[Minor] Fix pushing empty strings

diff --git a/src/libmime/received.cxx b/src/libmime/received.cxx
index b4b3c76e9230bb588b7b17bab1edaaa5414140d3..836af0464c1c316d19596f99f3394fdb99b9949b 100644 (file)
--- a/src/libmime/received.cxx
+++ b/src/libmime/received.cxx
@@ -765,16 +765,21 @@ received_export_to_lua(received_header_chain *chain, lua_State *L) -> bool
                push_flag(rh, received_flags::SSL, "ssl");
                lua_setfield(L, -2, "flags");
 
-               lua_pushlstring(L, rh.from_hostname.data(), rh.from_hostname.size());
-               lua_setfield(L, -2, "from_hostname");
-               lua_pushlstring(L, rh.real_hostname.data(), rh.real_hostname.size());
-               lua_setfield(L, -2, "real_hostname");
-               lua_pushlstring(L, rh.real_ip.data(), rh.real_ip.size());
-               lua_setfield(L, -2, "from_ip");
-               lua_pushlstring(L, rh.by_hostname.data(), rh.by_hostname.size());
-               lua_setfield(L, -2, "by_hostname");
-               lua_pushlstring(L, rh.for_mbox.data(), rh.for_mbox.size());
-               lua_setfield(L, -2, "for");
+               auto push_nullable_string = [L](const mime_string &st, const char *field) {
+                       if (st.empty()) {
+                               lua_pushnil(L);
+                       }
+                       else {
+                               lua_pushlstring(L, st.data(), st.size());
+                       }
+                       lua_setfield(L, -2, field);
+               };
+
+               push_nullable_string(rh.from_hostname, "from_hostname");
+               push_nullable_string(rh.real_hostname, "real_hostname");
+               push_nullable_string(rh.real_ip, "from_ip");
+               push_nullable_string(rh.by_hostname, "by_hostname");
+               push_nullable_string(rh.for_mbox, "for");
 
                rspamd_lua_ip_push (L, rh.addr);
                lua_setfield(L, -2, "real_ip");