Wrong MIME-Type for uploaded ZIP files

Question

How do I handle MIME-Type validation of an uploaded ZIP file in both Linux and Windows environments?

I created a testing purposes ZIP file and downloaded another one (first Google result) and use them as arguments of the following code:

$finfo = new finfo( FILEINFO_MIME );

echo $finfo -> file( 'benchmark.zip' ), '<br />', $finfo -> file( 'css3menu.zip' ), '<br />';

echo mime_content_type( 'benchmark.zip' ), '<br />', mime_content_type( 'css3menu.zip' );

It reported me:

application/zip; charset=binary
application/zip; charset=binary
application/zip
application/zip

In both environments, Linux, using Apache, and Windows, with PHP built-in webserver.

After reading this answer I also considered application/octet-stream as valid so I added them both to my Upload Handler.

But the upload failed, reporting me invalid file type :(

I checked everything and it was correct, so I decided to isolate the problem with the most basic upload implementation possible (together with that debugging code):

if( isset( $_POST['button'] ) ) {

    print '<pre>'; print_r( $_FILES );

    $finfo = new finfo( FILEINFO_MIME );

    echo $finfo -> file( 'benchmark.zip' ), '<br />', $finfo -> file( 'css3menu.zip' ), '<br />';

    echo mime_content_type( 'benchmark.zip' ), '<br />', mime_content_type( 'css3menu.zip' ), '<br />';
}

?>

<form enctype="multipart/form-data" action="http://localhost/test.php" method="post">

<input type="file" name="file[]" id="file" />

<input type="submit" name="button" value="Send" />

</form>

The MIME-Type reported by FileInfo and mime_content_type() were the same as before, but the type index in $_FILES returned application/vnd.zend.serverconfig in Linux environment and the less desirable, although valid, application/octet-stream in Windows.

Any ideas of why this is happening?

One thing that worth to mention is I'm new in Linux environment so I didn't know how to setup a webserver so, at first, I installed Zend Server but later I uninstalled it completelly and reinstall everything manually using apt-get.

Answer 1

After understanding that the type index is provided by the browser and not by PHP I tested in Google Chrome and got the correct application/zip

So I Google'd how to fix this issue in Firefox, the browser I was testing before, and all I needed to do was delete the mimeTypes.rdf file in the profile folder located in ~/.mozilla/firefox/