Different behavior between mg_http_reply() and mg_printf()

[MalcolmGillott]

I am testing some code and would like to understand the difference in behavior in these two calls.
I have created some REST API code, and in one scenario, I am handling an invalid request to my API

If I use
mg_http_reply(c, 404, "", "", "")
to respond to a bad request, then my API behaves how I expect

If I use
mg_printf(c,"HTTP/1.1 404 Not Found\r\nContent-Length: 0 \r\n\r\n");
which generates the same reply, Mongoose will not fire another MG_EV_HTTP_MSG event until the connection is closed and re-opened.

Plainly I can use mg_http_reply() as my solution, but I would like to understand what is going on

Thanks
Malc

[scaprile]

Please read https://mongoose.ws/documentation/#best-practices

Long story short: use mg_http_reply() or chunked encoding (mg_http_...chunk()). Those functions set Content-Length and c->is_respfor you. If you use mg_printf() or mg_send() instead, don't forget to set Content-Length and c->is_resp yourself

Please follow the guidelines in the documentation, examples and tutorials available.