From 91eef646a59575bd9ae792e257bb6ad12fafc0b1 Mon Sep 17 00:00:00 2001
From: sfan5 <sfan5@live.de>
Date: Tue, 11 Feb 2020 13:23:03 +0100
Subject: [PATCH] Script API: Check that SAOs are still usable before
 attempting to use them

---
 src/content_sao.cpp             |  4 ++--
 src/script/lua_api/l_object.cpp |  4 ++++
 src/server.cpp                  | 10 ++--------
 3 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/src/content_sao.cpp b/src/content_sao.cpp
index 43c784b42..5119223a7 100644
--- a/src/content_sao.cpp
+++ b/src/content_sao.cpp
@@ -864,7 +864,7 @@ PlayerSAO::PlayerSAO(ServerEnvironment *env_, RemotePlayer *player_, session_t p
 	m_peer_id(peer_id_),
 	m_is_singleplayer(is_singleplayer)
 {
-	assert(m_peer_id != 0);	// pre-condition
+	SANITY_CHECK(m_peer_id != PEER_ID_INEXISTENT);
 
 	m_prop.hp_max = PLAYER_MAX_HP_DEFAULT;
 	m_prop.breath_max = PLAYER_MAX_BREATH_DEFAULT;
@@ -1393,7 +1393,7 @@ bool PlayerSAO::setWieldedItem(const ItemStack &item)
 
 void PlayerSAO::disconnected()
 {
-	m_peer_id = 0;
+	m_peer_id = PEER_ID_INEXISTENT;
 	m_pending_removal = true;
 }
 
diff --git a/src/script/lua_api/l_object.cpp b/src/script/lua_api/l_object.cpp
index efdb345c9..f23282a95 100644
--- a/src/script/lua_api/l_object.cpp
+++ b/src/script/lua_api/l_object.cpp
@@ -60,6 +60,8 @@ LuaEntitySAO* ObjectRef::getluaobject(ObjectRef *ref)
 		return NULL;
 	if (obj->getType() != ACTIVEOBJECT_TYPE_LUAENTITY)
 		return NULL;
+	if (obj->isGone())
+		return NULL;
 	return (LuaEntitySAO*)obj;
 }
 
@@ -70,6 +72,8 @@ PlayerSAO* ObjectRef::getplayersao(ObjectRef *ref)
 		return NULL;
 	if (obj->getType() != ACTIVEOBJECT_TYPE_PLAYER)
 		return NULL;
+	if (obj->isGone())
+		return NULL;
 	return (PlayerSAO*)obj;
 }
 
diff --git a/src/server.cpp b/src/server.cpp
index f1613cffe..c1f271490 100644
--- a/src/server.cpp
+++ b/src/server.cpp
@@ -1768,10 +1768,7 @@ void Server::SendTimeOfDay(session_t peer_id, u16 time, f32 time_speed)
 void Server::SendPlayerHP(session_t peer_id)
 {
 	PlayerSAO *playersao = getPlayerSAO(peer_id);
-	// In some rare case if the player is disconnected
-	// while Lua call l_punch, for example, this can be NULL
-	if (!playersao)
-		return;
+	assert(playersao);
 
 	SendHP(peer_id, playersao->getHP());
 	m_script->player_event(playersao,"health_changed");
@@ -2701,10 +2698,7 @@ void Server::sendDetachedInventories(session_t peer_id, bool incremental)
 void Server::DiePlayer(session_t peer_id, const PlayerHPChangeReason &reason)
 {
 	PlayerSAO *playersao = getPlayerSAO(peer_id);
-	// In some rare cases this can be NULL -- if the player is disconnected
-	// when a Lua function modifies l_punch, for example
-	if (!playersao)
-		return;
+	assert(playersao);
 
 	infostream << "Server::DiePlayer(): Player "
 			<< playersao->getPlayer()->getName()