/* <!-- copyright */
/*
 * aria2 - The high speed download utility
 *
 * Copyright (C) 2006 Tatsuhiro Tsujikawa
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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
 *
 * In addition, as a special exception, the copyright holders give
 * permission to link the code of portions of this program with the
 * OpenSSL library under certain conditions as described in each
 * individual source file, and distribute linked combinations
 * including the two.
 * You must obey the GNU General Public License in all respects
 * for all of the code used other than OpenSSL.  If you modify
 * file(s) with this exception, you may extend this exception to your
 * version of the file(s), but you are not obligated to do so.  If you
 * do not wish to do so, delete this exception statement from your
 * version.  If you delete this exception statement from all source
 * files in the program, then also delete it here.
 */
/* copyright --> */
#include "DHTTokenTracker.h"

#include <cstring>

#include "util.h"
#include "bittorrent_helper.h"
#include "DlAbortEx.h"
#include "DHTConstants.h"
#include "MessageDigest.h"
#include "message_digest_helper.h"
#include "fmt.h"

namespace aria2 {

DHTTokenTracker::DHTTokenTracker()
{
  util::generateRandomData(secret_[0], SECRET_SIZE);
  memcpy(secret_[1], secret_[0], SECRET_SIZE);
}

DHTTokenTracker::DHTTokenTracker(const unsigned char* initialSecret)
{
  memcpy(secret_[0], initialSecret, SECRET_SIZE);
  memcpy(secret_[1], initialSecret, SECRET_SIZE);
}

DHTTokenTracker::~DHTTokenTracker() {}

std::string DHTTokenTracker::generateToken
(const unsigned char* infoHash,
 const std::string& ipaddr, uint16_t port,
 const unsigned char* secret) const
{
  unsigned char src[DHT_ID_LENGTH+COMPACT_LEN_IPV6+SECRET_SIZE];
  memset(src, 0, sizeof(src));
  int compactlen = bittorrent::packcompact(src+DHT_ID_LENGTH, ipaddr, port);
  if(compactlen == 0) {
    throw DL_ABORT_EX
      (fmt("Token generation failed: ipaddr=%s, port=%u",
           ipaddr.c_str(), port));
  }
  memcpy(src, infoHash, DHT_ID_LENGTH);
  memcpy(src+DHT_ID_LENGTH+COMPACT_LEN_IPV6, secret, SECRET_SIZE);
  unsigned char md[20];
  message_digest::digest(md, sizeof(md), MessageDigest::sha1().get(),
                         src, sizeof(src));
  return std::string(&md[0], &md[sizeof(md)]);
}

std::string DHTTokenTracker::generateToken(const unsigned char* infoHash,
                                           const std::string& ipaddr, uint16_t port) const
{
  return generateToken(infoHash, ipaddr, port, secret_[0]);
}

bool DHTTokenTracker::validateToken(const std::string& token,
                                    const unsigned char* infoHash,
                                    const std::string& ipaddr, uint16_t port) const
{
  for(auto & elem : secret_) {
    if(generateToken(infoHash, ipaddr, port, elem) == token) {
      return true;
    }
  }
  return false;
}

void DHTTokenTracker::updateTokenSecret()
{
  memcpy(secret_[1], secret_[0], SECRET_SIZE);
  util::generateRandomData(secret_[0], SECRET_SIZE);
}

} // namespace aria2
