Overview

Anti-Swap Fix addresses a critical combat exploit where players can swap weapons mid-attack to gain unintended attribute bonuses. This exploit allows players to combine the attack speed of one weapon with the damage or attributes of another, creating an unfair advantage in PvP and PvE scenarios.

This mod was specifically designed for large modpack SMPs where players have access to weapons with unique attributes and special effects. In these environments, the exploit becomes particularly problematic as players can mix and match powerful modded weapon attributes, completely breaking the intended game balance and progression systems.

The Problem

In vanilla Minecraft, when a player initiates an attack, the game calculates damage and applies attributes based on the item held at the moment the attack connects, not when it was initiated. This creates a window of opportunity where players can:

Start an attack with a fast weapon (e.g., dagger with high attack speed)
Swap to a powerful weapon mid-attack (e.g., sword with high damage)
Deal damage with the powerful weapon while maintaining the attack speed of the fast weapon

This exploit is commonly known as "Attribute Swap" or "Weapon Swap" and can severely impact game balance, especially on servers with custom weapons or RPG-style combat systems.

How It Works

Anti-Swap Fix uses a simple but effective approach:

Snapshot System: At the start of each player tick, the mod records which item the player is holding
Attack Validation: When a player attempts to attack, the mod compares the current held item with the snapshot
Exploit Prevention: If the items don't match, the attack is cancelled

This "snapshot-and-validate" strategy ensures that players can only deal damage with the weapon they were actually holding when they initiated the attack.

Features

Server-Side Only: No client installation required
Lightweight: Minimal performance impact with efficient snapshot caching
Configurable: Enable/disable protection via server config or commands
Debug Mode: Optional per-player debug messages for testing and verification
Zero False Positives: Only cancels attacks when an actual swap is detected

Configuration

The mod creates a configuration file at config/antiswapfix-server.toml with the following options:

[General Settings]
    # Enables protection against the Attribute Swap exploit
    enabled = true

    # Sends debug messages to players when attacks are cancelled
    debugMode = false

Commands

All commands require operator permission (level 2).

Toggle Protection

/antiswap toggle true/false

Enables or disables the anti-swap protection.

Toggle Debug Mode

/antiswap debug true/false

Enables or disables debug messages for the player who executes the command. When enabled, you will receive detailed messages showing which items were swapped when an attack is cancelled.

Debug messages show:

The item held at the start of the tick
The item held when the attack was attempted
Color-coded information for easy identification

Compatibility

Minecraft Version: 1.20.1
Mod Loader: Forge 47.4.10+
Side: Server-side (client installation optional but not required)

Why This Mod?

In large modpack environments, the Attribute Swap exploit becomes exponentially more dangerous. Players can exploit combinations of:

High attack speed weapons from one mod with high damage weapons from another
Weapons with special effects combined with weapons that have high base damage
Enchantments and custom attributes that were never meant to work together A player with a fast dagger and a powerful greatsword can effectively have both at once, trivializing boss fights and making PvP completely unbalanced. Anti-Swap Fix provides a clean, universal solution that works with any item, any mod, and any combat system. It doesn't care about attributes, enchantments, or special effects - it simply ensures you attack with the weapon you're actually holding.

Credits

Author: SatDPhoe

AntiSwap (Attribute Swap Fix)