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<h1 class="title">connection.cpp Example File</h1>
<span class="subtitle">network-chat/connection.cpp</span>
<!-- $$$network-chat/connection.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">

  <span class="comment">/****************************************************************************
  **
  ** Copyright (C) 2016 The Qt Company Ltd.
  ** Copyright (C) 2018 Intel Corporation.
  ** Contact: https://www.qt.io/licensing/
  **
  ** This file is part of the examples of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:BSD$
  ** 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.
  **
  ** BSD License Usage
  ** Alternatively, you may use this file under the terms of the BSD license
  ** as follows:
  **
  ** &quot;Redistribution and use in source and binary forms, with or without
  ** modification, are permitted provided that the following conditions are
  ** met:
  **   * Redistributions of source code must retain the above copyright
  **     notice, this list of conditions and the following disclaimer.
  **   * Redistributions in binary form must reproduce the above copyright
  **     notice, this list of conditions and the following disclaimer in
  **     the documentation and/or other materials provided with the
  **     distribution.
  **   * Neither the name of The Qt Company Ltd nor the names of its
  **     contributors may be used to endorse or promote products derived
  **     from this software without specific prior written permission.
  **
  **
  ** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  ** &quot;AS IS&quot; AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  ** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  ** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  ** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  ** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  ** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  ** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  ** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  ** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  ** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.&quot;
  **
  ** $QT_END_LICENSE$
  **
  ****************************************************************************/</span>

  <span class="preprocessor">#include &quot;connection.h&quot;</span>

  <span class="preprocessor">#include &lt;QtNetwork&gt;</span>

  <span class="keyword">static</span> <span class="keyword">const</span> <span class="type">int</span> TransferTimeout <span class="operator">=</span> <span class="number">30</span> <span class="operator">*</span> <span class="number">1000</span>;
  <span class="keyword">static</span> <span class="keyword">const</span> <span class="type">int</span> PongTimeout <span class="operator">=</span> <span class="number">60</span> <span class="operator">*</span> <span class="number">1000</span>;
  <span class="keyword">static</span> <span class="keyword">const</span> <span class="type">int</span> PingInterval <span class="operator">=</span> <span class="number">5</span> <span class="operator">*</span> <span class="number">1000</span>;

  <span class="comment">/*
   * Protocol is defined as follows, using the CBOR Data Definition Language:
   *
   *  protocol    = [
   *     greeting,        ; must start with a greeting command
   *     * command        ; zero or more regular commands after
   *  ]
   *  command     = plaintext / ping / pong / greeting
   *  plaintext   = { 0 =&gt; text }
   *  ping        = { 1 =&gt; null }
   *  pong        = { 2 =&gt; null }
   *  greeting    = { 3 =&gt; text }
   */</span>

  Connection<span class="operator">::</span>Connection(<span class="type"><a href="../qtcore/qobject.html">QObject</a></span> <span class="operator">*</span>parent)
      : <span class="type"><a href="qtcpsocket.html">QTcpSocket</a></span>(parent)<span class="operator">,</span> writer(<span class="keyword">this</span>)
  {
      greetingMessage <span class="operator">=</span> tr(<span class="string">&quot;undefined&quot;</span>);
      username <span class="operator">=</span> tr(<span class="string">&quot;unknown&quot;</span>);
      state <span class="operator">=</span> WaitingForGreeting;
      currentDataType <span class="operator">=</span> Undefined;
      transferTimerId <span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>;
      isGreetingMessageSent <span class="operator">=</span> <span class="keyword">false</span>;
      pingTimer<span class="operator">.</span>setInterval(PingInterval);

      <span class="type"><a href="../qtcore/qobject.html">QObject</a></span><span class="operator">::</span>connect(<span class="keyword">this</span><span class="operator">,</span> SIGNAL(readyRead())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(processReadyRead()));
      <span class="type"><a href="../qtcore/qobject.html">QObject</a></span><span class="operator">::</span>connect(<span class="keyword">this</span><span class="operator">,</span> SIGNAL(disconnected())<span class="operator">,</span> <span class="operator">&amp;</span>pingTimer<span class="operator">,</span> SLOT(stop()));
      <span class="type"><a href="../qtcore/qobject.html">QObject</a></span><span class="operator">::</span>connect(<span class="operator">&amp;</span>pingTimer<span class="operator">,</span> SIGNAL(timeout())<span class="operator">,</span> <span class="keyword">this</span><span class="operator">,</span> SLOT(sendPing()));
      <span class="type"><a href="../qtcore/qobject.html">QObject</a></span><span class="operator">::</span>connect(<span class="keyword">this</span><span class="operator">,</span> SIGNAL(connected())<span class="operator">,</span>
                       <span class="keyword">this</span><span class="operator">,</span> SLOT(sendGreetingMessage()));
  }

  Connection<span class="operator">::</span>Connection(qintptr socketDescriptor<span class="operator">,</span> <span class="type"><a href="../qtcore/qobject.html">QObject</a></span> <span class="operator">*</span>parent)
      : Connection(parent)
  {
      setSocketDescriptor(socketDescriptor);
      reader<span class="operator">.</span>setDevice(<span class="keyword">this</span>);
  }

  Connection<span class="operator">::</span><span class="operator">~</span>Connection()
  {
      <span class="keyword">if</span> (isGreetingMessageSent) {
          <span class="comment">// Indicate clean shutdown.</span>
          writer<span class="operator">.</span>endArray();
          waitForBytesWritten(<span class="number">2000</span>);
      }
  }

  <span class="type"><a href="../qtcore/qstring.html">QString</a></span> Connection<span class="operator">::</span>name() <span class="keyword">const</span>
  {
      <span class="keyword">return</span> username;
  }

  <span class="type">void</span> Connection<span class="operator">::</span>setGreetingMessage(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&amp;</span>message)
  {
      greetingMessage <span class="operator">=</span> message;
  }

  bool Connection<span class="operator">::</span>sendMessage(<span class="keyword">const</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span> <span class="operator">&amp;</span>message)
  {
      <span class="keyword">if</span> (message<span class="operator">.</span>isEmpty())
          <span class="keyword">return</span> <span class="keyword">false</span>;

      writer<span class="operator">.</span>startMap(<span class="number">1</span>);
      writer<span class="operator">.</span>append(PlainText);
      writer<span class="operator">.</span>append(message);
      writer<span class="operator">.</span>endMap();
      <span class="keyword">return</span> <span class="keyword">true</span>;
  }

  <span class="type">void</span> Connection<span class="operator">::</span>timerEvent(<span class="type"><a href="../qtcore/qtimerevent.html">QTimerEvent</a></span> <span class="operator">*</span>timerEvent)
  {
      <span class="keyword">if</span> (timerEvent<span class="operator">-</span><span class="operator">&gt;</span>timerId() <span class="operator">=</span><span class="operator">=</span> transferTimerId) {
          abort();
          killTimer(transferTimerId);
          transferTimerId <span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>;
      }
  }

  <span class="type">void</span> Connection<span class="operator">::</span>processReadyRead()
  {
      <span class="comment">// we've got more data, let's parse</span>
      reader<span class="operator">.</span>reparse();
      <span class="keyword">while</span> (reader<span class="operator">.</span>lastError() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="../qtcore/qtcborcommon.html">QCborError</a></span><span class="operator">::</span>NoError) {
          <span class="keyword">if</span> (state <span class="operator">=</span><span class="operator">=</span> WaitingForGreeting) {
              <span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>isArray())
                  <span class="keyword">break</span>;                  <span class="comment">// protocol error</span>

              reader<span class="operator">.</span>enterContainer();    <span class="comment">// we'll be in this array forever</span>
              state <span class="operator">=</span> ReadingGreeting;
          } <span class="keyword">else</span> <span class="keyword">if</span> (reader<span class="operator">.</span>containerDepth() <span class="operator">=</span><span class="operator">=</span> <span class="number">1</span>) {
              <span class="comment">// Current state: no command read</span>
              <span class="comment">// Next state: read command ID</span>
              <span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>hasNext()) {
                  reader<span class="operator">.</span>leaveContainer();
                  disconnectFromHost();
                  <span class="keyword">return</span>;
              }

              <span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>isMap() <span class="operator">|</span><span class="operator">|</span> <span class="operator">!</span>reader<span class="operator">.</span>isLengthKnown() <span class="operator">|</span><span class="operator">|</span> reader<span class="operator">.</span>length() <span class="operator">!</span><span class="operator">=</span> <span class="number">1</span>)
                  <span class="keyword">break</span>;                  <span class="comment">// protocol error</span>
              reader<span class="operator">.</span>enterContainer();
          } <span class="keyword">else</span> <span class="keyword">if</span> (currentDataType <span class="operator">=</span><span class="operator">=</span> Undefined) {
              <span class="comment">// Current state: read command ID</span>
              <span class="comment">// Next state: read command payload</span>
              <span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>isInteger())
                  <span class="keyword">break</span>;                  <span class="comment">// protocol error</span>
              currentDataType <span class="operator">=</span> DataType(reader<span class="operator">.</span>toInteger());
              reader<span class="operator">.</span>next();
          } <span class="keyword">else</span> {
              <span class="comment">// Current state: read command payload</span>
              <span class="keyword">if</span> (reader<span class="operator">.</span>isString()) {
                  <span class="keyword">auto</span> r <span class="operator">=</span> reader<span class="operator">.</span>readString();
                  buffer <span class="operator">+</span><span class="operator">=</span> r<span class="operator">.</span>data;
                  <span class="keyword">if</span> (r<span class="operator">.</span>status <span class="operator">!</span><span class="operator">=</span> <span class="type"><a href="../qtcore/qcborstreamreader.html">QCborStreamReader</a></span><span class="operator">::</span>EndOfString)
                      <span class="keyword">continue</span>;
              } <span class="keyword">else</span> <span class="keyword">if</span> (reader<span class="operator">.</span>isNull()) {
                  reader<span class="operator">.</span>next();
              } <span class="keyword">else</span> {
                  <span class="keyword">break</span>;                   <span class="comment">// protocol error</span>
              }

              <span class="comment">// Next state: no command read</span>
              reader<span class="operator">.</span>leaveContainer();
              <span class="keyword">if</span> (transferTimerId <span class="operator">!</span><span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>) {
                  killTimer(transferTimerId);
                  transferTimerId <span class="operator">=</span> <span class="operator">-</span><span class="number">1</span>;
              }

              <span class="keyword">if</span> (state <span class="operator">=</span><span class="operator">=</span> ReadingGreeting) {
                  <span class="keyword">if</span> (currentDataType <span class="operator">!</span><span class="operator">=</span> Greeting)
                      <span class="keyword">break</span>;              <span class="comment">// protocol error</span>
                  processGreeting();
              } <span class="keyword">else</span> {
                  processData();
              }
          }
      }

      <span class="keyword">if</span> (reader<span class="operator">.</span>lastError() <span class="operator">!</span><span class="operator">=</span> <span class="type"><a href="../qtcore/qtcborcommon.html">QCborError</a></span><span class="operator">::</span>EndOfFile)
          abort();       <span class="comment">// parse error</span>

      <span class="keyword">if</span> (transferTimerId <span class="operator">!</span><span class="operator">=</span> <span class="operator">-</span><span class="number">1</span> <span class="operator">&amp;</span><span class="operator">&amp;</span> reader<span class="operator">.</span>containerDepth() <span class="operator">&gt;</span> <span class="number">1</span>)
          transferTimerId <span class="operator">=</span> startTimer(TransferTimeout);
  }

  <span class="type">void</span> Connection<span class="operator">::</span>sendPing()
  {
      <span class="keyword">if</span> (pongTime<span class="operator">.</span>elapsed() <span class="operator">&gt;</span> PongTimeout) {
          abort();
          <span class="keyword">return</span>;
      }

      writer<span class="operator">.</span>startMap(<span class="number">1</span>);
      writer<span class="operator">.</span>append(Ping);
      writer<span class="operator">.</span>append(nullptr);     <span class="comment">// no payload</span>
      writer<span class="operator">.</span>endMap();
  }

  <span class="type">void</span> Connection<span class="operator">::</span>sendGreetingMessage()
  {
      writer<span class="operator">.</span>startArray();        <span class="comment">// this array never ends</span>

      writer<span class="operator">.</span>startMap(<span class="number">1</span>);
      writer<span class="operator">.</span>append(Greeting);
      writer<span class="operator">.</span>append(greetingMessage);
      writer<span class="operator">.</span>endMap();
      isGreetingMessageSent <span class="operator">=</span> <span class="keyword">true</span>;

      <span class="keyword">if</span> (<span class="operator">!</span>reader<span class="operator">.</span>device())
          reader<span class="operator">.</span>setDevice(<span class="keyword">this</span>);
  }

  <span class="type">void</span> Connection<span class="operator">::</span>processGreeting()
  {
      username <span class="operator">=</span> buffer <span class="operator">+</span> <span class="char">'@'</span> <span class="operator">+</span> peerAddress()<span class="operator">.</span>toString() <span class="operator">+</span> <span class="char">':'</span>
              <span class="operator">+</span> <span class="type"><a href="../qtcore/qstring.html">QString</a></span><span class="operator">::</span>number(peerPort());
      currentDataType <span class="operator">=</span> Undefined;
      buffer<span class="operator">.</span>clear();

      <span class="keyword">if</span> (<span class="operator">!</span>isValid()) {
          abort();
          <span class="keyword">return</span>;
      }

      <span class="keyword">if</span> (<span class="operator">!</span>isGreetingMessageSent)
          sendGreetingMessage();

      pingTimer<span class="operator">.</span>start();
      pongTime<span class="operator">.</span>start();
      state <span class="operator">=</span> ReadyForUse;
      <span class="keyword">emit</span> readyForUse();
  }

  <span class="type">void</span> Connection<span class="operator">::</span>processData()
  {
      <span class="keyword">switch</span> (currentDataType) {
      <span class="keyword">case</span> PlainText:
          <span class="keyword">emit</span> newMessage(username<span class="operator">,</span> buffer);
          <span class="keyword">break</span>;
      <span class="keyword">case</span> Ping:
          writer<span class="operator">.</span>startMap(<span class="number">1</span>);
          writer<span class="operator">.</span>append(Pong);
          writer<span class="operator">.</span>append(nullptr);     <span class="comment">// no payload</span>
          writer<span class="operator">.</span>endMap();
          <span class="keyword">break</span>;
      <span class="keyword">case</span> Pong:
          pongTime<span class="operator">.</span>restart();
          <span class="keyword">break</span>;
      <span class="keyword">default</span>:
          <span class="keyword">break</span>;
      }

      currentDataType <span class="operator">=</span> Undefined;
      buffer<span class="operator">.</span>clear();
  }

</pre>
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<!-- @@@network-chat/connection.cpp -->
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