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<refentry xml:id="function.session-create-id" xmlns="http://docbook.org/ns/docbook">

<refnamediv>

<refname>session_create_id</refname>

<refpurpose>Create new session id</refpurpose>

</refnamediv>

<refsect1 role="description">

&reftitle.description;

<methodsynopsis>

<type class="union"><type>string</type><type>false</type></type><methodname>session_create_id</methodname>

<methodparam choice="opt"><type>string</type><parameter>prefix</parameter><initializer>""</initializer></methodparam>

</methodsynopsis>

<para>

<function>session_create_id</function> is used to create new

session id for the current session. It returns collision free

session id.

</para>

<para>

If session is not active, collision check is omitted.

</para>

<para>

Session ID is created according to php.ini settings.

</para>

<para>

It is important to use the same user ID of your web server for GC

task script. Otherwise, you may have permission problems especially

with files save handler.

</para>

</refsect1>

<refsect1 role="parameters">

&reftitle.parameters;

<para>

<variablelist>

<varlistentry>

<term><parameter>prefix</parameter></term>

<listitem>

<para>

If <parameter>prefix</parameter> is specified, new session id

is prefixed by <parameter>prefix</parameter>. Not all

characters are allowed within the session id. Characters in

the range <literal>[a-zA-Z0-9,-]</literal> are allowed. Maximum length is 256 characters.

</para>

</listitem>

</varlistentry>

</variablelist>

</para>

</refsect1>

<refsect1 role="returnvalues">

&reftitle.returnvalues;

<para>

<function>session_create_id</function> returns new collision free

session id for the current session. If it is used without active

session, it omits collision check.

On failure, &false; is returned.

</para>

</refsect1>

<refsect1 role="examples">

&reftitle.examples;

<para>

<example>

<title><function>session_create_id</function> example with <function>session_regenerate_id</function></title>

<programlisting role="php">

<![CDATA[

<?php

// My session start function support timestamp management

function my_session_start() {

session_start();

// Do not allow to use too old session ID

if (!empty($_SESSION['deleted_time']) && $_SESSION['deleted_time'] < time() - 180) {

session_destroy();

session_start();

}

}

// My session regenerate id function

function my_session_regenerate_id() {

// Call session_create_id() while session is active to

// make sure collision free.

if (session_status() != PHP_SESSION_ACTIVE) {

session_start();

}

// WARNING: Never use confidential strings for prefix!

$newid = session_create_id('myprefix-');

// Set deleted timestamp. Session data must not be deleted immediately for reasons.

$_SESSION['deleted_time'] = time();

// Finish session

session_commit();

// Make sure to accept user defined session ID

// NOTE: You must enable use_strict_mode for normal operations.

ini_set('session.use_strict_mode', 0);

// Set new custom session ID

session_id($newid);

// Start with custom session ID

session_start();

}

// Make sure use_strict_mode is enabled.

// use_strict_mode is mandatory for security reasons.

ini_set('session.use_strict_mode', 1);

my_session_start();

// Session ID must be regenerated when

// - User logged in

// - User logged out

// - Certain period has passed

my_session_regenerate_id();

// Write useful codes

?>

]]>

</programlisting>

</example>

</para>

</refsect1>

<refsect1 role="seealso">

&reftitle.seealso;

<para>

<simplelist>

<member><function>session_regenerate_id</function></member>

<member><function>session_start</function></member>

<member><link linkend="ini.session.use-strict-mode">session.use_strict_mode</link></member>

<member><methodname>SessionHandler::create_sid</methodname></member>

</simplelist>

</para>

</refsect1>

</refentry>

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