PaperMC/patches/server/0162-revert-serverside-behavior-of-keepalives.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shane Freeder <theboyetronic@gmail.com>
Date: Sun, 15 Oct 2017 00:29:07 +0100
Subject: [PATCH] revert serverside behavior of keepalives

This patch intends to bump up the time that a client has to reply to the
server back to 30 seconds as per pre 1.12.2, which allowed clients
more than enough time to reply potentially allowing them to be less
tempermental due to lag spikes on the network thread, e.g. that caused
by plugins that are interacting with netty.

We also add a system property to allow people to tweak how long the server
will wait for a reply. There is a compromise here between lower and higher
values, lower values will mean that dead connections can be closed sooner,
whereas higher values will make this less sensitive to issues such as spikes
from networking or during connections flood of chunk packets on slower clients,
 at the cost of dead connections being kept open for longer.

diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index 652703b1582e63148658a3a9d2604afa55674c23..cf42d59254f2786bfe8785249ad270d35996417a 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -221,9 +221,9 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Ser
     private final MinecraftServer server;
     public ServerPlayer player;
     private int tickCount;
-    private long keepAliveTime; @Deprecated private void setLastPing(long lastPing) { this.keepAliveTime = lastPing;}; @Deprecated private long getLastPing() { return this.keepAliveTime;}; // Paper - OBFHELPER
-    private boolean keepAlivePending; @Deprecated private void setPendingPing(boolean isPending) { this.keepAlivePending = isPending;}; @Deprecated private boolean isPendingPing() { return this.keepAlivePending;}; // Paper - OBFHELPER
-    private long keepAliveChallenge; @Deprecated private void setKeepAliveID(long keepAliveID) { this.keepAliveChallenge = keepAliveID;}; @Deprecated private long getKeepAliveID() {return this.keepAliveChallenge; };  // Paper - OBFHELPER
+    private long keepAliveTime = Util.getMillis();
+    private boolean keepAlivePending;
+    private long keepAliveChallenge;
     // CraftBukkit start - multithreaded fields
     private AtomicInteger chatSpamTickCount = new AtomicInteger();
     // CraftBukkit end
@@ -252,6 +252,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Ser
     private int aboveGroundVehicleTickCount;
     private int receivedMovePacketCount;
     private int knownMovePacketCount;
+    private static final long KEEPALIVE_LIMIT = Long.getLong("paper.playerconnection.keepalive", 30) * 1000; // Paper - provide property to set keepalive limit
 
     public ServerGamePacketListenerImpl(MinecraftServer server, Connection connection, ServerPlayer player) {
         this.server = server;
@@ -334,18 +335,25 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Ser
         }
 
         this.server.getProfiler().push("keepAlive");
-        long i = Util.getMillis();
-
-        if (i - this.keepAliveTime >= 25000L) { // CraftBukkit
-            if (this.keepAlivePending) {
-                this.disconnect(new TranslatableComponent("disconnect.timeout"));
-            } else {
+        // Paper Start - give clients a longer time to respond to pings as per pre 1.12.2 timings
+        // This should effectively place the keepalive handling back to "as it was" before 1.12.2
+        long currentTime = Util.getMillis();
+        long elapsedTime = currentTime - this.keepAliveTime;
+
+        if (this.keepAlivePending) {
+            if (!this.processedDisconnect && elapsedTime >= KEEPALIVE_LIMIT) { // check keepalive limit, don't fire if already disconnected
+                ServerGamePacketListenerImpl.LOGGER.warn("{} was kicked due to keepalive timeout!", this.player.getScoreboardName()); // more info
+                this.disconnect(new TranslatableComponent("disconnect.timeout", new Object[0]));
+            }
+        } else {
+            if (elapsedTime >= 15000L) { // 15 seconds
                 this.keepAlivePending = true;
-                this.keepAliveTime = i;
-                this.keepAliveChallenge = i;
+                this.keepAliveTime = currentTime;
+                this.keepAliveChallenge = currentTime;
                 this.send(new ClientboundKeepAlivePacket(this.keepAliveChallenge));
             }
         }
+        // Paper end
 
         this.server.getProfiler().pop();
         // CraftBukkit start