Date: Fri, 23 Jul 2021 23:25:36 +0300 From: Yuri Kanivetsky <yuri.kanivetsky@...il.com> To: musl@...ts.openwall.com Cc: "Olivier A." <olivier.antoine@...il.com> Subject: Re: getaddrinfo() fails for domains with no AAAA records (regression?) Can you possibly provide some quotes from the RFCs? The closest I could find is: > QNAME=host3.example. QTYPE=A, QCLASS=IN > the answer will reflect "no error, but no data" > because there is no A RR set at '*.example.' https://datatracker.ietf.org/doc/html/rfc4592 And it's from an example. Also, all other software I could get my hands on (basically, glibc, I guess) ignores NXDOMAIN for AAAA RRs. On Tue, Jul 20, 2021 at 12:12 AM Rich Felker <dalias@...c.org> wrote: > > On Mon, Jul 19, 2021 at 11:07:21PM +0200, Olivier A. wrote: > > On 19/07/2021 14:58, Yuri Kanivetsky wrote: > > > [..] > > > > Hi, > > > > I notice that too. If both A and AAAA are sent and there is a > > response for A and NXDomain for AAAA > > > > musl-libc discard both results. It's the expected behaviour > > according to this commit: > > > > https://git.musl-libc.org/cgit/musl/commit/src/network/lookup_name.c?id=5cf1ac2443ad0dba263559a3fe043d929e0e5c4c > > > > And it conform to https://datatracker.ietf.org/doc/html/rfc8020 > > > > It's was not the case before Alpine-Linux 3.13 > > > > But I also notice that if the DNS reply ServFailed instead of > > NXDomain for AAAA request, musl-libc retry 10 times, return 'bad > > address' and do not fallback to return a A record. > > > > According to > > https://datatracker.ietf.org/doc/html/rfc4074#section-4.3 it's not > > expected. > > This behavior is necessary/mandatory to provide secure behavior under > DNSSEC. Otherwise a forged response (causing ServFail) would result in > a false answer returned to the application, indicating that only one > or the other exists, rather than the correct inconclusive answer. > > This is https://sourceware.org/bugzilla/show_bug.cgi?id=27929
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