Update code style, fix compiler warnings

- Use nullptr instead of NULL for better warnings in case of mistakes
- Get rid of VLAs which are not in C++11 actually
- Fix implicit signed <-> unsigned mismatches by adding checks and casts

25 files changed, 194 insertions, 186 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c18a0e9..d536232 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -10,7 +10,7 @@ SET(EXTRA_CXX_FLAGS "" CACHE STRING "Additional options to pass to C++ compiler"
 # set compiler optimizations for debug and release
 SET(CMAKE_C_FLAGS_DEBUG "-O0 -g -Wall -Wunused -Wunreachable-code -pedantic")
 SET(CMAKE_C_FLAGS_RELEASE "-O2")
-SET(CMAKE_CXX_FLAGS_DEBUG "-O0 -g -Wall -Wextra -Wpedantic -std=c++0x -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wdisabled-optimization -Wfloat-equal -Wformat -Wformat=2 -Wformat-nonliteral -Wformat-security -Wformat-y2k -Wimport -Winit-self -Winline -Winvalid-pch -Wunsafe-loop-optimizations -Wlong-long -Wmissing-braces -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-include-dirs -Wmissing-noreturn -Wpacked -Wparentheses -Wpointer-arith -Wredundant-decls -Wreturn-type -Wsequence-point -Wsign-compare -Wstack-protector -Wstrict-aliasing -Wstrict-aliasing=2 -Wswitch -Wswitch-default -Wswitch-enum -Wtrigraphs -Wuninitialized -Wunknown-pragmas -Wunreachable-code -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings")
+SET(CMAKE_CXX_FLAGS_DEBUG "-O0 -g -Wall -Wextra -Wpedantic -std=c++0x -Wcast-align -Wcast-qual -Wchar-subscripts -Wcomment -Wconversion -Wdisabled-optimization -Wfloat-equal -Wformat -Wformat=2 -Wformat-nonliteral -Wformat-security -Wformat-y2k -Wimport -Winit-self -Winline -Winvalid-pch -Wlong-long -Wmissing-braces -Wmissing-field-initializers -Wmissing-format-attribute -Wmissing-include-dirs -Wmissing-noreturn -Wpacked -Wparentheses -Wpointer-arith -Wredundant-decls -Wreturn-type -Wsequence-point -Wsign-compare -Wstack-protector -Wstrict-aliasing -Wstrict-aliasing=2 -Wswitch -Wswitch-default -Wswitch-enum -Wtrigraphs -Wuninitialized -Wunknown-pragmas -Wunreachable-code -Wunused -Wunused-function -Wunused-label -Wunused-parameter -Wunused-value -Wunused-variable -Wvariadic-macros -Wvolatile-register-var -Wwrite-strings")
 SET(CMAKE_CXX_FLAGS_RELEASE "-O2")
 # -Wshadow spams too much :/
 SET(CMAKE_CXX_STANDARD 11)
diff --git a/src/client/clientapp/clientapp.cpp b/src/client/clientapp/clientapp.cpp
index 2f65bd1..962ec42 100644
--- a/src/client/clientapp/clientapp.cpp
+++ b/src/client/clientapp/clientapp.cpp
@@ -5,7 +5,7 @@
 #include "../net/serverconnection.h"
 
 ClientApp::ClientApp(int& argc, char** argv)
-	: QApplication(argc, argv), _connectionMode(ConnectionMode::None), _examMode(false), _connection(NULL), _isManagerPc(false)
+	: QApplication(argc, argv), _connectionMode(ConnectionMode::None), _examMode(false), _connection(nullptr), _isManagerPc(false)
 {
 	/* some values */
 	setOrganizationName("openslx");
@@ -31,7 +31,7 @@ ClientApp::ClientApp(int& argc, char** argv)
 
 	readIsManagerPc();
 
-	_connectWindow = new ConnectWindow(NULL);
+	_connectWindow = new ConnectWindow(nullptr);
 	connect(_connectWindow, SIGNAL(connected(ServerConnection*)), this, SLOT(connected(ServerConnection*)));
 	if (_connectionMode == ConnectionMode::Auto) {
 		_toolbar = new Toolbar(true); // auto connect client without session ID.
@@ -114,10 +114,10 @@ void ClientApp::connected(ServerConnection* connection)
 
 void ClientApp::disconnected(ServerConnection* connection)
 {
-	if (connection != NULL)
+	if (connection != nullptr)
 		connection->blockSignals(true);
 	if (_connection == connection) {
-		_connection = NULL;
+		_connection = nullptr;
 	}
 }
 
diff --git a/src/client/clientapp/clientapp.h b/src/client/clientapp/clientapp.h
index 0f7cb5b..91dccf3 100644
--- a/src/client/clientapp/clientapp.h
+++ b/src/client/clientapp/clientapp.h
@@ -58,7 +58,7 @@ public:
 
 	bool isConfiguredAsManager() { return _isManagerPc; }
 
-	bool isConnectedToLocalManager() { return _connection != NULL && _connection->isLocalConnection(); }
+	bool isConnectedToLocalManager() { return _connection != nullptr && _connection->isLocalConnection(); }
 
 private slots:
 
diff --git a/src/client/connectwindow/connectwindow.cpp b/src/client/connectwindow/connectwindow.cpp
index b1f583a..c77a5e6 100644
--- a/src/client/connectwindow/connectwindow.cpp
+++ b/src/client/connectwindow/connectwindow.cpp
@@ -27,7 +27,7 @@ ConnectWindow::ConnectWindow(QWidget *parent) :	QWidget(parent)
 	_timerHide = 0;
 	_state = Idle;
 	_hashSslErrorCount = 0;
-	_pendingConnection = NULL;
+	_pendingConnection = nullptr;
 
 	// Initialize the GUI
 	_ui->setupUi(this);
@@ -320,7 +320,7 @@ void ConnectWindow::onConnectionStateChange(ConnectWindow::ConnectionState state
 		QObject::disconnect(_pendingConnection, SIGNAL(stateChange(ConnectWindow::ConnectionState)), this, SLOT(onConnectionStateChange(ConnectWindow::ConnectionState)));
 		QObject::disconnect(_pendingConnection, SIGNAL(destroyed(QObject*)), this, SLOT(onConnectionClosed(QObject*)));
 		emit connected(_pendingConnection);
-		_pendingConnection = NULL;
+		_pendingConnection = nullptr;
 
 		this->updateUserInterface();
 
@@ -341,12 +341,12 @@ void ConnectWindow::onComboBox_keyPressed(QKeyEvent* e)
 }
 
 /***************************************************************************//**
- * If connection is closed set _pendingConnection = NULL.
+ * If connection is closed set _pendingConnection = nullptr.
  * @param connection
  */
 void ConnectWindow::onConnectionClosed(QObject* /* connection */ )
 {
-	_pendingConnection = NULL;
+	_pendingConnection = nullptr;
 }
 
 /***************************************************************************//**
diff --git a/src/client/connectwindow/connectwindow.h b/src/client/connectwindow/connectwindow.h
index 51b1bf2..af45db6 100644
--- a/src/client/connectwindow/connectwindow.h
+++ b/src/client/connectwindow/connectwindow.h
@@ -54,7 +54,7 @@ public:
 		Connected
 	};
 
-	explicit ConnectWindow(QWidget *parent = NULL);
+	explicit ConnectWindow(QWidget *parent = nullptr);
 	virtual ~ConnectWindow();
 
 	void connectToSession(const QByteArray sessionName, QString mgrIP);
diff --git a/src/client/net/serverconnection.cpp b/src/client/net/serverconnection.cpp
index 0cbd4c2..6350418 100644
--- a/src/client/net/serverconnection.cpp
+++ b/src/client/net/serverconnection.cpp
@@ -19,7 +19,7 @@
 #define CHALLENGE_LEN 20
 
 ServerConnection::ServerConnection(const QString& host, const quint16 port, const QByteArray& sessionName, const QByteArray& certHash, bool autoConnect) :
-	QObject(NULL), _timerDelete(0), _jpegQuality(80), _authed(0), _autoConnect(autoConnect), _isLocalConnection(-1), _sessionName(sessionName), _certHash(certHash)
+	QObject(nullptr), _timerDelete(0), _jpegQuality(80), _authed(0), _autoConnect(autoConnect), _isLocalConnection(-1), _sessionName(sessionName), _certHash(certHash)
 {
 	_socket = new QSslSocket();
 	_blank = new BlankScreen();
@@ -46,13 +46,13 @@ ServerConnection::ServerConnection(const QString& host, const quint16 port, cons
 ServerConnection::~ServerConnection()
 {
 	this->disconnectFromServer();
-	if (_socket != NULL) {
+	if (_socket != nullptr) {
 		qCritical("**** SOCKET DELETE IN DESTRUCTOR");
 		_socket->deleteLater();
 	}
 	qDebug("*** Server connection destroyed.");
 	_blank->deleteLater();
-	_blank = NULL;
+	_blank = nullptr;
 }
 
 /**
@@ -60,7 +60,7 @@ ServerConnection::~ServerConnection()
  */
 void ServerConnection::sendMessage(NetworkMessage& message)
 {
-	if (_socket == NULL || _socket->state() != QAbstractSocket::ConnectedState)
+	if (_socket == nullptr || _socket->state() != QAbstractSocket::ConnectedState)
 		return;
 	message.writeMessage(_socket);
 	if (!message.writeComplete()) {
@@ -89,7 +89,7 @@ void ServerConnection::disconnectFromServer()
 		emit disconnected(this);
 		_timerDelete = startTimer(500);
 		qDebug("Closing connection to server");
-		if (_socket != NULL) {
+		if (_socket != nullptr) {
 			_socket->blockSignals(true);
 			_socket->abort();
 		}
@@ -144,11 +144,11 @@ void ServerConnection::handleMsg()
 			}
 			emit stateChange(ConnectWindow::LoggingIn);
 			const char *user = getpwuid(getuid())->pw_name;
-			if (user == NULL || *user == '\0')
+			if (user == nullptr || *user == '\0')
 				user = getenv("USER");
-			if (user == NULL || *user == '\0')
+			if (user == nullptr || *user == '\0')
 				user = getenv("USERNAME");
-			if (user == NULL || *user == '\0')
+			if (user == nullptr || *user == '\0')
 				user = "Hans Affe";
 			_toServer.reset();
 			_toServer.setField(_ID, _LOGIN);
@@ -269,7 +269,7 @@ void ServerConnection::handleMsg()
 
 void ServerConnection::checkLocalConnection()
 {
-	if (_socket == NULL) {
+	if (_socket == nullptr) {
 		return;
 	}
 	if (_socket->peerAddress() == _socket->localAddress()) {
@@ -297,10 +297,10 @@ void ServerConnection::timerEvent(QTimerEvent *event)
 		_timerId = 0;
 		this->disconnectFromServer();
 	} else if (event->timerId() == _timerDelete) {
-		if (_socket == NULL || _socket->state() == QAbstractSocket::UnconnectedState) {
-			if (_socket != NULL)
+		if (_socket == nullptr || _socket->state() == QAbstractSocket::UnconnectedState) {
+			if (_socket != nullptr)
 				_socket->deleteLater();
-			_socket = NULL;
+			_socket = nullptr;
 			killTimer(_timerDelete);
 			this->deleteLater();
 			return;
@@ -375,7 +375,7 @@ void ServerConnection::sslErrors(const QList<QSslError> & errors)
 
 void ServerConnection::sock_dataArrival()
 {
-	if (_socket == NULL || _socket->state() != QAbstractSocket::ConnectedState) {
+	if (_socket == nullptr || _socket->state() != QAbstractSocket::ConnectedState) {
 		qDebug("dataArrival called in bad state");
 		return;
 	}
@@ -390,7 +390,7 @@ void ServerConnection::sock_dataArrival()
 			return;
 		if (_fromServer.readComplete()) { // message is complete
 			this->handleMsg();
-			if (_socket == NULL)
+			if (_socket == nullptr)
 				return;
 			_fromServer.reset();
 		}
diff --git a/src/client/net/serverconnection.h b/src/client/net/serverconnection.h
index 9db9b02..f5f6264 100644
--- a/src/client/net/serverconnection.h
+++ b/src/client/net/serverconnection.h
@@ -38,7 +38,7 @@ public:
 	~ServerConnection();
 	inline bool isConnected() const
 	{
-		return _socket != NULL && _socket->state() == QAbstractSocket::ConnectedState;
+		return _socket != nullptr && _socket->state() == QAbstractSocket::ConnectedState;
 	}
 
 	const inline QString getPeerAdress() const
diff --git a/src/client/net/serverdiscovery.cpp b/src/client/net/serverdiscovery.cpp
index 33ddbf5..799fcbe 100644
--- a/src/client/net/serverdiscovery.cpp
+++ b/src/client/net/serverdiscovery.cpp
@@ -145,12 +145,12 @@ void ServerDiscovery::onUdpReadyRead()
 	while (_discoverySocket.hasPendingDatagrams()) {
 		// Discard any packets if discovery is stopped
 		if (!this->isActive()) {
-			_discoverySocket.readDatagram(NULL, 0);
+			_discoverySocket.readDatagram(nullptr, 0);
 			continue;
 		}
 
 		const qint64 size = _discoverySocket.readDatagram(data, UDPBUFSIZ, &addr, &port);
-		if (size <= 0) //|| clientApp->connection() != NULL) // TODO CHECK
+		if (size <= 0) //|| clientApp->connection() != nullptr) // TODO CHECK
 			continue;
 
 		_packet.reset();
diff --git a/src/client/toolbar/toolbar.cpp b/src/client/toolbar/toolbar.cpp
index 955731a..a8e50e9 100644
--- a/src/client/toolbar/toolbar.cpp
+++ b/src/client/toolbar/toolbar.cpp
@@ -99,7 +99,7 @@ void Toolbar::init()
 	setAttribute(Qt::WA_DeleteOnClose, false);
 
 	/* Create the VNC Window */
-	_vnc = new VncWindow(NULL);
+	_vnc = new VncWindow(nullptr);
 
 	/* Create the connect window */
 	clientApp->connectWindow()->setAvailableRooms(myRooms());
@@ -353,7 +353,7 @@ void Toolbar::onVncServerIsRunning(int port)
  */
 void Toolbar::onDisconnected(ServerConnection* connection)
 {
-	if (connection != NULL) {
+	if (connection != nullptr) {
 		disconnect(connection, SIGNAL(disconnected(ServerConnection*)), this, SLOT(onDisconnected(ServerConnection*)));
 	}
 	_ui->lblStatus->setStyleSheet("color:red");
@@ -398,7 +398,7 @@ void Toolbar::onConnected(ServerConnection* connection)
  */
 void Toolbar::onDoDisconnect()
 {
-	if (clientApp->connection() != NULL)
+	if (clientApp->connection() != nullptr)
 		clientApp->connection()->disconnectFromServer();
 }
 
@@ -486,12 +486,12 @@ void Toolbar::showInformationDialog()
 
 void Toolbar::onBtnAttention()
 {
-	const bool on = clientApp->connection() != NULL && _ui->btnAttention->isChecked();
+	const bool on = clientApp->connection() != nullptr && _ui->btnAttention->isChecked();
 	if (on != _ui->btnAttention->isChecked()) {
 		_ui->btnAttention->setChecked(on);
 		return;
 	}
-	if (clientApp->connection() != NULL) {
+	if (clientApp->connection() != nullptr) {
 		clientApp->connection()->sendAttention(on);
 	}
 }
diff --git a/src/client/util/platform/blankscreen.cpp b/src/client/util/platform/blankscreen.cpp
index ee644ca..bf34614 100644
--- a/src/client/util/platform/blankscreen.cpp
+++ b/src/client/util/platform/blankscreen.cpp
@@ -16,11 +16,11 @@ struct BlankScreen_Sysdep {
 	Display *dpy;
 };
 
-BlankScreen::BlankScreen() : QDialog(NULL)
+BlankScreen::BlankScreen() : QDialog(nullptr)
 {
 	_sysdep = new BlankScreen_Sysdep;
-	_sysdep->dpy = XOpenDisplay(NULL);
-	if (_sysdep->dpy == NULL)
+	_sysdep->dpy = XOpenDisplay(nullptr);
+	if (_sysdep->dpy == nullptr)
 		return;
 
 	setWindowFlags(Qt::WindowStaysOnTopHint | Qt::X11BypassWindowManagerHint | Qt::FramelessWindowHint);
@@ -35,7 +35,7 @@ BlankScreen::BlankScreen() : QDialog(NULL)
 BlankScreen::~BlankScreen()
 {
 	unlock();
-	if (_sysdep->dpy != NULL) {
+	if (_sysdep->dpy != nullptr) {
 		XCloseDisplay(_sysdep->dpy);
 	}
 	delete _sysdep;
@@ -45,7 +45,7 @@ bool BlankScreen::lock(const QString& message)
 {
 	if (_locked)
 		return true;
-	if (_sysdep->dpy == NULL)
+	if (_sysdep->dpy == nullptr)
 		return false;
 
 	_message = message;
@@ -73,7 +73,7 @@ bool BlankScreen::unlock()
 	this->hide();
 	if (!_locked)
 		return true;
-	if (_sysdep->dpy == NULL)
+	if (_sysdep->dpy == nullptr)
 		return false;
 
 	// ungrabbing of keyboard and mouse
diff --git a/src/client/vnc/vncserver.cpp b/src/client/vnc/vncserver.cpp
index 165ba6d..a016f08 100644
--- a/src/client/vnc/vncserver.cpp
+++ b/src/client/vnc/vncserver.cpp
@@ -12,7 +12,7 @@
 #include "vncserver.h"
 #include "../util/util.h"
 
-VncServer* VncServer::me = NULL;
+VncServer* VncServer::me = nullptr;
 
 /***************************************************************************//**
  * @brief VncServer::instance
@@ -20,7 +20,7 @@ VncServer* VncServer::me = NULL;
  */
 VncServer* VncServer::instance()
 {
-	if (me == NULL)
+	if (me == nullptr)
 		me = new VncServer();
 	return me;
 }
@@ -32,10 +32,10 @@ VncServer* VncServer::instance()
  */
 static QString makePassword(int len = 10)
 {
-	char pass[len];
+	QString ret(len, Qt::Uninitialized);
 	for (int i = 0; i < len; ++i)
-		pass[i] = (char)(43 + qrand() % 80);
-	return QString::fromUtf8(pass, len);
+		ret[i] = QChar(43 + qrand() % 80);
+	return ret;
 }
 
 /***************************************************************************//**
@@ -48,7 +48,7 @@ struct Sleeper : public QThread {
 /***************************************************************************//**
  * @brief VncServer::VncServer
  */
-VncServer::VncServer() : _process(NULL), _port(0), _timerId(0) {}
+VncServer::VncServer() : _process(nullptr), _port(0), _timerId(0) {}
 
 /***************************************************************************//**
  * @brief VncServer::~VncServer
@@ -73,7 +73,7 @@ QSharedPointer<QFile> VncServer::createPwFile(const QDir& dir)
 void VncServer::start()
 {
 	// Keep things clean
-	if (_process != NULL) {
+	if (_process != nullptr) {
 		disconnect(_process, SIGNAL(error(QProcess::ProcessError)), this, SLOT(onError(QProcess::ProcessError)));
 		disconnect(_process, SIGNAL(finished(int)), this, SLOT(onFinished(int)));
 	}
@@ -138,13 +138,13 @@ void VncServer::stop()
 		killTimer(_timerId);
 		_timerId = 0;
 	}
-	if (_process == NULL)
+	if (_process == nullptr)
 		return;
 	qDebug("Stopping old VNC server.");
 	disconnect(_process, SIGNAL(readyReadStandardOutput()), this, SLOT(onStdOut()));
 	disconnect(_process, SIGNAL(readyReadStandardError()), this, SLOT(onStdErr()));
 	QProcess *process = _process;
-	_process = NULL;
+	_process = nullptr;
 	_port = 0;
 	process->terminate();
 	for (int i = 0; i < 10 && process->state() != QProcess::NotRunning; ++i)
@@ -185,7 +185,7 @@ void VncServer::timerEvent(QTimerEvent * /* event */ )
  */
 void VncServer::onStdOut()
 {
-	if (_process == NULL) {
+	if (_process == nullptr) {
 		qDebug("VncServer::onStdOut() called in bad state.");
 		return;
 	}
@@ -211,7 +211,7 @@ void VncServer::onStdOut()
  */
 void VncServer::onStdErr()
 {
-	if (_process == NULL) {
+	if (_process == nullptr) {
 		qDebug("VncServer::onStdErr() called in bad state.");
 		return;
 	}
diff --git a/src/client/vnc/vncthread.cpp b/src/client/vnc/vncthread.cpp
index 1dbe005..e399e9b 100644
--- a/src/client/vnc/vncthread.cpp
+++ b/src/client/vnc/vncthread.cpp
@@ -36,7 +36,7 @@ VncThread::VncThread(QString host, int port, QString passwd, int quality) :
 	_port = port;
 	_passwd = passwd;
 	_quality = quality;
-	_client = NULL;
+	_client = nullptr;
 	_connected = false;
 	moveToThread(this);
 }
@@ -45,7 +45,7 @@ VncThread::~VncThread()
 {
 	qDebug("VNC worker destructor called.");
 	Q_ASSERT(_run == false);
-	if (_client != NULL) {
+	if (_client != nullptr) {
 		if (_client->sock != -1)
 			::close(_client->sock);
 		_client->sock = -1;
@@ -82,27 +82,27 @@ void VncThread::run()
 		_client->canHandleNewFBSize = true;
 		free(_client->serverHost); // in rfbGetClient, serverHost is assigned strdup(""), so free that first.
 		_client->serverHost = strdup(_host.toUtf8().constData());
-		_client->desktopName = NULL;
+		_client->desktopName = nullptr;
 		_client->serverPort = _port;
 		_client->GetPassword = &passwdHandler;
 		_client->GotFrameBufferUpdate = &updateImage;
-		_client->frameBuffer = NULL;
+		_client->frameBuffer = nullptr;
 
 		// save this instance in vnc-struct for callbacks
 		rfbClientSetClientData(_client, 0, this);
 
 		// start client
-		if (rfbInitClient(_client, NULL, NULL)) {
+		if (rfbInitClient(_client, nullptr, nullptr)) {
 			break; // Success!
 		}
 		// Connection failed
-		_client = NULL; // InitClient frees the client on failure, so make sure we don't keep an invalid pointer around
+		_client = nullptr; // InitClient frees the client on failure, so make sure we don't keep an invalid pointer around
 		if (!_run)
 			break;
 		// error, let's try again
 		this->msleep(10 + qrand() % 50);
 	}
-	if (_client != NULL) {
+	if (_client != nullptr) {
 		qDebug("[%s] Connection successful!", metaObject()->className());
 		int one = 1;
 		setsockopt(_client->sock, SOL_TCP, TCP_NODELAY, &one, sizeof(one));
@@ -136,7 +136,7 @@ void VncThread::run()
  */
 const QString VncThread::getDesktopName() const
 {
-	if (_client == NULL || _client->desktopName == NULL)
+	if (_client == nullptr || _client->desktopName == nullptr)
 		return QString();
 	return QString(_client->desktopName);
 }
@@ -189,6 +189,11 @@ rfbBool VncThread::frameBufferHandler(rfbClient *client)
 	const int width = client->width, height = client->height, depth = 32;
 	const int size = width * height * (depth / 8);
 	qDebug("[%s] Remote desktop: %ix%ix%i", t->metaObject()->className(), width, height, depth);
+	if (width < 0 || height < 0 || size < 0) {
+		qWarning() << "IGNORING INVALID FRAMEBUFFER SIZE";
+		client->frameBuffer = nullptr;
+		return false;
+	}
 
 	t->_img = QSharedPointer<QImage>(new QImage(width, height, QImage::Format_RGB32));
 	if (size > t->_img->byteCount()) {
@@ -196,7 +201,7 @@ rfbBool VncThread::frameBufferHandler(rfbClient *client)
 		::exit(1);
 	}
 	client->frameBuffer = t->_img->bits();
-	memset(client->frameBuffer, '\0', size);
+	memset(client->frameBuffer, '\0', (size_t)size);
 	client->format.trueColour = 1;
 	client->format.bitsPerPixel = depth;
 	client->format.redShift = 16;
diff --git a/src/client/vnc/vncwindow.cpp b/src/client/vnc/vncwindow.cpp
index 79352ae..a9d85f4 100644
--- a/src/client/vnc/vncwindow.cpp
+++ b/src/client/vnc/vncwindow.cpp
@@ -37,7 +37,7 @@ static int gcd(int a, int b)
 
 VncWindow::VncWindow(QWidget *parent) :
 	QWidget(parent), _srcStepX(1), _srcStepY(1), _dstStepX(1), _dstStepY(1),
-	_vncWorker(NULL), _viewOnly(true), _multiScreen(false), _clientId(0), _redrawTimer(0), _tcpTimeoutTimer(0)
+	_vncWorker(nullptr), _viewOnly(true), _multiScreen(false), _clientId(0), _redrawTimer(0), _tcpTimeoutTimer(0)
 {
 	QTimer *upper = new QTimer(this);
 	connect(upper, SIGNAL(timeout()), this, SLOT(timer_moveToTop()));
@@ -55,13 +55,13 @@ VncWindow::~VncWindow()
 /**
  * Terminates the vnc worker thread and stops all related timers.
  * The thread will be signalled to stop, but we don't wait for it
- * to actually terminate. All signals of the thread are blocked, and we NULL
+ * to actually terminate. All signals of the thread are blocked, and we nullptr
  * our reference to it. It will finish running in a detached state and finally
  * delete itself upon completion.
  */
 void VncWindow::terminateVncThread()
 {
-	if (_vncWorker == NULL)
+	if (_vncWorker == nullptr)
 		return;
 
 	disconnect(_vncWorker, SIGNAL(projectionStopped()), this, SLOT(onProjectionStopped()));
@@ -69,7 +69,7 @@ void VncWindow::terminateVncThread()
 	disconnect(_vncWorker, SIGNAL(imageUpdated(const int, const int, const int, const int)), this,
 			SLOT(onUpdateImage(const int, const int, const int, const int)));
 	_vncWorker->stop();
-	_vncWorker = NULL;
+	_vncWorker = nullptr;
 	if (_redrawTimer != 0) {
 		killTimer(_redrawTimer);
 		_redrawTimer = 0;
@@ -96,7 +96,7 @@ void VncWindow::deleteVncThread()
  */
 void VncWindow::draw(const int x, const int y, const int w, const int h)
 {
-	if (_vncWorker == NULL)
+	if (_vncWorker == nullptr)
 		return;
 	QSharedPointer<QImage> buffer = _vncWorker->getFrameBuffer();
 	if (buffer.isNull())
@@ -147,10 +147,10 @@ void VncWindow::draw(const int x, const int y, const int w, const int h)
 bool VncWindow::calcScaling(const QImage *remote)
 {
 	if (this->size() == _desiredSize &&
-			(remote == NULL || remote->size() == _remoteSize))
+			(remote == nullptr || remote->size() == _remoteSize))
 		return false;
 	const QSize mySize = this->size();
-	const QSize remoteSize = remote == NULL ? _remoteSize : remote->size();
+	const QSize remoteSize = remote == nullptr ? _remoteSize : remote->size();
 	if (mySize.isEmpty())
 		return false;
 	if (remoteSize.isEmpty())
@@ -270,7 +270,7 @@ void VncWindow::closeEvent(QCloseEvent * /* e */ )
  */
 void VncWindow::onUpdateImage(const int x, const int y, const int w, const int h)
 {
-	if (_vncWorker == NULL)
+	if (_vncWorker == nullptr)
 		return;
 	if (!this->calcScaling(_vncWorker->getFrameBuffer().data()) && !_remoteSize.isEmpty()) {
 		if (_srcStepX > 1 || _srcStepY > 1) {
@@ -345,7 +345,7 @@ void VncWindow::timerEvent(QTimerEvent *event)
 	} else if (event->timerId() == _tcpTimeoutTimer) {
 		killTimer(_tcpTimeoutTimer);
 		_tcpTimeoutTimer = 0;
-		if (_vncWorker != NULL && !_vncWorker->isConnected()) {
+		if (_vncWorker != nullptr && !_vncWorker->isConnected()) {
 			this->close();
 		}
 	} else
@@ -362,7 +362,7 @@ void VncWindow::timerEvent(QTimerEvent *event)
  */
 void VncWindow::paintEvent(QPaintEvent *event)
 {
-	if (_vncWorker == NULL || !_vncWorker->isConnected()) {
+	if (_vncWorker == nullptr || !_vncWorker->isConnected()) {
 		QPainter painter(this);
 		if (!_remoteThumb.isNull() && _remoteThumb.height() > 0) {
 			painter.drawPixmap(0, 0, this->width(), this->height(), _remoteThumb);
diff --git a/src/server/connectionframe/connectionframe.cpp b/src/server/connectionframe/connectionframe.cpp
index 875e031..e8d8349 100644
--- a/src/server/connectionframe/connectionframe.cpp
+++ b/src/server/connectionframe/connectionframe.cpp
@@ -58,7 +58,7 @@ static QString style_disconnected(
 		QGroupBox { background-color: #7F7F7F; margin: 1px; border-radius: 4px}"
 );
 
-static QIcon *term = NULL, *cam = NULL, *eye = NULL, *lock = NULL;
+static QIcon *term = nullptr, *cam = nullptr, *eye = nullptr, *lock = nullptr;
 
 bool ConnectionFrame::paintDisabled = false;
 
@@ -69,13 +69,13 @@ bool ConnectionFrame::paintDisabled = false;
  * @param height
  */
 ConnectionFrame::ConnectionFrame(MainWindow* main, QWidget *parent, bool fromRoomplan) :
-	QGroupBox(parent), _client(NULL), _timerId(0), _timerCounter(0), _isSelected(false), _isTutor(false),
+	QGroupBox(parent), _client(nullptr), _timerId(0), _timerCounter(0), _isSelected(false), _isTutor(false),
 	_isFromRoomplan(fromRoomplan), _mainWindow(main)
 {
 
 	//defines the ui-stuff
 	// load icons first
-	if (term == NULL) {
+	if (term == nullptr) {
 		term = new QIcon(":terminal");
 		cam = new QIcon(":cf_cam");
 		eye = new QIcon(":cf_eye");
@@ -88,7 +88,7 @@ ConnectionFrame::ConnectionFrame(MainWindow* main, QWidget *parent, bool fromRoo
 	_mainLayout->setAlignment(Qt::AlignHCenter);
 	this->setStyleSheet(style_student);
 
-	_iconLayout = new QBoxLayout(QBoxLayout::RightToLeft, NULL);
+	_iconLayout = new QBoxLayout(QBoxLayout::RightToLeft, nullptr);
 	_iconLayout->setSpacing(1);
 	_iconLayout->setMargin(3);
 
@@ -124,7 +124,7 @@ ConnectionFrame::ConnectionFrame(MainWindow* main, QWidget *parent, bool fromRoo
 
 ConnectionFrame::~ConnectionFrame()
 {
-	if (_client != NULL) {
+	if (_client != nullptr) {
 		_client->deleteLater();
 	}
 	_iconLayout->deleteLater();
@@ -145,7 +145,7 @@ void ConnectionFrame::updateGeometry()
 {
 	const QRect rect = _mainWindow->calcFrameGeometry(this);
 	setGeometry(rect);
-	if (this->_client == NULL)
+	if (this->_client == nullptr)
 		showDefaultThumb();
 }
 
@@ -171,7 +171,7 @@ QLabel* ConnectionFrame::addIcon(const QIcon* icon)
  */
 void ConnectionFrame::assignClient(Client* client)
 {
-	assert(_client == NULL);
+	assert(_client == nullptr);
 	connect( client, SIGNAL(disconnected()), this, SLOT(onClientDisconnected()) );
 	connect( client, SIGNAL(thumbUpdated(Client*, const QImage&)), this, SLOT(onThumbUpdated(Client*, const QImage&)) );
 	connect( client, SIGNAL(vncServerStateChange(Client*)), this, SLOT(updateAppearance()));
@@ -206,7 +206,7 @@ void ConnectionFrame::calcDesiredThumbSize(const QSize &frameSize)
 void ConnectionFrame::updateLabels()
 {
 	_lblHostName->setText(_computerId);
-	if (_client == NULL) {
+	if (_client == nullptr) {
 		_lblUserName->setText(QString());
 		_lblUserName->hide();
 	} else {
@@ -331,7 +331,7 @@ void ConnectionFrame::paintEvent(QPaintEvent *event)
  */
 void ConnectionFrame::timerEvent(QTimerEvent* /* event */ )
 {
-	if (_client == NULL)
+	if (_client == nullptr)
 		return;
 	++_timerCounter;
 	if (_client->isActiveVncServer() && _timerCounter % 5 != 0)
@@ -357,7 +357,7 @@ void ConnectionFrame::setSelection(bool selected)
  */
 void ConnectionFrame::setTutor(bool b)
 {
-	if (_isTutor != b && _client != NULL)
+	if (_isTutor != b && _client != nullptr)
 		_client->setTutor(b);
 	_isTutor = b;
 	this->updateAppearance();
@@ -369,7 +369,7 @@ void ConnectionFrame::setTutor(bool b)
  */
 void ConnectionFrame::updateAppearance()
 {
-	if (_client == NULL) {
+	if (_client == nullptr) {
 		// Unconnected Frame
 		if (_isSelected) {
 			this->setStyleSheet(style_selectedStudent);
@@ -426,7 +426,7 @@ void ConnectionFrame::onClientDisconnected()
 		killTimer(_timerId);
 		_timerId = 0;
 	}
-	_client = NULL;
+	_client = nullptr;
 	updateLabels();
 	updateAppearance();
 	showDefaultThumb();
diff --git a/src/server/connectionframe/connectionframe.h b/src/server/connectionframe/connectionframe.h
index 898d97a..ba5f235 100644
--- a/src/server/connectionframe/connectionframe.h
+++ b/src/server/connectionframe/connectionframe.h
@@ -66,7 +66,7 @@ public:
 	inline bool isSelected() { return _isSelected; }
 
 	const QString& computerId() const { return _computerId; }
-	void setComputerId(QString computerId) { if (_client != NULL) return; _computerId = computerId; updateLabels(); }
+	void setComputerId(QString computerId) { if (_client != nullptr) return; _computerId = computerId; updateLabels(); }
 	Client* client() const { return _client; }
 
 	inline bool isTutor() { return _isTutor; }
diff --git a/src/server/mainwindow/mainwindow.cpp b/src/server/mainwindow/mainwindow.cpp
index 5daade4..dcf8973 100644
--- a/src/server/mainwindow/mainwindow.cpp
+++ b/src/server/mainwindow/mainwindow.cpp
@@ -190,7 +190,7 @@ void MainWindow::clientCountChanged()
 
 	for (auto it = _clientFrames.begin(); it != _clientFrames.end(); ++it) {
 		Client* c = (*it)->client();
-		if (c != NULL) {
+		if (c != nullptr) {
 			bool b = c->isExamMode();
 			examClientCount += b ? 1 : 0;
 			clientCount++;
@@ -262,7 +262,7 @@ int distance(QPointF a, QPointF b)
 QPoint MainWindow::closestFreeSlot(QPoint preferredPixels, ConnectionFrame* toIgnore)
 {
 	const bool pickFirstOne = ( preferredPixels == QPoint(-1, -1) );
-	if (!pickFirstOne && toIgnore != NULL) {
+	if (!pickFirstOne && toIgnore != nullptr) {
 		// Check if we're already in the desired location and skip all the checks
 		QPoint desired = QPoint(preferredPixels.x() / getTileWidthPx(), preferredPixels.y() / getTileHeightPx());
 		if (desired == toIgnore->getGridPosition()) {
@@ -270,8 +270,9 @@ QPoint MainWindow::closestFreeSlot(QPoint preferredPixels, ConnectionFrame* toIg
 		}
 	}
 	const QSize& clientSize = serverApp->getCurrentRoom()->clientSize;
-	bool grid[_tilesX][_tilesY];
-	memset(grid, 0, sizeof(bool) * _tilesX * _tilesY); /* set everything to false */
+#define GRID(X,Y) (grid[X * _tilesX + Y])
+	bool *grid = new bool[_tilesX * _tilesY];
+	memset(grid, 0, sizeof(bool) * size_t(_tilesX * _tilesY)); /* set everything to false */
 
 	/* fill grid */
 	for (auto  it = _clientFrames.begin(); it != _clientFrames.end(); ++it) {
@@ -282,7 +283,7 @@ QPoint MainWindow::closestFreeSlot(QPoint preferredPixels, ConnectionFrame* toIg
 
 		for (int x = p.x(); x < p.x() + clientSize.width(); x++) {
 			for (int y = p.y(); y < p.y() + clientSize.height(); y++) {
-				grid[x][y] = true;
+				GRID(x, y) = true;
 			}
 		}
 	}
@@ -295,7 +296,7 @@ QPoint MainWindow::closestFreeSlot(QPoint preferredPixels, ConnectionFrame* toIg
 			bool isFree = true;
 			for (int dx = 0; dx < clientSize.width(); dx++) {
 				for (int dy = 0; dy < clientSize.height(); dy++) {
-					if (grid[x + dx][y + dy]) {
+					if (GRID(x + dx, y + dy)) {
 						isFree = false;
 						goto endLoop; // double-break
 					}
@@ -311,6 +312,8 @@ endLoop: ;
 		}
 	}
 endSearch: ;
+#undef GRID
+	delete[] grid;
 	/* among all the free positions, find the closest */
 	int min_distance = 1000000;
 	QPoint bestPosition = QPoint(0, 0);
@@ -342,7 +345,7 @@ void MainWindow::placeFrameInFreeSlot(ConnectionFrame* frame, QPoint preferredPi
 ConnectionFrame* MainWindow::createFrame(const QString &computerId, const QPoint* gridPosition, bool fromRoomplan)
 {
 	ConnectionFrame *cf = new ConnectionFrame(this, ui->frmRoom, fromRoomplan);
-	if (gridPosition == NULL) {
+	if (gridPosition == nullptr) {
 		placeFrameInFreeSlot(cf);
 	} else {
 		cf->setGridPosition(*gridPosition);
@@ -378,47 +381,47 @@ void MainWindow::tellClientCurrentSituation(Client* client)
  * Returns connected client which belongs to given id.
  * Iterating over ConnectionFrames and comparing id to given id.
  * @param id
- * @return Client with given id, if not NULL.
+ * @return Client with given id, if not nullptr.
  */
 Client* MainWindow::getClientFromId(int id)
 {
 	for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
-		if ((*it)->client() != NULL) {
+		if ((*it)->client() != nullptr) {
 			if ((*it)->client()->id() == id)
 				return (*it)->client();
 		}
 	}
-	return NULL;
+	return nullptr;
 }
 
 /***************************************************************************//**
  * Return the Frame, which is currently beeing Tutor.
  * Iterating over all ConnectionFrames, and looking for flag _isTutor.
  * @return Frame with flag _isTutor = true,
- * else NULL if no Tutor is available.
+ * else nullptr if no Tutor is available.
  */
 ConnectionFrame* MainWindow::getTutorFrame()
 {
 	for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
-		if (((*it) != NULL) && ((*it)->isTutor()))
+		if (((*it) != nullptr) && ((*it)->isTutor()))
 			return (*it);
 	}
-	return NULL;
+	return nullptr;
 }
 
 /***************************************************************************//**
  * Return the Frame, which is currently selected by user.
  * Iterating over all ConnectionFrame and looking for flag _isSelected.
  * @return Frame with flag _isSelected = true,
- * else NULL if no frame is selected.
+ * else nullptr if no frame is selected.
  */
 ConnectionFrame* MainWindow::getSelectedFrame()
 {
 	for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
-		if (((*it) != NULL) && ((*it)->isSelected()))
+		if (((*it) != nullptr) && ((*it)->isSelected()))
 			return (*it);
 	}
-	return NULL;
+	return nullptr;
 }
 
 /*
@@ -527,7 +530,7 @@ void MainWindow::resizeEvent(QResizeEvent* /* e */ )
 	}
 
 	/* update background image label */
-	if (_backgroundImage != NULL) {
+	if (_backgroundImage != nullptr) {
 		int w = ui->frmRoom->width() - 5; /* to make sure that we don't enlarge the window */
 		int h = ui->frmRoom->height() - 5;
 		ui->imageLabel->hide();
@@ -553,10 +556,10 @@ void MainWindow::unlockContextButtons()
 		(*it)->setEnabled(true);
 	}
 	/* and disable some again based on special rules */
-	if (getSelectedFrame()->client() != NULL) {
+	if (getSelectedFrame()->client() != nullptr) {
 		ui->action_DeleteClient->setEnabled(false);
 	}
-	if (getSelectedFrame()->client() == NULL) {
+	if (getSelectedFrame()->client() == nullptr) {
 		ui->action_SetAsTutor->setEnabled(false);
 		ui->action_StudentToTutorExclusive->setEnabled(false);
 		ui->action_StudentToTutor->setEnabled(false);
@@ -583,7 +586,7 @@ void MainWindow::mouseReleaseEvent(QMouseEvent* e)
 	const QSize frame(ui->frmRoom->size());
 	if (frame.width() > pos.x() && frame.height() > pos.y()) {
 		lockContextButtons();
-		if (getSelectedFrame() != NULL) {
+		if (getSelectedFrame() != nullptr) {
 			getSelectedFrame()->setSelection(false);
 		}
 	}
@@ -598,13 +601,13 @@ void MainWindow::reset(bool lock)
 
 	// Unlock all clients
 	for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-		if ((*it)->client() != NULL) {
+		if ((*it)->client() != nullptr) {
 			(*it)->client()->lockScreen(lock);
 			(*it)->client()->removeAttention();
 		}
 
 	// Stop server (Clients get stopped on ACK)
-	if (getClientFromId(_streamingSource) != NULL)
+	if (getClientFromId(_streamingSource) != nullptr)
 		getClientFromId(_streamingSource)->stopVncServer();
 }
 
@@ -623,7 +626,7 @@ void MainWindow::onPlaceFrame(ConnectionFrame* connectionFrame)
 	const QPoint preferredPixels = connectionFrame->pos();
 	placeFrameInFreeSlot(connectionFrame, preferredPixels);
 
-	//resizeEvent(NULL);
+	//resizeEvent(nullptr);
 }
 
 /***************************************************************************//**
@@ -638,7 +641,7 @@ void MainWindow::onFrameClicked(ConnectionFrame* frame)
 
 	// If another frame has been selected, unselect it
 	// Set the ui selected and set a new reference
-	if (getSelectedFrame() != NULL) {
+	if (getSelectedFrame() != nullptr) {
 		getSelectedFrame()->setSelection(false);
 	}
 	frame->setSelection(true);
@@ -698,14 +701,14 @@ void MainWindow::startVncServerIfNecessary(int from)
 	Client* ns = getClientFromId(from);
 
 	// if there is a server running which is not "from" stop it.
-	if (os != NULL && _streamingSource != from)
+	if (os != nullptr && _streamingSource != from)
 		os->stopVncServer();
 
 	// Set new streaming source
 	_streamingSource = from;
 
 	// If streaming source is already active avoid a restart
-	if (ns != NULL) {
+	if (ns != nullptr) {
 		if (ns->isActiveVncServer()) {
 			this->onVncServerStateChange(ns);
 		} else { // Could not take shortcut, (re)start VNC server on source
@@ -737,11 +740,11 @@ void MainWindow::onReloadRoomCancel()
 void MainWindow::reloadCurrentRoom()
 {
 	/* delete old image */
-	if (_backgroundImage != NULL) {delete _backgroundImage; }
-	_backgroundImage = NULL;
+	if (_backgroundImage != nullptr) {delete _backgroundImage; }
+	_backgroundImage = nullptr;
 
 	const Room *room = serverApp->getCurrentRoom();
-	if (room != NULL) {
+	if (room != nullptr) {
 		/* set tiles */
 		_tilesX = room->gridSize.width();
 		_tilesY = room->gridSize.height();
@@ -756,7 +759,7 @@ void MainWindow::reloadCurrentRoom()
 			onPlaceFrame(cf);
 			if (computerId == room->tutorIP) {
 				qDebug() << "set computer with id " << computerId << " as tutor per configuration";
-				if (getTutorFrame() != NULL) {
+				if (getTutorFrame() != nullptr) {
 					getTutorFrame()->setTutor(false);
 				}
 				cf->setTutor(true);
@@ -785,12 +788,12 @@ void MainWindow::reloadCurrentRoom()
 	}
 
 	/* and force a resize event (this scales the image)  */
-	resizeEvent(NULL);
+	resizeEvent(nullptr);
 }
 
 void MainWindow::onReloadRoomOk()
 {
-	if (_reloadWindow->ui->roomList->currentItem() == NULL) {
+	if (_reloadWindow->ui->roomList->currentItem() == nullptr) {
 		QMessageBox::critical(this, "Warning", tr("No item selected, please select room!"), 0, 1);
 		return;
 	}
@@ -855,9 +858,9 @@ void MainWindow::onButtonTutorToAll()
 {
 	ui->action_Lock->setChecked(false);
 
-	if (getTutorFrame() == NULL)
+	if (getTutorFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorNdef);
-	else if (getTutorFrame()->client() == NULL)
+	else if (getTutorFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorOffline);
 	else if (_clientFrames.size() == 1)
 		QMessageBox::critical(this, tr("Projection"), sStrNoDestAv);
@@ -870,7 +873,7 @@ void MainWindow::onButtonTutorToAll()
 
 		// Set all clients as watchers of tutor. Except for the tutors desired source, which hase to be none
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-			if ((*it)->client() != NULL)
+			if ((*it)->client() != nullptr)
 				(*it)->client()->setDesiredProjectionSource((*it)->client() == getTutorFrame()->client() ? NO_SOURCE : getTutorFrame()->client()->id());
 
 		disableButtons();
@@ -887,21 +890,21 @@ void MainWindow::onButtonTutorToStudent()
 {
 	ui->action_Lock->setChecked(false);
 
-	if (getSelectedFrame() == NULL)
+	if (getSelectedFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrDestNdef);
-	else if (getTutorFrame() == NULL)
+	else if (getTutorFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorNdef);
 	else if (getSelectedFrame() == getTutorFrame())
 		QMessageBox::critical(this, tr("Projection"), sStrSourceDestSame);
-	else if (getSelectedFrame()->client() == NULL)
+	else if (getSelectedFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrDestOffline);
-	else if (getTutorFrame()->client() == NULL)
+	else if (getTutorFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorOffline);
 	else {
 		// If this is the first call in this mode clear the watchers
 		if (_mode != Mode::Multicast) {
 			for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-				if ((*it)->client() != NULL)
+				if ((*it)->client() != nullptr)
 					(*it)->client()->setDesiredProjectionSource(NO_SOURCE);
 		}
 
@@ -925,15 +928,15 @@ void MainWindow::onButtonStudentToTutor()
 {
 	ui->action_Lock->setChecked(false);
 
-	if (getSelectedFrame() == NULL)
+	if (getSelectedFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrSourceNdef);
-	else if (getTutorFrame() == NULL)
+	else if (getTutorFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorNdef);
 	else if (getTutorFrame() == getSelectedFrame())
 		QMessageBox::critical(this, tr("Projection"), sStrSourceDestSame);
-	else if (getSelectedFrame()->client() == NULL)
+	else if (getSelectedFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrSourceOffline);
-	else if (getTutorFrame()->client() == NULL)
+	else if (getTutorFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorOffline);
 	else {
 		// If this is not the first run in this mode and the current source is selected, stop the streaming.
@@ -946,7 +949,7 @@ void MainWindow::onButtonStudentToTutor()
 
 		// Unset all clients desired sources. Except the tutors desired source, this has to be the selecteds frame
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-			if ((*it)->client() != NULL)
+			if ((*it)->client() != nullptr)
 				(*it)->client()->setDesiredProjectionSource(getTutorFrame()->client()->id() == (*it)->client()->id() ? getSelectedFrame()->client()->id() : NO_SOURCE);
 
 		disableButtons();
@@ -963,15 +966,15 @@ void MainWindow::onButtonStudentToTutorExclusive()
 {
 	ui->action_Lock->setChecked(false);
 
-	if (getSelectedFrame() == NULL)
+	if (getSelectedFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrSourceNdef);
-	else if (getTutorFrame() == NULL)
+	else if (getTutorFrame() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorNdef);
 	else if (getTutorFrame() == getSelectedFrame())
 		QMessageBox::critical(this, tr("Projection"), sStrSourceDestSame);
-	else if (getSelectedFrame()->client() == NULL)
+	else if (getSelectedFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrSourceOffline);
-	else if (getTutorFrame()->client() == NULL)
+	else if (getTutorFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorOffline);
 	else {
 		Client *selectedClient = getSelectedFrame()->client();
@@ -986,7 +989,7 @@ void MainWindow::onButtonStudentToTutorExclusive()
 
 		// Unset all clients desired sources. Except the tutors desired source, this has to be the selecteds frame
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-			if ((*it)->client() != NULL)
+			if ((*it)->client() != nullptr)
 				(*it)->client()->setDesiredProjectionSource(tutorClient->id() == (*it)->client()->id() ? selectedClient->id() : NO_SOURCE);
 
 		disableButtons();
@@ -1022,14 +1025,14 @@ void MainWindow::onButtonLock(bool checked)
 void MainWindow::onButtonLockSingle()
 {
 	// If no frame is selected, warning.
-	if (getSelectedFrame() == NULL) {
+	if (getSelectedFrame() == nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("No client is selected."));
 		return;
 	}
 	Client *client = getSelectedFrame()->client();
 
 	// If frame of inactive client has been selected unselect it
-	if (client == NULL) {
+	if (client == nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("The selected client is not connected."));
 		return;
 	} else { // If selected client is locked, first unlock
@@ -1038,7 +1041,7 @@ void MainWindow::onButtonLockSingle()
 		if (!newState) {
 			// If no more clients are locked, reset button
 			for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
-				if ((*it)->client() == NULL)
+				if ((*it)->client() == nullptr)
 					continue;
 				if ((*it)->client()->isLocked())
 					return;
@@ -1063,13 +1066,13 @@ void MainWindow::onButtonExit()
 void MainWindow::onButtonSetAsTutor()
 {
 	// If no frame is selected, warning.
-	if (getSelectedFrame() == NULL) {
+	if (getSelectedFrame() == nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("No client is selected."));
 		return;
 	}
 
 	// If frame of inactive client has been selected unselect it
-	if (getSelectedFrame()->client() == NULL) {
+	if (getSelectedFrame()->client() == nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("The selected client is not connected."));
 		return;
 	} else { // If selected client is locked, first unlock
@@ -1081,7 +1084,7 @@ void MainWindow::onButtonSetAsTutor()
 		return;
 
 	// Else unset the old and set the new tutor
-	if (getTutorFrame() != NULL) {
+	if (getTutorFrame() != nullptr) {
 		getTutorFrame()->setTutor(false);
 	}
 	getSelectedFrame()->setTutor(true);
@@ -1122,7 +1125,7 @@ void MainWindow::onClientAuthenticating(Client* client, ClientLogin* request)
 		inuse = false;
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
 			Client *c = (**it).client();
-			if (c == NULL)
+			if (c == nullptr)
 				continue;
 			if (!c->isAuthed())
 				continue;
@@ -1158,8 +1161,8 @@ void MainWindow::onClientAuthenticated(Client* client)
 	disconnect(client, SIGNAL(authenticated(Client*)), this, SLOT(onClientAuthenticated(Client*)));
 	connect(client, SIGNAL(vncServerStateChange(Client*)), this, SLOT(onVncServerStateChange(Client*)));
 	connect(client, SIGNAL(vncClientStateChange(Client*)), this, SLOT(onVncClientStateChange(Client*)));
-	ConnectionFrame *existing = NULL;
-	ConnectionFrame *cf = NULL;
+	ConnectionFrame *existing = nullptr;
+	ConnectionFrame *cf = nullptr;
 	for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
 		if ((*it)->computerId() == client->ip()) {
 			existing = *it;
@@ -1167,7 +1170,7 @@ void MainWindow::onClientAuthenticated(Client* client)
 	}
 
 	// Clients ip already exists, but was not active.
-	if (existing != NULL) {
+	if (existing != nullptr) {
 		cf = existing;
 	} else {
 		cf = createFrame();
@@ -1193,7 +1196,7 @@ void MainWindow::onVncServerStateChange(Client* client)
 	if (client->isActiveVncServer()) {
 		// apply the desired projection sources
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-			if ( (*it)->client() != NULL) { // Ignore offline clients
+			if ( (*it)->client() != nullptr) { // Ignore offline clients
 				if ( (*it)->client()->desiredProjectionSource() == client->id() )
 					(*it)->client()->startVncClient(client);
 				else
@@ -1206,7 +1209,7 @@ void MainWindow::onVncServerStateChange(Client* client)
 	} else {
 		// VNC server stopped on some client or failed to start - reset local pending projection information
 		for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it) {
-			if ((*it)->client() != NULL) {
+			if ((*it)->client() != nullptr) {
 				if ((*it)->client()->desiredProjectionSource() == client->id()) {
 					(*it)->client()->setDesiredProjectionSource(NO_SOURCE);
 					(*it)->client()->stopVncClient();
@@ -1234,7 +1237,7 @@ void MainWindow::onVncServerStateChange(Client* client)
  */
 void MainWindow::onVncClientStateChange(Client* client)
 {
-	if (client != NULL) {
+	if (client != nullptr) {
 		// VNC Client stopped -> remove from watchers
 		if (!client->isActiveVncClient()) {
 			// Only unset a desired Projection source if it has not changed meanwhile
@@ -1252,7 +1255,7 @@ void MainWindow::onVncClientStateChange(Client* client)
 			 */
 			bool serverHasWatchers = false;
 			for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-				if ((*it)->client() != NULL)
+				if ((*it)->client() != nullptr)
 					if ((*it)->client()->desiredProjectionSource() == client->projectionSource()) {
 						serverHasWatchers = true;
 						break;
@@ -1260,7 +1263,7 @@ void MainWindow::onVncClientStateChange(Client* client)
 
 			if ( !serverHasWatchers ) {
 				Client* c = getClientFromId(client->projectionSource());
-				if (c != NULL)
+				if (c != nullptr)
 					c->stopVncServer();
 			}
 		}
@@ -1296,11 +1299,11 @@ void MainWindow::onDeleteClient()
 {
 	// If no frame is selected, warning.
 	ConnectionFrame* frame = getSelectedFrame();
-	if (frame == NULL) {
+	if (frame == nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("No client is selected."));
 		return;
 	}
-	if (frame->client() != NULL) {
+	if (frame->client() != nullptr) {
 		QMessageBox::critical(this, tr("Selection"), tr("This client is still connected."));
 		return;
 	}
diff --git a/src/server/mainwindow/mainwindow.h b/src/server/mainwindow/mainwindow.h
index 4e99747..43804a7 100644
--- a/src/server/mainwindow/mainwindow.h
+++ b/src/server/mainwindow/mainwindow.h
@@ -44,8 +44,8 @@ private:
 	Qt::ToolBarArea   _tbArea;
 	int  _tilesX;
 	int  _tilesY;
-	QImage* _backgroundImage = NULL;
-	QLabel* _examModeLabel = NULL;
+	QImage* _backgroundImage = nullptr;
+	QLabel* _examModeLabel = nullptr;
 
 
 	/* virtual columns to preserve the aspect ratio of the loaded room */
@@ -79,7 +79,7 @@ private:
 
 	QPoint closestFreeSlot(QPoint preferredPixels, ConnectionFrame* toIgnore);
 	void placeFrameInFreeSlot(ConnectionFrame* frame, QPoint preferred = QPoint(-1, -1));
-	ConnectionFrame* createFrame(const QString &computerId = QString(), const QPoint *gridPosition = NULL, bool fromRoomplan = false);
+	ConnectionFrame* createFrame(const QString &computerId = QString(), const QPoint *gridPosition = nullptr, bool fromRoomplan = false);
 	void savePosition(ConnectionFrame *cf);
 	void startVncServerIfNecessary(int from);
 	void tellClientCurrentSituation(Client* client);
diff --git a/src/server/net/certmanager.cpp b/src/server/net/certmanager.cpp
index a7df6cc..a503088 100644
--- a/src/server/net/certmanager.cpp
+++ b/src/server/net/certmanager.cpp
@@ -66,7 +66,7 @@ bool getPrivateKeyAndCert(const QString &name, QSslKey &key, QSslCertificate &ce
 
 void fatal()
 {
-	QMessageBox::critical(NULL, QCoreApplication::trUtf8("OpenSSL error", "CertManager"),
+	QMessageBox::critical(nullptr, QCoreApplication::trUtf8("OpenSSL error", "CertManager"),
 			QCoreApplication::trUtf8("Could not generate certificates for secure connections.\n"
 			"PVS will not work.\n\n"
 			"Press OK to quit.", "CertManager"));
diff --git a/src/server/net/client.cpp b/src/server/net/client.cpp
index c11cb63..9e96dec 100644
--- a/src/server/net/client.cpp
+++ b/src/server/net/client.cpp
@@ -19,7 +19,7 @@ int Client::_clientIdCounter = 0;
 /******************************************************************************/
 Client::Client(QTcpSocket* socket) : _socket(socket)
 {
-	assert(socket != NULL);
+	assert(socket != nullptr);
 	_authed = 0;
 	_projectionSource = 0;
 	_desiredSource = 0;
diff --git a/src/server/net/listenserver.cpp b/src/server/net/listenserver.cpp
index 0a585c7..628b62d 100644
--- a/src/server/net/listenserver.cpp
+++ b/src/server/net/listenserver.cpp
@@ -31,7 +31,7 @@ ListenServer::~ListenServer()
 void ListenServer::newClientConnection()
 {
 	QTcpSocket* sock;
-	while ((sock = _server.nextPendingConnection()) != NULL) {
+	while ((sock = _server.nextPendingConnection()) != nullptr) {
 		Client* client = new Client(sock); // TODO: what happens with disconnected clients
 		emit newClient(client);
 	}
diff --git a/src/server/net/sslserver.cpp b/src/server/net/sslserver.cpp
index 0e0639e..c11f0ae 100644
--- a/src/server/net/sslserver.cpp
+++ b/src/server/net/sslserver.cpp
@@ -20,7 +20,7 @@
 #include "certmanager.h"
 #include <unistd.h>
 
-SslServer::SslServer() : QTcpServer(NULL)
+SslServer::SslServer() : QTcpServer(nullptr)
 {
 	_tmr = startTimer(5123);
 }
@@ -43,10 +43,10 @@ void SslServer::incomingConnection(qintptr socketDescriptor)
 		if (++certFails > 5) {
 			CertManager::fatal();
 		}
-		::close(socketDescriptor);
+		::close((int)socketDescriptor);
 		return;
 	}
-	QSslSocket *serverSocket = new QSslSocket(NULL);
+	QSslSocket *serverSocket = new QSslSocket(nullptr);
 	connect(serverSocket, SIGNAL(sslErrors(const QList<QSslError> &)), this, SLOT(sslErrors(const QList<QSslError> &)));
 	connect(serverSocket, SIGNAL(disconnected()), this, SLOT(sock_closed()));
 	connect(serverSocket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(sock_error(QAbstractSocket::SocketError)));
@@ -70,7 +70,7 @@ void SslServer::incomingConnection(qintptr socketDescriptor)
 	}
 }
 
-void SslServer::sslErrors(const QList<QSslError> &errors)
+void SslServer::sslErrors(const QList<QSslError>& /* errors */)
 {
 	/*
 	qDebug() << "Client caused sslErrors before connection:";
@@ -134,6 +134,6 @@ QTcpSocket* SslServer::nextPendingConnection()
 			return sock;
 		}
 	}
-	return NULL;
+	return nullptr;
 }
 
diff --git a/src/server/serverapp/serverapp.cpp b/src/server/serverapp/serverapp.cpp
index 7ee06e0..f680f89 100644
--- a/src/server/serverapp/serverapp.cpp
+++ b/src/server/serverapp/serverapp.cpp
@@ -7,7 +7,7 @@ static QSize minimalGridSize(const QMap<QString, QPoint>& clientPositions, QSize
 
 ServerApp::ServerApp(int& argc, char** argv)
 	: QApplication(argc, argv),
-		_mainWindow(NULL),
+		_mainWindow(nullptr),
 		_managerOnly(false),
 		_isExam(false)
 {
@@ -132,8 +132,8 @@ const Room* ServerApp::getCurrentRoom()
 	if (_rooms.contains(_currentRoom)) {
 		return _rooms[_currentRoom];
 	} else {
-		static Room* defaultRoom = NULL;
-		if (defaultRoom == NULL) {
+		static Room* defaultRoom = nullptr;
+		if (defaultRoom == nullptr) {
 			defaultRoom = new Room(QMap<QString,
 			                       QPoint>(), QSize(8, 6), QSize(1, 1), "", "");
 		}
diff --git a/src/server/util/platform/screensaver.cpp b/src/server/util/platform/screensaver.cpp
index efffba9..cdd6ee1 100644
--- a/src/server/util/platform/screensaver.cpp
+++ b/src/server/util/platform/screensaver.cpp
@@ -14,17 +14,17 @@
 
 namespace {
 
-	Display *display = NULL;
+	Display *display = nullptr;
 	bool extensionSupported = false;
 	bool dpmsSupported = false;
 
 	bool init()
 	{
-		if (display != NULL) {
+		if (display != nullptr) {
 			return true;
 		}
 		display = QX11Info::display();
-		if (display == NULL) {
+		if (display == nullptr) {
 			return false;
 		}
 #ifdef X11_Xscreensaver_FOUND
diff --git a/src/shared/networkmessage.cpp b/src/shared/networkmessage.cpp
index 64e02e7..0bdf3c5 100644
--- a/src/shared/networkmessage.cpp
+++ b/src/shared/networkmessage.cpp
@@ -22,32 +22,32 @@
     ((((x) & 0xFF00u) >> 8) | \
      (((x) & 0x00FFu) << 8))
 
-static quint16 _htons(quint16 x)
+static quint16 _htons(const quint16 x)
 {
 	if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
 		return x;
 	return (quint16)BYTE_SWAP2(x);
 }
 
-static quint16 _ntohs(quint16 x)
+static quint32 _htonl(const quint32 x)
 {
 	if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
 		return x;
-	return (quint16)BYTE_SWAP2(x);
+	return (quint32)BYTE_SWAP4(x);
 }
 
-static quint32 _htonl(quint32 x)
+static quint16 _ntohs(const char *in)
 {
-	if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
-		return x;
-	return (quint32)BYTE_SWAP4(x);
+	return quint16(quint8(in[0]) << 8
+			| quint8(in[1]));
 }
 
-static quint32 _ntohl(quint32 x)
+static quint32 _ntohl(const char *in)
 {
-	if (QSysInfo::ByteOrder == QSysInfo::BigEndian)
-		return x;
-	return (quint32)BYTE_SWAP4(x);
+	return quint32(quint8(in[0])) << 24
+			| quint32(quint8(in[1])) << 16
+			| quint32(quint8(in[2])) << 8
+			| quint32(quint8(in[3]));
 }
 
 /*
@@ -56,7 +56,7 @@ static quint32 _ntohl(quint32 x)
  */
 
 NetworkMessage::NetworkMessage() :
-	_buffer(NULL), _bufferSize(0), _bufferPos(0), _lastBufferSize(0), _mode(0)
+	_buffer(nullptr), _bufferSize(0), _bufferPos(0), _lastBufferSize(0), _mode(0)
 {
 	//
 }
@@ -69,7 +69,7 @@ NetworkMessage::~NetworkMessage()
 
 inline void NetworkMessage::allocBuffer()
 {
-	if (_lastBufferSize < _bufferSize || _buffer == NULL) {
+	if (_lastBufferSize < _bufferSize || _buffer == nullptr) {
 		if (_buffer)
 			delete[] _buffer;
 		_lastBufferSize = _bufferSize;
@@ -150,7 +150,7 @@ bool NetworkMessage::parseHeader(char *header)
 		return false;
 	}
 	_bufferPos = 0;
-	_bufferSize = _ntohl(*(quint32*)(header + 4));
+	_bufferSize = _ntohl(header + 4);
 	if (_bufferSize > MAX_MSG_LEN) {
 		qDebug("Disconnecting Client: MAX_MSG_LEN exceeded.");
 		return false;
@@ -166,9 +166,9 @@ bool NetworkMessage::parseMessage(char *buffer)
 {
 	char *ptr = buffer;
 	while (_bufferSize - (ptr - buffer) >= 4) {
-		const quint16 keyLen = _ntohs(*(quint16*)(ptr));
+		const quint16 keyLen = _ntohs(ptr);
 		ptr += 2;
-		const quint16 valLen = _ntohs(*(quint16*)(ptr));
+		const quint16 valLen = _ntohs(ptr);
 		ptr += 2;
 		if (_bufferSize - (ptr - buffer) < keyLen + valLen) {
 			qDebug() << "Warning: Error parsing message. key(" << keyLen << ")+value(" << valLen
@@ -237,7 +237,7 @@ void NetworkMessage::serializeMessage()
 {
 	QByteArray buf;
 	//qDebug() << "Default size: " << buf.capacity();
-	buf.reserve(_lastBufferSize > 0 ? _lastBufferSize : 200);
+	buf.reserve(_lastBufferSize > 0 ? int(_lastBufferSize) : 200);
 	for (QHash<QByteArray, QByteArray>::const_iterator it = _fields.begin(); it != _fields.end(); ++it) {
 		const QByteArray &ba = it.key();
 		const QByteArray &val = it.value();
@@ -249,9 +249,9 @@ void NetworkMessage::serializeMessage()
 		buf.append(ba);
 		buf.append(val);
 	}
-	_bufferSize = buf.length() + HEADER_LEN;
+	_bufferSize = quint32(buf.length() + HEADER_LEN);
 	allocBuffer();
-	memcpy(_buffer + HEADER_LEN, buf.data(), buf.size());
+	memcpy(_buffer + HEADER_LEN, buf.data(), size_t(buf.size()));
 	_buffer[0] = 'P';
 	_buffer[1] = 'V';
 	_buffer[2] = 'S';
diff --git a/src/shared/util.h b/src/shared/util.h
index c2e5145..e9530a8 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -10,6 +10,6 @@
 
 #include <QByteArray>
 
-QByteArray genSha1(const QByteArray* a, const QByteArray* b = NULL, const QByteArray* c = NULL, const QByteArray* d = NULL, const QByteArray* e = NULL);
+QByteArray genSha1(const QByteArray* a, const QByteArray* b = nullptr, const QByteArray* c = nullptr, const QByteArray* d = nullptr, const QByteArray* e = nullptr);
 
 #endif /* UTIL_H_ */