ngx_http_send_special_response

[Maxim Dounin]

Hello!

On Mon, Apr 16, 2012 at 04:29:18AM -0700, hagai avrahami wrote:

> WOW thanks for the quick and elaborate response
> 
> So what is the right way to send response with status code 302 on GET request but
> with content length 0 and no body (I want to redirect the request to other Server)

Easiest solution is to just write

    return 302 $where;

in config. :)

>From the code point of view (assuming content handler context), 
something like this should work:

    ngx_table_elt_t  *h;

    ngx_http_clear_location(r);

    h = ngx_list_push(&r->headers_out.headers);
    if (h == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    h->hash = 1;
    ngx_str_set(&h->key, "Location");

    h->value.data = ...
    h->value.len = ...

    r->headers_out.location = h;

    return NGX_HTTP_MOVED_TEMPORARILY;

Maxim Dounin


> 
> Thanks 
> 
> Hagai
> 
> 
> 
> 
> >________________________________
> > From: Maxim Dounin <mdounin at mdounin.ru>
> >To: nginx at nginx.org 
> >Sent: Monday, April 16, 2012 12:37 PM
> >Subject: Re: ngx_http_send_special_response
> > 
> >Hello!
> >
> >On Mon, Apr 16, 2012 at 01:53:39AM -0700, hagai avrahami wrote:
> >
> >> 
> >> 
> >> Hi
> >> 
> >> I am appreciate any help I can get on the following issues.
> >> 
> >> I am writing my own module.
> >> 
> >> 1. I can see in function ngx_http_send_special_response
> >>     that it calculates the content length of the error page even if the request signed as header only (r->header_only = 1)
> >>     and set the content length header with value, after sending the header it does not send the body ( because  r->header_only = 1)
> >>     so the response arrive with content length different than 0 but without body 
> >> 
> >>     Is it a BUG?
> >
> >No.  The r->header_only flag should is set when body isn't 
> >expected per protocol (HEAD requests, 304 responses).  Having 
> >Content-Length present in such responses is ok.
> >
> >> 2.In the module I am trying to redirect the request with status code 302 (NGX_HTTP_MOVED_TEMPORARILY)
> >>    Trying to user->headers_out.location for the Alternate URL failed, I looked in the code and saw the Location must start with "/" - why?
> >
> >You have to set it correctly, i.e. add to r->headers_out.headers 
> >and link to r->headers_out.location.  If it starts with "/" it 
> >works even if set incorrectly due to adding of a server_name, 
> >that's probably what confused you.
> >
> >>    In the end I add it to r->headers_out.headers
> >>    using header = ngx_list_push(&r->headers_out.headers);
> >>    Is it the write way to do it?
> >> 
> >> 3. Can you explain please the different between
> >>     a. r->headers_out.content_length_n
> >>     b. r->headers_out.content_length
> >
> >The content_length_n is a numeric length, this what you normaly 
> >should set when generating response in nginx.  The content_length 
> >is a pointer to a headers array element, it might be present if 
> >there is string representation of a Content-Length header 
> >available for some reason (e.g. from a backend).
> >
> >> 4. Can you explain the usage of the hash field in ngx_table_elt_t
> >
> >Normally the hash field is used for fast lookups in hash 
> >structures.  In case of r->headers_out it's usually just set to 1 
> >indicate the header is valid (or reset to 0 to indicate the 
> >header should not be sent as it was superseeded by some other 
> >header).
> >
> >Maxim Dounin
> >
> >_______________________________________________
> >nginx mailing list
> >nginx at nginx.org
> >http://mailman.nginx.org/mailman/listinfo/nginx
> >
> >

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