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refsockinit.html

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  1. <html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>ne_sock_init</title><link rel="stylesheet" type="text/css" href="manual.css"><meta name="generator" content="DocBook XSL Stylesheets Vsnapshot"><link rel="home" href="index.html" title="neon HTTP/WebDAV client library"><link rel="up" href="ref.html" title="neon API reference"><link rel="prev" href="refshave.html" title="ne_shave"><link rel="next" href="refcert.html" title="ne_ssl_cert_identity"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">ne_sock_init</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="refshave.html">Prev</a> </td><th width="60%" align="center">neon API reference</th><td width="20%" align="right"> <a accesskey="n" href="refcert.html">Next</a></td></tr></table><hr></div><div class="refentry"><a name="refsockinit"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>ne_sock_init, ne_sock_exit — perform library initialization</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include &lt;ne_socket.h&gt;</pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">ne_sock_init</b>(</code></td><td><code>void)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">void <b class="fsfunc">ne_sock_exit</b>(</code></td><td><code>void)</code>;</td><td> </td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="id3761"></a><h2>Description</h2><p>In some platforms and configurations, neon may be using
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  2.     some socket or SSL libraries which require global initialization
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  3.     before use.  To perform this initialization, the
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  4.     <code class="function">ne_sock_init</code> function must be called before
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  5.     any other library functions are used.</p><p>Once all use of neon is complete,
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  6.     <code class="function">ne_sock_exit</code> can be called to perform
    7. 

  7.     de-initialization of socket or SSL libraries, if necessary.  Uses
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  8.     of <code class="function">ne_sock_init</code> and
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  9.     <code class="function">ne_sock_exit</code> are "reference counted"; if N
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  10.     calls to <code class="function">ne_sock_init</code> are made, only the Nth
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  11.     call to <code class="function">ne_sock_exit</code> will have effect.</p><p><code class="function">ne_sock_init</code> will set the disposition
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  12.     of the <code class="literal">SIGPIPE</code> signal to
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  13.     <span class="emphasis"><em>ignored</em></span>.  No change is made to the
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  14.     <code class="literal">SIGPIPE</code> disposition by
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  15.     <code class="function">ne_sock_exit</code>.</p><p>Both the SSL libraries supported by neon — OpenSSL
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  16.     and GnuTLS — require callbacks to be registered to allow
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  17.     thread-safe use of SSL.  These callbacks are stored as global
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  18.     variables and so their state persists for as long as the library
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  19.     in question is loaded into the process.  If multiple users of the
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  20.     SSL library exist within the process, this can be problematic,
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  21.     particularly if one is dynamically loaded (and may subsequently be
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  22.     unloaded).</p><p>If neon is configured using the
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  23.     <code class="literal">--enable-threadsafe-ssl</code> flag, thread-safe SSL
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  24.     support will be enabled automatically, as covered in the following
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  25.     section.  Otherwise, it is not safe to use neon with SSL in a
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  26.     multi-threaded process.  The <a class="xref" href="reffeat.html#ne_has_support">ne_has_support</a>
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  27.     function can be used to determine whether neon is built to
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  28.     enable thread-safety support in the SSL library.</p><div class="refsect2"><a name="id3781"></a><h3>Thread-safe SSL with OpenSSL</h3><p>neon follows two simple rules when dealing with the
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  29.       OpenSSL locking callbacks:
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  30. 

  31.       </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><code class="function">ne_sock_init</code> will set
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  32.         thread-safety locking callbacks if and only if no locking
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  33.         callbacks are already registered.</li><li class="listitem"><code class="function">ne_sock_exit</code> will
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  34.         unset the thread-safety locking callbacks if and only if the
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  35.         locking callbacks registered are those registered by
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  36.         <code class="function">ne_sock_init</code>.</li></ul></div><p>
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  37. 

  38.       Applications and libraries should be able to co-operate to
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  39.       ensure that SSL use is always thread-safe if similar rules are
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  40.       always followed.</p></div><div class="refsect2"><a name="id3792"></a><h3>Thread-safe SSL with GnuTLS</h3><p>The cryptography library used by GnuTLS, libgcrypt, only
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  41.       supports an initialization operation to register thread-safety
    42. 

  42.       callbacks.  <code class="function">ne_sock_init</code> will register the
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  43.       thread-safe locking callbacks on first use;
    44. 

  44.       <code class="function">ne_sock_exit</code> cannot unregister them.  If
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  45.       multiple users of GnuTLS are present within the process, it is
    46. 

  46.       unsafe to dynamically unload neon from the process if neon
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  47.       is configured with thread-safe SSL support enabled (since the
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  48.       callbacks would be left pointing at unmapped memory once neon
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  49.       is unloaded).</p></div></div><div class="refsect1"><a name="id3797"></a><h2>Return value</h2><p><code class="function">ne_sock_init</code> returns zero on success,
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  50.     or non-zero on error.  If an error occurs, no further use of the
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  51.     neon library should be attempted.</p></div><div class="refsect1"><a name="id3801"></a><h2>See also</h2><p><a class="xref" href="refneon.html" title="neon"><span class="refentrytitle">neon</span></a>, <a class="xref" href="reffeat.html" title="ne_has_support"><span class="refentrytitle">ne_has_support</span></a></p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="refshave.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ref.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="refcert.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">ne_shave </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> ne_ssl_cert_identity</td></tr></table></div></body></html>
    52.