From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Spottedleaf <spottedleaf@spottedleaf.dev>
Date: Sun, 17 May 2020 23:47:33 -0700
Subject: [PATCH] Fix for large move vectors crashing server

Check movement distance also based on current position.

diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
index d622abf1013d500532cc6072e5cbb12248e983c2..563ae7355f4f4645d21f2fbd494a5b5656c5e664 100644
--- a/src/main/java/net/minecraft/server/PlayerConnection.java
+++ b/src/main/java/net/minecraft/server/PlayerConnection.java
@@ -369,19 +369,24 @@ public class PlayerConnection implements PacketListenerPlayIn {
 
             if (entity != this.player && entity.getRidingPassenger() == this.player && entity == this.r) {
                 WorldServer worldserver = this.player.getWorldServer();
-                double d0 = entity.locX();
-                double d1 = entity.locY();
-                double d2 = entity.locZ();
-                double d3 = packetplayinvehiclemove.getX();
-                double d4 = packetplayinvehiclemove.getY();
-                double d5 = packetplayinvehiclemove.getZ();
+                double d0 = entity.locX();double fromX = d0; // Paper - OBFHELPER
+                double d1 = entity.locY();double fromY = d1; // Paper - OBFHELPER
+                double d2 = entity.locZ();double fromZ = d2; // Paper - OBFHELPER
+                double d3 = packetplayinvehiclemove.getX();double toX = d3; // Paper - OBFHELPER
+                double d4 = packetplayinvehiclemove.getY();double toY = d4; // Paper - OBFHELPER
+                double d5 = packetplayinvehiclemove.getZ();double toZ = d5; // Paper - OBFHELPER
                 float f = packetplayinvehiclemove.getYaw();
                 float f1 = packetplayinvehiclemove.getPitch();
                 double d6 = d3 - this.s;
                 double d7 = d4 - this.t;
                 double d8 = d5 - this.u;
                 double d9 = entity.getMot().g();
-                double d10 = d6 * d6 + d7 * d7 + d8 * d8;
+                // Paper start - fix large move vectors killing the server
+                double currDeltaX = toX - fromX;
+                double currDeltaY = toY - fromY;
+                double currDeltaZ = toZ - fromZ;
+                double d10 = Math.max(d6 * d6 + d7 * d7 + d8 * d8, (currDeltaX * currDeltaX + currDeltaY * currDeltaY + currDeltaZ * currDeltaZ) - 1);
+                // Paper end - fix large move vectors killing the server
 
 
                 // CraftBukkit start - handle custom speeds and skipped ticks
@@ -1073,7 +1078,7 @@ public class PlayerConnection implements PacketListenerPlayIn {
                         double d2 = this.player.locZ();
                         double d3 = this.player.locY();
                         double d4 = packetplayinflying.a(this.player.locX());double toX = d4; // Paper - OBFHELPER
-                        double d5 = packetplayinflying.b(this.player.locY());
+                        double d5 = packetplayinflying.b(this.player.locY());double toY = d5; // Paper - OBFHELPER
                         double d6 = packetplayinflying.c(this.player.locZ());double toZ = d6; // Paper - OBFHELPER
                         float f = packetplayinflying.a(this.player.yaw);
                         float f1 = packetplayinflying.b(this.player.pitch);
@@ -1081,7 +1086,12 @@ public class PlayerConnection implements PacketListenerPlayIn {
                         double d8 = d5 - this.m;
                         double d9 = d6 - this.n;
                         double d10 = this.player.getMot().g();
-                        double d11 = d7 * d7 + d8 * d8 + d9 * d9;
+                        // Paper start - fix large move vectors killing the server
+                        double currDeltaX = toX - prevX;
+                        double currDeltaY = toY - prevY;
+                        double currDeltaZ = toZ - prevZ;
+                        double d11 = Math.max(d7 * d7 + d8 * d8 + d9 * d9, (currDeltaX * currDeltaX + currDeltaY * currDeltaY + currDeltaZ * currDeltaZ) - 1);
+                        // Paper end - fix large move vectors killing the server
 
                         if (this.player.isSleeping()) {
                             if (d11 > 1.0D) {
