SSL_ACCEPT
Section: OpenSSL (3)
Updated: 2021-03-26
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NAME
SSL_accept - wait for a TLS/SSL client to initiate a TLS/SSL handshake
SYNOPSIS
#include <openssl/ssl.h>
int SSL_accept(SSL *ssl);
DESCRIPTION
SSL_accept() waits for a
TLS/SSL client to initiate the
TLS/SSL handshake.
The communication channel must already have been set and assigned to the
ssl by setting an underlying
BIO.
NOTES
The behaviour of
SSL_accept() depends on the underlying
BIO.
If the underlying BIO is blocking, SSL_accept() will only return once the
handshake has been finished or an error occurred.
If the underlying BIO is nonblocking, SSL_accept() will also return
when the underlying BIO could not satisfy the needs of SSL_accept()
to continue the handshake, indicating the problem by the return value -1.
In this case a call to SSL_get_error() with the
return value of SSL_accept() 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_accept().
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_shutdown(3),
ssl(7),
bio(7),
SSL_set_connect_state(3),
SSL_do_handshake(3),
SSL_CTX_new(3)
COPYRIGHT
Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the OpenSSL license (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>.