Detect component loops

api/src/main/java/net/md_5/bungee/chat/BaseComponentSerializer.java

@@ -1,5 +1,6 @@
 package net.md_5.bungee.chat;
 
+import com.google.common.base.Preconditions;
 import com.google.gson.JsonDeserializationContext;
 import com.google.gson.JsonObject;
 import com.google.gson.JsonSerializationContext;
@@ -72,6 +73,8 @@ public class BaseComponentSerializer
 
     protected void serialize(JsonObject object, BaseComponent component, JsonSerializationContext context)
     {
+        Preconditions.checkArgument( !ComponentSerializer.serializedComponents.get().contains( component ), "Component loop" );
+        ComponentSerializer.serializedComponents.get().add( component );
         if ( component.getColorRaw() != null )
         {
             object.addProperty( "color", component.getColorRaw().getName() );

api/src/main/java/net/md_5/bungee/chat/ComponentSerializer.java

@@ -14,6 +14,7 @@ import net.md_5.bungee.api.chat.TextComponent;
 import net.md_5.bungee.api.chat.TranslatableComponent;
 
 import java.lang.reflect.Type;
+import java.util.HashSet;
 
 public class ComponentSerializer implements JsonSerializer<BaseComponent>, JsonDeserializer<BaseComponent>
 {
@@ -24,6 +25,15 @@ public class ComponentSerializer implements JsonSerializer<BaseComponent>, JsonD
             registerTypeAdapter( TranslatableComponent.class, new TranslatableComponentSerializer() ).
             create();
 
+    public final static ThreadLocal<HashSet<BaseComponent>> serializedComponents = new ThreadLocal<HashSet<BaseComponent>>()
+    {
+        @Override
+        protected HashSet<BaseComponent> initialValue()
+        {
+            return new HashSet<>();
+        }
+    };
+
     public static BaseComponent[] parse(String json)
     {
         if ( json.startsWith( "[" ) )
@@ -64,6 +74,11 @@ public class ComponentSerializer implements JsonSerializer<BaseComponent>, JsonD
     @Override
     public JsonElement serialize(BaseComponent src, Type typeOfSrc, JsonSerializationContext context)
     {
-        return context.serialize( src, src.getClass() );
+        try {
+            return context.serialize( src, src.getClass() );
+        } finally
+        {
+            serializedComponents.get().clear();
+        }
     }
 }

proxy/src/test/java/net/md_5/bungee/chat/ComponentsTest.java

@@ -80,4 +80,22 @@ public class ComponentsTest
                 + "World" + ChatColor.YELLOW + ChatColor.BOLD + "!", BaseComponent.toLegacyText( components ) );
     }
 
+    @Test(expected = IllegalArgumentException.class)
+    public void testLoopSimple() {
+        TextComponent component = new TextComponent( "Testing" );
+        component.addExtra( component );
+        ComponentSerializer.toString( component );
+    }
+
+    @Test(expected = IllegalArgumentException.class)
+    public void testLoopComplex() {
+        TextComponent a = new TextComponent( "A" );
+        TextComponent b = new TextComponent( "B" );
+        TextComponent c = new TextComponent( "C" );
+        a.addExtra( b );
+        b.addExtra( c );
+        c.addExtra( a );
+        ComponentSerializer.toString( a );
+    }
+
 }