aria2/src/DHTRoutingTableDeserializer.cc

/* <!-- 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 "DHTRoutingTableDeserializer.h"

#include <cstring>
#include <cassert>
#include <cstdio>
#include <utility>

#include "DHTNode.h"
#include "DHTConstants.h"
#include "bittorrent_helper.h"
#include "DlAbortEx.h"
#include "Logger.h"
#include "a2netcompat.h"
#include "fmt.h"
#include "util.h"
#include "array_fun.h"
#include "LogFactory.h"
#include "BufferedFile.h"

namespace aria2 {

DHTRoutingTableDeserializer::DHTRoutingTableDeserializer(int family)
    : family_(family)
{
}

DHTRoutingTableDeserializer::~DHTRoutingTableDeserializer() = default;

#define READ_CHECK(fp, ptr, count)                                             \
  if (fp.read((ptr), (count)) != (count)) {                                    \
    throw DL_ABORT_EX("Failed to load DHT routing table.");                    \
  }

namespace {
void readBytes(BufferedFile& fp, unsigned char* buf, size_t buflen,
               size_t readlen)
{
  assert(readlen <= buflen);
  READ_CHECK(fp, buf, readlen);
}
} // namespace

void DHTRoutingTableDeserializer::deserialize(const std::string& filename)
{
  A2_LOG_INFO(fmt("Loading DHT routing table from %s.", filename.c_str()));
  BufferedFile fp(filename.c_str(), BufferedFile::READ);
  if (!fp) {
    throw DL_ABORT_EX(
        fmt("Failed to load DHT routing table from %s", filename.c_str()));
  }
  char header[8];
  memset(header, 0, sizeof(header));
  // magic
  header[0] = 0xa1u;
  header[1] = 0xa2u;
  // format ID
  header[2] = 0x02u;
  // version
  header[6] = 0;
  header[7] = 0x03u;

  char headerCompat[8];
  memset(headerCompat, 0, sizeof(headerCompat));
  // magic
  headerCompat[0] = 0xa1u;
  headerCompat[1] = 0xa2u;
  // format ID
  headerCompat[2] = 0x02u;
  // version
  headerCompat[6] = 0;
  headerCompat[7] = 0x02u;

  char zero[18];
  memset(zero, 0, sizeof(zero));

  int version;

  // If you change the code to read more than the size of buf, then
  // expand the buf size here.
  array_wrapper<unsigned char, 255> buf;

  // header
  readBytes(fp, buf, buf.size(), 8);
  if (memcmp(header, buf, 8) == 0) {
    version = 3;
  }
  else if (memcmp(headerCompat, buf, 8) == 0) {
    version = 2;
  }
  else {
    throw DL_ABORT_EX(fmt("Failed to load DHT routing table from %s. cause:%s",
                          filename.c_str(), "bad header"));
  }

  uint32_t temp32;
  uint64_t temp64;
  // time
  if (version == 2) {
    READ_CHECK(fp, &temp32, sizeof(temp32));
    serializedTime_.setTimeFromEpoch(ntohl(temp32));
    // 4bytes reserved
    readBytes(fp, buf, buf.size(), 4);
  }
  else {
    READ_CHECK(fp, &temp64, sizeof(temp64));
    serializedTime_.setTimeFromEpoch(ntoh64(temp64));
  }

  // localnode
  // 8bytes reserved
  readBytes(fp, buf, buf.size(), 8);
  // localnode ID
  readBytes(fp, buf, buf.size(), DHT_ID_LENGTH);
  auto localNode = std::make_shared<DHTNode>(buf);
  // 4bytes reserved
  readBytes(fp, buf, buf.size(), 4);

  // number of nodes
  READ_CHECK(fp, &temp32, sizeof(temp32));
  uint32_t numNodes = ntohl(temp32);
  // 4bytes reserved
  readBytes(fp, buf, buf.size(), 4);

  std::vector<std::shared_ptr<DHTNode>> nodes;
  // nodes
  const int compactlen = bittorrent::getCompactLength(family_);
  for (size_t i = 0; i < numNodes; ++i) {
    // 1byte compact peer info length
    uint8_t peerInfoLen;
    READ_CHECK(fp, &peerInfoLen, sizeof(peerInfoLen));
    if (peerInfoLen != compactlen) {
      // skip this entry
      readBytes(fp, buf, buf.size(), 7 + 48);
      continue;
    }
    // 7bytes reserved
    readBytes(fp, buf, buf.size(), 7);
    // compactlen bytes compact peer info
    readBytes(fp, buf, buf.size(), compactlen);
    if (memcmp(zero, buf, compactlen) == 0) {
      // skip this entry
      readBytes(fp, buf, buf.size(), 48 - compactlen);
      continue;
    }
    std::pair<std::string, uint16_t> peer =
        bittorrent::unpackcompact(buf, family_);
    if (peer.first.empty()) {
      // skip this entry
      readBytes(fp, buf, buf.size(), 48 - compactlen);
      continue;
    }
    // 24-compactlen bytes reserved
    readBytes(fp, buf, buf.size(), 24 - compactlen);
    // node ID
    readBytes(fp, buf, buf.size(), DHT_ID_LENGTH);

    auto node = std::make_shared<DHTNode>(buf);
    node->setIPAddress(peer.first);
    node->setPort(peer.second);
    // 4bytes reserved
    readBytes(fp, buf, buf.size(), 4);

    nodes.push_back(node);
  }
  localNode_ = localNode;
  nodes_ = nodes;
  A2_LOG_INFO("DHT routing table was loaded successfully");
}

} // namespace aria2