Simplify binding code

This also removes the capability of choosing the network interface by its primary IP address, since we've never needed it and the code got too confusing.

src/Abc.Zebus.Tests/Transport/ZmqTransportTests.cs

@@ -270,16 +270,15 @@ public void should_support_peer_endpoint_modifications()
             var senderTransport = CreateAndStartZmqTransport();
 
             var receivedMessages = new ConcurrentBag<TransportMessage>();
-            var receiverTransport = CreateAndStartZmqTransport(onMessageReceived: receivedMessages.Add);
-            var receiver = receiverTransport.GetPeer();
+            var receiverTransport1 = CreateAndStartZmqTransport(onMessageReceived: receivedMessages.Add);
+            var receiverTransport2 = CreateAndStartZmqTransport(onMessageReceived: receivedMessages.Add);
+            var receiver = receiverTransport1.GetPeer();
 
             senderTransport.Send(new FakeCommand(0).ToTransportMessage(), new[] { receiver });
             Wait.Until(() => receivedMessages.Count == 1, 2.Seconds());
 
-            var newEndPoint = "tcp://127.0.0.1:" + TcpUtil.GetRandomUnusedPort();
-            receiverTransport.Stop();
-            receiverTransport = CreateAndStartZmqTransport(newEndPoint, receivedMessages.Add);
-            receiver.EndPoint = receiverTransport.InboundEndPoint;
+            receiverTransport1.Stop();
+            receiver.EndPoint = receiverTransport2.InboundEndPoint;
 
             senderTransport.Send(new FakeCommand(0).ToTransportMessage(), new[] { receiver });
             Wait.Until(() => receivedMessages.Count == 2, 2.Seconds(), "unable to receive message");

src/Abc.Zebus/Transport/ZmqEndPoint.cs

@@ -1,12 +1,25 @@
-namespace Abc.Zebus.Transport;
+using System;
+using System.Text.RegularExpressions;
+
+namespace Abc.Zebus.Transport;
 
 internal readonly struct ZmqEndPoint
 {
+    private static readonly Regex _endpointRegex = new(@"^tcp://(?<host>\*|[0-9a-zA-Z_.-]+):(?<port>\*|[0-9]+)/?$", RegexOptions.IgnoreCase);
+
     private readonly string? _value;
 
     public ZmqEndPoint(string? value)
         => _value = value;
 
     public override string ToString()
         => _value ?? "tcp://*:*";
+
+    public static (string host, string port) Parse(string? endpoint)
+    {
+        var match = _endpointRegex.Match(endpoint ?? string.Empty);
+        return match.Success
+            ? (match.Groups["host"].Value, match.Groups["port"].Value)
+            : throw new InvalidOperationException($"Invalid endpoint: {endpoint}");
+    }
 }

src/Abc.Zebus/Transport/ZmqInboundSocket.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Net;
-using System.Text.RegularExpressions;
 using Abc.Zebus.Serialization.Protobuf;
 using Abc.Zebus.Transport.Zmq;
 using Microsoft.Extensions.Logging;
@@ -11,9 +10,6 @@ internal class ZmqInboundSocket : IDisposable
 {
     private static readonly ILogger _logger = ZebusLogManager.GetLogger(typeof(ZmqInboundSocket));
 
-    private static readonly Regex _endpointRegex = new(@"^tcp://(?<host>\*|[0-9a-zA-Z_.-]+):(?<port>\*|[0-9]+)/?$", RegexOptions.IgnoreCase);
-    private static readonly Regex _ipRegex = new(@"^(?:[0-9]+\.){3}[0-9]+$");
-
     private readonly ZmqContext _context;
     private readonly ZmqEndPoint _configuredEndPoint;
     private readonly ZmqSocketOptions _options;
@@ -32,11 +28,12 @@ public ZmqEndPoint Bind()
     {
         _socket = CreateSocket();
 
-        var (configuredHost, configuredPort) = ParseEndpoint(_configuredEndPoint.ToString());
+        var (configuredHost, configuredPort) = ZmqEndPoint.Parse(_configuredEndPoint.ToString());
+
+        _socket.Bind($"tcp://*:{configuredPort}");
 
-        _socket.Bind($"tcp://{(_ipRegex.IsMatch(configuredHost) ? configuredHost : "*")}:{configuredPort}");
+        var (boundHost, boundPort) = ZmqEndPoint.Parse(_socket.GetOptionString(ZmqSocketOption.LAST_ENDPOINT));
 
-        var (boundHost, boundPort) = ParseEndpoint(_socket.GetOptionString(ZmqSocketOption.LAST_ENDPOINT));
         if (boundHost == "0.0.0.0")
         {
             // Use the hostname from the config when one is provided, or the FQDN otherwise
@@ -49,14 +46,6 @@ public ZmqEndPoint Bind()
         _logger.LogInformation($"Socket bound, Inbound EndPoint: {socketEndPoint}");
 
         return socketEndPoint;
-
-        static (string host, string port) ParseEndpoint(string endpoint)
-        {
-            var match = _endpointRegex.Match(endpoint);
-            return match.Success
-                ? (match.Groups["host"].Value, match.Groups["port"].Value)
-                : throw new InvalidOperationException($"Invalid endpoint: {endpoint}");
-        }
     }
 
     public void Dispose()