feat: config support for how many max channels a player can register

Author: SpigotRCE

api/src/main/java/com/velocitypowered/api/proxy/config/ProxyConfig.java

@@ -203,4 +203,11 @@ default boolean isKickOnCommandRateLimit() {
   default boolean isKickOnTabCompleteRateLimit() {
     return getKickAfterRateLimitedTabCompletes() > 0;
   }
+
+  /**
+   * Get the channel register limit a client can register.
+   *
+   * @return the channel limit a client can register
+   */
+  int getChannelRegisterLimit();
 }

proxy/src/main/java/com/velocitypowered/proxy/config/VelocityConfiguration.java

@@ -375,6 +375,11 @@ public int getKickAfterRateLimitedTabCompletes() {
     return advanced.getKickAfterRateLimitedTabCompletes();
   }
 
+  @Override
+  public int getChannelRegisterLimit() {
+    return advanced.getChannelRegisterLimit();
+  }
+
   @Override
   public boolean isForwardCommandsIfRateLimited() {
     return advanced.isForwardCommandsIfRateLimited();
@@ -773,6 +778,8 @@ private static class Advanced {
     private int tabCompleteRateLimit = 50;
     @Expose
     private int kickAfterRateLimitedTabCompletes = 10;
+    @Expose
+    private int channelRegisterLimit = 128;
 
     private Advanced() {
     }
@@ -891,6 +898,10 @@ public int getKickAfterRateLimitedTabCompletes() {
       return kickAfterRateLimitedTabCompletes;
     }
 
+    public int getChannelRegisterLimit() {
+      return channelRegisterLimit;
+    }
+
     @Override
     public String toString() {
       return "Advanced{"

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -299,16 +299,16 @@ public boolean handle(PluginMessagePacket packet) {
     // Handling edge case when packet with FML client handshake (state COMPLETE)
     // arrives after JoinGame packet from destination server
     VelocityServerConnection serverConn =
-        (player.getConnectedServer() == null
-            && packet.getChannel().equals(
-            LegacyForgeConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL))
-            ? player.getConnectionInFlight() : player.getConnectedServer();
+            (player.getConnectedServer() == null
+                    && packet.getChannel().equals(
+                    LegacyForgeConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL))
+                    ? player.getConnectionInFlight() : player.getConnectedServer();
 
     MinecraftConnection backendConn = serverConn != null ? serverConn.getConnection() : null;
     if (serverConn != null && backendConn != null) {
       if (backendConn.getState() != StateRegistry.PLAY) {
         logger.warn("A plugin message was received while the backend server was not "
-            + "ready. Channel: {}. Packet discarded.", packet.getChannel());
+                + "ready. Channel: {}. Packet discarded.", packet.getChannel());
       } else if (PluginMessageUtil.isRegister(packet)) {
         List<String> channels = PluginMessageUtil.getChannels(packet);
         player.getClientsideChannels().addAll(channels);
@@ -321,8 +321,8 @@ public boolean handle(PluginMessagePacket packet) {
           }
         }
         server.getEventManager()
-            .fireAndForget(
-                new PlayerChannelRegisterEvent(player, ImmutableList.copyOf(channelIdentifiers)));
+                .fireAndForget(
+                        new PlayerChannelRegisterEvent(player, ImmutableList.copyOf(channelIdentifiers)));
         backendConn.write(packet.retain());
       } else if (PluginMessageUtil.isUnregister(packet)) {
         player.getClientsideChannels().removeAll(PluginMessageUtil.getChannels(packet));
@@ -349,7 +349,7 @@ public boolean handle(PluginMessagePacket packet) {
           if (id == null) {
             // We don't have any plugins listening on this channel, process the packet now.
             if (!player.getPhase().consideredComplete() || !serverConn.getPhase()
-                .consideredComplete()) {
+                    .consideredComplete()) {
               // The client is trying to send messages too early. This is primarily caused by mods,
               // but further aggravated by Velocity. To work around these issues, we will queue any
               // non-FML handshake messages to be sent once the FML handshake has completed or the
@@ -368,9 +368,9 @@ public boolean handle(PluginMessagePacket packet) {
             server.getEventManager().fire(event).thenAcceptAsync(pme -> {
               if (pme.getResult().isAllowed()) {
                 PluginMessagePacket message = new PluginMessagePacket(packet.getChannel(),
-                    Unpooled.wrappedBuffer(copy));
+                        Unpooled.wrappedBuffer(copy));
                 if (!player.getPhase().consideredComplete() || !serverConn.getPhase()
-                    .consideredComplete()) {
+                        .consideredComplete()) {
                   // We're still processing the connection (see above), enqueue the packet for now.
                   loginPluginMessages.add(message.retain());
                 } else {

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -145,7 +145,6 @@
 public class ConnectedPlayer implements MinecraftConnectionAssociation, Player, KeyIdentifiable,
     VelocityInboundConnection {
 
-  private static final int MAX_CLIENTSIDE_PLUGIN_CHANNELS = 1024;
   private static final PlainTextComponentSerializer PASS_THRU_TRANSLATE =
       PlainTextComponentSerializer.builder().flattener(TranslatableMapper.FLATTENER).build();
   static final PermissionProvider DEFAULT_PERMISSIONS = s -> PermissionFunction.ALWAYS_UNDEFINED;
@@ -208,7 +207,7 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player,
     this.permissionFunction = PermissionFunction.ALWAYS_UNDEFINED;
     this.connectionPhase = connection.getType().getInitialClientPhase();
     this.onlineMode = onlineMode;
-    this.clientsideChannels = CappedSet.create(MAX_CLIENTSIDE_PLUGIN_CHANNELS);
+    this.clientsideChannels = CappedSet.create(server.getConfiguration().getChannelRegisterLimit());
 
     if (connection.getProtocolVersion().noLessThan(ProtocolVersion.MINECRAFT_1_19_3)) {
       this.tabList = new VelocityTabList(this);

proxy/src/main/resources/com/velocitypowered/proxy/l10n/messages.properties

@@ -64,4 +64,5 @@ velocity.command.send-usage=/send <player> <server>
 # Kick
 velocity.kick.shutdown=Proxy shutting down.
 velocity.kick.command-rate-limit=You are sending too many commands too quickly.
-velocity.kick.tab-complete-rate-limit=You are sending too many tab complete requests too quickly.
+velocity.kick.tab-complete-rate-limit=You are sending too many tab complete requests too quickly.
+velocity.kick.channel-register-limit=You attempted to register too many channels.

proxy/src/main/resources/default-velocity.toml

@@ -177,6 +177,9 @@ tab-complete-rate-limit = 10
 # Setting this to 0 or lower will disable this feature.
 kick-after-rate-limited-tab-completes = 0
 
+# How many channels a player can (un)register
+channel-register-limit = 128
+
 [query]
 # Whether to enable responding to GameSpy 4 query responses or not.
 enabled = false