Alert shared connections (#29405)

* add admin alert for active shared connections

* update wizden config

* review

Content.Server/Connection/ConnectionManager.cs

@@ -1,7 +1,9 @@
 using System.Collections.Immutable;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Text.Json.Nodes;
 using System.Threading.Tasks;
+using Content.Server.Chat.Managers;
 using Content.Server.Database;
 using Content.Server.GameTicking;
 using Content.Server.Preferences.Managers;
@@ -10,7 +12,9 @@ using Content.Shared.GameTicking;
 using Content.Shared.Players.PlayTimeTracking;
 using Robust.Server.Player;
 using Robust.Shared.Configuration;
+using Robust.Shared.Enums;
 using Robust.Shared.Network;
+using Robust.Shared.Player;
 using Robust.Shared.Timing;
 
 /*
@@ -50,6 +54,7 @@ namespace Content.Server.Connection
         [Dependency] private readonly ServerDbEntryManager _serverDbEntry = default!;
         [Dependency] private readonly IGameTiming _gameTiming = default!;
         [Dependency] private readonly ILogManager _logManager = default!;
+        [Dependency] private readonly IChatManager _chatManager = default!;
 
         private readonly Dictionary<NetUserId, TimeSpan> _temporaryBypasses = [];
         private ISawmill _sawmill = default!;
@@ -60,6 +65,7 @@ namespace Content.Server.Connection
 
             _netMgr.Connecting += NetMgrOnConnecting;
             _netMgr.AssignUserIdCallback = AssignUserIdCallback;
+            _plyMgr.PlayerStatusChanged += PlayerStatusChanged;
             // Approval-based IP bans disabled because they don't play well with Happy Eyeballs.
             // _netMgr.HandleApprovalCallback = HandleApproval;
         }
@@ -128,6 +134,42 @@ namespace Content.Server.Connection
             }
         }
 
+        private async void PlayerStatusChanged(object? sender, SessionStatusEventArgs args)
+        {
+            if (args.NewStatus == SessionStatus.Connected)
+            {
+                AdminAlertIfSharedConnection(args.Session);
+            }
+        }
+
+        private void AdminAlertIfSharedConnection(ICommonSession newSession)
+        {
+            var playerThreshold = _cfg.GetCVar(CCVars.AdminAlertMinPlayersSharingConnection);
+            if (playerThreshold < 0)
+                return;
+
+            var addr = newSession.Channel.RemoteEndPoint.Address;
+
+            var otherConnectionsFromAddress = _plyMgr.Sessions.Where(session =>
+                    session.Status is SessionStatus.Connected or SessionStatus.InGame
+                    && session.Channel.RemoteEndPoint.Address.Equals(addr)
+                    && session.UserId != newSession.UserId)
+                .ToList();
+
+            var otherConnectionCount = otherConnectionsFromAddress.Count;
+            if (otherConnectionCount + 1 < playerThreshold) // Add one for the total, not just others, using the address
+                return;
+
+            var username = newSession.Name;
+            var otherUsernames = string.Join(", ",
+                otherConnectionsFromAddress.Select(session => session.Name));
+
+            _chatManager.SendAdminAlert(Loc.GetString("admin-alert-shared-connection",
+                ("player", username),
+                ("otherCount", otherConnectionCount),
+                ("otherList", otherUsernames)));
+        }
+
         /*
          * TODO: Jesus H Christ what is this utter mess of a function
          * TODO: Break this apart into is constituent steps.

Content.Shared/CCVar/CCVars.cs

@@ -832,6 +832,15 @@ namespace Content.Shared.CCVar
         public static readonly CVarDef<bool> ServerBanErasePlayer =
             CVarDef.Create("admin.server_ban_erase_player", false, CVar.ARCHIVE | CVar.SERVER | CVar.REPLICATED);
 
+        /// <summary>
+        ///     Minimum players sharing a connection required to create an alert. -1 to disable the alert.
+        /// </summary>
+        /// <remarks>
+        ///     If you set this to 0 or 1 then it will alert on every connection, so probably don't do that.
+        /// </remarks>
+        public static readonly CVarDef<int> AdminAlertMinPlayersSharingConnection =
+            CVarDef.Create("admin.alert.min_players_sharing_connection", -1, CVar.SERVERONLY);
+
         /// <summary>
         ///     Minimum explosion intensity to create an admin alert message. -1 to disable the alert.
         /// </summary>

Resources/ConfigPresets/WizardsDen/wizardsDen.toml

@@ -36,6 +36,7 @@ limit = 10.0
 see_own_notes = true
 deadmin_on_join = true
 new_player_threshold = 600
+alert.min_players_sharing_connection = 2
 
 [worldgen]
 enabled = true

Resources/Locale/en-US/administration/admin-alerts.ftl

@@ -0,0 +1 @@
+admin-alert-shared-connection = {$player} is sharing a connection with {$otherCount} connected player(s): {$otherList}