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Content-type sniffing
Syntax Syntax
Description Description
Based on the rules in http://tools.ietf.org/html/draft-abarth-mime-sniff-06
This is used since we can’t always trust Content-Type headers, and is based upon the HTML5 parsing rules.
This class can be overloaded with SimplePie::set_content_type_sniffer_class()
Source Source
File: wp-includes/SimplePie/Content/Type/Sniffer.php
{
/**
* File object
*
* @var SimplePie_File
*/
var $file;
/**
* Create an instance of the class with the input file
*
* @param SimplePie_Content_Type_Sniffer $file Input file
*/
public function __construct($file)
{
$this->file = $file;
}
/**
* Get the Content-Type of the specified file
*
* @return string Actual Content-Type
*/
public function get_type()
{
if (isset($this->file->headers['content-type']))
{
if (!isset($this->file->headers['content-encoding'])
&& ($this->file->headers['content-type'] === 'text/plain'
|| $this->file->headers['content-type'] === 'text/plain; charset=ISO-8859-1'
|| $this->file->headers['content-type'] === 'text/plain; charset=iso-8859-1'
|| $this->file->headers['content-type'] === 'text/plain; charset=UTF-8'))
{
return $this->text_or_binary();
}
if (($pos = strpos($this->file->headers['content-type'], ';')) !== false)
{
$official = substr($this->file->headers['content-type'], 0, $pos);
}
else
{
$official = $this->file->headers['content-type'];
}
$official = trim(strtolower($official));
if ($official === 'unknown/unknown'
|| $official === 'application/unknown')
{
return $this->unknown();
}
elseif (substr($official, -4) === '+xml'
|| $official === 'text/xml'
|| $official === 'application/xml')
{
return $official;
}
elseif (substr($official, 0, 6) === 'image/')
{
if ($return = $this->image())
{
return $return;
}
return $official;
}
elseif ($official === 'text/html')
{
return $this->feed_or_html();
}
return $official;
}
return $this->unknown();
}
/**
* Sniff text or binary
*
* @return string Actual Content-Type
*/
public function text_or_binary()
{
if (substr($this->file->body, 0, 2) === "\xFE\xFF"
|| substr($this->file->body, 0, 2) === "\xFF\xFE"
|| substr($this->file->body, 0, 4) === "\x00\x00\xFE\xFF"
|| substr($this->file->body, 0, 3) === "\xEF\xBB\xBF")
{
return 'text/plain';
}
elseif (preg_match('/[\x00-\x08\x0E-\x1A\x1C-\x1F]/', $this->file->body))
{
return 'application/octect-stream';
}
return 'text/plain';
}
/**
* Sniff unknown
*
* @return string Actual Content-Type
*/
public function unknown()
{
$ws = strspn($this->file->body, "\x09\x0A\x0B\x0C\x0D\x20");
if (strtolower(substr($this->file->body, $ws, 14)) === '<!doctype html'
|| strtolower(substr($this->file->body, $ws, 5)) === '<html'
|| strtolower(substr($this->file->body, $ws, 7)) === '<script')
{
return 'text/html';
}
elseif (substr($this->file->body, 0, 5) === '%PDF-')
{
return 'application/pdf';
}
elseif (substr($this->file->body, 0, 11) === '%!PS-Adobe-')
{
return 'application/postscript';
}
elseif (substr($this->file->body, 0, 6) === 'GIF87a'
|| substr($this->file->body, 0, 6) === 'GIF89a')
{
return 'image/gif';
}
elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
{
return 'image/png';
}
elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
{
return 'image/jpeg';
}
elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
{
return 'image/bmp';
}
elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
{
return 'image/vnd.microsoft.icon';
}
return $this->text_or_binary();
}
/**
* Sniff images
*
* @return string Actual Content-Type
*/
public function image()
{
if (substr($this->file->body, 0, 6) === 'GIF87a'
|| substr($this->file->body, 0, 6) === 'GIF89a')
{
return 'image/gif';
}
elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
{
return 'image/png';
}
elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
{
return 'image/jpeg';
}
elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
{
return 'image/bmp';
}
elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
{
return 'image/vnd.microsoft.icon';
}
return false;
}
/**
* Sniff HTML
*
* @return string Actual Content-Type
*/
public function feed_or_html()
{
$len = strlen($this->file->body);
$pos = strspn($this->file->body, "\x09\x0A\x0D\x20\xEF\xBB\xBF");
while ($pos < $len)
{
switch ($this->file->body[$pos])
{
case "\x09":
case "\x0A":
case "\x0D":
case "\x20":
$pos += strspn($this->file->body, "\x09\x0A\x0D\x20", $pos);
continue 2;
case '<':
$pos++;
break;
default:
return 'text/html';
}
if (substr($this->file->body, $pos, 3) === '!--')
{
$pos += 3;
if ($pos < $len && ($pos = strpos($this->file->body, '-->', $pos)) !== false)
{
$pos += 3;
}
else
{
return 'text/html';
}
}
elseif (substr($this->file->body, $pos, 1) === '!')
{
if ($pos < $len && ($pos = strpos($this->file->body, '>', $pos)) !== false)
{
$pos++;
}
else
{
return 'text/html';
}
}
elseif (substr($this->file->body, $pos, 1) === '?')
{
if ($pos < $len && ($pos = strpos($this->file->body, '?>', $pos)) !== false)
{
$pos += 2;
}
else
{
return 'text/html';
}
}
elseif (substr($this->file->body, $pos, 3) === 'rss'
|| substr($this->file->body, $pos, 7) === 'rdf:RDF')
{
return 'application/rss+xml';
}
elseif (substr($this->file->body, $pos, 4) === 'feed')
{
return 'application/atom+xml';
}
else
{
return 'text/html';
}
}
return 'text/html';
}
}