//go:build (darwin && !ios) || dragonfly || freebsd || netbsd || openbsd package networkmonitor import ( "context" "fmt" "syscall" "unsafe" log "github.com/sirupsen/logrus" "golang.org/x/net/route" "golang.org/x/sys/unix" "github.com/netbirdio/netbird/client/internal/routemanager/systemops" ) func checkChange(ctx context.Context, nexthopv4, nexthopv6 systemops.Nexthop, callback func()) error { fd, err := unix.Socket(syscall.AF_ROUTE, syscall.SOCK_RAW, syscall.AF_UNSPEC) if err != nil { return fmt.Errorf("failed to open routing socket: %v", err) } defer func() { if err := unix.Close(fd); err != nil { log.Errorf("Network monitor: failed to close routing socket: %v", err) } }() for { select { case <-ctx.Done(): return ErrStopped default: buf := make([]byte, 2048) n, err := unix.Read(fd, buf) if err != nil { log.Errorf("Network monitor: failed to read from routing socket: %v", err) continue } if n < unix.SizeofRtMsghdr { log.Errorf("Network monitor: read from routing socket returned less than expected: %d bytes", n) continue } msg := (*unix.RtMsghdr)(unsafe.Pointer(&buf[0])) switch msg.Type { // handle route changes case unix.RTM_ADD, syscall.RTM_DELETE: route, err := parseRouteMessage(buf[:n]) if err != nil { log.Errorf("Network monitor: error parsing routing message: %v", err) continue } if !route.Dst.Addr().IsUnspecified() { continue } intf := "" if route.Interface != nil { intf = route.Interface.Name } switch msg.Type { case unix.RTM_ADD: log.Infof("Network monitor: default route changed: via %s, interface %s", route.Gw, intf) go callback() case unix.RTM_DELETE: if nexthopv4.Intf != nil && route.Gw.Compare(nexthopv4.IP) == 0 || nexthopv6.Intf != nil && route.Gw.Compare(nexthopv6.IP) == 0 { log.Infof("Network monitor: default route removed: via %s, interface %s", route.Gw, intf) go callback() } } } } } } func parseRouteMessage(buf []byte) (*systemops.Route, error) { msgs, err := route.ParseRIB(route.RIBTypeRoute, buf) if err != nil { return nil, fmt.Errorf("parse RIB: %v", err) } if len(msgs) != 1 { return nil, fmt.Errorf("unexpected RIB message msgs: %v", msgs) } msg, ok := msgs[0].(*route.RouteMessage) if !ok { return nil, fmt.Errorf("unexpected RIB message type: %T", msgs[0]) } return systemops.MsgToRoute(msg) }