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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) 2004-2016, Ryan Parman, Sam 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   * @copyright 2004-2016 Ryan Parman, Sam Sneddon, Ryan McCue
  37   * @author Ryan Parman
  38   * @author Sam Sneddon
  39   * @author Ryan McCue
  40   * @link http://simplepie.org/ SimplePie
  41   * @license http://www.opensource.org/licenses/bsd-license.php BSD License
  42   */
  43  
  44  
  45  /**
  46   * Content-type sniffing
  47   *
  48   * Based on the rules in http://tools.ietf.org/html/draft-abarth-mime-sniff-06
  49   *
  50   * This is used since we can't always trust Content-Type headers, and is based
  51   * upon the HTML5 parsing rules.
  52   *
  53   *
  54   * This class can be overloaded with {@see SimplePie::set_content_type_sniffer_class()}
  55   *
  56   * @package SimplePie
  57   * @subpackage HTTP
  58   */
  59  class SimplePie_Content_Type_Sniffer
  60  {
  61      /**
  62       * File object
  63       *
  64       * @var SimplePie_File
  65       */
  66      var $file;
  67  
  68      /**
  69       * Create an instance of the class with the input file
  70       *
  71       * @param SimplePie_Content_Type_Sniffer $file Input file
  72       */
  73  	public function __construct($file)
  74      {
  75          $this->file = $file;
  76      }
  77  
  78      /**
  79       * Get the Content-Type of the specified file
  80       *
  81       * @return string Actual Content-Type
  82       */
  83  	public function get_type()
  84      {
  85          if (isset($this->file->headers['content-type']))
  86          {
  87              if (!isset($this->file->headers['content-encoding'])
  88                  && ($this->file->headers['content-type'] === 'text/plain'
  89                      || $this->file->headers['content-type'] === 'text/plain; charset=ISO-8859-1'
  90                      || $this->file->headers['content-type'] === 'text/plain; charset=iso-8859-1'
  91                      || $this->file->headers['content-type'] === 'text/plain; charset=UTF-8'))
  92              {
  93                  return $this->text_or_binary();
  94              }
  95  
  96              if (($pos = strpos($this->file->headers['content-type'], ';')) !== false)
  97              {
  98                  $official = substr($this->file->headers['content-type'], 0, $pos);
  99              }
 100              else
 101              {
 102                  $official = $this->file->headers['content-type'];
 103              }
 104              $official = trim(strtolower($official));
 105  
 106              if ($official === 'unknown/unknown'
 107                  || $official === 'application/unknown')
 108              {
 109                  return $this->unknown();
 110              }
 111              elseif (substr($official, -4) === '+xml'
 112                  || $official === 'text/xml'
 113                  || $official === 'application/xml')
 114              {
 115                  return $official;
 116              }
 117              elseif (substr($official, 0, 6) === 'image/')
 118              {
 119                  if ($return = $this->image())
 120                  {
 121                      return $return;
 122                  }
 123  
 124                  return $official;
 125              }
 126              elseif ($official === 'text/html')
 127              {
 128                  return $this->feed_or_html();
 129              }
 130  
 131              return $official;
 132          }
 133  
 134          return $this->unknown();
 135      }
 136  
 137      /**
 138       * Sniff text or binary
 139       *
 140       * @return string Actual Content-Type
 141       */
 142  	public function text_or_binary()
 143      {
 144          if (substr($this->file->body, 0, 2) === "\xFE\xFF"
 145              || substr($this->file->body, 0, 2) === "\xFF\xFE"
 146              || substr($this->file->body, 0, 4) === "\x00\x00\xFE\xFF"
 147              || substr($this->file->body, 0, 3) === "\xEF\xBB\xBF")
 148          {
 149              return 'text/plain';
 150          }
 151          elseif (preg_match('/[\x00-\x08\x0E-\x1A\x1C-\x1F]/', $this->file->body))
 152          {
 153              return 'application/octet-stream';
 154          }
 155  
 156          return 'text/plain';
 157      }
 158  
 159      /**
 160       * Sniff unknown
 161       *
 162       * @return string Actual Content-Type
 163       */
 164  	public function unknown()
 165      {
 166          $ws = strspn($this->file->body, "\x09\x0A\x0B\x0C\x0D\x20");
 167          if (strtolower(substr($this->file->body, $ws, 14)) === '<!doctype html'
 168              || strtolower(substr($this->file->body, $ws, 5)) === '<html'
 169              || strtolower(substr($this->file->body, $ws, 7)) === '<script')
 170          {
 171              return 'text/html';
 172          }
 173          elseif (substr($this->file->body, 0, 5) === '%PDF-')
 174          {
 175              return 'application/pdf';
 176          }
 177          elseif (substr($this->file->body, 0, 11) === '%!PS-Adobe-')
 178          {
 179              return 'application/postscript';
 180          }
 181          elseif (substr($this->file->body, 0, 6) === 'GIF87a'
 182              || substr($this->file->body, 0, 6) === 'GIF89a')
 183          {
 184              return 'image/gif';
 185          }
 186          elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
 187          {
 188              return 'image/png';
 189          }
 190          elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
 191          {
 192              return 'image/jpeg';
 193          }
 194          elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
 195          {
 196              return 'image/bmp';
 197          }
 198          elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
 199          {
 200              return 'image/vnd.microsoft.icon';
 201          }
 202  
 203          return $this->text_or_binary();
 204      }
 205  
 206      /**
 207       * Sniff images
 208       *
 209       * @return string Actual Content-Type
 210       */
 211  	public function image()
 212      {
 213          if (substr($this->file->body, 0, 6) === 'GIF87a'
 214              || substr($this->file->body, 0, 6) === 'GIF89a')
 215          {
 216              return 'image/gif';
 217          }
 218          elseif (substr($this->file->body, 0, 8) === "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A")
 219          {
 220              return 'image/png';
 221          }
 222          elseif (substr($this->file->body, 0, 3) === "\xFF\xD8\xFF")
 223          {
 224              return 'image/jpeg';
 225          }
 226          elseif (substr($this->file->body, 0, 2) === "\x42\x4D")
 227          {
 228              return 'image/bmp';
 229          }
 230          elseif (substr($this->file->body, 0, 4) === "\x00\x00\x01\x00")
 231          {
 232              return 'image/vnd.microsoft.icon';
 233          }
 234  
 235          return false;
 236      }
 237  
 238      /**
 239       * Sniff HTML
 240       *
 241       * @return string Actual Content-Type
 242       */
 243  	public function feed_or_html()
 244      {
 245          $len = strlen($this->file->body);
 246          $pos = strspn($this->file->body, "\x09\x0A\x0D\x20\xEF\xBB\xBF");
 247  
 248          while ($pos < $len)
 249          {
 250              switch ($this->file->body[$pos])
 251              {
 252                  case "\x09":
 253                  case "\x0A":
 254                  case "\x0D":
 255                  case "\x20":
 256                      $pos += strspn($this->file->body, "\x09\x0A\x0D\x20", $pos);
 257                      continue 2;
 258  
 259                  case '<':
 260                      $pos++;
 261                      break;
 262  
 263                  default:
 264                      return 'text/html';
 265              }
 266  
 267              if (substr($this->file->body, $pos, 3) === '!--')
 268              {
 269                  $pos += 3;
 270                  if ($pos < $len && ($pos = strpos($this->file->body, '-->', $pos)) !== false)
 271                  {
 272                      $pos += 3;
 273                  }
 274                  else
 275                  {
 276                      return 'text/html';
 277                  }
 278              }
 279              elseif (substr($this->file->body, $pos, 1) === '!')
 280              {
 281                  if ($pos < $len && ($pos = strpos($this->file->body, '>', $pos)) !== false)
 282                  {
 283                      $pos++;
 284                  }
 285                  else
 286                  {
 287                      return 'text/html';
 288                  }
 289              }
 290              elseif (substr($this->file->body, $pos, 1) === '?')
 291              {
 292                  if ($pos < $len && ($pos = strpos($this->file->body, '?>', $pos)) !== false)
 293                  {
 294                      $pos += 2;
 295                  }
 296                  else
 297                  {
 298                      return 'text/html';
 299                  }
 300              }
 301              elseif (substr($this->file->body, $pos, 3) === 'rss'
 302                  || substr($this->file->body, $pos, 7) === 'rdf:RDF')
 303              {
 304                  return 'application/rss+xml';
 305              }
 306              elseif (substr($this->file->body, $pos, 4) === 'feed')
 307              {
 308                  return 'application/atom+xml';
 309              }
 310              else
 311              {
 312                  return 'text/html';
 313              }
 314          }
 315  
 316          return 'text/html';
 317      }
 318  }