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**
** Copyright (C) 2016 The Qt Company Ltd.
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** This file is part of the QtNetwork module of the Qt Toolkit.
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** General Public License version 3 as published by the Free Software
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** ensure the GNU Lesser General Public License version 3 requirements
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** 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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****************************************************************************/

#include <QtCore/qbytearray.h>
#include <QtCore/qstring.h>

#include "private/qhttpnetworkrequest_p.h"
#include "http2protocol_p.h"
#include "http2frames_p.h"

QT_BEGIN_NAMESPACE

Q_LOGGING_CATEGORY(QT_HTTP2, "qt.network.http2")

namespace Http2
{

// 3.5 HTTP/2 Connection Preface:
// "That is, the connection preface starts with the string
// PRI * HTTP/2.0\r\n\r\nSM\r\n\r\n)."
const char Http2clientPreface[clientPrefaceLength] =
    {0x50, 0x52, 0x49, 0x20, 0x2a, 0x20,
     0x48, 0x54, 0x54, 0x50, 0x2f, 0x32,
     0x2e, 0x30, 0x0d, 0x0a, 0x0d, 0x0a,
     0x53, 0x4d, 0x0d, 0x0a, 0x0d, 0x0a};

QByteArray qt_default_SETTINGS_to_Base64()
{
    FrameWriter frame(qt_default_SETTINGS_frame());
    // SETTINGS frame's payload consists of pairs:
    // 2-byte-identifier | 4-byte-value - multiple of 6.
    // Also it's allowed to be empty.
    Q_ASSERT(!(frame.payloadSize() % 6));
    const char *src = reinterpret_cast<const char *>(&frame.rawFrameBuffer()[frameHeaderSize]);
    const QByteArray wrapper(QByteArray::fromRawData(src, int(frame.payloadSize())));
    // 3.2.1
    // The content of the HTTP2-Settings header field is the payload
    // of a SETTINGS frame (Section 6.5), encoded as a base64url string
    // (that is, the URL- and filename-safe Base64 encoding described in
    // Section 5 of [RFC4648], with any trailing '=' characters omitted).
    return wrapper.toBase64(QByteArray::Base64UrlEncoding | QByteArray::OmitTrailingEquals);
}

void qt_add_ProtocolUpgradeRequest(QHttpNetworkRequest &request)
{
    // RFC 2616, 14.10
    QByteArray value(request.headerField("Connection"));
    if (value.size())
        value += ", ";

    value += "Upgrade, HTTP2-Settings";
    request.setHeaderField("Connection", value);
    // This we just (re)write.
    request.setHeaderField("Upgrade", "h2c");
    // This we just (re)write.
    request.setHeaderField("HTTP2-Settings", qt_default_SETTINGS_to_Base64());
}

void qt_error(quint32 errorCode, QNetworkReply::NetworkError &error,
              QString &errorMessage)
{
    if (errorCode > quint32(HTTP_1_1_REQUIRED)) {
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("RST_STREAM with unknown error code (%1)");
        errorMessage = errorMessage.arg(errorCode);
        return;
    }

    const Http2Error http2Error = Http2Error(errorCode);

    switch (http2Error) {
    case HTTP2_NO_ERROR:
        error = QNetworkReply::NoError;
        errorMessage.clear();
        break;
    case PROTOCOL_ERROR:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("HTTP/2 protocol error");
        break;
    case INTERNAL_ERROR:
        error = QNetworkReply::InternalServerError;
        errorMessage = QLatin1String("Internal server error");
        break;
    case FLOW_CONTROL_ERROR:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Flow control error");
        break;
    case SETTINGS_TIMEOUT:
        error = QNetworkReply::TimeoutError;
        errorMessage = QLatin1String("SETTINGS ACK timeout error");
        break;
    case STREAM_CLOSED:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Server received frame(s) on a half-closed stream");
        break;
    case FRAME_SIZE_ERROR:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Server received a frame with an invalid size");
        break;
    case REFUSE_STREAM:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Server refused a stream");
        break;
    case CANCEL:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Stream is no longer needed");
        break;
    case COMPRESSION_ERROR:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Server is unable to maintain the "
                                     "header compression context for the connection");
        break;
    case CONNECT_ERROR:
        // TODO: in Qt6 we'll have to add more error codes in QNetworkReply.
        error = QNetworkReply::UnknownNetworkError;
        errorMessage = QLatin1String("The connection established in response "
                        "to a CONNECT request was reset or abnormally closed");
        break;
    case ENHANCE_YOUR_CALM:
        error = QNetworkReply::UnknownServerError;
        errorMessage = QLatin1String("Server dislikes our behavior, excessive load detected.");
        break;
    case INADEQUATE_SECURITY:
        error = QNetworkReply::ContentAccessDenied;
        errorMessage = QLatin1String("The underlying transport has properties "
                                     "that do not meet minimum security "
                                     "requirements");
        break;
    case HTTP_1_1_REQUIRED:
        error = QNetworkReply::ProtocolFailure;
        errorMessage = QLatin1String("Server requires that HTTP/1.1 "
                                     "be used instead of HTTP/2.");
    }
}

QString qt_error_string(quint32 errorCode)
{
    QNetworkReply::NetworkError error = QNetworkReply::NoError;
    QString message;
    qt_error(errorCode, error, message);
    return message;
}

QNetworkReply::NetworkError qt_error(quint32 errorCode)
{
    QNetworkReply::NetworkError error = QNetworkReply::NoError;
    QString message;
    qt_error(errorCode, error, message);
    return error;
}

FrameWriter qt_default_SETTINGS_frame()
{
    // 6.5 SETTINGS
    FrameWriter frame(FrameType::SETTINGS, FrameFlag::EMPTY, connectionStreamID);
    // MAX frame size (16 kb), disable PUSH
    frame.append(Settings::MAX_FRAME_SIZE_ID);
    frame.append(quint32(maxFrameSize));
    frame.append(Settings::ENABLE_PUSH_ID);
    frame.append(quint32(0));

    return frame;
}

}

QT_END_NAMESPACE