// 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);
}
// 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();
}
// 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));
}
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 ExternalConnector::socketConnected()
{
sendHandShake();
}