hex-encode.cpp

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/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/*
 * Copyright (c) 2013-2021 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library 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 Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */

#include "ndn-cxx/security/transform/hex-encode.hpp"

namespace ndn {
namespace security {
namespace transform {

static const uint8_t H2CL[] = {
  '0', '1', '2', '3', '4', '5', '6', '7',
  '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};
static_assert(std::extent<decltype(H2CL)>::value == 16, "");

static const uint8_t H2CU[] = {
  '0', '1', '2', '3', '4', '5', '6', '7',
  '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
};
static_assert(std::extent<decltype(H2CU)>::value == 16, "");


HexEncode::HexEncode(bool useUpperCase)
  : m_useUpperCase(useUpperCase)
{
}

size_t
HexEncode::convert(span<const uint8_t> data)
{
  setOutputBuffer(toHex(data.data(), data.size()));
  return data.size();
}

unique_ptr<Transform::OBuffer>
HexEncode::toHex(const uint8_t* data, size_t dataLen)
{
  auto encoded = make_unique<OBuffer>(dataLen * 2);
  uint8_t* buf = encoded->data();
  const uint8_t* encodePad = m_useUpperCase ? H2CU : H2CL;

  for (size_t i = 0; i < dataLen; i++) {
    buf[0] = encodePad[(data[i] >> 4) & 0x0F];
    buf[1] = encodePad[data[i] & 0x0F];
    buf += 2;
  }

  return encoded;
}

unique_ptr<Transform>
hexEncode(bool useUpperCase)
{
  return make_unique<HexEncode>(useUpperCase);
}

} // namespace transform
} // namespace security
} // namespace ndn