[Bug 1104675] Re: Bad handling of multiple domainname options

[Chris Carlin]

Maybe tomorrow I'll look into pcap. Right now, though, I do have this to
share. I had turned on dhclient-script.debug and here was its contents
(I'm fudging these domain names):

Thu Jan 24 22:17:16 EST 2013: entering /sbin, dumping variables.
reason='PREINIT'
interface='eth0'
--------------------------
Thu Jan 24 22:17:21 EST 2013: entering /sbin, dumping variables.
reason='BOUND'
interface='eth0'
new_ip_address='192.168.0.107'
new_network_number='192.168.0.0'
new_subnet_mask='255.255.255.0'
new_broadcast_address='192.168.0.255'
new_routers='192.168.0.1'
new_domain_name='my.comhr.remote.net'
new_domain_name_servers='192.168.0.1'
old_ip_address='192.168.0.107'
old_network_number='192.168.0.0'
old_subnet_mask='255.255.255.0'
old_broadcast_address='192.168.0.255'
old_routers='192.168.0.1'
old_domain_name='my.comhr.remote.net'
old_domain_name_servers='192.168.0.1'
--------------------------

Based on this am I right to assume it's something inside dhclient and
not part of a Debian-contributed script in /etc/dhcp ?

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https://bugs.launchpad.net/bugs/1104675

Title:
  Bad handling of multiple domainname options

Status in “isc-dhcp” package in Ubuntu:
  New

Bug description:
  As far as I know, the dhcp standards do not allow for multiple
  Domainnames to be set through Option 15. My LInksys router doesn't
  care, though, and sends both the Domainname I gave it AND the
  Domainname my ISP gives it. Maybe this is non-standard, but it is what
  it is.

  isc-dhcp-client handles this in the worst possible way. It could
  choose one name or the other, or it could ignore both names when it
  sees the malfunction. Instead, it concatenates the names together,
  assuring that it ends up with an invalid name.

  From the below excerpt of dhcpdump I would end up with the domain name
  my.comhr.remote.com.

  OPTION:   6 (  4) DNS server                192.168.0.1
  OPTION:  15 ( 6) Domainname                my.com
  OPTION:  15 ( 13) Domainname                hr.remote.com
  ---------------------------------------------------------------------------

  In the end this gives me an invalid domain in search in resolv.conf.
  Ideally I'd end up with "search my.com hr.remote.com" there, but from
  scanning the scripts I can see how that wouldn't really work. Still,
  the concated domainname seems like a bad idea.

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