- NAME
- SYNOPSIS
- DESCRIPTION
- NOTES
- RETURN VALUES
- SEE ALSO
- COPYRIGHT

# 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:

1. 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.

2. 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 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.