From mboxrd@z Thu Jan 1 00:00:00 1970 X-Msuck: nntp://news.gmane.org/gmane.linux.lib.musl.general/8730 Path: news.gmane.org!not-for-mail From: Tim Hockin Newsgroups: gmane.linux.lib.musl.general Subject: Re: Re: Would love to see reconsideration for domain and search Date: Thu, 22 Oct 2015 23:04:20 -0700 Message-ID: References: <20151022215608.GA8645@brightrain.aerifal.cx> <20151023042720.GE8645@brightrain.aerifal.cx> <20151023053108.GG8645@brightrain.aerifal.cx> <20151023060005.GH8645@brightrain.aerifal.cx> Reply-To: musl@lists.openwall.com NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Trace: ger.gmane.org 1445580305 21477 80.91.229.3 (23 Oct 2015 06:05:05 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 23 Oct 2015 06:05:05 +0000 (UTC) To: musl@lists.openwall.com Original-X-From: musl-return-8743-gllmg-musl=m.gmane.org@lists.openwall.com Fri Oct 23 08:05:05 2015 Return-path: Envelope-to: gllmg-musl@m.gmane.org Original-Received: from mother.openwall.net ([195.42.179.200]) by plane.gmane.org with smtp (Exim 4.69) (envelope-from ) id 1ZpVTD-0006Wi-8F for gllmg-musl@m.gmane.org; Fri, 23 Oct 2015 08:04:55 +0200 Original-Received: (qmail 12212 invoked by uid 550); 23 Oct 2015 06:04:53 -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 12194 invoked from network); 23 Oct 2015 06:04:52 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :content-type; bh=566I8rAk3IuQ2H5PDFvY7gUGG53Kp5FzKztFlsQ1CUc=; b=jfDYw6KsSn1pdXgGul4LrsJy9ldWYYeXLU1NRixCGAwIUHXA+Bvxqqpm2ivDKr5tKI Y0vGXQJDy0Ol3G3K3+ct35q6gUePvt/YvgJhXaR220SZsnyKdkwdvQE+CnEL4cnRN7wm BcRFuEmr1JK9tsqGObzS0AwPzlMuCGk+JJvycBlL9w4FhRMw5raF/SJ0kUIXh5PDkSYt 1Tdc9FBrKrdzt66PhTkhQ6gE+b/F/cmPaGiFX4MO0jkfXaZvfcoC179ziS2jCwIRFcxr PLX11IFFvGZc4739w9SyBgmFXULF3TAc1Pkp2mH1G5d8piJm58fqPn8H/s0Q9ebh0P11 CV2Q== 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:from:date :message-id:subject:to:content-type; bh=566I8rAk3IuQ2H5PDFvY7gUGG53Kp5FzKztFlsQ1CUc=; b=WAmcQU7ng8u3PBSmieor71CuTyw17tuI6satvFbfnUE68Pt20E2rwKxcnqh34Iu22I 1CHkidjkAkFR6pH+lIGWu0J1b7UEAYlBraIFy93oZTMvOQ3EbduYVEt+uXgxLcEy7y2w HlWDTZYvURDchczeWf8QdkKIm55BfkV/qbkJuAHa4hZ7gLGapIOtRmq5vc1rJYfC1ue5 SiNiVIoLEsp7EQIcRF8NcSygn+UT6JuAUA9a6pRfrm1kDq4nEbtZLXMfbsmnYsgItjwY CxWTC3KD812AjbNbWid8g1R1/9n1jf6YimFSE+fM0UeW78uEucL/KOh4akxOdoNtSM55 6OVA== X-Gm-Message-State: ALoCoQn6wmPr1sdo/h94rkIWpI9OvpKolxozwrU3pRDx/crK68B/gaEClLN/let+BhV0wNQZ8FjQ X-Received: by 10.31.8.21 with SMTP id 21mr11845742vki.82.1445580280288; Thu, 22 Oct 2015 23:04:40 -0700 (PDT) In-Reply-To: <20151023060005.GH8645@brightrain.aerifal.cx> Xref: news.gmane.org gmane.linux.lib.musl.general:8730 Archived-At: On Thu, Oct 22, 2015 at 11:00 PM, Rich Felker wrote: > On Thu, Oct 22, 2015 at 10:37:53PM -0700, Tim Hockin wrote: >> I saw from a different thread that musl doesn't or didn't do TCP >> fallbacks - is that still the case? I know we need that for things >> like large multi-SRV sets (which I do not expect libc to support), and >> we have some people who have large A sets (which I do expect libc to >> support). > > Indeed. The only way you can overflow the UDP size limit with the > records the stub resolver uses is with a max-length CNAME pointing to > a max or near-max length record with little or no overlap to allow for > compression. Of course you might run out of space for all the address > results in other cases, but the truncated packet will still have > usable results. While I'm not aware of any official document to this > effect, for practical purposes you just have to avoid making names > that long. There are too many nameservers that don't do TCP at all, as > well as locked-down networks that don't allow TCP except on a few > specific ports, to be able to rely on doing DNS over TCP. Our case is exposing sets of fungible backends as a DNS name with multiple A records. Truncating the set will cause incorrect results for clients who need to discover the whole set. We can cross that bridge when we get there. > Naturally other non-stub-resolver things like zone transfers may need > TCP, but that's outside the domain of the stub resolver. Note that the > libc res_*/dn_*/ns_* APIs should be capable of working with longer > messages over TCP as long as you setup the socket and do the send/recv > yourself. > > Rich