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<title>SSL_pending</title>
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<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>
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<h1 id="NAME">NAME</h1>
<p>SSL_pending, SSL_has_pending - check for readable bytes buffered in an SSL object</p>
<h1 id="SYNOPSIS">SYNOPSIS</h1>
<pre><code> #include <openssl/ssl.h>
int SSL_pending(const SSL *ssl);
int SSL_has_pending(const SSL *s);</code></pre>
<h1 id="DESCRIPTION">DESCRIPTION</h1>
<p>Data is received in whole blocks known as records from the peer. A whole record is processed (e.g. decrypted) in one go and is buffered by OpenSSL until it is read by the application via a call to <a href="../man3/SSL_read_ex.html">SSL_read_ex(3)</a> or <a href="../man3/SSL_read.html">SSL_read(3)</a>.</p>
<p>SSL_pending() returns the number of bytes which have been processed, buffered and are available inside <b>ssl</b> for immediate read.</p>
<p>If the <b>SSL</b> object's <i>read_ahead</i> flag is set (see <a href="../man3/SSL_CTX_set_read_ahead.html">SSL_CTX_set_read_ahead(3)</a>), additional protocol bytes (beyond the current record) may have been read containing more TLS/SSL records. This also applies to DTLS and pipelining (see <a href="../man3/SSL_CTX_set_split_send_fragment.html">SSL_CTX_set_split_send_fragment(3)</a>). These additional bytes will be buffered by OpenSSL but will remain unprocessed until they are needed. As these bytes are still in an unprocessed state SSL_pending() will ignore them. Therefore, it is possible for no more bytes to be readable from the underlying BIO (because OpenSSL has already read them) and for SSL_pending() to return 0, even though readable application data bytes are available (because the data is in unprocessed buffered records).</p>
<p>SSL_has_pending() returns 1 if <b>s</b> has buffered data (whether processed or unprocessed) and 0 otherwise. Note that it is possible for SSL_has_pending() to return 1, and then a subsequent call to SSL_read_ex() or SSL_read() to return no data because the unprocessed buffered data when processed yielded no application data (for example this can happen during renegotiation). It is also possible in this scenario for SSL_has_pending() to continue to return 1 even after an SSL_read_ex() or SSL_read() call because the buffered and unprocessed data is not yet processable (e.g. because OpenSSL has only received a partial record so far).</p>
<h1 id="RETURN-VALUES">RETURN VALUES</h1>
<p>SSL_pending() returns the number of buffered and processed application data bytes that are pending and are available for immediate read. SSL_has_pending() returns 1 if there is buffered record data in the SSL object and 0 otherwise.</p>
<h1 id="SEE-ALSO">SEE ALSO</h1>
<p><a href="../man3/SSL_read_ex.html">SSL_read_ex(3)</a>, <a href="../man3/SSL_read.html">SSL_read(3)</a>, <a href="../man3/SSL_CTX_set_read_ahead.html">SSL_CTX_set_read_ahead(3)</a>, <a href="../man3/SSL_CTX_set_split_send_fragment.html">SSL_CTX_set_split_send_fragment(3)</a>, <a href="../man7/ssl.html">ssl(7)</a></p>
<h1 id="HISTORY">HISTORY</h1>
<p>The SSL_has_pending() function was added in OpenSSL 1.1.0.</p>
<h1 id="COPYRIGHT">COPYRIGHT</h1>
<p>Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.</p>
<p>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 <a href="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</a>.</p>
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