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In this article, I will show you a cool tip on how to properly validate the file MIME types even if they change the extension of the file.
I will cover the following in this article
finfo
)Basic knowledge on PHP. Even if you don't know how to upload the files and handle it then I have written an article on it:
This is very basic HTML form make sure you have enctype="multipart/form-data"
<form action="store_product.php" method="post" enctype="multipart/form-data">
<div>
<input type="file" name="product_invoice" id="product_invoice">
</div> <br>
<div>
<input type="submit" value="Create Product">
</div>
</form>
From the above form when you select the image and upload it will go to store_product.php
PHP file which will handle the file upload with validation.
Following is the snippet code which demonstrates the file validation
/** Store the file details in variable */
$product_invoice = $_FILES['product_invoice'];
/** Uploaded file name */
$file_name = $product_invoice['name'];
$file_tmp = $product_invoice['tmp_name'];
/** Using pathinfo() to get the file extension of file */
$pathinfo = pathinfo($file_name);
$extension = $pathinfo['extension'];
/** Allowed extensions */
$file_extensions = ['pdf', 'xls', 'jpeg', 'jpg', 'png', 'svg', 'webp'];
/** Check File extensions */
if(!in_array($extensio
n, $file_extensions)){
$errors[] = 'File allowed extensions '. implode(', ', $file_extensions);
}
The above is wrong because we are validating based on file extension. Because someone may upload video & change just the extension to jpeg or pdf.
finfo
)To properly validate the file MIME you need to use finfo
which internally uses finfo_open
Basically you use it the following way
/** Using finfo to just get the MIME type */
$finfo = new finfo(FILEINFO_MIME_TYPE);
/** You will get extension along with the mime types */
$extension = $finfo->file($file_tmp);
Full detailed on the same as follows
/** Store the file details in variable */
$product_invoice = $_FILES['product_invoice'];
/** Uploaded file name */
$file_name = $product_invoice['name'];
$file_tmp = $product_invoice['tmp_name'];
/** Allowed MIME extensions */
$file_extensions = ['image/jpeg', 'image/pjpeg', 'application/pdf'];
/** Using finfo to just get the MIME type */
$finfo = new finfo(FILEINFO_MIME_TYPE);
/** You will get extension along with the mime types */
$extension = $finfo->file($file_tmp);
/** Check File extensions */
if(!in_array($extension, $file_extensions)){
$errors[] = 'File allowed extensions '. implode(', ', $file_extensions);
}
I don't want to reinvent the wheel. So here is the link for the CODEIGNITER FRAMEWORK MIME TYPES
Hope you liked the article. If yes then please do share with your friends.
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