touch-packages team mailing list archive

[Ketil <1466608@xxxxxxxxxxxxxxxxxx>]

Thanks, I was hoping for some help to find the right place to report
this.

I poked around some more, and I found out what the problem was. First of
all, my wireless router was confused. I rebooted it, and then everything
started working again.

I did some debugging before I rebooted it, though, and the reason for
the partial failure situation was that EDNS0 wasn't specified in the
queries sent by Ubuntu, but dig specifies it by default (as well as the
AD flag, but I don't think that's relevant). A partial result should
have been given by the DNS server (on the wireless router), or it should
have truncated the reply to force a TCP retry by the client. (Now that
everything works, it trims down the Additional section to fit the
response.) To confirm, I ran dig like this, and these queries failed on
my confused router:

dig +noedns +noadflag @127.0.1.1 www.sciencedaily.com

So if Ubuntu had in fact set EDNS0 in the query, it would have worked.
Falling back to TCP presumably wasn't an option since no
malformed/truncated result was received first.

Feel free to close this issue if my router's behaviour was completely
unacceptable and should cause failure on the client side. If it ought to
have been handled better by Ubuntu, however, this may have been an
interesting corner case for debugging.

Let me know if you need anything else.

-- 
You received this bug notification because you are a member of Ubuntu
Touch seeded packages, which is subscribed to dnsmasq in Ubuntu.
https://bugs.launchpad.net/bugs/1466608

Title:
  Unable to resolve domains with large EDNS0 replies

Status in dnsmasq package in Ubuntu:
  New

Bug description:
  Not sure resolvconf is the correct place to report this bug, but I'm
  unable to resolve domains with large EDNS0 replies.

  A couple of examples are www.sciencedaily.com and
  www.ncbi.nlm.nih.gov. Interestingly, they resolve when I use "dig
  <domain>", but if I enter a URL with either of those domains in my
  browser (tried Chromium and Firefox), then name resolution fails. Ping
  also fails with a name resolution error message.

  Here's an example:

  $ dig www.ncbi.nlm.nih.gov

  ; <<>> DiG 9.9.5-3ubuntu0.2-Ubuntu <<>> www.ncbi.nlm.nih.gov
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 8409
  ;; flags: qr rd ra ad; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 1

  ;; OPT PSEUDOSECTION:
  ; EDNS: version: 0, flags: do; udp: 1280
  ;; QUESTION SECTION:
  ;www.ncbi.nlm.nih.gov.		IN	A

  ;; ANSWER SECTION:
  www.ncbi.nlm.nih.gov.	2358	IN	CNAME	www.wip.ncbi.nlm.nih.gov.
  www.ncbi.nlm.nih.gov.	2358	IN	RRSIG	CNAME 7 5 86400 20151213102025 20150616102025 52670 ncbi.nlm.nih.gov. dZt9uuyLImbB23vdqcsSK+nWK77BREttiAP80Ovq2/xV48JsII3Uxzxc W8OkLmc5dSdPNkfwc6QFC/+wqe+4ORb1TC4Qxw5HQxo4nCindPFGZAgJ SEFcWRJ2HrU5BKz/MeVMALJ3YN6LSHIwkTIwJbKweTGLQTZPZTryp1M7 UQrqd0hs7tjjwVl/6zRIA5UGgFbdrLwX9jmh4ykBTqK8u0Rt/wrTeHbp UpVMxAUdUW1CJ7xAnn/k4td6zdx7Tm5+CkS99Qva0cPfSSo6Qh4Uplun LKwT9GR4zqBTQRjBWSTf2YdhrAU8oyh9WbQ66WHLYkC8Kp55iskL8E8p E5wOYA==
  www.wip.ncbi.nlm.nih.gov. 30	IN	A	130.14.29.110
  www.wip.ncbi.nlm.nih.gov. 30	IN	RRSIG	A 7 6 30 20150708223631 20150617223631 34334 wip.ncbi.nlm.nih.gov. aF9abjtGNMz+8NkcTGIY8GwjfZBCcL532B2sdJM891OAP2V9GwPCDGNY VzMPzZjMGN9qHsBgXuFY5jZQNWFvWfIQctTJEZTxClyJyFhe5JbyIspg NIO6ZXxjD3h7Ax/Sr5peyf8mfCU/8FZHPGJOhsNEFOwL3RjIddTK6Ibc PQ55CWOuVrvw26kKj9gxBG8r6iBcKe89xHQYPm1w+Osp8c2twGhqBmfd 7zcRxFLyF0BpY63kcQiF5lJ2fI31x+zCAROL9H3L1jm/K7aMAiO5kuWl DK57upsmtQNzjWX8coYpm7/3Gebfmpjx4BtC75L5IP/WfwVBfzHeRjAG KY/7aQ==

  ;; Query time: 132 msec
  ;; SERVER: 127.0.1.1#53(127.0.1.1)
  ;; WHEN: Thu Jun 18 20:26:50 CEST 2015
  ;; MSG SIZE  rcvd: 699

  $ ping www.ncbi.nlm.nih.gov
  ping: unknown host www.ncbi.nlm.nih.gov

  I also watched with tcpdump when trying to look up the domain
  www.sciencedaily.com, and when I use dig I immediately get the reply,
  but when trying with ping I don't get any reply, and it gives up after
  4 queries are sent. Must have something to do with the DNS flags that
  are set on the query in the different cases.

  Here's a lookup with dig:

  20:01:47.857269 IP 127.0.0.1.56927 > 127.0.1.1.53: 9907+ [1au] A? www.sciencedaily.com. (49)
  20:01:47.869516 IP 127.0.1.1.53 > 127.0.0.1.56927: 9907 2/6/43 CNAME ed5n3.x.incapdns.net., A 149.126.72.70 (879)

  and here's a name resolution triggered by running ping:

  20:02:47.969527 IP 127.0.0.1.35905 > 127.0.1.1.53: 59118+ A? www.sciencedaily.com. (38)
  20:02:52.974752 IP 127.0.0.1.35905 > 127.0.1.1.53: 59118+ A? www.sciencedaily.com. (38)
  20:02:57.980296 IP 127.0.0.1.48738 > 127.0.1.1.53: 3668+ A? www.sciencedaily.com. (38)
  20:03:02.985493 IP 127.0.0.1.48738 > 127.0.1.1.53: 3668+ A? www.sciencedaily.com. (38)

  I've not experienced this before, though these aren't domains I
  commonly visit. Is this a new issue?

  ProblemType: Bug
  DistroRelease: Ubuntu 14.04
  Package: resolvconf 1.69ubuntu1.1
  ProcVersionSignature: Ubuntu 3.13.0-52.86-generic 3.13.11-ckt18
  Uname: Linux 3.13.0-52-generic x86_64
  ApportVersion: 2.14.1-0ubuntu3.11
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Thu Jun 18 20:23:19 2015
  InstallationDate: Installed on 2014-10-19 (241 days ago)
  InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
  PackageArchitecture: all
  SourcePackage: resolvconf
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/dnsmasq/+bug/1466608/+subscriptions