openvswitch: add OpenvSwitch and OpenvSwitchSlave link models

Signed-off-by: Ivan Tsvetkov <ivanfromearth@gmail.com>

link.go

@@ -289,6 +289,21 @@ func (bridge *Bridge) Type() string {
 	return "bridge"
 }
 
+// OpenvSwitch links are Open vSwitch bridge devices.
+// Note: their lifecycle is typically managed by OVS (OVSDB/ovs-vsctl),
+// while netlink is used to query/link them.
+type OpenvSwitch struct {
+	LinkAttrs
+}
+
+func (ovs *OpenvSwitch) Attrs() *LinkAttrs {
+	return &ovs.LinkAttrs
+}
+
+func (ovs *OpenvSwitch) Type() string {
+	return "openvswitch"
+}
+
 // Vlan links have ParentIndex set in their Attrs()
 type Vlan struct {
 	LinkAttrs
@@ -1066,6 +1081,12 @@ func (v *VrfSlave) SlaveType() string {
 	return "vrf"
 }
 
+type OpenvSwitchSlave struct{}
+
+func (o *OpenvSwitchSlave) SlaveType() string {
+	return "openvswitch"
+}
+
 // Geneve devices must specify RemoteIP and ID (VNI) on create
 // https://github.com/torvalds/linux/blob/47ec5303d73ea344e84f46660fff693c57641386/drivers/net/geneve.c#L1209-L1223
 type Geneve struct {

link_linux.go

@@ -2188,6 +2188,8 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 						link = &Ifb{}
 					case "bridge":
 						link = &Bridge{}
+					case "openvswitch":
+						link = &OpenvSwitch{}
 					case "vlan":
 						link = &Vlan{}
 					case "netkit":
@@ -2308,6 +2310,8 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 						linkSlave = &BondSlave{}
 					case "vrf":
 						linkSlave = &VrfSlave{}
+					case "openvswitch":
+						linkSlave = &OpenvSwitchSlave{}
 					}
 
 				case nl.IFLA_INFO_SLAVE_DATA:

link_test.go

@@ -2240,6 +2240,49 @@ func TestLinkByIndex(t *testing.T) {
 	}
 }
 
+func TestOpenvSwitch(t *testing.T) {
+	skipUnlessRoot(t)
+	skipUnlessKModuleLoaded(t, "openvswitch")
+
+	// This test validates host OVS state, so it must not create an isolated netns
+	// via setUpNetlinkTest(), otherwise host OVS links will be invisible.
+	link, err := LinkByName("ovs-system")
+	if err != nil {
+		if _, ok := err.(LinkNotFoundError); ok {
+			t.Skip("ovs-system interface not found")
+		}
+		t.Fatal("Failed getting link: ", err)
+	}
+
+	ovsSystem, ok := link.(*OpenvSwitch)
+	if !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	}
+
+	links, err := LinkList()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, l := range links {
+		if l.Attrs().Name == ovsSystem.Name {
+			if _, ok := l.(*OpenvSwitch); !ok {
+				t.Fatalf("unexpected link type: %T", l)
+			}
+		}
+
+		if l.Attrs().Slave != nil && l.Attrs().Slave.SlaveType() == "openvswitch" {
+			if _, ok := l.Attrs().Slave.(*OpenvSwitchSlave); !ok {
+				t.Fatalf("unexpected slave type: %T", l.Attrs().Slave)
+			}
+
+			if l.Attrs().MasterIndex != ovsSystem.Index {
+				t.Fatalf("Got unexpected master index: %d, expected: %d", l.Attrs().MasterIndex, ovsSystem.Index)
+			}
+		}
+	}
+}
+
 func TestLinkSet(t *testing.T) {
 	t.Cleanup(setUpNetlinkTest(t))