Update S1AP RNTI context when doing Reestablishment (#1582)

lib/include/srslte/interfaces/enb_interfaces.h

@@ -474,6 +474,7 @@ public:
 
   virtual void write_pdu(uint16_t rnti, srslte::unique_byte_buffer_t pdu)                              = 0;
   virtual bool user_exists(uint16_t rnti)                                                              = 0;
+  virtual void user_mod(uint16_t old_rnti, uint16_t new_rnti)                                          = 0;
   virtual bool user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_radio)              = 0;
   virtual void ue_ctxt_setup_complete(uint16_t rnti, const asn1::s1ap::init_context_setup_resp_s& res) = 0;
   virtual void ue_erab_setup_complete(uint16_t rnti, const asn1::s1ap::erab_setup_resp_s& res)         = 0;

srsenb/hdr/stack/upper/s1ap.h

@@ -71,6 +71,7 @@ public:
                   uint8_t                               mmec) override;
   void write_pdu(uint16_t rnti, srslte::unique_byte_buffer_t pdu) override;
   bool user_exists(uint16_t rnti) override;
+  void user_mod(uint16_t old_rnti, uint16_t new_rnti) override;
   bool user_release(uint16_t rnti, asn1::s1ap::cause_radio_network_e cause_radio) override;
   void ue_ctxt_setup_complete(uint16_t rnti, const asn1::s1ap::init_context_setup_resp_s& res) override;
   void ue_erab_setup_complete(uint16_t rnti, const asn1::s1ap::erab_setup_resp_s& res) override;

srsenb/src/stack/rrc/rrc_ue.cc

@@ -346,8 +346,9 @@ void rrc::ue::handle_rrc_con_reest_req(rrc_conn_reest_request_s* msg)
       ue_security_cfg                   = parent->users[old_rnti]->ue_security_cfg;
       ue_security_cfg.regenerate_keys_handover(pcell_cfg->cell_cfg.pci, pcell_cfg->cell_cfg.dl_earfcn);
 
-      // Modify GTP-U tunnel
+      // Modify GTP-U tunnel and S1AP context
       parent->gtpu->mod_bearer_rnti(old_rnti, rnti);
+      parent->s1ap->user_mod(old_rnti, rnti);
 
       // Get PDCP entity state (required when using RLC AM)
       for (const auto& erab_pair : parent->users[old_rnti]->bearer_list.get_erabs()) {

srsenb/src/stack/upper/s1ap.cc

@@ -367,6 +367,20 @@ bool s1ap::user_exists(uint16_t rnti)
   return users.find_ue_rnti(rnti) != nullptr;
 }
 
+void s1ap::user_mod(uint16_t old_rnti, uint16_t new_rnti)
+{
+  s1ap_log->info("Modifying user context. Old rnti: 0x%x, new rnti: 0x%x\n", old_rnti, new_rnti);
+  if (not user_exists(old_rnti)) {
+    s1ap_log->error("Old rnti does not exist, aborting.\n");
+    return;
+  }
+  if (user_exists(new_rnti)) {
+    s1ap_log->error("New rnti already exists, aborting.\n");
+    return;
+  }
+  users.find_ue_rnti(old_rnti)->ctxt.rnti = new_rnti;
+}
+
 void s1ap::ue_ctxt_setup_complete(uint16_t rnti, const asn1::s1ap::init_context_setup_resp_s& res)
 {
   ue* u = users.find_ue_rnti(rnti);

srsenb/test/upper/test_helpers.h

@@ -104,6 +104,7 @@ public:
       }
     }
   }
+  void user_mod(uint16_t old_rnti, uint16_t new_rnti) override {}
 };
 
 class pdcp_mobility_dummy : public pdcp_dummy