string * * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string. */ public static function decompress($data) { if (is_string($data) === false) { throw InvalidArgument::create(1, '$data', 'string', gettype($data)); } if (trim($data) === '') { // Empty body does not need further processing. return $data; } $marker = substr($data, 0, 2); if (!isset(self::$magic_compression_headers[$marker])) { // Not actually compressed. Probably cURL ruining this for us. return $data; } if (function_exists('gzdecode')) { $decoded = @gzdecode($data); if ($decoded !== false) { return $decoded; } } if (function_exists('gzinflate')) { $decoded = @gzinflate($data); if ($decoded !== false) { return $decoded; } } $decoded = self::compatible_gzinflate($data); if ($decoded !== false) { return $decoded; } if (function_exists('gzuncompress')) { $decoded = @gzuncompress($data); if ($decoded !== false) { return $decoded; } } return $data; } /** * Decompression of deflated string while staying compatible with the majority of servers. * * Certain Servers will return deflated data with headers which PHP's gzinflate() * function cannot handle out of the box. The following function has been created from * various snippets on the gzinflate() PHP documentation. * * Warning: Magic numbers within. Due to the potential different formats that the compressed * data may be returned in, some "magic offsets" are needed to ensure proper decompression * takes place. For a simple progmatic way to determine the magic offset in use, see: * https://core.trac.wordpress.org/ticket/18273 * * @since 1.6.0 * @link https://core.trac.wordpress.org/ticket/18273 * @link https://www.php.net/gzinflate#70875 * @link https://www.php.net/gzinflate#77336 * * @param string $gz_data String to decompress. * @return string|bool False on failure. * * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string. */ public static function compatible_gzinflate($gz_data) { if (is_string($gz_data) === false) { throw InvalidArgument::create(1, '$gz_data', 'string', gettype($gz_data)); } if (trim($gz_data) === '') { return false; } // Compressed data might contain a full zlib header, if so strip it for // gzinflate() if (substr($gz_data, 0, 3) === "\x1f\x8b\x08") { $i = 10; $flg = ord(substr($gz_data, 3, 1)); if ($flg > 0) { if ($flg & 4) { list($xlen) = unpack('v', substr($gz_data, $i, 2)); $i += 2 + $xlen; } if ($flg & 8) { $i = strpos($gz_data, "\0", $i) + 1; } if ($flg & 16) { $i = strpos($gz_data, "\0", $i) + 1; } if ($flg & 2) { $i += 2; } } $decompressed = self::compatible_gzinflate(substr($gz_data, $i)); if ($decompressed !== false) { return $decompressed; } } // If the data is Huffman Encoded, we must first strip the leading 2 // byte Huffman marker for gzinflate() // The response is Huffman coded by many compressors such as // java.util.zip.Deflater, Ruby's Zlib::Deflate, and .NET's // System.IO.Compression.DeflateStream. // // See https://decompres.blogspot.com/ for a quick explanation of this // data type $huffman_encoded = false; // low nibble of first byte should be 0x08 list(, $first_nibble) = unpack('h', $gz_data); // First 2 bytes should be divisible by 0x1F list(, $first_two_bytes) = unpack('n', $gz_data); if ($first_nibble === 0x08 && ($first_two_bytes % 0x1F) === 0) { $huffman_encoded = true; } if ($huffman_encoded) { $decompressed = @gzinflate(substr($gz_data, 2)); if ($decompressed !== false) { return $decompressed; } } if (substr($gz_data, 0, 4) === "\x50\x4b\x03\x04") { // ZIP file format header // Offset 6: 2 bytes, General-purpose field // Offset 26: 2 bytes, filename length // Offset 28: 2 bytes, optional field length // Offset 30: Filename field, followed by optional field, followed // immediately by data list(, $general_purpose_flag) = unpack('v', substr($gz_data, 6, 2)); // If the file has been compressed on the fly, 0x08 bit is set of // the general purpose field. We can use this to differentiate // between a compressed document, and a ZIP file $zip_compressed_on_the_fly = ((0x08 & $general_purpose_flag) === 0x08); if (!$zip_compressed_on_the_fly) { // Don't attempt to decode a compressed zip file return $gz_data; } // Determine the first byte of data, based on the above ZIP header // offsets: $first_file_start = array_sum(unpack('v2', substr($gz_data, 26, 4))); $decompressed = @gzinflate(substr($gz_data, 30 + $first_file_start)); if ($decompressed !== false) { return $decompressed; } return false; } // Finally fall back to straight gzinflate $decompressed = @gzinflate($gz_data); if ($decompressed !== false) { return $decompressed; } // Fallback for all above failing, not expected, but included for // debugging and preventing regressions and to track stats $decompressed = @gzinflate(substr($gz_data, 2)); if ($decompressed !== false) { return $decompressed; } return false; } }