From 0ecc5e8c96c235af265ab747d7345b363f94b1e4 Mon Sep 17 00:00:00 2001
From: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>
Date: Thu, 14 Mar 2024 09:00:47 +0100
Subject: [PATCH] Throttle people trying to connect to a full server. (#20972)

* Throttle people trying to connect to a full server.

To reduce spam/load on the server and connection logs table.

Players are forced to wait 30 seconds after getting denied for "server full", before they can try connecting again.

This code is an absolute nightmare mess. I tried to re-use the existing code for the redial timer but god everything here sucks so much.

Requires https://github.com/space-wizards/RobustToolbox/pull/4487

* Use new NetDisconnectMessage API instead.

* Add admin.bypass_max_players CVar.

Just something to help with debugging the player cap on dev, I don't expect this to ever be disabled on real servers.
---
 Content.Client/Launcher/LauncherConnecting.cs |  2 +
 .../Launcher/LauncherConnectingGui.xaml       |  4 -
 .../Launcher/LauncherConnectingGui.xaml.cs    | 82 ++++++++++++++-----
 .../Connection/ConnectionManager.cs           | 10 ++-
 Content.Shared/CCVar/CCVars.cs                | 14 ++++
 5 files changed, 86 insertions(+), 26 deletions(-)

diff --git a/Content.Client/Launcher/LauncherConnecting.cs b/Content.Client/Launcher/LauncherConnecting.cs
index 9625f9e31c..29b241ae5d 100644
--- a/Content.Client/Launcher/LauncherConnecting.cs
+++ b/Content.Client/Launcher/LauncherConnecting.cs
@@ -54,6 +54,7 @@ namespace Content.Client.Launcher
         public event Action<Page>? PageChanged;
         public event Action<string?>? ConnectFailReasonChanged;
         public event Action<ClientConnectionState>? ConnectionStateChanged;
+        public event Action<NetConnectFailArgs>? ConnectFailed;
 
         protected override void Startup()
         {
@@ -85,6 +86,7 @@ namespace Content.Client.Launcher
             }
             ConnectFailReason = args.Reason;
             CurrentPage = Page.ConnectFailed;
+            ConnectFailed?.Invoke(args);
         }
 
         private void OnConnectStateChanged(ClientConnectionState state)
diff --git a/Content.Client/Launcher/LauncherConnectingGui.xaml b/Content.Client/Launcher/LauncherConnectingGui.xaml
index 083e4ca871..3734fa5b3a 100644
--- a/Content.Client/Launcher/LauncherConnectingGui.xaml
+++ b/Content.Client/Launcher/LauncherConnectingGui.xaml
@@ -33,10 +33,6 @@
                         <Button Name="ReconnectButton" Text="{Loc 'connecting-reconnect'}"
                                 HorizontalAlignment="Center"
                                 VerticalExpand="True" VerticalAlignment="Bottom" />
-                        <Button Name="RedialButton" Text="{Loc 'connecting-redial'}"
-                                Disabled="True"
-                                HorizontalAlignment="Center"
-                                VerticalExpand="True" VerticalAlignment="Bottom" />
                     </BoxContainer>
                 </Control>
                 <Label Name="ConnectingAddress" StyleClasses="LabelSubText" HorizontalAlignment="Center" />
diff --git a/Content.Client/Launcher/LauncherConnectingGui.xaml.cs b/Content.Client/Launcher/LauncherConnectingGui.xaml.cs
index 79fba7c285..ac74ad7b60 100644
--- a/Content.Client/Launcher/LauncherConnectingGui.xaml.cs
+++ b/Content.Client/Launcher/LauncherConnectingGui.xaml.cs
@@ -9,7 +9,6 @@ using Robust.Client.UserInterface.XAML;
 using Robust.Shared.Configuration;
 using Robust.Shared.IoC;
 using Robust.Shared.Timing;
-using Robust.Shared.Localization;
 using Robust.Shared.Network;
 using Robust.Shared.Prototypes;
 using Robust.Shared.Random;
@@ -21,12 +20,15 @@ namespace Content.Client.Launcher
     {
         private const float RedialWaitTimeSeconds = 15f;
         private readonly LauncherConnecting _state;
+        private float _waitTime;
+
+        // Pressing reconnect will redial instead of simply reconnecting.
+        private bool _redial;
+
         private readonly IRobustRandom _random;
         private readonly IPrototypeManager _prototype;
         private readonly IConfigurationManager _cfg;
 
-        private float _redialWaitTime = RedialWaitTimeSeconds;
-
         public LauncherConnectingGui(LauncherConnecting state, IRobustRandom random,
             IPrototypeManager prototype, IConfigurationManager config)
         {
@@ -42,14 +44,8 @@ namespace Content.Client.Launcher
             Stylesheet = IoCManager.Resolve<IStylesheetManager>().SheetSpace;
 
             ChangeLoginTip();
-            ReconnectButton.OnPressed += _ => _state.RetryConnect();
-            // Redial shouldn't fail, but if it does, try a reconnect (maybe we're being run from debug)
-            RedialButton.OnPressed += _ =>
-            {
-                if (!_state.Redial())
-                    _state.RetryConnect();
-            };
-            RetryButton.OnPressed += _ => _state.RetryConnect();
+            ReconnectButton.OnPressed += ReconnectButtonPressed;
+            RetryButton.OnPressed += ReconnectButtonPressed;
             ExitButton.OnPressed += _ => _state.Exit();
 
             var addr = state.Address;
@@ -59,6 +55,7 @@ namespace Content.Client.Launcher
             state.PageChanged += OnPageChanged;
             state.ConnectFailReasonChanged += ConnectFailReasonChanged;
             state.ConnectionStateChanged += ConnectionStateChanged;
+            state.ConnectFailed += HandleDisconnectReason;
 
             ConnectionStateChanged(state.ConnectionState);
 
@@ -68,6 +65,19 @@ namespace Content.Client.Launcher
             LastNetDisconnectedArgsChanged(edim.LastNetDisconnectedArgs);
         }
 
+        // Just button, there's only one at once anyways :)
+        private void ReconnectButtonPressed(BaseButton.ButtonEventArgs args)
+        {
+            if (_redial)
+            {
+                // Redial shouldn't fail, but if it does, try a reconnect (maybe we're being run from debug)
+                if (_state.Redial())
+                    return;
+            }
+
+            _state.RetryConnect();
+        }
+
         private void ConnectFailReasonChanged(string? reason)
         {
             ConnectFailReason.SetMessage(reason == null
@@ -77,9 +87,30 @@ namespace Content.Client.Launcher
 
         private void LastNetDisconnectedArgsChanged(NetDisconnectedArgs? args)
         {
-            var redialFlag = args?.RedialFlag ?? false;
-            RedialButton.Visible = redialFlag;
-            ReconnectButton.Visible = !redialFlag;
+            HandleDisconnectReason(args);
+        }
+
+        private void HandleDisconnectReason(INetStructuredReason? reason)
+        {
+            if (reason == null)
+            {
+                _waitTime = 0;
+                _redial = false;
+            }
+            else
+            {
+                _redial = reason.RedialFlag;
+
+                if (reason.Message.Int32Of("delay") is { } delay)
+                {
+                    _waitTime = delay;
+                }
+                else if (_redial)
+                {
+                    _waitTime = RedialWaitTimeSeconds;
+                }
+
+            }
         }
 
         private void ChangeLoginTip()
@@ -108,16 +139,27 @@ namespace Content.Client.Launcher
         protected override void FrameUpdate(FrameEventArgs args)
         {
             base.FrameUpdate(args);
-            _redialWaitTime -= args.DeltaSeconds;
-            if (_redialWaitTime <= 0)
+
+            var button = _state.CurrentPage == LauncherConnecting.Page.ConnectFailed
+                ? RetryButton
+                : ReconnectButton;
+
+            _waitTime -= args.DeltaSeconds;
+            if (_waitTime <= 0)
             {
-                RedialButton.Disabled = false;
-                RedialButton.Text = Loc.GetString("connecting-redial");
+                button.Disabled = false;
+                var key = _redial
+                    ? "connecting-redial"
+                    : _state.CurrentPage == LauncherConnecting.Page.ConnectFailed
+                        ? "connecting-reconnect"
+                        : "connecting-retry";
+
+                button.Text = Loc.GetString(key);
             }
             else
             {
-                RedialButton.Disabled = true;
-                RedialButton.Text = Loc.GetString("connecting-redial-wait", ("time", _redialWaitTime.ToString("00.000")));
+                button.Disabled = true;
+                button.Text = Loc.GetString("connecting-redial-wait", ("time", _waitTime.ToString("00.000")));
             }
         }
 
diff --git a/Content.Server/Connection/ConnectionManager.cs b/Content.Server/Connection/ConnectionManager.cs
index 2fbc6f2359..1367cae82c 100644
--- a/Content.Server/Connection/ConnectionManager.cs
+++ b/Content.Server/Connection/ConnectionManager.cs
@@ -1,4 +1,5 @@
 using System.Collections.Immutable;
+using System.Text.Json.Nodes;
 using System.Threading.Tasks;
 using Content.Server.Database;
 using Content.Server.GameTicking;
@@ -77,7 +78,11 @@ namespace Content.Server.Connection
                 if (banHits is { Count: > 0 })
                     await _db.AddServerBanHitsAsync(id, banHits);
 
-                e.Deny(msg);
+                var properties = new Dictionary<string, object>();
+                if (reason == ConnectionDenyReason.Full)
+                    properties["delay"] = _cfg.GetCVar(CCVars.GameServerFullReconnectDelay);
+
+                e.Deny(new NetDenyReason(msg, properties));
             }
             else
             {
@@ -156,7 +161,8 @@ namespace Content.Server.Connection
             var wasInGame = EntitySystem.TryGet<GameTicker>(out var ticker) &&
                             ticker.PlayerGameStatuses.TryGetValue(userId, out var status) &&
                             status == PlayerGameStatus.JoinedGame;
-            if ((_plyMgr.PlayerCount >= _cfg.GetCVar(CCVars.SoftMaxPlayers) && adminData is null) && !wasInGame)
+            var adminBypass = _cfg.GetCVar(CCVars.AdminBypassMaxPlayers) && adminData != null;
+            if ((_plyMgr.PlayerCount >= _cfg.GetCVar(CCVars.SoftMaxPlayers) && !adminBypass) && !wasInGame)
             {
                 return (ConnectionDenyReason.Full, Loc.GetString("soft-player-cap-full"), null);
             }
diff --git a/Content.Shared/CCVar/CCVars.cs b/Content.Shared/CCVar/CCVars.cs
index c48a203c59..8a592d4b30 100644
--- a/Content.Shared/CCVar/CCVars.cs
+++ b/Content.Shared/CCVar/CCVars.cs
@@ -260,6 +260,13 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<int> SoftMaxPlayers =
             CVarDef.Create("game.soft_max_players", 30, CVar.SERVERONLY | CVar.ARCHIVE);
 
+        /// <summary>
+        /// If a player gets denied connection to the server,
+        /// how long they are forced to wait before attempting to reconnect.
+        /// </summary>
+        public static readonly CVarDef<int> GameServerFullReconnectDelay =
+            CVarDef.Create("game.server_full_reconnect_delay", 30, CVar.SERVERONLY);
+
         /// <summary>
         /// Whether or not panic bunker is currently enabled.
         /// </summary>
@@ -852,6 +859,13 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<float> AdminAfkTime =
             CVarDef.Create("admin.afk_time", 600f, CVar.SERVERONLY);
 
+        /// <summary>
+        /// If true, admins are able to connect even if
+        /// <see cref="SoftMaxPlayers"/> would otherwise block regular players.
+        /// </summary>
+        public static readonly CVarDef<bool> AdminBypassMaxPlayers =
+            CVarDef.Create("admin.bypass_max_players", true, CVar.SERVERONLY);
+
         /*
          * Explosions
          */
-- 
2.51.2