Add proxy support to the neighbor functions (#149)

- Don't require a MAC address for a neighbor proxy
- Include proxies in the list of neighbors

Signed-off-by: Zvi "CtrlZvi" Effron <viz+GitHub@flippedperspective.com>

neigh_linux.go

@@ -151,8 +151,10 @@ func neighHandle(neigh *Neigh, req *nl.NetlinkRequest) error {
 	dstData := nl.NewRtAttr(NDA_DST, ipData)
 	req.AddData(dstData)
 
-	hwData := nl.NewRtAttr(NDA_LLADDR, []byte(neigh.HardwareAddr))
-	req.AddData(hwData)
+	if neigh.Flags != NTF_PROXY || neigh.HardwareAddr != nil {
+		hwData := nl.NewRtAttr(NDA_LLADDR, []byte(neigh.HardwareAddr))
+		req.AddData(hwData)
+	}
 
 	_, err := req.Execute(syscall.NETLINK_ROUTE, 0)
 	return err
@@ -165,14 +167,33 @@ func NeighList(linkIndex, family int) ([]Neigh, error) {
 	return pkgHandle.NeighList(linkIndex, family)
 }
 
+// NeighProxyList gets a list of neighbor proxies in the system.
+// Equivalent to: `ip neighbor show proxy`.
+// The list can be filtered by link and ip family.
+func NeighProxyList(linkIndex, family int) ([]Neigh, error) {
+	return pkgHandle.NeighProxyList(linkIndex, family)
+}
+
 // NeighList gets a list of IP-MAC mappings in the system (ARP table).
 // Equivalent to: `ip neighbor show`.
 // The list can be filtered by link and ip family.
 func (h *Handle) NeighList(linkIndex, family int) ([]Neigh, error) {
+	return h.neighList(linkIndex, family, 0)
+}
+
+// NeighProxyList gets a list of neighbor proxies in the system.
+// Equivalent to: `ip neighbor show proxy`.
+// The list can be filtered by link, ip family.
+func (h *Handle) NeighProxyList(linkIndex, family int) ([]Neigh, error) {
+	return h.neighList(linkIndex, family, NTF_PROXY)
+}
+
+func (h *Handle) neighList(linkIndex, family, flags int) ([]Neigh, error) {
 	req := h.newNetlinkRequest(syscall.RTM_GETNEIGH, syscall.NLM_F_DUMP)
 	msg := Ndmsg{
 		Family: uint8(family),
 		Index:  uint32(linkIndex),
+		Flags:  uint8(flags),
 	}
 	req.AddData(&msg)
 

neigh_test.go

@@ -10,6 +10,11 @@ type arpEntry struct {
 	mac net.HardwareAddr
 }
 
+type proxyEntry struct {
+	ip  net.IP
+	dev int
+}
+
 func parseMAC(s string) net.HardwareAddr {
 	m, err := net.ParseMAC(s)
 	if err != nil {
@@ -27,6 +32,15 @@ func dumpContains(dump []Neigh, e arpEntry) bool {
 	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 {
+			return true
+		}
+	}
+	return false
+}
+
 func TestNeighAddDel(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()
@@ -102,3 +116,77 @@ func TestNeighAddDel(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestNeighAddDelProxy(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	dummy := Dummy{LinkAttrs{Name: "neigh0"}}
+	if err := LinkAdd(&dummy); err != nil {
+		t.Fatal(err)
+	}
+
+	ensureIndex(dummy.Attrs())
+
+	proxyTable := []proxyEntry{
+		{net.ParseIP("10.99.0.1"), dummy.Index},
+		{net.ParseIP("10.99.0.2"), dummy.Index},
+		{net.ParseIP("10.99.0.3"), dummy.Index},
+		{net.ParseIP("10.99.0.4"), dummy.Index},
+		{net.ParseIP("10.99.0.5"), dummy.Index},
+	}
+
+	// Add the proxyTable
+	for _, entry := range proxyTable {
+		err := NeighAdd(&Neigh{
+			LinkIndex: dummy.Index,
+			Flags:     NTF_PROXY,
+			IP:        entry.ip,
+		})
+
+		if err != nil {
+			t.Errorf("Failed to NeighAdd: %v", err)
+		}
+	}
+
+	// Dump and see that all added entries are there
+	dump, err := NeighProxyList(dummy.Index, 0)
+	if err != nil {
+		t.Errorf("Failed to NeighList: %v", err)
+	}
+
+	for _, entry := range proxyTable {
+		if !dumpContainsProxy(dump, entry) {
+			t.Errorf("Dump does not contain: %v", entry)
+		}
+	}
+
+	// Delete the proxyTable
+	for _, entry := range proxyTable {
+		err := NeighDel(&Neigh{
+			LinkIndex: dummy.Index,
+			Flags:     NTF_PROXY,
+			IP:        entry.ip,
+		})
+
+		if err != nil {
+			t.Errorf("Failed to NeighDel: %v", err)
+		}
+	}
+
+	// Dump and see that none of deleted entries are there
+	dump, err = NeighProxyList(dummy.Index, 0)
+	if err != nil {
+		t.Errorf("Failed to NeighList: %v", err)
+	}
+
+	for _, entry := range proxyTable {
+		if dumpContainsProxy(dump, entry) {
+			t.Errorf("Dump contains: %v", entry)
+		}
+	}
+
+	if err := LinkDel(&dummy); err != nil {
+		t.Fatal(err)
+	}
+}