正则表达式从PHP imap的电子邮件正文中提取base64编码的部分

Question

I have the following sting below, It's an e-mail body and I want to extract only the base64 encoded files from it in PHP. I was thinking I could use regex to just extract the base64 parts so I could then decode them eg

preg_match('/Content-Transfer-Encoding: base64\s(.*)\sContent-Type:/', $message['body'], $matches);

echo base64_decode($matches[0]);

However I'm not getting any matches as I don't think my regex is working. Ideally I want to capture each part which starts after 'Content-Transfer-Encoding:' and ends with another 'Content-Type:' part starting. My question is, how do I regex all the base64 parts? eg

Content-Transfer-Encoding : (capture this part as a match) Content-Type:

Below is part of the message and the full string can be found here:

http://pastebin.com/A5XXnSaT

--_004_D16F6E4A2986D34F9D752E3564EAC46F359618EFAPP1197ghakfplc_ Content-Type: multipart/alternative; boundary="_000_D16F6E4A2986D34F9D752E3564EAC46F359618EFAPP1197ghakfplc_" --_000_D16F6E4A2986D34F9D752E3564EAC46F359618EFAPP1197ghakfplc_ Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 SGksIFBsZWFzZSBmaW5kIHRoZSBhdHRhY2hlZCBQRlMgZXJyb3IgUmVwb3J0DQoKLS0tLS0tLS0t LQpCJlEgcGxjClJlZ2lzdGVyZWQgT2ZmaWNlOiBCJlEgSG91c2UsIENoZXN0bnV0IEF2ZW51ZSwg Q2hhbmRsZXJzIEZvcmQsIEVhc3RsZWlnaCwgSGFtcHNoaXJlLCBTTzUzIDNMRQpCdXkgT25saW5l IE5PVyBhdCB3d3cuZGl5LmNvbSBvciBmb2xsb3cgQiZRIG9uIEZhY2Vib29rIHd3dy5mYWNlYm9v...

Answer 1

Outputs 6 decoded parts

$result=[];
preg_match_all('/Content-Transfer-Encoding: base64\s(.*?)\s--/', $message['body'], $matches);

foreach ($matches[1] as $base) {
    $result[] = base64_decode($base);
}

print_r($result);

Example: https://eval.in/438478