QDnsLookup Class

void MyObject::lookupServers()
{
    // Create a DNS lookup.
    dns = new QDnsLookup(this);
    connect(dns, &QDnsLookup::finished, this, &MyObject::handleServers);

    // Find the XMPP servers for gmail.com
    dns->setType(QDnsLookup::SRV);
    dns->setName("_xmpp-client._tcp.gmail.com");
    dns->lookup();
}

void MyObject::handleServers()
{
    // Check the lookup succeeded.
    if (dns->error() != QDnsLookup::NoError) {
        qWarning("DNS lookup failed");
        dns->deleteLater();
        return;
    }

    // Handle the results.
    const auto records = dns->serviceRecords();
    for (const QDnsServiceRecord &record : records) {
        ...
    }
    dns->deleteLater();
}

Member Function Documentation

[explicit] QDnsLookup::QDnsLookup(QObject *parent = nullptr)

Constructs a QDnsLookup object and sets parent as the parent object.

The type property will default to QDnsLookup::A.

QDnsLookup::QDnsLookup(QDnsLookup::Type type, const QString &name, QObject *parent = nullptr)

Constructs a QDnsLookup object for the given type and name and sets parent as the parent object.

QDnsLookup::QDnsLookup(QDnsLookup::Type type, const QString &name, const QHostAddress &nameserver, QObject *parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type, using the DNS server nameserver running on the default DNS port, and sets parent as the parent object.

[since 6.6] QDnsLookup::QDnsLookup(QDnsLookup::Type type, const QString &name, const QHostAddress &nameserver, quint16 port, QObject *parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type, using the DNS server nameserver running on port port, and sets parent as the parent object.

This function was introduced in Qt 6.6.

[since 6.8] QDnsLookup::QDnsLookup(QDnsLookup::Type type, const QString &name, QDnsLookup::Protocol protocol, const QHostAddress &nameserver, quint16 port = 0, QObject *parent = nullptr)

Constructs a QDnsLookup object to issue a query for name of record type type, using the DNS server nameserver running on port port, and sets parent as the parent object.

The query will be sent using protocol, if supported. Use isProtocolSupported() to check if it is supported.

This function was introduced in Qt 6.8.

[virtual noexcept] QDnsLookup::~QDnsLookup()

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.

[slot] void QDnsLookup::abort()

Aborts the DNS lookup operation.

If the lookup is already finished, does nothing.

QList<QDnsDomainNameRecord> QDnsLookup::canonicalNameRecords() const

Returns the list of canonical name records associated with this lookup.

[static noexcept, since 6.8] quint16 QDnsLookup::defaultPortForProtocol(QDnsLookup::Protocol protocol)

Returns the standard (default) port number for the protocol protocol.

This function was introduced in Qt 6.8.

See also isProtocolSupported().

[signal] void QDnsLookup::finished()

This signal is emitted when the reply has finished processing.

QList<QDnsHostAddressRecord> QDnsLookup::hostAddressRecords() const

Returns the list of host address records associated with this lookup.

bool QDnsLookup::isFinished() const

Returns whether the reply has finished or was aborted.

[static, since 6.8] bool QDnsLookup::isProtocolSupported(QDnsLookup::Protocol protocol)

Returns true if DNS queries using protocol are supported with QDnsLookup.

This function was introduced in Qt 6.8.

See also nameserverProtocol.

[slot] void QDnsLookup::lookup()

Performs the DNS lookup.

The finished() signal is emitted upon completion.

QList<QDnsMailExchangeRecord> QDnsLookup::mailExchangeRecords() const

Returns the list of mail exchange records associated with this lookup.

The records are sorted according to RFC 5321, so if you use them to connect to servers, you should try them in the order they are listed.

[signal] void QDnsLookup::nameChanged(const QString &name)

This signal is emitted when the lookup name changes. name is the new lookup name.

QList<QDnsDomainNameRecord> QDnsLookup::nameServerRecords() const

Returns the list of name server records associated with this lookup.

QList<QDnsDomainNameRecord> QDnsLookup::pointerRecords() const

Returns the list of pointer records associated with this lookup.

QList<QDnsServiceRecord> QDnsLookup::serviceRecords() const

Returns the list of service records associated with this lookup.

The records are sorted according to RFC 2782, so if you use them to connect to servers, you should try them in the order they are listed.

[since 6.6] void QDnsLookup::setNameserver(const QHostAddress &nameserver, quint16 port)

Sets the nameserver to nameserver and the port to port.

This function was introduced in Qt 6.6.

See also QDnsLookup::nameserver and QDnsLookup::nameserverPort.

[since 6.8] void QDnsLookup::setSslConfiguration(const QSslConfiguration &sslConfiguration)

Sets the sslConfiguration to use for outgoing DNS-over-TLS connections.

This function was introduced in Qt 6.8.

See also sslConfiguration() and QSslSocket::setSslConfiguration().

QSslConfiguration QDnsLookup::sslConfiguration() const

Returns the current SSL configuration.

See also setSslConfiguration().

QList<QDnsTextRecord> QDnsLookup::textRecords() const

Returns the list of text records associated with this lookup.

[since 6.8] QList<QDnsTlsAssociationRecord> QDnsLookup::tlsAssociationRecords() const

Returns the list of TLS association records associated with this lookup.

According to the standards relating to DNS-based Authentication of Named Entities (DANE), this field should be ignored and must not be used for verifying the authentity of a given server if the authenticity of the DNS reply cannot itself be confirmed. See isAuthenticData() for more information.

This function was introduced in Qt 6.8.

[signal] void QDnsLookup::typeChanged(QDnsLookup::Type type)

This signal is emitted when the lookup type changes. type is the new lookup type.