Adding UE context release command. Fixing issue when identity response is integrity protected.

srsepc/hdr/mme/s1ap_ctx_mngmt_proc.h

@@ -50,7 +50,7 @@ public:
   bool send_initial_context_setup_request(uint32_t mme_ue_s1ap_id, struct srslte::gtpc_create_session_response *cs_resp, struct srslte::gtpc_f_teid_ie sgw_ctrl_fteid);
   bool handle_initial_context_setup_response(LIBLTE_S1AP_MESSAGE_INITIALCONTEXTSETUPRESPONSE_STRUCT *in_ctxt_resp);
   bool handle_ue_context_release_request(LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASEREQUEST_STRUCT *ue_rel, struct sctp_sndrcvinfo *enb_sri, srslte::byte_buffer_t *reply_buffer, bool *reply_flag);
-  bool pack_ue_context_release_request(uint32_t mme_ue_s1ap_id, srslte::byte_buffer_t *reply_buffer);
+  bool send_ue_context_release_command(ue_ecm_ctx_t *ecm_ctx, srslte::byte_buffer_t *reply_buffer);
 
 private:
   s1ap_ctx_mngmt_proc();

srsepc/src/mme/s1ap_ctx_mngmt_proc.cc

@@ -309,36 +309,44 @@ s1ap_ctx_mngmt_proc::handle_ue_context_release_request(LIBLTE_S1AP_MESSAGE_UECON
 }
 
 bool
-s1ap_ctx_mngmt_proc::pack_ue_context_release_request(uint32_t mme_ue_s1ap_id, srslte::byte_buffer_t *reply_buffer)
+s1ap_ctx_mngmt_proc::send_ue_context_release_command(ue_ecm_ctx_t *ecm_ctx, srslte::byte_buffer_t *reply_buffer)
 {
 
+  int s1mme = m_s1ap->get_s1_mme();
+
   //Prepare reply PDU
   LIBLTE_S1AP_S1AP_PDU_STRUCT pdu;
   bzero(&pdu, sizeof(LIBLTE_S1AP_S1AP_PDU_STRUCT));
   pdu.choice_type = LIBLTE_S1AP_S1AP_PDU_CHOICE_INITIATINGMESSAGE;
 
   LIBLTE_S1AP_INITIATINGMESSAGE_STRUCT *init = &pdu.choice.initiatingMessage;
-  init->procedureCode = LIBLTE_S1AP_PROC_ID_UECONTEXTRELEASEREQUEST;
+  init->procedureCode = LIBLTE_S1AP_PROC_ID_UECONTEXTRELEASE;
-  init->choice_type   = LIBLTE_S1AP_INITIATINGMESSAGE_CHOICE_UECONTEXTRELEASEREQUEST;
+  init->choice_type   = LIBLTE_S1AP_INITIATINGMESSAGE_CHOICE_UECONTEXTRELEASECOMMAND;
+
+  LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASECOMMAND_STRUCT *ctx_rel_cmd = &init->choice.UEContextReleaseCommand;
+
+  ctx_rel_cmd->UE_S1AP_IDs.choice_type = LIBLTE_S1AP_UE_S1AP_IDS_CHOICE_UE_S1AP_ID_PAIR;
+  ctx_rel_cmd->UE_S1AP_IDs.choice.uE_S1AP_ID_pair.mME_UE_S1AP_ID.MME_UE_S1AP_ID = ecm_ctx->mme_ue_s1ap_id;
+  ctx_rel_cmd->UE_S1AP_IDs.choice.uE_S1AP_ID_pair.eNB_UE_S1AP_ID.ENB_UE_S1AP_ID = ecm_ctx->enb_ue_s1ap_id;
+
+  ctx_rel_cmd->Cause.choice_type = LIBLTE_S1AP_CAUSE_CHOICE_NAS;
+  ctx_rel_cmd->Cause.choice.nas.ext = false;
+  ctx_rel_cmd->Cause.choice.nas.e =  LIBLTE_S1AP_CAUSENAS_NORMAL_RELEASE;
 
-  LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASEREQUEST_STRUCT *ctx_rel_req = &init->choice.UEContextReleaseRequest;
-  
-  /*
-    typedef struct{
-    bool                                                         ext;
-    LIBLTE_S1AP_MME_UE_S1AP_ID_STRUCT                            MME_UE_S1AP_ID;
-    LIBLTE_S1AP_ENB_UE_S1AP_ID_STRUCT                            eNB_UE_S1AP_ID;
-    LIBLTE_S1AP_CAUSE_STRUCT                                     Cause;
-    LIBLTE_S1AP_GWCONTEXTRELEASEINDICATION_ENUM_EXT              GWContextReleaseIndication;
-    bool                                                         GWContextReleaseIndication_present;
-    }LIBLTE_S1AP_MESSAGE_UECONTEXTRELEASEREQUEST_STRUCT;
-   */
   LIBLTE_ERROR_ENUM err = liblte_s1ap_pack_s1ap_pdu(&pdu, (LIBLTE_BYTE_MSG_STRUCT*)reply_buffer);
   if(err != LIBLTE_SUCCESS)
   {
     m_s1ap_log->error("Could not pack Initial Context Setup Request Message\n");
     return false;
   }
+  //Send Reply to eNB 
+  int n_sent = sctp_send(s1mme,reply_buffer->msg, reply_buffer->N_bytes, &ecm_ctx->enb_sri, 0);
+  if(n_sent == -1)
+  {
+    m_s1ap_log->error("Failed to send Initial Context Setup Request\n");
+    return false;
+  }
+
 
   return true;
 }

srsepc/src/mme/s1ap_mngmt_proc.cc

@@ -234,7 +234,7 @@ s1ap_mngmt_proc::pack_s1_setup_response(s1ap_args_t s1ap_args, srslte::byte_buff
   LIBLTE_S1AP_SERVEDGUMMEISITEM_STRUCT *serv_gummei = &s1_resp->ServedGUMMEIs.buffer[0];
 
   serv_gummei->ext=false;
-  //serv_gummei->iE_Extensions=false;
+  serv_gummei->iE_Extensions_present = false;
 
   uint32_t plmn=0;
   srslte::s1ap_mccmnc_to_plmn(s1ap_args.mcc, s1ap_args.mnc, &plmn);
@@ -257,7 +257,9 @@ s1ap_mngmt_proc::pack_s1_setup_response(s1ap_args_t s1ap_args, srslte::byte_buff
 
   //Relay Unsupported
   s1_resp->MMERelaySupportIndicator_present=false;
-    
+
+  s1_resp->CriticalityDiagnostics_present = false;
+
   liblte_s1ap_pack_s1ap_pdu(&pdu, (LIBLTE_BYTE_MSG_STRUCT*)msg);
   
  return true;

srsepc/src/mme/s1ap_nas_transport.cc

@@ -158,15 +158,27 @@ s1ap_nas_transport::handle_uplink_nas_transport(LIBLTE_S1AP_MESSAGE_UPLINKNASTRA
     ue_emm_ctx = m_s1ap->find_ue_emm_ctx_from_imsi(ue_ecm_ctx->imsi);
     if(ue_emm_ctx == NULL)
     {
-      m_s1ap_log->warning("Uplink NAS: could not find security context for integrity protected message. MME-UE S1AP id: %lu\n",mme_ue_s1ap_id);
+      //No EMM context found.
-      m_pool->deallocate(nas_msg);
+      //Perhaps a temporary context is being created?
-      return false;
+      //This can happen with integrity protected identity reponse and authentication response messages
+      if( !(msg_type == LIBLTE_MME_MSG_TYPE_IDENTITY_RESPONSE && sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_INTEGRITY) &&
+          !(msg_type == LIBLTE_MME_MSG_TYPE_AUTHENTICATION_RESPONSE && sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_INTEGRITY))
+      {
+        m_s1ap_log->warning("Uplink NAS: could not find security context for integrity protected message. MME-UE S1AP id: %lu\n",mme_ue_s1ap_id);
+        m_pool->deallocate(nas_msg);
+        return false;
+      }
     }
   }
 
-  if(sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_PLAIN_NAS)
+  if( sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_PLAIN_NAS ||
+      (msg_type == LIBLTE_MME_MSG_TYPE_IDENTITY_RESPONSE && sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_INTEGRITY) ||
+      (msg_type == LIBLTE_MME_MSG_TYPE_AUTHENTICATION_RESPONSE && sec_hdr_type == LIBLTE_MME_SECURITY_HDR_TYPE_INTEGRITY))
   {
-    //Plain NAS, only identity response is valid.
+    //Only identity response and authentication response are valid as plain NAS.
+    //Sometimes authentication response and identity are sent as integrity protected,
+    //but these messages are sent when the securty context is not setup yet, so we cannot integrity check it.
+    //FIXME Double-check
     switch(msg_type)
     {
     case LIBLTE_MME_MSG_TYPE_IDENTITY_RESPONSE:
@@ -220,17 +232,17 @@ s1ap_nas_transport::handle_uplink_nas_transport(LIBLTE_S1AP_MESSAGE_UPLINKNASTRA
     //Integrity protected NAS message, possibly chiphered.
     ue_emm_ctx->security_ctxt.ul_nas_count++;
     mac_valid = integrity_check(ue_emm_ctx,nas_msg);
-    if(!mac_valid && msg_type != LIBLTE_MME_MSG_TYPE_AUTHENTICATION_RESPONSE){
+    if(!mac_valid){
       m_s1ap_log->warning("Invalid MAC in NAS message type 0x%x.\n", msg_type);
       m_pool->deallocate(nas_msg);
       return false;
     }
     switch (msg_type) {
-    case LIBLTE_MME_MSG_TYPE_AUTHENTICATION_RESPONSE:
+  /*case LIBLTE_MME_MSG_TYPE_AUTHENTICATION_RESPONSE:
       m_s1ap_log->info("Uplink NAS: Received Authentication Response\n");
       m_s1ap_log->console("Uplink NAS: Received Authentication Response\n");
       handle_nas_authentication_response(nas_msg, ue_ecm_ctx, reply_buffer, reply_flag);
-      break;
+      break;*/
     case  LIBLTE_MME_MSG_TYPE_ATTACH_COMPLETE:
       m_s1ap_log->info("Uplink NAS: Received Attach Complete\n");
       m_s1ap_log->console("Uplink NAS: Received Attach Complete\n");
@@ -599,7 +611,7 @@ s1ap_nas_transport::handle_nas_service_request(uint32_t m_tmsi,
       //Service request to Connected UE.
       //Delete ECM context and connect.
       m_mme_gtpc->send_delete_session_request(ecm_ctx);
-      //pack_context_release_request();
+      //m_s1ap send_context_release_request(ecm_ctx, reply_buffer);
     }
     else
     {