Core/Spells: Fully prevent infinite proc loops and add logging to detect most spells that could possibly trigger this behavior at startup

Port From (https://github.com/TrinityCore/TrinityCore/commit/29eac37a16df2ec14cba89f4d6e28f54ca1a4e25)

Source/Game/Entities/Unit/Unit.Fields.cs

@@ -77,7 +77,8 @@ namespace Game.Entities
         MultiMap<uint, uint>[] m_spellImmune = new MultiMap<uint, uint>[(int)SpellImmunity.Max];
         SpellAuraInterruptFlags m_interruptMask;
         SpellAuraInterruptFlags2 m_interruptMask2;
-        protected int m_procDeep;
+        int m_procDeep;               // tracked for proc system correctness (what spells should proc what)
+        int m_procChainLength;        // tracked to protect against infinite proc loops (hard limit, will disallow procs even if they should happen)
         SpellHistory _spellHistory;
 
         //Auras

Source/Game/Entities/Unit/Unit.Spells.cs

@@ -1480,6 +1480,13 @@ namespace Game.Entities
 
         public static void ProcSkillsAndAuras(Unit actor, Unit actionTarget, ProcFlagsInit typeMaskActor, ProcFlagsInit typeMaskActionTarget, ProcFlagsSpellType spellTypeMask, ProcFlagsSpellPhase spellPhaseMask, ProcFlagsHit hitMask, Spell spell, DamageInfo damageInfo, HealInfo healInfo)
         {
+            int ProcChainHardLimit = 10;
+            if (spell != null && spell.GetProcChainLength() >= ProcChainHardLimit)
+            {
+                Log.outError(LogFilter.Spells, $"Unit::ProcSkillsAndAuras: Possible infinite proc loop detected, current triggering spell {spell.GetDebugInfo()}");
+                return;
+            }
+
             WeaponAttackType attType = damageInfo != null ? damageInfo.GetAttackType() : WeaponAttackType.BaseAttack;
             if (typeMaskActor && actor != null)
                 actor.ProcSkillsAndReactives(false, actionTarget, typeMaskActor, hitMask, attType);
@@ -1625,6 +1632,11 @@ namespace Game.Entities
         {
             Spell triggeringSpell = eventInfo.GetProcSpell();
             bool disableProcs = triggeringSpell && triggeringSpell.IsProcDisabled();
+
+
+            int oldProcChainLength = m_procChainLength;
+            m_procChainLength = Math.Max(m_procChainLength + 1, triggeringSpell != null ? triggeringSpell.GetProcChainLength() : 0);
+
             if (disableProcs)
                 SetCantProc(true);
 
@@ -1638,6 +1650,8 @@ namespace Game.Entities
 
             if (disableProcs)
                 SetCantProc(false);
+
+            m_procChainLength = oldProcChainLength;
         }
 
         void SetCantProc(bool apply)
@@ -3877,6 +3891,8 @@ namespace Game.Entities
 
         public bool CanProc() { return m_procDeep == 0; }
 
+        public int GetProcChainLength() { return m_procChainLength; }
+        
         public void _ApplyAuraEffect(Aura aura, uint effIndex)
         {
             Cypher.Assert(aura != null);

Source/Game/Spells/Spell.cs

@@ -84,6 +84,7 @@ namespace Game.Spells
             m_castId = ObjectGuid.Create(HighGuid.Cast, SpellCastSource.Normal, m_caster.GetMapId(), m_spellInfo.Id, m_caster.GetMap().GenerateLowGuid(HighGuid.Cast));
             m_originalCastId = originalCastId;
             m_SpellVisual.SpellXSpellVisualID = caster.GetCastSpellXSpellVisualId(m_spellInfo);
+            m_procChainLength = caster.IsUnit() ? caster.ToUnit().GetProcChainLength() : 0;
 
             //Auto Shot & Shoot (wand)
             m_autoRepeat = m_spellInfo.IsAutoRepeatRangedSpell();
@@ -7991,6 +7992,8 @@ namespace Game.Spells
         public bool IsProcDisabled() { return _triggeredCastFlags.HasAnyFlag(TriggerCastFlags.DisallowProcEvents); }
         public bool IsChannelActive() { return m_caster.IsUnit() && m_caster.ToUnit().GetChannelSpellId() != 0; }
 
+        public int GetProcChainLength() { return m_procChainLength; }
+        
         public bool IsDeletable()
         {
             return !m_referencedFromCurrentSpell && !m_executedCurrently;
@@ -8161,6 +8164,7 @@ namespace Game.Spells
         // we can't store original aura link to prevent access to deleted auras
         // and in same time need aura data and after aura deleting.
         public SpellInfo m_triggeredByAuraSpell;
+        int m_procChainLength;
         #endregion
     }
 

Source/Game/Spells/SpellManager.cs

@@ -1518,6 +1518,7 @@ namespace Game.Entities
                 procEntry.SpellPhaseMask = ProcFlagsSpellPhase.Hit;
                 procEntry.HitMask = ProcFlagsHit.None; // uses default proc @see SpellMgr::CanSpellTriggerProcOnEvent
 
+                bool triggersSpell = false;
                 foreach (var spellEffectInfo in spellInfo.GetEffects())
                 {
                     if (!spellEffectInfo.IsAura())
@@ -1543,6 +1544,10 @@ namespace Game.Entities
                             if (spellEffectInfo.CalcValue() <= -100)
                                 procEntry.HitMask = ProcFlagsHit.Miss;
                             break;
+                        case AuraType.ProcTriggerSpell:
+                        case AuraType.ProcTriggerSpellWithValue:
+                            triggersSpell = spellEffectInfo.TriggerSpell != 0;
+                            break;
                         default:
                             continue;
                     }
@@ -1561,6 +1566,20 @@ namespace Game.Entities
                 procEntry.Cooldown = spellInfo.ProcCooldown;
                 procEntry.Charges = spellInfo.ProcCharges;
 
+                if (spellInfo.HasAttribute(SpellAttr3.CanProcFromProcs) && !procEntry.SpellFamilyMask
+                    && procEntry.Chance >= 100
+                    && spellInfo.ProcBasePPM <= 0.0f
+                    && procEntry.Cooldown <= 0
+                    && procEntry.Charges <= 0
+                    && procEntry.ProcFlags.HasFlag(ProcFlags.DealMeleeAbility | ProcFlags.DealRangedAttack | ProcFlags.DealRangedAbility | ProcFlags.DealHelpfulAbility
+                    | ProcFlags.DealHarmfulAbility | ProcFlags.DealHelpfulSpell | ProcFlags.DealHarmfulSpell | ProcFlags.DealHarmfulPeriodic | ProcFlags.DealHelpfulPeriodic)
+                    && triggersSpell)
+                {
+                    Log.outError(LogFilter.Sql, $"Spell Id {spellInfo.Id} has SPELL_ATTR3_CAN_PROC_FROM_PROCS attribute and no restriction on what spells can cause it to proc and no cooldown. " +
+                        "This spell can cause infinite proc loops. Proc data for this spell was not generated, data in `spell_proc` table is required for it to function!");
+                    continue;
+                }
+
                 mSpellProcMap[(spellInfo.Id, spellInfo.Difficulty)] = procEntry;
                 ++count;
             }