Torrent Example▲
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#include "peerwireclient.h"
#include <QHostAddress>
#include <QTimerEvent>
static const int PendingRequestTimeout = 60 * 1000;
static const int ClientTimeout = 120 * 1000;
static const int ConnectTimeout = 60 * 1000;
static const int KeepAliveInterval = 30 * 1000;
static const int RateControlTimerDelay = 2000;
static const int MinimalHeaderSize = 48;
static const char ProtocolId[] = "BitTorrent protocol";
static const char ProtocolIdSize = 19;
// Reads a 32bit unsigned int from data in network order.
static inline quint32 fromNetworkData(const char *data)
{
const unsigned char *udata = (const unsigned char *)data;
return (quint32(udata[0]) << 24)
| (quint32(udata[1]) << 16)
| (quint32(udata[2]) << 8)
| (quint32(udata[3]));
}
// Writes a 32bit unsigned int from num to data in network order.
static inline void toNetworkData(quint32 num, char *data)
{
unsigned char *udata = (unsigned char *)data;
udata[3] = (num & 0xff);
udata[2] = (num & 0xff00) >> 8;
udata[1] = (num & 0xff0000) >> 16;
udata[0] = (num & 0xff000000) >> 24;
}
// Constructs an unconnected PeerWire client and starts the connect timer.
PeerWireClient::PeerWireClient(const QByteArray &peerId, QObject *parent)
: QTcpSocket(parent), pendingBlockSizes(0),
pwState(ChokingPeer | ChokedByPeer), receivedHandShake(false), gotPeerId(false),
sentHandShake(false), nextPacketLength(-1), pendingRequestTimer(0), invalidateTimeout(false),
keepAliveTimer(0), torrentPeer(0)
{
memset(uploadSpeedData, 0, sizeof(uploadSpeedData));
memset(downloadSpeedData, 0, sizeof(downloadSpeedData));
transferSpeedTimer = startTimer(RateControlTimerDelay);
timeoutTimer = startTimer(ConnectTimeout);
peerIdString = peerId;
connect(this, SIGNAL(readyRead()), this, SIGNAL(readyToTransfer()));
connect(this, SIGNAL(connected()), this, SIGNAL(readyToTransfer()));
connect(&socket, SIGNAL(connected()),
this, SIGNAL(connected()));
connect(&socket, SIGNAL(readyRead()),
this, SIGNAL(readyRead()));
connect(&socket, SIGNAL(disconnected()),
this, SIGNAL(disconnected()));
connect(&socket, SIGNAL(error(QAbstractSocket::SocketError)),
this, SIGNAL(error(QAbstractSocket::SocketError)));
connect(&socket, SIGNAL(bytesWritten(qint64)),
this, SIGNAL(bytesWritten(qint64)));
connect(&socket, SIGNAL(stateChanged(QAbstractSocket::SocketState)),
this, SLOT(socketStateChanged(QAbstractSocket::SocketState)));
}
// Registers the peer ID and SHA1 sum of the torrent, and initiates
// the handshake.
void PeerWireClient::initialize(const QByteArray &infoHash, int pieceCount)
{
this->infoHash = infoHash;
peerPieces.resize(pieceCount);
if (!sentHandShake)
sendHandShake();
}
void PeerWireClient::setPeer(TorrentPeer *peer)
{
torrentPeer = peer;
}
TorrentPeer *PeerWireClient::peer() const
{
return torrentPeer;
}
QBitArray PeerWireClient::availablePieces() const
{
return peerPieces;
}
QList<TorrentBlock> PeerWireClient::incomingBlocks() const
{
return incoming;
}
// Sends a "choke" message, asking the peer to stop requesting blocks.
void PeerWireClient::chokePeer()
{
const char message[] = {0, 0, 0, 1, 0};
write(message, sizeof(message));
pwState |= ChokingPeer;
// After receiving a choke message, the peer will assume all
// pending requests are lost.
pendingBlocks.clear();
pendingBlockSizes = 0;
}
// Sends an "unchoke" message, allowing the peer to start/resume
// requesting blocks.
void PeerWireClient::unchokePeer()
{
const char message[] = {0, 0, 0, 1, 1};
write(message, sizeof(message));
pwState &= ~ChokingPeer;
if (pendingRequestTimer)
killTimer(pendingRequestTimer);
}
// Sends a "keep-alive" message to prevent the peer from closing
// the connection when there's no activity
void PeerWireClient::sendKeepAlive()
{
const char message[] = {0, 0, 0, 0};
write(message, sizeof(message));
}
// Sends an "interested" message, informing the peer that it has got
// pieces that we'd like to download.
void PeerWireClient::sendInterested()
{
const char message[] = {0, 0, 0, 1, 2};
write(message, sizeof(message));
pwState |= InterestedInPeer;
// After telling the peer that we're interested, we expect to get
// unchoked within a certain timeframe; otherwise we'll drop the
// connection.
if (pendingRequestTimer)
killTimer(pendingRequestTimer);
pendingRequestTimer = startTimer(PendingRequestTimeout);
}
// Sends a "not interested" message, informing the peer that it does
// not have any pieces that we'd like to download.
void PeerWireClient::sendNotInterested()
{
const char message[] = {0, 0, 0, 1, 3};
write(message, sizeof(message));
pwState &= ~InterestedInPeer;
}
// Sends a piece notification / a "have" message, informing the peer
// that we have just downloaded a new piece.
void PeerWireClient::sendPieceNotification(int piece)
{
if (!sentHandShake)
sendHandShake();
char message[] = {0, 0, 0, 5, 4, 0, 0, 0, 0};
toNetworkData(piece, &message[5]);
write(message, sizeof(message));
}
// Sends the complete list of pieces that we have downloaded.
void PeerWireClient::sendPieceList(const QBitArray &bitField)
{
// The bitfield message may only be sent immediately after the
// handshaking sequence is completed, and before any other
// messages are sent.
if (!sentHandShake)
sendHandShake();
// Don't send the bitfield if it's all zeros.
if (bitField.count(true) == 0)
return;
int bitFieldSize = bitField.size();
int size = (bitFieldSize + 7) / 8;
QByteArray bits(size, '\0');
for (int i = 0; i < bitFieldSize; ++i) {
if (bitField.testBit(i)) {
quint32 byte = quint32(i) / 8;
quint32 bit = quint32(i) % 8;
bits[byte] = uchar(bits.at(byte)) | (1 << (7 - bit));
}
}
char message[] = {0, 0, 0, 1, 5};
toNetworkData(bits.size() + 1, &message[0]);
write(message, sizeof(message));
write(bits);
}
// Sends a request for a block.
void PeerWireClient::requestBlock(int piece, int offset, int length)
{
char message[] = {0, 0, 0, 1, 6};
toNetworkData(13, &message[0]);
write(message, sizeof(message));
char numbers[4 * 3];
toNetworkData(piece, &numbers[0]);
toNetworkData(offset, &numbers[4]);
toNetworkData(length, &numbers[8]);
write(numbers, sizeof(numbers));
incoming << TorrentBlock(piece, offset, length);
// After requesting a block, we expect the block to be sent by the
// other peer within a certain number of seconds. Otherwise, we
// drop the connection.
if (pendingRequestTimer)
killTimer(pendingRequestTimer);
pendingRequestTimer = startTimer(PendingRequestTimeout);
}
// Cancels a request for a block.
void PeerWireClient::cancelRequest(int piece, int offset, int length)
{
char message[] = {0, 0, 0, 1, 8};
toNetworkData(13, &message[0]);
write(message, sizeof(message));
char numbers[4 * 3];
toNetworkData(piece, &numbers[0]);
toNetworkData(offset, &numbers[4]);
toNetworkData(length, &numbers[8]);
write(numbers, sizeof(numbers));
incoming.removeAll(TorrentBlock(piece, offset, length));
}
// Sends a block to the peer.
void PeerWireClient::sendBlock(int piece, int offset, const QByteArray &data)
{
QByteArray block;
char message[] = {0, 0, 0, 1, 7};
toNetworkData(9 + data.size(), &message[0]);
block += QByteArray(message, sizeof(message));
char numbers[4 * 2];
toNetworkData(piece, &numbers[0]);
toNetworkData(offset, &numbers[4]);
block += QByteArray(numbers, sizeof(numbers));
block += data;
BlockInfo blockInfo;
blockInfo.pieceIndex = piece;
blockInfo.offset = offset;
blockInfo.length = data.size();
blockInfo.block = block;
pendingBlocks << blockInfo;
pendingBlockSizes += block.size();
if (pendingBlockSizes > 32 * 16384) {
chokePeer();
unchokePeer();
return;
}
emit readyToTransfer();
}
// Attempts to write 'bytes' bytes to the socket from the buffer.
// This is used by RateController, which precisely controls how much
// each client can write.
qint64 PeerWireClient::writeToSocket(qint64 bytes)
{
qint64 totalWritten = 0;
do {
if (outgoingBuffer.isEmpty() && !pendingBlocks.isEmpty()) {
BlockInfo block = pendingBlocks.takeFirst();
pendingBlockSizes -= block.length;
outgoingBuffer += block.block;
}
qint64 written = socket.write(outgoingBuffer.constData(),
qMin<qint64>(bytes - totalWritten, outgoingBuffer.size()));
if (written <= 0)
return totalWritten ? totalWritten : written;
totalWritten += written;
uploadSpeedData[0] += written;
outgoingBuffer.remove(0, written);
} while (totalWritten < bytes && (!outgoingBuffer.isEmpty() || !pendingBlocks.isEmpty()));
return totalWritten;
}
// Attempts to read at most 'bytes' bytes from the socket.
qint64 PeerWireClient::readFromSocket(qint64 bytes)
{
char buffer[1024];
qint64 totalRead = 0;
do {
qint64 bytesRead = socket.read(buffer, qMin<qint64>(sizeof(buffer), bytes - totalRead));
if (bytesRead <= 0)
break;
qint64 oldSize = incomingBuffer.size();
incomingBuffer.resize(oldSize + bytesRead);
memcpy(incomingBuffer.data() + oldSize, buffer, bytesRead);
totalRead += bytesRead;
} while (totalRead < bytes);
if (totalRead > 0) {
downloadSpeedData[0] += totalRead;
emit bytesReceived(totalRead);
processIncomingData();
}
return totalRead;
}
// Returns the average number of bytes per second this client is
// downloading.
qint64 PeerWireClient::downloadSpeed() const
{
qint64 sum = 0;
for (unsigned int i = 0; i < sizeof(downloadSpeedData) / sizeof(qint64); ++i)
sum += downloadSpeedData[i];
return sum / (8 * 2);
}
// Returns the average number of bytes per second this client is
// uploading.
qint64 PeerWireClient::uploadSpeed() const
{
qint64 sum = 0;
for (unsigned int i = 0; i < sizeof(uploadSpeedData) / sizeof(qint64); ++i)
sum += uploadSpeedData[i];
return sum / (8 * 2);
}
void PeerWireClient::setReadBufferSize(qint64 size)
{
socket.setReadBufferSize(size);
}
bool PeerWireClient::canTransferMore() const
{
return bytesAvailable() > 0 || socket.bytesAvailable() > 0
|| !outgoingBuffer.isEmpty() || !pendingBlocks.isEmpty();
}
void PeerWireClient::connectToHost(const QHostAddress &address,
quint16 port, OpenMode openMode)
{
setOpenMode(openMode);
socket.connectToHost(address, port, openMode);
}
void PeerWireClient::diconnectFromHost()
{
socket.disconnectFromHost();
}
void PeerWireClient::timerEvent(QTimerEvent *event)
{
if (event->timerId() == transferSpeedTimer) {
// Rotate the upload / download records.
for (int i = 6; i >= 0; --i) {
uploadSpeedData[i + 1] = uploadSpeedData[i];
downloadSpeedData[i + 1] = downloadSpeedData[i];
}
uploadSpeedData[0] = 0;
downloadSpeedData[0] = 0;
} else if (event->timerId() == timeoutTimer) {
// Disconnect if we timed out; otherwise the timeout is
// restarted.
if (invalidateTimeout) {
invalidateTimeout = false;
} else {
abort();
emit infoHashReceived(QByteArray());
}
} else if (event->timerId() == pendingRequestTimer) {
abort();
} else if (event->timerId() == keepAliveTimer) {
sendKeepAlive();
}
QTcpSocket::timerEvent(event);
}
// Sends the handshake to the peer.
void PeerWireClient::sendHandShake()
{
sentHandShake = true;
// Restart the timeout
if (timeoutTimer)
killTimer(timeoutTimer);
timeoutTimer = startTimer(ClientTimeout);
// Write the 68 byte PeerWire handshake.
write(&ProtocolIdSize, 1);
write(ProtocolId, ProtocolIdSize);
write(QByteArray(8, '\0'));
write(infoHash);
write(peerIdString);
}
void PeerWireClient::processIncomingData()
{
invalidateTimeout = true;
if (!receivedHandShake) {
// Check that we received enough data
if (bytesAvailable() < MinimalHeaderSize)
return;
// Sanity check the protocol ID
QByteArray id = read(ProtocolIdSize + 1);
if (id.at(0) != ProtocolIdSize || !id.mid(1).startsWith(ProtocolId)) {
abort();
return;
}
// Discard 8 reserved bytes, then read the info hash and peer ID
(void) read(8);
// Read infoHash
QByteArray peerInfoHash = read(20);
if (!infoHash.isEmpty() && peerInfoHash != infoHash) {
abort();
return;
}
emit infoHashReceived(peerInfoHash);
if (infoHash.isEmpty()) {
abort();
return;
}
// Send handshake
if (!sentHandShake)
sendHandShake();
receivedHandShake = true;
}
// Handle delayed peer id arrival
if (!gotPeerId) {
if (bytesAvailable() < 20)
return;
gotPeerId = true;
if (read(20) == peerIdString) {
// We connected to ourself
abort();
return;
}
}
// Initialize keep-alive timer
if (!keepAliveTimer)
keepAliveTimer = startTimer(KeepAliveInterval);
do {
// Find the packet length
if (nextPacketLength == -1) {
if (bytesAvailable() < 4)
return;
char tmp[4];
read(tmp, sizeof(tmp));
nextPacketLength = fromNetworkData(tmp);
if (nextPacketLength < 0 || nextPacketLength > 200000) {
// Prevent DoS
abort();
return;
}
}
// KeepAlive
if (nextPacketLength == 0) {
nextPacketLength = -1;
continue;
}
// Wait with parsing until the whole packet has been received
if (bytesAvailable() < nextPacketLength)
return;
// Read the packet
QByteArray packet = read(nextPacketLength);
if (packet.size() != nextPacketLength) {
abort();
return;
}
switch (packet.at(0)) {
case ChokePacket:
// We have been choked.
pwState |= ChokedByPeer;
incoming.clear();
if (pendingRequestTimer)
killTimer(pendingRequestTimer);
emit choked();
break;
case UnchokePacket:
// We have been unchoked.
pwState &= ~ChokedByPeer;
emit unchoked();
break;
case InterestedPacket:
// The peer is interested in downloading.
pwState |= PeerIsInterested;
emit interested();
break;
case NotInterestedPacket:
// The peer is not interested in downloading.
pwState &= ~PeerIsInterested;
emit notInterested();
break;
case HavePacket: {
// The peer has a new piece available.
quint32 index = fromNetworkData(&packet.data()[1]);
if (index < quint32(peerPieces.size())) {
// Only accept indexes within the valid range.
peerPieces.setBit(int(index));
}
emit piecesAvailable(availablePieces());
break;
}
case BitFieldPacket:
// The peer has the following pieces available.
for (int i = 1; i < packet.size(); ++i) {
for (int bit = 0; bit < 8; ++bit) {
if (packet.at(i) & (1 << (7 - bit))) {
int bitIndex = int(((i - 1) * 8) + bit);
if (bitIndex >= 0 && bitIndex < peerPieces.size()) {
// Occasionally, broken clients claim to have
// pieces whose index is outside the valid range.
// The most common mistake is the index == size
// case.
peerPieces.setBit(bitIndex);
}
}
}
}
emit piecesAvailable(availablePieces());
break;
case RequestPacket: {
// The peer requests a block.
quint32 index = fromNetworkData(&packet.data()[1]);
quint32 begin = fromNetworkData(&packet.data()[5]);
quint32 length = fromNetworkData(&packet.data()[9]);
emit blockRequested(int(index), int(begin), int(length));
break;
}
case PiecePacket: {
int index = int(fromNetworkData(&packet.data()[1]));
int begin = int(fromNetworkData(&packet.data()[5]));
incoming.removeAll(TorrentBlock(index, begin, packet.size() - 9));
// The peer sends a block.
emit blockReceived(index, begin, packet.mid(9));
// Kill the pending block timer.
if (pendingRequestTimer) {
killTimer(pendingRequestTimer);
pendingRequestTimer = 0;
}
break;
}
case CancelPacket: {
// The peer cancels a block request.
quint32 index = fromNetworkData(&packet.data()[1]);
quint32 begin = fromNetworkData(&packet.data()[5]);
quint32 length = fromNetworkData(&packet.data()[9]);
for (int i = 0; i < pendingBlocks.size(); ++i) {
const BlockInfo &blockInfo = pendingBlocks.at(i);
if (blockInfo.pieceIndex == int(index)
&& blockInfo.offset == int(begin)
&& blockInfo.length == int(length)) {
pendingBlocks.removeAt(i);
break;
}
}
break;
}
default:
// Unsupported packet type; just ignore it.
break;
}
nextPacketLength = -1;
} while (bytesAvailable() > 0);
}
void PeerWireClient::socketStateChanged(QAbstractSocket::SocketState state)
{
setLocalAddress(socket.localAddress());
setLocalPort(socket.localPort());
setPeerName(socket.peerName());
setPeerAddress(socket.peerAddress());
setPeerPort(socket.peerPort());
setSocketState(state);
}
qint64 PeerWireClient::readData(char *data, qint64 size)
{
int n = qMin<int>(size, incomingBuffer.size());
memcpy(data, incomingBuffer.constData(), n);
incomingBuffer.remove(0, n);
return n;
}
qint64 PeerWireClient::readLineData(char *data, qint64 maxlen)
{
return QIODevice::readLineData(data, maxlen);
}
qint64 PeerWireClient::writeData(const char *data, qint64 size)
{
int oldSize = outgoingBuffer.size();
outgoingBuffer.resize(oldSize + size);
memcpy(outgoingBuffer.data() + oldSize, data, size);
emit readyToTransfer();
return size;
}