Qt 如何让QNetworkProxy在第一个请求中发送用户名和密码？

我有用户名和密码的代码代理：

QNetworkProxy* proxy = new QNetworkProxy;
proxy->setType(QNetworkProxy::HttpProxy);
proxy->setHostName(proxyAddress.host);
proxy->setPort(proxyAddress.port);
proxy->setUser(proxyAddress.userName);
proxy->setPassword(proxyAddress.password);
QSslSocket* socket = new QSslSocket(this);
socket->setProxy(*proxy);
socket->connectToHost(remoteAddress.host, remoteAddress.port);

但请求没有用户名和密码。如何使用用户名和密码进行请求