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<ul id="index">
  <li><a href="#NAME">NAME</a></li>
  <li><a href="#SYNOPSIS">SYNOPSIS</a></li>
  <li><a href="#DESCRIPTION">DESCRIPTION</a></li>
  <li><a href="#RETURN-VALUES">RETURN VALUES</a></li>
  <li><a href="#SEE-ALSO">SEE ALSO</a></li>
  <li><a href="#HISTORY">HISTORY</a></li>
  <li><a href="#COPYRIGHT">COPYRIGHT</a></li>
</ul>

<h1 id="NAME">NAME</h1>

<p>SSL_set_bio, SSL_set0_rbio, SSL_set0_wbio - connect the SSL object with a BIO</p>

<h1 id="SYNOPSIS">SYNOPSIS</h1>

<pre><code>#include &lt;openssl/ssl.h&gt;

void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio);
void SSL_set0_rbio(SSL *s, BIO *rbio);
void SSL_set0_wbio(SSL *s, BIO *wbio);</code></pre>

<h1 id="DESCRIPTION">DESCRIPTION</h1>

<p>SSL_set0_rbio() connects the BIO <b>rbio</b> for the read operations of the <b>ssl</b> object. The SSL engine inherits the behaviour of <b>rbio</b>. If the BIO is nonblocking then the <b>ssl</b> object will also have nonblocking behaviour. This function transfers ownership of <b>rbio</b> to <b>ssl</b>. It will be automatically freed using <a href="../man3/BIO_free_all.html">BIO_free_all(3)</a> when the <b>ssl</b> is freed. On calling this function, any existing <b>rbio</b> that was previously set will also be freed via a call to <a href="../man3/BIO_free_all.html">BIO_free_all(3)</a> (this includes the case where the <b>rbio</b> is set to the same value as previously).</p>

<p>If using a custom BIO, <b>rbio</b> must implement either <a href="../man3/BIO_meth_set_read_ex.html">BIO_meth_set_read_ex(3)</a> or <a href="../man3/BIO_meth_set_read.html">BIO_meth_set_read(3)</a>.</p>

<p>SSL_set0_wbio() works in the same as SSL_set0_rbio() except that it connects the BIO <b>wbio</b> for the write operations of the <b>ssl</b> object. Note that if the rbio and wbio are the same then SSL_set0_rbio() and SSL_set0_wbio() each take ownership of one reference. Therefore, it may be necessary to increment the number of references available using <a href="../man3/BIO_up_ref.html">BIO_up_ref(3)</a> before calling the set0 functions.</p>

<p>If using a custom BIO, <b>wbio</b> must implement <a href="../man3/BIO_meth_set_write_ex.html">BIO_meth_set_write_ex(3)</a> or <a href="../man3/BIO_meth_set_write.html">BIO_meth_set_write(3)</a>. It additionally must implement <a href="../man3/BIO_flush.html">BIO_flush(3)</a> using <b>BIO_CTRL_FLUSH</b> and <a href="../man3/BIO_meth_set_ctrl.html">BIO_meth_set_ctrl(3)</a>. If flushing is unnecessary with <b>wbio</b>, <a href="../man3/BIO_flush.html">BIO_flush(3)</a> should return one and do nothing.</p>

<p>SSL_set_bio() is similar to SSL_set0_rbio() and SSL_set0_wbio() except that it connects both the <b>rbio</b> and the <b>wbio</b> at the same time, and transfers the ownership of <b>rbio</b> and <b>wbio</b> to <b>ssl</b> according to the following set of rules:</p>

<ul>

<li><p>If neither the <b>rbio</b> or <b>wbio</b> have changed from their previous values then nothing is done.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are different and both are different to their previously set values then one reference is consumed for the rbio and one reference is consumed for the wbio.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are the same and the <b>rbio</b> is not the same as the previously set value then one reference is consumed.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are the same and the <b>rbio</b> is the same as the previously set value, then no additional references are consumed.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are different and the <b>rbio</b> is the same as the previously set value then one reference is consumed for the <b>wbio</b> and no references are consumed for the <b>rbio</b>.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are different and the <b>wbio</b> is the same as the previously set value and the old <b>rbio</b> and <b>wbio</b> values were the same as each other then one reference is consumed for the <b>rbio</b> and no references are consumed for the <b>wbio</b>.</p>

</li>
<li><p>If the <b>rbio</b> and <b>wbio</b> parameters are different and the <b>wbio</b> is the same as the previously set value and the old <b>rbio</b> and <b>wbio</b> values were different to each other, then one reference is consumed for the <b>rbio</b> and one reference is consumed for the <b>wbio</b>.</p>

</li>
</ul>

<p>Because of this complexity, this function should be avoided; use SSL_set0_rbio() and SSL_set0_wbio() instead.</p>

<p>Where a new BIO is set on a QUIC connection SSL object, blocking mode will be disabled on that SSL object if the BIO cannot support blocking mode. If another BIO is subsequently set on the SSL object which can support blocking mode, blocking mode will not be automatically re-enabled. For more information, see <a href="../man3/SSL_set_blocking_mode.html">SSL_set_blocking_mode(3)</a>.</p>

<h1 id="RETURN-VALUES">RETURN VALUES</h1>

<p>SSL_set_bio(), SSL_set0_rbio() and SSL_set0_wbio() cannot fail.</p>

<h1 id="SEE-ALSO">SEE ALSO</h1>

<p><a href="../man3/SSL_get_rbio.html">SSL_get_rbio(3)</a>, <a href="../man3/SSL_connect.html">SSL_connect(3)</a>, <a href="../man3/SSL_accept.html">SSL_accept(3)</a>, <a href="../man3/SSL_shutdown.html">SSL_shutdown(3)</a>, <a href="../man7/ssl.html">ssl(7)</a>, <a href="../man7/bio.html">bio(7)</a></p>

<h1 id="HISTORY">HISTORY</h1>

<p>SSL_set0_rbio() and SSL_set0_wbio() were added in OpenSSL 1.1.0.</p>

<h1 id="COPYRIGHT">COPYRIGHT</h1>

<p>Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved.</p>

<p>Licensed under the Apache License 2.0 (the &quot;License&quot;). 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 <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>


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