Allow only upload specific file type

[relacja]

The issue is more related to the R2 itself, but perhaps someone has advice on how to validate the file type in a secure environment?

Passing ContentType in PutObjectCommand doesn't work.

Currently, anyone from the client side can send a malware file with any header, and it will be correctly uploaded via presigned url.

At the moment, presigned URLs don't support POST methods, and R2 doesn't have Bucket Policies.