aria2/src/PeerConnection.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 "PeerConnection.h"
#include "message.h"
#include "DlAbortEx.h"
#include "LogFactory.h"
#include "Logger.h"
#include "BtHandshakeMessage.h"
#include "Socket.h"
#include "a2netcompat.h"
#include "ARC4Encryptor.h"
#include "ARC4Decryptor.h"
#include "StringFormat.h"
#include <cstring>
#include <cassert>
#include <algorithm>

namespace aria2 {

PeerConnection::PeerConnection(int32_t cuid,
			       const SocketHandle& socket,
			       const Option* op)
  :cuid(cuid),
   socket(socket),
   option(op),
   logger(LogFactory::getInstance()),
   resbufLength(0),
   currentPayloadLength(0),
   lenbufLength(0),
   _encryptionEnabled(false),
   _prevPeek(false)
{}

PeerConnection::~PeerConnection() {}

ssize_t PeerConnection::sendMessage(const unsigned char* data, size_t dataLength) {
  if(socket->isWritable(0)) {
    // TODO fix this
    sendData(data, dataLength, _encryptionEnabled);
    return dataLength;
  } else {
    return 0;
  }
}

bool PeerConnection::receiveMessage(unsigned char* data, size_t& dataLength) {
  if(resbufLength == 0 && 4 > lenbufLength) {
    if(!socket->isReadable(0)) {
      return false;
    }
    // read payload size, 32bit unsigned integer
    size_t remaining = 4-lenbufLength;
    size_t temp = remaining;
    readData(lenbuf+lenbufLength, remaining, _encryptionEnabled);
    if(remaining == 0) {
      // we got EOF
      logger->debug("CUID#%d - In PeerConnection::receiveMessage(), remain=%zu",
		    cuid, temp);
      throw DlAbortEx(EX_EOF_FROM_PEER);
    }
    lenbufLength += remaining;
    if(4 > lenbufLength) {
      // still 4-lenbufLength bytes to go
      return false;
    }
    uint32_t payloadLength = ntohl(*(reinterpret_cast<uint32_t*>(lenbuf)));
    if(payloadLength > MAX_PAYLOAD_LEN) {
      throw DlAbortEx(StringFormat(EX_TOO_LONG_PAYLOAD, payloadLength).str());
    }
    currentPayloadLength = payloadLength;
  }
  if(!socket->isReadable(0)) {
    return false;
  }
  // we have currentPayloadLen-resbufLen bytes to read
  size_t remaining = currentPayloadLength-resbufLength;
  size_t temp = remaining;
  if(remaining > 0) {
    readData(resbuf+resbufLength, remaining, _encryptionEnabled);
    if(remaining == 0) {
      // we got EOF
      logger->debug("CUID#%d - In PeerConnection::receiveMessage(), payloadlen=%zu, remaining=%zu",
		    cuid, currentPayloadLength, temp);
      throw DlAbortEx(EX_EOF_FROM_PEER);
    }
    resbufLength += remaining;
    if(currentPayloadLength > resbufLength) {
      return false;
    }
  }
  // we got whole payload.
  resbufLength = 0;
  lenbufLength = 0;

  memcpy(data, resbuf, currentPayloadLength);
  dataLength = currentPayloadLength;
  return true;
}

bool PeerConnection::receiveHandshake(unsigned char* data, size_t& dataLength,
				      bool peek) {
  assert(BtHandshakeMessage::MESSAGE_LENGTH >= resbufLength);
  bool retval = true;
  if(_prevPeek && !peek && resbufLength) {
    // We have data in previous peek.
    // There is a chance that socket is readable because of EOF, for example,
    // official bttrack shutdowns socket after sending first 48 bytes of
    // handshake in its NAT checking.
    // So if there are data in resbuf, return it without checking socket
    // status.
    _prevPeek = false;
    retval = BtHandshakeMessage::MESSAGE_LENGTH <= resbufLength;
  } else {
    _prevPeek = peek;
    size_t remaining = BtHandshakeMessage::MESSAGE_LENGTH-resbufLength;
    if(remaining > 0 && !socket->isReadable(0)) {
      dataLength = 0;
      return false;
    }
    if(remaining > 0) {
      size_t temp = remaining;
      readData(resbuf+resbufLength, remaining, _encryptionEnabled);
      if(remaining == 0) {
	// we got EOF
	logger->debug("CUID#%d - In PeerConnection::receiveHandshake(), remain=%zu",
		      cuid, temp);
	throw DlAbortEx(EX_EOF_FROM_PEER);
      }
      resbufLength += remaining;
      if(BtHandshakeMessage::MESSAGE_LENGTH > resbufLength) {
	retval = false;
      }
    }
  }
  size_t writeLength = std::min(resbufLength, dataLength);
  memcpy(data, resbuf, writeLength);
  dataLength = writeLength;
  if(retval && !peek) {
    resbufLength = 0;
  }
  return retval;
}

void PeerConnection::readData(unsigned char* data, size_t& length, bool encryption)
{
  if(encryption) {
    unsigned char temp[MAX_PAYLOAD_LEN];
    assert(MAX_PAYLOAD_LEN >= length);
    socket->readData(temp, length);
    _decryptor->decrypt(data, length, temp, length);
  } else {
    socket->readData(data, length);
  }
}

void PeerConnection::sendData(const unsigned char* data, size_t length, bool encryption)
{
  if(encryption) {
    unsigned char temp[4096];
    const unsigned char* dptr = data;
    size_t r = length;
    while(r > 0) {
      size_t s = std::min(r, sizeof(temp));
      _encryptor->encrypt(temp, s, dptr, s);
      socket->writeData(temp, s);
      dptr += s;
      r -= s;
    }
  } else {
    socket->writeData(data, length);
  }
}

void PeerConnection::enableEncryption(const SharedHandle<ARC4Encryptor>& encryptor,
				      const SharedHandle<ARC4Decryptor>& decryptor)
{
  _encryptor = encryptor;
  _decryptor = decryptor;

  _encryptionEnabled = true;
}

void PeerConnection::presetBuffer(const unsigned char* data, size_t length)
{
  size_t nwrite = std::min((size_t)MAX_PAYLOAD_LEN, length);
  memcpy(resbuf, data, nwrite);
  resbufLength = length;
}

} // namespace aria2