Fix issue #1009 (minetest.get_connected_players() returns non-existing players)

builtin/misc.lua

@@ -53,7 +53,9 @@ end)
 function minetest.get_connected_players()
 	local temp_table = {}
 	for index, value in pairs(player_list) do
-		table.insert(temp_table, value)
+		if value:is_player_connected() then
+			table.insert(temp_table, value)
+		end
 	end
 	return temp_table
 end

src/script/lua_api/l_object.cpp

@@ -621,6 +621,16 @@ int ObjectRef::l_is_player(lua_State *L)
 	return 1;
 }
 
+// is_player_connected(self)
+int ObjectRef::l_is_player_connected(lua_State *L)
+{
+	NO_MAP_LOCK_REQUIRED;
+	ObjectRef *ref = checkobject(L, 1);
+	Player *player = getplayer(ref);
+	lua_pushboolean(L, (player != NULL && player->peer_id != 0));
+	return 1;
+}
+
 // get_player_name(self)
 int ObjectRef::l_get_player_name(lua_State *L)
 {
@@ -1148,6 +1158,7 @@ const luaL_reg ObjectRef::methods[] = {
 	luamethod(ObjectRef, get_luaentity),
 	// Player-only
 	luamethod(ObjectRef, is_player),
+	luamethod(ObjectRef, is_player_connected),
 	luamethod(ObjectRef, get_player_name),
 	luamethod(ObjectRef, get_look_dir),
 	luamethod(ObjectRef, get_look_pitch),

src/script/lua_api/l_object.h

@@ -158,6 +158,9 @@ private:
 	// is_player(self)
 	static int l_is_player(lua_State *L);
 
+	// is_player_connected(self)
+	static int l_is_player_connected(lua_State *L);
+
 	// get_player_name(self)
 	static int l_get_player_name(lua_State *L);