core: new option BUILD_NEW_LOCAL_VIA to recreate the local via

- to be used from tm uac when a local-generated request has to update
the via header following the event route execution

src/core/msg_translator.c

@@ -1971,7 +1971,7 @@ int check_boundaries(struct sip_msg *msg, struct dest_info *send_info)
   * depending on the presence of the BUILD_IN_SHM flag, needs freeing when
   *   done) and sets returned_len or 0 on error.
   */
-char * build_req_buf_from_sip_req( struct sip_msg* msg,
+char * build_req_buf_from_sip_req(struct sip_msg* msg,
 								unsigned int *returned_len,
 								struct dest_info* send_info,
 								unsigned int mode)
@@ -1987,6 +1987,7 @@ char * build_req_buf_from_sip_req( struct sip_msg* msg,
 	unsigned int offset, s_offset, size;
 	struct lump* via_anchor;
 	struct lump* via_lump;
+	struct lump* via_rm;
 	struct lump* via_insert_param;
 	struct lump* path_anchor;
 	struct lump* path_lump;
@@ -2032,11 +2033,22 @@ char * build_req_buf_from_sip_req( struct sip_msg* msg,
 
 	via_anchor=anchor_lump(msg, msg->via1->hdr.s-buf, 0, HDR_VIA_T);
 	if (unlikely(via_anchor==0)) goto error00;
-	line_buf = create_via_hf( &via_len, msg, send_info, &branch);
+	line_buf = create_via_hf(&via_len, msg, send_info, &branch);
 	if (unlikely(!line_buf)){
 		LM_ERR("could not create Via header\n");
 		goto error00;
 	}
+	if(unlikely(mode&BUILD_NEW_LOCAL_VIA)) {
+		/* delete exiting top Via header */
+		via_rm = del_lump(msg, msg->h_via1->name.s - msg->buf,
+				msg->h_via1->len, 0);
+		if (via_rm==0) {
+			LM_ERR("failed to remove exiting Via header\n");
+			goto error00;
+		}
+		/* do not update old Via header anymore */
+		mode |= BUILD_NO_VIA1_UPDATE;
+	}
 after_local_via:
 	if(unlikely(mode&BUILD_NO_VIA1_UPDATE))
 		goto after_update_via1;

src/core/msg_translator.h

@@ -49,6 +49,7 @@
 #define BUILD_NO_LOCAL_VIA		(1<<0)
 #define BUILD_NO_VIA1_UPDATE	(1<<1)
 #define BUILD_NO_PATH			(1<<2)
+#define BUILD_NEW_LOCAL_VIA		(1<<3)
 #define BUILD_IN_SHM			(1<<7)
 
 #include "parser/msg_parser.h"