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Thread: A Web Proxy multithread

  1. 29th July 2011, 18:17 #1
    giusepped
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    Default A Web Proxy multithread

    I found within the Web a good example to implement an Http Proxy.
    It works great, but the problem is that it is single threaded.
    I tried to change it to a multithread version, but for some odd reason the code fires a segfault.
    The original single thread version follows:
    Qt Code: 
    1. /*
    2.  
    3. */
    4.  
    5. #include "webproxy.h"
    6. #include <QtNetwork>
    7. #include <QMessageBox>
    8. #include <QtGui>
    9. #include <QHash>
    10.  
    11.  
    12. WebProxy::WebProxy(QObject *parent,int port): QObject(parent)
    13.  
    14.     {
    15.  
    16.         QTcpServer *proxyServer = new QTcpServer(this);
    17.         if (!proxyServer->listen(QHostAddress::Any, port)) {
    18.            emit error(1);
    19.  
    20.             return;
    21.         }
    22.  
    23.         connect(proxyServer, SIGNAL(newConnection()), this, SLOT(manageQuery()));
    24.         qDebug() << "Proxy server running at port" << proxyServer->serverPort();
    25.  
    26.  
    27.     }
    28.  
    29. void WebProxy::setAddress(const QHostAddress &a, int port)
    30. {
    31.     proxyAddress = a;
    32.     proxyPort    = port;
    33.     port = port < 0 ? 8081 : port;
    34.  
    35.  
    36. }
    37.  
    38. void WebProxy::manageQuery() {
    39.         QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender());
    40.         QTcpSocket *socket = proxyServer->nextPendingConnection();
    41.         connect(socket, SIGNAL(readyRead()), this, SLOT(processQuery()));
    42.         connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
    43.         qDebug()<<"New connection started..."<<socket->peerAddress();
    44.     }
    45. QUrl WebProxy::getUrl(QList<QByteArray > &entries)
    46.    {
    47.  
    48.        QByteArray method = entries.value(0);
    49.        QByteArray address = entries.value(1);
    50.        QByteArray version = entries.value(2);
    51.  
    52.  
    53.        QUrl url = QUrl::fromEncoded(address);
    54.        if (!url.isValid()) {
    55.  
    56.            qWarning() << "Invalid URL:" << url;
    57.            return QString();
    58.        }
    59.        return url;
    60.    }
    61.  
    62.   void WebProxy::processQuery() {
    63.  
    64.         QTcpSocket *socket = qobject_cast<QTcpSocket*>(sender());
    65.         QByteArray requestData = socket->readAll();
    66.  
    67.         int pos = requestData.indexOf("\r\n");
    68.  
    69.         QByteArray requestLine = requestData.left(pos);
    70.         requestData.remove(0, pos + 2);
    71.  
    72.         QList<QByteArray> entries = requestLine.split(' ');
    73.         QByteArray method         = entries.value(0);
    74.         QByteArray address         = entries.value(1);
    75.         QByteArray version         = entries.value(2);
    76.  
    77.         QByteArray auth;
    78.         QByteArray authMethod;
    79.  
    80.         QUrl url = QUrl::fromEncoded(address);
    81.         if (!url.isValid()) {
    82.             qWarning() << "Invalid URL:" << url;
    83.             socket->disconnectFromHost();
    84.             return;
    85.         }
    86.  
    87.         QString host              = url.host();
    88.  
    89.         int port = (url.port() <= 0) ? 80 : url.port();
    90.         QByteArray req = url.encodedPath();
    91.         if (url.hasQuery())
    92.             req.append('?').append(url.encodedQuery());
    93.  
    94.         requestLine = method + " " + req + " " + version + "\r\n";
    95.  
    96.  
    97.         QString key = host + ':' + QString::number(port);
    98.         QTcpSocket *proxySocket = socket->findChild<QTcpSocket*>(key);
    99.         if (proxySocket) {
    100.             proxySocket->setObjectName(key);
    101.             proxySocket->setProperty("url", url);
    102.             proxySocket->setProperty("requestData", requestData);
    103.             proxySocket->write(requestData);
    104.         } else {
    105.             proxySocket = new QTcpSocket(socket);
    106.             proxySocket->setObjectName(key);
    107.             proxySocket->setProperty("url", url);
    108.             proxySocket->setProperty("requestData", requestData);
    109.             connect(proxySocket, SIGNAL(connected()), this, SLOT(sendRequest()));
    110.             connect(proxySocket, SIGNAL(readyRead()), this, SLOT(transferData()));
    111.             connect(proxySocket, SIGNAL(disconnected()), this, SLOT(closeConnection()));
    112.             connect(proxySocket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(closeConnection()));
    113.             proxySocket->connectToHost(host, port);
    114.         }
    115.     }
    116.  
    117. void WebProxy::sendRequest() {
    118.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    119.         QByteArray requestData = proxySocket->property("requestData").toByteArray();
    120.         proxySocket->write(requestData);
    121.     }
    122.  
    123. void WebProxy::transferData() {
    124.  
    125.  
    126.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    127.         QByteArray data = proxySocket->readAll();
    128.         QString host = proxySocket->peerAddress().toString();
    129.  
    130.         QTcpSocket *socket = qobject_cast<QTcpSocket*>(proxySocket->parent());
    131.         socket->write(data);
    132.  
    133.     }
    134.  
    135. void WebProxy::closeConnection() {
    136.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    137.         if (proxySocket) {
    138.             QTcpSocket *socket = qobject_cast<QTcpSocket*>(proxySocket->parent());
    139.             if (socket)
    140.                 socket->disconnectFromHost();
    141.             if (proxySocket->error() != QTcpSocket::RemoteHostClosedError)
    142.                 qWarning() << "Error for:" << proxySocket->property("url").toUrl()
    143.                         << proxySocket->errorString();
    144.             proxySocket->deleteLater();;
    145.         }
    146.     }
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    I call "new WebProxy " in the main.
    In the multithreaded version, I put all functions from manageQuery() inside a new threaded Class. But when a connection start, I got a segfault.
    Any help appreciated.
    Does anybody know
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  2. 30th July 2011, 09:11 #2
    tbscope
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    Default Re: A Web Proxy multithread

    Quote Originally Posted by giusepped View Post
    In the multithreaded version, I put all functions from manageQuery() inside a new threaded Class. But when a connection start, I got a segfault.
    Any help appreciated.
    Please post the code that causes the problem.
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  3. 30th July 2011, 14:01 #3
    giusepped
    giusepped is offline Advanced user
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    Default Re: A Web Proxy multithread

    Ok, but it is as I said.
    Qt Code: 
    1. WebProxy::WebProxy(QObject *parent,int port): QTcpServer(parent)
    2.  
    3.     {
    4.         qDebug()<<" Listen...";
    5.         authMethod = "";
    6.         proxyServer = new QTcpServer;
    7.         if (!proxyServer->listen(QHostAddress::Any, port)) {
    8.            emit error(1);
    9.  
    10.             return;
    11.         }
    12.  
    13.         connect(proxyServer, SIGNAL(newConnection()), this, SLOT(go()));
    14.         qDebug() << "Proxy server running at port" << proxyServer->serverPort() << proxyServer->serverAddress();
    15.  
    16. thr = 0;
    17.     }
    18. void WebProxy::addFilter(const QHash<QString, QString> &user, const QHash<QString, QString> &pass, const QHash<QString, QString> &u_format, const QHash<QString, QString> &p_format, const QHash<QString, int> &dvr,const QHash<QString,QString > &submit, const QHash<QString,QString> &search)
    19. {
    20.      qDebug() << "Server status..............";
    21.      qDebug() << "Server status"<<proxyServer->isListening();
    22.         hashUsername = user;
    23.         hashPassword = pass;
    24.         hashUFormat  = u_format;
    25.         hashPFormat  = p_format;
    26.         hashDvr      = dvr;
    27.         hashSubmit  = submit;
    28.         hashSearch  = search;
    29.  
    30.  
    31. }
    32.  
    33. void WebProxy::setAddress(const QHostAddress &a, int port)
    34. {
    35.     proxyAddress = a;
    36.     proxyPort    = port;
    37.     port = port < 0 ? 8081 : port;
    38.  
    39.  
    40. }
    41. void WebProxy::go()
    42. {
    43.     // Create a new Thread
    44.     int sck = socketDescriptor();
    45.     WebProxyThread *wpt = new WebProxyThread(sck,
    46.                                                hashUsername,
    47.                                                hashPassword,
    48.                                                hashUFormat,
    49.                                                hashPFormat,
    50.                                                hashDvr,
    51.                                                hashSubmit,
    52.                                                hashSearch,this);
    53.     connect(wpt, SIGNAL(finished()), wpt, SLOT(deleteLater()));
    54.     wpt->start();
    55.      qDebug() << "New thread"<<thr++;
    56.  
    57.  
    58. }
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    and the threaded proxy is in another class:
    Qt Code: 
    1. #include "webproxythreaded.h"
    2. #include <QTcpServer>
    3. #include <QTcpSocket>
    4. #include <QtGui>
    5.  
    6.  
    7. WebProxyThread::WebProxyThread(int socketDescriptor,
    8.                                const QHash<QString, QString> &user,
    9.                                const QHash<QString, QString> &pass,
    10.                                const QHash<QString, QString> &u_format,
    11.                                const QHash<QString, QString> &p_format,
    12.                                const QHash<QString, int> &dvr,
    13.                                const QHash<QString, QString> &submit_str,
    14.                                const QHash<QString, QString> &submit_search,
    15.                                QObject *parent) :
    16.         QThread(parent), socketDescriptor(socketDescriptor)
    17. {
    18.     hashUsername = user;
    19.     hashPassword = pass;
    20.     hashUFormat  = u_format;
    21.     hashPFormat  = p_format;
    22.     hashDvr      = dvr;
    23.     hashSubmit  = submit_str;
    24.     hashSearch  = submit_search;
    25. }
    26.  
    27.  
    28.  
    29.  
    30. void WebProxyThread::run()
    31. {
    32.     QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender());
    33.     QTcpSocket *socket = proxyServer->nextPendingConnection();
    34.     connect(socket, SIGNAL(readyRead()), this, SLOT(processQuery()));
    35.     connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
    36.  
    37. qDebug()<<"New connection started..run." ;
    38. //! [1] //! [2]
    39.  
    40.  
    41.  
    42.  
    43. }
    44. void WebProxyThread::manageQuery() {
    45.         QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender());
    46.         QTcpSocket *socket = proxyServer->nextPendingConnection();
    47.         connect(socket, SIGNAL(readyRead()), this, SLOT(processQuery()));
    48.         connect(socket, SIGNAL(disconnected()), socket, SLOT(deleteLater()));
    49.         qDebug()<<"New connection started..."<<socket->peerAddress();
    50.     }
    51. QUrl WebProxyThread::getUrl(QList<QByteArray > &entries)
    52.    {
    53.  
    54.        QByteArray method = entries.value(0);
    55.        QByteArray address = entries.value(1);
    56.        QByteArray version = entries.value(2);
    57.  
    58.        qDebug()<<method;
    59.        qDebug()<<address;
    60.        qDebug()<<version;
    61.        QUrl url = QUrl::fromEncoded(address);
    62.        if (!url.isValid()) {
    63.  
    64.            qWarning() << "Invalid URL:" << url;
    65.  
    66.            return QString();
    67.        }
    68.  
    69.  
    70.        return url;
    71.    }
    72.  
    73.   void WebProxyThread::processQuery() {
    74.  
    75.  
    76.         QTcpSocket *socket = qobject_cast<QTcpSocket*>(sender());
    77.         QByteArray requestData = socket->readAll();
    78.         int pos = requestData.indexOf("\r\n");
    79.         QByteArray requestLine = requestData.left(pos);
    80.         requestData.remove(0, pos + 2);
    81.         QList<QByteArray> entries = requestLine.split(' ');
    82.         QByteArray method         = entries.value(0);
    83.         QByteArray address        = entries.value(1);
    84.         QByteArray version        = entries.value(2);
    85.  
    86.         QUrl url = QUrl::fromEncoded(address);
    87.         if (!url.isValid()) {
    88.             qWarning() << "Invalid URL:" << url;
    89.             socket->disconnectFromHost();
    90.             return;
    91.         }
    92.  
    93.         QString host              = url.host();
    94.  
    95.         int port = (url.port() <= 0) ? 80 : url.port();
    96.         QByteArray req = url.encodedPath();
    97.         if (url.hasQuery())
    98.             req.append('?').append(url.encodedQuery());
    99.  
    100.         requestLine = method + " " + req + " " + version + "\r\n";
    101.         requestData.prepend(requestLine);
    102.         QString key = host + ':' + QString::number(port);
    103.         QTcpSocket *proxySocket = socket->findChild<QTcpSocket*>(key);
    104.         if (proxySocket) {
    105.             proxySocket->setObjectName(key);
    106.             proxySocket->setProperty("url", url);
    107.             proxySocket->setProperty("requestData", requestData);
    108.             proxySocket->write(requestData);
    109.         } else {
    110.             proxySocket = new QTcpSocket(socket);
    111.             proxySocket->setObjectName(key);
    112.             proxySocket->setProperty("url", url);
    113.             proxySocket->setProperty("requestData", requestData);
    114.             connect(proxySocket, SIGNAL(connected()), this, SLOT(sendRequest()));
    115.             connect(proxySocket, SIGNAL(readyRead()), this, SLOT(transferData()));
    116.             connect(proxySocket, SIGNAL(disconnected()), this, SLOT(closeConnection()));
    117.             connect(proxySocket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(closeConnection()));
    118.             proxySocket->connectToHost(host, port);
    119.         }
    120.     }
    121.  
    122. void WebProxyThread::sendRequest() {
    123.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    124.         QByteArray requestData = proxySocket->property("requestData").toByteArray();
    125.         proxySocket->write(requestData);
    126.     }
    127.  
    128. void WebProxyThread::transferData() {
    129.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    130.         QByteArray data = proxySocket->readAll();
    131.         QString host = proxySocket->peerAddress().toString();
    132.         QByteArray    filtered(data);
    133.         if (hashDvr.value(host) == 1)
    134.         {
    135.  
    136.         QString name = hashUFormat.value(host);
    137.         QString pass = hashPFormat.value(host);
    138.         QString repU  = "name=" + name + " value=" + hashUsername.value(host);
    139.         QString repP  = "name="+ pass + " value=" + hashPassword.value(host);
    140.         QString submit = hashSubmit.value(host);
    141.         QString search = hashSearch.value(host);
    142.         filtered.replace("name=" + name,repU.toLocal8Bit());
    143.         filtered.replace("name=" + pass,repP.toLocal8Bit());
    144.         filtered.replace(search.toLocal8Bit(),submit.toLocal8Bit());
    145.          }
    146.         QTcpSocket *socket = qobject_cast<QTcpSocket*>(proxySocket->parent());
    147.         socket->write(filtered);
    148.     }
    149.  
    150. void WebProxyThread::closeConnection() {
    151.         QTcpSocket *proxySocket = qobject_cast<QTcpSocket*>(sender());
    152.         if (proxySocket) {
    153.             QTcpSocket *socket = qobject_cast<QTcpSocket*>(proxySocket->parent());
    154.             if (socket)
    155.                 socket->disconnectFromHost();
    156.             if (proxySocket->error() != QTcpSocket::RemoteHostClosedError)
    157.                 qWarning() << "Error for:" << proxySocket->property("url").toUrl()
    158.                         << proxySocket->errorString();
    159.             proxySocket->deleteLater();;
    160.         }
    161.     }
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  4. 30th July 2011, 14:21 #4
    tbscope
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    Default Re: A Web Proxy multithread

    That's completely incorrect. There are lots of errors.

    One thing I'm pretty sure off is that the proxyServer pointer points to nothing or nothing usable.

    What does the following code do?
    Qt Code: 
    1. QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender());
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    Can you explain this?
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  5. 1st August 2011, 16:10 #5
    giusepped
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    Default Re: A Web Proxy multithread

    It should triy to guess who is the sender of the signal....
    G
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  6. 2nd August 2011, 06:42 #6
    NullPointer
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    Default Re: A Web Proxy multithread

    tbscope is right...

    When you connect proxyServer::newConnection and WebProxy::go(), they are on the same thread, so it is a direct connection. When this happens, Qt doesn't fill up the sender() value... so, when you do it in your wpt->start(), which calls run(), you are using a null value.
    As a try, you can replace
    Qt Code: 
    1. QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender());
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    by
    Qt Code: 
    1. QTcpServer *proxyServer = qobject_cast<QTcpServer*>(parent());
    To copy to clipboard, switch view to plain text mode 

    BTW, I think you will need at least one mutex to protect the following
    Qt Code: 
    1. QTcpServer *proxyServer = qobject_cast<QTcpServer*>(sender()); //this you should review
    2. QTcpSocket *socket = proxyServer->nextPendingConnection();
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    to avoid lost connections.
    Try making this a piece of WebProxy implementation, instead of doing this in the thread start...

    Or better: catch the nextPendigConnection, and pass it to constructor of the thread object (using socket descriptor, not sure if you can use a QTcpSocket across different threads)... and then use the QAbstractSocket::setSocketDescriptor at thread startup...

    hth.
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