filter: Add support for the csum action in u32

This patch adds support for the U32 action that can force a csum
recalculation in different layers of a packet.

filter.go

@@ -157,6 +157,39 @@ func NewConnmarkAction() *ConnmarkAction {
 	}
 }
 
+type CsumUpdateFlags uint32
+
+const (
+	TCA_CSUM_UPDATE_FLAG_IPV4HDR CsumUpdateFlags = 1
+	TCA_CSUM_UPDATE_FLAG_ICMP    CsumUpdateFlags = 2
+	TCA_CSUM_UPDATE_FLAG_IGMP    CsumUpdateFlags = 4
+	TCA_CSUM_UPDATE_FLAG_TCP     CsumUpdateFlags = 8
+	TCA_CSUM_UPDATE_FLAG_UDP     CsumUpdateFlags = 16
+	TCA_CSUM_UPDATE_FLAG_UDPLITE CsumUpdateFlags = 32
+	TCA_CSUM_UPDATE_FLAG_SCTP    CsumUpdateFlags = 64
+)
+
+type CsumAction struct {
+	ActionAttrs
+	UpdateFlags CsumUpdateFlags
+}
+
+func (action *CsumAction) Type() string {
+	return "csum"
+}
+
+func (action *CsumAction) Attrs() *ActionAttrs {
+	return &action.ActionAttrs
+}
+
+func NewCsumAction() *CsumAction {
+	return &CsumAction{
+		ActionAttrs: ActionAttrs{
+			Action: TC_ACT_PIPE,
+		},
+	}
+}
+
 type MirredAct uint8
 
 func (a MirredAct) String() string {

filter_linux.go

@@ -607,6 +607,16 @@ func EncodeActions(attr *nl.RtAttr, actions []Action) error {
 			}
 			toTcGen(action.Attrs(), &connmark.TcGen)
 			aopts.AddRtAttr(nl.TCA_CONNMARK_PARMS, connmark.Serialize())
+		case *CsumAction:
+			table := attr.AddRtAttr(tabIndex, nil)
+			tabIndex++
+			table.AddRtAttr(nl.TCA_ACT_KIND, nl.ZeroTerminated("csum"))
+			aopts := table.AddRtAttr(nl.TCA_ACT_OPTIONS, nil)
+			csum := nl.TcCsum{
+				UpdateFlags: uint32(action.UpdateFlags),
+			}
+			toTcGen(action.Attrs(), &csum.TcGen)
+			aopts.AddRtAttr(nl.TCA_CSUM_PARMS, csum.Serialize())
 		case *BpfAction:
 			table := attr.AddRtAttr(tabIndex, nil)
 			tabIndex++
@@ -675,6 +685,8 @@ func parseActions(tables []syscall.NetlinkRouteAttr) ([]Action, error) {
 					action = &BpfAction{}
 				case "connmark":
 					action = &ConnmarkAction{}
+				case "csum":
+					action = &CsumAction{}
 				case "gact":
 					action = &GenericAction{}
 				case "tunnel_key":
@@ -755,6 +767,14 @@ func parseActions(tables []syscall.NetlinkRouteAttr) ([]Action, error) {
 							toAttrs(&connmark.TcGen, action.Attrs())
 							action.(*ConnmarkAction).Zone = connmark.Zone
 						}
+					case "csum":
+						switch adatum.Attr.Type {
+						case nl.TCA_CSUM_PARMS:
+							csum := *nl.DeserializeTcCsum(adatum.Value)
+							action.(*CsumAction).ActionAttrs = ActionAttrs{}
+							toAttrs(&csum.TcGen, action.Attrs())
+							action.(*CsumAction).UpdateFlags = CsumUpdateFlags(csum.UpdateFlags)
+						}
 					case "gact":
 						switch adatum.Attr.Type {
 						case nl.TCA_GACT_PARMS:

filter_test.go

@@ -785,6 +785,135 @@ func TestFilterU32ConnmarkAddDel(t *testing.T) {
 	}
 }
 
+func TestFilterU32CsumAddDel(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+	if err := LinkAdd(&Ifb{LinkAttrs{Name: "foo"}}); err != nil {
+		t.Fatalf("add link foo error: %v", err)
+	}
+	link, err := LinkByName("foo")
+	if err != nil {
+		t.Fatalf("add link foo error: %v", err)
+	}
+	if err := LinkSetUp(link); err != nil {
+		t.Fatalf("set foo link up error: %v", err)
+	}
+
+	qdisc := &Ingress{
+		QdiscAttrs: QdiscAttrs{
+			LinkIndex: link.Attrs().Index,
+			Handle:    MakeHandle(0xffff, 0),
+			Parent:    HANDLE_INGRESS,
+		},
+	}
+	if err := QdiscAdd(qdisc); err != nil {
+		t.Fatal(err)
+	}
+	qdiscs, err := SafeQdiscList(link)
+	if err != nil {
+		t.Fatalf("get qdisc error: %v", err)
+	}
+
+	found := false
+	for _, v := range qdiscs {
+		if _, ok := v.(*Ingress); ok {
+			found = true
+			break
+		}
+	}
+	if !found {
+		t.Fatal("Qdisc is the wrong type")
+	}
+
+	classId := MakeHandle(1, 1)
+	filter := &U32{
+		FilterAttrs: FilterAttrs{
+			LinkIndex: link.Attrs().Index,
+			Parent:    MakeHandle(0xffff, 0),
+			Priority:  1,
+			Protocol:  unix.ETH_P_ALL,
+		},
+		ClassId: classId,
+		Actions: []Action{
+			&CsumAction{
+				ActionAttrs: ActionAttrs{
+					Action: TC_ACT_PIPE,
+				},
+				UpdateFlags: TCA_CSUM_UPDATE_FLAG_TCP,
+			},
+		},
+	}
+
+	if err := FilterAdd(filter); err != nil {
+		t.Fatal(err)
+	}
+
+	filters, err := FilterList(link, MakeHandle(0xffff, 0))
+	if err != nil {
+		t.Fatalf("get filter error: %v", err)
+	}
+
+	if len(filters) != 1 {
+		t.Fatalf("the count filters error, expect: 1, acutal: %d", len(filters))
+	}
+
+	ft, ok := filters[0].(*U32)
+	if !ok {
+		t.Fatal("Filter is the wrong type")
+	}
+
+	if ft.LinkIndex != link.Attrs().Index {
+		t.Fatal("link index error")
+	}
+
+	if len(ft.Actions) != 1 {
+		t.Fatalf("filter has wrong number of actions, expect: 1, acutal: %d", len(filters))
+	}
+
+	csum, ok := ft.Actions[0].(*CsumAction)
+	if !ok {
+		t.Fatal("action is the wrong type")
+	}
+
+	if csum.Attrs().Action != TC_ACT_PIPE {
+		t.Fatal("Csum action isn't TC_ACT_PIPE")
+	}
+
+	if csum.UpdateFlags != TCA_CSUM_UPDATE_FLAG_TCP {
+		t.Fatalf("Csum action isn't TCA_CSUM_UPDATE_FLAG_TCP, got %d", csum.UpdateFlags)
+	}
+
+	if err := FilterDel(ft); err != nil {
+		t.Fatal(err)
+	}
+	filters, err = FilterList(link, MakeHandle(0xffff, 0))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(filters) != 0 {
+		t.Fatal("Failed to remove filter")
+	}
+
+	if err := QdiscDel(qdisc); err != nil {
+		t.Fatal(err)
+	}
+	qdiscs, err = SafeQdiscList(link)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	found = false
+	for _, v := range qdiscs {
+		if _, ok := v.(*Ingress); ok {
+			found = true
+			break
+		}
+	}
+	if found {
+		t.Fatal("Failed to remove qdisc")
+	}
+}
+
 func setupLinkForTestWithQdisc(t *testing.T, linkName string) (Qdisc, Link) {
 	if err := LinkAdd(&Ifb{LinkAttrs{Name: linkName}}); err != nil {
 		t.Fatal(err)

nl/tc_linux.go

@@ -90,6 +90,7 @@ const (
 	SizeofTcU32Sel       = 0x10 // without keys
 	SizeofTcGen          = 0x14
 	SizeofTcConnmark     = SizeofTcGen + 0x04
+	SizeofTcCsum         = SizeofTcGen + 0x04
 	SizeofTcMirred       = SizeofTcGen + 0x08
 	SizeofTcTunnelKey    = SizeofTcGen + 0x04
 	SizeofTcSkbEdit      = SizeofTcGen
@@ -694,6 +695,36 @@ func (x *TcConnmark) Serialize() []byte {
 	return (*(*[SizeofTcConnmark]byte)(unsafe.Pointer(x)))[:]
 }
 
+const (
+	TCA_CSUM_UNSPEC = iota
+	TCA_CSUM_PARMS
+	TCA_CSUM_TM
+	TCA_CSUM_PAD
+	TCA_CSUM_MAX = TCA_CSUM_PAD
+)
+
+// struct tc_csum {
+//   tc_gen;
+//   __u32 update_flags;
+// }
+
+type TcCsum struct {
+	TcGen
+	UpdateFlags uint32
+}
+
+func (msg *TcCsum) Len() int {
+	return SizeofTcCsum
+}
+
+func DeserializeTcCsum(b []byte) *TcCsum {
+	return (*TcCsum)(unsafe.Pointer(&b[0:SizeofTcCsum][0]))
+}
+
+func (x *TcCsum) Serialize() []byte {
+	return (*(*[SizeofTcCsum]byte)(unsafe.Pointer(x)))[:]
+}
+
 const (
 	TCA_ACT_MIRRED = 8
 )