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defuse/quine.php

Created September 21, 2013 20:39
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Escaping Challenge: Make a PHP script that (Z:) generates JavaScript code that generates an HTML page containing a PHP script that (goto Z)...
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quine.php
<?php
/* Escaping Challenge: Make a PHP script that (Z:) generates JavaScript code
* that generates an HTML page containing a PHP script that (goto Z) */
/* The purpose of this challenge is to demonstrate how complicated escaping can
* get when you're trying to combine 4 different languages (PHP, JavaScript,
* HTML, and string literals). */
function js_string_escape($data)
{
$safe = "";
for($i = 0; $i < strlen($data); $i++)
{
if(ctype_alnum($data[$i]))
$safe .= $data[$i];
else
$safe .= sprintf("\\x%02X", ord($data[$i]));
}
return $safe;
}
function javascriptify($str) {
return $script;
}
echo "<html><body><script>\n";
echo "var x = \"<pre>" . js_string_escape(htmlentities(file_get_contents(__FILE__), ENT_QUOTES)) . "</pre>\";\n";
echo "document.body.innerHTML = x;\n";
echo "</script></body></html>";
?>
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