remove UE on S1AP Release Request if MME S1AP UE ID hasn't been assigned yet

srsenb/src/stack/rrc/rrc_ue.cc

@@ -386,8 +386,10 @@ void rrc::ue::handle_rrc_con_req(rrc_conn_request_s* msg)
     for (auto& user : parent->users) {
       if (user.first != rnti && user.second->has_tmsi && user.second->mmec == mmec && user.second->m_tmsi == m_tmsi) {
         parent->logger.info("RRC connection request: UE context already exists. M-TMSI=%d", m_tmsi);
-        parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost);
-        parent->rem_user_thread(user.first);
+        if (parent->s1ap->user_release(rnti, asn1::s1ap::cause_radio_network_opts::radio_conn_with_ue_lost)) {
+          // Do not wait for MME response
+          parent->rem_user_thread(user.first);
+        }
         break;
       }
     }

srsenb/src/stack/upper/s1ap.cc

@@ -418,7 +418,7 @@ bool s1ap::user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_r
     return false;
   }
 
-  if (u->was_uectxtrelease_requested()) {
+  if (u->was_uectxtrelease_requested() or not u->ctxt.mme_ue_s1ap_id.has_value()) {
     logger.warning("UE context for RNTI:0x%x is in zombie state. Releasing...", rnti);
     users.erase(u);
     rrc->release_ue(rnti);
@@ -428,10 +428,7 @@ bool s1ap::user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_r
   cause_c cause;
   cause.set_radio_network().value = cause_radio.value;
 
-  if (u->ctxt.mme_ue_s1ap_id.has_value()) {
-    return u->send_uectxtreleaserequest(cause);
-  }
-  return true;
+  return u->send_uectxtreleaserequest(cause);
 }
 
 bool s1ap::user_exists(uint16_t rnti)