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<refentry id="refsockinit">
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<refmeta>
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<refentrytitle>ne_sock_init</refentrytitle>
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<manvolnum>3</manvolnum>
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</refmeta>
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<refnamediv>
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<refname id="ne_sock_init">ne_sock_init</refname>
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<refname id="ne_sock_exit">ne_sock_exit</refname>
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<refpurpose>perform library initialization</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcsynopsisinfo>#include <ne_socket.h></funcsynopsisinfo>
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<funcprototype>
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<funcdef>int <function>ne_sock_init</function></funcdef>
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<void/>
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</funcprototype>
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<funcprototype>
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<funcdef>void <function>ne_sock_exit</function></funcdef>
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<void/>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>In some platforms and configurations, &neon; may be using
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some socket or SSL libraries which require global initialization
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before use. To perform this initialization, the
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<function>ne_sock_init</function> function must be called before
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any other library functions are used.</para>
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<para>Once all use of &neon; is complete,
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<function>ne_sock_exit</function> can be called to perform
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de-initialization of socket or SSL libraries, if necessary. Uses
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of <function>ne_sock_init</function> and
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<function>ne_sock_exit</function> are "reference counted"; if N
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calls to <function>ne_sock_init</function> are made, only the Nth
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call to <function>ne_sock_exit</function> will have effect.</para>
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<para><function>ne_sock_init</function> will set the disposition
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of the <literal>SIGPIPE</literal> signal to
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<emphasis>ignored</emphasis>. No change is made to the
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<literal>SIGPIPE</literal> disposition by
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<function>ne_sock_exit</function>.</para>
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<para>Both the SSL libraries supported by &neon; — OpenSSL
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and GnuTLS — require callbacks to be registered to allow
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thread-safe use of SSL. These callbacks are stored as global
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variables and so their state persists for as long as the library
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in question is loaded into the process. If multiple users of the
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SSL library exist within the process, this can be problematic,
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particularly if one is dynamically loaded (and may subsequently be
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unloaded).</para>
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<para>If &neon; is configured using the
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<literal>--enable-threadsafe-ssl</literal> flag, thread-safe SSL
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support will be enabled automatically, as covered in the following
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section. Otherwise, it is not safe to use &neon; with SSL in a
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multi-threaded process. The <xref linkend="ne_has_support"/>
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function can be used to determine whether &neon; is built to
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enable thread-safety support in the SSL library.</para>
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<refsect2>
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<title>Thread-safe SSL with OpenSSL</title>
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<para>&neon; follows two simple rules when dealing with the
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OpenSSL locking callbacks:
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<itemizedlist>
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<listitem><simpara><function>ne_sock_init</function> will set
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thread-safety locking callbacks if and only if no locking
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callbacks are already registered.</simpara></listitem>
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<listitem><simpara><function>ne_sock_exit</function> will
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unset the thread-safety locking callbacks if and only if the
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locking callbacks registered are those registered by
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<function>ne_sock_init</function>.</simpara></listitem>
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</itemizedlist>
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Applications and libraries should be able to co-operate to
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ensure that SSL use is always thread-safe if similar rules are
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always followed.</para>
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</refsect2>
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<refsect2>
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<title>Thread-safe SSL with GnuTLS</title>
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<para>The cryptography library used by GnuTLS, libgcrypt, only
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supports an initialization operation to register thread-safety
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callbacks. <function>ne_sock_init</function> will register the
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thread-safe locking callbacks on first use;
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<function>ne_sock_exit</function> cannot unregister them. If
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multiple users of GnuTLS are present within the process, it is
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unsafe to dynamically unload &neon; from the process if &neon;
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is configured with thread-safe SSL support enabled (since the
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callbacks would be left pointing at unmapped memory once &neon;
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is unloaded).</para>
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</refsect2>
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</refsect1>
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<refsect1>
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<title>Return value</title>
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<para><function>ne_sock_init</function> returns zero on success,
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or non-zero on error. If an error occurs, no further use of the
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&neon; library should be attempted.</para>
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</refsect1>
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<refsect1>
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<title>See also</title>
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<para><xref linkend="refneon"/>, <xref linkend="reffeat"/></para>
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</refsect1>
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</refentry>
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