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*
* Copyright 2013 - 2022, nymea GmbH
* Contact: contact@nymea.io
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* under https://nymea.io/license
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* GNU Lesser General Public License Usage
* Alternatively, this project may be redistributed and/or modified under the
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* Software Foundation; version 3. This project is distributed in the hope that
* it will be useful, but WITHOUT ANY WARRANTY; without even the implied
* warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
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#include "networkdevicediscoveryimpl.h"

#include "nymeasettings.h"
#include "loggingcategories.h"

#include <network/ping.h>
#include <network/arpsocket.h>
#include <network/networkutils.h>

#include <QDateTime>

NYMEA_LOGGING_CATEGORY(dcNetworkDeviceDiscovery, "NetworkDeviceDiscovery")

namespace nymeaserver {

NetworkDeviceDiscoveryImpl::NetworkDeviceDiscoveryImpl(QObject *parent) :
    NetworkDeviceDiscovery(parent)
{
    // Create ARP socket
    m_arpSocket = new ArpSocket(this);
    connect(m_arpSocket, &ArpSocket::arpResponse, this, &NetworkDeviceDiscoveryImpl::onArpResponseReceived);
    bool arpAvailable = m_arpSocket->openSocket();
    if (!arpAvailable) {
        m_arpSocket->closeSocket();
    }

    // Create ping socket
    m_ping = new Ping(this);
    if (!m_ping->available())
        qCWarning(dcNetworkDeviceDiscovery()) << "Failed to create ping tool" << m_ping->error();

    // Init MAC database if available
    m_macAddressDatabase = new MacAddressDatabase(this);

    // Timer for max duration af a discovery
    m_discoveryTimer = new QTimer(this);
    m_discoveryTimer->setInterval(20000);
    m_discoveryTimer->setSingleShot(true);
    connect(m_discoveryTimer, &QTimer::timeout, this, [=](){
        if (m_runningPingRepies.isEmpty() && m_currentReply) {
            finishDiscovery();
        }
    });

    // Timer for updating the monitors
    m_monitorTimer = new QTimer(this);
    m_monitorTimer->setInterval(5000);
    m_monitorTimer->setSingleShot(false);
    connect(m_monitorTimer, &QTimer::timeout, this, &NetworkDeviceDiscoveryImpl::evaluateMonitors);

    if (!arpAvailable && !m_ping->available()) {
        qCWarning(dcNetworkDeviceDiscovery()) << "Network device discovery is not available on this system.";
    } else {
        qCDebug(dcNetworkDeviceDiscovery()) << "Created successfully";
    }

    m_cacheSettings = new QSettings(NymeaSettings::cachePath() + "/network-device-discovery.cache", QSettings::IniFormat);
    loadNetworkDeviceCache();
}

NetworkDeviceDiscoveryImpl::~NetworkDeviceDiscoveryImpl()
{

}

NetworkDeviceDiscoveryReply *NetworkDeviceDiscoveryImpl::discover()
{
    if (m_currentReply) {
        qCDebug(dcNetworkDeviceDiscovery()) << "Discovery already running. Returning current pending discovery reply...";
        return m_currentReply;
    }

    qCDebug(dcNetworkDeviceDiscovery()) << "Starting network device discovery ...";
    m_currentReply = new NetworkDeviceDiscoveryReplyImpl(this);
    connect(m_currentReply, &NetworkDeviceDiscoveryReplyImpl::networkDeviceInfoAdded, this, &NetworkDeviceDiscoveryImpl::updateCache);

    if (m_ping->available())
        pingAllNetworkDevices();

    if (m_arpSocket->isOpen())
        m_arpSocket->sendRequest();

    m_discoveryTimer->start();

    m_running = true;
    emit runningChanged(m_running);

    return m_currentReply;
}

bool NetworkDeviceDiscoveryImpl::available() const
{
    return m_arpSocket->isOpen() || m_ping->available();
}

bool NetworkDeviceDiscoveryImpl::enabled() const
{
    return m_enabled;
}

bool NetworkDeviceDiscoveryImpl::running() const
{
    return m_running;
}

NetworkDeviceMonitor *NetworkDeviceDiscoveryImpl::registerMonitor(const QString &macAddress)
{
    if (m_monitors.contains(macAddress))
        return m_monitors.value(macAddress);

    NetworkDeviceInfo info;
    if (m_networkInfoCache.contains(macAddress)) {
        info = m_networkInfoCache.value(macAddress);
    } else {
        info.setMacAddress(macAddress);
        qCDebug(dcNetworkDeviceDiscovery()) << "Adding mac address monitor for unresolved mac address. Starting a discovery...";
        discover();
    }

    NetworkDeviceMonitorImpl *monitor = new NetworkDeviceMonitorImpl(info, this);
    bool initRequired = m_monitors.isEmpty();
    m_monitors.insert(macAddress, monitor);
    if (initRequired) {
        m_monitorTimer->start();
        evaluateMonitors();
    }

    return monitor;
}

void NetworkDeviceDiscoveryImpl::unregisterMonitor(const QString &macAddress)
{
    if (m_monitors.contains(macAddress)) {
        NetworkDeviceMonitor *monitor = m_monitors.take(macAddress);
        monitor->deleteLater();
    }
}

void NetworkDeviceDiscoveryImpl::unregisterMonitor(NetworkDeviceMonitor *networkDeviceMonitor)
{
    unregisterMonitor(networkDeviceMonitor->networkDeviceInfo().macAddress());
}

PingReply *NetworkDeviceDiscoveryImpl::ping(const QHostAddress &address)
{
    // Note: we use any ping used trough this method also for the monitor evaluation
    PingReply *reply = m_ping->ping(address);
    connect(reply, &PingReply::finished, this, [=](){
        foreach (NetworkDeviceMonitorImpl *monitor, m_monitors.values()) {
            if (monitor->networkDeviceInfo().address() == address) {
                processMonitorPingResult(reply, monitor);
            }
        }
    });
    return reply;
}

MacAddressDatabaseReply *NetworkDeviceDiscoveryImpl::lookupMacAddress(const QString &macAddress)
{
    return m_macAddressDatabase->lookupMacAddress(macAddress);
}

bool NetworkDeviceDiscoveryImpl::sendArpRequest(const QHostAddress &address)
{
    if (m_arpSocket && m_arpSocket->isOpen())
        return m_arpSocket->sendRequest(address);

    return false;
}

void NetworkDeviceDiscoveryImpl::setEnabled(bool enabled)
{
    m_enabled = enabled;
    emit enabledChanged(m_enabled);

    // TODO: disable network discovery if false, not used for now
}

void NetworkDeviceDiscoveryImpl::pingAllNetworkDevices()
{
    qCDebug(dcNetworkDeviceDiscovery()) << "Starting ping for all network devices...";
    foreach (const QNetworkInterface &networkInterface, QNetworkInterface::allInterfaces()) {
        if (networkInterface.flags().testFlag(QNetworkInterface::IsLoopBack))
            continue;

        if (!networkInterface.flags().testFlag(QNetworkInterface::IsUp))
            continue;

        if (!networkInterface.flags().testFlag(QNetworkInterface::IsRunning))
            continue;

        qCDebug(dcNetworkDeviceDiscovery()) << "Verifying network interface" << networkInterface.name() << networkInterface.hardwareAddress() << "...";
        foreach (const QNetworkAddressEntry &entry, networkInterface.addressEntries()) {
            qCDebug(dcNetworkDeviceDiscovery()) << "  Checking entry" << entry.ip().toString();

            // Only IPv4
            if (entry.ip().protocol() != QAbstractSocket::IPv4Protocol)
                continue;

            qCDebug(dcNetworkDeviceDiscovery()) << "    Host address:" << entry.ip().toString();
            qCDebug(dcNetworkDeviceDiscovery()) << "    Broadcast address:" << entry.broadcast().toString();
            qCDebug(dcNetworkDeviceDiscovery()) << "    Netmask:" << entry.netmask().toString();
            quint32 addressRangeStart = entry.ip().toIPv4Address() & entry.netmask().toIPv4Address();
            quint32 addressRangeStop = entry.broadcast().toIPv4Address() | addressRangeStart;
            quint32 range = addressRangeStop - addressRangeStart;

            // Let's scan only 255.255.255.0 networks for now
            if (range > 255)
                continue;

            qCDebug(dcNetworkDeviceDiscovery()) << "    Address range" << range << " | from" << QHostAddress(addressRangeStart).toString() << "-->" << QHostAddress(addressRangeStop).toString();
            // Send ping request to each address within the range
            for (quint32 i = 1; i < range; i++) {
                quint32 address = addressRangeStart + i;
                QHostAddress targetAddress(address);

                // Skip our self
                if (targetAddress == entry.ip())
                    continue;

                PingReply *reply = ping(targetAddress);
                m_runningPingRepies.append(reply);
                connect(reply, &PingReply::finished, this, [=](){
                    m_runningPingRepies.removeAll(reply);
                    if (reply->error() == PingReply::ErrorNoError) {
                        qCDebug(dcNetworkDeviceDiscovery()) << "Ping response from" << targetAddress.toString() << reply->hostName() << reply->duration() << "ms";
                        if (m_currentReply) {
                            m_currentReply->processPingResponse(targetAddress, reply->hostName());
                        }
                    }

                    if (m_runningPingRepies.isEmpty() && m_currentReply) {
                        qCWarning(dcNetworkDeviceDiscovery()) << "All ping replies finished for discovery." << m_currentReply->networkDeviceInfos().count();
                        finishDiscovery();
                    }
                });
            }
        }
    }
}

void NetworkDeviceDiscoveryImpl::finishDiscovery()
{
    m_discoveryTimer->stop();

    m_running = false;
    emit runningChanged(m_running);

    emit networkDeviceInfoCacheUpdated();

    m_currentReply->processDiscoveryFinished();
    m_currentReply->deleteLater();
    m_currentReply = nullptr;
}

void NetworkDeviceDiscoveryImpl::processMonitorPingResult(PingReply *reply, NetworkDeviceMonitorImpl *monitor)
{
    if (reply->error() == PingReply::ErrorNoError) {
        qCDebug(dcNetworkDeviceDiscovery()) << "Ping response from" << monitor << reply->duration() << "ms";
        monitor->setLastSeen(QDateTime::currentDateTime());
        monitor->setReachable(true);
    } else {
        qCDebug(dcNetworkDeviceDiscovery()) << "Failed to ping device from" << monitor << reply->error();
        monitor->setReachable(false);
    }
}

void NetworkDeviceDiscoveryImpl::loadNetworkDeviceCache()
{
    qCDebug(dcNetworkDeviceDiscovery()) << "Loading cached network device information from" << m_cacheSettings->fileName();
    m_networkInfoCache.clear();
    m_cacheSettings->beginGroup("NetworkDeviceInfos");
    foreach (const QString &macAddress, m_cacheSettings->childGroups()) {
        m_cacheSettings->beginGroup(macAddress);
        NetworkDeviceInfo info(macAddress);
        info.setAddress(QHostAddress(m_cacheSettings->value("address").toString()));
        info.setHostName(m_cacheSettings->value("hostName").toString());
        info.setMacAddressManufacturer(m_cacheSettings->value("manufacturer").toString());
        info.setNetworkInterface(QNetworkInterface::interfaceFromName(m_cacheSettings->value("interface").toString()));
        if (info.isValid() && info.isComplete()) {
            qCDebug(dcNetworkDeviceDiscovery()) << "Loaded cached" << info;
            m_networkInfoCache.insert(info.macAddress(), info);
        } else {
            qCWarning(dcNetworkDeviceDiscovery()) << "Clean up invalid cached network device info from cache" << info;
            m_cacheSettings->remove("");
        }
        m_cacheSettings->endGroup(); // mac address
    }
    m_cacheSettings->endGroup(); // NetworkDeviceInfos
}

void NetworkDeviceDiscoveryImpl::removeFromNetworkDeviceCache(const QString &macAddress)
{
    if (macAddress.isEmpty())
        return;

    m_networkInfoCache.remove(macAddress);

    m_cacheSettings->beginGroup("NetworkDeviceInfos");
    m_cacheSettings->beginGroup(macAddress);
    m_cacheSettings->remove("");
    m_cacheSettings->endGroup(); // mac address
    m_cacheSettings->endGroup(); // NetworkDeviceInfos
}

void NetworkDeviceDiscoveryImpl::saveNetworkDeviceCache(const NetworkDeviceInfo &deviceInfo)
{
    m_cacheSettings->beginGroup("NetworkDeviceInfos");
    m_cacheSettings->beginGroup(deviceInfo.macAddress());
    m_cacheSettings->setValue("address", deviceInfo.address().toString());
    m_cacheSettings->setValue("hostName", deviceInfo.hostName());
    m_cacheSettings->setValue("manufacturer", deviceInfo.macAddressManufacturer());
    m_cacheSettings->setValue("interface", deviceInfo.networkInterface().name());
    m_cacheSettings->endGroup(); // mac address
    m_cacheSettings->endGroup(); // NetworkDeviceInfos
}

void NetworkDeviceDiscoveryImpl::updateCache(const NetworkDeviceInfo &deviceInfo)
{
    if (deviceInfo.macAddress().isEmpty())
        return;

    if (m_monitors.contains(deviceInfo.macAddress())) {
        NetworkDeviceMonitorImpl *monitor = m_monitors.value(deviceInfo.macAddress());
        monitor->updateNetworkDeviceInfo(deviceInfo);
    }

    if (m_networkInfoCache.value(deviceInfo.macAddress()) == deviceInfo)
        return;

    m_networkInfoCache[deviceInfo.macAddress()] = deviceInfo;
    saveNetworkDeviceCache(deviceInfo);
}

void NetworkDeviceDiscoveryImpl::onArpResponseReceived(const QNetworkInterface &interface, const QHostAddress &address, const QString &macAddress)
{
    // Ignore ARP from zero mac
    if (macAddress == QString("00:00:00:00:00:00")) {
        qCDebug(dcNetworkDeviceDiscovery()) << "Ignoring ARP reply from" << address.toString() << macAddress << interface.name();
        return;
    }

    qCDebug(dcNetworkDeviceDiscovery()) << "ARP reply received" << address.toString() << macAddress << interface.name();

    if (m_networkInfoCache.contains(macAddress)) {
        if (m_networkInfoCache.value(macAddress).address() != address) {
            m_networkInfoCache[macAddress].setAddress(address);
            saveNetworkDeviceCache(m_networkInfoCache[macAddress]);
        }
    }

    // Update the monitors
    foreach (NetworkDeviceMonitorImpl *monitor, m_monitors) {
        if (monitor->networkDeviceInfo().macAddress() == macAddress) {
            monitor->setLastSeen(QDateTime::currentDateTime());
            monitor->setReachable(true);

            if (monitor->networkDeviceInfo().address() != address) {
                monitor->m_networkDeviceInfo.setAddress(address);
                emit monitor->networkDeviceInfoChanged(monitor->networkDeviceInfo());
            }
        }
    }

    // Check if we have a reply running
    if (m_currentReply) {

        // First process the response
        m_currentReply->processArpResponse(interface, address, macAddress);

        // Check if we know the mac address manufacturer from the cache
        if (m_networkInfoCache.contains(macAddress)) {
            QString cachedManufacturer = m_networkInfoCache[macAddress].macAddressManufacturer();
            if (!cachedManufacturer.isEmpty()) {
                // Found the mac address manufacturer in the cache, let's use that
                m_currentReply->processMacManufacturer(macAddress, cachedManufacturer);
            }
        } else {
            // Lookup the mac address vendor if possible
            if (m_macAddressDatabase->available()) {
                MacAddressDatabaseReply *reply = m_macAddressDatabase->lookupMacAddress(macAddress);
                connect(reply, &MacAddressDatabaseReply::finished, m_currentReply, [=](){
                    qCDebug(dcNetworkDeviceDiscovery()) << "MAC manufacturer lookup finished for" << macAddress << ":" << reply->manufacturer();
                    m_currentReply->processMacManufacturer(macAddress, reply->manufacturer());
                });
            } else {
                // Note: set the mac manufacturer explicitly to make the info complete
                m_currentReply->processMacManufacturer(macAddress, QString());
            }
        }
    }
}

void NetworkDeviceDiscoveryImpl::evaluateMonitors()
{
    foreach (NetworkDeviceMonitorImpl *monitor, m_monitors) {
        // Start action if we have not seen the device for gracePeriod seconds
        const int gracePeriod = 60;
        QDateTime currentDateTime = QDateTime::currentDateTime();

        bool requiresRefresh = false;

        if (monitor->lastSeen().isNull()) {
            qCDebug(dcNetworkDeviceDiscovery()) << monitor << "requires refresh. Not seen yet";
            requiresRefresh = true;
        }

        if (!requiresRefresh && currentDateTime > monitor->lastSeen().addSecs(gracePeriod)) {
            qCDebug(dcNetworkDeviceDiscovery()) << monitor << "requires refresh. Not see since" << (currentDateTime.toMSecsSinceEpoch() - monitor->lastSeen().toMSecsSinceEpoch()) / 1000.0 << "s";
            requiresRefresh = true;
        }

        if (!requiresRefresh)
            continue;

        if (monitor->networkDeviceInfo().address().isNull()) {
            // Not known yet
            // TODO: load from cache
            continue;
        }

        // Try to ping first
        qCDebug(dcNetworkDeviceDiscovery()) << monitor << "try to ping" << monitor->networkDeviceInfo().address().toString();
        PingReply *reply = m_ping->ping(monitor->networkDeviceInfo().address());
        connect(reply, &PingReply::finished, monitor, [=](){
            processMonitorPingResult(reply, monitor);
        });
    }
}

}