From 7831ed6ca113913bc8a54cf996cdb485dcf590ac Mon Sep 17 00:00:00 2001
From: staphen <staphen@gmail.com>
Date: Wed, 23 Apr 2025 23:04:10 -0400
Subject: [PATCH] Isolate monster sync packet validation using Monsters array

---
 Source/msg.cpp  |  1 +
 Source/sync.cpp | 45 +++++++++++++++++++++++++--------------------
 2 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/Source/msg.cpp b/Source/msg.cpp
index cd9612395..c6c1f573e 100644
--- a/Source/msg.cpp
+++ b/Source/msg.cpp
@@ -26,6 +26,7 @@
 #include "engine/random.hpp"
 #include "engine/world_tile.hpp"
 #include "gamemenu.h"
+#include "items/validation.h"
 #include "levels/crypt.h"
 #include "levels/town.h"
 #include "levels/trigs.h"
diff --git a/Source/sync.cpp b/Source/sync.cpp
index 199ed651e..fb4fb8901 100644
--- a/Source/sync.cpp
+++ b/Source/sync.cpp
@@ -205,29 +205,18 @@ void SyncMonster(bool isOwner, const TSyncMonster &monsterSync)
 	monster.whoHit |= monsterSync.mWhoHit;
 }
 
-bool IsEnemyIdValid(const Monster &monster, uint8_t enemyId)
+bool IsEnemyIdValid(uint8_t enemyId)
 {
-	if (enemyId > MaxMonsters) {
-		enemyId -= MaxMonsters;
-		if (enemyId >= Players.size())
-			return false;
-		return Players[enemyId].plractive;
-	}
-
-	const Monster &enemy = Monsters[enemyId];
+	if (enemyId < MaxMonsters)
+		return true;
 
-	if (&enemy == &monster) {
+	enemyId -= MaxMonsters;
+	if (enemyId >= Players.size())
 		return false;
-	}
-
-	if (enemy.hitPoints <= 0) {
-		return false;
-	}
-
-	return true;
+	return Players[enemyId].plractive;
 }
 
-bool IsTSyncMonsterValidate(const TSyncMonster &monsterSync)
+bool IsTSyncMonsterValid(const TSyncMonster &monsterSync)
 {
 	const size_t monsterId = monsterSync._mndx;
 
@@ -237,12 +226,26 @@ bool IsTSyncMonsterValidate(const TSyncMonster &monsterSync)
 	if (!InDungeonBounds({ monsterSync._mx, monsterSync._my }))
 		return false;
 
-	if (!IsEnemyIdValid(Monsters[monsterId], monsterSync._menemy))
+	if (!IsEnemyIdValid(monsterSync._menemy))
 		return false;
 
 	return true;
 }
 
+bool IsTSyncEnemyValid(const TSyncMonster &monsterSync)
+{
+	const size_t enemyId = monsterSync._menemy;
+	if (enemyId >= MaxMonsters)
+		return true;
+
+	const size_t monsterId = monsterSync._mndx;
+	if (enemyId == monsterId)
+		return false;
+
+	const Monster &enemy = Monsters[enemyId];
+	return enemy.hitPoints > 0;
+}
+
 } // namespace
 
 size_t sync_all_monsters(std::byte *pbBuf, size_t dwMaxLen)
@@ -314,10 +317,12 @@ uint32_t OnSyncData(const TCmd *pCmd, const Player &player)
 		bool isOwner = player.getId() > MyPlayerId;
 
 		for (int i = 0; i < monsterCount; i++) {
-			if (!IsTSyncMonsterValidate(monsterSyncs[i]))
+			if (!IsTSyncMonsterValid(monsterSyncs[i]))
 				continue;
 
 			if (syncLocalLevel) {
+				if (!IsTSyncEnemyValid(monsterSyncs[i]))
+					continue;
 				SyncMonster(isOwner, monsterSyncs[i]);
 			}