5.x PHPMailer.php

public PHPMailer::DKIM_HeaderC($signHeader)

Generate a DKIM canonicalization header. Uses the 'relaxed' algorithm from RFC6376 section 3.4.2. Canonicalized headers should *always* use CRLF, regardless of mailer setting.

Parameters

string $signHeader Header:

Return value

string

See also

https://tools.ietf.org/html/rfc6376#section-3.4.2

File

inc/PHPMailer/src/PHPMailer.php, line 4351

Class

PHPMailer

PHPMailer - PHP email creation and transport class.

Namespace

PHPMailer\PHPMailer

Code

public function DKIM_HeaderC($signHeader) 
 {
  //Unfold all header continuation lines
  //Also collapses folded whitespace.
  //Note PCRE \s is too broad a definition of whitespace; RFC5322 defines it as `[ \t]`
  //@see https://tools.ietf.org/html/rfc5322#section-2.2
  //That means this may break if you do something daft like put vertical tabs in your headers.
  $signHeader = preg_replace('/\r\n[ \t]+/', ' ', $signHeader);
  $lines = explode("\r\n", $signHeader);
  foreach ($lines as $key => $line) {
    //If the header is missing a :, skip it as it's invalid
    //This is likely to happen because the explode() above will also split
    //on the trailing LE, leaving an empty line
    if (strpos($line, ':') === false) {
      continue;
    }
    list($heading, $value) = explode(':', $line, 2);
    //Lower-case header name
    $heading = strtolower($heading);
    //Collapse white space within the value
    $value = preg_replace('/[ \t]{2,}/', ' ', $value);
    //RFC6376 is slightly unclear here - it says to delete space at the *end* of each value
    //But then says to delete space before and after the colon.
    //Net result is the same as trimming both ends of the value.
    //by elimination, the same applies to the field name
    $lines [$key] = trim($heading, " \t") . ':' . trim($value, " \t");
  }

  return implode("\r\n", $lines);
}