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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.libxml-set-external-entity-loader" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>libxml_set_external_entity_loader</refname>
<refpurpose>Changes the default external entity loader</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>bool</type><methodname>libxml_set_external_entity_loader</methodname>
<methodparam><type class="union"><type>callable</type><type>null</type></type><parameter>resolver_function</parameter></methodparam>
</methodsynopsis>
<para>
Changes the default external entity loader.
This can be used to suppress the expansion of arbitrary external entities to avoid XXE attacks,
even when <constant>LIBXML_NOENT</constant> has been set for the respective operation,
and is usually preferable over calling <function>libxml_disable_entity_loader</function>.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<variablelist>
<varlistentry>
<term><parameter>resolver_function</parameter></term>
<listitem>
<para>
A <type>callable</type> with the following signature:
<methodsynopsis>
<type class="union"><type>resource</type><type>string</type><type>null</type></type><methodname><replaceable>resolver</replaceable></methodname>
<methodparam><type class="union"><type>string</type><type>null</type></type><parameter>public_id</parameter></methodparam>
<methodparam><type>string</type><parameter>system_id</parameter></methodparam>
<methodparam><type>array</type><parameter>context</parameter></methodparam>
</methodsynopsis>
<variablelist>
<varlistentry>
<term><parameter>public_id</parameter></term>
<listitem>
<simpara>
The public ID.
</simpara>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>system_id</parameter></term>
<listitem>
<simpara>
The system ID.
</simpara>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>context</parameter></term>
<listitem>
<simpara>
An array with the four elements <literal>"directory"</literal>, <literal>"intSubName"</literal>,
<literal>"extSubURI"</literal> and <literal>"extSubSystem"</literal>.
</simpara>
</listitem>
</varlistentry>
</variablelist>
This callable should return a &resource;, a &string; from which a resource can be
opened. If &null; is returned, the entity reference resolution will fail.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
&return.success;
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>libxml_set_external_entity_loader</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
$xml = <<<XML
<!DOCTYPE foo PUBLIC "-//FOO/BAR" "http://example.com/foobar">
<foo>bar</foo>
XML;
$dtd = <<<DTD
<!ELEMENT foo (#PCDATA)>
DTD;
libxml_set_external_entity_loader(
function ($public, $system, $context) use($dtd) {
var_dump($public);
var_dump($system);
var_dump($context);
$f = fopen("php://temp", "r+");
fwrite($f, $dtd);
rewind($f);
return $f;
}
);
$dd = new DOMDocument;
$r = $dd->loadXML($xml);
var_dump($dd->validate());
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
string(10) "-//FOO/BAR"
string(25) "http://example.com/foobar"
array(4) {
["directory"] => NULL
["intSubName"] => NULL
["extSubURI"] => NULL
["extSubSystem"] => NULL
}
bool(true)
]]>
</screen>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>libxml_disable_entity_loader</function></member>
<member><function>libxml_get_external_entity_loader</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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sgml-minimize-attributes:nil
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sgml-parent-document:nil
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