More efficient message handling

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

@@ -6,6 +6,7 @@ import com.velocitypowered.proxy.protocol.packets.*;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
+import io.netty.util.ReferenceCountUtil;
 
 public class BackendPlaySessionHandler implements MinecraftSessionHandler {
     private final ServerConnection connection;
@@ -43,15 +44,20 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
             connection.getProxyPlayer().getConnection().write(packet);
         } else if (packet instanceof PluginMessage) {
             PluginMessage pm = (PluginMessage) packet;
-            if (!canForwardMessage(pm)) {
+            try {
+                PluginMessage newPacket = pm;
+                if (!canForwardMessage(newPacket)) {
                     return;
                 }
 
-            if (pm.getChannel().equals("MC|Brand")) {
+                if (newPacket.getChannel().equals("MC|Brand")) {
-                pm = PluginMessageUtil.rewriteMCBrand(pm);
+                    newPacket = PluginMessageUtil.rewriteMCBrand(pm);
                 }
 
-            connection.getProxyPlayer().getConnection().write(pm);
+                connection.getProxyPlayer().getConnection().write(newPacket);
+            } finally {
+                ReferenceCountUtil.release(pm.getData());
+            }
         } else {
             // Just forward the packet on. We don't have anything to handle at this time.
             connection.getProxyPlayer().getConnection().write(packet);

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

@@ -10,6 +10,7 @@ import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import com.velocitypowered.proxy.util.ThrowableUtils;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.EventLoop;
+import io.netty.util.ReferenceCountUtil;
 import net.kyori.text.TextComponent;
 import net.kyori.text.format.TextColor;
 import org.apache.logging.log4j.LogManager;
@@ -173,6 +174,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     public void handleClientPluginMessage(PluginMessage packet) {
         logger.info("Got client plugin message packet {}", packet);
 
+        PluginMessage original = packet;
+        try {
             if (packet.getChannel().equals("REGISTER")) {
                 List<String> actuallyRegistered = new ArrayList<>();
                 List<String> channels = PluginMessageUtil.getChannels(packet);
@@ -208,6 +211,9 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
             // No other special handling?
             player.getConnectedServer().getChannel().write(packet);
+        } finally {
+            ReferenceCountUtil.release(original.getData());
+        }
     }
 
     public Set<String> getClientPluginMsgChannels() {

src/main/java/com/velocitypowered/proxy/protocol/ProtocolUtils.java

@@ -2,6 +2,7 @@ package com.velocitypowered.proxy.protocol;
 
 import com.google.common.base.Preconditions;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 
 import java.nio.charset.StandardCharsets;
 import java.util.UUID;
@@ -40,15 +41,15 @@ public enum ProtocolUtils { ;
     public static String readString(ByteBuf buf, int cap) {
         int length = readVarInt(buf);
         Preconditions.checkArgument(length <= cap, "Bad string size (got %s, maximum is %s)", length, cap);
-        byte[] str = new byte[length];
+        String str = buf.toString(buf.readerIndex(), length, StandardCharsets.UTF_8);
-        buf.readBytes(str);
+        buf.skipBytes(length);
-        return new String(str, StandardCharsets.UTF_8);
+        return str;
     }
 
     public static void writeString(ByteBuf buf, String str) {
-        byte[] asUtf8 = str.getBytes(StandardCharsets.UTF_8);
+        int size = ByteBufUtil.utf8Bytes(str);
-        writeVarInt(buf, asUtf8.length);
+        writeVarInt(buf, size);
-        buf.writeBytes(asUtf8);
+        ByteBufUtil.writeUtf8(buf, str);
     }
 
     public static byte[] readByteArray(ByteBuf buf) {

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

@@ -4,12 +4,13 @@ import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 
 import java.util.Arrays;
 
 public class PluginMessage implements MinecraftPacket {
     private String channel;
-    private byte[] data;
+    private ByteBuf data;
 
     public String getChannel() {
         return channel;
@@ -19,11 +20,11 @@ public class PluginMessage implements MinecraftPacket {
         this.channel = channel;
     }
 
-    public byte[] getData() {
+    public ByteBuf getData() {
         return data;
     }
 
-    public void setData(byte[] data) {
+    public void setData(ByteBuf data) {
         this.data = data;
     }
 
@@ -31,15 +32,14 @@ public class PluginMessage implements MinecraftPacket {
     public String toString() {
         return "PluginMessage{" +
                 "channel='" + channel + '\'' +
-                ", data=" + Arrays.toString(data) +
+                ", data=" + ByteBufUtil.hexDump(data) +
                 '}';
     }
 
     @Override
     public void decode(ByteBuf buf, ProtocolConstants.Direction direction, int protocolVersion) {
         this.channel = ProtocolUtils.readString(buf, 20);
-        this.data = new byte[buf.readableBytes()];
+        this.data = buf.readRetainedSlice(buf.readableBytes());
-        buf.readBytes(this.data);
     }
 
     @Override

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

@@ -6,6 +6,7 @@ import com.google.common.collect.ImmutableList;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.packets.PluginMessage;
 import io.netty.buffer.ByteBuf;
+import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 
 import java.nio.charset.StandardCharsets;
@@ -18,32 +19,33 @@ public enum PluginMessageUtil {
     public static List<String> getChannels(PluginMessage message) {
         Preconditions.checkArgument(message.getChannel().equals("REGISTER") ||
                 message.getChannel().equals("UNREGISTER"), "Unknown channel type " + message.getChannel());
-        return ImmutableList.copyOf(new String(message.getData()).split("\0"));
+        String channels = message.getData().toString(StandardCharsets.UTF_8);
+        return ImmutableList.copyOf(channels.split("\0"));
     }
 
     public static PluginMessage constructChannelsPacket(String channel, Collection<String> channels) {
         PluginMessage message = new PluginMessage();
         message.setChannel(channel);
-        message.setData(Joiner.on("\0").join(channels).getBytes(StandardCharsets.UTF_8));
+
+        ByteBuf data = Unpooled.buffer();
+        for (String s : channels) {
+            ByteBufUtil.writeUtf8(data, s);
+            data.writeByte(0);
+        }
+        data.writerIndex(data.writerIndex() - 1);
+
+        message.setData(data);
         return message;
     }
 
     public static PluginMessage rewriteMCBrand(PluginMessage message) {
-        ByteBuf currentBrandBuf = Unpooled.wrappedBuffer(message.getData());
         ByteBuf rewrittenBuf = Unpooled.buffer();
-        byte[] rewrittenBrand;
+        String currentBrand = ProtocolUtils.readString(message.getData());
-        try {
-            String currentBrand = ProtocolUtils.readString(currentBrandBuf);
         ProtocolUtils.writeString(rewrittenBuf, currentBrand + " (Velocity)");
-            rewrittenBrand = new byte[rewrittenBuf.readableBytes()];
-            rewrittenBuf.readBytes(rewrittenBrand);
-        } finally {
-            rewrittenBuf.release();
-        }
 
         PluginMessage newMsg = new PluginMessage();
         newMsg.setChannel("MC|Brand");
-        newMsg.setData(rewrittenBrand);
+        newMsg.setData(rewrittenBuf);
         return newMsg;
     }
 }