[client] Cleanup dns and route states on startup (#2757)

client/internal/routemanager/systemops/state.go

@@ -0,0 +1,81 @@
+package systemops
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/netip"
+	"sync"
+
+	"github.com/hashicorp/go-multierror"
+
+	nberrors "github.com/netbirdio/netbird/client/errors"
+)
+
+type RouteEntry struct {
+	Prefix  netip.Prefix `json:"prefix"`
+	Nexthop Nexthop      `json:"nexthop"`
+}
+
+type ShutdownState struct {
+	Routes map[netip.Prefix]RouteEntry `json:"routes,omitempty"`
+	mu     sync.RWMutex
+}
+
+func NewShutdownState() *ShutdownState {
+	return &ShutdownState{
+		Routes: make(map[netip.Prefix]RouteEntry),
+	}
+}
+
+func (s *ShutdownState) Name() string {
+	return "route_state"
+}
+
+func (s *ShutdownState) Cleanup() error {
+	sysops := NewSysOps(nil, nil)
+	var merr *multierror.Error
+
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	for _, route := range s.Routes {
+		if err := sysops.removeFromRouteTable(route.Prefix, route.Nexthop); err != nil {
+			merr = multierror.Append(merr, fmt.Errorf("remove route %s: %w", route.Prefix, err))
+		}
+	}
+
+	return nberrors.FormatErrorOrNil(merr)
+}
+
+func (s *ShutdownState) UpdateRoute(prefix netip.Prefix, nexthop Nexthop) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	s.Routes[prefix] = RouteEntry{
+		Prefix:  prefix,
+		Nexthop: nexthop,
+	}
+}
+
+func (s *ShutdownState) RemoveRoute(prefix netip.Prefix) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	delete(s.Routes, prefix)
+}
+
+// MarshalJSON ensures that empty routes are marshaled as null
+func (s *ShutdownState) MarshalJSON() ([]byte, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	if len(s.Routes) == 0 {
+		return json.Marshal(nil)
+	}
+
+	return json.Marshal(s.Routes)
+}
+
+func (s *ShutdownState) UnmarshalJSON(data []byte) error {
+	return json.Unmarshal(data, &s.Routes)
+}