[dev] http phase handler

[Igor Sysoev]

On Wed, Dec 05, 2007 at 06:32:23PM +0100, Manlio Perillo wrote:

> I'm interested in how HTTP phases handlers works in nginx.
> 
> I would like to add support, in mod_wsgi, to NGX_HTTP_PREACCESS_PHASE, 
> NGX_HTTP_ACCESS_PHASE and NGX_HTTP_CONTENT_PHASE.
> 
> I'm reading the sources but I'm not sure to understand how a phase 
> handler terminates.
> 
> With a request handler, the handler can return NGX_DONE and then call 
> ngx_http_finalize_request, but what about a phase handler?

All phase handlers should simpy return value
NGX_OK/NGX_DECLINED/NGX_HTTP_FORBIDDEN/etc.

In the context phase there may run a single defined content handler (perl,
proxy_pass, fastcgi_pass, memcached_pass, flv, empty_gif) or stack
of handlers: index, autoindex, dav, static.

If a defined handler calls finally ngx_http_finalize_request(NGX_DECLINED),
then nginx goes to the stack of handlers. Now only perl can do this.

The preaccess phase is for generic handlers:
on NGX_OK it goes to a next phase,
on NGX_DECLINED it goes to a next handler in the same phase,
on NGX_AGAIN/NGX_DONE it simply return,
on NGX_ERROR or NGX_HTTP_... it calls ngx_http_finalize_request()

The access phase is special to handle NGX_OK/NGX_DECLINED depending on
satisfy_any. However, I'm going to change it, because now:

     location / {
         satisfy_any  on;
         auth_basic ...
         # no allow/deny rules
     }

does not ask username/password.


-- 
Igor Sysoev
http://sysoev.ru/en/