From 0b3a792a513baa2262b6ca6262f1b423162a8927 Mon Sep 17 00:00:00 2001
From: Nassim Jahnke <nassim@njahnke.dev>
Date: Sun, 18 Aug 2024 15:13:51 +0200
Subject: [PATCH] Properly read unused light data in 1.17->1.16 Some servers
 for some reason do this

---
 .../rewriter/BlockItemPacketRewriter1_17.java      | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_17to1_16_4/rewriter/BlockItemPacketRewriter1_17.java b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_17to1_16_4/rewriter/BlockItemPacketRewriter1_17.java
index eee094a4..b315d92d 100644
--- a/common/src/main/java/com/viaversion/viabackwards/protocol/v1_17to1_16_4/rewriter/BlockItemPacketRewriter1_17.java
+++ b/common/src/main/java/com/viaversion/viabackwards/protocol/v1_17to1_16_4/rewriter/BlockItemPacketRewriter1_17.java
@@ -247,13 +247,14 @@ public final class BlockItemPacketRewriter1_17 extends BackwardsItemRewriter<Cli
 
             private void writeLightArrays(PacketWrapper wrapper, BitSet bitMask, int cutBitMask,
                                           int startFromSection, int sectionHeight) {
-                wrapper.read(Types.VAR_INT); // Length - throw it away
-
+                int packetContentsLength = wrapper.read(Types.VAR_INT);
+                int read = 0;
                 List<byte[]> light = new ArrayList<>();
 
                 // Remove lower bounds
                 for (int i = 0; i < startFromSection; i++) {
                     if (bitMask.get(i)) {
+                        read++;
                         wrapper.read(Types.BYTE_ARRAY_PRIMITIVE);
                     }
                 }
@@ -261,6 +262,7 @@ public final class BlockItemPacketRewriter1_17 extends BackwardsItemRewriter<Cli
                 // Add the important 18 sections
                 for (int i = 0; i < 18; i++) {
                     if (isSet(cutBitMask, i)) {
+                        read++;
                         light.add(wrapper.read(Types.BYTE_ARRAY_PRIMITIVE));
                     }
                 }
@@ -268,6 +270,14 @@ public final class BlockItemPacketRewriter1_17 extends BackwardsItemRewriter<Cli
                 // Remove upper bounds
                 for (int i = startFromSection + 18; i < sectionHeight + 2; i++) {
                     if (bitMask.get(i)) {
+                        read++;
+                        wrapper.read(Types.BYTE_ARRAY_PRIMITIVE);
+                    }
+                }
+
+                if (read != packetContentsLength) {
+                    // Read the rest if the server for some reason sends more than are actually consumed
+                    for (int i = read; i < packetContentsLength; i++) {
                         wrapper.read(Types.BYTE_ARRAY_PRIMITIVE);
                     }
                 }