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Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" SSL_client_version, SSL_get_version, SSL_is_dtls, 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_version(const SSL *s); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\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 \s-1TLS,\s0 this value will never indicate a version greater than TLSv1.2 even if TLSv1.3 is subsequently negotiated. \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 one if the connection is using \s-1DTLS,\s0 zero 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 "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 "\s-1SSL3_VERSION\s0" 4 .IX Item "SSL3_VERSION" The connection uses the SSLv3 protocol. .IP "\s-1TLS1_VERSION\s0" 4 .IX Item "TLS1_VERSION" The connection uses the TLSv1.0 protocol. .IP "\s-1TLS1_1_VERSION\s0" 4 .IX Item "TLS1_1_VERSION" The connection uses the TLSv1.1 protocol. .IP "\s-1TLS1_2_VERSION\s0" 4 .IX Item "TLS1_2_VERSION" The connection uses the TLSv1.2 protocol. .IP "\s-1TLS1_3_VERSION\s0" 4 .IX Item "TLS1_3_VERSION" The connection uses the TLSv1.3 protocol (never returned for \&\fBSSL_client_version()\fR). .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. .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2001\-2018 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.