[Bug 1633619] Re: dhclient -1 exits 0 when no lease found

[Steve Langasek]

Here is the behavior on either 14.04 or 16.04:

# dhclient -1 -v virbr0
Internet Systems Consortium DHCP Client 4.2.4
Copyright 2004-2012 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/

Listening on LPF/virbr0/52:54:00:05:e1:f3
Sending on   LPF/virbr0/52:54:00:05:e1:f3
Sending on   Socket/fallback
DHCPDISCOVER on virbr0 to 255.255.255.255 port 67 interval 3 (xid=0xe7ef8212)
DHCPDISCOVER on virbr0 to 255.255.255.255 port 67 interval 1 (xid=0xe7ef8212)
No DHCPOFFERS received.
No working leases in persistent database - sleeping.
# ps awxfu|grep dh.*virbr
root     16796  0.0  0.0   8868   792 pts/36   S+   05:31   0:00          |   |                   \_ grep dh.*virbr
root     16772  0.0  0.0  10220  4368 ?        Ss   05:30   0:00          \_ dhclient -1 -v virbr0
#

Not only does it not return the documented exit code, it also
backgrounds itself and continues polling.  So the -1 option seems to be
completely broken.

I've looked at the source package, and this is due to
debian/patches/onetry_retry_after_initial_success.  The addition of this
patch isn't documented in the changelog, there are no referenced bugs,
and the patch description doesn't make sense to me; assigning to
stgraber, who is listed as the author of this patch.

** Changed in: isc-dhcp (Ubuntu)
     Assignee: (unassigned) => Stéphane Graber (stgraber)

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https://bugs.launchpad.net/bugs/1633619

Title:
  dhclient -1 exits 0 when no lease found

Status in isc-dhcp package in Ubuntu:
  Confirmed

Bug description:
  I've tried this in containers of xenial, trusty and yakkety.

  i've created a lxc network that does not have dhcp4.

  See https://github.com/lxc/lxd/issues/2481 for some info on how to do
  that.

  Then, I launch an instance:

  $ lxc launch ubuntu-daily:xenial --profile=sm-test-profile2 x1
  % killall dhclient
  % dhclient -r eth0
  % dhclient -1 -v eth0
  Internet Systems Consortium DHCP Client 4.3.3
  Copyright 2004-2015 Internet Systems Consortium.
  All rights reserved.
  For info, please visit https://www.isc.org/software/dhcp/

  Listening on LPF/eth0/00:16:3e:b8:e6:70
  Sending on   LPF/eth0/00:16:3e:b8:e6:70
  Sending on   Socket/fallback
  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 3 (xid=0xc08cb53c)

  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 4 (xid=0xc08cb53c)
  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 9 (xid=0xc08cb53c)
  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 19 (xid=0xc08cb53c)
  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 7 (xid=0xc08cb53c)
  DHCPDISCOVER on eth0 to 255.255.255.255 port 67 interval 12 (xid=0xc08cb53c)
  ..
  No DHCPOFFERS received.
  No working leases in persistent database - sleeping.

  % echo $?
  0
  % ps axw | grep dhcl
    356 ?        Ss     0:00 dhclient -1 -v eth0

  
  the man page says of the '-1' option:
         -1     Try to get a lease once.  On  failure  exit  with  code  2.   In
                DHCPv6 this sets the maximum duration of the initial exchange to
                timeout (from dhclient.conf with a default of sixty seconds).

  ProblemType: Bug
  DistroRelease: Ubuntu 16.10
  Package: isc-dhcp-client 4.3.3-5ubuntu15
  ProcVersionSignature: Ubuntu 4.8.0-22.24-generic 4.8.0
  Uname: Linux 4.8.0-22-generic x86_64
  NonfreeKernelModules: zfs zunicode zcommon znvpair zavl
  ApportVersion: 2.20.3-0ubuntu8
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Fri Oct 14 16:59:45 2016
  DhclientLeases:

  EcryptfsInUse: Yes
  InstallationDate: Installed on 2015-07-23 (449 days ago)
  InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Alpha amd64 (20150722.1)
  SourcePackage: isc-dhcp
  UpgradeStatus: No upgrade log present (probably fresh install)

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