php file upload, how to restrict file upload type

Question

I have the following code to check if (resume and reference letter uploaded match desired type (pdf OR doc OR docx) and size (less than 400 kb)

//check file          


        

Answer 1

To do that I usually using something like that:

$filename = $_FILES['field_name']['name']; // Get the name of the file (including file extension).
$ext = strtolower(substr($filename, strpos($filename,'.'), strlen($filename)-1)); //get the extention in lower case

And than check if the file extension is accepted.

Also be aware that that the user can simply change the extension for a dangerous file, so it is safer to check with the mime type

Answer 2

Here is some code I wrote in the past..

function checkFileExtension($ext)
{
    if ($ext == 'ai' || $ext == 'pdf' || $ext == 'jpg' || $ext == 'jpeg' || $ext ==
        'gif' || $ext == 'eps' || $ext == 'tif' || $ext == 'png' || $ext == 'xls' || $ext ==
        'xlsx' || $ext == 'doc' || $ext == 'docx' || $ext == 'ppt' || $ext == 'pptx' ||
        $ext == 'zip' || $ext == 'rar' || $ext == 'sitx' || $ext == 'psd' || $ext ==
        'indd' || $ext == 'dng') {
        $pass = (int)1;
    } else {
        $pass = (int)0;
    }
    return (int)$pass;
}


$ext = substr(strrchr($_FILES['file']['name'], "."), 1);
$fileAccepted = checkFileExtension($ext);
$fileSize = $_FILES['file']['size'];

if($fileAccepted==1 && $fileSize > '82428800'){
    // do stuff
}

Answer 3

The Mime type for docx is application/vnd.openxmlformatsofficedocument.wordprocessingml.document

Answer 4

This may be useful:

First check desired mime types to verify:

Microsoft Office MIME Types and List of MIME Types

Then try make your code easier...

    $mimeTypes = array('application/vnd.openxmlformats-officedocument.wordprocessingml.document', 
'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet', 
'application/vnd.openxmlformats-officedocument.presentationml.presentation');

    if (in_array($_FILES["resume"]["type"], $mimeTypes))
    {
        // File's OK
    }
    else
    {
        // Bad file !
    }

Important: User may change file extension, so always check the mime type intead of extension!! =)

Answer 5

The below just uses the mime types to validate a file, then checks the size of both. For a list of most mime types see here or google.

function allowed_file(){

//Add the allowed mime-type files to an 'allowed' array 
 $allowed = array('application/doc', 'application/pdf', 'another/type');

//Check uploaded file type is in the above array (therefore valid)  
    if(in_array($_FILES['resume']['type'], $allowed) AND in_array($_FILES['reference']['type'], $allowed)){

   //If filetypes allowed types are found, continue to check filesize:

  if($_FILES["resume"]["size"] < 400000 AND $_FILES["reference"]["size"] < 400000 ){

    //if both files are below given size limit, allow upload
    //Begin filemove here....

    }

    }

}