feat(MulticastService): enable/disable ignoring duplicate message

src/MulticastService.cs

@@ -132,6 +132,7 @@ public MulticastService(Func<IEnumerable<NetworkInterface>, IEnumerable<NetworkI
 
             UseIpv4 = Socket.OSSupportsIPv4;
             UseIpv6 = Socket.OSSupportsIPv6;
+            IgnoreDuplicateMessages = true;
         }
 
         /// <summary>
@@ -150,6 +151,18 @@ public MulticastService(Func<IEnumerable<NetworkInterface>, IEnumerable<NetworkI
         /// </value>
         public bool UseIpv6 { get; set; }
 
+        /// <summary>
+        ///   Determines if received messages are checked for duplicates.
+        /// </summary>
+        /// <value>
+        ///   <b>true</b> to ignore duplicate messages. Defaults to <b>true</b>.
+        /// </value>
+        /// <remarks>
+        ///   When set, a message that has been received within the last minute
+        ///   will be ignored.
+        /// </remarks>
+        public bool IgnoreDuplicateMessages { get; set; }
+
         /// <summary>
         ///   The interval for discovering network interfaces.
         /// </summary>

test/MulticastServiceTest.cs

@@ -19,6 +19,7 @@ public void Can_Create()
         {
             var mdns = new MulticastService();
             Assert.IsNotNull(mdns);
+            Assert.IsTrue(mdns.IgnoreDuplicateMessages);
         }
 
         [TestMethod]

test/ServiceDiscoveryTest.cs

@@ -524,7 +524,10 @@ public void Announce_SentTwice()
             var service = new ServiceProfile("z", "_sdtest-4._udp", 1024, new[] { IPAddress.Loopback });
             var done = new ManualResetEvent(false);
             var nanswers = 0;
-            var mdns = new MulticastService();
+            var mdns = new MulticastService
+            {
+                IgnoreDuplicateMessages = false
+            };
             mdns.AnswerReceived += (s, e) =>
             {
                 var msg = e.Message;