connection.cpp Example File

network-chat/connection.cpp
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#include "connection.h" #include <QtNetwork> static const int TransferTimeout = 30 * 1000; static const int PongTimeout = 60 * 1000; static const int PingInterval = 5 * 1000; /* * 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 => text } * ping = { 1 => null } * pong = { 2 => null } * greeting = { 3 => text } */ Connection::Connection(QObject *parent) : QTcpSocket(parent), writer(this) { greetingMessage = tr("undefined"); username = tr("unknown"); state = WaitingForGreeting; currentDataType = Undefined; transferTimerId = -1; isGreetingMessageSent = false; pingTimer.setInterval(PingInterval); QObject::connect(this, SIGNAL(readyRead()), this, SLOT(processReadyRead())); QObject::connect(this, SIGNAL(disconnected()), &pingTimer, SLOT(stop())); QObject::connect(&pingTimer, SIGNAL(timeout()), this, SLOT(sendPing())); QObject::connect(this, SIGNAL(connected()), this, SLOT(sendGreetingMessage())); } Connection::Connection(qintptr socketDescriptor, QObject *parent) : Connection(parent) { setSocketDescriptor(socketDescriptor); reader.setDevice(this); } Connection::~Connection() { if (isGreetingMessageSent) { // Indicate clean shutdown. writer.endArray(); waitForBytesWritten(2000); } } QString Connection::name() const { return username; } void Connection::setGreetingMessage(const QString &message) { greetingMessage = message; } bool Connection::sendMessage(const QString &message) { if (message.isEmpty()) return false; writer.startMap(1); writer.append(PlainText); writer.append(message); writer.endMap(); return true; } void Connection::timerEvent(QTimerEvent *timerEvent) { if (timerEvent->timerId() == transferTimerId) { abort(); killTimer(transferTimerId); transferTimerId = -1; } } void Connection::processReadyRead() { // we've got more data, let's parse reader.reparse(); while (reader.lastError() == QCborError::NoError) { if (state == WaitingForGreeting) { if (!reader.isArray()) break; // protocol error reader.enterContainer(); // we'll be in this array forever state = ReadingGreeting; } else if (reader.containerDepth() == 1) { // Current state: no command read // Next state: read command ID if (!reader.hasNext()) { reader.leaveContainer(); disconnectFromHost(); return; } if (!reader.isMap() || !reader.isLengthKnown() || reader.length() != 1) break; // protocol error reader.enterContainer(); } else if (currentDataType == Undefined) { // Current state: read command ID // Next state: read command payload if (!reader.isInteger()) break; // protocol error currentDataType = DataType(reader.toInteger()); reader.next(); } else { // Current state: read command payload if (reader.isString()) { auto r = reader.readString(); buffer += r.data; if (r.status != QCborStreamReader::EndOfString) continue; } else if (reader.isNull()) { reader.next(); } else { break; // protocol error } // Next state: no command read reader.leaveContainer(); if (transferTimerId != -1) { killTimer(transferTimerId); transferTimerId = -1; } if (state == ReadingGreeting) { if (currentDataType != Greeting) break; // protocol error processGreeting(); } else { processData(); } } } if (reader.lastError() != QCborError::EndOfFile) abort(); // parse error if (transferTimerId != -1 && reader.containerDepth() > 1) transferTimerId = startTimer(TransferTimeout); } void Connection::sendPing() { if (pongTime.elapsed() > PongTimeout) { abort(); return; } writer.startMap(1); writer.append(Ping); writer.append(nullptr); // no payload writer.endMap(); } void Connection::sendGreetingMessage() { writer.startArray(); // this array never ends writer.startMap(1); writer.append(Greeting); writer.append(greetingMessage); writer.endMap(); isGreetingMessageSent = true; if (!reader.device()) reader.setDevice(this); } void Connection::processGreeting() { username = buffer + '@' + peerAddress().toString() + ':' + QString::number(peerPort()); currentDataType = Undefined; buffer.clear(); if (!isValid()) { abort(); return; } if (!isGreetingMessageSent) sendGreetingMessage(); pingTimer.start(); pongTime.start(); state = ReadyForUse; emit readyForUse(); } void Connection::processData() { switch (currentDataType) { case PlainText: emit newMessage(username, buffer); break; case Ping: writer.startMap(1); writer.append(Pong); writer.append(nullptr); // no payload writer.endMap(); break; case Pong: pongTime.restart(); break; default: break; } currentDataType = Undefined; buffer.clear(); }

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