file/plugin: if there is a delegation use that (#1299)

Don't put NS records in the answer section; if we see it is delegated
we should put the records in the AUTHORITY section.

This removes a special case, which is good.

plugin/file/delegation_test.go

@@ -25,7 +25,7 @@ var delegationTestCases = []test.Case{
 	},
 	{
 		Qname: "delegated.miek.nl.", Qtype: dns.TypeNS,
-		Answer: []dns.RR{
+		Ns: []dns.RR{
 			test.NS("delegated.miek.nl.	1800	IN	NS	a.delegated.miek.nl."),
 			test.NS("delegated.miek.nl.	1800	IN	NS	ns-ext.nlnetlabs.nl."),
 		},
@@ -91,9 +91,12 @@ var secureDelegationTestCases = []test.Case{
 	{
 		Qname: "delegated.example.org.", Qtype: dns.TypeNS,
 		Do: true,
-		Answer: []dns.RR{
+		Ns: []dns.RR{
+			test.DS("delegated.example.org.	1800	IN	DS	10056 5 1 EE72CABD1927759CDDA92A10DBF431504B9E1F13"),
+			test.DS("delegated.example.org.	1800	IN	DS	10056 5 2 E4B05F87725FA86D9A64F1E53C3D0E6250946599DFE639C45955B0ED416CDDFA"),
 			test.NS("delegated.example.org.	1800	IN	NS	a.delegated.example.org."),
 			test.NS("delegated.example.org.	1800	IN	NS	ns-ext.nlnetlabs.nl."),
+			test.RRSIG("delegated.example.org.	1800	IN	RRSIG	DS 13 3 1800 20161129153240 20161030153240 49035 example.org. rlNNzcUmtbjLSl02ZzQGUbWX75yCUx0Mug1jHtKVqRq1hpPE2S3863tIWSlz+W9wz4o19OI4jbznKKqk+DGKog=="),
 		},
 		Extra: []dns.RR{
 			test.OPT(4096, true),

plugin/file/lookup.go

@@ -128,11 +128,6 @@ func (z *Zone) Lookup(state request.Request, qname string) ([]dns.RR, []dns.RR,
 		// If we see NS records, it means the name as been delegated, and we should return the delegation.
 		if nsrrs := elem.Types(dns.TypeNS); nsrrs != nil {
 			glue := z.Glue(nsrrs, do)
-			// If qtype == NS, we should returns success to put RRs in answer.
-			if qtype == dns.TypeNS {
-				return nsrrs, nil, glue, Success
-			}
-
 			if do {
 				dss := z.typeFromElem(elem, dns.TypeDS, do)
 				nsrrs = append(nsrrs, dss...)