Authenticators and monitors now use SSL when configured. The fix has two parts:
1) Removed the extra SSLConfig inside SSLProvider, as SSLContext already contains
the config.
2) When inputting parameter values to mysql_ssl_set(), empty strings are converted
to NULL-pointers as the function expects those for unused values.
The functionality is more a part of the provider than the context so it
should be defined in it. It also doesn't use any parts of the SSLContext
which makes it somewhat more clear that it doesn't belong there.
Changes to SSL configurations is expected to be rare which allows them to
be made into immutable objects once created. This is an acceptable
compromise between performance and usability.
The header depended on ssl.hh to include the OpenSSL headers even though
it used OpenSSL types. By fixing these dependencies the ssl.h header can
now freely include the rworker_local type which removes the need for the
hidden implementation of SSLProvider.
The class is intended to be inherited by objects that need an SSL context
and a configuration. In practice this will be servers and listeners.
The SSLContext is stored in a rworker_local shared_ptr that makes it
possible to update safely. As the copying is always done behind a lock the
cached local value always holds a valid SSLContext instance for the
duration of all function calls.
Using the pImpl idiom, the routingworker.hh header is not exposed in the
ssl.hh header. This allows the SSLProvider class to be inherited more
easily.
Changed getter function return values to std::string, converted
MXS_CONFIG_PARAMETER::set_from_list to take std::strings instead of const
char pointers.
