/****************************************************************************

**

** Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (qt-info@nokia.com)

**

** This file is part of the QtNetwork module of the Qt Toolkit.

**

** $QT_BEGIN_LICENSE:LGPL$

** GNU Lesser General Public License Usage

** This file may be used under the terms of the GNU Lesser General Public

** License version 2.1 as published by the Free Software Foundation and

** appearing in the file LICENSE.LGPL included in the packaging of this

** file. Please review the following information to ensure the GNU Lesser

** General Public License version 2.1 requirements will be met:

** http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.

**

** In addition, as a special exception, Nokia gives you certain additional

** rights. These rights are described in the Nokia Qt LGPL Exception

** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** GNU General Public License Usage

** Alternatively, this file may be used under the terms of the GNU General

** Public License version 3.0 as published by the Free Software Foundation

** and appearing in the file LICENSE.GPL included in the packaging of this

** file. Please review the following information to ensure the GNU General

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** $QT_END_LICENSE$

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****************************************************************************/

#include "qhostinfo.h"

#include "qhostinfo_p.h"

#include "QtCore/qscopedpointer.h"

#include <qabstracteventdispatcher.h>

#include <qcoreapplication.h>

#include <qmetaobject.h>

#include <qstringlist.h>

#include <qthread.h>

#include <qurl.h>

#include <private/qnetworksession_p.h>

#ifdef Q_OS_UNIX

#  include <unistd.h>

#endif

QT_BEGIN_NAMESPACE

//#define QHOSTINFO_DEBUG

#ifndef Q_OS_SYMBIAN

Q_GLOBAL_STATIC(QHostInfoLookupManager, theHostInfoLookupManager)

#else

Q_GLOBAL_STATIC(QSymbianHostInfoLookupManager, theHostInfoLookupManager)

#endif

/*!

    \class QHostInfo

    \brief The QHostInfo class provides static functions for host name lookups.

    \reentrant

    \inmodule QtNetwork

    \ingroup network

    QHostInfo uses the lookup mechanisms provided by the operating

    system to find the IP address(es) associated with a host name,

    or the host name associated with an IP address.

    The class provides two static convenience functions: one that

    works asynchronously and emits a signal once the host is found,

    and one that blocks and returns a QHostInfo object.

    To look up a host's IP addresses asynchronously, call lookupHost(),

    which takes the host name or IP address, a receiver object, and a slot

    signature as arguments and returns an ID. You can abort the

    lookup by calling abortHostLookup() with the lookup ID.

    Example:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 0

    The slot is invoked when the results are ready. The results are

    stored in a QHostInfo object. Call

    addresses() to get the list of IP addresses for the host, and

    hostName() to get the host name that was looked up.

    If the lookup failed, error() returns the type of error that

    occurred. errorString() gives a human-readable description of the

    lookup error.

    If you want a blocking lookup, use the QHostInfo::fromName() function:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 1

    QHostInfo supports Internationalized Domain Names (IDNs) through the

    IDNA and Punycode standards.

    To retrieve the name of the local host, use the static

    QHostInfo::localHostName() function.

    \note Since Qt 4.6.1 QHostInfo is using multiple threads for DNS lookup

    instead of one dedicated DNS thread. This improves performance,

    but also changes the order of signal emissions when using lookupHost()

    compared to previous versions of Qt.

    \note Since Qt 4.6.3 QHostInfo is using a small internal 60 second DNS cache

    for performance improvements.

    \sa QAbstractSocket, {http://www.rfc-editor.org/rfc/rfc3492.txt}{RFC 3492}

*/

static QBasicAtomicInt theIdCounter = Q_BASIC_ATOMIC_INITIALIZER(1);

/*!

    Looks up the IP address(es) associated with host name \a name, and

    returns an ID for the lookup. When the result of the lookup is

    ready, the slot or signal \a member in \a receiver is called with

    a QHostInfo argument. The QHostInfo object can then be inspected

    to get the results of the lookup.

    The lookup is performed by a single function call, for example:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 2

    The implementation of the slot prints basic information about the

    addresses returned by the lookup, or reports an error if it failed:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 3

    If you pass a literal IP address to \a name instead of a host name,

    QHostInfo will search for the domain name for the IP (i.e., QHostInfo will

    perform a \e reverse lookup). On success, the resulting QHostInfo will

    contain both the resolved domain name and IP addresses for the host

    name. Example:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 4

    \note There is no guarantee on the order the signals will be emitted

    if you start multiple requests with lookupHost().

    \sa abortHostLookup(), addresses(), error(), fromName()

*/

int QHostInfo::lookupHost(const QString &name, QObject *receiver,

                          const char *member)

{

#if defined QHOSTINFO_DEBUG

    qDebug("QHostInfo::lookupHost(\"%s\", %p, %s)",

           name.toLatin1().constData(), receiver, member ? member + 1 : 0);

#endif

    if (!QAbstractEventDispatcher::instance(QThread::currentThread())) {

        qWarning("QHostInfo::lookupHost() called with no event dispatcher");

        return -1;

    }

    qRegisterMetaType<QHostInfo>("QHostInfo");

    int id = theIdCounter.fetchAndAddRelaxed(1); // generate unique ID

    if (name.isEmpty()) {

        QHostInfo hostInfo(id);

        hostInfo.setError(QHostInfo::HostNotFound);

        hostInfo.setErrorString(QCoreApplication::translate("QHostInfo", "No host name given"));

        QScopedPointer<QHostInfoResult> result(new QHostInfoResult);

        QObject::connect(result.data(), SIGNAL(resultsReady(QHostInfo)),

                         receiver, member, Qt::QueuedConnection);

        result.data()->emitResultsReady(hostInfo);

        return id;

    }

#ifndef Q_OS_SYMBIAN

    QHostInfoLookupManager *manager = theHostInfoLookupManager();

    if (manager) {

        // the application is still alive

        if (manager->cache.isEnabled()) {

            // check cache first

            bool valid = false;

            QHostInfo info = manager->cache.get(name, &valid);

            if (valid) {

                info.setLookupId(id);

                QHostInfoResult result;

                QObject::connect(&result, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);

                result.emitResultsReady(info);

                return id;

            }

        }

        // cache is not enabled or it was not in the cache, do normal lookup

        QHostInfoRunnable* runnable = new QHostInfoRunnable(name, id);

        QObject::connect(&runnable->resultEmitter, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);

        manager->scheduleLookup(runnable);

    }

#else

    QSymbianHostInfoLookupManager *manager = theHostInfoLookupManager();

    if (manager) {

        // the application is still alive

        if (manager->cache.isEnabled()) {

            // check cache first

            bool valid = false;

            QHostInfo info = manager->cache.get(name, &valid);

            if (valid) {

                info.setLookupId(id);

                QHostInfoResult result;

                QObject::connect(&result, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);

                result.emitResultsReady(info);

                return id;

            }

        }

        // cache is not enabled or it was not in the cache, do normal lookup

#ifndef QT_NO_BEARERMANAGEMENT

        QSharedPointer<QNetworkSession> networkSession;

        QVariant v(receiver->property("_q_networksession"));

        if (v.isValid())

            networkSession = qvariant_cast< QSharedPointer<QNetworkSession> >(v);

#endif

        QSymbianHostResolver *symbianResolver = 0;

        QT_TRAP_THROWING(symbianResolver = new QSymbianHostResolver(name, id, networkSession));

        QObject::connect(&symbianResolver->resultEmitter, SIGNAL(resultsReady(QHostInfo)), receiver, member, Qt::QueuedConnection);

        manager->scheduleLookup(symbianResolver);

    }

#endif

    return id;

}

/*!

    Aborts the host lookup with the ID \a id, as returned by lookupHost().

    \sa lookupHost(), lookupId()

*/

void QHostInfo::abortHostLookup(int id)

{

    theHostInfoLookupManager()->abortLookup(id);

}

/*!

    Looks up the IP address(es) for the given host \a name. The

    function blocks during the lookup which means that execution of

    the program is suspended until the results of the lookup are

    ready. Returns the result of the lookup in a QHostInfo object.

    If you pass a literal IP address to \a name instead of a host name,

    QHostInfo will search for the domain name for the IP (i.e., QHostInfo will

    perform a \e reverse lookup). On success, the returned QHostInfo will

    contain both the resolved domain name and IP addresses for the host name.

    \sa lookupHost()

*/

QHostInfo QHostInfo::fromName(const QString &name)

{

#if defined QHOSTINFO_DEBUG

    qDebug("QHostInfo::fromName(\"%s\")",name.toLatin1().constData());

#endif

    QHostInfo hostInfo = QHostInfoAgent::fromName(name);

    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();

    manager->cache.put(name, hostInfo);

    return hostInfo;

}

#ifndef QT_NO_BEARERMANAGEMENT

QHostInfo QHostInfoPrivate::fromName(const QString &name, QSharedPointer<QNetworkSession> session)

{

#if defined QHOSTINFO_DEBUG

    qDebug("QHostInfoPrivate::fromName(\"%s\") with session %p",name.toLatin1().constData(), session.data());

#endif

    QHostInfo hostInfo = QHostInfoAgent::fromName(name, session);

    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();

    manager->cache.put(name, hostInfo);

    return hostInfo;

}

#endif

#ifndef Q_OS_SYMBIAN

#ifndef QT_NO_BEARERMANAGEMENT

// This function has a special implementation for symbian right now in qhostinfo_symbian.cpp but not on other OS.

QHostInfo QHostInfoAgent::fromName(const QString &hostName, QSharedPointer<QNetworkSession>)

{

    return QHostInfoAgent::fromName(hostName);

}

#endif

#endif

/*!

    \enum QHostInfo::HostInfoError

    This enum describes the various errors that can occur when trying

    to resolve a host name.

    \value NoError The lookup was successful.

    \value HostNotFound No IP addresses were found for the host.

    \value UnknownError An unknown error occurred.

    \sa error(), setError()

*/

/*!

    Constructs an empty host info object with lookup ID \a id.

    \sa lookupId()

*/

QHostInfo::QHostInfo(int id)

    : d(new QHostInfoPrivate)

{

    d->lookupId = id;

}

/*!

    Constructs a copy of \a other.

*/

QHostInfo::QHostInfo(const QHostInfo &other)

    : d(new QHostInfoPrivate(*other.d.data()))

{

}

/*!

    Assigns the data of the \a other object to this host info object,

    and returns a reference to it.

*/

QHostInfo &QHostInfo::operator=(const QHostInfo &other)

{

    *d.data() = *other.d.data();

    return *this;

}

/*!

    Destroys the host info object.

*/

QHostInfo::~QHostInfo()

{

}

/*!

    Returns the list of IP addresses associated with hostName(). This

    list may be empty.

    Example:

    \snippet doc/src/snippets/code/src_network_kernel_qhostinfo.cpp 5

    \sa hostName(), error()

*/

QList<QHostAddress> QHostInfo::addresses() const

{

    return d->addrs;

}

/*!

    Sets the list of addresses in this QHostInfo to \a addresses.

    \sa addresses()

*/

void QHostInfo::setAddresses(const QList<QHostAddress> &addresses)

{

    d->addrs = addresses;

}

/*!

    Returns the name of the host whose IP addresses were looked up.

    \sa localHostName()

*/

QString QHostInfo::hostName() const

{

    return d->hostName;

}

/*!

    Sets the host name of this QHostInfo to \a hostName.

    \sa hostName()

*/

void QHostInfo::setHostName(const QString &hostName)

{

    d->hostName = hostName;

}

/*!

    Returns the type of error that occurred if the host name lookup

    failed; otherwise returns NoError.

    \sa setError(), errorString()

*/

QHostInfo::HostInfoError QHostInfo::error() const

{

    return d->err;

}

/*!

    Sets the error type of this QHostInfo to \a error.

    \sa error(), errorString()

*/

void QHostInfo::setError(HostInfoError error)

{

    d->err = error;

}

/*!

    Returns the ID of this lookup.

    \sa setLookupId(), abortHostLookup(), hostName()

*/

int QHostInfo::lookupId() const

{

    return d->lookupId;

}

/*!

    Sets the ID of this lookup to \a id.

    \sa lookupId(), lookupHost()

*/

void QHostInfo::setLookupId(int id)

{

    d->lookupId = id;

}

/*!

    If the lookup failed, this function returns a human readable

    description of the error; otherwise "Unknown error" is returned.

    \sa setErrorString(), error()

*/

QString QHostInfo::errorString() const

{

    return d->errorStr;

}

/*!

    Sets the human readable description of the error that occurred to \a str

    if the lookup failed.

    \sa errorString(), setError()

*/

void QHostInfo::setErrorString(const QString &str)

{

    d->errorStr = str;

}

/*!

    \fn QString QHostInfo::localHostName()

    Returns the host name of this machine.

    \sa hostName()

*/

/*!

    \fn QString QHostInfo::localDomainName()

    Returns the DNS domain of this machine.

    Note: DNS domains are not related to domain names found in

    Windows networks.

    \sa hostName()

*/

#ifndef Q_OS_SYMBIAN

QHostInfoRunnable::QHostInfoRunnable(QString hn, int i) : toBeLookedUp(hn), id(i)

{

    setAutoDelete(true);

}

// the QHostInfoLookupManager will at some point call this via a QThreadPool

void QHostInfoRunnable::run()

{

    QHostInfoLookupManager *manager = theHostInfoLookupManager();

    // check aborted

    if (manager->wasAborted(id)) {

        manager->lookupFinished(this);

        return;

    }

    QHostInfo hostInfo;

    // QHostInfo::lookupHost already checks the cache. However we need to check

    // it here too because it might have been cache saved by another QHostInfoRunnable

    // in the meanwhile while this QHostInfoRunnable was scheduled but not running

    if (manager->cache.isEnabled()) {

        // check the cache first

        bool valid = false;

        hostInfo = manager->cache.get(toBeLookedUp, &valid);

        if (!valid) {

            // not in cache, we need to do the lookup and store the result in the cache

            hostInfo = QHostInfoAgent::fromName(toBeLookedUp);

            manager->cache.put(toBeLookedUp, hostInfo);

        }

    } else {

        // cache is not enabled, just do the lookup and continue

        hostInfo = QHostInfoAgent::fromName(toBeLookedUp);

    }

    // check aborted again

    if (manager->wasAborted(id)) {

        manager->lookupFinished(this);

        return;

    }

    // signal emission

    hostInfo.setLookupId(id);

    resultEmitter.emitResultsReady(hostInfo);

    // now also iterate through the postponed ones

    {

        QMutexLocker locker(&manager->mutex);

        QMutableListIterator<QHostInfoRunnable*> iterator(manager->postponedLookups);

        while (iterator.hasNext()) {

            QHostInfoRunnable* postponed = iterator.next();

            if (toBeLookedUp == postponed->toBeLookedUp) {

                // we can now emit

                iterator.remove();

                hostInfo.setLookupId(postponed->id);

                postponed->resultEmitter.emitResultsReady(hostInfo);

                delete postponed;

            }

        }

    }

    manager->lookupFinished(this);

    // thread goes back to QThreadPool

}

QHostInfoLookupManager::QHostInfoLookupManager() : mutex(QMutex::Recursive), wasDeleted(false)

{

    moveToThread(QCoreApplicationPrivate::mainThread());

    connect(QCoreApplication::instance(), SIGNAL(destroyed()), SLOT(waitForThreadPoolDone()), Qt::DirectConnection);

    threadPool.setMaxThreadCount(5); // do 5 DNS lookups in parallel

}

QHostInfoLookupManager::~QHostInfoLookupManager()

{

    wasDeleted = true;

    // don't qDeleteAll currentLookups, the QThreadPool has ownership

    clear();

}

void QHostInfoLookupManager::clear()

{

    {

        QMutexLocker locker(&mutex);

        qDeleteAll(postponedLookups);

        qDeleteAll(scheduledLookups);

        qDeleteAll(finishedLookups);

        postponedLookups.clear();

        scheduledLookups.clear();

        finishedLookups.clear();

    }

    threadPool.waitForDone();

    cache.clear();

}

void QHostInfoLookupManager::work()

{

    if (wasDeleted)

        return;

    // goals of this function:

    //  - launch new lookups via the thread pool

    //  - make sure only one lookup per host/IP is in progress

    QMutexLocker locker(&mutex);

    if (!finishedLookups.isEmpty()) {

        // remove ID from aborted if it is in there

        for (int i = 0; i < finishedLookups.length(); i++) {

           abortedLookups.removeAll(finishedLookups.at(i)->id);

        }

        finishedLookups.clear();

    }

    if (!postponedLookups.isEmpty()) {

        // try to start the postponed ones

        QMutableListIterator<QHostInfoRunnable*> iterator(postponedLookups);

        while (iterator.hasNext()) {

            QHostInfoRunnable* postponed = iterator.next();

            // check if none of the postponed hostnames is currently running

            bool alreadyRunning = false;

            for (int i = 0; i < currentLookups.length(); i++) {

                if (currentLookups.at(i)->toBeLookedUp == postponed->toBeLookedUp) {

                    alreadyRunning = true;

                    break;

                }

            }

            if (!alreadyRunning) {

                iterator.remove();

                scheduledLookups.prepend(postponed); // prepend! we want to finish it ASAP

            }

        }

    }

    if (!scheduledLookups.isEmpty()) {

        // try to start the new ones

        QMutableListIterator<QHostInfoRunnable*> iterator(scheduledLookups);

        while (iterator.hasNext()) {

            QHostInfoRunnable *scheduled = iterator.next();

            // check if a lookup for this host is already running, then postpone

            for (int i = 0; i < currentLookups.size(); i++) {

                if (currentLookups.at(i)->toBeLookedUp == scheduled->toBeLookedUp) {

                    iterator.remove();

                    postponedLookups.append(scheduled);

                    scheduled = 0;

                    break;

                }

            }

            if (scheduled && currentLookups.size() < threadPool.maxThreadCount()) {

                // runnable now running in new thread, track this in currentLookups

                threadPool.start(scheduled);

                iterator.remove();

                currentLookups.append(scheduled);

            } else {

                // was postponed, continue iterating

                continue;

            }

        };

    }

}

// called by QHostInfo

void QHostInfoLookupManager::scheduleLookup(QHostInfoRunnable *r)

{

    if (wasDeleted)

        return;

    QMutexLocker locker(&this->mutex);

    scheduledLookups.enqueue(r);

    work();

}

// called by QHostInfo

void QHostInfoLookupManager::abortLookup(int id)

{

    if (wasDeleted)

        return;

    QMutexLocker locker(&this->mutex);

    // is postponed? delete and return

    for (int i = 0; i < postponedLookups.length(); i++) {

        if (postponedLookups.at(i)->id == id) {

            delete postponedLookups.takeAt(i);

            return;

        }

    }

    // is scheduled? delete and return

    for (int i = 0; i < scheduledLookups.length(); i++) {

        if (scheduledLookups.at(i)->id == id) {

            delete scheduledLookups.takeAt(i);

            return;

        }

    }

    if (!abortedLookups.contains(id))

        abortedLookups.append(id);

}

// called from QHostInfoRunnable

bool QHostInfoLookupManager::wasAborted(int id)

{

    if (wasDeleted)

        return true;

    QMutexLocker locker(&this->mutex);

    return abortedLookups.contains(id);

}

// called from QHostInfoRunnable

void QHostInfoLookupManager::lookupFinished(QHostInfoRunnable *r)

{

    if (wasDeleted)

        return;

    QMutexLocker locker(&this->mutex);

    currentLookups.removeOne(r);

    finishedLookups.append(r);

    work();

}

#endif

// This function returns immediately when we had a result in the cache, else it will later emit a signal

QHostInfo qt_qhostinfo_lookup(const QString &name, QObject *receiver, const char *member, bool *valid, int *id)

{

    *valid = false;

    *id = -1;

    // check cache

    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();

    if (manager && manager->cache.isEnabled()) {

        QHostInfo info = manager->cache.get(name, valid);

        if (*valid) {

            return info;

        }

    }

    // was not in cache, trigger lookup

    *id = QHostInfo::lookupHost(name, receiver, member);

    // return empty response, valid==false

    return QHostInfo();

}

void qt_qhostinfo_clear_cache()

{

    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();

    if (manager) {

        manager->clear();

    }

}

void Q_AUTOTEST_EXPORT qt_qhostinfo_enable_cache(bool e)

{

    QAbstractHostInfoLookupManager* manager = theHostInfoLookupManager();

    if (manager) {

        manager->cache.setEnabled(e);

    }

}

// cache for 60 seconds

// cache 64 items

QHostInfoCache::QHostInfoCache() : max_age(60), enabled(true), cache(64)

{

#ifdef QT_QHOSTINFO_CACHE_DISABLED_BY_DEFAULT

    enabled = false;

#endif

}

bool QHostInfoCache::isEnabled()

{

    return enabled;

}

// this function is currently only used for the auto tests

// and not usable by public API

void QHostInfoCache::setEnabled(bool e)

{

    enabled = e;

}

QHostInfo QHostInfoCache::get(const QString &name, bool *valid)

{

    QMutexLocker locker(&this->mutex);

    *valid = false;

    if (cache.contains(name)) {

        QHostInfoCacheElement *element = cache.object(name);

        if (element->age.elapsed() < max_age*1000)

            *valid = true;

        return element->info;

        // FIXME idea:

        // if too old but not expired, trigger a new lookup

        // to freshen our cache

    }

    return QHostInfo();

}

void QHostInfoCache::put(const QString &name, const QHostInfo &info)

{

    // if the lookup failed, don't cache

    if (info.error() != QHostInfo::NoError)

        return;

    QHostInfoCacheElement* element = new QHostInfoCacheElement();

    element->info = info;

    element->age = QElapsedTimer();

    element->age.start();

    QMutexLocker locker(&this->mutex);

    cache.insert(name, element); // cache will take ownership

}

void QHostInfoCache::clear()

{

    QMutexLocker locker(&this->mutex);

    cache.clear();

}

QAbstractHostInfoLookupManager* QAbstractHostInfoLookupManager::globalInstance()

{

    return theHostInfoLookupManager();

}

QT_END_NAMESPACE