Process Create SM Context Request colliding with an existing SM Context

src/smf_app/smf_app.cpp

@@ -770,23 +770,7 @@ void smf_app::handle_pdu_session_create_sm_context_request(
     return;
   }
 
-  //Step 4. Verify the session is already existed
-  if (is_scid_2_smf_context(supi64, dnn, snssai, pdu_session_id)) {
-    //TODO: should delete the local context (including and any associated resources in the UPF and PCF) and create a new one
-    Logger::smf_app().warn(
-        "PDU Session already existed (SUPI " SUPI_64_FMT ", DNN %s, NSSAI (sst %d, sd %s), PDU Session ID %d)",
-        supi64, dnn.c_str(), snssai.sST, snssai.sD.c_str(), pdu_session_id);
-    //TODO: temporary disable this action to test with AMF
-    /*
-    //trigger to send reply to AMF
-   trigger_http_response(
-        http_status_code_e::HTTP_STATUS_CODE_406_NOT_ACCEPTABLE, smreq->pid,
-        N11_SESSION_CREATE_SM_CONTEXT_RESPONSE);
-    return;
-    */
-  }
-
-  //Step 5. create a context for this supi if not existed, otherwise update
+  //Step 4. create a context for this supi if not existed, otherwise update
   std::shared_ptr<smf_context> sc = { };
   if (is_supi_2_smf_context(supi64)) {
     Logger::smf_app().debug("Update SMF context with SUPI " SUPI_64_FMT "",
@@ -802,7 +786,7 @@ void smf_app::handle_pdu_session_create_sm_context_request(
     set_supi_2_smf_context(supi64, sc);
   }
 
-  //Step 6. Create/update context with dnn information
+  //Step 5. Create/update context with dnn information
   std::shared_ptr<dnn_context> sd = { };
 
   if (!sc.get()->find_dnn_context(snssai, dnn, sd)) {
@@ -818,6 +802,16 @@ void smf_app::handle_pdu_session_create_sm_context_request(
     }
   }
 
+  //Step 6. if colliding with an existing SM context (session is already existed and request type is INITIAL_REQUEST)
+  //Delete the local context (including and any associated resources in the UPF and PCF) and create a new one
+  if (is_scid_2_smf_context(supi64, dnn, snssai, pdu_session_id) && (request_type.compare("INITIAL_REQUEST") == 0)) {
+    //remove smf_pdu_session (including all flows associated to this session)
+    sd.get()->remove_pdu_session(pdu_session_id);
+    Logger::smf_app().warn(
+        "PDU Session already existed (SUPI " SUPI_64_FMT ", DNN %s, NSSAI (sst %d, sd %s), PDU Session ID %d)",
+        supi64, dnn.c_str(), snssai.sST, snssai.sD.c_str(), pdu_session_id);
+  }
+
   //Step 7. retrieve Session Management Subscription data from UDM if not available (step 4, section 4.3.2 3GPP TS 23.502)
   std::string dnn_selection_mode = smreq->req.get_dnn_selection_mode();
   //if the Session Management Subscription data is not available, get from configuration file or UDM

src/smf_app/smf_context.hpp

@@ -233,6 +233,12 @@ class smf_pdu_session : public std::enable_shared_from_this<smf_pdu_session> {
    */
   void remove_qos_flow(smf_qos_flow &flow);
 
+  /*
+   * Remove all QoS flow associated with this PDU Session
+   * @return void
+   */
+  void remove_qos_flows();
+
   /*
    * Set current status of PDU Session
    * @param [const pdu_session_status_e &] status: status to be set
@@ -428,8 +434,7 @@ class smf_pdu_session : public std::enable_shared_from_this<smf_pdu_session> {
   uint8_t number_of_supported_packet_filters;  //number_of_supported_packet_filters
   util::uint_generator<uint32_t> qos_rule_id_generator;
 
-  // Recursive lock
-  mutable std::recursive_mutex m_pdu_session_mutex;
+   mutable std::shared_mutex m_pdu_session_mutex;
 
 };
 
@@ -438,7 +443,8 @@ class session_management_subscription {
   session_management_subscription(snssai_t snssai)
       :
       single_nssai(snssai),
-      dnn_configurations() {
+      dnn_configurations(),
+      m_mutex() {
   }
 
   /*
@@ -471,6 +477,7 @@ class session_management_subscription {
  private:
   snssai_t single_nssai;
   std::map<std::string, std::shared_ptr<dnn_configuration_t>> dnn_configurations;  //dnn <->dnn_configuration
+  mutable std::shared_mutex m_mutex;
 };
 
 /*
@@ -513,6 +520,14 @@ class dnn_context {
    */
   void insert_pdu_session(std::shared_ptr<smf_pdu_session> &sp);
 
+  /*
+   * Delete a PDU Session identified by its ID
+   * @param [const uint32_t] pdu_session_id
+   * @return bool: return true if the pdu session is deleted, otherwise, return false
+   */
+  bool remove_pdu_session(const uint32_t pdu_session_id);
+
+
   /*
    * Get number of pdu sessions associated with this context (dnn and Nssai)
    * @param void
@@ -531,7 +546,7 @@ class dnn_context {
   std::string dnn_in_use;   // The DNN currently used, as received from the AMF
   snssai_t nssai;
   std::vector<std::shared_ptr<smf_pdu_session>> pdu_sessions;  //Store all PDU Sessions associated with this DNN context
-  mutable std::recursive_mutex m_context;
+  mutable std::shared_mutex m_context;
 };
 
 class smf_context;