Now the application does not start if it does not find ip, which starts with "fc" (ie, before starting the messenger, you need to run the cjdns daemon)

src/kernel/network.cpp

@@ -37,11 +37,19 @@ void Network::processTheDatagram()
 QString Network::localIPv6()
 {
     QHostAddress address;
+    QString addressString;
     foreach (address, QNetworkInterface::allAddresses()) {
         if (address.protocol() == QAbstractSocket::IPv6Protocol && address != QHostAddress(QHostAddress::LocalHostIPv6) && (address.toString()).contains("fc"))
+        {
+            addressString = address.toString();
             break;
         }
-    return(address.toString());
+        else
+        {
+            addressString = "null";
+        }
+    }
+    return(addressString);
 }
 
 Network::~Network()

src/main.cpp

@@ -5,6 +5,10 @@ int main(int argc, char *argv[])
 {
     QApplication a(argc, argv);
     MainWindow w;
+    if(w.doQuit())
+    {
+        return -1;
+    }
     w.show();
 
     return a.exec();

src/mainwindow.cpp

@@ -5,8 +5,13 @@ MainWindow::MainWindow(QWidget *parent) :
     QMainWindow(parent),
     ui(new Ui::MainWindow)
 {
-    ui->setupUi(this);
     network = new Network(false);
+    if(*network->myIPv6 == "null")
+    {
+        QMessageBox::critical(parent, tr("Cjdns is not running!"), tr("Cjdns is not running, so the application will be closed."));
+        mDoQuit = true;
+    }
+    ui->setupUi(this);
     handler = new Handler();
     timer = new QTimer();
     connect(timer, SIGNAL(timeout()), this, SLOT(slotTimerAlarm()));

src/mainwindow.h

@@ -25,6 +25,7 @@ class MainWindow : public QMainWindow
         QVector<ChatWindow*> pChatWindows;
         void setButtonToWaiting();
         void setButtonToConnect();
+        inline bool doQuit() const { return mDoQuit; }
     public slots:
         void peerReceiverAvailable();
     private slots:
@@ -42,4 +43,5 @@ class MainWindow : public QMainWindow
         Network *network;
         Handler *handler;
         bool receive = false;
+        bool mDoQuit = false;
 };