geneve: Support setting/getting source port range

Add support for geneve feature to specify source port range, see
kernel commits:

- e1f95b1992b8 ("geneve: Allow users to specify source port range")
- 5a41a00cd5d5 ("geneve, specs: Add port range to rt_link specification")

This is exactly equivalent on what is done in case of vxlan today.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

link.go

@@ -1059,6 +1059,8 @@ type Geneve struct {
 	FlowBased         bool
 	InnerProtoInherit bool
 	Df                GeneveDf
+	PortLow           int
+	PortHigh          int
 }
 
 func (geneve *Geneve) Attrs() *LinkAttrs {

link_linux.go

@@ -3100,6 +3100,10 @@ func linkFlags(rawFlags uint32) net.Flags {
 	return f
 }
 
+type genevePortRange struct {
+	Lo, Hi uint16
+}
+
 func addGeneveAttrs(geneve *Geneve, linkInfo *nl.RtAttr) {
 	data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil)
 
@@ -3136,6 +3140,15 @@ func addGeneveAttrs(geneve *Geneve, linkInfo *nl.RtAttr) {
 		data.AddRtAttr(nl.IFLA_GENEVE_TOS, nl.Uint8Attr(geneve.Tos))
 	}
 
+	if geneve.PortLow > 0 || geneve.PortHigh > 0 {
+		pr := genevePortRange{uint16(geneve.PortLow), uint16(geneve.PortHigh)}
+
+		buf := new(bytes.Buffer)
+		binary.Write(buf, binary.BigEndian, &pr)
+
+		data.AddRtAttr(nl.IFLA_GENEVE_PORT_RANGE, buf.Bytes())
+	}
+
 	data.AddRtAttr(nl.IFLA_GENEVE_DF, nl.Uint8Attr(uint8(geneve.Df)))
 }
 
@@ -3157,6 +3170,13 @@ func parseGeneveData(link Link, data []syscall.NetlinkRouteAttr) {
 			geneve.FlowBased = true
 		case nl.IFLA_GENEVE_INNER_PROTO_INHERIT:
 			geneve.InnerProtoInherit = true
+		case nl.IFLA_GENEVE_PORT_RANGE:
+			buf := bytes.NewBuffer(datum.Value[0:4])
+			var pr genevePortRange
+			if binary.Read(buf, binary.BigEndian, &pr) == nil {
+				geneve.PortLow = int(pr.Lo)
+				geneve.PortHigh = int(pr.Hi)
+			}
 		}
 	}
 }

link_test.go

@@ -438,6 +438,15 @@ func compareGeneve(t *testing.T, expected, actual *Geneve) {
 		t.Fatal("Geneve.InnerProtoInherit doesn't match")
 	}
 
+	if expected.PortLow > 0 || expected.PortHigh > 0 {
+		if actual.PortLow != expected.PortLow {
+			t.Fatal("Geneve.PortLow doesn't match")
+		}
+		if actual.PortHigh != expected.PortHigh {
+			t.Fatal("Geneve.PortHigh doesn't match")
+		}
+	}
+
 	// TODO: we should implement the rest of the geneve methods
 }
 

nl/link_linux.go

@@ -234,6 +234,7 @@ const (
 	IFLA_GENEVE_TTL_INHERIT
 	IFLA_GENEVE_DF
 	IFLA_GENEVE_INNER_PROTO_INHERIT
+	IFLA_GENEVE_PORT_RANGE
 	IFLA_GENEVE_MAX = IFLA_GENEVE_INNER_PROTO_INHERIT
 )