Allow for sending plugin messages during configuration stage (#12915)

paper-api/src/main/java/io/papermc/paper/connection/PlayerCommonConnection.java

@@ -4,11 +4,12 @@ import java.util.Map;
 
 import com.destroystokyo.paper.ClientOption;
 import org.bukkit.ServerLinks;
+import org.bukkit.plugin.messaging.PluginMessageRecipient;
 
 /**
  * Represents a connection that has properties shared between the GAME and CONFIG stage.
  */
-public interface PlayerCommonConnection extends WritablePlayerCookieConnection, ReadablePlayerCookieConnection {
+public interface PlayerCommonConnection extends WritablePlayerCookieConnection, ReadablePlayerCookieConnection, PluginMessageRecipient {
 
     /**
      * Sends data to appear in this connection's report logs.

paper-server/patches/features/0032-Improve-keepalive-ping-system.patch

@@ -100,7 +100,7 @@ index 962084054c0208470d0c3c99c5dca6327c9b8752..2abc21102bbd2da79dc0c50826cff7da
      }
  }
 diff --git a/net/minecraft/server/network/ServerCommonPacketListenerImpl.java b/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
-index 1b42d5e9f9fd07f99009de6f4483648f416db733..08c59d603fca038fc2dde36384eea1b6c971e659 100644
+index 5e074e6b5b8699b5c978a31518775479a43266ac..07c4a25c121676db867e8fb438ba41ad58528a4d 100644
 --- a/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
 +++ b/net/minecraft/server/network/ServerCommonPacketListenerImpl.java
 @@ -38,12 +38,13 @@ public abstract class ServerCommonPacketListenerImpl implements ServerCommonPack
@@ -120,7 +120,7 @@ index 1b42d5e9f9fd07f99009de6f4483648f416db733..08c59d603fca038fc2dde36384eea1b6
 +    private final io.papermc.paper.util.KeepAlive keepAlive; // Paper - improve keepalives
      private volatile boolean suspendFlushingOnServerThread = false;
      // CraftBukkit start
-     protected final org.bukkit.craftbukkit.CraftServer cserver;
+     public final org.bukkit.craftbukkit.CraftServer cserver;
 @@ -60,13 +61,14 @@ public abstract class ServerCommonPacketListenerImpl implements ServerCommonPack
      public ServerCommonPacketListenerImpl(MinecraftServer server, Connection connection, CommonListenerCookie cookie) {
          this.server = server;

paper-server/patches/sources/net/minecraft/server/network/ServerCommonPacketListenerImpl.java.patch

@@ -14,7 +14,7 @@
      private int latency;
      private volatile boolean suspendFlushingOnServerThread = false;
 +    // CraftBukkit start
-+    protected final org.bukkit.craftbukkit.CraftServer cserver;
++    public final org.bukkit.craftbukkit.CraftServer cserver;
 +    public boolean processedDisconnect;
 +    // CraftBukkit end
 +    public final java.util.Map<java.util.UUID, net.kyori.adventure.resource.ResourcePackCallback> packCallbacks = new java.util.concurrent.ConcurrentHashMap<>(); // Paper - adventure resource pack callbacks

paper-server/src/main/java/io/papermc/paper/connection/PaperPlayerConfigurationConnection.java

@@ -20,13 +20,18 @@ import net.kyori.adventure.resource.ResourcePackInfo;
 import net.kyori.adventure.resource.ResourcePackRequest;
 import net.minecraft.network.chat.Component;
 import net.minecraft.network.protocol.common.ClientboundClearDialogPacket;
+import net.minecraft.network.protocol.common.ClientboundCustomPayloadPacket;
 import net.minecraft.network.protocol.common.ClientboundResourcePackPopPacket;
 import net.minecraft.network.protocol.common.ClientboundResourcePackPushPacket;
 import net.minecraft.network.protocol.common.ClientboundShowDialogPacket;
+import net.minecraft.network.protocol.common.custom.DiscardedPayload;
 import net.minecraft.network.protocol.configuration.ClientboundResetChatPacket;
+import net.minecraft.resources.ResourceLocation;
 import net.minecraft.server.level.ClientInformation;
 import net.minecraft.server.network.ConfigurationTask;
 import net.minecraft.server.network.ServerConfigurationPacketListenerImpl;
+import org.bukkit.plugin.Plugin;
+import org.bukkit.plugin.messaging.StandardMessenger;
 import org.jspecify.annotations.Nullable;
 
 public class PaperPlayerConfigurationConnection extends PaperCommonConnection<ServerConfigurationPacketListenerImpl> implements PlayerConfigurationConnection, Audience, PluginMessageBridgeImpl {
@@ -122,4 +127,21 @@ public class PaperPlayerConfigurationConnection extends PaperCommonConnection<Se
     public Set<String> channels() {
         return this.handle.pluginMessagerChannels;
     }
+
+    @Override
+    public void sendPluginMessage(final Plugin source, final String channel, final byte[] message) {
+        StandardMessenger.validatePluginMessage(this.handle.cserver.getMessenger(), source, channel, message);
+
+        if (this.channels().contains(channel)) {
+            @SuppressWarnings("deprecation") // "not an API method" does not apply to us
+            ResourceLocation id = ResourceLocation.parse(StandardMessenger.validateAndCorrectChannel(channel));
+            ClientboundCustomPayloadPacket packet = new ClientboundCustomPayloadPacket(new DiscardedPayload(id, message));
+            this.handle.send(packet);
+        }
+    }
+
+    @Override
+    public Set<String> getListeningPluginChannels() {
+        return Set.copyOf(this.channels());
+    }
 }

paper-server/src/main/java/io/papermc/paper/connection/PaperPlayerGameConnection.java

@@ -3,6 +3,8 @@ package io.papermc.paper.connection;
 import net.minecraft.server.level.ClientInformation;
 import net.minecraft.server.network.ServerGamePacketListenerImpl;
 import org.bukkit.entity.Player;
+import org.bukkit.plugin.Plugin;
+import java.util.Set;
 
 public class PaperPlayerGameConnection extends PaperCommonConnection<ServerGamePacketListenerImpl> implements PlayerGameConnection {
 
@@ -28,4 +30,14 @@ public class PaperPlayerGameConnection extends PaperCommonConnection<ServerGameP
     public Player getPlayer() {
         return this.handle.getCraftPlayer();
     }
+
+    @Override
+    public void sendPluginMessage(final Plugin source, final String channel, final byte[] message) {
+        getPlayer().sendPluginMessage(source, channel, message);
+    }
+
+    @Override
+    public Set<String> getListeningPluginChannels() {
+        return getPlayer().getListeningPluginChannels();
+    }
 }