Fix custom MOTD not being sent after a player joins the server (fixes #8073)

paper-api/src/main/java/com/destroystokyo/paper/event/server/PaperServerListPingEvent.java

@@ -31,6 +31,16 @@
 /**
  * Extended version of {@link ServerListPingEvent} that allows full control
  * of the response sent to the client.
+ * <p>
+ * This event will sometimes fire synchronously, depending on how it was
+ * triggered.
+ * <p>
+ * If a request is done from outside the server, via the Minecraft client
+ * server menu or external tools, this event will be asynchronous.
+ * If a player joins the server, this event will be synchronous.
+ * <p>
+ * Care should be taken to check {@link #isAsynchronous()} and treat the event
+ * appropriately.
  */
 public class PaperServerListPingEvent extends ServerListPingEvent implements Cancellable {
 
@@ -56,9 +66,9 @@ public class PaperServerListPingEvent extends ServerListPingEvent implements Can
     private Object[] players;
 
     @ApiStatus.Internal
-    public PaperServerListPingEvent(@NotNull StatusClient client, @NotNull net.kyori.adventure.text.Component motd, int numPlayers, int maxPlayers,
-                                    @NotNull String version, int protocolVersion, @Nullable CachedServerIcon favicon) {
-        super("", client.getAddress().getAddress(), motd, numPlayers, maxPlayers);
+    public PaperServerListPingEvent(final boolean async, @NotNull StatusClient client, @NotNull net.kyori.adventure.text.Component motd, int numPlayers,
+                                    int maxPlayers, @NotNull String version, int protocolVersion, @Nullable CachedServerIcon favicon) {
+        super(async, "", client.getAddress().getAddress(), motd, numPlayers, maxPlayers);
         this.client = client;
         this.numPlayers = numPlayers;
         this.version = version;

paper-api/src/main/java/org/bukkit/event/server/ServerListPingEvent.java

@@ -35,8 +35,8 @@ public class ServerListPingEvent extends ServerEvent implements Iterable<Player>
 
     @ApiStatus.Internal
     @Deprecated(forRemoval = true)
-    public ServerListPingEvent(@NotNull final String hostname, @NotNull final InetAddress address, @NotNull final String motd, final int numPlayers, final int maxPlayers) {
-        super(true);
+    public ServerListPingEvent(final boolean async, @NotNull final String hostname, @NotNull final InetAddress address, @NotNull final String motd, final int numPlayers, final int maxPlayers) {
+        super(async);
         Preconditions.checkArgument(numPlayers >= 0, "Cannot have negative number of players online", numPlayers);
         this.hostname = hostname;
         this.address = address;
@@ -47,8 +47,8 @@ public ServerListPingEvent(@NotNull final String hostname, @NotNull final InetAd
 
     @ApiStatus.Internal
     @Deprecated(forRemoval = true)
-    protected ServerListPingEvent(@NotNull final String hostname, @NotNull final InetAddress address, @NotNull final String motd, final int maxPlayers) {
-        super(true);
+    protected ServerListPingEvent(final boolean async, @NotNull final String hostname, @NotNull final InetAddress address, @NotNull final String motd, final int maxPlayers) {
+        super(async);
         this.numPlayers = MAGIC_PLAYER_COUNT;
         this.hostname = hostname;
         this.address = address;
@@ -58,13 +58,13 @@ protected ServerListPingEvent(@NotNull final String hostname, @NotNull final Ine
 
     @ApiStatus.Internal
     @Deprecated(forRemoval = true)
-    public ServerListPingEvent(@NotNull final InetAddress address, @NotNull final Component motd, final int numPlayers, final int maxPlayers) {
-        this("", address, motd, numPlayers, maxPlayers);
+    public ServerListPingEvent(final boolean async, @NotNull final InetAddress address, @NotNull final Component motd, final int numPlayers, final int maxPlayers) {
+        this(async, "", address, motd, numPlayers, maxPlayers);
     }
 
     @ApiStatus.Internal
-    public ServerListPingEvent(@NotNull final String hostname, @NotNull final InetAddress address, @NotNull final Component motd, final int numPlayers, final int maxPlayers) {
-        super(true);
+    public ServerListPingEvent(final boolean async, @NotNull final String hostname, @NotNull final InetAddress address, @NotNull final Component motd, final int numPlayers, final int maxPlayers) {
+        super(async);
         this.hostname = hostname;
         this.address = address;
         this.motd = motd;

paper-server/patches/sources/net/minecraft/server/players/PlayerList.java.patch

@@ -86,7 +86,7 @@
          serverGamePacketListenerImpl.send(new ClientboundChangeDifficultyPacket(levelData.getDifficulty(), levelData.isDifficultyLocked()));
          serverGamePacketListenerImpl.send(new ClientboundPlayerAbilitiesPacket(player.getAbilities()));
          serverGamePacketListenerImpl.send(new ClientboundSetHeldSlotPacket(player.getInventory().getSelectedSlot()));
-@@ -203,24 +_,129 @@
+@@ -203,24 +_,135 @@
              mutableComponent = Component.translatable("multiplayer.player.joined.renamed", player.getDisplayName(), string);
          }
 
@@ -97,7 +97,14 @@
          serverGamePacketListenerImpl.teleport(player.getX(), player.getY(), player.getZ(), player.getYRot(), player.getXRot());
          ServerStatus status = this.server.getStatus();
          if (status != null && !cookie.transferred()) {
-             player.sendServerStatus(status);
+-            player.sendServerStatus(status);
++            // Paper start - Fire PaperServerListPingEvent when the player joins
++            // player.sendServerStatus(status);
++            status = com.destroystokyo.paper.network.StandardPaperServerListPingEventImpl.getEventResponse(this.server, player.connection.connection, false);
++            if (status != null) {
++                player.sendServerStatus(status);
++            }
++            // Paper end - Fire PaperServerListPingEvent when the player joins
          }
 
 -        player.connection.send(ClientboundPlayerInfoUpdatePacket.createPlayerInitializing(this.players));

paper-server/src/main/java/com/destroystokyo/paper/network/PaperLegacyStatusClient.java

@@ -47,7 +47,7 @@ public static PaperServerListPingEvent processRequest(MinecraftServer server,
             InetSocketAddress address, int protocolVersion, @Nullable InetSocketAddress virtualHost) {
 
         PaperServerListPingEvent event =  new PaperServerListPingEventImpl(server,
-                new PaperLegacyStatusClient(address, protocolVersion, virtualHost), Byte.MAX_VALUE, null);
+                new PaperLegacyStatusClient(address, protocolVersion, virtualHost), Byte.MAX_VALUE, null, true);
         server.server.getPluginManager().callEvent(event);
 
         if (event.isCancelled()) {

paper-server/src/main/java/com/destroystokyo/paper/network/PaperServerListPingEventImpl.java

@@ -12,8 +12,8 @@ class PaperServerListPingEventImpl extends PaperServerListPingEvent {
 
     private final MinecraftServer server;
 
-    PaperServerListPingEventImpl(MinecraftServer server, StatusClient client, int protocolVersion, @Nullable CachedServerIcon icon) {
-        super(client, server.motd(), server.getPlayerCount(), server.getMaxPlayers(),
+    PaperServerListPingEventImpl(MinecraftServer server, StatusClient client, int protocolVersion, @Nullable CachedServerIcon icon, boolean async) {
+        super(async, client, server.motd(), server.getPlayerCount(), server.getMaxPlayers(),
                 server.getServerModName() + ' ' + server.getServerVersion(), protocolVersion, icon);
         this.server = server;
     }

paper-server/src/main/java/com/destroystokyo/paper/network/StandardPaperServerListPingEventImpl.java

@@ -20,8 +20,8 @@ public final class StandardPaperServerListPingEventImpl extends PaperServerListP
 
     private List<NameAndId> originalSample;
 
-    private StandardPaperServerListPingEventImpl(MinecraftServer server, Connection networkManager, ServerStatus ping) {
-        super(server, new PaperStatusClient(networkManager), ping.version().map(ServerStatus.Version::protocol).orElse(-1), server.server.getServerIcon());
+    private StandardPaperServerListPingEventImpl(MinecraftServer server, Connection networkManager, ServerStatus ping, boolean async) {
+        super(server, new PaperStatusClient(networkManager), ping.version().map(ServerStatus.Version::protocol).orElse(-1), server.server.getServerIcon(), async);
         this.originalSample = ping.players().map(ServerStatus.Players::sample).orElse(null); // GH-1473 - pre-tick race condition NPE
     }
 
@@ -64,13 +64,24 @@ private List<NameAndId> getPlayerSampleHandle() {
     }
 
     public static void processRequest(MinecraftServer server, Connection networkManager) {
-        StandardPaperServerListPingEventImpl event = new StandardPaperServerListPingEventImpl(server, networkManager, server.getStatus());
+        ServerStatus ping = getEventResponse(server, networkManager, true);
+
+        if (ping == null) {
+            networkManager.disconnect((Component) null);
+            return;
+        }
+
+        // Send response
+        networkManager.send(new ClientboundStatusResponsePacket(ping));
+    }
+
+    public static ServerStatus getEventResponse(MinecraftServer server, Connection networkManager, boolean async) {
+        StandardPaperServerListPingEventImpl event = new StandardPaperServerListPingEventImpl(server, networkManager, server.getStatus(), async);
         server.server.getPluginManager().callEvent(event);
 
         // Close connection immediately if event is cancelled
         if (event.isCancelled()) {
-            networkManager.disconnect((Component) null);
-            return;
+            return null;
         }
 
         // Setup response
@@ -96,10 +107,9 @@ public static void processRequest(MinecraftServer server, Connection networkMana
         } else {
             favicon = Optional.empty();
         }
-        final ServerStatus ping = new ServerStatus(description, players, Optional.of(version), favicon, server.enforceSecureProfile());
 
-        // Send response
-        networkManager.send(new ClientboundStatusResponsePacket(ping));
+        // Return response
+        return new ServerStatus(description, players, Optional.of(version), favicon, server.enforceSecureProfile());
     }
 
 }