	}
+
+	sort.Strings(newNets)
+
+	if slices.Equal(n.currentPrefixes, newNets) {
+		return
+	}
+
+	n.currentPrefixes = newNets
+	n.notify()
+}
+
+func (n *Notifier) notify() {
+	n.listenerMux.Lock()
+	defer n.listenerMux.Unlock()
+	if n.listener == nil {
+		return
+	}
+
+	go func(l listener.NetworkChangeListener) {
+		l.OnNetworkChanged(strings.Join(n.addIPv6RangeIfNeeded(n.currentPrefixes), ","))
+	}(n.listener)
+}
+
+func (n *Notifier) GetInitialRouteRanges() []string {
+	return nil
+}
+
+func (n *Notifier) addIPv6RangeIfNeeded(inputRanges []string) []string {
+	for _, r := range inputRanges {
+		if r == "0.0.0.0/0" {
+			return append(slices.Clone(inputRanges), "::/0")
+		}
+	}
+	return inputRanges
+}