PHP 5.5.17 is available

XML External Entity Example

This example highlights XML code. It illustrates how to use an external entity reference handler to include and parse other documents, as well as how PIs can be processed, and a way of determining "trust" for PIs containing code.

XML documents that can be used for this example are found below the example (xmltest.xml and xmltest2.xml.)

Example #1 External Entity Example

<?php
$file 
"xmltest.xml";

function 
trustedFile($file
{
    
// only trust local files owned by ourselves
    
if (!preg_match("@^([a-z]+)\:\/\/@i"$file
        && 
fileowner($file) == getmyuid()) {
            return 
true;
    }
    return 
false;
}

function 
startElement($parser$name$attribs
{
    echo 
"&lt;<font color=\"#0000cc\">$name</font>";
    if (
count($attribs)) {
        foreach (
$attribs as $k => $v) {
            echo 
" <font color=\"#009900\">$k</font>=\"<font 
                   color=\"#990000\">
$v</font>\"";
        }
    }
    echo 
"&gt;";
}

function 
endElement($parser$name
{
    echo 
"&lt;/<font color=\"#0000cc\">$name</font>&gt;";
}

function 
characterData($parser$data
{
    echo 
"<b>$data</b>";
}

function 
PIHandler($parser$target$data
{
    switch (
strtolower($target)) {
        case 
"php":
            global 
$parser_file;
            
// If the parsed document is "trusted", we say it is safe
            // to execute PHP code inside it.  If not, display the code
            // instead.
            
if (trustedFile($parser_file[$parser])) {
                eval(
$data);
            } else {
                
printf("Untrusted PHP code: <i>%s</i>"
                        
htmlspecialchars($data));
            }
            break;
    }
}

function 
defaultHandler($parser$data
{
    if (
substr($data01) == "&" && substr($data, -11) == ";") {
        
printf('<font color="#aa00aa">%s</font>'
                
htmlspecialchars($data));
    } else {
        
printf('<font size="-1">%s</font>'
                
htmlspecialchars($data));
    }
}

function 
externalEntityRefHandler($parser$openEntityNames$base$systemId,
                                  
$publicId) {
    if (
$systemId) {
        if (!list(
$parser$fp) = new_xml_parser($systemId)) {
            
printf("Could not open entity %s at %s\n"$openEntityNames,
                   
$systemId);
            return 
false;
        }
        while (
$data fread($fp4096)) {
            if (!
xml_parse($parser$datafeof($fp))) {
                
printf("XML error: %s at line %d while parsing entity %s\n",
                       
xml_error_string(xml_get_error_code($parser)),
                       
xml_get_current_line_number($parser), $openEntityNames);
                
xml_parser_free($parser);
                return 
false;
            }
        }
        
xml_parser_free($parser);
        return 
true;
    }
    return 
false;
}

function 
new_xml_parser($file
{
    global 
$parser_file;

    
$xml_parser xml_parser_create();
    
xml_parser_set_option($xml_parserXML_OPTION_CASE_FOLDING1);
    
xml_set_element_handler($xml_parser"startElement""endElement");
    
xml_set_character_data_handler($xml_parser"characterData");
    
xml_set_processing_instruction_handler($xml_parser"PIHandler");
    
xml_set_default_handler($xml_parser"defaultHandler");
    
xml_set_external_entity_ref_handler($xml_parser"externalEntityRefHandler");
    
    if (!(
$fp = @fopen($file"r"))) {
        return 
false;
    }
    if (!
is_array($parser_file)) {
        
settype($parser_file"array");
    }
    
$parser_file[$xml_parser] = $file;
    return array(
$xml_parser$fp);
}

if (!(list(
$xml_parser$fp) = new_xml_parser($file))) {
    die(
"could not open XML input");
}

echo 
"<pre>";
while (
$data fread($fp4096)) {
    if (!
xml_parse($xml_parser$datafeof($fp))) {
        die(
sprintf("XML error: %s at line %d\n",
                    
xml_error_string(xml_get_error_code($xml_parser)),
                    
xml_get_current_line_number($xml_parser)));
    }
}
echo 
"</pre>";
echo 
"parse complete\n";
xml_parser_free($xml_parser);

?>

Example #2 xmltest.xml

<?xml version='1.0'?>
<!DOCTYPE chapter SYSTEM "/just/a/test.dtd" [
<!ENTITY plainEntity "FOO entity">
<!ENTITY systemEntity SYSTEM "xmltest2.xml">
]>
<chapter>
 <TITLE>Title &plainEntity;</TITLE>
 <para>
  <informaltable>
   <tgroup cols="3">
    <tbody>
     <row><entry>a1</entry><entry morerows="1">b1</entry><entry>c1</entry></row>
     <row><entry>a2</entry><entry>c2</entry></row>
     <row><entry>a3</entry><entry>b3</entry><entry>c3</entry></row>
    </tbody>
   </tgroup>
  </informaltable>
 </para>
 &systemEntity;
 <section id="about">
  <title>About this Document</title>
  <para>
   <!-- this is a comment -->
   <?php echo 'Hi!  This is PHP version ' . phpversion(); ?>
  </para>
 </section>
</chapter>

This file is included from xmltest.xml:

Example #3 xmltest2.xml

<?xml version="1.0"?>
<!DOCTYPE foo [
<!ENTITY testEnt "test entity">
]>
<foo>
   <element attrib="value"/>
   &testEnt;
   <?php echo "This is some more PHP code being executed."; ?>
</foo>

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