Libevent2 Server HTTP callback inside get client side IP, port, fd wait

Write this is mainly to prevent forgetting, fast memory.
Libevent2 Server HTTP callback inside get client side IP, port, FD, etc., in http_internal.h file, struct evhttp_connection inside
, you can directly save the struct evhttp *request inside the HTTP callback, as long as the evhttp_send_reply () client file descriptor is not closed in the callback, and the HTTP callback is not released after the end of the call. Evhttp_send is invoked to invoke Evhttp_write_buffer only when the evhttp_send_reply is invoked. into the buffer. When the data is sent from the buffer, the Evhttp_send_done is invoked, and then the Evhttp_request_free is called, which is released