bug#46807: [website] return 404 with HTTP header 'Accept-Language: zh-CN, zh'

["pelzflorian (Florian Pelz)" <pelzflorian@pelzflorian.de>]

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Hello all,

On Mon, Mar 01, 2021 at 11:06:59AM +0100, Ludovic Courtès wrote:
> Florian, could it be that we’re not normalizing language tags
> appropriately?  Does that ring a bell?

The attached patch to maintenance.git fixes the remaining minor issue:
Now Accept-Language language codes get normalized, zh to zh-CN, so web
browsers requesting any kind of Chinese get the website in mainland
Chinese.  (This is a minor issue.  The only valid URL is /zh-CN/ since
my last patch to guix-artwork because I don’t know how to
rewrite/redirect URLs in nginx.)

The patch was tested on a berlin VM.

There is no copyright header in maintenance.git’s
hydra/nginx/berlin.scm so I did not add a copyright.  I hereby license
the patch CC0
<https://creativecommons.org/publicdomain/zero/1.0/legalcode>.

Shall I just push?  A reconfigure of berlin will be necessary but is
not urgent.

Regards,
Florian

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From: Florian Pelz <pelzflorian@pelzflorian.de>
Date: Thu, 4 Mar 2021 20:29:27 +0100
Content-Type: text/plain; charset=UTF-8
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Subject: [PATCH] nginx: berlin: Normalize Accept-Language language code zh to
 zh-CN.

Now web browsers requesting any kind of Chinese get the website in
mainland Chinese.

zh, zh-Hans, zh-Hans-CN all are synonymous with zh-CN now.

* hydra/nginx/berlin.scm (accept-languages): New procedure.
(%extra-content): Normalize $lang variable with it.
---
 hydra/nginx/berlin.scm | 27 ++++++++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/hydra/nginx/berlin.scm b/hydra/nginx/berlin.scm
index 85aaf38..4b9d297 100644
--- a/hydra/nginx/berlin.scm
+++ b/hydra/nginx/berlin.scm
@@ -995,12 +995,37 @@ PUBLISH-URL."
        (uri "~ /(.*)")
        (body (list "return 301 $scheme://guixwl.org/$1;"))))))))
 
+(define (accept-languages language-lists)
+  "Returns nginx configuration code to set up the $lang variable
+according to the Accept-Language header in the HTTP request.  The
+requesting user agent will be served the files at /$lang/some/url.
+Each list in LANGUAGE-LISTS starts with the $lang and is followed by
+synonymous IETF language tags that should be mapped to the same $lang."
+  (define (language-mappings language-list)
+    (define (language-mapping language)
+      (string-join (list "    "  language (car language-list) ";")))
+    (string-join (map language-mapping language-list) "\n"))
+
+  (let ((directives
+         `(,(string-join
+             `("set_from_accept_language $lang_unmapped"
+               ,@(map string-join language-lists)
+               ";"))
+           "map $lang_unmapped $lang {"
+           ,@(map language-mappings language-lists)
+           "}")))
+    (string-join directives "\n")))
+
 (define %extra-content
   (list
    "default_type  application/octet-stream;"
    "sendfile        on;"
 
-   "set_from_accept_language $lang en de es fr zh-CN;"
+   (accept-languages '(("en")
+                       ("de")
+                       ("es")
+                       ("fr")
+                       ("zh-CN" "zh" "zh-Hans" "zh-Hans-CN")))
 
    ;; Maximum chunk size to send.  Partly this is a workaround for
    ;; <http://bugs.gnu.org/19939>, but also the nginx docs mention that
-- 
2.30.1