SSL_get_version() was an easy one :-)

=pod

=head1 NAME

SSL_get_version - get the protocol version of a connection.

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 const char *SSL_get_version(SSL *ssl);

=head1 DESCRIPTION

SSL_get_cipher_version() returns the name of the protocol used for the

connection B<ssl>.

=head1 RETURN VALUES

The following strings can occur:

=over 4

=item SSLv2

The connection uses the SSLv2 protocol.

=item SSLv3

The connection uses the SSLv3 protocol.

=item TLSv1

The connection uses the TLSv1 protocol.

=item unknown

This indicates that no version has been set (no connection established).

=back

=head1 SEE ALSO

L<ssl(3)|ssl(3)>

=cut

L<SSL_get_rbio(3)|SSL_get_rbio(3)>,

L<SSL_get_session(3)|SSL_get_session(3)>,

L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,

L<SSL_get_version(3)|SSL_get_version(3)>,

L<SSL_library_init(3)|SSL_library_init(3)>,

L<SSL_load_client_CA_file(3)|SSL_load_client_CA_file(3)>,

L<SSL_new(3)|SSL_new(3)>,