Reading an email's subject in Unicode out of an IMAP server - php

Question

I'm using Zend Framework 1's IMAP server connector and I'm trying to fetch an email from server with Unicode characters in its subject. Here's how I do it:
$message = $imapServer->getMessage($message_number);
echo $message->getHeader('subject');
The problem is that it comes out encoded:
=?UTF-8?B?2KjYp9uM?=
I can find the encoding function within Zend_Mail class named _encodeHeader but I can not find the decoding pair! Does anyone know how to decode this string?
And here's the encoder function:
protected function _encodeHeader($value)
{
if (Zend_Mime::isPrintable($value) === false) {
if ($this->getHeaderEncoding() === Zend_Mime::ENCODING_QUOTEDPRINTABLE) {
$value = Zend_Mime::encodeQuotedPrintableHeader($value, $this->getCharset(), Zend_Mime::LINELENGTH, Zend_Mime::LINEEND);
} else {
$value = Zend_Mime::encodeBase64Header($value, $this->getCharset(), Zend_Mime::LINELENGTH, Zend_Mime::LINEEND);
}
}
return $value;
}

Answer 1

Search for a "RFC2047 decoder" and pick one of the existing libraries which does just that. If nothing is usable, roll your own.

Answer 2

Here's how I solved it:
switch (strtolower($encoding)) {
case \Zend_Mime::ENCODING_QUOTEDPRINTABLE:
if (preg_match('/^\s?=\?([^\?]+)\?Q\?/', $str, $matches) === 1) {
$str = preg_replace('/\s?=\?'.preg_quote($matches[1]).'\?Q\?/', ' ', $str);
$str = strtr($str, array('?=' => ''));
$str = trim($str);
}
return \Zend_Mime_Decode::decodeQuotedPrintable($str);
case \Zend_Mime::ENCODING_BASE64:
return base64_decode($encodedText);
case \Zend_Mime::ENCODING_7BIT:
case \Zend_Mime::ENCODING_8BIT:
default:
return $encodedText;
}