Merge remote-tracking branch 'origin/5.13' into dev

Change-Id: If912f4f8c24075c6947f5c22bb70bdba57d1e8ae

22 files changed, 290 insertions, 103 deletions

diff --git a/examples/coap/doc/images/quickmulticastclient.png b/examples/coap/doc/images/quickmulticastclient.png
new file mode 100644
index 0000000..3339db1
--- /dev/null
+++ b/examples/coap/doc/images/quickmulticastclient.png
diff --git a/examples/coap/doc/quickmulticastclient.qdoc b/examples/coap/doc/quickmulticastclient.qdoc
index c3295c5..25d86b6 100644
--- a/examples/coap/doc/quickmulticastclient.qdoc
+++ b/examples/coap/doc/quickmulticastclient.qdoc
@@ -31,4 +31,131 @@
     \ingroup qtcoap-examples
     \brief Using the CoAP client for a multicast resource discovery with a Qt Quick
     user interface.
+
+    \image quickmulticastclient.png
+
+    The \e {Quick CoAP Multicast Discovery Example} demonstrates how to register
+    QCoapClient as a QML type and use it in a Qt Quick application for CoAP multicast
+    resource discovery.
+
+    \note Qt CoAP does not provide a QML API in its current version. However, you can
+    make the C++ classes of the module available to QML as shown in this example.
+
+    \section1 Running the Example
+
+    To run the example application, you first need to set up and start at least one CoAP
+    server supporting multicast resource discovery. You have the following options:
+
+    \list
+        \li Manually build and run CoAP servers using
+        \l {https://github.com/obgm/libcoap} {libcoap},
+        \l {https://github.com/eclipse/californium/} {Californium}, or any
+        other CoAP server implementation, which supports multicast and resource
+        discovery features.
+        \li Use the ready Docker image available at Docker Hub, which builds and starts
+        CoAP server based on Californium's
+        \l {https://github.com/eclipse/californium/tree/2.0.x/demo-apps/cf-helloworld-server}
+        {multicast server example}.
+    \endlist
+
+    \section2 Using the Docker-based Test Server
+
+    The following command pulls the docker container for the CoAP server from the
+    Docker Hub and starts it:
+
+    \badcode
+    docker run --name coap-multicast-server -d --rm --net=host sokurazy/coap-multicast-test-server:californium.2.0.x
+    \endcode
+
+    \note You can run more than one multicast CoAP servers (on the same host or other
+    hosts in the network) by passing a different \c{--name} to the command above.
+
+    \section1 Creating a Client and Using It with QML
+
+    We create the \c QmlCoapMulticastClient class with the QCoapClient class as a
+    base class:
+
+    \quotefromfile quickmulticastclient/qmlcoapmulticastclient.h
+    \skipto QmlCoapMulticastClient
+    \printuntil };
+
+    In the main.cpp file, we register the \c QmlCoapMulticastClient class as a QML
+    type:
+
+    \quotefromfile quickmulticastclient/main.cpp
+    \skipto qmlRegisterType
+    \printline qmlRegisterType
+
+    We also register the QtCoap namespace, to be able to use it in QML code:
+
+    \skipto qmlRegisterUncreatableMetaObject
+    \printto const QUrl
+
+    Now in the QML code, we can import and use these types:
+
+    \quotefromfile quickmulticastclient/main.qml
+    \dots
+    \skipto CoapMulticastClient
+    \printuntil qtcoap.example.namespace
+    \dots
+    \skipto CoapMulticastClient
+    \printto GridLayout
+    \dots
+
+    The \c {QCoapClient::error()} signal triggers the \c onError signal handler of
+    \c CoapMulticastClient, and the \c {QmlCoapMulticastClient::finished()} signal
+    triggers the \c onFinished signal handler, to show the request's status in the UI.
+    Note that we are not using the \c {QCoapClient::finished()} signal directly,
+    because it takes a \c {QCoapReply} as a parameter (which is not a QML type), and
+    we are interested only in the error code.
+
+    In the \c QmlCoapMulticastClient's constructor, we arrange for the
+    \c {QCoapClient::finished()} signal to be forwarded to the
+    \c {QmlCoapMulticastClient::finished()} signal:
+
+    \quotefromfile quickmulticastclient/qmlcoapmulticastclient.cpp
+    \skipto QmlCoapMulticastClient::QmlCoapMulticastClient
+    \printto QmlCoapMulticastClient::discover
+
+    When the \uicontrol Discover button is pressed, we invoke one of the overloaded
+    \c {discover()} methods, based on the selected multicast group:
+
+    \quotefromfile quickmulticastclient/main.qml
+    \skipto Button {
+    \dots
+    \printto ListModel {
+    \dots
+
+    This overload is called when a custom multicast group or a host address is selected:
+
+    \quotefromfile quickmulticastclient/qmlcoapmulticastclient.cpp
+    \skipto QmlCoapMulticastClient::discover
+    \printto QmlCoapMulticastClient::discover(QtCoap::MulticastGroup
+
+    And this overload is called when one of the suggested multicast groups is selected
+    in the UI:
+
+    \printto void QmlCoapMulticastClient::onDiscovered
+
+    The \c {QCoapClient::discovered()} signal delivers a list of \c {QCoapResources},
+    which is not a QML type. To make the resources available in QML, we forward each
+    resource in the list to the \c {QmlCoapMulticastClient::discovered()} signal, which
+    takes a \c QmlCoapResource instead:
+
+    \printuntil
+
+    \c QmlCoapResource is a wrapper around QCoapResource, to make some of its
+    properties available in QML:
+
+    \quotefromfile quickmulticastclient/qmlcoapmulticastclient.h
+    \skipto class QmlCoapResource
+    \printuntil };
+
+    The discovered resources are added to the \c resourceModel of the list view in the UI:
+
+    \quotefromfile quickmulticastclient/main.qml
+    \skipto addResource
+    \dots
+    \printto CoapMulticastClient {
+    \dots
 */
diff --git a/src/coap/coap.pro b/src/coap/coap.pro
index 571b746..024de15 100644
--- a/src/coap/coap.pro
+++ b/src/coap/coap.pro
@@ -10,7 +10,6 @@ PUBLIC_HEADERS += \
     qcoapconnection.h \
     qcoapdiscoveryreply.h \
     qcoapglobal.h \
-    qcoapinternalmessage.h \
     qcoapmessage.h \
     qcoapnamespace.h \
     qcoapoption.h \
diff --git a/src/coap/doc/src/external-resources.qdoc b/src/coap/doc/src/external-resources.qdoc
index 8cbbf9f..f018c94 100644
--- a/src/coap/doc/src/external-resources.qdoc
+++ b/src/coap/doc/src/external-resources.qdoc
@@ -59,3 +59,8 @@
     \externalpage https://tools.ietf.org/html/rfc7252#section-4.2
     \title RFC 7252 - Section 4.2
 */
+
+/*!
+    \externalpage https://www.iana.org/assignments/core-parameters/core-parameters.xhtml#content-formats
+    \title CoAP Content-Formats Registry
+*/
diff --git a/src/coap/qcoapclient.cpp b/src/coap/qcoapclient.cpp
index b438ba6..dced30e 100644
--- a/src/coap/qcoapclient.cpp
+++ b/src/coap/qcoapclient.cpp
@@ -127,7 +127,7 @@ QCoapClientPrivate::~QCoapClientPrivate()
 
 /*!
     \fn void QCoapClient::responseToMulticastReceived(QCoapReply *reply,
-                                                      const QCoapMessage& message,
+                                                      const QCoapMessage &message,
                                                       const QHostAddress &sender)
 
     This signal is emitted when a unicast response to a multicast request
@@ -508,6 +508,15 @@ void QCoapClient::cancelObserve(const QUrl &url)
 }
 
 /*!
+    Closes the open sockets and connections to free the transport.
+*/
+void QCoapClient::disconnect()
+{
+    Q_D(QCoapClient);
+    QMetaObject::invokeMethod(d->connection, "disconnect", Qt::QueuedConnection);
+}
+
+/*!
     \internal
 
     Sends the CoAP \a request to its own URL and returns a new QCoapReply
diff --git a/src/coap/qcoapclient.h b/src/coap/qcoapclient.h
index 5795191..4645c4c 100644
--- a/src/coap/qcoapclient.h
+++ b/src/coap/qcoapclient.h
@@ -72,6 +72,7 @@ public:
     QCoapReply *observe(const QUrl &request);
     void cancelObserve(QCoapReply *notifiedReply);
     void cancelObserve(const QUrl &url);
+    void disconnect();
 
     QCoapDiscoveryReply *discover(QtCoap::MulticastGroup group = QtCoap::AllCoapNodesIPv4,
                                   int port = QtCoap::DefaultPort,
@@ -89,7 +90,7 @@ public:
 
 Q_SIGNALS:
     void finished(QCoapReply *reply);
-    void responseToMulticastReceived(QCoapReply *reply, const QCoapMessage& message,
+    void responseToMulticastReceived(QCoapReply *reply, const QCoapMessage &message,
                                      const QHostAddress &sender);
     void error(QCoapReply *reply, QtCoap::Error error);
 
diff --git a/src/coap/qcoapconnection.cpp b/src/coap/qcoapconnection.cpp
index 0263618..7ee529a 100644
--- a/src/coap/qcoapconnection.cpp
+++ b/src/coap/qcoapconnection.cpp
@@ -98,7 +98,16 @@ Q_LOGGING_CATEGORY(lcCoapConnection, "qt.coap.connection")
 
     This is a pure virtual method.
 
-    \sa bound()
+    \sa bound(), close()
+*/
+
+/*!
+    \fn void QCoapConnection::close()
+
+    Closes the open sockets and connections to free the underlying transport.
+    This is a pure virtual method.
+
+    \sa bind()
 */
 
 /*!
@@ -133,6 +142,12 @@ QCoapConnection::QCoapConnection(QtCoap::SecurityMode securityMode, QObject *par
 QCoapConnection::QCoapConnection(QObjectPrivate &dd, QObject *parent)
     : QObject(dd, parent)
 {
+    connect(this, &QCoapConnection::bound, this,
+            [this]() {
+                Q_D(QCoapConnection);
+                d->state = QCoapConnection::Bound;
+                startToSendRequest();
+            });
 }
 
 /*!
@@ -160,16 +175,10 @@ QCoapConnectionPrivate::sendRequest(const QByteArray &request, const QString &ho
     CoapFrame frame(request, host, port);
     framesToSend.enqueue(frame);
 
-    if (state == QCoapConnection::ConnectionState::Unconnected) {
-        q->connect(q, &QCoapConnection::bound, q,
-                [this, q]() {
-                    state = QCoapConnection::ConnectionState::Bound;
-                    q->startToSendRequest();
-                });
+    if (state == QCoapConnection::ConnectionState::Unconnected)
         q->bind(host, port);
-    } else {
+    else
         q->startToSendRequest();
-    }
 }
 
 /*!
@@ -242,4 +251,18 @@ QCoapSecurityConfiguration QCoapConnection::securityConfiguration() const
     return d->securityConfiguration;
 }
 
+/*!
+    Closes the open sockets and connections to free the transport and clears
+    the connection state.
+*/
+void QCoapConnection::disconnect()
+{
+    Q_D(QCoapConnection);
+
+    close();
+
+    d->framesToSend.clear();
+    d->state = QCoapConnection::Unconnected;
+}
+
 QT_END_NAMESPACE
diff --git a/src/coap/qcoapconnection.h b/src/coap/qcoapconnection.h
index 017a0bd..017053b 100644
--- a/src/coap/qcoapconnection.h
+++ b/src/coap/qcoapconnection.h
@@ -58,6 +58,7 @@ public:
     QCoapSecurityConfiguration securityConfiguration() const;
 
     Q_INVOKABLE void setSecurityConfiguration(const QCoapSecurityConfiguration &configuration);
+    Q_INVOKABLE void disconnect();
 
 Q_SIGNALS:
     void error(QAbstractSocket::SocketError error);
@@ -73,6 +74,7 @@ protected:
 
     virtual void bind(const QString &host, quint16 port) = 0;
     virtual void writeData(const QByteArray &data, const QString &host, quint16 port) = 0;
+    virtual void close() = 0;
 
 private:
     friend class QCoapProtocolPrivate;
diff --git a/src/coap/qcoapdiscoveryreply_p.h b/src/coap/qcoapdiscoveryreply_p.h
index ccd5d72..5f4856e 100644
--- a/src/coap/qcoapdiscoveryreply_p.h
+++ b/src/coap/qcoapdiscoveryreply_p.h
@@ -54,7 +54,7 @@ class Q_AUTOTEST_EXPORT QCoapDiscoveryReplyPrivate : public QCoapReplyPrivate
 public:
     QCoapDiscoveryReplyPrivate(const QCoapRequest &request);
 
-    void _q_setContent(const QHostAddress &sender, const QCoapMessage &, QtCoap::ResponseCode) Q_DECL_OVERRIDE;
+    void _q_setContent(const QHostAddress &sender, const QCoapMessage &, QtCoap::ResponseCode) override;
 
     QVector<QCoapResource> resources;
 
diff --git a/src/coap/qcoapinternalmessage.h b/src/coap/qcoapinternalmessage.h
deleted file mode 100644
index af858bf..0000000
--- a/src/coap/qcoapinternalmessage.h
+++ /dev/null
@@ -1,74 +0,0 @@
-/****************************************************************************
-**
-** Copyright (C) 2017 Witekio.
-** Copyright (C) 2018 The Qt Company Ltd.
-** Contact: https://www.qt.io/licensing/
-**
-** This file is part of the QtCoap module.
-**
-** $QT_BEGIN_LICENSE:GPL$
-** Commercial License Usage
-** Licensees holding valid commercial Qt licenses may use this file in
-** accordance with the commercial license agreement provided with the
-** Software or, alternatively, in accordance with the terms contained in
-** a written agreement between you and The Qt Company. For licensing terms
-** and conditions see https://www.qt.io/terms-conditions. For further
-** information use the contact form at https://www.qt.io/contact-us.
-**
-** GNU General Public License Usage
-** Alternatively, this file may be used under the terms of the GNU
-** General Public License version 3 or (at your option) any later version
-** approved by the KDE Free Qt Foundation. The licenses are as published by
-** the Free Software Foundation and appearing in the file LICENSE.GPL3
-** included in the packaging of this file. Please review the following
-** information to ensure the GNU General Public License requirements will
-** be met: https://www.gnu.org/licenses/gpl-3.0.html.
-**
-** $QT_END_LICENSE$
-**
-****************************************************************************/
-
-#ifndef QCOAPINTERNALMESSAGE_H
-#define QCOAPINTERNALMESSAGE_H
-
-#include <QtCoap/qcoapmessage.h>
-#include <QtCore/qobject.h>
-
-QT_BEGIN_NAMESPACE
-
-class QCoapInternalMessagePrivate;
-class Q_AUTOTEST_EXPORT QCoapInternalMessage : public QObject
-{
-    Q_OBJECT
-public:
-    explicit QCoapInternalMessage(QObject *parent = nullptr);
-    explicit QCoapInternalMessage(const QCoapMessage &message, QObject *parent = nullptr);
-    QCoapInternalMessage(const QCoapInternalMessage &other, QObject *parent = nullptr);
-    virtual ~QCoapInternalMessage() {}
-
-    void addOption(QCoapOption::OptionName name, const QByteArray &value);
-    void addOption(QCoapOption::OptionName name, quint32 value);
-    virtual void addOption(const QCoapOption &option);
-    void removeOption(QCoapOption::OptionName name);
-
-    QCoapMessage *message();
-    const QCoapMessage *message() const;
-
-    uint currentBlockNumber() const;
-    bool hasMoreBlocksToReceive() const;
-    uint blockSize() const;
-
-    virtual bool isValid() const;
-    static bool isUrlValid(const QUrl &url);
-
-protected:
-    explicit QCoapInternalMessage(QCoapInternalMessagePrivate &dd, QObject *parent = nullptr);
-
-    void setFromDescriptiveBlockOption(const QCoapOption &option);
-
-    Q_DECLARE_PRIVATE(QCoapInternalMessage)
-};
-
-QT_END_NAMESPACE
-
-#endif // QCOAPINTERNALMESSAGE_H
diff --git a/src/coap/qcoapinternalmessage_p.h b/src/coap/qcoapinternalmessage_p.h
index b239ca6..8ed1309 100644
--- a/src/coap/qcoapinternalmessage_p.h
+++ b/src/coap/qcoapinternalmessage_p.h
@@ -31,7 +31,6 @@
 #ifndef QCOAPINTERNALMESSAGE_P_H
 #define QCOAPINTERNALMESSAGE_P_H
 
-#include <QtCoap/qcoapinternalmessage.h>
 #include <private/qcoapmessage_p.h>
 #include <private/qobject_p.h>
 
@@ -48,6 +47,39 @@
 
 QT_BEGIN_NAMESPACE
 
+class QCoapInternalMessagePrivate;
+class Q_AUTOTEST_EXPORT QCoapInternalMessage : public QObject
+{
+    Q_OBJECT
+public:
+    explicit QCoapInternalMessage(QObject *parent = nullptr);
+    explicit QCoapInternalMessage(const QCoapMessage &message, QObject *parent = nullptr);
+    QCoapInternalMessage(const QCoapInternalMessage &other, QObject *parent = nullptr);
+    virtual ~QCoapInternalMessage() {}
+
+    void addOption(QCoapOption::OptionName name, const QByteArray &value);
+    void addOption(QCoapOption::OptionName name, quint32 value);
+    virtual void addOption(const QCoapOption &option);
+    void removeOption(QCoapOption::OptionName name);
+
+    QCoapMessage *message();
+    const QCoapMessage *message() const;
+
+    uint currentBlockNumber() const;
+    bool hasMoreBlocksToReceive() const;
+    uint blockSize() const;
+
+    virtual bool isValid() const;
+    static bool isUrlValid(const QUrl &url);
+
+protected:
+    explicit QCoapInternalMessage(QCoapInternalMessagePrivate &dd, QObject *parent = nullptr);
+
+    void setFromDescriptiveBlockOption(const QCoapOption &option);
+
+    Q_DECLARE_PRIVATE(QCoapInternalMessage)
+};
+
 class Q_AUTOTEST_EXPORT QCoapInternalMessagePrivate : public QObjectPrivate
 {
 public:
diff --git a/src/coap/qcoapinternalreply_p.h b/src/coap/qcoapinternalreply_p.h
index cd24b87..db9a052 100644
--- a/src/coap/qcoapinternalreply_p.h
+++ b/src/coap/qcoapinternalreply_p.h
@@ -33,7 +33,6 @@
 
 #include <QtCoap/qcoapglobal.h>
 #include <QtCoap/qcoapnamespace.h>
-#include <QtCoap/qcoapinternalmessage.h>
 #include <private/qcoapinternalmessage_p.h>
 #include <QtNetwork/qhostaddress.h>
 
@@ -64,7 +63,7 @@ public:
     int nextBlockToSend() const;
 
     using QCoapInternalMessage::addOption;
-    void addOption(const QCoapOption &option);
+    void addOption(const QCoapOption &option) override;
     void setSenderAddress(const QHostAddress &address);
 
     QtCoap::ResponseCode responseCode() const;
diff --git a/src/coap/qcoapinternalrequest_p.h b/src/coap/qcoapinternalrequest_p.h
index df22736..1b50aae 100644
--- a/src/coap/qcoapinternalrequest_p.h
+++ b/src/coap/qcoapinternalrequest_p.h
@@ -35,7 +35,6 @@
 
 #include <QtCoap/qcoapglobal.h>
 #include <QtCoap/qcoapnamespace.h>
-#include <QtCoap/qcoapinternalmessage.h>
 #include <QtCoap/qcoapconnection.h>
 
 #include <QtCore/qglobal.h>
@@ -64,7 +63,7 @@ public:
     explicit QCoapInternalRequest(QObject *parent = nullptr);
     explicit QCoapInternalRequest(const QCoapRequest &request, QObject *parent = nullptr);
 
-    bool isValid() const Q_DECL_OVERRIDE;
+    bool isValid() const override;
 
     void initForAcknowledgment(quint16 messageId, const QByteArray &token);
     void initForReset(quint16 messageId);
@@ -77,7 +76,7 @@ public:
     bool checkBlockNumber(uint blockNumber);
 
     using QCoapInternalMessage::addOption;
-    void addOption(const QCoapOption &option) Q_DECL_OVERRIDE;
+    void addOption(const QCoapOption &option) override;
     bool addUriOptions(QUrl uri, const QUrl &proxyUri = QUrl());
 
     QCoapToken token() const;
diff --git a/src/coap/qcoapmessage.cpp b/src/coap/qcoapmessage.cpp
index 49e8030..d07611c 100644
--- a/src/coap/qcoapmessage.cpp
+++ b/src/coap/qcoapmessage.cpp
@@ -371,9 +371,15 @@ void QCoapMessage::setMessageId(quint16 id)
 }
 
 /*!
-    Sets the message payload to \a payload.
+    Sets the message payload to \a payload. The payload can be represented in
+    one of the content formats defined in \l {CoAP Content-Formats Registry}.
 
-    \sa payload()
+    \note CoAP supports common content formats such as XML, JSON, and so on, but
+    these are text based and consequently heavy both in payload and in processing.
+    One of the recommended content formats to use with CoAP is CBOR, which is
+    designed to be used in such contexts.
+
+    \sa payload(), QCborStreamWriter, QCborStreamReader
 */
 void QCoapMessage::setPayload(const QByteArray &payload)
 {
diff --git a/src/coap/qcoapmessage.h b/src/coap/qcoapmessage.h
index 769c613..550ff88 100644
--- a/src/coap/qcoapmessage.h
+++ b/src/coap/qcoapmessage.h
@@ -53,7 +53,7 @@ public:
 
     QCoapMessage();
     QCoapMessage(const QCoapMessage &other);
-    virtual ~QCoapMessage();
+    ~QCoapMessage();
 
     void swap(QCoapMessage &other) Q_DECL_NOTHROW;
     QCoapMessage &operator=(const QCoapMessage &other);
@@ -79,7 +79,7 @@ public:
     QVector<QCoapOption> options(QCoapOption::OptionName name) const;
     int optionCount() const;
     void addOption(QCoapOption::OptionName name, const QByteArray &value = QByteArray());
-    virtual void addOption(const QCoapOption &option);
+    void addOption(const QCoapOption &option);
     void removeOption(const QCoapOption &option);
     void removeOption(QCoapOption::OptionName name);
     void removeAllOptions();
diff --git a/src/coap/qcoapprotocol.h b/src/coap/qcoapprotocol.h
index e7763d9..0c91443 100644
--- a/src/coap/qcoapprotocol.h
+++ b/src/coap/qcoapprotocol.h
@@ -67,7 +67,7 @@ public:
 
 Q_SIGNALS:
     void finished(QCoapReply *reply);
-    void responseToMulticastReceived(QCoapReply *reply, const QCoapMessage& message,
+    void responseToMulticastReceived(QCoapReply *reply, const QCoapMessage &message,
                                      const QHostAddress &sender);
     void error(QCoapReply *reply, QtCoap::Error error);
 
diff --git a/src/coap/qcoapqudpconnection.cpp b/src/coap/qcoapqudpconnection.cpp
index 636554c..831b23d 100644
--- a/src/coap/qcoapqudpconnection.cpp
+++ b/src/coap/qcoapqudpconnection.cpp
@@ -242,6 +242,30 @@ void QCoapQUdpConnection::writeData(const QByteArray &data, const QString &host,
 }
 
 /*!
+    \internal
+
+    \brief Close the UDP socket
+
+    In the case of a secure connection, this also interrupts any ongoing
+    hand-shake and shuts down the DTLS connection.
+*/
+void QCoapQUdpConnection::close()
+{
+    Q_D(QCoapQUdpConnection);
+
+#if QT_CONFIG(dtls)
+    if (isSecure()) {
+        if (d->dtls->handshakeState() == QDtls::HandshakeInProgress)
+            d->dtls->abortHandshake(d->socket());
+
+        if (d->dtls->isConnectionEncrypted())
+            d->dtls->shutdown(d->socket());
+    }
+#endif
+    d->socket()->close();
+}
+
+/*!
     Sets the QUdpSocket socket \a option to \a value.
 */
 void QCoapQUdpConnection::setSocketOption(QAbstractSocket::SocketOption option, const QVariant &value)
@@ -393,8 +417,10 @@ void QCoapQUdpConnection::handshakeTimeout()
     Q_D(QCoapQUdpConnection);
 
     qCWarning(lcCoapConnection, "Handshake timeout, trying to re-transmit");
-    if (!d->dtls->handleTimeout(d->udpSocket))
+    if (d->dtls->handshakeState() == QDtls::HandshakeInProgress &&
+            !d->dtls->handleTimeout(d->udpSocket)) {
         qCWarning(lcCoapConnection) << "Failed to re-transmit" << d->dtls->dtlsErrorString();
+    }
 }
 
 /*!
diff --git a/src/coap/qcoapqudpconnection.h b/src/coap/qcoapqudpconnection.h
index b070d1d..76c5abf 100644
--- a/src/coap/qcoapqudpconnection.h
+++ b/src/coap/qcoapqudpconnection.h
@@ -69,6 +69,7 @@ protected:
 
     void bind(const QString &host, quint16 port) override;
     void writeData(const QByteArray &data, const QString &host, quint16 port) override;
+    void close() override;
 
     void createSocket();
 
diff --git a/src/coap/qcoapreply.h b/src/coap/qcoapreply.h
index 648dc3b..afdd5ea 100644
--- a/src/coap/qcoapreply.h
+++ b/src/coap/qcoapreply.h
@@ -73,8 +73,8 @@ protected:
 
     explicit QCoapReply(QCoapReplyPrivate &dd, QObject *parent = nullptr);
 
-    qint64 readData(char *data, qint64 maxSize) Q_DECL_OVERRIDE;
-    qint64 writeData(const char *data, qint64 maxSize) Q_DECL_OVERRIDE;
+    qint64 readData(char *data, qint64 maxSize) override;
+    qint64 writeData(const char *data, qint64 maxSize) override;
 
     Q_DECLARE_PRIVATE(QCoapReply)
     Q_PRIVATE_SLOT(d_func(), void _q_setRunning(const QCoapToken &, QCoapMessageId))
diff --git a/src/coap/qcoapresource.cpp b/src/coap/qcoapresource.cpp
index c24950e..7e20209 100644
--- a/src/coap/qcoapresource.cpp
+++ b/src/coap/qcoapresource.cpp
@@ -255,9 +255,15 @@ void QCoapResource::setMaximumSize(int maximumSize)
 }
 
 /*!
-    Sets the content format of the resource to \a contentFormat.
+    Sets the content format of the resource to \a contentFormat. The content
+    format can be one of the content formats defined in \l {CoAP Content-Formats Registry}.
 
-    \sa contentFormat()
+    \note CoAP supports common content formats such as XML, JSON, and so on, but
+    these are text based and consequently heavy both in payload and in processing.
+    One of the recommended content formats to use with CoAP is CBOR, which is
+    designed to be used in such contexts.
+
+    \sa contentFormat(), QCborStreamWriter, QCborStreamReader
  */
 void QCoapResource::setContentFormat(uint contentFormat)
 {
diff --git a/tests/auto/qcoapclient/tst_qcoapclient.cpp b/tests/auto/qcoapclient/tst_qcoapclient.cpp
index ee61f70..04db9f4 100644
--- a/tests/auto/qcoapclient/tst_qcoapclient.cpp
+++ b/tests/auto/qcoapclient/tst_qcoapclient.cpp
@@ -154,6 +154,8 @@ public:
         Q_UNUSED(port);
         // Do nothing
     }
+
+    void close() override {}
 };
 
 class QCoapClientForMulticastTests : public QCoapClient
diff --git a/tests/auto/qcoapqudpconnection/tst_qcoapqudpconnection.cpp b/tests/auto/qcoapqudpconnection/tst_qcoapqudpconnection.cpp
index 6b3f0e9..898466d 100644
--- a/tests/auto/qcoapqudpconnection/tst_qcoapqudpconnection.cpp
+++ b/tests/auto/qcoapqudpconnection/tst_qcoapqudpconnection.cpp
@@ -58,6 +58,7 @@ class tst_QCoapQUdpConnection : public QObject
 private Q_SLOTS:
     void ctor();
     void connectToHost();
+    void reconnect();
     void sendRequest_data();
     void sendRequest();
 };
@@ -105,6 +106,29 @@ void tst_QCoapQUdpConnection::connectToHost()
 #endif
 }
 
+void tst_QCoapQUdpConnection::reconnect()
+{
+#ifdef QT_BUILD_INTERNAL
+    QCoapQUdpConnectionForTest connection;
+
+    // This will trigger connection.bind()
+    QSignalSpy connectionBoundSpy(&connection, SIGNAL(bound()));
+    connection.sendRequest(QByteArray(), QString(), 0);
+    QTRY_COMPARE(connectionBoundSpy.count(), 1);
+    QCOMPARE(connection.state(), QCoapQUdpConnection::Bound);
+
+    connection.disconnect();
+    QCOMPARE(connection.state(), QCoapQUdpConnection::Unconnected);
+
+    // Make sure that we are able to connect again
+    connection.sendRequest(QByteArray(), QString(), 0);
+    QTRY_COMPARE(connectionBoundSpy.count(), 2);
+    QCOMPARE(connection.state(), QCoapQUdpConnection::Bound);
+#else
+    QSKIP("Not an internal build, skipping this test");
+#endif
+}
+
 void tst_QCoapQUdpConnection::sendRequest_data()
 {
     QTest::addColumn<QString>("protocol");