/****************************************************************************
**
** Copyright (C) 2016 Kurt Pattyn <pattyn.kurt@gmail.com>.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtWebSockets module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
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** accordance with the commercial license agreement provided with the
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** information use the contact form at https://www.qt.io/contact-us.
**
** GNU Lesser General Public License Usage
** Alternatively, this file may be used under the terms of the GNU Lesser
** General Public License version 3 as published by the Free Software
** Foundation and appearing in the file LICENSE.LGPL3 included in the
** packaging of this file. Please review the following information to
** ensure the GNU Lesser General Public License version 3 requirements
** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
**
** GNU General Public License Usage
** Alternatively, this file may be used under the terms of the GNU
** General Public License version 2.0 or (at your option) the GNU General
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** included in the packaging of this file. Please review the following
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** $QT_END_LICENSE$
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****************************************************************************/

/*!
    \class QWebSocketFrame
    The class QWebSocketFrame is responsible for reading, validating and
    interpreting frames from a WebSocket.
    It reads data from a QIODevice, validates it against RFC 6455, and parses it into a
    frame (data, control).
    Whenever an error is detected, isValid() returns false.

    \note The QWebSocketFrame class does not look at valid sequences of frames.
    It processes frames one at a time.
    \note It is the QWebSocketDataProcessor that takes the sequence into account.

    \sa QWebSocketDataProcessor
    \internal
 */

#include "qwebsocketframe_p.h"
#include "qwebsocketprotocol_p.h"

#include <QtCore/QtEndian>
#include <QtCore/QDebug>

QT_BEGIN_NAMESPACE

/*!
    \internal
 */
QWebSocketFrame::QWebSocketFrame() :
    m_closeCode(QWebSocketProtocol::CloseCodeNormal),
    m_closeReason(),
    m_mask(0),
    m_opCode(QWebSocketProtocol::OpCodeReservedC),
    m_length(0),
    m_payload(),
    m_isFinalFrame(true),
    m_rsv1(false),
    m_rsv2(false),
    m_rsv3(false),
    m_isValid(false)
{
}

/*!
    \internal
 */
QWebSocketFrame::QWebSocketFrame(const QWebSocketFrame &other) :
    m_closeCode(other.m_closeCode),
    m_closeReason(other.m_closeReason),
    m_mask(other.m_mask),
    m_opCode(other.m_opCode),
    m_length(other.m_length),
    m_payload(other.m_payload),
    m_isFinalFrame(other.m_isFinalFrame),
    m_rsv1(other.m_rsv1),
    m_rsv2(other.m_rsv2),
    m_rsv3(other.m_rsv3),
    m_isValid(other.m_isValid)
{
}

/*!
    \internal
 */
QWebSocketFrame &QWebSocketFrame::operator =(const QWebSocketFrame &other)
{
    m_closeCode = other.m_closeCode;
    m_closeReason = other.m_closeReason;
    m_isFinalFrame = other.m_isFinalFrame;
    m_mask = other.m_mask;
    m_rsv1 = other.m_rsv1;
    m_rsv2 = other.m_rsv2;
    m_rsv3 = other.m_rsv3;
    m_opCode = other.m_opCode;
    m_length = other.m_length;
    m_payload = other.m_payload;
    m_isValid = other.m_isValid;

    return *this;
}

#ifdef Q_COMPILER_RVALUE_REFS
/*!
    \internal
 */
QWebSocketFrame::QWebSocketFrame(QWebSocketFrame &&other) :
    m_closeCode(qMove(other.m_closeCode)),
    m_closeReason(qMove(other.m_closeReason)),
    m_mask(qMove(other.m_mask)),
    m_opCode(qMove(other.m_opCode)),
    m_length(qMove(other.m_length)),
    m_payload(qMove(other.m_payload)),
    m_isFinalFrame(qMove(other.m_isFinalFrame)),
    m_rsv1(qMove(other.m_rsv1)),
    m_rsv2(qMove(other.m_rsv2)),
    m_rsv3(qMove(other.m_rsv3)),
    m_isValid(qMove(other.m_isValid))
{}


/*!
    \internal
 */
QWebSocketFrame &QWebSocketFrame::operator =(QWebSocketFrame &&other)
{
    qSwap(m_closeCode, other.m_closeCode);
    qSwap(m_closeReason, other.m_closeReason);
    qSwap(m_isFinalFrame, other.m_isFinalFrame);
    qSwap(m_mask, other.m_mask);
    qSwap(m_rsv1, other.m_rsv1);
    qSwap(m_rsv2, other.m_rsv2);
    qSwap(m_rsv3, other.m_rsv3);
    qSwap(m_opCode, other.m_opCode);
    qSwap(m_length, other.m_length);
    qSwap(m_payload, other.m_payload);
    qSwap(m_isValid, other.m_isValid);

    return *this;
}

#endif

/*!
    \internal
 */
void QWebSocketFrame::swap(QWebSocketFrame &other)
{
    if (&other != this) {
        qSwap(m_closeCode, other.m_closeCode);
        qSwap(m_closeReason, other.m_closeReason);
        qSwap(m_isFinalFrame, other.m_isFinalFrame);
        qSwap(m_mask, other.m_mask);
        qSwap(m_rsv1, other.m_rsv1);
        qSwap(m_rsv2, other.m_rsv2);
        qSwap(m_rsv3, other.m_rsv3);
        qSwap(m_opCode, other.m_opCode);
        qSwap(m_length, other.m_length);
        qSwap(m_payload, other.m_payload);
        qSwap(m_isValid, other.m_isValid);
    }
}

/*!
    \internal
 */
QWebSocketProtocol::CloseCode QWebSocketFrame::closeCode() const
{
    return m_closeCode;
}

/*!
    \internal
 */
QString QWebSocketFrame::closeReason() const
{
    return m_closeReason;
}

/*!
    \internal
 */
bool QWebSocketFrame::isFinalFrame() const
{
    return m_isFinalFrame;
}

/*!
    \internal
 */
bool QWebSocketFrame::isControlFrame() const
{
    return (m_opCode & 0x08) == 0x08;
}

/*!
    \internal
 */
bool QWebSocketFrame::isDataFrame() const
{
    return !isControlFrame();
}

/*!
    \internal
 */
bool QWebSocketFrame::isContinuationFrame() const
{
    return isDataFrame() && (m_opCode == QWebSocketProtocol::OpCodeContinue);
}

/*!
    \internal
 */
bool QWebSocketFrame::hasMask() const
{
    return m_mask != 0;
}

/*!
    \internal
 */
quint32 QWebSocketFrame::mask() const
{
    return m_mask;
}

/*!
    \internal
 */
QWebSocketProtocol::OpCode QWebSocketFrame::opCode() const
{
    return m_opCode;
}

/*!
    \internal
 */
QByteArray QWebSocketFrame::payload() const
{
    return m_payload;
}

/*!
    Resets all member variables, and invalidates the object.

    \internal
 */
void QWebSocketFrame::clear()
{
    m_closeCode = QWebSocketProtocol::CloseCodeNormal;
    m_closeReason.clear();
    m_isFinalFrame = true;
    m_mask = 0;
    m_rsv1 = false;
    m_rsv2 = false;
    m_rsv3 = false;
    m_opCode = QWebSocketProtocol::OpCodeReservedC;
    m_length = 0;
    m_payload.clear();
    m_isValid = false;
}

/*!
    \internal
 */
bool QWebSocketFrame::isValid() const
{
    return m_isValid;
}

#define WAIT_FOR_MORE_DATA(dataSizeInBytes)  \
    { returnState = processingState; \
      processingState = PS_WAIT_FOR_MORE_DATA; dataWaitSize = dataSizeInBytes; }

/*!
    \internal
 */
QWebSocketFrame QWebSocketFrame::readFrame(QIODevice *pIoDevice)
{
    bool isDone = false;
    qint64 bytesRead = 0;
    QWebSocketFrame frame;
    quint64 dataWaitSize = 0;
    Q_UNUSED(dataWaitSize); // value is used in MACRO, Q_UNUSED to avoid compiler warnings
    ProcessingState processingState = PS_READ_HEADER;
    ProcessingState returnState = PS_READ_HEADER;
    bool hasMask = false;
    quint64 payloadLength = 0;

    while (!isDone)
    {
        switch (processingState) {
        case PS_WAIT_FOR_MORE_DATA:
            //TODO: waitForReadyRead should really be changed
            //now, when a WebSocket is used in a GUI thread
            //the GUI will hang for at most 5 seconds
            //maybe, a QStateMachine should be used
            if (!pIoDevice->waitForReadyRead(5000)) {
                frame.setError(QWebSocketProtocol::CloseCodeGoingAway,
                               tr("Timeout when reading data from socket."));
                processingState = PS_DISPATCH_RESULT;
            } else {
                processingState = returnState;
            }
            break;

        case PS_READ_HEADER:
            if (Q_LIKELY(pIoDevice->bytesAvailable() >= 2)) {
                //FIN, RSV1-3, Opcode
                char header[2] = {0};
                bytesRead = pIoDevice->read(header, 2);
                frame.m_isFinalFrame = (header[0] & 0x80) != 0;
                frame.m_rsv1 = (header[0] & 0x40);
                frame.m_rsv2 = (header[0] & 0x20);
                frame.m_rsv3 = (header[0] & 0x10);
                frame.m_opCode = static_cast<QWebSocketProtocol::OpCode>(header[0] & 0x0F);

                //Mask, PayloadLength
                hasMask = (header[1] & 0x80) != 0;
                frame.m_length = (header[1] & 0x7F);

                switch (frame.m_length)
                {
                    case 126:
                    {
                        processingState = PS_READ_PAYLOAD_LENGTH;
                        break;
                    }
                    case 127:
                    {
                        processingState = PS_READ_BIG_PAYLOAD_LENGTH;
                        break;
                    }
                    default:
                    {
                        payloadLength = frame.m_length;
                        processingState = hasMask ? PS_READ_MASK : PS_READ_PAYLOAD;
                        break;
                    }
                }
                if (!frame.checkValidity())
                    processingState = PS_DISPATCH_RESULT;
            } else {
                WAIT_FOR_MORE_DATA(2);
            }
            break;

        case PS_READ_PAYLOAD_LENGTH:
            if (Q_LIKELY(pIoDevice->bytesAvailable() >= 2)) {
                uchar length[2] = {0};
                bytesRead = pIoDevice->read(reinterpret_cast<char *>(length), 2);
                if (Q_UNLIKELY(bytesRead == -1)) {
                    frame.setError(QWebSocketProtocol::CloseCodeGoingAway,
                                   tr("Error occurred while reading from the network: %1")
                                        .arg(pIoDevice->errorString()));
                    processingState = PS_DISPATCH_RESULT;
                } else {
                    payloadLength = qFromBigEndian<quint16>(reinterpret_cast<const uchar *>(length));
                    if (Q_UNLIKELY(payloadLength < 126)) {
                        //see http://tools.ietf.org/html/rfc6455#page-28 paragraph 5.2
                        //"in all cases, the minimal number of bytes MUST be used to encode
                        //the length, for example, the length of a 124-byte-long string
                        //can't be encoded as the sequence 126, 0, 124"
                        frame.setError(QWebSocketProtocol::CloseCodeProtocolError,
                                       tr("Lengths smaller than 126 " \
                                                   "must be expressed as one byte."));
                        processingState = PS_DISPATCH_RESULT;
                    } else {
                        processingState = hasMask ? PS_READ_MASK : PS_READ_PAYLOAD;
                    }
                }
            } else {
                WAIT_FOR_MORE_DATA(2);
            }
            break;

        case PS_READ_BIG_PAYLOAD_LENGTH:
            if (Q_LIKELY(pIoDevice->bytesAvailable() >= 8)) {
                uchar length[8] = {0};
                bytesRead = pIoDevice->read(reinterpret_cast<char *>(length), 8);
                if (Q_UNLIKELY(bytesRead < 8)) {
                    frame.setError(QWebSocketProtocol::CloseCodeAbnormalDisconnection,
                                   tr("Something went wrong during "\
                                               "reading from the network."));
                    processingState = PS_DISPATCH_RESULT;
                } else {
                    //Most significant bit must be set to 0 as
                    //per http://tools.ietf.org/html/rfc6455#section-5.2
                    payloadLength = qFromBigEndian<quint64>(length);
                    if (Q_UNLIKELY(payloadLength & (quint64(1) << 63))) {
                        frame.setError(QWebSocketProtocol::CloseCodeProtocolError,
                                       tr("Highest bit of payload length is not 0."));
                        processingState = PS_DISPATCH_RESULT;
                    } else if (Q_UNLIKELY(payloadLength <= 0xFFFFu)) {
                        //see http://tools.ietf.org/html/rfc6455#page-28 paragraph 5.2
                        //"in all cases, the minimal number of bytes MUST be used to encode
                        //the length, for example, the length of a 124-byte-long string
                        //can't be encoded as the sequence 126, 0, 124"
                        frame.setError(QWebSocketProtocol::CloseCodeProtocolError,
                                       tr("Lengths smaller than 65536 (2^16) " \
                                                   "must be expressed as 2 bytes."));
                        processingState = PS_DISPATCH_RESULT;
                    } else {
                        processingState = hasMask ? PS_READ_MASK : PS_READ_PAYLOAD;
                    }
                }
            } else {
                WAIT_FOR_MORE_DATA(8);
            }

            break;

        case PS_READ_MASK:
            if (Q_LIKELY(pIoDevice->bytesAvailable() >= 4)) {
                bytesRead = pIoDevice->read(reinterpret_cast<char *>(&frame.m_mask),
                                            sizeof(frame.m_mask));
                if (bytesRead == -1) {
                    frame.setError(QWebSocketProtocol::CloseCodeGoingAway,
                                   tr("Error while reading from the network: %1.")
                                        .arg(pIoDevice->errorString()));
                    processingState = PS_DISPATCH_RESULT;
                } else {
                    frame.m_mask = qFromBigEndian(frame.m_mask);
                    processingState = PS_READ_PAYLOAD;
                }
            } else {
                WAIT_FOR_MORE_DATA(4);
            }
            break;

        case PS_READ_PAYLOAD:
            if (!payloadLength) {
                processingState = PS_DISPATCH_RESULT;
            } else if (Q_UNLIKELY(payloadLength > MAX_FRAME_SIZE_IN_BYTES)) {
                frame.setError(QWebSocketProtocol::CloseCodeTooMuchData,
                               tr("Maximum framesize exceeded."));
                processingState = PS_DISPATCH_RESULT;
            } else {
                quint64 bytesAvailable = quint64(pIoDevice->bytesAvailable());
                if (bytesAvailable >= payloadLength) {
                    frame.m_payload = pIoDevice->read(payloadLength);
                    //payloadLength can be safely cast to an integer,
                    //because MAX_FRAME_SIZE_IN_BYTES = MAX_INT
                    if (Q_UNLIKELY(frame.m_payload.length() != int(payloadLength))) {
                        //some error occurred; refer to the Qt documentation of QIODevice::read()
                        frame.setError(QWebSocketProtocol::CloseCodeAbnormalDisconnection,
                                       tr("Some serious error occurred " \
                                                   "while reading from the network."));
                        processingState = PS_DISPATCH_RESULT;
                    } else {
                        if (hasMask)
                            QWebSocketProtocol::mask(&frame.m_payload, frame.m_mask);
                        processingState = PS_DISPATCH_RESULT;
                    }
                } else {
                    //if payload is too big, then this will timeout
                    WAIT_FOR_MORE_DATA(payloadLength);
                }
            }
            break;

        case PS_DISPATCH_RESULT:
            processingState = PS_READ_HEADER;
            isDone = true;
            break;

        default:
            //should not come here
            qWarning() << "DataProcessor::process: Found invalid state. This should not happen!";
            frame.clear();
            isDone = true;
            break;
        }	//end switch
    }

    return frame;
}

/*!
    \internal
 */
void QWebSocketFrame::setError(QWebSocketProtocol::CloseCode code, const QString &closeReason)
{
    clear();
    m_closeCode = code;
    m_closeReason = closeReason;
    m_isValid = false;
}

/*!
    \internal
 */
bool QWebSocketFrame::checkValidity()
{
    if (Q_UNLIKELY(m_rsv1 || m_rsv2 || m_rsv3)) {
        setError(QWebSocketProtocol::CloseCodeProtocolError, tr("Rsv field is non-zero"));
    } else if (Q_UNLIKELY(QWebSocketProtocol::isOpCodeReserved(m_opCode))) {
        setError(QWebSocketProtocol::CloseCodeProtocolError, tr("Used reserved opcode"));
    } else if (isControlFrame()) {
        if (Q_UNLIKELY(m_length > 125)) {
            setError(QWebSocketProtocol::CloseCodeProtocolError,
                     tr("Control frame is larger than 125 bytes"));
        } else if (Q_UNLIKELY(!m_isFinalFrame)) {
            setError(QWebSocketProtocol::CloseCodeProtocolError,
                     tr("Control frames cannot be fragmented"));
        } else {
            m_isValid = true;
        }
    } else {
        m_isValid = true;
    }
    return m_isValid;
}

QT_END_NAMESPACE