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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) 2004-2009, 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-dev | |
37 | * @copyright 2004-2010 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 | * @todo phpDoc comments | |
44 | */ | |
45 | ||
46 | ||
47 | /** | |
48 | * gzdecode | |
49 | * | |
50 | * @package SimplePie | |
51 | */ | |
52 | class SimplePie_gzdecode | |
53 | { | |
54 | /** | |
55 | * Compressed data | |
56 | * | |
57 | * @access private | |
58 | * @see gzdecode::$data | |
59 | */ | |
60 | var $compressed_data; | |
61 | ||
62 | /** | |
63 | * Size of compressed data | |
64 | * | |
65 | * @access private | |
66 | */ | |
67 | var $compressed_size; | |
68 | ||
69 | /** | |
70 | * Minimum size of a valid gzip string | |
71 | * | |
72 | * @access private | |
73 | */ | |
74 | var $min_compressed_size = 18; | |
75 | ||
76 | /** | |
77 | * Current position of pointer | |
78 | * | |
79 | * @access private | |
80 | */ | |
81 | var $position = 0; | |
82 | ||
83 | /** | |
84 | * Flags (FLG) | |
85 | * | |
86 | * @access private | |
87 | */ | |
88 | var $flags; | |
89 | ||
90 | /** | |
91 | * Uncompressed data | |
92 | * | |
93 | * @access public | |
94 | * @see gzdecode::$compressed_data | |
95 | */ | |
96 | var $data; | |
97 | ||
98 | /** | |
99 | * Modified time | |
100 | * | |
101 | * @access public | |
102 | */ | |
103 | var $MTIME; | |
104 | ||
105 | /** | |
106 | * Extra Flags | |
107 | * | |
108 | * @access public | |
109 | */ | |
110 | var $XFL; | |
111 | ||
112 | /** | |
113 | * Operating System | |
114 | * | |
115 | * @access public | |
116 | */ | |
117 | var $OS; | |
118 | ||
119 | /** | |
120 | * Subfield ID 1 | |
121 | * | |
122 | * @access public | |
123 | * @see gzdecode::$extra_field | |
124 | * @see gzdecode::$SI2 | |
125 | */ | |
126 | var $SI1; | |
127 | ||
128 | /** | |
129 | * Subfield ID 2 | |
130 | * | |
131 | * @access public | |
132 | * @see gzdecode::$extra_field | |
133 | * @see gzdecode::$SI1 | |
134 | */ | |
135 | var $SI2; | |
136 | ||
137 | /** | |
138 | * Extra field content | |
139 | * | |
140 | * @access public | |
141 | * @see gzdecode::$SI1 | |
142 | * @see gzdecode::$SI2 | |
143 | */ | |
144 | var $extra_field; | |
145 | ||
146 | /** | |
147 | * Original filename | |
148 | * | |
149 | * @access public | |
150 | */ | |
151 | var $filename; | |
152 | ||
153 | /** | |
154 | * Human readable comment | |
155 | * | |
156 | * @access public | |
157 | */ | |
158 | var $comment; | |
159 | ||
160 | /** | |
161 | * Don't allow anything to be set | |
162 | * | |
163 | * @access public | |
164 | */ | |
165 | public function __set($name, $value) | |
166 | { | |
167 | trigger_error("Cannot write property $name", E_USER_ERROR); | |
168 | } | |
169 | ||
170 | /** | |
171 | * Set the compressed string and related properties | |
172 | * | |
173 | * @access public | |
174 | */ | |
175 | public function __construct($data) | |
176 | { | |
177 | $this->compressed_data = $data; | |
178 | $this->compressed_size = strlen($data); | |
179 | } | |
180 | ||
181 | /** | |
182 | * Decode the GZIP stream | |
183 | * | |
184 | * @access public | |
185 | */ | |
186 | public function parse() | |
187 | { | |
188 | if ($this->compressed_size >= $this->min_compressed_size) | |
189 | { | |
190 | // Check ID1, ID2, and CM | |
191 | if (substr($this->compressed_data, 0, 3) !== "\x1F\x8B\x08") | |
192 | { | |
193 | return false; | |
194 | } | |
195 | ||
196 | // Get the FLG (FLaGs) | |
197 | $this->flags = ord($this->compressed_data[3]); | |
198 | ||
199 | // FLG bits above (1 << 4) are reserved | |
200 | if ($this->flags > 0x1F) | |
201 | { | |
202 | return false; | |
203 | } | |
204 | ||
205 | // Advance the pointer after the above | |
206 | $this->position += 4; | |
207 | ||
208 | // MTIME | |
209 | $mtime = substr($this->compressed_data, $this->position, 4); | |
210 | // Reverse the string if we're on a big-endian arch because l is the only signed long and is machine endianness | |
211 | if (current(unpack('S', "\x00\x01")) === 1) | |
212 | { | |
213 | $mtime = strrev($mtime); | |
214 | } | |
215 | $this->MTIME = current(unpack('l', $mtime)); | |
216 | $this->position += 4; | |
217 | ||
218 | // Get the XFL (eXtra FLags) | |
219 | $this->XFL = ord($this->compressed_data[$this->position++]); | |
220 | ||
221 | // Get the OS (Operating System) | |
222 | $this->OS = ord($this->compressed_data[$this->position++]); | |
223 | ||
224 | // Parse the FEXTRA | |
225 | if ($this->flags & 4) | |
226 | { | |
227 | // Read subfield IDs | |
228 | $this->SI1 = $this->compressed_data[$this->position++]; | |
229 | $this->SI2 = $this->compressed_data[$this->position++]; | |
230 | ||
231 | // SI2 set to zero is reserved for future use | |
232 | if ($this->SI2 === "\x00") | |
233 | { | |
234 | return false; | |
235 | } | |
236 | ||
237 | // Get the length of the extra field | |
238 | $len = current(unpack('v', substr($this->compressed_data, $this->position, 2))); | |
239 | $this->position += 2; | |
240 | ||
241 | // Check the length of the string is still valid | |
242 | $this->min_compressed_size += $len + 4; | |
243 | if ($this->compressed_size >= $this->min_compressed_size) | |
244 | { | |
245 | // Set the extra field to the given data | |
246 | $this->extra_field = substr($this->compressed_data, $this->position, $len); | |
247 | $this->position += $len; | |
248 | } | |
249 | else | |
250 | { | |
251 | return false; | |
252 | } | |
253 | } | |
254 | ||
255 | // Parse the FNAME | |
256 | if ($this->flags & 8) | |
257 | { | |
258 | // Get the length of the filename | |
259 | $len = strcspn($this->compressed_data, "\x00", $this->position); | |
260 | ||
261 | // Check the length of the string is still valid | |
262 | $this->min_compressed_size += $len + 1; | |
263 | if ($this->compressed_size >= $this->min_compressed_size) | |
264 | { | |
265 | // Set the original filename to the given string | |
266 | $this->filename = substr($this->compressed_data, $this->position, $len); | |
267 | $this->position += $len + 1; | |
268 | } | |
269 | else | |
270 | { | |
271 | return false; | |
272 | } | |
273 | } | |
274 | ||
275 | // Parse the FCOMMENT | |
276 | if ($this->flags & 16) | |
277 | { | |
278 | // Get the length of the comment | |
279 | $len = strcspn($this->compressed_data, "\x00", $this->position); | |
280 | ||
281 | // Check the length of the string is still valid | |
282 | $this->min_compressed_size += $len + 1; | |
283 | if ($this->compressed_size >= $this->min_compressed_size) | |
284 | { | |
285 | // Set the original comment to the given string | |
286 | $this->comment = substr($this->compressed_data, $this->position, $len); | |
287 | $this->position += $len + 1; | |
288 | } | |
289 | else | |
290 | { | |
291 | return false; | |
292 | } | |
293 | } | |
294 | ||
295 | // Parse the FHCRC | |
296 | if ($this->flags & 2) | |
297 | { | |
298 | // Check the length of the string is still valid | |
299 | $this->min_compressed_size += $len + 2; | |
300 | if ($this->compressed_size >= $this->min_compressed_size) | |
301 | { | |
302 | // Read the CRC | |
303 | $crc = current(unpack('v', substr($this->compressed_data, $this->position, 2))); | |
304 | ||
305 | // Check the CRC matches | |
306 | if ((crc32(substr($this->compressed_data, 0, $this->position)) & 0xFFFF) === $crc) | |
307 | { | |
308 | $this->position += 2; | |
309 | } | |
310 | else | |
311 | { | |
312 | return false; | |
313 | } | |
314 | } | |
315 | else | |
316 | { | |
317 | return false; | |
318 | } | |
319 | } | |
320 | ||
321 | // Decompress the actual data | |
322 | if (($this->data = gzinflate(substr($this->compressed_data, $this->position, -8))) === false) | |
323 | { | |
324 | return false; | |
325 | } | |
326 | else | |
327 | { | |
328 | $this->position = $this->compressed_size - 8; | |
329 | } | |
330 | ||
331 | // Check CRC of data | |
332 | $crc = current(unpack('V', substr($this->compressed_data, $this->position, 4))); | |
333 | $this->position += 4; | |
334 | /*if (extension_loaded('hash') && sprintf('%u', current(unpack('V', hash('crc32b', $this->data)))) !== sprintf('%u', $crc)) | |
335 | { | |
336 | return false; | |
337 | }*/ | |
338 | ||
339 | // Check ISIZE of data | |
340 | $isize = current(unpack('V', substr($this->compressed_data, $this->position, 4))); | |
341 | $this->position += 4; | |
342 | if (sprintf('%u', strlen($this->data) & 0xFFFFFFFF) !== sprintf('%u', $isize)) | |
343 | { | |
344 | return false; | |
345 | } | |
346 | ||
347 | // Wow, against all odds, we've actually got a valid gzip string | |
348 | return true; | |
349 | } | |
350 | else | |
351 | { | |
352 | return false; | |
353 | } | |
354 | } | |
355 | } |