Makes name compares case-insensitive.

command/agent/dns.go

@@ -494,11 +494,13 @@ func (d *DNSServer) formatNodeRecord(node *structs.Node, addr, qName string, qTy
 	return records
 }
 
-// indexRRs creates a map which indexes a given list of RRs by name.
+// indexRRs creates a map which indexes a given list of RRs by name. NOTE that
+// the names are all squashed to lower case so we can perform case-insensitive
+// lookups; the RRs are not modified.
 func indexRRs(rrs []dns.RR) map[string]dns.RR {
 	index := make(map[string]dns.RR, len(rrs))
 	for _, rr := range rrs {
-		name := rr.Header().Name
+		name := strings.ToLower(rr.Header().Name)
 		if _, ok := index[name]; !ok {
 			index[name] = rr
 		}
@@ -519,7 +521,11 @@ func syncExtra(index map[string]dns.RR, resp *dns.Msg) {
 		if !ok {
 			continue
 		}
-		target := srv.Target
+
+		// Note that we always use lower case when using the index so
+		// that compares are not case-sensitive. We don't alter the actual
+		// RRs we add into the extra section, however.
+		target := strings.ToLower(srv.Target)
 
 	RESOLVE:
 		if _, ok := resolved[target]; ok {
@@ -531,7 +537,7 @@ func syncExtra(index map[string]dns.RR, resp *dns.Msg) {
 		if ok {
 			extra = append(extra, extraRR)
 			if cname, ok := extraRR.(*dns.CNAME); ok {
-				target = cname.Target
+				target = strings.ToLower(cname.Target)
 				goto RESOLVE
 			}
 		}

command/agent/dns_test.go

@@ -3403,6 +3403,19 @@ func TestDNS_syncExtra(t *testing.T) {
 				Port:   1003,
 				Target: "demo.consul.io.",
 			},
+			// This one isn't in the Consul domain and it will get
+			// a CNAME and A record from a recursor that alters the
+			// case of the name. This proves we look up in the index
+			// in a case-insensitive way.
+			&dns.SRV{
+				Hdr: dns.RR_Header{
+					Name:   "redis-cache-redis.service.consul.",
+					Rrtype: dns.TypeSRV,
+					Class:  dns.ClassINET,
+				},
+				Port:   1001,
+				Target: "insensitive.consul.io.",
+			},
 			// This is also a CNAME, but it'll be set up to loop to
 			// make sure we don't crash.
 			&dns.SRV{
@@ -3462,6 +3475,23 @@ func TestDNS_syncExtra(t *testing.T) {
 				},
 				Target: "fakeserver.consul.io.",
 			},
+			// These differ in case to test case insensitivity.
+			&dns.CNAME{
+				Hdr: dns.RR_Header{
+					Name:   "INSENSITIVE.CONSUL.IO.",
+					Rrtype: dns.TypeCNAME,
+					Class:  dns.ClassINET,
+				},
+				Target: "Another.Server.Com.",
+			},
+			&dns.A{
+				Hdr: dns.RR_Header{
+					Name:   "another.server.com.",
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+				},
+				A: net.ParseIP("127.0.0.1"),
+			},
 			// This doesn't appear in the answer, so should get
 			// dropped.
 			&dns.A{
@@ -3522,6 +3552,22 @@ func TestDNS_syncExtra(t *testing.T) {
 				},
 				A: net.ParseIP("127.0.0.1"),
 			},
+			&dns.CNAME{
+				Hdr: dns.RR_Header{
+					Name:   "INSENSITIVE.CONSUL.IO.",
+					Rrtype: dns.TypeCNAME,
+					Class:  dns.ClassINET,
+				},
+				Target: "Another.Server.Com.",
+			},
+			&dns.A{
+				Hdr: dns.RR_Header{
+					Name:   "another.server.com.",
+					Rrtype: dns.TypeA,
+					Class:  dns.ClassINET,
+				},
+				A: net.ParseIP("127.0.0.1"),
+			},
 			&dns.CNAME{
 				Hdr: dns.RR_Header{
 					Name:   "deadly.consul.io.",