использованы костыли для предотвращения "рваных" пакетоов

Пакеты иногда могут приходить не полностью, а кусками. Раньше из-за этого
возникали ошибки декода пакетов, у которых данные обрывались.

core/src/main/java/mc/core/network/NetInputStream.java

@@ -22,6 +22,7 @@ public abstract class NetInputStream {
     public abstract short readShort();
     public abstract int readInt();
     public abstract int readVarInt();
+    public abstract int readVarInt(int[] countReadBytes);
     public abstract long readLong();
     public abstract float readFloat();
     public abstract double readDouble();

proto_1.12.2/src/main/java/mc/core/network/proto_1_12_2/NetInputStream_p340.java

@@ -13,25 +13,31 @@ import java.util.UUID;
 @Slf4j
 public abstract class NetInputStream_p340 extends NetInputStream {
     @Override
-    public int readVarInt() {
+    public int readVarInt(int[] countReadBytes) {
         int numRead = 0;
         int result = 0;
         byte read;
         do {
+            if ((numRead+1) > 5) {
+                log.warn("VarInt is too big");
+                break;
+            }
             read = readByte();
             int value = (read & 0b01111111);
             result |= (value << (7 * numRead));
 
             numRead++;
-            if (numRead > 5) {
-                log.warn("VarInt is too big");
-                break;
-            }
         } while ((read & 0b10000000) != 0);
 
+        if (countReadBytes != null && countReadBytes.length == 1) countReadBytes[0] = numRead;
         return result;
     }
 
+    @Override
+    public int readVarInt() {
+        return readVarInt(null);
+    }
+
     @Override
     public String readString() {
         int size = readVarInt();

proto_1.12.2_netty/src/main/java/mc/core/network/proto_1_12_2/netty/PacketDecoder.java

@@ -1,12 +1,8 @@
-/*
- * DmitriyMX <dimon550@gmail.com>
- * 2018-06-10
- */
 package mc.core.network.proto_1_12_2.netty;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;
-import io.netty.handler.codec.ByteToMessageDecoder;
+import io.netty.handler.codec.ReplayingDecoder;
 import lombok.extern.slf4j.Slf4j;
 import mc.core.network.CSPacket;
 import mc.core.network.NetInputStream;
@@ -18,7 +14,9 @@ import java.util.List;
 import static mc.core.network.proto_1_12_2.netty.NettyServer.ATTR_STATE;
 
 @Slf4j
-public class PacketDecoder extends ByteToMessageDecoder {
+public class PacketDecoder extends ReplayingDecoder<CSPacket> {
+    private int[] countReadBytes = new int[]{0};
+
     @Override
     public void channelActive(ChannelHandlerContext ctx) throws Exception {
         ctx.channel().attr(ATTR_STATE).set(State.HANDSHAKE);
@@ -33,27 +31,25 @@ public class PacketDecoder extends ByteToMessageDecoder {
 
     @Override
     protected void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
-        log.debug("ByteBuf readableBytes: {}", in.readableBytes());
-
         State state = ctx.channel().attr(ATTR_STATE).get();
         NetInputStream netStream = new WrapperNetInputStream(in);
 
         int packetSize = netStream.readVarInt();
         log.debug("Packet size: {}", packetSize);
-        int rb = in.readableBytes();
+        int leftDataPacket = packetSize;
 
-        int packetId = netStream.readVarInt();
+        int packetId = netStream.readVarInt(countReadBytes);
         String hexPacketId = Integer.toHexString(packetId).toUpperCase();
         if (hexPacketId.length() == 1) hexPacketId = "0" + hexPacketId;
         log.debug("Packet id: 0x{}", hexPacketId);
-        rb = rb - in.readableBytes();
+        leftDataPacket = leftDataPacket - countReadBytes[0];
 
         Class<? extends CSPacket> packetClass = state.getClientSidePacket(packetId);
         if (packetClass == null) {
             log.warn("Unknown packet: {}:0x{}", state.name(), hexPacketId);
-            in.skipBytes(in.readableBytes());
+            in.skipBytes(leftDataPacket);
         } else {
-            netStream.setDataSize(packetSize - rb);
+            netStream.setDataSize(leftDataPacket);
             CSPacket packet = packetClass.newInstance();
             try {
                 packet.readSelf(netStream);
@@ -62,7 +58,7 @@ public class PacketDecoder extends ByteToMessageDecoder {
             } catch (Exception e) {
                 log.warn("Known packet: {}:{}. But throw exception. See debug log.", state.name(), packet.getClass().getSimpleName());
                 log.debug("Read packet", e);
-                in.skipBytes(in.readableBytes());
+                in.skipBytes(leftDataPacket);
             }
         }
     }