Create a specific Forge-related package

proxy/src/main/java/com/velocitypowered/proxy/connection/VelocityConstants.java

@@ -7,9 +7,4 @@ public class VelocityConstants {
 
     public static final String VELOCITY_IP_FORWARDING_CHANNEL = "velocity:player_info";
 
-    public static final String FORGE_LEGACY_HANDSHAKE_CHANNEL = "FML|HS";
-    public static final String FORGE_LEGACY_CHANNEL = "FML";
-    public static final String FORGE_MULTIPART_LEGACY_CHANNEL = "FML|MP";
-
-    public static final byte[] FORGE_LEGACY_HANDSHAKE_RESET_DATA = new byte[] { -2, 0 };
 }

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

@@ -5,14 +5,13 @@ import com.velocitypowered.api.event.player.ServerConnectedEvent;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
+import com.velocitypowered.proxy.connection.forge.ForgeUtil;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.*;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
-import com.velocitypowered.proxy.tablist.VelocityTabList;
 import io.netty.buffer.ByteBuf;
 
 public class BackendPlaySessionHandler implements MinecraftSessionHandler {
@@ -85,7 +84,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
             return true;
         }
 
-        if (!serverConn.hasCompletedJoin() && packet.getChannel().equals(VelocityConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL)) {
+        if (!serverConn.hasCompletedJoin() && packet.getChannel().equals(ForgeUtil.FORGE_LEGACY_HANDSHAKE_CHANNEL)) {
             if (!serverConn.isLegacyForge()) {
                 serverConn.setLegacyForge(true);
 
@@ -174,7 +173,7 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
         boolean isMCOrFMLMessage;
         if (serverConn.getConnection().getProtocolVersion() <= ProtocolConstants.MINECRAFT_1_12_2) {
             String channel = message.getChannel();
-            isMCOrFMLMessage = channel.startsWith("MC|") || channel.startsWith(VelocityConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL);
+            isMCOrFMLMessage = channel.startsWith("MC|") || channel.startsWith(ForgeUtil.FORGE_LEGACY_HANDSHAKE_CHANNEL);
         } else {
             isMCOrFMLMessage = message.getChannel().startsWith("minecraft:");
         }

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

@@ -6,8 +6,8 @@ import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.util.ModInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
-import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
+import com.velocitypowered.proxy.connection.forge.ForgeUtil;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
 import com.velocitypowered.proxy.protocol.packet.*;
@@ -144,9 +144,9 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
         } else if (PluginMessageUtil.isMCBrand(packet)) {
             player.getConnectedServer().getConnection().write(PluginMessageUtil.rewriteMCBrand(packet));
         } else if (player.getConnectedServer().isLegacyForge() && !player.getConnectedServer().hasCompletedJoin()) {
-            if (packet.getChannel().equals(VelocityConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL)) {
+            if (packet.getChannel().equals(ForgeUtil.FORGE_LEGACY_HANDSHAKE_CHANNEL)) {
                 if (!player.getModInfo().isPresent()) {
-                    PluginMessageUtil.readModList(packet).ifPresent(mods -> player.setModInfo(new ModInfo("FML", mods)));
+                    ForgeUtil.readModList(packet).ifPresent(mods -> player.setModInfo(new ModInfo("FML", mods)));
                 }
                 
                 // Always forward the FML handshake to the remote server.

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

@@ -25,8 +25,8 @@ import com.velocitypowered.api.util.title.Titles;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
-import com.velocitypowered.proxy.connection.VelocityConstants;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
+import com.velocitypowered.proxy.connection.forge.ForgeUtil;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults;
 import com.velocitypowered.proxy.protocol.ProtocolConstants;
@@ -400,8 +400,8 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     public void sendLegacyForgeHandshakeResetPacket() {
         if (connection.canSendLegacyFMLResetPacket()) {
             PluginMessage resetPacket = new PluginMessage();
-            resetPacket.setChannel(VelocityConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL);
+            resetPacket.setChannel(ForgeUtil.FORGE_LEGACY_HANDSHAKE_CHANNEL);
-            resetPacket.setData(VelocityConstants.FORGE_LEGACY_HANDSHAKE_RESET_DATA);
+            resetPacket.setData(ForgeUtil.FORGE_LEGACY_HANDSHAKE_RESET_DATA);
             connection.write(resetPacket);
             connection.setCanSendLegacyFMLResetPacket(false);
         }

proxy/src/main/java/com/velocitypowered/proxy/connection/forge/ForgeConstants.java

@@ -0,0 +1,4 @@
+package com.velocitypowered.proxy.connection.forge;
+
+public class ForgeConstants {
+}

proxy/src/main/java/com/velocitypowered/proxy/connection/forge/ForgeUtil.java

@@ -0,0 +1,51 @@
+package com.velocitypowered.proxy.connection.forge;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.ImmutableList;
+import com.velocitypowered.api.util.ModInfo;
+import com.velocitypowered.proxy.protocol.ProtocolUtils;
+import com.velocitypowered.proxy.protocol.packet.PluginMessage;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+
+import java.util.List;
+import java.util.Optional;
+
+public class ForgeUtil {
+    public static final String FORGE_LEGACY_HANDSHAKE_CHANNEL = "FML|HS";
+    public static final String FORGE_LEGACY_CHANNEL = "FML";
+    public static final String FORGE_MULTIPART_LEGACY_CHANNEL = "FML|MP";
+    public static final byte[] FORGE_LEGACY_HANDSHAKE_RESET_DATA = new byte[] { -2, 0 };
+
+    private ForgeUtil() {
+        throw new AssertionError();
+    }
+
+    public static Optional<List<ModInfo.Mod>> readModList(PluginMessage message) {
+        Preconditions.checkNotNull(message, "message");
+        Preconditions.checkArgument(message.getChannel().equals(FORGE_LEGACY_HANDSHAKE_CHANNEL),
+                "message is not a FML HS plugin message");
+
+        ByteBuf byteBuf = Unpooled.wrappedBuffer(message.getData());
+        try {
+            byte discriminator = byteBuf.readByte();
+
+            if (discriminator == 2) {
+                ImmutableList.Builder<ModInfo.Mod> mods = ImmutableList.builder();
+                int modCount = ProtocolUtils.readVarInt(byteBuf);
+
+                for (int index = 0; index < modCount; index++) {
+                    String id = ProtocolUtils.readString(byteBuf);
+                    String version = ProtocolUtils.readString(byteBuf);
+                    mods.add(new ModInfo.Mod(id, version));
+                }
+
+                return Optional.of(mods.build());
+            }
+
+            return Optional.empty();
+        } finally {
+            byteBuf.release();
+        }
+    }
+}

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

@@ -81,31 +81,4 @@ public class PluginMessageUtil {
         return newMsg;
     }
 
-    public static Optional<List<ModInfo.Mod>> readModList(PluginMessage message) {
-        Preconditions.checkNotNull(message, "message");
-        Preconditions.checkArgument(message.getChannel().equals(VelocityConstants.FORGE_LEGACY_HANDSHAKE_CHANNEL),
-                "message is not a FML HS plugin message");
-        
-        ByteBuf byteBuf = Unpooled.wrappedBuffer(message.getData());
-        try {
-            byte discriminator = byteBuf.readByte();
-            
-            if (discriminator == 2) {
-                ImmutableList.Builder<ModInfo.Mod> mods = ImmutableList.builder();
-                int modCount = ProtocolUtils.readVarInt(byteBuf);
-                
-                for (int index = 0; index < modCount; index++) {
-                    String id = ProtocolUtils.readString(byteBuf);
-                    String version = ProtocolUtils.readString(byteBuf);
-                    mods.add(new ModInfo.Mod(id, version));
-                }
-                
-                return Optional.of(mods.build());
-            }
-            
-            return Optional.empty();
-        } finally {
-            byteBuf.release();
-        }
-    }
 }