Improve resource record implementation in the mdns package.

pkg/mdns/test/resource_record_cache.dart

+// Copyright (c) 2015, the Fletch project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE.md file.
+
+// Test that the resource record cache works correctly.  In particular, make
+// sure that it removes all entries for a name before inserting new records
+// of that name.
+
+import 'dart:io';
+
+import 'package:expect/expect.dart';
+import 'package:mdns/src/constants.dart' show RRType;
+import 'package:mdns/src/native_protocol_client.dart'
+    show ResourceRecordCache;
+import 'package:mdns/src/packet.dart';
+
+int entries(ResourceRecordCache cache) {
+  int c = 0;
+  for (int i = 0; i < cache.size; i++) {
+    if (cache.buffer[i] != null) {
+      ++c;
+    }
+  }
+  return c;
+}
+
+main() {
+  testOverwrite();
+  testTimeout();
+}
+
+testOverwrite() {
+  InternetAddress ip1 = new InternetAddress("192.168.1.1");
+  InternetAddress ip2 = new InternetAddress("192.168.1.2");
+  int valid = new DateTime.now().millisecondsSinceEpoch + 86400 * 1000;
+
+  ResourceRecordCache cache = new ResourceRecordCache();
+
+  // Add two different records.
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "hest", ip1, valid),
+    new ResourceRecord(RRType.A, "fisk", ip2, valid)]);
+  Expect.equals(2, entries(cache));
+
+  // Update these records.
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "hest", ip1, valid),
+    new ResourceRecord(RRType.A, "fisk", ip2, valid)]);
+  Expect.equals(2, entries(cache));
+
+  // Add two records with the same name (should remove the old one
+  // with that name only.)
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "hest", ip1, valid),
+    new ResourceRecord(RRType.A, "hest", ip2, valid)]);
+  Expect.equals(3, entries(cache));
+
+  // Overwrite the two cached entries with one with the same name.
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "hest", ip1, valid),
+  ]);
+  Expect.equals(2, entries(cache));
+}
+
+testTimeout() {
+  InternetAddress ip1 = new InternetAddress("192.168.1.1");
+  InternetAddress ip2 = new InternetAddress("192.168.1.2");
+  int valid = new DateTime.now().millisecondsSinceEpoch + 86400 * 1000;
+  int notValid = new DateTime.now().millisecondsSinceEpoch - 1;
+
+  ResourceRecordCache cache = new ResourceRecordCache();
+
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "hest", ip1, valid)
+  ]);
+  Expect.equals(1, entries(cache));
+
+  cache.updateRecords([
+    new ResourceRecord(RRType.A, "fisk", ip1, notValid)
+  ]);
+
+  var results;
+  results = [];
+  cache.lookup("hest", RRType.A, results);
+  Expect.isFalse(results.isEmpty);
+
+  results = [];
+  cache.lookup("fisk", RRType.A, results);
+  Expect.isTrue(results.isEmpty);
+  Expect.equals(1, entries(cache));
+}