Implement filter goto action support

filter.go

@@ -28,6 +28,11 @@ func (q FilterAttrs) String() string {
 
 type TcAct int32
 
+const (
+	TC_ACT_EXT_SHIFT    = 28
+	TC_ACT_EXT_VAL_MASK = (1 << TC_ACT_EXT_SHIFT) - 1
+)
+
 const (
 	TC_ACT_UNSPEC     TcAct = -1
 	TC_ACT_OK         TcAct = 0
@@ -41,6 +46,22 @@ const (
 	TC_ACT_JUMP       TcAct = 0x10000000
 )
 
+func getTcActExt(local int32) int32 {
+	return local << TC_ACT_EXT_SHIFT
+}
+
+func getTcActGotoChain() TcAct {
+	return TcAct(getTcActExt(2))
+}
+
+func getTcActExtOpcode(combined int32) int32 {
+	return combined & (^TC_ACT_EXT_VAL_MASK)
+}
+
+func TcActExtCmp(combined int32, opcode int32) bool {
+	return getTcActExtOpcode(combined) == opcode
+}
+
 func (a TcAct) String() string {
 	switch a {
 	case TC_ACT_UNSPEC:
@@ -64,6 +85,9 @@ func (a TcAct) String() string {
 	case TC_ACT_JUMP:
 		return "jump"
 	}
+	if TcActExtCmp(int32(a), int32(getTcActGotoChain())) {
+		return "goto"
+	}
 	return fmt.Sprintf("0x%x", int32(a))
 }
 
@@ -113,6 +137,7 @@ type Action interface {
 
 type GenericAction struct {
 	ActionAttrs
+	Chain int32
 }
 
 func (action *GenericAction) Type() string {

filter_linux.go

@@ -805,6 +805,9 @@ func parseActions(tables []syscall.NetlinkRouteAttr) ([]Action, error) {
 						case nl.TCA_GACT_PARMS:
 							gen := *nl.DeserializeTcGen(adatum.Value)
 							toAttrs(&gen, action.Attrs())
+							if action.Attrs().Action.String() == "goto" {
+								action.(*GenericAction).Chain = TC_ACT_EXT_VAL_MASK & gen.Action
+							}
 						}
 					case "police":
 						parsePolice(adatum, action.(*PoliceAction))

filter_test.go

@@ -1796,6 +1796,12 @@ func TestFilterFlowerAddDel(t *testing.T) {
 				MirredAction: TCA_EGRESS_REDIR,
 				Ifindex:      redir.Attrs().Index,
 			},
+			&GenericAction{
+				ActionAttrs: ActionAttrs{
+					Action: getTcActGotoChain(),
+				},
+				Chain: 20,
+			},
 		},
 	}
 
@@ -1859,6 +1865,15 @@ func TestFilterFlowerAddDel(t *testing.T) {
 		t.Fatal("Mirred action isn't TC_ACT_STOLEN")
 	}
 
+	ga, ok := flower.Actions[1].(*GenericAction)
+	if !ok {
+		t.Fatal("Unable to find generic action")
+	}
+
+	if ga.Attrs().Action != getTcActGotoChain() {
+		t.Fatal("Generic action isn't TC_ACT_GOTO_CHAIN")
+	}
+
 	if err := FilterDel(filter); err != nil {
 		t.Fatal(err)
 	}

nl/tc_linux.go

@@ -101,7 +101,7 @@ const (
 	SizeofTcHtbGlob      = 0x14
 	SizeofTcU32Key       = 0x10
 	SizeofTcU32Sel       = 0x10 // without keys
-	SizeofTcGen          = 0x14
+	SizeofTcGen          = 0x16
 	SizeofTcConnmark     = SizeofTcGen + 0x04
 	SizeofTcCsum         = SizeofTcGen + 0x04
 	SizeofTcMirred       = SizeofTcGen + 0x08