Add system for sending messages between servers

src/main/java/emu/grasscutter/server/dispatch/DispatchClient.java

@@ -1,17 +1,22 @@
 package emu.grasscutter.server.dispatch;
 
-import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
-
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.database.DatabaseHelper;
+import emu.grasscutter.server.event.dispatch.ServerMessageEvent;
 import emu.grasscutter.server.game.GameServer;
 import emu.grasscutter.server.http.handlers.GachaHandler;
 import emu.grasscutter.utils.Crypto;
 import emu.grasscutter.utils.DispatchUtils;
 import emu.grasscutter.utils.JsonUtils;
 import emu.grasscutter.utils.objects.HandbookBody;
+import lombok.Getter;
+import org.java_websocket.WebSocket;
+import org.java_websocket.client.WebSocketClient;
+import org.java_websocket.handshake.ServerHandshake;
+import org.slf4j.Logger;
+
 import java.net.ConnectException;
 import java.net.URI;
 import java.nio.ByteBuffer;
@@ -22,11 +27,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
-import lombok.Getter;
+
-import org.java_websocket.WebSocket;
+import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
-import org.java_websocket.client.WebSocketClient;
-import org.java_websocket.handshake.ServerHandshake;
-import org.slf4j.Logger;
 
 public final class DispatchClient extends WebSocketClient implements IDispatcher {
     @Getter private final Logger logger = Grasscutter.getLogger();
@@ -44,6 +46,7 @@ public final class DispatchClient extends WebSocketClient implements IDispatcher
         this.registerHandler(PacketIds.GmTalkReq, this::handleHandbookAction);
         this.registerHandler(PacketIds.GetPlayerFieldsReq, this::fetchPlayerFields);
         this.registerHandler(PacketIds.GetPlayerByAccountReq, this::fetchPlayerByAccount);
+        this.registerHandler(PacketIds.ServerMessageNotify, ServerMessageEvent::invoke);
     }
 
     /**

src/main/java/emu/grasscutter/server/dispatch/DispatchServer.java

@@ -1,12 +1,17 @@
 package emu.grasscutter.server.dispatch;
 
-import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
-
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.database.DatabaseHelper;
+import emu.grasscutter.server.event.dispatch.ServerMessageEvent;
 import emu.grasscutter.utils.Crypto;
+import lombok.Getter;
+import org.java_websocket.WebSocket;
+import org.java_websocket.handshake.ClientHandshake;
+import org.java_websocket.server.WebSocketServer;
+import org.slf4j.Logger;
+
 import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
@@ -15,11 +20,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
-import lombok.Getter;
+
-import org.java_websocket.WebSocket;
+import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
-import org.java_websocket.handshake.ClientHandshake;
-import org.java_websocket.server.WebSocketServer;
-import org.slf4j.Logger;
 
 /* Internal communications server. */
 public final class DispatchServer extends WebSocketServer implements IDispatcher {
@@ -40,6 +42,7 @@ public final class DispatchServer extends WebSocketServer implements IDispatcher
         this.registerHandler(PacketIds.LoginNotify, this::handleLogin);
         this.registerHandler(PacketIds.TokenValidateReq, this::validateToken);
         this.registerHandler(PacketIds.GetAccountReq, this::fetchAccount);
+        this.registerHandler(PacketIds.ServerMessageNotify, ServerMessageEvent::invoke);
     }
 
     /**

src/main/java/emu/grasscutter/server/dispatch/IDispatcher.java

@@ -1,7 +1,5 @@
 package emu.grasscutter.server.dispatch;
 
-import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
-
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
 import com.google.gson.JsonElement;
@@ -9,7 +7,11 @@ import com.google.gson.JsonObject;
 import emu.grasscutter.utils.Crypto;
 import emu.grasscutter.utils.JsonAdapters.ByteArrayAdapter;
 import emu.grasscutter.utils.objects.JObject;
+import org.java_websocket.WebSocket;
+import org.slf4j.Logger;
+
 import java.nio.charset.StandardCharsets;
+import java.util.Base64;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
@@ -18,8 +20,8 @@ import java.util.concurrent.TimeUnit;
 import java.util.function.BiConsumer;
 import java.util.function.Consumer;
 import java.util.function.Function;
-import org.java_websocket.WebSocket;
+
-import org.slf4j.Logger;
+import static emu.grasscutter.config.Configuration.DISPATCH_INFO;
 
 public interface IDispatcher {
     Gson JSON =
@@ -246,6 +248,51 @@ public interface IDispatcher {
         this.getCallbacks().get(packetId).add(callback);
     }
 
+    /**
+     * Sends a server message to the client.
+     *
+     * @param data The data to send.
+     * @param binary Whether the data is binary.
+     */
+    default void sendServerMessage(byte[] data, boolean binary) {
+        var message = new JObject()
+            .add("binary", binary)
+            .add("data", Base64.getEncoder().encodeToString(data))
+            .gson();
+
+        this.sendMessage(PacketIds.ServerMessageNotify, message);
+    }
+
+    /**
+     * Sends a server message to the client.
+     * The data is sent as a string.
+     *
+     * @param data The data to send.
+     */
+    default void sendServerMessage(String data) {
+        this.sendServerMessage(data.getBytes(), false);
+    }
+
+    /**
+     * Sends a server message to the client.
+     * The data is sent as a byte array.
+     *
+     * @param data The data to send.
+     */
+    default void sendServerMessage(byte[] data) {
+        this.sendServerMessage(data, true);
+    }
+
+    /**
+     * Sends a server message to the client.
+     * The data is sent as a JSON object.
+     *
+     * @param data The data to send.
+     */
+    default void sendServerMessage(Object data) {
+        this.sendServerMessage(JSON.toJson(data));
+    }
+
     /**
      * @return The logger for the dispatcher.
      */

src/main/java/emu/grasscutter/server/dispatch/PacketIds.java

@@ -17,4 +17,5 @@ public interface PacketIds {
     int GetPlayerFieldsRsp = 9;
     int GetPlayerByAccountReq = 10;
     int GetPlayerByAccountRsp = 11;
+    int ServerMessageNotify = 12;
 }

src/main/java/emu/grasscutter/server/event/dispatch/ServerMessageEvent.java

@@ -0,0 +1,61 @@
+package emu.grasscutter.server.event.dispatch;
+
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+import emu.grasscutter.server.dispatch.IDispatcher;
+import emu.grasscutter.server.event.Event;
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+import org.java_websocket.WebSocket;
+
+import java.util.Base64;
+
+@Getter
+@RequiredArgsConstructor
+public final class ServerMessageEvent extends Event {
+    /**
+     * Invokes the event.
+     *
+     * @param client The client that sent the message.
+     * @param object The message.
+     */
+    public static void invoke(WebSocket client, JsonElement object) {
+        var message = IDispatcher.decode(object);
+        var isBinary = message.get("binary").getAsBoolean();
+        var data = Base64.getDecoder().decode(
+            message.get("data").getAsString());
+
+        // Create the event and invoke it.
+        new ServerMessageEvent(client, isBinary, data).call();
+    }
+
+    private final WebSocket client;
+    private final boolean isBinary;
+    private final byte[] message;
+
+    /**
+     * @return The message as a string.
+     */
+    public String asString() {
+        if (this.isBinary)
+            throw new UnsupportedOperationException("Cannot convert binary message to string.");
+        return new String(this.message);
+    }
+
+    /**
+     * @return The message as a JSON object.
+     */
+    public JsonObject asJson() {
+        return IDispatcher.JSON.fromJson(
+            this.asString(), JsonObject.class);
+    }
+
+    /**
+     * @return The message as a JSON object.
+     *         The type is specified.
+     */
+    public <T> T asJson(Class<T> type) {
+        return IDispatcher.JSON.fromJson(
+            this.asString(), type);
+    }
+}