Version 1.1: also cancel attribute updates

Author: Beaness

.idea/gradle.xml

@@ -26,6 +26,9 @@ Doing this fix should make hit slowdown **less latency** dependant.
 
 **Warning:** This plugin will make hit slowdown happen completely different to most servers (To compare: minemen.club has fixed this issue partly by not doing setSprinting(false) internally, it still has the other issue, of when the client sends START_SPRINTING / STOP_SPRINTING)
 
+## Attribute
+Since version 1.1 BetterSlowdown also cancels "useless" attribute packets which apply / remove the sprint modifier, this is handled client side and the server should not try to override this. 
+
 ## Dependencies
 
 This plugin uses, and depends on [PacketEvents](https://github.com/retrooper/packetevents)

.idea/vcs.xml

@@ -1,20 +1,27 @@
 package me.beanes.betterslowdown;
 
 import com.github.retrooper.packetevents.PacketEvents;
+import com.github.retrooper.packetevents.event.PacketListenerCommon;
 import com.github.retrooper.packetevents.event.PacketListenerPriority;
 import me.beanes.betterslowdown.listener.FilterListener;
 import org.bukkit.plugin.java.JavaPlugin;
 
 public class BetterSlowdown extends JavaPlugin {
     private FallbackMode mode = FallbackMode.SPRINT;
+    private boolean alwaysAddSprint = false;
+    private PacketListenerCommon listener;
 
     public FallbackMode getMode() {
         return mode;
     }
 
+    public boolean isAlwaysAddSprint() {
+        return alwaysAddSprint;
+    }
+
     @Override
     public void onLoad() {
-        PacketEvents.getAPI().getEventManager().registerListener(new FilterListener(this), PacketListenerPriority.LOWEST);
+        listener = PacketEvents.getAPI().getEventManager().registerListener(new FilterListener(this), PacketListenerPriority.LOWEST);
     }
 
     @Override
@@ -23,11 +30,18 @@ public void onEnable() {
 
         try {
             mode = FallbackMode.valueOf(getConfig().getString("mode").toUpperCase());
+            alwaysAddSprint = getConfig().getBoolean("always-add-sprint");
         } catch (Exception ex) {
             mode = FallbackMode.SERVER;
             getLogger().info("Failed to load config due to error");
         }
 
         getLogger().info("Slowdown fallback mode is set to " + mode);
+        getLogger().info("Always add sprint is set to " + alwaysAddSprint);
+    }
+
+    @Override
+    public void onDisable() {
+        PacketEvents.getAPI().getEventManager().unregisterListener(listener);
     }
 }

README.md

@@ -7,20 +7,26 @@
 import com.github.retrooper.packetevents.protocol.packettype.PacketType;
 import com.github.retrooper.packetevents.protocol.player.User;
 import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerEntityMetadata;
+import com.github.retrooper.packetevents.wrapper.play.server.WrapperPlayServerUpdateAttributes;
 import me.beanes.betterslowdown.BetterSlowdown;
 import me.beanes.betterslowdown.FallbackMode;
 
 import java.util.HashMap;
 import java.util.Iterator;
 import java.util.Map;
+import java.util.UUID;
 
 public class FilterListener implements PacketListener {
+    private static final UUID SPRINT_MODIFIER_UUID = UUID.fromString("662A6B8D-DA3E-4C1C-8813-96EA6097278D");
+    private static final WrapperPlayServerUpdateAttributes.PropertyModifier SPRINT_MODIFIER = new WrapperPlayServerUpdateAttributes.PropertyModifier(SPRINT_MODIFIER_UUID, 0.30000001192092896D, WrapperPlayServerUpdateAttributes.PropertyModifier.Operation.MULTIPLY_TOTAL);
     private final BetterSlowdown plugin;
     private final ThreadLocal<Map<User, Byte>> lastUsefulBitmaskThreadLocal;
+    private final ThreadLocal<Map<User, Double>> lastSpeedThreadLocal;
 
     public FilterListener(BetterSlowdown plugin) {
         this.plugin = plugin;
         this.lastUsefulBitmaskThreadLocal = ThreadLocal.withInitial(HashMap::new);
+        this.lastSpeedThreadLocal = ThreadLocal.withInitial(HashMap::new);
     }
 
 
@@ -53,7 +59,7 @@ public void onPacketSend(PacketSendEvent event) {
 
                             if (plugin.getMode() != FallbackMode.SERVER) {
                                 if (plugin.getMode() == FallbackMode.SPRINT) {
-                                    data.setValue((byte) ((byte) data.getValue() | 0x08)); // Rewrite with sprinting=true
+                                    data.setValue((byte) ((byte) data.getValue() | 0x08)); // Rewrite with sprinting = true
                                 } else if (plugin.getMode() == FallbackMode.NO_SPRINT) {
                                     data.setValue((byte) ((byte) data.getValue() & ~0x08)); // Rewrite with sprinting = false
                                 }
@@ -75,11 +81,53 @@ public void onPacketSend(PacketSendEvent event) {
                     }
                 }
             }
+        } else if (event.getPacketType() == PacketType.Play.Server.UPDATE_ATTRIBUTES) {
+            WrapperPlayServerUpdateAttributes wrapper = new WrapperPlayServerUpdateAttributes(event);
+            User user = event.getUser();
+
+            if (wrapper.getEntityId() == user.getEntityId()) {
+                for (WrapperPlayServerUpdateAttributes.Property snapshot : wrapper.getProperties()) {
+                    if (snapshot.getAttribute().getName().getKey().equals("movement_speed")) {
+                        // Calculate the movement speed without sprint
+                        boolean exists = snapshot.getModifiers().removeIf(modifier -> modifier.getUUID().equals(SPRINT_MODIFIER_UUID));
+                        if (exists) {
+                            snapshot.setDirty();
+                        }
+
+                        double speed = snapshot.calcValue();
+
+                        Map<User, Double> lastSpeed = lastSpeedThreadLocal.get();
+
+                        if (lastSpeed.getOrDefault(user, -1.0D) == speed) {
+                            // Cancel this attribute packet as it only changes the sprint attribute
+                            event.setCancelled(true);
+                        } else {
+                            // Update the speed
+                            lastSpeed.put(user, speed);
+
+                            if (exists) {
+                                snapshot.addModifier(SPRINT_MODIFIER); // Re-add the modifier if packetevents is on default re-encode
+                            } else if (plugin.isAlwaysAddSprint()) {
+                                // TODO: check if the player is "allowed" to sprint, keep food value, and check START_SPRINTING and STOP_SPRINTING to prevent omnisprint?
+                                snapshot.addModifier(SPRINT_MODIFIER);
+                                event.markForReEncode(true);
+                            }
+                        }
+                    }
+                }
+            }
+        } else if (event.getPacketType() == PacketType.Play.Server.RESPAWN) {
+            User user = event.getUser();
+
+            // Reset last as the entity is recreated
+            this.lastUsefulBitmaskThreadLocal.get().remove(user);
+            this.lastSpeedThreadLocal.get().remove(user);
         }
     }
 
     @Override
     public void onUserDisconnect(UserDisconnectEvent event) {
         this.lastUsefulBitmaskThreadLocal.get().remove(event.getUser());
+        this.lastSpeedThreadLocal.get().remove(event.getUser());
     }
 }

src/main/java/me/beanes/betterslowdown/BetterSlowdown.java

@@ -14,4 +14,9 @@
 #   SERVER - this mode will just use the server sent value
 #   SPRINT - always set sprinting true, causes the client to force the hit slowdown (if the client hit) for a single tick when it receives the updated metadata
 #   NO_SPRINT - always set sprinting false, causes the client to not do the hit slowdown (if the client hit) even when its sprinting when it receives the updated metadata
-mode: NO_SPRINT
+mode: SPRINT
+
+# Should the server always apply the sprint attribute when attributes are being overridden by server (and the plugin can't cancel it due to speed change)
+# This is useful for HCF servers when you get speed 3 / speed 2, and your sprint suddenly disappears
+# This is still in beta as this can cause the player to sprint while not having the food for it and it can cause omnisprint
+always-add-sprint: false

src/main/java/me/beanes/betterslowdown/listener/FilterListener.java

@@ -1,7 +1,7 @@
 name: BetterSlowdown
-version: '${version}'
+version: 1.1
 main: me.beanes.betterslowdown.BetterSlowdown
 author: Beanes
 description: Fixes server/network issues related to hit slowdown
 depend:
-  - packetevents
+  - packetevents