Merge remote-tracking branch 'origin/hack-exit-gnb-when-no-enb-nsa' into integration_2021_wk18_a

ci-scripts/auto_start_gnb.sh

+#!/bin/bash
+while true
+do
+  echo "gNB will be started automatically..."
+  sleep 1
+  sudo .././cmake_targets/ran_build/build/nr-softmodem -E -O ../targets/PROJECTS/GENERIC-LTE-EPC/CONF/testing_gnb.conf
+done

openair2/X2AP/x2ap_eNB.c

@@ -130,6 +130,18 @@ void x2ap_eNB_handle_sctp_association_resp(instance_t instance, sctp_new_associa
   DevAssert(x2ap_enb_data_p != NULL);
   dump_trees();
 
+  /* gNB: exit if connection to eNB failed - to be modified if needed.
+   * We may want to try to connect over and over again until we succeed
+   * but the modifications to the code to get this behavior are complex.
+   * Exit on error is a simple solution that can be caught by a script
+   * for example.
+   */
+  if (instance_p->cell_type == CELL_MACRO_GNB
+      && sctp_new_association_resp->sctp_state == SCTP_STATE_UNREACHABLE) {
+    X2AP_ERROR("association with eNB failed, is it running? If no, run it first. If yes, check IP addresses in your configuration file.\n");
+    exit(1);
+  }
+
   if (sctp_new_association_resp->sctp_state != SCTP_STATE_ESTABLISHED) {
     X2AP_WARN("Received unsuccessful result for SCTP association (%u), instance %ld, cnx_id %u\n",
               sctp_new_association_resp->sctp_state,