# Ngx\_http\_send\_special\_response **URL:** \ **Category:** NGINX\ **Created:** [April 16, 2012, 10:54am UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926 "2012-04-16T10:54:23Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Gurdipe\_D](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/g/b77776/32.png) [@Gurdipe\_D](https://www.ruby-forum.com/u/Gurdipe_D)\ **Post date:** [April 16, 2012, 10:54am UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/1 "2012-04-16T10:54:23Z")
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? 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? 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? 1. Can you explain please the different between a. r-\>headers\_out.content\_length\_n b. r-\>headers\_out.content\_length 2. Can you explain the usage of the hash field in ngx\_table\_elt\_t Thanks Hagai A. ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 12:38pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/2 "2012-04-16T12:38:08Z")
Hello! On Mon, Apr 16, 2012 at 01:53:39AM -0700, hagai avrahami wrote: > 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? > > 1. 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). > 1. 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 D. ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 1:29pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/3 "2012-04-16T13:29:41Z")
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) Thanks Hagai ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 3:39pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/4 "2012-04-16T15:39:01Z")
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 D. > > To: [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > > > > > > > > that’s probably what confused you. > > should set when generating response in nginx. The content\_length > > header). > > > > Maxim D. > > > > * * * > > > > nginx mailing list > > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) > > [mailman.nginx.org archive](http://mailman.nginx.org/mailman/listinfo/nginx) ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 5:15pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/5 "2012-04-16T17:15:21Z")
Hi Thanks The redirect response is from content handler context. Using the code you added cause Nginx to send back the Error Page (302) with Content-Length and Content-Type (“test/html”) (And I am trying avoid that) without Body That’s why I assumed using r-\>header\_only = 1 will solve my problem but as you explained it is used for other cases. please see that in ngx\_http\_send\_special\_response when this flag set to 1 the Header is set with this fields but no body in response (I think this is not a good result) if adding in the beginning of the function (ngx\_http\_send\_special\_response) the following code it solves the problem: if (r-\>header\_only == 1) { ngx\_http\_clear\_accept\_ranges®; ngx\_http\_clear\_last\_modified®; rc = ngx\_http\_send\_header®; return rc; } Is there any other way I can avoid content length and content-type in 302 response Thanks Hagai ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 5:58pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/6 "2012-04-16T17:58:08Z")
Hello! On Mon, Apr 16, 2012 at 08:14:25AM -0700, hagai avrahami wrote: > Hi > Thanks > > The redirect response is from content handler context. > > Using the code you added > > cause Nginx to send back the Error Page (302) with > Content-Length and Content-Type (“test/html”) (And I am trying > avoid that) without Body Ah, sorry, I missed you want to send 302 with an empty body, not just 302. Then instead of ``` return NGX_HTTP_MOVED_TEMPORARY; ``` you have to send actual response youself, like this: ``` r->headers_out.status = NGX_HTTP_MOVED_TEMPORARY; r->headers_out.content_length_n = 0; rc = ngx_http_send_header(r); if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) { return rc; } return ngx_http_send_special(r, NGX_HTTP_LAST); ``` Maxim D. ---
**Author:** ![hagai\_avrahami](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/e47c2d/32.png) [@hagai\_avrahami](https://www.ruby-forum.com/u/hagai_avrahami)\ **Post date:** [April 16, 2012, 6:28pm UTC](https://www.ruby-forum.com/t/ngx-http-send-special-response/218926/7 "2012-04-16T18:28:33Z")
Thanks!