Add support for DNS lookups using native APIs

The QDnsLookup class provides asynchronous APIs for performing
DNS lookups. For now, the following lookups are supported:
- A and AAAA
- CNAME as defined per RFC 1035
- MX as defined per RFC 1035
- NS as defined per RFC 1035
- PTR as defined per RFC 1035
- SRV as defined per RFC 2782
- TXT as defined per RFC 1035

Task-number: QTBUG-10481
Change-Id: I46c1741ec23615863eeca3a1231d5e3f8942495e
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 988 insertions, 0 deletions

diff --git a/src/network/kernel/qdnslookup.cpp b/src/network/kernel/qdnslookup.cpp
new file mode 100644
index 0000000000..f4b143a5fc
--- /dev/null
+++ b/src/network/kernel/qdnslookup.cpp
@@ -0,0 +1,988 @@
+/****************************************************************************
+**
+** Copyright (C) 2012 Jeremy Lainé <jeremy.laine@m4x.org>
+** Contact: http://www.qt-project.org/
+**
+** 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
+** Public License version 3.0 requirements will be met:
+** http://www.gnu.org/copyleft/gpl.html.
+**
+** Other Usage
+** Alternatively, this file may be used in accordance with the terms and
+** conditions contained in a signed written agreement between you and Nokia.
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qdnslookup.h"
+#include "qdnslookup_p.h"
+
+#include <qcoreapplication.h>
+#include <qdatetime.h>
+#include <qthreadstorage.h>
+#include <qurl.h>
+
+QT_BEGIN_NAMESPACE
+
+Q_GLOBAL_STATIC(QDnsLookupThreadPool, theDnsLookupThreadPool);
+Q_GLOBAL_STATIC(QThreadStorage<bool *>, theDnsLookupSeedStorage);
+
+static bool qt_qdnsmailexchangerecord_less_than(const QDnsMailExchangeRecord &r1, const QDnsMailExchangeRecord &r2)
+{
+    // Lower numbers are more preferred than higher ones.
+    return r1.preference() < r2.preference();
+}
+
+/*!
+    Sorts a list of QDnsMailExchangeRecord objects according to RFC 5321.
+*/
+
+static void qt_qdnsmailexchangerecord_sort(QList<QDnsMailExchangeRecord> &records)
+{
+    // If we have no more than one result, we are done.
+    if (records.size() <= 1)
+        return;
+
+    // Order the records by preference.
+    qSort(records.begin(), records.end(), qt_qdnsmailexchangerecord_less_than);
+
+    int i = 0;
+    while (i < records.size()) {
+
+        // Determine the slice of records with the current preference.
+        QList<QDnsMailExchangeRecord> slice;
+        const quint16 slicePreference = records[i].preference();
+        for (int j = i; j < records.size(); ++j) {
+            if (records[j].preference() != slicePreference)
+                break;
+            slice << records[j];
+        }
+
+        // Randomize the slice of records.
+        while (!slice.isEmpty()) {
+            const unsigned int pos = qrand() % slice.size();
+            records[i++] = slice.takeAt(pos);
+        }
+    }
+}
+
+static bool qt_qdnsservicerecord_less_than(const QDnsServiceRecord &r1, const QDnsServiceRecord &r2)
+{
+    // Order by priority, or if the priorities are equal,
+    // put zero weight records first.
+    return r1.priority() < r2.priority()
+       || (r1.priority() == r2.priority()
+        && r1.weight() == 0 && r2.weight() > 0);
+}
+
+/*!
+    Sorts a list of QDnsServiceRecord objects according to RFC 2782.
+*/
+
+static void qt_qdnsservicerecord_sort(QList<QDnsServiceRecord> &records)
+{
+    // If we have no more than one result, we are done.
+    if (records.size() <= 1)
+        return;
+
+    // Order the records by priority, and for records with an equal
+    // priority, put records with a zero weight first.
+    qSort(records.begin(), records.end(), qt_qdnsservicerecord_less_than);
+
+    int i = 0;
+    while (i < records.size()) {
+
+        // Determine the slice of records with the current priority.
+        QList<QDnsServiceRecord> slice;
+        const quint16 slicePriority = records[i].priority();
+        unsigned int sliceWeight = 0;
+        for (int j = i; j < records.size(); ++j) {
+            if (records[j].priority() != slicePriority)
+                break;
+            sliceWeight += records[j].weight();
+            slice << records[j];
+        }
+#ifdef QDNSLOOKUP_DEBUG
+        qDebug("qt_qdnsservicerecord_sort() : priority %i (size: %i, total weight: %i)",
+               slicePriority, slice.size(), sliceWeight);
+#endif
+
+        // Order the slice of records.
+        while (!slice.isEmpty()) {
+            const unsigned int weightThreshold = qrand() % (sliceWeight + 1);
+            unsigned int summedWeight = 0;
+            for (int j = 0; j < slice.size(); ++j) {
+                summedWeight += slice[j].weight();
+                if (summedWeight >= weightThreshold) {
+#ifdef QDNSLOOKUP_DEBUG
+                    qDebug("qt_qdnsservicerecord_sort() : adding %s %i (weight: %i)",
+                           qPrintable(slice[j].target()), slice[j].port(),
+                           slice[j].weight());
+#endif
+                    // Adjust the slice weight and take the current record.
+                    sliceWeight -= slice[j].weight();
+                    records[i++] = slice.takeAt(j);
+                    break;
+                }
+            }
+        }
+    }
+}
+
+/*!
+    \class QDnsLookup
+    \brief The QDnsLookup class represents a DNS lookup.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    QDnsLookup uses the mechanisms provided by the operating system to perform
+    DNS lookups. To perform a lookup you need to specify a \l name and \l type
+    then invoke the \l{QDnsLookup::lookup()}{lookup()} slot. The
+    \l{QDnsLookup::finished()}{finished()} signal will be emitted upon
+    completion.
+
+    For example, you can determine which servers an XMPP chat client should
+    connect to for a given domain with:
+
+    \snippet doc/src/snippets/code/src_network_kernel_qdnslookup.cpp 0
+
+    Once the request finishes you can handle the results with:
+
+    \snippet doc/src/snippets/code/src_network_kernel_qdnslookup.cpp 1
+
+    \note If you simply want to find the IP address(es) associated with a host
+    name, or the host name associated with an IP address you should use
+    QHostInfo instead.
+*/
+
+/*!
+    \enum QDnsLookup::Error
+
+    Indicates all possible error conditions found during the
+    processing of the DNS lookup.
+
+    \value NoError              no error condition.
+
+    \value ResolverError        there was an error initializing the system's
+    DNS resolver.
+
+    \value OperationCancelledError  the lookup was aborted using the abort()
+    method.
+
+    \value InvalidRequestError  the requested DNS lookup was invalid.
+
+    \value InvalidReplyError    the reply returned by the server was invalid.
+
+    \value ServerFailureError   the server encountered an internal failure
+    while processing the request (SERVFAIL).
+
+    \value ServerRefusedError   the server refused to process the request for
+    security or policy reasons (REFUSED).
+
+    \value NotFoundError        the requested domain name does not exist
+    (NXDOMAIN).
+*/
+
+/*!
+    \enum QDnsLookup::Type
+
+    Indicates the type of DNS lookup that was performed.
+
+    \value A        IPv4 address records.
+
+    \value AAAA     IPv6 address records.
+
+    \value ANY      any records.
+
+    \value CNAME    canonical name records.
+
+    \value MX       mail exchange records.
+
+    \value NS       name server records.
+
+    \value PTR      pointer records.
+
+    \value SRV      service records.
+
+    \value TXT      text records.
+*/
+
+/*!
+    \fn void QDnsLookup::finished()
+
+    This signal is emitted when the reply has finished processing.
+*/
+
+/*!
+    \fn void QDnsLookup::nameChanged(const QString &name)
+
+    This signal is emitted when the lookup \l name changes.
+    \a name is the new lookup name.
+*/
+
+/*!
+    \fn void QDnsLookup::typeChanged(Type type)
+
+    This signal is emitted when the lookup \l type changes.
+    \a type is the new lookup type.
+*/
+
+/*!
+    Constructs a QDnsLookup object and sets \a parent as the parent object.
+
+    The \l type property will default to QDnsLookup::A.
+*/
+
+QDnsLookup::QDnsLookup(QObject *parent)
+    : QObject(*new QDnsLookupPrivate, parent)
+{
+    qRegisterMetaType<QDnsLookupReply>();
+}
+/*!
+    Constructs a QDnsLookup object for the given \a type and \a name and sets
+    \a parent as the parent object.
+*/
+
+QDnsLookup::QDnsLookup(Type type, const QString &name, QObject *parent)
+    : QObject(*new QDnsLookupPrivate, parent)
+{
+    Q_D(QDnsLookup);
+    qRegisterMetaType<QDnsLookupReply>();
+    d->name = name;
+    d->type = type;
+}
+
+/*!
+    Destroys the QDnsLookup object.
+
+    It is safe to delete a QDnsLookup object even if it is not finished, you
+    will simply never receive its results.
+*/
+
+QDnsLookup::~QDnsLookup()
+{
+}
+
+/*!
+    \property QDnsLookup::error
+    \brief the type of error that occurred if the DNS lookup failed, or NoError.
+*/
+
+QDnsLookup::Error QDnsLookup::error() const
+{
+    return d_func()->reply.error;
+}
+
+/*!
+    \property QDnsLookup::errorString
+    \brief a human-readable description of the error if the DNS lookup failed.
+*/
+
+QString QDnsLookup::errorString() const
+{
+    return d_func()->reply.errorString;
+}
+
+/*!
+    \property QDnsLookup::finished
+    \brief whether the reply has finished or was aborted.
+*/
+
+bool QDnsLookup::isFinished() const
+{
+    return d_func()->isFinished;
+}
+
+/*!
+    \property QDnsLookup::name
+    \brief the name to lookup.
+
+    \note The name will be encoded using IDNA, which means it's unsuitable for
+    querying SRV records compatible with the DNS-SD specification.
+*/
+
+QString QDnsLookup::name() const
+{
+    return d_func()->name;
+}
+
+void QDnsLookup::setName(const QString &name)
+{
+    Q_D(QDnsLookup);
+    if (name != d->name) {
+        d->name = name;
+        emit nameChanged(name);
+    }
+}
+
+/*!
+    \property QDnsLookup::type
+    \brief the type of DNS lookup.
+*/
+
+QDnsLookup::Type QDnsLookup::type() const
+{
+    return d_func()->type;
+}
+
+void QDnsLookup::setType(Type type)
+{
+    Q_D(QDnsLookup);
+    if (type != d->type) {
+        d->type = type;
+        emit typeChanged(type);
+    }
+}
+
+/*!
+    Returns the list of canonical name records associated with this lookup.
+*/
+
+QList<QDnsDomainNameRecord> QDnsLookup::canonicalNameRecords() const
+{
+    return d_func()->reply.canonicalNameRecords;
+}
+
+/*!
+    Returns the list of host address records associated with this lookup.
+*/
+
+QList<QDnsHostAddressRecord> QDnsLookup::hostAddressRecords() const
+{
+    return d_func()->reply.hostAddressRecords;
+}
+
+/*!
+    Returns the list of mail exchange records associated with this lookup.
+
+    The records are sorted according to
+    \l{http://www.rfc-editor.org/rfc/rfc5321.txt}{RFC 5321}, so if you use them
+    to connect to servers, you should try them in the order they are listed.
+*/
+
+QList<QDnsMailExchangeRecord> QDnsLookup::mailExchangeRecords() const
+{
+    return d_func()->reply.mailExchangeRecords;
+}
+
+/*!
+    Returns the list of name server records associated with this lookup.
+*/
+
+QList<QDnsDomainNameRecord> QDnsLookup::nameServerRecords() const
+{
+    return d_func()->reply.nameServerRecords;
+}
+
+/*!
+    Returns the list of pointer records associated with this lookup.
+*/
+
+QList<QDnsDomainNameRecord> QDnsLookup::pointerRecords() const
+{
+    return d_func()->reply.pointerRecords;
+}
+
+/*!
+    Returns the list of service records associated with this lookup.
+
+    The records are sorted according to
+    \l{http://www.rfc-editor.org/rfc/rfc2782.txt}{RFC 2782}, so if you use them
+    to connect to servers, you should try them in the order they are listed.
+*/
+
+QList<QDnsServiceRecord> QDnsLookup::serviceRecords() const
+{
+    return d_func()->reply.serviceRecords;
+}
+
+/*!
+    Returns the list of text records associated with this lookup.
+*/
+
+QList<QDnsTextRecord> QDnsLookup::textRecords() const
+{
+    return d_func()->reply.textRecords;
+}
+
+/*!
+    Aborts the DNS lookup operation.
+
+    If the lookup is already finished, does nothing.
+*/
+
+void QDnsLookup::abort()
+{
+    Q_D(QDnsLookup);
+    if (d->runnable) {
+        d->runnable = 0;
+        d->reply = QDnsLookupReply();
+        d->reply.error = QDnsLookup::OperationCancelledError;
+        d->reply.errorString = tr("Operation cancelled");
+        d->isFinished = true;
+        emit finished();
+    }
+}
+
+/*!
+    Performs the DNS lookup.
+
+    The \l{QDnsLookup::finished()}{finished()} signal is emitted upon completion.
+*/
+
+void QDnsLookup::lookup()
+{
+    Q_D(QDnsLookup);
+    d->isFinished = false;
+    d->reply = QDnsLookupReply();
+    d->runnable = new QDnsLookupRunnable(d->type, QUrl::toAce(d->name));
+    connect(d->runnable, SIGNAL(finished(QDnsLookupReply)),
+            this, SLOT(_q_lookupFinished(QDnsLookupReply)),
+            Qt::BlockingQueuedConnection);
+    theDnsLookupThreadPool()->start(d->runnable);
+}
+
+/*!
+    \class QDnsDomainNameRecord
+    \brief The QDnsDomainNameRecord class stores information about a domain
+    name record.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    When performing a name server lookup, zero or more records will be returned.
+    Each record is represented by a QDnsDomainNameRecord instance.
+
+    \sa QDnsLookup
+*/
+
+/*!
+    Constructs an empty domain name record object.
+*/
+
+QDnsDomainNameRecord::QDnsDomainNameRecord()
+    : d(new QDnsDomainNameRecordPrivate)
+{
+}
+
+/*!
+    Constructs a copy of \a other.
+*/
+
+QDnsDomainNameRecord::QDnsDomainNameRecord(const QDnsDomainNameRecord &other)
+    : d(other.d)
+{
+}
+
+/*!
+    Destroys a domain name record.
+*/
+
+QDnsDomainNameRecord::~QDnsDomainNameRecord()
+{
+}
+
+/*!
+    Returns the name for this record.
+*/
+
+QString QDnsDomainNameRecord::name() const
+{
+    return d->name;
+}
+
+/*!
+    Returns the duration in seconds for which this record is valid.
+*/
+
+quint32 QDnsDomainNameRecord::timeToLive() const
+{
+    return d->timeToLive;
+}
+
+/*!
+    Returns the value for this domain name record.
+*/
+
+QString QDnsDomainNameRecord::value() const
+{
+    return d->value;
+}
+
+/*!
+    Assigns the data of the \a other object to this record object,
+    and returns a reference to it.
+*/
+
+QDnsDomainNameRecord &QDnsDomainNameRecord::operator=(const QDnsDomainNameRecord &other)
+{
+    d = other.d;
+    return *this;
+}
+
+/*!
+    \class QDnsHostAddressRecord
+    \brief The QDnsHostAddressRecord class stores information about a host
+    address record.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    When performing an address lookup, zero or more records will be
+    returned. Each record is represented by a QDnsHostAddressRecord instance.
+
+    \sa QDnsLookup
+*/
+
+/*!
+    Constructs an empty host address record object.
+*/
+
+QDnsHostAddressRecord::QDnsHostAddressRecord()
+    : d(new QDnsHostAddressRecordPrivate)
+{
+}
+
+/*!
+    Constructs a copy of \a other.
+*/
+
+QDnsHostAddressRecord::QDnsHostAddressRecord(const QDnsHostAddressRecord &other)
+    : d(other.d)
+{
+}
+
+/*!
+    Destroys a host address record.
+*/
+
+QDnsHostAddressRecord::~QDnsHostAddressRecord()
+{
+}
+
+/*!
+    Returns the name for this record.
+*/
+
+QString QDnsHostAddressRecord::name() const
+{
+    return d->name;
+}
+
+/*!
+    Returns the duration in seconds for which this record is valid.
+*/
+
+quint32 QDnsHostAddressRecord::timeToLive() const
+{
+    return d->timeToLive;
+}
+
+/*!
+    Returns the value for this host address record.
+*/
+
+QHostAddress QDnsHostAddressRecord::value() const
+{
+    return d->value;
+}
+
+/*!
+    Assigns the data of the \a other object to this record object,
+    and returns a reference to it.
+*/
+
+QDnsHostAddressRecord &QDnsHostAddressRecord::operator=(const QDnsHostAddressRecord &other)
+{
+    d = other.d;
+    return *this;
+}
+
+/*!
+    \class QDnsMailExchangeRecord
+    \brief The QDnsMailExchangeRecord class stores information about a DNS MX record.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    When performing a lookup on a service, zero or more records will be
+    returned. Each record is represented by a QDnsMailExchangeRecord instance.
+
+    The meaning of the fields is defined in
+    \l{http://www.rfc-editor.org/rfc/rfc1035.txt}{RFC 1035}.
+
+    \sa QDnsLookup
+*/
+
+/*!
+    Constructs an empty mail exchange record object.
+*/
+
+QDnsMailExchangeRecord::QDnsMailExchangeRecord()
+    : d(new QDnsMailExchangeRecordPrivate)
+{
+}
+
+/*!
+    Constructs a copy of \a other.
+*/
+
+QDnsMailExchangeRecord::QDnsMailExchangeRecord(const QDnsMailExchangeRecord &other)
+    : d(other.d)
+{
+}
+
+/*!
+    Destroys a mail exchange record.
+*/
+
+QDnsMailExchangeRecord::~QDnsMailExchangeRecord()
+{
+}
+
+/*!
+    Returns the domain name of the mail exchange for this record.
+*/
+
+QString QDnsMailExchangeRecord::exchange() const
+{
+    return d->exchange;
+}
+
+/*!
+    Returns the name for this record.
+*/
+
+QString QDnsMailExchangeRecord::name() const
+{
+    return d->name;
+}
+
+/*!
+    Returns the preference for this record.
+*/
+
+quint16 QDnsMailExchangeRecord::preference() const
+{
+    return d->preference;
+}
+
+/*!
+    Returns the duration in seconds for which this record is valid.
+*/
+
+quint32 QDnsMailExchangeRecord::timeToLive() const
+{
+    return d->timeToLive;
+}
+
+/*!
+    Assigns the data of the \a other object to this record object,
+    and returns a reference to it.
+*/
+
+QDnsMailExchangeRecord &QDnsMailExchangeRecord::operator=(const QDnsMailExchangeRecord &other)
+{
+    d = other.d;
+    return *this;
+}
+
+/*!
+    \class QDnsServiceRecord
+    \brief The QDnsServiceRecord class stores information about a DNS SRV record.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    When performing a lookup on a service, zero or more records will be
+    returned. Each record is represented by a QDnsServiceRecord instance.
+
+    The meaning of the fields is defined in
+    \l{http://www.rfc-editor.org/rfc/rfc2782.txt}{RFC 2782}.
+
+    \sa QDnsLookup
+*/
+
+/*!
+    Constructs an empty service record object.
+*/
+
+QDnsServiceRecord::QDnsServiceRecord()
+    : d(new QDnsServiceRecordPrivate)
+{
+}
+
+/*!
+    Constructs a copy of \a other.
+*/
+
+QDnsServiceRecord::QDnsServiceRecord(const QDnsServiceRecord &other)
+    : d(other.d)
+{
+}
+
+/*!
+    Destroys a service record.
+*/
+
+QDnsServiceRecord::~QDnsServiceRecord()
+{
+}
+
+/*!
+    Returns the name for this record.
+*/
+
+QString QDnsServiceRecord::name() const
+{
+    return d->name;
+}
+
+/*!
+    Returns the port on the target host for this service record.
+*/
+
+quint16 QDnsServiceRecord::port() const
+{
+    return d->port;
+}
+
+/*!
+    Returns the priority for this service record.
+
+    A client must attempt to contact the target host with the lowest-numbered
+    priority.
+*/
+
+quint16 QDnsServiceRecord::priority() const
+{
+    return d->priority;
+}
+
+/*!
+    Returns the domain name of the target host for this service record.
+*/
+
+QString QDnsServiceRecord::target() const
+{
+    return d->target;
+}
+
+/*!
+    Returns the duration in seconds for which this record is valid.
+*/
+
+quint32 QDnsServiceRecord::timeToLive() const
+{
+    return d->timeToLive;
+}
+
+/*!
+    Returns the weight for this service record.
+
+    The weight field specifies a relative weight for entries with the same
+    priority. Entries with higher weights should be selected with a higher
+    probability.
+*/
+
+quint16 QDnsServiceRecord::weight() const
+{
+    return d->weight;
+}
+
+/*!
+    Assigns the data of the \a other object to this record object,
+    and returns a reference to it.
+*/
+
+QDnsServiceRecord &QDnsServiceRecord::operator=(const QDnsServiceRecord &other)
+{
+    d = other.d;
+    return *this;
+}
+
+/*!
+    \class QDnsTextRecord
+    \brief The QDnsTextRecord class stores information about a DNS TXT record.
+
+    \inmodule QtNetwork
+    \ingroup network
+
+    When performing a text lookup, zero or more records will be
+    returned. Each record is represented by a QDnsTextRecord instance.
+
+    The meaning of the fields is defined in
+    \l{http://www.rfc-editor.org/rfc/rfc1035.txt}{RFC 1035}.
+
+    \sa QDnsLookup
+*/
+
+/*!
+    Constructs an empty text record object.
+*/
+
+QDnsTextRecord::QDnsTextRecord()
+    : d(new QDnsTextRecordPrivate)
+{
+}
+
+/*!
+    Constructs a copy of \a other.
+*/
+
+QDnsTextRecord::QDnsTextRecord(const QDnsTextRecord &other)
+    : d(other.d)
+{
+}
+
+/*!
+    Destroys a text record.
+*/
+
+QDnsTextRecord::~QDnsTextRecord()
+{
+}
+
+/*!
+    Returns the name for this text record.
+*/
+
+QString QDnsTextRecord::name() const
+{
+    return d->name;
+}
+
+/*!
+    Returns the duration in seconds for which this record is valid.
+*/
+
+quint32 QDnsTextRecord::timeToLive() const
+{
+    return d->timeToLive;
+}
+
+/*!
+    Returns the values for this text record.
+*/
+
+QList<QByteArray> QDnsTextRecord::values() const
+{
+    return d->values;
+}
+
+/*!
+    Assigns the data of the \a other object to this record object,
+    and returns a reference to it.
+*/
+
+QDnsTextRecord &QDnsTextRecord::operator=(const QDnsTextRecord &other)
+{
+    d = other.d;
+    return *this;
+}
+
+void QDnsLookupPrivate::_q_lookupFinished(const QDnsLookupReply &_reply)
+{
+    Q_Q(QDnsLookup);
+    if (runnable == q->sender()) {
+#ifdef QDNSLOOKUP_DEBUG
+        qDebug("DNS reply for %s: %i (%s)", qPrintable(name), _reply.error, qPrintable(_reply.errorString));
+#endif
+        reply = _reply;
+        runnable = 0;
+        isFinished = true;
+        emit q->finished();
+    }
+}
+
+void QDnsLookupRunnable::run()
+{
+    QDnsLookupReply reply;
+
+    // Validate input.
+    if (requestName.isEmpty()) {
+        reply.error = QDnsLookup::InvalidRequestError;
+        reply.errorString = tr("Invalid domain name");
+        emit finished(reply);
+        return;
+    }
+
+    // Perform request.
+    query(requestType, requestName, &reply);
+
+    // Sort results.
+    if (!theDnsLookupSeedStorage()->hasLocalData()) {
+        qsrand(QTime(0,0,0).msecsTo(QTime::currentTime()) ^ reinterpret_cast<quintptr>(this));
+        theDnsLookupSeedStorage()->setLocalData(new bool(true));
+    }
+    qt_qdnsmailexchangerecord_sort(reply.mailExchangeRecords);
+    qt_qdnsservicerecord_sort(reply.serviceRecords);
+
+    emit finished(reply);
+}
+
+QDnsLookupThreadPool::QDnsLookupThreadPool()
+    : signalsConnected(false)
+{
+    // Run up to 5 lookups in parallel.
+    setMaxThreadCount(5);
+}
+
+void QDnsLookupThreadPool::start(QRunnable *runnable)
+{
+    // Ensure threads complete at application destruction.
+    if (!signalsConnected) {
+        QMutexLocker signalsLocker(&signalsMutex);
+        if (!signalsConnected) {
+            QCoreApplication *app = QCoreApplication::instance();
+            if (!app) {
+                qWarning("QDnsLookup requires a QCoreApplication");
+                delete runnable;
+                return;
+            }
+
+            moveToThread(app->thread());
+            connect(app, SIGNAL(destroyed()),
+                SLOT(_q_applicationDestroyed()), Qt::DirectConnection);
+            signalsConnected = true;
+        }
+    }
+
+    QThreadPool::start(runnable);
+}
+
+void QDnsLookupThreadPool::_q_applicationDestroyed()
+{
+    waitForDone();
+    signalsConnected = false;
+}
+
+QT_END_NAMESPACE
+
+#include "moc_qdnslookup.cpp"