Use QT to read from socket - c++

Question

I want to use IPC in order to exchange messages between two separate applications. The first one is a BASH script which is fired when a specific udev rule is activated (in Ubuntu Linux), and the other one is a simple Qt 5.7 console application, which acts as a server.
I already have the Qt server working and printing a message when it accepts a connection to the specified socket. What I'm trying to achieve now, is to make the server do something not when it accepts a connection, but when it receives a certain "message". Any ideas on how to do it?
Below is my code:
server.cpp
#include "server.h"
Server::Server() : QThread()
{
m_server = new QLocalServer(this);
m_server->listen("somesocket.sock");
connect(m_server, &QLocalServer::newConnection, this, &Server::testFunction);
}
Server::~Server()
{
m_server->removeServer("somesocket.sock");
}
void Server::run()
{
}
void Server::testFunction(){
qDebug() << "Sth happened!";
return;
}
server.h
#ifndef SERVER_H
#define SERVER_H
#include <QThread>
#include <QObject>
#include <QDebug>
#include <QLocalServer>
class Server : public QThread
{
public:
Server();
~Server();
void run();
void testFunction();
private:
QLocalServer *m_server;
signals:
void connectionEstablished(bool);
};
#endif // SERVER_H

Answer 1

You could connect to readyRead signal, and then check received message, like in this example:
connect( this, SIGNAL(readyRead()), SLOT(readClient()) );
void readClient()
{
QTextStream ts( this );
int line = 0;
while ( canReadLine() ) {
QString str = ts.readLine();
if(str == "someSpecialMessage")
{
//...
}
line++;
}
}
for more informations about this signal, see documentation: http://doc.qt.io/qt-5/qiodevice.html#readyRead
This is also an example of client and server applications in Qt, using QSocket and QServerSocket: https://doc.qt.io/archives/3.3/clientserver-example.html