error ngx_http_send_header

[Maxim Dounin]

Hello!

On Wed, May 16, 2018 at 01:05:50PM -0700, Dk Jack wrote:

> Hi Maxim,
> 
> I am sending the response in the request handler which I registered for
> 
> in the NGX_HTTP_SERVER_REWRITE_PHASE handler. In my handler, I have the

In a rewrite phase handler you are _not_ expected to return a 
response.  If you do return it, you have to be careful to properly 
cancel additional request processing.

Moreover, the server rewrite phase is _not_ executed for 
locations.  Instead, it is a phase for rewrites affecting the 
whole server block.  The configuration example you've provided 
makes no sense for a module which works in the server rewrite 
phase.

For returning a custom response in a specifically set location it 
might be better idea to use the content phase, or, even simplier, 
to register a location-specific content handler.  See empty gif 
module sources for a relatively simple example.

> following code to avoid responding multiple times as well. Still, I am getting
> 
> the error.
> 
>   if (r->main->count > 1)
>     return NGX_DECLINED;

This is not expected to prevent anything from being executed 
multiple times.  Rather, it will prevent your code from executing 
when there is more than one reference to the request.

You may want to read some guides on writing nginx modules, as it 
is more or less clear you don't understand basics.  In particular, 
Evan Miller's one might be a good start:

https://www.evanmiller.org/nginx-modules-guide.html

Refer to the Development Guide for more advanced subjects:

http://nginx.org/en/docs/dev/development_guide.html

-- 
Maxim Dounin
http://mdounin.ru/