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 */
59class 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}
319