commit 030873c: [Minor] Fix pushing empty strings

[Vsevolod Stakhov]

Author: Vsevolod Stakhov
Date: 2021-10-07 08:39:57 +0100
URL: https://github.com/rspamd/rspamd/commit/030873c19f9c15d37e52243962abbdb85b86a245 (HEAD -> master)

[Minor] Fix pushing empty strings

---
 src/libmime/received.cxx | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/src/libmime/received.cxx b/src/libmime/received.cxx
index b4b3c76e9..836af0464 100644
--- 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");