1<?php
2/**
3 * HTTP API: WP_Http_Encoding class
4 *
5 * @package WordPress
6 * @subpackage HTTP
7 * @since 4.4.0
8 */
9
10/**
11 * Core class used to implement deflate and gzip transfer encoding support for HTTP requests.
12 *
13 * Includes RFC 1950, RFC 1951, and RFC 1952.
14 *
15 * @since 2.8.0
16 */
17#[AllowDynamicProperties]
18class WP_Http_Encoding {
19
20 /**
21 * Compress raw string using the deflate format.
22 *
23 * Supports the RFC 1951 standard.
24 *
25 * @since 2.8.0
26 *
27 * @param string $raw String to compress.
28 * @param int $level Optional. Compression level, 9 is highest. Default 9.
29 * @param string $supports Optional, not used. When implemented it will choose
30 * the right compression based on what the server supports.
31 * @return string|false Compressed string on success, false on failure.
32 */
33 public static function compress( $raw, $level = 9, $supports = null ) {
34 return gzdeflate( $raw, $level );
35 }
36
37 /**
38 * Decompression of deflated string.
39 *
40 * Will attempt to decompress using the RFC 1950 standard, and if that fails
41 * then the RFC 1951 standard deflate will be attempted. Finally, the RFC
42 * 1952 standard gzip decode will be attempted. If all fail, then the
43 * original compressed string will be returned.
44 *
45 * @since 2.8.0
46 *
47 * @param string $compressed String to decompress.
48 * @param int $length The optional length of the compressed data.
49 * @return string|false Decompressed string on success, false on failure.
50 */
51 public static function decompress( $compressed, $length = null ) {
52
53 if ( empty( $compressed ) ) {
54 return $compressed;
55 }
56
57 $decompressed = @gzinflate( $compressed );
58 if ( false !== $decompressed ) {
59 return $decompressed;
60 }
61
62 $decompressed = self::compatible_gzinflate( $compressed );
63 if ( false !== $decompressed ) {
64 return $decompressed;
65 }
66
67 $decompressed = @gzuncompress( $compressed );
68 if ( false !== $decompressed ) {
69 return $decompressed;
70 }
71
72 if ( function_exists( 'gzdecode' ) ) {
73 $decompressed = @gzdecode( $compressed );
74
75 if ( false !== $decompressed ) {
76 return $decompressed;
77 }
78 }
79
80 return $compressed;
81 }
82
83 /**
84 * Decompression of deflated string while staying compatible with the majority of servers.
85 *
86 * Certain Servers will return deflated data with headers which PHP's gzinflate()
87 * function cannot handle out of the box. The following function has been created from
88 * various snippets on the gzinflate() PHP documentation.
89 *
90 * Warning: Magic numbers within. Due to the potential different formats that the compressed
91 * data may be returned in, some "magic offsets" are needed to ensure proper decompression
92 * takes place. For a simple pragmatic way to determine the magic offset in use, see:
93 * https://core.trac.wordpress.org/ticket/18273
94 *
95 * @since 2.8.1
96 *
97 * @link https://core.trac.wordpress.org/ticket/18273
98 * @link https://www.php.net/manual/en/function.gzinflate.php#70875
99 * @link https://www.php.net/manual/en/function.gzinflate.php#77336
100 *
101 * @param string $gz_data String to decompress.
102 * @return string|false Decompressed string on success, false on failure.
103 */
104 public static function compatible_gzinflate( $gz_data ) {
105
106 // Compressed data might contain a full header, if so strip it for gzinflate().
107 if ( str_starts_with( $gz_data, "\x1f\x8b\x08" ) ) {
108 $i = 10;
109 $flg = ord( substr( $gz_data, 3, 1 ) );
110 if ( $flg > 0 ) {
111 if ( $flg & 4 ) {
112 list($xlen) = unpack( 'v', substr( $gz_data, $i, 2 ) );
113 $i = $i + 2 + $xlen;
114 }
115 if ( $flg & 8 ) {
116 $i = strpos( $gz_data, "\0", $i ) + 1;
117 }
118 if ( $flg & 16 ) {
119 $i = strpos( $gz_data, "\0", $i ) + 1;
120 }
121 if ( $flg & 2 ) {
122 $i = $i + 2;
123 }
124 }
125 $decompressed = @gzinflate( substr( $gz_data, $i, -8 ) );
126 if ( false !== $decompressed ) {
127 return $decompressed;
128 }
129 }
130
131 // Compressed data from java.util.zip.Deflater amongst others.
132 $decompressed = @gzinflate( substr( $gz_data, 2 ) );
133 if ( false !== $decompressed ) {
134 return $decompressed;
135 }
136
137 return false;
138 }
139
140 /**
141 * What encoding types to accept and their priority values.
142 *
143 * @since 2.8.0
144 *
145 * @param string $url
146 * @param array $args
147 * @return string Types of encoding to accept.
148 */
149 public static function accept_encoding( $url, $args ) {
150 $type = array();
151 $compression_enabled = self::is_available();
152
153 if ( ! $args['decompress'] ) { // Decompression specifically disabled.
154 $compression_enabled = false;
155 } elseif ( $args['stream'] ) { // Disable when streaming to file.
156 $compression_enabled = false;
157 } elseif ( isset( $args['limit_response_size'] ) ) { // If only partial content is being requested, we won't be able to decompress it.
158 $compression_enabled = false;
159 }
160
161 if ( $compression_enabled ) {
162 if ( function_exists( 'gzinflate' ) ) {
163 $type[] = 'deflate;q=1.0';
164 }
165
166 if ( function_exists( 'gzuncompress' ) ) {
167 $type[] = 'compress;q=0.5';
168 }
169
170 if ( function_exists( 'gzdecode' ) ) {
171 $type[] = 'gzip;q=0.5';
172 }
173 }
174
175 /**
176 * Filters the allowed encoding types.
177 *
178 * @since 3.6.0
179 *
180 * @param string[] $type Array of what encoding types to accept and their priority values.
181 * @param string $url URL of the HTTP request.
182 * @param array $args HTTP request arguments.
183 */
184 $type = apply_filters( 'wp_http_accept_encoding', $type, $url, $args );
185
186 return implode( ', ', $type );
187 }
188
189 /**
190 * What encoding the content used when it was compressed to send in the headers.
191 *
192 * @since 2.8.0
193 *
194 * @return string Content-Encoding string to send in the header.
195 */
196 public static function content_encoding() {
197 return 'deflate';
198 }
199
200 /**
201 * Whether the content be decoded based on the headers.
202 *
203 * @since 2.8.0
204 *
205 * @param array|string $headers All of the available headers.
206 * @return bool
207 */
208 public static function should_decode( $headers ) {
209 if ( is_array( $headers ) ) {
210 if ( array_key_exists( 'content-encoding', $headers ) && ! empty( $headers['content-encoding'] ) ) {
211 return true;
212 }
213 } elseif ( is_string( $headers ) ) {
214 return ( stripos( $headers, 'content-encoding:' ) !== false );
215 }
216
217 return false;
218 }
219
220 /**
221 * Whether decompression and compression are supported by the PHP version.
222 *
223 * Each function is tested instead of checking for the zlib extension, to
224 * ensure that the functions all exist in the PHP version and aren't
225 * disabled.
226 *
227 * @since 2.8.0
228 *
229 * @return bool
230 */
231 public static function is_available() {
232 return ( function_exists( 'gzuncompress' ) || function_exists( 'gzdeflate' ) || function_exists( 'gzinflate' ) );
233 }
234}
235