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.\" ========================================================================
.\"
.IX Title "SSL_GET_VERSION 3ssl"
.TH SSL_GET_VERSION 3ssl 2024-10-23 3.4.0 OpenSSL
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
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.nh
.SH NAME
SSL_client_version, SSL_get_version, SSL_is_dtls, SSL_is_tls, SSL_is_quic,
SSL_version \- get the protocol information of a connection
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 1
\& #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_is_tls(const SSL *ssl);
\& int SSL_is_quic(const SSL *ssl);
\&
\& int SSL_version(const SSL *s);
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
For SSL, TLS and DTLS protocols \fBSSL_client_version()\fR returns the numeric
protocol version advertised by the client in the legacy_version field of the
ClientHello when initiating the connection. Note that, for TLS, this value
will never indicate a version greater than TLSv1.2 even if TLSv1.3 is
subsequently negotiated. For QUIC connections it returns OSSL_QUIC1_VERSION.
.PP
\&\fBSSL_get_version()\fR returns the name of the protocol used for the connection.
\&\fBSSL_version()\fR returns the numeric 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.
.PP
\&\fBSSL_is_dtls()\fR returns 1 if the connection is using DTLS or 0 if not.
.PP
\&\fBSSL_is_tls()\fR returns 1 if the connection is using SSL/TLS or 0 if not.
.PP
\&\fBSSL_is_quic()\fR returns 1 if the connection is using QUIC or 0 if not.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fBSSL_get_version()\fR returns one of the following strings:
.IP SSLv3 4
.IX Item "SSLv3"
The connection uses the SSLv3 protocol.
.IP TLSv1 4
.IX Item "TLSv1"
The connection uses the TLSv1.0 protocol.
.IP TLSv1.1 4
.IX Item "TLSv1.1"
The connection uses the TLSv1.1 protocol.
.IP TLSv1.2 4
.IX Item "TLSv1.2"
The connection uses the TLSv1.2 protocol.
.IP TLSv1.3 4
.IX Item "TLSv1.3"
The connection uses the TLSv1.3 protocol.
.IP DTLSv0.9 4
.IX Item "DTLSv0.9"
The connection uses an obsolete pre-standardisation DTLS protocol
.IP DTLSv1 4
.IX Item "DTLSv1"
The connection uses the DTLSv1 protocol
.IP DTLSv1.2 4
.IX Item "DTLSv1.2"
The connection uses the DTLSv1.2 protocol
.IP QUICv1 4
.IX Item "QUICv1"
The connection uses the QUICv1 protocol.
.IP unknown 4
.IX Item "unknown"
This indicates an unknown protocol version.
.PP
\&\fBSSL_version()\fR and \fBSSL_client_version()\fR return an integer which could include any
of the following:
.IP SSL3_VERSION 4
.IX Item "SSL3_VERSION"
The connection uses the SSLv3 protocol.
.IP TLS1_VERSION 4
.IX Item "TLS1_VERSION"
The connection uses the TLSv1.0 protocol.
.IP TLS1_1_VERSION 4
.IX Item "TLS1_1_VERSION"
The connection uses the TLSv1.1 protocol.
.IP TLS1_2_VERSION 4
.IX Item "TLS1_2_VERSION"
The connection uses the TLSv1.2 protocol.
.IP TLS1_3_VERSION 4
.IX Item "TLS1_3_VERSION"
The connection uses the TLSv1.3 protocol (never returned for
\&\fBSSL_client_version()\fR).
.IP DTLS1_BAD_VER 4
.IX Item "DTLS1_BAD_VER"
The connection uses an obsolete pre-standardisation DTLS protocol
.IP DTLS1_VERSION 4
.IX Item "DTLS1_VERSION"
The connection uses the DTLSv1 protocol
.IP DTLS1_2_VERSION 4
.IX Item "DTLS1_2_VERSION"
The connection uses the DTLSv1.2 protocol
.IP OSSL_QUIC1_VERSION 4
.IX Item "OSSL_QUIC1_VERSION"
The connection uses the QUICv1 protocol.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBssl\fR\|(7)
.SH HISTORY
.IX Header "HISTORY"
The \fBSSL_is_dtls()\fR function was added in OpenSSL 1.1.0. The \fBSSL_is_tls()\fR and
\&\fBSSL_is_quic()\fR functions were added in OpenSSL 3.2.
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2001\-2023 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (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
<https://www.openssl.org/source/license.html>.