/**
 *
 * \section COPYRIGHT
 *
 * Copyright 2013-2017 Software Radio Systems Limited
 *
 * \section LICENSE
 *
 * This file is part of the srsLTE library.
 *
 * srsUE is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of
 * the License, or (at your option) any later version.
 *
 * srsUE is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * A copy of the GNU Affero General Public License can be found in
 * the LICENSE file in the top-level directory of this distribution
 * and at http://www.gnu.org/licenses/.
 *
 */


#include "srslte/upper/gtpu.h"


namespace srslte {

/****************************************************************************
 * Header pack/unpack helper functions
 * Ref: 3GPP TS 29.281 v10.1.0 Section 5
 ***************************************************************************/

bool gtpu_write_header(gtpu_header_t *header, srslte::byte_buffer_t *pdu)
{
  if(header->flags != 0x30) {
    //gtpu_log->error("gtpu_write_header - Unhandled header flags: 0x%x\n", header->flags);
    return false;
  }
  if(header->message_type != 0xFF) {
    //gtpu_log->error("gtpu_write_header - Unhandled message type: 0x%x\n", header->message_type);
    return false;
  }
  if(pdu->get_headroom() < GTPU_HEADER_LEN) {
    //gtpu_log->error("gtpu_write_header - No room in PDU for header\n");
    return false;
  }

  pdu->msg      -= GTPU_HEADER_LEN;
  pdu->N_bytes  += GTPU_HEADER_LEN;

  uint8_t *ptr = pdu->msg;

  *ptr = header->flags;
  ptr++;
  *ptr = header->message_type;
  ptr++;
  uint16_to_uint8(header->length, ptr);
  ptr += 2;
  uint32_to_uint8(header->teid, ptr);

  return true;
}

bool gtpu_read_header(srslte::byte_buffer_t *pdu, gtpu_header_t *header)
{
  uint8_t *ptr  = pdu->msg;

  pdu->msg      += GTPU_HEADER_LEN;
  pdu->N_bytes  -= GTPU_HEADER_LEN;

  header->flags         = *ptr;
  ptr++;
  header->message_type  = *ptr;
  ptr++;
  uint8_to_uint16(ptr, &header->length);
  ptr += 2;
  uint8_to_uint32(ptr, &header->teid);

  if(header->flags != 0x30) {
    //gtpu_log->error("gtpu_read_header - Unhandled header flags: 0x%x\n", header->flags);
    return false;
  }
  if(header->message_type != 0xFF) {
    //gtpu_log->error("gtpu_read_header - Unhandled message type: 0x%x\n", header->message_type);
    return false;
  }

  return true;
}

} // namespace srslte