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Fix infinite loop after cancelling PlayerVelocityEvent #13844

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Fix infinite loop after cancelling PlayerVelocityEvent #13844

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11 changes: 4 additions & 7 deletions paper-server/patches/sources/net/minecraft/server/level/ServerEntity.java.patch
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Original file line number Diff line number Diff line change
Expand Up @@ -61,15 +61,14 @@
Packet<ClientGamePacketListener> packet = null;
boolean pos = positionChanged || this.tickCount % 60 == 0;
boolean sentPosition = false;
@@ -218,6 +_,25 @@
@@ -218,7 +_,22 @@

this.tickCount++;
if (this.entity.hurtMarked) {
+ // CraftBukkit start - Create PlayerVelocity event
+ boolean cancelled = false;
+
+ if (this.entity instanceof ServerPlayer) {
+ org.bukkit.entity.Player player = (org.bukkit.entity.Player) this.entity.getBukkitEntity();
+ if (this.entity.getBukkitEntity() instanceof org.bukkit.entity.Player player) {
+ org.bukkit.util.Vector velocity = player.getVelocity();
+
+ org.bukkit.event.player.PlayerVelocityEvent event = new org.bukkit.event.player.PlayerVelocityEvent(player, velocity.clone());
Expand All @@ -79,14 +78,12 @@
+ player.setVelocity(event.getVelocity());
+ }
+ }
+
+ if (cancelled) {
+ return;
+ }
+ // CraftBukkit end
this.entity.hurtMarked = false;
+ if (cancelled) return; // Paper - if PlayerVelocity was cancel then we skip the sendToTrackingPlayersAndSelf
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@Lulu13022002 Lulu13022002 May 7, 2026

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I would rather not early return here just in case more stuff gets added later.

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@Doc94 Doc94 May 7, 2026

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So just remove this change?

this.synchronizer.sendToTrackingPlayersAndSelf(new ClientboundSetEntityMotionPacket(this.entity));
}
}
@@ -269,7 +_,10 @@
public void sendPairingData(final ServerPlayer player, final Consumer<Packet<ClientGamePacketListener>> broadcast) {
this.entity.updateDataBeforeSync();
Expand Down
12 changes: 11 additions & 1 deletion ...server/patches/sources/net/minecraft/world/entity/boss/enderdragon/EnderDragon.java.patch
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Original file line number Diff line number Diff line change
Expand Up @@ -152,7 +152,17 @@
if (destroyedBlock) {
BlockPos randomPos = new BlockPos(
x0 + this.random.nextInt(x1 - x0 + 1), y0 + this.random.nextInt(y1 - y0 + 1), z0 + this.random.nextInt(z1 - z0 + 1)
@@ -501,7 +_,15 @@
@@ -493,15 +_,23 @@
}

@Override
- public void knockback(final double power, final double xd, final double zd) {
+ public void knockback(final double power, final double xd, final double zd, final @Nullable Entity attacker, final io.papermc.paper.event.entity.EntityKnockbackEvent.Cause eventCause) { // Paper - knockback events
if (!this.phaseManager.getCurrentPhase().isSitting()) {
- super.knockback(power, xd, zd);
+ super.knockback(power, xd, zd, attacker, eventCause); // Paper - knockback events
}
}

@Override
public void kill(final ServerLevel level) {
Expand Down
22 changes: 9 additions & 13 deletions paper-server/patches/sources/net/minecraft/world/entity/player/Player.java.patch
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Original file line number Diff line number Diff line change
Expand Up @@ -291,7 +291,7 @@
return true;
} else {
return false;
@@ -1109,19 +_,40 @@
@@ -1109,18 +_,35 @@
public void causeExtraKnockback(final Entity entity, final float knockbackAmount, final Vec3 oldMovement) {
if (knockbackAmount > 0.0F) {
if (entity instanceof LivingEntity livingTarget) {
Expand All @@ -311,29 +311,25 @@
}

if (entity instanceof ServerPlayer && entity.hurtMarked) {
+ // CraftBukkit start - Add Velocity Event
+ boolean cancelled = false;
- ((ServerPlayer)entity).connection.send(new ClientboundSetEntityMotionPacket(entity));
+ // Paper start - Add Velocity Event
+ org.bukkit.entity.Player player = (org.bukkit.entity.Player) entity.getBukkitEntity();
+ org.bukkit.util.Vector velocity = org.bukkit.craftbukkit.util.CraftVector.toBukkit(oldMovement);
+
+ org.bukkit.event.player.PlayerVelocityEvent event = new org.bukkit.event.player.PlayerVelocityEvent(player, velocity.clone());
+ this.level().getCraftServer().getPluginManager().callEvent(event);
+
+ if (event.isCancelled()) {
+ cancelled = true;
entity.hurtMarked = false;
+ if (!event.callEvent()) {
+ return;
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+ } else if (!velocity.equals(event.getVelocity())) {
+ player.setVelocity(event.getVelocity());
+ }
+
+ if (!cancelled) {
((ServerPlayer)entity).connection.send(new ClientboundSetEntityMotionPacket(entity));
entity.hurtMarked = false;
+ // Paper end
+ ((ServerPlayer)entity).connection.send(new ClientboundSetEntityMotionPacket(entity));
+ // entity.hurtMarked = false; // Paper - move before PlayerVelocityEvent call
entity.setDeltaMovement(oldMovement);
+ }
+ // CraftBukkit end
}
}

@@ -1142,8 +_,11 @@
&& !(nearby instanceof ArmorStand armorStand && armorStand.isMarker())
&& this.distanceToSqr(nearby) < 9.0) {
Expand Down
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