--- /dev/null
+commit 281a6c6b6eaaf30058b603325e8ded20b99e1456
+Author: Henning Westerholt <hw@kamailio.org>
+Date: Mon May 7 09:36:53 2018 +0200
+
+ core: improve to header check guards, str consists of length and pointer
+
+diff --git a/src/core/msg_translator.c b/src/core/msg_translator.c
+index 22122768a..4dd648e87 100644
+--- a/src/core/msg_translator.c
++++ b/src/core/msg_translator.c
+@@ -2369,7 +2369,7 @@ char * build_res_buf_from_sip_req( unsigned int code, str *text ,str *new_tag,
+ case HDR_TO_T:
+ if (new_tag && new_tag->len) {
+ to_tag=get_to(msg)->tag_value;
+- if ( to_tag.len || to_tag.s )
++ if ( to_tag.len && to_tag.s )
+ len+=new_tag->len-to_tag.len;
+ else
+ len+=new_tag->len+TOTAG_TOKEN_LEN/*";tag="*/;
+@@ -2497,7 +2497,7 @@ char * build_res_buf_from_sip_req( unsigned int code, str *text ,str *new_tag,
+ break;
+ case HDR_TO_T:
+ if (new_tag && new_tag->len){
+- if (to_tag.s ) { /* replacement */
++ if (to_tag.len && to_tag.s) { /* replacement */
+ /* before to-tag */
+ append_str( p, hdr->name.s, to_tag.s-hdr->name.s);
+ /* to tag replacement */