res_send() doesn't work with osquery enabled

Corinna Vinschen
Thu Aug 26 16:38:00 GMT 2010

Pierre, would you mind to take a look?

On Aug 26 19:07, wrote:
> Currently res_init() checks for availability of the native windows
> function DnsQuery_A. If the function is found, it's preferred over the
> cygwin implementation and res_query is set up to use it.
> As DnsQuery_A finds the configured name servers itself, the current code
> assumes we can avoid loading the dns server list with GetNetworkParams().
> However, the assumption that everybody would use res_query is wrong. Some
> programs may use res_mkquery() and res_send() or may only read the list of
> servers from _res.nsaddr_list and send/receive the queries/replies
> themselves. res_send() also relies on nsaddr_list.
> The following patch makes get_dns_info() always try to populate
> nsaddr_list if empty. If resolv.conf exists and provides nameservers, they
> will be used as usual. Otherwise, GetNetworkParams() will be called to get
> the servers from the operating system.
> 2010-08-26  Rumen Stoyanov <>
>      * libc/minires-os-if.c (get_dns_info): Always populate nsaddr_list
>      if empty, regardless of the availability of os_query.
>      * libc/minires.c (res_nsend): Make sure there is atleast one
>      nameserver in nsaddr_list or return.


Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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