qbluetoothdevicediscoveryagent_android.cpp

Go to the documentation of this file.

// Copyright (C) 2016 Lauri Laanmets (Proekspert AS) <lauri.laanmets@eesti.ee>
// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
 
#include "android/devicediscoverybroadcastreceiver_p.h"
#include "android/androidutils_p.h"
#include "android/jni_android_p.h"
#include "qbluetoothdevicediscoveryagent_p.h"
#include <QCoreApplication>
#include <QtCore/QLoggingCategory>
#include <QtCore/qpermissions.h>
#include <QtBluetooth/QBluetoothAddress>
#include <QtBluetooth/QBluetoothDeviceInfo>
#include <QtCore/QJniEnvironment>
#include <QtCore/private/qandroidextras_p.h>
 
QT_BEGIN_NAMESPACE
 
Q_DECLARE_LOGGING_CATEGORY(QT_BT_ANDROID)
 
enum {
    NoScanActive = 0,
    SDPScanActive = 1,
    BtleScanActive = 2
};
 
static constexpr auto deviceDiscoveryStartTimeLimit = std::chrono::seconds{5};
static constexpr short deviceDiscoveryStartMaxAttempts = 6;
 
QBluetoothDeviceDiscoveryAgentPrivate::QBluetoothDeviceDiscoveryAgentPrivate(
    const QBluetoothAddress &deviceAdapter, QBluetoothDeviceDiscoveryAgent *parent) :
    adapterAddress(deviceAdapter),
    m_active(NoScanActive),
    deviceDiscoveryStartAttemptsLeft(deviceDiscoveryStartMaxAttempts),
    q_ptr(parent)
{
    adapter = getDefaultBluetoothAdapter();
 
    if (!adapter.isValid())
        qCWarning(QT_BT_ANDROID) << "Device does not support Bluetooth";
}
 
QBluetoothDeviceDiscoveryAgentPrivate::~QBluetoothDeviceDiscoveryAgentPrivate()
{
    if (m_active != NoScanActive)
        stop();
 
    if (leScanner.isValid())
        leScanner.setField<jlong>("qtObject", reinterpret_cast<jlong>(nullptr));
 
    if (receiver) {
        receiver->unregisterReceiver();
        delete receiver;
    }
}
 
bool QBluetoothDeviceDiscoveryAgentPrivate::isActive() const
{
    if (pendingStart)
        return true;
    if (pendingCancel)
        return false;
    return m_active != NoScanActive;
}
 
QBluetoothDeviceDiscoveryAgent::DiscoveryMethods QBluetoothDeviceDiscoveryAgent::supportedDiscoveryMethods()
{
    return (LowEnergyMethod | ClassicMethod);
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::classicDiscoveryStartFail()
{
    Q_Q(QBluetoothDeviceDiscoveryAgent);
    lastError = QBluetoothDeviceDiscoveryAgent::InputOutputError;
    errorString = QBluetoothDeviceDiscoveryAgent::tr("Classic Discovery cannot be started");
    emit q->errorOccurred(lastError);
}
 
// Sets & emits an error and returns true if bluetooth is off
bool QBluetoothDeviceDiscoveryAgentPrivate::setErrorIfPowerOff()
{
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    const int state = adapter.callMethod<jint>("getState");
    if (state != 12) {  // BluetoothAdapter.STATE_ON
        lastError = QBluetoothDeviceDiscoveryAgent::PoweredOffError;
        m_active = NoScanActive;
        errorString = QBluetoothDeviceDiscoveryAgent::tr("Device is powered off");
        emit q->errorOccurred(lastError);
        return true;
    }
    return false;
}
 
/*
The Classic/LE discovery method precedence is handled as follows:
 
If only classic method is set => only classic method is used
If only LE method is set => only LE method is used
If both classic and LE methods are set, start classic scan first
    If classic scan fails to start, start LE scan immediately in the start function
    Otherwise start LE scan when classic scan completes
*/
 
void QBluetoothDeviceDiscoveryAgentPrivate::start(QBluetoothDeviceDiscoveryAgent::DiscoveryMethods methods)
{
    requestedMethods = methods;
 
    if (pendingCancel) {
        pendingStart = true;
        return;
    }
 
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    if (!adapter.isValid()) {
        qCWarning(QT_BT_ANDROID) << "Device does not support Bluetooth";
        lastError = QBluetoothDeviceDiscoveryAgent::InputOutputError;
        errorString = QBluetoothDeviceDiscoveryAgent::tr("Device does not support Bluetooth");
        emit q->errorOccurred(lastError);
        return;
    }
 
    if (!adapterAddress.isNull()
        && adapter.callMethod<jstring>("getAddress").toString()
        != adapterAddress.toString()) {
        qCWarning(QT_BT_ANDROID) << "Incorrect local adapter passed.";
        lastError = QBluetoothDeviceDiscoveryAgent::InvalidBluetoothAdapterError;
        errorString = QBluetoothDeviceDiscoveryAgent::tr("Passed address is not a local device.");
        emit q->errorOccurred(lastError);
        return;
    }
 
    if (setErrorIfPowerOff())
        return;
 
    if (!ensureAndroidPermission(QBluetoothPermission::Access)) {
        qCWarning(QT_BT_ANDROID)
                << "Search not possible due to missing QBluetoothPermission::Access permission";
        errorString = QBluetoothDeviceDiscoveryAgent::tr(
            "Failed to start device discovery due to missing permissions.");
        lastError = QBluetoothDeviceDiscoveryAgent::MissingPermissionsError;
        emit q->errorOccurred(lastError);
        return;
    }
    qCDebug(QT_BT_ANDROID) << "QBluetoothPermission::Access permission available";
 
    const bool scanNeedsLocation = (bool)QtJniTypes::QtBtUtility::callStaticMethod<jboolean>(
            "bluetoothScanRequiresLocation", QNativeInterface::QAndroidApplication::context());
 
    qCDebug(QT_BT_ANDROID) << "Is location service and location permission required for scan:"
                           << scanNeedsLocation;
 
    if (scanNeedsLocation) {
        // Double check we have location permission. With API-level < 31 it is already
        // guaranteed by the ensureAndroidPermission() above, but with API-level 31+ it is
        // required additionally if 'neverForLocation' assertion isn't set.
        QLocationPermission locationPermission;
        locationPermission.setAccuracy(QLocationPermission::Accuracy::Precise);
 
        if (qApp->checkPermission(locationPermission) != Qt::PermissionStatus::Granted) {
            qCWarning(QT_BT_ANDROID) << "Search not possible due to missing location permissions";
            lastError = QBluetoothDeviceDiscoveryAgent::LocationServiceTurnedOffError;
            errorString = QBluetoothDeviceDiscoveryAgent::tr("Location permission not granted. Search is not possible.");
            emit q->errorOccurred(lastError);
            return;
        }
 
        qCDebug(QT_BT_ANDROID) << "Location permission granted";
 
        // Double check Location service is turned on
        bool locationTurnedOn = true; // backwards compatible behavior to previous Qt versions
        const  QJniObject locString = QJniObject::getStaticObjectField(
            "android/content/Context", "LOCATION_SERVICE", "Ljava/lang/String;");
 
        const QJniObject locService =
            QJniObject(QNativeInterface::QAndroidApplication::context()).callMethod<jobject>(
                "getSystemService",
                locString.object<jstring>());
 
        if (locService.isValid()) {
            if (QNativeInterface::QAndroidApplication::sdkVersion() >= 28) {
                locationTurnedOn = bool(locService.callMethod<jboolean>("isLocationEnabled"));
            } else {
                // check whether there is any enabled provider
                QJniObject listOfEnabledProviders =
                    locService.callMethod<QtJniTypes::List>("getProviders", true);
 
                if (listOfEnabledProviders.isValid()) {
                    int size = listOfEnabledProviders.callMethod<jint>("size");
                    locationTurnedOn = size > 0;
                    qCDebug(QT_BT_ANDROID) << size << "enabled location providers detected.";
                }
            }
        }
 
        if (!locationTurnedOn) {
            qCWarning(QT_BT_ANDROID) << "Search not possible due to turned off Location service";
            lastError = QBluetoothDeviceDiscoveryAgent::LocationServiceTurnedOffError;
            errorString = QBluetoothDeviceDiscoveryAgent::tr("Location service turned off. Search is not possible.");
            emit q->errorOccurred(lastError);
            return;
        }
 
        qCDebug(QT_BT_ANDROID) << "Location turned on";
    }
 
    // install Java BroadcastReceiver
    if (!receiver) {
        // SDP based device discovery
        receiver = new DeviceDiscoveryBroadcastReceiver();
        qRegisterMetaType<QBluetoothDeviceInfo>();
        QObject::connect(receiver, SIGNAL(deviceDiscovered(QBluetoothDeviceInfo,bool)),
                         this, SLOT(processDiscoveredDevices(QBluetoothDeviceInfo,bool)));
        QObject::connect(receiver, SIGNAL(finished()), this, SLOT(processSdpDiscoveryFinished()));
    }
 
    lastError = QBluetoothDeviceDiscoveryAgent::NoError;
    errorString.clear();
    discoveredDevices.clear();
 
    // by arbitrary definition we run classic search first
    if (requestedMethods & QBluetoothDeviceDiscoveryAgent::ClassicMethod) {
        const bool success = adapter.callMethod<jboolean>("startDiscovery");
        if (!success) {
            qCDebug(QT_BT_ANDROID) << "Classic Discovery cannot be started";
            // Check if only classic discovery requested -> error out and return.
            // Otherwise since LE was also requested => don't return but allow the
            // function to continue to LE scanning
            if (requestedMethods == QBluetoothDeviceDiscoveryAgent::ClassicMethod) {
                classicDiscoveryStartFail();
                return;
            }
        } else {
            m_active = SDPScanActive;
            if (!deviceDiscoveryStartTimeout) {
                // In some bluetooth environments device discovery does not start properly
                // if it is done shortly after (up to 20 seconds) a full service discovery.
                // In that case we never get DISOVERY_STARTED action and device discovery never
                // finishes. Here we use a small timeout to guard it; if we don't get the
                // 'started' action in time, we restart the query. In the normal case the action
                // is received in < 1 second. See QTBUG-101066
                deviceDiscoveryStartTimeout = new QTimer(this);
                deviceDiscoveryStartTimeout->setInterval(deviceDiscoveryStartTimeLimit);
                deviceDiscoveryStartTimeout->setSingleShot(true);
                QObject::connect(receiver, &DeviceDiscoveryBroadcastReceiver::discoveryStarted,
                                 deviceDiscoveryStartTimeout, &QTimer::stop);
                QObject::connect(deviceDiscoveryStartTimeout, &QTimer::timeout, this, [this]() {
                    deviceDiscoveryStartAttemptsLeft -= 1;
                    qCWarning(QT_BT_ANDROID) << "Discovery start not received, attempts left:"
                                             <<  deviceDiscoveryStartAttemptsLeft;
                    // Check that bluetooth is not switched off
                    if (setErrorIfPowerOff())
                        return;
                    // If this was the last retry attempt, cancel the discovery just in case
                    // as a good cleanup practice
                    if (deviceDiscoveryStartAttemptsLeft <= 0) {
                        qCWarning(QT_BT_ANDROID) << "Classic device discovery failed to start";
                        (void)adapter.callMethod<jboolean>("cancelDiscovery");
                    }
                    // Restart the discovery and retry timer.
                    // The logic below is similar as in the start()
                    if (deviceDiscoveryStartAttemptsLeft > 0 &&
                            adapter.callMethod<jboolean>("startDiscovery"))
                        deviceDiscoveryStartTimeout->start();
                    else if (requestedMethods == QBluetoothDeviceDiscoveryAgent::ClassicMethod)
                        classicDiscoveryStartFail(); // No LE scan requested, scan is done
                    else
                        startLowEnergyScan(); // Continue to LE scan
                });
            }
            deviceDiscoveryStartAttemptsLeft = deviceDiscoveryStartMaxAttempts;
            deviceDiscoveryStartTimeout->start();
 
            qCDebug(QT_BT_ANDROID)
                << "QBluetoothDeviceDiscoveryAgentPrivate::start() - Classic search successfully started.";
            return;
        }
    }
 
    if (requestedMethods & QBluetoothDeviceDiscoveryAgent::LowEnergyMethod) {
        // LE search only requested or classic discovery failed but lets try LE scan anyway
        startLowEnergyScan();
    }
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::stop()
{
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    pendingStart = false;
 
    if (deviceDiscoveryStartTimeout)
        deviceDiscoveryStartTimeout->stop();
 
    if (m_active == NoScanActive)
        return;
 
    if (m_active == SDPScanActive) {
        if (pendingCancel) {
            // If we had both a pending cancel and a pending start,
            // we now have only a pending cancel.
            // The pending start was canceled above.
            return;
        }
 
        pendingCancel = true;
        bool success = adapter.callMethod<jboolean>("cancelDiscovery");
        if (!success) {
            lastError = QBluetoothDeviceDiscoveryAgent::InputOutputError;
            errorString = QBluetoothDeviceDiscoveryAgent::tr("Discovery cannot be stopped");
            emit q->errorOccurred(lastError);
            return;
        }
    } else if (m_active == BtleScanActive) {
        stopLowEnergyScan();
    }
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::processSdpDiscoveryFinished()
{
    // We need to guard because Android sends two DISCOVERY_FINISHED when cancelling
    // Also if we have two active agents both receive the same signal.
    // If this one is not active ignore the device information
    if (m_active != SDPScanActive)
        return;
 
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    if (pendingCancel && !pendingStart) {
        m_active = NoScanActive;
        pendingCancel = false;
        emit q->canceled();
    } else if (pendingStart) {
        pendingStart = pendingCancel = false;
        start(requestedMethods);
    } else {
        // check that it didn't finish due to turned off Bluetooth Device
        if (setErrorIfPowerOff())
            return;
        // Since no BTLE scan requested and classic scan is done => finished()
        if (!(requestedMethods & QBluetoothDeviceDiscoveryAgent::LowEnergyMethod)) {
            m_active = NoScanActive;
            emit q->finished();
            return;
        }
 
        startLowEnergyScan();
    }
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::processDiscoveredDevices(
    const QBluetoothDeviceInfo &info, bool isLeResult)
{
    // If we have two active agents both receive the same signal.
    // If this one is not active ignore the device information
    if (m_active != SDPScanActive && !isLeResult)
        return;
    if (m_active != BtleScanActive && isLeResult)
        return;
 
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    // Android Classic scan and LE scan can find the same device under different names
    // The classic name finds the SDP based device name, the LE scan finds the name in
    // the advertisement package.
    // If address is same but name different then we keep both entries.
 
    for (qsizetype i = 0; i < discoveredDevices.size(); ++i) {
        if (discoveredDevices[i].address() == info.address()) {
            QBluetoothDeviceInfo::Fields updatedFields = QBluetoothDeviceInfo::Field::None;
            if (discoveredDevices[i].rssi() != info.rssi()) {
                qCDebug(QT_BT_ANDROID) << "Updating RSSI for" << info.address()
                                       << info.rssi();
                discoveredDevices[i].setRssi(info.rssi());
                updatedFields.setFlag(QBluetoothDeviceInfo::Field::RSSI);
            }
            if (discoveredDevices[i].manufacturerData() != info.manufacturerData()) {
                qCDebug(QT_BT_ANDROID) << "Updating manufacturer data for" << info.address();
                const QList<quint16> keys = info.manufacturerIds();
                for (auto key: keys)
                    discoveredDevices[i].setManufacturerData(key, info.manufacturerData(key));
                updatedFields.setFlag(QBluetoothDeviceInfo::Field::ManufacturerData);
            }
            if (discoveredDevices[i].serviceData() != info.serviceData()) {
                qCDebug(QT_BT_ANDROID) << "Updating service data for" << info.address();
                const QList<QBluetoothUuid> keys = info.serviceIds();
                for (auto key : keys)
                    discoveredDevices[i].setServiceData(key, info.serviceData(key));
                updatedFields.setFlag(QBluetoothDeviceInfo::Field::ServiceData);
            }
 
            if (lowEnergySearchTimeout > 0) {
                if (discoveredDevices[i] != info) {
                    if (discoveredDevices.at(i).name() == info.name()) {
                        qCDebug(QT_BT_ANDROID) << "Almost Duplicate " << info.address()
                                               << info.name() << "- replacing in place";
                        discoveredDevices.replace(i, info);
                        emit q->deviceDiscovered(info);
                    }
                } else {
                    if (!updatedFields.testFlag(QBluetoothDeviceInfo::Field::None))
                        emit q->deviceUpdated(discoveredDevices[i], updatedFields);
                }
 
                return;
            }
 
            discoveredDevices.replace(i, info);
            emit q->deviceDiscovered(info);
 
            if (!updatedFields.testFlag(QBluetoothDeviceInfo::Field::None))
                emit q->deviceUpdated(discoveredDevices[i], updatedFields);
 
            return;
        }
    }
 
    discoveredDevices.append(info);
    qCDebug(QT_BT_ANDROID) << "Device found: " << info.name() << info.address().toString()
                           << "isLeScanResult:" << isLeResult
                           << "Manufacturer data size:" << info.manufacturerData().size();
    emit q->deviceDiscovered(info);
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::startLowEnergyScan()
{
    Q_Q(QBluetoothDeviceDiscoveryAgent);
 
    m_active = BtleScanActive;
 
    if (!leScanner.isValid()) {
        leScanner = QJniObject::construct<QtJniTypes::QtBtLECentral>(
                    QNativeInterface::QAndroidApplication::context());
        if (!leScanner.isValid()) {
            qCWarning(QT_BT_ANDROID) << "Cannot load BTLE device scan class";
            m_active = NoScanActive;
            emit q->finished();
            return;
        }
 
        leScanner.setField<jlong>("qtObject", reinterpret_cast<long>(receiver));
    }
 
    jboolean result = leScanner.callMethod<jboolean>("scanForLeDevice", true);
    if (!result) {
        qCWarning(QT_BT_ANDROID) << "Cannot start BTLE device scanner";
        m_active = NoScanActive;
        emit q->finished();
        return;
    }
 
    // wait interval and sum up what was found
    if (!leScanTimeout) {
        leScanTimeout = new QTimer(this);
        leScanTimeout->setSingleShot(true);
        connect(leScanTimeout, &QTimer::timeout,
                this, &QBluetoothDeviceDiscoveryAgentPrivate::stopLowEnergyScan);
    }
 
    if (lowEnergySearchTimeout > 0) { // otherwise no timeout and stop() required
        leScanTimeout->setInterval(lowEnergySearchTimeout);
        leScanTimeout->start();
    }
 
    qCDebug(QT_BT_ANDROID)
        << "QBluetoothDeviceDiscoveryAgentPrivate::start() - Low Energy search successfully started.";
}
 
void QBluetoothDeviceDiscoveryAgentPrivate::stopLowEnergyScan()
{
    jboolean result = leScanner.callMethod<jboolean>("scanForLeDevice", false);
    if (!result)
        qCWarning(QT_BT_ANDROID) << "Cannot stop BTLE device scanner";
 
    m_active = NoScanActive;
 
    Q_Q(QBluetoothDeviceDiscoveryAgent);
    if (leScanTimeout->isActive()) {
        // still active if this function was called from stop()
        leScanTimeout->stop();
        emit q->canceled();
    } else {
        // timeout -> regular stop
        emit q->finished();
    }
}
QT_END_NAMESPACE