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