- Qt 5.5
- Qt Network
- Torrent Example
- bencodeparser.cpp Example File
- Qt 5.5.1 Reference Documentation

# bencodeparser.cpp Example File

torrent/bencodeparser.cpp

    /****************************************************************************
    **
    ** Copyright (C) 2015 The Qt Company Ltd.
    ** Contact: http://www.qt.io/licensing/
    **
    ** 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 The Qt Company Ltd 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."
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    ****************************************************************************/

    #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;
    }