5.x PHPMailer.php

public PHPMailer::encodeHeader($str, $position = 'text')

Encode a header value (not including its label) optimally. Picks shortest of Q, B, or none. Result includes folding if needed. See RFC822 definitions for phrase, comment and text positions.

Parameters

string $str The header value to encode:

string $position What context the string will be used in:

Return value

string

File

inc/PHPMailer/src/PHPMailer.php, line 3105

Class

PHPMailer

PHPMailer - PHP email creation and transport class.

Namespace

PHPMailer\PHPMailer

Code

public function encodeHeader($str, $position = 'text') 
 {
  $matchcount = 0;
  switch (strtolower($position)) {
    case 'phrase':
      if (!preg_match('/[\200-\377]/', $str)) {
        // Can't use addslashes as we don't know the value of magic_quotes_sybase
        $encoded = addcslashes($str, "\0..\37\177\\\"");
        if (($str == $encoded) and !preg_match('/[^A-Za-z0-9!#$%&\'*+\/=?^_`{|}~ -]/', $str)) {
          return $encoded;
        }

        return "\"$encoded\"";
      }
      $matchcount = preg_match_all('/[^\040\041\043-\133\135-\176]/', $str, $matches);
      break;
      /* @noinspection PhpMissingBreakStatementInspection */
    case 'comment':
      $matchcount = preg_match_all('/[()"]/', $str, $matches);
      //fallthrough
    case 'text':
    default:
      $matchcount += preg_match_all('/[\000-\010\013\014\016-\037\177-\377]/', $str, $matches);
      break;
  }

  //RFCs specify a maximum line length of 78 chars, however mail() will sometimes
  //corrupt messages with headers longer than 65 chars. See #818
  $lengthsub = 'mail' == $this->Mailer ? 13 : 0;
  $maxlen = static::STD_LINE_LENGTH - $lengthsub;
  // Try to select the encoding which should produce the shortest output
  if ($matchcount > strlen($str) / 3) {
    // More than a third of the content will need encoding, so B encoding will be most efficient
    $encoding = 'B';
    //This calculation is:
    // max line length
    // - shorten to avoid mail() corruption
    // - Q/B encoding char overhead ("` =?<charset>?[QB]?<content>?=`")
    // - charset name length
    $maxlen = static::STD_LINE_LENGTH - $lengthsub - 8 - strlen($this->CharSet);
    if ($this->hasMultiBytes($str)) {
      // Use a custom function which correctly encodes and wraps long
      // multibyte strings without breaking lines within a character
      $encoded = $this->base64EncodeWrapMB($str, "\n");
    }
    else {
      $encoded = base64_encode($str);
      $maxlen -= $maxlen % 4;
      $encoded = trim(chunk_split($encoded, $maxlen, "\n"));
    }
    $encoded = preg_replace('/^(.*)$/m', ' =?' . $this->CharSet . "?$encoding?\\1?=", $encoded);
  }
  elseif ($matchcount > 0) {
    //1 or more chars need encoding, use Q-encode
    $encoding = 'Q';
    //Recalc max line length for Q encoding - see comments on B encode
    $maxlen = static::STD_LINE_LENGTH - $lengthsub - 8 - strlen($this->CharSet);
    $encoded = $this->encodeQ($str, $position);
    $encoded = $this->wrapText($encoded, $maxlen, true);
    $encoded = str_replace('=' . static::$LE, "\n", trim($encoded));
    $encoded = preg_replace('/^(.*)$/m', ' =?' . $this->CharSet . "?$encoding?\\1?=", $encoded);
  }
  elseif (strlen($str) > $maxlen) {
    //No chars need encoding, but line is too long, so fold it
    $encoded = trim($this->wrapText($str, $maxlen, false));
    if ($str == $encoded) {
      //Wrapping nicely didn't work, wrap hard instead
      $encoded = trim(chunk_split($str, static::STD_LINE_LENGTH, static::$LE));
    }
    $encoded = str_replace(static::$LE, "\n", trim($encoded));
    $encoded = preg_replace('/^(.*)$/m', ' \\1', $encoded);
  }
  else {
    //No reformatting needed
    return $str;
  }

  return trim(static::normalizeBreaks($encoded));
}