src/s1ap/handlers/detach_accept.c - MME2 - Gitiles

 /*
  * Copyright (c) 2003-2018, Great Software Laboratory Pvt. Ltd.
  * Copyright (c) 2017 Intel Corporation
  *
  * 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 <stdio.h>
 #include <stdlib.h>
 #include <pthread.h>
 #include <string.h>
 #include <unistd.h>
 #include <stdint.h>

 #include "log.h"
 #include "err_codes.h"
 #include "message_queues.h"
 #include "ipc_api.h"
 #include "s1ap.h"
 #include "s1ap_config.h"
 #include "main.h"
 #include "msgType.h"

 static int
 get_detach_accept_protoie_value(struct proto_IE *value, struct detach_accept_Q_msg *g_acptReqInfo)
 {
 	uint8_t ieCnt = 0;

 	value->no_of_IEs = DTCH_ACCEPT_NO_OF_IES;

 	value->data = (proto_IEs *) malloc(DTCH_ACCEPT_NO_OF_IES *
 			sizeof(proto_IEs));

 	value->data[ieCnt].val.mme_ue_s1ap_id = g_acptReqInfo->ue_idx;
 	ieCnt++;

 	value->data[ieCnt].val.enb_ue_s1ap_id = g_acptReqInfo->enb_s1ap_ue_id;
 	ieCnt++;

 	struct nasPDU *nas = &(value->data[ieCnt].val.nas);
 	nas->header.security_header_type = IntegrityProtectedCiphered;
 	nas->header.proto_discriminator = EPSMobilityManagementMessages;

 	/* placeholder for mac. mac value will be calculated later */
 	uint8_t mac[MAC_SIZE] = {0};
 	memcpy(nas->header.mac, mac, MAC_SIZE);

 	nas->header.seq_no = g_acptReqInfo->dl_seq_no;
 	nas->header.message_type = DetachAccept;

 	ieCnt++;

 	return SUCCESS;
 }

 /**
 * Stage specific message processing.
 */
 static int
 detach_accept_processing(struct detach_accept_Q_msg *g_acptReqInfo)
 {
 	unsigned char tmpStr[4];
 	struct s1ap_PDU s1apPDU= {0};
 	uint16_t protocolIe_Id;
 	uint8_t protocolIe_criticality = CRITICALITY_REJECT;
 	uint8_t initiating_msg = 0;
 	uint8_t datalen = 0;
 	uint8_t s1ap_len_pos;
 	uint8_t nas_len_pos;
 	uint8_t u8value = 0;
 	uint8_t mac_data_pos;

 	Buffer g_acpt_buffer;

 	s1apPDU.procedurecode = id_downlinkNASTransport;
 	s1apPDU.criticality = CRITICALITY_IGNORE;

 	get_detach_accept_protoie_value(&s1apPDU.value, g_acptReqInfo);

 	g_acpt_buffer.pos = 0;

 	buffer_copy(&g_acpt_buffer, &initiating_msg,
 			sizeof(initiating_msg));

 	buffer_copy(&g_acpt_buffer, &s1apPDU.procedurecode,
 			sizeof(s1apPDU.procedurecode));

 	buffer_copy(&g_acpt_buffer, &s1apPDU.criticality,
 				sizeof(s1apPDU.criticality));

 	s1ap_len_pos = g_acpt_buffer.pos;

 	/* length of Detach Accept */
 	u8value = 0;
 	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

 	/* TODO remove hardcoded values */
 	uint8_t chProtoIENo[3] = {0,0,3};
 	buffer_copy(&g_acpt_buffer, chProtoIENo, 3);

 	/* id-MME-UE-S1AP-ID */
 	protocolIe_Id = id_MME_UE_S1AP_ID;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
 	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
 					sizeof(protocolIe_criticality));
 	datalen = 2;
 	/* TODO need to add proper handling*/
 	unsigned char mme_ue_id[3];
 	datalen = copyU16(mme_ue_id, s1apPDU.value.data[0].val.mme_ue_s1ap_id);
 	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));
 	buffer_copy(&g_acpt_buffer, mme_ue_id, datalen);

 	/* id-eNB-UE-S1AP-ID */
 	protocolIe_Id = id_eNB_UE_S1AP_ID;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
 	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
 					sizeof(protocolIe_criticality));
 	/* TODO needs proper handling*/
 	unsigned char enb_ue_id[3];
 	datalen = copyU16(enb_ue_id, s1apPDU.value.data[1].val.enb_ue_s1ap_id);
 	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));
 	buffer_copy(&g_acpt_buffer, enb_ue_id, datalen);

 	/* NAS PDU start */
 	protocolIe_Id = id_NAS_PDU;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
 	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
 					sizeof(protocolIe_criticality));

 	nas_len_pos = g_acpt_buffer.pos;

 	datalen = 0;
 	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));

 	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));

 	nas_pdu_header *nas_hdr = &(s1apPDU.value.data[2].val.nas.header);

 	/* security header and protocol discriminator */
 	u8value = (nas_hdr->security_header_type << 4 |
 			nas_hdr->proto_discriminator);
 	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

 	/* mac */
 	/* placeholder for mac. mac value will be calculated later */
 	buffer_copy(&g_acpt_buffer, nas_hdr->mac, MAC_SIZE);
 	mac_data_pos = g_acpt_buffer.pos;

 	/* sequence number */
 	buffer_copy(&g_acpt_buffer, &(nas_hdr->seq_no),
 			sizeof(nas_hdr->seq_no));

 	/* security header and protocol discriminator */
 	nas_hdr->security_header_type = Plain;
 	u8value = (nas_hdr->security_header_type << 4 |
 			nas_hdr->proto_discriminator);
 	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

 	/* message type */
 	buffer_copy(&g_acpt_buffer, &(nas_hdr->message_type),
 			sizeof(nas_hdr->message_type));

 	/* NAS PDU end */

 	/* Calculate mac */
 	uint8_t direction = 1;
 	uint8_t bearer = 0;

 	calculate_mac(g_acptReqInfo->int_key, nas_hdr->seq_no,
 			direction, bearer, &g_acpt_buffer.buf[mac_data_pos],
 			g_acpt_buffer.pos - mac_data_pos,
 			&g_acpt_buffer.buf[mac_data_pos - MAC_SIZE]);

 	/* Copy nas length to nas length field */
 	datalen = g_acpt_buffer.pos - nas_len_pos -1;
 	memcpy(&(g_acpt_buffer.buf[nas_len_pos]), &datalen, sizeof(datalen));

 	/* Copy nas length to nas length field */
 	datalen = g_acpt_buffer.pos - nas_len_pos - 2;
 	memcpy(&(g_acpt_buffer.buf[nas_len_pos + 1]), &datalen, sizeof(datalen));

 	/* Copy length to s1ap length field */
 	datalen = g_acpt_buffer.pos - s1ap_len_pos - 1;
 	memcpy(g_acpt_buffer.buf + s1ap_len_pos, &datalen, sizeof(datalen));

 	/* TODO: temp fix */
 	//g_ics_buffer.buf[1] = 0x09;
 	send_sctp_msg(g_acptReqInfo->enb_fd, g_acpt_buffer.buf, g_acpt_buffer.pos,1);

 	log_msg(LOG_INFO, "Detach Accept sent to UE.");

 	return SUCCESS;
 }

 /**
 * essage processing for ue context release
 */
 static int
 ue_ctx_release_processing(struct detach_accept_Q_msg *g_acptReqInfo)
 {
 	Buffer g_ctxrel_buffer;
 	unsigned char tmpStr[4];
 	struct s1ap_PDU s1apPDU;
 	uint16_t protocolIe_Id;
 	uint8_t protocolIe_criticality = CRITICALITY_REJECT;
 	uint8_t initiating_msg = 0;
 	uint8_t datalen = 0;
 	uint8_t s1ap_len_pos;
 	uint8_t u8value = 0;

 	s1apPDU.procedurecode = id_UEContexRelease;
 	s1apPDU.criticality = CRITICALITY_IGNORE;

 	g_ctxrel_buffer.pos = 0;

 	buffer_copy(&g_ctxrel_buffer, &initiating_msg,
 			sizeof(initiating_msg));

 	buffer_copy(&g_ctxrel_buffer, &s1apPDU.procedurecode,
 			sizeof(s1apPDU.procedurecode));

 	buffer_copy(&g_ctxrel_buffer, &s1apPDU.criticality,
 				sizeof(s1apPDU.criticality));

 	s1ap_len_pos = g_ctxrel_buffer.pos;

 	/* length of UE Context Release */
 	u8value = 0;
 	buffer_copy(&g_ctxrel_buffer, &u8value, sizeof(u8value));

 	/* TODO remove hardcoded values */
 	uint8_t chProtoIENo[3] = {0,0,2};
 	buffer_copy(&g_ctxrel_buffer, chProtoIENo, 3);

 	/* id-UE-S1AP-IDs */
 	protocolIe_Id = id_UE_S1AP_IDs;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_ctxrel_buffer, tmpStr, sizeof(protocolIe_Id));
 	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
 					sizeof(protocolIe_criticality));

 	uint8_t mme_ue_id[4];
 	uint8_t mme_ue_id_len = copyU16(mme_ue_id,
 				s1apPDU.value.data[0].val.mme_ue_s1ap_id);

 	if (mme_ue_id[0] == 0x40 || mme_ue_id[0] == 0x80)
 		mme_ue_id[0] = ((mme_ue_id[0] & 0x0F)<<4 |
 				(mme_ue_id[0] & 0xF0)>>4);

 	uint8_t enb_ue_id[4];
 	uint8_t enb_ue_id_len = copyU16(enb_ue_id,
 				s1apPDU.value.data[1].val.enb_ue_s1ap_id);

 	datalen = mme_ue_id_len + enb_ue_id_len;
 	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
 	buffer_copy(&g_ctxrel_buffer, mme_ue_id, mme_ue_id_len);
 	buffer_copy(&g_ctxrel_buffer, enb_ue_id, enb_ue_id_len);

 #if 0
 	/* id-MME-UE-S1AP-ID */
 	protocolIe_Id = id_MME_UE_S1AP_ID;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_ctxrel_buffer, tmpStr,
 	                                sizeof(protocolIe_Id));

 	protocolIe_criticality = CRITICALITY_REJECT;
 	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
 	                                sizeof(protocolIe_criticality));

 	datalen = 2;

 	/* TODO needs proper handling*/
 	unsigned char mme_ue_id[4];
 	datalen = copyU16(mme_ue_id, s1apPDU.value.data[0].val.mme_ue_s1ap_id);
 	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
 	buffer_copy(&g_ctxrel_buffer, mme_ue_id, datalen);
 #endif

 	/* id-Cause */
 	protocolIe_Id = id_Cause;
 	protocolIe_criticality = CRITICALITY_IGNORE;
 	copyU16(tmpStr, protocolIe_Id);
 	buffer_copy(&g_ctxrel_buffer, tmpStr, sizeof(protocolIe_Id));
 	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
 					sizeof(protocolIe_criticality));
 	datalen = 1;
 	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
 	/* TODO : Revisit. cause : nas(2) and value : detach (2), why 0x24 ? */
 	u8value = 0x24;
 	buffer_copy(&g_ctxrel_buffer, &u8value, sizeof(u8value));

 	/* Copy length to s1ap length field */
 	datalen = g_ctxrel_buffer.pos - s1ap_len_pos - 1;
 	memcpy(g_ctxrel_buffer.buf + s1ap_len_pos, &datalen, sizeof(datalen));
 	send_sctp_msg(g_acptReqInfo->enb_fd, g_ctxrel_buffer.buf, g_ctxrel_buffer.pos,1);

 	log_msg(LOG_INFO,"S1 Release sent to UE");

 	return SUCCESS;
 }

 /**
 * Thread function for stage.
 */
 void*
 detach_accept_handler(void *data)
 {
    log_msg(LOG_INFO, "detach accept handler ready.\n");
    struct detach_accept_Q_msg *msg = (struct detach_accept_Q_msg *)data;

    detach_accept_processing(msg);
    ue_ctx_release_processing(msg);

    return NULL;
 }
	/*
	* Copyright (c) 2003-2018, Great Software Laboratory Pvt. Ltd.
	* Copyright (c) 2017 Intel Corporation
	*
	* 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 <stdio.h>
	#include <stdlib.h>
	#include <pthread.h>
	#include <string.h>
	#include <unistd.h>
	#include <stdint.h>

	#include "log.h"
	#include "err_codes.h"
	#include "message_queues.h"
	#include "ipc_api.h"
	#include "s1ap.h"
	#include "s1ap_config.h"
	#include "main.h"
	#include "msgType.h"

	static int
	get_detach_accept_protoie_value(struct proto_IE value, struct detach_accept_Q_msg g_acptReqInfo)
	{
	uint8_t ieCnt = 0;

	value->no_of_IEs = DTCH_ACCEPT_NO_OF_IES;

	value->data = (proto_IEs ) malloc(DTCH_ACCEPT_NO_OF_IES
	sizeof(proto_IEs));

	value->data[ieCnt].val.mme_ue_s1ap_id = g_acptReqInfo->ue_idx;
	ieCnt++;

	value->data[ieCnt].val.enb_ue_s1ap_id = g_acptReqInfo->enb_s1ap_ue_id;
	ieCnt++;

	struct nasPDU *nas = &(value->data[ieCnt].val.nas);
	nas->header.security_header_type = IntegrityProtectedCiphered;
	nas->header.proto_discriminator = EPSMobilityManagementMessages;

	/* placeholder for mac. mac value will be calculated later */
	uint8_t mac[MAC_SIZE] = {0};
	memcpy(nas->header.mac, mac, MAC_SIZE);

	nas->header.seq_no = g_acptReqInfo->dl_seq_no;
	nas->header.message_type = DetachAccept;

	ieCnt++;

	return SUCCESS;
	}

	/**
	* Stage specific message processing.
	*/
	static int
	detach_accept_processing(struct detach_accept_Q_msg *g_acptReqInfo)
	{
	unsigned char tmpStr[4];
	struct s1ap_PDU s1apPDU= {0};
	uint16_t protocolIe_Id;
	uint8_t protocolIe_criticality = CRITICALITY_REJECT;
	uint8_t initiating_msg = 0;
	uint8_t datalen = 0;
	uint8_t s1ap_len_pos;
	uint8_t nas_len_pos;
	uint8_t u8value = 0;
	uint8_t mac_data_pos;

	Buffer g_acpt_buffer;

	s1apPDU.procedurecode = id_downlinkNASTransport;
	s1apPDU.criticality = CRITICALITY_IGNORE;

	get_detach_accept_protoie_value(&s1apPDU.value, g_acptReqInfo);

	g_acpt_buffer.pos = 0;

	buffer_copy(&g_acpt_buffer, &initiating_msg,
	sizeof(initiating_msg));

	buffer_copy(&g_acpt_buffer, &s1apPDU.procedurecode,
	sizeof(s1apPDU.procedurecode));

	buffer_copy(&g_acpt_buffer, &s1apPDU.criticality,
	sizeof(s1apPDU.criticality));

	s1ap_len_pos = g_acpt_buffer.pos;

	/* length of Detach Accept */
	u8value = 0;
	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

	/* TODO remove hardcoded values */
	uint8_t chProtoIENo[3] = {0,0,3};
	buffer_copy(&g_acpt_buffer, chProtoIENo, 3);

	/* id-MME-UE-S1AP-ID */
	protocolIe_Id = id_MME_UE_S1AP_ID;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));
	datalen = 2;
	/* TODO need to add proper handling*/
	unsigned char mme_ue_id[3];
	datalen = copyU16(mme_ue_id, s1apPDU.value.data[0].val.mme_ue_s1ap_id);
	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));
	buffer_copy(&g_acpt_buffer, mme_ue_id, datalen);

	/* id-eNB-UE-S1AP-ID */
	protocolIe_Id = id_eNB_UE_S1AP_ID;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));
	/* TODO needs proper handling*/
	unsigned char enb_ue_id[3];
	datalen = copyU16(enb_ue_id, s1apPDU.value.data[1].val.enb_ue_s1ap_id);
	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));
	buffer_copy(&g_acpt_buffer, enb_ue_id, datalen);

	/* NAS PDU start */
	protocolIe_Id = id_NAS_PDU;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_acpt_buffer, tmpStr, sizeof(protocolIe_Id));
	buffer_copy(&g_acpt_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));

	nas_len_pos = g_acpt_buffer.pos;

	datalen = 0;
	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));

	buffer_copy(&g_acpt_buffer, &datalen, sizeof(datalen));

	nas_pdu_header *nas_hdr = &(s1apPDU.value.data[2].val.nas.header);

	/* security header and protocol discriminator */
	u8value = (nas_hdr->security_header_type << 4 \|
	nas_hdr->proto_discriminator);
	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

	/* mac */
	/* placeholder for mac. mac value will be calculated later */
	buffer_copy(&g_acpt_buffer, nas_hdr->mac, MAC_SIZE);
	mac_data_pos = g_acpt_buffer.pos;

	/* sequence number */
	buffer_copy(&g_acpt_buffer, &(nas_hdr->seq_no),
	sizeof(nas_hdr->seq_no));

	/* security header and protocol discriminator */
	nas_hdr->security_header_type = Plain;
	u8value = (nas_hdr->security_header_type << 4 \|
	nas_hdr->proto_discriminator);
	buffer_copy(&g_acpt_buffer, &u8value, sizeof(u8value));

	/* message type */
	buffer_copy(&g_acpt_buffer, &(nas_hdr->message_type),
	sizeof(nas_hdr->message_type));

	/* NAS PDU end */

	/* Calculate mac */
	uint8_t direction = 1;
	uint8_t bearer = 0;

	calculate_mac(g_acptReqInfo->int_key, nas_hdr->seq_no,
	direction, bearer, &g_acpt_buffer.buf[mac_data_pos],
	g_acpt_buffer.pos - mac_data_pos,
	&g_acpt_buffer.buf[mac_data_pos - MAC_SIZE]);

	/* Copy nas length to nas length field */
	datalen = g_acpt_buffer.pos - nas_len_pos -1;
	memcpy(&(g_acpt_buffer.buf[nas_len_pos]), &datalen, sizeof(datalen));

	/* Copy nas length to nas length field */
	datalen = g_acpt_buffer.pos - nas_len_pos - 2;
	memcpy(&(g_acpt_buffer.buf[nas_len_pos + 1]), &datalen, sizeof(datalen));

	/* Copy length to s1ap length field */
	datalen = g_acpt_buffer.pos - s1ap_len_pos - 1;
	memcpy(g_acpt_buffer.buf + s1ap_len_pos, &datalen, sizeof(datalen));

	/* TODO: temp fix */
	//g_ics_buffer.buf[1] = 0x09;
	send_sctp_msg(g_acptReqInfo->enb_fd, g_acpt_buffer.buf, g_acpt_buffer.pos,1);

	log_msg(LOG_INFO, "Detach Accept sent to UE.");

	return SUCCESS;
	}

	/**
	* essage processing for ue context release
	*/
	static int
	ue_ctx_release_processing(struct detach_accept_Q_msg *g_acptReqInfo)
	{
	Buffer g_ctxrel_buffer;
	unsigned char tmpStr[4];
	struct s1ap_PDU s1apPDU;
	uint16_t protocolIe_Id;
	uint8_t protocolIe_criticality = CRITICALITY_REJECT;
	uint8_t initiating_msg = 0;
	uint8_t datalen = 0;
	uint8_t s1ap_len_pos;
	uint8_t u8value = 0;

	s1apPDU.procedurecode = id_UEContexRelease;
	s1apPDU.criticality = CRITICALITY_IGNORE;

	g_ctxrel_buffer.pos = 0;

	buffer_copy(&g_ctxrel_buffer, &initiating_msg,
	sizeof(initiating_msg));

	buffer_copy(&g_ctxrel_buffer, &s1apPDU.procedurecode,
	sizeof(s1apPDU.procedurecode));

	buffer_copy(&g_ctxrel_buffer, &s1apPDU.criticality,
	sizeof(s1apPDU.criticality));

	s1ap_len_pos = g_ctxrel_buffer.pos;

	/* length of UE Context Release */
	u8value = 0;
	buffer_copy(&g_ctxrel_buffer, &u8value, sizeof(u8value));

	/* TODO remove hardcoded values */
	uint8_t chProtoIENo[3] = {0,0,2};
	buffer_copy(&g_ctxrel_buffer, chProtoIENo, 3);

	/* id-UE-S1AP-IDs */
	protocolIe_Id = id_UE_S1AP_IDs;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_ctxrel_buffer, tmpStr, sizeof(protocolIe_Id));
	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));

	uint8_t mme_ue_id[4];
	uint8_t mme_ue_id_len = copyU16(mme_ue_id,
	s1apPDU.value.data[0].val.mme_ue_s1ap_id);

	if (mme_ue_id[0] == 0x40 \|\| mme_ue_id[0] == 0x80)
	mme_ue_id[0] = ((mme_ue_id[0] & 0x0F)<<4 \|
	(mme_ue_id[0] & 0xF0)>>4);

	uint8_t enb_ue_id[4];
	uint8_t enb_ue_id_len = copyU16(enb_ue_id,
	s1apPDU.value.data[1].val.enb_ue_s1ap_id);

	datalen = mme_ue_id_len + enb_ue_id_len;
	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
	buffer_copy(&g_ctxrel_buffer, mme_ue_id, mme_ue_id_len);
	buffer_copy(&g_ctxrel_buffer, enb_ue_id, enb_ue_id_len);

	#if 0
	/* id-MME-UE-S1AP-ID */
	protocolIe_Id = id_MME_UE_S1AP_ID;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_ctxrel_buffer, tmpStr,
	sizeof(protocolIe_Id));

	protocolIe_criticality = CRITICALITY_REJECT;
	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));

	datalen = 2;

	/* TODO needs proper handling*/
	unsigned char mme_ue_id[4];
	datalen = copyU16(mme_ue_id, s1apPDU.value.data[0].val.mme_ue_s1ap_id);
	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
	buffer_copy(&g_ctxrel_buffer, mme_ue_id, datalen);
	#endif

	/* id-Cause */
	protocolIe_Id = id_Cause;
	protocolIe_criticality = CRITICALITY_IGNORE;
	copyU16(tmpStr, protocolIe_Id);
	buffer_copy(&g_ctxrel_buffer, tmpStr, sizeof(protocolIe_Id));
	buffer_copy(&g_ctxrel_buffer, &protocolIe_criticality,
	sizeof(protocolIe_criticality));
	datalen = 1;
	buffer_copy(&g_ctxrel_buffer, &datalen, sizeof(datalen));
	/* TODO : Revisit. cause : nas(2) and value : detach (2), why 0x24 ? */
	u8value = 0x24;
	buffer_copy(&g_ctxrel_buffer, &u8value, sizeof(u8value));

	/* Copy length to s1ap length field */
	datalen = g_ctxrel_buffer.pos - s1ap_len_pos - 1;
	memcpy(g_ctxrel_buffer.buf + s1ap_len_pos, &datalen, sizeof(datalen));
	send_sctp_msg(g_acptReqInfo->enb_fd, g_ctxrel_buffer.buf, g_ctxrel_buffer.pos,1);

	log_msg(LOG_INFO,"S1 Release sent to UE");

	return SUCCESS;
	}

	/**
	* Thread function for stage.
	*/
	void*
	detach_accept_handler(void *data)
	{
	log_msg(LOG_INFO, "detach accept handler ready.\n");
	struct detach_accept_Q_msg msg = (struct detach_accept_Q_msg )data;

	detach_accept_processing(msg);
	ue_ctx_release_processing(msg);

	return NULL;
	}