LDAP server and user authentication on third party http service (not LDAP)?

Question

LDAP

There is a task to raise an LDAP server (samba 4 for example), but it is necessary to authenticate the user (compare a pair of username and password) on a third-party service using the http protocol.
1) the user enters his login and password into the application that is configured for LDAP
2) LDAP - the server ensures that the login is in its database, and the login and password match in the http service and returns true if successful.
Thoughts arise to somehow modify the authentication algorithm on the LDAP server and return true if a third-party service returned true. How to do it?

Answer 1

1) an LDAP server is set ( 1 , 2 , 3 ), users are created
2) a request is made to the ldap server in the application