1<?php
2
3// SPDX-FileCopyrightText: 2004-2023 Ryan Parman, Sam Sneddon, Ryan McCue
4// SPDX-License-Identifier: BSD-3-Clause
5
6declare(strict_types=1);
7
8namespace SimplePie;
9
10/**
11 * Decode 'gzip' encoded HTTP data
12 *
13 * @link http://www.gzip.org/format.txt
14 * @link https://www.php.net/manual/en/function.gzdecode.php
15 * @deprecated since SimplePie 1.9.0, use `gzdecode` function instead.
16 */
17class Gzdecode
18{
19 /**
20 * Compressed data
21 *
22 * @access private
23 * @var string
24 * @see gzdecode::$data
25 */
26 public $compressed_data;
27
28 /**
29 * Size of compressed data
30 *
31 * @access private
32 * @var int
33 */
34 public $compressed_size;
35
36 /**
37 * Minimum size of a valid gzip string
38 *
39 * @access private
40 * @var int
41 */
42 public $min_compressed_size = 18;
43
44 /**
45 * Current position of pointer
46 *
47 * @access private
48 * @var int
49 */
50 public $position = 0;
51
52 /**
53 * Flags (FLG)
54 *
55 * @access private
56 * @var int
57 */
58 public $flags;
59
60 /**
61 * Uncompressed data
62 *
63 * @access public
64 * @see gzdecode::$compressed_data
65 * @var string
66 */
67 public $data;
68
69 /**
70 * Modified time
71 *
72 * @access public
73 * @var int
74 */
75 public $MTIME;
76
77 /**
78 * Extra Flags
79 *
80 * @access public
81 * @var int
82 */
83 public $XFL;
84
85 /**
86 * Operating System
87 *
88 * @access public
89 * @var int
90 */
91 public $OS;
92
93 /**
94 * Subfield ID 1
95 *
96 * @access public
97 * @see gzdecode::$extra_field
98 * @see gzdecode::$SI2
99 * @var string
100 */
101 public $SI1;
102
103 /**
104 * Subfield ID 2
105 *
106 * @access public
107 * @see gzdecode::$extra_field
108 * @see gzdecode::$SI1
109 * @var string
110 */
111 public $SI2;
112
113 /**
114 * Extra field content
115 *
116 * @access public
117 * @see gzdecode::$SI1
118 * @see gzdecode::$SI2
119 * @var string
120 */
121 public $extra_field;
122
123 /**
124 * Original filename
125 *
126 * @access public
127 * @var string
128 */
129 public $filename;
130
131 /**
132 * Human readable comment
133 *
134 * @access public
135 * @var string
136 */
137 public $comment;
138
139 /**
140 * Don't allow anything to be set
141 *
142 * @param string $name
143 * @param mixed $value
144 */
145 public function __set(string $name, $value)
146 {
147 throw new Exception("Cannot write property $name");
148 }
149
150 /**
151 * Set the compressed string and related properties
152 *
153 * @param string $data
154 */
155 public function __construct(string $data)
156 {
157 $this->compressed_data = $data;
158 $this->compressed_size = strlen($data);
159 }
160
161 /**
162 * Decode the GZIP stream
163 *
164 * @return bool Successfulness
165 */
166 public function parse()
167 {
168 if ($this->compressed_size >= $this->min_compressed_size) {
169 $len = 0;
170
171 // Check ID1, ID2, and CM
172 if (substr($this->compressed_data, 0, 3) !== "\x1F\x8B\x08") {
173 return false;
174 }
175
176 // Get the FLG (FLaGs)
177 $this->flags = ord($this->compressed_data[3]);
178
179 // FLG bits above (1 << 4) are reserved
180 if ($this->flags > 0x1F) {
181 return false;
182 }
183
184 // Advance the pointer after the above
185 $this->position += 4;
186
187 // MTIME
188 $mtime = substr($this->compressed_data, $this->position, 4);
189 // Reverse the string if we're on a big-endian arch because l is the only signed long and is machine endianness
190 if (current((array) unpack('S', "\x00\x01")) === 1) {
191 $mtime = strrev($mtime);
192 }
193 $this->MTIME = current((array) unpack('l', $mtime));
194 $this->position += 4;
195
196 // Get the XFL (eXtra FLags)
197 $this->XFL = ord($this->compressed_data[$this->position++]);
198
199 // Get the OS (Operating System)
200 $this->OS = ord($this->compressed_data[$this->position++]);
201
202 // Parse the FEXTRA
203 if ($this->flags & 4) {
204 // Read subfield IDs
205 $this->SI1 = $this->compressed_data[$this->position++];
206 $this->SI2 = $this->compressed_data[$this->position++];
207
208 // SI2 set to zero is reserved for future use
209 if ($this->SI2 === "\x00") {
210 return false;
211 }
212
213 // Get the length of the extra field
214 $len = current((array) unpack('v', substr($this->compressed_data, $this->position, 2)));
215 $this->position += 2;
216
217 // Check the length of the string is still valid
218 $this->min_compressed_size += $len + 4;
219 if ($this->compressed_size >= $this->min_compressed_size) {
220 // Set the extra field to the given data
221 $this->extra_field = substr($this->compressed_data, $this->position, $len);
222 $this->position += $len;
223 } else {
224 return false;
225 }
226 }
227
228 // Parse the FNAME
229 if ($this->flags & 8) {
230 // Get the length of the filename
231 $len = strcspn($this->compressed_data, "\x00", $this->position);
232
233 // Check the length of the string is still valid
234 $this->min_compressed_size += $len + 1;
235 if ($this->compressed_size >= $this->min_compressed_size) {
236 // Set the original filename to the given string
237 $this->filename = substr($this->compressed_data, $this->position, $len);
238 $this->position += $len + 1;
239 } else {
240 return false;
241 }
242 }
243
244 // Parse the FCOMMENT
245 if ($this->flags & 16) {
246 // Get the length of the comment
247 $len = strcspn($this->compressed_data, "\x00", $this->position);
248
249 // Check the length of the string is still valid
250 $this->min_compressed_size += $len + 1;
251 if ($this->compressed_size >= $this->min_compressed_size) {
252 // Set the original comment to the given string
253 $this->comment = substr($this->compressed_data, $this->position, $len);
254 $this->position += $len + 1;
255 } else {
256 return false;
257 }
258 }
259
260 // Parse the FHCRC
261 if ($this->flags & 2) {
262 // Check the length of the string is still valid
263 $this->min_compressed_size += $len + 2;
264 if ($this->compressed_size >= $this->min_compressed_size) {
265 // Read the CRC
266 $crc = current((array) unpack('v', substr($this->compressed_data, $this->position, 2)));
267
268 // Check the CRC matches
269 if ((crc32(substr($this->compressed_data, 0, $this->position)) & 0xFFFF) === $crc) {
270 $this->position += 2;
271 } else {
272 return false;
273 }
274 } else {
275 return false;
276 }
277 }
278
279 // Decompress the actual data
280 if (($data = gzinflate(substr($this->compressed_data, $this->position, -8))) === false) {
281 return false;
282 }
283
284 $this->data = $data;
285 $this->position = $this->compressed_size - 8;
286
287 // Check CRC of data
288 $crc = current((array) unpack('V', substr($this->compressed_data, $this->position, 4)));
289 $this->position += 4;
290 /*if (extension_loaded('hash') && sprintf('%u', current(unpack('V', hash('crc32b', $this->data)))) !== sprintf('%u', $crc))
291 {
292 return false;
293 }*/
294
295 // Check ISIZE of data
296 $isize = current((array) unpack('V', substr($this->compressed_data, $this->position, 4)));
297 $this->position += 4;
298 if (sprintf('%u', strlen($this->data) & 0xFFFFFFFF) !== sprintf('%u', $isize)) {
299 return false;
300 }
301
302 // Wow, against all odds, we've actually got a valid gzip string
303 return true;
304 }
305
306 return false;
307 }
308}
309
310class_alias('SimplePie\Gzdecode', 'SimplePie_gzdecode');
311