fix(Core/Spells): Fixed players being able to mount with all transfor… (#11767)

…m auras.

Co-authored-by: Shauren <shauren.trinity@gmail.com>

src/server/game/Entities/Unit/Unit.cpp

@@ -20669,3 +20669,58 @@ bool Unit::CanRestoreMana(SpellInfo const* spellInfo) const
 
     return false;
 }
+
+bool Unit::IsInDisallowedMountForm() const
+{
+    if (SpellInfo const* transformSpellInfo = sSpellMgr->GetSpellInfo(getTransForm()))
+    {
+        if (transformSpellInfo->HasAttribute(SPELL_ATTR0_ALLOW_WHILE_MOUNTED))
+        {
+            return false;
+        }
+    }
+
+    if (ShapeshiftForm form = GetShapeshiftForm())
+    {
+        SpellShapeshiftEntry const* shapeshift = sSpellShapeshiftStore.LookupEntry(form);
+        if (!shapeshift)
+        {
+            return true;
+        }
+
+        if (!(shapeshift->flags1 & 0x1))
+        {
+            return true;
+        }
+    }
+
+    if (GetDisplayId() == GetNativeDisplayId())
+    {
+        return false;
+    }
+
+    CreatureDisplayInfoEntry const* display = sCreatureDisplayInfoStore.LookupEntry(GetDisplayId());
+    if (!display)
+    {
+        return true;
+    }
+
+    CreatureDisplayInfoExtraEntry const* displayExtra = sCreatureDisplayInfoExtraStore.LookupEntry(display->ExtendedDisplayInfoID);
+    if (!displayExtra)
+    {
+        return true;
+    }
+
+    CreatureModelDataEntry const* model = sCreatureModelDataStore.LookupEntry(display->ModelId);
+    ChrRacesEntry const* race = sChrRacesStore.LookupEntry(displayExtra->DisplayRaceID);
+
+    if (model && !(model->HasFlag(CREATURE_MODEL_DATA_FLAGS_CAN_MOUNT)))
+    {
+        if (race && !(race->HasFlag(CHRRACES_FLAGS_CAN_MOUNT)))
+        {
+            return true;
+        }
+    }
+
+    return false;
+}