plugin/hosts: make unsupported type fallthrough opt-in (#8282)

plugin/hosts/hosts_test.go

@@ -58,31 +58,81 @@ func TestLookupA(t *testing.T) {
 }
 
 func TestFallthroughUnsupportedType(t *testing.T) {
-	h := Hosts{
-		Next: test.NextHandler(dns.RcodeRefused, nil),
-		Hostsfile: &Hostsfile{
-			Origins: []string{"."},
-			hmap:    newMap(),
-			inline:  newMap(),
-			options: newOptions(),
+	tests := []struct {
+		name              string
+		qname             string
+		fall              fall.F
+		unsupported       bool
+		expectFallthrough bool
+	}{
+		{
+			name:  "existing name returns nodata by default",
+			qname: "example.org.",
+			fall:  fall.Root,
+		},
+		{
+			name:              "existing name falls through with opt-in",
+			qname:             "example.org.",
+			fall:              fall.Root,
+			unsupported:       true,
+			expectFallthrough: true,
+		},
+		{
+			name:        "opt-in respects fallthrough zones",
+			qname:       "example.org.",
+			fall:        fall.F{Zones: []string{"example.net."}},
+			unsupported: true,
+		},
+		{
+			name:              "missing name still falls through",
+			qname:             "missing.example.org.",
+			fall:              fall.Root,
+			expectFallthrough: true,
 		},
-		Fall: fall.Root,
 	}
-	h.hmap = h.parse(strings.NewReader(hostsExample))
 
-	m := new(dns.Msg)
-	m.SetQuestion("example.org.", dns.TypeTXT)
-	rec := dnstest.NewRecorder(&test.ResponseWriter{})
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			h := Hosts{
+				Next: test.NextHandler(dns.RcodeRefused, nil),
+				Hostsfile: &Hostsfile{
+					Origins: []string{"."},
+					hmap:    newMap(),
+					inline:  newMap(),
+					options: newOptions(),
+				},
+				Fall:                   tc.fall,
+				fallthroughUnsupported: tc.unsupported,
+			}
+			h.hmap = h.parse(strings.NewReader(hostsExample))
 
-	rcode, err := h.ServeDNS(context.Background(), rec, m)
-	if err != nil {
-		t.Fatalf("Expected no error, got %v", err)
-	}
-	if rcode != dns.RcodeRefused {
-		t.Fatalf("Expected fallthrough rcode %d, got %d", dns.RcodeRefused, rcode)
-	}
-	if rec.Msg != nil {
-		t.Fatalf("Expected no response from hosts after fallthrough, got %#v", rec.Msg)
+			m := new(dns.Msg)
+			m.SetQuestion(tc.qname, dns.TypeTXT)
+			rec := dnstest.NewRecorder(&test.ResponseWriter{})
+
+			rcode, err := h.ServeDNS(context.Background(), rec, m)
+			if err != nil {
+				t.Fatalf("Expected no error, got %v", err)
+			}
+			if tc.expectFallthrough {
+				if rcode != dns.RcodeRefused {
+					t.Fatalf("Expected fallthrough rcode %d, got %d", dns.RcodeRefused, rcode)
+				}
+				if rec.Msg != nil {
+					t.Fatalf("Expected no response from hosts after fallthrough, got %#v", rec.Msg)
+				}
+				return
+			}
+			if rcode != dns.RcodeSuccess {
+				t.Fatalf("Expected authoritative NODATA rcode %d, got %d", dns.RcodeSuccess, rcode)
+			}
+			if rec.Msg == nil {
+				t.Fatal("Expected authoritative NODATA response from hosts, got no response")
+			}
+			if !rec.Msg.Authoritative || len(rec.Msg.Answer) != 0 {
+				t.Fatalf("Expected authoritative NODATA response, got %#v", rec.Msg)
+			}
+		})
 	}
 }