QDnsLookup: add support for setting the port number of the server

I couldn't make my Windows 10 or 11 query a non-standard port. It kept
complaining about "The parameter is incorrect.", so as a result the unit
test doesn't actually test the new feature there. I can't find a single
example of this on the Internet; my speculation is that the backend API
that DnsQueryEx uses does not support setting port numbers
(DnsQuery_{A,W} didn't offer that option).

[ChangeLog][QtNetwork][QDnsLookup] Added setNameserverPort().

Change-Id: I3e3bfef633af4130a03afffd175d60a581cc0a9c
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

src/network/kernel/qdnslookup.cpp

@@ -244,16 +244,39 @@ QDnsLookup::QDnsLookup(Type type, const QString &name, QObject *parent)
 /*!
     \fn QDnsLookup::QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, QObject *parent)
     \since 5.4
-    Constructs a QDnsLookup object for the given \a type, \a name and
+
-    \a nameserver and sets \a parent as the parent object.
+    Constructs a QDnsLookup object to issue a query for \a name of record type
+    \a type, using the DNS server \a nameserver running on the default DNS port,
+    and sets \a parent as the parent object.
 */
 
 QDnsLookup::QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, QObject *parent)
+    : QDnsLookup(type, name, nameserver, DnsPort, parent)
+{
+}
+
+/*!
+    \fn QDnsLookup::QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, quint16 port, QObject *parent)
+    \since 6.6
+
+    Constructs a QDnsLookup object to issue a query for \a name of record type
+    \a type, using the DNS server \a nameserver running on port \a port, and
+    sets \a parent as the parent object.
+
+//! [nameserver-port]
+    \note Setting the port number to any value other than the default (53) can
+    cause the name resolution to fail, depending on the operating system
+    limitations and firewalls. Notably, the Windows API used by QDnsLookup is
+    unable to handle alternate port numbers.
+//! [nameserver-port]
+*/
+QDnsLookup::QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, quint16 port, QObject *parent)
     : QObject(*new QDnsLookupPrivate, parent)
 {
     Q_D(QDnsLookup);
     d->name = name;
     d->type = type;
+    d->port = port;
     d->nameserver = nameserver;
 }
 
@@ -366,6 +389,46 @@ QBindable<QHostAddress> QDnsLookup::bindableNameserver()
     return &d->nameserver;
 }
 
+/*!
+    \property QDnsLookup::nameserverPort
+    \since 6.6
+    \brief the port number of nameserver to use for DNS lookup.
+    \include qdnslookup.cpp nameserver-port
+*/
+
+quint16 QDnsLookup::nameserverPort() const
+{
+    return d_func()->port;
+}
+
+void QDnsLookup::setNameserverPort(quint16 nameserverPort)
+{
+    Q_D(QDnsLookup);
+    d->port = nameserverPort;
+}
+
+QBindable<quint16> QDnsLookup::bindableNameserverPort()
+{
+    Q_D(QDnsLookup);
+    return &d->port;
+}
+
+/*!
+    \since 6.6
+    Sets the nameserver to \a nameserver and the port to \a port.
+
+    \include qdnslookup.cpp nameserver-port
+
+    \sa QDnsLookup::nameserver, QDnsLookup::nameserverPort
+*/
+void QDnsLookup::setNameserver(const QHostAddress &nameserver, quint16 port)
+{
+    Qt::beginPropertyUpdateGroup();
+    setNameserver(nameserver);
+    setNameserverPort(port);
+    Qt::endPropertyUpdateGroup();
+}
+
 /*!
     Returns the list of canonical name records associated with this lookup.
 */
@@ -965,7 +1028,8 @@ void QDnsLookupPrivate::_q_lookupFinished(const QDnsLookupReply &_reply)
 inline QDnsLookupRunnable::QDnsLookupRunnable(const QDnsLookupPrivate *d)
     : requestName(QUrl::toAce(d->name)),
       nameserver(d->nameserver),
-      requestType(d->type)
+      requestType(d->type),
+      port(d->port)
 {
 }
 

src/network/kernel/qdnslookup.h

@@ -146,6 +146,8 @@ class Q_NETWORK_EXPORT QDnsLookup : public QObject
     Q_PROPERTY(Type type READ type WRITE setType NOTIFY typeChanged BINDABLE bindableType)
     Q_PROPERTY(QHostAddress nameserver READ nameserver WRITE setNameserver NOTIFY nameserverChanged
                BINDABLE bindableNameserver)
+    Q_PROPERTY(quint16 nameserverPort READ nameserverPort WRITE setNameserverPort
+               NOTIFY nameserverPortChanged BINDABLE bindableNameserverPort)
 
 public:
     enum Error
@@ -178,6 +180,8 @@ public:
     explicit QDnsLookup(QObject *parent = nullptr);
     QDnsLookup(Type type, const QString &name, QObject *parent = nullptr);
     QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, QObject *parent = nullptr);
+    QDnsLookup(Type type, const QString &name, const QHostAddress &nameserver, quint16 port,
+               QObject *parent = nullptr);
     ~QDnsLookup();
 
     Error error() const;
@@ -195,6 +199,10 @@ public:
     QHostAddress nameserver() const;
     void setNameserver(const QHostAddress &nameserver);
     QBindable<QHostAddress> bindableNameserver();
+    quint16 nameserverPort() const;
+    void setNameserverPort(quint16 port);
+    QBindable<quint16> bindableNameserverPort();
+    void setNameserver(const QHostAddress &nameserver, quint16 port);
 
     QList<QDnsDomainNameRecord> canonicalNameRecords() const;
     QList<QDnsHostAddressRecord> hostAddressRecords() const;
@@ -214,6 +222,7 @@ Q_SIGNALS:
     void nameChanged(const QString &name);
     void typeChanged(Type type);
     void nameserverChanged(const QHostAddress &nameserver);
+    void nameserverPortChanged(quint16 port);
 
 private:
     Q_DECLARE_PRIVATE(QDnsLookup)

src/network/kernel/qdnslookup_p.h

@@ -120,15 +120,12 @@ class QDnsLookupPrivate : public QObjectPrivate
 {
 public:
     QDnsLookupPrivate()
-        : isFinished(false)
+        : type(QDnsLookup::A)
-        , type(QDnsLookup::A)
+        , port(DnsPort)
-        , runnable(nullptr)
     { }
     void _q_lookupFinished(const QDnsLookupReply &reply);
 
 
-    bool isFinished;
-
     void nameChanged()
     {
         emit q_func()->nameChanged(name);
@@ -136,6 +133,13 @@ public:
     Q_OBJECT_BINDABLE_PROPERTY(QDnsLookupPrivate, QString, name,
                                &QDnsLookupPrivate::nameChanged);
 
+    void nameserverChanged()
+    {
+        emit q_func()->nameserverChanged(nameserver);
+    }
+    Q_OBJECT_BINDABLE_PROPERTY(QDnsLookupPrivate, QHostAddress, nameserver,
+                               &QDnsLookupPrivate::nameserverChanged);
+
     void typeChanged()
     {
         emit q_func()->typeChanged(type);
@@ -144,15 +148,18 @@ public:
     Q_OBJECT_BINDABLE_PROPERTY(QDnsLookupPrivate, QDnsLookup::Type,
                                type, &QDnsLookupPrivate::typeChanged);
 
-    void nameserverChanged()
+    void nameserverPortChanged()
     {
-        emit q_func()->nameserverChanged(nameserver);
+        emit q_func()->nameserverPortChanged(port);
     }
-    Q_OBJECT_BINDABLE_PROPERTY(QDnsLookupPrivate, QHostAddress, nameserver,
+
-                               &QDnsLookupPrivate::nameserverChanged);
+    Q_OBJECT_BINDABLE_PROPERTY(QDnsLookupPrivate, quint16,
+                               port, &QDnsLookupPrivate::nameserverPortChanged);
+
 
     QDnsLookupReply reply;
-    QDnsLookupRunnable *runnable;
+    QDnsLookupRunnable *runnable = nullptr;
+    bool isFinished = false;
 
     Q_DECLARE_PUBLIC(QDnsLookup)
 };
@@ -173,6 +180,7 @@ private:
     QByteArray requestName;
     QHostAddress nameserver;
     QDnsLookup::Type requestType;
+    quint16 port;
 };
 
 class QDnsLookupThreadPool : public QThreadPool

src/network/kernel/qdnslookup_unix.cpp

@@ -109,7 +109,7 @@ void QDnsLookupRunnable::query(QDnsLookupReply *reply)
     auto guard = qScopeGuard([&] { res_nclose(&state); });
 
     //Check if a nameserver was set. If so, use it
-    if (!applyNameServer(&state, nameserver, DnsPort)) {
+    if (!applyNameServer(&state, nameserver, port)) {
         qWarning("QDnsLookup: %s", "IPv6 nameservers are currently not supported on this OS");
         return reply->setError(QDnsLookup::ResolverError,
                                QDnsLookup::tr("IPv6 nameservers are currently not supported on this OS"));

src/network/kernel/qdnslookup_win.cpp

@@ -82,7 +82,7 @@ void QDnsLookupRunnable::query(QDnsLookupReply *reply)
         request.pDnsServerList->MaxCount = sizeof(dnsAddresses);
         request.pDnsServerList->AddrCount = 1;
         // ### setting port 53 seems to cause some systems to fail
-        setSockaddr(sa, nameserver, 0);
+        setSockaddr(sa, nameserver, port == DnsPort ? 0 : port);
         request.pDnsServerList->Family = sa->sa_family;
     }
 

tests/auto/network/kernel/qdnslookup/tst_qdnslookup.cpp

@@ -7,7 +7,11 @@
 #include <QSignalSpy>
 
 #include <QtNetwork/QDnsLookup>
+
+#include <QtCore/QRandomGenerator>
 #include <QtNetwork/QHostAddress>
+#include <QtNetwork/QNetworkDatagram>
+#include <QtNetwork/QUdpSocket>
 
 using namespace Qt::StringLiterals;
 static const int Timeout = 15000; // 15s
@@ -35,6 +39,7 @@ private slots:
 
     void lookupReuse();
     void lookupAbortRetry();
+    void setNameserverLoopback();
     void bindingsAndProperties();
 };
 
@@ -351,6 +356,62 @@ void tst_QDnsLookup::lookupAbortRetry()
     QCOMPARE(lookup.hostAddressRecords().first().value(), QHostAddress("2001:db8::1"));
 }
 
+void tst_QDnsLookup::setNameserverLoopback()
+{
+#ifdef Q_OS_WIN
+    // Windows doesn't like sending DNS requests to ports other than 53, so
+    // let's try it first.
+    constexpr quint16 DesiredPort = 53;
+#else
+    // Trying to bind to port 53 will fail on Unix systems unless this test is
+    // run as root, so we try mDNS's port (to help decoding in a packet capture).
+    constexpr quint16 DesiredPort = 5353;   // mDNS
+#endif
+    // random loopback address so multiple copies of this test can run
+    QHostAddress desiredAddress(0x7f000000 | QRandomGenerator::system()->bounded(0xffffff));
+
+    QUdpSocket server;
+    if (!server.bind(desiredAddress, DesiredPort)) {
+        // port in use, try a random one
+        server.bind(QHostAddress::LocalHost, 0);
+    }
+    QCOMPARE(server.state(), QUdpSocket::BoundState);
+
+    QDnsLookup lookup(QDnsLookup::Type::A, u"somelabel.somedomain"_s);
+    QSignalSpy spy(&lookup, SIGNAL(finished()));
+    lookup.setNameserver(server.localAddress(), server.localPort());
+
+    // QDnsLookup is threaded, so we can answer on the main thread
+    QObject::connect(&server, &QUdpSocket::readyRead,
+                     &QTestEventLoop::instance(), &QTestEventLoop::exitLoop);
+    QObject::connect(&lookup, &QDnsLookup::finished,
+                     &QTestEventLoop::instance(), &QTestEventLoop::exitLoop);
+    lookup.lookup();
+    QTestEventLoop::instance().enterLoop(5);
+    QVERIFY(!QTestEventLoop::instance().timeout());
+    QVERIFY2(spy.isEmpty(), qPrintable(lookup.errorString()));
+
+    QNetworkDatagram dgram = server.receiveDatagram();
+    QByteArray data = dgram.data();
+    QCOMPARE_GT(data.size(), HeaderSize);
+
+    quint8 opcode = (quint8(data.at(3)) >> 4) & 0xF;
+    QCOMPARE(opcode, 0);        // standard query
+
+    // send an NXDOMAIN reply to release the lookup thread
+    QByteArray reply = data;
+    reply[2] = 0x80;    // header->qr = true;
+    reply[3] = 3;       // header->rcode = NXDOMAIN;
+    server.writeDatagram(dgram.makeReply(reply));
+    server.close();
+
+    // now check that the QDnsLookup finished
+    QTestEventLoop::instance().enterLoop(5);
+    QVERIFY(!QTestEventLoop::instance().timeout());
+    QCOMPARE(spy.size(), 1);
+    QCOMPARE(lookup.error(), QDnsLookup::NotFoundError);
+}
+
 void tst_QDnsLookup::bindingsAndProperties()
 {
     QDnsLookup lookup;
@@ -383,14 +444,23 @@ void tst_QDnsLookup::bindingsAndProperties()
     QProperty<QHostAddress> nameserverProp;
     lookup.bindableNameserver().setBinding(Qt::makePropertyBinding(nameserverProp));
     const QSignalSpy nameserverChangeSpy(&lookup, &QDnsLookup::nameserverChanged);
+    const QSignalSpy nameserverPortChangeSpy(&lookup, &QDnsLookup::nameserverPortChanged);
 
     nameserverProp = QHostAddress::LocalHost;
     QCOMPARE(nameserverChangeSpy.size(), 1);
+    QCOMPARE(nameserverPortChangeSpy.size(), 0);
     QCOMPARE(lookup.nameserver(), QHostAddress::LocalHost);
 
     nameserverProp.setBinding(lookup.bindableNameserver().makeBinding());
     lookup.setNameserver(QHostAddress::Any);
     QCOMPARE(nameserverProp.value(), QHostAddress::Any);
+    QCOMPARE(nameserverChangeSpy.size(), 2);
+    QCOMPARE(nameserverPortChangeSpy.size(), 0);
+
+    lookup.setNameserver(QHostAddress::LocalHostIPv6, 10053);
+    QCOMPARE(nameserverProp.value(), QHostAddress::LocalHostIPv6);
+    QCOMPARE(nameserverChangeSpy.size(), 3);
+    QCOMPARE(nameserverPortChangeSpy.size(), 1);
 }
 
 QTEST_MAIN(tst_QDnsLookup)

tests/manual/qdnslookup/main.cpp

@@ -6,6 +6,7 @@
 #include <QtCore/QElapsedTimer>
 #include <QtCore/QMetaEnum>
 #include <QtCore/QTimer>
+#include <QtCore/QUrl>
 #include <QtNetwork/QHostAddress>
 #include <QtNetwork/QHostInfo>
 #include <QtNetwork/QDnsLookup>
@@ -38,6 +39,24 @@ static int showHelp(const char *argv0, int exitcode)
     return exitcode;
 }
 
+static auto parseServerAddress(QString server)
+{
+    struct R {
+        QHostAddress address;
+        int port = -1;
+    } r;
+
+    // let's use QUrl to help us
+    QUrl url;
+    url.setAuthority(server);
+    if (!url.isValid() || !url.userInfo().isNull())
+        return r;           // failed
+
+    r.port = url.port();
+    r.address.setAddress(url.host());
+    return r;
+}
+
 static void printAnswers(const QDnsLookup &lookup)
 {
     printf("\n;; ANSWER:\n");
@@ -96,7 +115,7 @@ static void printResults(const QDnsLookup &lookup, QElapsedTimer::Duration durat
 
     printf("\n;; Query time: %lld ms\n", qint64(duration_cast<milliseconds>(duration).count()));
     if (QHostAddress server = lookup.nameserver(); !server.isNull())
-        printf(";; SERVER: %s#53\n", qPrintable(server.toString()));
+        printf(";; SERVER: %s#%d\n", qPrintable(server.toString()), lookup.nameserverPort());
 }
 
 int main(int argc, char *argv[])
@@ -138,15 +157,15 @@ int main(int argc, char *argv[])
 
     QDnsLookup lookup(type, domain);
     if (!server.isEmpty()) {
-        QHostAddress addr(server);
+        auto addr = parseServerAddress(server);
-        if (addr.isNull())
+        if (addr.address.isNull()) {
-            addr = QHostInfo::fromName(server).addresses().value(0);
-        if (addr.isNull()) {
             fprintf(stderr, "%s: could not parse name server address '%s'\n",
                     argv[0], qPrintable(server));
             return EXIT_FAILURE;
         }
-        lookup.setNameserver(addr);
+        lookup.setNameserver(addr.address);
+        if (addr.port > 0)
+            lookup.setNameserverPort(addr.port);
     }
 
     // execute the lookup