From b1247748157ccdc9a40c6255ece4e5d64f71c6a4 Mon Sep 17 00:00:00 2001
From: Vsevolod Stakhov <vsevolod@highsecure.ru>
Date: Thu, 5 May 2016 14:24:16 +0100
Subject: [PATCH] [Feature] Add better method to check lua userdata types

---
 src/lua/lua_common.c | 79 +++++++++++++++++++++++++++++++++++++++-----
 src/lua/lua_common.h |  9 +++++
 2 files changed, 79 insertions(+), 9 deletions(-)

diff --git a/src/lua/lua_common.c b/src/lua/lua_common.c
index e85f82d1a..63aab5830 100644
--- a/src/lua/lua_common.c
+++ b/src/lua/lua_common.c
@@ -849,24 +849,30 @@ rspamd_lua_parse_table_arguments (lua_State *L, gint pos,
 	return TRUE;
 }
 
-gint
-rspamd_lua_traceback (lua_State *L)
+static void
+rspamd_lua_traceback_string (lua_State *L, GString *s)
 {
-	lua_Debug d;
-	GString *tb;
-	const gchar *msg = lua_tostring (L, 1);
 	gint i = 1;
-
-	tb = g_string_sized_new (100);
-	g_string_append_printf (tb, "%s; trace:", msg);
+	lua_Debug d;
 
 	while (lua_getstack (L, i++, &d)) {
 		lua_getinfo (L, "nSl", &d);
-		g_string_append_printf (tb, " [%d]:{%s:%d - %s [%s]};",
+		g_string_append_printf (s, " [%d]:{%s:%d - %s [%s]};",
 				i - 1, d.short_src, d.currentline,
 				(d.name ? d.name : "<unknown>"), d.what);
 	}
+}
+
+gint
+rspamd_lua_traceback (lua_State *L)
+{
+
+	GString *tb;
+	const gchar *msg = lua_tostring (L, 1);
 
+	tb = g_string_sized_new (100);
+	g_string_append_printf (tb, "%s; trace:", msg);
+	rspamd_lua_traceback_string (L, tb);
 	lua_pushlightuserdata (L, tb);
 
 	return 1;
@@ -985,3 +991,58 @@ lua_push_internet_address_list (lua_State *L, InternetAddressList *addrs)
 	}
 #endif
 }
+
+
+void *
+rspamd_lua_check_udata (lua_State *L, gint pos, const gchar *classname)
+{
+	void *p = lua_touserdata (L, pos);
+	GString *err_msg;
+
+	if (p == NULL) {
+		err_msg = g_string_sized_new (100);
+		rspamd_printf_gstring (err_msg, "expected %s at %d, but got %s; trace: ",
+				classname, pos, lua_typename (L, lua_type (L, pos)));
+		rspamd_lua_traceback_string (L, err_msg);
+		msg_err ("lua typecheck error: %v", err_msg);
+		g_string_free (err_msg, TRUE);
+	}
+	else {
+		/* Match class */
+		if (lua_getmetatable (L, pos)) {
+			luaL_getmetatable (L, classname);
+
+			if (!lua_rawequal (L, -1, -2)) {
+				p = NULL;
+				lua_pushstring (L, "__index");
+				lua_gettable (L, -3);
+				lua_pushstring (L, "class");
+				lua_gettable (L, -2);
+
+				err_msg = g_string_sized_new (100);
+				rspamd_printf_gstring (err_msg, "expected %s at %d, but userdata has "
+						"classname: %s; trace: ",
+						classname, pos, lua_tostring (L, -1));
+				rspamd_lua_traceback_string (L, err_msg);
+				msg_err ("lua typecheck error: %v", err_msg);
+				g_string_free (err_msg, TRUE);
+
+				lua_pop (L, 2); /* __index -> classname */
+			}
+
+			lua_pop (L, 2);
+		}
+		else {
+			p = NULL;
+			err_msg = g_string_sized_new (100);
+			rspamd_printf_gstring (err_msg, "expected %s at %d, but userdata has "
+					"no metatable; trace: ",
+					classname, pos);
+			rspamd_lua_traceback_string (L, err_msg);
+			msg_err ("lua typecheck error: %v", err_msg);
+			g_string_free (err_msg, TRUE);
+		}
+	}
+
+	return p;
+}
diff --git a/src/lua/lua_common.h b/src/lua/lua_common.h
index 73be9e0c5..63039533c 100644
--- a/src/lua/lua_common.h
+++ b/src/lua/lua_common.h
@@ -346,5 +346,14 @@ gboolean lua_push_internet_address (lua_State *L, InternetAddress *ia);
  */
 gsize lua_logger_out_type (lua_State *L, gint pos, gchar *outbuf,
 		gsize len);
+
+/**
+ * Safely checks userdata to match specified class
+ * @param L
+ * @param pos
+ * @param classname
+ */
+void *rspamd_lua_check_udata (lua_State *L, gint pos, const gchar *classname);
+
 #endif /* WITH_LUA */
 #endif /* RSPAMD_LUA_H */
-- 
2.39.5