problem with QLocalSocket sending continues data to QLocalServer - qt

I'm trying to send some data from QLocalSocket to QLocalSever in a loop. Sever only gets the first data and not receiving subsequent data, but if I introduce 1 mec delay between each call from the client then the server starts to receive everything. Please check out the below Client & Server code.
client.cpp
#include "client.h"
#include "QDataStream"
#include <QTest>
TestClient::TestClient() : m_socket{new QLocalSocket(this)}{
m_socket->connectToServer("TestServer");
if (m_socket->waitForConnected(1000)) {
qDebug("socket Connected!");
}
connect(m_socket, &QLocalSocket::readyRead, this, &TestClient::onNewData);
}
void TestClient::onNewData() {
qCritical() << "data received from server";
}
void TestClient::sendDataToServer() {
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_10);
QString testString = "test data";
out << quint32(testString.size());
out << testString;
m_socket->write(block);
m_socket->flush();
}
void TestClient::startClient() {
for(int i = 0; i < 5; i++) {
//QTest::qWait(1); //works if I uncomment this line
sendDataToServer();
}
}
server.cpp
#include "server.h"
TestServer::TestServer() : m_server{new QLocalServer(this)} {
QLocalServer::removeServer("TestServer");
if (!m_server->listen("TestServer")) {
qCritical() << "couldn't connect to server";
}
connect(m_server, &QLocalServer::newConnection, this, &TestServer::onNewConnection);
}
void TestServer::onNewConnection() {
m_socket = m_server->nextPendingConnection();
connect(m_socket, &QLocalSocket::readyRead, this,
&TestServer::onNewData);
connect(m_socket, &QLocalSocket::disconnected, m_socket,
&QLocalSocket::deleteLater);
}
void TestServer::onNewData() {
QLocalSocket* client = qobject_cast<QLocalSocket*>(sender());
client->readAll();
qCritical() << "data read by server";
}
from the qt doc, it's stated that
readyRead() is not emitted recursively; if you reenter the event loop
or call waitForReadyRead() inside a slot connected to the readyRead()
signal, the signal will not be reemitted (although waitForReadyRead()
may still return true).
so is this my problem? adding timer is the only solution here?
You can compile this test project -> http://www.filedropper.com/testsocket

Related

QTcpSocket data arrives late

I am using QTCPSockets to talk to a program I've written in Qt for Raspberry Pi. The same software runs on my Mac (or Windows, whatever). The Pi is running a QTCPServer.
I send JSON data to it and most of the time this goes ok.
But sometimes, the Pi is not responding, the data does not seem to arrive. But then, when I send some more data, that data is not being handled, but the previous Json message is! And this stays like this. All the messages are now off by 1. Sending a new messages, triggers the previous one.
It feels a bit connected to this bugreport: https://bugreports.qt.io/browse/QTBUG-58262
But I'm not sure if it is the same.
I've tried waitForBytesWritten and flush and it seemed to work at first, but later I saw the issue again.
I expect that the TCP buffer on the Pi is not being flushed, but I do now know how to make sure that all data is handled right away.
As asked, here is some sourcecode:
This is the client software:
Client::Client() : tcpSocket(new QTcpSocket(this)), in(tcpSocket)
{
connect(tcpSocket, &QIODevice::readyRead, this, &Client::readData);
connect(tcpSocket, &QTcpSocket::connected, this, &Client::connected);
connect(tcpSocket, &QTcpSocket::stateChanged, this, &Client::onConnectionStateChanged);
void (QAbstractSocket:: *sig)(QAbstractSocket::SocketError) = &QAbstractSocket::error;
connect(tcpSocket, sig, this, &Client::error);
}
void Client::connectTo(QString ip, int port) {
this->ip = ip;
this->port = port;
tcpSocket->connectToHost(ip, port);
}
void Client::reconnect() {
connectTo(ip, port);
}
void Client::disconnect()
{
tcpSocket->disconnectFromHost();
}
void Client::connected()
{
qDebug() << TAG << "connected!";
}
void Client::error(QAbstractSocket::SocketError error)
{
qDebug() << TAG << error;
}
void Client::sendData(const QString& data)
{
bool connected = (tcpSocket->state() == QTcpSocket::ConnectedState);
if (!connected) {
qDebug() << TAG << "NOT CONNECTED!";
return;
}
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_7);
out << data;
tcpSocket->write(block);
tcpSocket->flush();
}
void Client::sendData(const QByteArray& data) {
bool connected = (tcpSocket->state() == QTcpSocket::ConnectedState);
if (!connected) {
qDebug() << TAG << " is NOT connected!";
return;
}
tcpSocket->write(data);
tcpSocket->flush();
}
void Client::readData()
{
in.startTransaction();
QString data;
in >> data;
if (!in.commitTransaction())
{
return;
}
emit dataReceived(data);
}
void Client::onConnectionStateChanged(QAbstractSocket::SocketState state)
{
switch (state) {
case QAbstractSocket::UnconnectedState:
connectionState = "Not connected";
break;
case QAbstractSocket::ConnectingState:
connectionState = "connecting";
break;
case QAbstractSocket::ConnectedState:
connectionState = "connected";
break;
default:
connectionState = QString::number(state);
}
qDebug() << TAG << " connecting state: " << state;
emit connectionStateChanged(connectionState);
if (state == QAbstractSocket::UnconnectedState) {
QTimer::singleShot(1000, this, &Client::reconnect);
}
}
and here the server part:
Server::Server()
{
tcpServer = new QTcpServer(this);
connect(tcpServer, &QTcpServer::newConnection, this, &Server::handleConnection);
tcpServer->listen(QHostAddress::Any, 59723);
QString ipAddress;
QList<QHostAddress> ipAddressesList = QNetworkInterface::allAddresses();
// use the first non-localhost IPv4 address
for (int i = 0; i < ipAddressesList.size(); ++i) {
if (ipAddressesList.at(i) != QHostAddress::LocalHost &&
ipAddressesList.at(i).toIPv4Address()) {
ipAddress = ipAddressesList.at(i).toString();
break;
}
}
// if we did not find one, use IPv4 localhost
if (ipAddress.isEmpty())
ipAddress = QHostAddress(QHostAddress::LocalHost).toString();
qDebug() << TAG << "ip " << ipAddress << " serverport: " << tcpServer->serverPort();
}
void Server::clientDisconnected()
{
QTcpSocket *client = qobject_cast<QTcpSocket *>(QObject::sender());
int idx = clients.indexOf(client);
if (idx != -1) {
clients.removeAt(idx);
}
qDebug() << TAG << "client disconnected: " << client;
client->deleteLater();
}
void Server::handleConnection()
{
qDebug() << TAG << "incoming!";
QTcpSocket* clientConnection = tcpServer->nextPendingConnection();
connect(clientConnection, &QAbstractSocket::disconnected, this, &Server::clientDisconnected);
connect(clientConnection, &QIODevice::readyRead, this, &Server::readData);
clients.append(clientConnection);
broadcastUpdate(Assets().toJson());
}
void Server::readData()
{
QTcpSocket *client = qobject_cast<QTcpSocket *>(QObject::sender());
QDataStream in(client);
in.startTransaction();
QString data;
in >> data;
if (!in.commitTransaction())
{
return;
}
...
// here I do something with the data. I removed that code as it is
// not necessary for this issue
...
broadcastUpdate(data);
}
void Server::broadcastUpdate(const QString& data)
{
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_5_7);
out << data;
foreach(QTcpSocket* client, clients) {
bool connected = (client->state() == QTcpSocket::ConnectedState);
if (!connected) {
qDebug() << TAG << client << " is NOT connected!";
continue;
}
client->write(block);
}
}
I think the problem is with your void Client::readData(): you have to write it in such a way that you read all available data from the socket inside it (usually it's written with while (socket->bytesAvailable() > 0) { ... } loop).
It is because of the way the readyRead() signal is emitted: the remote peer may send any non-zero number of packets to you, and your socket will emit any non-zero number of readyRead() signals. In your case, it seems that the server sends two messages but they only cause one readyRead() signal to be emitted on the client.

read and write to qtcpsocket using qdatastream

There are various methods of reading and writing from a QTcpSocket using a QDatastream as seen here
The difference is, I will be sending more than "one packet" or blocks.
A basic implementation on the server (sending) side and client (recieving) is seen below - only the actual sending and receiving snippets are shown
More Info, What I tried:
When writing to a QTcpSocket, I attempted to use the QTcpSocket::canReadLine() however this fails straightup after the QTcpSocket::waitForReadReady() signal fires.
I then tried QDataStream::atEnd() in a while loop which causes a system crash :(
The code below shows my latest attempt of going through the QDataStream docs, and utilzing the commitTransaction where it states
If no full packet is received, this code restores the stream to the initial position, after which you need to wait for more data to arrive.
Under the heading Using Read Transactions. But ofcourse, this just reads one block that is sent, i.e the first block.
Question:
When writing to a QTcpSocket multiple times, and flushing the socket each time to send that data, how can I read this from a QTcpSocket as it is send, keep the original "send structure"?
The example below only reads the first block and ends. I would like to read the block containing "Response 2" and "Response 3".
Code Implementations:
//server.h
//...
QTcpSocket *clientSocket = nullptr;
QDataStream in;
//...
//server.cpp
//...
in.setDevice(clientSocket);
in.setVersion(QDataStream::Qt_4_0);
in.startTransaction();
QString nextFortune;
in >> nextFortune;
if (in.commitTransaction())
ui->lblOut->setText(nextFortune);
if (clientSocket != nullptr) {
if (!clientSocket->isValid()) {
qDebug() << "tcp socket invalid";
return;
}
if (!clientSocket->isOpen()) {
qDebug() << "tcp socket not open";
return;
}
QByteArray block;
QDataStream out(&block, QIODevice::WriteOnly);
out.setVersion(QDataStream::Qt_4_0);
out << QString(QString("Response:") + nextFortune);
if (!clientSocket->write(block)){
QMessageBox::information(this, tr("Server"),tr("Could not send message"));
}
clientSocket->flush();
// block.clear();
out << QString("Response number 2");
if (!clientSocket->write(block)){
QMessageBox::information(this, tr("Server"),tr("Could not send message"));
}
clientSocket->flush();
// block.clear();
out << QString("Response number 3 here, and this is the end!");
if (!clientSocket->write(block)){
QMessageBox::information(this, tr("Server"),tr("Could not send message"));
}
clientSocket->flush();
clientSocket->disconnectFromHost();
}
//...
And the client side
//client.h
//...
QTcpSocket *tcp_con = nullptr;
QDataStream in;
//...
//client.cpp
//...
if(!tcp_con->waitForReadyRead()){
qDebug(log_lib_netman_err) << "tcp con timeout for reading";
tcp_con->disconnectFromHost();
return ReturnObject(ReturnCode::SocketError, QString());
}
in.setDevice(tcp_con);
in.setVersion(QDataStream::Qt_4_0);
in.startTransaction();
QList<QString> data_rcv = QList<QString>();
QString s;
// while (tcp_con->canReadLine()) {
// in >> s;
// data_rcv.push_back(s);
// }
// while (!in.read) {
in >> s;
data_rcv.push_back(s);
// }
while (!in.commitTransaction()){
qDebug(log_lib_netman_info) << "waiting for more data";
in >> s;
data_rcv.push_back(s);
// qDebug(log_lib_netman_err) << "Unable to send data to server";
// tcp_con->disconnectFromHost();
// return ReturnObject(ReturnCode::FailedReceiving, QString());
}
// if (s.isEmpty()) {
// qDebug(log_lib_netman_err) << "Empty response recieved";
// tcp_con->disconnectFromHost();
// return ReturnObject(ReturnCode::NoDataRecieved, QString());
// }
tcp_con->disconnectFromHost();
return ReturnObject(ReturnCode::ReceivedSuccess, data_rcv);
Help would be greatly appreciated!

Qt , QMutex: destroying locked mutex then app crash

I make an http operation(get,post etc...) by using QNetworkAccessManager. I run a few "get" operation in paralel. For this , I use QtConcurrent::run(this,&RestWebservice::GetHTTPData) to make multi HTTP operations.
My problem is When I close the app before HTTP operation does not complete , App is crashed.Application Output write this line QMutex: destroying locked mutex then write The program has unexpectedly finished.
I guest problem occurs in this line
void RestWebservice::get()
{
// mutex.lock();
m_networkManager.get(m_networkrequest);
// mutex.unlock();
}
But I am not sure because QtCreater Debugger is not good like VS.By the way , GetHTTPData is in different class.
MY CODE for start network Operation:(MobileOperation.cpp).For exapmle getUserAccount metod start a http operation.
void MobileOperations::getWorkOrderListT(int ekipId) {
MyGlobal::Metods metod=MyGlobal::EkipIsEmriListesi;
QString parameters="{EkipId}";
QMap<QString,QVariant> paramlist;
paramlist["EkipId"]=ekipId;
GetHTTPData(metod,parameters,paramlist);
if(m_workorder.IsSuccess==true)
{
// emit successupdatewo();
if(m_workorder.workorders.count()>0)
{
InsertWo(json.workorder->workorders);
emit processstop("İş Emri Listesi Güncellendi");
// QThread::sleep(2);
}
else
{
emit processstop(json.workorder->ReturnMessage);
}
emit successworkstart();
}
else
{
emit processstop("Bağlantı Başarısız Oldu");
}
}
void MobileOperations::getUserAccount(QString kullaniciAdi, QString sifre,bool isremember)
{
json.user=m_user;
QtConcurrent::run(this,&MobileOperations::getUserAccountT,kullaniciAdi,sifre,isremember);
// getUserAccountT(kullaniciAdi,sifre,isremember);
processstart("Baglaniyor");
}
void MobileOperations::GetHTTPData(MyGlobal::Metods MetodName, QString Parameters, QMap<QString, QVariant> paramlist)
{
try
{
parameter=new HttpRequest();
parameter->url=m_url;
parameter->metodname=MetodName;
parameter->resource=m_path;
parameter->appid=m_appid;
parameter->apppass=m_apppass;
parameter->parametersname=Parameters;
parameter->params=paramlist;
rest= new RestWebservice(parameter->GenerateHTTPQuery(),MetodName);
// json=new JSonParser();
// loop=new QEventLoop();
loop=new QEventLoop();
QObject::connect(rest,SIGNAL(sendhttpdata(QByteArray,MyGlobal::Metods)),&json,SLOT(onGetData(QByteArray,MyGlobal::Metods)));
QObject::connect(&json,SIGNAL(serilazitionCompleted()),loop,SLOT(quit()));
rest->get();
loop->exec();
}
catch(std::string &exp)
{
qDebug()<<"Sonlandırıldı";
}
}
MY CODE of classes For HTTP operatins :
#include "restwebservice.h"
#include <QJsonDocument>
#include<QJsonArray>
#include <QJsonObject>
#include<QJsonValue>
#include<QList>
#include <QThread>
RestWebservice::RestWebservice(QNetworkRequest request,
MyGlobal::Metods metod,
QObject* parent):QObject(parent),m_networkrequest(request),m_metodname(metod)
{
connect(&m_networkManager, SIGNAL(finished(QNetworkReply*)),this, SLOT(onResult(QNetworkReply*)));
// connect(&m_networkManager,SIGNAL())
}
void RestWebservice::get()
{
// mutex.lock();
m_networkManager.get(m_networkrequest);
// mutex.unlock();
}
void RestWebservice::post(QString request)
{
QByteArray requestA= request.toUtf8();
m_networkManager.post(m_networkrequest,requestA);
}
void RestWebservice::onResult(QNetworkReply* reply)
{
try
{
if (reply->error() != QNetworkReply::NoError)
{
qDebug()<<reply->error()<<":"<<reply->errorString();
MyGlobal::NetworkStatus=reply->errorString();
emit sendhttpdata(m_data,m_metodname);
return;
// throw(reply->errorString().toStdString());
}
QByteArray data = reply->readAll();
reply->deleteLater();
m_data=data;
MyGlobal::NetworkStatus="Tablolar Yüklendi";
emit sendhttpdata(m_data,m_metodname);
}
catch(std::string exp)
{
qDebug()<<"Exception:"<<QString::fromStdString(exp);
}
catch(std::exception &exp)
{
qDebug()<<"Exception:"<<QString::fromStdString(exp.what());
}
}
void RestWebservice::onError()
{
qDebug()<<"Hata VAR";
}
HttpRequest::HttpRequest(QObject *parent) :
QObject(parent)
{
}
QNetworkRequest HttpRequest::GenerateHTTPQuery()
{
// QString path="";
QString path=QString("/%1/%2/%3/%4/%5").arg(resource).arg(MyGlobal::getMetodName(metodname)).arg(appid).arg(apppass).arg(parametersname);
foreach (QString param, params.keys()) {
path.replace("{"+param+"}",params[param].toString());
}
QUrl m_url(url);
m_url.setPath(path);
m_request.setUrl(m_url);
m_request.setRawHeader("Content-Type","application/json;charset=utf-8");
// m_request.setRawHeader("SOAPAction","http://tempuri.org/IMobileClient/UserAuth");
qDebug()<<m_url.url();
return m_request;
}
QNetworkRequest HttpRequest::GenerateHTTPQueryPost()
{
// QString path="";
QString path=QString("/%1/%2").arg(resource).arg(MyGlobal::getMetodName(metodname));
QUrl m_url(url);
m_url.setPath(path);
m_request.setUrl(m_url);
m_request.setRawHeader("Content-Type","application/json;charset=utf-8");
// m_request.setRawHeader("SOAPAction","http://tempuri.org/IMobileClient/UserAuth");
qDebug()<<m_url.url();
return m_request;
}
Is you mutex a member of your class. In that case the mutex is destructed before it is unlocked (as I presume the containing class goes out of scope), which causes the message you see. The destructor of the mutex is called when the class is destructed, while the lock is held. This is a problem. Typically you will have to find a way to not block indefinitely during your network request.

Ssl Server using QSslSocket in Qt

I have implemented a ssl server using QSslSocket and run it correctly. But I have some problem with it that I couldn't solve them immediately.
I thought that just connecting readyRead() signal to a slot for reading buffer is sufficient to do that but I have recognized that the readyRead() does not emit at all in this situation and I must also use waitForReadyRead() function in my code. But the problem is using this function cause blocking read the buffer. Actually I want to know how I can read buffer when data has arrived without blocking?
Bellow is my implemented ssl server:
#include "sslserver.h"
#include <QtNetwork/QTcpServer>
#include <QtNetwork/QTcpSocket>
#include <QFile>
#include <QtNetwork/QSslKey>
#include <QtNetwork/QSslConfiguration>
#include <QtNetwork/QSslError>
SslServer::SslServer(QObject *parent) : QTcpServer(parent)
{
server = new QTcpServer(this);
if(!server->listen(QHostAddress::Any, 9996))
{
qDebug() << "Server could not start";
}
else
{
qDebug() << "Server started!";
}
connect(server, SIGNAL(newConnection()), this, SLOT(newConnectionRecognized()));
}
void SslServer::showErrors()
{
this-> err = socket->sslErrors();
for(int i=0;i<err.size();i++)
qDebug() << err[i];
}
SslServer::~SslServer()
{
}
void SslServer::newConnectionRecognized()
{
incomingConnection(server->nextPendingConnection()->socketDescriptor());
}
void SslServer::incomingConnection(qintptr socketDescriptor)
{
socket = new QSslSocket(this);
socket->setProtocol(QSsl::SslV3);
connect(socket, SIGNAL(sslErrors(QList<QSslError>)), this, SLOT(showErrors()));
connect(socket, SIGNAL(encrypted()), this, SLOT(ready()));
connect(socket, SIGNAL(readyRead()), this, SLOT(readChannel()));
// Read Key from file
QByteArray key;
QFile KeyFile("server.key");
if(KeyFile.open(QIODevice::ReadOnly))
{
key = KeyFile.readAll();
KeyFile.close();
}
else
{
qDebug() << KeyFile.errorString();
}
QSslKey sslKey(key, QSsl::Rsa);
socket->setPrivateKey(sslKey);
// Load server ssl certificate from file
QByteArray cert;
QFile CertFile("server.csr");
if(CertFile.open(QIODevice::ReadOnly))
{
cert = CertFile.readAll();
CertFile.close();
}
else
{
qDebug() << CertFile.errorString();
}
QSslCertificate sslCert(cert);
socket->setLocalCertificate(sslCert);
QSslConfiguration cfg = socket->sslConfiguration();
cfg.caCertificates();
if (!socket->setSocketDescriptor(socketDescriptor))ee
{
qDebug() << ("! Couldn't set socket descriptor");
delete socket;
return;
}
socket->startServerEncryption();
if (socket->isEncrypted())
emit socket->encrypted();
if(!socket->waitForEncrypted(3000)) {
qDebug("Wait for encrypted!!!!");
return;
}
while (true) {
socket->waitForReadyRead();
}
}
void SslServer::readChannel()
{
QByteArray qstrbytes = socket->readLine();
qDebug() << qstrbytes;
}
void SslServer::ready()
{
qDebug() << "Encrypted";
}
I have found the problem when I implement another client/server but this time with QTcpSocket. I dont know exactly why but I guess the problem is because of using socketDescriptor for creating a QSslSocket. When I created client and server with QTcpSocket they works perfectly without any event loop and only by connecting readyRead() signal to an slot. After that in order to testing some situation I have create QTcpSocket using socketDescriptor. Then I found the problem is from creating socket using socketDescriptor because this time the readyRead() signal doesn't work as before.

unable to establish two way communication using qt

I have used QTcpSocket and QTcpServer class of qt to establish two way communication. I am able to send data from client to server. But am not getting the response back from server i.e my client.cpp never fires readyRead() signal. I have checked using Wireshark that my data from the server is available in specifed port.
I am posting my client.cpp code( Please help) :
Client::Client(QObject* parent): QObject(parent)
{
socket = new QTcpSocket(this);
connect(socket, SIGNAL(connected()),
this, SLOT(startTransfer()));
connect(socket, SIGNAL(readyRead()),this, SLOT(startRead()));
connect(socket, SIGNAL(error(QAbstractSocket::SocketError)),
this, SLOT(socketError(QAbstractSocket::SocketError)) );
}
Client::~Client()
{
socket->close();
}
void Client::start(QString address, quint16 port)
{
addr.setAddress(address);
socket->connectToHost(addr,port,QTcpSocket::ReadWrite);
}
void Client::startTransfer()
{
printf("Connection established.\n");
char buffer[1024];
forever
{
printf(">> ");
gets(buffer);
int len = strlen(buffer);
buffer[len] = '\n';
buffer[len+1] = '\0';
socket->write(buffer);
socket->flush();
}
}
void Client::startRead()
{
cout<<"inside startRead()<<endl";
while(socket->canReadLine())
{
QByteArray ba = socket->readLine();
if(strcmp(ba.constData(), "!exit\n") == 0)
{
socket->disconnectFromHost();
break;
}
printf(">> %s", ba.constData());
}
}
void Client::socketError(QAbstractSocket::SocketError )
{
qDebug()<<"error" ;
}
Looks like you have forever loop here. This means that your Qt main eventloop never gets the control back after you call startTransfer(). How do you suppose the Qt should run the startRead() code if you block your execution thread with infinite loop?
For Amartel adding the server code:
Server::Server(QObject* parent): QObject(parent)
{
// cout << "Before connect" << endl;
connect(&server, SIGNAL(newConnection()),
this, SLOT(acceptConnection()));
cout << "Listening.." << endl;
server.listen(QHostAddress::Any, 9999);
// cout << "Server started.." << endl;
}
Server::~Server()
{
server.close();
}
void Server::acceptConnection()
{
// cout << "In acceptConnection" << endl;
client = server.nextPendingConnection();
connect(client, SIGNAL(readyRead()),
this, SLOT(startRead()));
}
void Server::startRead()
{
while(client->canReadLine())
{
QByteArray ba = client->readLine();
if(strcmp(ba.constData(), "!exit\n") == 0)
{
client->disconnectFromHost();
break;
}
printf(">> %s", ba.constData());
int result = 0;
bool ack = true;
result = client->write("I Reached");
cout<<result<<endl;
if(result <= 0)
qDebug("Ack NOT sent to client!!!");
else
qDebug("Ack sent to client.");
// client->write("I Reached");
client->flush();
}
}

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