/*

 * This file is part of PowerDNS or dnsdist.

 * Copyright -- PowerDNS.COM B.V. and its contributors

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of version 2 of the GNU General Public License as

 * published by the Free Software Foundation.

 *

 * In addition, for the avoidance of any doubt, permission is granted to

 * link this program with OpenSSL and to (re)distribute the binaries

 * produced as the result of such linking.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include "config.h"

#include "base64.hh"

#include <limits>

#include <memory>

#include <stdexcept>

#include <boost/scoped_array.hpp>

#include <openssl/bio.h>

#include <openssl/evp.h>

template <typename Container>

int B64Decode(const std::string& src, Container& dst)

{

  if (src.empty()) {

    dst.clear();

    return 0;

  }

  // check if the dlen computation might overflow or it does not fit into an int (for IO_write)

  if (src.length() > std::numeric_limits<size_t>::max() / 7U || src.length() > std::numeric_limits<int>::max()) {

    throw std::runtime_error("B64Decode too large");

  }

  const size_t dlen = (src.length() * 6U + 7U) / 8U;

  dst.resize(dlen);

  auto bio = std::unique_ptr<BIO, void (*)(BIO*)>(BIO_new(BIO_s_mem()), BIO_free_all);

  if (!bio) {

    throw std::runtime_error("BIO_new failed");

  }

  if (BIO_write(bio.get(), src.c_str(), src.length()) != static_cast<int>(src.length())) {

    throw std::runtime_error("BIO_write failed");

  }

  auto* b64 = BIO_new(BIO_f_base64());

  if (b64 == nullptr) {

    throw std::runtime_error("BIO_new failed");

  }

  bio = std::unique_ptr<BIO, void (*)(BIO*)>(BIO_push(b64, bio.release()), BIO_free_all);

  BIO_set_flags(bio.get(), BIO_FLAGS_BASE64_NO_NL);

  auto olen = BIO_read(b64, &dst.at(0), dlen);

  if ((olen == 0 || olen == -1) && BIO_should_retry(bio.get())) {

    throw std::runtime_error("BIO_read failed to read all data from memory buffer");

  }

  bio.reset();

  if (olen > 0) {

    dst.resize(olen);

    return 0;

  }

  return -1;

}

template int B64Decode<std::string>(const std::string& strInput, std::string& strOutput);

std::string Base64Encode(const std::string& src)

{

  if (!src.empty()) {

    auto bio = std::unique_ptr<BIO, void (*)(BIO*)>(BIO_new(BIO_s_mem()), BIO_free_all);

    if (!bio) {

      throw std::runtime_error("BIO_new failed");

    }

    auto* b64 = BIO_new(BIO_f_base64());

    if (b64 == nullptr) {

      throw std::runtime_error("BIO_new failed");

    }

    bio = std::unique_ptr<BIO, void (*)(BIO*)>(BIO_push(b64, bio.release()), BIO_free_all);

    BIO_set_flags(bio.get(), BIO_FLAGS_BASE64_NO_NL);

    int bioWriteRet = BIO_write(bio.get(), src.c_str(), src.length());

    if (bioWriteRet < 0 || static_cast<size_t>(bioWriteRet) != src.length()) {

      throw std::runtime_error("BIO_write failed to write all data to memory buffer");

    }

    (void)BIO_flush(bio.get());

    char* pp;

    std::string out;

    auto olen = BIO_get_mem_data(bio.get(), &pp);

    if (olen > 0) {

      out = std::string(pp, olen);

    }

    bio.reset();

    return out;

  }

  return "";

}

#if 0

#include <iostream>

int main() {

  std::string in = "PowerDNS Test String 1";

  std::string out = Base64Encode(in);

  std::cout << out << std::endl;

  if (out != "UG93ZXJETlMgVGVzdCBTdHJpbmcgMQ==") {

    std::cerr << "output did not match expected data" << std::endl;

  }

  std::string roundtrip;

  B64Decode(out, roundtrip);

  std::cout << roundtrip << std::endl;

  if (roundtrip != in) {

    std::cerr << "roundtripped data did not match input data" << std::endl;

  }

  return 0;

}

#endif