Kick on ban for entire server group (#28649)

* Start work on PostgresNotificationManager
Implement initial version of init and listening code

* Finish implementing PostgresNotificationManager
Implement ban insert trigger

* Implement ignoring notifications if the ban was from the same server

* Address reviews

* Fixes and refactorings

Fix typo in migration SQL

Pull new code in BanManager out into its own partial file.

Unify logic to kick somebody with that when a new ban is placed directly on the server.

New bans are now checked against all parameters (IP, HWID) instead of just user ID.

Extracted SQLite ban matching code into a new class so that it can mostly be re-used by the ban notification code. No copy-paste here.

Database notifications are now not implicitly sent to the main thread, this means basic checks will happen in the thread pool beforehand.

Bans without user ID are now sent to servers. Bans are rate limited to avoid undue work from mass ban imports, beyond the rate limit they are dropped.

Improved error handling and logging for the whole system.

Matching bans against connected players requires knowing their ban exemption flags. These are now cached when the player connects.

ServerBanDef now has exemption flags, again to allow matching full ban details for ban notifications.

Made database notifications a proper struct type to reduce copy pasting a tuple.

Remove copy pasted connection string building code by just... passing the string into the constructor.

Add lock around _notificationHandlers just in case.

Fixed postgres connection wait not being called in a loop and therefore spamming LISTEN commands for every received notification.

Added more error handling and logging to notification listener.

Removed some copy pasting from SQLite database layer too while I was at it because god forbid we expect anybody else to do all the work in this project.

Sorry Julian

---------

Co-authored-by: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>

Content.Server/Database/ServerDbBase.cs

@@ -28,6 +28,8 @@ namespace Content.Server.Database
     {
         private readonly ISawmill _opsLog;
 
+        public event Action<DatabaseNotification>? OnNotificationReceived;
+
         /// <param name="opsLog">Sawmill to trace log database operations to.</param>
         public ServerDbBase(ISawmill opsLog)
         {
@@ -425,13 +427,16 @@ namespace Content.Server.Database
             await db.DbContext.SaveChangesAsync();
         }
 
-        protected static async Task<ServerBanExemptFlags?> GetBanExemptionCore(DbGuard db, NetUserId? userId)
+        protected static async Task<ServerBanExemptFlags?> GetBanExemptionCore(
+            DbGuard db,
+            NetUserId? userId,
+            CancellationToken cancel = default)
         {
             if (userId == null)
                 return null;
 
             var exemption = await db.DbContext.BanExemption
-                .SingleOrDefaultAsync(e => e.UserId == userId.Value.UserId);
+                .SingleOrDefaultAsync(e => e.UserId == userId.Value.UserId, cancellationToken: cancel);
 
             return exemption?.Flags;
         }
@@ -462,11 +467,11 @@ namespace Content.Server.Database
             await db.DbContext.SaveChangesAsync();
         }
 
-        public async Task<ServerBanExemptFlags> GetBanExemption(NetUserId userId)
+        public async Task<ServerBanExemptFlags> GetBanExemption(NetUserId userId, CancellationToken cancel)
         {
-            await using var db = await GetDb();
+            await using var db = await GetDb(cancel);
 
-            var flags = await GetBanExemptionCore(db, userId);
+            var flags = await GetBanExemptionCore(db, userId, cancel);
             return flags ?? ServerBanExemptFlags.None;
         }
 
@@ -1677,5 +1682,15 @@ INSERT INTO player_round (players_id, rounds_id) VALUES ({players[player]}, {id}
 
             public abstract ValueTask DisposeAsync();
         }
+
+        protected void NotificationReceived(DatabaseNotification notification)
+        {
+            OnNotificationReceived?.Invoke(notification);
+        }
+
+        public virtual void Shutdown()
+        {
+
+        }
     }
 }