Add Geneve link support

Heavily based on the existing Gretap support

link.go

@@ -851,6 +851,30 @@ func (b *BondSlave) SlaveType() string {
 	return "bond"
 }
 
+// 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 {
+	LinkAttrs
+	ID             uint32 // vni
+	Remote         net.IP
+	Ttl            uint8
+	Tos            uint8
+	Dport          uint16
+	UdpCsum        uint8
+	UdpZeroCsum6Tx uint8
+	UdpZeroCsum6Rx uint8
+	Link           uint32
+	FlowBased      bool
+}
+
+func (geneve *Geneve) Attrs() *LinkAttrs {
+	return &geneve.LinkAttrs
+}
+
+func (geneve *Geneve) Type() string {
+	return "geneve"
+}
+
 // Gretap devices must specify LocalIP and RemoteIP on create
 type Gretap struct {
 	LinkAttrs

link_linux.go

@@ -1404,6 +1404,8 @@ func (h *Handle) linkModify(link Link, flags int) error {
 			data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil)
 			data.AddRtAttr(nl.IFLA_MACVLAN_MODE, nl.Uint32Attr(macvlanModes[link.Mode]))
 		}
+	case *Geneve:
+		addGeneveAttrs(link, linkInfo)
 	case *Gretap:
 		addGretapAttrs(link, linkInfo)
 	case *Iptun:
@@ -1667,6 +1669,8 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 						link = &Macvlan{}
 					case "macvtap":
 						link = &Macvtap{}
+					case "geneve":
+						link = &Geneve{}
 					case "gretap":
 						link = &Gretap{}
 					case "ip6gretap":
@@ -1716,6 +1720,8 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 						parseMacvlanData(link, data)
 					case "macvtap":
 						parseMacvtapData(link, data)
+					case "geneve":
+						parseGeneveData(link, data)
 					case "gretap":
 						parseGretapData(link, data)
 					case "ip6gretap":
@@ -2452,6 +2458,56 @@ func linkFlags(rawFlags uint32) net.Flags {
 	return f
 }
 
+func addGeneveAttrs(geneve *Geneve, linkInfo *nl.RtAttr) {
+	data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil)
+
+	if geneve.FlowBased {
+		// In flow based mode, no other attributes need to be configured
+		linkInfo.AddRtAttr(nl.IFLA_GENEVE_COLLECT_METADATA, boolAttr(geneve.FlowBased))
+		return
+	}
+
+	if ip := geneve.Remote; ip != nil {
+		if ip4 := ip.To4(); ip4 != nil {
+			data.AddRtAttr(nl.IFLA_GENEVE_REMOTE, []byte(ip))
+		} else {
+			data.AddRtAttr(nl.IFLA_GENEVE_REMOTE6, []byte(ip))
+		}
+	}
+
+	if geneve.ID != 0 {
+		data.AddRtAttr(nl.IFLA_GENEVE_ID, htonl(geneve.ID))
+	}
+
+	if geneve.Dport != 0 {
+		data.AddRtAttr(nl.IFLA_GENEVE_PORT, htons(geneve.Dport))
+	}
+
+	if geneve.Ttl != 0 {
+		data.AddRtAttr(nl.IFLA_GENEVE_TTL, nl.Uint8Attr(geneve.Ttl))
+	}
+
+	if geneve.Tos != 0 {
+		data.AddRtAttr(nl.IFLA_GENEVE_TOS, nl.Uint8Attr(geneve.Tos))
+	}
+}
+
+func parseGeneveData(link Link, data []syscall.NetlinkRouteAttr) {
+	geneve := link.(*Geneve)
+	for _, datum := range data {
+		switch datum.Attr.Type {
+		case nl.IFLA_GENEVE_ID:
+			geneve.ID = ntohl(datum.Value[0:4])
+		case nl.IFLA_GENEVE_PORT:
+			geneve.Dport = ntohs(datum.Value[0:2])
+		case nl.IFLA_GENEVE_TTL:
+			geneve.Ttl = uint8(datum.Value[0])
+		case nl.IFLA_GENEVE_TOS:
+			geneve.Tos = uint8(datum.Value[0])
+		}
+	}
+}
+
 func addGretapAttrs(gretap *Gretap, linkInfo *nl.RtAttr) {
 	data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil)
 

link_test.go

@@ -245,6 +245,14 @@ func testLinkAddDel(t *testing.T, link Link) {
 		}
 	}
 
+	if geneve, ok := link.(*Geneve); ok {
+		other, ok := result.(*Geneve)
+		if !ok {
+			t.Fatal("Result of create is not a Geneve")
+		}
+		compareGeneve(t, geneve, other)
+	}
+
 	if gretap, ok := link.(*Gretap); ok {
 		other, ok := result.(*Gretap)
 		if !ok {
@@ -293,6 +301,31 @@ func testLinkAddDel(t *testing.T, link Link) {
 	}
 }
 
+func compareGeneve(t *testing.T, expected, actual *Geneve) {
+	if actual.ID != expected.ID {
+		t.Fatalf("Geneve.ID doesn't match: %d %d", actual.ID, expected.ID)
+	}
+
+	// set the Dport to 6081 (the linux default) if it wasn't specified at creation
+	if expected.Dport == 0 {
+		expected.Dport = 6081
+	}
+
+	if actual.Dport != expected.Dport {
+		t.Fatal("Geneve.Dport doesn't match")
+	}
+
+	if actual.Ttl != expected.Ttl {
+		t.Fatal("Geneve.Ttl doesn't match")
+	}
+
+	if actual.Tos != expected.Tos {
+		t.Fatal("Geneve.Tos doesn't match")
+	}
+
+	// TODO: we should implement the rest of the geneve methods
+}
+
 func compareGretap(t *testing.T, expected, actual *Gretap) {
 	if actual.IKey != expected.IKey {
 		t.Fatal("Gretap.IKey doesn't match")
@@ -575,6 +608,21 @@ func TestLinkAddDelBridge(t *testing.T) {
 	testLinkAddDel(t, &Bridge{LinkAttrs: LinkAttrs{Name: "foo", MTU: 1400}})
 }
 
+func TestLinkAddDelGeneve(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	testLinkAddDel(t, &Geneve{
+		LinkAttrs: LinkAttrs{Name: "foo4", EncapType: "geneve"},
+		ID:        0x1000,
+		Remote:    net.IPv4(127, 0, 0, 1)})
+
+	testLinkAddDel(t, &Geneve{
+		LinkAttrs: LinkAttrs{Name: "foo6", EncapType: "geneve"},
+		ID:        0x1000,
+		Remote:    net.ParseIP("2001:db8:ef33::2")})
+}
+
 func TestLinkAddDelGretap(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()

nl/link_linux.go

@@ -173,6 +173,22 @@ const (
 	IFLA_BOND_SLAVE_AD_PARTNER_OPER_PORT_STATE
 )
 
+const (
+	IFLA_GENEVE_UNSPEC = iota
+	IFLA_GENEVE_ID     // vni
+	IFLA_GENEVE_REMOTE
+	IFLA_GENEVE_TTL
+	IFLA_GENEVE_TOS
+	IFLA_GENEVE_PORT // destination port
+	IFLA_GENEVE_COLLECT_METADATA
+	IFLA_GENEVE_REMOTE6
+	IFLA_GENEVE_UDP_CSUM
+	IFLA_GENEVE_UDP_ZERO_CSUM6_TX
+	IFLA_GENEVE_UDP_ZERO_CSUM6_RX
+	IFLA_GENEVE_LABEL
+	IFLA_GENEVE_MAX = IFLA_GENEVE_LABEL
+)
+
 const (
 	IFLA_GRE_UNSPEC = iota
 	IFLA_GRE_LINK