fix(1640): don't crash on dns failure (AscensionGameDev#2013)

Author: pandinocoder

Intersect.Client/Interface/Interface.cs

@@ -1,8 +1,4 @@
-using System.Collections.Generic;
-using System.Linq;
-
 using Intersect.Client.Core;
-using Intersect.Client.Framework.File_Management;
 using Intersect.Client.Framework.GenericClasses;
 using Intersect.Client.Framework.Graphics;
 using Intersect.Client.Framework.Gwen.Control;
@@ -22,8 +18,12 @@ namespace Intersect.Client.Interface
     public static partial class Interface
     {
 
-        public static readonly List<KeyValuePair<string, string>> MsgboxErrors =
-            new List<KeyValuePair<string, string>>();
+        public static readonly List<KeyValuePair<string, string>> MsgboxErrors = new();
+
+        public static void ShowError(string message, string? header = default)
+        {
+            MsgboxErrors.Add(new KeyValuePair<string, string>(header ?? string.Empty, message));
+        }
 
         public static ErrorHandler ErrorMsgHandler;
 

Intersect.Client/Localization/Strings.cs

@@ -1,8 +1,3 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Linq;
 using System.Reflection;
 using Intersect.Configuration;
 using Intersect.Enums;
@@ -917,6 +912,9 @@ public partial struct Errors
             public static LocalizedString lostconnection =
                 @"Lost connection to the game server. Please make sure you're connected to the internet and try again!";
 
+            public static LocalizedString HostNotFound =
+                @"DNS resolution error, please report this to the game administrator.";
+
         }
 
         public partial struct Words

Intersect.Client/MonoGame/Network/MonoSocket.cs

@@ -1,6 +1,7 @@
 using System.Collections.Concurrent;
 using System.Diagnostics.CodeAnalysis;
 using System.Net;
+using System.Net.Sockets;
 using System.Resources;
 using Intersect.Client.Framework.Network;
 using Intersect.Configuration;
@@ -11,6 +12,7 @@
 using Intersect.Client.Core;
 using Intersect.Client.General;
 using Intersect.Client.Interface.Menu;
+using Intersect.Client.Localization;
 using Intersect.Network.Packets.Unconnected.Client;
 using Intersect.Rsa;
 
@@ -94,6 +96,7 @@ public INetwork? Network
         private string? _lastHost;
         private int? _lastPort;
         private IPEndPoint? _lastEndpoint;
+        private static HashSet<string> UnresolvableHostNames = new();
 
         internal MonoSocket(IClientContext context)
         {
@@ -103,6 +106,12 @@ internal MonoSocket(IClientContext context)
         private bool TryResolveEndPoint([NotNullWhen(true)] out IPEndPoint? endPoint)
         {
             var currentHost = ClientConfiguration.Instance.Host;
+            if (UnresolvableHostNames.Contains(currentHost))
+            {
+                endPoint = default;
+                return false;
+            }
+
             if (!string.Equals(_lastHost, currentHost))
             {
                 _lastHost = currentHost;
@@ -128,17 +137,33 @@ private bool TryResolveEndPoint([NotNullWhen(true)] out IPEndPoint? endPoint)
                 return true;
             }
 
-            var address = Dns.GetHostAddresses(_lastHost).FirstOrDefault();
-            var port = _lastPort;
-            if (address == default || !port.HasValue)
+            try
+            {
+                var address = Dns.GetHostAddresses(_lastHost).FirstOrDefault();
+                var port = _lastPort;
+                if (address == default || !port.HasValue)
+                {
+                    endPoint = default;
+                    return false;
+                }
+
+                endPoint = new IPEndPoint(address, port.Value);
+                _lastEndpoint = endPoint;
+                return true;
+            }
+            catch (SocketException socketException)
             {
+                if (socketException.SocketErrorCode != SocketError.HostNotFound)
+                {
+                    throw;
+                }
+
+                UnresolvableHostNames.Add(_lastHost);
+                Interface.Interface.ShowError(Strings.Errors.HostNotFound);
+                Log.Error(socketException, $"Failed to resolve host: '{_lastHost}'");
                 endPoint = default;
                 return false;
             }
-
-            endPoint = new IPEndPoint(address, port.Value);
-            _lastEndpoint = endPoint;
-            return true;
         }
 
         public override void Connect(string host, int port)
@@ -178,6 +203,10 @@ public static bool AddPacketToQueue(IConnection connection, IPacket packet)
             return true;
         }
 
+        private volatile bool _resolvingHost;
+
+
+
         public override void Update()
         {
             while (PacketQueue.TryDequeue(out KeyValuePair<IConnection, IPacket> dequeued))
@@ -192,21 +221,39 @@ public override void Update()
                 // ReSharper disable once InvertIf
                 if (_nextServerStatusPing <= now)
                 {
-                    if (TryResolveEndPoint(out var serverEndpoint))
-                    {
-                        var network = Network;
-                        if (network == default)
-                        {
-                            Log.Info("No network created to poll for server status.");
-                        }
-                        else
-                        {
-                            network.SendUnconnected(serverEndpoint, new ServerStatusRequestPacket());
-                        }
-                    }
-                    else
+                    if (!_resolvingHost)
                     {
-                        Log.Info($"Unable to resolve '{_lastHost}:{_lastPort}'");
+                        _resolvingHost = true;
+                        Task.Run(
+                            () =>
+                            {
+                                try
+                                {
+                                    if (TryResolveEndPoint(out var serverEndpoint))
+                                    {
+                                        var network = Network;
+                                        if (network == default)
+                                        {
+                                            Log.Info("No network created to poll for server status.");
+                                        }
+                                        else
+                                        {
+                                            network.SendUnconnected(serverEndpoint, new ServerStatusRequestPacket());
+                                        }
+                                    }
+                                    else if (!UnresolvableHostNames.Contains(_lastHost))
+                                    {
+                                        Log.Info($"Unable to resolve '{_lastHost}:{_lastPort}'");
+                                    }
+                                }
+                                catch (Exception exception)
+                                {
+                                    Log.Error(exception);
+                                }
+
+                                _resolvingHost = false;
+                            }
+                        );
                     }
 
                     if (MainMenu.LastNetworkStatusChangeTime + ServerStatusPingInterval < now)