How to determine file type?

Question

Programming

It is necessary to divide the files into 2 parts - doc and docx. Mimetype in tests showed
docx

application/vnd.openxmlformats-officedocument.wordprocessingml.document

doc
application/msword
How can I reliably determine the type of a file - by mime, extension, or both? Or in another way
Purposes:
Files of site users are in the cloud. I will convert Docx to html, doc has its own logic.
mysql, laravel 5.8, php 7.3 Ubuntu VPS

Answer 1

Define both at the same time, in case of differences, give preference to the MIME definition.