Merge pull request #2394 from arkodg/dns-lookup-case-insensitive

    Make DNS records and queries case-insensitive

Author: euanh

network.go

@@ -1381,14 +1381,18 @@ func delIPToName(ipMap setmatrix.SetMatrix, name, serviceID string, ip net.IP) {
 }
 
 func addNameToIP(svcMap setmatrix.SetMatrix, name, serviceID string, epIP net.IP) {
-	svcMap.Insert(name, svcMapEntry{
+	// Since DNS name resolution is case-insensitive, Use the lower-case form
+	// of the name as the key into svcMap
+	lowerCaseName := strings.ToLower(name)
+	svcMap.Insert(lowerCaseName, svcMapEntry{
 		ip:        epIP.String(),
 		serviceID: serviceID,
 	})
 }
 
 func delNameToIP(svcMap setmatrix.SetMatrix, name, serviceID string, epIP net.IP) {
-	svcMap.Remove(name, svcMapEntry{
+	lowerCaseName := strings.ToLower(name)
+	svcMap.Remove(lowerCaseName, svcMapEntry{
 		ip:        epIP.String(),
 		serviceID: serviceID,
 	})
@@ -1956,6 +1960,7 @@ func (n *network) ResolveName(req string, ipType int) ([]net.IP, bool) {
 	}
 
 	req = strings.TrimSuffix(req, ".")
+	req = strings.ToLower(req)
 	ipSet, ok := sr.svcMap.Get(req)
 
 	if ipType == types.IPv6 {

resolver.go

@@ -366,8 +366,8 @@ func (r *resolver) ServeDNS(w dns.ResponseWriter, query *dns.Msg) {
 	if query == nil || len(query.Question) == 0 {
 		return
 	}
-	name := query.Question[0].Name
 
+	name := query.Question[0].Name
 	switch query.Question[0].Qtype {
 	case dns.TypeA:
 		resp, err = r.handleIPQuery(name, query, types.IPv4)

resolver_test.go

@@ -126,29 +126,33 @@ func TestDNSIPQuery(t *testing.T) {
 	r := NewResolver(resolverIPSandbox, false, sb.Key(), sb.(*sandbox))
 
 	// test name1's IP is resolved correctly with the default A type query
-	q := new(dns.Msg)
-	q.SetQuestion("name1", dns.TypeA)
-	r.(*resolver).ServeDNS(w, q)
-	resp := w.GetResponse()
-	checkNonNullResponse(t, resp)
-	t.Log("Response: ", resp.String())
-	checkDNSResponseCode(t, resp, dns.RcodeSuccess)
-	checkDNSAnswersCount(t, resp, 1)
-	checkDNSRRType(t, resp.Answer[0].Header().Rrtype, dns.TypeA)
-	if answer, ok := resp.Answer[0].(*dns.A); ok {
-		if !bytes.Equal(answer.A, net.ParseIP("192.168.0.1")) {
-			t.Fatalf("IP response in Answer %v does not match 192.168.0.1", answer.A)
+	// Also make sure DNS lookups are case insensitive
+	names := []string{"name1", "NaMe1"}
+	for _, name := range names {
+		q := new(dns.Msg)
+		q.SetQuestion(name, dns.TypeA)
+		r.(*resolver).ServeDNS(w, q)
+		resp := w.GetResponse()
+		checkNonNullResponse(t, resp)
+		t.Log("Response: ", resp.String())
+		checkDNSResponseCode(t, resp, dns.RcodeSuccess)
+		checkDNSAnswersCount(t, resp, 1)
+		checkDNSRRType(t, resp.Answer[0].Header().Rrtype, dns.TypeA)
+		if answer, ok := resp.Answer[0].(*dns.A); ok {
+			if !bytes.Equal(answer.A, net.ParseIP("192.168.0.1")) {
+				t.Fatalf("IP response in Answer %v does not match 192.168.0.1", answer.A)
+			}
+		} else {
+			t.Fatal("Answer of type A not found")
 		}
-	} else {
-		t.Fatal("Answer of type A not found")
+		w.ClearResponse()
 	}
-	w.ClearResponse()
 
 	// test MX query with name1 results in Success response with 0 answer records
-	q = new(dns.Msg)
+	q := new(dns.Msg)
 	q.SetQuestion("name1", dns.TypeMX)
 	r.(*resolver).ServeDNS(w, q)
-	resp = w.GetResponse()
+	resp := w.GetResponse()
 	checkNonNullResponse(t, resp)
 	t.Log("Response: ", resp.String())
 	checkDNSResponseCode(t, resp, dns.RcodeSuccess)