SSL_GET_VERSION(3ossl) OpenSSL SSL_GET_VERSION(3ossl)
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
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_is_tls(const SSL *ssl);
int SSL_is_quic(const SSL *ssl);
int SSL_version(const SSL *s);
DESCRIPTION
For SSL, TLS and DTLS protocols SSL_client_version() 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.
SSL_get_version(3) returns the name of the protocol used for the
connection. SSL_version() 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.
SSL_is_dtls() returns 1 if the connection is using DTLS or 0 if not.
SSL_is_tls() returns 1 if the connection is using SSL/TLS or 0 if not.
SSL_is_quic() returns 1 if the connection is using QUIC or 0 if not.
RETURN VALUES
SSL_get_version(3) returns one of the following strings:
SSLv3
The connection uses the SSLv3 protocol.
TLSv1
The connection uses the TLSv1.0 protocol.
TLSv1.1
The connection uses the TLSv1.1 protocol.
TLSv1.2
The connection uses the TLSv1.2 protocol.
TLSv1.3
The connection uses the TLSv1.3 protocol.
DTLSv0.9
The connection uses an obsolete pre-standardisation DTLS protocol
DTLSv1
The connection uses the DTLSv1 protocol
DTLSv1.2
The connection uses the DTLSv1.2 protocol
QUICv1
The connection uses the QUICv1 protocol.
unknown
This indicates an unknown protocol version.
SSL_version() and SSL_client_version() return an integer which could
include any of the following:
SSL3_VERSION
The connection uses the SSLv3 protocol.
TLS1_VERSION
The connection uses the TLSv1.0 protocol.
TLS1_1_VERSION
The connection uses the TLSv1.1 protocol.
TLS1_2_VERSION
The connection uses the TLSv1.2 protocol.
TLS1_3_VERSION
The connection uses the TLSv1.3 protocol (never returned for
SSL_client_version()).
DTLS1_BAD_VER
The connection uses an obsolete pre-standardisation DTLS protocol
DTLS1_VERSION
The connection uses the DTLSv1 protocol
DTLS1_2_VERSION
The connection uses the DTLSv1.2 protocol
OSSL_QUIC1_VERSION
The connection uses the QUICv1 protocol.
SEE ALSO
ssl(7)
HISTORY
The SSL_is_dtls() function was added in OpenSSL 1.1.0. The SSL_is_tls()
and SSL_is_quic() functions were added in OpenSSL 3.2.
COPYRIGHT
Copyright 2001-2023 The OpenSSL Project Authors. All Rights Reserved.
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>.
3.5.0 2025-04-10 SSL_GET_VERSION(3ossl)
openssl 3.5.0 - Generated Wed Apr 30 07:38:55 CDT 2025