Subject: 28.0.50; dns-set-servers fails on IPv6 available Windows
From: Kazuhiro Ito <[email-masked]>
To: [email-masked]
Date: Tue, 31 Mar 2020 17:46:47 +0900
List-Id: <debbugs-submit.debbugs.gnu.org>

dns-set-servers function fails to set dns-servers on Windows with IPv6
available network.

(progn
  (require 'dns)
  (dns-set-servers)
  dns-servers)

-> (nil)

The reason is that Windows's nslookup program returns server's IPv6
address if availeble but dns-set-servers function assumes that
server's address is always IPv4.

> C:\>nslookup localhost
> サーバー:  server.lan
> Address:  xxxx:xxxx:xxxx::1
>
> 名前:    localhost.lan
> Addresses:  ::1
>           127.0.0.1

# "サーバー" and "名前" are Japanese translations for "Server" and
# "Name", respectively.

From dns-set-servers definition in lisp/net/dns.el

> (re-search-forward
>  "^Address:[ \t]*\\([0-9]+\\.[0-9]+\\.[0-9]+\\.[0-9]+\\)" nil t)

-- 
Kazuhiro Ito