Although we can set a close callback on HTTP connection, but the HTTP server is not notified if client close unexpetedly, such as CTRL+C.
evhttp_connection_set_closecb(req->evcon, on_close, NULL);
Because libevent called bufferevent_disable(evon, EV_READ) to stop read on the connection, so the server would not know the client close by read() returns 0, or send() causes SIGPIPE.
All you need to is to re-enable EV_READ on that connection:
struct bufferevent *bev = evhttp_connection_get_bufferevent(req->evcon); bufferevent_enable(bev, EV_READ);
