curl that uses the new CURLOPT_FTP_SSL_CCC option in libcurl. If enabled, it
will make libcurl shutdown SSL/TLS after the authentication is done on a
FTP-SSL operation.
internally, with code provided by sslgen.c. All SSL-layer-specific code is
then written in ssluse.c (for OpenSSL) and gtls.c (for GnuTLS).
As far as possible, internals should not need to know what SSL layer that is
in use. Building with GnuTLS currently makes two test cases fail.
TODO.gnutls contains a few known outstanding issues for the GnuTLS support.
GnuTLS support is enabled with configure --with-gnutls