Parsing headers, with focus on Content-* headers

parsing_headers.php

<?php
/**
 * Parsing headers with code adapted from the user contributed notes at
 * http://php.net/manual/en/function.http-parse-headers.php
 * 
 * @author Hugo Wetterberg, Good Old
 */

/*
// Sample usage
$headers = 'content-type: text/html; charset="UTF-8"; format=flowed'."\r\n".
  'Content-disposition: attachment; filename="Hello \"World.txt"' . "\r\n".
  "Server: Funky/1.0\r\n".
  "Set-Cookie: foo=bar\r\n".
  "Set-Cookie: baz=quux\r\n".
  "Folded: works\r\n\ttoo\r\n";
$ph = parse_headers($headers);

print "Headers: \n";
print $headers;

print "\nBecomes: \n";
print_r($ph);
//*/

function parse_headers($header) {
  $retVal = array();
  $fields = explode("\r\n", preg_replace('/\x0D\x0A[\x09\x20]+/', ' ', $header));
  foreach( $fields as $field ) {
    if( preg_match('/([^:]+): (.+)/m', $field, $match) ) {
      $match[1] = preg_replace('/(?<=^|[\x09\x20\x2D])./e', 'strtoupper("\0")', strtolower(trim($match[1])));
      if( isset($retVal[$match[1]]) ) {
        $retVal[$match[1]] = array($retVal[$match[1]], $match[2]);
      } else {
        $retVal[$match[1]] = trim($match[2]);
      }
    }
  }
  
  foreach ($retVal as $name => $value) {
    switch ($name) {
      case 'Content-Disposition':
      case 'Content-Type':
        $retVal[$name] = parse_content_header_value($value);
        break;
    }
  }
  
  return $retVal;
}

function parse_content_header_value($value) {
  $retVal = array();
  $value_pattern = '/^([^;]+)(;\s*(.+)\s*)?$/';
  $param_pattern = '/([a-z]+)=(([^\"][^;]+)|(\"(\\\"|[^"])+\"))/';
  $vm=array();
  
  if (preg_match($value_pattern, $value, $vm)) {
    $retVal['value'] = $vm[1];
    if (count($vm)>2) {
      $pm = array();
      if (preg_match_all($param_pattern, $vm[3], $pm)) {
        $pcount = count($pm[0]);
        for ($i=0; $i<$pcount; $i++) {
          $value = $pm[2][$i];
          if (substr($value, 0, 1) == '"') {
            $value = stripcslashes(substr($value, 1, mb_strlen($value)-2));
          }
          $retVal['params'][$pm[1][$i]] = $value;
        }
      }
    }
  }

  return $retVal;
}

sample_output.txt

Headers: 
content-type: text/html; charset="UTF-8"; format=flowed 
Content-disposition: attachment; filename="Hello \"World.txt" 
Server: Funky/1.0 
Set-Cookie: foo=bar 
Set-Cookie: baz=quux 
Folded: works 
	too 

Becomes: 
Array
(
    [Content-Type] => Array
        (
            [value] => text/html
            [params] => Array
                (
                    [charset] => UTF-8
                    [format] => flowed
                )

        )

    [Content-Disposition] => Array
        (
            [value] => attachment
            [params] => Array
                (
                    [filename] => Hello "World.txt
                )

        )

    [Server] => Funky/1.0
    [Set-Cookie] => Array
        (
            [0] => foo=bar
            [1] => baz=quux
        )

    [Folded] => works too
)