From 671df77c1f5f2328a7359b9ef2f4254287c2e184 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Sun, 12 Aug 2018 08:06:50 -0400
Subject: [PATCH] Forward the keep-alive packet directly onto the client.
This improves anti-cheat compatibility.
---
.../backend/BackendPlaySessionHandler.java | 5 +--
.../client/ClientPlaySessionHandler.java | 32 +++++--------------
2 files changed, 11 insertions(+), 26 deletions(-)
diff --git a/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java b/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
index b0784b179..bd6ad4d77 100644
--- a/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
+++ b/proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java
@@ -27,8 +27,9 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
ClientPlaySessionHandler playerHandler =
(ClientPlaySessionHandler) connection.getProxyPlayer().getConnection().getSessionHandler();
if (packet instanceof KeepAlive) {
- // Forward onto the server
- connection.getMinecraftConnection().write(packet);
+ // Forward onto the player
+ playerHandler.setLastPing(((KeepAlive) packet).getRandomId());
+ connection.getProxyPlayer().getConnection().write(packet);
} else if (packet instanceof Disconnect) {
Disconnect original = (Disconnect) packet;
connection.getProxyPlayer().handleConnectionException(connection.getServerInfo(), original);
diff --git a/proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java b/proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java
index c1451ef9e..549c8fb46 100644
--- a/proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java
+++ b/proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java
@@ -25,7 +25,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
private static final int MAX_PLUGIN_CHANNELS = 128;
private final ConnectedPlayer player;
- private ScheduledFuture<?> pingTask;
private long lastPing = -1;
private boolean spawned = false;
private final List<UUID> serverBossBars = new ArrayList<>();
@@ -36,30 +35,15 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
this.player = player;
}
- @Override
- public void activated() {
- EventLoop loop = player.getConnection().getChannel().eventLoop();
- pingTask = loop.scheduleAtFixedRate(this::ping, 5, 15, TimeUnit.SECONDS);
- }
-
- private void ping() {
- long randomId = ThreadLocalRandom.current().nextInt();
- lastPing = randomId;
- KeepAlive keepAlive = new KeepAlive();
- keepAlive.setRandomId(randomId);
- player.getConnection().write(keepAlive);
- }
-
@Override
public void handle(MinecraftPacket packet) {
if (packet instanceof KeepAlive) {
KeepAlive keepAlive = (KeepAlive) packet;
if (keepAlive.getRandomId() != lastPing) {
- throw new IllegalStateException("Client sent invalid keepAlive; expected " + lastPing + ", got " + keepAlive.getRandomId());
+ // The last keep alive we got was probably from a different server. Let's ignore it, and hope the next
+ // ping is alright.
+ return;
}
-
- // Do not forward the packet to the player's server, because we handle pings for all servers already.
- return;
}
if (packet instanceof ClientSettings) {
@@ -132,11 +116,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
@Override
public void disconnected() {
player.teardown();
-
- if (pingTask != null && !pingTask.isCancelled()) {
- pingTask.cancel(false);
- pingTask = null;
- }
}
@Override
@@ -149,6 +128,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
}
public void handleBackendJoinGame(JoinGame joinGame) {
+ lastPing = Long.MIN_VALUE; // reset last ping
if (!spawned) {
// nothing special to do here
spawned = true;
@@ -244,4 +224,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
public EntityIdRemapper getIdRemapper() {
return idRemapper;
}
+
+ public void setLastPing(long lastPing) {
+ this.lastPing = lastPing;
+ }
}