From 3daaf9b356d8c412fb9db2732a6cb060e503054c Mon Sep 17 00:00:00 2001
From: Francisco Paisana <francisco.paisana@softwareradiosystems.com>
Date: Fri, 9 Dec 2022 12:50:22 +0100
Subject: [PATCH] Allow NAS PDUs to be cleared only after the Reconfiguration
 Complete is received by the eNB

---
 srsenb/hdr/stack/rrc/rrc_bearer_cfg.h  |  4 ++++
 srsenb/src/stack/rrc/rrc_bearer_cfg.cc | 18 +++++++++++++++++-
 srsenb/src/stack/rrc/rrc_ue.cc         |  3 +++
 3 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/srsenb/hdr/stack/rrc/rrc_bearer_cfg.h b/srsenb/hdr/stack/rrc/rrc_bearer_cfg.h
index 11abfa4cd..fb8e8fc7a 100644
--- a/srsenb/hdr/stack/rrc/rrc_bearer_cfg.h
+++ b/srsenb/hdr/stack/rrc/rrc_bearer_cfg.h
@@ -114,6 +114,7 @@ public:
                                              const gtpu_interface_rrc::bearer_props* props = nullptr);
   void                       rem_gtpu_bearer(uint32_t erab_id);
   void                       fill_pending_nas_info(asn1::rrc::rrc_conn_recfg_r8_ies_s* msg);
+  void                       clear_pending_nas_info();
 
   const std::map<uint8_t, erab_t>&        get_erabs() const { return erabs; }
   const asn1::rrc::drb_to_add_mod_list_l& get_established_drbs() const { return current_drbs; }
@@ -127,6 +128,9 @@ private:
   const rrc_cfg_t*      cfg  = nullptr;
   gtpu_interface_rrc*   gtpu = nullptr;
 
+  // NAS PDUs being currently sent.
+  std::vector<uint32_t> erab_ids_with_pending_nas_pdus;
+
   // last cfg
   asn1::rrc::drb_to_add_mod_list_l current_drbs;
 };
diff --git a/srsenb/src/stack/rrc/rrc_bearer_cfg.cc b/srsenb/src/stack/rrc/rrc_bearer_cfg.cc
index cb1fb3ee2..8d54b0301 100644
--- a/srsenb/src/stack/rrc/rrc_bearer_cfg.cc
+++ b/srsenb/src/stack/rrc/rrc_bearer_cfg.cc
@@ -417,6 +417,8 @@ void bearer_cfg_handler::fill_pending_nas_info(asn1::rrc::rrc_conn_recfg_r8_ies_
   // DRBs have already been configured in GTPU during bearer setup
   // Add E-RAB info message for the E-RABs
   if (msg->rr_cfg_ded.drb_to_add_mod_list_present) {
+    erab_ids_with_pending_nas_pdus.clear();
+
     for (const drb_to_add_mod_s& drb : msg->rr_cfg_ded.drb_to_add_mod_list) {
       uint32_t lcid    = drb_to_lcid((lte_drb)drb.drb_id);
       auto     erab_it = std::find_if(
@@ -429,7 +431,7 @@ void bearer_cfg_handler::fill_pending_nas_info(asn1::rrc::rrc_conn_recfg_r8_ies_
         msg->ded_info_nas_list.push_back({});
         msg->ded_info_nas_list.back().resize(erab_info.size());
         memcpy(msg->ded_info_nas_list.back().data(), &erab_info[0], erab_info.size());
-        erab_info_list.erase(info_it);
+        erab_ids_with_pending_nas_pdus.push_back(erab_id);
       } else {
         logger->warning("Not adding NAS message to connection reconfiguration. E-RAB id %d", erab_id);
       }
@@ -438,4 +440,18 @@ void bearer_cfg_handler::fill_pending_nas_info(asn1::rrc::rrc_conn_recfg_r8_ies_
   }
 }
 
+void bearer_cfg_handler::clear_pending_nas_info()
+{
+  for (uint32_t erab_id : erab_ids_with_pending_nas_pdus) {
+    auto info_it = erab_info_list.find(erab_id);
+    if (info_it == erab_info_list.end()) {
+      logger->warning("NAS PDU with ERAB id={} went missing", erab_id);
+      continue;
+    }
+    erab_info_list.erase(info_it);
+  }
+
+  erab_ids_with_pending_nas_pdus.clear();
+}
+
 } // namespace srsenb
diff --git a/srsenb/src/stack/rrc/rrc_ue.cc b/srsenb/src/stack/rrc/rrc_ue.cc
index 922b5e5a2..a0073c3f9 100644
--- a/srsenb/src/stack/rrc/rrc_ue.cc
+++ b/srsenb/src/stack/rrc/rrc_ue.cc
@@ -961,6 +961,9 @@ void rrc::ue::handle_rrc_reconf_complete(rrc_conn_recfg_complete_s* msg, srsran:
   // If performing handover, signal its completion
   mobility_handler->trigger(*msg);
 
+  // Clear pending NAS PDUs
+  bearer_list.clear_pending_nas_info();
+
   // 2> if the UE has radio link failure or handover failure information available
   const auto& complete_r8 = msg->crit_exts.rrc_conn_recfg_complete_r8();
   if (complete_r8.non_crit_ext.non_crit_ext.rlf_info_available_r10_present or rlf_info_pending) {