qt - QSslSocket error when SSL is NOT used

Question

I have noticed this output in two of my Qt applications that use QNetworkRequest to load some data from outside over QNeworkRequest :

QSslSocket: cannot resolve TLSv1_1_client_method
QSslSocket: cannot resolve TLSv1_2_client_method
QSslSocket: cannot resolve TLSv1_1_server_method
QSslSocket: cannot resolve TLSv1_2_server_method
QSslSocket: cannot resolve SSL_select_next_proto
QSslSocket: cannot resolve SSL_CTX_set_next_proto_select_cb
QSslSocket: cannot resolve SSL_get0_next_proto_negotiated

One example of the request which causes these warnings to appear is

QNetworkReply reply = m_nam->get(QNetworkRequest(QUrl("http://api.openweathermap.org/data/2.5/forecast?id=2835297&mode=xml")));

I am reasonably sure that there is no TLS/SSL involved in any of the queries, all are plain HTTP. The messages appear always after the first request is dispatched, regardless of URL. I have no intention to ude SSL at all, there is no mention of SSL in the code, which means I can't ignore the warnings programatically.

My setup is Windows 7 64 bit, MSVC2013 and MinGW, Qt 5.3.2. The messages appear regardless of the compiler used. No OpenSSL or other SSL development libraries are installed.

And the question is: How do I get rid of these warnings?

Answer 1

These are just from qWarning() call when OpenSSL functions are resolved. It is not trying to call these functions, just resolving them. Calling unresolved functions would result in QSslSocket: cannot call unresolved function ... warning instead.

The warning is result of OpenSSL functions being resolved at runtime by a call to QSslSocket::supportsSsl() static in QNetworkAccessManager::supportedSchemesImplementation() that returns supported schemas --- http and, if SSL supported https.

You have few options about these warnings,

1. ignore them because you don't want or need SSL anyway
2. recompile Qt with -no-openssl passed to configure
3. ship OpenSSL so functions are resolved and https becomes available - probably not what you want