c++ - 如何让 QNetworkReply 返回自定义数据？

Question

我将使用 QNetworkAccessManager 通过我的移动应用向服务器发出对 HTTP 服务器的请求。问题是，如何将自定义数据链接到每个请求？我尝试子类化 QNetworkReply 但我发现我必须实现虚拟方法 close() 和 isSequential() 但我不知道它们应该返回什么所以我是恐怕我会破坏网络请求功能。

例如，当我的应用执行登录程序时，它必须存储帐户的电子邮件地址:

class MyApp : public QObject
{
    Q_OBJECT

private:
    QNetworkRequest             request;
    QNetworkReply               *reply;
    QNetworkAccessManager       *manager;

    ...

}

void MyApp::do_log_in(QString email, QString password) {
    QString s;

    someobject.email=email; // <-- I have to store email address before sending request to server, but where do I store it?
    s.append("http://myapp.com/do-auth.php?email=");
    s.append(QUrl::toPercentEncoding(email));
    s.append("&password=");
    s.append(QUrl::toPercentEncoding(password));
    connect(manager,SIGNAL(finished(QNetworkReply*)),this,SLOT(login_finished(QNetworkReply*)));
    request.setUrl(QUrl(s));
    manager->get(request);

}

void MyApp::login_finished(QNetworkReply *rep) {
    DepservReply *reply;
    QString email;
    ....
    email= ...... // <-- I need to get the email address from QNetworkReply object somehow
    ///my code here handling server reply
    ....
} 

那么，在我的案例中，我该如何实现电子邮件的存储和检索，我应该子类化哪些类以及我应该重新实现哪些方法？

Answer 1

您可以利用每个 QObject 中可用的动态属性系统并将数据保存在回复中:

// https://github.com/KubaO/stackoverflown/tree/master/questions/network-reply-tracking-40707025
#include <QtNetwork>

class MyCtl : public QObject
{
    Q_OBJECT
    QNetworkAccessManager manager{this};
    // ...
    void reply_finished(QNetworkReply *reply);
public:
    MyCtl(QObject *parent = nullptr);
    void do_log_in(const QString &email, const QString &password);
};

static const char kAuthGetSalt[] = "req_auth-get-salt";
static const char kDoAuth[] = "req_do-auth";
static const char kEmail[] = "req_email";
static const char kPassword[] = "req_password";

static const auto authGetSaltUrl = QStringLiteral("https://myapp.com/auth-get-salt.php?email=%1");
static const auto doAuthUrl = QStringLiteral("https://myapp.com/do-auth.php?email=%1&passwordHash=%2");

MyCtl::MyCtl(QObject *parent) : QObject{parent}
{
    connect(&manager, &QNetworkAccessManager::finished, this, &MyCtl::reply_finished);
}

void MyCtl::do_log_in(const QString &email, const QString &password) {
    auto url = authGetSaltUrl.arg(email);
    auto reply = manager.get(QNetworkRequest{url});
    reply->setProperty(kAuthGetSalt, true);
    reply->setProperty(kEmail, email);
    reply->setProperty(kPassword, password);
}

void MyCtl::reply_finished(QNetworkReply *reply) {
    if (!reply->property(kAuthGetSalt).isNull()) {
        reply->deleteLater(); // let's not leak the reply
        if (reply->error() == QNetworkReply::NoError) {
            auto salt = reply->readAll();
            auto email = reply->property(kEmail).toString();
            auto password = reply->property(kPassword).toString();
            Q_ASSERT(!password.isEmpty() && !email.isEmpty());
            QCryptographicHash hasher{QCryptographicHash::Sha1};
            hasher.addData(salt); // the server must hash the same way
            hasher.addData("----");
            hasher.addData(password.toUtf8());
            auto hash = hasher.result().toBase64(QByteArray::Base64UrlEncoding);
            auto url = doAuthUrl.arg(email).arg(QString::fromLatin1(hash));

            auto reply = manager.get(QNetworkRequest{url});
            reply->setProperty(kDoAuth, true);
            reply->setProperty(kEmail, email);
        }
    }
    else if (!reply->property(kDoAuth).isNull()) {
        if (reply->error() == QNetworkReply::NoError) {
            auto email = reply->property(kEmail).toString();
            // ...
        }
    }
}

通过让编译器检查您使用的标识符是否有效，将常量用作属性名称以避免拼写错误。

上面的示例纠正了代码中的以下关键安全问题:

1. 通过清晰的连接发送安全凭证:使用 https://，而不是 http://。

2. 以明文形式发送密码:相反，发送密码的加盐哈希值。创建帐户时，您的服务器应该为每个帐户生成一个随机盐。现有帐户可以不加盐，但一旦用户更改密码，它们就应该加盐。

另请注意，QString 到 QUrl 的转换将自动对字符串进行百分号编码，因此无需显式执行此操作。