allow automatically assign listening tcp port

Author: Jacques Kang

src/JKang.IpcServiceFramework.Server/Tcp/TcpIpcServiceEndpoint.cs

@@ -12,19 +12,26 @@ public class TcpIpcServiceEndpoint<TContract> : IpcServiceEndpoint<TContract>
         where TContract : class
     {
         private readonly ILogger<TcpIpcServiceEndpoint<TContract>> _logger;
+
+        public int Port { get; private set; }
+
         private readonly TcpListener _listener;
 
-        public TcpIpcServiceEndpoint(String name, IServiceProvider serviceProvider, IPAddress ipEndpoint, int port)
+        public TcpIpcServiceEndpoint(String name, IServiceProvider serviceProvider, IPAddress ipEndpoint, int port = 0)
             : base(name, serviceProvider)
         {
             _listener = new TcpListener(ipEndpoint, port);
             _logger = serviceProvider.GetService<ILogger<TcpIpcServiceEndpoint<TContract>>>();
+            Port = port;
         }
 
         public override Task ListenAsync(CancellationToken cancellationToken = default(CancellationToken))
         {
             _listener.Start();
 
+            // If port is dynamically assigned, get the port number after start
+            Port = ((IPEndPoint)_listener.LocalEndpoint).Port;
+
             cancellationToken.Register(() =>
             {
                 _logger.LogDebug($"Shutting down tcp endpoint '{Name}'...");
@@ -35,7 +42,7 @@ public TcpIpcServiceEndpoint(String name, IServiceProvider serviceProvider, IPAd
             {
                 try
                 {
-                    _logger.LogDebug($"Listening tcp endpoint '{Name}'...");
+                    _logger.LogDebug($"Listening tcp endpoint '{Name}' on port {Port}...");
                     while (true)
                     {
                         TcpClient client = await _listener.AcceptTcpClientAsync();

src/JKang.IpcServiceFramework.Server/Tcp/TcpIpcServiceHostBuilderExtensions.cs

@@ -5,6 +5,13 @@ namespace JKang.IpcServiceFramework
 {
     public static class TcpIpcServiceHostBuilderExtensions
     {
+        public static IpcServiceHostBuilder AddTcpEndpoint<TContract>(this IpcServiceHostBuilder builder,
+            string name, IPAddress ipEndpoint)
+            where TContract : class
+        {
+            return builder.AddEndpoint(new TcpIpcServiceEndpoint<TContract>(name, builder.ServiceProvider, ipEndpoint));
+        }
+
         public static IpcServiceHostBuilder AddTcpEndpoint<TContract>(this IpcServiceHostBuilder builder,
             string name, IPAddress ipEndpoint, int port)
             where TContract : class