plugin/k8s_external: Add support for PTR requests (#5435)

* Exclude External IP addresses from being added to the existing kubernetes' plugin IP->Service index
* Add support for PTR requests on External IPs of Services to the k8s_external plugin

Signed-off-by: Chris O'Haver <cohaver@infoblox.com>

1 files changed, 41 insertions, 6 deletions

diff --git a/plugin/k8s_external/external_test.go b/plugin/k8s_external/external_test.go
index 558c894f6..22ef08cc1 100644
--- a/plugin/k8s_external/external_test.go
+++ b/plugin/k8s_external/external_test.go
@@ -20,7 +20,7 @@ func TestExternal(t *testing.T) {
 	k.APIConn = &external{}
 
 	e := New()
-	e.Zones = []string{"example.com."}
+	e.Zones = []string{"example.com.", "in-addr.arpa."}
 	e.Next = test.NextHandler(dns.RcodeSuccess, nil)
 	e.externalFunc = k.External
 	e.externalAddrFunc = externalAddress  // internal test function
@@ -49,12 +49,33 @@ func TestExternal(t *testing.T) {
 			t.Error("Expected authoritative answer")
 		}
 		if err = test.SortAndCheck(resp, tc); err != nil {
-			t.Error(err)
+			t.Errorf("Test %d: %v", i, err)
 		}
 	}
 }
 
 var tests = []test.Case{
+	// PTR reverse lookup
+	{
+		Qname: "4.3.2.1.in-addr.arpa.", Qtype: dns.TypePTR, Rcode: dns.RcodeSuccess,
+		Answer: []dns.RR{
+			test.PTR("4.3.2.1.in-addr.arpa. 5 IN PTR svc1.testns.example.com."),
+		},
+	},
+	// Bad PTR reverse lookup using existing service name
+	{
+		Qname: "svc1.testns.example.com.", Qtype: dns.TypePTR, Rcode: dns.RcodeSuccess,
+		Ns: []dns.RR{
+			test.SOA("example.com.	5	IN	SOA	ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+		},
+	},
+	// Bad PTR reverse lookup using non-existing service name
+	{
+		Qname: "not-existing.testns.example.com.", Qtype: dns.TypePTR, Rcode: dns.RcodeNameError,
+		Ns: []dns.RR{
+			test.SOA("example.com.	5	IN	SOA	ns1.dns.example.com. hostmaster.example.com. 1499347823 7200 1800 86400 5"),
+		},
+	},
 	// A Service
 	{
 		Qname: "svc1.testns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeSuccess,
@@ -155,7 +176,7 @@ var tests = []test.Case{
 	{
 		Qname: "svc11.testns.example.com.", Qtype: dns.TypeA, Rcode: dns.RcodeSuccess,
 		Answer: []dns.RR{
-			test.A("svc11.testns.example.com.	5	IN	A	1.2.3.4"),
+			test.A("svc11.testns.example.com.	5	IN	A	2.3.4.5"),
 		},
 	},
 	{
@@ -164,7 +185,7 @@ var tests = []test.Case{
 			test.SRV("_http._tcp.svc11.testns.example.com.	5	IN	SRV	0 100 80 svc11.testns.example.com."),
 		},
 		Extra: []dns.RR{
-			test.A("svc11.testns.example.com.	5	IN	A	1.2.3.4"),
+			test.A("svc11.testns.example.com.	5	IN	A	2.3.4.5"),
 		},
 	},
 	{
@@ -173,7 +194,7 @@ var tests = []test.Case{
 			test.SRV("svc11.testns.example.com.	5	IN	SRV	0 100 80 svc11.testns.example.com."),
 		},
 		Extra: []dns.RR{
-			test.A("svc11.testns.example.com.	5	IN	A	1.2.3.4"),
+			test.A("svc11.testns.example.com.	5	IN	A	2.3.4.5"),
 		},
 	},
 	// svc12
@@ -211,6 +232,20 @@ func (external) GetNodeByName(ctx context.Context, name string) (*api.Node, erro
 func (external) SvcIndex(s string) []*object.Service                               { return svcIndexExternal[s] }
 func (external) PodIndex(string) []*object.Pod                                     { return nil }
 
+func (external) SvcExtIndexReverse(ip string) (result []*object.Service) {
+	for _, svcs := range svcIndexExternal {
+		for _, svc := range svcs {
+			for _, exIp := range svc.ExternalIPs {
+				if exIp != ip {
+					continue
+				}
+				result = append(result, svc)
+			}
+		}
+	}
+	return result
+}
+
 func (external) GetNamespaceByName(name string) (*object.Namespace, error) {
 	return &object.Namespace{
 		Name: name,
@@ -243,7 +278,7 @@ var svcIndexExternal = map[string][]*object.Service{
 			Name:        "svc11",
 			Namespace:   "testns",
 			Type:        api.ServiceTypeLoadBalancer,
-			ExternalIPs: []string{"1.2.3.4"},
+			ExternalIPs: []string{"2.3.4.5"},
 			Ports:       []api.ServicePort{{Name: "http", Protocol: "tcp", Port: 80}},
 		},
 	},