From 4543311d5d5d8c3d177b684ada0212781cef11c0 Mon Sep 17 00:00:00 2001
From: WinterSolstice8 <60417494+wintersolstice8@users.noreply.github.com>
Date: Thu, 2 Apr 2026 11:08:44 -0600
Subject: [PATCH] [core] Filter additional bad equip packets

Also emit the "you cant dual wield that" message when appropriate
---
 src/map/enums/msg_basic.h   |  1 +
 src/map/utils/charutils.cpp | 85 ++++++++++++++++++++++++++++++++++++-
 2 files changed, 85 insertions(+), 1 deletion(-)

diff --git a/src/map/enums/msg_basic.h b/src/map/enums/msg_basic.h
index b492c688907..3390bb7dc49 100644
--- a/src/map/enums/msg_basic.h
+++ b/src/map/enums/msg_basic.h
@@ -63,6 +63,7 @@ enum class MsgBasic : uint16_t
     LoseSight                       = 36,  // You lose sight of <target>.
     TooFarForExp                    = 37,  // You are too far from the battle to gain experience.
     SkillGain                       = 38,  // <target>'s <skill> skill rises X points.
+    NeedDualWield                   = 39,  // You need the Dual Wield ability to equip <name of item> as a sub-weapon
     CannotInThisArea                = 40,  // cannot use in this area
     ReadiesWeaponskill              = 43,  // <entity> readies <skill>.
     SpikesEffectDmg                 = 44,  // <target>'s spikes deal <number> damage to <attacker>
diff --git a/src/map/utils/charutils.cpp b/src/map/utils/charutils.cpp
index 85b9ffbd4f6..18f0b81fb4e 100644
--- a/src/map/utils/charutils.cpp
+++ b/src/map/utils/charutils.cpp
@@ -3140,7 +3140,72 @@ void EquipItem(CCharEntity* PChar, uint8 slotID, uint8 equipSlotID, uint8 contai
         return;
     }
 
-    // if player attempts to change thier ranged weapon during a ranged state then prevent equip
+    // slotID of zero = unequip
+    if (slotID > 0)
+    {
+        // skip the rest of the function if we are trying to equip the same item to a different slot
+        switch (static_cast<SLOTTYPE>(equipSlotID))
+        {
+            case SLOT_MAIN:
+            {
+                auto PSub = PChar->getEquip(SLOT_SUB);
+                if (PItem == PSub)
+                {
+                    return;
+                }
+                break;
+            }
+            case SLOT_SUB:
+            {
+                auto PMain = PChar->getEquip(SLOT_MAIN);
+                if (PItem == PMain)
+                {
+                    return;
+                }
+                break;
+            }
+            case SLOT_EAR1:
+            {
+                auto PEar2 = PChar->getEquip(SLOT_EAR2);
+                if (PItem == PEar2)
+                {
+                    return;
+                }
+                break;
+            }
+            case SLOT_EAR2:
+            {
+                auto PEar1 = PChar->getEquip(SLOT_EAR1);
+                if (PItem == PEar1)
+                {
+                    return;
+                }
+                break;
+            }
+            case SLOT_RING1:
+            {
+                auto PRing2 = PChar->getEquip(SLOT_RING2);
+                if (PItem == PRing2)
+                {
+                    return;
+                }
+                break;
+            }
+            case SLOT_RING2:
+            {
+                auto PRing1 = PChar->getEquip(SLOT_RING1);
+                if (PItem == PRing1)
+                {
+                    return;
+                }
+                break;
+            }
+            default:
+                break;
+        }
+    }
+
+    // if player attempts to change their ranged weapon during a ranged state then prevent equip
     // this prevents players from starting a RA with short delay x-bow and ending with high dmg longbow
     if (equipSlotID == SLOT_RANGED || (equipSlotID == SLOT_AMMO && !PChar->getEquip(SLOT_RANGED)))
     {
@@ -3154,12 +3219,30 @@ void EquipItem(CCharEntity* PChar, uint8 slotID, uint8 equipSlotID, uint8 contai
     {
         auto PItemWeapon = dynamic_cast<CItemWeapon*>(PItem);
         auto PMainItem   = dynamic_cast<CItemWeapon*>(PChar->getEquip(SLOT_MAIN));
+
         if (PItemWeapon && PItemWeapon->getSkillType() == SKILL_NONE && (!PMainItem || !PMainItem->isTwoHanded()))
         {
             PChar->pushPacket<GP_SERV_COMMAND_BATTLE_MESSAGE>(PChar, PChar, 0, 0, MsgBasic::Requires2HForGrip);
             return;
         }
 
+        if (PItemWeapon && PItemWeapon->getSkillType() != SKILL_NONE)
+        {
+            // Don't attempt to equip item in equip menu if you don't have dual wield trait (client sees BLU, THF, DNC, NIN, /DNC or /NIN etc as able to equip sub weapons even if sub is too low or no trait on BLU)
+            if (!PChar->hasTrait(TRAIT_DUAL_WIELD))
+            {
+                PChar->pushPacket<GP_SERV_COMMAND_BATTLE_MESSAGE>(PChar, PChar, PItemWeapon->getID(), 0, MsgBasic::NeedDualWield);
+                return;
+            }
+
+            // Don't allow Dual Wield injections to offhand when you dont have a mainahdn (this was visual only)
+            // Don't allow non-shields in offhand with no weapon
+            if ((PMainItem && PMainItem->isTwoHanded()) || !PMainItem)
+            {
+                return;
+            }
+        }
+
         // Disallow everything but shields if you're using H2H
         // Equipping a shield will unequip the H2H weapon and you will go barefisted with a shield
         if (PMainItem && PMainItem->getSkillType() == SKILL_HAND_TO_HAND)