Added using of NetworkChange.NetworkAddressChanged instead of Timer

Spike/Program.cs

@@ -21,10 +21,7 @@ static void Main(string[] args)
             };
             LogManager.Adapter = new ConsoleOutLoggerFactoryAdapter(properties);
 
-            var mdns = new MulticastService
-            {
-                NetworkInterfaceDiscoveryInterval = TimeSpan.FromSeconds(1),
-            };
+            var mdns = new MulticastService();
 
             foreach (var a in MulticastService.GetIPAddresses())
             {

src/MulticastService.cs

@@ -1,16 +1,16 @@
-using Common.Logging;
-using System;
-using System.Collections.Generic;
+using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.Linq;
 using System.Net;
 using System.Net.NetworkInformation;
 using System.Net.Sockets;
 using System.Runtime.InteropServices;
-using System.Threading;
-using System.Threading.Tasks;
 using System.Security.Cryptography;
 using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Common.Logging;
 
 namespace Makaretu.Dns
 {
@@ -82,7 +82,8 @@ static MulticastService()
         ///   Always use socketLock to gain access.
         /// </remarks>
         UdpClient sender;
-        readonly Object senderLock = new object();
+
+        readonly object senderLock = new object();
 
         /// <summary>
         ///   Raised when any local MDNS service sends a query.
@@ -123,23 +124,10 @@ public MulticastService()
                 throw new InvalidOperationException("No OS support for IPv4 nor IPv6");
 
             mdnsEndpoint = new IPEndPoint(
-                ip6 ? MulticastAddressIp6 : MulticastAddressIp4, 
+                ip6 ? MulticastAddressIp6 : MulticastAddressIp4,
                 MulticastPort);
         }
 
-        /// <summary>
-        ///   The interval for discovering network interfaces.
-        /// </summary>
-        /// <value>
-        ///   Default is 2 minutes.
-        /// </value>
-        /// <remarks>
-        ///   When the interval is reached a task is started to discover any
-        ///   new network interfaces. 
-        /// </remarks>
-        /// <seealso cref="NetworkInterfaceDiscovered"/>
-        public TimeSpan NetworkInterfaceDiscoveryInterval { get; set; } = TimeSpan.FromMinutes(2);
-
         /// <summary>
         ///   Get the network interfaces that are useable.
         /// </summary>
@@ -200,7 +188,7 @@ public void Start()
             knownNics.Clear();
 
             // Start a task to find the network interfaces.
-            PollNetworkInterfaces();
+            FindNetworkInterfaces();
         }
 
         /// <summary>
@@ -235,26 +223,9 @@ public void Stop()
             }
         }
 
-        async void PollNetworkInterfaces()
+        void OnNetworkAddressChanged(object sender, EventArgs e)
         {
-            var cancel = serviceCancellation.Token;
-            try
-            {
-                while (!cancel.IsCancellationRequested)
-                {
-                    FindNetworkInterfaces();
-                    await Task.Delay(NetworkInterfaceDiscoveryInterval, cancel);
-                }
-            }
-            catch (TaskCanceledException)
-            {
-                //  eat it
-            }
-            catch (Exception e)
-            {
-                log.Error(e);
-                // eat it.
-            }
+            FindNetworkInterfaces();
         }
 
         void FindNetworkInterfaces()
@@ -282,6 +253,7 @@ void FindNetworkInterfaces()
                     }
                 }
             }
+
             knownNics = currentNics;
 
             // If any NIC change, then get new sockets.
@@ -297,17 +269,20 @@ void FindNetworkInterfaces()
                 sender.MulticastLoopback = true;
 
                 // Start a task to listen for MDNS messages.
-                Listener();
+                Task.Factory.StartNew(async () => await ListenerAsync());
             }
 
             // Tell others.
             if (newNics.Any())
-            { 
+            {
                 NetworkInterfaceDiscovered?.Invoke(this, new NetworkInterfaceEventArgs
                 {
                     NetworkInterfaces = newNics
                 });
             }
+
+            NetworkChange.NetworkAddressChanged -= OnNetworkAddressChanged;
+            NetworkChange.NetworkAddressChanged += OnNetworkAddressChanged;
         }
 
         /// <inheritdoc />
@@ -547,7 +522,7 @@ void OnDnsMessage(byte[] datagram, int length)
         ///   A background task to receive DNS messages from this and other MDNS services.  It is
         ///   cancelled via <see cref="Stop"/>.  All messages are forwarded to <see cref="OnDnsMessage"/>.
         /// </remarks>
-        async void Listener()
+        async Task ListenerAsync()
         {
             var isWindows = RuntimeInformation.IsOSPlatform(OSPlatform.Windows);
 
@@ -558,25 +533,25 @@ async void Listener()
             }
 
             listenerCancellation = new CancellationTokenSource();
+
             UdpClient receiver = new UdpClient(mdnsEndpoint.AddressFamily);
             if (isWindows)
             {
                 receiver.ExclusiveAddressUse = false;
             }
-            receiver.Client.SetSocketOption(
-                SocketOptionLevel.Socket, 
-                SocketOptionName.ReuseAddress,
-                true);
+            receiver.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
             if (isWindows)
             {
                 receiver.ExclusiveAddressUse = false;
             }
             var endpoint = new IPEndPoint(ip6 ? IPAddress.IPv6Any : IPAddress.Any, MulticastPort);
             receiver.Client.Bind(endpoint);
-            receiver.JoinMulticastGroup(mdnsEndpoint.Address);
+            receiver.JoinMulticastGroup(mdnsEndpoint.Address, endpoint.Address);
 
             var cancel = listenerCancellation.Token;
+
             cancel.Register(() => receiver.Dispose());
+
             try
             {
                 while (!cancel.IsCancellationRequested)
@@ -592,11 +567,10 @@ async void Listener()
                 // eat the exception
             }
 
-            receiver.Dispose();
-            if (listenerCancellation != null)
+            using (var lc = listenerCancellation)
             {
-                listenerCancellation.Dispose();
                 listenerCancellation = null;
+                lc?.Cancel();
             }
         }
 
@@ -618,6 +592,5 @@ public void Dispose()
         }
 
         #endregion
-
     }
 }

src/ServiceDiscovery.cs

@@ -1,9 +1,8 @@
-using Common.Logging;
-using Makaretu.Dns.Resolving;
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
-using System.Net;
+using Common.Logging;
+using Makaretu.Dns.Resolving;
 
 namespace Makaretu.Dns
 {
@@ -80,7 +79,8 @@ public ServiceDiscovery(MulticastService mdns)
         /// <value>
         ///   Is used to answer questions.
         /// </value>
-        public NameServer NameServer { get; } = new NameServer {
+        public NameServer NameServer { get; } = new NameServer
+        {
             Catalog = new Catalog(),
             AnswerAllQuestions = true
         };
@@ -196,31 +196,39 @@ void OnQuery(object sender, MessageEventArgs e)
             var request = e.Message;
 
             if (log.IsDebugEnabled)
+            {
                 log.Debug($"got query for {request.Questions[0].Name} {request.Questions[0].Type}");
+            }
+
             var response = NameServer.ResolveAsync(request).Result;
-            if (response.Status == MessageStatus.NoError)
+
+            if (response.Status != MessageStatus.NoError)
             {
-                // Many bonjour browsers don't like DNS-SD response
-                // with additional records.
-                if (response.Answers.Any(a => a.Name == ServiceName))
-                {
-                    response.AdditionalRecords.Clear();
-                }
+                return;
+            }
 
-                if (AnswersContainsAdditionalRecords)
-                {
-                    response.Answers.AddRange(response.AdditionalRecords);
-                    response.AdditionalRecords.Clear();
-                }
+            if (AnswersContainsAdditionalRecords)
+            {
+                response.Answers.AddRange(response.AdditionalRecords);
+            }
+
+            // Many bonjour browsers don't like DNS-SD response
+            // with additional records.
+            if (response.Answers.Any(a => a.Name == ServiceName))
+            {
+                response.AdditionalRecords.Clear();
+            }
+
+            Mdns.SendAnswer(response);
 
-                Mdns.SendAnswer(response);
-                if (log.IsDebugEnabled)
-                    log.Debug($"sent answer {response.Answers[0]}");
-                //Console.WriteLine($"Response time {(DateTime.Now - request.CreationTime).TotalMilliseconds}ms");
+            if (log.IsDebugEnabled)
+            {
+                log.Debug($"sent answer {response.Answers[0]}");
             }
+            //Console.WriteLine($"Response time {(DateTime.Now - request.CreationTime).TotalMilliseconds}ms");
         }
 
-#region IDisposable Support
+        #region IDisposable Support
 
         /// <inheritdoc />
         protected virtual void Dispose(bool disposing)
@@ -245,7 +253,8 @@ public void Dispose()
         {
             Dispose(true);
         }
-#endregion
+
+        #endregion
     }
 
 }

test/ServiceDiscoveryTest.cs

@@ -194,39 +194,35 @@ public void Discover_ServiceInstance_WithAnswersContainingAdditionRecords()
         {
             var service = new ServiceProfile("y", "_sdtest-2._udp", 1024);
             var done = new ManualResetEvent(false);
-            var mdns = new MulticastService();
-            var sd = new ServiceDiscovery(mdns)
-            {
-                AnswersContainsAdditionalRecords = true
-            };
-            Message discovered = null;
-            mdns.NetworkInterfaceDiscovered += (s, e) =>
-            {
-                sd.QueryServiceInstances(service.ServiceName);
-            };
 
-            sd.ServiceInstanceDiscovered += (s, e) =>
+            using (var mdns = new MulticastService())
+            using (var sd = new ServiceDiscovery(mdns) { AnswersContainsAdditionalRecords = true })
             {
-                if (e.ServiceInstanceName == service.FullyQualifiedName)
+                Message discovered = null;
+
+                mdns.NetworkInterfaceDiscovered += (s, e) =>
                 {
-                    Assert.IsNotNull(e.Message);
-                    discovered = e.Message;
-                    done.Set();
-                }
-            };
-            try
-            {
+                    sd.QueryServiceInstances(service.ServiceName);
+                };
+
+                sd.ServiceInstanceDiscovered += (s, e) =>
+                {
+                    if (e.ServiceInstanceName == service.FullyQualifiedName)
+                    {
+                        Assert.IsNotNull(e.Message);
+                        discovered = e.Message;
+                        done.Set();
+                    }
+                };
+
                 sd.Advertise(service);
+
                 mdns.Start();
+
                 Assert.IsTrue(done.WaitOne(TimeSpan.FromSeconds(1)), "instance not found");
-                Assert.AreEqual(0, discovered.AdditionalRecords.Count);
-                Assert.IsTrue(discovered.Answers.Count > 1);
-            }
-            finally
-            {
-                sd.Dispose();
-                mdns.Stop();
-            }
+                Assert.IsTrue(discovered.AdditionalRecords.Count > 0);
+                Assert.IsTrue(discovered.Answers.Count > 0);
+            }            
         }
 
     }