Description:
------------
PHP's xml_parse() ignores external DTD specified in the
XML file and thus can't parse the file if it has
unknown entities (defined in the DTD mentioned).


Test script:
---------------
#!/usr/bin/php
<?php

$xml_ext_dtd=<<<EOXML
<?xml version="1.0"?>
<!DOCTYPE mytag SYSTEM "./mytag.dtd">
<mytag><elem>one</elem><elem>two</elem><elem>&custom;</elem>/mytag>
EOXML;

$xml_int_dtd=<<<EOXML
<?xml version="1.0"?>
<!DOCTYPE mytag
[
<!ENTITY custom SYSTEM "file.txt">
]>
<mytag><elem>one</elem><elem>two</elem><elem>&custom;</elem>/mytag>
EOXML;

function externalEntityHandler($parser, $name, $base, $systemId, $publicId)
{
	echo "PROCESS EXTERNAL REFERENCE(file=$systemId)\n";
	return true;
}

function characterDataHandler($parser, $data)
{
	echo "CDATA found: '$data'\n";
}

function xerr($parser)
{
	$out = "XML parser error:";
	$out.=xml_error_string(xml_get_error_code($parser));
	$out.="\n";
	return $out;
}

echo "This works OK - parse xml1:\n$xml_int_dtd\n";
echo "---------------------------------------\n";
$xml_parser = xml_parser_create();
xml_set_character_data_handler($xml_parser, "characterDataHandler");
xml_set_external_entity_ref_handler($xml_parser, "externalEntityHandler");
xml_parse($xml_parser, $xml_int_dtd) or die(xerr($xml_parser));

echo "\nThis FAILS - parse xml2:\n$xml_ext_dtd\n";
echo "---------------------------------------\n";
$xml_parser = xml_parser_create();
xml_set_character_data_handler($xml_parser, "characterDataHandler");
xml_set_external_entity_ref_handler($xml_parser, "externalEntityHandler");
$rv = xml_parse($xml_parser, $xml_ext_dtd);
if (!$rv) echo xerr($xml_parser);

echo "file 'mytag.dtd' is:\n".file_get_contents("./mytag.dtd");

?>

Expected result:
----------------
This works OK - parse xml1:
<?xml version="1.0"?>
<!DOCTYPE mytag
[
<!ENTITY custom SYSTEM "file.txt">
]>
<mytag><elem>one</elem><elem>two</elem><elem>&custom;</elem>/mytag>
---------------------------------------
CDATA found: 'one'
CDATA found: 'two'
PROCESS EXTERNAL REFERENCE(file=file.txt)


Actual result:
--------------
This FAILS - parse xml2:
<?xml version="1.0"?>
<!DOCTYPE mytag SYSTEM "./mytag.dtd">
<mytag><elem>one</elem><elem>two</elem><elem>&custom;</elem>/mytag>
---------------------------------------
CDATA found: 'one'
CDATA found: 'two'
XML parser error:Undeclared entity warning
file 'mytag.dtd' is:
<!ENTITY custom SYSTEM "file.txt">