Hi, I would like to have the auth_request fastcgi auth server to send some custom variables to the fastcgi back-end server. For example, the Radius server returned some parameters which the fastcgi auth server needs to send to the fastcgi back-end server.

locate / {
auth_request /auth;
fastcgi_pass <back-end server>; <--- would like this server to see the custom param variable
}

locate /auth {
fastcgi_param CUSTOM_PARAM custom_param;
fastcgi_pass <auth server>; <---- returns a custom param value to be used by the back-end server
}

Could someone give me a pointer on how to this in the nginx.conf and the auth and back-end servers in C? I saw many examples for PHP but none for C.
In the auth server app, I defined "int custom_param=100" for example, and would like the back-end server to see get this variable and value. Thanks!