/****************************************************************************
**
** Copyright (C) 2017 The Qt Company Ltd.
** Copyright (C) 2016 Javier S. Pedro <maemo@javispedro.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtBluetooth module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:LGPL$
** Commercial License Usage
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** accordance with the commercial license agreement provided with the
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** a written agreement between you and The Qt Company. For licensing terms
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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
** Public license version 3 or any later version approved by the KDE Free
** Qt Foundation. The licenses are as published by the Free Software
** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
** included in the packaging of this file. Please review the following
** information to ensure the GNU General Public License requirements will
** be met: https://www.gnu.org/licenses/gpl-2.0.html and
** https://www.gnu.org/licenses/gpl-3.0.html.
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** $QT_END_LICENSE$
**
****************************************************************************/

#include "lecmaccalculator_p.h"
#include "qlowenergycontroller_p.h"
#include "qbluetoothsocket_p.h"
#include "qleadvertiser_p.h"
#include "bluez/bluez_data_p.h"
#include "bluez/hcimanager_p.h"
#include "bluez/remotedevicemanager_p.h"
#include "bluez/bluez5_helper_p.h"
#include "bluez/bluetoothmanagement_p.h"

#include <QtCore/QFileInfo>
#include <QtCore/QLoggingCategory>
#include <QtCore/QSettings>
#include <QtCore/QTimer>
#include <QtBluetooth/QBluetoothLocalDevice>
#include <QtBluetooth/QBluetoothSocket>
#include <QtBluetooth/QLowEnergyCharacteristicData>
#include <QtBluetooth/QLowEnergyDescriptorData>
#include <QtBluetooth/QLowEnergyService>
#include <QtBluetooth/QLowEnergyServiceData>

#include <algorithm>
#include <climits>
#include <cstring>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#define ATT_DEFAULT_LE_MTU 23
#define ATT_MAX_LE_MTU 0x200

#define GATT_PRIMARY_SERVICE    quint16(0x2800)
#define GATT_SECONDARY_SERVICE  quint16(0x2801)
#define GATT_INCLUDED_SERVICE   quint16(0x2802)
#define GATT_CHARACTERISTIC     quint16(0x2803)

// GATT commands
#define ATT_OP_ERROR_RESPONSE           0x1
#define ATT_OP_EXCHANGE_MTU_REQUEST     0x2 //send own mtu
#define ATT_OP_EXCHANGE_MTU_RESPONSE    0x3 //receive server MTU
#define ATT_OP_FIND_INFORMATION_REQUEST 0x4 //discover individual attribute info
#define ATT_OP_FIND_INFORMATION_RESPONSE 0x5
#define ATT_OP_FIND_BY_TYPE_VALUE_REQUEST 0x6
#define ATT_OP_FIND_BY_TYPE_VALUE_RESPONSE 0x7
#define ATT_OP_READ_BY_TYPE_REQUEST     0x8 //discover characteristics
#define ATT_OP_READ_BY_TYPE_RESPONSE    0x9
#define ATT_OP_READ_REQUEST             0xA //read characteristic & descriptor values
#define ATT_OP_READ_RESPONSE            0xB
#define ATT_OP_READ_BLOB_REQUEST        0xC //read values longer than MTU-1
#define ATT_OP_READ_BLOB_RESPONSE       0xD
#define ATT_OP_READ_MULTIPLE_REQUEST    0xE
#define ATT_OP_READ_MULTIPLE_RESPONSE   0xF
#define ATT_OP_READ_BY_GROUP_REQUEST    0x10 //discover services
#define ATT_OP_READ_BY_GROUP_RESPONSE   0x11
#define ATT_OP_WRITE_REQUEST            0x12 //write characteristic with response
#define ATT_OP_WRITE_RESPONSE           0x13
#define ATT_OP_PREPARE_WRITE_REQUEST    0x16 //write values longer than MTU-3 -> queueing
#define ATT_OP_PREPARE_WRITE_RESPONSE   0x17
#define ATT_OP_EXECUTE_WRITE_REQUEST    0x18 //write values longer than MTU-3 -> execute queue
#define ATT_OP_EXECUTE_WRITE_RESPONSE   0x19
#define ATT_OP_HANDLE_VAL_NOTIFICATION  0x1b //informs about value change
#define ATT_OP_HANDLE_VAL_INDICATION    0x1d //informs about value change -> requires reply
#define ATT_OP_HANDLE_VAL_CONFIRMATION  0x1e //answer for ATT_OP_HANDLE_VAL_INDICATION
#define ATT_OP_WRITE_COMMAND            0x52 //write characteristic without response
#define ATT_OP_SIGNED_WRITE_COMMAND     0xD2

//GATT command sizes in bytes
#define ERROR_RESPONSE_HEADER_SIZE 5
#define FIND_INFO_REQUEST_HEADER_SIZE 5
#define GRP_TYPE_REQ_HEADER_SIZE 7
#define READ_BY_TYPE_REQ_HEADER_SIZE 7
#define READ_REQUEST_HEADER_SIZE 3
#define READ_BLOB_REQUEST_HEADER_SIZE 5
#define WRITE_REQUEST_HEADER_SIZE 3    // same size for WRITE_COMMAND header
#define PREPARE_WRITE_HEADER_SIZE 5
#define EXECUTE_WRITE_HEADER_SIZE 2
#define MTU_EXCHANGE_HEADER_SIZE 3

// GATT error codes
#define ATT_ERROR_INVALID_HANDLE        0x01
#define ATT_ERROR_READ_NOT_PERM         0x02
#define ATT_ERROR_WRITE_NOT_PERM        0x03
#define ATT_ERROR_INVALID_PDU           0x04
#define ATT_ERROR_INSUF_AUTHENTICATION  0x05
#define ATT_ERROR_REQUEST_NOT_SUPPORTED 0x06
#define ATT_ERROR_INVALID_OFFSET        0x07
#define ATT_ERROR_INSUF_AUTHORIZATION   0x08
#define ATT_ERROR_PREPARE_QUEUE_FULL    0x09
#define ATT_ERROR_ATTRIBUTE_NOT_FOUND   0x0A
#define ATT_ERROR_ATTRIBUTE_NOT_LONG    0x0B
#define ATT_ERROR_INSUF_ENCR_KEY_SIZE   0x0C
#define ATT_ERROR_INVAL_ATTR_VALUE_LEN  0x0D
#define ATT_ERROR_UNLIKELY              0x0E
#define ATT_ERROR_INSUF_ENCRYPTION      0x0F
#define ATT_ERROR_UNSUPPRTED_GROUP_TYPE 0x10
#define ATT_ERROR_INSUF_RESOURCES       0x11
#define ATT_ERROR_APPLICATION_START     0x80
//------------------------------------------
// The error codes in this block are
// implementation specific errors

#define ATT_ERROR_REQUEST_STALLED       0x81

//------------------------------------------
#define ATT_ERROR_APPLICATION_END       0x9f

#define APPEND_VALUE true
#define NEW_VALUE false

QT_BEGIN_NAMESPACE

Q_DECLARE_LOGGING_CATEGORY(QT_BT_BLUEZ)

using namespace QBluetooth;

const int maxPrepareQueueSize = 1024;

static inline QBluetoothUuid convert_uuid128(const quint128 *p)
{
    quint128 dst_hostOrder, dst_bigEndian;

    // Bluetooth LE data comes as little endian
    // uuids are constructed using high endian
    btoh128(p, &dst_hostOrder);
    hton128(&dst_hostOrder, &dst_bigEndian);

    // convert to Qt's own data type
    quint128 qtdst;
    memcpy(&qtdst, &dst_bigEndian, sizeof(quint128));

    return QBluetoothUuid(qtdst);
}

static void dumpErrorInformation(const QByteArray &response)
{
    const char *data = response.constData();
    if (response.size() != 5 || data[0] != ATT_OP_ERROR_RESPONSE) {
        qCWarning(QT_BT_BLUEZ) << QLatin1String("Not a valid error response");
        return;
    }

    quint8 lastCommand = data[1];
    quint16 handle = bt_get_le16(&data[2]);
    quint8 errorCode = data[4];

    QString errorString;
    switch (errorCode) {
    case ATT_ERROR_INVALID_HANDLE:
        errorString = QStringLiteral("invalid handle"); break;
    case ATT_ERROR_READ_NOT_PERM:
        errorString = QStringLiteral("not readable attribute - permissions"); break;
    case ATT_ERROR_WRITE_NOT_PERM:
        errorString = QStringLiteral("not writable attribute - permissions"); break;
    case ATT_ERROR_INVALID_PDU:
        errorString = QStringLiteral("PDU invalid"); break;
    case ATT_ERROR_INSUF_AUTHENTICATION:
        errorString = QStringLiteral("needs authentication - permissions"); break;
    case ATT_ERROR_REQUEST_NOT_SUPPORTED:
        errorString = QStringLiteral("server does not support request"); break;
    case ATT_ERROR_INVALID_OFFSET:
        errorString = QStringLiteral("offset past end of attribute"); break;
    case ATT_ERROR_INSUF_AUTHORIZATION:
        errorString = QStringLiteral("need authorization - permissions"); break;
    case ATT_ERROR_PREPARE_QUEUE_FULL:
        errorString = QStringLiteral("run out of prepare queue space"); break;
    case ATT_ERROR_ATTRIBUTE_NOT_FOUND:
        errorString = QStringLiteral("no attribute in given range found"); break;
    case ATT_ERROR_ATTRIBUTE_NOT_LONG:
        errorString = QStringLiteral("attribute not read/written using read blob"); break;
    case ATT_ERROR_INSUF_ENCR_KEY_SIZE:
        errorString = QStringLiteral("need encryption key size - permissions"); break;
    case ATT_ERROR_INVAL_ATTR_VALUE_LEN:
        errorString = QStringLiteral("written value is invalid size"); break;
    case ATT_ERROR_UNLIKELY:
        errorString = QStringLiteral("unlikely error"); break;
    case ATT_ERROR_INSUF_ENCRYPTION:
        errorString = QStringLiteral("needs encryption - permissions"); break;
    case ATT_ERROR_UNSUPPRTED_GROUP_TYPE:
        errorString = QStringLiteral("unsupported group type"); break;
    case ATT_ERROR_INSUF_RESOURCES:
        errorString = QStringLiteral("insufficient resources to complete request"); break;
    default:
        if (errorCode >= ATT_ERROR_APPLICATION_START && errorCode <= ATT_ERROR_APPLICATION_END)
            errorString = QStringLiteral("application error: %1").arg(errorCode);
        else
            errorString = QStringLiteral("unknown error code");
        break;
    }

    qCDebug(QT_BT_BLUEZ) << "Error1:" << errorString
             << "last command:" << hex << lastCommand
             << "handle:" << handle;
}

static int getUuidSize(const QBluetoothUuid &uuid)
{
    return uuid.minimumSize() == 2 ? 2 : 16;
}

template<typename T> static void putDataAndIncrement(const T &src, char *&dst)
{
    putBtData(src, dst);
    dst += sizeof(T);
}
template<> void putDataAndIncrement(const QBluetoothUuid &uuid, char *&dst)
{
    const int uuidSize = getUuidSize(uuid);
    if (uuidSize == 2) {
        putBtData(uuid.toUInt16(), dst);
    } else {
        quint128 hostOrder;
        quint128 qtUuidOrder = uuid.toUInt128();
        ntoh128(&qtUuidOrder, &hostOrder);
        putBtData(hostOrder, dst);
    }
    dst += uuidSize;
}
template<> void putDataAndIncrement(const QByteArray &value, char *&dst)
{
    using namespace std;
    memcpy(dst, value.constData(), value.count());
    dst += value.count();
}

QLowEnergyControllerPrivate::QLowEnergyControllerPrivate()
    : QObject(),
      state(QLowEnergyController::UnconnectedState),
      error(QLowEnergyController::NoError),
      lastLocalHandle(0),
      l2cpSocket(0), requestPending(false),
      mtuSize(ATT_DEFAULT_LE_MTU),
      securityLevelValue(-1),
      encryptionChangePending(false),
      hciManager(0),
      advertiser(0),
      serverSocketNotifier(0)
{
    registerQLowEnergyControllerMetaType();
    qRegisterMetaType<QList<QLowEnergyHandle> >();
}

void QLowEnergyControllerPrivate::init()
{
    hciManager = new HciManager(localAdapter, this);
    if (!hciManager->isValid())
        return;

    hciManager->monitorEvent(HciManager::EncryptChangeEvent);
    connect(hciManager, SIGNAL(encryptionChangedEvent(QBluetoothAddress,bool)),
            this, SLOT(encryptionChangedEvent(QBluetoothAddress,bool)));
    hciManager->monitorEvent(HciManager::LeMetaEvent);
    hciManager->monitorAclPackets();
    connect(hciManager, &HciManager::connectionComplete, [this](quint16 handle) {
        connectionHandle = handle;
        qCDebug(QT_BT_BLUEZ) << "received connection complete event, handle:" << handle;
    });
    connect(hciManager, &HciManager::connectionUpdate,
            [this](quint16 handle, const QLowEnergyConnectionParameters &params) {
                if (handle == connectionHandle)
                    emit q_ptr->connectionUpdated(params);
            }
    );
    connect(hciManager, &HciManager::signatureResolvingKeyReceived,
            [this](quint16 handle, bool remoteKey, const quint128 &csrk) {
                if (handle != connectionHandle)
                    return;
                if ((remoteKey && role == QLowEnergyController::CentralRole)
                        || (!remoteKey && role == QLowEnergyController::PeripheralRole)) {
                    return;
                }
                qCDebug(QT_BT_BLUEZ) << "received new signature resolving key"
                                     << QByteArray(reinterpret_cast<const char *>(csrk.data),
                                                   sizeof csrk).toHex();
                signingData.insert(remoteDevice.toUInt64(), SigningData(csrk));
        }
    );

    if (role == QLowEnergyController::CentralRole) {
        if (Q_UNLIKELY(!qEnvironmentVariableIsEmpty("BLUETOOTH_GATT_TIMEOUT"))) {
            bool ok = false;
            int value = qEnvironmentVariableIntValue("BLUETOOTH_GATT_TIMEOUT", &ok);
            if (ok)
                gattRequestTimeout = value;
        }

        // permit disabling of timeout behavior via environment variable
        if (gattRequestTimeout > 0) {
            qCWarning(QT_BT_BLUEZ) << "Enabling GATT request timeout behavior" << gattRequestTimeout;
            requestTimer = new QTimer(this);
            requestTimer->setSingleShot(true);
            requestTimer->setInterval(gattRequestTimeout);
            connect(requestTimer, &QTimer::timeout,
                    this, &QLowEnergyControllerPrivate::handleGattRequestTimeout);
        }
    }
}

void QLowEnergyControllerPrivate::handleGattRequestTimeout()
{
    // antyhing open that might require cancellation or a warning?
    if (encryptionChangePending) {
        // We cannot really recover for now but the warning is essential for debugging
        qCWarning(QT_BT_BLUEZ) << "****** Encryption change event blocking further GATT requests";
        return;
    }

    if (!openRequests.isEmpty() && requestPending) {
        requestPending = false; // reset pending flag
        const Request currentRequest = openRequests.dequeue();

        qCWarning(QT_BT_BLUEZ).nospace() << "****** Request type 0x" << hex << currentRequest.command
                           << " to server/peripheral timed out";
        qCWarning(QT_BT_BLUEZ) << "****** Looks like the characteristic or descriptor does NOT act in"
                               <<  "accordance to Bluetooth 4.x spec.";
        qCWarning(QT_BT_BLUEZ) << "****** Please check server implementation."
                               << "Continuing under reservation.";

        quint8 command = currentRequest.command;
        const auto createRequestErrorMessage = [](quint8 opcodeWithError,
                                           QLowEnergyHandle handle) {
            QByteArray errorPackage(ERROR_RESPONSE_HEADER_SIZE, Qt::Uninitialized);
            errorPackage[0] = ATT_OP_ERROR_RESPONSE;
            errorPackage[1] = opcodeWithError; // e.g. ATT_OP_READ_REQUEST
            putBtData(handle, errorPackage.data() + 2); //
            errorPackage[4] = ATT_ERROR_REQUEST_STALLED;

            return errorPackage;
        };

        switch (command) {
        case ATT_OP_EXCHANGE_MTU_REQUEST:  // MTU change request
            // never received reply to MTU request
            // it is safe to skip and go to next request
            sendNextPendingRequest();
            break;
        case ATT_OP_READ_BY_GROUP_REQUEST: // primary or secondary service discovery
        case ATT_OP_READ_BY_TYPE_REQUEST:  // characteristic or included service discovery
            // jump back into usual response handling with custom error code
            // 2nd param "0" as required by spec
            processReply(currentRequest, createRequestErrorMessage(command, 0));
            break;
        case ATT_OP_READ_REQUEST:          // read descriptor or characteristic value
        case ATT_OP_READ_BLOB_REQUEST:     // read long descriptor or characteristic
        case ATT_OP_WRITE_REQUEST:         // write descriptor or characteristic
        {
            uint handleData = currentRequest.reference.toUInt();
            const QLowEnergyHandle charHandle = (handleData & 0xffff);
            const QLowEnergyHandle descriptorHandle = ((handleData >> 16) & 0xffff);
            processReply(currentRequest, createRequestErrorMessage(command,
                                descriptorHandle ? descriptorHandle : charHandle));
        }
            break;
        case ATT_OP_FIND_INFORMATION_REQUEST: // get descriptor information
            processReply(currentRequest, createRequestErrorMessage(
                                            command, currentRequest.reference2.toUInt()));
            break;
        case ATT_OP_PREPARE_WRITE_REQUEST: // prepare to write long desc or char
        case ATT_OP_EXECUTE_WRITE_REQUEST: // execute long write of desc or char
        {
            uint handleData = currentRequest.reference.toUInt();
            const QLowEnergyHandle attrHandle = (handleData & 0xffff);
            processReply(currentRequest,
                         createRequestErrorMessage(command, attrHandle));
        }
            break;
        default:
            // not a command used by central role implementation
            return;
        }
    }
}

QLowEnergyControllerPrivate::~QLowEnergyControllerPrivate()
{
    closeServerSocket();
    delete cmacCalculator;
}

class ServerSocket
{
public:
    bool listen(const QBluetoothAddress &localAdapter)
    {
        m_socket = ::socket(AF_BLUETOOTH, SOCK_SEQPACKET, BTPROTO_L2CAP);
        if (m_socket == -1) {
            qCWarning(QT_BT_BLUEZ) << "socket creation failed:" << qt_error_string(errno);
            return false;
        }
        sockaddr_l2 addr;

        // memset should be in std namespace for C++ compilers, but we also need to support
        // broken ones that put it in the global one.
        using namespace std;
        memset(&addr, 0, sizeof addr);

        addr.l2_family = AF_BLUETOOTH;
        addr.l2_cid = htobs(ATTRIBUTE_CHANNEL_ID);
        addr.l2_bdaddr_type = BDADDR_LE_PUBLIC;
        convertAddress(localAdapter.toUInt64(), addr.l2_bdaddr.b);
        if (::bind(m_socket, reinterpret_cast<sockaddr *>(&addr), sizeof addr) == -1) {
            qCWarning(QT_BT_BLUEZ) << "bind() failed:" << qt_error_string(errno);
            return false;
        }
        if (::listen(m_socket, 1)) {
            qCWarning(QT_BT_BLUEZ) << "listen() failed:" << qt_error_string(errno);
            return false;
        }
        return true;
    }

    ~ServerSocket()
    {
        if (m_socket != -1)
            close(m_socket);
    }

    int takeSocket()
    {
        const int socket = m_socket;
        m_socket = -1;
        return socket;
    }

private:
    int m_socket = -1;
};


void QLowEnergyControllerPrivate::startAdvertising(const QLowEnergyAdvertisingParameters &params,
        const QLowEnergyAdvertisingData &advertisingData,
        const QLowEnergyAdvertisingData &scanResponseData)
{
    qCDebug(QT_BT_BLUEZ) << "Starting to advertise";
    if (!advertiser) {
        advertiser = new QLeAdvertiserBluez(params, advertisingData, scanResponseData, *hciManager,
                                            this);
        connect(advertiser, &QLeAdvertiser::errorOccurred, this,
                &QLowEnergyControllerPrivate::handleAdvertisingError);
    }
    setState(QLowEnergyController::AdvertisingState);
    advertiser->startAdvertising();
    if (params.mode() == QLowEnergyAdvertisingParameters::AdvNonConnInd
            || params.mode() == QLowEnergyAdvertisingParameters::AdvScanInd) {
        qCDebug(QT_BT_BLUEZ) << "Non-connectable advertising requested, "
                                "not listening for connections.";
        return;
    }

    ServerSocket serverSocket;
    if (!serverSocket.listen(localAdapter)) {
        setError(QLowEnergyController::AdvertisingError);
        setState(QLowEnergyController::UnconnectedState);
        return;
    }

    const int socketFd = serverSocket.takeSocket();
    serverSocketNotifier = new QSocketNotifier(socketFd, QSocketNotifier::Read, this);
    connect(serverSocketNotifier, &QSocketNotifier::activated, this,
            &QLowEnergyControllerPrivate::handleConnectionRequest);
}

void QLowEnergyControllerPrivate::stopAdvertising()
{
    setState(QLowEnergyController::UnconnectedState);
    advertiser->stopAdvertising();
}

void QLowEnergyControllerPrivate::requestConnectionUpdate(const QLowEnergyConnectionParameters &params)
{
    // The spec says that the connection update command can be used by both slave and master
    // devices, but BlueZ allows it only for master devices. So for slave devices, we have to use a
    // connection parameter update request, which we need to wrap in an ACL command, as BlueZ
    // does not allow user-space sockets for the signaling channel.
    if (role == QLowEnergyController::CentralRole)
        hciManager->sendConnectionUpdateCommand(connectionHandle, params);
    else
        hciManager->sendConnectionParameterUpdateRequest(connectionHandle, params);
}

void QLowEnergyControllerPrivate::connectToDevice()
{
    if (remoteDevice.isNull()) {
        qCWarning(QT_BT_BLUEZ) << "Invalid/null remote device address";
        setError(QLowEnergyController::UnknownRemoteDeviceError);
        return;
    }

    setState(QLowEnergyController::ConnectingState);
    if (l2cpSocket)
        delete l2cpSocket;

    // check for active running connections
    // BlueZ 5.37+ (maybe even earlier versions) can have pending BTLE connections
    // Only one active L2CP socket to CID 0x4 possible at a time
    // this check is not performed for BlueZ 4 based platforms as bluetoothd
    // does not support BTLE management

    if (!isBluez5()) {
        establishL2cpClientSocket();
        return;
    }

    QVector<quint16> activeHandles = hciManager->activeLowEnergyConnections();
    if (!activeHandles.isEmpty()) {
        qCWarning(QT_BT_BLUEZ) << "Cannot connect due to pending active LE connections";

        if (!device1Manager) {
            device1Manager = new RemoteDeviceManager(localAdapter, this);
            connect(device1Manager, &RemoteDeviceManager::finished,
                    this, &QLowEnergyControllerPrivate::activeConnectionTerminationDone);
        }

        QVector<QBluetoothAddress> connectedAddresses;
        for (const auto handle: activeHandles) {
            const QBluetoothAddress addr = hciManager->addressForConnectionHandle(handle);
            if (!addr.isNull())
                connectedAddresses.push_back(addr);
        }
        device1Manager->scheduleJob(RemoteDeviceManager::JobType::JobDisconnectDevice, connectedAddresses);
    } else {
        establishL2cpClientSocket();
    }
}

/*!
 * Handles outcome of attempts to close external connections.
 */
void QLowEnergyControllerPrivate::activeConnectionTerminationDone()
{
    if (!device1Manager)
        return;

    qCDebug(QT_BT_BLUEZ) << "RemoteDeviceManager finished attempting"
                         << "to close external connections";

    QVector<quint16> activeHandles = hciManager->activeLowEnergyConnections();
    if (!activeHandles.isEmpty()) {
        qCWarning(QT_BT_BLUEZ) << "Cannot close pending external BTLE connections. Aborting connect attempt";
        setError(QLowEnergyController::ConnectionError);
        setState(QLowEnergyController::UnconnectedState);
        return;
    } else {
        establishL2cpClientSocket();
    }
}

/*!
 * Establishes the L2CP client socket.
 */
void QLowEnergyControllerPrivate::establishL2cpClientSocket()
{
    //we are already in Connecting state

    l2cpSocket = new QBluetoothSocket(QBluetoothServiceInfo::L2capProtocol, this);
    connect(l2cpSocket, SIGNAL(connected()), this, SLOT(l2cpConnected()));
    connect(l2cpSocket, SIGNAL(disconnected()), this, SLOT(l2cpDisconnected()));
    connect(l2cpSocket, SIGNAL(error(QBluetoothSocket::SocketError)),
            this, SLOT(l2cpErrorChanged(QBluetoothSocket::SocketError)));
    connect(l2cpSocket, SIGNAL(readyRead()), this, SLOT(l2cpReadyRead()));

    quint32 addressTypeToUse = (addressType == QLowEnergyController::PublicAddress)
                                    ? BDADDR_LE_PUBLIC : BDADDR_LE_RANDOM;
    if (BluetoothManagement::instance()->isMonitoringEnabled()) {
        // if monitoring is possible and it's private then we force it to the relevant option
        if (BluetoothManagement::instance()->isAddressRandom(remoteDevice)) {
            addressTypeToUse = BDADDR_LE_RANDOM;
        }
    }

    qCDebug(QT_BT_BLUEZ) << "addresstypeToUse:"
                         << (addressTypeToUse == BDADDR_LE_RANDOM
                                 ? QStringLiteral("Random") : QStringLiteral("Public"));

    l2cpSocket->d_ptr->lowEnergySocketType = addressTypeToUse;

    int sockfd = l2cpSocket->socketDescriptor();
    if (sockfd < 0) {
        qCWarning(QT_BT_BLUEZ) << "l2cp socket not initialised";
        setError(QLowEnergyController::ConnectionError);
        setState(QLowEnergyController::UnconnectedState);
        return;
    }

    struct sockaddr_l2 addr;
    memset(&addr, 0, sizeof(addr));
    addr.l2_family = AF_BLUETOOTH;
    addr.l2_cid = htobs(ATTRIBUTE_CHANNEL_ID);
    addr.l2_bdaddr_type = BDADDR_LE_PUBLIC;
    convertAddress(localAdapter.toUInt64(), addr.l2_bdaddr.b);

    // bind the socket to the local device
    if (::bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
        qCWarning(QT_BT_BLUEZ) << qt_error_string(errno);
        setError(QLowEnergyController::ConnectionError);
        setState(QLowEnergyController::UnconnectedState);
        return;
    }

    // connect
    // Unbuffered mode required to separate each GATT packet
    l2cpSocket->connectToService(remoteDevice, ATTRIBUTE_CHANNEL_ID,
                                 QIODevice::ReadWrite | QIODevice::Unbuffered);
    loadSigningDataIfNecessary(LocalSigningKey);
}

void QLowEnergyControllerPrivate::l2cpConnected()
{
    Q_Q(QLowEnergyController);

    securityLevelValue = securityLevel();
    exchangeMTU();

    setState(QLowEnergyController::ConnectedState);
    emit q->connected();
}

void QLowEnergyControllerPrivate::disconnectFromDevice()
{
    setState(QLowEnergyController::ClosingState);
    l2cpSocket->close();
    resetController();
}

void QLowEnergyControllerPrivate::l2cpDisconnected()
{
    Q_Q(QLowEnergyController);

    if (role == QLowEnergyController::PeripheralRole)
        storeClientConfigurations();
    invalidateServices();
    resetController();
    setState(QLowEnergyController::UnconnectedState);
    emit q->disconnected();
}

void QLowEnergyControllerPrivate::l2cpErrorChanged(QBluetoothSocket::SocketError e)
{
    switch (e) {
    case QBluetoothSocket::HostNotFoundError:
        setError(QLowEnergyController::UnknownRemoteDeviceError);
        qCDebug(QT_BT_BLUEZ) << "The passed remote device address cannot be found";
        break;
    case QBluetoothSocket::NetworkError:
        setError(QLowEnergyController::NetworkError);
        qCDebug(QT_BT_BLUEZ) << "Network IO error while talking to LE device";
        break;
    case QBluetoothSocket::UnknownSocketError:
    case QBluetoothSocket::UnsupportedProtocolError:
    case QBluetoothSocket::OperationError:
    case QBluetoothSocket::ServiceNotFoundError:
    default:
        // these errors shouldn't happen -> as it means
        // the code in this file has bugs
        qCDebug(QT_BT_BLUEZ) << "Unknown l2cp socket error: " << e << l2cpSocket->errorString();
        setError(QLowEnergyController::UnknownError);
        break;
    }

    invalidateServices();
    resetController();
    setState(QLowEnergyController::UnconnectedState);
}


void QLowEnergyControllerPrivate::resetController()
{
    openRequests.clear();
    openPrepareWriteRequests.clear();
    scheduledIndications.clear();
    indicationInFlight = false;
    requestPending = false;
    encryptionChangePending = false;
    receivedMtuExchangeRequest = false;
    securityLevelValue = -1;
    connectionHandle = 0;

    // public API behavior requires stop of advertisement
    if (role == QLowEnergyController::PeripheralRole && advertiser)
        advertiser->stopAdvertising();
}

void QLowEnergyControllerPrivate::restartRequestTimer()
{
    if (!requestTimer)
        return;

    if (gattRequestTimeout > 0)
        requestTimer->start(gattRequestTimeout);
}

void QLowEnergyControllerPrivate::l2cpReadyRead()
{
    const QByteArray incomingPacket = l2cpSocket->readAll();
    qCDebug(QT_BT_BLUEZ) << "Received size:" << incomingPacket.size() << "data:"
                         << incomingPacket.toHex();
    if (incomingPacket.isEmpty())
        return;

    const quint8 command = incomingPacket.constData()[0];
    switch (command) {
    case ATT_OP_HANDLE_VAL_NOTIFICATION:
    {
        processUnsolicitedReply(incomingPacket);
        return;
    }
    case ATT_OP_HANDLE_VAL_INDICATION:
    {
        //send confirmation
        QByteArray packet;
        packet.append(static_cast<char>(ATT_OP_HANDLE_VAL_CONFIRMATION));
        sendPacket(packet);

        processUnsolicitedReply(incomingPacket);
        return;
    }
    //--------------------------------------------------
    // Peripheral side packet handling
    case ATT_OP_EXCHANGE_MTU_REQUEST:
        handleExchangeMtuRequest(incomingPacket);
        return;
    case ATT_OP_FIND_INFORMATION_REQUEST:
        handleFindInformationRequest(incomingPacket);
        return;
    case ATT_OP_FIND_BY_TYPE_VALUE_REQUEST:
        handleFindByTypeValueRequest(incomingPacket);
        return;
    case ATT_OP_READ_BY_TYPE_REQUEST:
        handleReadByTypeRequest(incomingPacket);
        return;
    case ATT_OP_READ_REQUEST:
        handleReadRequest(incomingPacket);
        return;
    case ATT_OP_READ_BLOB_REQUEST:
        handleReadBlobRequest(incomingPacket);
        return;
    case ATT_OP_READ_MULTIPLE_REQUEST:
        handleReadMultipleRequest(incomingPacket);
        return;
    case ATT_OP_READ_BY_GROUP_REQUEST:
        handleReadByGroupTypeRequest(incomingPacket);
        return;
    case ATT_OP_WRITE_REQUEST:
    case ATT_OP_WRITE_COMMAND:
    case ATT_OP_SIGNED_WRITE_COMMAND:
        handleWriteRequestOrCommand(incomingPacket);
        return;
    case ATT_OP_PREPARE_WRITE_REQUEST:
        handlePrepareWriteRequest(incomingPacket);
        return;
    case ATT_OP_EXECUTE_WRITE_REQUEST:
        handleExecuteWriteRequest(incomingPacket);
        return;
    case ATT_OP_HANDLE_VAL_CONFIRMATION:
        if (indicationInFlight) {
            indicationInFlight = false;
            sendNextIndication();
        } else {
            qCWarning(QT_BT_BLUEZ) << "received unexpected handle value confirmation";
        }
        return;
    //--------------------------------------------------
    default:
        //only solicited replies finish pending requests
        requestPending = false;
        break;
    }

    if (openRequests.isEmpty()) {
        qCWarning(QT_BT_BLUEZ) << "Received unexpected packet from peer, disconnecting.";
        disconnectFromDevice();
        return;
    }

    const Request request = openRequests.dequeue();
    processReply(request, incomingPacket);

    sendNextPendingRequest();
}

/*!
 * Called when the request for socket encryption has been
 * processed by the kernel. Such requests take time as the kernel
 * has to renegotiate the link parameters with the remote device.
 *
 * Therefore any such request delays the pending ATT commands until this
 * callback is called. The first pending request in the queue is the request
 * that triggered the encryption request.
 */
void QLowEnergyControllerPrivate::encryptionChangedEvent(
        const QBluetoothAddress &address, bool wasSuccess)
{
    if (!encryptionChangePending) // somebody else caused change event
        return;

    if (remoteDevice != address)
        return;

    securityLevelValue = securityLevel();

    // On success continue to process ATT command queue
    if (!wasSuccess) {
        // We could not increase the security of the link
        // The next request was requeued due to security error
        // skip it to avoid endless loop of security negotiations
        Q_ASSERT(!openRequests.isEmpty());
        Request failedRequest = openRequests.takeFirst();

        if (failedRequest.command == ATT_OP_WRITE_REQUEST) {
             // Failing write requests trigger some sort of response
            uint ref = failedRequest.reference.toUInt();
            const QLowEnergyHandle charHandle = (ref & 0xffff);
            const QLowEnergyHandle descriptorHandle = ((ref >> 16) & 0xffff);

            QSharedPointer<QLowEnergyServicePrivate> service
                                                = serviceForHandle(charHandle);
            if (!service.isNull() && service->characteristicList.contains(charHandle)) {
                if (!descriptorHandle)
                    service->setError(QLowEnergyService::CharacteristicWriteError);
                else
                    service->setError(QLowEnergyService::DescriptorWriteError);
            }
        } else if (failedRequest.command == ATT_OP_PREPARE_WRITE_REQUEST) {
            uint handleData = failedRequest.reference.toUInt();
            const QLowEnergyHandle attrHandle = (handleData & 0xffff);
            const QByteArray newValue = failedRequest.reference2.toByteArray();

            // Prepare command failed, cancel pending prepare queue on
            // the device. The appropriate (Descriptor|Characteristic)WriteError
            // is emitted too once the execute write request comes through
            sendExecuteWriteRequest(attrHandle, newValue, true);
        }
    }

    encryptionChangePending = false;
    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::sendPacket(const QByteArray &packet)
{
    qint64 result = l2cpSocket->write(packet.constData(),
                                      packet.size());
    // We ignore result == 0 which is likely to be caused by EAGAIN.
    // This packet is effectively discarded but the controller can still recover

    if (result == -1) {
        qCDebug(QT_BT_BLUEZ) << "Cannot write L2CP packet:" << hex
                             << packet.toHex()
                             << l2cpSocket->errorString();
        setError(QLowEnergyController::NetworkError);
    } else if (result < packet.size()) {
        qCWarning(QT_BT_BLUEZ) << "L2CP write request incomplete:"
                               << result << "of" << packet.size();
    }

}

void QLowEnergyControllerPrivate::sendNextPendingRequest()
{
    if (openRequests.isEmpty() || requestPending || encryptionChangePending)
        return;

    const Request &request = openRequests.head();
//    qCDebug(QT_BT_BLUEZ) << "Sending request, type:" << hex << request.command
//             << request.payload.toHex();

    requestPending = true;
    restartRequestTimer();
    sendPacket(request.payload);
}

QLowEnergyHandle parseReadByTypeCharDiscovery(
        QLowEnergyServicePrivate::CharData *charData,
        const char *data, quint16 elementLength)
{
    Q_ASSERT(charData);
    Q_ASSERT(data);

    QLowEnergyHandle attributeHandle = bt_get_le16(&data[0]);
    charData->properties =
            (QLowEnergyCharacteristic::PropertyTypes)(data[2] & 0xff);
    charData->valueHandle = bt_get_le16(&data[3]);

    if (elementLength == 7) // 16 bit uuid
        charData->uuid = QBluetoothUuid(bt_get_le16(&data[5]));
    else
        charData->uuid = convert_uuid128((quint128 *)&data[5]);

    qCDebug(QT_BT_BLUEZ) << "Found handle:" << hex << attributeHandle
             << "properties:" << charData->properties
             << "value handle:" << charData->valueHandle
             << "uuid:" << charData->uuid.toString();

    return attributeHandle;
}

QLowEnergyHandle parseReadByTypeIncludeDiscovery(
        QList<QBluetoothUuid> *foundServices,
        const char *data, quint16 elementLength)
{
    Q_ASSERT(foundServices);
    Q_ASSERT(data);

    QLowEnergyHandle attributeHandle = bt_get_le16(&data[0]);

    // the next 2 elements are not required as we have discovered
    // all (primary/secondary) services already. Now we are only
    // interested in their relationship to each other
    // data[2] -> included service start handle
    // data[4] -> included service end handle

    if (elementLength == 8) //16 bit uuid
        foundServices->append(QBluetoothUuid(bt_get_le16(&data[6])));
    else
        foundServices->append(convert_uuid128((quint128 *) &data[6]));

    qCDebug(QT_BT_BLUEZ) << "Found included service: " << hex
                         << attributeHandle << "uuid:" << *foundServices;

    return attributeHandle;
}

void QLowEnergyControllerPrivate::processReply(
        const Request &request, const QByteArray &response)
{
    Q_Q(QLowEnergyController);

    quint8 command = response.constData()[0];

    bool isErrorResponse = false;
    // if error occurred 2. byte is previous request type
    if (command == ATT_OP_ERROR_RESPONSE) {
        dumpErrorInformation(response);
        command = response.constData()[1];
        isErrorResponse = true;
    }

    switch (command) {
    case ATT_OP_EXCHANGE_MTU_REQUEST: // in case of error
    case ATT_OP_EXCHANGE_MTU_RESPONSE:
    {
        Q_ASSERT(request.command == ATT_OP_EXCHANGE_MTU_REQUEST);
        if (isErrorResponse) {
            mtuSize = ATT_DEFAULT_LE_MTU;
            break;
        }

        const char *data = response.constData();
        quint16 mtu = bt_get_le16(&data[1]);
        mtuSize = mtu;
        if (mtuSize < ATT_DEFAULT_LE_MTU)
            mtuSize = ATT_DEFAULT_LE_MTU;

        qCDebug(QT_BT_BLUEZ) << "Server MTU:" << mtu << "resulting mtu:" << mtuSize;
    }
        break;
    case ATT_OP_READ_BY_GROUP_REQUEST: // in case of error
    case ATT_OP_READ_BY_GROUP_RESPONSE:
    {
        // Discovering services
        Q_ASSERT(request.command == ATT_OP_READ_BY_GROUP_REQUEST);

        const quint16 type = request.reference.toUInt();

        if (isErrorResponse) {
            if (type == GATT_SECONDARY_SERVICE) {
                setState(QLowEnergyController::DiscoveredState);
                q->discoveryFinished();
            } else { // search for secondary services
                sendReadByGroupRequest(0x0001, 0xFFFF, GATT_SECONDARY_SERVICE);
            }
            break;
        }

        QLowEnergyHandle start = 0, end = 0;
        const quint16 elementLength = response.constData()[1];
        const quint16 numElements = (response.size() - 2) / elementLength;
        quint16 offset = 2;
        const char *data = response.constData();
        for (int i = 0; i < numElements; i++) {
            start = bt_get_le16(&data[offset]);
            end = bt_get_le16(&data[offset+2]);

            QBluetoothUuid uuid;
            if (elementLength == 6) //16 bit uuid
                uuid = QBluetoothUuid(bt_get_le16(&data[offset+4]));
            else if (elementLength == 20) //128 bit uuid
                uuid = convert_uuid128((quint128 *)&data[offset+4]);
            //else -> do nothing

            offset += elementLength;


            qCDebug(QT_BT_BLUEZ) << "Found uuid:" << uuid << "start handle:" << hex
                     << start << "end handle:" << end;

            QLowEnergyServicePrivate *priv = new QLowEnergyServicePrivate();
            priv->uuid = uuid;
            priv->startHandle = start;
            priv->endHandle = end;
            if (type != GATT_PRIMARY_SERVICE) //unset PrimaryService bit
                priv->type &= ~QLowEnergyService::PrimaryService;
            priv->setController(this);

            QSharedPointer<QLowEnergyServicePrivate> pointer(priv);

            serviceList.insert(uuid, pointer);
            emit q->serviceDiscovered(uuid);
        }

        if (end != 0xFFFF) {
            sendReadByGroupRequest(end+1, 0xFFFF, type);
        } else {
            if (type == GATT_SECONDARY_SERVICE) {
                setState(QLowEnergyController::DiscoveredState);
                emit q->discoveryFinished();
            } else { // search for secondary services
                sendReadByGroupRequest(0x0001, 0xFFFF, GATT_SECONDARY_SERVICE);
            }
        }
    }
        break;
    case ATT_OP_READ_BY_TYPE_REQUEST: //in case of error
    case ATT_OP_READ_BY_TYPE_RESPONSE:
    {
        // Discovering characteristics
        Q_ASSERT(request.command == ATT_OP_READ_BY_TYPE_REQUEST);

        QSharedPointer<QLowEnergyServicePrivate> p =
                request.reference.value<QSharedPointer<QLowEnergyServicePrivate> >();
        const quint16 attributeType = request.reference2.toUInt();

        if (isErrorResponse) {
            if (attributeType == GATT_CHARACTERISTIC) {
                // we reached end of service handle
                // just finished up characteristic discovery
                // continue with values of characteristics
                if (!p->characteristicList.isEmpty()) {
                    readServiceValues(p->uuid, true);
                } else {
                    // discovery finished since the service doesn't have any
                    // characteristics
                    p->setState(QLowEnergyService::ServiceDiscovered);
                }
            } else if (attributeType == GATT_INCLUDED_SERVICE) {
                // finished up include discovery
                // continue with characteristic discovery
                sendReadByTypeRequest(p, p->startHandle, GATT_CHARACTERISTIC);
            }
            break;
        }

        /* packet format:
         * if GATT_CHARACTERISTIC discovery
         *      <opcode><elementLength>
         *          [<handle><property><charHandle><uuid>]+
         *
         * if GATT_INCLUDE discovery
         *      <opcode><elementLength>
         *          [<handle><startHandle_included><endHandle_included><uuid>]+
         *
         *  The uuid can be 16 or 128 bit.
         */
        QLowEnergyHandle lastHandle;
        const quint16 elementLength = response.constData()[1];
        const quint16 numElements = (response.size() - 2) / elementLength;
        quint16 offset = 2;
        const char *data = response.constData();
        for (int i = 0; i < numElements; i++) {
            if (attributeType == GATT_CHARACTERISTIC) {
                QLowEnergyServicePrivate::CharData characteristic;
                lastHandle = parseReadByTypeCharDiscovery(
                            &characteristic, &data[offset], elementLength);
                p->characteristicList[lastHandle] = characteristic;
                offset += elementLength;
            } else if (attributeType == GATT_INCLUDED_SERVICE) {
                QList<QBluetoothUuid> includedServices;
                lastHandle = parseReadByTypeIncludeDiscovery(
                            &includedServices, &data[offset], elementLength);
                p->includedServices = includedServices;
                foreach (const QBluetoothUuid &uuid, includedServices) {
                    if (serviceList.contains(uuid))
                        serviceList[uuid]->type |= QLowEnergyService::IncludedService;
                }
            }
        }

        if (lastHandle + 1 < p->endHandle) { // more chars to discover
            sendReadByTypeRequest(p, lastHandle + 1, attributeType);
        } else {
            if (attributeType == GATT_INCLUDED_SERVICE)
                sendReadByTypeRequest(p, p->startHandle, GATT_CHARACTERISTIC);
            else
                readServiceValues(p->uuid, true);
        }
    }
        break;
    case ATT_OP_READ_REQUEST: //error case
    case ATT_OP_READ_RESPONSE:
    {
        //Reading characteristics and descriptors
        Q_ASSERT(request.command == ATT_OP_READ_REQUEST);

        uint handleData = request.reference.toUInt();
        const QLowEnergyHandle charHandle = (handleData & 0xffff);
        const QLowEnergyHandle descriptorHandle = ((handleData >> 16) & 0xffff);

        QSharedPointer<QLowEnergyServicePrivate> service = serviceForHandle(charHandle);
        Q_ASSERT(!service.isNull());
        bool isServiceDiscoveryRun
                = !(service->state == QLowEnergyService::ServiceDiscovered);

        if (isErrorResponse) {
            Q_ASSERT(!encryptionChangePending);
            encryptionChangePending = increaseEncryptLevelfRequired(response.constData()[4]);
            if (encryptionChangePending) {
                // Just requested a security level change.
                // Retry the same command again once the change has happened
                openRequests.prepend(request);
                break;
            } else if (!isServiceDiscoveryRun) {
                // not encryption problem -> abort readCharacteristic()/readDescriptor() run
                if (!descriptorHandle)
                    emit service->error(QLowEnergyService::CharacteristicReadError);
                else
                    emit service->error(QLowEnergyService::DescriptorReadError);
            }
        } else {
            if (!descriptorHandle)
                updateValueOfCharacteristic(charHandle, response.mid(1), NEW_VALUE);
            else
                updateValueOfDescriptor(charHandle, descriptorHandle,
                                        response.mid(1), NEW_VALUE);

            if (response.size() == mtuSize) {
                qCDebug(QT_BT_BLUEZ) << "Switching to blob reads for"
                         << charHandle << descriptorHandle
                         << service->characteristicList[charHandle].uuid.toString();
                // Potentially more data -> switch to blob reads
                readServiceValuesByOffset(handleData, mtuSize-1,
                                          request.reference2.toBool());
                break;
            } else if (!isServiceDiscoveryRun) {
                // readCharacteristic() or readDescriptor() ongoing
                if (!descriptorHandle) {
                    QLowEnergyCharacteristic ch(service, charHandle);
                    emit service->characteristicRead(ch, response.mid(1));
                } else {
                    QLowEnergyDescriptor descriptor(service, charHandle, descriptorHandle);
                    emit service->descriptorRead(descriptor, response.mid(1));
                }
                break;
            }
        }

        if (request.reference2.toBool() && isServiceDiscoveryRun) {
            // we only run into this code path during the initial service discovery
            // and not when processing readCharacteristics() after service discovery

            //last characteristic -> progress to descriptor discovery
            //last descriptor -> service discovery is done
            if (!descriptorHandle)
                discoverServiceDescriptors(service->uuid);
            else
                service->setState(QLowEnergyService::ServiceDiscovered);
        }
    }
        break;
    case ATT_OP_READ_BLOB_REQUEST: //error case
    case ATT_OP_READ_BLOB_RESPONSE:
    {
        //Reading characteristic or descriptor with value longer value than MTU
        Q_ASSERT(request.command == ATT_OP_READ_BLOB_REQUEST);

        uint handleData = request.reference.toUInt();
        const QLowEnergyHandle charHandle = (handleData & 0xffff);
        const QLowEnergyHandle descriptorHandle = ((handleData >> 16) & 0xffff);

        QSharedPointer<QLowEnergyServicePrivate> service = serviceForHandle(charHandle);
        Q_ASSERT(!service.isNull());

        /*
         * READ_BLOB does not require encryption setup code. BLOB commands
         * are only issued after read request if the read request is too long
         * for single MTU. The preceding read request would have triggered
         * the setup of the encryption already.
         */
        if (!isErrorResponse) {
            quint16 length = 0;
            if (!descriptorHandle)
                length = updateValueOfCharacteristic(charHandle, response.mid(1), APPEND_VALUE);
            else
                length = updateValueOfDescriptor(charHandle, descriptorHandle,
                                        response.mid(1), APPEND_VALUE);

            if (response.size() == mtuSize) {
                readServiceValuesByOffset(handleData, length,
                                          request.reference2.toBool());
                break;
            } else if (service->state == QLowEnergyService::ServiceDiscovered) {
                // readCharacteristic() or readDescriptor() ongoing
                if (!descriptorHandle) {
                    QLowEnergyCharacteristic ch(service, charHandle);
                    emit service->characteristicRead(ch, ch.value());
                } else {
                    QLowEnergyDescriptor descriptor(service, charHandle, descriptorHandle);
                    emit service->descriptorRead(descriptor, descriptor.value());
                }
                break;
            }
        } else {
            qWarning() << "READ BLOB for char:" << charHandle
                       << "descriptor:" << descriptorHandle << "on service"
                       << service->uuid.toString() << "failed (service discovery run:"
                       << (service->state == QLowEnergyService::ServiceDiscovered) << ")";
        }

        if (request.reference2.toBool()) {
            //last overlong characteristic -> progress to descriptor discovery
            //last overlong descriptor -> service discovery is done

            if (!descriptorHandle)
                discoverServiceDescriptors(service->uuid);
            else
                service->setState(QLowEnergyService::ServiceDiscovered);
        }

    }
        break;
    case ATT_OP_FIND_INFORMATION_REQUEST: //error case
    case ATT_OP_FIND_INFORMATION_RESPONSE:
    {
        //Discovering descriptors
        Q_ASSERT(request.command == ATT_OP_FIND_INFORMATION_REQUEST);

        /* packet format:
         *  <opcode><format>[<handle><descriptor_uuid>]+
         *
         *  The uuid can be 16 or 128 bit which is indicated by format.
         */

        QList<QLowEnergyHandle> keys = request.reference.value<QList<QLowEnergyHandle> >();
        if (keys.isEmpty()) {
            qCWarning(QT_BT_BLUEZ) << "Descriptor discovery for unknown characteristic received";
            break;
        }
        QLowEnergyHandle charHandle = keys.first();

        QSharedPointer<QLowEnergyServicePrivate> p =
                serviceForHandle(charHandle);
        Q_ASSERT(!p.isNull());

        if (isErrorResponse) {
            if (keys.count() == 1) {
                // no more descriptors to discover
                readServiceValues(p->uuid, false); //read descriptor values
            } else {
                // hop to the next descriptor
                keys.removeFirst();
                discoverNextDescriptor(p, keys, keys.first());
            }
            break;
        }

        const quint8 format = response[1];
        quint16 elementLength;
        switch (format) {
        case 0x01:
            elementLength = 2 + 2; //sizeof(QLowEnergyHandle) + 16bit uuid
            break;
        case 0x02:
            elementLength = 2 + 16; //sizeof(QLowEnergyHandle) + 128bit uuid
            break;
        default:
            qCWarning(QT_BT_BLUEZ) << "Unknown format in FIND_INFORMATION_RESPONSE";
            return;
        }

        const quint16 numElements = (response.size() - 2) / elementLength;

        quint16 offset = 2;
        QLowEnergyHandle descriptorHandle;
        QBluetoothUuid uuid;
        const char *data = response.constData();
        for (int i = 0; i < numElements; i++) {
            descriptorHandle = bt_get_le16(&data[offset]);

            if (format == 0x01)
                uuid = QBluetoothUuid(bt_get_le16(&data[offset+2]));
            else if (format == 0x02)
                uuid = convert_uuid128((quint128 *)&data[offset+2]);

            offset += elementLength;

            // ignore all attributes which are not of type descriptor
            // examples are the characteristics value or
            bool ok = false;
            quint16 shortUuid = uuid.toUInt16(&ok);
            if (ok && shortUuid >= QLowEnergyServicePrivate::PrimaryService
                   && shortUuid <= QLowEnergyServicePrivate::Characteristic){
                qCDebug(QT_BT_BLUEZ) << "Suppressing primary/characteristic" << hex << shortUuid;
                continue;
            }

            // ignore value handle
            if (descriptorHandle == p->characteristicList[charHandle].valueHandle) {
                qCDebug(QT_BT_BLUEZ) << "Suppressing char handle" << hex << descriptorHandle;
                continue;
            }

            QLowEnergyServicePrivate::DescData data;
            data.uuid = uuid;
            p->characteristicList[charHandle].descriptorList.insert(
                        descriptorHandle, data);

            qCDebug(QT_BT_BLUEZ) << "Descriptor found, uuid:"
                                 << uuid.toString()
                                 << "descriptor handle:" << hex << descriptorHandle;
        }

        const QLowEnergyHandle nextPotentialHandle = descriptorHandle + 1;
        if (keys.count() == 1) {
            // Reached last characteristic of service

            // The endhandle of a service is always the last handle of
            // the current service. We must either continue until we have reached
            // the starting handle of the next service (endHandle+1) or
            // the last physical handle address (0xffff). Note that
            // the endHandle of the last service on the device is 0xffff.

            if ((p->endHandle != 0xffff && nextPotentialHandle >= p->endHandle + 1)
                    || (descriptorHandle == 0xffff)) {
                keys.removeFirst();
                // last descriptor of last characteristic found
                // continue with reading descriptor values
                readServiceValues(p->uuid, false);
            } else {
                discoverNextDescriptor(p, keys, nextPotentialHandle);
            }
        } else {
            if (nextPotentialHandle >= keys[1]) //reached next char
                keys.removeFirst();
            discoverNextDescriptor(p, keys, nextPotentialHandle);
        }
    }
        break;
    case ATT_OP_WRITE_REQUEST: //error case
    case ATT_OP_WRITE_RESPONSE:
    {
        //Write command response
        Q_ASSERT(request.command == ATT_OP_WRITE_REQUEST);

        uint ref = request.reference.toUInt();
        const QLowEnergyHandle charHandle = (ref & 0xffff);
        const QLowEnergyHandle descriptorHandle = ((ref >> 16) & 0xffff);

        QSharedPointer<QLowEnergyServicePrivate> service = serviceForHandle(charHandle);
        if (service.isNull() || !service->characteristicList.contains(charHandle))
            break;

        if (isErrorResponse) {
            Q_ASSERT(!encryptionChangePending);
            encryptionChangePending = increaseEncryptLevelfRequired(response.constData()[4]);
            if (encryptionChangePending) {
                openRequests.prepend(request);
                break;
            }

            if (!descriptorHandle)
                service->setError(QLowEnergyService::CharacteristicWriteError);
            else
                service->setError(QLowEnergyService::DescriptorWriteError);
            break;
        }

        const QByteArray newValue = request.reference2.toByteArray();
        if (!descriptorHandle) {
            QLowEnergyCharacteristic ch(service, charHandle);
            if (ch.properties() & QLowEnergyCharacteristic::Read)
                updateValueOfCharacteristic(charHandle, newValue, NEW_VALUE);
            emit service->characteristicWritten(ch, newValue);
        } else {
            updateValueOfDescriptor(charHandle, descriptorHandle, newValue, NEW_VALUE);
            QLowEnergyDescriptor descriptor(service, charHandle, descriptorHandle);
            emit service->descriptorWritten(descriptor, newValue);
        }
    }
        break;
    case ATT_OP_PREPARE_WRITE_REQUEST: //error case
    case ATT_OP_PREPARE_WRITE_RESPONSE:
    {
        //Prepare write command response
        Q_ASSERT(request.command == ATT_OP_PREPARE_WRITE_REQUEST);

        uint handleData = request.reference.toUInt();
        const QLowEnergyHandle attrHandle = (handleData & 0xffff);
        const QByteArray newValue = request.reference2.toByteArray();
        const int writtenPayload = ((handleData >> 16) & 0xffff);

        if (isErrorResponse) {
            Q_ASSERT(!encryptionChangePending);
            encryptionChangePending = increaseEncryptLevelfRequired(response.constData()[4]);
            if (encryptionChangePending) {
                openRequests.prepend(request);
                break;
            }
            //emits error on cancellation and aborts existing prepare reuqests
            sendExecuteWriteRequest(attrHandle, newValue, true);
        } else {
            if (writtenPayload < newValue.size()) {
                sendNextPrepareWriteRequest(attrHandle, newValue, writtenPayload);
            } else {
                sendExecuteWriteRequest(attrHandle, newValue, false);
            }
        }
    }
        break;
    case ATT_OP_EXECUTE_WRITE_REQUEST: //error case
    case ATT_OP_EXECUTE_WRITE_RESPONSE:
    {
        // right now used in connection with long characteristic/descriptor value writes
        // not catering for reliable writes
        Q_ASSERT(request.command == ATT_OP_EXECUTE_WRITE_REQUEST);

        uint handleData = request.reference.toUInt();
        const QLowEnergyHandle attrHandle = handleData & 0xffff;
        bool wasCancellation = !((handleData >> 16) & 0xffff);
        const QByteArray newValue = request.reference2.toByteArray();

        // is it a descriptor or characteristic?
        const QLowEnergyDescriptor descriptor = descriptorForHandle(attrHandle);
        QSharedPointer<QLowEnergyServicePrivate> service = serviceForHandle(attrHandle);
        Q_ASSERT(!service.isNull());

        if (isErrorResponse || wasCancellation) {
            // charHandle == 0 -> cancellation
            if (descriptor.isValid())
                service->setError(QLowEnergyService::DescriptorWriteError);
            else
                service->setError(QLowEnergyService::CharacteristicWriteError);
        } else {
            if (descriptor.isValid()) {
                updateValueOfDescriptor(descriptor.characteristicHandle(),
                                        attrHandle, newValue, NEW_VALUE);
                emit service->descriptorWritten(descriptor, newValue);
            } else {
                QLowEnergyCharacteristic ch(service, attrHandle);
                if (ch.properties() & QLowEnergyCharacteristic::Read)
                    updateValueOfCharacteristic(attrHandle, newValue, NEW_VALUE);
                emit service->characteristicWritten(ch, newValue);
            }
        }
    }
        break;
    default:
        qCDebug(QT_BT_BLUEZ) << "Unknown packet: " << response.toHex();
        break;
    }
}

void QLowEnergyControllerPrivate::discoverServices()
{
    sendReadByGroupRequest(0x0001, 0xFFFF, GATT_PRIMARY_SERVICE);
}

void QLowEnergyControllerPrivate::sendReadByGroupRequest(
        QLowEnergyHandle start, QLowEnergyHandle end, quint16 type)
{
    //call for primary and secondary services
    quint8 packet[GRP_TYPE_REQ_HEADER_SIZE];

    packet[0] = ATT_OP_READ_BY_GROUP_REQUEST;
    putBtData(start, &packet[1]);
    putBtData(end, &packet[3]);
    putBtData(type, &packet[5]);

    QByteArray data(GRP_TYPE_REQ_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet,  GRP_TYPE_REQ_HEADER_SIZE);
    qCDebug(QT_BT_BLUEZ) << "Sending read_by_group_type request, startHandle:" << hex
             << start << "endHandle:" << end << type;

    Request request;
    request.payload = data;
    request.command = ATT_OP_READ_BY_GROUP_REQUEST;
    request.reference = type;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::discoverServiceDetails(const QBluetoothUuid &service)
{
    if (!serviceList.contains(service)) {
        qCWarning(QT_BT_BLUEZ) << "Discovery of unknown service" << service.toString()
                               << "not possible";
        return;
    }

    QSharedPointer<QLowEnergyServicePrivate> serviceData = serviceList.value(service);
    serviceData->characteristicList.clear();
    sendReadByTypeRequest(serviceData, serviceData->startHandle, GATT_INCLUDED_SERVICE);
}

void QLowEnergyControllerPrivate::sendReadByTypeRequest(
        QSharedPointer<QLowEnergyServicePrivate> serviceData,
        QLowEnergyHandle nextHandle, quint16 attributeType)
{
    quint8 packet[READ_BY_TYPE_REQ_HEADER_SIZE];

    packet[0] = ATT_OP_READ_BY_TYPE_REQUEST;
    putBtData(nextHandle, &packet[1]);
    putBtData(serviceData->endHandle, &packet[3]);
    putBtData(attributeType, &packet[5]);

    QByteArray data(READ_BY_TYPE_REQ_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet,  READ_BY_TYPE_REQ_HEADER_SIZE);
    qCDebug(QT_BT_BLUEZ) << "Sending read_by_type request, startHandle:" << hex
             << nextHandle << "endHandle:" << serviceData->endHandle
             << "type:" << attributeType << "packet:" << data.toHex();

    Request request;
    request.payload = data;
    request.command = ATT_OP_READ_BY_TYPE_REQUEST;
    request.reference = QVariant::fromValue(serviceData);
    request.reference2 = attributeType;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

/*!
    \internal

    Reads all values of specific characteristic and descriptor. This function is
    used during the initial service discovery process.

    \a readCharacteristics determines whether we intend to read a characteristic;
    otherwise we read a descriptor.
 */
void QLowEnergyControllerPrivate::readServiceValues(
        const QBluetoothUuid &serviceUuid, bool readCharacteristics)
{
    quint8 packet[READ_REQUEST_HEADER_SIZE];
    if (QT_BT_BLUEZ().isDebugEnabled()) {
        if (readCharacteristics)
            qCDebug(QT_BT_BLUEZ) << "Reading all characteristic values for"
                         << serviceUuid.toString();
        else
            qCDebug(QT_BT_BLUEZ) << "Reading all descriptor values for"
                         << serviceUuid.toString();
    }

    QSharedPointer<QLowEnergyServicePrivate> service = serviceList.value(serviceUuid);

    // pair.first -> target attribute
    // pair.second -> context information for read request
    QPair<QLowEnergyHandle, quint32> pair;

    // Create list of attribute handles which need to be read
    QList<QPair<QLowEnergyHandle, quint32> > targetHandles;

    CharacteristicDataMap::const_iterator charIt = service->characteristicList.constBegin();
    for ( ; charIt != service->characteristicList.constEnd(); ++charIt) {
        const QLowEnergyHandle charHandle = charIt.key();
        const QLowEnergyServicePrivate::CharData &charDetails = charIt.value();

        if (readCharacteristics) {
            // Collect handles of all characteristic value attributes

            // Don't try to read writeOnly characteristic
            if (!(charDetails.properties & QLowEnergyCharacteristic::Read))
                continue;

            pair.first = charDetails.valueHandle;
            pair.second  = charHandle;
            targetHandles.append(pair);

        } else {
            // Collect handles of all descriptor attributes
            DescriptorDataMap::const_iterator descIt = charDetails.descriptorList.constBegin();
            for ( ; descIt != charDetails.descriptorList.constEnd(); ++descIt) {
                const QLowEnergyHandle descriptorHandle = descIt.key();

                pair.first = descriptorHandle;
                pair.second = (charHandle | (descriptorHandle << 16));
                targetHandles.append(pair);
            }
        }
    }


    if (targetHandles.isEmpty()) {
        if (readCharacteristics) {
            // none of the characteristics is readable
            // -> continue with descriptor discovery
            discoverServiceDescriptors(service->uuid);
        } else {
            // characteristic w/o descriptors
            service->setState(QLowEnergyService::ServiceDiscovered);
        }
        return;
    }

    for (int i = 0; i < targetHandles.count(); i++) {
        pair = targetHandles.at(i);
        packet[0] = ATT_OP_READ_REQUEST;
        putBtData(pair.first, &packet[1]);

        QByteArray data(READ_REQUEST_HEADER_SIZE, Qt::Uninitialized);
        memcpy(data.data(), packet,  READ_REQUEST_HEADER_SIZE);

        Request request;
        request.payload = data;
        request.command = ATT_OP_READ_REQUEST;
        request.reference = pair.second;
        // last entry?
        request.reference2 = QVariant((bool)(i + 1 == targetHandles.count()));
        openRequests.enqueue(request);
    }

    sendNextPendingRequest();
}

/*!
    \internal

    This function is used when reading a handle value that is
    longer than the mtuSize.

    The BLOB read request is prepended to the list of
    open requests to finish the current value read up before
    starting the next read request.
 */
void QLowEnergyControllerPrivate::readServiceValuesByOffset(
        uint handleData, quint16 offset, bool isLastValue)
{
    const QLowEnergyHandle charHandle = (handleData & 0xffff);
    const QLowEnergyHandle descriptorHandle = ((handleData >> 16) & 0xffff);

    QByteArray data(READ_BLOB_REQUEST_HEADER_SIZE, Qt::Uninitialized);
    data[0] = ATT_OP_READ_BLOB_REQUEST;

    QLowEnergyHandle handleToRead = charHandle;
    if (descriptorHandle) {
        handleToRead = descriptorHandle;
        qCDebug(QT_BT_BLUEZ) << "Reading descriptor via blob request"
                             << hex << descriptorHandle;
    } else {
        //charHandle is not the char's value handle
        QSharedPointer<QLowEnergyServicePrivate> service =
                serviceForHandle(charHandle);
        if (!service.isNull()
                && service->characteristicList.contains(charHandle)) {
            handleToRead = service->characteristicList[charHandle].valueHandle;
            qCDebug(QT_BT_BLUEZ) << "Reading characteristic via blob request"
                                 << hex << handleToRead;
        } else {
            Q_ASSERT(false);
        }
    }

    putBtData(handleToRead, data.data() + 1);
    putBtData(offset, data.data() + 3);

    Request request;
    request.payload = data;
    request.command = ATT_OP_READ_BLOB_REQUEST;
    request.reference = handleData;
    request.reference2 = isLastValue;
    openRequests.prepend(request);
}

void QLowEnergyControllerPrivate::discoverServiceDescriptors(
        const QBluetoothUuid &serviceUuid)
{
    qCDebug(QT_BT_BLUEZ) << "Discovering descriptor values for"
                         << serviceUuid.toString();
    QSharedPointer<QLowEnergyServicePrivate> service = serviceList.value(serviceUuid);

    if (service->characteristicList.isEmpty()) { // service has no characteristics
        // implies that characteristic & descriptor discovery can be skipped
        service->setState(QLowEnergyService::ServiceDiscovered);
        return;
    }

    // start handle of all known characteristics
    QList<QLowEnergyHandle> keys = service->characteristicList.keys();
    std::sort(keys.begin(), keys.end());

    discoverNextDescriptor(service, keys, keys[0]);
}

void QLowEnergyControllerPrivate::processUnsolicitedReply(const QByteArray &payload)
{
    const char *data = payload.constData();
    bool isNotification = (data[0] == ATT_OP_HANDLE_VAL_NOTIFICATION);
    const QLowEnergyHandle changedHandle = bt_get_le16(&data[1]);

    if (QT_BT_BLUEZ().isDebugEnabled()) {
        if (isNotification)
            qCDebug(QT_BT_BLUEZ) << "Change notification for handle" << hex << changedHandle;
        else
            qCDebug(QT_BT_BLUEZ) << "Change indication for handle" << hex << changedHandle;
    }

    const QLowEnergyCharacteristic ch = characteristicForHandle(changedHandle);
    if (ch.isValid() && ch.handle() == changedHandle) {
        if (ch.properties() & QLowEnergyCharacteristic::Read)
            updateValueOfCharacteristic(ch.attributeHandle(), payload.mid(3), NEW_VALUE);
        emit ch.d_ptr->characteristicChanged(ch, payload.mid(3));
    } else {
        qCWarning(QT_BT_BLUEZ) << "Cannot find matching characteristic for "
                                  "notification/indication";
    }
}

void QLowEnergyControllerPrivate::exchangeMTU()
{
    qCDebug(QT_BT_BLUEZ) << "Exchanging MTU";

    quint8 packet[MTU_EXCHANGE_HEADER_SIZE];
    packet[0] = ATT_OP_EXCHANGE_MTU_REQUEST;
    putBtData(quint16(ATT_MAX_LE_MTU), &packet[1]);

    QByteArray data(MTU_EXCHANGE_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet, MTU_EXCHANGE_HEADER_SIZE);

    Request request;
    request.payload = data;
    request.command = ATT_OP_EXCHANGE_MTU_REQUEST;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

int QLowEnergyControllerPrivate::securityLevel() const
{
    int socket = l2cpSocket->socketDescriptor();
    if (socket < 0) {
        qCWarning(QT_BT_BLUEZ) << "Invalid l2cp socket, aborting getting of sec level";
        return -1;
    }

    struct bt_security secData;
    socklen_t length = sizeof(secData);
    memset(&secData, 0, length);

    if (getsockopt(socket, SOL_BLUETOOTH, BT_SECURITY, &secData, &length) == 0) {
        qCDebug(QT_BT_BLUEZ) << "Current l2cp sec level:" << secData.level;
        return secData.level;
    }

    if (errno != ENOPROTOOPT) //older kernel, fall back to L2CAP_LM option
        return -1;

    // cater for older kernels
    int optval;
    length = sizeof(optval);
    if (getsockopt(socket, SOL_L2CAP, L2CAP_LM, &optval, &length) == 0) {
        int level = BT_SECURITY_SDP;
        if (optval & L2CAP_LM_AUTH)
            level = BT_SECURITY_LOW;
        if (optval & L2CAP_LM_ENCRYPT)
            level = BT_SECURITY_MEDIUM;
        if (optval & L2CAP_LM_SECURE)
            level = BT_SECURITY_HIGH;

        qDebug() << "Current l2cp sec level (old):" << level;
        return level;
    }

    return -1;
}

bool QLowEnergyControllerPrivate::setSecurityLevel(int level)
{
    if (level > BT_SECURITY_HIGH || level < BT_SECURITY_LOW)
        return false;

    int socket = l2cpSocket->socketDescriptor();
    if (socket < 0) {
        qCWarning(QT_BT_BLUEZ) << "Invalid l2cp socket, aborting setting of sec level";
        return false;
    }

    struct bt_security secData;
    socklen_t length = sizeof(secData);
    memset(&secData, 0, length);
    secData.level = level;

    if (setsockopt(socket, SOL_BLUETOOTH, BT_SECURITY, &secData, length) == 0) {
        qCDebug(QT_BT_BLUEZ) << "Setting new l2cp sec level:" << secData.level;
        return true;
    }

    if (errno != ENOPROTOOPT) //older kernel
        return false;

    int optval = 0;
    switch (level) { // fall through intendeds
        case BT_SECURITY_HIGH:
            optval |= L2CAP_LM_SECURE;
            Q_FALLTHROUGH();
        case BT_SECURITY_MEDIUM:
            optval |= L2CAP_LM_ENCRYPT;
            Q_FALLTHROUGH();
        case BT_SECURITY_LOW:
            optval |= L2CAP_LM_AUTH;
            break;
        default:
            return false;
    }

    if (setsockopt(socket, SOL_L2CAP, L2CAP_LM, &optval, sizeof(optval)) == 0) {
        qDebug(QT_BT_BLUEZ) << "Old l2cp sec level:" << optval;
        return true;
    }

    return false;
}

void QLowEnergyControllerPrivate::discoverNextDescriptor(
        QSharedPointer<QLowEnergyServicePrivate> serviceData,
        const QList<QLowEnergyHandle> pendingCharHandles,
        const QLowEnergyHandle startingHandle)
{
    Q_ASSERT(!pendingCharHandles.isEmpty());
    Q_ASSERT(!serviceData.isNull());

    qCDebug(QT_BT_BLUEZ) << "Sending find_info request" << hex
                         << pendingCharHandles << startingHandle;

    quint8 packet[FIND_INFO_REQUEST_HEADER_SIZE];
    packet[0] = ATT_OP_FIND_INFORMATION_REQUEST;

    const QLowEnergyHandle charStartHandle = startingHandle;
    QLowEnergyHandle charEndHandle = 0;
    if (pendingCharHandles.count() == 1) //single characteristic
        charEndHandle = serviceData->endHandle;
    else
        charEndHandle = pendingCharHandles[1] - 1;

    putBtData(charStartHandle, &packet[1]);
    putBtData(charEndHandle, &packet[3]);

    QByteArray data(FIND_INFO_REQUEST_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet, FIND_INFO_REQUEST_HEADER_SIZE);

    Request request;
    request.payload = data;
    request.command = ATT_OP_FIND_INFORMATION_REQUEST;
    request.reference = QVariant::fromValue<QList<QLowEnergyHandle> >(pendingCharHandles);
    request.reference2 = startingHandle;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::sendNextPrepareWriteRequest(
        const QLowEnergyHandle handle, const QByteArray &newValue,
        quint16 offset)
{
    // is it a descriptor or characteristic?
    QLowEnergyHandle targetHandle = 0;
    const QLowEnergyDescriptor descriptor = descriptorForHandle(handle);
    if (descriptor.isValid())
        targetHandle = descriptor.handle();
    else
        targetHandle = characteristicForHandle(handle).handle();

    if (!targetHandle) {
        qCWarning(QT_BT_BLUEZ) << "sendNextPrepareWriteRequest cancelled due to invalid handle"
                               << handle;
        return;
    }

    quint8 packet[PREPARE_WRITE_HEADER_SIZE];
    packet[0] = ATT_OP_PREPARE_WRITE_REQUEST;
    putBtData(targetHandle, &packet[1]); // attribute handle
    putBtData(offset, &packet[3]); // offset into newValue

    qCDebug(QT_BT_BLUEZ) << "Writing long characteristic (prepare):"
                         << hex << handle;


    const int maxAvailablePayload = mtuSize - PREPARE_WRITE_HEADER_SIZE;
    const int requiredPayload = qMin(newValue.size() - offset, maxAvailablePayload);
    const int dataSize = PREPARE_WRITE_HEADER_SIZE + requiredPayload;

    Q_ASSERT((offset + requiredPayload) <= newValue.size());
    Q_ASSERT(dataSize <= mtuSize);

    QByteArray data(dataSize, Qt::Uninitialized);
    memcpy(data.data(), packet, PREPARE_WRITE_HEADER_SIZE);
    memcpy(&(data.data()[PREPARE_WRITE_HEADER_SIZE]), &(newValue.constData()[offset]),
                                               requiredPayload);

    Request request;
    request.payload = data;
    request.command = ATT_OP_PREPARE_WRITE_REQUEST;
    request.reference = (handle | ((offset + requiredPayload) << 16));
    request.reference2 = newValue;
    openRequests.enqueue(request);
}

/*!
    Sends an "Execute Write Request" for a long characteristic or descriptor write.
    This cannot be used for executes in relation to reliable write requests.

    A cancellation removes all pending prepare write request on the GATT server.
    Otherwise this function sends an execute request for all pending prepare
    write requests.
 */
void QLowEnergyControllerPrivate::sendExecuteWriteRequest(
        const QLowEnergyHandle attrHandle, const QByteArray &newValue,
        bool isCancelation)
{
    quint8 packet[EXECUTE_WRITE_HEADER_SIZE];
    packet[0] = ATT_OP_EXECUTE_WRITE_REQUEST;
    if (isCancelation)
        packet[1] = 0x00; // cancel pending write prepare requests
    else
        packet[1] = 0x01; // execute pending write prepare requests

    QByteArray data(EXECUTE_WRITE_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet, EXECUTE_WRITE_HEADER_SIZE);

    qCDebug(QT_BT_BLUEZ) << "Sending Execute Write Request for long characteristic value"
                         << hex << attrHandle;

    Request request;
    request.payload = data;
    request.command = ATT_OP_EXECUTE_WRITE_REQUEST;
    request.reference  = (attrHandle | ((isCancelation ? 0x00 : 0x01) << 16));
    request.reference2 = newValue;
    openRequests.prepend(request);
}


/*!
    Writes long (prepare write request), short (write request)
    and writeWithoutResponse characteristic values.

    TODO Reliable/prepare write across multiple characteristics is not supported
 */
void QLowEnergyControllerPrivate::writeCharacteristic(
        const QSharedPointer<QLowEnergyServicePrivate> service,
        const QLowEnergyHandle charHandle,
        const QByteArray &newValue,
        QLowEnergyService::WriteMode mode)
{
    Q_ASSERT(!service.isNull());

    if (!service->characteristicList.contains(charHandle))
        return;

    QLowEnergyServicePrivate::CharData &charData = service->characteristicList[charHandle];
    if (role == QLowEnergyController::PeripheralRole)
        writeCharacteristicForPeripheral(charData, newValue);
    else
        writeCharacteristicForCentral(service, charHandle, charData.valueHandle, newValue, mode);
}

void QLowEnergyControllerPrivate::writeDescriptor(
        const QSharedPointer<QLowEnergyServicePrivate> service,
        const QLowEnergyHandle charHandle,
        const QLowEnergyHandle descriptorHandle,
        const QByteArray &newValue)
{
    Q_ASSERT(!service.isNull());

    if (role == QLowEnergyController::PeripheralRole)
        writeDescriptorForPeripheral(service, charHandle, descriptorHandle, newValue);
    else
        writeDescriptorForCentral(charHandle, descriptorHandle, newValue);
}

/*!
    \internal

    Reads the value of one specific characteristic.
 */
void QLowEnergyControllerPrivate::readCharacteristic(
        const QSharedPointer<QLowEnergyServicePrivate> service,
        const QLowEnergyHandle charHandle)
{
    Q_ASSERT(!service.isNull());
    if (!service->characteristicList.contains(charHandle))
        return;

    const QLowEnergyServicePrivate::CharData &charDetails
            = service->characteristicList[charHandle];
    if (!(charDetails.properties & QLowEnergyCharacteristic::Read)) {
        // if this succeeds the device has a bug, char is advertised as
        // non-readable. We try to be permissive and let the remote
        // device answer to the read attempt
        qCWarning(QT_BT_BLUEZ) << "Reading non-readable char" << charHandle;
    }

    quint8 packet[READ_REQUEST_HEADER_SIZE];
    packet[0] = ATT_OP_READ_REQUEST;
    putBtData(charDetails.valueHandle, &packet[1]);

    QByteArray data(READ_REQUEST_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet,  READ_REQUEST_HEADER_SIZE);

    qCDebug(QT_BT_BLUEZ) << "Targeted reading characteristic" << hex << charHandle;

    Request request;
    request.payload = data;
    request.command = ATT_OP_READ_REQUEST;
    request.reference = charHandle;
    // reference2 not really required but false prevents service discovery
    // code from running in ATT_OP_READ_RESPONSE handler
    request.reference2 = false;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::readDescriptor(
        const QSharedPointer<QLowEnergyServicePrivate> service,
        const QLowEnergyHandle charHandle,
        const QLowEnergyHandle descriptorHandle)
{
    Q_ASSERT(!service.isNull());
    if (!service->characteristicList.contains(charHandle))
        return;

    const QLowEnergyServicePrivate::CharData &charDetails
            = service->characteristicList[charHandle];
    if (!charDetails.descriptorList.contains(descriptorHandle))
        return;

    quint8 packet[READ_REQUEST_HEADER_SIZE];
    packet[0] = ATT_OP_READ_REQUEST;
    putBtData(descriptorHandle, &packet[1]);

    QByteArray data(READ_REQUEST_HEADER_SIZE, Qt::Uninitialized);
    memcpy(data.data(), packet,  READ_REQUEST_HEADER_SIZE);

    qCDebug(QT_BT_BLUEZ) << "Targeted reading descriptor" << hex << descriptorHandle;

    Request request;
    request.payload = data;
    request.command = ATT_OP_READ_REQUEST;
    request.reference = (charHandle | (descriptorHandle << 16));
    // reference2 not really required but false prevents service discovery
    // code from running in ATT_OP_READ_RESPONSE handler
    request.reference2 = false;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

/*!
 * Returns true if the encryption change was successfully requested.
 * The request is triggered if we got a related ATT error.
 */
bool QLowEnergyControllerPrivate::increaseEncryptLevelfRequired(quint8 errorCode)
{
    if (securityLevelValue == BT_SECURITY_HIGH)
        return false;

    switch (errorCode) {
    case ATT_ERROR_INSUF_ENCRYPTION:
    case ATT_ERROR_INSUF_AUTHENTICATION:
    case ATT_ERROR_INSUF_ENCR_KEY_SIZE:
        if (!hciManager->isValid())
            return false;
        if (!hciManager->monitorEvent(HciManager::EncryptChangeEvent))
            return false;
        if (securityLevelValue != BT_SECURITY_HIGH) {
            qCDebug(QT_BT_BLUEZ) << "Requesting encrypted link";
            if (setSecurityLevel(BT_SECURITY_HIGH)) {
                restartRequestTimer();
                return true;
            }
        }
        break;
    default:
        break;
    }

    return false;
}

void QLowEnergyControllerPrivate::handleAdvertisingError()
{
    qCWarning(QT_BT_BLUEZ) << "received advertising error";
    setError(QLowEnergyController::AdvertisingError);
    setState(QLowEnergyController::UnconnectedState);
}

bool QLowEnergyControllerPrivate::checkPacketSize(const QByteArray &packet, int minSize,
                                                  int maxSize)
{
    if (maxSize == -1)
        maxSize = minSize;
    if (Q_LIKELY(packet.count() >= minSize && packet.count() <= maxSize))
        return true;
    qCWarning(QT_BT_BLUEZ) << "client request of type" << packet.at(0)
                           << "has unexpected packet size" << packet.count();
    sendErrorResponse(packet.at(0), 0, ATT_ERROR_INVALID_PDU);
    return false;
}

bool QLowEnergyControllerPrivate::checkHandle(const QByteArray &packet, QLowEnergyHandle handle)
{
    if (handle != 0 && handle <= lastLocalHandle)
        return true;
    sendErrorResponse(packet.at(0), handle, ATT_ERROR_INVALID_HANDLE);
    return false;
}

bool QLowEnergyControllerPrivate::checkHandlePair(quint8 request, QLowEnergyHandle startingHandle,
                                                  QLowEnergyHandle endingHandle)
{
    if (startingHandle == 0 || startingHandle > endingHandle) {
        qCDebug(QT_BT_BLUEZ) << "handle range invalid";
        sendErrorResponse(request, startingHandle, ATT_ERROR_INVALID_HANDLE);
        return false;
    }
    return true;
}

void QLowEnergyControllerPrivate::handleExchangeMtuRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.2

    if (!checkPacketSize(packet, 3))
        return;
    if (receivedMtuExchangeRequest) { // Client must only send this once per connection.
        qCDebug(QT_BT_BLUEZ) << "Client sent extraneous MTU exchange packet";
        sendErrorResponse(packet.at(0), 0, ATT_ERROR_REQUEST_NOT_SUPPORTED);
        return;
    }
    receivedMtuExchangeRequest = true;

    // Send reply.
    QByteArray reply(MTU_EXCHANGE_HEADER_SIZE, Qt::Uninitialized);
    reply[0] = ATT_OP_EXCHANGE_MTU_RESPONSE;
    putBtData(static_cast<quint16>(ATT_MAX_LE_MTU), reply.data() + 1);
    sendPacket(reply);

    // Apply requested MTU.
    const quint16 clientRxMtu = bt_get_le16(packet.constData() + 1);
    mtuSize = qMax<quint16>(ATT_DEFAULT_LE_MTU, qMin<quint16>(clientRxMtu, ATT_MAX_LE_MTU));
    qCDebug(QT_BT_BLUEZ) << "MTU request from client:" << clientRxMtu
                         << "effective client RX MTU:" << mtuSize;
    qCDebug(QT_BT_BLUEZ) << "Sending server RX MTU" << ATT_MAX_LE_MTU;
}

void QLowEnergyControllerPrivate::handleFindInformationRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.3.1-2

    if (!checkPacketSize(packet, 5))
        return;
    const QLowEnergyHandle startingHandle = bt_get_le16(packet.constData() + 1);
    const QLowEnergyHandle endingHandle = bt_get_le16(packet.constData() + 3);
    qCDebug(QT_BT_BLUEZ) << "client sends find information request; start:" << startingHandle
                         << "end:" << endingHandle;
    if (!checkHandlePair(packet.at(0), startingHandle, endingHandle))
        return;

    QVector<Attribute> results = getAttributes(startingHandle, endingHandle);
    if (results.isEmpty()) {
        sendErrorResponse(packet.at(0), startingHandle, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
        return;
    }
    ensureUniformUuidSizes(results);

    QByteArray responsePrefix(2, Qt::Uninitialized);
    const int uuidSize = getUuidSize(results.first().type);
    responsePrefix[0] = ATT_OP_FIND_INFORMATION_RESPONSE;
    responsePrefix[1] = uuidSize == 2 ? 0x1 : 0x2;
    const int elementSize = sizeof(QLowEnergyHandle) + uuidSize;
    const auto elemWriter = [](const Attribute &attr, char *&data) {
        putDataAndIncrement(attr.handle, data);
        putDataAndIncrement(attr.type, data);
    };
    sendListResponse(responsePrefix, elementSize, results, elemWriter);

}

void QLowEnergyControllerPrivate::handleFindByTypeValueRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.3.3-4

    if (!checkPacketSize(packet, 7, mtuSize))
        return;
    const QLowEnergyHandle startingHandle = bt_get_le16(packet.constData() + 1);
    const QLowEnergyHandle endingHandle = bt_get_le16(packet.constData() + 3);
    const quint16 type = bt_get_le16(packet.constData() + 5);
    const QByteArray value = QByteArray::fromRawData(packet.constData() + 7, packet.count() - 7);
    qCDebug(QT_BT_BLUEZ) << "client sends find by type value request; start:" << startingHandle
                         << "end:" << endingHandle << "type:" << type
                         << "value:" << value.toHex();
    if (!checkHandlePair(packet.at(0), startingHandle, endingHandle))
        return;

    const auto predicate = [value, this, type](const Attribute &attr) {
        return attr.type == QBluetoothUuid(type) && attr.value == value
                && checkReadPermissions(attr) == 0;
    };
    const QVector<Attribute> results = getAttributes(startingHandle, endingHandle, predicate);
    if (results.isEmpty()) {
        sendErrorResponse(packet.at(0), startingHandle, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
        return;
    }

    QByteArray responsePrefix(1, ATT_OP_FIND_BY_TYPE_VALUE_RESPONSE);
    const int elemSize = 2 * sizeof(QLowEnergyHandle);
    const auto elemWriter = [](const Attribute &attr, char *&data) {
        putDataAndIncrement(attr.handle, data);
        putDataAndIncrement(attr.groupEndHandle, data);
    };
    sendListResponse(responsePrefix, elemSize, results, elemWriter);
}

void QLowEnergyControllerPrivate::handleReadByTypeRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.4.1-2

    if (!checkPacketSize(packet, 7, 21))
        return;
    const QLowEnergyHandle startingHandle = bt_get_le16(packet.constData() + 1);
    const QLowEnergyHandle endingHandle = bt_get_le16(packet.constData() + 3);
    const void * const typeStart = packet.constData() + 5;
    const bool is16BitUuid = packet.count() == 7;
    const bool is128BitUuid = packet.count() == 21;
    QBluetoothUuid type;
    if (is16BitUuid) {
        type = QBluetoothUuid(bt_get_le16(typeStart));
    } else if (is128BitUuid) {
        type = QBluetoothUuid(convert_uuid128(reinterpret_cast<const quint128 *>(typeStart)));
    } else {
        qCWarning(QT_BT_BLUEZ) << "read by type request has invalid packet size" << packet.count();
        sendErrorResponse(packet.at(0), 0, ATT_ERROR_INVALID_PDU);
        return;
    }
    qCDebug(QT_BT_BLUEZ) << "client sends read by type request, start:" << startingHandle
                         << "end:" << endingHandle << "type:" << type;
    if (!checkHandlePair(packet.at(0), startingHandle, endingHandle))
        return;

    // Get all attributes with matching type.
    QVector<Attribute> results = getAttributes(startingHandle, endingHandle,
        [type](const Attribute &attr) { return attr.type == type; });
    ensureUniformValueSizes(results);

    if (results.isEmpty()) {
        sendErrorResponse(packet.at(0), startingHandle, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
        return;
    }

    const int error = checkReadPermissions(results);
    if (error) {
        sendErrorResponse(packet.at(0), results.first().handle, error);
        return;
    }

    const int elementSize = sizeof(QLowEnergyHandle) + results.first().value.count();
    QByteArray responsePrefix(2, Qt::Uninitialized);
    responsePrefix[0] = ATT_OP_READ_BY_TYPE_RESPONSE;
    responsePrefix[1] = elementSize;
    const auto elemWriter = [](const Attribute &attr, char *&data) {
        putDataAndIncrement(attr.handle, data);
        putDataAndIncrement(attr.value, data);
    };
    sendListResponse(responsePrefix, elementSize, results, elemWriter);
}

void QLowEnergyControllerPrivate::handleReadRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.4.3-4

    if (!checkPacketSize(packet, 3))
        return;
    const QLowEnergyHandle handle = bt_get_le16(packet.constData() + 1);
    qCDebug(QT_BT_BLUEZ) << "client sends read request; handle:" << handle;

    if (!checkHandle(packet, handle))
        return;
    const Attribute &attribute = localAttributes.at(handle);
    const int permissionsError = checkReadPermissions(attribute);
    if (permissionsError) {
        sendErrorResponse(packet.at(0), handle, permissionsError);
        return;
    }

    const int sentValueLength = qMin(attribute.value.count(), mtuSize - 1);
    QByteArray response(1 + sentValueLength, Qt::Uninitialized);
    response[0] = ATT_OP_READ_RESPONSE;
    using namespace std;
    memcpy(response.data() + 1, attribute.value.constData(), sentValueLength);
    qCDebug(QT_BT_BLUEZ) << "sending response:" << response.toHex();
    sendPacket(response);
}

void QLowEnergyControllerPrivate::handleReadBlobRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.4.5-6

    if (!checkPacketSize(packet, 5))
        return;
    const QLowEnergyHandle handle = bt_get_le16(packet.constData() + 1);
    const quint16 valueOffset = bt_get_le16(packet.constData() + 3);
    qCDebug(QT_BT_BLUEZ) << "client sends read blob request; handle:" << handle
                         << "offset:" << valueOffset;

    if (!checkHandle(packet, handle))
        return;
    const Attribute &attribute = localAttributes.at(handle);
    const int permissionsError = checkReadPermissions(attribute);
    if (permissionsError) {
        sendErrorResponse(packet.at(0), handle, permissionsError);
        return;
    }
    if (valueOffset > attribute.value.count()) {
        sendErrorResponse(packet.at(0), handle, ATT_ERROR_INVALID_OFFSET);
        return;
    }
    if (attribute.value.count() <= mtuSize - 3) {
        sendErrorResponse(packet.at(0), handle, ATT_ERROR_ATTRIBUTE_NOT_LONG);
        return;
    }

    // Yes, this value can be zero.
    const int sentValueLength = qMin(attribute.value.count() - valueOffset, mtuSize - 1);

    QByteArray response(1 + sentValueLength, Qt::Uninitialized);
    response[0] = ATT_OP_READ_BLOB_RESPONSE;
    using namespace std;
    memcpy(response.data() + 1, attribute.value.constData() + valueOffset, sentValueLength);
    qCDebug(QT_BT_BLUEZ) << "sending response:" << response.toHex();
    sendPacket(response);
}

void QLowEnergyControllerPrivate::handleReadMultipleRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.4.7-8

    if (!checkPacketSize(packet, 5, mtuSize))
        return;
    QVector<QLowEnergyHandle> handles((packet.count() - 1) / sizeof(QLowEnergyHandle));
    auto *packetPtr = reinterpret_cast<const QLowEnergyHandle *>(packet.constData() + 1);
    for (int i = 0; i < handles.count(); ++i, ++packetPtr)
        handles[i] = bt_get_le16(packetPtr);
    qCDebug(QT_BT_BLUEZ) << "client sends read multiple request for handles" << handles;

    const auto it = std::find_if(handles.constBegin(), handles.constEnd(),
            [this](QLowEnergyHandle handle) { return handle >= lastLocalHandle; });
    if (it != handles.constEnd()) {
        sendErrorResponse(packet.at(0), *it, ATT_ERROR_INVALID_HANDLE);
        return;
    }
    const QVector<Attribute> results = getAttributes(handles.first(), handles.last());
    QByteArray response(1, ATT_OP_READ_MULTIPLE_RESPONSE);
    foreach (const Attribute &attr, results) {
        const int error = checkReadPermissions(attr);
        if (error) {
            sendErrorResponse(packet.at(0), attr.handle, error);
            return;
        }

        // Note: We do not abort if no more values fit into the packet, because we still have to
        //       report possible permission errors for the other handles.
        response += attr.value.left(mtuSize - response.count());
    }

    qCDebug(QT_BT_BLUEZ) << "sending response:" << response.toHex();
    sendPacket(response);
}

void QLowEnergyControllerPrivate::handleReadByGroupTypeRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.4.9-10

    if (!checkPacketSize(packet, 7, 21))
        return;
    const QLowEnergyHandle startingHandle = bt_get_le16(packet.constData() + 1);
    const QLowEnergyHandle endingHandle = bt_get_le16(packet.constData() + 3);
    const bool is16BitUuid = packet.count() == 7;
    const bool is128BitUuid = packet.count() == 21;
    const void * const typeStart = packet.constData() + 5;
    QBluetoothUuid type;
    if (is16BitUuid) {
        type = QBluetoothUuid(bt_get_le16(typeStart));
    } else if (is128BitUuid) {
        type = QBluetoothUuid(convert_uuid128(reinterpret_cast<const quint128 *>(typeStart)));
    } else {
        qCWarning(QT_BT_BLUEZ) << "read by group type request has invalid packet size"
                               << packet.count();
        sendErrorResponse(packet.at(0), 0, ATT_ERROR_INVALID_PDU);
        return;
    }
    qCDebug(QT_BT_BLUEZ) << "client sends read by group type request, start:" << startingHandle
                         << "end:" << endingHandle << "type:" << type;

    if (!checkHandlePair(packet.at(0), startingHandle, endingHandle))
        return;
    if (type != QBluetoothUuid(static_cast<quint16>(GATT_PRIMARY_SERVICE))
            && type != QBluetoothUuid(static_cast<quint16>(GATT_SECONDARY_SERVICE))) {
        sendErrorResponse(packet.at(0), startingHandle, ATT_ERROR_UNSUPPRTED_GROUP_TYPE);
        return;
    }

    QVector<Attribute> results = getAttributes(startingHandle, endingHandle,
            [type](const Attribute &attr) { return attr.type == type; });
    if (results.isEmpty()) {
        sendErrorResponse(packet.at(0), startingHandle, ATT_ERROR_ATTRIBUTE_NOT_FOUND);
        return;
    }
    const int error = checkReadPermissions(results);
    if (error) {
        sendErrorResponse(packet.at(0), results.first().handle, error);
        return;
    }

    ensureUniformValueSizes(results);

    const int elementSize = 2 * sizeof(QLowEnergyHandle) + results.first().value.count();
    QByteArray responsePrefix(2, Qt::Uninitialized);
    responsePrefix[0] = ATT_OP_READ_BY_GROUP_RESPONSE;
    responsePrefix[1] = elementSize;
    const auto elemWriter = [](const Attribute &attr, char *&data) {
        putDataAndIncrement(attr.handle, data);
        putDataAndIncrement(attr.groupEndHandle, data);
        putDataAndIncrement(attr.value, data);
    };
    sendListResponse(responsePrefix, elementSize, results, elemWriter);
}

void QLowEnergyControllerPrivate::updateLocalAttributeValue(
        QLowEnergyHandle handle,
        const QByteArray &value,
        QLowEnergyCharacteristic &characteristic,
        QLowEnergyDescriptor &descriptor)
{
    localAttributes[handle].value = value;
    foreach (const auto &service, localServices) {
        if (handle < service->startHandle || handle > service->endHandle)
            continue;
        for (auto charIt = service->characteristicList.begin();
             charIt != service->characteristicList.end(); ++charIt) {
            QLowEnergyServicePrivate::CharData &charData = charIt.value();
            if (handle == charIt.key() + 1) { // Char value decl comes right after char decl.
                charData.value = value;
                characteristic = QLowEnergyCharacteristic(service, charIt.key());
                return;
            }
            for (auto descIt = charData.descriptorList.begin();
                 descIt != charData.descriptorList.end(); ++descIt) {
                if (handle == descIt.key()) {
                    descIt.value().value = value;
                    descriptor = QLowEnergyDescriptor(service, charIt.key(), handle);
                    return;
                }
            }
        }
    }
    qFatal("local services map inconsistent with local attribute map");
}

static bool isNotificationEnabled(quint16 clientConfigValue) { return clientConfigValue & 0x1; }
static bool isIndicationEnabled(quint16 clientConfigValue) { return clientConfigValue & 0x2; }

void QLowEnergyControllerPrivate::writeCharacteristicForPeripheral(
        QLowEnergyServicePrivate::CharData &charData,
        const QByteArray &newValue)
{
    const QLowEnergyHandle valueHandle = charData.valueHandle;
    Q_ASSERT(valueHandle <= lastLocalHandle);
    Attribute &attribute = localAttributes[valueHandle];
    if (newValue.count() < attribute.minLength || newValue.count() > attribute.maxLength) {
        qCWarning(QT_BT_BLUEZ) << "ignoring value of invalid length" << newValue.count()
                               << "for attribute" << valueHandle;
        return;
    }
    attribute.value = newValue;
    charData.value = newValue;
    const bool hasNotifyProperty = attribute.properties & QLowEnergyCharacteristic::Notify;
    const bool hasIndicateProperty
            = attribute.properties & QLowEnergyCharacteristic::Indicate;
    if (!hasNotifyProperty && !hasIndicateProperty)
        return;
    foreach (const QLowEnergyServicePrivate::DescData &desc, charData.descriptorList) {
        if (desc.uuid != QBluetoothUuid::ClientCharacteristicConfiguration)
            continue;

        // Notify/indicate currently connected client.
        const bool isConnected = state == QLowEnergyController::ConnectedState;
        if (isConnected) {
            Q_ASSERT(desc.value.count() == 2);
            quint16 configValue = bt_get_le16(desc.value.constData());
            if (isNotificationEnabled(configValue) && hasNotifyProperty) {
                sendNotification(valueHandle);
            } else if (isIndicationEnabled(configValue) && hasIndicateProperty) {
                if (indicationInFlight)
                    scheduledIndications << valueHandle;
                else
                    sendIndication(valueHandle);
            }
        }

        // Prepare notification/indication of unconnected, bonded clients.
        for (auto it = clientConfigData.begin(); it != clientConfigData.end(); ++it) {
            if (isConnected && it.key() == remoteDevice.toUInt64())
                continue;
            QVector<ClientConfigurationData> &configDataList = it.value();
            for (ClientConfigurationData &configData : configDataList) {
                if (configData.charValueHandle != valueHandle)
                    continue;
                if ((isNotificationEnabled(configData.configValue) && hasNotifyProperty)
                        || (isIndicationEnabled(configData.configValue) && hasIndicateProperty)) {
                    configData.charValueWasUpdated = true;
                    break;
                }
            }
        }
        break;
    }
}

void QLowEnergyControllerPrivate::writeCharacteristicForCentral(const QSharedPointer<QLowEnergyServicePrivate> &service,
        QLowEnergyHandle charHandle,
        QLowEnergyHandle valueHandle,
        const QByteArray &newValue,
        QLowEnergyService::WriteMode mode)
{
    QByteArray packet(WRITE_REQUEST_HEADER_SIZE + newValue.count(), Qt::Uninitialized);
    putBtData(valueHandle, packet.data() + 1);
    memcpy(packet.data() + 3, newValue.constData(), newValue.count());
    bool writeWithResponse = false;
    switch (mode) {
    case QLowEnergyService::WriteWithResponse:
        if (newValue.size() > (mtuSize - WRITE_REQUEST_HEADER_SIZE)) {
            sendNextPrepareWriteRequest(charHandle, newValue, 0);
            sendNextPendingRequest();
            return;
        }
        // write value fits into single package
        packet[0] = ATT_OP_WRITE_REQUEST;
        writeWithResponse = true;
        break;
    case QLowEnergyService::WriteWithoutResponse:
        packet[0] = ATT_OP_WRITE_COMMAND;
        break;
    case QLowEnergyService::WriteSigned:
        packet[0] = ATT_OP_SIGNED_WRITE_COMMAND;
        if (!isBonded()) {
            qCWarning(QT_BT_BLUEZ) << "signed write not possible: requires bond between devices";
            service->setError(QLowEnergyService::CharacteristicWriteError);
            return;
        }
        if (securityLevel() >= BT_SECURITY_MEDIUM) {
            qCWarning(QT_BT_BLUEZ) << "signed write not possible: not allowed on encrypted link";
            service->setError(QLowEnergyService::CharacteristicWriteError);
            return;
        }
        const auto signingDataIt = signingData.find(remoteDevice.toUInt64());
        if (signingDataIt == signingData.end()) {
            qCWarning(QT_BT_BLUEZ) << "signed write not possible: no signature key found";
            service->setError(QLowEnergyService::CharacteristicWriteError);
            return;
        }
        ++signingDataIt.value().counter;
        packet = LeCmacCalculator::createFullMessage(packet, signingDataIt.value().counter);
        const quint64 mac = LeCmacCalculator().calculateMac(packet, signingDataIt.value().key);
        packet.resize(packet.count() + sizeof mac);
        putBtData(mac, packet.data() + packet.count() - sizeof mac);
        storeSignCounter(LocalSigningKey);
        break;
    }

    qCDebug(QT_BT_BLUEZ) << "Writing characteristic" << hex << charHandle
                         << "(size:" << packet.count() << "with response:"
                         << (mode == QLowEnergyService::WriteWithResponse)
                         << "signed:" << (mode == QLowEnergyService::WriteSigned) << ")";

    // Advantage of write without response is the quick turnaround.
    // It can be sent at any time and does not produce responses.
    // Therefore we will not put them into the openRequest queue at all.
    if (!writeWithResponse) {
        sendPacket(packet);
        return;
    }

    Request request;
    request.payload = packet;
    request.command = ATT_OP_WRITE_REQUEST;
    request.reference = charHandle;
    request.reference2 = newValue;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::writeDescriptorForPeripheral(
        const QSharedPointer<QLowEnergyServicePrivate> &service,
        const QLowEnergyHandle charHandle,
        const QLowEnergyHandle descriptorHandle,
        const QByteArray &newValue)
{
    Q_ASSERT(descriptorHandle <= lastLocalHandle);
    Attribute &attribute = localAttributes[descriptorHandle];
    if (newValue.count() < attribute.minLength || newValue.count() > attribute.maxLength) {
        qCWarning(QT_BT_BLUEZ) << "invalid value of size" << newValue.count()
                               << "for attribute" << descriptorHandle;
        return;
    }
    attribute.value = newValue;
    service->characteristicList[charHandle].descriptorList[descriptorHandle].value = newValue;
}

void QLowEnergyControllerPrivate::writeDescriptorForCentral(
        const QLowEnergyHandle charHandle,
        const QLowEnergyHandle descriptorHandle,
        const QByteArray &newValue)
{
    if (newValue.size() > (mtuSize - WRITE_REQUEST_HEADER_SIZE)) {
        sendNextPrepareWriteRequest(descriptorHandle, newValue, 0);
        sendNextPendingRequest();
        return;
    }

    quint8 packet[WRITE_REQUEST_HEADER_SIZE];
    packet[0] = ATT_OP_WRITE_REQUEST;
    putBtData(descriptorHandle, &packet[1]);

    const int size = WRITE_REQUEST_HEADER_SIZE + newValue.size();
    QByteArray data(size, Qt::Uninitialized);
    memcpy(data.data(), packet, WRITE_REQUEST_HEADER_SIZE);
    memcpy(&(data.data()[WRITE_REQUEST_HEADER_SIZE]), newValue.constData(), newValue.size());

    qCDebug(QT_BT_BLUEZ) << "Writing descriptor" << hex << descriptorHandle
                         << "(size:" << size << ")";

    Request request;
    request.payload = data;
    request.command = ATT_OP_WRITE_REQUEST;
    request.reference = (charHandle | (descriptorHandle << 16));
    request.reference2 = newValue;
    openRequests.enqueue(request);

    sendNextPendingRequest();
}

void QLowEnergyControllerPrivate::handleWriteRequestOrCommand(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.5.1-3

    const bool isRequest = packet.at(0) == ATT_OP_WRITE_REQUEST;
    const bool isSigned = quint8(packet.at(0)) == quint8(ATT_OP_SIGNED_WRITE_COMMAND);
    if (!checkPacketSize(packet, isSigned ? 15 : 3, mtuSize))
        return;
    const QLowEnergyHandle handle = bt_get_le16(packet.constData() + 1);
    qCDebug(QT_BT_BLUEZ) << "client sends" << (isSigned ? "signed" : "") << "write"
                         << (isRequest ? "request" : "command") << "for handle" << handle;

    if (!checkHandle(packet, handle))
        return;

    Attribute &attribute = localAttributes[handle];
    const QLowEnergyCharacteristic::PropertyType type = isRequest
            ? QLowEnergyCharacteristic::Write : isSigned
              ? QLowEnergyCharacteristic::WriteSigned : QLowEnergyCharacteristic::WriteNoResponse;
    const int permissionsError = checkPermissions(attribute, type);
    if (permissionsError) {
        sendErrorResponse(packet.at(0), handle, permissionsError);
        return;
    }

    int valueLength;
    if (isSigned) {
        if (!isBonded()) {
            qCWarning(QT_BT_BLUEZ) << "Ignoring signed write from non-bonded device.";
            return;
        }
        if (securityLevel() >= BT_SECURITY_MEDIUM) {
            qCWarning(QT_BT_BLUEZ) << "Ignoring signed write on encrypted link.";
            return;
        }
        const auto signingDataIt = signingData.find(remoteDevice.toUInt64());
        if (signingDataIt == signingData.constEnd()) {
            qCWarning(QT_BT_BLUEZ) << "No CSRK found for peer device, ignoring signed write";
            return;
        }

        const quint32 signCounter = getBtData<quint32>(packet.data() + packet.count() - 12);
        if (signCounter < signingDataIt.value().counter + 1) {
            qCWarning(QT_BT_BLUEZ) << "Client's' sign counter" << signCounter
                                   << "not greater than local sign counter"
                                   << signingDataIt.value().counter
                                   << "; ignoring signed write command.";
            return;
        }

        const quint64 macFromClient = getBtData<quint64>(packet.data() + packet.count() - 8);
        const bool signatureCorrect = verifyMac(packet.left(packet.count() - 12),
                signingDataIt.value().key, signCounter, macFromClient);
        if (!signatureCorrect) {
            qCWarning(QT_BT_BLUEZ) << "Signed Write packet has wrong signature, disconnecting";
            disconnectFromDevice(); // Recommended by spec v4.2, Vol 3, part C, 10.4.2
            return;
        }

        signingDataIt.value().counter = signCounter;
        storeSignCounter(RemoteSigningKey);
        valueLength = packet.count() - 15;
    } else {
        valueLength = packet.count() - 3;
    }

    if (valueLength > attribute.maxLength) {
        sendErrorResponse(packet.at(0), handle, ATT_ERROR_INVAL_ATTR_VALUE_LEN);
        return;
    }

    // If the attribute value has a fixed size and the value in the packet is shorter,
    // then we overwrite only the start of the attribute value and keep the rest.
    QByteArray value = packet.mid(3, valueLength);
    if (attribute.minLength == attribute.maxLength && valueLength < attribute.minLength)
        value += attribute.value.mid(valueLength, attribute.maxLength - valueLength);

    QLowEnergyCharacteristic characteristic;
    QLowEnergyDescriptor descriptor;
    updateLocalAttributeValue(handle, value, characteristic, descriptor);

    if (isRequest) {
        const QByteArray response = QByteArray(1, ATT_OP_WRITE_RESPONSE);
        sendPacket(response);
    }

    if (characteristic.isValid()) {
        emit characteristic.d_ptr->characteristicChanged(characteristic, value);
    } else {
        Q_ASSERT(descriptor.isValid());
        emit descriptor.d_ptr->descriptorWritten(descriptor, value);
    }
}

void QLowEnergyControllerPrivate::handlePrepareWriteRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.6.1

    if (!checkPacketSize(packet, 5, mtuSize))
        return;
    const quint16 handle = bt_get_le16(packet.constData() + 1);
    qCDebug(QT_BT_BLUEZ) << "client sends prepare write request for handle" << handle;

    if (!checkHandle(packet, handle))
        return;
    const Attribute &attribute = localAttributes.at(handle);
    const int permissionsError = checkPermissions(attribute, QLowEnergyCharacteristic::Write);
    if (permissionsError) {
        sendErrorResponse(packet.at(0), handle, permissionsError);
        return;
    }
    if (openPrepareWriteRequests.count() >= maxPrepareQueueSize) {
        sendErrorResponse(packet.at(0), handle, ATT_ERROR_PREPARE_QUEUE_FULL);
        return;
    }

    // The value is not checked here, but on the Execute request.
    openPrepareWriteRequests << WriteRequest(handle, bt_get_le16(packet.constData() + 3),
                                                    packet.mid(5));

    QByteArray response = packet;
    response[0] = ATT_OP_PREPARE_WRITE_RESPONSE;
    sendPacket(response);
}

void QLowEnergyControllerPrivate::handleExecuteWriteRequest(const QByteArray &packet)
{
    // Spec v4.2, Vol 3, Part F, 3.4.6.3

    if (!checkPacketSize(packet, 2))
        return;
    const bool cancel = packet.at(1) == 0;
    qCDebug(QT_BT_BLUEZ) << "client sends execute write request; flag is"
                         << (cancel ? "cancel" : "flush");

    QVector<WriteRequest> requests = openPrepareWriteRequests;
    openPrepareWriteRequests.clear();
    QVector<QLowEnergyCharacteristic> characteristics;
    QVector<QLowEnergyDescriptor> descriptors;
    if (!cancel) {
        foreach (const WriteRequest &request, requests) {
            Attribute &attribute = localAttributes[request.handle];
            if (request.valueOffset > attribute.value.count()) {
                sendErrorResponse(packet.at(0), request.handle, ATT_ERROR_INVALID_OFFSET);
                return;
            }
            const QByteArray newValue = attribute.value.left(request.valueOffset) + request.value;
            if (newValue.count() > attribute.maxLength) {
                sendErrorResponse(packet.at(0), request.handle, ATT_ERROR_INVAL_ATTR_VALUE_LEN);
                return;
            }
            QLowEnergyCharacteristic characteristic;
            QLowEnergyDescriptor descriptor;
            // TODO: Redundant attribute lookup for the case of the same handle appearing
            //       more than once.
            updateLocalAttributeValue(request.handle, newValue, characteristic, descriptor);
            if (characteristic.isValid()) {
                characteristics << characteristic;
            } else if (descriptor.isValid()) {
                Q_ASSERT(descriptor.isValid());
                descriptors << descriptor;
            }
        }
    }

    sendPacket(QByteArray(1, ATT_OP_EXECUTE_WRITE_RESPONSE));

    foreach (const QLowEnergyCharacteristic &characteristic, characteristics)
        emit characteristic.d_ptr->characteristicChanged(characteristic, characteristic.value());
    foreach (const QLowEnergyDescriptor &descriptor, descriptors)
        emit descriptor.d_ptr->descriptorWritten(descriptor, descriptor.value());
}

void QLowEnergyControllerPrivate::sendErrorResponse(quint8 request, quint16 handle, quint8 code)
{
    // An ATT command never receives an error response.
    if (request == ATT_OP_WRITE_COMMAND || request == ATT_OP_SIGNED_WRITE_COMMAND)
        return;

    QByteArray packet(ERROR_RESPONSE_HEADER_SIZE, Qt::Uninitialized);
    packet[0] = ATT_OP_ERROR_RESPONSE;
    packet[1] = request;
    putBtData(handle, packet.data() + 2);
    packet[4] = code;
    qCWarning(QT_BT_BLUEZ) << "sending error response; request:" << request << "handle:" << handle
                << "code:" << code;
    sendPacket(packet);
}

void QLowEnergyControllerPrivate::sendListResponse(const QByteArray &packetStart, int elemSize,
        const QVector<Attribute> &attributes, const ElemWriter &elemWriter)
{
    const int offset = packetStart.count();
    const int elemCount = qMin(attributes.count(), (mtuSize - offset) / elemSize);
    const int totalPacketSize = offset + elemCount * elemSize;
    QByteArray response(totalPacketSize, Qt::Uninitialized);
    using namespace std;
    memcpy(response.data(), packetStart.constData(), offset);
    char *data = response.data() + offset;
    for_each(attributes.constBegin(), attributes.constBegin() + elemCount,
             [&data, elemWriter](const Attribute &attr) { elemWriter(attr, data); });
    qCDebug(QT_BT_BLUEZ) << "sending response:" << response.toHex();
    sendPacket(response);
}

void QLowEnergyControllerPrivate::sendNotification(QLowEnergyHandle handle)
{
    sendNotificationOrIndication(ATT_OP_HANDLE_VAL_NOTIFICATION, handle);
}

void QLowEnergyControllerPrivate::sendIndication(QLowEnergyHandle handle)
{
    Q_ASSERT(!indicationInFlight);
    indicationInFlight = true;
    sendNotificationOrIndication(ATT_OP_HANDLE_VAL_INDICATION, handle);
}

void QLowEnergyControllerPrivate::sendNotificationOrIndication(
        quint8 opCode,
        QLowEnergyHandle handle)
{
    Q_ASSERT(handle <= lastLocalHandle);
    const Attribute &attribute = localAttributes.at(handle);
    const int maxValueLength = qMin(attribute.value.count(), mtuSize - 3);
    QByteArray packet(3 + maxValueLength, Qt::Uninitialized);
    packet[0] = opCode;
    putBtData(handle, packet.data() + 1);
    using namespace std;
    memcpy(packet.data() + 3, attribute.value.constData(), maxValueLength);
    qCDebug(QT_BT_BLUEZ) << "sending notification/indication:" << packet.toHex();
    sendPacket(packet);
}

void QLowEnergyControllerPrivate::sendNextIndication()
{
    if (!scheduledIndications.isEmpty())
        sendIndication(scheduledIndications.takeFirst());
}

void QLowEnergyControllerPrivate::handleConnectionRequest()
{
    if (state != QLowEnergyController::AdvertisingState) {
        qCWarning(QT_BT_BLUEZ) << "Incoming connection request in unexpected state" << state;
        return;
    }
    Q_ASSERT(serverSocketNotifier);
    serverSocketNotifier->setEnabled(false);
    sockaddr_l2 clientAddr;
    socklen_t clientAddrSize = sizeof clientAddr;
    const int clientSocket = accept(serverSocketNotifier->socket(),
                                    reinterpret_cast<sockaddr *>(&clientAddr), &clientAddrSize);
    if (clientSocket == -1) {
        // Not fatal in itself. The next one might succeed.
        qCWarning(QT_BT_BLUEZ) << "accept() failed:" << qt_error_string(errno);
        serverSocketNotifier->setEnabled(true);
        return;
    }
    remoteDevice = QBluetoothAddress(convertAddress(clientAddr.l2_bdaddr.b));
    qCDebug(QT_BT_BLUEZ) << "GATT connection from device" << remoteDevice;
    if (connectionHandle == 0)
        qCWarning(QT_BT_BLUEZ) << "Received client connection, but no connection complete event";

    closeServerSocket();
    l2cpSocket = new QBluetoothSocket(QBluetoothServiceInfo::L2capProtocol, this);
    connect(l2cpSocket, &QBluetoothSocket::disconnected,
            this, &QLowEnergyControllerPrivate::l2cpDisconnected);
    connect(l2cpSocket, static_cast<void (QBluetoothSocket::*)(QBluetoothSocket::SocketError)>
            (&QBluetoothSocket::error), this, &QLowEnergyControllerPrivate::l2cpErrorChanged);
    connect(l2cpSocket, &QIODevice::readyRead, this, &QLowEnergyControllerPrivate::l2cpReadyRead);
    l2cpSocket->d_ptr->lowEnergySocketType = addressType == QLowEnergyController::PublicAddress
            ? BDADDR_LE_PUBLIC : BDADDR_LE_RANDOM;
    l2cpSocket->setSocketDescriptor(clientSocket, QBluetoothServiceInfo::L2capProtocol,
            QBluetoothSocket::ConnectedState, QIODevice::ReadWrite | QIODevice::Unbuffered);
    restoreClientConfigurations();
    loadSigningDataIfNecessary(RemoteSigningKey);

    Q_Q(QLowEnergyController);
    setState(QLowEnergyController::ConnectedState);
    emit q->connected();
}

void QLowEnergyControllerPrivate::closeServerSocket()
{
    if (!serverSocketNotifier)
        return;
    serverSocketNotifier->disconnect();
    close(serverSocketNotifier->socket());
    serverSocketNotifier->deleteLater();
    serverSocketNotifier = nullptr;
}

bool QLowEnergyControllerPrivate::isBonded() const
{
    // Pairing does not necessarily imply bonding, but we don't know whether the
    // bonding flag was set in the original pairing request.
    return QBluetoothLocalDevice(localAdapter).pairingStatus(remoteDevice)
            != QBluetoothLocalDevice::Unpaired;
}

QVector<QLowEnergyControllerPrivate::TempClientConfigurationData> QLowEnergyControllerPrivate::gatherClientConfigData()
{
    QVector<TempClientConfigurationData> data;
    foreach (const auto &service, localServices) {
        for (auto charIt = service->characteristicList.begin();
             charIt != service->characteristicList.end(); ++charIt) {
            QLowEnergyServicePrivate::CharData &charData = charIt.value();
            for (auto descIt = charData.descriptorList.begin();
                 descIt != charData.descriptorList.end(); ++descIt) {
                QLowEnergyServicePrivate::DescData &descData = descIt.value();
                if (descData.uuid == QBluetoothUuid::ClientCharacteristicConfiguration) {
                    data << TempClientConfigurationData(&descData, charData.valueHandle,
                                                        descIt.key());
                    break;
                }
            }
        }
    }
    return data;
}

void QLowEnergyControllerPrivate::storeClientConfigurations()
{
    if (!isBonded()) {
        clientConfigData.remove(remoteDevice.toUInt64());
        return;
    }
    QVector<ClientConfigurationData> clientConfigs;
    const QVector<TempClientConfigurationData> &tempConfigList = gatherClientConfigData();
    foreach (const auto &tempConfigData, tempConfigList) {
        Q_ASSERT(tempConfigData.descData->value.count() == 2);
        const quint16 value = bt_get_le16(tempConfigData.descData->value.constData());
        if (value != 0) {
            clientConfigs << ClientConfigurationData(tempConfigData.charValueHandle,
                                                     tempConfigData.configHandle, value);
        }
    }
    clientConfigData.insert(remoteDevice.toUInt64(), clientConfigs);
}

void QLowEnergyControllerPrivate::restoreClientConfigurations()
{
    const QVector<TempClientConfigurationData> &tempConfigList = gatherClientConfigData();
    const QVector<ClientConfigurationData> &restoredClientConfigs = isBonded()
            ? clientConfigData.value(remoteDevice.toUInt64()) : QVector<ClientConfigurationData>();
    QVector<QLowEnergyHandle> notifications;
    foreach (const auto &tempConfigData, tempConfigList) {
        bool wasRestored = false;
        foreach (const auto &restoredData, restoredClientConfigs) {
            if (restoredData.charValueHandle == tempConfigData.charValueHandle) {
                Q_ASSERT(tempConfigData.descData->value.count() == 2);
                putBtData(restoredData.configValue, tempConfigData.descData->value.data());
                wasRestored = true;
                if (restoredData.charValueWasUpdated) {
                    if (isNotificationEnabled(restoredData.configValue))
                        notifications << restoredData.charValueHandle;
                    else if (isIndicationEnabled(restoredData.configValue))
                        scheduledIndications << restoredData.charValueHandle;
                }
                break;
            }
        }
        if (!wasRestored)
            tempConfigData.descData->value = QByteArray(2, 0); // Default value.
        Q_ASSERT(lastLocalHandle >= tempConfigData.configHandle);
        Q_ASSERT(tempConfigData.configHandle > tempConfigData.charValueHandle);
        localAttributes[tempConfigData.configHandle].value = tempConfigData.descData->value;
    }

    foreach (const QLowEnergyHandle handle, notifications)
        sendNotification(handle);
    sendNextIndication();
}

void QLowEnergyControllerPrivate::loadSigningDataIfNecessary(SigningKeyType keyType)
{
    const auto signingDataIt = signingData.constFind(remoteDevice.toUInt64());
    if (signingDataIt != signingData.constEnd())
        return; // We are up to date for this device.
    const QString settingsFilePath = keySettingsFilePath();
    if (!QFileInfo(settingsFilePath).exists()) {
        qCDebug(QT_BT_BLUEZ) << "No settings found for peer device.";
        return;
    }
    QSettings settings(settingsFilePath, QSettings::IniFormat);
    const QString group = signingKeySettingsGroup(keyType);
    settings.beginGroup(group);
    const QByteArray keyString = settings.value(QLatin1String("Key")).toByteArray();
    if (keyString.isEmpty()) {
        qCDebug(QT_BT_BLUEZ) << "Group" << group << "not found in settings file";
        return;
    }
    const QByteArray keyData = QByteArray::fromHex(keyString);
    if (keyData.count() != int(sizeof(quint128))) {
        qCWarning(QT_BT_BLUEZ) << "Signing key in settings file has invalid size"
                               << keyString.count();
        return;
    }
    qCDebug(QT_BT_BLUEZ) << "CSRK of peer device is" << keyString;
    const quint32 counter = settings.value(QLatin1String("Counter"), 0).toUInt();
    quint128 csrk;
    using namespace std;
    memcpy(csrk.data, keyData.constData(), keyData.count());
    signingData.insert(remoteDevice.toUInt64(), SigningData(csrk, counter - 1));
}

void QLowEnergyControllerPrivate::storeSignCounter(SigningKeyType keyType) const
{
    const auto signingDataIt = signingData.constFind(remoteDevice.toUInt64());
    if (signingDataIt == signingData.constEnd())
        return;
    const QString settingsFilePath = keySettingsFilePath();
    if (!QFileInfo(settingsFilePath).exists())
        return;
    QSettings settings(settingsFilePath, QSettings::IniFormat);
    if (!settings.isWritable())
        return;
    settings.beginGroup(signingKeySettingsGroup(keyType));
    const QString counterKey = QLatin1String("Counter");
    if (!settings.allKeys().contains(counterKey))
        return;
    const quint32 counterValue = signingDataIt.value().counter + 1;
    if (counterValue == settings.value(counterKey).toUInt())
        return;
    settings.setValue(counterKey, counterValue);
}

QString QLowEnergyControllerPrivate::signingKeySettingsGroup(SigningKeyType keyType) const
{
    return QLatin1String(keyType == LocalSigningKey ? "LocalSignatureKey" : "RemoteSignatureKey");
}

QString QLowEnergyControllerPrivate::keySettingsFilePath() const
{
    return QString::fromLatin1("/var/lib/bluetooth/%1/%2/info")
            .arg(localAdapter.toString(), remoteDevice.toString());
}

static QByteArray uuidToByteArray(const QBluetoothUuid &uuid)
{
    QByteArray ba;
    if (uuid.minimumSize() == 2) {
        ba.resize(2);
        putBtData(uuid.toUInt16(), ba.data());
    } else {
        ba.resize(16);
        quint128 hostOrder;
        quint128 qtUuidOrder = uuid.toUInt128();
        ntoh128(&qtUuidOrder, &hostOrder);
        putBtData(hostOrder, ba.data());
    }
    return ba;
}

void QLowEnergyControllerPrivate::addToGenericAttributeList(const QLowEnergyServiceData &service,
                                                            QLowEnergyHandle startHandle)
{
    // Construct generic attribute data for the service with handles as keys.
    // Otherwise a number of request handling functions will be awkward to write
    // as well as computationally inefficient.

    localAttributes.resize(lastLocalHandle + 1);
    Attribute serviceAttribute;
    serviceAttribute.handle = startHandle;
    serviceAttribute.type = QBluetoothUuid(static_cast<quint16>(service.type()));
    serviceAttribute.properties = QLowEnergyCharacteristic::Read;
    serviceAttribute.value = uuidToByteArray(service.uuid());
    QLowEnergyHandle currentHandle = startHandle;
    foreach (const QLowEnergyService * const service, service.includedServices()) {
        Attribute attribute;
        attribute.handle = ++currentHandle;
        attribute.type = QBluetoothUuid(GATT_INCLUDED_SERVICE);
        attribute.properties = QLowEnergyCharacteristic::Read;
        const bool includeUuidInValue = service->serviceUuid().minimumSize() == 2;
        attribute.value.resize((2 + includeUuidInValue) * sizeof(QLowEnergyHandle));
        char *valueData = attribute.value.data();
        putDataAndIncrement(service->d_ptr->startHandle, valueData);
        putDataAndIncrement(service->d_ptr->endHandle, valueData);
        if (includeUuidInValue)
            putDataAndIncrement(service->serviceUuid(), valueData);
        localAttributes[attribute.handle] = attribute;
    }
    foreach (const QLowEnergyCharacteristicData &cd, service.characteristics()) {
        Attribute attribute;

        // Characteristic declaration;
        attribute.handle = ++currentHandle;
        attribute.groupEndHandle = attribute.handle + 1 + cd.descriptors().count();
        attribute.type = QBluetoothUuid(GATT_CHARACTERISTIC);
        attribute.properties = QLowEnergyCharacteristic::Read;
        attribute.value.resize(1 + sizeof(QLowEnergyHandle) + cd.uuid().minimumSize());
        char *valueData = attribute.value.data();
        putDataAndIncrement(static_cast<quint8>(cd.properties()), valueData);
        putDataAndIncrement(QLowEnergyHandle(currentHandle + 1), valueData);
        putDataAndIncrement(cd.uuid(), valueData);
        localAttributes[attribute.handle] = attribute;

        // Characteristic value declaration.
        attribute.handle = ++currentHandle;
        attribute.groupEndHandle = attribute.handle;
        attribute.type = cd.uuid();
        attribute.properties = cd.properties();
        attribute.readConstraints = cd.readConstraints();
        attribute.writeConstraints = cd.writeConstraints();
        attribute.value = cd.value();
        attribute.minLength = cd.minimumValueLength();
        attribute.maxLength = cd.maximumValueLength();
        localAttributes[attribute.handle] = attribute;

        foreach (const QLowEnergyDescriptorData &dd, cd.descriptors()) {
            attribute.handle = ++currentHandle;
            attribute.groupEndHandle = attribute.handle;
            attribute.type = dd.uuid();
            attribute.properties = QLowEnergyCharacteristic::PropertyTypes();
            attribute.readConstraints = AttAccessConstraints();
            attribute.writeConstraints = AttAccessConstraints();
            attribute.minLength = 0;
            attribute.maxLength = INT_MAX;

            // Spec v4.2, Vol. 3, Part G, 3.3.3.x
            if (attribute.type == QBluetoothUuid::CharacteristicExtendedProperties) {
                attribute.properties = QLowEnergyCharacteristic::Read;
                attribute.minLength = attribute.maxLength = 2;
            } else if (attribute.type == QBluetoothUuid::CharacteristicPresentationFormat) {
                attribute.properties = QLowEnergyCharacteristic::Read;
                attribute.minLength = attribute.maxLength = 7;
            } else if (attribute.type == QBluetoothUuid::CharacteristicAggregateFormat) {
                attribute.properties = QLowEnergyCharacteristic::Read;
                attribute.minLength = 4;
            } else if (attribute.type == QBluetoothUuid::ClientCharacteristicConfiguration
                       || attribute.type == QBluetoothUuid::ServerCharacteristicConfiguration) {
                attribute.properties = QLowEnergyCharacteristic::Read
                        | QLowEnergyCharacteristic::Write
                        | QLowEnergyCharacteristic::WriteNoResponse
                        | QLowEnergyCharacteristic::WriteSigned;
                attribute.writeConstraints = dd.writeConstraints();
                attribute.minLength = attribute.maxLength = 2;
            } else {
                if (dd.isReadable())
                    attribute.properties |= QLowEnergyCharacteristic::Read;
                if (dd.isWritable()) {
                    attribute.properties |= QLowEnergyCharacteristic::Write;
                    attribute.properties |= QLowEnergyCharacteristic::WriteNoResponse;
                    attribute.properties |= QLowEnergyCharacteristic::WriteSigned;
                }
                attribute.readConstraints = dd.readConstraints();
                attribute.writeConstraints = dd.writeConstraints();
            }

            attribute.value = dd.value();
            if (attribute.value.count() < attribute.minLength
                    || attribute.value.count() > attribute.maxLength) {
                qCWarning(QT_BT_BLUEZ) << "attribute of type" << attribute.type
                                       << "has invalid length of" << attribute.value.count()
                                       << "bytes";
                attribute.value = QByteArray(attribute.minLength, 0);
            }
            localAttributes[attribute.handle] = attribute;
        }
    }
    serviceAttribute.groupEndHandle = currentHandle;
    localAttributes[serviceAttribute.handle] = serviceAttribute;
}

void QLowEnergyControllerPrivate::ensureUniformAttributes(QVector<Attribute> &attributes,
        const std::function<int (const Attribute &)> &getSize)
{
    if (attributes.isEmpty())
        return;
    const int firstSize = getSize(attributes.first());
    const auto it = std::find_if(attributes.begin() + 1, attributes.end(),
            [firstSize, getSize](const Attribute &attr) { return getSize(attr) != firstSize; });
    if (it != attributes.end())
        attributes.erase(it, attributes.end());

}

void QLowEnergyControllerPrivate::ensureUniformUuidSizes(QVector<Attribute> &attributes)
{
    ensureUniformAttributes(attributes,
                            [](const Attribute &attr) { return getUuidSize(attr.type); });
}

void QLowEnergyControllerPrivate::ensureUniformValueSizes(QVector<Attribute> &attributes)
{
    ensureUniformAttributes(attributes,
                            [](const Attribute &attr) { return attr.value.count(); });
}

QVector<QLowEnergyControllerPrivate::Attribute> QLowEnergyControllerPrivate::getAttributes(QLowEnergyHandle startHandle,
        QLowEnergyHandle endHandle, const AttributePredicate &attributePredicate)
{
    QVector<Attribute> results;
    if (startHandle > lastLocalHandle)
        return results;
    if (lastLocalHandle == 0) // We have no services at all.
        return results;
    Q_ASSERT(startHandle <= endHandle); // Must have been checked before.
    const QLowEnergyHandle firstHandle = qMin(startHandle, lastLocalHandle);
    const QLowEnergyHandle lastHandle = qMin(endHandle, lastLocalHandle);
    for (QLowEnergyHandle i = firstHandle; i <= lastHandle; ++i) {
        const Attribute &attr = localAttributes.at(i);
        if (attributePredicate(attr))
            results << attr;
    }
    return results;
}

int QLowEnergyControllerPrivate::checkPermissions(const Attribute &attr,
                                                  QLowEnergyCharacteristic::PropertyType type)
{
    const bool isReadAccess = type == QLowEnergyCharacteristic::Read;
    const bool isWriteCommand = type == QLowEnergyCharacteristic::WriteNoResponse;
    const bool isWriteAccess = type == QLowEnergyCharacteristic::Write
            || type == QLowEnergyCharacteristic::WriteSigned
            || isWriteCommand;
    Q_ASSERT(isReadAccess || isWriteAccess);
    if (!(attr.properties & type)) {
        if (isReadAccess)
            return ATT_ERROR_READ_NOT_PERM;

        // The spec says: If an attribute requires a signed write, then a non-signed write command
        // can also be used if the link is encrypted.
        const bool unsignedWriteOk = isWriteCommand
                && (attr.properties & QLowEnergyCharacteristic::WriteSigned)
                && securityLevel() >= BT_SECURITY_MEDIUM;
        if (!unsignedWriteOk)
            return ATT_ERROR_WRITE_NOT_PERM;
    }
    const AttAccessConstraints constraints = isReadAccess
            ? attr.readConstraints : attr.writeConstraints;
    if (constraints.testFlag(AttAuthorizationRequired))
        return ATT_ERROR_INSUF_AUTHORIZATION; // TODO: emit signal (and offer authorization function)?
    if (constraints.testFlag(AttEncryptionRequired) && securityLevel() < BT_SECURITY_MEDIUM)
        return ATT_ERROR_INSUF_ENCRYPTION;
    if (constraints.testFlag(AttAuthenticationRequired) && securityLevel() < BT_SECURITY_HIGH)
        return ATT_ERROR_INSUF_AUTHENTICATION;
    if (false)
        return ATT_ERROR_INSUF_ENCR_KEY_SIZE;
    return 0;
}

int QLowEnergyControllerPrivate::checkReadPermissions(const Attribute &attr)
{
    return checkPermissions(attr, QLowEnergyCharacteristic::Read);
}

int QLowEnergyControllerPrivate::checkReadPermissions(QVector<Attribute> &attributes)
{
    if (attributes.isEmpty())
        return 0;

    // The logic prescribed in the spec is as follows:
    //    1) If the first in a list of matching attributes has a permissions error,
    //       then that error is returned via an error response.
    //    2) If any other element of that list would cause a permissions error, then all
    //       attributes from this one on are not part of the result set, but no error is returned.
    const int error = checkReadPermissions(attributes.first());
    if (error)
        return error;
    const auto it = std::find_if(attributes.begin() + 1, attributes.end(),
            [this](const Attribute &attr) { return checkReadPermissions(attr) != 0; });
    if (it != attributes.end())
        attributes.erase(it, attributes.end());
    return 0;
}

bool QLowEnergyControllerPrivate::verifyMac(const QByteArray &message, const quint128 &csrk,
                                             quint32 signCounter, quint64 expectedMac)
{
    if (!cmacCalculator)
        cmacCalculator = new LeCmacCalculator;
    return cmacCalculator->verify(LeCmacCalculator::createFullMessage(message, signCounter), csrk,
                                expectedMac);
}

QT_END_NAMESPACE