Add the CoAP module, providing a client for Qt

Features:
- Send GET/POST/PUT/DELETE requests
- Discover resources (single server)
- Observe resources and cancel the observation
- Blockwise requests and replies
- Requests (and replies) can be confirmable or non-confirmable
- Some options can be added to the request
- Replies can be received in a separate or piggybacked message

Change-Id: I31e0e20a4f19bdc6d6489281fde73a4ff848eda4
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

5 files changed, 282 insertions, 0 deletions

diff --git a/examples/examples.pro b/examples/examples.pro
new file mode 100644
index 0000000..0490212
--- /dev/null
+++ b/examples/examples.pro
@@ -0,0 +1,5 @@
+TEMPLATE = subdirs
+CONFIG += no_docs_target
+
+SUBDIRS += \
+    testapp
diff --git a/examples/testapp/coaphandler.cpp b/examples/testapp/coaphandler.cpp
new file mode 100644
index 0000000..1e50117
--- /dev/null
+++ b/examples/testapp/coaphandler.cpp
@@ -0,0 +1,117 @@
+/****************************************************************************
+**
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "coaphandler.h"
+
+#include <QDebug>
+#include <QCoapClient>
+#include <QCoapReply>
+#include <QCoapDiscoveryReply>
+
+CoapHandler::CoapHandler(QObject *parent) : QObject(parent)
+{
+    connect(&m_coapClient, &QCoapClient::finished, this, &CoapHandler::onFinished);
+    connect(&m_coapClient, &QCoapClient::error, this, &CoapHandler::onError);
+}
+
+bool CoapHandler::runGet(const QUrl &url)
+{
+    return m_coapClient.get(url);
+}
+
+bool CoapHandler::runPost(const QUrl &url)
+{
+    return m_coapClient.post(url);
+}
+
+bool CoapHandler::runPut(const QUrl &url)
+{
+    return m_coapClient.put(url);
+}
+
+bool CoapHandler::runDelete(const QUrl &url)
+{
+    return m_coapClient.deleteResource(url);
+}
+
+bool CoapHandler::runObserve(const QUrl &url)
+{
+    QCoapReply *observeReply = m_coapClient.observe(url);
+    if (!observeReply)
+        return false;
+
+    connect(observeReply, &QCoapReply::notified, this, &CoapHandler::onNotified);
+    return true;
+}
+
+bool CoapHandler::runDiscover(const QUrl &url)
+{
+    QCoapDiscoveryReply *discoverReply = m_coapClient.discover(url);
+    if (discoverReply)
+        return false;
+
+    connect(discoverReply, &QCoapDiscoveryReply::discovered, this, &CoapHandler::onDiscovered);
+    return true;
+}
+
+void CoapHandler::onFinished(QCoapReply *reply)
+{
+    if (reply->errorReceived() == QtCoap::NoError)
+        qDebug() << "Request finished with payload: " << reply->readAll();
+    else
+        qDebug() << "Request failed";
+
+    // Don't forget to remove the reply
+    reply->deleteLater();
+}
+
+void CoapHandler::onNotified(QCoapReply *reply, QCoapMessage message)
+{
+    Q_UNUSED(message)
+
+    // You can alternatively use `message.payload();`
+    qDebug() << "Received Observe notification with payload: " << reply->readAll();
+}
+
+void CoapHandler::onDiscovered(QCoapDiscoveryReply *reply, QVector<QCoapResource> resources)
+{
+    Q_UNUSED(reply)
+
+    for (const QCoapResource &res : qAsConst(resources))
+        qDebug() << "Discovered resource: " << res.path() << res.title();
+}
+
+void CoapHandler::onError(QCoapReply *reply, QtCoap::Error error)
+{
+    if (reply)
+        qDebug() << "CoAP reply error: " << reply->errorString();
+    else
+        qDebug() << "CoAP error: " << error;
+}
diff --git a/examples/testapp/coaphandler.h b/examples/testapp/coaphandler.h
new file mode 100644
index 0000000..fd64eb6
--- /dev/null
+++ b/examples/testapp/coaphandler.h
@@ -0,0 +1,71 @@
+/****************************************************************************
+**
+** 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 COAPHANDLER_H
+#define COAPHANDLER_H
+
+#include <QObject>
+#include <QCoapClient>
+#include <QCoapMessage>
+#include <QCoapResource>
+#include <qcoapnamespace.h>
+
+QT_BEGIN_NAMESPACE
+
+class QCoapReply;
+class QCoapDiscoveryReply;
+class QCoapResource;
+
+QT_END_NAMESPACE
+
+class CoapHandler : public QObject
+{
+    Q_OBJECT
+public:
+    explicit CoapHandler(QObject *parent = nullptr);
+
+    bool runGet(const QUrl &url);
+    bool runPost(const QUrl &url);
+    bool runPut(const QUrl &url);
+    bool runDelete(const QUrl &url);
+    bool runObserve(const QUrl &url);
+    bool runDiscover(const QUrl &url);
+
+public Q_SLOTS:
+    void onFinished(QCoapReply *reply);
+    void onNotified(QCoapReply *reply, QCoapMessage message);
+    void onDiscovered(QCoapDiscoveryReply *reply, QVector<QCoapResource> resources);
+    void onError(QCoapReply *reply, QtCoap::Error error);
+
+private:
+    QCoapClient m_coapClient;
+};
+
+#endif // COAPHANDLER_H
diff --git a/examples/testapp/main.cpp b/examples/testapp/main.cpp
new file mode 100644
index 0000000..096277c
--- /dev/null
+++ b/examples/testapp/main.cpp
@@ -0,0 +1,75 @@
+/****************************************************************************
+**
+** 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "coaphandler.h"
+
+#include <QCoreApplication>
+#include <QCommandLineParser>
+#include <QUrl>
+
+int main(int argc, char *argv[])
+{
+    QCoreApplication a(argc, argv);
+
+    QCommandLineParser parser;
+    parser.setApplicationDescription("Qt CoAP test application");
+    parser.addHelpOption();
+    parser.addPositionalArgument("url",
+                                 "The targeted coap resource URL, e.g. 'coap://10.10.10.10/myresource'");
+    parser.addOption({"get", "Use GET method for the request. This is the default method"});
+    parser.addOption({"post", "Use POST method for the request"});
+    parser.addOption({"put", "Use PUT method for the request"});
+    parser.addOption({"delete", "Use DELETE method for the request"});
+    parser.addOption({"observe", "Observe a resource"});
+    parser.addOption({"discover", "Discover available resources"});
+
+    parser.process(a);
+
+    if (parser.positionalArguments().isEmpty()) {
+        qWarning("Please provide an url for the request");
+        parser.showHelp(1);
+    }
+
+    QUrl url = parser.positionalArguments().first();
+    if (!url.isValid()) {
+        qWarning("The url provided is not valid.");
+        parser.showHelp(1);
+    }
+
+    CoapHandler handler;
+    if (parser.isSet("get"))        handler.runGet(url);
+    if (parser.isSet("post"))       handler.runPost(url);
+    if (parser.isSet("put"))        handler.runPut(url);
+    if (parser.isSet("delete"))     handler.runDelete(url);
+    if (parser.isSet("observe"))    handler.runObserve(url);
+    if (parser.isSet("discover"))   handler.runDiscover(url);
+
+    return a.exec();
+}
diff --git a/examples/testapp/testapp.pro b/examples/testapp/testapp.pro
new file mode 100644
index 0000000..d41641b
--- /dev/null
+++ b/examples/testapp/testapp.pro
@@ -0,0 +1,14 @@
+QT -= gui
+QT += network coap
+
+TARGET = testapp
+
+HEADERS += \
+    coaphandler.h
+
+SOURCES += main.cpp \
+    coaphandler.cpp
+
+# install
+target.path = $$[QT_INSTALL_EXAMPLES]/testapp
+INSTALLS += target