src/common/compressor.cpp

   1 /***************************************************************************
   2  *   Copyright (C) 2005-2014 by the Quassel Project                        *
   3  *   devel@quassel-irc.org                                                 *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
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   8  *   (at your option) version 3.                                           *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
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  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
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  20
  21 #include "compressor.h"
  22
  23 #include <QTcpSocket>
  24 #include <QTimer>
  25
  26 #define MINIZ_HEADER_FILE_ONLY
  27 #include "../../3rdparty/miniz/miniz.c"
  28
  29 const int maxBufferSize = 64 * 1024 * 1024; // protect us from zip bombs
  30 const int ioBufferSize = 64 * 1024;         // chunk size for inflate/deflate; should not be too large as we preallocate that space!
  31
  32 Compressor::Compressor(QTcpSocket *socket, Compressor::CompressionLevel level, QObject *parent)
  33     : QObject(parent),
  34     _socket(socket),
  35     _level(level),
  36     _inflater(0),
  37     _deflater(0)
  38 {
  39     connect(socket, SIGNAL(readyRead()), SLOT(readData()));
  40
  41     bool ok = true;
  42     if (level != NoCompression)
  43         ok = initStreams();
  44
  45     if (!ok) {
  46         // something went wrong during initialization... but we can only emit an error after RemotePeer has connected its signal
  47         QTimer::singleShot(0, this, SIGNAL(error()));
  48         return;
  49     }
  50
  51     // It's possible that more data has already arrived during the handshake, so readyRead() wouldn't be triggered.
  52     // However, we want to give RemotePeer a chance to connect to our signals, so trigger this asynchronously.
  53     if (socket->bytesAvailable())
  54         QTimer::singleShot(0, this, SLOT(readData()));
  55 }
  56
  57
  58 Compressor::~Compressor()
  59 {
  60     // release resources allocated by zlib
  61     if (_inflater) {
  62         inflateEnd(_inflater);
  63         delete _inflater;
  64     }
  65     if (_deflater) {
  66         deflateEnd(_deflater);
  67         delete _deflater;
  68     }
  69 }
  70
  71
  72 bool Compressor::initStreams()
  73 {
  74     int zlevel;
  75     switch(compressionLevel()) {
  76         case BestCompression:
  77             zlevel = 9;
  78             break;
  79         case BestSpeed:
  80             zlevel = 1;
  81             break;
  82         default:
  83             zlevel = Z_DEFAULT_COMPRESSION;
  84     }
  85
  86     _inflater = new z_stream;
  87     memset(_inflater, 0, sizeof(z_stream));
  88     if (Z_OK != inflateInit(_inflater)) {
  89         qWarning() << "Could not initialize the inflate stream!";
  90         return false;
  91     }
  92
  93     _deflater = new z_stream;
  94     memset(_deflater, 0, sizeof(z_stream));
  95     if (Z_OK != deflateInit(_deflater, zlevel)) {
  96         qWarning() << "Could not intialize the deflate stream!";
  97         return false;
  98     }
  99
 100     _inputBuffer.reserve(ioBufferSize); // pre-allocate space
 101     _outputBuffer.resize(ioBufferSize); // not a typo; we never change the size of this buffer anyway (we *do* for _inputBuffer!)
 102
 103     qDebug() << "Enabling compression...";
 104
 105     return true;
 106 }
 107
 108
 109
 110 qint64 Compressor::bytesAvailable() const
 111 {
 112     return _readBuffer.size();
 113 }
 114
 115
 116 qint64 Compressor::read(char *data, qint64 maxSize)
 117 {
 118     if (maxSize <= 0)
 119         maxSize = _readBuffer.size();
 120
 121     qint64 n = qMin(maxSize, (qint64)_readBuffer.size());
 122     memcpy(data, _readBuffer.constData(), n);
 123
 124     // TODO: don't copy for every read
 125     if (n == _readBuffer.size())
 126         _readBuffer.clear();
 127     else
 128         _readBuffer = _readBuffer.mid(n);
 129
 130     // If there's still data left in the socket buffer, make sure to schedule a read
 131     if (_socket->bytesAvailable())
 132         QTimer::singleShot(0, this, SLOT(readData()));
 133
 134     return n;
 135 }
 136
 137
 138 // The usual usage pattern is to write a blocksize first, followed by the actual data.
 139 // By setting NoFlush, one can indicate that the write buffer should not immediately be
 140 // written, which should make things a bit more efficient.
 141 qint64 Compressor::write(const char *data, qint64 count, WriteBufferHint flush)
 142 {
 143     int pos = _writeBuffer.size();
 144     _writeBuffer.resize(pos + count);
 145     memcpy(_writeBuffer.data() + pos, data, count);
 146
 147     if (flush != NoFlush)
 148         writeData();
 149
 150     return count;
 151 }
 152
 153
 154 void Compressor::readData()
 155 {
 156     // don't try to read more data if we're already closing
 157     if (_socket->state() !=  QAbstractSocket::ConnectedState)
 158         return;
 159
 160     if (!_socket->bytesAvailable() || _readBuffer.size() >= maxBufferSize)
 161         return;
 162
 163     if (compressionLevel() == NoCompression) {
 164         _readBuffer.append(_socket->read(maxBufferSize - _readBuffer.size()));
 165         emit readyRead();
 166         return;
 167     }
 168
 169     // We let zlib directly append to the readBuffer, which means we pre-allocate extra space for ioBufferSize.
 170     // Afterwards, we'll shrink the buffer appropriately. Since shrinking should not reallocate, the readBuffer's
 171     // capacity should over time adapt to the largest message sizes we encounter. However, this is not a bad thing
 172     // considering that otherwise (using an intermediate buffer) we'd copy around data for every single message.
 173     // TODO: Benchmark if it would still make sense to squeeze the buffer from time to time (e.g. after initial sync)!
 174
 175     while (_socket->bytesAvailable() && _readBuffer.size() + ioBufferSize < maxBufferSize && _inputBuffer.size() < ioBufferSize) {
 176         _readBuffer.resize(_readBuffer.size() + ioBufferSize);
 177         _inputBuffer.append(_socket->read(ioBufferSize - _inputBuffer.size()));
 178
 179         _inflater->next_in = reinterpret_cast<const unsigned char *>(_inputBuffer.constData());
 180         _inflater->avail_in = _inputBuffer.size();
 181         _inflater->next_out = reinterpret_cast<unsigned char *>(_readBuffer.data() + _readBuffer.size() - ioBufferSize);
 182         _inflater->avail_out = ioBufferSize;
 183
 184         const unsigned char *orig_out = _inflater->next_out; // so we see if we have actually produced any output
 185
 186         int status = inflate(_inflater, Z_SYNC_FLUSH); // get as much data as possible
 187
 188         // adjust input and output buffers
 189         _readBuffer.resize(_inflater->next_out - reinterpret_cast<const unsigned char *>(_readBuffer.constData()));
 190         if (_inflater->avail_in > 0)
 191             memmove(_inputBuffer.data(), _inflater->next_in, _inflater->avail_in);
 192         _inputBuffer.resize(_inflater->avail_in);
 193
 194         if (_inflater->next_out != orig_out)
 195             emit readyRead();
 196
 197         switch(status) {
 198             case Z_NEED_DICT:
 199             case Z_DATA_ERROR:
 200             case Z_MEM_ERROR:
 201             case Z_STREAM_ERROR:
 202                 qWarning() << "Error while decompressing stream:" << status;
 203                 emit error(StreamError);
 204                 return;
 205             case Z_BUF_ERROR:
 206                 // means that we need more input to continue, so this is not an actual error
 207                 return;
 208             case Z_STREAM_END:
 209                 qWarning() << "Reached end of zlib stream!"; // this should really never happen
 210                 return;
 211             default:
 212                 // just try to get more out of the stream
 213                 break;
 214         }
 215     }
 216     //qDebug() << "inflate in:" << _inflater->total_in << "out:" << _inflater->total_out << "ratio:" << (double)_inflater->total_in/_inflater->total_out;
 217 }
 218
 219
 220 void Compressor::writeData()
 221 {
 222     if (compressionLevel() == NoCompression) {
 223         _socket->write(_writeBuffer);
 224         _writeBuffer.clear();
 225         return;
 226     }
 227
 228     _deflater->next_in = reinterpret_cast<const unsigned char *>(_writeBuffer.constData());
 229     _deflater->avail_in = _writeBuffer.size();
 230
 231     int status;
 232     do {
 233         _deflater->next_out = reinterpret_cast<unsigned char *>(_outputBuffer.data());
 234         _deflater->avail_out = ioBufferSize;
 235         status = deflate(_deflater, Z_PARTIAL_FLUSH);
 236         if (status != Z_OK && status != Z_BUF_ERROR) {
 237             qWarning() << "Error while compressing stream:" << status;
 238             emit error(StreamError);
 239             return;
 240         }
 241
 242         if (_deflater->avail_out == ioBufferSize)
 243             continue; // nothing to write here
 244
 245         if (!_socket->write(_outputBuffer.constData(), ioBufferSize - _deflater->avail_out)) {
 246             qWarning() << "Error while writing to socket:" << _socket->errorString();
 247             emit error(DeviceError);
 248             return;
 249         }
 250     } while (_deflater->avail_out == 0); // the output buffer being full is the only reason we should have to loop here!
 251
 252     if (_deflater->avail_in > 0) {
 253         qWarning() << "Oops, something weird happened: data still remaining in write buffer!";
 254         emit error(StreamError);
 255     }
 256
 257     _writeBuffer.resize(0);
 258
 259     //qDebug() << "deflate in:" << _deflater->total_in << "out:" << _deflater->total_out << "ratio:" << (double)_deflater->total_out/_deflater->total_in;
 260 }
 261
 262
 263 void Compressor::flush()
 264 {
 265     if (compressionLevel() == NoCompression && _socket->state() == QAbstractSocket::ConnectedState)
 266         _socket->flush();
 267
 268     // FIXME: missing impl for enabled compression; but then we're not using this method yet
 269 }