src/mme-app/utils/mmeCommonUtils.cpp

/*
 * Copyright (c) 2019, Infosys Ltd.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <utils/mmeCommonUtils.h>
#include <controlBlock.h>
#include <contextManager/dataBlocks.h>
#include <contextManager/subsDataGroupManager.h>
#include <log.h>
#include <mme_app.h>
#include <msgBuffer.h>
#include <s1ap_structs.h>
#include <utils/defaultMmeProcedureCtxt.h>

using namespace mme;

extern mme_config g_mme_cfg;

bool MmeCommonUtils::isLocalGuti(const guti &guti_r)
{
	bool rc = false;

	if (guti_r.mme_grp_id == g_mme_cfg.mme_group_id &&
			guti_r.mme_code == g_mme_cfg.mme_code)
	{
		rc = true;
	}

	return rc;
}

uint32_t MmeCommonUtils::allocateMtmsi()
{
	uint32_t tmsi = 0;

	while(1)
	{
		tmsi = rand() % 10000;

		if (SubsDataGroupManager::Instance()->findCBWithmTmsi(tmsi) == -1)
			break;
	}

	log_msg(LOG_INFO, "MTMSI allocated is %u\n", tmsi);

	return tmsi;
}

AttachType MmeCommonUtils::getAttachType(UEContext* ueContext_p,
		const struct ue_attach_info& ue_info)
{
	log_msg(LOG_INFO, "deriveAttachType\n");

	AttachType attachType = maxAttachType_c;

	if(UE_ID_IMSI(ue_info.flags))
	{
		log_msg(LOG_INFO, "IMSI attach received.\n");

		attachType = imsiAttach_c;
	}
	else if (UE_ID_GUTI(ue_info.flags))
	{
		log_msg(LOG_INFO, "GUTI attach received. mTMSI is %u \n",
				ue_info.mi_guti.m_TMSI);

		attachType = unknownGutiAttach_c;

		if (isLocalGuti(ue_info.mi_guti))
		{
			// The guti is allocated by this MME, check if a context exists.
			// If the context does not exist, treat as unknown GUTI attach?
			log_msg(LOG_INFO, "GUTI is local..");

			if (ueContext_p != NULL)
			{
				if (ueContext_p->getMtmsi() == ue_info.mi_guti.m_TMSI)
				{
					log_msg(LOG_INFO, "and known\n");

					attachType = knownGutiAttach_c;
				}
				else
				{
					log_msg(LOG_INFO, "mTMSI mismatches with UE context. "
							"Treat as unknown GUTI attach\n");
				}
			}
			else
			{
				log_msg(LOG_INFO, "UE context is null. Unknown GUTI attach triggered\n");
			}

		}
		else
		{
			log_msg(LOG_INFO, "GUTI is not local..");
		}
	}
	return attachType;
}

SM::ControlBlock* MmeCommonUtils::findControlBlock(cmn::utils::MsgBuffer* buf)
{
	SM::ControlBlock *cb = NULL;

	const s1_incoming_msg_data_t* msgData_p = (s1_incoming_msg_data_t*)(buf->getDataPointer());
	if(msgData_p == NULL)
	{
		log_msg(LOG_INFO, "MsgData is NULL .\n");
		return cb;
	}

	switch (msgData_p->msg_type)
	{
		case attach_request:
		{
			const struct ue_attach_info &ue_info = (msgData_p->msg_data.ue_attach_info_m);
			if(UE_ID_IMSI(ue_info.flags))
			{
				log_msg(LOG_INFO, "IMSI attach received.\n");

				cb = SubsDataGroupManager::Instance()->allocateCB();
				cb->setTempDataBlock(DefaultMmeProcedureCtxt::Instance());
			}
			else if (UE_ID_GUTI(ue_info.flags))
			{
                		log_msg(LOG_INFO, "GUTI attach received.\n");

				if (isLocalGuti(ue_info.mi_guti))
				{
					log_msg(LOG_INFO, "GUTI is local.\n");

					int cbIndex = SubsDataGroupManager::Instance()->findCBWithmTmsi(ue_info.mi_guti.m_TMSI);
					if (cbIndex > 0)
					{
						cb = SubsDataGroupManager::Instance()->findControlBlock(cbIndex);
					}
					else
					{
						log_msg(LOG_ERROR, "Failed to find control block with mTmsi.\n");

                        // allocate new cb and proceed?
                        cb = SubsDataGroupManager::Instance()->allocateCB();
                        cb->setTempDataBlock(DefaultMmeProcedureCtxt::Instance());
					}
				}
                else
                {
                    cb = SubsDataGroupManager::Instance()->allocateCB();
                    cb->setTempDataBlock(DefaultMmeProcedureCtxt::Instance());
                }
			}
			break;
		}
		case service_request:
		{
			const struct service_req_Q_msg &service_req = (msgData_p->msg_data.service_req_Q_msg_m);
			int cbIndex = SubsDataGroupManager::Instance()->findCBWithmTmsi(service_req.s_tmsi.m_TMSI);
			if (cbIndex > 0)
			{
				cb = SubsDataGroupManager::Instance()->findControlBlock(cbIndex);
			}
			else
			{
				log_msg(LOG_INFO, "Failed to find control block with mTmsi.\n");
			}

			break;
		}
		case detach_request:
		{
			const struct detach_req_Q_msg &detach_Req = (msgData_p->msg_data.detachReq_Q_msg_m);
			int cbIndex = SubsDataGroupManager::Instance()->findCBWithmTmsi(detach_Req.ue_m_tmsi);
			if (cbIndex > 0)
			{
				cb = SubsDataGroupManager::Instance()->findControlBlock(cbIndex);
			}
			else
			{
				log_msg(LOG_INFO, "Failed to find control block with mTmsi. %d\n", detach_Req.ue_m_tmsi);
			}
			break;
		}
		case tau_request:
		{
			cb = SubsDataGroupManager::Instance()->findControlBlock(msgData_p->ue_idx);

			if (cb == NULL)
				log_msg(LOG_INFO, "Failed to retrieve CB using idx %d.\n", msgData_p->ue_idx);

			break;
		}
		default:
		{
			log_msg(LOG_INFO, "Unhandled message is NULL .\n");
		}
	}

	return cb;
}