=pod

=head1 NAME

SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_version - get the
protocol information of a connection

=head1 SYNOPSIS

 #include <openssl/ssl.h>

 int SSL_client_version(const SSL *s);

 const char *SSL_get_version(const SSL *ssl);

 int SSL_is_dtls(const SSL *ssl);

 int SSL_version(const SSL *s);

=head1 DESCRIPTION

SSL_client_version() returns the protocol version used by the client when
initiating the connection. SSL_get_version() returns the name of the protocol
used for the connection. SSL_version() returns the protocol version used for the
connection. They should only be called after the initial handshake has been
completed. Prior to that the results returned from these functions may be
unreliable.

SSL_is_dtls() returns one if the connection is using DTLS, zero if not.

=head1 RETURN VALUES

SSL_get_version() returns one of the following strings:

=over 4

=item SSLv3

The connection uses the SSLv3 protocol.

=item TLSv1

The connection uses the TLSv1.0 protocol.

=item TLSv1.1

The connection uses the TLSv1.1 protocol.

=item TLSv1.2

The connection uses the TLSv1.2 protocol.

=item TLSv1.3

The connection uses the TLSv1.3 protocol.

=item unknown

This indicates an unknown protocol version.

=back

SSL_version() and SSL_client_version() return an integer which could include any of
the following:

=over 4

=item SSL3_VERSION

The connection uses the SSLv3 protocol.

=item TLS1_VERSION

The connection uses the TLSv1.0 protocol.

=item TLS1_1_VERSION

The connection uses the TLSv1.1 protocol.

=item TLS1_2_VERSION

The connection uses the TLSv1.2 protocol.

=item TLS1_3_VERSION

The connection uses the TLSv1.3 protocol.

=back

=head1 SEE ALSO

L<ssl(7)>

=head1 HISTORY

SSL_is_dtls() was added in OpenSSL 1.1.0.

=head1 COPYRIGHT

Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the OpenSSL license (the "License").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.

=cut