Limit number of Loki ring offsets and prevent cost calculation overflow

Fixes #4681 by restricting the number of offsets to prevent the ring's NBT data from exceeding protocol limits. This also contains a fix to a potential integer overflow in the mana calculation that can happen within intended use of the ring already.

Xplat/src/main/java/vazkii/botania/common/item/relic/RingOfLokiItem.java

@@ -14,6 +14,7 @@
 import net.minecraft.core.BlockPos;
 import net.minecraft.core.Direction;
 import net.minecraft.nbt.CompoundTag;
+import net.minecraft.network.chat.Component;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.util.Mth;
 import net.minecraft.world.InteractionHand;
@@ -52,6 +53,11 @@
 
 public class RingOfLokiItem extends RelicBaubleItem implements WireframeCoordinateListProvider {
 
+	/**
+	 * This limit exists to prevent players from accidentally NBT-banning themselves from a world or server.
+	 * TODO 1.21: It might be possible to increase this if the storage tag structure is optimized.
+	 */
+	private static final int MAX_NUM_CURSORS = 1023;
 	private static final String TAG_CURSOR_LIST = "cursorList";
 	private static final String TAG_CURSOR_PREFIX = "cursor";
 	private static final String TAG_CURSOR_COUNT = "cursorCount";
@@ -99,7 +105,11 @@ public static InteractionResult onPlayerInteract(Player player, Level world, Int
 
 						boolean removed = cursors.remove(relPos);
 						if (!removed) {
-							cursors.add(relPos);
+							if (cursors.size() < MAX_NUM_CURSORS) {
+								cursors.add(relPos);
+							} else {
+								player.displayClientMessage(Component.translatable("botaniamisc.lokiRingLimitReached"), true);
+							}
 						}
 						setCursorList(lokiRing, cursors);
 					}
@@ -108,7 +118,9 @@ public static InteractionResult onPlayerInteract(Player player, Level world, Int
 
 			return InteractionResult.SUCCESS;
 		} else {
-			int cost = Math.min(cursors.size(), (int) Math.pow(Math.E, cursors.size() * 0.25));
+			int numCursors = cursors.size();
+			// particularly large cursor counts can overflow after exponentiation
+			int cost = numCursors > 10 ? numCursors : Math.min(numCursors, (int) Math.pow(Math.E, numCursors * 0.25));
 			ItemStack original = stack.copy();
 			int successes = 0;
 			for (BlockPos cursor : cursors) {

Xplat/src/main/resources/assets/botania/lang/en_us.json

@@ -131,6 +131,7 @@
   "botaniamisc.invalidDodge": "Invalid Dodge Packet",
   "botaniamisc.rannuncarpus.state_sensitive": "Match Exact State",
   "botaniamisc.rannuncarpus.state_insensitive": "Match Block Only",
+  "botaniamisc.lokiRingLimitReached": "Selection limit reached",
 
   "botania.tater_birthday.0": "Wow, is this for me?",
   "botania.tater_birthday.1": "It's my birthday today; I'm %d years old now!",

web/changelog.md

@@ -35,6 +35,7 @@ and start a new "Upcoming" section.
   * Missing lookup references for derivatives of certain decorative blocks (e.g. quartz variants) have been added for the quick-lookup feature while holding the book
   * Lexica Botania acknowledges that Trinkets are used on Fabric instead of Curios
   * Various entries were updated to match recent changes and fix old errors
+* Change: The Ring of Loki now has a (reasonably high) selection limit to prevent players from accidentally "NBT-banning" themselves from their world or server by going too hard with it
 * Remove: Config option `orechidPriorityMods` didn't have any effect since 1.16, never made it to Fabric, and is now gone in the Forge version as well; pack authors should use data pack recipes to define Orechid outputs and weights
 * Fix: Flight bar for Flügel Tiara no longer overlaps with the refilling air bubbles indicator or the mount health bar, if that uses more than one row
 * Fix: The Manaseer Monocle's flower radius indicator no longer jumps around if you are very far from the world origin, and should also not Z-fight with the binding radius indicator of luminizers anymore
@@ -47,6 +48,7 @@ and start a new "Upcoming" section.
 * Fix: Floating flower islands properly show the soil type on Forge, and are no longer invisible in Patchouli multiblock visualizations (although that latter part is merely a workaround for a Patchouli issue at the moment)
 * Fix: Position of the binding information icon on flowers' wand HUD has been adjusted to not overlap with longer flower names
 * Fix: Suspicious stew effect from Pure Daisy actually works now, clearing all active status effects
+* Fix: Potential integer overflow in Ring of Loki mana calculation
 
 ---