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 * Decode 'gzip' encoded HTTP data
48 *
49 * @package SimplePie
50 * @subpackage HTTP
51 * @link http://www.gzip.org/format.txt
52 */
53 class SimplePie_gzdecode
54 {
55 /**
56 * Compressed data
57 *
58 * @access private
59 * @var string
60 * @see gzdecode::$data
61 */
62 var $compressed_data;
63
64 /**
65 * Size of compressed data
66 *
67 * @access private
68 * @var int
69 */
70 var $compressed_size;
71
72 /**
73 * Minimum size of a valid gzip string
74 *
75 * @access private
76 * @var int
77 */
78 var $min_compressed_size = 18;
79
80 /**
81 * Current position of pointer
82 *
83 * @access private
84 * @var int
85 */
86 var $position = 0;
87
88 /**
89 * Flags (FLG)
90 *
91 * @access private
92 * @var int
93 */
94 var $flags;
95
96 /**
97 * Uncompressed data
98 *
99 * @access public
100 * @see gzdecode::$compressed_data
101 * @var string
102 */
103 var $data;
104
105 /**
106 * Modified time
107 *
108 * @access public
109 * @var int
110 */
111 var $MTIME;
112
113 /**
114 * Extra Flags
115 *
116 * @access public
117 * @var int
118 */
119 var $XFL;
120
121 /**
122 * Operating System
123 *
124 * @access public
125 * @var int
126 */
127 var $OS;
128
129 /**
130 * Subfield ID 1
131 *
132 * @access public
133 * @see gzdecode::$extra_field
134 * @see gzdecode::$SI2
135 * @var string
136 */
137 var $SI1;
138
139 /**
140 * Subfield ID 2
141 *
142 * @access public
143 * @see gzdecode::$extra_field
144 * @see gzdecode::$SI1
145 * @var string
146 */
147 var $SI2;
148
149 /**
150 * Extra field content
151 *
152 * @access public
153 * @see gzdecode::$SI1
154 * @see gzdecode::$SI2
155 * @var string
156 */
157 var $extra_field;
158
159 /**
160 * Original filename
161 *
162 * @access public
163 * @var string
164 */
165 var $filename;
166
167 /**
168 * Human readable comment
169 *
170 * @access public
171 * @var string
172 */
173 var $comment;
174
175 /**
176 * Don't allow anything to be set
177 *
178 * @param string $name
179 * @param mixed $value
180 */
181 public function __set($name, $value)
182 {
183 trigger_error("Cannot write property $name", E_USER_ERROR);
184 }
185
186 /**
187 * Set the compressed string and related properties
188 *
189 * @param string $data
190 */
191 public function __construct($data)
192 {
193 $this->compressed_data = $data;
194 $this->compressed_size = strlen($data);
195 }
196
197 /**
198 * Decode the GZIP stream
199 *
200 * @return bool Successfulness
201 */
202 public function parse()
203 {
204 if ($this->compressed_size >= $this->min_compressed_size)
205 {
206 // Check ID1, ID2, and CM
207 if (substr($this->compressed_data, 0, 3) !== "\x1F\x8B\x08")
208 {
209 return false;
210 }
211
212 // Get the FLG (FLaGs)
213 $this->flags = ord($this->compressed_data[3]);
214
215 // FLG bits above (1 << 4) are reserved
216 if ($this->flags > 0x1F)
217 {
218 return false;
219 }
220
221 // Advance the pointer after the above
222 $this->position += 4;
223
224 // MTIME
225 $mtime = substr($this->compressed_data, $this->position, 4);
226 // Reverse the string if we're on a big-endian arch because l is the only signed long and is machine endianness
227 if (current(unpack('S', "\x00\x01")) === 1)
228 {
229 $mtime = strrev($mtime);
230 }
231 $this->MTIME = current(unpack('l', $mtime));
232 $this->position += 4;
233
234 // Get the XFL (eXtra FLags)
235 $this->XFL = ord($this->compressed_data[$this->position++]);
236
237 // Get the OS (Operating System)
238 $this->OS = ord($this->compressed_data[$this->position++]);
239
240 // Parse the FEXTRA
241 if ($this->flags & 4)
242 {
243 // Read subfield IDs
244 $this->SI1 = $this->compressed_data[$this->position++];
245 $this->SI2 = $this->compressed_data[$this->position++];
246
247 // SI2 set to zero is reserved for future use
248 if ($this->SI2 === "\x00")
249 {
250 return false;
251 }
252
253 // Get the length of the extra field
254 $len = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
255 $this->position += 2;
256
257 // Check the length of the string is still valid
258 $this->min_compressed_size += $len + 4;
259 if ($this->compressed_size >= $this->min_compressed_size)
260 {
261 // Set the extra field to the given data
262 $this->extra_field = substr($this->compressed_data, $this->position, $len);
263 $this->position += $len;
264 }
265 else
266 {
267 return false;
268 }
269 }
270
271 // Parse the FNAME
272 if ($this->flags & 8)
273 {
274 // Get the length of the filename
275 $len = strcspn($this->compressed_data, "\x00", $this->position);
276
277 // Check the length of the string is still valid
278 $this->min_compressed_size += $len + 1;
279 if ($this->compressed_size >= $this->min_compressed_size)
280 {
281 // Set the original filename to the given string
282 $this->filename = substr($this->compressed_data, $this->position, $len);
283 $this->position += $len + 1;
284 }
285 else
286 {
287 return false;
288 }
289 }
290
291 // Parse the FCOMMENT
292 if ($this->flags & 16)
293 {
294 // Get the length of the comment
295 $len = strcspn($this->compressed_data, "\x00", $this->position);
296
297 // Check the length of the string is still valid
298 $this->min_compressed_size += $len + 1;
299 if ($this->compressed_size >= $this->min_compressed_size)
300 {
301 // Set the original comment to the given string
302 $this->comment = substr($this->compressed_data, $this->position, $len);
303 $this->position += $len + 1;
304 }
305 else
306 {
307 return false;
308 }
309 }
310
311 // Parse the FHCRC
312 if ($this->flags & 2)
313 {
314 // Check the length of the string is still valid
315 $this->min_compressed_size += $len + 2;
316 if ($this->compressed_size >= $this->min_compressed_size)
317 {
318 // Read the CRC
319 $crc = current(unpack('v', substr($this->compressed_data, $this->position, 2)));
320
321 // Check the CRC matches
322 if ((crc32(substr($this->compressed_data, 0, $this->position)) & 0xFFFF) === $crc)
323 {
324 $this->position += 2;
325 }
326 else
327 {
328 return false;
329 }
330 }
331 else
332 {
333 return false;
334 }
335 }
336
337 // Decompress the actual data
338 if (($this->data = gzinflate(substr($this->compressed_data, $this->position, -8))) === false)
339 {
340 return false;
341 }
342 else
343 {
344 $this->position = $this->compressed_size - 8;
345 }
346
347 // Check CRC of data
348 $crc = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
349 $this->position += 4;
350 /*if (extension_loaded('hash') && sprintf('%u', current(unpack('V', hash('crc32b', $this->data)))) !== sprintf('%u', $crc))
351 {
352 return false;
353 }*/
354
355 // Check ISIZE of data
356 $isize = current(unpack('V', substr($this->compressed_data, $this->position, 4)));
357 $this->position += 4;
358 if (sprintf('%u', strlen($this->data) & 0xFFFFFFFF) !== sprintf('%u', $isize))
359 {
360 return false;
361 }
362
363 // Wow, against all odds, we've actually got a valid gzip string
364 return true;
365 }
366 else
367 {
368 return false;
369 }
370 }
371 }
372