qt5base-lts/examples/network/torrent/bencodeparser.cpp

/****************************************************************************
**
** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).
** Contact: http://www.qt-project.org/
**
** This file is part of the examples of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** You may use this file under the terms of the BSD license as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * Redistributions in binary form must reproduce the above copyright
**     notice, this list of conditions and the following disclaimer in
**     the documentation and/or other materials provided with the
**     distribution.
**   * Neither the name of Nokia Corporation and its Subsidiary(-ies) nor
**     the names of its contributors may be used to endorse or promote
**     products derived from this software without specific prior written
**     permission.
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "bencodeparser.h"

#include <QList>
#include <QMetaType>

BencodeParser::BencodeParser()
{
}

bool BencodeParser::parse(const QByteArray &content)
{
    if (content.isEmpty()) {
        errString = QString("No content");
        return false;
    }

    this->content = content;
    index = 0;
    infoStart = 0;
    infoLength = 0;
    return getDictionary(&dictionaryValue);
}

QString BencodeParser::errorString() const
{
    return errString;
}

QMap<QByteArray, QVariant> BencodeParser::dictionary() const
{
    return dictionaryValue;
}

QByteArray BencodeParser::infoSection() const
{
    return content.mid(infoStart, infoLength);
}

bool BencodeParser::getByteString(QByteArray *byteString)
{
    const int contentSize = content.size();
    int size = -1;
    do {
	char c = content.at(index);
	if (c < '0' || c > '9') {
	    if (size == -1)
		return false;
	    if (c != ':') {
		errString = QString("Unexpected character at pos %1: %2")
		    .arg(index).arg(c);
		return false;
	    }
	    ++index;
	    break;
	}
	if (size == -1)
	    size = 0;
	size *= 10;
	size += c - '0';
    } while (++index < contentSize);

    if (byteString)
	*byteString = content.mid(index, size);
    index += size;
    return true;
}

bool BencodeParser::getInteger(qint64 *integer)
{
    const int contentSize = content.size();
    if (content.at(index) != 'i')
	return false;

    ++index;
    qint64 num = -1;
    bool negative = false;

    do {
	char c = content.at(index);
	if (c < '0' || c > '9') {
	    if (num == -1) {
		if (c != '-' || negative)
		    return false;
		negative = true;
		continue;
	    } else {
		if (c != 'e') {
		    errString = QString("Unexpected character at pos %1: %2")
			.arg(index).arg(c);
		    return false;
		}
		++index;
		break;
	    }
	}
	if (num == -1)
	    num = 0;
	num *= 10;
	num += c - '0';
    } while (++index < contentSize);

    if (integer)
	*integer = negative ? -num : num;
    return true;
}

bool BencodeParser::getList(QList<QVariant> *list)
{
    const int contentSize = content.size();
    if (content.at(index) != 'l')
	return false;

    QList<QVariant> tmp;    
    ++index;

    do {
	if (content.at(index) == 'e') {
	    ++index;
	    break;
	}

	qint64 number;
	QByteArray byteString;
	QList<QVariant> tmpList;
	QMap<QByteArray, QVariant> dictionary;

	if (getInteger(&number))
	    tmp << number;
	else if (getByteString(&byteString))
	    tmp << byteString;
	else if (getList(&tmpList))
	    tmp << tmpList;
	else if (getDictionary(&dictionary))
	    tmp << QVariant::fromValue<QMap<QByteArray, QVariant> >(dictionary);
	else {
	    errString = QString("error at index %1").arg(index);
	    return false;
	}
    } while (index < contentSize);

    if (list)
	*list = tmp;
    return true;
}

bool BencodeParser::getDictionary(QMap<QByteArray, QVariant> *dictionary)
{
    const int contentSize = content.size();
    if (content.at(index) != 'd')
	return false;

    QMap<QByteArray, QVariant> tmp;    
    ++index;

    do {
	if (content.at(index) == 'e') {
	    ++index;
	    break;
	}

	QByteArray key;
	if (!getByteString(&key))
	    break;

	if (key == "info")
	  infoStart = index;

	qint64 number;
	QByteArray byteString;
	QList<QVariant> tmpList;
	QMap<QByteArray, QVariant> dictionary;

	if (getInteger(&number))
	    tmp.insert(key, number);
	else if (getByteString(&byteString))
	    tmp.insert(key, byteString);
	else if (getList(&tmpList))
	    tmp.insert(key, tmpList);
	else if (getDictionary(&dictionary))
	    tmp.insert(key, QVariant::fromValue<QMap<QByteArray, QVariant> >(dictionary));
	else {
	    errString = QString("error at index %1").arg(index);
	    return false;
	}

	if (key == "info")
	  infoLength = index - infoStart;

    } while (index < contentSize);

    if (dictionary)
	*dictionary = tmp;
    return true;
}