Remove PluginMessage slicing for now.

This was causing leak issues and needs to be reimplemented. If anyone's
willing to undertake the work, I will gladly accept the PR!

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -45,7 +45,6 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
             connection.getProxyPlayer().getConnection().write(packet);
         } else if (packet instanceof PluginMessage) {
             PluginMessage pm = (PluginMessage) packet;
-            try {
             if (!canForwardPluginMessage(pm)) {
                 return;
             }
@@ -55,14 +54,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
                 return;
             }
 
-                // we'll decrement this twice: once when writing to the server, once just below this block,
-                // and once in the MinecraftConnection (since this is a slice)
-                pm.getData().retain();
-
             connection.getProxyPlayer().getConnection().write(pm);
-            } finally {
-                pm.getData().release();
-            }
         } else {
             // Just forward the packet on. We don't have anything to handle at this time.
             if (packet instanceof ScoreboardTeam ||

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -191,8 +191,6 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
     public void handleClientPluginMessage(PluginMessage packet) {
         logger.info("Got client plugin message packet {}", packet);
-
-        try {
         if (packet.getChannel().equals("REGISTER") || packet.getChannel().equals("minecraft:register")) {
             List<String> actuallyRegistered = new ArrayList<>();
             List<String> channels = PluginMessageUtil.getChannels(packet);
@@ -226,11 +224,7 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         }
 
         // We're going to forward on the original packet.
-            packet.getData().retain();
         player.getConnectedServer().getMinecraftConnection().write(packet);
-        } finally {
-            ReferenceCountUtil.release(packet.getData());
-        }
     }
 
     public void handleServerScoreboardPacket(MinecraftPacket packet) {

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/PluginMessage.java

@@ -8,7 +8,7 @@ import io.netty.buffer.ByteBufUtil;
 
 public class PluginMessage implements MinecraftPacket {
     private String channel;
-    private ByteBuf data;
+    private byte[] data;
 
     public String getChannel() {
         return channel;
@@ -18,11 +18,11 @@ public class PluginMessage implements MinecraftPacket {
         this.channel = channel;
     }
 
-    public ByteBuf getData() {
+    public byte[] getData() {
         return data;
     }
 
-    public void setData(ByteBuf data) {
+    public void setData(byte[] data) {
         this.data = data;
     }
 
@@ -37,7 +37,8 @@ public class PluginMessage implements MinecraftPacket {
     @Override
     public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
         this.channel = ProtocolUtils.readString(buf);
-        this.data = buf.readRetainedSlice(buf.readableBytes());
+        this.data = new byte[buf.readableBytes()];
+        buf.readBytes(data);
     }
 
     @Override

proxy/src/main/java/com/velocitypowered/proxy/protocol/util/PluginMessageUtil.java

@@ -27,7 +27,7 @@ public enum PluginMessageUtil {
                 message.getChannel().equals("minecraft:register") ||
                 message.getChannel().equals("minecraft:unregister"),
                 "Unknown channel type " + message.getChannel());
-        String channels = message.getData().toString(StandardCharsets.UTF_8);
+        String channels = new String(message.getData(), StandardCharsets.UTF_8);
         return ImmutableList.copyOf(channels.split("\0"));
     }
 
@@ -37,15 +37,7 @@ public enum PluginMessageUtil {
 
         PluginMessage message = new PluginMessage();
         message.setChannel(channel);
-
-        ByteBuf data = Unpooled.buffer();
-        for (String s : channels) {
-            ByteBufUtil.writeUtf8(data, s);
-            data.writeByte(0);
-        }
-        data.writerIndex(data.writerIndex() - 1);
-
-        message.setData(data);
+        message.setData(String.join("\0", channels).getBytes(StandardCharsets.UTF_8));
         return message;
     }
 
@@ -53,13 +45,20 @@ public enum PluginMessageUtil {
         Preconditions.checkNotNull(message, "message");
         Preconditions.checkArgument(isMCBrand(message), "message is not a MC Brand plugin message");
 
+        byte[] rewrittenData;
         ByteBuf rewrittenBuf = Unpooled.buffer();
-        String currentBrand = ProtocolUtils.readString(message.getData());
+        try {
+            String currentBrand = ProtocolUtils.readString(Unpooled.wrappedBuffer(message.getData()));
             ProtocolUtils.writeString(rewrittenBuf, currentBrand + " (Velocity)");
+            rewrittenData = new byte[rewrittenBuf.readableBytes()];
+            rewrittenBuf.readBytes(rewrittenData);
+        } finally {
+            rewrittenBuf.release();
+        }
 
         PluginMessage newMsg = new PluginMessage();
         newMsg.setChannel(message.getChannel());
-        newMsg.setData(rewrittenBuf);
+        newMsg.setData(rewrittenData);
         return newMsg;
     }
 }