fix 1.7.10 chunk reading + tests

This only happens with custom servers, vanilla does not use the single chunk packet, only the batched chunk packet (always 5 afaik). This was seen on via backwards. Reported by Couleur on matrix.

Author: Bixilon

src/integration-test/kotlin/de/bixilon/minosoft/protocol/packets/s2c/play/chunk/ChunkS2CPTest.kt

@@ -1,6 +1,6 @@
 /*
  * Minosoft
- * Copyright (C) 2020-2025 Moritz Zwerger
+ * Copyright (C) 2020-2026 Moritz Zwerger
  *
  * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
  *
@@ -120,6 +120,30 @@ class ChunkS2CPTest {
         assertEquals(blocks[4]!![4, 3, 4]!!.block.identifier, MinecraftBlocks.STONE)
     }
 
+    fun `viabackwards 1_8_9`() {
+        val packet = read("viabackwards_1_8_9", "1.8.9", dimension = DimensionProperties(light = true, skyLight = true, minY = 0, height = 256))
+        assertEquals(packet.position, ChunkPosition(5843 - 1))
+        val blocks = packet.prototype.blocks
+        assertNotNull(blocks); blocks!!
+
+        assertEquals(blocks[4]!![0, 0, 0]!!.block.identifier, MinecraftBlocks.STONE)
+        assertEquals(blocks[5]!![129]!!.block.identifier, MinecraftBlocks.TERRACOTTA)
+        assertEquals(blocks[5]!![205]!!.block.identifier, MinecraftBlocks.TERRACOTTA)
+        assertEquals(blocks[6]!![361]!!.block.identifier, MinecraftBlocks.COBBLESTONE_WALL)
+    }
+
+    fun `viabackwards 1_7_10`() {
+        val packet = read("viabackwards_1_7_10", "1.7.10", dimension = DimensionProperties(light = true, skyLight = true, minY = 0, height = 256))
+        assertEquals(packet.position, ChunkPosition(5843 - 1))
+        val blocks = packet.prototype.blocks
+        assertNotNull(blocks); blocks!!
+
+        assertEquals(blocks[4]!![0, 0, 0]!!.block.identifier, MinecraftBlocks.STONE)
+        assertEquals(blocks[5]!![129]!!.block.identifier, MinecraftBlocks.TERRACOTTA)
+        assertEquals(blocks[5]!![205]!!.block.identifier, MinecraftBlocks.TERRACOTTA)
+        assertEquals(blocks[6]!![361]!!.block.identifier, MinecraftBlocks.COBBLESTONE_WALL)
+    }
+
 //    fun benchmark() {
 //        val start = now()
 //        for (i in 0 until 10000) {

src/integration-test/resources/packets/chunk/viabackwards_1_7_10.bin

@@ -1,6 +1,6 @@
 /*
  * Minosoft
- * Copyright (C) 2020-2025 Moritz Zwerger
+ * Copyright (C) 2020-2026 Moritz Zwerger
  *
  * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
  *
@@ -58,7 +58,7 @@ class ChunkS2CP(buffer: PlayInByteBuffer) : PlayS2CPacket {
     val prototype: ChunkData = ChunkData()
     var action: ChunkAction = ChunkAction.CREATE
         private set
-    private lateinit var readingData: ChunkReadingData
+    private var readingData: ChunkReadingData? = null
 
     init {
         val dimension = buffer.session.world.dimension
@@ -67,15 +67,12 @@ class ChunkS2CP(buffer: PlayInByteBuffer) : PlayS2CPacket {
             action = if (buffer.readBoolean()) ChunkAction.CREATE else ChunkAction.UPDATE
         }
         if (buffer.versionId < V_14W26A) { // ToDo
-            val sectionBitMask = BitSet.valueOf(buffer.readByteArray(2))
-            val addBitMask = BitSet.valueOf(buffer.readByteArray(2))
+            val sectionBitMask = buffer.readLegacyBitSet(2)
+            val addBitMask = buffer.readLegacyBitSet(2)
 
             // decompress chunk data
-            val decompressed: PlayInByteBuffer = if (buffer.versionId < V_14W28A) {
-                PlayInByteBuffer(buffer.readByteArray(buffer.readInt()).decompress(), buffer.session)
-            } else {
-                buffer
-            }
+            val decompressed = if (buffer.versionId < V_14W28A) PlayInByteBuffer(buffer.readByteArray(buffer.readInt()).decompress(), buffer.session) else buffer
+
             val chunkData = ChunkPacketUtil.readChunkPacket(decompressed, dimension, sectionBitMask, addBitMask, action == ChunkAction.CREATE, dimension.skyLight)
             if (chunkData == null) {
                 action = ChunkAction.UNLOAD
@@ -175,7 +172,7 @@ class ChunkS2CP(buffer: PlayInByteBuffer) : PlayS2CPacket {
     }
 
     private fun ChunkReadingData.readChunkData() {
-        val chunkData = if (readingData.buffer.versionId < V_21W37A) ChunkPacketUtil.readChunkPacket(buffer, dimension, sectionBitMask!!, null, action == ChunkAction.CREATE, dimension.skyLight) else ChunkPacketUtil.readPaletteChunk(buffer, dimension, null, complete = true, skylight = false)
+        val chunkData = if (buffer.versionId < V_21W37A) ChunkPacketUtil.readChunkPacket(buffer, dimension, sectionBitMask!!, null, action == ChunkAction.CREATE, dimension.skyLight) else ChunkPacketUtil.readPaletteChunk(buffer, dimension, null, complete = true, skylight = false)
         ALLOCATOR.free(data)
         if (chunkData == null) {
             action = ChunkAction.UNLOAD
@@ -185,7 +182,7 @@ class ChunkS2CP(buffer: PlayInByteBuffer) : PlayS2CPacket {
     }
 
     fun parse() {
-        this.readingData.readChunkData()
+        this.readingData?.readChunkData()
     }
 
     override fun handle(session: PlaySession) {

src/integration-test/resources/packets/chunk/viabackwards_1_8_9.bin

@@ -1,6 +1,6 @@
 /*
  * Minosoft
- * Copyright (C) 2020-2025 Moritz Zwerger
+ * Copyright (C) 2020-2026 Moritz Zwerger
  *
  * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
  *
@@ -36,6 +36,6 @@ class SignTextS2CP(buffer: PlayInByteBuffer) : PlayS2CPacket {
     }
 
     override fun log(reducedLog: Boolean) {
-        Log.log(LogMessageType.NETWORK_IN, level = LogLevels.VERBOSE) { "Sign text (position=$position, lines=$lines" }
+        Log.log(LogMessageType.NETWORK_IN, level = LogLevels.VERBOSE) { "Sign text (position=$position, lines=${lines.contentToString()}" }
     }
 }

src/main/java/de/bixilon/minosoft/protocol/packets/s2c/play/block/chunk/ChunkS2CP.kt

@@ -1,6 +1,6 @@
 /*
  * Minosoft
- * Copyright (C) 2020-2025 Moritz Zwerger
+ * Copyright (C) 2020-2026 Moritz Zwerger
  *
  * This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
  *
@@ -240,10 +240,10 @@ object KUtil {
     }
 
     fun PlayInByteBuffer.dump(name: String) {
-        val pointer = offset
+        val offset = this@dump.offset
         this.offset = data.offset
         val data = readRemaining()
-        this.offset = pointer
+        this.offset = offset
 
         val path = "/home/moritz/${name}_${Versions.getById(this.versionId)?.name?.replace(".", "_")}.bin"
         val stream = FileOutputStream(path)