PHP server as a relay?

Question

PHP

Task : Transfer the client file through server A to server B preferably as quickly as possible.
Restrictions : The client file is transferred via POST and PUT methods.
It is clear that, as an option, we upload the file to server A, and then this server sends the file to server B. But here we lose in speed, and server resources are wasted. I would like a solution that is similar in efficiency to directly sending a file to a client with the readfile function ( habrahabr.ru/post/151795).
UPD: It is not possible to install custom modules on the server

Answer 1

mod_proxy connect: folder to the IP of server B.