middleware/file: add nsec for wildcard expansion (#382)

A NSEC record is need to deny any other name that might exist.
Also don't blindly perform the interface conversion when getting
glue for NS records as they now may include RRSIG - also add tests
for that.

middleware/file/closest.go

@@ -6,7 +6,7 @@ import (
 	"github.com/miekg/dns"
 )
 
-// ClosestEncloser returns the closest encloser for rr.
+// ClosestEncloser returns the closest encloser for qname.
 func (z *Zone) ClosestEncloser(qname string) (*tree.Elem, bool) {
 
 	offset, end := dns.NextLabel(qname, 0)

middleware/file/dnssec_test.go

@@ -29,6 +29,17 @@ var dnssecTestCases = []test.Case{
 		},
 		Extra: []dns.RR{test.OPT(4096, true)},
 	},
+	{
+		Qname: "miek.nl.", Qtype: dns.TypeNS, Do: true,
+		Answer: []dns.RR{
+			test.NS("miek.nl.	1800	IN	NS	ext.ns.whyscream.net."),
+			test.NS("miek.nl.	1800	IN	NS	linode.atoom.net."),
+			test.NS("miek.nl.	1800	IN	NS	ns-ext.nlnetlabs.nl."),
+			test.NS("miek.nl.	1800	IN	NS	omval.tednet.nl."),
+			test.RRSIG("miek.nl.	1800	IN	RRSIG	NS 8 2 1800 20160426031301 20160327031301 12051 miek.nl. ZLtsQhwaz+lHfNpztFoR1Vxs="),
+		},
+		Extra: []dns.RR{test.OPT(4096, true)},
+	},
 	{
 		Qname: "miek.nl.", Qtype: dns.TypeMX, Do: true,
 		Answer: []dns.RR{

middleware/file/lookup.go

@@ -146,7 +146,9 @@ func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR,
 
 	// Haven't found the original name.
 
+	// Found wildcard.
 	if wildElem != nil {
+		auth := []dns.RR{}
 
 		if rrs := wildElem.Types(dns.TypeCNAME, qname); len(rrs) > 0 {
 			return z.searchCNAME(rrs, qtype, do)
@@ -154,26 +156,29 @@ func (z *Zone) Lookup(qname string, qtype uint16, do bool) ([]dns.RR, []dns.RR,
 
 		rrs := wildElem.Types(qtype, qname)
 
-		// NODATA
+		// NODATA response.
 		if len(rrs) == 0 {
 			ret := z.soa(do)
 			if do {
-				// Do we need to add closest encloser here as well.
-				// closest encloser
-				//				ce, _ := z.ClosestEncloser(qname)
-				//				println("CLOSEST ENCLOSER", ce.Name()) // need to add this too.
 				nsec := z.typeFromElem(wildElem, dns.TypeNSEC, do)
 				ret = append(ret, nsec...)
 			}
 			return nil, ret, nil, Success
 		}
+
 		if do {
+			// An NSEC is needed to say no longer name exists under this wildcard.
+			if deny, found := z.Tree.Prev(qname); found {
+				nsec := z.typeFromElem(deny, dns.TypeNSEC, do)
+				auth = append(auth, nsec...)
+			}
+
 			sigs := wildElem.Types(dns.TypeRRSIG, qname)
 			sigs = signatureForSubType(sigs, qtype)
 			rrs = append(rrs, sigs...)
 
 		}
-		return rrs, nil, nil, Success
+		return rrs, auth, nil, Success
 	}
 
 	rcode := NameError
@@ -289,9 +294,9 @@ func signatureForSubType(rrs []dns.RR, subtype uint16) []dns.RR {
 // Glue returns any potential glue records for nsrrs.
 func (z *Zone) Glue(nsrrs []dns.RR) []dns.RR {
 	glue := []dns.RR{}
-	for _, ns := range nsrrs {
-		if dns.IsSubDomain(ns.Header().Name, ns.(*dns.NS).Ns) {
-			glue = append(glue, z.searchGlue(ns.(*dns.NS).Ns)...)
+	for _, rr := range nsrrs {
+		if ns, ok := rr.(*dns.NS); ok && dns.IsSubDomain(ns.Header().Name, ns.Ns) {
+			glue = append(glue, z.searchGlue(ns.Ns)...)
 		}
 	}
 	return glue

middleware/file/wildcard_test.go

@@ -31,6 +31,10 @@ var wildcardTestCases = []test.Case{
 			test.RRSIG("wild.dnssex.nl.	1800	IN	RRSIG	TXT 8 2 1800 20160428190224 20160329190224 14460 dnssex.nl. FUZSTyvZfeuuOpCm"),
 			test.TXT(`wild.dnssex.nl.	1800	IN	TXT	"Doing It Safe Is Better"`),
 		},
+		Ns: []dns.RR{
+			test.NSEC("a.dnssex.nl.	14400	IN	NSEC	www.dnssex.nl. A AAAA RRSIG NSEC"),
+			test.RRSIG("a.dnssex.nl.	14400	IN	RRSIG	NSEC 8 3 14400 20160428190224 20160329190224 14460 dnssex.nl. S+UMs2ySgRaaRY"),
+		},
 		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	{
@@ -39,6 +43,10 @@ var wildcardTestCases = []test.Case{
 			test.RRSIG("a.wild.dnssex.nl.	1800	IN	RRSIG	TXT 8 2 1800 20160428190224 20160329190224 14460 dnssex.nl. FUZSTyvZfeuuOpCm"),
 			test.TXT(`a.wild.dnssex.nl.	1800	IN	TXT	"Doing It Safe Is Better"`),
 		},
+		Ns: []dns.RR{
+			test.NSEC("a.dnssex.nl.	14400	IN	NSEC	www.dnssex.nl. A AAAA RRSIG NSEC"),
+			test.RRSIG("a.dnssex.nl.	14400	IN	RRSIG	NSEC 8 3 14400 20160428190224 20160329190224 14460 dnssex.nl. S+UMs2ySgRaaRY"),
+		},
 		Extra: []dns.RR{test.OPT(4096, true)},
 	},
 	// nodata responses