From 11c291c105cc108c4bf12b15a2914e6afdd2d857 Mon Sep 17 00:00:00 2001
From: "Robin C. Ladiges" <rcl.git@blackpinguin.de>
Date: Thu, 23 Mar 2023 01:16:11 +0100
Subject: [PATCH] fix: actually working ban functionality

Changes:
- ignore new sockets from banned IP addresses way earlier.
- ignore all packets by banned profiles.

Intentionally keeping the connection open instead of d/c banned clients.
This is to prevent endless server logs due to automatically reconnecting clients.

Before:
Reconnecting clients aren't entering `ClientJoined` and therefore the d/c is only working on first connections.
Effectively banned clients got a d/c and then automatically reconnected again without getting a d/c again.
Therefore allowing them to play normally.
---
 Server/BanLists.cs |  1 +
 Server/Client.cs   |  1 +
 Server/Program.cs  |  3 ---
 Server/Server.cs   | 22 +++++++++++++++++++++-
 4 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/Server/BanLists.cs b/Server/BanLists.cs
index 7458389..6ce8fba 100644
--- a/Server/BanLists.cs
+++ b/Server/BanLists.cs
@@ -128,6 +128,7 @@ public static class BanLists {
 
 
     public static void Crash(Client user, bool permanent = false) {
+        user.Ignored = true;
         Task.Run(async () => {
             await user.Send(new ChangeStagePacket {
                 Id              = (permanent ? "$agogus/ban4lyfe" : "$among$us/cr4sh%"),
diff --git a/Server/Client.cs b/Server/Client.cs
index 5f3336f..9b7aa05 100644
--- a/Server/Client.cs
+++ b/Server/Client.cs
@@ -12,6 +12,7 @@ namespace Server;
 public class Client : IDisposable {
     public readonly ConcurrentDictionary<string, object?> Metadata = new ConcurrentDictionary<string, object?>(); // can be used to store any information about a player
     public bool Connected = false;
+    public bool Ignored = false;
     public CostumePacket? CurrentCostume = null; // required for proper client sync
     public string Name {
         get => Logger.Name;
diff --git a/Server/Program.cs b/Server/Program.cs
index 1ae5933..8bb3c7d 100644
--- a/Server/Program.cs
+++ b/Server/Program.cs
@@ -62,9 +62,6 @@ async Task LoadShines()
 await LoadShines();
 
 server.ClientJoined += (c, _) => {
-    if (BanLists.Enabled && BanLists.IsClientBanned(c)) {
-        throw new Exception($"Banned player attempted join: {c.Name}");
-    }
     c.Metadata["shineSync"] = new ConcurrentBag<int>();
     c.Metadata["loadedSave"] = false;
     c.Metadata["scenario"] = (byte?) 0;
diff --git a/Server/Server.cs b/Server/Server.cs
index cfb7091..0c01067 100644
--- a/Server/Server.cs
+++ b/Server/Server.cs
@@ -29,6 +29,11 @@ public class Server {
                 Socket socket = token.HasValue ? await serverSocket.AcceptAsync(token.Value) : await serverSocket.AcceptAsync();
                 socket.SetSocketOption(SocketOptionLevel.Tcp, SocketOptionName.NoDelay, true);
 
+                if (BanLists.Enabled && BanLists.IsIPv4Banned(((IPEndPoint) socket.RemoteEndPoint!).Address!)) {
+                    Logger.Warn($"Ignoring banned IPv4 address {socket.RemoteEndPoint}");
+                    continue;
+                }
+
                 Logger.Warn($"Accepted connection for client {socket.RemoteEndPoint}");
 
                 try {
@@ -64,7 +69,7 @@ public class Server {
 
     public static void FillPacket<T>(PacketHeader header, T packet, Memory<byte> memory) where T : struct, IPacket {
         Span<byte> data = memory.Span;
-        
+
         header.Serialize(data[..Constants.HeaderSize]);
         packet.Serialize(data[Constants.HeaderSize..]);
     }
@@ -167,6 +172,11 @@ public class Server {
                         break;
                 }
 
+                if (client.Ignored) {
+                    memory.Dispose();
+                    continue;
+                }
+
                 // connection initialization
                 if (first) {
                     first = false;
@@ -174,6 +184,16 @@ public class Server {
 
                     ConnectPacket connect = new ConnectPacket();
                     connect.Deserialize(memory.Memory.Span[packetRange]);
+
+                    if (BanLists.Enabled && BanLists.IsProfileBanned(header.Id)) {
+                        client.Id      = header.Id;
+                        client.Name    = connect.ClientName;
+                        client.Ignored = true;
+                        client.Logger.Warn($"Ignoring banned profile ID {header.Id}");
+                        memory.Dispose();
+                        continue;
+                    }
+
                     lock (Clients) {
                         if (Clients.Count(x => x.Connected) == Settings.Instance.Server.MaxPlayers) {
                             client.Logger.Error($"Turned away as server is at max clients");