QSslSocket 等待数据时超时（但 QTcpSocket 不会）

Posted 2023-02-16

【中文标题】QSslSocket 等待数据时超时（但 QTcpSocket 不会）

【英文标题】：QSslSocket times out when waiting for data (but QTcpSocket does not)

【发布时间】：2017-03-30 10:53:56

【问题描述】：

这是一对简单的客户端和服务器应用程序，它们尝试通过 QTcpSocket 或 QSslSocket 进行通信并相互发送几个字节的数据。它似乎可以通过 TCP 工作，但是当我尝试使用 SSL 时，读取总是在服务器端超时。请告诉我我做错了什么。

这是我的完整代码：

客户：

#include <QTcpSocket>
#include <QSslSocket>
#include <QTimer>
#include <QApplication>

#define dumpvar(x) qDebug()<<#x<<'='<<x

// reads exactly len bytes from d into data,
// blocks until data is available
// or throws std::runtime_error on error or timeout
// timeout_msec = -1 means no timeout
void readWrapper(QIODevice &d, void *data, qint64 len, int timeout_msec)

    QTimer t;
    t.setSingleShot(true);
    // note: inactive timer's remainingTime() returns -1
    if (timeout_msec >= 0) t.start(timeout_msec);
    qint64 bytesRead = 0;
    auto dataPtr = (char*)data;
    while (bytesRead < len)
        auto bytesNeeded = len - bytesRead;
        auto ret = d.read(dataPtr, bytesNeeded);
        if (ret == -1)
            throw std::runtime_error(d.errorString().toStdString());
        
        qDebug()<<QString("Attempted to read %1 bytes, got %2 bytes")
                  .arg(bytesNeeded)
                  .arg(ret);
        if (ret == 0) 
            qDebug("Calling waitForReadyRead");
            bool ret = d.waitForReadyRead(t.remainingTime());
            if (!ret)
                qDebug()<<"waitForReadyRead failed";
                throw std::runtime_error(d.errorString().toStdString());
            
        
        else 
            bytesRead += ret;
            dataPtr += ret;
        
        if (t.remainingTime() == 0)
            throw std::runtime_error("blockingRead timeout");
    


QByteArray readWrapper(QIODevice &d, qint64 len, int timeout_msec = 10000)

    QByteArray ret;
    ret.resize(len);
    readWrapper(d, ret.data(), len, timeout_msec);
    return ret;


void writeWrapper(QIODevice &d, void *data, qint64 len)

    auto ret = d.write((char*)data, len);
    if (ret < len)
        throw std::runtime_error(QString("error writing data: %1")
                                 .arg(d.errorString())
                                 .toStdString());
    


void writeWrapper(QIODevice &d, const QByteArray &data)

    writeWrapper(d, (void*)data.data(), data.size());


using namespace std;

void handleConnection(QAbstractSocket& s)

    QByteArray data = "test c";
    qDebug()<<"writing data";
    writeWrapper(s, data);
    qDebug()<<"reading data";
    auto readData = readWrapper(s, 6);
    dumpvar(readData);
    s.disconnectFromHost();
    s.waitForDisconnected();


void tcpclient()

    QTcpSocket s;
    s.connectToHost("localhost", 1234);
    if(!s.waitForConnected(-1))
        qDebug()<<s.errorString();
        return;
    

    qDebug()<<"client connected";
    handleConnection(s);


void sslclient()

    QSslSocket s;
    auto cert = QSslCertificate::fromPath("/home/piotrek/cert.pem");
    Q_ASSERT(!cert.isEmpty());
    s.setCaCertificates(cert);
    s.ignoreSslErrors(QSslError::HostNameMismatch, cert[0]);
    s.connectToHostEncrypted("localhost", 1234);
    if (!s.waitForEncrypted(10000))
        dumpvar(s.errorString());
        dumpvar(s.sslErrors());
        return;
    

    qDebug()<<"client connected";
    handleConnection(s);



int main(int argc, char** argv)

    QCoreApplication a(argc, argv);

//  tcpclient();
    sslclient();

服务器：

#include <QTcpSocket>
#include <QSslSocket>
#include <QTimer>
#include <QCoreApplication>
#include <QTcpServer>
#include <QSslKey>

#define dumpvar(x) qDebug()<<#x<<'='<<x

// reads exactly len bytes from d into data,
// blocks until data is available
// or throws std::runtime_error on error or timeout
// timeout_msec = -1 means no timeout
void readWrapper(QIODevice &d, void *data, qint64 len, int timeout_msec)

    QTimer t;
    t.setSingleShot(true);
    // note: inactive timer's remainingTime() returns -1
    if (timeout_msec >= 0) t.start(timeout_msec);
    qint64 bytesRead = 0;
    auto dataPtr = (char*)data;
    while (bytesRead < len)
        auto bytesNeeded = len - bytesRead;
        auto ret = d.read(dataPtr, bytesNeeded);
        if (ret == -1)
            throw std::runtime_error(d.errorString().toStdString());
        
        qDebug()<<QString("Attempted to read %1 bytes, got %2 bytes")
                  .arg(bytesNeeded)
                  .arg(ret);
        if (ret == 0) 
            qDebug("Calling waitForReadyRead");
            bool ret = d.waitForReadyRead(t.remainingTime());
            if (!ret)
                qDebug()<<"waitForReadyRead failed";
                throw std::runtime_error(d.errorString().toStdString());
            
        
        else 
            bytesRead += ret;
            dataPtr += ret;
        
        if (t.remainingTime() == 0)
            throw std::runtime_error("blockingRead timeout");
    


QByteArray readWrapper(QIODevice &d, qint64 len, int timeout_msec = 10000)

    QByteArray ret;
    ret.resize(len);
    readWrapper(d, ret.data(), len, timeout_msec);
    return ret;


void writeWrapper(QIODevice &d, void *data, qint64 len)

    auto ret = d.write((char*)data, len);
    if (ret < len)
        throw std::runtime_error(QString("error writing data: %1")
                                 .arg(d.errorString())
                                 .toStdString());
    


void writeWrapper(QIODevice &d, const QByteArray &data)

    writeWrapper(d, (void*)data.data(), data.size());


void handleConnection(QAbstractSocket* s)

    qDebug()<<__FUNCTION__;
    QByteArray data = "test s";
    qDebug()<<"writing data";
    writeWrapper(*s, data);
    qDebug()<<"reading data";
    auto readData = readWrapper(*s, 6);
    dumpvar(readData);
    s->disconnectFromHost();
    s->waitForDisconnected();


class SslServer: public QTcpServer

    // QTcpServer interface
protected:
    void incomingConnection(qintptr handle) override
    
        QSslSocket s;
        if (!s.setSocketDescriptor(handle))
            dumpvar(s.errorString());
            return;
        

        s.setLocalCertificate("/home/piotrek/cert.pem");
        Q_ASSERT(!s.localCertificate().isNull());
        s.setPrivateKey("/home/piotrek/key.pem", QSsl::Rsa, QSsl::Pem, "test"); // last argument is private key decryption password
        Q_ASSERT(!s.privateKey().isNull());
        s.startServerEncryption();
        qDebug()<<"waiting for encrypted";
        if(!s.waitForEncrypted(10000))
            dumpvar(s.errorString());
            dumpvar(s.sslErrors());
            return;
        

        qDebug()<<"server encrypted";

        handleConnection(&s);
    
;

void tcpserver()

    QTcpServer *s = new QTcpServer;
    QObject::connect(s, &QTcpServer::newConnection, [s]
        handleConnection(s->nextPendingConnection());
    );

    s->listen(QHostAddress::Any, 1234);


void sslserver()

    auto s = new SslServer;
    s->listen(QHostAddress::Any, 1234);


int main(int argc, char *argv[])

    QCoreApplication a(argc, argv);

//  tcpserver();
    sslserver();

    return a.exec();

用于生成自签名证书的命令：

openssl req -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem -days 365

这是 TCP 上的输出：

客户：

client connected
writing data
reading data
"Attempted to read 6 bytes, got 0 bytes"
Calling waitForReadyRead
"Attempted to read 6 bytes, got 6 bytes"
readData = "test s"
QAbstractSocket::waitForDisconnected() is not allowed in UnconnectedState

服务器：

handleConnection
writing data
reading data
"Attempted to read 6 bytes, got 0 bytes"
Calling waitForReadyRead
"Attempted to read 6 bytes, got 6 bytes"
readData = "test c"

使用 SSL：

客户：

qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
client connected
writing data
reading data
"Attempted to read 6 bytes, got 6 bytes"
readData = "test s"

服务器：

qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
waiting for encrypted
server encrypted
handleConnection
writing data
reading data
"Attempted to read 6 bytes, got 0 bytes"
Calling waitForReadyRead
waitForReadyRead failed
terminate called after throwing an instance of 'std::runtime_error'
  what():  Network operation timed out

编辑：另外，如果我忽略 waitForReadyRead() 的返回值，read() 仍然会继续返回 0，即使我确实向连接的另一端写入了 6 个字节。

【参考方案1】：

因为您没有将套接字与信号和插槽异步使用，所以您必须选择哪一侧首先写入并在waitForBytesWritten 中阻塞，然后阻塞读取直到接收到数据。而另一方则以相反的顺序做同样的事情。

服务器：

void handleConnection(QAbstractSocket* s)

    qDebug()<<__FUNCTION__;
    QByteArray data = "test s";
    qDebug()<<"writing data";
    writeWrapper(*s, data);
    s->waitForBytesWritten(3000);
    qDebug()<<"reading data";
    auto readData = readWrapper(*s, 6);
    dumpvar(readData);
    s->disconnectFromHost();
    s->waitForDisconnected();

客户：

void handleConnection(QAbstractSocket& s)

    QByteArray data = "test c";
    qDebug()<<"reading data";
    auto readData = readWrapper(s, 6);
    dumpvar(readData);
    qDebug()<<"writing data";
    writeWrapper(s, data);
    s.waitForBytesWritten(3000);
    s.disconnectFromHost();
    s.waitForDisconnected();

服务器输出：

qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
waiting for encrypted
server encrypted
handleConnection
writing data
reading data
"Attempted to read 6 bytes, got 0 bytes"
Calling waitForReadyRead
"Attempted to read 6 bytes, got 6 bytes"
readData = "test c"
qt.network.ssl: QSslSocket::waitForDisconnected() is not allowed in UnconnectedState

客户端输出：

qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
client connected
reading data
"Attempted to read 6 bytes, got 6 bytes"
readData = "test s"
writing data
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