Refactor trusted mod checking code

src/script/cpp_api/s_security.cpp

@@ -27,6 +27,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 
 #include <cerrno>
 #include <string>
+#include <algorithm>
 #include <iostream>
 
 
@@ -604,6 +605,38 @@ bool ScriptApiSecurity::checkPath(lua_State *L, const char *path,
 	return false;
 }
 
+bool ScriptApiSecurity::checkWhitelisted(lua_State *L, const std::string &setting)
+{
+	assert(str_starts_with(setting, "secure."));
+
+	// We have to make sure that this function is being called directly by
+	// a mod, otherwise a malicious mod could override this function and
+	// steal its return value.
+	lua_Debug info;
+
+	// Make sure there's only one item below this function on the stack...
+	if (lua_getstack(L, 2, &info))
+		return false;
+	FATAL_ERROR_IF(!lua_getstack(L, 1, &info), "lua_getstack() failed");
+	FATAL_ERROR_IF(!lua_getinfo(L, "S", &info), "lua_getinfo() failed");
+
+	// ...and that that item is the main file scope.
+	if (strcmp(info.what, "main") != 0)
+		return false;
+
+	// Mod must be listed in secure.http_mods or secure.trusted_mods
+	lua_rawgeti(L, LUA_REGISTRYINDEX, CUSTOM_RIDX_CURRENT_MOD_NAME);
+	if (!lua_isstring(L, -1))
+		return false;
+	std::string mod_name = readParam<std::string>(L, -1);
+
+	std::string value = g_settings->get(setting);
+	value.erase(std::remove(value.begin(), value.end(), ' '), value.end());
+	auto mod_list = str_split(value, ',');
+
+	return CONTAINS(mod_list, mod_name);
+}
+
 
 int ScriptApiSecurity::sl_g_dofile(lua_State *L)
 {