#3864: Add ServerLinks API

api/src/main/java/net/md_5/bungee/api/ServerLink.java

@@ -0,0 +1,77 @@
+package net.md_5.bungee.api;
+
+import lombok.AccessLevel;
+import lombok.Data;
+import lombok.NonNull;
+import lombok.RequiredArgsConstructor;
+import net.md_5.bungee.api.chat.BaseComponent;
+
+/**
+ * Represents a server link which may be sent to the client.
+ */
+@Data
+@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
+public final class ServerLink
+{
+
+    /**
+     * The links type.
+     *
+     * Note: This value is nullable, if null, label is non-null.
+     */
+    private final LinkType type;
+
+    /**
+     * The label for the link.
+     *
+     * Note: This value is nullable, if null, type is non-null.
+     */
+    private final BaseComponent label;
+
+    /**
+     * The URL that is displayed.
+     */
+    @NonNull
+    private final String url;
+
+    /**
+     * Creates a link with a specified type and URL.
+     *
+     * @param type the type of the link
+     * @param url the URL to be displayed
+     */
+    public ServerLink(@NonNull LinkType type, @NonNull String url)
+    {
+        this.type = type;
+        this.label = null;
+        this.url = url;
+    }
+
+    /**
+     * Creates a link with a label and URL.
+     *
+     * @param label the label to be displayed
+     * @param url the URL to be displayed
+     */
+    public ServerLink(@NonNull BaseComponent label, @NonNull String url)
+    {
+        this.type = null;
+        this.label = label;
+        this.url = url;
+    }
+
+    public enum LinkType
+    {
+
+        REPORT_BUG,
+        COMMUNITY_GUIDELINES,
+        SUPPORT,
+        STATUS,
+        FEEDBACK,
+        COMMUNITY,
+        WEBSITE,
+        FORUMS,
+        NEWS,
+        ANNOUNCEMENTS;
+    }
+}

api/src/main/java/net/md_5/bungee/api/connection/ProxiedPlayer.java

@@ -1,5 +1,6 @@
 package net.md_5.bungee.api.connection;
 
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.UUID;
@@ -8,6 +9,7 @@ import net.md_5.bungee.api.Callback;
 import net.md_5.bungee.api.ChatMessageType;
 import net.md_5.bungee.api.CommandSender;
 import net.md_5.bungee.api.ServerConnectRequest;
+import net.md_5.bungee.api.ServerLink;
 import net.md_5.bungee.api.SkinConfiguration;
 import net.md_5.bungee.api.Title;
 import net.md_5.bungee.api.chat.BaseComponent;
@@ -411,4 +413,16 @@ public interface ProxiedPlayer extends Connection, CommandSender
      */
     @ApiStatus.Experimental
     void showDialog(Dialog dialog);
+
+    /**
+     * Sends server links to the player.
+     *
+     * Note: The links already sent to the player will be overwritten. Also, the
+     * backend server is able to override links sent by the proxy.
+     *
+     * @param serverLinks the server links to send
+     * @throws IllegalStateException if the player's version is not at least
+     * 1.21
+     */
+    void sendServerLinks(List<ServerLink> serverLinks);
 }

protocol/src/main/java/net/md_5/bungee/protocol/packet/ServerLinks.java

@@ -27,10 +27,10 @@ public class ServerLinks extends DefinedPacket
         links = new Link[ len ];
         for ( int i = 0; i < len; i++ )
         {
-            Either<LinkType, BaseComponent> type;
+            Either<Integer, BaseComponent> type;
             if ( buf.readBoolean() )
             {
-                type = Either.left( LinkType.values()[readVarInt( buf )] );
+                type = Either.left( readVarInt( buf ) );
             } else
             {
                 type = Either.right( readBaseComponent( buf, protocolVersion ) );
@@ -47,11 +47,11 @@ public class ServerLinks extends DefinedPacket
         writeVarInt( links.length, buf );
         for ( Link link : links )
         {
-            Either<LinkType, BaseComponent> type = link.getType();
+            Either<Integer, BaseComponent> type = link.getType();
             if ( type.isLeft() )
             {
                 buf.writeBoolean( true );
-                writeVarInt( type.getLeft().ordinal(), buf );
+                writeVarInt( type.getLeft(), buf );
             } else
             {
                 buf.writeBoolean( false );
@@ -67,26 +67,11 @@ public class ServerLinks extends DefinedPacket
         handler.handle( this );
     }
 
-    public enum LinkType
-    {
-
-        REPORT_BUG,
-        COMMUNITY_GUIDELINES,
-        SUPPORT,
-        STATUS,
-        FEEDBACK,
-        COMMUNITY,
-        WEBSITE,
-        FORUMS,
-        NEWS,
-        ANNOUNCEMENTS;
-    }
-
     @Data
     public static class Link
     {
 
-        private final Either<LinkType, BaseComponent> type;
+        private final Either<Integer, BaseComponent> type;
         private final String url;
     }
 }

proxy/src/main/java/net/md_5/bungee/UserConnection.java

@@ -14,6 +14,7 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.Objects;
@@ -29,6 +30,7 @@ import net.md_5.bungee.api.Callback;
 import net.md_5.bungee.api.ChatMessageType;
 import net.md_5.bungee.api.ProxyServer;
 import net.md_5.bungee.api.ServerConnectRequest;
+import net.md_5.bungee.api.ServerLink;
 import net.md_5.bungee.api.SkinConfiguration;
 import net.md_5.bungee.api.Title;
 import net.md_5.bungee.api.chat.BaseComponent;
@@ -59,6 +61,7 @@ import net.md_5.bungee.protocol.packet.ClientSettings;
 import net.md_5.bungee.protocol.packet.Kick;
 import net.md_5.bungee.protocol.packet.PlayerListHeaderFooter;
 import net.md_5.bungee.protocol.packet.PluginMessage;
+import net.md_5.bungee.protocol.packet.ServerLinks;
 import net.md_5.bungee.protocol.packet.SetCompression;
 import net.md_5.bungee.protocol.packet.ShowDialog;
 import net.md_5.bungee.protocol.packet.ShowDialogDirect;
@@ -860,4 +863,16 @@ public final class UserConnection implements ProxiedPlayer
 
         unsafe.sendPacket( new ShowDialog( Either.right( dialog ) ) );
     }
+
+    @Override
+    public void sendServerLinks(List<ServerLink> serverLinks)
+    {
+        Preconditions.checkState( getPendingConnection().getVersion() >= ProtocolConstants.MINECRAFT_1_21, "Server links are only supported in 1.21 and above" );
+
+        ServerLinks.Link[] links = serverLinks.stream()
+                .map( link -> new ServerLinks.Link( link.getType() != null ? Either.left( link.getType().ordinal() ) : Either.right( link.getLabel() ), link.getUrl() ) )
+                .toArray( ServerLinks.Link[]::new );
+
+        unsafe.sendPacket( new ServerLinks( links ) );
+    }
 }