agent: Add test for CNAME recursion

command/agent/dns_test.go

@@ -2,7 +2,9 @@ package agent
 
 import (
 	"fmt"
+	"net"
 	"os"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -1569,3 +1571,133 @@ func TestDNS_ServiceLookup_SRV_RFC_TCP_Default(t *testing.T) {
 		t.Fatalf("Bad: %#v", in.Extra[0])
 	}
 }
+
+func TestDNS_CNAME_recurse(t *testing.T) {
+	// Create our recursor - Consul will recurse to this
+	dnsConf := nextConfig()
+	dnsAddr := fmt.Sprintf("%s:%d", dnsConf.Addresses.DNS, dnsConf.Ports.DNS)
+	mux := dns.NewServeMux()
+	mux.HandleFunc(".", func(resp dns.ResponseWriter, msg *dns.Msg) {
+
+		cnResp := func(src, target string) *dns.CNAME {
+			return &dns.CNAME{
+				Hdr: dns.RR_Header{
+					Name:   src,
+					Rrtype: dns.TypeCNAME,
+					Class:  dns.ClassINET,
+				},
+				Target: target,
+			}
+		}
+
+		// Create the answer
+		ans := &dns.Msg{}
+		ans.SetReply(msg)
+		ans.Answer = append(ans.Answer,
+			cnResp("a.example.com.", "b.example.com."),
+			cnResp("b.example.com.", "c.example.com."),
+			cnResp("c.example.com.", "d.example.com."),
+			&dns.A{
+				Hdr: dns.RR_Header{
+					Name:   "d.example.com.",
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+				},
+				A: net.ParseIP("1.2.3.4"),
+			})
+
+		// Write the answer back to the client
+		if err := resp.WriteMsg(ans); err != nil {
+			t.Fatalf("err: %s", err)
+		}
+	})
+	server := &dns.Server{
+		Addr:    dnsAddr,
+		Net:     "udp",
+		Handler: mux,
+	}
+	go server.ListenAndServe()
+	defer server.Shutdown()
+
+	// Create the Consul server
+	dconf := &DNSConfig{}
+	config := nextConfig()
+	addr, _ := config.ClientListener(config.Addresses.DNS, config.Ports.DNS)
+	dir, agent := makeAgent(t, config)
+	defer os.RemoveAll(dir)
+	defer agent.Shutdown()
+
+	srv, err := NewDNSServer(agent, dconf, agent.logOutput,
+		config.Domain, addr.String(), []string{dnsAddr})
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	testutil.WaitForLeader(t, srv.agent.RPC, "dc1")
+
+	// Register a service with a recursing CNAME as the address
+	args := &structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "a.example.com",
+		Service: &structs.NodeService{
+			Service: "db",
+			Tags:    []string{"master"},
+			Address: "a.example.com",
+			Port:    12345,
+		},
+	}
+
+	var out struct{}
+	if err := srv.agent.RPC("Catalog.Register", args, &out); err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Create the DNS query against the Consul server
+	m := new(dns.Msg)
+	m.SetQuestion("db.service.consul.", dns.TypeA)
+
+	c := new(dns.Client)
+	c.Net = "tcp"
+	in, _, err := c.Exchange(m, addr.String())
+	if err != nil {
+		t.Fatalf("err: %v", err)
+	}
+
+	// Should have all 3 CNAMES and the A record
+	if len(in.Answer) != 4 {
+		t.Fatalf("Bad: %#v", in)
+	}
+
+	// Check all the records
+	expected := []dns.RR{
+		&dns.CNAME{
+			Hdr: dns.RR_Header{
+				Rrtype: dns.TypeCNAME,
+			},
+			Target: "abc",
+		},
+		&dns.CNAME{
+			Hdr: dns.RR_Header{
+				Rrtype: dns.TypeCNAME,
+			},
+			Target: "abc",
+		},
+		&dns.CNAME{
+			Hdr: dns.RR_Header{
+				Rrtype: dns.TypeCNAME,
+			},
+			Target: "abc",
+		},
+		&dns.A{
+			Hdr: dns.RR_Header{
+				Rrtype: dns.TypeCNAME,
+			},
+			A: net.ParseIP("1.2.3.4"),
+		},
+	}
+
+	if !reflect.DeepEqual(expected, in.Answer) {
+		t.Fatalf("Bad: %v %v", expected, in.Answer)
+	}
+}