Checking "Magic Bytes" or Mime Types in PHP?
So, I've currently used a few different methods to check the mime type. The user uploads a file using a form, I grab the mime type, if it's application/zip, I allow it, if it's anything else, I deny it. The issue is that something (browsers I assume) is changing the mime type to "application/octet-stream"
I'm wondering how else I can verify a file is .zip upon form upload.
Code:
$name = strtolower(end(explode('.', $filename)));
$accepted_types = array('application/zip', 'application/x-zip-compressed', 'multipart/x-zip', 'application/x-compressed');
foreach($accepted_types as $good_type) {
if($good_type == $type) {
$okay = true;
break;
} else {
$okay = false;
}
}
使用mime-content-type。
$type = mime_content_type($filename);
FWIW, you can get the magic bytes using bin2hex . According to Wikipedia (https://en.m.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files), zips have the first 2 hex bytes 50 4B
$zip=file_get_contents("somefile.zip");
echo strtoupper (substr(bin2hex($zip),0,2)); //504B