Add compression support for proxy->server connections.

src/main/java/io/minimum/minecraft/velocity/protocol/netty/MinecraftCompressEncoder.java

@@ -17,14 +17,12 @@ public class MinecraftCompressEncoder extends MessageToByteEncoder<ByteBuf> {
     @Override
     protected void encode(ChannelHandlerContext ctx, ByteBuf msg, ByteBuf out) throws Exception {
         if (msg.readableBytes() <= threshold) {
-            System.out.println("not compressing packet of 0x" + msg.readableBytes() + " size");
             // Under the threshold, there is nothing to do.
             ProtocolUtils.writeVarInt(out, 0);
             out.writeBytes(msg);
             return;
         }
 
-        System.out.println("compressing packet of 0x" + msg.readableBytes() + " size");
         Deflater deflater = new Deflater();
         byte[] buf = new byte[msg.readableBytes()];
         msg.readBytes(buf);

src/main/java/io/minimum/minecraft/velocity/protocol/netty/MinecraftPipelineUtils.java

@@ -23,6 +23,12 @@ public class MinecraftPipelineUtils {
     }
 
     public static void enableCompression(Channel ch, int threshold) {
+        if (threshold == -1) {
+            ch.pipeline().remove("compress-decoder");
+            ch.pipeline().remove("compress-encoder");
+            return;
+        }
+
         MinecraftCompressEncoder encoder = new MinecraftCompressEncoder(threshold);
         MinecraftCompressDecoder decoder = new MinecraftCompressDecoder(threshold);
 

src/main/java/io/minimum/minecraft/velocity/proxy/ServerConnection.java

@@ -7,10 +7,7 @@ import io.minimum.minecraft.velocity.data.ServerInfo;
 import io.minimum.minecraft.velocity.protocol.netty.MinecraftDecoder;
 import io.minimum.minecraft.velocity.protocol.netty.MinecraftEncoder;
 import io.minimum.minecraft.velocity.protocol.netty.MinecraftPipelineUtils;
-import io.minimum.minecraft.velocity.protocol.packets.Disconnect;
-import io.minimum.minecraft.velocity.protocol.packets.Handshake;
-import io.minimum.minecraft.velocity.protocol.packets.ServerLogin;
-import io.minimum.minecraft.velocity.protocol.packets.ServerLoginSuccess;
+import io.minimum.minecraft.velocity.protocol.packets.*;
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.*;
 import net.kyori.text.TextComponent;
@@ -119,6 +116,12 @@ public class ServerConnection {
                 proxyPlayer.handleConnectionException(disconnect);
             }
 
+            if (packet instanceof SetCompression) {
+                System.out.println("Enabling compression on server connection, this is inefficient!");
+                SetCompression sc = (SetCompression) packet;
+                MinecraftPipelineUtils.enableCompression(channel, sc.getThreshold());
+            }
+
             if (packet instanceof ServerLoginSuccess) {
                 // the player has been logged on.
                 System.out.println("Player connected to remote server");