[Bug 1674273] Re: Resolver ignores ndots option

Wed Mar 22 13:44:16 UTC 2017

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: glibc (Ubuntu Xenial)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1674273

Title:
  Resolver ignores ndots option

Status in glibc package in Ubuntu:
  Confirmed
Status in linux package in Ubuntu:
  Confirmed
Status in glibc source package in Xenial:
  Confirmed
Status in linux source package in Xenial:
  Confirmed

Bug description:
  This is a re-report of
  https://bugs.launchpad.net/ubuntu/+source/linux/+bug/401202 since that
  one was apparently closed as no-fix simply because it was too old.

  This still occurs in xenial.

  Original description:
  Regardless of ndots option in /etc/resolv.conf, when NXDOMAIN is returned from the DNS server then resolver always try another attempt with the original name extended by what is in search option.
  For example, if you're looking for very.long.url.nowhere and there is a line "search ubuntu.com" in resolv.conf you will get addres of server very.long.url.nowhere.ubuntu.com if such exists. It is incorrect, it should occurs only for urls having less that ndots option dots in its name.

  My system is a standard Ubuntu Xenial desktop amd64 using network
  manager and the default configured Wired Connection 1 (i.e. DHCP).

  To reproduce:
  - sudo install /dev/fd/0 /etc/NetworkManager/dnsmasq.d/domain <<<'log-queries=extra'
  - sudo killall dnsmasq
  - ping some.long.non-existent.name
  - Watch /var/log/syslog

  In my case:
  Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 query[A] some.long.non-existent.name from 127.0.0.1
  Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 forwarded some.long.non-existent.name to 192.168.5.1
  Mar 20 23:19:22 eragon dnsmasq[27367]: 46 127.0.0.1/40646 reply some.long.non-existent.name is NXDOMAIN
  Mar 20 23:19:22 eragon dnsmasq[27367]: 47 127.0.0.1/52417 query[A] some.long.non-existent.name.sebunger.dnsalias.org from 127.0.0.1
  Mar 20 23:19:22 eragon dnsmasq[27367]: 47 127.0.0.1/52417 forwarded some.long.non-existent.name.sebunger.dnsalias.org to 192.168.5.1
  Mar 20 23:19:23 eragon dnsmasq[27367]: 47 127.0.0.1/52417 reply some.long.non-existent.name.sebunger.dnsalias.org is <CNAME>
  Mar 20 23:19:23 eragon dnsmasq[27367]: 47 127.0.0.1/52417 reply sebunger.dnsalias.org is 203.173.156.30

  My /etc/resolv.conf (which is a sym-link to ../run/resolvconf/resolv.conf
  # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
  #     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
  nameserver 127.0.1.1
  search sebunger.dnsalias.org
  options ndots:1

  (I added the options ndots with no effect)
  --- 
  ApportVersion: 2.20.1-0ubuntu2.5
  Architecture: amd64
  AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-id', '/dev/snd/by-path', '/dev/snd/pcmC1D0c', '/dev/snd/controlC1', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D2c', '/dev/snd/pcmC0D1c', '/dev/snd/pcmC0D1p', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/controlC0', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
  DistroRelease: Ubuntu 16.04
  EcryptfsInUse: Yes
  IwConfig:
   enp2s0    no wireless extensions.

   lo        no wireless extensions.
  MachineType: Gigabyte Technology Co., Ltd. GA-MA770-UD3
  NonfreeKernelModules: nvidia_uvm nvidia
  Package: linux (not installed)
  ProcFB:

  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-66-generic root=/dev/mapper/vg0-root ro rootdelay=120 quiet splash
  ProcVersionSignature: Ubuntu 4.4.0-66.87-generic 4.4.44
  PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
  RelatedPackageVersions:
   linux-restricted-modules-4.4.0-66-generic N/A
   linux-backports-modules-4.4.0-66-generic  N/A
   linux-firmware                            1.157.8
  RfKill:

  Tags:  xenial xenial
  Uname: Linux 4.4.0-66-generic x86_64
  UpgradeStatus: No upgrade log present (probably fresh install)
  UserGroups: adm audio cdrom dialout dip floppy kvm lpadmin plugdev sambashare ssh sudo users video
  _MarkForUpload: True
  dmi.bios.date: 06/12/2009
  dmi.bios.vendor: Award Software International, Inc.
  dmi.bios.version: FB
  dmi.board.name: GA-MA770-UD3
  dmi.board.vendor: Gigabyte Technology Co., Ltd.
  dmi.board.version: x.x
  dmi.chassis.type: 3
  dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
  dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrFB:bd06/12/2009:svnGigabyteTechnologyCo.,Ltd.:pnGA-MA770-UD3:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnGA-MA770-UD3:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
  dmi.product.name: GA-MA770-UD3
  dmi.sys.vendor: Gigabyte Technology Co., Ltd.

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