From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/4307 Path: news.gmane.org!not-for-mail From: Justin Cormack Newsgroups: gmane.linux.lib.musl.general Subject: Re: IPv4 and IPv6 addresses in resolv.conf Date: Sat, 30 Nov 2013 09:16:54 +0000 Message-ID: References: <761df492-c2ee-41d5-84f8-faef313164bf@email.android.com> <20131129174410.GD24286@brightrain.aerifal.cx> <20131130003704.GL24286@brightrain.aerifal.cx> <20131130031744.GM24286@brightrain.aerifal.cx> <20131130035116.GO24286@brightrain.aerifal.cx> <20131130035912.GP24286@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: multipart/alternative; boundary=047d7bdc9a4863c51504ec61689c X-Trace: ger.gmane.org 1385803021 26088 80.91.229.3 (30 Nov 2013 09:17:01 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sat, 30 Nov 2013 09:17:01 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-4311-gllmg-musl=m.gmane.org@lists.openwall.com Sat Nov 30 10:17:08 2013 Return-path: Envelope-to: gllmg-musl@plane.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1Vmgfj-0004zb-TJ for gllmg-musl@plane.gmane.org; Sat, 30 Nov 2013 10:17:07 +0100 Original-Received: (qmail 24091 invoked by uid 550); 30 Nov 2013 09:17:07 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Original-Received: (qmail 24081 invoked from network); 30 Nov 2013 09:17:06 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=specialbusservice.com; s=google; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; bh=p2zZHiGODMwsCz+9GCwXrugAG7gAdbWsZZsjzn+/n2Y=; b=Ua1NQ5r1bVJoUfAhujVA2YVwdHz8VKHChW/To/8twdDWg64a0mae4cbPDQ4INkgj0q X8qfDAcc3Eh10c9+JMO1iRKxvRns+stcKR9VLGqQ30+qLNa5yfyLYIeYXPSbCJKF9m4V o1iLf7Ifcs4qTj5MLe0oJCH8IVRitJ6u5jiNE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=p2zZHiGODMwsCz+9GCwXrugAG7gAdbWsZZsjzn+/n2Y=; b=R8BooAtar8UOa/HN9cxYNXnBxmfJC6zR9WiNAHIO/zSQ6xayxzo9F4bDqi4n/BAjlc uECXRzi/OAtGc//j3uL98TyCTc6RrSahyjILjaJtsQE9AVRouUhnOpB2iovIVJu7Yzgz YlL618yiowbirp00WtnzCBNAjkpknA8u4gNWOSGBlC2Kxlh2zHVsjhdJps9a6hwQBNJY C2RGgqYE9sWtRGNJXGZlNQ74JExz1lWAJAtffbnAVGkWxjfljMKRj6RB5Q+WEdCkf0EK ktfVwl04dWGWgIAe/XzWq3mY49Gy1pjOYIEVXslI8BDcCpiTKoYoz7F3iBZURUaNzpDH 1PiA== X-Gm-Message-State: ALoCoQlHZWw+7gPmqaIeZhguYGRy0LRNebf+I9vpJqMX1ONmTSuLqvXIlPXUJyFICcjS6TB0mcP4 X-Received: by 10.66.170.168 with SMTP id an8mr57336036pac.58.1385803014186; Sat, 30 Nov 2013 01:16:54 -0800 (PST) In-Reply-To: <20131130035912.GP24286@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:4307 Archived-At: --047d7bdc9a4863c51504ec61689c Content-Type: text/plain; charset=UTF-8 On 30 Nov 2013 03:59, "Rich Felker" wrote: > > On Fri, Nov 29, 2013 at 10:51:16PM -0500, Rich Felker wrote: > > On Fri, Nov 29, 2013 at 10:45:26PM -0500, Strake wrote: > > > On 29/11/2013, Rich Felker wrote: > > > > But that would mean complete unconditional DNS failure on systems > > > > lacking IPv6. > > > > > > We could do so iff system has IPv6. Switching on whether system has > > > IPv6 rather than whether resolv.conf has any IPv6 nameservers means > > > * no check whether resolv.conf includes v6 server > > > * that adding a v6 server to resolv.conf can not break DNS even on > > > systems lacking v6 > > > which seems saner. > > > > OK, so how do we detect if the system "has IPv6"? I don't think it's > > BTW, short of an answer to this question, I think the approach I > already suggested is rather safe. I can't imagine how an IPv6 > nameserver address would end up in resolv.conf on a system completely > lacking IPv6 support at the kernel level. > I can imagine how it got there eg if you have a standard config or you compile a new kernel and omit ipv6... --047d7bdc9a4863c51504ec61689c Content-Type: text/html; charset=UTF-8


On 30 Nov 2013 03:59, "Rich Felker" <dalias@aerifal.cx> wrote:
>
> On Fri, Nov 29, 2013 at 10:51:16PM -0500, Rich Felker wrote:
> > On Fri, Nov 29, 2013 at 10:45:26PM -0500, Strake wrote:
> > > On 29/11/2013, Rich Felker <dalias@aerifal.cx> wrote:
> > > > But that would mean complete unconditional DNS failure on systems
> > > > lacking IPv6.
> > >
> > > We could do so iff system has IPv6. Switching on whether system has
> > > IPv6 rather than whether resolv.conf has any IPv6 nameservers means
> > > * no check whether resolv.conf includes v6 server
> > > * that adding a v6 server to resolv.conf can not break DNS even on
> > > systems lacking v6
> > > which seems saner.
> >
> > OK, so how do we detect if the system "has IPv6"? I don't think it's
>
> BTW, short of an answer to this question, I think the approach I
> already suggested is rather safe. I can't imagine how an IPv6
> nameserver address would end up in resolv.conf on a system completely
> lacking IPv6 support at the kernel level.
>

I can imagine how it got there eg if you have a standard config or you compile a new kernel and omit ipv6...

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