FST: Fix Session Transition element length field value

The Element ID and Length subfields are not supposed to be included in
the Length. In addition, both of these subfields needs to be filled in
even for non-zero status code cases.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/fst/fst_session.c

@@ -893,7 +893,7 @@ int fst_session_initiate_setup(struct fst_session *s)
 	req.llt = host_to_le32(FST_LLT_MS_TO_VAL(s->data.llt_ms));
 	/* 8.4.2.147 Session Transition element */
 	req.stie.element_id = WLAN_EID_SESSION_TRANSITION;
-	req.stie.length = sizeof(req.stie);
+	req.stie.length = sizeof(req.stie) - 2;
 	req.stie.fsts_id = host_to_le32(fsts_id);
 	req.stie.session_control = SESSION_CONTROL(SESSION_TYPE_BSS, 0);
 
@@ -968,9 +968,10 @@ int fst_session_respond(struct fst_session *s, u8 status_code)
 	res.dialog_token = s->data.pending_setup_req_dlgt;
 	res.status_code = status_code;
 
+	res.stie.element_id = WLAN_EID_SESSION_TRANSITION;
+	res.stie.length = sizeof(res.stie) - 2;
+
 	if (status_code == WLAN_STATUS_SUCCESS) {
-		res.stie.element_id = WLAN_EID_SESSION_TRANSITION;
-		res.stie.length = sizeof(res.stie);
 		res.stie.fsts_id = s->data.fsts_id;
 		res.stie.session_control = SESSION_CONTROL(SESSION_TYPE_BSS, 0);
 
@@ -1374,7 +1375,7 @@ int fst_test_req_send_fst_request(const char *params)
 	req.llt = host_to_le32(FST_LLT_MS_DEFAULT);
 	/* 8.4.2.147 Session Transition element */
 	req.stie.element_id = WLAN_EID_SESSION_TRANSITION;
-	req.stie.length = sizeof(req.stie);
+	req.stie.length = sizeof(req.stie) - 2;
 	req.stie.fsts_id = host_to_le32(fsts_id);
 	req.stie.session_control = SESSION_CONTROL(SESSION_TYPE_BSS, 0);
 
@@ -1443,9 +1444,10 @@ int fst_test_req_send_fst_response(const char *params)
 		_s->data.pending_setup_req_dlgt : g->dialog_token;
 	res.status_code  = status_code;
 
+	res.stie.element_id = WLAN_EID_SESSION_TRANSITION;
+	res.stie.length = sizeof(res.stie) - 2;
+
 	if (res.status_code == WLAN_STATUS_SUCCESS) {
-		res.stie.element_id = WLAN_EID_SESSION_TRANSITION;
-		res.stie.length = sizeof(res.stie);
 		res.stie.fsts_id = fsts_id;
 		res.stie.session_control = SESSION_CONTROL(SESSION_TYPE_BSS, 0);