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>.