How to decode/inflate a chunked gzip string?

After making a gzip deflate request in PHP, I receive the deflated string in offset chunks, which looks like the following

Example shortened greatly to show format:

00001B4E
¾”kŒj…Øæ’ìÑ«F1ìÊ`+ƒQì¹UÜjùJƒZ\µy¡ÓUžGr‡J&=KLËÙÍ~=ÍkR
0000102F
ñÞœÞôÎ‘üo[¾”+’Ñ8#à»0±R-4VÕ’n›êˆÍ.MCŽ…ÏÖr¿3M—èßñ°r¡\+
00000000

I'm unable to inflate that presumably because of the chunked format. I can confirm the data is not corrupt after manually removing the offsets with a Hex editor and reading the gzip archive. I'm wondering if there's a proper method to parse this chunked gzip deflated response into a readable string?

I might be able to split these offsets and join the data together in one string to call gzinflate, but it seems there must be an easier way.

Solution

The proper method to deflate a chunked response is roughly as follows:

initialise string to hold result
for each chunk {
  check that the stated chunk length equals the string length of the chunk
  append the chunk data to the result variable
}

Here's a handy PHP function to do that for you (FIXED):

function unchunk_string ($str) {

  // A string to hold the result
  $result = '';

  // Split input by CRLF
  $parts = explode("\r\n", $str);

  // These vars track the current chunk
  $chunkLen = 0;
  $thisChunk = '';

  // Loop the data
  while (($part = array_shift($parts)) !== NULL) {
    if ($chunkLen) {
      // Add the data to the string
      // Don't forget, the data might contain a literal CRLF
      $thisChunk .= $part."\r\n";
      if (strlen($thisChunk) == $chunkLen) {
        // Chunk is complete
        $result .= $thisChunk;
        $chunkLen = 0;
        $thisChunk = '';
      } else if (strlen($thisChunk) == $chunkLen + 2) {
        // Chunk is complete, remove trailing CRLF
        $result .= substr($thisChunk, 0, -2);
        $chunkLen = 0;
        $thisChunk = '';
      } else if (strlen($thisChunk) > $chunkLen) {
        // Data is malformed
        return FALSE;
      }
    } else {
      // If we are not in a chunk, get length of the new one
      if ($part === '') continue;
      if (!$chunkLen = hexdec($part)) break;
    }
  }

  // Return the decoded data of FALSE if it is incomplete
  return ($chunkLen) ? FALSE : $result;

}