[jcifs] jcifs and dfs from UNIX host - STATUS_BAD_NETWORK_NAME

[Andrew Hale]

We are experiencing an issue with the jcifs client when trying to extract
data from a DFS share under the following circumstances:
We have a subdomain of sub.domain.com that has 40+ domain controllers.  Not
all domain controllers are hosting the DFS root (does not have local DFS
shares).  Only a subset of 10 or so do.  Accessing the domain based DFS
could potentially hit any of these 40 domain controllers from the client.
When the domain controller referred to the client by DNS does not host the
DFS root we encounter an error (more on the error below).  When the domain
controller referred to the client by DNS does host the DFS root everything
works as expected.  Since DNS can return any of the domain controllers this
results in inconsistent behavior.

Note I am about 80% sure that this is what is happening. The only way we
could test this was by modifying the hosts file and hardcoding the subdomain
to point to the different domain controllers directly.  I realize that this
is not a 100% replication of the entire live process but it supports my
theory.

Below is a chunk of a trace file from a failed attempt (referred to a domain
controller not hosting the DFS root):

1373 20:15:56 2011/5/3       32.919983           {TCP:41, IPv4:40}
130.226.187.2     130.226.185.3     SMB  SMB:C; Tree Connect Andx, Path =
\\sub.domain.com\IPC$ <file://sub.domain.com/IPC$>, Service = ?????
1374 20:15:56 2011/5/3       32.920355           {TCP:41, IPv4:40}
130.226.185.3     130.226.187.2     SMB  SMB:R; Tree Connect Andx, Service =
IPC
1375 20:15:56 2011/5/3       32.921955           {SMB:42, TCP:41,
IPv4:40}     130.226.187.2     130.226.185.3     DFS   DFS:Get DFS Referral
Request, FileName: <empty>, MaxReferralLevel: 3
1376 20:15:56 2011/5/3       32.922452           {SMB:42, TCP:41,
IPv4:40}     130.226.185.3     130.226.187.2     SMB  SMB:R;
InterimResponse; Transact2, Get Dfs Referral - NT Status: System - Warning,
Code = (5) STATUS_BUFFER_OVERFLOW
1377 20:15:56 2011/5/3       32.923334           {TCP:41, IPv4:40}
130.226.187.2     130.226.185.3     SMB  SMB:C; Tree Connect Andx, Path =
\\sub.domain.com\DFS <file://sub.domain.com/DFS>, Service = ?????
1378 20:15:56 2011/5/3       32.923697           {TCP:41, IPv4:40}
130.226.185.3     130.226.187.2     SMB  SMB:R; Tree Connect Andx - NT
Status: System - Error, Code = (204) STATUS_BAD_NETWORK_NAME

According to Microsoft Support, packet 1375 looks strange as the filename is
empty in the DFS referral request.  Then, the client apparently treats the
DFS path as a normal UNC path and receives a STATUS_BAD_NETWORK_NAME (packet
1377-78).

Again according to Microsoft support the filename for the first DFS referral
request should be populated with the domain name, something like "\
sub.domain.com" and the next should be the DFS root and so on...

Any ideas on something we may be doing wrong or some piece of configuration
we are missing?  Should jcifs be able to resolve DFS referrals on domain
controllers that do not necessarily host the DFS root?

Thanks,
Andrew
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