147 lines
5.5 KiB
HTML
147 lines
5.5 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of BIO</TITLE>
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</HEAD><BODY>
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<H1>BIO</H1>
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Section: OpenSSL (7SSL)<BR>Updated: 2021-03-22<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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bio - Basic I/O abstraction
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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#include <<A HREF="file:///usr/include/openssl/bio.h">openssl/bio.h</A>>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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A <FONT SIZE="-1">BIO</FONT> is an I/O abstraction, it hides many of the underlying I/O
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details from an application. If an application uses a <FONT SIZE="-1">BIO</FONT> for its
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I/O it can transparently handle <FONT SIZE="-1">SSL</FONT> connections, unencrypted network
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connections and file I/O.
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<P>
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There are two type of <FONT SIZE="-1">BIO,</FONT> a source/sink <FONT SIZE="-1">BIO</FONT> and a filter <FONT SIZE="-1">BIO.</FONT>
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<P>
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As its name implies a source/sink <FONT SIZE="-1">BIO</FONT> is a source and/or sink of data,
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examples include a socket <FONT SIZE="-1">BIO</FONT> and a file <FONT SIZE="-1">BIO.</FONT>
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<P>
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A filter <FONT SIZE="-1">BIO</FONT> takes data from one <FONT SIZE="-1">BIO</FONT> and passes it through to
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another, or the application. The data may be left unmodified (for
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example a message digest <FONT SIZE="-1">BIO</FONT>) or translated (for example an
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encryption <FONT SIZE="-1">BIO</FONT>). The effect of a filter <FONT SIZE="-1">BIO</FONT> may change according
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to the I/O operation it is performing: for example an encryption
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<FONT SIZE="-1">BIO</FONT> will encrypt data if it is being written to and decrypt data
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if it is being read from.
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<P>
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BIOs can be joined together to form a chain (a single <FONT SIZE="-1">BIO</FONT> is a chain
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with one component). A chain normally consist of one source/sink
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<FONT SIZE="-1">BIO</FONT> and one or more filter BIOs. Data read from or written to the
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first <FONT SIZE="-1">BIO</FONT> then traverses the chain to the end (normally a source/sink
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<FONT SIZE="-1">BIO</FONT>).
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<P>
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Some BIOs (such as memory BIOs) can be used immediately after calling
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<B>BIO_new()</B>. Others (such as file BIOs) need some additional initialization,
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and frequently a utility function exists to create and initialize such BIOs.
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<P>
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If <B>BIO_free()</B> is called on a <FONT SIZE="-1">BIO</FONT> chain it will only free one <FONT SIZE="-1">BIO</FONT> resulting
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in a memory leak.
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<P>
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Calling <B>BIO_free_all()</B> on a single <FONT SIZE="-1">BIO</FONT> has the same effect as calling
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<B>BIO_free()</B> on it other than the discarded return value.
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<P>
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Normally the <B>type</B> argument is supplied by a function which returns a
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pointer to a <FONT SIZE="-1">BIO_METHOD.</FONT> There is a naming convention for such functions:
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a source/sink <FONT SIZE="-1">BIO</FONT> is normally called BIO_s_*() and a filter <FONT SIZE="-1">BIO</FONT>
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BIO_f_*();
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<A NAME="lbAE"> </A>
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<H2>EXAMPLES</H2>
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Create a memory <FONT SIZE="-1">BIO:</FONT>
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<P>
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<PRE>
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BIO *mem = BIO_new(BIO_s_mem());
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</PRE>
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<A NAME="lbAF"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_ctrl">BIO_ctrl</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_f_base64">BIO_f_base64</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_f_buffer">BIO_f_buffer</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_f_cipher">BIO_f_cipher</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_f_md">BIO_f_md</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_f_null">BIO_f_null</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_f_ssl">BIO_f_ssl</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_find_type">BIO_find_type</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_new">BIO_new</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_new_bio_pair">BIO_new_bio_pair</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_push">BIO_push</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_read_ex">BIO_read_ex</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_s_accept">BIO_s_accept</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_s_bio">BIO_s_bio</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_s_connect">BIO_s_connect</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_s_fd">BIO_s_fd</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_s_file">BIO_s_file</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_s_mem">BIO_s_mem</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_s_null">BIO_s_null</A></B>(3), <B><A HREF="/cgi-bin/man/man2html?3+BIO_s_socket">BIO_s_socket</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_set_callback">BIO_set_callback</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+BIO_should_retry">BIO_should_retry</A></B>(3)
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<A NAME="lbAG"> </A>
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<H2>COPYRIGHT</H2>
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Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
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<P>
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Licensed under the OpenSSL license (the ``License''). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file <FONT SIZE="-1">LICENSE</FONT> in the source distribution or at
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<<A HREF="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</A>>.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">EXAMPLES</A><DD>
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<DT id="5"><A HREF="#lbAF">SEE ALSO</A><DD>
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<DT id="6"><A HREF="#lbAG">COPYRIGHT</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:06:07 GMT, March 31, 2021
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</BODY>
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</HTML>
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