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   1  <?php
   2  /**
   3   * SimplePie
   4   *
   5   * A PHP-Based RSS and Atom Feed Framework.
   6   * Takes the hard work out of managing a complete RSS/Atom solution.
   7   *
   8   * Copyright (c) 2004-2012, Ryan Parman, Geoffrey Sneddon, Ryan McCue, and contributors
   9   * All rights reserved.
  10   *
  11   * Redistribution and use in source and binary forms, with or without modification, are
  12   * permitted provided that the following conditions are met:
  13   *
  14   *     * Redistributions of source code must retain the above copyright notice, this list of
  15   *       conditions and the following disclaimer.
  16   *
  17   *     * Redistributions in binary form must reproduce the above copyright notice, this list
  18   *       of conditions and the following disclaimer in the documentation and/or other materials
  19   *       provided with the distribution.
  20   *
  21   *     * Neither the name of the SimplePie Team nor the names of its contributors may be used
  22   *       to endorse or promote products derived from this software without specific prior
  23   *       written permission.
  24   *
  25   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS
  26   * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
  27   * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS
  28   * AND CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  30   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  31   * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
  32   * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33   * POSSIBILITY OF SUCH DAMAGE.
  34   *
  35   * @package SimplePie
  36   * @version 1.3.1
  37   * @copyright 2004-2012 Ryan Parman, Geoffrey Sneddon, Ryan McCue
  38   * @author Ryan Parman
  39   * @author Geoffrey Sneddon
  40   * @author Ryan McCue
  41   * @link http://simplepie.org/ SimplePie
  42   * @license http://www.opensource.org/licenses/bsd-license.php BSD License
  43   */
  44  
  45  
  46  /**
  47   * Content-type sniffing
  48   *
  49   * Based on the rules in http://tools.ietf.org/html/draft-abarth-mime-sniff-06
  50   *
  51   * This is used since we can't always trust Content-Type headers, and is based
  52   * upon the HTML5 parsing rules.
  53   *
  54   *
  55   * This class can be overloaded with {@see SimplePie::set_content_type_sniffer_class()}
  56   *
  57   * @package SimplePie
  58   * @subpackage HTTP
  59   */
  60  class SimplePie_Content_Type_Sniffer
  61  {
  62      /**
  63       * File object
  64       *
  65       * @var SimplePie_File
  66       */
  67      var $file;
  68  
  69      /**
  70       * Create an instance of the class with the input file
  71       *
  72       * @param SimplePie_Content_Type_Sniffer $file Input file
  73       */
  74  	public function __construct($file)
  75      {
  76          $this->file = $file;
  77      }
  78  
  79      /**
  80       * Get the Content-Type of the specified file
  81       *
  82       * @return string Actual Content-Type
  83       */
  84  	public function get_type()
  85      {
  86          if (isset($this->file->headers['content-type']))
  87          {
  88              if (!isset($this->file->headers['content-encoding'])
  89                  && ($this->file->headers['content-type'] === 'text/plain'
  90                      || $this->file->headers['content-type'] === 'text/plain; charset=ISO-8859-1'
  91                      || $this->file->headers['content-type'] === 'text/plain; charset=iso-8859-1'
  92                      || $this->file->headers['content-type'] === 'text/plain; charset=UTF-8'))
  93              {
  94                  return $this->text_or_binary();
  95              }
  96  
  97              if (($pos = strpos($this->file->headers['content-type'], ';')) !== false)
  98              {
  99                  $official = substr($this->file->headers['content-type'], 0, $pos);
 100              }
 101              else
 102              {
 103                  $official = $this->file->headers['content-type'];
 104              }
 105              $official = trim(strtolower($official));
 106  
 107              if ($official === 'unknown/unknown'
 108                  || $official === 'application/unknown')
 109              {
 110                  return $this->unknown();
 111              }
 112              elseif (substr($official, -4) === '+xml'
 113                  || $official === 'text/xml'
 114                  || $official === 'application/xml')
 115              {
 116                  return $official;
 117              }
 118              elseif (substr($official, 0, 6) === 'image/')
 119              {
 120                  if ($return = $this->image())
 121                  {
 122                      return $return;
 123                  }
 124                  else
 125                  {
 126                      return $official;
 127                  }
 128              }
 129              elseif ($official === 'text/html')
 130              {
 131                  return $this->feed_or_html();
 132              }
 133              else
 134              {
 135                  return $official;
 136              }
 137          }
 138          else
 139          {
 140              return $this->unknown();
 141          }
 142      }
 143  
 144      /**
 145       * Sniff text or binary
 146       *
 147       * @return string Actual Content-Type
 148       */
 149  	public function text_or_binary()
 150      {
 151          if (substr($this->file->body, 0, 2) === "\xFE\xFF"
 152              || substr($this->file->body, 0, 2) === "\xFF\xFE"
 153              || substr($this->file->body, 0, 4) === "\x00\x00\xFE\xFF"
 154              || substr($this->file->body, 0, 3) === "\xEF\xBB\xBF")
 155          {
 156              return 'text/plain';
 157          }
 158          elseif (preg_match('/[\x00-\x08\x0E-\x1A\x1C-\x1F]/', $this->file->body))
 159          {
 160              return 'application/octect-stream';
 161          }
 162          else
 163          {
 164              return 'text/plain';
 165          }
 166      }
 167  
 168      /**
 169       * Sniff unknown
 170       *
 171       * @return string Actual Content-Type
 172       */
 173  	public function unknown()
 174      {
 175          $ws = strspn($this->file->body, "\x09\x0A\x0B\x0C\x0D\x20");
 176          if (strtolower(substr($this->file->body, $ws, 14)) === '<!doctype html'
 177              || strtolower(substr($this->file->body, $ws, 5)) === '<html'
 178              || strtolower(substr($this->file->body, $ws, 7)) === '<script')
 179          {
 180              return 'text/html';
 181          }
 182          elseif (substr($this->file->body, 0, 5) === '%PDF-')
 183          {
 184              return 'application/pdf';
 185          }
 186          elseif (substr($this->file->body, 0, 11) === '%!PS-Adobe-')
 187          {
 188              return 'application/postscript';
 189          }
 190          elseif (substr($this->file->body, 0, 6) === 'GIF87a'
 191              || substr($this->file->body, 0, 6) === 'GIF89a')
 192          {
 193              return 'image/gif';
 194          }
 195          elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
 196          {
 197              return 'image/png';
 198          }
 199          elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
 200          {
 201              return 'image/jpeg';
 202          }
 203          elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
 204          {
 205              return 'image/bmp';
 206          }
 207          elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
 208          {
 209              return 'image/vnd.microsoft.icon';
 210          }
 211          else
 212          {
 213              return $this->text_or_binary();
 214          }
 215      }
 216  
 217      /**
 218       * Sniff images
 219       *
 220       * @return string Actual Content-Type
 221       */
 222  	public function image()
 223      {
 224          if (substr($this->file->body, 0, 6) === 'GIF87a'
 225              || substr($this->file->body, 0, 6) === 'GIF89a')
 226          {
 227              return 'image/gif';
 228          }
 229          elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
 230          {
 231              return 'image/png';
 232          }
 233          elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
 234          {
 235              return 'image/jpeg';
 236          }
 237          elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
 238          {
 239              return 'image/bmp';
 240          }
 241          elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
 242          {
 243              return 'image/vnd.microsoft.icon';
 244          }
 245          else
 246          {
 247              return false;
 248          }
 249      }
 250  
 251      /**
 252       * Sniff HTML
 253       *
 254       * @return string Actual Content-Type
 255       */
 256  	public function feed_or_html()
 257      {
 258          $len = strlen($this->file->body);
 259          $pos = strspn($this->file->body, "\x09\x0A\x0D\x20");
 260  
 261          while ($pos < $len)
 262          {
 263              switch ($this->file->body[$pos])
 264              {
 265                  case "\x09":
 266                  case "\x0A":
 267                  case "\x0D":
 268                  case "\x20":
 269                      $pos += strspn($this->file->body, "\x09\x0A\x0D\x20", $pos);
 270                      continue 2;
 271  
 272                  case '<':
 273                      $pos++;
 274                      break;
 275  
 276                  default:
 277                      return 'text/html';
 278              }
 279  
 280              if (substr($this->file->body, $pos, 3) === '!--')
 281              {
 282                  $pos += 3;
 283                  if ($pos < $len && ($pos = strpos($this->file->body, '-->', $pos)) !== false)
 284                  {
 285                      $pos += 3;
 286                  }
 287                  else
 288                  {
 289                      return 'text/html';
 290                  }
 291              }
 292              elseif (substr($this->file->body, $pos, 1) === '!')
 293              {
 294                  if ($pos < $len && ($pos = strpos($this->file->body, '>', $pos)) !== false)
 295                  {
 296                      $pos++;
 297                  }
 298                  else
 299                  {
 300                      return 'text/html';
 301                  }
 302              }
 303              elseif (substr($this->file->body, $pos, 1) === '?')
 304              {
 305                  if ($pos < $len && ($pos = strpos($this->file->body, '?>', $pos)) !== false)
 306                  {
 307                      $pos += 2;
 308                  }
 309                  else
 310                  {
 311                      return 'text/html';
 312                  }
 313              }
 314              elseif (substr($this->file->body, $pos, 3) === 'rss'
 315                  || substr($this->file->body, $pos, 7) === 'rdf:RDF')
 316              {
 317                  return 'application/rss+xml';
 318              }
 319              elseif (substr($this->file->body, $pos, 4) === 'feed')
 320              {
 321                  return 'application/atom+xml';
 322              }
 323              else
 324              {
 325                  return 'text/html';
 326              }
 327          }
 328  
 329          return 'text/html';
 330      }
 331  }
 332