fix(ServiceProfile): only advertise link local addresses

src/Mdns.csproj

@@ -31,6 +31,7 @@
 
   <ItemGroup>
     <PackageReference Include="Common.Logging" Version="3.4.1" />
+    <PackageReference Include="IPNetwork2" Version="2.1.2" />
     <PackageReference Include="Makaretu.Dns" Version="0.13.4" />
   </ItemGroup>
 

src/MulticastService.cs

@@ -28,6 +28,11 @@ public class MulticastService : IResolver, IDisposable
         static readonly ILog log = LogManager.GetLogger(typeof(MulticastService));
         static readonly IPAddress MulticastAddressIp4 = IPAddress.Parse("224.0.0.251");
         static readonly IPAddress MulticastAddressIp6 = IPAddress.Parse("FF02::FB");
+        static readonly IPNetwork[] linkLocalNetworks = new IPNetwork[]
+        {
+            IPNetwork.Parse("169.254.0.0/16"),
+            IPNetwork.Parse("fe80::/10")
+        };
 
         const int MulticastPort = 5353;
         // IP header (20 bytes for IPv4; 40 bytes for IPv6) and the UDP header(8 bytes).
@@ -152,6 +157,23 @@ public static IEnumerable<IPAddress> GetIPAddresses()
                 .Select(u => u.Address);
         }
 
+        /// <summary>
+        ///   Get the link local IP addresses of the local machine.
+        /// </summary>
+        /// <returns>
+        ///   A sequence of IP addresses.
+        /// </returns>
+        /// <remarks>
+        ///   All IPv4 addresses are considered link local.
+        /// </remarks>
+        /// <seealso href="https://en.wikipedia.org/wiki/Link-local_address"/>
+        public static IEnumerable<IPAddress> GetLinkLocalAddresses()
+        {
+            return GetIPAddresses()
+                .Where(a => a.AddressFamily == AddressFamily.InterNetwork ||
+                    (a.AddressFamily == AddressFamily.InterNetworkV6 && a.IsIPv6LinkLocal));
+        }
+
         /// <summary>
         ///   Start the service.
         /// </summary>

src/ServiceProfile.cs

@@ -73,7 +73,7 @@ public ServiceProfile(string instanceName, string serviceName, ushort port, IEnu
                 Strings = { "txtvers=1" }
             });
 
-            foreach (var address in addresses ?? MulticastService.GetIPAddresses())
+            foreach (var address in addresses ?? MulticastService.GetLinkLocalAddresses())
             {
                 Resources.Add(AddressRecord.Create(HostName, address));
             }