From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-3.3 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 25573 invoked from network); 5 Jun 2022 18:48:18 -0000 Received: from mother.openwall.net (195.42.179.200) by inbox.vuxu.org with ESMTPUTF8; 5 Jun 2022 18:48:18 -0000 Received: (qmail 11719 invoked by uid 550); 5 Jun 2022 18:48:13 -0000 Mailing-List: contact musl-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Reply-To: musl@lists.openwall.com Received: (qmail 11687 invoked from network); 5 Jun 2022 18:48:12 -0000 Date: Sun, 5 Jun 2022 14:47:59 -0400 From: Rich Felker To: Sascha Braun Cc: musl@lists.openwall.com Message-ID: <20220605184759.GC7074@brightrain.aerifal.cx> References: <20220601141453.GW7074@brightrain.aerifal.cx> <20220601213022.GX7074@brightrain.aerifal.cx> <20220602142504.GY7074@brightrain.aerifal.cx> <20220603122704.GZ7074@brightrain.aerifal.cx> <20220603123437.GA7074@brightrain.aerifal.cx> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Subject: Re: [musl] Problably Issue in name_from_dns // __res_msend_rc (lookup_name.c) On Sun, Jun 05, 2022 at 08:14:49PM +0200, Sascha Braun wrote: > Hi Rich, >=20 > I tested your patch against my new (high res clock_realtime 100nsec) and = my > old (low res 1msec) code and in both cases it's working, no more problems. Great! Thanks for following up. I'll include the patch upstream. Rich > Am Fr., 3. Juni 2022 um 14:34 Uhr schrieb Rich Felker : >=20 > > On Fri, Jun 03, 2022 at 08:27:04AM -0400, Rich Felker wrote: > > > On Fri, Jun 03, 2022 at 12:28:40AM +0200, Sascha Braun wrote: > > > > Hi Rich, > > > > > > > > I think I narrowed the thing down. Below is a dump of what happens = in a > > > > 'normal' situation and what happened when the sporadic issue appear= ed.. > > > > > > > > Normal: > > > > begin lookup3... > > > > __syscall_send_internal 020000350808040400000000000000008.8.4.4:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d0000010001 > > > > __syscall_send_internal 02000035d043dede00000000000000 > > 00208.67.222.222:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d0000010001 > > > > __syscall_send_internal 020000350909090900000000000000009.9.9.9:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d0000010001 > > > > __syscall_send_internal 020000350808040400000000000000008.8.4.4:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d00001c0001 > > > > __syscall_send_internal 02000035d043dede00000000000000 > > 00208.67.222.222:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d00001c0001 > > > > __syscall_send_internal 020000350909090900000000000000009.9.9.9:53] > > > > ecea010000010000000000000377777706676f6f676c6503636f6d00001c0001 > > > > __syscall_recv begin EP[0.0.0.0:0] > > > > __syscall_recv'd_internal [020000000000000000000000000000009.9.9.9:= 53] > > > > > > ecea818000010001000000000377777706676f6f676c6503636f6d0000010001c00c000= 10001000000390004d83ad48400000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 00000000000000000000000000000000000000000000000000000 > > > > __syscall_recv begin EP[9.9.9.9:53] > > > > __syscall_recv'd_internal [020000350909090900000000000000009.9.9.9:= 53] > > > > > > ecea818000010001000000000377777706676f6f676c6503636f6d00001c0001c00c001= c00010000003400102a00145040010808000000000000200400000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 00000000000000000000000000000000000000000000000000000 > > > > connect:0200ffffd83ad4840000000000000000 > > > > connect:0a00ffff000000002a00145040010808000000000000200400000000 > > > > > > > > So we did sent the bytes > > > > ecea010000010000000000000377777706676f6f676c6503636f6d0000010001 and > > the > > > > other sequence (hex encoded, 2 characters per byte) to each of the = DNS > > and > > > > we received back one 'short' and one 'long' reply from 9.9.9.9. > > > > I guess the short one is IPv4, long one IPv6(?). That's the case wi= th > > all > > > > successful lookups, i.e. the 99% ok ones - (at least) one short - (= at > > > > least) one long. > > > > > > > > Now the problematic one: > > > > > > > > begin lookup1... > > > > __syscall_send_internal 020000350808040400000000000000008.8.4.4:53] > > > > 94d90100000100000000000003777777037765620264650000010001 > > > > __syscall_send_internal 02000035d043dede00000000000000 > > 00208.67.222.222:53] > > > > 94d90100000100000000000003777777037765620264650000010001 > > > > __syscall_send_internal 020000350909090900000000000000009.9.9.9:53] > > > > 94d90100000100000000000003777777037765620264650000010001 > > > > __syscall_send_internal 020000350808040400000000000000008.8.4.4:53] > > > > 94d901000001000000000000037777770377656202646500001c0001 > > > > __syscall_send_internal 02000035d043dede00000000000000 > > 00208.67.222.222:53] > > > > 94d901000001000000000000037777770377656202646500001c0001 > > > > __syscall_send_internal 020000350909090900000000000000009.9.9.9:53] > > > > 94d901000001000000000000037777770377656202646500001c0001 > > > > > > > > __syscall_recv begin EP[0.0.0.0:0] > > > > __syscall_recv'd_internal [020000000000000000000000000000009.9.9.9:= 53] > > > > > > 94d981800001000100010000037777770377656202646500001c0001c00c00050001000= 0004e000f0377777708672d68612d776562c014c02c00060001000000340031036e73310270= 6f0675692d646e73c0140a686f73746d6173746572c04378860f1200002a3000000e1000093= a800000003c0000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 00000000000000000000000000000000000000000000000000000 > > > > __syscall_recv begin EP[9.9.9.9:53] > > > > __syscall_recv'd_internal [020000350909090900000000000000008.8.4.4:= 53] > > > > > > 94d981800001000100010000037777770377656202646500001c0001c00c00050001000= 00114000f0377777708672d68612d776562c014c02c000600010000002c0031036e73310270= 6f0675692d646e73c0140a686f73746d6173746572c04378860f1200002a3000000e1000093= a800000003c0000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 000000000000000000000000000000000000000000000000000000000000000000000000000= 00000000000000000000000000000000000000000000000000000 > > > > getaddrinfo1: Address in use > > > > > > > > We received two 'long' responses, one from 9.9.9.9; one from 8.8.4.4 > > > > > > > > All occurrences of the problem show this constellation - two 'long' > > > > responses received. > > > > As a note, of course my implementation of recv returns the correct > > number > > > > of bytes received. The zeros you see are only from the dump functio= n, > > it's > > > > dumping the 512 byte buffer. > > > > > > > > I hope this is helpful in some manner. > > > > > > > > I came across this, I seems glibc had a similar issue (I did not lo= ok > > > > in-depth, just want to share the link) > > > > https://bugzilla.redhat.com/show_bug.cgi?id=3D1044628 > > > > https://sourceware.org/legacy-ml/libc-alpha/2014-04/msg00321.html > > > > > > OK, I found your problem. It's that the query ids for both the A and > > > AAAA are the same, probably because you have a low-resolution or > > > non-working clock_gettime. If the host environment does not provide a > > > way to get a high resolution clock, I think you should still apply a > > > monotonic increasing increment of the nanoseconds on each call where > > > the host environment's time did not increase so that the clock is > > > strictly monotonic. However musl's resolver should also deal with this > > > case since it's always possible to get identical query ids (with low > > > probability). We should just check if they're equal, and if so, > > > increment the second one. I'll write a patch to do this. > > > > See if the attached patch fixes it. > > > >