authenticate ftp users from sql database in c++ - c++

Question

i have a messaging app written in c++ (qt) and now i want to add a library to move heavy media via ftp to a ftp server and give the link to other user to download it.
the problem is there are to many users to create separate ftp accounts for all of them manually and using one account for all of them isn't safe.i want to limit every users access to their own subdirectory and delete that dir and ftp account if the users deletes account.
i think the following approaches makes sense:
1)in ftp server check login credentials submitted with ftp.login(user,password) in server with existing users in a sql database (users are added to database with signup and deleted with delete account)
2)adding a proxy server to check authorization to access ftp server and then give access to ftp server subdirectory
3)manually writing a ftp daemon for server with c++ or qt library and listen to a port
4)if there is a way to automatically add ftp user to ftp server when signing up
if there is another way i'd appreciate the help and if you have an idea how to implement one of the above please explain in detail
i tried to find a module in C++ to help build ftp server app but couldn't find any.

Answer 1

i found a way.pureFTPD is a ftp daemon that lets u use a sql database to validate ftp users and limit their access.