HandshakeResponsePacket

pom.xml

@@ -41,6 +41,11 @@
             <artifactId>lombok</artifactId>
             <version>1.16.16</version>
         </dependency>
+        <dependency>
+            <groupId>com.google.code.gson</groupId>
+            <artifactId>gson</artifactId>
+            <version>2.8.2</version>
+        </dependency>
 
         <!-- Netty -->
         <dependency>

src/main/java/mc/core/netty/BasePacket.java

@@ -4,14 +4,21 @@
  */
 package mc.core.netty;
 
+import io.netty.buffer.ByteBuf;
 import lombok.Getter;
 import lombok.RequiredArgsConstructor;
 import lombok.ToString;
+import lombok.extern.slf4j.Slf4j;
 
 @RequiredArgsConstructor
 @Getter
 @ToString
+@Slf4j
 class BasePacket {
     private final int length;
     private final int id;
+
+    public void writeSelf(ByteBuf byteBuf) {
+        log.warn("write not support");
+    }
 }

src/main/java/mc/core/netty/HandshakeRequestPacket.java

@@ -12,13 +12,13 @@ import static mc.core.netty.Utilits.*;
 
 @Getter
 @ToString
-public class HandshakePacket extends BasePacket {
+public class HandshakeRequestPacket extends BasePacket {
     private final int protocolVersion;
     private final String serverAddress;
     private final int serverPort;
     private final int nextState;
 
-    public HandshakePacket(int length, int id, ByteBuf byteBuf) throws Exception {
+    public HandshakeRequestPacket(int length, int id, ByteBuf byteBuf) throws Exception {
         super(length, id);
 
         protocolVersion = readVarInt(byteBuf);

src/main/java/mc/core/netty/HandshakeResponsePacket.java

@@ -0,0 +1,48 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-03-25
+ */
+package mc.core.netty;
+
+import com.google.gson.JsonObject;
+import io.netty.buffer.ByteBuf;
+
+import static mc.core.netty.Utilits.lengthVarInt;
+
+public class HandshakeResponsePacket extends BasePacket {
+    private static String json;
+
+    static {
+        JsonObject versionObj = new JsonObject();
+        versionObj.addProperty("name", "1.12.2");
+        versionObj.addProperty("protocol", 340);
+
+        JsonObject playersObj = new JsonObject();
+        playersObj.addProperty("max", 100);
+        playersObj.addProperty("online", 15);
+
+        JsonObject descriptionObj = new JsonObject();
+        descriptionObj.addProperty("text", "MC Core");
+
+        JsonObject rootObj = new JsonObject();
+        rootObj.add("version", versionObj);
+        rootObj.add("players", playersObj);
+        rootObj.add("description", descriptionObj);
+
+        json = rootObj.toString();
+    }
+
+    public HandshakeResponsePacket(int length, int id) {
+        super(length, id);
+    }
+
+    @Override
+    public void writeSelf(ByteBuf byteBuf) {
+        Utilits.writeString(json, byteBuf);
+    }
+
+    @Override
+    public int getLength() {
+        return lengthVarInt(getId()) + lengthVarInt(json.length()) + json.length();
+    }
+}

src/main/java/mc/core/netty/NettyServer.java

@@ -23,6 +23,7 @@ public class NettyServer implements Server {
             protected void initChannel(SocketChannel socketChannel) {
                 socketChannel.pipeline().addLast(
                         new LoggingHandler(),
+                        new PacketEncoder(),
                         new PacketDecoder(),
                         new PacketHandler()
                 );

src/main/java/mc/core/netty/PacketDecoder.java

@@ -19,7 +19,7 @@ public class PacketDecoder extends ReplayingDecoder<BasePacket> {
         int id = readVarInt(byteBuf);
 
         if (id == 0) {
-            list.add(new HandshakePacket(length, id, byteBuf));
+            list.add(new HandshakeRequestPacket(length, id, byteBuf));
         } else {
             list.add(new BasePacket(length, id));
             byteBuf.skipBytes(length);

src/main/java/mc/core/netty/PacketEncoder.java

@@ -0,0 +1,20 @@
+/*
+ * DmitriyMX <dimon550@gmail.com>
+ * 2018-03-25
+ */
+package mc.core.netty;
+
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.MessageToByteEncoder;
+
+import static mc.core.netty.Utilits.writeVarInt;
+
+public class PacketEncoder extends MessageToByteEncoder<BasePacket> {
+    @Override
+    protected void encode(ChannelHandlerContext context, BasePacket packet, ByteBuf byteBuf) throws Exception {
+        writeVarInt(packet.getLength(), byteBuf);
+        writeVarInt(packet.getId(), byteBuf);
+        packet.writeSelf(byteBuf);
+    }
+}

src/main/java/mc/core/netty/PacketHandler.java

@@ -15,5 +15,9 @@ public class PacketHandler extends SimpleChannelInboundHandler<BasePacket> {
         log.info("Packet: {} | Data: {}",
                 packet.getClass().getSimpleName(),
                 packet.toString());
+
+        if (packet.getClass().getSimpleName().equals("HandshakeRequestPacket")) {
+            context.channel().writeAndFlush(new HandshakeResponsePacket(0, 0));
+        }
     }
 }

src/main/java/mc/core/netty/Utilits.java

@@ -28,6 +28,29 @@ public class Utilits {
         return result;
     }
 
+    public static void writeVarInt(int value, ByteBuf byteBuf) {
+        do {
+            byte temp = (byte)(value & 0b01111111);
+            value >>>= 7;
+            if (value != 0) {
+                temp |= 0b10000000;
+            }
+
+            byteBuf.writeByte(temp);
+        } while (value != 0);
+    }
+
+    public static int lengthVarInt(int value) {
+        int result = 0;
+
+        do {
+            value >>>= 7;
+            result++;
+        } while (value != 0);
+
+        return result;
+    }
+
     public static String readString(ByteBuf byteBuf) throws Exception {
         int length = readVarInt(byteBuf);
         byte[] buffer = new byte[length];
@@ -42,4 +65,9 @@ public class Utilits {
     public static int readUnsignedShort(ByteBuf byteBuf) {
         return byteBuf.readUnsignedShort();
     }
+
+    public static void writeString(String value, ByteBuf byteBuf) {
+        writeVarInt(value.length(), byteBuf);
+        byteBuf.writeBytes(value.getBytes());
+    }
 }