After reading the source code available in "ngx_mail_auth_http_module.c"

trying to figure out how to make a "basic TCP connection" to

a backend server, nothing seems clear. I didn't find any simple pattern

to read/write on a TCP socket, even if there are simple call like

ngx_event_connect_peer() or ngx_close_connection() for connection phase

and ngx_send|recv / ngx_unix_send|recv / send|recv for reading and writing on a socket.

How can I setup a basic TCP socket into my handler which will connect / send / recv and then

close the connection ?