SSL_do_handshake

SSL_DO_HANDSHAKE(3)                  OpenSSL                 SSL_DO_HANDSHAKE(3)



NAME
       SSL_do_handshake - perform a TLS/SSL handshake

SYNOPSIS
        #include <openssl/ssl.h>

        int SSL_do_handshake(SSL *ssl);

DESCRIPTION
       SSL_do_handshake() will wait for a SSL/TLS handshake to take place. If
       the connection is in client mode, the handshake will be started. The
       handshake routines may have to be explicitly set in advance using either
       SSL_set_connect_state(3) or SSL_set_accept_state(3).

NOTES
       The behaviour of SSL_do_handshake() depends on the underlying BIO.

       If the underlying BIO is blocking, SSL_do_handshake() will only return
       once the handshake has been finished or an error occurred.

       If the underlying BIO is nonblocking, SSL_do_handshake() will also return
       when the underlying BIO could not satisfy the needs of SSL_do_handshake()
       to continue the handshake. In this case a call to SSL_get_error() with
       the return value of SSL_do_handshake() will yield SSL_ERROR_WANT_READ or
       SSL_ERROR_WANT_WRITE. The calling process then must repeat the call after
       taking appropriate action to satisfy the needs of SSL_do_handshake().
       The action depends on the underlying BIO. When using a nonblocking
       socket, nothing is to be done, but select() can be used to check for the
       required condition. When using a buffering BIO, like a BIO pair, data
       must be written into or retrieved out of the BIO before being able to
       continue.

RETURN VALUES
       The following return values can occur:

       0   The TLS/SSL handshake was not successful but was shut down controlled
           and by the specifications of the TLS/SSL protocol. Call
           SSL_get_error() with the return value ret to find out the reason.

       1   The TLS/SSL handshake was successfully completed, a TLS/SSL
           connection has been established.

       <0  The TLS/SSL handshake was not successful because a fatal error
           occurred either at the protocol level or a connection failure
           occurred. The shutdown was not clean. It can also occur if action is
           needed to continue the operation for nonblocking BIOs. Call
           SSL_get_error() with the return value ret to find out the reason.

SEE ALSO
       SSL_get_error(3), SSL_connect(3), SSL_accept(3), ssl(7), bio(7),
       SSL_set_connect_state(3)

COPYRIGHT
       Copyright 2002-2020 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>.



3.0.0-alpha12                      2021-02-18                SSL_DO_HANDSHAKE(3)