Add support for the expires option of ip route

Author: albertjin

route.go

@@ -45,6 +45,17 @@ type Encap interface {
 	Equal(Encap) bool
 }
 
+type RouteCacheInfo struct {
+	Users   uint32
+	Age     uint32
+	Expires int32
+	Error   uint32
+	Used    uint32
+	Id      uint32
+	Ts      uint32
+	Tsage   uint32
+}
+
 // Protocol describe what was the originator of the route
 type RouteProtocol int
 
@@ -87,6 +98,8 @@ type Route struct {
 	QuickACK         int
 	Congctl          string
 	FastOpenNoCookie int
+	Expires          int
+	CacheInfo        *RouteCacheInfo
 }
 
 func (r Route) String() string {
@@ -117,6 +130,9 @@ func (r Route) String() string {
 	elems = append(elems, fmt.Sprintf("Flags: %s", r.ListFlags()))
 	elems = append(elems, fmt.Sprintf("Table: %d", r.Table))
 	elems = append(elems, fmt.Sprintf("Realm: %d", r.Realm))
+	if r.Expires != 0 {
+		elems = append(elems, fmt.Sprintf("Expires: %dsec", r.Expires))
+	}
 	return fmt.Sprintf("{%s}", strings.Join(elems, " "))
 }
 

route_linux.go

@@ -1086,6 +1086,12 @@ func (h *Handle) prepareRouteReq(route *Route, req *nl.NetlinkRequest, msg *nl.R
 		msg.Type = uint8(route.Type)
 	}
 
+	if route.Expires > 0 {
+		b := make([]byte, 4)
+		native.PutUint32(b, uint32(route.Expires))
+		rtAttrs = append(rtAttrs, nl.NewRtAttr(unix.RTA_EXPIRES, b))
+	}
+
 	var metrics []*nl.RtAttr
 	if route.MTU > 0 {
 		b := nl.Uint32Attr(uint32(route.MTU))
@@ -1320,6 +1326,25 @@ func (h *Handle) RouteListFilteredIter(family int, filter *Route, filterMask uin
 	return executeErr
 }
 
+// deserializeRouteCacheInfo decodes a RTA_CACHEINFO attribute into a RouteCacheInfo struct
+func deserializeRouteCacheInfo(b []byte) (*RouteCacheInfo, error) {
+	if len(b) != 32 {
+		return nil, unix.EINVAL
+	}
+
+	e := nl.NativeEndian()
+	return &RouteCacheInfo{
+		e.Uint32(b),
+		e.Uint32(b[4:]),
+		int32(e.Uint32(b[8:])),
+		e.Uint32(b[12:]),
+		e.Uint32(b[16:]),
+		e.Uint32(b[20:]),
+		e.Uint32(b[24:]),
+		e.Uint32(b[28:]),
+	}, nil
+}
+
 // deserializeRoute decodes a binary netlink message into a Route struct
 func deserializeRoute(m []byte) (Route, error) {
 	msg := nl.DeserializeRtMsg(m)
@@ -1363,6 +1388,12 @@ func deserializeRoute(m []byte) (Route, error) {
 			route.ILinkIndex = int(native.Uint32(attr.Value[0:4]))
 		case unix.RTA_PRIORITY:
 			route.Priority = int(native.Uint32(attr.Value[0:4]))
+		case unix.RTA_CACHEINFO:
+			route.CacheInfo, err = deserializeRouteCacheInfo(attr.Value)
+			if err != nil {
+				return route, err
+			}
+			route.Expires = int(route.CacheInfo.Expires) / 100
 		case unix.RTA_FLOW:
 			route.Realm = int(native.Uint32(attr.Value[0:4]))
 		case unix.RTA_TABLE:

route_test.go

@@ -192,7 +192,7 @@ func TestRoute6AddDel(t *testing.T) {
 		IP:   net.ParseIP("2001:db8::0"),
 		Mask: net.CIDRMask(64, 128),
 	}
-	route := Route{LinkIndex: link.Attrs().Index, Dst: dst}
+	route := Route{LinkIndex: link.Attrs().Index, Dst: dst, Expires: 10}
 	if err := RouteAdd(&route); err != nil {
 		t.Fatal(err)
 	}
@@ -204,6 +204,25 @@ func TestRoute6AddDel(t *testing.T) {
 		t.Fatal("Route not added properly")
 	}
 
+	// route expiry is supported by kernel 4.4+
+	k, m, err := KernelVersion()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if k > 4 || (k == 4 && m > 4) {
+		foundExpires := false
+		for _, route := range routes {
+			if route.Dst.IP.Equal(dst.IP) {
+				if route.Expires > 0 && route.Expires <= 10 {
+					foundExpires = true
+				}
+			}
+		}
+		if !foundExpires {
+			t.Fatal("Route 'expires' not set")
+		}
+	}
+
 	dstIP := net.ParseIP("2001:db8::1")
 	routeToDstIP, err := RouteGet(dstIP)
 	if err != nil {