[PATCH 16 of 20] Upstream: duplicate headers ignored or properly linked

[Sergey Kandaurov]

On Thu, Apr 21, 2022 at 01:18:56AM +0300, Maxim Dounin wrote:
> # HG changeset patch
> # User Maxim Dounin <mdounin at mdounin.ru>
> # Date 1650492338 -10800
> #      Thu Apr 21 01:05:38 2022 +0300
> # Node ID f460a2f9f88d264ef6c8588eb37bcb85c48010db
> # Parent  ab424b5e32405aeec54ccdfe38e9408209209e0a
> Upstream: duplicate headers ignored or properly linked.
> 
> Most of the known duplicate upstream response headers are now ignored
> with a warning.
> 
> If syntax permits multiple headers, these are now properly linked to
> the lists, notably Vary and WWW-Authenticate.  This makes it possible
> to further handle such lists where it makes sense.

This reminds me of curl deficiency to handle WWW-Authenticate
as a comma-separate multi-value header (which nginx doesn't emit though):
https://curl.se/mail/lib-2020-01/0064.html
https://curl.se/docs/knownbugs.html

> 
> diff --git a/src/http/ngx_http_upstream.c b/src/http/ngx_http_upstream.c
> --- a/src/http/ngx_http_upstream.c
> +++ b/src/http/ngx_http_upstream.c
> @@ -101,6 +101,9 @@ static void ngx_http_upstream_finalize_r
>  
>  static ngx_int_t ngx_http_upstream_process_header_line(ngx_http_request_t *r,
>      ngx_table_elt_t *h, ngx_uint_t offset);
> +static ngx_int_t
> +    ngx_http_upstream_process_multi_header_lines(ngx_http_request_t *r,
> +    ngx_table_elt_t *h, ngx_uint_t offset);

I'd suggest renaming this pair to ngx_http_upstream_process_header_line /
ngx_http_upstream_process_unique_header_line to be on par with functions
in ngx_http_request.c (and after the 7th renaming patch of this series).

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