From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: "Sofiane H. Djerbi" <46628754+kugge@users.noreply.github.com>
Date: Fri, 31 Mar 2023 01:52:44 +0300
Subject: [PATCH] Alternate Keepalive

Don't kick players because 1 keepalive is lost.
This patch is from Purpur.

diff --git a/src/main/java/dev/kaiijumc/kaiiju/KaiijuConfig.java b/src/main/java/dev/kaiijumc/kaiiju/KaiijuConfig.java
index ab08e11f13921163b8ff1ff51ff9e9b86d2b47c7..b42a3466f145a92608c8746fd4beb529b4a60b01 100644
--- a/src/main/java/dev/kaiijumc/kaiiju/KaiijuConfig.java
+++ b/src/main/java/dev/kaiijumc/kaiiju/KaiijuConfig.java
@@ -200,8 +200,10 @@ public class KaiijuConfig {
     }
     
     public static boolean sendNullEntityPackets = true;
+    public static boolean alternateKeepAlive = false;
 
     private static void networkSettings() {
         sendNullEntityPackets = getBoolean("network.send-null-entity-packets", sendNullEntityPackets);
+        alternateKeepAlive = getBoolean("network.alternate-keepalive", alternateKeepAlive);
     }
 }
diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
index b2feaea169fa9d3977c3dfdfdf3dea9283f5d854..1ab0d3e0653028b7d93177c28c1f532d8b10b1b1 100644
--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
@@ -263,6 +263,7 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
     private long keepAliveTime = Util.getMillis();
     private boolean keepAlivePending;
     private long keepAliveChallenge;
+    private it.unimi.dsi.fastutil.longs.LongList keepAlives = new it.unimi.dsi.fastutil.longs.LongArrayList(); // Kaiiju
     // CraftBukkit start - multithreaded fields
     private final AtomicInteger chatSpamTickCount = new AtomicInteger();
     private final java.util.concurrent.atomic.AtomicInteger tabSpamLimiter = new java.util.concurrent.atomic.AtomicInteger(); // Paper - configurable tab spam limits
@@ -355,6 +356,20 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
         long currentTime = Util.getMillis();
         long elapsedTime = currentTime - this.keepAliveTime;
 
+        // Kaiiju start
+        if (dev.kaiijumc.kaiiju.KaiijuConfig.alternateKeepAlive) {
+            if (elapsedTime >= 1000L) { // 1 second
+                if (!processedDisconnect && keepAlives.size() * 1000L >= KEEPALIVE_LIMIT) {
+                    LOGGER.warn("{} was kicked due to keepalive timeout!", this.player.getScoreboardName());
+                    disconnect(Component.translatable("disconnect.timeout"), org.bukkit.event.player.PlayerKickEvent.Cause.TIMEOUT);
+                } else {
+                    keepAliveTime = currentTime; // hijack this field for 1 second intervals
+                    keepAlives.add(currentTime); // currentTime is ID
+                    send(new ClientboundKeepAlivePacket(currentTime));
+                }
+            }
+        } else
+        // Kaiiju end
         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
@@ -3523,6 +3538,16 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
 
     @Override
     public void handleKeepAlive(ServerboundKeepAlivePacket packet) {
+        // Kaiiju start
+        if (dev.kaiijumc.kaiiju.KaiijuConfig.alternateKeepAlive) {
+            long id = packet.getId();
+            if (keepAlives.size() > 0 && keepAlives.contains(id)) {
+                int ping = (int) (Util.getMillis() - id);
+                player.latency = (player.latency * 3 + ping) / 4;
+                keepAlives.clear(); // we got a valid response, lets roll with it and forget the rest
+            }
+        } else
+        // Kaiiju end
         //PacketUtils.ensureRunningOnSameThread(packet, this, this.player.serverLevel()); // CraftBukkit // Paper - This shouldn't be on the main thread
         if (this.keepAlivePending && packet.getId() == this.keepAliveChallenge) {
             int i = (int) (Util.getMillis() - this.keepAliveTime);