[lte] Handling Implicit detach timer while mme restart

lte/gateway/c/oai/include/mme_app_ue_context.h

@@ -414,6 +414,7 @@ typedef struct ue_mm_context_s {
    * Stop when UE moves to connected state
    */
   struct mme_app_timer_t implicit_detach_timer;
+  time_t time_implicit_detach_timer_started;
   /* Initial Context Setup Procedure Guard timer */
   struct mme_app_timer_t initial_context_setup_rsp_timer;
   /* UE Context Modification Procedure Guard timer */

lte/gateway/c/oai/tasks/mme_app/mme_app_bearer.c

@@ -1590,6 +1590,7 @@ void mme_app_handle_mobile_reachability_timer_expiry(void* args) {
         ue_context_p->mme_ue_s1ap_id);
     ue_context_p->implicit_detach_timer.id = MME_APP_TIMER_INACTIVE_ID;
   } else {
+    ue_context_p->time_implicit_detach_timer_started = time(NULL);
     OAILOG_DEBUG_UE(
         LOG_MME_APP, ue_context_p->emm_context._imsi64,
         "Started Implicit Detach timer for UE id: " MME_UE_S1AP_ID_FMT "\n",
@@ -1616,6 +1617,7 @@ void mme_app_handle_implicit_detach_timer_expiry(void* args) {
     OAILOG_FUNC_OUT(LOG_MME_APP);
   }
   ue_context_p->implicit_detach_timer.id = MME_APP_TIMER_INACTIVE_ID;
+  ue_context_p->time_implicit_detach_timer_started = 0;
   // Initiate Implicit Detach for the UE
   nas_proc_implicit_detach_ue_ind(mme_ue_s1ap_id);
   OAILOG_FUNC_OUT(LOG_MME_APP);

lte/gateway/c/oai/tasks/mme_app/mme_app_context.c

@@ -102,6 +102,9 @@ static bool mme_app_recover_timers_for_ue(
 static void mme_app_resume_mobile_reachability_timer(
     struct ue_mm_context_s* const ue_mm_context_pP);
 
+static void mme_app_resume_implicit_detach_timer(
+    struct ue_mm_context_s* const ue_mm_context_pP);
+
 static void _directoryd_report_location(uint64_t imsi, uint8_t imsi_len) {
   char imsi_str[IMSI_BCD_DIGITS_MAX + 1];
   IMSI64_TO_STRING(imsi, imsi_str, imsi_len);
@@ -1529,6 +1532,7 @@ void mme_ue_context_update_ue_sig_connection_state(
         free_wrapper((void**) &timer_argP);
       }
       ue_context_p->implicit_detach_timer.id = MME_APP_TIMER_INACTIVE_ID;
+      ue_context_p->time_implicit_detach_timer_started = 0;
     }
     // Update Stats
     update_mme_app_stats_connected_ue_add();
@@ -2289,27 +2293,37 @@ static bool mme_app_recover_timers_for_ue(
       ue_mm_context_pP->time_mobile_reachability_timer_started) {
     mme_app_resume_mobile_reachability_timer(ue_mm_context_pP);
   }
+  if (ue_mm_context_pP &&
+      ue_mm_context_pP->time_implicit_detach_timer_started) {
+    mme_app_resume_implicit_detach_timer(ue_mm_context_pP);
+  }
   OAILOG_FUNC_RETURN(LOG_MME_APP, false);
 }
 
+// Resumes mobile reachability timer on MME restart
 static void mme_app_resume_mobile_reachability_timer(
     struct ue_mm_context_s* const ue_mm_context_pP) {
   OAILOG_FUNC_IN(LOG_MME_APP);
   time_t current_time = time(NULL);
   time_t lapsed_time =
       current_time - ue_mm_context_pP->time_mobile_reachability_timer_started;
-  ue_mm_context_pP->mobile_reachability_timer.sec =
-      (((mme_config.nas_config.t3412_min) +
-        MME_APP_DELTA_T3412_REACHABILITY_TIMER) *
-       60) -
-      lapsed_time;
 
+  /* Below condition validates whether timer has expired before MME recovers
+   * from restart, so MME shall handle as timer expiry
+   */
+  if (ue_mm_context_pP->mobile_reachability_timer.sec <= lapsed_time) {
+    mme_app_handle_mobile_reachability_timer_expiry(
+        (void*) &(ue_mm_context_pP->mme_ue_s1ap_id));
+    OAILOG_FUNC_OUT(LOG_MME_APP);
+  }
+  uint32_t remaining_time_in_seconds =
+      ue_mm_context_pP->mobile_reachability_timer.sec - lapsed_time;
   OAILOG_DEBUG(
       LOG_MME_APP,
-      "Current_time :%ld time mobile reachability timer "
-      "started:%ld lapsed time:%ld remaining time:%ld\n",
+      "Current_time :%ld mobile reachability timer start time :%ld "
+      "lapsed time:%ld remaining time:%d \n",
       current_time, ue_mm_context_pP->time_mobile_reachability_timer_started,
-      lapsed_time, ue_mm_context_pP->mobile_reachability_timer.sec);
+      lapsed_time, remaining_time_in_seconds);
 
   // Start Mobile reachability timer only for remaining duration
   nas_itti_timer_arg_t timer_callback_arg = {0};
@@ -2318,9 +2332,8 @@ static void mme_app_resume_mobile_reachability_timer(
   timer_callback_arg.nas_timer_callback_arg =
       (void*) &(ue_mm_context_pP->mme_ue_s1ap_id);
   if (timer_setup(
-          ue_mm_context_pP->mobile_reachability_timer.sec, 0, TASK_MME_APP,
-          INSTANCE_DEFAULT, TIMER_ONE_SHOT, &timer_callback_arg,
-          sizeof(timer_callback_arg),
+          remaining_time_in_seconds, 0, TASK_MME_APP, INSTANCE_DEFAULT,
+          TIMER_ONE_SHOT, &timer_callback_arg, sizeof(timer_callback_arg),
           &(ue_mm_context_pP->mobile_reachability_timer.id)) < 0) {
     OAILOG_ERROR_UE(
         LOG_MME_APP, ue_mm_context_pP->emm_context._imsi64,
@@ -2336,3 +2349,53 @@ static void mme_app_resume_mobile_reachability_timer(
   }
   OAILOG_FUNC_OUT(LOG_MME_APP);
 }
+
+// Resumes implicit detach timer on MME restart
+static void mme_app_resume_implicit_detach_timer(
+    struct ue_mm_context_s* const ue_mm_context_pP) {
+  OAILOG_FUNC_IN(LOG_MME_APP);
+  time_t current_time = time(NULL);
+  time_t lapsed_time =
+      current_time - ue_mm_context_pP->time_implicit_detach_timer_started;
+
+  /* Below condition validates whether timer has expired before MME recovers
+   * from restart, so MME shall handle as timer expiry
+   */
+  if (ue_mm_context_pP->implicit_detach_timer.sec <= lapsed_time) {
+    mme_app_handle_implicit_detach_timer_expiry(
+        (void*) &(ue_mm_context_pP->mme_ue_s1ap_id));
+    OAILOG_FUNC_OUT(LOG_MME_APP);
+  }
+  uint32_t remaining_time_in_seconds =
+      ue_mm_context_pP->implicit_detach_timer.sec - lapsed_time;
+  OAILOG_DEBUG(
+      LOG_MME_APP,
+      "Current_time :%ld imiplcit detach timer start time:%ld "
+      "lapsed time:%ld remaining time:%d \n",
+      current_time, ue_mm_context_pP->time_implicit_detach_timer_started,
+      lapsed_time, remaining_time_in_seconds);
+
+  // Start Implicit detach timer only for remaining duration
+  nas_itti_timer_arg_t timer_callback_arg = {0};
+  timer_callback_arg.nas_timer_callback =
+      mme_app_handle_implicit_detach_timer_expiry;
+  timer_callback_arg.nas_timer_callback_arg =
+      (void*) &(ue_mm_context_pP->mme_ue_s1ap_id);
+  if (timer_setup(
+          remaining_time_in_seconds, 0, TASK_MME_APP, INSTANCE_DEFAULT,
+          TIMER_ONE_SHOT, &timer_callback_arg, sizeof(timer_callback_arg),
+          &(ue_mm_context_pP->implicit_detach_timer.id)) < 0) {
+    OAILOG_ERROR_UE(
+        LOG_MME_APP, ue_mm_context_pP->emm_context._imsi64,
+        "Failed to start Implicit Detach timer for UE id "
+        " " MME_UE_S1AP_ID_FMT "\n",
+        ue_mm_context_pP->mme_ue_s1ap_id);
+    ue_mm_context_pP->implicit_detach_timer.id = MME_APP_TIMER_INACTIVE_ID;
+  } else {
+    OAILOG_DEBUG_UE(
+        LOG_MME_APP, ue_mm_context_pP->emm_context._imsi64,
+        "Started Implicit Detach timer for UE id  " MME_UE_S1AP_ID_FMT "\n",
+        ue_mm_context_pP->mme_ue_s1ap_id);
+  }
+  OAILOG_FUNC_OUT(LOG_MME_APP);
+}

lte/gateway/c/oai/tasks/mme_app/mme_app_state_converter.cpp

@@ -504,6 +504,7 @@ void MmeNasStateConverter::proto_to_pdn_context_list(
 
 void MmeNasStateConverter::ue_context_to_proto(
     const ue_mm_context_t* state_ue_context, oai::UeContext* ue_context_proto) {
+  OAILOG_FUNC_IN(LOG_MME_APP);
   ue_context_proto->Clear();
 
   char* msisdn_buffer = bstr2cstr(state_ue_context->msisdn, (char) '?');
@@ -602,11 +603,15 @@ void MmeNasStateConverter::ue_context_to_proto(
       ue_context_proto->mutable_ulr_response_timer());
   ue_context_proto->mutable_time_mobile_reachability_timer_started()
       ->set_seconds(state_ue_context->time_mobile_reachability_timer_started);
+  ue_context_proto->mutable_time_implicit_detach_timer_started()->set_seconds(
+      state_ue_context->time_implicit_detach_timer_started);
+  OAILOG_FUNC_OUT(LOG_MME_APP);
 }
 
 void MmeNasStateConverter::proto_to_ue_mm_context(
     const oai::UeContext& ue_context_proto,
     ue_mm_context_t* state_ue_mm_context) {
+  OAILOG_FUNC_IN(LOG_MME_APP);
   state_ue_mm_context->msisdn = bfromcstr(ue_context_proto.msisdn().c_str());
   state_ue_mm_context->ue_context_rel_cause =
       static_cast<enum s1cause>(ue_context_proto.rel_cause());
@@ -690,6 +695,9 @@ void MmeNasStateConverter::proto_to_ue_mm_context(
       &state_ue_mm_context->paging_response_timer);
   state_ue_mm_context->time_mobile_reachability_timer_started =
       ue_context_proto.time_mobile_reachability_timer_started().seconds();
+  state_ue_mm_context->time_implicit_detach_timer_started =
+      ue_context_proto.time_implicit_detach_timer_started().seconds();
+  OAILOG_FUNC_OUT(LOG_MME_APP);
 }
 
 /*********************************************************

lte/gateway/c/oai/tasks/mme_app/mme_app_state_manager.cpp

@@ -136,6 +136,9 @@ void MmeNasStateManager::mme_nas_state_init_local_state() {
         mme_statistic_timer_);
     state_cache_p->statistic_timer_id = 0;
   }
+  if (is_initialized) {
+    mme_app_recover_timers_for_all_ues();
+  }
 }
 
 // Create the hashtables for MME NAS state

lte/protos/oai/mme_nas_state.proto

@@ -133,6 +133,7 @@ message UeContext {
   uint32 rau_tau_timer = 205;
   Timer ulr_response_timer = 206;
   google.protobuf.Timestamp time_mobile_reachability_timer_started = 207;
+  google.protobuf.Timestamp time_implicit_detach_timer_started = 208;
 }
 
 // mme_ue_context_t