1=pod
2
3=head1 NAME
4
5SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_version - get the
6protocol information of a connection
7
8=head1 SYNOPSIS
9
10 #include <openssl/ssl.h>
11
12 int SSL_client_version(const SSL *s);
13
14 const char *SSL_get_version(const SSL *ssl);
15
16 int SSL_is_dtls(const SSL *ssl);
17
18 int SSL_version(const SSL *s);
19
20=head1 DESCRIPTION
21
22SSL_client_version() returns the numeric protocol version advertised by the
23client in the legacy_version field of the ClientHello when initiating the
24connection. Note that, for TLS, this value will never indicate a version greater
25than TLSv1.2 even if TLSv1.3 is subsequently negotiated. SSL_get_version()
26returns the name of the protocol used for the connection. SSL_version() returns
27the numeric protocol version used for the connection. They should only be called
28after the initial handshake has been completed. Prior to that the results
29returned from these functions may be unreliable.
30
31SSL_is_dtls() returns one if the connection is using DTLS, zero if not.
32
33=head1 RETURN VALUES
34
35
36SSL_get_version() returns one of the following strings:
37
38=over 4
39
40=item SSLv3
41
42The connection uses the SSLv3 protocol.
43
44=item TLSv1
45
46The connection uses the TLSv1.0 protocol.
47
48=item TLSv1.1
49
50The connection uses the TLSv1.1 protocol.
51
52=item TLSv1.2
53
54The connection uses the TLSv1.2 protocol.
55
56=item TLSv1.3
57
58The connection uses the TLSv1.3 protocol.
59
60=item unknown
61
62This indicates an unknown protocol version.
63
64=back
65
66SSL_version() and SSL_client_version() return an integer which could include any
67of the following:
68
69=over 4
70
71=item SSL3_VERSION
72
73The connection uses the SSLv3 protocol.
74
75=item TLS1_VERSION
76
77The connection uses the TLSv1.0 protocol.
78
79=item TLS1_1_VERSION
80
81The connection uses the TLSv1.1 protocol.
82
83=item TLS1_2_VERSION
84
85The connection uses the TLSv1.2 protocol.
86
87=item TLS1_3_VERSION
88
89The connection uses the TLSv1.3 protocol (never returned for
90SSL_client_version()).
91
92=back
93
94=head1 SEE ALSO
95
96L<ssl(7)>
97
98=head1 HISTORY
99
100The SSL_is_dtls() function was added in OpenSSL 1.1.0.
101
102=head1 COPYRIGHT
103
104Copyright 2001-2018 The OpenSSL Project Authors. All Rights Reserved.
105
106Licensed under the Apache License 2.0 (the "License").  You may not use
107this file except in compliance with the License.  You can obtain a copy
108in the file LICENSE in the source distribution or at
109L<https://www.openssl.org/source/license.html>.
110
111=cut
112