ip neighbour: Add support for lladdr to be an IP address

The ip neighbour supports adding of peers statically using commands
where the lladdr is an IP address.

ip neighbor add 10.0.0.2 lladdr 203.0.113.6 dev tun8

This is used in the case of point-to-multipoint GRE to setup the
remote end point of the tunnel

Note that link-layer address and neighbor address are both IP addresses

Signed-off-by: Manohar Castelino <manohar.r.castelino@intel.com>

neigh.go

@@ -14,6 +14,7 @@ type Neigh struct {
 	Flags        int
 	IP           net.IP
 	HardwareAddr net.HardwareAddr
+	LLIPAddr     net.IP //Used in the case of NHRP
 }
 
 // String returns $ip/$hwaddr $label

neigh_linux.go

@@ -128,6 +128,7 @@ func (h *Handle) NeighDel(neigh *Neigh) error {
 
 func neighHandle(neigh *Neigh, req *nl.NetlinkRequest) error {
 	var family int
+
 	if neigh.Family > 0 {
 		family = neigh.Family
 	} else {
@@ -151,7 +152,10 @@ func neighHandle(neigh *Neigh, req *nl.NetlinkRequest) error {
 	dstData := nl.NewRtAttr(NDA_DST, ipData)
 	req.AddData(dstData)
 
-	if neigh.Flags != NTF_PROXY || neigh.HardwareAddr != nil {
+	if neigh.LLIPAddr != nil {
+		llIPData := nl.NewRtAttr(NDA_LLADDR, neigh.LLIPAddr.To4())
+		req.AddData(llIPData)
+	} else if neigh.Flags != NTF_PROXY || neigh.HardwareAddr != nil {
 		hwData := nl.NewRtAttr(NDA_LLADDR, []byte(neigh.HardwareAddr))
 		req.AddData(hwData)
 	}
@@ -237,12 +241,33 @@ func NeighDeserialize(m []byte) (*Neigh, error) {
 		return nil, err
 	}
 
+	// This should be cached for perfomance
+	// once per table dump
+	link, err := LinkByIndex(neigh.LinkIndex)
+	if err != nil {
+		return nil, err
+	}
+	encapType := link.Attrs().EncapType
+
 	for _, attr := range attrs {
 		switch attr.Attr.Type {
 		case NDA_DST:
 			neigh.IP = net.IP(attr.Value)
 		case NDA_LLADDR:
-			neigh.HardwareAddr = net.HardwareAddr(attr.Value)
+			// BUG: Is this a bug in the netlink library?
+			// #define RTA_LENGTH(len) (RTA_ALIGN(sizeof(struct rtattr)) + (len))
+			// #define RTA_PAYLOAD(rta) ((int)((rta)->rta_len) - RTA_LENGTH(0))
+			attrLen := attr.Attr.Len - syscall.SizeofRtAttr
+			if attrLen == 4 && (encapType == "ipip" ||
+				encapType == "sit" ||
+				encapType == "gre") {
+				neigh.LLIPAddr = net.IP(attr.Value)
+			} else if attrLen == 16 &&
+				encapType == "tunnel6" {
+				neigh.IP = net.IP(attr.Value)
+			} else {
+				neigh.HardwareAddr = net.HardwareAddr(attr.Value)
+			}
 		}
 	}
 

neigh_test.go

@@ -34,6 +34,15 @@ func dumpContains(dump []Neigh, e arpEntry) bool {
 	return false
 }
 
+func dumpContainsNeigh(dump []Neigh, ne Neigh) bool {
+	for _, n := range dump {
+		if n.IP.Equal(ne.IP) && n.LLIPAddr.Equal(ne.LLIPAddr) {
+			return true
+		}
+	}
+	return false
+}
+
 func dumpContainsProxy(dump []Neigh, p proxyEntry) bool {
 	for _, n := range dump {
 		if n.IP.Equal(p.ip) && (n.LinkIndex == p.dev) && (n.Flags&NTF_PROXY) == NTF_PROXY {
@@ -43,6 +52,54 @@ func dumpContainsProxy(dump []Neigh, p proxyEntry) bool {
 	return false
 }
 
+func TestNeighAddDelLLIPAddr(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	dummy := Iptun{
+		LinkAttrs: LinkAttrs{Name: "neigh0"},
+		PMtuDisc:  1,
+		Local:     net.IPv4(127, 0, 0, 1),
+		Remote:    net.IPv4(127, 0, 0, 1)}
+	if err := LinkAdd(&dummy); err != nil {
+		t.Errorf("Failed to create link: %v", err)
+	}
+	ensureIndex(dummy.Attrs())
+
+	entry := Neigh{
+		LinkIndex: dummy.Index,
+		State:     NUD_PERMANENT,
+		IP:        net.IPv4(198, 51, 100, 2),
+		LLIPAddr:  net.IPv4(198, 51, 100, 1),
+	}
+
+	err := NeighAdd(&entry)
+	if err != nil {
+		t.Errorf("Failed to NeighAdd: %v", err)
+	}
+
+	// Dump and see that all added entries are there
+	dump, err := NeighList(dummy.Index, 0)
+	if err != nil {
+		t.Errorf("Failed to NeighList: %v", err)
+	}
+
+	if !dumpContainsNeigh(dump, entry) {
+		t.Errorf("Dump does not contain: %v: %v", entry, dump)
+
+	}
+
+	// Delete the entry
+	err = NeighDel(&entry)
+	if err != nil {
+		t.Errorf("Failed to NeighDel: %v", err)
+	}
+
+	if err := LinkDel(&dummy); err != nil {
+		t.Fatal(err)
+	}
+}
+
 func TestNeighAddDel(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()